Resonance Interference Effects Research Articles

U-fiber-based biosensor for temperature-compensated acetylcholine-specific measurement.

This paper presents a U-fiber-based biosensor to achieve temperature-compensated acetylcholine-specific measurement. The surface plasmon resonance (SPR) and multimode interference (MMI) effects are simultaneously realized in a U-shaped fiber structure for the first time, to the best of our knowledge. The experimental results show refractive index (RI) sensitivities of 3042 and 2958 nm/RIU and temperature sensitivities of -0.47 and -0.40 nm/°C for the MMI and SPR, which are greatly improved compared with the traditional structure. Simultaneously, a sensitivity matrix for detecting two parameters is introduced to solve the problem of temperature interference of biosensors based on RI changes. Label-free detection of acetylcholine (ACh) was achieved by immobilizing acetylcholinesterase (AChE) on optical fibers. The experimental results show that the sensor can realize the specific detection of acetylcholine and has good stability and selectivity, and the detection limit of the sensor is 30 nM. The sensor has the advantages of simple structure, high sensitivity, convenient operation, direct insertion into small spaces, temperature compensation, etc., which provide an important supplement to traditional fiber-optic SPR biosensors.

Analysis of the fine-mesh subgroup method and its feasible improvement

The fine-mesh subgroup method (FSM) is proposed to treat the significant resonance self-shielding effect both effectively and accurately. Similar to the ultra-fine group method, the fine-mesh subgroup method adopts a fine group structure on the resonance energy range to avoid the extra resonance interference effect correction. To improve the efficiency, on the one hand, the one-group micro-level optimization is adopted, so the subgroup fixed-source equations will be only calculated on a certain number of pre-determined subgroup levels, and an interpolation process is employed to obtain the actual subgroup flux. On the other hand, the slowing-down calculation is carried out for group condensation for multigroup transport calculation. The main theory and feasible improvements of the fine-mesh subgroup method are analyzed in this paper. Several pin cell and lattice problems are applied to test the performance of the fine-mesh subgroup method, and the particle swarm optimization method is adopted to find the better group structure. The numerical results indicate a good performance both for accuracy and efficiency.

Resonance Interference Research of MEMS Inertial Sensors and Algorithm Elimination

The mechanical structure of MEMS inertial sensors is a spring-mass-damper system, which is susceptible to interference near the resonant frequency. This work compared the resonance interference effects of mechanical vibrations and high frequency sound waves on inertial sensors. Three MEMS gyroscopes ADXRS620 were interfered by vibrations and sound waves near the resonant frequency. The error outputs increased linearly with the increase of interference intensity. In amplitude sweep experiment, the max error could reach 126.00 °/s, which seriously affect the normal operation of the gyroscope. The waveforms of gyroscope outputs under acoustic and vibration interference were almost coincident, which showed the similarity of acoustic and vibration interference. However, the MEMS accelerometer ADXL103 has a very different performance under acoustic and vibration interference, not only the resonant frequency and max error change, but also the error output and interference intensity are nonlinearly related. In amplitude sweep experiment, the max error could reach 9.78 m/s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . In addition, to produce the same effect on MEMS inertial sensors, the power required of vibration interference was much less than that of acoustic interference. The effectiveness against vibration interference of the filtering algorithm based on orthogonal demodulation was verified by testing the self-developed gyroscope. To the best of our knowledge, it is the first time that use the IQ two-channel orthogonal demodulation filtering algorithm to eliminate vibration interference. The elimination effect was over 97%.

Multi-group neutron cross section generation capability for FRENDY nuclear data processing code

ABSTRACT The multi-group cross-section generation capability for neutrons is implemented in the FRENDY nuclear data processing code. ACE-formatted files are used as the source of nuclear data instead of ENDF-formatted files since FRENDY already has the capability to generate pointwise cross sections in the ACE format. The several distinguished features are implemented for the multi-group generation capability, e.g. explicit consideration of resonance interference effect among nuclides, enhanced resonance treatment for various nuclear reactions, and accurate numerical integration of thermal cross sections. Verification calculations of the newly implemented capability are carried out through the comparison with the NJOY nuclear data processing code. Cross-section generations for all nuclides in JENDL-4.0, -4.0u, -, ENDF/B-VII.1, -VIII.0, JEFF-3.3, and TENDL-2019 are carried out without unexpected processing issues, except for Pu-238 of TENDL-2019 that includes inconsistent data. The verification results indicate that the multi-group cross sections generated by FRENDY are consistent with those generated by NJOY. Now FRENDY can generate not only the pointwise cross sections for continuous energy Monte-Carlo codes but also the multi-group cross sections for deterministic neutronics analysis codes.

