C程序设计中循环结构的教学设计与探讨

循环结构在C程序设计中占据重要的位置,是教学中的重点,同时也是教学中的难点。在教学中,如何使学生建立“循环”的概念、理解“循环”的含义、设计“循环”算法、实现“循环”功能,是教学设计的重点。通过对循环结构教学设计,理清教学思路,明确教学目标,化解教学难点、突出教学重点,寓趣味性、目标性于教学中,采用了项目引导、任务驱动、演示法、分析法、讨论法等多种教学方法,调动学生学习的积极性,培养学生程序设计能力。     

基于跨场景推理的事件关系检测方法

事件关系检测是一项面向事件之间逻辑关系的自然语言处理技术。事件关系识别的核心任务是以事件为基本语义单元,通过分析事件的篇章结构信息及语义特征,实现事件逻辑关系的深层检测。该文首次建立一套事件关系检测的任务和研究体系,包括任务定义、关系体系划分、语料采集与标注、评价方法等。同时,该文提出了一种跨场景推理的事件关系检测方法,该方法认为,具有相同事件场景的“事件对”,往往具有相同的事件关系类型。该文提出的基于跨场景推理的事件关系检测方法在针对四大类事件关系类型的检测精确率为54.21%。     

X-ray photoelectron spectroscopy of Pd/γ-alumina and Pd foil after catalytic methane oxidation

Samples of palladium supported on-alumina and a palladium foil were used as catalysts for methane oxidation at 550° C. The samples were quenched quickly in the reaction chamber to room temperature in flowing Ar and then transferred in vacuo for XPS analysis. Structure sensitivity was manifest from an increase in PdO stability and a decrease in carbon deposition relative to Pd with increasing particle size. The results were compared with recent ellipsometric data.     

应用高分子分子设计合成节能丁苯橡胶：Ⅱ.链结构形成机理

用阴离子法合成ＳＢＲ，多官能团锂为引发剂，环已烷为熔剂，极性添加剂为无规化剂和结构调节剂。对苯乙烯、１．２－结构单元在分子链上的分布情况进行了研究。对丁苯共聚物的共聚组成，序列分布、微观结构 形成机理进行了探讨。认为在聚合体系中同时存在有丁二烯的π烯丙基活性种、σ烯丙基活性种及苯乙烯活性种。丁二烯与σ烯丙基活性中心反应主要形成１．４－结构，同π烯丙基中心反应主要形成１．２－结构。对于π烯丙基活性中     

Morphology of epoxy resin modified with silyl‐crosslinked urethane elastomer

Silyl‐crosslinked urethane elastomer modifying epoxy resin has drawn much interest. Here the triethoxysilyl‐terminated polycaprolactone elastomer (PCL‐TESi) modifying diglycidylether of bisphenol A epoxy resins (DGEBA) system was chosen, and then the effect of the type of curing agent on the phase structure of the studied epoxy resin system was investigated. The modified systems were obtained with different phase structures by varying the formulations of the curing agent. It was experimentally shown that with the addition of aminosilane (KBE‐9103), the crosslinked density was greatly increased. The cured system also showed from SEM and TEM analysis that addition of KBE‐9103 increased the compatibility between the PCL‐TESi and DGEBA, which made the ductility of the system decrease, but also indicated from TEM that addition of much KBE‐9103 made the reacted silicone particles coagulate each other. The state of phase separation from TEM in the cured system was theoretically explained. These would serve the deeper studies of the mechanism of silyl‐crosslinked urethane elastomer modifying epoxy resin in the future. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 611–619, 2005     

基于结构聚类的图像去噪

为了克服传统BM3D去噪算法的不足,根据图像局部结构相似性提出了基于结构聚类的图像去噪算法。首先根据均值进行粗聚类构成块群;其次利用鲁棒数据归一化构造结构相似子群;最后对子群进行去噪,如果子群容量大于1,运用BM3D对该子群进行去噪处理,反之,运用基于阈值的DCT去噪算法对该块进行去噪。实验结果表明,该算法保护了图像的结构信息,相对于传统BM3D算法提高了图像的视觉效果。     

The phosphorous level fine structure in homoepitaxial and polycrystalline n-type CVD diamond

The application of very sensitive photocurrent-based spectroscopic techniques have led to the detection of new levels for the electronic structure of the phosphorous donor in n-type CVD diamond. By combining quasi-steady-state photocurrent measurements (PC), photothermal ionisation spectroscopy (PTIS) and the highly sensitive Fourier transform photocurrent spectroscopy (FTPS) technique at different temperatures, ranging from liquid nitrogen temperature to 170 K, the resulting spectra point to a richer structure than assumed up to now. This is the consequence of the improved sample quality over the last years, opening up to a much larger attainable doping window. By using doping levels, ranging from 10¹⁹ cm⁻³ down to 10¹⁶ cm⁻³ on 111 -oriented Ib HPHT substrates, still giving rise to measurable n-type conductivity, spectra showed less line broadening and more fine structure. Finally, the results will be compared with spectra measured on active P-doped polycrystalline n-type films.     

磷铝酸盐水泥浆体的抗冻性研究

抗冻性是砼耐久性的重要方面,尤其影响北方地区砼工程的使用寿命。引气能提高砼的抗冻性,但同时又存在气泡的稳定性问题和砼其他性能的受损问题。若能提高砼中水泥浆体的抗冻性,则对提高砼耐久性更有意义。作者从宏观和微观两方面研究了磷铝酸盐水泥浆体的抗冻性,同时与硅酸盐水泥、硫铝酸盐水泥浆体进行了比较;采用压汞测孔方法测试了三种水泥浆体冻融前后的孔结构,并用分形理论分析了各自特征。结果证实:磷铝酸盐水泥具有优越的抗冻融性能,其自身优良的水化特性以及体系的低碱度是良好抗冻性的内在原因。     

料温对RIM交联型聚氨酯脲结构与性能的影响

采用便携式微型反应注射成型机制备了一组料温分别为３０，４０，５０，６０℃的交联型聚氨酯脲。用ＤＳＣ和力学性能对试样进行表征的结果表明：料温提高有利于软、硬微相的混合，而硬链段微区的有序性变差。反映在宏观力学性能上则表现为：试样的拉伸强度提高，伸长率在５０℃料温时出现极大值，弯曲强度和弯曲模量则出现最小值。料温为３０℃时，物料混合不充分，随着料温升高，混合逐渐均匀，试样透明度提高。     

传热设备自动清洗纽带的开孔结构优化研究

对设有开孔结构的自转清洗纽带进行了传热特性及流阻特性研究。结构优化试验的结果表明 :摩擦阻力和传热强化都随开孔面积比率的增大表现出先上升后下降的趋势 ,传热强化的幅度在 2 %— 18%之间 ,摩擦阻力系数在开孔率 18%时最大 ,其中 7#开孔比率纽带的综合性能最佳。因此 ,这种开孔结构的纽带更宜用于中低Re工况下应用 ,在 2 .0m/s以上的高流速工况下应采用高开孔率结构的纽带或螺旋带