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).

Effects of postselected von Neumann measurement on the properties of single-mode radiation fields

Postselected von Neumann measurement characterized by postselection and weak value has been found to possess potential applications in quantum metrology and solved plenty of fundamental problems in quantum theory. As an application of this new measurement technique in quantum optics and quantum information processing, its effects on the features of single-mode radiation fields such as coherent state, squeezed vacuum state and Schrödinger cat sate are investigated by considering full-order effects of unitary evolution. The results show that the conditional probabilities of finding photons, second-order correlation functions, Qm-factors and squeezing effects of those states after the postselected measurement is significantly changed are comparable with the corresponding initial pointer states.

Molecular Structure and Electronic Spectra of CoS under the Radiation Fields

We optimized the ground-state stable configuration of CoS molecule in different external radiation fields(0-0.04 atomic units(a.u.))at the basis set level of 6-311G++(d,p)using the B3LYP density functional theory.On this basis,the molecular structure,total energy,energy gap,and the intensities of infrared ray(IR)spectra,Raman spectra,and ultraviolet-visible(UV-Vis)absorption spectra of CoS molecule were computed using the same method.The results showed that the molecular structure changed greatly under the effect of the external radiation fields and had significant dependency on the radiation fields.The total energy of CoS molecule grew slightly at first and then significantly decreased in a monotonous manner.The bond length,dipole moment,and energy gap of the molecule all reduced at first and then increased,with the turning point all at F=0.025 a.u.of the radiation field.The absorption peak of IR spectra and Raman optical activity both had maximums at F=0.03 a.u.with significant red shift.In the external radiation field of F=0.030 a.u.,the absorption wavelength of the UV-Vis absorption spectra showed large blue shift,and a strong absorption peak was observed.

RESEARCH ON INDOOR ELECTROMAGNETIC RADIATION FIELD OF MULTIPLE ANTENNA SYSTEM

The complexity of the indoor environment brings great challenges to predict the electromagnetic radiation field of multiple antenna systems. Based on the Finite Difference Time Domain (FDTD) algorithm, using the mobile phone shielding device as the multiple antenna systems example, the mobile phone shielding device's indoor electromagnetic radiation field is researched by measurment method and simulation method. The effectivity of prediction method is verified by comparing the prediciton results with the measurment results. About 80% of the error can be controlled less than dB. The quantitative research has certain guiding significance to the prediction of the multiple antenna systems radio wave propagation.

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.

As Regards the Speed in a Medium of the Electromagnetic Radiation Field

The velocity of the electromagnetic radiation in a perfect dielectric, containing no charges and no conduction currents, is explored and determined on making use of the Lorentz transformations. Besides the idealised blackbody radiation, whose vacuum propagation velocity is the universal constant c, being this value independent of the observer, there is another behaviour of electromagnetic radiation, we call inertial radiation, which is characterized by an electromagnetic inertial density , and therefore, it happens to be described by a time-like Poynting four-vector field which propagates with velocity . is found to be a relativistic invariant expressible in terms of the relativistic invariants of the electromagnetic field. It is shown that there is a rest frame, where the Poynting vector is equal to zero. Both phase and group velocities of the electromagnetic radiation are evaluated. The wave and eikonal equations for the dynamics of the radiation field are formulated.

Modeling and Simulation of High Frequency Electromagnetics Wave Propagation on Vivaldi Antenna Using Finite Element Method

The simulation of the electromagnetic wave propagation plays an important role in predicting the performance of wireless transmission and communication systems. This research paper performs a numerical simulation using the finite element method (FEM) to study electromagnetic propagation through both conductive and dielectric media. The simulations are made using the COMSOL Multiphysics software which notably implements the finite element method. The microwave is produced by a Vivaldi antenna at the respective frequencies of 2.6 and 5 GHz and the propagation equation is formulated from Maxwell’s equations. The results obtained show that in the air, strong electric fields are observed in the slot and the micro-strip line for the two frequencies, they are even greater when the wave propagates in the glass and very weak for the copper. The 3D evolutions of the wave in air and glass present comparable values at equal frequencies, the curves being more regular in air (dielectric). The radiation patterns produced for air and glass are directional, with a large main lobe, which is narrower at 5 GHz. For copper, the wave propagation is quite uniform in space, and the radiation patterns show two main lobes with a much larger size at 2.6 GHz than at 5 GHz. The propagation medium would therefore influence the range of values of the gain of the antenna.

