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Purpose: To compare the 3D accuracy of three scanning strategies and conventional impressions using an edentulous model with six implants. Materials and Methods: An edentulous maxillary master model was fabricated with six equigingival internal connection implants at 0 degrees of angulation. Ten conventional open-tray splinted implant-level impressions were made and poured in stone. A master model and conventional casts were digitized with a reference scanner. Digital impressions were made by calibrated clinicians with a TRIOS 3 intraoral scanner ([IOS] 3Shape) according to three scanning strategies: DIG1 (occlusal-palatal-lingual), DIG2 (S-type motion from buccal to palatal), and DIG3 (scanning two half arches and connecting them at the midline). Each technique was repeated 10 times on the master model. Deviations from the STL datasets (N = 40) were compared to those of the reference master model using the Hexagon Metrology software system PC-DMIS CAD++. Linear distortions (dX, dY, dZ), global linear distortion (dR), and angular distortions (Absdθx, Absdθy) were calculated. Kruskal-Wallis test and mixed linear and logistic regression models were used to compare the original and binary distortion measures between the techniques. Results: The mean dR ranged from 91 μm (conventional method) to 183 μm (DIG1). The mean angular distortion ranged from 0.20 degrees (Absdθx for DIG2) to 0.69 degrees (Absdθy for DIG3). No scan pattern resulted in a more accurate reproduction in any of the measured parameters than the conventional impression method. There were significant differences between the methods for all distortion measures. Conclusions: No group reproduced the 3D position of the six-implant master model below the thresholds for both global linear and angular distortions. All the digital strategies tested were less accurate than the conventional open-tray splinted implant-level impression technique. [ABSTRACT FROM AUTHOR]

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In this paper, the accurate free vibration characteristics of thin-walled box beam are discussed and the kinematic model is established by using fine shear deformation theory. The model adopts the in-plane and out-of-plane displacement fields including extension, torsion, warping and distortion, as well as the transverse shear due to bending and warping due to torsion. One-dimensional high-order beam theory is applied to the dynamic solution of thin-walled box beam, and the analytical solution of high free vibration modes of multi-deformation coupled modes under different boundary conditions is derived. The results show that warping, distortion and shear deformation play an important role in the free vibration characteristics of thin-walled box beam, and the validity of the model is verified. In addition, finite element software (ANSYS) is used for finite element simulation. The application of vibration mode in the structure design of thin-walled box beam is summarized, especially in the case of higher natural frequency. The calculation method is in good agreement with the finite element results. [ABSTRACT FROM AUTHOR]

Featured Application: Composite tooling design and manufacturing. Composite laminate design optimization through advanced simulation methods. Unintended shape distortions, such as spring-in, spring-back, and warping, commonly occur during the curing process of laminate composites. The source of dimensional changes at the macro-scale is residual stress. The main triggers for residual stresses at this scale are anisotropic behavior and the constraint effect of individual plies and tooling constraints. Thermoelastic residual stresses are quasi-reversible, whereas non-thermoelastic residual stresses are permanent, and the underlying mechanisms contributing to them are highly intricate. The challenges associated with simulating the curing of large-scale parts to obtain reliable engineering data are significantly influenced by factors such as thermal anisotropy, polymerization shrinkage, tool–part interaction, resin flow, and compaction. A comprehensive grasp of the involved phenomena can facilitate the creation and application of numerical tools that model the curing process, providing essential information on geometry distortion that is crucial for the overall manufacturing of structural components and assemblies. To ensure that a numerical prediction tool is dependable in terms of both accuracy and precision, it is essential to have significant experimental backing throughout the entire process, from selecting the appropriate mathematical models to calibrating the calculations of distortion values. [ABSTRACT FROM AUTHOR]

