scholarly journals Advances in 6C seismology: Applications of combined translational and rotational motion measurements in global and exploration seismology

Geophysics ◽  
2018 ◽  
Vol 83 (3) ◽  
pp. WC53-WC69 ◽  
Author(s):  
Cedric Schmelzbach ◽  
Stefanie Donner ◽  
Heiner Igel ◽  
David Sollberger ◽  
Taufiq Taufiqurrahman ◽  
...  
Keyword(s):  
Rotational Motion ◽  
Tomographic Reconstruction ◽  
High Sensitivity ◽  
Seismic Source ◽  
Motion Sensors ◽  
S Wave ◽  
Single Station ◽  
Potential Applications ◽  
Global Seismology ◽  
Motion Measurements

Over the past few decades, the potential of collocated measurements of 6C data (3C of translational and 3C of rotational motion) has been demonstrated in global seismology using high-sensitivity, observatory-based ring laser technology. Proposed applications of 6C seismology range from tomographic reconstruction of near-receiver structure to the reduction of nonuniqueness in seismic source inverse problems. Applications to exploration problems have so far been hampered by the lack of appropriate sensors, but several applications have been proposed and demonstrated with array-derived rotational motion estimates. With the recent availability of, for example, fiber-optic-based high-sensitivity rotational motion sensors, widespread applications of 6C techniques to exploration problems are in sight. Potential applications are based on, for example, the fact that the extended set of combined translational and rotational motion observations enables carrying out array-type processing with single-station recordings such as wavefield separation and surface-wave suppression. Furthermore, measuring the rotational component (curl) of the seismic wavefield enables direct isolation of the S-wave constituents and could significantly improve S-wave exploration. Rotational measurements provide estimates of the spatial wavefield gradient at the free surface that allow carrying out analyses such as local slowness estimation and wavefield reconstruction. Furthermore, rotational motion measurements can help to resolve wavefield infidelity introduced by seismic instruments that are not well-coupled to the ground.

scholarly journals Precession Azimuth Sensing with Low-Noise Molecular Electronics Angular Sensors

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Dmitry L. Zaitsev ◽  
Vadim M. Agafonov ◽  
Egor V. Egorov ◽  
Alexander N. Antonov ◽  
Vladimir G. Krishtop
Keyword(s):  
Molecular Electronics ◽  
Low Cost ◽  
Rotational Velocity ◽  
High Sensitivity ◽  
Low Noise ◽  
Motion Sensors ◽  
Noise Performance ◽  
Rotating Platform ◽  
Vector Projection ◽  
Signal Processing Algorithms

This paper describes the use of MET-based low-noise angular motion sensors to precisely determine azimuth direction in a dynamic-scheme method of measuring the Earth’s rotational velocity vector. The scheme includes sensor installation on a rotating platform so that it could scan the space and seek for the position of the highest Earth’s rotation vector projection on its axis. This method is very efficient provided a low-noise sensor is used. A low-cost angular sensor based on MET (molecular electronic transduction) technology has been used. The sensors of this kind were originally developed for seismic activity monitoring and are well known for very good noise performance and high sensitivity. This approach, combined with the use of special signal processing algorithms, allowed reaching the accuracy of 0.2°, while the measurement time was less than 100 seconds.

scholarly journals High-sensitivity tunneling magneto-resistive micro-gyroscope with immunity to external magnetic interference

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Li Jin ◽  
Shi-Yang Qin ◽  
Rui Zhang ◽  
Meng-Wei Li
Keyword(s):  
Bridge Circuit ◽  
High Sensitivity ◽  
Micro Electro Mechanical System ◽  
Detection Sensitivity ◽  
Force Detection ◽  
Mems Gyroscope ◽  
Mems Gyroscopes ◽  
Potential Applications ◽  
Magneto Resistance ◽  
Total Sensitivity

Abstract Micro-electro-mechanical system (MEMS) gyroscopes have numerous potential applications including guidance, robotics, tactical-grade navigation, and automotive applications fields. The methods with ability of the weak Coriolis force detection are critical for MEMS gyroscopes. In this paper, we presented a design of MEMS gyroscope based on the tunneling magneto-resistance effect with higher detection sensitivity. Of all these designed parameters, the structural, magnetic field, and magneto-resistance sensitivity values reach to 21.6 nm/°/s, 0.0023 Oe/nm, and 29.5 mV/Oe, thus, with total sensitivity of 1.47 mV/°/s. Multi-bridge circuit method is employed to suppress external magnetic interference and avoid the integration error of the TMR devices effectively. The proposed tunneling magneto-resistive micro-gyroscope shows a possibility to make an inertial grade MEMS gyroscope in the future.

scholarly journals Photoacoustic reporter genes for noninvasive molecular imaging and theranostics

