厦门海底隧道堵水限排安全监测及分析

海底隧道应采取堵水限排的地下水处理方式,为了研究堵水限排海底隧道围岩压力、初期支护水压力和钢拱架内力在施工阶段的变化规律,结合厦门海底隧道工程,对施工现场的围岩压力、初期支护后水压力和钢拱架内力进行实时监测.研究表明,初期支护在施工阶段有较高的安全系数,止水超前注浆和初期支护背后注浆对海底隧道非常有必要.在堵水限排情况下,通过加强注浆等工程措施,初期支护水压力可降至静水压力的1/3.通过对施工现场排水量的监测与分析,提出了排水量控制标准,厦门海底隧道软弱围岩地段的排水量应按照0.25 m'/(m·d)控制.研究成果在厦门海底隧道中得到了验证和应用.     

IDC机房用板式换热器的节能实例分析

在分析当前IDC机房高能耗背景的基础上,结合某IDC机房的空调节能改造实例,对改造后的节电效果进行理论计算与实际测试.结果表明,通信机房用板式换热器的节电效果是显著的,节电率达14.6%,回收期为2.25年,具有良好的经济效益和社会效益.     

高岭土/聚丙烯酸钠高吸水性复合材料表面交联改性及吸水动力学研究

以乙二醇二缩水甘油醚为交联剂,蒸馏水和丙酮的混合溶液为溶剂,用水溶液聚合法对高吸水性复合材料进行了表面交联反应.结果表明,当交联剂用量为0.5％(相对于表面交联前吸水材料的质量),相比(水与丙酮的体积比)为0.15时材料的性能最好,吸水倍率达406g/g,前130min吸水材料的平均吸水速率达0.280g/g ·m i...     

丙烯酸酯-乙烯基三乙氧基硅烷共聚物膜的制备及乙醇/水中的溶胀吸附性能研究

采用乳液聚合法制备了丙烯酸酯-乙烯基三乙氧基硅烷共聚乳液.用全反射-傅立叶红外光谱仪( ATR- FTIR)对共聚物膜结构进行了表征.考察了VTES与丙烯酸酯用量比对共聚乳液的绝对黏度、共聚物膜的交联度及亲水性、溶胀吸附性能的影响,最后计算了共聚物膜在乙醇和水中的扩散系数.实验结果表明:VTES与丙烯酸酯发生自由基聚合;随着VTES与丙烯酸酯用量比的增大,共聚乳液的绝对黏度逐渐增加,共聚物膜的交联度及接触角逐渐增大.提高乙醇浓度或者增加温度,都可以提高共聚物膜在乙醇/水体系中的溶胀度;VTES与丙烯酸酯用量比为0.15的共聚物膜在乙醇中的扩散系数最大,为0.023 09×10-4 m2/s;VTES与丙烯酸酯用量比为0.02的共聚物膜在水中的扩散系数最大,为0.023 57×10-4 m2/s.     

切削液对光学玻璃SF6在金刚石切削加工中可加工性的影响(英文)

本文研究了切削液对光学玻璃SF6在金刚石切削加工中可加工性的影响.首先对SF6进行了维氏压痕试验,并分析切削液(处理液)浸泡试件前后,SF6材料的硬度及断裂韧性的变化.进而进行了SF6试件的变切深刻划试验,采用共聚焦显微镜检测SF6材料的临界切削深度,试验结果表明,与未采用切削液的刻划相比,以碳酸钠为切削液的刻划使SF6的临界切削深度增加了35.6%;最后以压痕及刻划试验的结果为基础,进行了SF6试件的金刚石切削加工试验,由原子力显微镜(AFM)检测可知有切削液作用的切削试验中获得工件的表面粗糙度值比无切削液作用试验中的粗糙度值降低超过50%.试验结果表明,以碳酸钠溶液为切削液可显著改善光学玻璃SF6的可加工性.     

聚氨酯无机杂化材料研究进展及应用前景

介绍了聚氨酯无机杂化材料的性能,叙述了制备聚氨酯无机杂化材料的4种主要方法.重点对国内外聚氨酯无机杂化材料的研究现状进行了分析,对纳米SiO2和蒙脱土杂化的聚氨酯杂化材料进行了着重阐述,进而探讨了无机杂化材料在聚氨酯注浆材料中应用的可能性和今后发展前景.     

