- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Handbook of Materials Modeling (Applications: Current and Emerging Materials) || Incorporating Electronic Effects in Molecular Dynamics Simulations of Neutron and Ion-Induced Collision Cascades
摘要： Molecular dynamics offers an ideal method for investigating the evolution of collision cascades and the formation of the resulting primary radiation damage. However, several modifications to classical molecular dynamics are needed in order to facilitate simulating the highly non-equilibrium cascade process. One such modification, which is still a point of active research, concerns methods by which electronic effects, which are expected to be important in collision cascades, can be included in molecular dynamics simulations, where a priori atoms are treated as classical particles and electrons are only present implicitly through the atomic interactions represented by the interatomic potential. This chapter describes current methods by which electronic effects can be accounted for in cascade simulations, with special focus on the developments in the field that have taken place over the last 10 years.
关键词： interatomic potential,collision cascades,electronic effects,radiation damage,Molecular dynamics
更新于2025-09-23 15:21:21
-
[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Gamma-Ray Irradiation Effects of CdS/CdTe Photodiode for Radiation Tolerant FEA Image Sensor
摘要： The influences of gamma irradiation on CdS/CdTe photodiodes were investigated in order to evaluate their potential for applications to the radiation tolerant field emitter array (FEA) image sensor. It was found that the CdS/CdTe photodiodes have sufficient tolerance to high gamma-ray exposure more than 2 MGy. Furthermore, I-V characteristics of CdS/CdTe photodiodes under gamma-ray irradiation were investigated. In the CdTe thickness of 6.5 ?m, the change rate of current density increased with increase in the reverse bias voltage. On the other hand, in the case of 2.2 ?m, the change rate of current density was almost constant irrespective of the reverse bias voltage. These results suggest that the increase in depletion layer width affects the change rate of current density.
关键词： image sensor,cadmium telluride,field emitter array,radiation tolerance
更新于2025-09-23 15:21:21
-
[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Generation of light beams by electron beam excited surface plasmons
摘要： Manipulation of Smith-Purcell radiation (SPR) by electron-bunch excitation of localized surface plasmon (LSP) of gold (Au) disc arrays on Au substrate is investigated by FDTD simulation. When the wavelength of LSP mode is within the SPR emission band, SPR is locked and enhanced at the LSP wavelength. The emission angle of LSP-locked SPR still follows the wavelength-angle relation of traditional SPR. Furthermore, both the emission wavelength and angle increase as the radius and height of Au disc increase.
关键词： FDTD simulation,Smith-Purcell radiation (SPR),localized surface plasmon (LSP)
更新于2025-09-23 15:21:21
-
Pre- and post-contrast versus post-contrast cone-beam breast CT: can we reduce radiation exposure while maintaining diagnostic accuracy?
摘要： Objectives To evaluate whether post-contrast cone-beam breast CT (CBBCT) alone is comparable to the current standard of combined pre- and post-contrast CBBCT regarding diagnostic accuracy and superior regarding radiation exposure. Material and methods This study included 49 women (61 breasts) with median age 57.9 years and BI-RADS 4/5 lesions diagnosed on mammography/ultrasound in density type c/d breasts. Two radiologists rated post-contrast CBBCT and pre- and post-contrast CBBCT with subtraction images on the BI-RADS scale separately for calculation of inter- and intra-observer agreement and in consensus for diagnostic accuracy assessment. Sensitivity, specificity, and area under the curve (AUC) were compared via McNemar test and DeLong method, respectively. Subtraction imaging misregistration were measured from 1 (no artifacts) to 4 (artifacts with width > 4 mm). Results A total of 100 lesion (51 malignant; 6 high risk; 43 benign) were included. AUC, sensitivity, and specificity showed no significant differences comparing post-contrast CBBCT alone versus pre- and post-contrast CBBCT (AUC 0.84 vs. 0.83, p = 0.643; sensitivity 0.89 vs. 0.85, p = 0.158; specificity 0.73 vs. 0.76, p = 0.655). Inter- and intra-observer agreement was excellent (intra-class correlation coefficient ICC = 0.76, ICC = 0.83, respectively). Radiation dose was significantly lower for post-contrast CBBCT alone versus pre- and post-contrast CBBCT (median average glandular radiation dose 5.9 mGy vs. 11.7 mGy, p < 0.001). High-degree misregistrations were evident in the majority of subtraction images (level 1/2/3/4 16.9%/27.1%/16.9%/39%), in particular for bilateral exams (3.2%/29.2%/8.3%/58.3%). Conclusion Diagnostic accuracy of post-contrast CBBCT alone is comparable to pre- and post-contrast CBBCT in type c/d breasts, while yielding a significant twofold radiation dose reduction.
