水下声学浮标南中国海海洋环境噪声实测分析

海洋环境噪声是多种自然噪声和人为噪声的复杂组合,其谱级大小和频率组成是影响声呐系统探测性能的重要参数,鉴于海洋环境噪声时空域特性非常复杂,需要对海洋环境噪声进行长时间和大范围的观测才足以分析其特性。该文通过在多剖面水下浮标平台基础上集成声学测量系统,研制了一种具有海洋环境噪声监测能力的水下声学浮标平台,该浮标平台可多次上浮、下潜,具备原位坐底和定深漂流两种工作模式,能连续观测海洋环境噪声时长多达数月。利用2019年8月在南中国海海区组织的多台水下声学浮标试验某一天的数据,给出了20 Hz、63 Hz、100 Hz、200 Hz、400 Hz、800 Hz、1.6 kHz和3.15 kHz 8个频点中心处海洋环境噪声谱级随时间变化,讨论了附近航船噪声对其的干扰影响。试验表明,水下声学浮标可作为一种潜在的优势水下漂流移动平台,用于监测关注海域海洋环境噪声特性。     

插值法在低温温度测量中的应用

依托建立的低温精馏装置,针对低温环境中温度测量问题,提出一种基于LabVIEW的低温温度测量方法。该方法将插值法引入到数据分析中,通过软件编程实现数据处理、显示、存储等功能。经过理论分析与实验对比,该方法准确度提高到0.01 K,可移植性强,是低温环境中温度测量的可行方法。     

修饰酶电极的响应特性

在考虑电极电位、浓度极化等影响因素的情况下, 提出了介体型酶电极响应的数学表达式, 并对吸附法制备的修饰酶电极进行了初步的实验验证和模拟计算, 其实验结果与理论推导是一致的.     

Developing cold-resistant high-adhesive electronic substrate for WIMPs detectors at CDEX

Herein we report a prototypical electronic substrate specifically designed to serve the weakly interacting massive particles(WIMPs)detectors at the China Dark Matter Experiment(CDEX).Because the bulky high-purity germanium(HPGe)detectors operate under liquid-nitrogen temperatures and ultralow radiation backgrounds,the desired electronic substrates must maintain high adhesivity across different layers in such cold environment and be free from any radioactive nuclides.To conquer these challenges,for the first time,we employed polytetrafluoroethylene((C2F4)n)foil as the base substrate,in conjunction with ion implantation and deposition techniques using an independently developed device at Beijing Normal University for surface modification prior to electroplating.The remarkable peeling strengths of 0.88±0.06 N/mm for as-prepared sample and 0.75±0.05 N/mm for that after 2.5-days of soaking inside the liquid nitrogen were observed,while the regular standards commonly require 0.4 N/mm^0.6 N/mm for electronic substrates.     

An Infrared Metamaterial Broadband Absorber Based on a Simple Titanium Disk with High Absorption and a Tunable Spectral Absorption Band

A metamaterial absorber is proposed that functions in the medium- (3–5 µm) and long-wavelength (8–12 µm) infrared (medium-wavelength infrared, MWIR, and long-wavelength infrared, LWIR, respectively) regions. The proposed design, which consists of periodic cells, can be tuned to achieve single-band or dual-band light absorption by changing the periodicity of the structure. Each cell forming the metamaterial absorber consists of a bottom metal plate (Al), a top metal disk (Ti), and an intermediate dielectric medium (Si or ZnS) in which a metal disk (Ti) is embedded. For a period of 0.85 µm, the absorber achieves broadband absorption in the LWIR region, with an average absorption of 92.1%. Further, the absorber shows acceptable tolerance to irradiation at oblique incidence. For a period of 2 µm, a peak absorption of 99.05% is achieved in the MWIR region, thereby providing dual-band absorption. Tuning the periodicity of the structure enhances the localized surface plasmon resonance, with the absorption mechanism explained by establishing an equivalent parallel LC circuit. The absorption properties demonstrated by the proposed metamaterial absorber are promising for thermal imaging and infrared spectroscopy.     

饱和多孔弹性Timoshenko梁的大挠度分析

基于微观不可压饱和多孔介质理论和弹性梁的大挠度变形假设,考虑梁剪切变形效应,在梁轴线不可伸长和孔隙流体仅沿轴向扩散的限定下,建立了饱和多孔弹性Timoshenko梁大挠度弯曲变形的非线性数学模型.在此基础上,利用Galerkin截断法,研究了两端可渗透简支饱和多孔Timoshenko梁在突加均布横向载荷作用下的拟静态弯曲,给出了饱和多孔 Timoshenko梁弯曲变形时固相挠度、弯矩和孔隙流体压力等效力偶等随时间的响应.比较了饱和多孔Timoshenko梁非线性大挠度和线性小挠度理论以及饱和多孔 Euler-Bernoulli梁非线性大挠度理论的结果,揭示了他们间的差异,指出当无量纲载荷参数q＞l0时,应采用饱和多孔Timoshenko梁或Euler-Bernoulli梁的大挠度数学模型进行分析,特别的,当梁长细比λ＜30时,应采用饱和多孔Timoshenko梁大挠度数学模型进行分析.     

具有弱界面特性叠层压电球壳的自由振动

针对具有弱界面的叠层压电球壳自由振动,引入两个位移和应力函数,从三维压电弹性理论基本方程出发建立了分别对应于两类振动形式的独立状态方程,并通过球面谐函数展开技术以及近似层合模型将其化为关于径向坐标的常系数状态方程.采用弱界面模型建立状态向量的界面传递关系,与层内传递关系得到球壳内外状态变量的整体传递关系.最后考虑球壳内外边界自由条件,得到了两类振动形式的频率方程.通过与已有精确解的比较验证了论文解的准确性,数值详细表明弱界面弹性柔性系数的大小对叠层球壳自振频率有较大影响,但弱界面导电性的高低对自振频率的影响不大.     

An alternative interpretation of the optical spectra for Fe-doped KTaO3 crystals

In this paper, the excitation spectrum and luminescence at 14 569, 17 225, 18 829 and 14 659 cm^-1 for Fe³⁺ ion at the K⁺ site of KTaO₃ crystals are assigned, respectively, to the ⁶A₁(S)→⁴T₁(G), ⁴T₂(G), ⁴E₁(G)[⁴A₁(G)] and ⁴T₁(G)→⁶A₁(S) transitions rather than to the ⁶A₁(S)→⁴T₁(G), ²T₂(I), ⁴T₂(G) and ⁴T₁(G)→⁶A₁(S) transitions given in a previous paper [Bryknar et al., Radiat. Eff. Def. Solids 149(1999)51]. On the basis of this assignment, the reasonable optical spectrum parameters (in particular, the cubic field parameter Dq≈−640 cm⁻¹) are obtained. The validity of this assignment is discussed.