2020 ◽  
Vol 13 (03) ◽  
pp. 2030005
Author(s):  
Zhao Lei ◽  
Yun Zeng ◽  
Xiaofen Zhang ◽  
Xiaoyong Wang ◽  
Gang Liu
Keyword(s):  
Molecular Imaging ◽  
Fluorescent Proteins ◽  
Photoacoustic Imaging ◽  
High Sensitivity ◽  
Reporter Genes ◽  
Biological Processes ◽  
Deep Tissue ◽  
Potential Applications ◽  
Improved Performance

Noninvasive molecular imaging makes the observation and comprehensive understanding of complex biological processes possible. Photoacoustic imaging (PAI) is a fast evolving hybrid imaging technology enabling in vivo imaging with high sensitivity and spatial resolution in deep tissue. Among the various probes developed for PAI, genetically encoded reporters attracted increasing attention of researchers, which provide improved performance by acquiring images of a PAI reporter gene’s expression driven by disease-specific enhancers/promoters. Here, we present a brief overview of recent studies about the existing photoacoustic reporter genes (RGs) for noninvasive molecular imaging, such as the pigment enzyme reporters, fluorescent proteins and chromoproteins, photoswitchable proteins, including their properties and potential applications in theranostics. Furthermore, the challenges that PAI RGs face when applied to the clinical studies are also examined.

Bio-Sensing Textile for Medical Monitoring Applications

2008 ◽  
Vol 57 ◽  
pp. 257-265 ◽  
Author(s):  
Jean Luprano
Keyword(s):  
Health Management ◽  
Health And Safety ◽  
High Sensitivity ◽  
Body Fluids ◽  
Sensor Calibration ◽  
Medical Monitoring ◽  
Healthcare Applications ◽  
Safety Issues ◽  
Important Health ◽  
Potential Applications

The commercial systems using intelligent textiles that start to appear on the market perform physiological measurements such as body temperature, electrocardiogram, respiration rate, etc. and target sport and healthcare applications. Biochemical measurements of body fluids combined with available health monitoring technology will extend these systems by addressing important health and safety issues. BIOTEX, standing for Bio-sensing Textile for Health Management, is a European project, which aims at developing dedicated biochemical sensing techniques that can be integrated into textiles. Such a system would be a major breakthrough for personalized healthcare and would allow for the first time the monitoring of body fluids with sensors distributed in a textile substrate. The potential applications include isolated people, convalescents and patients with chronic diseases, sports performance assessment and training. The project is addressing several challenges, among which: sweat collection and delivery to the sensors, high sensitivity with a wearable system, wearability issues, sensor calibration and lack of research in sweat analysis.

Inversion of reflection traveltimes for transverse isotropy

Geophysics ◽  
1995 ◽  
Vol 60 (4) ◽  
pp. 1095-1107 ◽  
Author(s):  
Ilya Tsvankin ◽  
Leon Thomsen
Keyword(s):  
Wave Velocity ◽  
Vertical Velocity ◽  
Joint Inversion ◽  
Transverse Isotropy ◽  
Taylor Series Expansion ◽  
High Sensitivity ◽  
Transversely Isotropic ◽  
P Wave ◽  
S Wave ◽  
Quartic Term

In anisotropic media, the short‐spread stacking velocity is generally different from the root‐mean‐square vertical velocity. The influence of anisotropy makes it impossible to recover the vertical velocity (or the reflector depth) using hyperbolic moveout analysis on short‐spread, common‐midpoint (CMP) gathers, even if both P‐ and S‐waves are recorded. Hence, we examine the feasibility of inverting long‐spread (nonhyperbolic) reflection moveouts for parameters of transversely isotropic media with a vertical symmetry axis. One possible solution is to recover the quartic term of the Taylor series expansion for [Formula: see text] curves for P‐ and SV‐waves, and to use it to determine the anisotropy. However, this procedure turns out to be unstable because of the ambiguity in the joint inversion of intermediate‐spread (i.e., spreads of about 1.5 times the reflector depth) P and SV moveouts. The nonuniqueness cannot be overcome by using long spreads (twice as large as the reflector depth) if only P‐wave data are included. A general analysis of the P‐wave inverse problem proves the existence of a broad set of models with different vertical velocities, all of which provide a satisfactory fit to the exact traveltimes. This strong ambiguity is explained by a trade‐off between vertical velocity and the parameters of anisotropy on gathers with a limited angle coverage. The accuracy of the inversion procedure may be significantly increased by combining both long‐spread P and SV moveouts. The high sensitivity of the long‐spread SV moveout to the reflector depth permits a less ambiguous inversion. In some cases, the SV moveout alone may be used to recover the vertical S‐wave velocity, and hence the depth. Success of this inversion depends on the spreadlength and degree of SV‐wave velocity anisotropy, as well as on the constraints on the P‐wave vertical velocity.