关键词： Contrast media,Breast,Radiation dosage,Cone-beam computed tomography
更新于2025-09-23 15:21:21
-
[IEEE 2018 VII. Lighting Conference of the Visegrad Countries (Lumen V4) - Trebic, Czech Republic (2018.9.18-2018.9.20)] 2018 VII. Lighting Conference of the Visegrad Countries (Lumen V4) - Radiation of the Luminous Flux Into the Upper Half-Space in Wils - Building Design
摘要： The article focuses on the further verification of the software goniophotometer in the BUILDING DESIGN computational program in terms of the possibility of calculating the radiation of the liminous flux flowing into the upper half- space from public lighting systems [1]. Software goniophotometer was tested by the previous verification for the accuracy of calculations of the direct and indirect component of luminaire luminous flux. The superstructure was conceived as the possibility of inserting a network of calculating points in the shape of a sphere. We can imagine the points showing normal illuminance towards the centre of the sphere as a lux meter sensor. The system thus designed duplicates the function of a real goniophotometer, a photometric laboratory instrument that measures luminous intensity or luminous intensity curves. The principle of a goniophotometer is that it allows to measure the luminous intensity in different planes and at different angles, which can be easily interpreted by a sphere with a network of calculation points. The density of the calculation points can be entered in an angular step according to the standard luminaire measurement plan C, γ. The goal of implementing such a network of calculation points is to extend the possibilities of a computational program for modelling the luminous intensity curves of existing luminaires as well as newly composed luminaires. The main goal is calculating the radiation of the liminous flux flowing into the upper half-space from the outdoor lighting systems. It will be the basis for further astronomical calculations that focus on distracting light and increased sky luminance. Based on the testing, it will be possible to create model of lighting system in some city or district of the city by inserting LDT data of real luminaires, thus creating a real lighting system with real building models. From the resulting model, it will be possible to quantify the proportion of the direct and indirect luminous flux flowing into the upper half-space.
关键词： sodium lighting system,modeling,radiation curves,LED lighting system,software goniophotometer,upper half-space
更新于2025-09-23 15:21:21
-
Beam frame representation for ultra-wide-band radiation from volume source distributions: Frequency domain and time domain formulations
摘要： We present two novel beam summation (BS) schemes for radiation from time-harmonic or time-dependent volume source distributions, where the field is expanded using a discrete phase-space set of beam-wave propagators. The generic term “beams” is used here for both the frequency-domain and the time-domain formulations where the propagators are iso-diffracting Gaussian beam (ID-GB) or iso-diffracting pulsed beams (ID-PB), respectively. The formulations are structured upon the recently formulated “beam-frame” theorem that establishes these phase-space beam-sets as frame-sets everywhere in the propagation domain, and not only over the aperture plane as in previous formulations. The expansion coefficients are obtained by projecting the source distributions over the dual beam-frame sets that have essentially the same structure as the basic sets. As such, these formulations constitute local generalization to the conventional plane-waves or Green’s function formulations, and also reduce the overall degrees of freedom needed to describe the radiated field. As demonstrated by the numerical examples they resolve the local features of the source distributions in space-time, and hence provide a basis for a new local inverse scattering theory to be presented subsequently.
