Distortion Effects Research Articles

Simultaneous geometric calibration and orbit-attitude determination of Hayabusa2’s deployable camera (DCAM3)

Hayabusa2’s deployable camera (DCAM3) was deployed from the spacecraft near the asteroid Ryugu to successfully monitor the artificial cratering experiment. Scientific analyses of the observed impact ejecta require accurate determination of the camera’s position and orientation. However, in contrast to conventional spacecraft operations, DCAM3 lacked the capability to acquire orbit tracking data and attitude sensor data due to its limited onboard resources. Even though the optical images obtained by DCAM3 itself are the only source of geometric information, they were subject to significant distortion caused by the rolling shutter effect and lens distortion. This research is, therefore, designed to simultaneously estimate the image distortion and the orbital and attitude motions of DCAM3, relying solely on its image data. The relative geometry between the camera and the asteroid is reconstructed from the geographic information of the observed feature points by incorporating distortion effects. The proposed method involves segmenting the geometry reconstruction, with more than ten thousand feature measurements, into smaller-scale least-squares problems. The image-based estimation yields consistent distortion, orbit, and attitude solutions with pixel-scale accuracy. The analysis results indicate that DCAM3 experienced significant nutation of its optical axis during ballistic flight in a semi-elliptical orbit. In addition, these motions were sensitive enough to simultaneously determine system parameters, such as the gravitational parameter of Ryugu and the inertia moment of DCAM3. This paper illustrates the potential of deployable camera systems as a promising option for enhancing the scientific and engineering aspects of asteroid exploration.

Ispitivanje poprečne unutarnje sile sandučastog nosača primjenom principa varijacije energije

This study investigated the transverse internal force of a box girder with a trapezoidal cross-section under eccentric loading. The effects of the box girder distortion and frame shear difference on the transverse internal force were considered. An energy variation method based on the minimum potential energy principle was adopted for transverse internal force analysis of the frames. The variable shear difference of the top slab was considered an unknown quantity, and a fourth-order governing differential equation was established. The transverse bending moment of the frame was obtained by solving for the shear difference. Two examples were used to verify the proposed method and analyse the differences between the transverse internal force results calculated using different methods. The effect of the distribution of the box-girder distorted transverse bending moment on each slab was investigated for various stiffness ratios. The results showed that the transverse internal force of the box girder calculated using the proposed method agreed well with the finite element results, with a maximum error of less than 9.68 %. When the stiffness ratio of the box girder increased, the distribution of the distorted transverse bending moment on the top slab increased, whereas that on the bottom slab decreased.

High-Entropy Engineering in Thermoelectric Materials: A Review

Thermoelectric (TE) materials play a crucial role in converting energy between heat and electricity, essentially for environmentally friendly renewable energy conversion technologies aimed at addressing the global energy crisis. Significant advances in TE performance have been achieved over the past decades in various TE materials through key approaches, such as nanostructuring, band engineering, and high-entropy engineering. Among them, the design of high-entropy materials has recently emerged as a forefront strategy to achieve significantly low thermal conductivity, attributed to severe lattice distortion and microstructure effects, thereby enhancing the materials’ figure of merit (zT). This review reveals the progress of high-entropy TE materials developed in the past decade. It discusses high-entropy-driven structural stabilization to maintain favorable electrical transport properties, achieving low lattice thermal conductivity, and the impact of high entropy on mechanical properties. Furthermore, the review explores the theoretical development of high-entropy TE material and discusses potential strategies for future advancements in this field through interactions among experimental and theoretical studies.

An Omnidirectional Image Super-Resolution Method Based on Enhanced SwinIR

For the significant distortion problem caused by the special projection method of equi-rectangular projection (ERP) images, this paper proposes an omnidirectional image super-resolution algorithm model based on position information transformation, taking SwinIR as the base. By introducing a space position transformation module that supports deformable convolution, the image preprocessing process is optimized to reduce the distortion effects in the polar regions of the ERP image. Meanwhile, by introducing deformable convolution in the deep feature extraction process, the model’s adaptability to local deformations of images is enhanced. Experimental results on publicly available datasets have shown that our method outperforms SwinIR, with an average improvement of over 0.2 dB in WS-PSNR and over 0.030 in WS-SSIM for ×4 pixel upscaling.

