λ／4介电型吸波体材料参数的优化设计

λ／4型电磁波吸收体以其结构简单,易于制备和吸收效果好等优点被广泛关注,因此其性能设计至关重要。本文根据电磁波吸收理论提出简化K值设计法,并深入探讨了λ／4型吸波体电磁参数的选择原则和优化设计方法。     

谐振子含量变化引起的反射与吸收多效应

研究了含有谐振子和损耗介质的环氧树脂基复合材料对电磁波的反射与吸收效应。对具有不同谐振子含量的复合材料的微波反射率测试结果表明:复合材料中谐振子的含量达到某一临界值 V_(fc)时,呈现对电磁波吸收至反射的转变效应,对于铁氧体填充的环氧树脂基复合材料,当铁氧体的体积含量为70%时,V_(fc)=0.4%,实验发现:V_(fc)依赖于材料的介电特性,复数介电常数虚部越小,V_(fc)越大,对于复数介电常数虚部很小的材料,由吸收向反射的转变是逐渐过渡的,V_(fc)存在一个较宽的范围。分析表明:当谐振子含量 V_f 增大时,出现吸收与反射转变效应,与体系的快极化电容增加以及谐振子感应场的相互作用增强有关。     

Co@CNT复合电磁波吸收剂的制备及其吸波性能

以石墨相氮化碳(g-C₃N₄)和六水合硝酸钴为原料制备Co@CNT复合电磁波吸收剂,调节Co元素含量以提高其电磁波吸收性能。采用X射线衍射(XRD)、X射线光电子能谱(XPS)、拉曼光谱、扫描电镜(SEM)、能谱分析(EDS)和透射电镜(TEM)等手段表征其微结构和物相组成,使用矢量网络分析仪测量复合物电磁参数并进行Matlab模拟得到反射损耗图。结果表明,Co@CNT-1与石蜡质量比为1：3的材料,其吸波性能最优,厚度为4.1 mm时对电磁波的吸收最强,最小反射损耗(RL_min)为-45.5 dB;厚度仅为1.5 mm的材料,有效吸收带宽(RL<-10 dB)最大为4.42 GHz。     

MgFe2O4/Fe2O3纳米粉的溶胶-凝胶法合成及电磁波吸收特性

用热分解柠檬酸盐凝胶的方法制备了MgFe2O4／Fe2O3复合纳米粉体,用综合热分析仪、X射线衍射仪、透射电镜、纳米粒度测量仪、电磁测量仪对所制备样品的结构、粒径分布、电磁波吸收特性等进行表征。结果表明,产物为平均粒径44nm的MgFe2O4和Fe2O3的混合物,在0．1、1．0和1．8GHz处tgδ（ε″＋μ″/μ′）分别为0．206、0．265及0．614。     

基于S型曲线比较法的项目管理

评价项目进度控制好坏的依据,主要是整个项目实施时间的长短,为了解决工程需要投入的资金和人工成本浪费较大的问题,在最小的投入机成本前提下使利润实现最大化。本文将项目进度控制的理论和方法应用在工程项目的实证分析中,以期为类似项目实施进度控制提供一定的参考和借鉴。分析了人员、机械设备、技术及环境因素对项目进度的影响,设计了该工程项目进度控制,采用S形曲线法分析了项目进度控制过程,本文提出了工程项目进度控制体系保障措施。     

多组分核壳型空心微球的制备及其电磁波吸收性能研究

制备了空心玻璃微珠@聚吡咯(HGS@PPy)和空心玻璃微珠@Fe3O4@聚吡咯(HGS@Fe3O4@PPy)两种空心核壳结构材料。前者是通过对空心玻璃微珠进行氨基化改性,富集单体后在水/乙醇/5-磺基水杨酸/氯化铁的引发-掺杂体系中进行原位化学氧化聚合反应而制得的;后者是采用共沉淀法在空心玻璃微珠表面沉积Fe3O4后通过聚合反应包覆聚吡咯而制得的,粗糙的Fe3O4沉积层在包覆聚吡咯后变得紧实致密。表征了材料的核壳结构、组分含量、形貌及性能。所得材料具有轻质、导电和磁性能佳的特点,作为导电填料和电磁波吸收材料具有广阔的应用前景。     

预防沥青路面反射裂缝施工中应力吸收层的分析与运用

针对沥青路面裂缝处治的问题,目前还没有非常有效的方法,但是可以在裂缝未出现前就采取预防措施,推迟裂缝的产生,以延长沥青路面的使用寿命,主要结合近年来的工作情况介绍橡胶沥青应力吸收层SAMI和高弹性改性沥青应力吸收层SAWFTL在预防沥青路面反射裂缝中的应用。     

陶瓷型铁电复合物厚片介电系数的电场依赖性

建立起高压介电测试装置和相应的数据处理方法。研究了PZT/P (VDF-T rFE) 和PT/P (VDF- rFE) 0-3型铁电复合物厚片介电系数的电场依赖性。对于陶瓷体积分数U> 0.3 的复合物, 介电系数随测试场强的升高明显增大。在U< 0.1 时, 可用M axw ell-Garnet t 方程拟合试验结果。B ruggeman 方程适合于低电场(< 1MV/m ) 下复合物介电系数的预测。通过L z 的变化, 用Yamada 模型可拟合复合物介电系数随电场变化的关系, 说明L z 是由复合物的组分维数、粒子形状以及粒子间静电相互作用所决定的参数。      

聚苯胺与Si/C/N复合粉体的制备及其微波介电特性

用原位合成法在Si/C/N纳米粉表面包覆聚苯胺,制备出聚苯胺与Si/C/N复合材料,复合粉体近似球形,粒径为1～3μm.研究了聚苯胺与Si/C/N复合粉在8.2～12.4GHz的微波介电特性,与纳米Si/C/N相比,聚苯胺与Si/C/N复合粉体的ε′、ε"和tanδ有所增加,ε′在5.16～5.88范围内波动,ε"的变化范围为1.96～2.53,介电损耗角正切值达到了0.43,具有较好的微波介电特性.在8～12.4GHz范围内随频率的增加,聚苯胺与Si/C/N复合粉体的ε′、ε"和tanδ值均出现频响效应,是较为理想的微波吸收材料.     

