T梁预应力智能张拉精细化施工工艺及施工控制

桥梁工程的预应力施工采用智能张拉能够解决传统张拉中存在的问题,能够有效地控制施工质量、规范施工、节约投资,正在工程中大力推广。     

钢绞线张拉伸长值计算书的编写

针对预应力钢绞线张拉伸长值计算的准确性、计算书内容的完整性以及实用性,提出参考性意见。     

上海嘉定新城低碳道路的构建

根据低碳城市建设需求与上海嘉定新城定位,针对嘉定新城道路,设计采用了温拌型排水性沥青路面、钢渣透水人行道、绿化储碳技术与灌溉节水技术,率先在嘉定新城的临泽路成功实施,构建了低碳道路,起到了较好的工程示范作用,下一步将在嘉定新城大面积推广应用。     

基于二次反馈的两级交换结构

为缓解FTSA(feedback-based two-stage switch architecture)对调度算法执行时间的限制,提出了一种基于二次反馈的两级交换结构DFTS(double-feedback-based two-stage switch architecture).该结构通过二次反馈和接力调度模式,以多反馈一次N位缓存信息的代价拓展了调度算法的时域空间(N为交换端口数).理论分析表明:在相同条件下,DFTS的时延性能与FTSA的理论性能是一致的.     

斜靠式拱桥吊杆张力计算模型探讨

以斜靠式拱桥——平顶山市城东河路湛河桥主桥为工程实例,采用有限元程序MIDAS／Civil对该桥进行空间有限元离散,建立了斜靠式拱桥空间有限元计算模型．分别采用一次落架法、用吊杆张力设计值作为吊杆张拉控制力的计算方法及影响矩阵法3种不同方法,求解了吊杆初始张拉控制力．由3种不同计算模型得到的结果进行对比可以看出：采用影响矩阵法确定吊杆张力的计算模型得到的吊杆张力响应值与设计值吻合较好,保证了成桥时桥梁的内力和线形,是斜靠式拱桥确定吊杆张力的合适计算模型,对复杂空间异型梁拱组合桥的吊杆张力确定有较大的参考价值;其他两种方法计算结果的偏差均较大．     

某轮发电柴油机的高排温和低爆压故障分析

文章以某轮发电柴油机的高排温、低爆压故障为例,通过对6DSb-22型发电柴油机的工作原理和导致此故障的可能原因分析,提出了解决此类问题的具体方案。     

基于切换系统的船舶电力推进储能系统建模与控制

为减小推进负载扰动对船舶电力系统的影响,提出一种由超级电容构成的储能系统吸收推进负载扰动的新方法.在建立储能系统等效电路的基础上,通过引入切换系统理论,构建储能系统双向DC-DC变换器的切换系统模型,构造Lyapunov函数,进而得到系统切换律.以动态定位船为例的仿真研究表明,超级电容储能系统能够吸收低负载时的船舶电网能量,并在高负载时释放,有效降低能耗,提高推进系统性能.     

关于锚泊线表观张力若干问题的分析

分析锚泊线表观张力的概念及其作用,为使问题简化,避开表观张力,采用锚泊线重量与侧面静水压力分别计算的方法,给出修正后的锚泊线微分方程,用数值方法直接解出实际张力.     

Hydrodynamic comparison of a semi-submersible, TLP, and Spar: Numerical study in the South China Sea environment

The South China Sea contains tremendous oil and gas resources in deepwater areas. However, one of the keys for deepwater exploration, the investigation of deepwater floating platforms, is very inadequate. In this paper, the authors studied and compared the hydrodynamics and global motion behaviors of typical deepwater platforms in the South China Sea environment. The hydrodynamic models of three main types of floating platforms, e.g. the Semi-submersible, tension leg platform (TLP), and Truss Spar, which could potentially be utilized in the South China Sea, were established by using the 3-D potential theory. Additionally, some important considerations which significantly influence the hydrodynamics were given. The RAOs in frequency domains as well as global motions in time domains under time-varying wind, random waves, and current in 100-y, 10-y, and 1-y return period environment conditions were predicted, compared, and analyzed. The results indicate that the heave and especially the pitch motion of the TLP are favorable. The heave response of the Truss Spar is perfect and comparable with that of the TLP when the peak period of random waves is low. However, the pitch motion of Truss Spar is extraordinarily larger than that of Semi-submersible and TLP.     

Modal-split effects of climate change: The effect of low water levels on the competitive position of inland waterway transport in the river Rhine area

Future climate change is expected to affect inland waterway transport in most main natural waterways in Europe. For the river Rhine it is expected that, in summer, more and longer periods with low water levels will occur. In periods of low water levels inland waterway vessels have to reduce their load factors and, as a result, transport prices per tonne will increase. One possible consequence of these higher transport prices is a deterioration of the competitive position of inland waterway transport compared with rail and road transport, and thus a change in modal split. We study this issue using a GIS-based software model called NODUS which provides a tool for the detailed analysis of freight transportation over extensive multimodal networks. We assess the effect of low water levels on the costs of transport operations for inland waterway transport in North West Europe under several climate scenarios. It turns out, that the effect on the modal split is limited. Under the most extreme climate scenario, inland waterway transport would lose about 5.4% of the quantity that is currently being transported annually in the part of the European inland waterway transport market considered. The very dry year of 2003 can be seen as an analogue for this scenario.