Research on perturbation of neutron fluence rate in a closed thermal neutron field due to medium materials

The neutron radiation field has vital applications in areas such as biomedicine,geology,radiation safety,and many others for neutron detection and neutron metrology.Correcting neutron fluence rate perturbation accurately is an important yet challenging problem.This study proposes a correction method that analyzes three physical processes.This method,which transforms the detection process from point detection to area detection,is based on a novel physical model and has been validated through theoretical analyses,experiments,and simulations.According to the average differences between the calculated and experimental results,the new method(1.67%)demonstrated better accuracy than the traditional simulation(2.17%).In a closed thermal neutron radiation field,the detector or strong neutron absorption material significantly perturbs the neutron fluence rate,whereas its impact on the energy spectrum shape and neutron directionality is relatively minor.Furthermore,based on the calculation results of the perturbation rate formula for medium materials with different compositions and sizes,the larger the volume and capture cross section of the medium,the higher the perturbation rate generated in the closed radiation field.

MarkNeRF:Watermarking for Neural Radiance Field

This paper presents a novel watermarking scheme designed to address the copyright protection challenges encountered with Neural radiation field(NeRF)models.We employ an embedding network to integrate the watermark into the images within the training set.Then,theNeRFmodel is utilized for 3Dmodeling.For copyright verification,a secret image is generated by inputting a confidential viewpoint into NeRF.On this basis,design an extraction network to extract embedded watermark images fromconfidential viewpoints.In the event of suspicion regarding the unauthorized usage of NeRF in a black-box scenario,the verifier can extract the watermark from the confidential viewpoint to authenticate the model’s copyright.The experimental results demonstrate not only the production of visually appealing watermarks but also robust resistance against various types of noise attacks,thereby substantiating the effectiveness of our approach in safeguarding NeRF.

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.

XPS STUDIES OF IRRADIATED HARD AND SOFT Si—SiO_2

The interracial structure of hard and soft oxides grown by dry oxidation on<100> n-type silicon substrates is examined using high resolution mild X-ray photoelectron spectroscopy (XPS) before and after irradiation. Substantial differences in silicon of silica state (B.E. 103.4 eV), silicon of transitional state (B.E. 101.5 eV), surplus oxygen (B.E. 529.6 eV) and negative two-valence oxygen (B.E. 531.4 eV) are observed between the two kinds of samples. The XPS spectra strongly depend on the conditions of irradiation for soft samples, but do not as remarkablely as soft samples for hard samples. The effects of irradiation doses on XPS are greater than that of irradiation bias fields. Some viewpoints of irradiation induced hole electron pair are proposed to explain the results.

Thermal evolution of neutron stars with decaying magnetic fields

Rotochemical heating originates in the deviation from beta equilibrium due to spin-down compression, which is closely related to the dipole magnetic field. We numerically calculate the deviation from chemical equilibrium and thermal evolution of neutron stars with decaying magnetic fields. We find that the power-law long term decay of the magnetic field slightly affects the deviation from chemical equilibrium and surface temperature. However, the magnetic decay leads to older neutron stars that could have a different surface temperature with the same magnetic field strength. That is, older neutron stars with a low magnetic field （10^8 G） could have a lower temper- ature even with rotochemical heating in operation, which probably explains the lack of other observations on older millisecond pulsars with higher surface temperature, except millisecond pulsar J0437-4715.

Effect of aperture field distribution on the maximum radiated power at atmospheric pressure

The air breakdown in the high-power antenna near-field region limits the enhancement of the radiated power. A model coupling the field equivalent principle and the electron number density equation is presented to study the breakdown process in the near-field region of the circular aperture antenna at atmospheric pressure. Simulation results show that, although the electric field in the near-field region is nonuniform, the electron diffusion has small influence on the breakdown process when the initial electron number density is uniform in space. The field magnitude distribution on the aperture plays an important role in the maximum radiated power above which the air breakdown occurs. The maximum radiated power also depends on the phase difference of the fields at the center and edge of the aperture, especially for the uniform field magnitude distribution.

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.