关键词： beam summation methods,pulsed beams,Gaussian beams,phase space representations,ultra wide band,time domain,Radiation theory
更新于2025-09-23 15:21:21
-
Broadside Scanning Asymmetric SIW LWA with Consistent Gain and Reduced Side Lobe
摘要： In this paper, a backwards-to-forward continuous beam scanning leaky wave antenna (LWA) is presented in substrate integrated waveguide (SIW) technology. The antenna radiates from a continuous longitudinal slot etched on its broad wall. The slot is excited by using periodic H-plane steps. An impedance matched unit cell structure is used to suppress the open stop-band in the broadside direction. Bloch wave analysis is used to obtain the propagation characteristics of the antenna. However, due to radiation being obtained only from the shunt type radiating element viz., the longitudinal slot, a gain dip is observed in the broadside direction. Transversal asymmetry is then introduced in the structure to eliminate the gain dip and obtain consistent gain. A prototype of the antenna is fabricated and measured. Continuous beam scanning is achieved from –29o to +30o about the broadside direction with a gain variation of less than 2 dB over 8.0–12.4 GHz. A measured peak gain of 16.1 dBi is obtained. Key structural design parameters of the antenna are identified for controlling the leakage rate. Next, Taylor tapered aperture illumination is used to obtain low sidelobe level (SLL). The Taylor tapered antenna is also fabricated with the measured SLL below -21 dB.
关键词： substrate integrated waveguide (SIW),broadside radiation,Taylor distribution,Leaky-wave antenna (LWA)
更新于2025-09-23 15:21:21
-
[IEEE 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Odessa, Ukraine (2018.9.4-2018.9.7)] 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Radiation Resistance of Resonant Impedance Monopole Placed on Metal Square Screen
摘要： The asymptotical solution of the 3-D vector problem of diffraction of the field of the monopole with the uniform distributed surface impedance, placed on the ideally conducting rectangular screen with the sides sizes L and W is obtained. Within the frame of the uniform geometrical theory of diffraction the radiation field in a far zone is represented as the sum of the geometric optics field from an impedance monopole placed on infinite screen, and the diffracted fields from the rectangular screen edges. The radiation resistances are calculated by the Poynting vector method as the functions of the monopole’s surface impedance and the sizes of monopole and screen. The input impedances of the same monopoles on the square screens have calculated using commercial software too. It is shown that at all surface impedances and monopole’s lengths the radiation and input resistances reach maximum at L=W=0.9 of wavelength.
关键词： impedance monopole,surface impedance,square screen,radiation resistance,input impedance,amplitude
更新于2025-09-23 15:21:21
-
[IEEE 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Odessa, Ukraine (2018.9.4-2018.9.7)] 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Mathematical Model of Transverse Circumferential Slots in Coaxial Line Shield With Nonhomogeneous Dielectric Interior
摘要： Excitation and scattering problem for transverse circumferential slots in a shield of coaxial line with dielectric insert just under the slot has been solved. Internal conductivity is determined including multiple reflections that are caused by dielectric insert of a finite length filling the feeder cross-section up. Formulas for radiation and reflection coefficients are presented.
关键词： dielectric insert,circumferential slot,reflection coefficient,radiation coefficient,line,conductivity,magnetomotive,force,coaxial
更新于2025-09-23 15:21:21
-
[IEEE 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Odessa, Ukraine (2018.9.4-2018.9.7)] 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Combined Wide-Angle Scanning by a Two-Dimensional Dipole Array
摘要： An analytical solution of an impedance synthesis problem for a two-dimensional dipole antenna array is obtained. The array consists of thin impedance electric dipoles whose centers are located at nodes of a planar rectangular grid with double periodicity. Radiation patterns of each dipole in the array does not differ from that of an isolated dipole. A new method for wide-angle scanning of the array radiation pattern, combining the simultaneous variation of phases of the excitation currents in the dipoles and of their surface impedances is proposed.
关键词： thin impedance dipole,flat two-dimensional antenna array,wide-angle scanning,radiation pattern,wave zone,impedance synthesis method
更新于2025-09-23 15:21:21