江海通航船货舱结构强度有限元分析

针对某江海通航船的货舱结构建立有限元模型,利用APDL语言实现波浪载荷的自动施加。分析江海通航货船在满载出港和压载到港两种典型工况下货舱结构的应力水平,并将有限元分析结果同传统的梁理论分析结果进行比较。     

Pressure drop and heat transfer of catalyzed diesel particulate filters due to changes in soot loading and flow rate

When soot particles are loaded in a diesel particulate filter, it causes increase in back pressure of the exhaust system. To minimize this pressure drop due to DPF, the filter needs to be regenerated after a certain amount of soot has been accumulated. It is crucial to estimate the correct amount of soot that has been accumulated by measuring the differential pressure. It is also important to understand changes in pressure drop due to flow rate variations of the exhaust gas, since the pressure drop would be influenced by the exhaust flow rate as well as the amount of soot. Furthermore, the heat transfer characteristics of the catalyzed diesel particulate filter (CDPF) are another major issue, as the filter is occasionally exposed to high temperature gas. This study presents the characteristics of pressure drop according to the variation of soot loading and the mass flow rate in CDPF. In addition, heat transfer characteristics in the filter was investigated when a high temperature gas flows into the CDPF. Tests were performed in several CDPF samples having varying amounts of catalyst coating. Experimental results indicate that rig-based experiments are useful in understanding the characteristics of pressure drop in the CDPF. In the cake filtration region, a pressure drop has a proportional relationship according to soot loading and mass flow rate. It was found that an increased catalyst coating may lead to enhanced convective heat transfer.     

基于ANSOFT的轴向磁场永磁同步发电机性能计算

本文介绍了一种轴向磁场永磁同步发电机,并使用ANSOFT公司的电磁场有限元分析软件Maxwe113D对其进行三维电磁场与外电路系统的场路耦合分析,从而得到该电机静磁场分布和空载与负载工况瞬态场的性能计算结果,通过样机试验证实了分析方法具有较高精度.     

船体纵骨的热点应力分析

运用MSC.Patran/Nastran软件,对典型船舶纵向构件进行了热点应力分析,讨论了4种不同因素对节点热点处的应力集中系数的影响,并总结了其变化规律。     

On stress concentration factors for tubular Y- and T-Joints in frame structures

This paper is written as a result of some years experience with fatigue analysis of offshore jacket structures where the connections are made as tubular joints. The hot spot stresses at the tubular joints in such analysis are normally derived based on parametric equations for stress concentration factors. These stress concentration factors are normally related to the axial force in the brace. It is observed that the hot spot stresses at the crown positions of the tubular joint in some cases are significantly affected by the local loading on the chord and the bending moment in the chord. In order to use the existing formulae in these cases some engineering effort is required to derive correct hot spot stress. This work can be avoided by using the nominal stress in the chord as the basis for calculating the hot spot stress at the crown position instead of using the axial force in the brace as basis for the analysis. This also extends the validity of the equations for stress concentration factors for T- and Y- joints in design standards. The proposed modification makes it also simpler to include the effect of joint flexibility in a proper way. The basis for a proposed revision of the equations for stress concentration factors for these joints is presented in this paper. It is considered that this modification leads to minor changes of the computer code, but that it will save analysis work for engineers and reduce the possibility of calculating incorrect fatigue lives in tubular frame structures.     

Levels of ultrafine particles in the Taipei Rapid Transit System

Ultrafine particle number concentrations are measured at five stations and inside trains on four routes in the Taipei Rapid Transit System during October–December 2007. The results indicate that there are no additional emission sources of ultrafine particle on the platforms. Ultrafine particle levels at a ground level station were, however, adversely affected by traffic outside of the station. Moreover, particles can enter the underground stations via the subway tunnels resulting in high levels during weekdays.     

强力骨架梁腹板开孔有限元分析

针对舰船结构中强梁腹板特殊开孔引起的应力集中问题,应用有限元法分析了开孔的垂向位置、孔的宽度、孔的长度对强梁整体强度的影响,以及其最大应力发生位置的变化规律,讨论了3种常用开孔补强方法的补强效果,并提出了一些供实际结构设计的参考意见。     

小水线面双体船全船应力分布的有限元分析

该文依据有关规范和文献,针对小水线面双体船的特殊外载及结构形式,用有限元法详细分析其全船及局部的应力分布规律,并计算出在不同载荷分布,不同结构形式,不同的加强措施下的应力分布情况及相应的应力值。     

非硫酸盐高浓度有机废水酸化的可生化性指标

利用表观B/C指标和理论B/C指标评价了厌氧酸化过程对蔗糖-蛋白胨人工废水可生化性的影响.结果显示对于COD为1 064～63 900 mg/L的废水,采用表观B/C评价指标,废水的可生化性降低了0%～96%;采用理论B/C指标,可生化性提高幅度为2%～21.6%.实验结果表明用理论B/C指标评价厌氧酸化过程对蔗糖-蛋白胨人工废水可生化性的影响较之表观B/C更为科学合理;同时说明对于非硫酸盐废水类型,理论B/C作为评价其酸化过程改变废水可生化性的指标同样适用;酸化出水的理论B/C随废水COD增加呈现下降的趋势,理论分析认为其与废水的酸化度(α)有关,酸化度越低,酸化出水的理论B/C越低.     

船舶应力监测系统疲劳监测点的布置

本文针对结构应力监测系统的疲劳监测点选取问题,根据规范初步筛选出疲劳危险点,利用谱分析法和应力集中系数法计算各类危险点的损伤度。基于各危险点损伤和坐标,设计了考虑损伤度和位置的程序进行筛选,进而确定疲劳监测点的位置。最后针对某艘船,运用上述方法确定了疲劳监测点的位置。