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81.
预应力混凝土梁桥以其结构刚度好、行车平顺、养护简单等一系列优点而备受工程界欢迎。然而近年来,大跨径预应力混凝土梁桥在施工过程或使用阶段,普遍出现各种不同性质的病害,最常见的病害为箱梁开裂和结构长期下挠;这些病害对桥梁的耐久性和营运的安全性构成了威胁,甚至在一定程度上阻碍、制约了大跨径预应力混凝土梁桥的发展。针对既有大跨径预应力混凝土梁桥的病害,病害成因分析、对桥梁损伤的诊断、损伤桥梁的修复加固方法是该类桥梁应用中亟待解决的问题。本文首先阐述我国现有大跨径梁桥的病害状况;大跨径预应力混凝土梁桥产生这些病害的原因,涉及设计计算、施工工艺、养护管理、材料性质等多个方面,针对各典型病害分析其原因,并给出相应的预防措施,以期对实际工程有所裨益。 相似文献
82.
Using daylight as primary light source has been widely recognized as an important strategy to reduce building energy demand and enhance indoor environment quality. However, to design and operate a building to make full use of daylight, which is a dynamic light source, to meet diverse occupant needs remains a challenge. This paper reports a post-occupancy study of the visual environment in a laboratory building on a university campus, and puts a spotlight on the building occupants as it examines the effectiveness of the daylighting design and systems integration in creating a visual environment to support occupant comfort and satisfaction while reducing artificial lighting demand. Results show generally high satisfaction with daylit work environment and positive effect of the horizontal shading strategy. Issues about the integration between daylighting and electric lighting systems and level of occupant control are identified and discussed for improving the effectiveness of daylighting and enhancing the quality of the visual environment in the building of study. A multiple-tool methodology is developed and tested, which included occupant surveys, interviews, illuminance measurements, continuous data loggers, fisheye-lens camera and glare-identifying software, and documentation of spatial settings, systems features, and user behavior. 相似文献
83.
研究行业诚信体系建设的动力演化机理。从系统动力学视角,建立行业诚信体系建设的动力学模型;基于实际行业诚信体系,进行了初始状态和方程设计分析、政策仿真分析。结果表明诚信制度越完善,诚信信息越透明,所需的诚信监管力度就越低,可有效降低监管成本并促进行业诚信水平提升;企业诚信水平对诚信制度变动最为敏感,行业从业人员诚信水平在长期内对诚信信息变动最为敏感,政府在诚信体系建设过程中发挥着至关重要的作用。基于诚信立法、诚信信息服务机构建设等角度为我国行业诚信体系建设提出对了策建议。 相似文献
84.
A novel reading and writing technology for a holographic versatile disk (HVD) system called collinear technology is developed. With this method a two-dimensional data page can be recorded as volumetric holograms generated by a reference beam and a signal beam that are bundled on the same axis and that are irradiated on the recording medium through a single objective lens. The multiplex recording and reconstruction process is demonstrated, and it is shown that the optical configuration and the dichroic medium disk structure are suitable for a compact system. With the HVD's special structure, the system can use a servo to focus, track, and locate the reading and writing addresses. A unique selectable-capacity recording format of a HVD and its standardization activity are also introduced. This method willenable us to construct a small HVD system with CD and DVD upper compatibilities. 相似文献
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这次建筑学年会的主题是“建筑我们的和谐家园”,那么什么是和谐家园?在建设和谐家园的过程中,中国建筑师应扮演怎样的角色?具备哪些方面的能力?通过城市、传统、与当代艺术的关联性三方面对建筑师的“礼”、“敬”、“慧”进行阐述,并结合相应的设计作品来回答这些问题. 相似文献
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XU Jianping MA Xiaodi ZHANG Zhifeng ZHAO Jiecheng NING Tong CHENG Yuting 《原子能科学技术》1959,54(10):1873-1878
The control rod worth measurement of the zero-power experimental device is generally performed by the periodic method, the substitution method or the rod drop method. In order to improve the efficiency of measurement, a multi-step rod-insertion method without compensation was proposed. The control rod worth of the first lead-bismuth reactor zero-power experimental device in China was measured by this method, and the results were compared with those obtained by the compensation method and the rod drop method. The accuracy of the method was verified by theoretical calculations. The results indicate that this method effectively reduces the space effect on measured worth, and the measurement results of control rod worth are accurate and reliable. The method can complete the higher precision rod worth measurement in a short time, and is suitable for the critical experimental device that needs to change the charging scheme frequently. 相似文献
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