Application of Transient Electromagnetic Method with Multi-Radiation Field Sources in Deep Edge Mineral Resources Exploration

In recent years,in order to meet the practical needs of deep edge mine detection with large depth and high precision,transient electromagnetic method(TEM)near emission source detection mode has become an international advanced method(Xue et al.,2020).

Transient numerical simulation of annealing process in a conjugate combined radiation conduction heat transfer

The annealing time is an important affecting factor in the performance of many furnaces.The present work deals with the transient simulation of annealing process in a cubic furnace in which a solid element is placed in its center.As the working gas can have some radiating features,a set of governing equations including the energy balance with the radiative transfer equation(RTE)for the gray radiating medium and the conduction equation inside the solid product are numerically solved with progressing in time.Numerical results which are validated against both analytical and theoretical findings in the literature demonstrate that during the starting period,a high rate of radiant energy transfers into the solid body even at small optical thickness.This behavior which hastens the rate of heat transfer at low values of the radiation conduction parameter,causes a fast annealing process in which the solid body warms up to its maximum temperature.Moreover,it is revealed that the rate of heat transfer is an increasing function of radiation-conduction parameter.

Conduction-radiation effect on transient natural convection with thermophoresis

This paper discusses the effect of thermophoretic particle deposition on the transient natural convection laminar flow along a vertical fiat surface, which is immersed in an optically dense gray fluid in the presence of thermal radiation. In the analysis, the radiative heat flux term is expressed by adopting the Rosseland diffusion approximation. The governing equations are reduced to a set of parabolic partial differential equations. Then, these equations are solved numerically with a finite-difference scheme in the entire time regime. The asymptotic solutions are also obtained for sufficiently small and large time. The obtained asymptotic solutions are then compared with the numerical solutions, and they are found in excellent agreement. Moreover, the effects of different physical pa- rameters, i.e., the thermal radiation parameter, the surface temperature parameter, and the thermophoretic parameter, on the transient surface shear stress, the rate of surface heat transfer, and the rate of species concentration, as well as the transient velocity, temperature, and concentration profiles are shown graphically for a fluid （i.e., air） with the Prandtl number of 0.7 at 20℃ and 1.013 × 10^5 Pa.

Study on the transient radiation for apertures excited by rectangle pulse

The analytic representation of the transient radiation for an aperture excited by a rectangle pulse is obtained. It shows that the field duration and amplitude depend on the observation distance, the elevation angle, the pulse width of the rectangle pulse and the aperture size.

Statistical Multiscale Analysis of Transient Conduction and Radiation Heat Transfer Problem in Random Inhomogeneous Porous Materials

This paper is devoted to the homogenization and statistical multiscale analysis of a transient heat conduction problem in random porous materials with a nonlinear radiation boundary condition.A novel statistical multiscale analysis method based on the two-scale asymptotic expansion is proposed.In the statistical multiscale formulations,a unified linear homogenization procedure is established and the second-order correctors are introduced for modeling the nonlinear radiative heat transfer in random perforations,which are our main contributions.Besides,a numerical algorithm based on the statistical multiscale method is given in details.Numerical results prove the accuracy and efficiency of our method for multiscale simulation of transient nonlinear conduction and radiation heat transfer problem in random porous materials.

Development of Transient Electric Field Radiation Simulation Device during Gas Insulation Switch Operation

In gas insulation switch(GIS)substation,secondary devices such as linemonitoring devices are placed in the switching field,and these electronic devices are vulnerable to transient electromagnetic interference caused by switching operation.In order to facilitate the measurement and research of electromagnetic disturbance data under different working conditions,a simulation test device is developed in this paper,which can be used to simulate electromagnetic disturbance of GIS substation sensor and secondary device port under switch operation.A four-channel parallel gas switch was designed,and the main characteristic parameters of electromagnetic disturbance generated by the simulation device were measured by using high-frequency pulse power supply as the excitation source.The comparison between the measured waveform and the measured disturbance characteristic parameters of GIS substation shows that it is in good agreement with the measured waveform characteristics,conforms to the basic characteristics of damped oscillation wave,and can be used in the secondary equipment port disturbance voltage coupling characteristics,protection measures evaluation and assessment method research.

Transient Natural Convection in an Annulus with Thermal Radiation

The interaction of transient fully developed natural convection flow with thermal radiation inside a vertical annulus is analyzed both analytically and numerically. The Rosseland approximation is used to describe the radiative heat flux in the energy equation. The mathematical model capturing the present physical situation is highly non-linear due to the presence of radiation effect. The solution of transient model is obtained by implicit finite difference method. To check accuracy of the numerical solution, steady state solution for energy and momentum equations are derived analytically using perturbation series method. Skin-friction and Nusselt number at the outer surface of inner cylinder as well as inner surface of the outer cylinder are obtained. Selected sets of graphical results illustrating the effects of various controlling parameters involved in the problem on flow formation are discussed.

