近海环境高架段组合道床系统隔振性能跟踪分析

目的 针对北部沿海地区高架段组合道床隔振系统进行跟踪测试研究,研究分析组合道床系统在近海环境下历经4a前后的轨道动态变形和隔振性能分析。方法 采用试验法对普通道床和组合道床的钢轨、道床进行动态变形和振动分析,分别计算出动态变形量及隔振量。结果 相对于普通道床,组合道床钢轨相对于基础的垂向平均变形为3.63～3.72 mm,符合相关技术规范的4 mm安全要求。高架线组合道床在运营4 a后,隔振量变化率为1.88%,表明组合道床在近海环境下具有稳定的隔振性能。结论 组合道床系统仍具有较好的且相对一致的安全性和隔振效果。     

基于数值仿真的全表面轮毂弯曲疲劳试验及疲劳寿命分析

目的 预测钢制全表面轮毂易产生疲劳破坏的危险区域,并分析其弯曲疲劳寿命。方法 针对全表面轮毂的弯曲疲劳试验工况,建立有限元分析模型,综合考虑螺栓拧紧方式、螺栓预紧力以及材料非线性特征的影响,通过在加载轴末端建立局部坐标系,实现载荷的分解,并最终实现弯矩的动态加载。在此基础上,进行轮毂的受力分析,然后构造适用于轮毂的应力寿命曲线,并使用名义应力法进行疲劳寿命预测。结果 动态弯矩的加载方向变化会显著影响轮辐表面的应力分布特点,螺栓预紧力施加后,螺栓孔附近区域的应力显著增大,在计算中应考虑其影响。在获得各节点载荷历程后,以高应力幅和平均应力为标准,筛选出了轮毂的危险节点。结论 基于数值仿真的本型全表面轮毂弯曲疲劳试验,危险节点位置均位于轮辐通风孔的内圆角附近区域,可有针对性地对该区域进行相应的优化设计,以进一步提高轮毂的弯曲疲劳寿命。分析得到当前轮辋弯曲疲劳寿命约7.6万次,符合国家标准的要求。     

复合材料与高温合金螺栓连接结构高温振动防松试验研究

目的 针对温度补偿垫块和碟形垫片2种防松形式的复合材料与高温合金螺栓连接结构,进行高温振动环境下的防松试验研究。方法 推导连接结构预紧力与固有频率的关系,表明固有频率的变化可作为连接结构是否松动的判据。研究常温环境下螺栓预紧力对复合材料连接结构固有频率的影响,以及在常温、高温振动环境下温度补偿垫块和碟形垫片2种防松形式的热防松效果。结果 在常温振动环境下,2种防松形式的防松效果接近,在高温振动环境下,温度补偿垫块方案的防松效果优于碟形垫片方案。结论 复合材料与高温合金螺栓2种材料的热膨胀系数不一致引起的热适配问题是导致的螺栓松动的主要原因。     

磁性分子筛负载TiO2复合光催化剂的制备及性能

采用超声辅助水热法合成了磁性分子筛Fe₃O₄/SSZ-13,然后通过溶胶-凝胶法对其继续负载TiO₂制得复合光催化剂TiO₂-Fe₃O₄/SSZ-13。借助XRD,FTIR,SEM,TEM,VSM,UV-Vis,PL对其形貌、结构及性能进行了表征,并考察了其光催化性能。表征结果表明,Fe₃O₄的加入不会改变分子筛的原有结构,复合材料的光响应范围扩大,电荷分离效率提高。降解实验结果表明,光照40 min时活性艳红的去除率可达89.7%,光照60 min时活性艳红去除率可达最大（93.6%）,较TiO₂提高了5.7%。此外,这种材料还具有较强的磁性,饱和磁化强度为17.80 （A·m²）/kg,可通过外加磁场回收。     

氨基磺酸溶液浸出废锂离子电池负极活性材料中的锂

随着锂离子电池的广泛应用,产生了大量废锂离子电池,其负极活性材料中积累了高品位的锂。锂作为一种稀有金属,对其进行回收利用很有意义。选取了无毒、稳定性好的氨基磺酸作为浸出剂,浸取废锂离子电池负极活性材料中的锂,考察了预处理方式对负极活性材料成分和结构的影响以及浸出条件对锂浸出率的影响。结果表明:600℃下煅烧4 h,可完全去除附着在负极活性材料表面的有机物;在氨基磺酸浓度0.75 mol/L、固液比5 g/L、浸出温度40℃、浸出时间45 min的最佳浸出条件下,负极活性材料中锂浸出率达97.2%。     

