Correct Mode Research Articles

Linking strike directions to invariant TE and TM impedances of the magnetotelluric impedance tensor

Estimation of the traditional transverse electric (TE) and transverse magnetic (TM) impedances of the magnetotelluric tensor for two-dimensional structures can be decoupled from the estimation of the strike direction with significant implications when dealing with galvanic distortions. Distortion-free data are obtainable by combining a quadratic equation with the phase tensor. In the terminology of Groom–Bailey, the quadratic equation provides amplitudes and phases that are immune to twist, and the phase tensor provides phases immune to both, twist and shear. On the other hand, distortion-free strike directions can be obtained using Bahr's approach or the phase tensor. In principle, this is all that is needed to proceed to a two-dimensional (2D) interpretation. However, the resulting impedances are strike ignorant because they are invariant under coordinate system rotation, and if they are to be related to a geological strike, they must be linked to a particular direction. This is an additional ambiguity to the one of 90° arising in classic strike-determination methods, which must be resolved independently. In this work, we use the distortion model of Groom–Bailey to resolve the ambiguity by bringing back the coupling between impedances and strike in the presence of galvanic distortions. Our approach is a hybrid between existing numerical and analytical methods that reduces the problem to a binary decision, which involves associating the invariant impedances with the correct TE and TM modes. To determine the appropriate association, we present three algorithms. Two of them require optimizing the fit to the data, and the third one requires a comparison of phases. All three keep track of possible crossings of the phase curves providing a clear-cut solution. Synthetic and field data illustrate the performance of the three schemes.Graphical

CryoSat-2 Significant Wave Height in Polar Oceans Derived Using a Semi-Analytical Model of Synthetic Aperture Radar 2011–2019

This paper documents the retrieval of significant ocean surface wave heights in the Arctic Ocean from CryoSat-2 data. We use a semi-analytical model for an idealised synthetic aperture satellite radar or pulse-limited radar altimeter echo power. We develop a processing methodology that specifically considers both the Synthetic Aperture and Pulse Limited modes of the radar that change close to the sea ice edge within the Arctic Ocean. All CryoSat-2 echoes to date were matched by our idealised echo revealing wave heights over the period 2011–2019. Our retrieved data were contrasted to existing processing of CryoSat-2 data and wave model data, showing the improved fidelity and accuracy of the semi-analytical echo power model and the newly developed processing methods. We contrasted our data to in situ wave buoy measurements, showing improved data retrievals in seasonal sea ice covered seas. We have shown the importance of directly considering the correct satellite mode of operation in the Arctic Ocean where SAR is the dominant operating mode. Our new data are of specific use for wave model validation close to the sea ice edge and is available at the link in the data availability statement.

Statement of the problem of assessing instability of passive quantum frequency standards in the presence of an error from the interaction

Construction of modern measuring complexes of the coordinate-time support system of Ukraine is impossible without improving mathematical models of quantum standards of frequency (QSF) used in group standards. This work is devoted to the analysis of methods for the stable solution of direct and inverse problems (methods for solving ill-posed problems) in models of the interaction of passive QSF in the process of their comparisons. The priority task is to use these methods for the numerical solution of problems in the design of group QSF and parallel quantum generators of random numbers. Methods for solving such problems are in demand, since they make it possible to create mathematical models of group QSF interaction. These models will enable the design of efficient parallel quantum random number generation devices for high-tech areas of cybersecurity.
 Varieties of methods such as the method of least squares or the method of the Moore-Penrose pseudo-inverse matrix are used, as a rule when evaluating the metrological parameters of QSF.Robust methods of regularization or filtering, for example, the Kalman or Wiener filter method, are used in the algorithms of group standards, due to the instability of the solution.However, these methods do not work in the presence of an error from the interaction of QSF in the process of their functioning in a group standard or in comparisons.
 The aim of this work is to analyze and substantiate the formulation of the problem of assessing the potential accuracy characteristics of passive QSF in the presence of an error from the interaction. Regularization parameters when determining the state vector of the group standard are found using signals transmitted by global navigation satellite systems such as GPS\GLONASS in the local differential correction mode.