Concurrent chemoradiotherapyof different radiation doses and different irradiation fields for locally advanced thoracic esophageal squamous cell carcinoma:A randomized,multicenter,phase Ⅲ clinical trial

Background:Concurrent chemoradiotherapy(CCRT)is the standard treatment for locally advanced esophageal squamous cell carcinoma(ESCC).However,the optimal radiotherapy regimen,particularly in terms of total dose and planned range of irradiation field,remains unclear.This phase III clinical trial aimed to compare the survival benefits between different radiation doses and different target fields.Methods:This trial compared two aspects of radiation treatment,total dose and field,using a two-by-two factorial design.The high-dose(HD)group received 59.4 Gy radiation,and the standard-dose(SD)group received 50.4 Gy.The involved field irradiation(IFI)group and elective nodal irradiation(ENI)group adopted different irradiation ranges.The participants were assigned to one of the four groups(HD+ENI,HD+IFI,SD+ENI and SD+IFI).The primary endpoint was overall survival(OS),and the secondary endpoints included progressionfree survival(PFS).The synergy indexwas used to measure the interaction effect between dose and field.Results:The interaction analysis did not reveal significant synergistic effects between the dose and irradiation field.In comparison to the target field,patients in IFI or ENI showed similar OS(hazard ratio[HR]=0.99,95%CI:0.80-1.23,p=0.930)and PFS(HR=1.02,95%CI:0.82–1.25).TheHDtreatment did not show significantly prolonged OS compared with SD(HR=0.90,95%CI:0.72–1.11,p=0.318),but it suggested improved PFS(25.2 months to 18.0 months).Among the four groups,the HD+IFI group presented the best survival,while the SD+IFI group had the worst prognosis.No significant difference in the occurrence of severe adverse events was found in dose or field comparisons.Conclusions:IFI demonstrated similar treatment efficacy to ENI in CCRT of ESCC.The HD demonstrated improved PFS,but did not significantly improve OS.The dose escalation based on IFI(HD+IFI)showed better therapeutic efficacy than the current recommendation(SD+ENI)and is worth further validation.

Measurement and theoretical analysis of solar temperature field in steel-concrete composite girder

The solar temperature field of a large three-span continuous bridge with steel-concrete composite box girder and variable cross-section is measured to verify a calculation method for the temperature field of steel-concrete composite beams. The test results show that the temperature of an external steel web- plate is higher than that of an internal web-plate due to the difference in solar radiation. Air temperature inside the box matches the average temperature of the whole steel box. Based on actual measurements, a transient thermal analysis with multiple boundary conditions is also carried out by a software program ANSYS. Convective boundary situation and states of solar radiation on steel web plates in different situations are determined in the analysis. The feature of the temperature field is preliminarily achieved through a comparative study between the actual measurement and the finite element analysis. The computed results are in good consistence with the actual measurement results, with the maximum difference within 2 ℃. This indicates that the theoretical calculation method is reliable and it provides a foundation for further research on temperature field distribution in the steel-concrete composite box girder.

Heat transfer model for microwave hot in-place recycling of asphalt pavements

In order to solve for temperature fields in microwave heating for recycling asphalt mixtures, a two-dimensional heat transfer model for the asphalt mixtures within the heating range is built based on the theory of unsteady heat conduction. Four onedimensional heat transfer models are established for the asphalt mixtures outside the heating range, which are simplified into four half-infinite solids. The intensity of the radiation electric field is calculated through experiment by using heating water loads. It is suggested that the mathematical model of boundary conditions can be established in two ways, which are theoretical deduction and experimental reverse. The actual temperature field is achieved by fitting temperatures of different positions collected in the heating experiment. The simulant temperature field, which is solved with the Matlab PDE toolbox, is in good agreement with the actual temperature field. The results indicate that the proposed models have high precision and can be directly used to calculate the temperature distribution of asphalt pavements.

Model and optimization of ultrasonic phased array parameters

Beam focusing is one of the unique characteristics of ultrasonic phased array compared with conventional ultrasound.On the basis of two-dimensional radiated sound field of phased array,the three-dimensional radiated sound field was simulated in the paper,and then the effect of different frequencies,different number of array elements and different element spacings on focal spot,the depth of focus and the effect on horizontal and vertical resolution were analyzed.The optimal results of transducer parameters have certain reference value for the design of phased array probe.

