水下盾构对接拆机后管片应力松弛控制措施研究

盾构对接技术凭借其“相向掘进、地中对接、洞内解体”等技术特点,在水下盾构隧道施工中的应用愈加频繁,由于技术尚不完善,盾构拆机导致的掌子面失稳和管片衬砌应力松弛等问题亟待解决。依托某海底隧道工程,针对盾构地中对接管片槽钢加固技术展开研究,建立了管片衬砌壳 连接器模型,通过在环间预留间隙实现了管片环缝的模拟,计算了管片环之间的连接强度,能够详细模拟不同荷载下的环缝张开量。以环缝张开量为判断标准,对比分析了加固范围、槽钢数量和槽钢型号等因素对加固效果的影响,研究结果表明：随着加固环数的增多,最大轴向位移和环缝张开量均呈现先减下后增加的趋势;随着槽钢的数量增多、型号变大,最大轴向位移和环缝张开量逐渐减小,减小趋势逐渐放缓,离盾尾较远的管片环加固效果相对较弱。     

一个北方乡村寺庙的千年自传(下):平顺龙门寺石刻文辑录(17~20世纪)

山西平顺龙门寺留有大量五代至民国的石碑、塔幢、题记,学界至今未有完备的整理及录文发表。笔者经多次实地踏查及文献搜集,整理、辑录了66篇(处)记文,是迄今对龙门寺文字史料最为完整的辑录。本篇为明崇祯、清、民国时期的部分,共计32篇。     

L-CNG与CNG加气站技术经济比较

介绍了我国天然气汽车加气站的建设状况,以同等规模的L-CNG加气站和CNG加气标准站为例,比较分析了两者的站内防火间距、占地面积、工程造价、运行费用。     

浅谈房屋建筑工程暖通设计的思路与方法

随着我国经济水平的不断提升,人们对居住环境的要求也越来越高,客观上给建筑业的发展带来了新的契机.房屋建筑工程的暖通条件应该满足人们的居住需要,符合城市的发展水平,同时也是建筑使用过程中的能耗重点,因此暖通工程设计是房屋建筑的设计重点,需要引起广大建筑设计者的重视.本文简单谈一点关于房屋建筑工程暖通设计的思路与方法,仅供广大建筑设计者参考.     

两种智能高效预测方法及其在人机系统中的应用

提出了两种高预测效率、高泛化能力的数值计算方法,一种方法是小波神经网络(Wavelet NeuralNetwork,WNN)算法;另一种是基于小波尺度函数的WSK-SV(Wavelet Scaling Kernel-Support Vector)算法.WNN算法将小波函数与BP神经网络方法相结合,通过输入层、隐含层、输出层间的连接权重以及隐含层使用的激励函数构成了这种算法的关键技术;WSK-SV算法将小波的尺度函数与SV(Support Vector)方法相结合,使这种算法既保持了SVM(Support Vector Machine)的优点,又具有很好的泛化能力.上述两种算法都属于计算智能(Computational Intelligence,简称CI)方法并用于人机系统的性能预测.     

大口径PE球阀启闭困难及关闭不严问题技术分析及解决方案

PE燃气管道在城镇燃气中低压管网中的应用越来越普遍,与之配套的PE球阀因其重量轻、耐腐蚀、免维护、寿命长等特点也得到广泛应用。但在实际使用中,经常遇到大口径PE球阀启闭困难和内漏问题,这给燃气公司安全运行、抢修工作造成了很大麻烦,并产生巨大经济损失。本文从PE球阀结构及工作原理方面分析问题原因,提出大小口径阀门并联操作的解决方案。     

氮苷1-(2,′3,′4,′6′-O-四乙酰基-β-D-吡喃葡萄糖基)-咪唑的制备

以D-葡萄糖(Ⅰ)、醋酸酐为原料,在无水吡啶中制得中间体1,2,3,4,6-O-五乙酰基-D-葡萄糖(Ⅱ),收率为87.5%。在HB r/CH3COOH条件下对Ⅱ异头碳上的乙酰基进行溴代,制得1-溴-2,3,4,6-O-四乙酰基-D-葡萄糖(Ⅲ),不经分离,在相转移催化剂TEBA催化下,Ⅲ直接与2,4-二硝基苯酚反应得到酚苷1-O-(2,′4′-二硝基苯)-2,3,4,6-O-四乙酰基-β-D-葡萄糖苷(Ⅳ),最后Ⅳ与1-三甲基硅基-咪唑在无水四氯化锡的催化下,室温反应52 h制得氮苷1-(2,′3,′4,′6′-O-四乙酰基-β-D-吡喃葡萄糖基)-咪唑(Ⅴ),此步反应收率为90%。     