Comment on ‘Piezoelectricity as a mechanism on generation of electromagnetic precursors before earthquakes’ by J.H. Wang

SUMMARY Wang (2021, hereafter JHW) recently investigated elastic–electric coupling (EEC) in terms of the piezoelectric effect to assess both the plausibility of and necessary conditions for generating pre-earthquake electromagnetic phenomena, including variations in the total electron content (TEC). The study considered a 1-D model to simulate the piezoelectric effect, and derived a quantitative relationship between the dislocation and intensity of the electric field. One of JHW's conclusions was that the piezoelectric effect is a potential mechanism for generating previously reported pre-earthquake TEC anomalies. However, the quantitative discussion in JHW contains a serious error. JHW had chosen an incorrect mode between the two solutions during the derivation of a quantitative relationship between the displacement and the electric field, which subsequently led to an incorrect estimation of the ratio of the generated electric field to the displacement. The opposite conclusion to that drawn by JHW is attained when a correct mode is used.

The derivative expansion in asymptotically safe quantum gravity: general setup and quartic order

We present a general framework to systematically study the derivative expansion of asymptotically safe quantum gravity. It is based on an exact decoupling and cancellation of different modes in the Landau limit, and implements a correct mode count as well as a regularisation based on geometrical considerations. It is applicable independent of the truncation order. To illustrate the power of the framework, we discuss the quartic order of the derivative expansion and its fixed point structure as well as physical implications.

Trifluoromethylated Flavonoid-Based Isoxazoles as Antidiabetic and Anti-Obesity Agents: Synthesis, In Vitro α-Amylase Inhibitory Activity, Molecular Docking and Structure-Activity Relationship Analysis.

Diabetes mellitus is a major health problem globally. The management of carbohydrate digestion provides an alternative treatment. Flavonoids constitute the largest group of polyphenolic compounds, produced by plants widely consumed as food and/or used for therapeutic purposes. As such, isoxazoles have attracted the attention of medicinal chemists by dint of their considerable bioactivity. Thus, the main goal of this work was to discover new hybrid molecules with properties of both flavonoids and isoxazoles in order to control carbohydrate digestion. Moreover, the trifluoromethyl group is a key entity in drug development, due to its strong lipophilicity and metabolic stability. Therefore, the present work describes the condensation of a previously synthesized trifluoromethylated flavonol with different aryl nitrile oxides, affording 13 hybrid molecules indicated as trifluoromethylated flavonoid-based isoxazoles. The structures of the obtained compounds were deduced from by 1H NMR, 13C NMR, and HRMS analysis. The 15 newly synthesized compounds inhibited the activity of α-amylase with an efficacy ranging from 64.5 ± 0.7% to 94.7 ± 1.2% at a concentration of 50 μM, and with IC50 values of 12.6 ± 0.2 μM–27.6 ± 1.1 μM. The most effective compounds in terms of efficacy and potency were 3b, 3h, 3j, and 3m. Among the new trifluoromethylated flavonoid-based isoxazoles, the compound 3b was the most effective inhibitor of α-amylase activity (PI = 94.7 ± 1.2% at 50 μM), with a potency (IC50 = 12.6 ± 0.2 μM) similar to that of the positive control acarbose (IC50 = 12.4 ± 0.1 μM). The study of the structure–activity relationship based on the molecular docking analysis showed a low binding energy, a correct mode of interaction in the active pocket of the target enzyme, and an ability to interact with the key residues of glycosidic cleavage (GLU-230 and ASP-206), explaining the inhibitory effects of α-amylase established by several derivatives.

Surgical correction of pediatric spinal deformities with coexisting intraspinal pathology: A case report and literature review.