Investigation of the efficiency optimization for the improved subgroup resonance self-shielding treatment on the GPU platform

The improved subgroup method adopts a fine energy mesh to handle the resonance interference effect, then the neutron slowing-down equation is solved for group condensation to obtain the multigroup cross section. A large calculating burden is raised in this process. In this paper, an acceleration scheme by the multigroup kernel method is investigated on both GPU and CPU platform. First, the subgroup fixed source and the neutron slowing-down equations are both defined to multigroup kernels to prevent the repetitive MOC sweep, and the group batch is introduced to save the memory usage. Then, the resonance treatment code is developed on the CPU/GPU heterogeneous clusters. Finally, the efficiency between the multigroup kernel and conventional group-by-group method is compared. The numerical verification shows that the multigroup kernel method in the GPU platform could effectively accelerate the solutions of both subgroup fixed source and neutron slowing-down equations.

A New Resonance Calculation Method Using Energy Expansion Based on a Reduced Order Model

A Resonance calculation using energy Spectrum Expansion (RSE) method is newly proposed in this paper. In this method, ultra-fine-group (UFG) spectra appearing in a resonance calculation are expanded by orthogonal bases on energy, which are extracted from the UFG spectra obtained in homogeneous geometry with various background cross sections using singular value decomposition and low-rank approximation. Namely, this method is based on the concept of a reduced order model. A neutron transport equation for flux moments (expansion coefficients) similar to the conventional one is derived and is numerically solved. This method applies to two benchmark problems in which a resonance interference effect and spatial self-shielding effect can appear. The results indicate that this method accurately predicts the reference effective cross sections and reaction rates obtained from direct UFG calculation in heterogeneous geometry.

A RESONANCE CALCULATION METHOD USING ENERGY EXPANSION BASED ON A REDUCED ORDER MODEL: USE OF ULTRA-FINE GROUP SPECTRUM CALCULATION AND APPLICATION TO HETEROGENEOUS GEOMETRY

A Resonance calculation using energy Spectral Expansion (RSE) method has been recently proposed in order to efficiently treat complicated heterogeneous geometry and resonance interference effect. In the RSE method, ultra-fine group spectra are generated from ultra-fine group calculations in homogeneous geometry, and the spectra are expanded by the orthogonal basis on energy based on the singular value decomposition. Then the transport calculation for expansion coefficients is numerically performed, and the ultra-fine group spectra in the target heterogeneous regions are reconstructed by the expansion coefficients and the orthogonal basis. In this study, the RSE method is applied to multi-cell geometries including UO2, MOX and water cells, in which the resonance interference effect between UO2 and MOX fuel cells appears. The validity of the RSE method is confirmed through comparison with the reference effective multi-group cross sections obtained from the direct ultra-fine group calculation in the target heterogeneous geometry.

RESONANCE SELF-SHIELDING CALCULATION FOR PLATE-TYPE FUEL ASSEMBLIES

Owing to its ability to handle arbitrary geometry and high computation efficiency, subgroup method is a widely used resonance self-shielding method. Ordinarily, the subgroup parameters are generated from homogenous resonance integral tables, and then can be used to calculate heterogeneous problems via the equivalence theory. However, it cannot provide accurate results especially for the plate-type assemblies with strong heterogeneity. What’s more, the fuel enrichment in plate-type assemblies is relatively much higher than the common rod-type ones. As a result, the resonance interference effect in plate-type fuels is particularly intense. To solve this problem and to provide accurate effective self-shielded cross-sections for plate-type fuel assemblies, 1-D plate problems are used to generate subgroup parameters. In order to deal with resonance interference, the resonance interference factors are generated by equivalent homogenous problems solved by 0-D hyperfine group solver. To avoid the computational burden caused by too many hyperfine group calculations, the importance of resonance isotopes is calculated in advance to select important resonance isotopes. Important and non-important ones are handled by different ways respectively. JRR-3M plate-type assemblies are used to test the newly method. Numerical results show that the relative errors of effective self-shielded cross-sections are generally less than 1.5% compared with the reference.

