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11 pags., 10 figs., 2 tabs., The coherent coupling between a quartz electro-mechanical resonator at room temperature and trapped ions in a 7 T Penning trap has been demonstrated for the first time. The signals arising from the coupling remain for integration times in the orders of seconds. From the measurements carried out, we demonstrate that the coupling allows detecting the reduced-cyclotron frequency (ν +) within times in the order of the decay-time constant of the energized resonator (below 10 ms), regardless of the data-acquisition time-window in use, and providing an improved resolution compared to conventional electronic detection schemes. A resolving power ν +/Δν + = 2.4 107 has been reached in single measurements. In this publication we present the first results, emphasizing the novel features of the quartz resonator as fast non-destructive ion-trap detector together with different ways to analyze the data and considering aspects like precision, resolution and sensitivity., We acknowledge support from the Spanish MCINN through the projects FPA2015-67694-P, and PID2019-104093GB-I00/AEI/10.01339/501100011033, and contract number PTA2018-016573-I, from the Spanish Ministry of Education through PhD fellowship FPU17/02596, and from the University of Granada ‘Plan propio-Programa de Intensificacion de la Investigacion’, project PP2017-PRI.I-04 and ‘Laboratorios ´ Singulares 2020’. The construction of the facility was supported by the European Research Council (contract No. 278648-TRAPSENSOR), the above-mentioned project FPA2015-67694-P, project FPA2012-32076, and the infrastructure projects UNGR10-1E-501, UNGR13-1E-1830 and EQC2018- 005130-P (MICINN/FEDER/Universidad de Granada), and the infrastructure projects IE-5713 and IE2017-5513 (Junta de Andalucía-FEDER). MB and SL acknowledge financial support by the German BMBF in the project 05P18UMFN1. JJGR acknowledges support from CSIC Technology Platform PTI-001 and CAM PRICYT project QUITEMAD+CM S2013-ICE2801.

FBG based sensors can be used to detect middle/high frequency elastic waves via intensity demodulation. Temperature change or structural deformation at the location where the sensing FBG is adhered may shift the FBG spectrum and mismatch the interrogator filter and sensing FBG spectra, leading to sensing failure. This paper proposes a broadband elastic wave measurement system with a trackable work point based on dual FBGs + PZT. Wherein, one FBG is pasted on the PZT as a filter and tracker. Via applying AC+DC excitation to the PZT and sweeping the DC bias, the two FBGs' spectra are autonomously matched by searching the max amplitude of the receiving AC signals to maintain high sensitivity. It is experimentally demonstrated that the proposed system can detect up to 500kHz broadband elastic waves. The proposed system is replicated four sets that are successfully used for detecting and locating the impact on an aluminum plate.

Conventional classical sensors are approaching their maximum sensitivity levels in many areas. Yet these levels still are far from the ultimate limits dictated by quantum mechanics. Quantum sensors promise a substantial step ahead by taking advantage of the salient sensitivity of quantum states to the environment. Here, we focus on sensing rotations, a topic of broad application. By resorting to the basic tools of estimation theory, we derive states that achieve the ultimate sensitivities in estimating both the orientation of an unknown rotation axis and the angle rotated about it. The critical enhancement obtained with these optimal states should make of them an indispensable ingredient in the next generation of rotation sensors that is now blossoming., 28 pages, 4 figures. Comments welcome!

Based on five different nonempirical (calculated ab initio) interaction potentials for pairs of colliding Li – Ne particles and three different interaction potentials for pairs of colliding Li – Ar particles, we have theoretically investigated the spectral features of the light-induced drift (LID) rate of Li atoms in the buffer Ne gas in a mixture of buffer Ne + Ar gases. The calculations of LID of Li atoms in the buffer Ne gas for two interaction potentials predict anomalous LID and, as a result, strong sensitivity of the spectral shape of the LID lines to the differences in these potentials. For three other potentials (out of the five in question), the shape of the LID line of Li atoms in Ne is insensitive to the shape of the potential, since calculations with these potentials predict a normal LID effect. In this case, as it turned out, by adding a small fraction (approximately 10 %) of Ar to Ne, one can go from normal LID to anomalous LID and thereby radically increase the sensitivity of the LID line shape of Li atoms to the difference in these interaction potentials. The results obtained enable high-precision testing of the interatomic interaction potentials in experiments on anomalous LID.

A surface profile measurement system was developed by combining a Scanning Electrostatic Force Microscope (SEFM) and a nano-measuring machine (NMM-1) and its characteristics were evaluated. SEFM is a type of Scanning Probe Microscope (SPM) advocated in 2012. In SEFM, eliminating the trade-off between measurement accuracy, measurement speed, and stability has been a problem. As with other SPMs, the positioning accuracy of the probe and sample directly affects the measurement accuracy in SEFM. In this research, the SEFM principle was applied to the NMM-1, which is a high-precision positioning platform that achieves an uncertainty of smaller than 10 nm. In order to improve the force detection sensitivity, a probe polishing and assembling procedures was devised and, as a result, the quality factor of the sensor has been significantly improved. Furthermore, a method for optimizing scan parameters based on a theoretical model was proposed. The noise level of the measurement results was reduced by setting appropriate parameters, which agreed well with the theory. Profile measurements utilizing the developed measurement system were performed on line-and-space samples with an amplitude of 270 nm and a pitch of 10 μm. The results were compared with a conventional Atomic Force Microscope (AFM) as a reference. A surface measurement was performed on the sample, and a complete non-contact scan of a measurement range of 25 μm × 25 μm was demonstrated.