超疏水材料的制备及其去除水中污染物性能的研究进展

综述了金属基超疏水材料和聚合物基超疏水材料的制备及其去除水中污染物性能的研究进展,并从污水处理的角度展望了超疏水材料的发展方向。指出,超疏水材料在污水处理领域中的发展方向主要为：低成本、高效能且环境友好的超疏水材料及其制备工艺的开发;持久（永久）性超疏水净水材料的制备;超疏水材料对水中有毒金属离子的去除及其机理研究;超疏水材料水中抑菌性的深入研究及其应用;超疏水材料对水中药物和个人护理品（PPCPs）以及纳米污染物的去除。     

Effect of PCM on temperature fluctuation during the door opening of a household refrigerator

Temperature fluctuation inside the cabinet of a household refrigerator significantly affects the quality of preserved food. Phase change material (PCM) is a latent heat storage system that can store and release the heat energy by changing its phase from liquid to solid and solid to liquid respectively. Therefore, use of PCM inside the refrigerator cabinet has the potential for minimizing the temperature fluctuation during the door opening and the power failure. However, very few studies in the literature were dedicated to investigating the role of PCM to reduce the temperature fluctuation. The aim of this work is to experimentally investigate the effects of PCM on temperature fluctuation inside the cabinet of a household refrigerator during the door opening and power failure. The results found that a significantly lower temperature fluctuation can be obtained using PCM. It was found that during the door opening condition the air temperature in the cabinet rose rapidly. However, when a PCM container was used, temperature variation was reduced to 3–5°C. During the power failure, the system with PCM maintained a lower temperature inside the storage chamber for a long period of time (about 2 hours). Moreover, the test results indicate that PCM maintains more stable temperature in the foodstuffs inside the refrigerator. This reduction of temperature fluctuation ultimately improves the quality of preserved food.     

Water Footprint of 65 Mid‐ to Large‐Sized U.S. Cities and Their Metropolitan Areas

Conventional indicators of water use for urban areas account primarily for direct water use. In contrast, our objective here is to employ the water footprint (WF) concept and methodology to include the virtual or indirect water use to assess the production‐side and consumption‐side WF of 65 United States (U.S.) cities. The 65 cities include the largest metropolitan areas and some of the major mid‐sized cities in the U.S. We use metropolitan areas to define our city boundaries as this is the native spatial resolution of the main datasets used. To estimate the urban WFs, we integrated large and disparate datasets, including commodity flow (agricultural, livestock, and industrial commodities), water use, and socioeconomic data. By analyzing the estimated WF values, we found indirect water use accounts on average for 66% of the WF of consumption. We found some cities are net virtual water exporters (11 of 65) because they rely heavily on direct water uses or are heavy producers of industrial commodities. Also, WF patterns vary widely across the U.S. but regional patterns seem to emerge. For example, the dense cities of the U.S. northeast megaregion have a significantly low per capita WF relative to the other cities, while cities in the Gulf Coast megaregion have a significantly higher industrial WF of production and consumption. Furthermore, there is inequality in the WF of consumption where a few cities account for a disproportionate share of the total U.S. urban water uses.     

基于GJB150舰船冲击测量中零漂问题分析

舰船冲击试验为破坏性试验。由于冲击的持续时间短并且能量释放剧烈,在测试的过程中经常出现信号丢失、过载或零漂现象,极大的影响了测量数据的可靠性。通过对冲击测量过程中产生的零漂现象进行原因分析,从而提高测量信号的有效性。     

灾后物资供应系统风险预警可拓模型的初步设计

在可拓学理论的基础上,按照风险预警目的和方法的要求,构建了灾后物资供应系统流动性风险预警模型.该模型解决了物资需求与客观实际采购量的矛盾,客观地反映了风险变化的动态化过程,初步提高了流动性风险预警的有效性.