Distortion Mechanisms Research Articles

Predictions and Experiments on the Distortion of the 20Cr2Ni4A C-ring during Carburizing and Quenching Process.

This paper focuses on the effect of gear steel on distortion due to phase transformation in carburizing and quenching. The carburizing and quenching process of C-rings under suspension was studied by using the finite element method based on the thermo-mechanical theory, considering phase transformation. The phase transformation kinetics parameters, depending on different carbon contents, were measured by Gleeble-3500. The distortion behavior of the carburized C-ring during the cooling stage was analyzed, as well as the carbon concentration distribution and martensite volume fractions. The accuracy of the simulation was also verified by comparing the experimental data with the simulated result of the distortion and microstructure. A reliable basis is provided for predicting the distortion mechanism of gear steels in carburizing and quenching.

Printable and Stretchable Conductive Elastomers for Monitoring Dynamic Strain with High Fidelity

AbstractPrintable and stretchable conductive elastomers have promising applications for epidermal and wearable electronics, soft robotics, etc. However, these conductive materials usually present poor performances in monitoring dynamic strains. The monitored signals are distorted and lose key physical signs, which limit their practical applications. Through investigating kinetic behaviors of conductive pathways along longitudinal and transverse directions in these conductive materials, the physical mechanism of signal distortion under dynamic strains is interpreted. To overcome this strain sensing problem, an Ag‐Ecoflex‐polydimethylsiloxane (PDMS) elastomer by printing Ag‐filler‐Ecoflex‐matrix ink on PDMS is proposed. Compared to other conductive materials, the Ag‐Ecoflex‐PDMS elastomer has preferable dynamic performances, embodying smaller overshoot response, higher strain sensitivity, and lower hysteresis. A deep‐learning‐based dynamic calibration method is proposed to successfully correct the sensing signals and eliminate the hysteresis error to 0.1%. Moreover, the proposed Ag‐Ecoflex‐PDMS elastomers gain high electrical conductivities owing to thermal expansion and contraction of PDMS substrate during the thermosetting of conductive ink, and thus can be both excellent stretchable sensors and stretchable conductors. Demonstrations of monitoring knee motion with high fidelity and human–robot collaborative playing ping‐pong validate superior accuracy and robustness of the Ag‐Ecoflex‐PDMS elastomers for monitoring human dynamic activities, human‐machine collaboration, virtual reality, etc.

How Energy Price Distortions Affect China’s Economic Growth and Carbon Emissions

China’s energy market reform is characterized by “asymmetry” as a result of the transition from a planned economy to a market economy, leading to typical distortions in energy prices. Using panel data from 30 Chinese provinces during 2006–2018, this paper examines the impact of the price distortions of fossil energy sources (coal, oil, and natural gas) as well as renewable energy on China’s economic growth and carbon emissions. The results show that coal price distortion is the highest among the fossil energy sources, followed by oil and natural gas. Renewable energy price is positively distorted. Not all price distortions of energy sources significantly impede economic growth—only those of coal and renewable energy. In contrast, oil and natural gas price distortions promote economic growth. All four energy price distortions contribute significantly to the increase in carbon emissions. Further analysis reveals that regional heterogeneity exists in the impact of energy price distortions on economic growth and carbon emissions. Additionally, this study finds that technological innovation, industrial structure upgrading, the investment effect, the optimization of energy consumption structure, and environmental regulations are important transmission mechanisms of energy price distortions affecting China’s economic growth and carbon emissions. The findings of this study can help us to understand the relationship between energy price distortions and China’s economic growth and carbon emissions, and provide a reference for formulating energy price reform policies that benefit the win-win development of China’s economy and environment.

Robust Control Method of Grid-Connected Inverters With Enhanced Current Quality While Connected to a Weak Power Grid

In order to improve the robust stability of the grid-connected inverter of wind power or photovoltaic power generation while connected to a weak power-grid, the robust model of grid-connected inverter under weak power-grid is established, and the influence mechanism of power-grid impedance and voltage distortion on the stability and current quality of grid-connected inverter is analyzed. On this basis, an adaptive robust <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H_∞</i> control method is proposed, in which there is no need to online measure the power-grid impedance, and the control parameters do not change with the change of the power-grid impedance. Then, the calculation method of each reference quantity and the design method of control parameters are introduced. Finally, an experimental platform is built, and the correctness and effectiveness of the theoretical analysis and the proposed control method are verified by experiments. Compared with other control methods, the adaptive robust <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H_∞</i> control method realizes the stability of the system when the power-grid impedance varies in a wide range, which optimally restrains the power-grid voltage distortion and improves the quality of grid-connected current.