Single metal thermocouples (SMTs) have recently been developed with a new design concept of width-engineering of metal segments. In such designs, two segments of different micro-width are formed to obtain different levels of Seebeck effects. The variations in the Seebeck effect achieved from dissimilar segment width are small. In addition, the fabrication of such micro-width patterns requires special fabrication facilities such as photolithography or electron-beam lithography. In this paper, an alternative method is presented that has the potential to give high thermal sensing SMTs and requires no sophisticated facilities to fabricate. The method is based on thickness-engineering instead of width-engineering, and thus devices can be obtained from commonly available thin film deposition techniques. Constructing better thermal sensing SMTs is possible with this approach as thickness can be easily and conveniently varied down to nanoscale range which is necessary to achieve significant changes in the Seebeck effects from effectively utilizing size effects. As a result, a high thermal sensing bismuth based-SMT has been fabricated with a sensitivity of as high as 31 μV K−1, one of the highest values reported for SMTs. It is straightforward, more convenient over width-engineering approach and thus SMTs can be easily developed.

The benefits conferred by the thermal stability, very low detection limit, and high sensitivity of planar Hall effect (PHE) sensors have supported up-to-date diversity of applications like nT magnetometer, current sensing, or low magnetic moments detection in lab-on-a-chip devices. Herein, we demonstrate in this review the implications linked to planar Hall effect sensors, initiating from the backbone of PHE and its evolution throughout the recent few decades. Key parameters affecting sensors' performance such as noise different sources, thermal stability, and magnetoresistance magnitude are discussed. The progression of sensor junction from disk, cross to bridge, ring, and ellipse configuration is delivered. Moreover, the logical sequence of structure from a single magnetoresistive layer to bi-, trilayers, and spin-valves is briefly investigated. Research contributions to the development of these sensors are highlighted with the focus on microfluidics and flexible sensorics areas. The conclusions extracted from this review are beneficial for the production, development, and performance quality validation of planar Hall effect-based devices and microfluidics and future expectations. Not at least, this review can be a valuable source of information for scientists that intend to use PHE for fundamental research or to develop new applications and devices.

In image processing, one of the most fundamental technique is edge detection. It is a process to detect edges from images by identifying discontinuities in brightness. In this research, we present an enhanced Canny edge detection technique. This method integrates local morphological contrast enhancement and Canny edge detection. Furthermore, the proposed edge detection technique was also applied for pneumonia and COVID-19 detection in digital x-ray images by utilising convolutional neural networks. Results show that this enhanced Canny edge detection technique is better than the traditional Canny technique. Also, we were able to produce classifiers that can classify edge x-ray images into COVID-19, normal, and pneumonia classes with high accuracy, sensitivity, and specificity.

A new type of device consisting of a lithium niobate film coupled with a distributed Bragg reflector (DBR) was theoretically proposed to explore and release Bloch surface waves for applications in sensing and detection. The film and grating made of lithium niobate (LiNbO3) were placed on both sides of the DBR and a concentrated electromagnetic field was formed at the film layer. By adjusting the spatial incidence angle of the incident light, two detection and analysis modes were obtained, including surface diffraction detection and guided Bloch detection. Surface diffraction detection was used to detect the gas molecule concentrations, while guided Bloch detection was applied for the concentration detection of biomolecule-modulated biological solutions. According to the drift of the Fano curve, the average sensor sensitivities from the analysis of the two modes were 1560 °/RIU and 1161 °/RIU, and the maximum detection sensitivity reached 2320 °/RIU and 2200 °/RIU, respectively. This study revealed the potential application of LiNbO3 as a tunable material when combined with DBR to construct a new type of biosensor, which offered broad application prospects in Bloch surface wave biosensors.

High-sensitivity electrical properties measurement of composite materials using an interferometric near-field microwave technique is proposed in this paper. A one-port calibration model is developed to relate the measured transmission coefficient to the local properties of the material. To represent the probe–composite sample interaction, an electrical model based on lumped elements is developed. As a demonstration, the complex permittivity and conductivity of composite materials prepared with polyvinyl chloride and different concentrations of graphene are experimentally determined at 2.45 GHz. The obtained results show that the proposed technique is sensitive for the detection of small contrasts of permittivity and conductivity in the composite material. When the graphene concentration increases from 1% to 30%, the conductivity increases from 0.0061 s m−1 to 0.056 s m−1.

Excellent luminescent materials are essential for high-performance fluorescent nanosensors. Here, a new-type of self-calibrated humidity sensor is established through monitoring the fluorescent color change of carbon dots (CDs) confined in sodium hydroxide (CDs@NaOH). The CDs are prepared by a facile and rapid microwave-assisted heating method using citric acid, urea, and NaOH as precursors. The confinement effect from the NaOH reduces the nonradiative transition and suppresses the aggregation-induced quenching of the CDs in the solid. Compared with other sensors based on CD fluorescent visualization, the sensor has good linearity and a wide humidity-detection range from 6.9% to 95.4%. With the increased relative humidity, the fluorescence color of the sensor changes from green to blue. The proposed sensing mechanism is due to the breaking and reforming of hydrogen bonds and proton transfer occurring at the CD-NaOH matrix interfaces. These findings suggest a potential role for the spatial confinement effect and may provide an avenue for developing highly sensitive humidity readouts.

