An Integrated Modelling Approach for Flood Simulation in the Urbanized Qinhuai River Basin,China

Water Resources Management - The accurate simulation and prediction of flood response in urbanized basins remains a great challenge due to the spatial and temporal heterogeneities in land surface...     

地铁CRD法施工对热力管网的影响研究

地铁车站近距离下穿热力管网风险极大,过度沉降常常导致管线变形损坏甚至引发安全事故,属于重大安全隐患.因此,研究暗挖施工对热力管网的影响,了解管线的变形及受力特性,对于生产安全的管控尤其重要.以北京地铁八号线中国美术馆站CRD单层暗挖段为依托,利用FLAC 3D模拟主动控制后热力管网的变形和受力,然后参照施工后现状,利用监测数据进行应力校核,并对预测值和实测值之间的差异作出分析.模型中对各种主要影响因素考虑得较为全面,可为类似工程提供参考.     

典型地区10kV配电线路雷击跳闸率计算分析

以安徽碧山117线10 kV配电线路为研究对象,在给定线路参数和环境参数的情况下,建立配电线路直击雷跳闸率和感应跳闸率的计算模型,并计算了雷击跳闸率,利用运行统计数据进行了结果验证,证明了所建模型的准确性。同时,对比研究了10 kV雷击跳闸率的影响因素。结果表明,绝缘U50%越高,雷击跳闸率越低;线路平均高度越高,雷击跳闸率越高;平均雷暴日增加,雷击跳闸率上升;土壤电阻率增加,雷击跳闸率上升,但变化幅度不大。     

水平弹性支撑抛物线拱在均布荷载与热载荷作用下的屈曲特性

分析了水平弹性支撑抛物线拱在均布荷载与热负荷共同作用下的屈曲特性,通过变分原理推导了弹性支撑抛物线拱的非线性平衡方程,得到了外荷载与径向位移和轴力的关系,用数值法分析了弹性支撑抛物线拱在均布荷载与热负荷共同作用下屈曲特性。     

某工程爆破及机车振动作用下房屋响应的研究

工程爆破及震动对地表建筑物会造成一定程度的损伤.以临合高速公路为背景,对该工程隧道爆破及机车震动的强震动实时测试和分析,并对附近房屋的损伤程度进行了宏观调查,分析得出地表震动特性、震动影响范围和程度,及其对房屋结构的影响.为类似工程爆破及震动的设计及施工安全管理提供参考和依据.     

上海地铁10号线车地无线通信受扰分析

上海地铁10号线采用卡斯柯公司提供的Urbalis888信号系统,当地铁信号系统受到干扰时,会导致信号系统安全保护功能启动而造成列车紧急制动,从而引发列车因重新启动而晚点或清客等情况.为避免类似情况的发生,对车地无线通信系统的特性进行分析,探讨车站内部PIS系统对CBTC系统的干扰以及外部ISM通信频道的干扰,提出减少无线干扰的措施.     

Characteristics of Left-Right Spiral Hollow Cylindrical Roller

Based on new rolling-sliding compound bearings,the wear between the one-way spiral hollow cylindrical roller and the ribs of the inner and outer ring of rolling-sliding compound bearings is reduced by innovational structural design. A new left-right spiral hollow cylindrical roller is proposed to replace the one-way spiral hollow cylindrical roller. The finite element analysis models of ordinary cylindrical rollers,one-way spiral hollow cylindrical rollers and left-right spiral hollow cylindrical rollers are respectively established by ABAQUS.The axial displacement of their center mass and the stress distribution of left-right spiral hollow cylindrical rollers are compared and analyzed. Theoretical study results show that this new left-right spiral hollow cylindrical roller not only inherits the advantages of one-way spiral hollow cylindrical rollers,but also avoids the axial offset and the serious wear of the one-way spiral hollow cylindrical roller. And the theory research conclusion is verified by the experiment. The left-right spiral hollow cylindrical roller has the advantages to overcome boundary stress concentration like logarithmic convex roller. The rolling-sliding compound bearings equipped with the new rollers can be better to adapt to the impact of vibration load.     

南昌工程学院“五力”模型战略分析

在我国高等教育大众化的推动下,江西省陆续产生了一批新建应用型本科院校.随着高等教育改革的不断深入,这些新建应用型本科院校也面临着前所未有的挑战,从竞争战略的角度来思考未来的生存发展已成为新建应用型本科院校的必然选择.借鉴迈克尔·波特的"五力"模型竞争理论,对南昌工程学院进行"五力"模型分析,在此基础上对南昌工程学院可供选择的3种竞争战略进行辨析,提出差异化战略是目前南昌工程学院的最佳选择.     

Preparation and characterization of high strength and high modulus PVA fiber via dry-wet spinning with cross-linking of boric acid

To improve the mechanical properties of polyvinyl alcohol (PVA) fibers, a series of PVA fibers were prepared via dry-wet spinning with cross-linking of boric acid (BA) (PVA/BA fibers), and using the mixed solvent of dimethyl sulfoxide and water. Moreover, the final PVA/BA fibers were characterized by Fourier transform infrared spectra (FTIR), scanning electron microscopy (SEM), differential scanning calorimetery (DSC), thermogravimetric analyzer (TGA), powder X-ray diffraction (XRD) and yarn strength tester. Furthermore, with the increasing of BA content, FTIR analysis showed that the degree of crosslinking of BA with PVA increased. SEM images of final PVA/BA fibers presented smooth surfaces, and the diameters decreased firstly and then increased. DSC, TGA, and XRD analysis indicated that the melting temperatures, thermal properties and crystallinities first increased and then decreased with the increasing of BA content. In addition, mechanical properties measurements illustrated that the cross-linking existed at an optimal BA content of 0.3 wt%, and PVA/BA-0.3 fiber had the highest tensile strength and Young's modulus of 13.1 ± 0.4 and 360.2 ± 10.4 cN/dtex, respectively.     

分段长初级双边直线感应电动机建模分析

分段长初级双边直线感应电动机(LP-DSLIM)系统由若干段单元电机串联或并联组成,为准确描述次级运动过程中单元电机的推力等状态变化和过分段时的暂态过程,该文提出了一种新型单元电机数学模型及分段LP-DSLIM系统模型.首先,对分段LP-DSLIM系统的特点进行分析,通过引入虚拟次级板将每段单元电机耦合的次级延长至与初级等长,以使单元电机初级、次级之间始终保持全耦合;然后,结合耦合因数得到实际次级磁链和初级磁链,以此推导得到新型单元电机数学模型,并基于此建立串联供电和并联供电的分段LP-DSLIM系统模型;最后,有限元计算和实验结果验证了提出的新型单元电机数学模型和分段LP-DSLIM系统模型的正确性.