Gain-induced scattering anomalies of diffractive metasurfaces

Abstract Photonic nanostructures with gain and loss have long been of interest in the context of diverse scattering anomalies and light-shaping phenomena. Here, we investigate the scattering coefficients of simple gain-doped diffractive metasurfaces, revealing pairs of scattering anomalies surrounded by phase vortices in frequency–momentum space. These result from an interplay between resonant gain, radiative loss, and interference effects in the vicinity of Rayleigh anomalies. We find similar vortices and singular points of giant amplification in angle-resolved reflectivity spectra of prism-coupled gain slabs. Our findings could be of interest for gain-induced wavefront shaping by all-dielectric metasurfaces, possibly employing gain coefficients as low as ∼50 cm−1.

Evaluation of improved subgroup resonance treatment based on Sanchez-Pomraning method for double heterogeneity in PWR

The feasibility of the improved subgroup method coupled with the Sanchez-Pomraning Method (ISSP) is analyzed for the resonance self-shielding calculation of double heterogeneity (DH) problems in PWR. The Sanchez-Pomraning method is developed for both fixed source and the eigenvalue problems. The improved subgroup method adopts a fine-mesh energy structure to handle the resonance interference effect. In this process, the subgroup fixed source equations are solved to get the fine-mesh cross section and the slowing-down equations are solved for group condensation. To extend the improved subgroup method to DH condition, the Sanchez-Pomraning method is applied twice to the subgroup fixed source equation and slowing-down equation respectively. Afterward, the Sanchez-Pomraning method is used the third time for multi-group transport problems. The ultra-fine group method coupled with the Sanchez-Pomraning method (UFGSP) is also established for comparison with ISSP. Numerical validation shows that both ISSP and UFGSP could treat the DH resonance effect precisely.

Fitting-based resonance database method for resonance self-shielding calculations of large-scale task considering depletion and intra-pin distribution

A fitting-based resonance database method is proposed to perform self-shielding calculation for large-scale problems. The intra-pin radial effects are also treated by this method. The new method is mainly divided into two steps. First, the operating conditions of different pin-cells existing in the target problem are simulated by the adjustments of the parameters of single pin-cell cases. The ultra-fine-group slowing-down solving process is performed for these pin-cells and the resonance database for the target problem is fitted using the obtained results. Second, the target problem is calculated using the resonance database generated. Transport calculations are performed at both steps to establish the equivalence relationship between the target problems and the single pin-cell cases. Several techniques are adopted to evaluate the resonance interference and radial effects. Numerical tests prove that the method is capable to give the accurate prediction for the spatial-dependent resonance self-shielded cross-sections in an efficient way.

The on-the-fly subgroup method capable of treating spatial self-shielding, resonance interference and temperature distribution effects

The pseudo-resonant-nuclide subgroup method (PRNSM) based global-local self-shielding calculation scheme was recently developed to resolve the spatial self-shielding and resonance interference effects for large-scale problems. But the PRNSM is not able to treat non-uniform temperature distribution. The reason is that the PRNSM generates physical probability tables at different temperatures with inconsistent subgroup probabilities. To overcome this defect, the on-the-fly subgroup method (OSM), which is an improvement of the PRNSM, is proposed. The new method generates the physical probability tables for different temperatures with shared subgroup probabilities and is able to treat non-uniform temperature distribution. This method replaces the PRNSM in the global-local self-shielding calculation scheme and is implemented in the high-fidelity neutronics code NECP-X. The numerical results show that the OSM can treat the spatial self-shielding effect, the resonance interference effect and the non-uniform temperature effect simultaneously. Besides, NECP-X is able to predict fuel temperature coefficients with high accuracy.