Symmetry is a fundamental property of many natural systems, which is observable through signals. In most out-of-equilibrium complex dynamic systems, the observed signals are asymmetric. However, for certain operating modes, some systems have demonstrated a resurgence of symmetry in their signals. Research has naturally focused on examining time invariance to quantify this symmetry. Measures based on the statistical and harmonic properties of signals have been proposed, but most of them focused on harmonic distortion without explicitly measuring symmetry. This paper introduces a new mathematical framework based on group theory for analyzing signal symmetry beyond time invariance. It presents new indicators to evaluate different types of symmetry in non-stochastic symmetric signals. Both periodic and non-periodic symmetric signals are analyzed to formalize the problem. The study raises critical questions about the completeness of symmetry in signals and proposes a new classification for periodic and non-periodic signals that goes beyond the traditional classification based on Fourier coefficients. Furthermore, new measures such as "symmetrometry" and "distorsymmetry" are introduced to quantify symmetry. These measures outperform traditional indicators like Total Harmonic Distortion (THD) and provide a more accurate measurement of symmetry in complex signals from applications where duty cycle plays a major role. [ABSTRACT FROM AUTHOR]

Purpose: To assess the predictive value of pre-operative metamorphopsia, measured using the D-Chart, in patients undergoing epiretinal membrane (ERM) surgery and how this relates to improvement in quality of life after surgery. Methods: 17 patients from vitreo-retinal surgery clinics at a tertiary ophthalmology centre were recruited when listed for pars plana vitrectomy (PPV) with ERM peel between September 2019 – February 2020. Pre-operatively patients underwent visual acuity (VA), Visual-Function Index 14 (VF-14) and metamorphopsia (D-Chart—Thomson Software Solutions) assessment and answered a questionnaire regarding cardinal ERM symptoms. Post-operatively patients were re-assessed in the same domains. Results: 13 patients completed the protocol (inclusion rate 76%) with a mean follow-up of 32.1 (± 3.1) months. Mean pre-operative VA of the affected eye was 0.42 logMAR (± 0.25). Mean pre-operative VF-14 score was 81.51 (± 12.8) and mean M-Score of the affected eye was 14.6 (± 12.7). Post-operatively, mean VA of the operated eye was 0.11 logMAR (± 0.11), mean VF-14 score was 97.4 (± 3.8) and mean M-Score was 1.31 (± 2.8). Mean improvement in VA was 0.31 logMAR (p < 0.001), in VF-14 15.9 (p = 0.002), and M-Score -13.3 (p = 0.003). There was a significant association between pre-operative D-Chart score and improvement in VA (r = -0.570, p = 0.042), visual functioning (r = 0.606 p = 0.028) and metamorphopsia (r = 0.916 p < 0.001), with those demonstrating poorer D-Chart scores showing greater improvements. Conclusion: Pre- and post-operative visual distortion measured using the D-Chart, correlates with vision related quality of life in patients undergoing epiretinal membrane surgery. Patients with worse pre-operative distortion scores noticed the greatest improvements in distortion and vision related quality of life following surgery. With a mean follow-up time of 32.1 months, this long-term follow-up data further reinforces the efficacy of vitrectomy and ERM peel by demonstrating significant and sustained improvement in visual acuity, metamorphopsia and visual functioning. The authors suggest there is a role for D-Chart assessment pre-operatively to improve selection of patients in ERM surgery. [ABSTRACT FROM AUTHOR]

Background: Geometric distortion is a serious problem in MRI, particularly in MRI guided therapy. A lack of affordable and adaptable tools in this area limits research progress and harmonized quality assurance. Purpose: To develop and test a suite of open‐source hardware and software tools for the measurement, characterization, reporting, and correction of geometric distortion in MRI. Methods: An open‐source python library was developed, comprising modules for parametric phantom design, data processing, spherical harmonics, distortion correction, and interactive reporting. The code was used to design and manufacture a distortion phantom consisting of 618 oil filled markers covering a sphere of radius 150 mm. This phantom was imaged on a CT scanner and a novel split‐bore 1.0 T MRI magnet. The CT images provide distortion‐free dataset. These data were used to test all modules of the open‐source software. Results: All markers were successfully extracted from all images. The distorted MRI markers were mapped to undistorted CT data using an iterative search approach. Spherical harmonics reconstructed the fitted gradient data to 1.0 ± 0.6% of the input data. High resolution data were reconstructed via spherical harmonics and used to generate an interactive report. Finally, distortion correction on an independent data set reduced distortion inside the DSV from 5.5 ± 3.1 to 1.6 ± 0.8 mm. Conclusion: Open‐source hardware and software for the measurement, characterization, reporting, and correction of geometric distortion in MRI have been developed. The utility of these tools has been demonstrated via their application on a novel 1.0 T split bore magnet. [ABSTRACT FROM AUTHOR]

