【作者】 李亚东；

【导师】 曹少魁；

【作者基本信息】 郑州大学 ， 有机高分子材料， 2005， 博士

【摘要】 北宋东京城,人口逾百万,是当时世界东方的大都市。其城市布局,既受“象天设都”、勘舆学这些规划思想的影响,又受历史、地理等客观条件的制约,具有多元性与复杂性。 北宋东京由外城、内城、皇城与宫城四重城垣组成,将中国古代“内城外廓”的城池结构发展到极致。宋外城周长48里233步,作为拱卫京师的首道屏障,筑有瓮城、马面、战棚等防御设施,是北宋“守内虚外”国策的重要体现。文章对有关宋外城的考古资料予以解说,并探讨了外城门与拐子城的形制等问题。宋内城,周长20里155步,为京师开封的第二道屏障,并对城市内部空间具有分隔与界定的作用。对于宋皇宫,文章一反“宋皇宫一城五里说”、“宋无宫城说”、“宋皇城七里说”、“宋皇宫加延福宫九里说”等观点,认为宋皇宫分为皇宫二城,皇城周长九里十三步,宫城周长五里,前者从东、南、两三面环卫后者。宋皇、宫二城的范围,与古人视“九五”为尊位有关。《周易·乾卦》曰:“九五,飞龙在天,利见大人。”龙是帝王的化身,故“九五”为帝王之数,象征等级之最,不可僭越。 宋东京城内,有汴河、蔡河、五丈河、金水河四河贯城,是各地贡赋物质漕运京师的通道,被视作东京的生命线。尤其是汴河,其沿岸邸店、酒楼、商业行市众多,是东京经济繁荣的集中体现,并对附近街市具有辐射力。由于诸河流走向的不规则性,致使宋东京的里坊布局,街道分布,难以像隋唐长安城那样整齐划一,呈现出城市空间格局上的灵活性。 宋东京街道,作为一种城市纹理,为混合式,以棋盘状为主,附以环形与斜线,这标志着隋唐时期规整的方格网状城市空间格局的终结。城内屡禁不止的侵街现象,是里坊制崩溃的原因与体现。关于其崩溃的时间,日本学者加藤繁先生认为是在北宋末年。事实上,早在五代后周时期,东京街道两侧允许种树、掘井、修盖凉棚,已播下了里坊制解体的种子。入宋以后,屡禁不止的侵街行为,促进了种子的发芽、生长。发展到仁宗景祐年间,政府允许临街开设邸店,随之,坊墙拆除了,至此里坊制彻底崩溃。并且,其崩溃过程,亦非从坊墙的倒塌开始,而是由侵街行为以发其端,待发展到政府因无力制止而予以承认时,坊墙这一坊制的外壳随之消失。也就是说,坊墙与墙外的侵街建筑,曾共存过相当时间。 街道既是构成城区的框架,具有交通功能,也是人们观光、交谈的场所,其景观更是人们对城市形象最直接、最便捷的感受。在以隋唐长安城为典型的里坊制度下,街道两侧以坊墙围合,是一种单调、死板的景象。而宋东京城,随着街市制的形成,邸店、商铺沿街而立,人流、物流充斥其间,呈现出前所未有的活泼、多彩的街道景观。这种景观,有助于人们由必要性活动向自发性和社会性活动转变。 北宋东京的厢坊制,是随着城市人口的增加,商品经济的繁荣而出现的新型管理体制,也可以说是由坊市分离到坊市合一后的产物。宋东京城内共分8厢120坊,城外9厢14坊。在经济及地理位置等因素的影响下,宋东京的人口分布并不均衡,内城比外城相对稠密,呈现出一种梯度。与人口梯度相一致,在市区土地划分上出现了“紧处”与“慢处”的区别。其上所建之屋,亦相应划分为“紧屋”与“慢屋”,其房租有高低之差。这是政府调整城市空间结构的一种经济手段,以缓解人口向市中心聚集。 为了从“点”上深入研究宋东京的布局,本文借用现代城市中“空间片区”这一概念,将其空间细分为政治、礼制、皇家园林、禁军营地、宗教、教育、商业、官营作坊及娱乐九种类型。文章对各空间片区的位置、内容、分布特点等方面,进行了探讨。在此无法一一列举,仅以政治与商业空间为例,予以说明。更多还原

【Abstract】 Flame spraying is a process in which a metallic or non-metallic material is heated and then propelled onto a substrate to produce overlay coatings for protection or performance enhancement purposes. The simplicity of the process allows the coating can be applied in the field, which is very cost effective. In addition, there is no limitation on shelf or pot life.Polyamide (PA) is a kind of high performance thermoplastic material. It becomes of great interest to applications as bearing and slider materials. PAIOIO is one of the long carbon chain polyamides with excellent properties like wear-resistance and corrosion-resistance etc. On the other hand, nanometer-sized particles have superior properties compared to conventional materials. However, little research on the flame-sprayed PAIOIO and its composite coatings. In this thesis, we report our investigations on the properties of flame-sprayed PAIOIO coatings with and without the incorporation of nanometer-sized particles such as silica (n-SiO2), titanium oxide (n-TiO2), zinc oxide (n-ZnO) and graphite (n-G).In the first part of the thesis, we have established a method for the first time for measuring the adhesive strength and cohesive strength about flame sprayed polymer coatings. We have designed two suites of moulds, one is for measuring the adhesive strength between the coatings and the metal substrates and the other is for measuring the cohesive strength of coatings. Results showed that the moulds are suitable to measure the strength of coatings. Both the adhesive and cohesive strengths of PAIOIO composite coatings with n-TiO2, n-ZnO, n-SiO2 and n-G was improved due to the incorporation of nanometer-sized materials.Using a uniform experimental design method, the dry friction and wear behaviors of PAIOIO and its composite coatings with graphite (G) and n-SiO2 were systematically investigated under dry sliding conditions against TMK rings by a ring-cube wear-test machine of MRH-3. The tests were performed at room temperature under air environment. The applied load (P) and sliding velocity (V)were selected according to the uniform design. Each test lasted for 20min and the weight loss was measured using an electronic scale. And the statistics of regression analysis of the experimental results was performed using software of SPSS 11.0 for Windows. The dry friction coefficient between the coating and steel increased while increasing the PV volume in some extent; when the PV volume increased beyond some value, the dry friction coefficient became decreased. The wear mass loss change with the PV volume was in the similar trends with that of dry friction coefficient. The wear mechanism of the coating was explained in terms of plastic deformation, fatigue tearing and adhesive abrasion.Due to the excellent thermal conductivity and lubricity of graphite, the friction surface temperature might be decreased and friction stress be diffused. Therefore, the incorporation of graphite improves the friction resistance of PA1010 coating greatly. SEM observations revealed that n-SiO2 can diffuse the friction stress and check the occurring of friction cracks, the worn surfaces of composite coatings with n-SiO2 were much smoother than that of pure PA1010 coating, the friction and wear resistance of PA1010 coating was improved obviously by the incorporation of n-SiO2. Ageing tests showed that the composite coatings with n-SiO2, n-TiO2 and n-ZnO have better age resistance than pure PAIOIO coating, and the composite coating with n-TiO2 has the best ageing property.更多还原