A high sensitivity plasmonic temperature sensor based on a side-polished photonic crystal fiber is proposed in this work. In order to achieve high sensitivity and high stability, the gold layer is coated on the side-polished photonic crystal fiber to support surface plasmon resonance. The mixture of ethanol and chloroform is used as the thermosensitive liquid. The performances of the proposed temperature sensor were investigated by the finite element method (FEM). Simulation results indicate that the sensitivity of the temperature sensor is as high as 7.82 nm/°C. It has good linearity (R 2 = 0.99803), the resolution of 1.1 × 10−3 °C, and the amplitude sensitivity of 0.1008 °C−1. In addition, the sizes of the small air hole and polishing depth have little influence on the sensitivity. Therefore, the proposed sensor shows a high structure tolerance. The excellent performance and high structure tolerance of the sensor make it an appropriate choice for temperature measurement.

Non-Hermitian systems can exhibit unconventional spectral singularities called exceptional points (EPs). Various EP sensors have been fabricated in recent years, showing strong spectral responses to external signals. Here we propose how to achieve a nonlinear anti-parity-time ( A P T ) gyroscope by spinning an optical resonator. We show that, in the absence of any nonlinearity, the sensitivity or optical mode splitting of the linear device can be magnified up to 3 orders compared to that of the conventional device without EPs. Remarkably, the A P T symmetry can be broken when including the Kerr nonlinearity of the materials and, as a result, the detection threshold can be significantly lowered, i.e., much weaker rotations which are well beyond the ability of a linear gyroscope can now be detected with the nonlinear device. Our work shows the powerful ability of A P T gyroscopes in practice to achieve ultrasensitive rotation measurement.

We propose a simple one-dimensional grating coupling system that can excite multiple surface plasmon resonances for refractive index (RI) sensing with self-reference characteristics in the near-infrared band. Using theoretical analysis and the finite-difference time-domain method, the plasmonic mechanism of the structure is discussed in detail. The results show that the excited resonances are independent of each other and have different fields of action. The mode involving extensive interaction with the analyte environment achieves a high sensitivity of 1236 nm/RIU, and the figure of merit (FOM) can reach 145 RIU−1. Importantly, the mode that is insensitive to the analyte environment exhibits good self-reference characteristics. Moreover, we discuss the case of exchanging the substrate material with the analyte environment. Promising simulation results show that this RIsensor can be widely deployed in unstable and complicated environments

Based on the fact that the electronic throttle angle effect performs well in the traditional car following model, this paper attempts to introduce the electronic throttle angle into the smart driver model (SDM) as an acceleration feedback control term, and establish an extended smart driver model considering electronic throttle angle changes with memory (ETSDM). In order to show the practicability of the extended model, the next generation simulation (NGSIM) data was used to calibrate and evaluate the extended model and the smart driver model. The calibration results show that, compared with SDM, the simulation value based on the ETSDM is better fitted with the measured data, that is, the extended model can describe the actual traffic situation more accurately. Then, the linear stability analysis of ETSDM was carried out theoretically, and the stability condition was derived. In addition, numerical simulations were explored to show the influence of the electronic throttle angle changes with memory and the driver sensitivity on the stability of traffic flow. The numerical results show that the feedback control term of electronic throttle angle changes with memory can enhance the stability of traffic flow, which shows the feasibility and superiority of the proposed model to a certain extent.

The energy deposition and electrothermal behavior of SiC metal–oxide–semiconductor field-effect transistor (MOSFET) under heavy ion radiation are investigated based on Monte Carlo method and TCAD numerical simulation. The Monte Carlo simulation results show that the density of heavy ion-induced energy deposition is the largest in the center of the heavy ion track. The time for energy deposition in SiC is on the order of picoseconds. The TCAD is used to simulate the single event burnout (SEB) sensitivity of SiC MOSFET at four representative incident positions and four incident depths. When heavy ions strike vertically from SiC MOSFET source electrode, the SiC MOSFET has the shortest SEB time and the lowest SEB voltage with respect to direct strike from the epitaxial layer, strike from the channel, and strike from the body diode region. High current and strong electric field simultaneously appear in the local area of SiC MOSFET, resulting in excessive power dissipation, further leading to excessive high lattice temperature. The gate–source junction area and the substrate–epitaxial layer junction area are both the regions where the SiC lattice temperature first reaches the SEB critical temperature. In the SEB simulation of SiC MOSFET at different incident depths, when the incident depth does not exceed the device’s epitaxial layer, the heavy-ion-induced charge deposition is not enough to make lattice temperature reach the SEB critical temperature.

