某型雷达旁瓣抑制电路抗干扰分析

旁瓣对消是雷达抗有源干扰的有效方法。文章介绍了某型雷达旁瓣抑制电路的组成,分析了其基本的对消原理,并进行了计算机仿真,最后,给出了对几种有源压制干扰的对消结果。仿真结果表明,该旁瓣抑制电路具有很好的抗旁瓣干扰能力。     

Optical properties of two-dimensional perovskites

The optical properties of two-dimensional (2D) perovskites recently receive numerous research focus thanks to the strong quantum and dielectric confinement effects. In addition to the strong excitonic effect at room temperature, 2D perovskites also have appealing features that their optical properties can be flexibly tuned by alternating organic or inorganic layers. Particularly, 2D chiral perovskites and 2D perovskites based heterostructures are emerging as new platforms to extend their functionalities. To optimize performance of 2D perovskites-based optoelectronic devices, it is critical to understand the fundamentals and explore the strategies to engineer their optical properties. This review begins with an introduction to the excitons and self-trapped excitons of 2D perovskites. Subsequently, inorganic/organic layer effects on optical properties and 2D perovskites based heterostructures are discussed. We also discussed the nonlinear optical properties of 2D perovskite. We are looking forward to that this review can stimulate more efforts to understand and optimize the optical properties of 2D perovskites.     

原子系统中偶极-偶极相互作用对量子存储支撑熵不确定度的调控研究

本文研究了Markovian过程和non-Markovian过程两种情况下,原子系统中偶极-偶极(D-D)相互作用和失谐量对两原子系统量子存储支撑(QMA)熵不确定度的调控作用.与Markovian过程相比,在non-Markovian过程中,由于库环境的记忆效应使得具有D-D相互作用的两原子系统QMA熵不确定度的演化行为呈现出振荡上升现象,且熵不确定度的上升趋势得到减缓,从而抑制了由系统量子噪声引起的退相干效应.此外,D-D相互作用对两原子系统QMA熵不确定度具有显著的调控能力,且D-D相互作用比失谐量的调控能力更强.     

综合自动测试系统集成策略

从应用需求的角度来描述现代军用自动测试系统的组成与发展 ,并对自动测试系统的集成过程加以描述 ,从而讨论现阶段我国军用综合自动测试系统集成的策略。     

声表面波滤波器教学与学生综合能力培养的探索

针对声表面波滤波器知识点教学环节中存在的问题,本文结合本科生综合能力培养这一宗旨,将声表面波滤波器的基本原理、器件结构、器件设计等授课和实验环节,与学生的文献检索、整理,科技论文撰写,工具软件使用等综合能力培养紧密联系在一起,加深了学生对声表面波滤波器知识的掌握,提高了学生的综合能力。此外,这种综合能力的培养在一定程度上解决了其它课程学习、毕业设计中存在的不会利用文献检索工具,不会进行科技论文撰写等问题。     

Synthesis and mesomorphic properties of mesogens containing 1,1,2,2-tetrahydroperfluorodecaoxy terminal chains

One series of two-ring and two series of three-ring mesogens with 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10-heptadecafluorodecaoxy terminal chains containing tolane or biphenyl units have been synthesized. Their mesomorphic properties were observed and measured by optical polarizing microscopy and differential scanning calorimetry. The three-ring mesogens only exhibit a wide smectic C phase when the length of their hydrocarbon chains is intermediate.     

Dislocation decoration and raft formation in irradiated materials

Experimental observations of dislocation decoration with self-interstitial atom (SIA) clusters and of SIA cluster rafts are analysed to establish the mechanisms controlling these phenomena in bcc metals. The elastic interaction between SIA clusters, and between clusters and dislocations is included in kinetic Monte Carlo (KMC) simulations of damage evolution in irradiated bcc metals. The results indicate that SIA clusters, which normally migrate by 1D glide, rotate due to their elastic interactions, and that this rotation is necessary to explain experimentally-observed dislocation decoration and raft formation in neutron-irradiated pure iron. The critical dose for raft formation in iron is shown to depend on the intrinsic glide/rotation characteristics of SIA clusters. The model is compared with experimental observations for the evolution of defect cluster densities (sessile SIA clusters and nano-voids), dislocation decoration characteristics and the conditions for raft formation.     

Magnetic properties and magnetocaloric effects in amorphous and crystalline Gd55Co35Ni10 ribbons

The magnetic properties and magnetocaloric effects of amorphous and crystalline Gd55Co35Ni10 ribbons are investigated.A main phase with a Ho 12 Co 7-type monoclinic structure(space group P21/c) and a minor phase with a Ho4Co3-type hexagonal structure(space group P63/m) are obtained for crystalline ribbon after annealing.The amorphous ribbons order ferromagnetically and undergo a second-order transition at 192 K.For crystalline Gd55Co35Ni10 ribbons,two magnetic phase transitions occur at 158 and 214 K,respectively.The peak value of-△SM under a field change of 0-5 T is 6.5 J/kg K at 192 K for amorphous Gd55Co35Ni10 ribbons.A relatively large magnetic entropy change(～5.0 J/kg K) under a field change of 0-5 T for the crystalline Gd55Co35Ni10 ribbons is obtained in the temperature interval range of 154-214 K.The large platform of magnetic entropy change and the negligible thermal/magnetic hysteresis loss mean the crystalline Gd55Co35Ni10 compound can satisfy the requirement of the Ericsson-type refrigerator working in the temperature range from 154K to 214K.     

Synthesis of mikto‐topology star polymer containing one cyclic arm

Well‐defined mikto‐topology star polystyrene composed of one cyclic arm and four linear arms was synthesized by a combination of atom transfer radical polymerization (ATRP) and Cu‐catalyzed azide‐alkyne cycloaddition (CuAAC) click reaction. First, the bromine‐alkyne α,ω‐linear polystyrenes containing four hydroxyl groups protected with acetone‐based ketal groups were synthesized by ATRP of styrene using a designed initiator. Then, the bromine end‐group was converted to the azide and the linear polystyrene was cyclized intra‐molecularly by the CuAAC reaction. The four hydroxyl groups were released by deprotection and then esterified with 2‐bromoisobutyryl bromide to produce a cyclic polymer bearing four ATRP initiating units. By subsequent ATRP of styrene to grow linear polymers with the cyclic polystyrene as a macroinitiator, the mikto‐topology star polymers were prepared. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012