基于混合范数约束的非均匀稀疏水声信道估计方法*

水声信道具有明显的簇状稀疏特性,即稀疏的信道冲激响应大部分为零或接近零的小值系数,而非零值系数是以簇的形式非均匀分布于时延域。为此本文提出了一种基于非均匀混合范数约束仿射投影算法的水声信道估计方法。该方法首先根据信道簇状结构对其进行非均匀分组,基于此将范数约束规则加入仿射投影算法中,具体方法为：对簇状部分施加范数约束,有效提高系数间的相关性,而簇状结构与其他零值抽头之间利用范数约束实现了整体的稀疏特性。数值仿真以及深海远程水声通信实验数据处理结果表明了本文所提出的水声信道估计算法相较现有稀疏信道估计方法能够实现更快的收敛速度以及更高精度的信道估计结果。     

Radiative Constants in the W VII Ion Spectrum

Optics and Spectroscopy - The probabilities of the 4 f 135p66p + 4 f 145p56p – 4 f 136s, 4 f 137s radiative transitions...     

扩散场重建格林函数检测钢轨近表面缺陷*

利用超声相控阵全矩阵捕获功能获取后期时间的扩散场信息,实现钢轨近表面缺陷成像。对扩散场信号进行互相关,重建阵元之间的格林函数,获取阵元之间未延时的响应,恢复被噪声湮没的早期缺陷信息,将波数成像方法用于近表面缺陷的快速成像。采用两种超声相控阵探头在钢轨表面采集实验数据,说明格林函数恢复效果与相控阵阵元的个数和激励频率有关。实验结果清晰地显示了距钢轨表面5～10 mm处的缺陷,证实了互相关方法重建格林函数对近表面缺陷检测的有效性。     

Synthesis,Structure, and Thermophysical Properties of Pb10 – xBix(GeO4)2 + xVO4)4 – x (x = 0–3) in the Temperature Range of 350–950 K

Physics of the Solid State - The Pb10 – xBix(GeO4)2 + x(VO4)4 – x (x = 0–3) compounds with an apatite structure have been...     

Ab Initio Study of the Structural Properties of the Co–Ni–Sn Heusler Alloys

Physics of the Solid State - The ab initio investigations of the structural and magnetic properties of the Co2Ni1 + xSn1 – x (x = 0,...     

The Influence of Interstitial Carbon and Oxygen on Grain Boundary Diffusion in Nickel and Silver

Russian Physics Journal - The paper investigates the influence of interstitial carbon and oxygen atoms on their diffusion along the <111>, <100> and <110>...     

Decomposition of Higher-Order Equations of Monge–Ampère Type

It is demonstrated that the fourth-order PDE

A study of conformationl transformations in guttapercha by infrared spectroscopy

The infrared spectra of crystalline - and -guttapercha, and also of molten guttapercha, were studied in the 400–1700 cm^–1 range. It is shown that the IR spectra of the two crystalline modifications exhibit marked differences. The absorption bands characterizing the crystalline - and -forms were determined. The crystalline bands were used to determine the melting points of the two forms. It is shown that stretching of the -form produces a more elongated rotational isomer, i. e., guttapercha; the -form is produced by recrystallization of the -form. The dichroism of the C=C valence vibrations observed in the spectrum of oriented guttapercha indicated that the molecular chains of the -form have a spiral conformation. Guttapercha, i. e., trans-polyisoprene exists in crystalline form at room temperature.     

Detection of Surface States in Bi2 – xSbxTe3 – ySey Topological Insulators by Magnetotransport Measurements

Physics of the Solid State - In this paper, we studied the effect of the magnetic field and temperature on conductivity of Bi2 ‒ xSbxTe3 – ySey...     