This is the Accepted Manuscript version of an article accepted for publication in Journal of Cosmology and Astroparticle Physics. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at https://doi.org/10.1088/1475-7516/2020/10/041, In the absence of a clear hint of dark matter (DM) signals in the GeV regime so far, heavy, O (TeV) DM candidates are gradually earning more and more attention within the community. Among others, extra-dimensional brane-world models may produce termal DM candidates with masses up to 100 TeV. These heavy DM candidates could be detected with the next generation of very-high-energy gamma-ray observatories such as the Cherenkov Telescope Array (CTA). In this work, we study the sensitivity of CTA to branon DM via the observation of representative astrophysical DM targets, namely dwarf spheroidal galaxies. In particular, we focus on Draco and Sculptor, two well-known dwarfs visible from the Northern and Southern Hemisphere, respectively. For each of these targets, we simulated 300 h of CTA observations and studied the sensitivity of both CTA-North and CTA-South to branon annihilations using the latest publicly available instrument response functions and most recent analysis tools. We computed annihilation cross section values needed to reach a 5σ detection as a function of the branon mass. Additionally, in the absence of a predicted DM signal, we obtained 2σ upper limits on the annihilation cross section. These limits lie 1.5 - 2 orders of magnitude above the thermal relic cross section value, depending on the considered branon mass. Yet, CTA will allow to exclude a significant portion of the brane tension-mass parameter space in the 0.1 - 60 TeV branon mass range, and up to tensions of ~ 10 TeV. More importantly, CTA will significantly enlarge the region already excluded by AMS and CMS, and will provide valuable complementary information to future SKA radio observations. We conclude that CTA will possess potential to constrain brane-world models and, more in general, TeV DM candidates, The work of AAS, VG and MASC was supported by the Spanish Agencia Estatal de Investigación through the grants PGC2018-095161-B-I00 and IFT Centro de Excelencia Severo Ochoa SEV-2016-0597, the Atracción de Talento contract no. 2016-T1/TIC-1542 granted by the Comunidad de Madrid in Spain, and the MultiDark Consolider Network FPA2017- 90566-REDC. DN acknowledges support from the former Spanish Ministry of Economy, Industry, and Competitiveness / European Regional Development Fund grant FPA2015-73913-JIN and the MultiDark Consolider Network FPA2017-90566-REDC

Atomic environment fingerprints are widely used in computational materials science, from machine learning potentials to the quantification of similarities between atomic configurations. Many approaches to the construction of such fingerprints, also called structural descriptors, have been proposed. In this work, we compare the performance of fingerprints based on the Overlap Matrix(OM), the Smooth Overlap of Atomic Positions (SOAP), Behler-Parrinello atom-centered symmetry functions (ACSF), modified Behler-Parrinello symmetry functions (MBSF) used in the ANI-1ccx potential and the Faber-Christensen-Huang-Lilienfeld (FCHL) fingerprint under various aspects. We study their ability to resolve differences in local environments and in particular examine whether there are certain atomic movements that leave the fingerprints exactly or nearly invariant. For this purpose, we introduce a sensitivity matrix whose eigenvalues quantify the effect of atomic displacement modes on the fingerprint. Further, we check whether these displacements correlate with the variation of localized physical quantities such as forces. Finally, we extend our examination to the correlation between molecular fingerprints obtained from the atomic fingerprints and global quantities of entire molecules., Comment: 18 pages, 11 figures

arXiv:2006.12935v2, Most of the CMB experiments proposed for the next generation aim to detect the Primordial Gravitational Wave Background (PGWB). The fulfillment of this objective depends on our capacity to separate Galactic foreground emissions and to delens the secondary B-mode component induced by weak gravitational lensing. Focusing on the latter of these efforts, in this work we briefly review the basic aspects of lensing, and exhaustively compare the performance of current delensing methodologies and implementations within the Born approximation as a preparation for the analysis of the data to come in the following years. Two of the main conclusions that can be drawn from our study are that, for next-generation experiments, delensing efficiency will still be limited by the quality of the data itself rather than by the limitations of current delensing methodologies, and that template delensing within the antilensing approximation will be the optimal (balancing accuracy and computational cost) technique to employ. We then evaluate the delensing capabilities of future experiments (like the Simons Observatory, the CMB Stage-IV, or the LiteBIRD and PICO satellites) by applying that methodology onto numerical simulations of the typical CMB and lensing potential reconstructions that they are expected to produce, and quantify how internal and external delensing will help them to improve their sensitivity to detect the PGWB. We also consider the benefits that a joint analysis of their data would provide., PDP acknowledges partial financial support from the Formación del Profesorado Universitario (FPU) programme of the Spanish Ministerio de Ciencia, Innovación y Universidades. We acknowledge Santander Supercomputación support group at the Universidad de Cantabria who provided access to the Altamira Supercomputer at the Instituto de Física de Cantabria (IFCA-CSIC), member of the Red Española de Supercomputación, for performing simulations/analyses. The authors would like to thank the Spanish Agencia Estatal de Investigación (AEI, MICIU) for the financial support provided under the projects with references ESP2017-83921-C2-1-R and AYA2017-90675-REDC, co-funded with EU FEDER funds, and also acknowledge the funding from Unidad de Excelencia María de Maeztu (MDM-2017-0765).

Structural damage tomography (SDT) uses full-field or distributed measurements collected from sensors or self-sensing materials to reconstruct quantitative images of potential damage in structures, such as civil structures, automobiles, aircraft, etc. In approximately the past ten years, SDT has increased in popularity due to significant gains in computing power, improvements in sensor quality, and increases in measurement device sensitivity. Nonetheless, from a mathematical standpoint, SDT remains challenging because the reconstruction problems are usually nonlinear and ill-posed. Inasmuch, the ability to reliably reconstruct or detect damage using SDT is seldom guaranteed due to factors such as noise, modeling errors, low sensor quality, and more. As such, damage processes may be rendered invisible due to data indistinguishability. In this paper we identify and address key physical, mathematical, and practical factors that may result in invisible structural damage. Demonstrations of damage invisibility and data indistinguishability in SDT are provided using experimental data generated from a damaged reinforced concrete beam.