Dimensional tolerances for high-speed-machined aluminum products continue to tighten due to the demand for automated assembly of complex monolithic parts in aerospace and other industries. Understanding the contribution of inherent residual stress in wrought Al 7050-T7451 plate, common in aircraft manufacture, to distortion of high-aspect-ratio machined parts is critical but remains problematic due to the alloy's low residual stress magnitude over large geometries. Prior investigations into residual stress effects on machined part distortion suffer inadequate characterizations of the wrought material stress field, either because of low fidelity due to "slitting" methods, confounding effects in machined-layer removal methods, or small sample size when using neutron diffraction (ND). In this work, inherent residual stress is measured via ND at 860 locations in a 90.5 mm thick Al 7050-T7451 plate having dimensions 399 mm in the rolling direction and 335 mm in the transverse direction. Unlike prior studies, the ND residual stress is reconstructed using an iterative algorithm to ensure fully compatible, equilibrated 3D field prior to examining its effect on distortion. The findings from simulations and experiments show that inherent residual stress alone could distort a high-aspect-ratio part beyond aerospace industry requirements, that slitting measurements may not sufficiently characterize residual stress for predicted distortion, and that parts machined from different plate thickness locations could exhibit reversed distortion patterns. Thus, research into distortion prediction that considers machining should carefully characterize and reconstruct inherent residual stress so that the coupled machining effects are accurately modeled. [ABSTRACT FROM AUTHOR]

The metal additive manufacturing (MAM) process has most employed methods to build complex geometry and lightweight 3-dimensional (3-D) parts directly from a computerized solid model. Distortion of the printed part is a highly significant concern within the MAM process. This issue is because of the heating and cooling effect of printing process that could accumulate residual stress (RS) during part building up. The aim of the literature work is to present various methodologies for measuring RS in MAM components and to furnish a brief summary of recent developments in the domain. These details aid scholars in the discernment of suitable techniques, namely destructive, semi-destructive, or non-destructive, contingent on their particular applications and the accessibility of these methods. Moreover, it facilitates the explication of their formation mechanisms, effectiveness of process parameters, prediction, and control techniques. The effect of RS on the mechanical characteristics of printed parts is analyzed and presented. Additionally, common defects incorporated into RS are discussed. Moreover, this review article discusses about the future challenges and opportunities in the RS analysis of MAM parts.Highlights: ●Different technique of residual stress measurement in additive manufacturing process. ●Influence of process parameter on residual stress. Scanning speed, layer height, laser power, laser energy density etc. ●Impact of residual stress on mechanical properties. ●Common defect due to residual stress. Delamination, parts cracking, separation from support, grain boundary cracking etc. ●Impact of in-process and post-process techniques in residual stress modification. Shot peening, heat treatment, hot isotatic pressing, laser shock peening etc. [ABSTRACT FROM AUTHOR]