Solvent‐Mediated Structural Evolution in Colloidal Lead Halide Perovskite Nanocrystals Self‐Assembly

AbstractFiguring out the inner mechanism of lattice distortion and unstable factors of inorganic perovskite nanocrystals in solvents is essential for fundamental studies and applications in photonic devices. Traditional research results simply ascribed the unstable factor to solvent polarity, which in fact are insufficient and inaccurate to explain some phenomena. Here, we propose a molecular level mechanism that the crucial cause for the instability of perovskite nanocrystals in solutions is the competition between complex bond energies in colloidal nanocrystals system. In combination with molecular dynamics simulations and first principle calculations, the kinetic process of lattice distortion and self‐assembly of perovskite nanocrystals is revealed in solutions. By tailoring the relative magnitude of the hydrogen bond energy between ligand ammonium ion and halogen, the van der Waals force between the ligands of adjacent nanocrystals and the bond energy between lead atom and halogen, nanocrystal arrays and single‐crystalline nanowires based on all‐inorganic perovskite nanocrystals can be freely obtained. Moreover, the polarization properties of the obtained nanowires are studied, which are related to their formation process.

Characterization of moral disconnection mechanisms used by students attending an official Educational Institution of the Department of Sucre- Colombia

El objetivo del presente estudio fue caracterizar los mecanismos de desconexión moral (DM) utilizados por un grupo de escolares pertenecientes a una Institución Educativa pública del Departamento de Sucre- Colombia. Se aplicó el cuestionario MD para medir la desconexión moral (Bandura, Barbaranelli, Caprara &amp; Pastorelli, 1996). Participaron 192 escolares (chicos y chicas) que cursaban 5to de primaria y 9no de secundaria. Los resultados evidenciaron que los mecanismos de DM más utilizados para justificar actos de agresión y de violencia son: transferencia de la responsabilidad, difusión de la responsabilidad, distorsión de las consecuencias y la culpabilización de la víctima. Es entre los 10 y 12 años de edad que se reportó con mayor frecuencia el uso de estos mecanismos, destacando que chicos y chicas utilizan por igual los mecanismos de distorsión de las consecuencias y la difusión de la responsabilidad. Los resultados permitirán proponer planes de intervención pertinentes a la realidad de los contextos educativos de la región.

Uncovering the Interplay of Competing Distortions in the Prussian Blue Analogue K2Cu[Fe(CN)6

We report the synthesis, crystal structure, thermal response, and electrochemical behavior of the Prussian blue analogue (PBA) K2Cu[Fe(CN)6]. From a structural perspective, this is the most complex PBA yet characterized: its triclinic crystal structure results from an interplay of cooperative Jahn–Teller order, octahedral tilts, and a collective “slide” distortion involving K-ion displacements. These different distortions give rise to two crystallographically distinct K-ion channels with different mobilities. Variable-temperature X-ray powder diffraction measurements show that K-ion slides are the lowest-energy distortion mechanism at play, as they are the only distortion to be switched off with increasing temperature. Electrochemically, the material operates as a K-ion cathode with a high operating voltage and an improved initial capacity relative to higher-vacancy PBA alternatives. On charging, K+ ions are selectively removed from a single K-ion channel type, and the slide distortions are again switched on and off accordingly. We discuss the functional importance of various aspects of structural complexity in this system, placing our discussion in the context of other related PBAs.

Structure and function of DNA transposition assemblies involved in antibiotic resistance spreading

Transposons are mobile genetic elements that drive evolution and adaptation throughout the tree of life. In bacteria, they often transfer antibiotic resistance genes and contribute to the emergence of multidrug‐resistant pathogens.In this talk, I will present our recent discoveries on a group of transposons that efficiently propagate antibiotic resistance genes across diverse microbial communities. Using a dedicated computational pipeline, we mapped the most wide‐spread transposons in bacterial genomes and characterized their diversity, genetic cargo, and transfer dynamics. Selected elements were experimentally reconstituted to describe their molecular mechanisms and biochemical pathways. We determined numerous high‐resolution crystal and cryo‐EM structures of the protein‐DNA assemblies involved in transposon movement. The structures capture various stages of transposition and reveal an intricate interplay between the core transposition machinery and host‐encoded proteins. Protein interactions shape transposon and genomic DNA in unique ways to cut, exchange and re‐join strands in a tightly regulated manner. Importantly, our data also explain how specific DNA distortion and cleavage mechanisms enable the transposons to move between diverse genomic sites, expanding gene transfer across many species.These results shed new light onto the molecular strategies of antibiotic resistance carrying transposons and show how they evolved to effectively spread key genetic traits. Our insights also open new opportunities to develop strategies for blocking transposition and thereby help control resistance spreading.