Sensitivity analysis associated with the evaluation of measurement uncertainty is a very important tool for the metrologist, enabling them to provide an uncertainty budget and to gain a better understanding of the measurand and the underlying measurement process. Using the GUM uncertainty framework, the contribution of an input quantity to the variance of the output quantity is obtained through so-called 'sensitivity coefficients'. In contrast, such coefficients are no longer computed in cases where a Monte-Carlo method is used. In such a case, supplement 1 to the GUM suggests varying the input quantities one at a time, which is not an efficient method and may provide incorrect contributions to the variance in cases where significant interactions arise. This paper proposes different methods for the elaboration of the uncertainty budget associated with a Monte Carlo method. An application to the mass calibration example described in supplement 1 to the GUM is performed with the corresponding R code for implementation. Finally, guidance is given for choosing a method, including suggestions for a future revision of supplement 1 to the GUM.

This paper deals with time-global solutions to the parabolic system under the homogeneous Neumann boundary conditions in a bounded and convex domain () with smooth boundary . Here τ is a positive parameter, χ is a smooth function on satisfying and is a pair of nonnegative initial data. We will consider the above system as a perturbation of a nonlocal parabolic equation and establish a sufficient condition of the sensitivity function χ for the global existence of solutions under the assumption of smallness of the constant τ.

The manufacturing of semiconductor devices using extreme ultraviolet (EUV) lithography started in 2019. A high numerical aperture tool under development is capable of resolving 8 nm line-and-space optical images and will extend the application of EUV lithography. However, resist materials have not been yet applicable to the production with 8 nm resolution. In this study, the relationships among the half-pitch of line-and-space patterns (resolution), chemical gradient [an indicator of line edge roughness (LER)], and sensitivity were investigated in the sub-10 nm half-pitch region for chemically amplified EUV resists. The chemical gradient was simulated on the basis of their sensitization and reaction mechanisms. The relationship was formulated as a function of total sensitizer concentration (the sum of photoacid generator and photodecomposable quencher concentrations) and the thermalization distance of secondary electrons. The effect of thermalized electrons was well incorporated into the trade-off relationships between resolution, LER, and sensitivity. (147/150)

In this paper we propose a zonal wavefront sensing scheme that facilitates wavefront measurement with enhanced sensitivity at the standard video rate. We achieve this enhanced sensitivity by implementing a sequential display of binary holograms described over each zone sampling the incident wavefront with the help of a ferroelectric liquid crystal spatial light modulator. By keeping the number of active zones as 24 and using a camera with an imaging frame rate equal to the binary hologram display rate of the spatial light modulator, we are able to reach a sensing frame rate of 60 Hz. In addition to enhanced sensitivity, the proposed scheme facilitates zone-wise tuning of binary holograms and eliminates the possibility of any crosstalk between adjacent zones. We perform a proof-of-principle experiment that validates the proposed zonal wavefront sensing scheme and demonstrates its advantages.

The sensitivity to fault reflection is very important for larger dynamic range in fiber fault detection technique. Using time delay signature (TDS) of chaotic laser formed by optical feedback can solve the sensitivity limitation of photodetector in fiber fault detection. The TDS corresponds to the feedback position and the fault reflection can be detected by the laser diode. The sensitivity to feedback level of circular-side hexagonal resonator (CSHR) microcavity laser is numerically simulated and the feedback level boundaries of each output dynamic state are demonstrated. The peak level of TDS is utilized to analyze the sensitivity. The demonstration is presented in two aspects: the minimum feedback level when the TDS emerges and the variation degree of TDS level on feedback level changing. The results show that the CSHR microcavity laser can respond to the feedback level of 0.07%, corresponding to -63-dB feedback strength. Compared to conventional distributed feedback laser, the sensitivity improves almost 20 dB due to the shorter internal cavity length of CSHR microcavity laser. Moreover, 1% feedback level changing will induce 1.001 variation on TDS level, and this variation degree can be influenced by other critical internal parameters (active region side length, damping rate, and linewidth enhancement factor).

Detection of ultralow magnetic field requires magnetic sensors with high sensitivity and low noise level, especially for low operating frequency applications. We investigated the transport properties of tunnel magnetoresistance (TMR) sensors based on the double indirect exchange coupling effect. The TMR ratio of about 150% was obtained in the magnetic tunnel junctions and linear response to an in-plane magnetic field was successfully achieved. A high sensitivity of 1.85%/Oe was achieved due to a designed soft pinned sensing layer of CoFeB/NiFe/Ru/IrMn. Furthermore, the voltage output sensitivity and the noise level of 10.7 mV/V/Oe, 10 nT/Hz1/2 at 1 Hz and 3.3 nT/Hz1/2 at 10 Hz were achieved in Full Wheatstone Bridge configuration. This kind of magnetic sensors can be used in the field of smart grid for current detection and sensing.

Objective. Alzheimer’s disease (AD), a common disease of the elderly with unknown etiology, has been adversely affecting many people, especially with the aging of the population and the younger trend of this disease. Current artificial intelligence (AI) methods based on individual information or magnetic resonance imaging (MRI) can solve the problem of diagnostic sensitivity and specificity, but still face the challenges of interpretability and clinical feasibility. In this study, we propose an interpretable multimodal deep reinforcement learning model for inferring pathological features and the diagnosis of AD. Approach. First, for better clinical feasibility, the compressed-sensing MRI image is reconstructed using an interpretable deep reinforcement learning model. Then, the reconstructed MRI is input into the full convolution neural network to generate a pixel-level disease probability risk map (DPM) of the whole brain for AD. The DPM of important brain regions and individual information are then input into the attention-based fully deep neural network to obtain the diagnosis results and analyze the biomarkers. We used 1349 multi-center samples to construct and test the model. Main results. Finally, the model obtained 99.6% ± 0.2%, 97.9% ± 0.2%, and 96.1% ± 0.3% area under curve in ADNI, AIBL and NACC, respectively. The model also provides an effective analysis of multimodal pathology, predicts the imaging biomarkers in MRI and the weight of each individual item of information. In this study, a deep reinforcement learning model was designed, which can not only accurately diagnose AD, but analyze potential biomarkers. Significance. In this study, a deep reinforcement learning model was designed. The model builds a bridge between clinical practice and AI diagnosis and provides a viewpoint for the interpretability of AI technology.