Active landslide detection using integrated remote sensing technologies for a wide region and multiple stages: A case study in southwestern China

While significant progress has been achieved in utilizing remote sensing technologies for landslide investigation in China, there remains a notable gap in consolidating information on applicable conditions, application stages, and workflows across various remote sensing methodologies. This paper proposes a comprehensive framework for active landslide detection, incorporating multiple stages and data sources, successfully implemented in a vast region of southwestern China. Furthermore, detailed discussions are provided on the effects of the geometric distortion, land cover type, and various InSAR methods on the accuracy of active landslide identification results. Additionally, the paper delves into the advantages of integrated remote sensing technology in active landslide investigation, encompassing the assessment of current landslide activity status, precise delineation of boundaries, identification of different deformation stages, and determination of damage patterns. Through comprehensive analysis of multisource data, it enhances understanding of the active landslide process, ultimately contributing to the mitigation of casualties and property damage.

Spectroflat: A generic spectrum and flat-field calibration library for spectro-polarimetric data

Flat-fielding spectro-polarimetric data with one spatial and one spectral dimension is inherently difficult as the imprint of the spectral lines needs to be separated from other wavelength-dependent instrumental effect (e.g., fringes or prefilter profiles) and wavelength-independent effects (e.g., dust and sensor response). Current approaches for spectrometers are often based on moving the grating or they depend on optical models and/or on lab calibration data. They are also limited to small spectral regions and are instrument-specific. Approaches that would be suitable for polarimeters have not been reported yet. We present an approach that allows for flat-field calibration data to be to obtained for diffraction-grating-based, long-slit spectrographs combined with temporally modulated polarimetry from high-resolution solar telescopes. This approach is based on nominal flat-fielding procedures performed during the instrument's science operations. We performed a precise and field-dependent correction of the spectrographic distortion effect (resulting in curved spectral lines, typically denoted as a "smile" effect) to ensure the orthogonality of the spectral and spatial dimensions. We identified distortions by tracking the position of multiple spectral lines within the full spectral field of view. From the raw modulated flats, we then removed the solar line imprints and derived separate flat-fields for sensor and slit dust features. Optionally, wavelength calibration and continuum correction can be included in this process. We have created generic Python libraries that can be plugged into existing Python-based data reduction pipelines or used as a standalone calibration tool. We show that for spectrographs covering many spectral lines, a correction of the smile distortion based on optical models alone is not sufficient. Our results demonstrate a suppression of fringes, sensor artifacts, and fixed-pattern imprints in demodulated data by one order of magnitude. For intensity images, the photon noise level can be closely attained after calibration. Our correction works across the full spectral range. The algorithm was tested for different wavelength regimes with emission (EUV range) or absorption (near-UV, VIS, IR range) spectra, on data acquired with ground-based (SST/TRIPPLE-SP, GREGOR/GRIS), balloon-borne (SUNRISE-III/SUSI), and space-based (SolO/SPICE) instruments. The data calibrated with our method offer robust and precise inversion results. We have extended existing spectroscopic flat-field techniques to modern instruments with large imaging sensors covering many spectral lines simultaneously, and with polarimetric capabilities, where methods described so far are not adequate. We believe that our method is applicable as a standard calibration approach for most modern high resolution large-FOV, long-slit spectrographs -- both with and without polarimetric capabilities.

Promotion of Acid-Water Oxidation by Lattice Distortion and Orbital Hybridization Induced by Ionic Dopant in Pyrochlore Y2Ru2O7.

For acid-water oxidation, pyrochloric ruthenates are thought to be extremely effective electrocatalysts. In this work, through partial B-site replacement with larger M2+ cations, the electronic states of Y2Ru2O7 with strong electron correlations are reasonably managed, by which the inherent performance is tremendously promoted. Based on this, the improved Y2Ru1.9Sr0.1O7 electrocatalyst exhibits an outstanding durability and presents a highly inherent mass activity of 1915.1 A gRu-1 (at 1.53 V vs RHE). The enhanced oxygen-evolving reaction (OER) activity by ionic dopant in YRO pyrochlore can be attributed to two aspects, i.e., the lattice distortion induced inhibition of the grain coarsening, which results in a large surface area for YRO-M and increases the OER active sites, and the weakening of electron correlation via broadening of the Ru 4d bandwidths due to the increase of the average radius of B-site ions, which gives rise to an enhancement of conductivity and a strengthened hybridization between Ru 4d and O 2p orbitals and improves the reaction kinetics. The synergistic effects of lattice distortion and orbital hybridization promote the enhanced OER activity. The results would provide fresh concepts for the design of improved electrocatalysts and underscore the significance of managing the intrinsic performance through the dual modification of microstructure morphology and electronic structure.

