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1.
本文从设计施工、环境侵蚀、突发自然灾害及突发事故灾害四个方面,分析了我国隧道衬砌结构安全所面临的问题;对上海地区黄浦江越江隧道和地下交通隧道等水下隧道工程进行了调查,重点分析了我国在役水下隧道衬砌结构服役的现状。并基于此,为有效保障隧道结构全寿命周期过程中的安全服役性能,及预留隧道结构长寿命有效条件,从隧道建设、结构性能退化、自然灾害、突发事故灾害等方面入手,探寻我国水下隧道结构的长寿命安全保障对策,以确保在隧道的全寿命周期内乃至长寿命要求下结构的安全服役性能。研究成果可为保障我国水下隧道等重大隧道结构的长寿命安全提供参考。  相似文献   

2.
我国已建成了规模居于世界前列的交通基础设施,但由于多种因素的影响,交通基础设施重大结构的安全保障问题面临着越来越严峻的挑战。本文分析了我国交通基础设施的发展现状,综述了国内外相关领域的研究进展,讨论了我国交通基础设施重大结构长寿命安全保障领域存在的主要问题及实现安全保障的技术途径,提出了实施安全保障计划应达到的目标以及需解决的关键问题。  相似文献   

3.
正会议主题:共享智能诊断技术构筑装备安全保障世界年腐蚀损耗的钢铁占总产量的1/6,我国年腐蚀损失达2万亿元。腐蚀是基础设施和工业设备服役寿命的决定性因素,高性能耐蚀材料开发和装备服役健康诊断及安全服役至关重要。然而,钢铁腐蚀造成了巨大的经济损失、灾难性事故和环境污染,严重制约了我国装备  相似文献   

4.
卷首语     
<正>本期《中国工程科学》以"交通基础设施重大结构安全保障战略研究"和"城市地下空间开发规划战略研究"的阶段性成果为主要内容,概要介绍了这两大专题的研究成果。交通基础设施是社会交通体系的核心部分,是国计民生和国家安全的重要支撑。改革开放30多年来,我国交通基础设施建设发展迅猛,取得了世人瞩目的成就。但是,以桥梁、隧道、  相似文献   

5.
本文介绍了网络安全基础设施可信保障体系建设的现状、问题及未来构建策略。通过对现有安全保障体系建设现状和存在问题的剖析,提出我国网络安全基础设施亟须构建基于主动防御思想的可信技术保障体系。为此,提出可信技术保障体系建设策略建议,主要包括:以自主创新的主动防御计算体系结构作为构建可信技术保障体系的突破点;在落实信息安全系统国产化的战略合作中一定要真正形成实质的本土化;加大自主创新力度,推动主动防御的理论研究、产品研发和工程应用;积极推进可信计算标准的制定和推广应用工作,以推动可信技术保障体系的规范化发展,开展试点示范。  相似文献   

6.
我国轨道交通基础建设实现了跨越式发展,但针对轨道工程运营的安全管理与高效维护,仍存在许多复杂的难题亟待解决,突出表现为轨道结构实际服役周期难以达到设计寿命。因此,组织实施铁路轨道工程长寿命安全保障计划尤为迫切。本文首先回顾了我国铁路轨道工程领域取得的成绩,进一步介绍了国外一些发达国家在该领域的发展动态。相比发达国家,目前我国在轨道工程长寿命安全领域的研究还存在比较大的提升空间,具体表现在缺乏顶层设计,研究工作的系统性不足,深度与广度不够。最后就该计划的实施从理论研究、人才培养、智能化信息管理、性能提升与恢复等方面提出了若干建议。  相似文献   

7.
<正>提高城市管网、排水防涝、消防、交通、污水和垃圾处理等基础设施的建设质量、运营标准和管理水平,消除安全隐患,增强城市防灾减灾能力,保障城市运行安全。围绕重点领域,促进城市基础设施水平全面提升。加强城市道路交通基础设施建设。公共交通基础设施建设。鼓励有条件的城市按照"量力而行、有序发展"的原则,推  相似文献   

8.
近些年来,随着我国城市化进程的加快,我国城市轨道交通基础设施建设也取得了显著的发展,从当前建设的现状来看,对于传统的以政府为主导的投资融资模式已难以满足现代建设的发展需求,因此新型的基础设施融资模式就显得非常具有应用价值,也就是国际较为流行的公私合作式融资模式即"PPP模式"。本文主要对"PPP模式"在城市轨道交通基础设施建设中的选择问题进行了分析探讨。  相似文献   

9.
近些年来,我国电力建设速度明显加快,在加大对电力基础设施投入的同时,我国也在电力信息化方面加大了投入,现今我国在电力信息化方面应经初具规模,在电力生产、电力销售、管理等方面都得到了应用,在享受电力信息化带来的便利的同时,怎样做好在信息化方面的保障工作,使其能够建立合理的电力信息化的安全保障体系是一项繁重的任务。本文将就电力信息化的现状以及如何建立合理的安全保障体系进行阐述。  相似文献   

10.
正会议主题:创新·延寿·突破·发展自2020年上半年以来,中央决定启动"新基建"刺激经济,在新基建大战略下,中国"基建狂魔"的核心基建材料——钢筋混凝土发挥着举足轻重的作用。但基础设施的耐久性与服役安全问题,成为"新基建"亟需考虑和解决的重要问题之一。因此,发展高性能钢筋混凝土材料、确保工程设施服役安全成为了当今必须攻克的课题。  相似文献   

11.
In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.  相似文献   

12.
We associate a variety of innovations with the term "Industry 4.0". The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...  相似文献   

13.
14.
ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.  相似文献   

15.
A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.  相似文献   

16.
Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……  相似文献   

17.
A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.  相似文献   

18.
Al2O3-ZrO2 nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness.  相似文献   

19.
On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……  相似文献   

20.
Friction stir processing (FSP) is an important technique for preparing surface composites. Fabricating defect-free surface composites with uniform particle distribution by FSP is a challenging task. In this study, silicon carbide particles reinforced AA5083 alloy surface composites was fabricated using different FSP strategies including variation in process parameters, dual-tool processing and tool offset overlapping. Material flow of the processed material with reinforcement particles demonstrated that the distribution of particles was influenced by the stirring action of the probe as well as the extrusion of the plasticized material due to the movement of the tool. Process parameters, particularly rotational speed, showed a dominant influence on the distribution of silicon carbide particles.  相似文献   

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