We present high resolution thermal expansion measurement data obtained with high relative sensitivity of ΔL/L = 10−9 and accuracy of ± 2 % using closed cycle refrigerators employing two different dilatometers. Experimental details of the set-up utilizing the multi-function probe integrated with the cold head of two kinds of closed cycle refrigerators, namely, pulse tube and Gifford-McMahon cryocoolers, has been described in detail. The design consists of decoupling the bottom sample puck and taking connections from the top of the multi-function probe to mitigate the vibrational noise arising from the cold heads, using which smooth and high quality thermal expansion data could be obtained. It was found that dilatometer#2 performs a better noise mitigation than dilatometer#1 due to the constrained movement of the spring in dilatometer#2. This was confirmed by finite element method simulations that were performed for understanding the spring movement in each dilatometer using which the effect of different forces/pressures and vibrations on the displacement of the spring was studied. Linear thermal expansion coefficient α obtained using both dilatometers was evaluated using derivative of a polynomial fit. The resultant α obtained using dilatometer#2 and either of the closed cycle cryostats on standard metals silver and aluminium showed excellent match with published values obtained using wet cryostats. Finally, thermal expansion measurements is reported on single crystals of two high temperature superconductors YBa2Cu3−x Al x O6+δ and Bi2Sr2CaCu2O8+x along the c-axis with very good match found with published data obtained earlier using wet liquid helium based cryostats.

We present a detailed analysis on measurement sensitivity of dynamic acoustic forces via numerical simulation of the micro-cantilever responses. The rectangular micro-cantilever is regarded as a point mass in the dynamic model of forced and damped harmonic oscillator. We use single- and bimodal-frequency excitation schemes for actuation of the micro-cantilever in the presence of dynamic acoustic forces. In bimodal-frequency excitation scheme, the micro-cantilever is excited at its first two eigenmode frequencies simultaneously as opposed to single-frequency excitation. First, we numerically obtain micro-cantilever deflections by solving the equations of Motions (EOMs) constructed for the first two eigenmodes. Then, we determine oscillation amplitude and phase shift as a function of acoustic force strength within different frequency regions. Moreover, we relate amplitude and phase shift to virial and energy dissipation in order to explore the interaction between flexural modes in multifrequency excitation. The simulation results point out that bimodal-frequency excitation improves the measurement sensitivity of dynamic acoustic forces at particular frequencies. Herein, simultaneous application of driving forces enables higher sensitivities of observables and energy quantities as acoustic force frequencies become around the eigenmode frequencies. For our case, we obtain the highest phase shift (∼178°) for the acoustic force strength of 100 pN at the frequency of around 307.2 kHz. Therefore, this method can be easily adapted to improve measurement sensitivity of dynamic acoustic forces in a wider frequency window.

High temperature superconducting (HTS) rotatory flux pump, or so called HTS dynamo, can output none-zero time-averaged DC voltage and charge the rest of the circuit if a closed loop has been formed. This type of flux pump is often employed together with HTS coils, where the HTS coils can potentially work in persistent current mode, and act like electromagnets with considerable magnetic field, having wide range of applications in industry. The output characteristics of HTS rotary flux pumps have been extensively explored through experiments and finite element method (FEM) simulations, yet the work on constructing statistical models as an alternative approach to capture key characteristics has not been studied and published. A 2D FEM program has been used to model the HTS rotatory flux pumps and evaluate the effects of different factors upon the output voltage through parameter sweeping and analysis of variance. Typical design considerations, including operation frequency, air gap, HTS tape width and remanent flux density have been investigated, in particular the bilateral effect of HTS tape width has been explained by looking at the averaged integration of the electric field over the tape. Based on the data obtained from various simulations, regression analysis has been conducted through a collection of machine learning methods and demonstrated that the output voltage of a rotary flux pump can be obtained promptly with satisfactory accuracy via Gaussian process regression, aiming to provide a novel approach for future research and powerful design tool for industrial applications using HTS rotary flux pump devices.

A high-sensitivity three-core photonic crystal fiber (PCF) sensor based on surface plasmon resonance (SPR) is proposed in this paper. The gold film is selected as the plasmonic metal and coated on the outside surface of the PCF to excite the SPR phenomenon. There are three different diameter air holes of d1, d2, and d3 distributed on the cross-section of the sensor. Among them, sensor performance can be affected by changing the diameter of the central hole and the thickness of the gold film. The sensor shows the maximum confinement loss value and spectral sensitivity of 50 dB cm−1 and 30600 nm RIU−1, respectively, at analyte RI (na = 1.41), and the corresponding maximum resolution is 3.27 × 10–6. The above simulation result shows that the sensor has excellent performance, thus laying the foundation for future research.

High precision phase estimation is at the core of modern physics and practical applications. We investigate a method for high precision phase estimation via inserting a reference state which enables weak measurement technique to be used in wide dynamic range. A reference phase is introduced artificially to offset the time delay between preselection state and reference state. The sensitivity of measured phase and the linear dynamic range are controllable by adjusting reference phase. Moreover, an arbitrary postselection in measurement is applicable by choosing appropriate reference phase. This method has merits of controllable sensitivity and wide dynamic range, which shows great potential practical applications in high precision phase measurement.

