Investigation of Rotating Eddy Current Testing Simulation Using Simplified Model

To reduce the time of simulation for rotating Eddy current testing (RECT) technique, a simplified model without modeling probe was proposed previously. However, the applicability of the simplified simulation model was unknown. In this paper, the applicability of the simplified model for the RECT technique was investigated. The application condition of the simplified model was provided by comparing it with the results of the traditional simulation model. The simplified model was suitable for the study of cracks shorter than 70% size of the uniform Eddy current induced by the probe in a traditional model or experiment. The experiment was conducted to validate the simplified model. Moreover, using the simplified model, the effects of crack depth, orientation, and exciting frequency were studied. The deeper the crack depth was, the greater peak value of [Formula: see text] signal was. The crack angle was linear with the phase of signal. The exciting frequency affected the amplitude and phase of the signal at the same time.

Bounds on dark matter annihilation cross-sections from inert doublet model in the context of 21-cm cosmology of dark ages

We study the fluctuations in the brightness temperature of 21-cm signal [Formula: see text] at the dark ages ([Formula: see text]) with a dark matter (DM) candidate in Inert Doublet Model (IDM). We then explore the effects of different fractions of IDM DM on [Formula: see text] signal. The IDM DM masses are chosen in few tens of GeV region as well as in the high mass region beyond 500 GeV. It has been observed that the [Formula: see text] signal is more sensitive in the DM mass range of 70–80 GeV. A lower bound on annihilation cross-section for this DM is also obtained by analyzing the [Formula: see text] signal. This is found to lie within the range [Formula: see text] cm3/s for the IDM DM mass range 10 GeV[Formula: see text] GeV.

Transforming a time-domain electromagnetic signal to a frequency-domain electromagnetic response using regularization inversion

Wide applications of time-domain electromagnetic (TEM) data require 3D inversion. A possible strategy is to use the developed 3D inversion algorithms in frequency-domain (FD) electromagnetic (EM) methods. Thus, the key of the strategy is how to transform the time-domain ([Formula: see text]-[Formula: see text]) EM signal into the FD. An inversion algorithm has been developed to transform the [Formula: see text]-[Formula: see text] signal into a corresponding FD response. In this method, a step-off current is presumed. Under this assumption, the Fourier transform relating the EM FD response to the [Formula: see text]-[Formula: see text] signal becomes a sine or cosine transformation. Using the polynomial approximation method, the transformation turns into a linear equation. From a set of [Formula: see text]-[Formula: see text] signals, FD responses could be obtained by solving these linear equations in the least-squares sense. To reduce the nonuniqueness of the solution, and enhance the solution stability, an additional smoothness constraint on the FD response is imposed, thus converting the minimization problem into a regularization inversion problem. The algorithm is applied to synthetic and field vertical magnetic data in the in-loop TEM surveying mode. The numerical results show that in the entire audio-frequency range, the relative errors between the inversed and theoretical FD responses of the real and imaginary parts are almost all less than 1%, with the largest discrepancy of 5% occurring at high frequencies. There are two significances behind our work: First, the possibility of accurately transforming [Formula: see text]-[Formula: see text] response into FD response in audio-frequency range is coming into true, thereby (from the mathematical perspective) implementing the equivalence between the responses of the EM method in the time domain and the FD. Second, the algorithm provides a new approach to interpret TEM data in 3D mode by using developed 3D FEM inversion techniques.

Higgs pair signal enhanced in the 2HDM with two degenerate 125 GeV Higgs bosons

We discuss a scenario of the type-II two-Higgs-doublet model (2HDM) in which the [Formula: see text] rate of the Higgs pair production is enhanced due to the two nearly degenerate 125 GeV Higgs bosons (h, H). Considering various theoretical and experimental constraints, we figure out the allowed ranges of the trilinear couplings of these two Higgs bosons and calculate the signal rate of [Formula: see text] from the productions of Higgs pairs (hh, hH, HH) at the large hadron collider (LHC). We find that in the allowed parameter space some trilinear Higgs couplings can be larger than the Standard Model (SM) value by an order and the production rate of [Formula: see text] can be greatly enhanced. We also consider a “decoupling” benchmark point where the light CP-even Higgs has a SM-like cubic self-coupling while other trilinear couplings are very small. With a detailed simulation on the [Formula: see text] signal and backgrounds, we find that in such a “decoupling” scenario the hh and hH channels can jointly enhance the statistical significance to 5[Formula: see text] at 14 TeV LHC with an integrated luminosity of 3000 fb[Formula: see text].

