舰船辐射噪声超混沌现象研究

水下弱目标探测和识别一直是水声信号处理领域中研究的难点。从Lyapunov指数谱、吸引子相空间轨迹的演化、分形维数等方面，对船舶辐射噪声是否存在超混沌现象进行了研究。实验结果表明，船舶辐射噪声信号确实存在至少两个正的Lyapunov指数，即存在超混沌现象。辐射噪声吸引子在相空间中的轨迹具有多方向伸展的趋势，且不同类型目标的吸引子具有不同的分形维数。研究结果为建立精确描述辐射噪声信号的非线性模型、为水下弱目标信号探测和识别提供一定的理论依据。     

147Pm激发的ZnS：Cu,Cl发光粉的研究

以高纯ZnS粉末为基质,采用高温转相、扩散,以及表面涂敷工艺,制得了¹⁴⁷Pm激发的ZnS:Cu,Cl发光粉。分析了ZnS:Cu,Cl的晶体结构,测量了ZnS:Cu,Cl的激发光谱、发射光谱、发光亮度。其晶体结构主要是六方纤锌矿型结构,激发光谱峰值波长为341nm,发射光谱峰值波长为513nm,初始发光亮度达到312mcd/m₂。由激发光谱的峰值波长341nm推算得到六方ZnS晶体的禁带宽度为3.64eV。分析了¹⁴⁷Pm激发的ZnS:Cu,Cl发光粉的发光寿命,其发光寿命达到5年以上。还探讨了该放射性发光粉的发光机理。¹⁴⁷Pm激发的ZnS:Cu,Cl的稳定发光,实际上是激发过程与复合过程的准平衡。ZnS:Cu,Cl的绿色发光来源于深施主-深受主对的复合发射。实验结果的分析表明,ZnS:Cu,Cl中深施主-深受主之间的能级间隔约为2.42eV。     

High performance oscillator with 2-mW output power at 300 GHz

Material structures and device structures of a 100-GHz InP based transferred-electron device are designed in this paper. In order to successfully fabricate the Gunn devices operating at 100 GHz, the InP substrate was entirely removed by mechanical thinning and wet etching. The Gunn device was connected to a tripler link and a high RF(radio frequency)output with power of 2 mW working at 300 GHz was obtained, which is high enough for applications in current military electronic systems.     

不同中心波长飞秒脉冲激发InAs表面辐射太赫兹波的机理研究

研究了p型(100)InAs在不同中心波长飞秒激发光(750—850nm)作用下的太赫兹(THz)波辐射特性.这种太赫兹辐射的光谱性质与光学Dember效应密切相关，飞秒脉冲激发下产生的载流子在InAs表面的Dember场内做加速运动，从而辐射出THz电磁波.实验结果表明：不同中心波长的激发光作用下，InAs表面产生的Dember电场、光生载流子浓度、谷间散射效应以及处于不同状态的载流子数目都发生了变化，因而激发出太赫兹波的功率、振幅、频谱分布和有效谱宽是不同的.这项研究将有利于THz时域光谱技术以及实验     

剪切形变下掺杂及缺陷对MoS2电子结构的影响

本文利用密度泛函理论,研究剪切形变下掺杂改性及不同类型缺陷对MoS2电子结构的影响。发现：剪切形变下,MoS2+P体系为相对最稳定的结构,掺杂改性相较于缺陷对模型稳定性影响更小;模型MoS2+P+Se中P-Mo键易形成共价键,而其中的Se-Mo键和MoS2+P-Mo-S模型中的P-Mo键,易形成离子键;掺杂使MoS2模型能隙变大,而缺陷使能隙减小,且S和Mo原子共缺陷的模型带隙为0;缺陷相较于掺杂改性模型,更能使Mo原子周围增加电荷聚集度,带隙值更低,更能影响或调控模型的电子结构。     

Electronic and optical properties of 3N-doped graphdiyne/MoS2 heterostructures tuned by biaxial strain and external electric field

The construction of van der Waals (vdW) heterostructures by stacking different two-dimensional layered materials have been recognised as an effective strategy to obtain the desired properties. The 3N-doped graphdiyne (N-GY) has been successfully synthesized in the laboratory. It could be assembled into a supercapacitor and can be used for tensile energy storage. However, the flat band and wide forbidden bands could hinder its application of N-GY layer in optoelectronic and nanoelectronic devices. In order to extend the application of N-GY layer in electronic devices, MoS₂ was selected to construct an N-GY/MoS₂ heterostructure due to its good electronic and optical properties. The N-GY/MoS₂ heterostructure has an optical absorption range from the visible to ultraviolet with a absorption coefficient of 10⁵ cm^-1. The N-GY/MoS₂ heterostructure exhibits a type-Ⅱ band alignment allows the electron-hole to be located on N-GY and MoS₂ respectively, which can further reduce the electron-hole complexation to increase exciton lifetime. The power conversion efficiency of N-GY/MoS₂ heterostructure is up to 17.77%, indicating it is a promising candidate material for solar cells. In addition, the external electric field and biaxial strain could effectively tune the electronic structure. Our results provide a theoretical support for the design and application of N-GY/MoS₂ vdW heterostructures in semiconductor sensors and photovoltaic devices.     

平面常宽凸集的Firey-Sallee定理

常宽凸集是一类广泛应用在机械设计、医学等领域的特殊几何图形.本文探讨平面中的常宽凸集,简化证明著名的Firey-Sallee定理,即宽度相等的正Reuleaux多边形中Reuleaux三角形的面积最小.     

7-(苯并噻唑-2-偶氮)-8-羟基喹啉-5-磺酸与镉显色反应的研究和应用

在 p H4 .8的邻苯二甲酸氢钾 - Na OH介质中 ,非离子表面活性剂 Tween- 80存在下 ,7- (苯并噻唑 - 2 -偶氮 ) - 8-羟基喹啉 - 5 -磺酸 (BTAQS)与镉形成 2∶ 1的紫红色配合物 ,其最大吸收波长 λmax=5 6 0 nm,表观摩尔吸光系数为 8.71× 10 4L· mol-1·cm-1,镉含量在 0— 6 μg/ 10 m L范围内服从比耳定律。用于矿样中镉的测定 ,相对误差小于 3% ,相对标准偏差小于 2 .5 % (n=5 )。     

土工聚合物减小土体差异沉降的机理及最佳埋置深度的计算

以弹性理论为基础,分析讨论了利用土工聚合物减小土体差异沉降的机理和土工聚合物最佳埋置深度的确定方法．