Facile synthesis, characterization, and mechanical properties of spinel-structured high-entropy oxides: Lattice distortion and sluggish diffusion effects induced by aluminum cation

For the first time, we adopted the in-situ formed alumina, which resulted from the thermal decomposition of cheap and accessible potassium alum, as the source of aluminum cation to synthesize (Co1/6Mn1/6Fe1/6Cr1/6Ni1/6Al1/6)3O4 spinel-structured high-entropy oxide powder after the solid state reaction process, showing the advantages of lower synthesis temperature and scalable fabrication. To investigate the effect of aluminum cation insertion on the mechanical properties of (Co1/6Mn1/6Fe1/6Cr1/6Ni1/6Al1/6)3O4, the (Co1/6Mn1/6Fe1/6Cr1/6Ni1/6Al1/6)3O4 and (Co1/5Mn1/5Fe1/5Cr1/5Ni1/5)3O4 ceramics were first fabricated and reported. Owing to significant lattice distortion induced by the aluminum cation, the (Co1/6Mn1/6Fe1/6Cr1/6Ni1/6Al1/6)3O4 possessed higher compressive strength, hardness, and elastic modulus, which were 139.3 MPa, 11.3 GPa, and 167.5 GPa, respectively. Moreover, the average grain size of (Co1/6Mn1/6Fe1/6Cr1/6Ni1/6Al1/6)3O4 only increased from 2.63 µm to 10.11 µm, while that of (Co1/5Mn1/5Fe1/5Cr1/5Ni1/5)3O4 increased from 1.77 µm to 15.61 µm. The slower grain growth rate of (Co1/6Mn1/6Fe1/6Cr1/6Ni1/6Al1/6)3O4 after aluminum cation insertion was attributed to the sluggish diffusion effect.

Lattice distortion effects induced by Li+ co-doping on ZnO:Tb3+ phosphors: Photoluminescence and unusual hypersensitive ⁵D₄ → ⁷F₀ transition

A series of Tb3+, Li+ co-doped ZnO phosphors were prepared using a precipitation method. X-ray diffraction (XRD) analysis indicated the successful incorporation of Tb3+ into the ZnO lattice. The influence of Tb3+ doping content and Li+ charge compensator on the photoluminescence (PL) properties of ZnO:Tb3+ was investigated. Under UV excitation, emissions corresponding to electron transitions 5D4→7FJ (J = 0,1,2,3,4,5,6) were observed from Tb3+ ions, including an unusual emission transition at 673 nm, which significantly enriches our understanding of Tb3+ luminescence. The critical concentration quenching of Tb3+ in ZnO:Tb3+ occurs at 7 mol%, as explained by the Van Uitert equation, which attributes this phenomenon to dipole-dipole interactions. Surprisingly, incorporating Li+ for charge balancing led to a reduction in the luminescence intensity of ZnO:7 mol%Tb3+, x%Li+ phosphors (x = 0.01 and 0.07) at 544 nm. This reduction highlights an increased degree of lattice distortion due to Li⁺ inclusion. Furthermore, CIE chromaticity analysis showed that the optimal doping concentration of 0.07 Tb³⁺ shifted the color coordinates towards vivid green, with a color temperature of approximately 6241 K, indicating of neutral white light.