Background: Surgical correction of spinal deformities with coexisting intraspinal pathology (SDCIP) requires special consideration to minimize risks of further injury to an already abnormal spinal cord. However, there is a paucity of literature on this topic. Here, the authors present a pediatric patient with a residual pilocytic astrocytoma and syringomyelia who underwent surgical correction of progressive postlaminectomy kyphoscoliosis. Techniques employed are compared to those in the literature to compile a set of guidelines for surgical correction of SDCIP.Methods: A systematic MEDLINE search was conducted using the following keywords; “pediatric,” “spinal tumor resection,” “deformity correction,” “postlaminectomy,” “scoliosis correction,” “intraspinal pathology,” “tethered cord,” “syringomyelia,” or “diastematomyelia.” Recommendations for surgical technique for pediatric SDCIP correction were reviewed.Results: The presented case demonstrates recommendations that primarily compressive forces on the convexity of the coronal curve should be used when performing in situ correction of SDCIP. Undercorrection is favored to minimize risks of traction on the abnormal spinal cord. The literature yielded 13 articles describing various intraoperative techniques. Notably, seven articles described use of compressive forces on the convex side of the deformity as the primary mode of correction, while only five articles provided recommendations on how to safely and effectively surgically correct SDCIP.Conclusion: The authors demonstrated with their case analysis and literature review that there are no clear current guidelines regarding the safe and effective techniques for in situ correction and fusion for the management of pediatric SDCIP.

Multi-centre cross-sectional study on vascular remodelling in children following successful coarctation correction.

Coarctation of the aorta is an arteriopathy with life-long sequelae, with remarkably increased cardiovascular events in young adults even after successful repair and despite blood pressure status. There are data on arterial remodelling in adults after coarctation correction, however, these data are scarce in childhood. Thus, the aim of this cross-sectional study was to evaluate changes in arterial wall function and morphology in children following successful coarctation repair and to compare these changes among patients with different blood pressure status and coarctation correction modes. Blood pressure status, echocardiographic parameters, arterial wall structure and stiffness, endothelial function and central blood pressure measurements were evaluated in 110 children aged 6-18 years following successful coarctation repair with right arm blood pressure not exceeding leg blood pressure by ≥20 mmHg. The prevalence of arterial hypertension was 50%. The mean carotid intima-media thickness SDS was 3.1 ± 1.5 and above 1.65 SDS in 91 of 110 patients. Increased right carotid intima-media thickness was associated with left ventricular hypertrophy, office blood pressure difference between leg and right arm, recoarctation in the past and interventional coarctation correction. Increased local common carotid artery stiffness was associated with increased pulse pressure and central systolic blood pressure. Potentially decreased endothelial function was related to a slight increase of peak and mean systolic gradient in the descending aorta. After successful coarctation repair and with a low blood pressure gradient, children still have a high prevalence of arterial hypertension and significant arterial remodelling, indicating accelerated biological age and advanced arteriosclerosis.

Signal-to-noise ratio with adaptive optics compensation in non-Kolmogorov weak turbulent atmosphere

This study investigates the average signal-to-noise ratio ⟨ SNR ⟩ at the shot-noise limited receiver of an optical wireless communication system (OWC) that uses collimated Gaussian beam with adaptive optics correction in non-Kolmogorov weak turbulent atmosphere. ⟨ SNR ⟩ and the variation in the percentage ⟨ SNR ⟩ are calculated and the results are presented against various adaptive optics correction modes, non-Kolmogorov power-law exponent, receiver aperture size, Gaussian beam source size, photodetector quantum efficiency, electronic bandwidth, link length, and turbulence strength. Adaptive optics correction is analyzed for tilt, defocus, astigmatism, coma and trefoil modes and their variations. The effects of adaptive optics compensation are examined that cause an increase in SNR, hence improve the performance of an OWC system using collimated Gaussian beam and operating in the non-Kolmogorov weak turbulent atmosphere.

Fabrication and characterisation of piezoelectric thick-film microcantilever deposited on stainless steel using electrohydrodynamic jet deposition

This paper presents a lead zirconate titanate (PZT) thick-film microcantilever fabricated on a stainless-steel substrate using electrohydrodynamic jet (E-jet) deposition. PZT thick-film functional layer arrays were produced directly on stainless-steel substrates via E-jet deposition to form microcantilevers with a width of only 150 μm and thickness of 62 μm. The method can realise batch manufacturing of microscale cantilevers, improve the PZT active layer energy and microcantilever fracture toughness under vibrational deformation, and eliminate the need for complex photolithography and etching processes. The microcantilever accurately realised the correct mode shapes, consistent with simulation results. The vibrational amplitude of the microcantilever reached 5.14 μm, while Qm was up to 688.1, considerably larger than those of thick-film silicon-based microcantilevers and free-standing microcantilevers with similar sizes. An effective electromechanical coupling coefficient, Keff, of approximately 0.13 was obtained. The potential for efficient applications in microelectromechanical system piezoelectric devices was confirmed.