Polarized vector boson scattering in the fully leptonic WZ and ZZ channels at the LHC

Isolating the scattering of longitudinal weak bosons at the LHC is an important tool to probe the ElectroWeak Symmetry Breaking mechanism. Separating polarizations of W and Z bosons is complicated, because of non resonant contributions and interference effects. Additional care is necessary when considering Z bosons, due to the γ/Z mixing in the coupling to charged leptons. We propose a method to define polarized signals in ZZ and W+Z scattering at the LHC, which relies on the separation of weak boson polarizations at the amplitude level in Monte Carlo simulations. After validation in the absence of lepton cuts, we investigate how polarized distributions are affected by a realistic set of kinematic cuts (and neutrino reconstruction, when needed). The total and differential polarized cross sections computed at the amplitude level are well defined, and their sum reproduces the full results, up to non negligible but computable interference effects which should be included in experimental analyses. We show that polarized cross sections computed using the reweighting method are inaccurate, particularly at large energies. We also present two procedures which address the model independent extraction of polarized components from LHC data, using Standard Model angular distribution templates.

Analysis of Categorical Subgroup Method for Resonance Self-Shielding Treatment

To meet the requirements of one step lattice calculation on resonance effect, a self-developed design and construction of a resonance treatment code are composed based on subgroup method and HELIOS-1.11 library. Subgroup fixed source equations are solved by method of characteristics to get subgroup fluxes, which are subsequently used to deduce effective resonance cross sections combined with subgroup weights and subgroup levels. Bondarenko method is employed to handle resonance interference effect and a resonance category scheme and resonance geometry simplification method are introduced to improve efficiency. Benchmarks of single pin cells and assemblies of light water reactor are adopted for numerical validation and the calculating results indicate that this method can treat resonance effect both precisely and effectively.

Improvements of the Embedded Self-Shielding Method with Pseudo-Resonant Isotope Model on the Multifuel Lattice System

The deviations brought by the embedded self-shielding method with the pseudo-resonant isotope model is investigated. Numerical results show that error sources mainly come from the inconsistency in the heterogeneous resonance integral (RI) generated in the two-dimensional square pin–cell case with reflective boundary conditions. The high-order resonance interference effect also contributes to the deviation. The black assumption on the macroscopic cross section of the fuel is proposed to enhance the consistency in the generation of the heterogeneous RI table. Numerical results show that the modification on the original embedded self-shielding method improves the accuracy of the cross-section prediction in the multifuel lattice systems.

Modeling of Resonance-Interference Effect in Depleted Fuel Compositions by Pseudo Resonant Isotopes

In order to develop an efficient resonance self-shielding method that can model the complex resonance-interference effects in depleted fuel compositions, an improved Pseudo Resonant Isotope Model (PRIM) has been developed by incorporating a number density–perturbation technique in the resonance cross-section tables for pseudo isotopes. Numerical results for homogeneous mixtures, pin cells, and pressurized water reactor lattice problems show that the new model is able to produce accurate group cross sections for a wide range of depletion states of different types of fuels, comparable to those obtained from online ultra-fine-group slowing-down calculations. Computational cost analysis shows that the improved PRIM is a promising method applicable to the resonance self-shielding calculations for large-scale reactor core analysis with depletion.

Improvement and optimization of the pseudo-resonant-nuclide subgroup method in NECP-X

The pseudo-resonant-nuclide subgroup method is a newly emerged self-shielding calculation method to treat resonance interference effect. It has been implemented in the NECP-X code which is developed for the high-fidelity neutronics calculation. Though this method has high accuracy, its computation time occupies more than half of the total computation time (mainly including resonance self-shielding calculation, multi-group transport calculation and depletion calculation). To improve the efficiency of the resonance self-shielding calculation, some analysis and optimization are performed in several aspects: firstly, the maximum number of subgroups is reduced from 7 to 5; secondly, the number of dilution cross section points is reduced from 21 to 9; thirdly, the number of fuel meshes in solving SFSE is reduced from 15 to 5; finally, number of fuel meshes in solving one-group fixed-source equation for the SPH factor is reduced from 15 to 1. The acceleration ratio of the self-shielding calculation is 3.45 for assembly without poison and 3.49 for assembly with poison. The time proportion of self-shielding calculation is reduced to less than 30%. The accuracy loss is negligible in the accelerations. Besides, it is found that the subgroup condensation scheme can obtain better self-shielded cross sections of component resonant nuclides than the dilution interpolation scheme.