Plain silver surface plasmon resonance imaging (SPRi) sensor has been studied extensively due to its high sensitivity and desirable stability in liquid environments. To further enhance sensitivity performance of the sensor, angular sensitivity, angular slope and depth-width ratio (DWR) of SPR curve, and imaging sensitivity are evaluated at different thickness combinations of the gold and silver films respectively. In this work, the angular slope of SPR curve is found to be the critical factor to the optimized imaging sensitivity of plain silver SPRi sensor. In the comparative study, the above parameters of the plain silver SPR sensor, single gold film and bimetallic SPRi sensors are compared. Plain silver SPRi sensor is proved to be of the highest imaging sensitivity, which is 4.08 and 1.18 times imaging sensitivity of the single gold film and bimetallic SPRi sensors separately.

The article presents the results of a preliminary analysis of the numerical model susceptibility for simulating the process of dry ice compaction utilizing single-channel and multiple channel dies. The work focuses on a preliminary comparison of the influence of changes in the geometrical parameters of the 4 types of compression channels. Based on the results of the performed analyses, conclusions were formulated for a basis and direction of further study regarding improving the energy efficiency of the indicated manufacturing process.

National Institute for Environmental Studies (NIES) and Centre for Climate Risk and Opportunity Management in Southeast Asia Pacific (CCROM-SEAP) working together to develop a beneficial monitoring system for measuring air pollutants. The monitoring system consists of system control units and instrument for measuring pollutants and located in a high-rise tower. This system can count how much anthropogenic and nature emission in this region. The primary sources of pollutants from the anthropogenic activity are traffic from vehicular transportation. This research focuses on air pollutants in the form of particulate matter (PM10 and PM2.5), Ozone (O3), methane (CH4), nitrogen oxide (NOx), sulphur dioxide (SO2), and carbon monoxide (CO). This research aims to measure the spatial coverage sensitivity of this NIES monitoring system in capturing the effect of the nearest traffic in Bogor. The method used is a sampling method using one day of data with the criteria of no rain and wind speed below two m/s to avoid washing out pollutants and turbulence from these pollutants. The data used are pollutants data on Saturday, June 6th 2020, as sampling data and data traffic in Bogor City. The result from this research is NIES monitoring system can catch air pollutants in Bogor and can measure as far a radius of 0,01 degrees from the NIES monitoring system.

Flexible strain sensors are emerging rapidly and overcoming the drawbacks of traditional strain sensors. However, many flexible sensors failed to balance the sensitivity, response time, and the desired sensing range. This work proposes a novel and cost-effective strain sensor which simultaneously achieved high sensitivity, fast response, and a good sensing range. It illustrates a prototype strain sensor realized with a nanocomposite constituting reduced graphene oxide and palladium as the primary sensing elements. These sensors were fabricated with manual screen-printing technology. The sensor exhibited an outstanding performance for the different strains ranging from 0.1% to 45%. As a result, a substantially high gauge factor around 1523 at a strain of as high as 45% and a rapid response time of 47 ms was obtained. This work demonstrated potential applications like real-time monitoring of pulse and respiration, and other physical movement detection, which become crucial parameters to be measured continuously during the COVID-19 pandemic.

In view of efficiency, simple operation, and affordable cost and disposability, quartz tuning fork systems form good candidates for mechanical-based biosensors in point of care applications. Based on the geometrical structure, the frequency response of the tuning fork- based sensors is dependent on the location of absorbed samples. In order to have the maximum efficiency and sensitivity, the optimized condition of sample loading on the fork structures should be considered. In this regard, here, we have determined the optimized sample location to be on the prongs of the quartz tuning fork by calculating the frequency response of the quartz tuning fork using the finite element method. From an application point of view, we have obtained an agreement between the calculational method and the experimental excitation technique of the structure. The results from our study show that by using an appropriate location for the sample, the quartz tuning fork could be exploited with high sensitivity.

Acceleration sensor is usually used to test the performance of equipment under high-acceleration vibration. It is widely used in aero-engine, steam turbine and other equipment working in high-acceleration vibration environment. Calibration is an important means to ensure the accuracy and reliability of the measurement results of the acceleration sensor. Aiming at the conventional intermediate frequency (IF) calibration system using many instruments and complicated operation, this paper designs a resonant high-acceleration calibration system based resonant beam. The system amplifies the acceleration amplitude through the resonance of the resonant beam at the natural frequency, thereby generating high-acceleration values to calibrate the sensor. Then the vibration control algorithm of the calibration system is optimized, and the stability of the system is verified through experiments. Finally, the communication between the upper and lower computers is carried out in the vibration control system and the laser measurement system, and the metrological traceability is realized. The experimental results show that the system can effectively calibrate the sensitivity amplitude and phase of high-acceleration sensor in the frequency range of 100-2148 Hz and the acceleration range of 50-11853 m/s2. This calibration system is of great significance to the research on the calibration of IF acceleration sensor.