建筑室内S带电磁污染控制板材的薄形化研究

本文报道了基于k／4型电磁波吸收原理,通过理论设计和模拟分析,以石膏板为介电材料,采用住相调制膜设计制备吸波体,成功实现了电磁波吸收体的薄化。研究表明,多边形及圆环形位相调制膜结构都可以实现吸收体的薄化和吸收宽化,但多边形效果更好。实验表明,环宽度15mm,间距为10mm的正六边形三环结构膜可以实现在2．2GHz附近,达到-25dB吸收,并呈现更大宽化,整体-10dB带宽达到70％且可减少介电层厚度15％。新材料可用于室内电磁环境的改善和污染控制。     

Master Curve implementation of the warm pre-stress effect

The Master Curve (MC) methodology has evolved from only being a brittle fracture testing and analysis procedure to a technological tool capable of addressing many more structural integrity issues like constraint and parameter transferability. One issue that not yet has been covered by the MC is the warm pre-stress (WPS) effect. This effect, which is known to produce an effective increase in fracture toughness, may be of great importance for some structural safety assessment situations where thermal transients are involved. Here, the WPS effect is re-examined and implemented into the MC methodology, by introducing a new simple WPS equation.     

关于曲线检测的探讨

曲线测量一直是几何计量中的一个重点 ,本文阐述了已知曲线和未知曲线测量原理 ,利用 B样条拟合曲线 ,以及如何借助最小二乘对测量值 (二维 )进行最佳拟合和偏差处理     

Uniqueness and rotation ambiguities in Multivariate Curve Resolution methods

The presence of rotation ambiguities and unique solutions in Multivariate Curve Resolution (MCR) chemometric methods is discussed in detail. Using recently proposed graphical approaches to display the bands and areas of feasible solutions in a subspace of reduced dimensions, the results obtained by different MCR methods are compared. These results show that in the presence of rotation ambiguities and under a particular set of constraints, the solutions obtained by the different MCR methods can differ among them and also from the true solution depending on initial estimates and on the applied algorithm. In absence of rotational ambiguities, all MCR methods should give the same unique solution which should be equal to the true one. Many of the MCR methods proposed in the literature like MCR-ALS, RFA, MCR-FMIN, or MCR-BANDS are confirmed to give a valid solution within the band or area of feasible solutions. On the contrary, and according to the results of this study, in its present implementation, the minimum volume simplex analysis, MVSA method can give unfeasible solutions when resolving bilinear data systems with more than two components, because it only applies non-negativity constraints to concentration profiles and not to spectral profiles.     

LAFFER'S CURVE理论与产业结构调控研究

在拉弗曲线理论的基础上,将过去的单目标静态最佳税率点,拓展为多目标动态税率调控区间,为实现产业结构优化与调控开辟了新的探索空间.在此基础上论证了GDP、私人部门收入、公共部门收入最大化之间的内在特征与相互联系,证明了它们不可能在任何相同的税率点同时达到最大化.     

Validation and application of the Master Curve and reconstitution techniques to a Spanish nuclear vessel

In this work, a methodology based on the Master Curve approach and the reconstitution of specimens is validated and applied to the vessel base metal of the currently in service Spanish boiling water reactor of the Santa María de Garoña nuclear power plant. The extensive experimental program performed consisted in the characterisation of the ductile to brittle transition region with standard and reconstituted specimens using subsized compact tension and Pre-Cracked Charpy V-notch specimens, under non-irradiated and irradiated conditions. Experimental results validated the reconstitution technique down to inserts of 10 mm which allows specimen reorientation and therefore, the comparison of LT and TL material orientations. The 110 specimens tested in this program allowed the Master Curve approach to be validated for the base steel of Santa María de Garoña nuclear power plant. By comparing the results for the compact and Pre-Cracked Charpy V-notch specimens, the existence of a systematic bias between these two geometries has been analysed. Although the neutron irradiation effect on the condition studied is predicted to be very limited (due to the small fluence), the results did allow the irradiation-induced shift of the ductile to brittle transition temperature to be detected. Comparison between the directly measured fracture toughness and the conventional semi-empirical approach proposed by the ASME Code reveals the overconservatism of the latter approach.     

翻领成形器交接曲线简化函数的研究

导出翻领成形器交接曲线的简化函数，为进一步完善该形器的数学模型及简化计算过程奠定了基础。     

显影温度与X射线胶片特性曲线的关系

利用工业X光机和Array 2905HD扫描仪,研究了两种显影液老化对几种常用工业X射线胶片感光特性曲线的影响关系。     

一种利用曲线结构和三角法进行指纹快速点模式匹配的算法研究与实现

针对指纹的点模式匹配方法中如何确定两枚指纹的比对基准参考点问题,提出了一种基于指纹的纹线结构与三角形方法相结合的方法。实验结果表明,该算法在保留了点模式匹配方法优点的同时有效地提高了匹配速度。