Rethinking the uncanny valley as a moderated linear function: Perceptual specialization increases the uncanniness of facial distortions

The relationship between artificial entities’ human likeness and aesthetic preference is thought to be best modelled by an N-shaped cubic “uncanny valley” function, which however suffers from conceptual criticisms and lack of parsimony. Here it is argued that uncanniness effects may instead be modelled by a linear function of deviation moderated by perceptual specialization. The two models are compared in an experiment with five incrementally distorted face types (cartoon, CG, drawing, real, robot). Recognition performance for upright and inverted faces were used as a specialization measure. Specialization significantly moderated the linear effect of distortion on uncanniness, and could explain the data better than a conventional uncanny valley. The uncanny valley may thus be better understood as a moderated linear function of specialization sensitizing the uncanniness of deviating stimuli. This simpler yet more accurate model is compatible with neurocognitive theories and can explain uncanniness effects beyond the conventional uncanny valley.

Thermal stability optimization of single-leg skutterudite-based thermoelectric devices based on lattice distortion effects

Skutterudite-based (SKD-based) thermoelectric materials are well-known for their high figure-of-merit (zT value) in the intermediate temperature region. Based on the urgent need for long-term high-temperature service, the poor interfacial thermal stability when connected with the Cu electrodes has greatly limited its industrial application. In this work, we propose a novel alloying route for the barrier layers for p-type SKDs. A Fe80Cr17.5Mo2.50/p-SKD junction with matched coefficients of thermal expansion (CTE), high mechanical reliability, and low contact resistivity is obtained. The addition of large-scale Mo causes severe lattice distortion in the barrier alloy, which contributes to the sluggish elemental diffusion. Thus, after aging at 823 K for 600 h, the Fe80Cr17.5Mo2.5 junction has a thinner reaction layer (∼25 μm), lower contact resistivity (∼3.8 μΩ·cm2), and higher shear strength (∼14 MPa), compared with the Mo-free (Fe80Cr20) barrier junction. Our finding opens a new insight for fabricating long-term high thermally stable SKD-based thermoelectric devices with desirable mechanical stability.

The geometry of the vergence-accommodation conflict in mixed reality systems

Mixed reality technologies, such as virtual (VR) and augmented (AR) reality, present promising opportunities to advance education and professional training due to their adaptability to diverse contexts. Distortions in the perceived distance in such mediated conditions, however, are well documented and have imposed nontrivial challenges that complicate and limit transferring task performance in a virtual setting to the unmediated reality (UR). One potential source of the distance distortion is the vergence-accommodation conflict—the discrepancy between the depth specified by the eyes’ accommodative state and the angle at which the eyes converge to fixate on a target. The present study involved the use of a manual pointing task in UR, VR, and AR to quantify the magnitude of the potential depth distortion in each modality. Conceptualizing the effect of vergence-accommodation offset as a constant offset to the vergence angle, a model was developed based on the stereoscopic viewing geometry. Different versions of the model were used to fit and predict the behavioral data for all modalities. Results confirmed the validity of the conceptualization of vergence-accommodation as a device-specific vergence offset, which predicted up to 66% of the variance in the data. The fitted parameters indicate that, due to the vergence-accommodation conflict, participants’ vergence angle was driven outwards by approximately 0.2°, which disrupted the stereoscopic viewing geometry and produced distance distortion in VR and AR. The implications of this finding are discussed in the context of developing virtual environments that minimize the effect of depth distortion.

The Effects of Supraharmonic Distortion in MV and LV AC Grids.

Since the integration of electronic devices and intelligent electronic devices into the power grid, power quality (PQ) has consistently remained a significant concern for system operators and experts. Maintaining high standards of power quality is crucial to preventing malfunctions and faults in electric assets and connected loads. Recently, PQ studies have shifted their focus to a specific frequency range, previously not considered problematic-the supraharmonic 2 kHz to 150 kHz range. This range is not populated by easily recognizable harmonic components of the 50 Hz to 60 Hz mains fundamental, but by a combination of intentional emissions, switching non-linearities and byproducts, and various types of resonances. This paper aims to provide a detailed analysis of the impact of supraharmonics (SHs) on power network operation and assets, focusing on the most relevant documented negative effects, namely power loss and the heating of grid elements, aging of dielectric materials, failure of medium voltage (MV) cable terminations, and interference with equipment and power line communication (PLC) technology in particular. Under some shareable assumptions, limits are derived and compared to existing ones for harmonic phenomena, providing a clear identification of the primary issues associated with supraharmonics and suggestions for the standardization process. Strictly related is the problem of grid monitoring and assessment of SH distortion, discussing the suitability of normative requirements for instrument transformers (ITs) with a specific focus on their accuracy.