Herein, a novel nanosensor consisting of a ring resonator with two rectangular stubs and a metal–insulator–metal waveguide with two triangular stubs is proposed. By adopting the finite element method, a Fano resonance is found in the transmission spectrum, which results from the coupling between the discrete narrowband mode and the continuous wideband mode. The physical mechanism is analyzed by the normalized magnetic field distribution, and the effects of structural geometric parameters on the transmission characteristics are studied carefully. The results demonstrate that the maximum sensitivity could reach 2660 nm RIU−1 with the corresponding figure of merit of 66.5. The applications of the structure for hemoglobin concentration detection and temperature measurement are discussed, and the sensitivity of the two applications can reach up to 2.524 nm·l g−1 and 0.831 nm °C−1, respectively. The proposed structure with extremely high sensitivity and compactness can provide an excellent case for designing high-performance integrated plasmonic devices.

A first order phase transition at the electroweak scale would lead to the production of gravitational waves that may be observable at upcoming space-based gravitational wave (GW) detectors such as LISA (Laser Interferometer Space Antenna). As the Standard Model has no phase transition, LISA can be used to search for new physics by searching for a stochastic gravitational wave background. In this work we investigate LISA's sensitivity to the thermodynamic parameters encoded in the stochastic background produced by a phase transition, using the sound shell model to characterise the gravitational wave power spectrum, and the Fisher matrix to estimate uncertainties. We explore a parameter space with transition strengths $��< 0.5$ and phase boundary speeds $0.4 < v_\text{w} < 0.9$, for transitions nucleating at $T_{\text{N}} = 100$ GeV, with mean bubble spacings $0.1$ and $0.01$ of the Hubble length, and sound speed $c/\sqrt{3}$. We show that the power spectrum in the sound shell model can be well approximated by a four-parameter double broken power law, and find that the peak power and frequency can be measured to approximately 10% accuracy for signal-to-noise ratios (SNRs) above 20. Determinations of the underlying thermodynamic parameters are complicated by degeneracies, but in all cases the phase boundary speed will be the best constrained parameter. Turning to the principal components of the Fisher matrix, a signal-to-noise ratio above 20 produces a relative uncertainty less than 3% in the two highest-order principal components, indicating good prospects for combinations of parameters. The highest-order principal component is dominated by the wall speed. These estimates of parameter sensitivity provide a preliminary accuracy target for theoretical calculations of thermodynamic parameters., 37 pages, 11 figures

The use of different material quality and amount can affect formwork performance at the beginning of casting. Practical easy to install formwork such as woven polyethylene with wire mesh reinforcement makes field work easier. Sensitivity analysis on the elastic modulus and the thermal coefficient variables of woven polyethylene, fresh concrete temperature during casting and fresh concrete load model are the objectives of this research. The research is performed by comparing experimental data and the numerical modeling of woven polyethylene formwork using Finite Element Method. The formwork span and width dimension are 1 m x 0.3 m, with a variety of heights namely 0.6 m, 0.45 m, and 0.3 m. The sensitivity value for each variable will be evaluated based on Pearson coefficient or R. The sensitivity analysis of thermal coefficient showed no correlation to changes in formwork deformation. The sensitivity analysis of elastic modulus and fresh concrete temperature showed perfect correlation to changes in formwork deformation although the changes are small (around 0.0003 cm to 0.0006 cm). The fresh concrete load model showed perfect correlation to formwork deformation as well as becoming the determining variable of the changes in the formwork deformation values.

Objective: The automatic discrimination between the coughing sounds produced by patients with tuberculosis (TB) and those produced by patients with other lung ailments. Approach: We present experiments based on a dataset of 1358 forced cough recordings obtained in a developing-world clinic from 16 patients with confirmed active pulmonary TB and 35 patients suffering from respiratory conditions suggestive of TB but confirmed to be TB negative. Using nested cross-validation, we have trained and evaluated five machine learning classifiers: logistic regression (LR), support vector machines (SVM), k-nearest neighbour (KNN), multilayer perceptrons (MLP) and convolutional neural networks (CNN). Main Results: Although classification is possible in all cases, the best performance is achieved using LR. In combination with feature selection by sequential forward selection (SFS), our best LR system achieves an area under the ROC curve (AUC) of 0.94 using 23 features selected from a set of 78 high-resolution mel-frequency cepstral coefficients (MFCCs). This system achieves a sensitivity of 93\% at a specificity of 95\% and thus exceeds the 90\% sensitivity at 70\% specificity specification considered by the World Health Organisation (WHO) as a minimal requirement for a community-based TB triage test. Significance: The automatic classification of cough audio sounds, when applied to symptomatic patients requiring investigation for TB, can meet the WHO triage specifications for the identification of patients who should undergo expensive molecular downstream testing. This makes it a promising and viable means of low cost, easily deployable frontline screening for TB, which can benefit especially developing countries with a heavy TB burden., Comment: This paper has been accepted in Physiological Measurement (2021)

In this paper we study $C^1$-structurally stable diffeomorphisms, that is, $C^1$ Axiom A diffeomorphisms with the strong transversality condition. In contrast to the case of dynamics restricted to a hyperbolic basic piece, structurally stable diffeomorphisms are in general not expansive and the conjugacies between $C^1$-close structurally stable diffeomorphisms may be non-unique, even if there are assumed $C^0$-close to the identity. Here we give a necessary and sufficient condition for a structurally stable diffeomorphism to admit a dense subset of points with expansiveness and sensitivity to initial conditions. Morever, we prove that the set of conjugacies between elements in the same conjugacy class is homeomorphic to the $C^0$-centralizer of the dynamics. Finally, we use this fact to deduce that any two $C^1$-close structurally stable diffeomorphismsare conjugated by a unique conjugacy $C^0$-close to the identity if and only if these are Anosov., 17 pages, 5 figures, final version to appear on Nonlinearity