井旁溶洞的偶极反射声波测井响应研究*

反射声波成像测井是适应复杂地区勘探开发的一种测井新技术,能够对井旁几米至几十米内声阻抗不连续的地层界面、裂缝、溶洞、盐丘等不同地质构造进行探测评价。针对井旁存在一个不同尺度大小的溶洞时的偶极反射声波测井响应进行了数值模拟,得到了不同情况下的回波信号,探究了地层横波波长与井旁溶洞尺度之间的关系。研究结果表明,等源距阵列波形中,溶洞的回波波列有特殊的"抛物线"型形态,上提过程中距溶洞最近时,回波到时最早、幅度最大。当井旁溶洞直径逐渐增大时,回波信号幅度越强,反射横波偏移成像的结果越清晰。通过该研究,初步形成了一种反射声波测井评价井旁溶洞的方法。     

Martensitic Transformation,Magnetotransport Properties,and Magnetocaloric Effect in Ni47 – xMn42 + xIn11 Alloys (0 ≤ x ≤ 2)

Physics of the Solid State - The structure, electrical and magnetic properties of Ni47 – xMn42 + xIn11 (0 ≤ x ≤ 2) alloys upon changing the...     

H/D Isotope Effect in the Conductivity of CaZr1 – xScxO3 – α in Reducing Atmospheres

Physics of the Solid State - The ionic (proton and deuteron) conductivity of the system CaZr1 – xScxO3 – α (x = 0.03–0.20) is studied...     

Customer Sojourn Time in GI / GI / 1 Feedback Queue in the Presence of Heavy Tails

Journal of Statistical Physics - We consider a single-server GI / GI / 1 queueing system with feedback. We assume the service time distribution to be...     

Photothermal Effect of Infrared (808 nm) Laser Radiation and Gold Nanoparticles in Different Modifications on S. aureus

Optics and Spectroscopy - A comparative study of the effect of infrared laser radiation (808 nm) of different power density on Staphylococcus aureus 209 P,...     

Theoretical Approach to Investigation of the Magnetic and Magnetocaloric Properties of Heusler Ni–Mn–Ga Alloys

Physics of the Solid State - The magnetic and magnetocaloric properties of Heusler Ni2 + xMn1 – xGa alloys (x = 0.16, 0.18, and 0.3) have been studied...     

Reflectivity and Photoreflectivity Spectra of Structures with Quantum Wells Based on ZnO

Physics of the Solid State - Reflectivity and modulated photoreflectivity spectra of ZnO and Zn1 – xMgxO epitaxial layers as well as ZnO/Zn1 – xMgxO...     

Haven Correlation Parameter for Diffusion of Fluorine in Superionic Conductors La1 – ySryF3 – y

Physics of the Solid State - The processes of electric charge transfer (conductivity) and mass transfer (diffusion) in La1 ‒ ySryF3 – y superionic...     

Iodine etching of the GaAs(1̄1̄1̄)As surface studied by LEED,AES, and mass spectroscopy

The iodine interaction with the GaAs(1̄1̄1̄)As surface prepared by molecular beam epitaxy has been studied by LEED, LEED intensity measurements, Auger electron spectroscopy (AES) and computer controlled mass spectroscopic study of the whole desorption spectrum. It is shown that an iodine beam hitting the GaAs(1̄1̄1̄)As face at 300 K under UHV conditions etches the surface continuously. After this etching there remains an adsorbate of GaI_x where x is a number between 0 and 3. By thermal desorption of this GaI_x adsorbate an As stabilized GaAs(1̄1̄1̄)As surface showing a (2 × 2) structure can be prepared, which up to the present could be done only by molecular beam epitaxy.     

基于深度约束的声速估算方法*

高精度的声速剖面数据是提高水下定位精度的关键。在无法精确获得声速剖面数据的情况下,该文提出了一种基于深度约束,同时根据浮标与水下目标的空间几何距离进行有效声速估算的方法。通过仿真模拟,将该文提出的方法与加权平均声速法、泰勒级数展开法和等效声速剖面法的定位结果进行对比分析。结果表明,新方法不需要依靠声速剖面数据,通过深度约束可有效地估算出声速值,其定位精度与等效声速结果相当,极大地提高了无声速剖面数据下的水下定位精度。     

Correction to: Dynamic Mach–Zehnder interferometer based on a Michelson configuration and a cube beam splitter system

Optical Review - The article Dynamic Mach–Zehnder interferometer based on a Michelson configuration and a cube beam splitter system written by A. Montes...