Novel recursive formula for removing damping distortion effect on bridge mode shape restoration using a two-axle scanning vehicle

Mode shapes recovered for bridges are often distorted by bridge damping when using the vehicle scanning method (VSM). To remedy such an effect, a novel recursive formula utilizing the spatial correlation between the front and rear contact points of a two-axle scanning vehicle is theoretically established. For a bridge subjected to a two-axle moving test vehicle, the dynamic response of the system is first derived in closed form. The vehicle-bridge contact response is used as a substitute for the vehicle response in signal processing, since it is free of the masking effect posed by vehicle frequencies. Using either the Hilbert transform (HT) or wavelet transform (WT), instantaneous amplitudes are extracted for the component response of the bridge of concern. Further, recursive formula that accounts for the spatial correlation between the two contact points is established to recover the undistorted bridge mode shapes. The following are the conclusions: (1) The distortion effect of damping on bridge mode shapes can be effectively removed by the recursive formula against various factors; (2) the WT is more effective in recovering undistorted bridge mode shapes than the HT; and (3) the proposed formula works well for restoring the mode shapes of bridges with rough pavement, by adding an accompanying truck during the vehicle scanning.

Regulation of the quantum barrier and carrier transport toward high-efficiency quasi-2D Dion-Jacobson tin perovskite solar cells

Quasi-2D Dion-Jacobson (DJ) tin halide perovskite has attracted much attention due to its elimination of Van der Waals gap and enhanced environmental stability. However, the bulky organic spacers usually form a natural quantum well structure, which brings a large quantum barrier and poor film quality, further limiting the carrier transport and device performance. Here, we designed three organic spacers with different chain lengths (ethylenediamine (EDA), 1,3-propanediamine (PDA), and 1,4-butanediamine (BDA)) to investigate the quantum barrier dependence. Theoretical and experimental characterizations indicate that EDA with short chain can reduce the lattice distortion and dielectric confinement effect, which is beneficial to the effective dissociation of excitons and the inhibition of trap-free non-radiative relaxation. In addition, EDA cation shows strong interaction with the inorganic octahedron, realizing large aggregates in precursor solution and high-quality films with improved structural stability. Furthermore, femtosecond transient absorption proves that EDA cations can also weaken the formation of small n-phases with large quantum barrier to achieve effective carrier transport between different n-phases. Finally, the quasi-2D DJ (EDA)FA9Sn10I31 solar cells achieves a 7.07% power conversion efficiency with good environment stability. Therefore, this work sheds light on the regulation of the quantum barrier and carrier transport through the chain length of organic spacer for quasi-2D DJ lead-free perovskites.

Recent Progress in High‐Entropy Alloy Electrocatalysts for Hydrogen Evolution Reaction

AbstractHigh‐entropy alloys (HEAs) materials, as promising nanomaterials, have garnered significant attention from researchers due to their excellent performance in the field of hydrogen evolution reaction (HER). The four core effects of HEAs, including the high‐entropy effect, severe lattice distortion effect, sluggish diffusion effect, and cocktail effect, are pivotal in underpinning their remarkable mechanical and thermodynamic properties. Nevertheless, the intricate geometric and electronic structures of HEAs make their catalytic mechanisms exceptionally complex and challenging to decipher. In particular, a thorough analysis of the underlying factors responsible for the outstanding catalytic activity, selectivity, and the ability to maintain stable hydrogen production, even at high current densities, in HEAs is lacking. To provide a systematic exploration of the design and application of HEAs in HER systems, this review commences with an examination of the physicochemical properties of HEAs. It covers a wide range of topics, including the synthesis methods of HEAs, and the major reaction mechanisms of HERs, and presents innovative methods and approaches for designing HEAs specifically in the context of HERs.