An improved distance relay based on electronic transformer by using instantaneous value after equal transfer processes

This paper analyses the formation mechanism of the transmission distortion of electronic voltage transformer, and points out that the integrator will magnify the transient transfer error and superimpose the dynamic additional component on the output signal, which may cause the transfer distortion of voltage signal in serious cases. To restrict the electronic transformer transient variable error effect on distance relay, a distance relay method using instantaneous value after equal transfer processes is proposed. It directly uses output differential signals of the capacitor voltage divider and Rogowski coil. The capacitor voltage divider and Rogowski coil are decomposed into several typical variable link in series. The virtual digital transfer link, which is constructed by the digital filter, is used to compensate for the difference parts of the transfer link, so that the voltage and current signals pass through the same transfer link. It can mitigate the influence of voltage and current signal transfer difference on the calculation accuracy of distance relay. The simulation results show that the proposed distance relay method has fast operation speed and is less affected by abnormal voltage and current signal transfer, and its performance is better than existing distance relay methods.

Harmonic and Supraharmonic Emissions of Plug-In Electric Vehicle Chargers

Electric vehicle (EV) charging represents a relevant electric load with a rapid evolution in terms of number, power rating and distortion, in particular, considering the connection to the low-voltage public grid: available short-circuit power may be limited and particularly susceptible loads may co-exist in the same grid portion. Standards can partially address the problem covering only the harmonic interval, but they necessitate significant extension and improvement in the supraharmonic range. In addition, EV chargers have been observed to violate in some scenarios the applicable harmonic limits, so that the mechanisms of emission and distortion should be better understood and evaluated, including phenomena of mutual influence between EV chargers and with pre-existing grid distortion. Although models can help simulate large-scale scenarios in terms of fundamental frequency phenomena, such as power flow, voltage fluctuation and imbalance, substantial and reliable information can come from experimental results, providing measured harmonic and supraharmonic emissions, accompanied by details on loads mix, grid characteristics and EV charger operating conditions. This work thus defines the applicable constraints in terms of limits and compatibility levels for public and light industrial low-voltage grids, discusses the available experimental results and datasets, analyzing the typical distortion behavior and providing indication of sources of information for further studies.

John-Teller Distortion in Octahedral hexaaquacopper (II) Transition for S=1/2, d9 Metal Complex

Jahn–Teller effect (JTE) describe how specific electrons distributions induce geometric deformation in molecules or ions. The distortion of Jahn–Teller (JT) takes place because of the uneven occupation of orbitals with the identical energies is disapproving. To prevent such inappropriate electronic arrangements, molecules distort (lose regularity), causing these orbitals to become non-degenerate. This distortion is most frequently seen in octahedral compounds, at which two axial bonds could be squeezed (compressed) or extend (elongated), leading to bond lengths that the different from equator bonds. The degeneracy of electronic states really isn’t accurately measured, but it would be measured precisely by the disparity in a concentration of electron among metal and the ligands upon on axil direction. The density functional theory has been used to calculate bond length in both cases geometry for , octahedral metal-complexes, the majority ordinary mechanism of distortion is elongation (z-out). In perfectly octahedral complexes deformation, the orbitals energy is changed more than the orbitals energy, causing elongation z-out distortion. The d-levels energy would be splitting in a ligand field throughout transition metal centers can frequently result in degenerate electron configurations that are subject to Jahn–Teller effects. In six-coordinate complexes of copper II ions. It is also significant in fewer regular oxidation levels of other transition ions with that count.

