基于语言结构和情感极性的虚假评论识别

随着电子商务的发展,识别网络中的虚假评论意义重大。传统的启发式策略或全监督学习算法不能有效地解决该问题。虚假评论与真实评论在语言结构和情感极性上存在差异,提出基于遗传算法对语言结构及情感极性特征进行优化选择,并利用选取的特征结合无监督硬、软聚类算法对虚假评论进行识别。实验结果验证了所提算法的有效性。     

“拟原位”法测定积炭催化剂有效扩散系数

用新设计的单片反应器制备积炭催化剂试样,与动态法测定催化剂微孔有效扩散系数的装置相配合,并采用以水为吸附介质的动态毛细凝聚法和毛细上升法测定积炭催化剂压片的孔隙率,实现了积炭催化剂粒内有效扩散系数的“拟原位”测定要求,避免了催化剂颗粒反应积炭后再研磨、压片对有效扩散系数测定带来的假象。本文利用提出的“拟原位”方法得到了ZSM-5沸石催化剂上乙苯/乙烯烷基化过程中反应-失活全过程的有效扩散系数变化曲线。     

气升式内环流反应器中油滴的分散特性

本文研究了气升式内环流反应器中油滴的分散特性。以对数正态分布密度函数为油滴尺寸的分散模型,导出了油滴的Sauter平均直径解析式。对模型作了实验验证,关联了模型参数。提出了油滴的尺寸分布密度函数和Sauter平均直径的半经验式。结果表明计算值与实验值吻合良好。     

A novel initial ranging algorithm for OFDMA systems using smart antenna

To improve the capacity of initial ranging （IR） users simultaneously accessing into network and enhance the performance of the IR, a novel IR algorithm is presented for the orthogonal frequency division multiple access systems with the smart antenna. The beamforming weight vectors provided by the antenna array are introduced for the IR users, and the procedures of the multiuser parameter estimation and the interference cancellation are designed. The proposed method can improve the accuracy of the channel estimation of active paths and efficiently reduce the residual multiple access interference. Simulation results show that the proposed method has a much better performance than the available successive multiuser detection and interference cancellation algorithm and accommodates more active ranging users simultaneously accessing into a cell.     

多级VPN技术在疫情直报网络中的应用

随着传染病网络直报的不断发展和关键业务不断增加,对传染病网络直报系统的安全性、可靠性、实时性提出了新的严峻挑战。本文分析了构建武汉市疾控系统VPN网络的背景及整体构架,阐述如何利用IPSEC VPN和SSL VPN技术构建国家、省、市、区疾控系统VPN网络的方法,真正实现资源共享和"一网多用"。     

改性水泥专用丁苯胶乳的稳定性研究

以十二烷基苯磺酸钠为乳化剂,用过硫酸钾引发体系,制备了改性水泥专用丁苯胶乳,考察了乳化剂浓度、进料方式和搅拌形式对胶乳稳定性的影响.     

Thermogravimetric analysis of methyl methacrylate‐graft‐natural rubber

The thermal degradations of methyl methacrylate‐graft‐natural rubber (MG) at different heating rates (B) in nitrogen were studied by thermogravimetric analysis. The results indicate that the thermal degradation of MG in nitrogen is a one‐step reaction. The degradation temperatures increase along with the increment of heating rates. The temperature of initial degradation (T₀) is 0.448B + 362.4°C, the temperature at maximum degradation rate, that is, the peak temperature on a differential thermogravimetric curve (T_p) is 0.545B + 380.7°C, and the temperature of final degradation (T_f) is 0.476B + 409.4°C. The degradation rate at T_p is not affected by B, and its average value is 48.9%; the degradation rate at T_f is not affected by B either, and its average value is 99.3%. The reaction order (n) is 2.1 and is not affected by B. The reaction activation energy (E) and the frequency factor (A) increase along with B, and the apparent reaction activation energy (E₀) is 254.6 kJ/mol. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2952–2955, 2002     

Diffusion of ellipsoidal granular particles in shear flow

The diffusion of nonspherical particles has not been well understood due to the complexity of their contact mechanics and self-organization of their orientations. We perform discrete element method simulations of monodisperse ellipsoids in a shear flow with Lees-Edwards boundary conditions to quantify the relation between the diffusion coefficient and the flow parameters. The results indicate that the particle aspect ratio strongly affects the diffusion coefficient by influencing the particle orientation and alignment. We develop a scaling law for the diffusion coefficient perpendicular to the flow direction, D_yy, which combines the influences of the shear rate , the solids fraction f, the effective particle diameter d_eff and the particle aspect ratio Z. We show that , where k_d is a dimensionless pre-factor, and a fit is obtained for the functional form of χ(f, Z). This scaling law will be useful in developing continuum transport models for applications.     

棉织物的抗菌免烫整理研究

通过正交试验探讨了用H2 O2 氧化降解法制备适用于与聚羧酸MAA - 1配合进行抗菌免烫整理的低聚水溶性壳聚糖的最佳工艺 ,研究了降解壳聚糖与聚羧酸MAA - 1配合对棉织物进行抗菌免烫整理的工艺以及降解壳聚糖的质量浓度和相对分子质量对整理效果的影响。结果表明 :用 80g/L的聚羧酸MAA - 1和 4 0 g/L相对分子质量为 90 0 0的降解壳聚糖分两浴整理的棉织物的褶皱回复角为 2 71°,DP等级为 4 .0 ,断裂强力保留率为 6 4 % ,对大肠杆菌和金黄色葡萄球菌的抗菌率分别为 94%和 83%。经过 2 0次洗涤 ,其WRA为 2 5 7° ,DP等级为 3.7,而抗菌率则均保持在洗涤前的 80 %以上。阴离子染料 (直接冻黄G)染色的K/S值较用聚羧酸MAA - 1整理的棉织物提高了 1 .85。     

快速高吸油性丙烯酸酯树脂的合成研究

以丙烯酸丁酯与甲基丙烯酸甲酯为共聚单体，在聚合体系中引入致孔剂和大分子增容剂，采用悬浮聚合法合成了快速高吸油性树脂，考察了致孔剂用量、增容剂用量、乙酸乙酯／异戊醇混合致孔剂质量比等对高吸油性树脂吸油性能的影响。结果表明：通过引入致孔剂乙酸乙酯，不仅使树脂对甲苯和汽油的吸油率分别达到了3300％和1000％，而且吸油速度加快，2h内可达到饱和吸油；在致孔的基础上引入增容剂，可使树脂对汽油的吸收率显著提高，达到了1500％。