多阶变截面杆弯曲自由振动的计算

本文通过引入一组用矩阵形式表示的基本函数,分解了单阶杆的精确解,导出了相应于多阶变截面杆的频率方程和振型函数的通式,并通过计算机处理得到了精确数字解。最后还给出了数值解与理论解的比较。     

水景住区设计的新构想——“衡水天元—怡水花园水景公寓”项目设计

通过回顾衡水天元—怡水花园水景公寓设计过程,表述了尊重自然、因地制宜的设计理念,把建筑与环境融合,凸显了滨水住区的特色,营造了高品质的人居环境。     

电能回馈式传动系疲劳寿命试验台的研制

为解决现有传动系疲劳寿命试验台能耗大的问题,研制开发了一种以直流测功电机为加载器、数字直流可逆调速器为控制器,将直流测功电机产生的电能回馈到电网的传动系疲劳寿命试验台。该装置的电能回馈率达76%左右,节能效果显著。     

浅析工程造价咨询项目的风险管理

随着近年来工程造价咨询业务的发展，风险管理已显得日益重要，本文围绕工程造价咨询项目的各个阶段，即签订合同阶段、咨询准备阶段、项目实施阶段、校核和出具成果阶段、收尾工作阶段，分别重点阐述了造价咨询项目存在的风险和相对应的控制措施。     

毛主席纪念堂屋面维修设计施工及问题分析

毛主席纪念堂经过近20年的使用，由于屋面防水材料老化等原因，需进行维修。维修中对下层屋面和下檐天沟两大部位分别采取了相应的治理措施。维修实践证明，在设计时应仔细考虑基层结构与温度变形作用及材料的耐久性问题，以免造成渗漏。     

钢丝网架水泥夹芯板防火性能研究

本文就钢丝网架水泥夹芯板的防火问题作了系统的实验研究.实验结果表明,用锥型量热计测定,在钢丝网架水泥夹芯板两面抹上10mm厚的水泥砂浆的情况下,复合板能满足防火要求,可作为不燃性材料使用.     

乳化沥青改性水泥砂浆力学性能试验研究

研究了乳化沥青改性水泥砂浆的力学性能试验，并对其试验结果作了分析，表明了乳化沥青改性水泥砂浆比普通水泥砂浆的力学性能有了较大的改善。     

城市规划公众参与模式探讨

介绍了当前规划中公众参与存在的问题，并对其存在的问题提出了解决途径，最后从法制建设、提高公众参与意识、城建会建设几方面对保障机制进行了阐述，以期在现今社会环境中，为公众参与寻找出问题的解决途径。     

测量不确定度在水泥胶砂强度检测中的应用

本文结合检测人员在测量不确定度评定中所遇到的实际问题，找出影响测量结果的所有不确定度来源。对其测量方法进行全面的了解，总结经验，加于探讨.     

Study on two operating conditions of a full-scale oxidation ditch for optimization of energy consumption and effluent quality by using CFD model

The operating condition of an oxidation ditch (OD) has significant impact on energy consumption and effluent quality of wastewater treatment plants (WWTPs). An experimentally validated numerical tool, based on computational fluid dynamics (CFD) model, was proposed to optimize the operating condition by considering two important factors: flow field and dissolved oxygen (DO) concentration profiles. The model is capable of predicting flow pattern and oxygen mass transfer characteristics in ODs equipped with surface aerators and submerged impellers. Performance demonstration and comparison of two operating conditions (existing and improved) were carried out in two full-scale Carrousel ODs at the Ping Dingshan WWTP in Henan, China. A moving wall model and a fan model were designed to simulate surface aerators and submerged impellers, respectively. Oxygen mass transfer in the ditch was predicted by using a unit analysis method. In aeration zones, the mass inlets representing the surface aerators were set as one source of DO. In the whole straight channel, the oxygen consumption was modeled by using modified BOD-DO model. The following results were obtained: (1) the CFD model characterized flow pattern and DO concentration profiles in the full-scale OD. The predicted flow field values were within 1.98 ± 4.28% difference from the actual measured values while the predicted DO concentration values were within −4.71 ± 4.15% of the measured ones, (2) a surface aerator should be relocated to around 15 m from the curve bend entrance to reduce energy loss caused by fierce collisions at the wall of the curve bend, and (3) DO concentration gradients in the OD under the improved operating condition were more favorable for occurrence of simultaneous nitrification and denitrification (SND).