Impression management strategy — The relationship between accounting narrative thematic bias and financial graph distortion

Prior literature has examined 10-K narrative thematic bias and financial graph distortion as two independent outcomes that might arise from managements' efforts at impression management. Largely unexplored is an analysis of narrative thematic bias and financial graph distortion as joint and interrelated outcomes that would arise if management coordinates both in the same 10-K report as part of an impression management strategy. We fill this void in the literature by using a simultaneous equation system to examine the joint relationship between narrative thematic bias and graph distortion in the 10-K filings of S&P 500 firms from 2014 to 2018. We draw upon Paivio's (1986) dual coding theory to predict a positive association between narrative thematic bias and financial graph distortion based on the insight that graph distortion helps reinforce the effects of thematic bias, and vice versa. Consistently, we find a simultaneous and positive relationship between thematic bias and graph distortion. Further, we find that this complementary relationship is more pronounced in firms with weak corporate governance and weak external monitoring. Our findings suggest that management may exploit the reinforcing effects of thematic bias and graph distortion to leave financial statement users with a more favorable impression of firm performance.

Influence of wind directionality on the three-dimensional distortion of buffeting force on a streamlined bridge deck: Insight into the pylon interference effect

The present work aims to experimentally investigate the influence of wind directionality on the three-dimensionality of buffeting force on a streamlined bridge deck, considering the pylon interference effect (PIE). The pylon has an obvious impact on the downstream flow structure under the skew wind, influencing the aerodynamic loads acting on the bridge deck. The results show that the most dangerous wind direction exists at 30° for the downstream bridge deck, indicating the invalidation of the traditional “cosine rule.” It indicates that the lift force will be amplified due to the PIE, depending on the yaw angle of the oncoming flow. When turbulence passes through the pylon, the large-scale eddies in the wake region will be broken into small-scale eddies, attenuating the integral length scale in comparison with that of the free-stream turbulence. Consequently, the lift spectrum and corresponding three-dimensional aerodynamic admittance (AAF) increase in the high-frequency domain, resulting in the decrease in the spanwise correlation under the skew wind. Notably, the two-dimensional (2D) AAF indicates that the 2D distortion effect of turbulence on the lift increases in the wake region, causing the 2D AAF to decay rapidly in the high-frequency domain.

Galaxy clustering multi-scale emulation

Simulation-based inference has seen increasing interest in the past few years as a promising approach to modelling the non-linear scales of galaxy clustering. The common approach, using the Gaussian process, is to train an emulator over the cosmological and galaxy–halo connection parameters independently for every scale. We present a new Gaussian process model that allows the user to extend the input parameter space dimensions and to use a non-diagonal noise covariance matrix. We use our new framework to simultaneously emulate every scale of the non-linear clustering of galaxies in redshift space from the ABACUSSUMMITN-body simulations at redshift z = 0.2. The model includes nine cosmological parameters, five halo occupation distribution (HOD) parameters, and one scale dimension. Accounting for the limited resolution of the simulations, we train our emulator on scales from 0.3 h−1 Mpc to 60 h−1 Mpc and compare its performance with the standard approach of building one independent emulator for each scale. The new model yields more accurate and precise constraints on cosmological parameters compared to the standard approach. As our new model is able to interpolate over the scale space, we are also able to account for the Alcock-Paczynski distortion effect, leading to more accurate constraints on the cosmological parameters.

Adaptive Local Flaw Detection Based on Magnetic Flux Leakage Images With a Noise Distortion Effect for Steel Wire Ropes

Steel wire rope (SWR) is widely used in industrial scenarios because of its high strength and toughness. To avoid accidents that local flaws (LFs) can cause, SWRs should be inspected regularly. Magnetic flux leakage (MFL) image detection, which is a common SWR inspection method, is inevitably influenced by shaking noise and strand noise. Although noise-reduction methods for these two types of noise have been proposed, the phenomenon of noise distortion has not received enough attention. This paper investigates the noise distortion phenomenon on the MFL image and finds that the distorted noise severely affects the performance of existing noise-feature-oriented (NFO) denoising methods. To solve this problem, we adopt a target-feature-oriented (TFO) denoising method. Specifically, the removal of noise is avoided, instead, an LF-enhancement-based denoising process is proposed. Moreover, to localize LFs in denoised images, a three-stage adaptive localization method mainly based on disjoint region analysis is proposed. The experiment results show that the proposed TFO denoising method significantly improves the denoising performance for images that distorted noise influences. In addition, the proposed adaptive localization method improves the intelligence of the localization process and has better localization performance for images with distorted noise.