Differentiating tidal and groundwater dynamics from barrier island framework geology: Testing the utility of portable multifrequency electromagnetic induction profilers

Electromagnetic induction (EMI) techniques are becoming increasingly popular for near-surface coastal geophysical applications. However, few studies have explored the capabilities and limitations of portable multifrequency EMI profilers for mapping large-scale ([Formula: see text]) barrier island hydrogeology. The purpose of this study is to investigate the influence of groundwater dynamics on apparent conductivity [Formula: see text] to separate the effects of hydrology and geology from the [Formula: see text] signal. Shore-normal and alongshore surveys were performed within a highly conductive barrier island/wind-tidal flat system at Padre Island National Seashore, Texas, USA. Assessments of instrument calibration and signal drift suggest that [Formula: see text] measurements are stable, but vary with height and location across the beach. Repeatability tests confirm [Formula: see text] values using different boom orientations collected during the same day are reproducible. Measurements over a 12 h tidal cycle suggest that there is a tide-dependent step response in [Formula: see text], complicating data processing and interpretation. Shore-normal surveys across the barrier/wind-tidal flats show that [Formula: see text] is roughly negatively correlated with topography and these relationships can be used for characterizing different coastal habitats. For all surveys, [Formula: see text] increases with decreasing frequency. Alongshore surveys performed during different seasons and beach states reveal a high degree of variability in [Formula: see text]. Here, it is argued that surveys collected during dry conditions characterize the underlying framework geology, whereas these features are somewhat masked during wet conditions. Differences in EMI signals should be viewed in a relative sense rather than as absolute magnitudes. Small-scale heterogeneities are related to changing hydrology, whereas low-frequency signals at the broadest scales reveal variations in framework geology. Multiple surveys should be done at different times of the year and tidal states before geologic interpretations can confidently be made from EMI surveys in coastal environments. This strategy enables the geophysicist to separate the effects of hydrology and geology from the [Formula: see text] signal.

New-Type Biosensor Based on Multiple Total-Internal Reflections in Heterodyne Interferometry

In this paper, a novel biosensor based on multiple total-internal reflections (MTIRs) in heterodyne interferometry (HI) is proposed. The biosensor is made of an elongated prism. As a heterodyne optical light source transmits through the new-type biosensor, it will undergo multiple total-internal reflections (MTIRs). Thus we can obtain the text signal at the output. The phase difference variation due to the different refractive indices of the tested media can be obtained by a Lock-In-amplifier (LIA). By some numerical calculations, we can achieve the related parameters of the tested medium. The resolution of the sensor can reach 4×10-7 refractive index unit (RIU). The electro-optical biosensor has some merits, easy operation, in real-time measurement, and high stability, etc.

ON THE "LSND ANOMALY"

In the LSND experiment at the Los Alamos National Laboratory, a larger than expected [Formula: see text] signal was observed and interpreted as evidence of the oscillation [Formula: see text] with Δm2 in the range of 0.2–10 eV2. Since such a Δm2 range is incompatible with the widely accepted model of oscillations between three light neutrino species, and since there was no confirmation from other neutrino experiments, this finding became known as the "LSND anomaly". If true, it would require the existence of at least one "sterile" neutrino which calls the Standard Model of particle physics in a nontrivial way into question. This review discusses the current status of the "LSND anomaly", including the prospects of further experimental checks.

THE FLAVOR-CHANGING BOTTOM AND ANTISTRANGE QUARK PRODUCTION IN THE ONE-GENERATION TECHNICOLOR MODEL AT THE ILC

The Technicolor (TC) model is a dynamical theory without fundamental scalars. Due to the pseudo-Goldstone bosons, there exist some new flavor-changing (FC) couplings in the TC model which can contribute to the production rates of some FC processes. In this paper, we study the [Formula: see text] production process in the one-generation technicolor model (OGTM) at the ILC, i.e. [Formula: see text]. We find that the cross section [Formula: see text] with the OGTM's contributions can be largely enhanced and the [Formula: see text] signal should be observable at the ILC. Our predictions can be viewed as valid estimates of other TC models. Therefore, the process [Formula: see text] may provide a unique window for studying the TC theory.

Study of riverine deposits using electromagnetic methods at a low induction number

We conducted electromagnetic (EM) profiles along the Po River in Turin, Italy. The aim of this activity was to verify the applicability of low-induction-number EM multifrequency soundings carried out from a boat in riverine surveys and to determine whether this technique, which is cheaper than air-carried surveys, could be used effectively to define the typology of sediments and to estimate the stratigraphy below a riverbed. We used a GEM-2 handheld broadband EM sensor operating with six frequencies to survey the investigated area. Ground-penetrating radar (GPR), a conductivity meter, and a time-domain reflectometer were used to estimate the bathymetry and to measure the EM properties of the water. A global positioning system, working in real-time kinematic mode, tracked the route of the boat with centimetric accuracy. We analyzed the induction number, the depth of investigation (DOI), and the sensitivity of our experimental setup by forward modeling — varying the water depth, frequency, and bottom-sediment resistivity. The simulations optimized the choice of the frequencies that could be used reliably for the interpretation. The [Formula: see text] signal had a DOI in the Po River water [Formula: see text] of [Formula: see text] and provided sediment resistivities higher than [Formula: see text]. We applied a bathymetric correction to the conductivity data using the water depths obtained from the GPR data. We plotted a map of the river bottom resistivity and compared this map to the results of a direct sediment sampling campaign. The resistivity values [Formula: see text] were compatible with the saturated gravel and pebbles in a sandy matrix, which resulted from direct sampling and with the known geology.