井田问题的探究

如图1所示,一块不规则的四边形田地ABCD,在每条边都取三等分点,再把两组对边上的三等分点连接起来,成了一个井字形.井字把这块田分成了九小块,正中间的那一块图形的面积正好是田地ABCD面积的1/9,     

Exploring Majorana zero modes in iron-based superconductors

Majorana zero modes (MZMs) are Majorana-fermion-like quasiparticles existing in crystals or hybrid platforms with topologically non-trivial electronic structures. They obey non-Abelian braiding statistics and are considered promising to realize topological quantum computing. Discovery of MZM in the vortices of the iron-based superconductors (IBSs) has recently fueled the Majorana research in a way which not only removes the material barrier requiring construction of complicated hybrid artificial structures, but also enables observation of pure MZMs under higher temperatures. So far, MZMs have been observed in iron-based superconductors including FeTe_0.55Se_0.45, (Li_0.84Fe_0.16)OHFeSe, CaKFe₄As₄, and LiFeAs. In this topical review, we present an overview of the recent STM studies on the MZMs in IBSs. We start with the observation of MZMs in the vortices in FeTe_0.55Se_0.45 and discuss the pros and cons of FeTe_0.55Se_0.45 compared with other platforms. We then review the following up discovery of MZMs in vortices of CaKFe₄As₄, impurity-assisted vortices of LiFeAs, and quantum anomalous vortices in FeTe_0.55Se_0.45, illustrating the pathway of the developments of MZM research in IBSs. Finally, we give perspective on future experimental works in this field.     

一种新颖的基于零知识证明的跨域DAA协议

In order to solve the issue that existing direct anonymous attestation (DAA) scheme can not operate effectively in different domains, based on the original DAA scheme, a novel direct anonymous attestation protocol used in multi domains environment is proposed and designed, in which, the certificate issuer located in outside of domain can be considered as a proxy server to issue the DAA certificate for valid member nodes directly. Our designed mechanism accords with present trusted computing group (TCG) international specification, and can solve the problems of practical authentication and privacy information protection between different trusted domains efficiently. Compared with present DAA scheme, in our protocol, the anonymity, unforgeability can be guaranteed, and the replay-attack also can be avoided. It has important referenced and practical application value in trusted computing field.     

数字经济背景下科技型在位企业商业模式演化策略研究

为探究数字经济背景下科技型在位企业商业模式演化策略选择的动态机制,基于商业模式冰山理论和演化博弈理论,以企业成本具有差异性为前提,借助Stackelberg竞争模型与Cournot竞争模型,分析了不同情形下企业商业模式演化的稳定均衡策略,并通过案例与仿真分析探讨了数字经济发展水平、数字化能力、数字化资源影响下企业商业模式演化策略选择的演化路径和演化稳定性。结果表明：数字经济发展水平、数字化能力和数字化资源是影响企业商业模式演化策略选择的重要因素;数字经济发展水平、数字化能力、数字化资源水平越高,企业越倾向于选择激进式商业模式演化;同一条件下,成本优势企业选择激进式商业模式演化的意愿更强烈;数字经济发展水平、数字化能力和数字化资源对企业商业模式演化策略选择的影响效果存在差异,数字经济发展水平的影响效果最为显著,数字化能力次之。相关研究结论可为数字经济背景下科技型在位企业商业模式演化提供决策依据。     

一种海洋通信频谱感知场景的仿真分析

可靠的海洋通信建立在高效利用有限的频谱资源基础上,认知无线网络体系提供了尽最大限度利用未被占用的无线频谱资源的可能.本文将序贯检测应用到海洋通信频谱感知场景中,通过仿真分析了在多船舶协作感知的情况下,该方法能有效地减少复杂的信号重构量,并大幅度降低了对高采样速率的要求.     

基于LabVIEW的时域抽样定理仿真实验

文章通过LabVIEW软件编程实现了时域抽样定理的仿真实验。界面简单明快,参数可调,程序具有扩展性,验证结果符合理论推导。通过实验编程能有效帮助学生深入理解傅立叶变换的概念,能准确应用时域抽样定理。     

基于工艺偏差的自旋转移矩辅助压控磁各向异性磁隧道结电学模型及其应用研究

自旋转移矩辅助电压调控磁各向异性磁隧道结(STT辅助VCMA-MTJ)作为非易失性全加器(NV-FA)中的核心部件,具有切换速度快、功耗低,稳定性好等优点,将在物联网、人工智能等领域具有良好的发展前景.然而随着磁隧道结(MTJ)尺寸的不断缩小以及芯片集成度的不断提高,工艺偏差对MTJ及NV-FA电路性能的影响将变得越来越显著.本文基于STT辅助VCMA-MTJ磁化动力学,在充分考虑薄膜生长工艺偏差以及刻蚀工艺偏差影响的情况下,建立了更为精确的STT辅助VCMA-MTJ电学模型,研究了上述两种工艺偏差对MTJ及NV-FA电路性能的影响.结果表明,当自由层厚度偏差γ_tf≥6%或氧化层厚度偏差γ_tox≥0.7%时,MTJ将无法实现状态切换;当隧穿磁阻率偏差β增大到30%时,读取裕度SM将下降高达17.6%.对于NV-FA电路,通过增大电压V_b1以及写‘0’时增大电压V_b2或写‘1’时减小V_b2,可有效降低非易失性加数写入错误率;通过增大逻辑运算驱动电压V_dd,可...     

石墨烯中选择性增强Kane-Mele型自旋-轨道相互作用

增强石墨烯中的自旋-轨道相互作用可能实现无耗散的量子自旋霍尔器件,这需要在石墨烯样品中引入独特的Kane-Mele型自旋-轨道相互作用,并保持较高的迁移率.然而,对石墨烯的外在修饰往往会引入“外禀型”Rashba自旋-轨道相互作用,会破坏可能存在的拓扑态,并带来一定程度的杂质散射,降低样品迁移率.在石墨烯表面修饰EDTA-Dy分子后,载流子迁移率得到了提高,并且可以看到显著的量子霍尔电导平台.其弱局域化效应相比被修饰之前得到了抑制,这意味石墨烯中可能引入了内禀的Kane-Mele型自旋-轨道相互作用,增强了Elliot-Yafet型电子自旋弛豫机制.进一步通过矢量磁体磁阻测量,发现该分子覆盖在石墨烯上后造成了石墨烯微弱的涟漪,这种涟漪引起的弯曲声子效应模拟了Kane-Mele型自旋-轨道相互作用.