高校WLAN优化方案研究

在规模应用无线局域网的网络中,网络优化是不可缺少的步骤。对重庆各大高校WLAN优化所使用的各种方案进行了总结及简单分析,并以楼层构造较特殊的某高校12舍为例,通过频点规划、功率控制和天线改造等优化方法,使得该宿舍楼在指标和业务测试结果中均有明显提升。     

真丝织物抗披裂性能的研究

本文从织物结构的角度研究了真丝织物的抗披裂性能。通过对七十一种织物试样的测试,探讨其产生披裂的原因;并运用线性回归的数据处理方法,得出织物的抗披裂性能与织物的经纬密度、条份(D)、织物组织、经丝上机张力等因素之间的关系;同时提出了抗披裂性能的最佳区域,对织物的设计和生产具有一定的指导意义。     

筏体和基础弹性对船舶设备冲击响应影响的试验分析

试验研究是船舶机械设备冲击隔离性能分析的主要方法之一。为了分析筏体弹性、基础弹性和限位器间隙对冲击响应的影响，设计制作了可以考虑筏体弹性和基础弹性的带有限位器的浮筏隔振系统试验模型。试验结果表明筏体弹性和基础弹性对系统的冲击响应均有一定程度的影响，它们使得机组的最大加速度响应减小，提高系统的抗冲击隔离效果。对于刚性浮筏隔振系统和弹性浮筏隔振系统，限位器与冲击响应之间的关系是相同的，即安装限位器之后将使得筏体和机组的加速度响应增大，随着限化器间隙的减小，筏体和机组的最大加速度响应进一步增大。     

1422粗轧带钢板廓形状变化仿真研究

采用有限元的方法建立带钢立轧/平轧的三维模型,对热轧带钢粗轧过程的板廓的变化规律进行了仿真研究,重点分析了各道次轧制后带钢板廓形状和边角的位置变化,以及材质,立辊辊形,立轧压下量等因素对边角位置的影响.研究结论为现场解决热轧带钢表面的边部黑线缺陷问题提供了技术思路,为工厂最终解决此一表面缺陷提供了帮助.     

埋地刚性管道上的地面荷载计算

针对埋地刚性管道上作用的地面荷载,明确附加荷载与堆积荷载的区别,并对几种计算方法进行分析和算例计算,提出了地面荷载计算时应明确的参数,得出了不同荷载条件下适用的计算方法。     

Preparation of nano‐Ag particles and their modification on the mechanical and dielectric properties of epoxy resin

Nano‐Ag particles stabilized by a hyperbranched polymer (HBP) template were prepared for modifying the epoxy resin. The effects of preparation condition on the size and size distribution of Ag colloidal particles were studied. The Ag@HBP particles were then compounded with the epoxy resin to obtain the Ag@HBP/epoxy composites and the mechanical and dielectric properties of these composites were investigated. Dynamic mechanical analysis results show that the composites have higher loss factors than does the unmodified epoxy resin, which indicate better dissipation of mechanical energy and hence better shock or impact resistance. Fracture morphology of the composite shows a toughness feature. From the dielectric test results, the breakdown strength and dielectric constant of the composites at room temperature are increased, which can be explained by the Coulomb block effect. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

噻吩在硫化态Mo基催化剂表面的吸附行为

 利用原位红外光谱技术，研究了噻吩在硫化态的负载型和分散型Mo催化剂表面的吸附行为。结果表明，在室温下，噻吩在硫化态Mo催化剂表面可发生微弱的化学吸附，在较高的真空度下脱附；噻吩主要以η¹(S)配位形式吸附在硫化态Mo催化剂表面类似于MoS₂结构边角的配位不饱和的Mo^δ+位上，硫原子与硫化态Mo催化剂上配位不饱和的Mo中心相互作用，降低了噻吩环的芳香性，从而增加了C=C电子云的密度，使C=C增强、C-S键减弱，有助于加氢脱硫反应的进行。     

Characterization of petroporphyrins in Gudao residue by ultraviolet-visible spectrophotometry and laser desorption ionization-time of flight mass spectrometry

A porphyrin-containing fraction isolated from the >500 °C residue of Chinese Gudao heavy oil was analyzed using laser desorption ionization-time of flight mass spectrometry (LDI-TOF-MS) for the first time. LDI-TOF-MS was revealed to be suitable for the characterization of petroporphyrins mixture. LDI-TOF mass analysis, combined with UV-vis measurement, indicated that the nickel porphyrins in Gudao residue are a mixture of ETIO homologues (C₂₅-C₃₄) maximizing at C₃₀ and DPEP homologues (C₂₈-C₃₇) maximizing at C₃₁. The ΣDPEP/ΣETIO ratio is about 1.04, suggesting Gudao oil is in the stage of becoming mature.     

汾河二库大坝安全监测成果分析

汾河二库大坝为全断面碾压混凝土重力坝。在坝体、坝基及岸坡共埋设内、外观测测点 335个。本文就施工阶段内部观测的部分成果进行了整理分析     

Optimization of conversion of waste rapeseed oil with high FFA to biodiesel using response surface methodology

In the present study, waste rapeseed oil with high free fatty acids (FFA) was used as feedstock for producing biodiesel. In the pretreatment step, FFA was reduced by distillation refining method. Then, biodiesel was produced by alkaline-catalyzed transesterification process, which was designed according to the 2⁴ full-factorial central composite design. The response surface methodology (RSM) was used to optimize the conditions for the maximum conversion to biodiesel and understand the significance and interaction of the factors affecting the biodiesel production. The results showed that catalyst concentration and reaction time were the limiting conditions and little variation in their value would alter the conversion. At the same time, there was a significant mutual interaction between catalyst concentration and reaction time.The biodiesel produced in the present experiment was analyzed by gas chromatography/mass spectrometry (GC/MS), which showed that it mainly contained six fatty acid methyl esters. In addition, the diesel indexes analysis showed that most of the fuel properties were in reasonable agreement with the 0# diesel standard of China (GB252-2000) and the biodiesel standard of America (ASTM D6751).