Green electroluminescent polyfluorenes containing 1,8-naphthalimide moieties as color tuner

A series of copolymers (CNPFs) containing low-band-gap 1,8-naphthalimide moieties as color tuner was prepared by a Yamamoto coupling reaction of 2,7-dibromo-9,9-dioctylfluorene (DBF) and different amount of 4-(3,6-dibromocarbazol-9-yl)-N-(4′-tert-butyl-phenyl)-1,8-naphthalimide (Br-CN) (0.05-1 mol% feed ratio). The light emitting properties of the resulting copolymers showed a heavy dependence on the feed ratio. In photoluminescence (PL) studies, an efficient color tuning through the Förster energy transfer mechanism was revealed from blue to green as the increase of Br-CN content, while in electroluminescence (EL) studies, the color tuning was found to go through a charge trapping mechanism. It was found that by introduction of a very small amount of Br-CN (0.1-0.5 mol%) into polyfluorene, the emission color can be tuned from blue to pure green with Commission International de l'Echairage (CIE) coordinates being (0.21, 0.42) and (0.21, 0.48). A green emitting EL single-layer device based on CNPF containing 0.1 mol% of Br-CN showed good performances with a low turn-on voltage of 4.2 V, a brightness of 9104 cd/m², the maximum luminous efficiency of 2.74 cd/A and the maximum power efficiency of 1.51 lm/W. To further improve the EL performances through balancing the charge trapping process, a copolymer (BCNPF05) derived from 0.5 mol% of a triarylamine-containing 4-{3,6-bis-[4″-(4?-bromophenyl-p-tolyl-amino)-phenyl]-carbazol-9-yl}-N-(4′-tert-butyl-phenyl)-1,8-naphthalimide (Br-BCN) and 99.5 mol% of 2,7-dibromo-9,9-dioctylfluorene was also prepared. As expected, a single layer EL device based on BCNPF05 exhibited better performances with a brightness of 14228 cd/m², the maximum luminous efficiency of 4.53 cd/A and the maximum power efficiency of 1.57 lm/W.     

Further investigation of polyaminoamide‐epichlorohydrin/stearic anhydride compatibilizer system for wood‐polyethylene composites

The combination of a polyaminoamide‐epichlorohydrin (PAE) resin (a paper wet strength agent) and stearic anhydride was recently reported as an effective compatibilizer system for wood‐polyethylene composites. Further investigation of this new compatibilizer system revealed that the pH value of a PAE solution, dosages of PAE and stearic anhydride, and the weight ratio of PAE to stearic anhydride had significant impacts on the compatibilization effects of the compatibilizer system. Adjusting the pH value of the PAE solution from 5.0 to 10.4 increased the strength of the resulting wood‐polyethylene composites. The highest strength of the resulting wood‐polyethylene composites was obtained at 3 wt % PAE and 3 wt % stearic anhydride. At 4 wt % or 6 wt % of a compatibilizer, this PAE‐stearic anhydride system was superior to maleic anhydride‐grafted polyethylene (MAPE), one of the most effective compatibilizers, in terms of enhancing the strength of the resulting wood‐polyethylene composites. Fourier transform infrared spectroscopy (FTIR) analysis revealed that PAE and stearic anhydride formed covalent bonding with wood flour. The compatibilization mechanisms of this PAE‐stearic anhydride compatibilizer system were investigated in detail. Water‐resistance tests indicated that the PAE‐stearic anhydride compatibilizer system increased the water‐resistance of the resulting composites. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 712–718, 2006     

Humidity sensitivity of polypyrrole and polypyrrole/SBA‐15 host–guest composite materials

Polypyrrole (PPY) and PPY/SBA‐15 host–guest composite materials have been prepared using chemical synthesis route and characterized by XRD, IR, N₂ adsorption–desorption isotherms, and SEM. The humidity sensitive properties (HSP) of this kind of materials have been studied by analyzing the variation curve of impedance as a function of relative humidity. It was found that the PPY/SBA‐15 host–guest composites materials exhibit better HSP than that of the corresponding pure PPY. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3301–3305, 2006