Resonance self-shielding treatment and analysis of resonance integral tables for Fully Ceramic Micro-encapsulated fuels with the Embedded Self-Shielding Method

A resonance calculation method for Fully Ceramic Micro-encapsulated (FCM) fuels containing stochastically dispersed tri-structural isotropic (TRISO) coated fuel particles has been proposed in this research. The purpose is to obtain effective homogenized resonance cross sections representing the effect of double heterogeneity (DH). The Monte Carlo code MVP is used to solve the heterogeneity in the isolated FCM fuels pin, and to couple with the method of characteristic (MOC) to generate heterogeneous resonance integral (RI) tables for the following Embedded Self-Shielding Method (ESSM) based resonance calculation. The ESSM method is employed to treat the heterogeneity in the lattice (Dancoff effect). Heterogeneous RI tables based on different packing fraction may differ in relationship between background and self-shielded cross sections. Analysis of this distinction’s impact on ESSM calculation has been conducted. Furthermore, resonance interference effect is neglected in ESSM because heterogeneous RI tables are developed for isolated resonant nuclide system. Therefore, Resonance Interference Factor (RIF) Method was applied to correct cross sections from ESSM. To obtain RIF, slowing-down equation need be solved twice for different homogeneous systems. Whereas, the cross section neglecting interference effect could be received by interpolating in homogeneous RI tables to improve efficiency. Evaluation of errors caused by interpolation in RIF method was performed with reference solutions from MVP. Numerical results show that the new method is proved effective in DH capability for resonance self-shielding calculation.

The pseudo-resonant-nuclide subgroup method based global–local self-shielding calculation scheme

ABSTRACT The pseudo-resonant-nuclide subgroup method (PRNSM) based global–local self-shielding calculation scheme is proposed to simultaneously resolve the local self-shielding effects (including spatial self-shielding effect and the resonance interference effect) for large-scale problems in reactor physics calculations. This method splits self-shielding calculation into global calculations and local calculations. The global calculations obtain the Dancoff correction factor for each pin cell by neutron current method. Then an equivalent one-dimensional (1D) cylindrical problem for each pin cell is isolated from the lattice system by preserving Dancoff correction factor. The local calculation is to perform self-shielding calculations of the equivalent 1D cylindrical problem by the PRNSM. The numerical results show that PRNSM obtains accurate spatial dependent self-shielded cross sections and improves the accuracy of dealing with the resonance interference over the conventional Bondarenko iteration method and the resonance interference factor method. Furthermore, because both global and local calculation is linearly proportional to the size of problems, the global–local calculation scheme could be applied to large-scale problems.

Pseudo-resonant-nuclide subgroup method capable to precisely treat spatial self-shielding effect

Considering that the conventional Bondarenko-Iteration Method (BIM) would introduce much error in treating resonance interference effect, the Resonance-Interference-Factor Method (RIFM) and the Heterogeneous-Pseudo-Resonant-Isotope Method (HPRIM) was developed by researchers. Though these two methods can give relatively precise pin-averaged self-shielded cross sections by considering resonance interference effect, they cannot give exact spatial dependent self-shielded cross sections for coarsely modeling spatial self-shielding effect. In order to overcome this problem, the Pseudo-Resonant-Nuclide Subgroup Method (PRNSM) is proposed in this paper. The PRNSM takes into account the resonance interference effect by making resonance cross section table of the pseudo resonant nuclide on-line. The subgroup parameters of the pseudo resonant nuclide and the partial resonant nuclide are obtained by fitting method. The spatial dependent self-shielded cross sections are obtained by condensing the subgroup cross sections of the partial resonant nuclide with the subgroup flux which is obtained by solving subgroup fixed source problem of the pseudo resonant nuclide. The numerous numerical results show that the PRNSM can give both precise pin-averaged self-shielded cross sections and precise spatial dependent self-shielded cross sections for UO2 problems with different enrichments.