Optimizing Antimicrobial Drug Dosing in Critically Ill Patients.

A fundamental step in the successful management of sepsis and septic shock is early empiric antimicrobial therapy. However, for this to be effective, several decisions must be addressed simultaneously: (1) antimicrobial choices should be adequate, covering the most probable pathogens; (2) they should be administered in the appropriate dose, (3) by the correct route, and (4) using the correct mode of administration to achieve successful concentration at the infection site. In critically ill patients, antimicrobial dosing is a common challenge and a frequent source of errors, since these patients present deranged pharmacokinetics, namely increased volume of distribution and altered drug clearance, which either increased or decreased. Moreover, the clinical condition of these patients changes markedly over time, either improving or deteriorating. The consequent impact on drug pharmacokinetics further complicates the selection of correct drug schedules and dosing during the course of therapy. In recent years, the knowledge of pharmacokinetics and pharmacodynamics, drug dosing, therapeutic drug monitoring, and antimicrobial resistance in the critically ill patients has greatly improved, fostering strategies to optimize therapeutic efficacy and to reduce toxicity and adverse events. Nonetheless, delivering adequate and appropriate antimicrobial therapy is still a challenge, since pathogen resistance continues to rise, and new therapeutic agents remain scarce. We aim to review the available literature to assess the challenges, impact, and tools to optimize individualization of antimicrobial dosing to maximize exposure and effectiveness in critically ill patients.

Benchmarking the Ability of Common Docking Programs to Correctly Reproduce and Score Binding Modes in SARS-CoV-2 Protease Mpro.

The coronavirus SARS-CoV-2 main protease, Mpro, is conserved among coronaviruses with no human homolog and has therefore attracted significant attention as an enzyme drug target for COVID-19. The number of studies targeting Mpro for in silico screening has grown rapidly, and it would be of great interest to know in advance how well docking methods can reproduce the correct ligand binding modes and rank these correctly. Clearly, current attempts at designing drugs targeting Mpro with the aid of computational docking would benefit from a priori knowledge of the ability of docking programs to predict correct binding modes and score these correctly. In the current work, we tested the ability of several leading docking programs, namely, Glide, DOCK, AutoDock, AutoDock Vina, FRED, and EnzyDock, to correctly identify and score the binding mode of Mpro ligands in 193 crystal structures. None of the codes were able to correctly identify the crystal structure binding mode (lowest energy pose with root-mean-square deviation < 2 Å) in more than 26% of the cases for noncovalently bound ligands (Glide: top performer), whereas for covalently bound ligands the top score was 45% (EnzyDock). These results suggest that one should perform in silico campaigns of Mpro with care and that more comprehensive strategies including ligand free energy perturbation might be necessary in conjunction with virtual screening and docking.

A fluid–structure interaction model for free-surface flows and flexible structures using smoothed particle hydrodynamics on a GPU

This paper presents the development of a numerical model for violent hydrodynamics of free-surface flows interacting with flexible structures using the meshless smoothed particle hydrodynamics (SPH) method accelerated with a graphics processing unit (GPU). The present work implements a unified SPH framework to solve both the fluid and structural dynamics within the open-source SPH code DualSPHysics. Well-known deficiencies with SPH-based structural modelling (linear inconsistency, tensile instability and rank deficiency) are addressed by adopting a Total Lagrangian formulation with kernel correction and zero-energy mode suppression. The fluid–structure coupling is handled via manipulation of the existing boundary condition within DualSPHysics, which does not require any geometrical knowledge of the interface. This, together with the unified SPH framework, permits straightforward implementation within DualSPHysics and retains its parallel scalability on hardware acceleration platforms, in particular on GPUs. An extensive validation and profiling of the proposed model is carried out for a range of challenging 2-D and 3-D test cases incorporating violent free-surface flows, nonlinear structural dynamics and complex fluid–structure interactions, and its performance is characterised and quantified. The analysis shows good agreement between the proposed model and analytical/benchmark solutions from the literature. Furthermore, the GPU profiling shows speedups on a single GPU of up to 40, compared to an optimised 12-core (24 threads) central processing unit (CPU) version. These findings indicate the proposed model is a viable and efficient approach to simulating violent free-surface fluid–structure interactions.