scholarly journals An Electrochemical Sensor Based on a Nitrogen-Doped Carbon Material and PEI Composites for Sensitive Detection of 4-Nitrophenol

Nanomaterials ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 86
Author(s):  
Xue Nie ◽  
Peihong Deng ◽  
Haiyan Wang ◽  
Yougen Tang
Keyword(s):  
Electrochemical Sensor ◽  
Signal To Noise Ratio ◽  
High Sensitivity ◽  
Environmental Water ◽  
Fast Response ◽  
Nitrogen Doped ◽  
Potential Applications ◽  
Good Repeatability ◽  
Nitrogen Doped Carbon ◽  
Optimized Conditions

A glassy carbon electrode (GCE) was modified with nitrogen-doped carbon materials (NC) and polyethyleneimine (PEI) composites to design an electrochemical sensor for detecting 4-nitrophenol (4-NP). The NC materials were prepared by a simple and economical method through the condensation and carbonization of formamide. The NC materials were dispersed in a polyethyleneimine (PEI) solution easily. Due to the excellent properties of NC and PEI as well as their synergistic effect, the electrochemical reduction of the 4-NP on the surface of the NC–PEI composite modified electrode was effectively enhanced. Under the optimized conditions, at 0.06–10 μM and 10–100 μM concentration ranges, the NC–PEI/GCE sensor shows a linear response to 4-NP, and the detection limit is 0.01 μM (the signal-to-noise ratio is three). The reliability of the sensor for the detection of 4-NP in environmental water samples was successfully evaluated. In addition, the sensor has many advantages, including simple preparation, fast response, high sensitivity and good repeatability. It may be helpful for potential applications in detecting other targets.

scholarly journals Sensing Enhancement of Electromagnetically Induced Transparency Effect in Terahertz Metamaterial by Substrate Etching

2021 ◽  
Vol 9 ◽  
Author(s):  
Tingling Lin ◽  
Yi Huang ◽  
Shuncong Zhong ◽  
Manting Luo ◽  
Yujie Zhong ◽  
...  
Keyword(s):  
Electric Field ◽  
Electromagnetically Induced Transparency ◽  
High Sensitivity ◽  
Strong Light ◽  
Refractive Index Sensing ◽  
Quadrupole Resonance ◽  
Matter Interaction ◽  
Potential Applications ◽  
Light Matter Interaction ◽  
Induced Transparency

A broad range of terahertz (THz) metamaterials have been developed for refractive index sensing. However, most of these metamaterials barely make sufficient use of the excited electric field which is crucial to achieve high sensitivity. Here, we proposed a metamaterial sensor possessing electromagnetically induced transparency (EIT) resonance that is formed by the interference of dipole and quadrupole resonance. In particular, the strengthening of light-matter interaction is realized through substrate etching, leading to a remarkable improvement in sensitivity. Hence, three kinds of etching mode were presented to maximize the utilization of the electric field, and the corresponding highest sensitivity is enhanced by up to ~2.2-fold, from 0.260 to 0.826 THz/RIU. The proposed idea to etch substrate with a strong light-matter interaction can be extended to other metamaterial sensors and possesses potential applications in integrating metamaterial and microfluid for biosensing.

scholarly journals Inversion of the reflected SV-wave for density and S-wave velocity structures

2020 ◽  
Vol 221 (3) ◽  
pp. 1635-1639
Author(s):  
Feng Zhang ◽  
Xiang-yang Li
Keyword(s):  
Wave Velocity ◽  
Incident Angle ◽  
Seismic Exploration ◽  
S Wave ◽  
Geological Interpretation ◽  
Data Application ◽  
Essential Properties ◽  
Global Seismology ◽  
Ill Posed ◽  
Formation And Evolution

SUMMARY Density is one of the most essential properties that determines the dynamic behavior of the Earth. Besides, density has been commonly used to investigate the mineral composition, porosity and fluid content of rock. Therefore, a reliable estimation of the density structure is one of the most important objectives in both global seismology and seismic exploration. However, seismic inversions of independent density estimates are ill-posed because density has a large trade-off with velocities. Shear wave propagation is sensitive to both density and the S-wave velocity. We show that the reflected SV-wave (SV-to-SV wave) at an incident angle of 22.5o depends only on density contrast, and at incident angle 30o it depends only on S-wave velocity contrast. Thus, density as well as S-wave velocity can be directly inverted from the reflected SV-wave as separate and independent parameters. The forward modelling has high accuracy, the inverse problem is well-posed and the misfit function can be easily regularized. Field data application demonstrates the proposed method can efficiently recover reliable and high-resolution density and S-wave velocity of fine sturctures. Thus, this method has great potential in geological interpretation including understanding regional Moho structure, crustal and mantle formation and evolution, and rock lithologic composition and fluid-filled porosity.

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