In order to prevent any potential setbacks in modern ultra-supercritical power plants, a numerical welding simulation was conducted on thin AISI304 steel plates and pipes. This simulation aimed to evaluate various factors such as transient temperature distribution, thermal cycle curves, residual stress states, and deformation in the welded pipe. The analysis employed a sequential couple method, incorporating the Element Birth and Death (EBD) technique to simulate the addition of filler metal. For the thermal analysis, a prescribed temperature was applied using DC3D8 element type for plates and DC3D20 for pipe weldment. Remarkably, the calculated temperature histories outside the weld pool closely matched numerical and experimental measurements found in the literature. The results exhibited an acceptable deviation for the AISI304 plate weldment. Initial measurements of residual stresses were focused on locations with high intensity. The maximum peaks were identified on the inside surface of the pipe weldment, revealing Tresca stresses of 434.76 MPa and von Mises stresses of 371.89 MPa at a distance of 1.05 mm from the weld centerline (WCL). Additionally, inside circumferential stresses were observed at 361.44 MPa Tresca and 311.67 MPa von Mises at a distance of 9.5 mm from the weld centerline at the specific moment when the weld torch was at t = 160 s . [ABSTRACT FROM AUTHOR]

In immersive VR, a self-avatar that replicates the user’s movements and is viewed from a first-person perspective can substitute the real body. If the avatar’s movements are sufficiently synchronized with the user’s actual movements, the user can experience a sense of embodiment over the avatar. Recent studies have shown that discrepancies between the movements of the avatar and those of the user can be well tolerated while maintaining high levels of embodiment. The point at which a distortion is perceived (detection threshold) and its impact on the level of embodiment has not been studied in lower limb tasks such as gait. This study aimed to identify a detection threshold of gait asymmetry by unilaterally manipulating the step length of a self-avatar, and the effect of this detection on perceived embodiment. A real-time step length distortion model was developed, and a detection threshold between actual and avatar’s gait movement was assessed on thirty healthy participants. The step length was manipulated to introduce gait asymmetry (ascending condition) or start from a large asymmetry that was gradually decreased (descending). The results showed that, on average, the avatar’s step length could be increased by up to 12% before the participants detected the distortion. Furthermore, in the descending condition, they detected increases that were above 9%. The point of detection had no effect on the sense of embodiment as participants still reported being embodied in their avatars, even when they consciously detected the step length distortion. The sense of embodiment was closely correlated with the level of distortion; as distortion increased, embodiment decreased, and vice versa. For a given distortion level, embodiment was similar whether in the ascending or descending condition. This suggests that embodiment can be achieved even when the avatar’s spatial alignment initially differs from the participants’, provided that alignment is gradually restored. These results provide valuable insights into participants’ ability to tolerate movement discrepancies in embodied avatar experiences during gait in virtual environments, with potential applications in motor training and gait rehabilitation. [ABSTRACT FROM AUTHOR]

The present investigation reports on the experimental and numerical study of weld sequence optimization in filet-welded aluminum alloy 6061-T6 structures during the gas metal arc (GMA) welding process. A 3D thermal–mechanical finite element (FE) procedure was considered for predicting thermal fields and deformations. Transient temperature distribution and distortions were simulated for different welding sequences using the thermal elasto-plastic approach. In the FE model, the same bead geometry as in the T-joint weld was considered for accuracy. Temperature-dependent material properties, latent heat effect, heat loss due to conduction, radiation and convection, and Goldak's volumetric heat source are also employed in the model. Further, the simulation results obtained from finite element FE modeling software SimufactTM were compared and validated against the experimental results. The experimental results show good agreement with numerical analysis with a maximum error of 10% and 12% for temperature and distortion results, respectively. It was also found that in five different welding sequences, the maximum angular distortion reduction of 16.06% was observed in the welding away from the center (case 5). Based on the results, an optimized welding sequence case 5 is the most suitable scheme for reducing angular distortions in AA T-joint filet welds. [ABSTRACT FROM AUTHOR]

We consider a setting with agents that have preferences over alternatives and are partitioned into disjoint districts. The goal is to choose one alternative as the winner using a mechanism which first decides a representative alternative for each district based on a local election with the agents therein as participants, and then chooses one of the district representatives as the winner. Previous work showed bounds on the distortion of a specific class of deterministic plurality-based mechanisms depending on the available information about the preferences of the agents in the districts. In this paper, we first consider the whole class of deterministic mechanisms and show asymptotically tight bounds on their distortion. We then initiate the study of the distortion of randomized mechanisms in distributed voting and show bounds based on several informational assumptions, which in many cases turn out to be tight. Finally, we also experimentally compare the distortion of many different mechanisms of interest using synthetic and real-world data. [ABSTRACT FROM AUTHOR]