Factors correlating with acoustic radiation force impulse elastography in chronic hepatitis C

AIM: To investigate the factors other than fibrosis stage correlating with acoustic radiation force impulse (ARFI) elastograpy in chronic hepatitis C.

Simplified Calculation Method for Transient Field of Transverse Electromagnetic Horn Antenna Used by High-altitude Electromagnetic Pulse Simulator

For conveniently calculating the radiated electric field of transverse electromagnetic(TEM) horn antenna,an approximate simplified analytical calculation method is suggested.This method divides the horn to a system of V-antennas and superimposes the fields of all V-antennas to obtain the field of the TEM horn.The method is compared with the traditional analytical method and numerical method.The obtained results suggest that the proposed method is valid,simple and that it can fastly calculate the radiated electric field of the TEM horn antenna in an arbitrary space with an arbitrary excitation voltage.Based on this method,radiation of the TEM horn antenna of a high-altitude electromagnetic pulse(HEMP) simulator is simulated.Rise time,pulse width,peak value of electric field,and field distribution are analyzed.Results show that the TEM horn antenna can be used in HEMP simulators: the near field waveform is closer to the standard waveform than to the far field waveform; the standards for the rise time and the peak value of electric field are easily satisfied; the pulse width of the radiated field can be increased by broadening the pulse width of an excitation source and by making the antenna of a proper

Mechanism of single-event transient pulse quenching between dummy gate isolated logic nodes

As integrated circuits scale down in size, a single high-energy ion strike often affects multiple adjacent logic nodes.The so-called single-event transient（SET） pulse quenching induced by single-event charge sharing collection has been widely studied. In this paper, SET pulse quenching enhancement is found in dummy gate isolated adjacent logic nodes compared with that isolated by the common shallow trench isolation（STI）. The physical mechanism is studied in depth and this isolation technique is explored for SET mitigation in combinational standard cells. Three-dimensional（3D） technology computer-aided design simulation（TCAD） results show that this technique can achieve efficient SET mitigation.

The dual role of multiple-transistor charge sharing collection in single-event transients

As technologies scale down in size, multiple-transistors being affected by a single ion has become a universal phenomenon, and some new effects are present in single event transients （SETs） due to the charge sharing collection of the adjacent multiple-transistors. In this paper, not only the off-state p-channel metal–oxide semiconductor field-effect transistor （PMOS FET）, but also the on-state PMOS is struck by a heavy-ion in the two-transistor inverter chain, due to the charge sharing collection and the electrical interaction. The SET induced by striking the off-state PMOS is efficiently mitigated by the pulse quenching effect, but the SET induced by striking the on-state PMOS becomes dominant. It is indicated in this study that in the advanced technologies, the SET will no longer just be induced by an ion striking the off-state transistor, and the SET sensitive region will no longer just surround the off-state transistor either, as it is in the older technologies. We also discuss this issue in a three-transistor inverter in depth, and the study illustrates that the three-transistor inverter is still a better replacement for spaceborne integrated circuit design in advanced technologies.

Radiation Phenomenon Due to Streamers of Sprites

An upper atmospheric phenomenon i.e., sprites can be thought to be mainly caused by the propagation of positive corona streamers. This research presents the formulation for the calculation of radiation power received from the propagating corona streamers responsible for the origination of the sprites. The produced magnetic field variation using the calculated electromagnetic radiation power is found to be similar with the previous observation-based research work.

船舶有航速时三维时域格林函数计算方法研究

船舶工业CAE软件势流求解器的开发对势流计算方法的可靠性提出要求,本文针对船舶有航速时深水三维时域格林函数计算方法开展研究。首先引入三维时域自由面格林函数,其瞬时项的求解采用Hess&Smith方法,自由面记忆项的求解采用美国密歇根大学Beck团队的方法。其次,分区域推导出三维时域自由面格林函数记忆项及其导数的编程所用的数学展开表达式。然后,采用间接法模型求解分布源强和速度势,并采用压力直接积分法求出时域辐射力。最后,针对Wigley I船型开展了辐射力计算,并与公开的试验及计算结果进行对比,验证本文方法的可靠性。

石英光纤近红外波段γ辐照效应实验研究

为提高某光学干涉测量系统的耐辐射能力,开展耐辐射光纤选型实验。以剂量率为0.5 Gy·s^(-1)的稳态γ射线和剂量率为5.0×10^(9) Gy·s^(-1)、脉冲宽度约20 ns的瞬态强γ射线为辐照源,获得掺锗、掺氟耐辐射单模光纤和常规G.652光纤在工作波长1550 nm、注入光功率40 mW工况下的辐射感生损耗,结果表明,实验获得的在线辐射感生损耗数据真实可靠;在稳态γ射线作用下,掺锗和掺氟耐辐射光纤的性能差异不大,辐射感生损耗小于17 dB·km^(-1),随着辐射时间的增加,辐射损耗呈现饱和,耐辐射光纤的性能均优于常规单模G.652通信光纤;在瞬态强γ射线作用下,两个不同型号掺氟光纤的性能最优,辐射感生损耗峰值分别为471.5 dB·km^(-1)和608.6 dB·km^(-1),恢复通信时长约μs量级。掺锗光纤的瞬态辐照性能最差,辐射感生损耗峰值为2691.3 dB·km^(-1),在μs时间尺度维持感生损耗饱和状态。

