新型CDCM催化剂在两段提升管催化裂化装置上的应用

CDCM催化剂在800 kt·a^－1两段提升管重油催化裂化装置（TSRFCC）上的应用结果表明,该催化剂具有活性高、目的产品选择性好、重油裂解能力强和抗重金属污染能力强的特点。能显著改善产品分布和提高产品质量，在操作条件基本不变的情况下，液态烃收率和总液收分别可提高2.80和0.60个百分点，同时汽油辛烷值和诱导期提高，液态烃中丙烯含量增加。     

混凝土冻融劣化后动态单轴抗压特性试验研究

为研究混凝土冻融循环后的动态力学性能,利用10 MN动静三轴仪对不同冻融劣化程度的混凝土在不同加载速率下进行单轴压缩试验,同时采集声发射数据分析试验过程中能量释放及损伤演化规律。最后,选用Weibull-Lognormal损伤本构模型,对试验数据进行拟合分析,并分析不同工况混凝土的损伤随应变的发展规律。研究结果表明:①相同冻融劣化程度时,随应变速率增加,峰值应力增大,峰值应变减小;冻融劣化程度会影响峰值应力的率敏感性;②在应变速率相同时,随冻融循环次数增加,峰值应力随之减小,峰值应变随之增大。③混凝土冻融劣化后应力应变关系峰前服从Weibull统计分布,峰后服从Lognormal统计分布。④在相同应变速率下,随着冻融循环次数的增加,混凝土的累计塑性应变整体呈增大趋势。     

两段浓缩、两段回收模式的煤泥水流程

介绍了选煤厂通常采用的单段浓缩、单段回收模式的煤泥水处理流程存在的局限性,阐述了两段浓缩、两段回收模式煤泥水处理流程中四个作业的主要作用及工艺要求,根据多年的设计经验和选煤厂生产实践,对煤泥水浓缩及粗、细煤泥脱水回收设备的选型提出了看法和建议。     

Revisiting the two-stage choice model: an empirical study of consumer choice on brand website visits

In consumer choice behaviour literature, a two-stage choice model serves as a base theory where choice behaviour is decomposed into a consideration stage plus a choice stage. Yet, this default model has been increasingly challenged by the ‘limited consumer search’ school of thought because consumers do not necessarily review all products in a choice set before making decisions, but frequently draw on external information as mental short cuts. Methodologically, the choice behaviour in stage 1 has traditionally been latent because data that directly observe how consumers form their consideration sets by eliminating alternatives are lacking. This study continues the ‘limited consumer search’ line of reasoning and proposes an aided non-compensatory process in choice stage 1, where consumers reduce brand website alternatives by using online ratings to arrive at a consideration set. We use observed Web analytics data to unveil the stage 1 choice process and also the transition from stage 1 to stage 2, which is in need of further research based on extant literature. Lastly, we cross-validate our model with two types of websites (i.e. search vs. experience/credence) and find our model is contingent on the type of website content, where consumers’ inclination to use online ratings for decision-making varies.     

沼蛤侵蚀对混凝土的性能损伤试验研究

沼蛤侵蚀给混凝土带来的性能影响对防治措施的选择与决策具有重要的参考意义。对于受侵蚀1年的自制试件和受侵蚀20余年的现场芯样,本文采用浸泡增重法、压汞法、场发射环境扫描电镜法和热重法分别测试了有贝附着组和无贝对照组的表层吸水率、表层孔隙特征与孔径分布、表层形貌和成分变化,以及表层钙成分含量变化这4个指标,研究了沼蛤侵蚀混凝土前后以及侵蚀时间对微观性能的影响。定量分析表明:沼蛤附着侵蚀混凝土后,混凝土不同尺寸的孔隙均有增加,同时表观密度分别下降了13.5%(侵蚀1年)和19.5%(侵蚀20余年),表层吸水率分别增加了82%(侵蚀1年)和101%(侵蚀20余年),混凝土表面的铝元素、铁元素和锰元素大幅增加,钙元素尤其是碳酸钙流失严重,分别减少了41.7%(侵蚀1年)和82%(侵蚀20余年)。因此,沼蛤的侵蚀会造成混凝土的微观性能损伤,受侵蚀时间越长,性能损伤越严重。     

两段法处理高浓度含砷废水的工艺研究

通过正交试验研究了用石灰、有机捕集沉淀剂(DTCR)两段法处理高浓度含砷废水的工艺条件，并与常规法比较了处理效果和处理费用。结果表明：用两段法处理后的废水可达标排放；污泥量大大减少，易脱水，含水率低，降低了后处理的难度和费用；污泥稳定，不产生二次污染。该法具有显著的社会效益和生态效益。     

大型磷酸浓缩装置设计的优化

过去十多年间,我国新建了十几套大型磷酸浓缩装置,均采用单级蒸发浓缩工艺,而国外大多采用两级或多级蒸发工艺。全面分析了两级浓缩技术经济上的先进性(降低投资,设备国产化难度降低),并提出了我国今后新建磷酸浓缩装置的优化方案应是两级或多级浓缩。     

Maximum quasi-likelihood estimation for the near(2) model

Abstract.  Maximum quasi-likelihood estimation is investigated for the NEAR(2) model, an autoregressive time series model with marginal exponential distributions. In certain regions of the parameter space, simulations indicate that maximum quasi-likelihood estimators perform better than two-stage conditional least squares estimators in terms of the per cent of estimates falling in the parameter space. The problem of out-of-range estimates is shown to be caused by the lack of information in the data rather than the characteristics of the method of estimation.     

基于通信流量特征的隐秘P2P僵尸网络检测

针对目前基于网络的P2P僵尸网络检测中特征建模不完善、不深入的问题, 以及僵尸网络中通信具有隐蔽性的特点, 提出一种对通信流量特征进行聚类分析的检测方法。分析P2P僵尸网络在潜伏阶段的通信流量统计特征, 使用结合主成分分析法和X-means聚类算法的两阶段聚类方法对特征数据集进行聚类分析, 进而达到检测P2P僵尸网络的目的。实验结果表明, 该方法具有较高的检测率和较好的识别准确性, 并保证了较快的执行效率。     

Treatment of methanol wastewater with two-stage and two-phase anaerobic process

The two-stage and two-phase anaerobic process (TSTP) composed of hydrolytic acidification reactor,first-order and second-order external circulation anaerobic reactors (EC) was taken to treat methanol wastewater. Test results show that TSTP process is quick start-up in 51 d, and the maximum VFA of hydrolytic acidification reactor effluent reaches 876 mg/L. Under the condition of volume loading of 6.56 kgCOD/m3·d, COD removal rate of the first-order EC reactor is about 85%, and under the condition of volume loading of 1.02 kgCOD/m3·d, COD removal rate of the second-order EC reactor is about 50%. When the inflow COD of TSTP process is between 7000-11000 mg/L, its effluent COD is lower than 600 mg/L. In the biological conversion process of methanol into methane,the production of acetic acids as an intermediate product can be ignored and the direct production of methane from methanol is predominant.