城市电网高压电缆地下敷设必要性及常见问题解析

近年在北京、上海等大城市电网10~220 kV高压供配电线路新建及改扩建工程中,广泛地采用了电缆线路方式,城网供电达到世界先进水平。本文就城网高压供电电缆敷设方式在设计与施工实践中发现的问题及注意事项,进行分析与探讨。     

中国吊装资源整合、集约式管理时代的来临

正一年前,中国核工业建设集团根据其发展战略方针,通过改制分立、资源重组,组建成立了中核机械工程有限公司(以下简称中核机械);而今年五月,筹措近一年的中石化重型起重运输工程有限公司(以下简称中石化重型起运)正式挂牌。这两家以专业提供吊装、运输服务的公司的成立,是国内大型工程建设企业向专业化、规模化方向发展的必然产物,     

带式输送机弯曲段曲率半径的确定

通过输送机平面转弯段的受力分析,改进了平面转弯带式输送机转变处的布置结构,经使用,输送带在运行至弯曲段时能自动进行居中调节,效果较好。     

施工班组电气安装工程质量管理浅析

电气安装过程中,任何细小的差错都会造成质量问题,任何质量问题都会造成损失,轻者造成材料浪费、设备损坏,重者造成人身伤亡事故.施工班组是企业各项规章制度和安全措施最终的贯彻执行者,班组安全质量管理水平的高低,直接影响到企业的经济效益和社会效益.     

谈钢筋混凝土冬期施工操作要求

介绍钢筋混凝土施工操作要求，用科学的办法，克服冬期施工常常出现的结构裂缝，降低结构强度等问题，以保证建筑施工质量。     

试论会计职业判断的质量控制

会计职业判断影响会计信息的质量.本文从会计职业判断应遵守的原则、判断程序的规范和会计人员自身素质提高等方面论述了会计职业判断的质量控制.     

万源市沙滩镇栀子园地表变形成因机制分析与防治对策

以地表变形区的工程地质调查、实测地质剖面等地质资料为依据,总结了区内典型地带的地表变形特征,较深入地分析了该斜坡区的地表变形的成因机制,提出了防止地表变形继续发展的切实有效的防治对策。     

60Si2Mn弹簧钢的断裂失效分析

60Si2Mn弹簧钢在正常服役过程中出现断裂,断裂后部分原件损失,根据材料力学原理,并结合断口特征,确定断裂起源位置;采用光学显微镜、扫描电镜、体视显微镜、直读光谱仪等对残留端口的显微组织、宏微观断口形貌和化学成分等进行观察和检测分析,以确定断口起源和断口特征。结果表明:由于生产过程操作不当,弹簧表面存在微裂纹,同时由于喷丸处理的工艺不恰当,造成弹簧表面形成较深的应力线,应力线发展成为沿应力线的开裂和脱落。这些微裂纹、开裂以及脱落,作为弹簧的疲劳断裂源,造成了弹簧的断裂。     

Synthesis and luminescent properties of ternary complex Eu(UVA)3Phen in nano-TiO2

By introducing 2-hydroxy-4-methoxy-benzophenone(UVA) and 1,10-phenanthroline(Phen) as the ligands, the ternary rare earth complex of Eu(UVA)3Phen is synthesized, and it is characterized by elemental analysis, mass spectra(MS) and infrared(IR) and ultraviolet(UV) spectroscopy. Results show that the Eu(III) in complex emits strong red luminescence when it is excited by UV light, and it has higher sensitized luminescent efficiency and longer lifetime. The organic-inorganic thin film of complex Eu(UVA)3Phen doped with nano-Ti O2 is prepared, and the nano-Ti O2 is used in the luminescence layer to change the luminescence property of Eu(UVA)3Phen. It is found that there is an efficient energy transfer process between ligands and metal ions. Moreover, in an indium tin oxide(ITO)/poly(N-vinylcar-bazole)(PVK)/Eu(UVA)3Phen/Al device, Eu3+ can be excited by intramolecular ligand-to-metal energy transfer process. The main peak of emission at 613 nm is attributed to 5D0→7F2 transition of the Eu3+, and this process results in the enhanced red emission.     

Uncooled InAs0.09Sb0.91 photoconductors with cutoff wave- length extended to 11.5 μm

Uncooled InAsSb photoconductors were fabricated. The photoconductors were based on InAs0.05Sb0.95 and InAs0.09Sb0.91 thick epilayers grown on InAs substrates by melt epitaxy (ME). Ge immersion lenses were set on the photoconductors. The cutoff wavelength of InAs0.09Sb0.91 detectors is obviously extended to 11.5 mm, and that of InAs0.05Sb0.95 detectors is 8.3 mm. At room temperature, the peak detectivity of Dλp at wavelength of 6.8 mm and modulation frequency of 1 200 Hz is 1.08×109 cm.Hz1/2.W-1 for InAs0.09Sb0.91 photoconductors, the detectivity D at wavelength of 9 mm is 7.56×108 cm.Hz1/2.W-1, and that at 11 mm is 3.92×108 cm.Hz1/2.W-1. The detectivity of InAs0.09Sb0.91 detectors at the wavelengths longer than 9 mm is about one order of magnitude higher than that of InAs0.05Sb0.95 detectors, which rises from the increase of arsenic (As) composition in InAs0.09Sb0.91 materials.