Ensemble Oscillation Correction (EnOC): Leveraging oscillatory modes to improve forecasts of chaotic systems

AbstractOscillatory modes of the climate system are among its most predictable features, especially at intraseasonal time scales. These oscillations can be predicted well with data-driven methods, often with better skill than dynamical models. However, since the oscillations only represent a portion of the total variance, a method for beneficially combining oscillation forecasts with dynamical forecasts of the full system was not previously known. We introduce Ensemble Oscillation Correction (EnOC), a general method to correct oscillatory modes in ensemble forecasts from dynamical models. We compute the ensemble mean—or the ensemble probability distribution—with only the best ensemble members, as determined by their discrepancy from a data-driven forecast of the oscillatory modes. We also present an alternate method which uses ensemble data assimilation to combine the oscillation forecasts with an ensemble of dynamical forecasts of the system (EnOCDA). The oscillatory modes are extracted with a time-series analysis method called multi-channel singular spectrum analysis (M-SSA), and forecast using an analog method. We test these two methods using chaotic toy models with significant oscillatory components, and show that they robustly reduce error compared to the uncorrected ensemble. We discuss the applications of this method to improve prediction of monsoons as well as other parts of the climate system.

Anisotropic damage model for concrete and other quasi-brittle materials

A thermodynamically consistent formulation to model anisotropic damage for quasi-brittle materials is proposed. The model is based on proper expressions for the specific Gibbs free energy and the complementary form of the dissipation potential. Damaging of the material is described by a symmetric positive definite second order damage tensor. Especially, the failure surface is formulated in such a way that it will mimic the behaviour of the well known Ottosen’s four parameter failure surface. While testing the model against the experimental results found in literature, the results were in good agreement in uniaxial tensile and compressive loadings as well as in biaxial compression. Besides the correct failure stress states, the model predicts the correct failure modes of concrete: axial splitting along the direction of uniaxial compression and tensile damaging normal to the direction of tension.

Prediction of landslide displacement with step-like curve using variational mode decomposition and periodic neural network

Landslide deformation characterized with step-like curves often presents periodicity implicitly. This paper proposed a novel data-driven approach that adopted periodic neural network (PNN) and variational mode decomposition (VMD) to conduct displacement prediction based on the intrinsic seasonality of step-like landslide displacement. PNN was a novel neural network designed for capturing the seasonality of the time series. Firstly, the initial displacement would be decomposed into trend component, periodic component, and random component using the variational mode decomposition (VMD). Then, the external triggering factors were also decomposed by VMD into several subsequences. Subsequences with periodic and random characteristics were selected as the input datasets to forecast the periodic and random components by PNN. Finally, the total displacement was obtained by superimposing the three predictive components to validate the model performance. The Baishuihe landslide was taken as a case study to validate the high effectiveness and efficiency of our method. The result proved that our new model presented satisfactory prediction accuracy without complex training process. Meanwhile, PNN performed a strong robustness to the missing values due to the advantage of its structure. In addition, we clarified a corrective data processing mode as “strict” mode: the dataset has to be divided into training and validation sets firstly to avoid the leakage of the future data.

SEPIC converter of Automatic Power Factor Correction by improved traditional linear control

With increasing using of nonlinear electronic equipment at a wide range, total harmonics distortion (THD) in the line current has grown to be a considerable problem. The methods that include reducing harmonics in line current and power factor correction are required. Therefore, the essential target of this proposed work is to reduce the harmonics produced in the line current and improve the power quality of the load by the output voltage regulation and power factor correction (PFC). This paper presents a Single-Ended Primary Inductance Converter (SEPIC) at Discontinuous Conduction Mode (DCM) for automatic power factor Correction (APFC). The SEPIC converter is modeling by utilizing Current Injected Equivalent Circuit Approach (CIECA). The control system is applied by traditional linear control (TLC). The TLC has been modified by an optimization algorithm (OA) and adds an (inner or current). The proposed design of SEPIC-PFC is implemented by MATLAB and Simulink. According to the simulated dynamic behavior results, a unity power factor and 15% of total harmonics distortion (THD) reduction have been obtained comparing with previous work. Besides, a regulated DC output voltage has been achieved. The proposed control system has a low overshoot, small settling time, and steady-state error close to zero