时间分辨动态LIBS测量方法

针对激光诱导击穿光谱(LIBS)研究对时间分辨动态光谱测量方法的需求,建立了基于多通道光纤束的动态LIBS测量方法。该方法首先利用不同长度的光纤组成多通道光纤束,对瞬态LIBS信号进行差异延迟,使按照特定时间序列发射的光谱信号同步到达探测器,而后采用面阵ICCD相机对同步到达的多通道光谱信号进行高时间分辨探测。该方法单次测量即可获得LIBS辐射不同时刻的时间分辨光谱。为了验证基于多通道光纤束的动态LIBS测量方法,研制了具有19个通道的光纤束,光纤束中包含的各个单根光纤长度呈等差数列排布,长度差设置为10 m,对应测量的时间间隔约为50 ns,单次测量记录的总时间长度近900 ns。分别基于短脉冲激光光源和标准光源,开展了系统时间响应和光谱响应特性研究,获得了系统的时间响应数据和光谱响应曲线。用YAG激光器的二倍频激光(532 nm)诱导Si产生等离子体辐射光谱,在线测量了辐射光谱的时间演化历程,获得了Si等离子体辐射过程中SiⅠ390.52 nm,SiⅡ385.51 nm,SiⅡ413.12 nm谱线从0~898 ns时间范围内19个时刻的光谱信息,获得了特征光谱的演化规律,验证了该测量方法的可行性。结果表明,利用该测量方法,单次测量可以获得瞬态LIBS辐射过程中19个时刻的光谱参数,具有很高的测量效率。对于实验成本较高、运行频率低的激光诱导等离子体实验研究,采用该方法可以大大降低了测量成本,有效提升等离子体时间分辨动态光谱测量能力。

SOI晶体管和电路的瞬时电离辐射效应研究

基于全介质隔离的绝缘硅(Silicon-on-insulator,SOI)器件与体硅器件的瞬时电离辐射效应存在差异,采用1 064 nm/12 ns激光装置开展了三种SOI晶体管的激光辐照试验,测试了不同激光能量下的晶体管光电流;采用脉冲γ射线辐射源开展了SOI集成电路的瞬时γ剂量率辐射试验,测试了不同剂量率条件下的电路功能、电参数和触发器链状态。研究表明:在相同激光能量条件和相同特征尺寸条件下,SOI晶体管的光电流峰值约为体硅晶体管的3.5%;SOI集成电路在1.0×10^(9)~4.2×10^(11) rad(Si)·s^(-1)的试验剂量率范围内无闭锁效应,但存在显著的翻转效应,表现为功能短暂中断、电流和电压波动以及大量触发器状态错误。翻转效应的主要原因包括晶体管本身的翻转和印刷电路板(Printed Circuit Board,PCB)板级电路的电压波动。

基于优化模型的纳米器件逻辑单元单粒子瞬态仿真研究

空间辐射诱发的单粒子瞬态(SET)是航天电子系统可靠性的主要威胁。本文分析了现有电荷注入仿真模型的不足,提出了一种改进的结合灵敏体和双极扩散机制的电荷收集模型,综合考虑了寄生双极放大效应和电荷共享效应,可针对不同角度、不同线性能量传输值(LET)的重离子入射版图不同位置,计算获取SET平均脉宽及敏感截面分布。该方法已集成于项目组自研TREES软件,并针对商用65 nm工艺库中的多种逻辑单元开展了相关仿真计算。结果表明,该方法可在物理版图设计阶段评估单粒子瞬态截面及脉宽分布,为版图屏蔽SET设计加固提供基础参考数据。

圆柱壳体瞬态辐射噪声评估试验验证与分析

基于自身振动数据实时测量进行水下结构体辐射噪声快速预报,对于掌握水下目标运行状况、保持隐蔽性具有重要意义。该文针对工况传递路径分析方法评估瞬态辐射噪声问题,在圆柱壳体(舱段模型)上开展验证试验,通过稳态工况下的振动信号和实测辐射噪声,利用基于广义交叉验证的正则化方法求解振-声传递函数,以此来评估瞬态激励下的辐射噪声,并与实测的瞬态辐射噪声进行对比,同时提出针对目标被探测性影响程度的加权平均误差来衡量评估误差。试验结果显示,在瞬态辐射噪声的特征频段(辐射噪声水平明显高于背景噪声),评估结果的加权平均误差在2 dB以内。该文验证了工况传递路径分析方法评估瞬态辐射噪声的有效性,为进一步在水下复杂结构上开展研究奠定了基础。