Effect of Process Parameters on Distortions Based on the Quantitative Model in the SLM Process

The selective laser melting (SLM) process provides a more extensive design space and manufacturability. However, it is still hindered by its inaccuracy in dimension and functionality. The distortion in the SLM process affects the dimensional accuracy of the component and may even hinder the SLM process. Still, the distortion mechanism has not been well explained; specifically, the effects from the process parameters and scan strategies on the distortion have not been sufficiently investigated. In this study, a quantitative model that considers displacements, plastic strains, and thermal strains on each layer is developed to analyze the distortion mechanism. The distortion is found to be induced by a residual stress gradient among the layers. Then, a transient numerical method calculates residual stress, plastic strain, and distortion in the SLM process. Different simulations with various layers, scanning speeds, stiffness of support structures, and scan strategies are performed to study the relationship between process parameters and distortion. It can be found that the distortion decreases as the height increases. The distortion increases with the scanning speed, reaching the maximum at 700 mm/s and then dropping. We concluded that increasing the stiffness of the support structures is beneficial to reduce the distortion and changing the scanning direction among layers is useless to reduce the distortion. This study gives a theoretical model to analyze the distortion and provides guidance for reducing distortions in the SLM process.

Far-field sonic boom prediction considering atmospheric turbulence effects: An improved approach

Accurate prediction of sonic boom is one of key challenges for the design of a low-boom supersonic aircraft. For most of available far-field prediction methods, the effect of atmospheric turbulence appearing in the planetary boundary layer cannot be considered, which results in remarkable inaccuracy of predicting ground-level sonic boom waveform. Although some efforts have been made to overcome the shortcoming, the turbulence effects are not yet well described so far. This article proposes an improved method by extending the two-dimensional Heterogeneous One-Way Approximation for the Resolution of Diffraction (HOWARD) equation to account for the axial and transverse convections of wind fluctuation as well as the effect of temperature fluctuation. The proposed method is validated by comparing the predictions with the flight-test data of JAXA D-SEND#1 LBM, which shows that the result of the proposed method is in better agreement with the flight-test data than that of the method without considering atmospheric turbulence effects. Then, distortion mechanism of sonic boom waveforms caused by atmospheric turbulence is analyzed by using the proposed method. It is indicated that the effect of turbulent convection makes uniform sonic-boom wavefronts irregular, which creates the condition of diffraction effect to perturb waveforms. Finally, the proposed method is applied to investigate the behavior of two types of waveforms given by the sonic boom minimization theory. Results show that a far-field waveform with a weaker initial shock is more beneficial for low-boom design of a supersonic aircraft.

Formation mechanism of nano-sized η and ω structures in β phase in ECP treated Cu-40Zn alloy

Two nano-scaled hexagonal distortions in high temperature BCC phase during cooling is commonly observed in many alloys systems. Although efforts have been made on studying the lattice softening of the BCC structure during cooling, the distortion mechanisms are less addressed. Thus, the formation of two hexagonal structures in the β precipitates in a Cu-40Zn alloy treated by ECP was thoroughly investigated. Results show that the β precipitates contain two kinds of nano-sized and diffuse atomic clusters one with a η structure obeying the Burgers OR and the other a ω structure obeying the Blackburn OR. They were each formed through a two-stepped atomic displacement. For the η structure, the first step is the atomic shuffle of each second 110β plane in the <11¯0>β direction and the second is a structure change mainly by a {1 1¯ 2} < 1¯11>β shear. For the ω structure, the first is an atomic shuffle on each second and third {112¯}β plane in the ± [111]β directions and then normal strains in three mutually perpendicular directions. The concomitant formation of the two structures minimizes the lattice distortion of single formation. The present results provide new information on the formation mechanism of the two hexagonal structures in a BCC matrix.

Liquid–liquid transition in elemental liquids investigated by sound velocity measurements: trends in the periodic table

Abstract The velocity of sound has been measured as a function of temperature to investigate structural changes in the molten As–Sb alloy. The overall profile of temperature dependence of the sound velocity changes smoothly from Sb to As. The results indicate that a tendency to change structures in the supercooled state develops with increasing As fraction, and confirm the previous conclusion that molten As changes rapidly its structure in the undercooled state and is already in the high-temperature side of an assumed liquid – liquid transition at the melting point. By confirming the structural transition in molten As, it is possible to mark the elements in the periodic table that undergo a crossover liquid –liquid transition around the melting point under the saturating vapor pressure. Observed trends for liquid – liquid transitions are discussed on the basis of the Peierls distortion mechanism.