Design of an auto adaption unit for reconfigurable analog to digital converters

This paper shows an auto adaption unit for reconfigurable ADC that is designed for low power operation with the transistor being operated in weak inversion region. The presented adaptation unit separates high frequency bio-signals from low frequency bio-signals and configures the ADC in the correct mode of operation. The adaptive mechanism provides technological flexibility in order to reconfigure the analog to digital converter (ADC) resolution and sampling rate regardless of the direction of the converter. It produces control bits toconfigure the ADC, based on the frequency and amplitude of the input signal. The reconfigurable ADC along with a auto adaptation circuitis designed for bio-mpedance monitoring systems. The paper consists of pre-amplifier and utilized models of FVC and Schmitt trigger concepts to design auto adaptation unit. The adaption unit consumes 89 $$\upmu$$ W with a supply voltage of 0.8 V. Simulation results found the frequency of input signals 1 to 10 MHz for the 10 KHz input signal, the DC voltage produced by the frequency-to-voltage converter is − 691 mV.The entire circuitry is designed, simulated and analyzed by using Cadence EDA tool with 18nm Fin-FET technology.

Beam finite element for thin-walled box girders considering shear lag and shear deformation effects

In this paper, a new formulation of beam finite element (B3S) is developed for predicting the performance of shear lag and shear deformation effects in thin-walled single- and multi-cell box girders. The longitudinal warping displacement of each wall of the cross-section is defined as the sum of five deformation modes, i.e., shear lag warping displacement mode, initial shear deformation mode, bending mode, axial mode, and correction mode. Based on the Minimum Potential Energy (MPE) principle with independent descriptions of the displacement fields, the governing differential equations in terms of two generalized displacements, normalized shear lag warping function U(x) and vertical displacement w(x), can be obtained. The proposed beam finite element is refined by selecting closed-form homogeneous solutions of the differential equations as interpolation functions. Besides the nodal Degree Of Freedoms (DOFs) of the conventional beam finite element, the normalized shear lag warping function has been considered as an additional DOF in each node at the element ends to account for the shear lag effect. Moreover, for comparison reasons, the one-dimensional beam finite elements developed based on the Euler-Bernoulli Beam Theory (EBT) and Timoshenko Beam Theory (TBT) have been also introduced. Numerical examples are presented regarding single- or multi-cell box girders with constant or variable depth and the results obtained are compared with those retrieved from the pioneering work or calculated by using solid finite-element models to validate the proposed beam finite element and to demonstrate the wide range of applicability and convenience of using it.

Effects of anisotropy on absorption cross-section spectra of medium-sized spheroidal corundum particles

Context. It has been widely accepted that corundum particles condense in the atmospheres of oxygen-rich asymptotic giant branch stars and effectively produce an infrared emission feature at 13 μm. Laboratory experiments have predicted that these particles have the shape of oblate spheroids. Aims. We investigate the influence of the material anisotropy of uniaxial corundum on absorption cross section spectra of medium sized spheroidal particles in the infrared spectral region. Methods. We compared absorption cross-section spectra of the anisotropic corundum particles gained by finite-difference time-domain simulations to spectra calculated by a weighted sum approximation of the according fictive isotropic materials, with one material having the dielectric function of the a–b-plane and the other having the dielectric function of the c-axis of corundum. We carried out investigations for different axes ratios of the spheroids, particles volumes, and different geometries of the dielectric axes to the particle axes as well as to the polarization and propagation direction of the incident light. Results. We observed several effects attributed to anisotropy that are non-additive, so that they cannot be reproduced with the combined spectra of the isotropic materials. Conclusions. Care should be taken when calculating the corundum infrared spectrum with simpler approaches. When particle sizes above 1 μm are to be considered, the T-matrix formalism delivers correct band shifts and bulk modes for many, but not all bands. This remains true in orientation-averaged spectra and for particles in the 0.1 μm size range.