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181.
在室内装潢方面,人们较注重室内布局和装饰,而对给水管道则极少关注.应引起足够的重视。在建筑给水系统中由新型塑料管材替代金属管材已成为趋势。所以,室内给水管应选用新型塑料管材,并且应根据新型塑料管材的特点进行施工。确保给水系统的安装质量。 相似文献
182.
高文华 《科技情报开发与经济》2004,14(6):304-305
以新长铁路为例,从施工前、施工中及施工后的具体情况出发,对过江光缆施工技术进行了详细的说明,就如何减小风险提出了一些建议。 相似文献
183.
1 Introduction
Over the past several years, the preparation and characterization ofnanoscale magnetic materials, especially one-dimensional (1D) nanostructure, have attracted much attention as the nanomaterials would allow investigating the fundamental aspects of magnetic-ordering phenomena in magnetic materials with reduced dimensions and could lead to new potential applications such as data storage technology[1-6]. 相似文献
184.
As a newly developed precision technology, casting-forging complex near net forming process is utilized to produce complex components with a short lead time, low cost and high precision, thus to accelerate the response speed of the market and enhance the competitive power of products. In this paper, the casting-forging complex near net forming process of alternator claw pole was developed and investigated with a combination of experimental and numerical simulation method. Qualified near net workpiece was manufactured, mechanical parameter and relative field information during the forming process was also obtained. While the alternator claw-pole is processed with this technology, the forming force is small, the process is short and the quality of forgings is perfect. Therefore, the complex casting-forging near net forming process of claw-pole is an energy and material saving technology, which will have a vast developing and application prospect in the future. 相似文献
185.
Fracture toughness is very important when applying Damage Tolerance Design and Assessment Techniques. The traditional testing approach for obtaining fracture toughness values is costly and time consuming. In order to estimate the fracture toughness of ductile metals, the fracture mechanics theory, materials plastic deformation theory and materials constructive relationships are employed here. A series of formulae and a theoretical approach are presented to calculate fracture toughness values of different materials in the plane stress and plane strain conditions. Compared with test results, evaluated values have a good agreement. 相似文献
186.
Selective functionalization of mesoporous silica nanospheres (MSNs) is crucial for nanoengineering of MSNs.
Herein, we have combined “surface-protected etching strategy” and “cationic surfactant assisted etching
strategy” to prepare functionalized MSNs with externally attached amino groups. The externally attached NH2
groups endow the catalysts with excellent catalytic performance for nitroaldol reaction between nitromethane
and benzaldehyde. In addition, those NH2-MSNs can also be used to support gold nanoparticles, which display
very good catalytic performance for reduction of 4-nitrophenol. It can be envisioned that the synthesis protocol
developed in this work could also be extended to nanoengineered MSNs, which provides opportunities for nanoreactors
design. 相似文献
187.
Rodney G.Downey ;Judith Egan ;Michael R.Fellows ;Frances A.Rosamond ;Peter Shaw 《清华大学学报》2014,(4):329-337
The main purpose of this paper is to exposit two very different, but very general, motivational schemes in the art of parameterization and a concrete example connecting them. We introduce a dynamic version of the DOMINATING SET problem and prove that it is fixed-parameter tractable(FPT). The problem is motivated by settings where problem instances evolve. It also arises in the quest to improve a natural greedy heuristic for the DOMINATING SET problem. 相似文献
188.
189.
In this paper, we present an explanatory objection to Norton's material theory of induction, as applied to predictive inferences. According to the objection we present, there is an explanatory disconnect between our beliefs about the future and the relevant future facts. We argue that if we recognize such a disconnect, we are no longer rationally entitled to our future beliefs. 相似文献
190.