Measurement and analysis on distribution of radiation field dose inside thetreatment room of TaiChi Pro multimodal integrated digitalradiotherapy system

Objective:To examine the leakage radiation dose from the accelerator module's primary beam self-shielding,aswell as stray radiation levels and distribution in the treatment room across various planes for the innovative X/γmultimodal radiotherapy system,TaiChi Pro,which is the world's first digitally integrated system that combines alinear accelerator,multi-source rotational focused gamma knife,and multi-modal image guidance,in order toformulate treatment room safety strategies and estimate additional radiation doses to patients.Methods:The TaiChi Pro multi-mode integrated radiotherapy system was utilized with a 6 MV X-ray accelerator inthe flatten-filter free(FFF)treatment mode.The system has a primary radiation beam self-shielding,and anisocenter dose rate of 800 cGy/min.For detection points in various planes,an x,y,z coordinate system wasestablished with the isocenter as the origin.To simulate the situation of patient,water-equivalent phantom wasemployed.The ambient dose equivalent and ambient dose equivalent rate at detection points in the radiation fieldwere measured using thermoluminescence dosimeters.Results:The self-shielding area achieved a maximum dose of 114.0 mGy at 1 m distance from the target point after3 min of cumulative irradiation.The leakage radiation ratios at all points remained below 0.5%,fulfilling the selfshielding design requirements.Regarding the couch,the highest radiation was observed in the opposite directionof the beam at the target point.The stray radiation on the treatment bed plane resulted in an ambient doseequivalent that did not exceed 0.5%of the ambient dose equivalent at the central point.Conclusion:The levels and distribution patterns of stray and leakage radiation inside the TaiChi Pro treatmentroom meet the requirements of the relevant national standard.The measured values of indoor radiation levels anddistribution are very useful for room shielding design and personnel protection.

Acoustic radiation field of the truncated parametric source generated by a piston radiator:model and experiment

A theoretical model is presented to describe the parametric acoustic field generated by a piston radiator. In the model, the high-frequency primary wave interaction region that is truncated by a low-pass acoustic filter can be viewed as a cylindrical source within the Rayleigh distance of the piston. When the radius of the piston is much smaller than the length of the parametric region, this model is reduced to the Berketey’s End-Fire Line Army model. Comparison between numerical calculations and experimental measurement show that the generated parametric sound field (especially near the axis) agrees well with the experiment results.

A transient process observation method based on the non-homogeneous Poisson process model

The current-mode-counting method is a new approach to observing transient processes,especially in transient nuclear fusion,based on the non-homogeneous Poisson process(NHPP)model.In this paper,a new measurement process model of the pulsed radiation field produced by transient nuclear fusion is built based on the NHPP.A simulated measurement is performed using the model,and the current signal from the detector is obtained by simulation based on Poisson process thinning.The neutron time spectrum is reconstructed and is in good agreement with the theoretical value,with its maximum error of a characteristic parameter less than 2.3%.Verification experiments were carried out on a CPNG-6 device at the China Institute of Atomic Energy,with a detection system with a nanosecond response time.The experimental charge amplitude spectra are in good agreement with those obtained by the traditional counting mode,and the characteristic parameters of the time spectrum are in good agreement with the theoretical values.This shows that the current-mode-counting method is effective for the observation of transient nuclear fusion processes.

Asymptotics for null-timelike boundary problems for general linear wave equations

We study the linear wave equation□gu=0 in Bondi-Sachs coordinates,for an asymptotically flat Lorentz metric g.We consider the null-timelike boundary problem,where an initial value is given on the null surfaceτ=0 and a boundary value on the timelike surface r=r0.We obtain spacetime Hp-estimates of ru for r>r0 and derive an asymptotic expansion of ru in terms of 1/r as r→∞.