Compositionally graded multilayer Ba<Subscript>x</Subscript>Sr<Subscript>0.95−x</Subscript>Ca<Subscript>0.05</Subscript>TiO<Subscript>3</Subscript> ceramics prepared by tape casting for use as dielectric materials

Compositionally graded multilayer Ba_xSr_0.95−xCa_0.05TiO₃ (BSCT) ceramics were prepared via tape casting method using nanometer powders from co-precipitation. Microstructures and dielectric properties of the BSCT system were investigated. The powders were characterized by using transmission electron microscope and BET surface area measurement. Surface morphologies of the sintered samples and multilayer structure were examined by scanning electron microscopy. BSCT particles were of spherical shape with diameters in the range of 73–93 nm. Their specific surface areas were in the range of 11.7–14.6 m²/g. The graded BSCT ceramics with nine layers laminated in vertical way exhibited a higher sintered density, with an average grain size of 0.4 μm, after sintered at 1,200 °C. Dielectric constant, dielectric loss and tunability of the graded ceramics were 2223.94, 1.5 × 10⁻³ at 2 MHz and 42.9% at 3.0 kV/mm, with good dielectric temperature and frequency stability, which made it a promising candidate used for tunable ceramic capacitors and phase shifters.     

“土木工程制图”研究性教学方案设计及实践

研究了以＂房屋建筑施工图＂为研究性教学的载体,采用任务驱动教学法,设计适应学生特点的教学方案。抓住课堂、课外、训练等几个主要环节,引导学生进行研究性学习。从＂图纸规范＂、＂图示内容＂、＂尺寸标注＂、＂符号表达＂、＂文字书写＂以及＂总体印象＂等几个方面对学生作业进行全面的评价。实践表明,研究性学习调动了学生的积极性,扩大了知识面,培养了工程素质和团队合作精神,绘图质量明显提高,取得了较好的教学效果。     

用于机器人辅助穿刺手术进针策略研究的猪肝进针力建模

为研究机器人辅助肝脏穿刺手术中的进针策略以确保手术安全,基于实验数据建立了猪肝的进针力模型.方法如下:在2个新鲜离体猪肝3个不同区域内共采集了18条进针力曲线数据,根据针尖位置及进针力特征将力曲线划分为“被膜刺破前”、“进入肝脏前”和“进入肝脏后”3个阶段,然后采用已有的力模型分别进行每一阶段的进针力建模,通过对比各阶段的建模效果,确定最优的各阶段进针力模型,最后组合成完整的进针力模型.最终的进针力模型比较表明,相同个体不同区域的力模型差异较小,可以用一个力模型来表示该个体进针力特征,不同个体的进针力特征能否用一个力模型表示还需进一步验证.猪肝进针力模型的建立,可为实现机器人辅助人体肝脏穿刺手术中的进针控制和手术安全提供重要依据.     

Large strain response in acceptor- and donor-doped Bi<Subscript>0.5</Subscript>Na<Subscript>0.5</Subscript>TiO<Subscript>3</Subscript>-based lead-free ceramics

Effects of Fe and La addition on the dielectric, ferroelectric, and piezoelectric properties of Bi_0.5Na_0.5TiO₃–Bi_0.5Li_0.5TiO₃–BaTiO₃–Mn ceramics were investigated. Similar to the doping effect in lead-based piezoelectric materials, here the Fe-doped ceramic created a hard effect with an improved mechanical quality factor (Q _m) ~ 160, coercive field (E _c) ~ 2.9 kV/mm, decreased dielectric constant ( e₃₃^T /e₀ ) ~ 80 3, \left( {\varepsilon_{33}^{T} /\varepsilon_{0} } \right)\sim 80 3, and loss (tanδ) ~ 0.024 while the La-doped one indicated a soft feature with improved piezoelectric constant (d ₃₃) ~ 184 pC/N, e₃₃^T /e₀   ~ 983, \varepsilon_{33}^{T} /\varepsilon_{0} \,\sim { 983}, tanδ ~ 0.033, and decreased E _c ~ 2.46 kV/mm. In addition, the temperature dependence of the ferroelectric hysteresis loops and strain response under unipolar electric field was also studied. Around the depolarization temperature T _d, large strain value was obtained with the normalized d₃₃^* d_{33}^{*} up to ~1,000 pC/N, which was suggested originated from the development of the short-range order or non-polar phases in the ferroelectric matrix. All these would provide a new way to realize high piezoelectric response for practical application in different temperature scale.