Mechanism of Spectral Distortion for Real-Time Crack Propagation on Aluminum Alloy Structure

This study investigates four characteristic damage mechanisms of fiber Bragg grating (FBG) sensors, with fatigue crack propagation in aluminum alloy. The multipeak wavelength distinguish algorithm was developed for FBG spectrum quantitative analysis. The results distinguish a subordinate peak skewing significantly, associated with strain patterns along the FBG, corresponding to various crack lengths. For parallel bonded direction grating, the subordinate peak skewing appears at the strain pattern transition region. This is located at the ratio 32%-34% of crack length lying in the crack tip. Meanwhile, the four damage characteristics correspond to subordinate peak skewing. When the strain is distributed along the grating, spectral distortion occurs. In this region, the cubic strain pattern determines the shorter wavelength location of subordinate peaks. This corresponds to the 15%-17% ratio of crack length lying in the grating, causing spectral oscillations.

Advanced Distortion Analysis of Heat Treated Rings*

Abstract The basic approach to interpret distortion as a system property is accepted in science and industry. The determination of significant factors and interactions on distortion in the overall production process of selected components represents a central point to identify relevant distortion mechanisms. In this context, a component specific distortion description is a major step to answer distortion problems. In the field of ball bearing engineering, roundness deviation of raceways is an important characteristic. But this parameter is not useful for distortion engineering because no information concerning ring shape is given. But in literature, roundness deviation can be separated in its respective forms like oval and triangle shape with harmonic analysis. In addition, this analysis can be used to specify an amplitude and a direction in the different shapes to describe distortion. In this article, harmonic analysis is used for advanced distortion analysis of tapered roller bearing. An analysis in graphical form is introduced, which illustrates both the amount and the direction of distortion.

Outer hair cell driven reticular lamina mechanical distortion in living cochleae

Cochlear distortions afford researchers and clinicians a glimpse into the conditions and properties of inner ear signal processing mechanisms. Until recently, our examination of these distortions has been limited to measuring the vibration of the basilar membrane or recording acoustic distortion output in the ear canal. Despite its importance, the generation mechanism of cochlear distortion remains a substantial task to understand. The ability to measure the vibration of the reticular lamina in rodent models is a recent experimental advance. Surprising mechanical properties have been revealed. These properties merit both discussion in context with our current understanding of distortion, and appraisal of the significance of new interpretations of cochlear mechanics. This review focusses on some of the recent data from our research groups and discusses the implications of these data on our understanding of vocalization processing in the periphery, and their influence upon future experimental directions.This article is part of the Special Issue Outer hair cell Edited by Joseph Santos-Sacchi and Kumar Navaratnam

An enhanced output voltage compensator for inverter under nonlinear load and voltage distortions

This paper focuses on voltage source inverters used in new energy user power supply and energy storage power supply systems. If it is equipped with linear load, the power quality of output voltage can be easily guaranteed. If it is equipped with a nonlinear load, the system is affected by output impedance, and the output voltage is easy to be distorted. In this paper, the mechanism of output voltage distortion of inverter with a nonlinear load is studied. It is concluded that the distortion is caused by the voltage drop of nonlinear load current in the output impedance of the inverter. We proposed an embedded repetitive control compensator to improve the output voltage quality. In addition, we give out the Bode diagram parameters select method. The simulation results show that the proposed control strategy is feasible and effective.

Strain driven phase transition and mechanism for Fe/Ir(111) films

By way of introducing heterogeneous interfaces, the stabilization of crystallographic phases is critical to a viable strategy for developing materials with novel characteristics, such as occurrence of new structure phase, anomalous enhancement in magnetic moment, enhancement of efficiency as nanoportals. Because of the different lattice structures at the interface, heterogeneous interfaces serve as a platform for controlling pseudomorphic growth, nanostructure evolution and formation of strained clusters. However, our knowledge related to the strain accumulation phenomenon in ultrathin Fe layers on face-centered cubic (fcc) substrates remains limited. For Fe deposited on Ir(111), here we found the existence of strain accumulation at the interface and demonstrate a strain driven phase transition in which fcc-Fe is transformed to a bcc phase. By substituting the bulk modulus and the shear modulus and the experimental results of lattice parameters in cubic geometry, we obtain the strain energy density for different Fe thicknesses. A limited distortion mechanism is proposed for correlating the increasing interfacial strain energy, the surface energy, and a critical thickness. The calculation shows that the strained layers undergo a phase transition to the bulk structure above the critical thickness. The results are well consistent with experimental measurements. The strain driven phase transition and mechanism presented herein provide a fundamental understanding of strain accumulation at the bcc/fcc interface.