Optimal Microwave Radiation Field Parameters for Mercury Ion Microwave Frequency Standards

We propose a method to determine the optimal power of the microwave resonance transition that simultaneously improves the signal-to-noise ratio and reduces line width based on saturation broadening theory and experiment. Saturation broadening spectra of the ground state hyperfine transition of trapped 199Hg＋ ions are measured and analyzed. The value of the optimal microwave power is obtained by using the proposed method and is verified. Rabi oscillations decay spectra of trapped 199Hg＋ ions are observed and the optimal microwave irradiation time for the maximum transition signal intensity is determined. This work will help to improve the short-term frequency stability of the mercury ion microwave frequency standard.

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).

Are Homologous Radio Bursts Driven by Solar Post-Flare Loops?

Three particularly complex radio bursts （2001 October 19, 2001 April 10 and 2003 October 26） obtained with the spectrometers （0.65-7.6GHz） at the National Astronomical Observatories, Chinese Academy of Sciences （NAOC, Beijing and Yunnan） and other instruments （NoRH, TRACE and SXT） are presented. They each have two groups of peaks occurring in different frequency ranges （broad-band microwave and narrow-band decimeter wavelengths）. We stress that the second group of burst peaks that occurred in the late phase of the flares and associated with post-flare loops may be homologous radio bursts. We think that they are driven by the post-flare loops. In contrast to the time profiles of the radio bursts and the images of coronal magnetic polarities, we are able to find that the three events are caused by the active regions including main single-bipole magnetic structures, which are associated with multipole magnetic structures during the flare evolutions. In particular, we point out that the later decimetric radio bursts are possibly the radio counterparts of the homologous flares （called ＂homologous radio bursts＂ by us）, which are also driven by the single-bipole mag- netic structures. By examining the evolutions of the magnetic polarities of sources （17 GHz）, we could presume that the drivers of the homologous radio bursts are new and/or recurring appearances/disappearances of the magnetic polarities of radio sources, and that the triggers are the magnetic reconnections of single-bipole configurations.

Time Evolution of the Turnover Frequency for Diagnosis of the Coronal Magnetic Field

Two impulsive microwave bursts observed by Owens-Valley Solar Arrays （OVSA） are studied. The fast time variation of the turnover frequency in these bursts is quite different from the constant value in the earlier conclusion. The observational turnover frequencies are consistent with the calculations using the non-thermal gyrosynchrotron radiation model. We find the turnover frequency may play an important role for calculating the coronal magnetic field on the basis of Dulk and Marsh＇s approximations.

Entanglement Properties of Two-Mode Squeezed Coherent States in Radiation Field

Entanglement properties of two-mode squeezed coherent states in the radiation field ＆re investigated according to the entanglement criterion [Phys. Rev. Lett. 84 （2000） 2722]. The dependence of entanglement on squeeze angle and squeeze parameter is discussed. It shows that the system evolves into entangled states and entanglement does not increase persistently with the increase of squeeze angle and squeeze parameter. There only exists a certain squeeze angle in which the entanglement exists continuously.

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.

Electron-Cyclotron Laser Using Free-Electron Two-Quantum Stark Radiation in a Strong Uniform Axial Magnetic Field and an Alternating Axial Electric Field in a Voltage-Supplied Pill-Box Cavity

We consider the radiation from the beam electrons traveling in a strong uniform axial magnetic field and an axial alternating electric field of wavelength Aw generated by a voltage-supplied pill-box cavity. The beam electrons emit genuine laser radiation that propagates only in the axial direction through free-electron two- quantum Stark radiation. We find that laser radiation takes place only at the expense of the axial kinetic energy when Aw 〈〈 c/（ωc/γ）, where ωc/γ is the relativistic electron--cyclotron frequency. We formulate the laser power based on quantum-wiggler electrodynamics, and envision a laser of length lore with estimated power 0.1 GW/（kA） in the 10-4 cm wavelength range.