Soil dielectric sensors have been widely used to obtain real-time soil moisture data, which are important for water resource management. However, soluble salts in the soil significantly affect the accuracy of these sensor measurements. Therefore, it is crucial to select suitable soil dielectric sensors for soil moisture measurements at different salinity levels. Eight mainstream sensors (EC-5, 5TE, Teros12, Hydra-probe II, TDR315L, TDR315H, TDR305H, and CS655) were selected and tested at four different soil salinity levels (EC1:5 = 3.0, 1.5, 1.0, and 0.75 dS·m−1). The measured values using the factory calibration formulas were compared at six soil moisture levels. The results showed that the measured soil moisture values from various sensors exhibited varying degrees of overestimation, which increased with increasing salinity. Only EC-5 did not exhibit distortion at high-salinity levels, with the measured values showing a good linear trend compared to the standard values. Mutational distortion of the measured apparent dielectric permittivity occurred in TDR315L, TDR315H, Hydra-probe II, and 5TE at EC1:5 = 3.0 dS·m−1. Insensitive distortion of the measured apparent dielectric permittivity occurred in Teros12 and TDR305H at EC1:5 = 3.0 dS·m−1 as well as in Teros12, TDR305H, 5TE and Hydra-probe II at EC1:5 = 1.5 dS·m−1. All tested sensors performed reasonably well at EC1:5 ≤ 1.0 dS·m−1. Seven sensors (excluding CS655) were calibrated within the distortion threshold. The soil moisture accuracy using the calibrated formulas could reach ±0.02 cm3·cm−3. At EC1:5 ≤ 1.0 dS·m−1, most sensors in this study could be applied with the factory calibration formulas. TDR series, EC-5, 5TE and Teros12 were recommended after calibration for EC1:5 > 1.0 dS·m−1. For extremely high soil salinity levels, the TDR series and EC-5 may be the best choices. [ABSTRACT FROM AUTHOR]

In scale-down tests of ship structures subjected to a blast load, the accuracy of the predicted response of a prototype is affected by the material substitution and geometric distortion between a scaled model and a full-size structure; this is known as incomplete similarity. To obtain a more accurate response from a prototype during small-size tests, a corrected method for scaling the response of thin plates and stiffened plates under a blast load was derived. In addition, based on numerical simulations of explosion responses by employing the elastic–plastic model and the Johnson–Cook constitutive model, it was found that using the average yield stress derived from the equivalent plastic strain energy in the ideal elastic–plastic model can obtain consistent structural responses. Moreover, a method for calculating the distortion factor caused by the yield stress of different materials was proposed. Furthermore, it was demonstrated that the average effective plastic strain between the prototype and the corrected model is equal, and based on this, a similarity prediction method was established to correct the distortions caused by yield stress and the thickness of blast loaded plates. The results indicate that the proposed correction method can compensate for the differences caused by distorted factors of yield stress and thickness, with the maximum error in the structure's peak displacement being less than 3%. [ABSTRACT FROM AUTHOR]

Laser Hot Wire (LHW) Directed Energy Deposition (DED) Additive Manufacturing (AM) processes are capable of manufacturing parts with a high deposition rate. There is a growing research interest in replacing large cast Nickel Aluminum Bronze (NAB) components using LHW DED processes for maritime applications. Understanding thermomechanical behavior during LHW DED of NAB is a critical step towards the production of high-quality NAB parts with desired performance and properties. In this paper, finite element simulations are first used to predict the thermomechanical time histories during LHW DED of NAB test coupons with an increasing geometric complexity, including single-layer and multilayer depositions. Simulation results are experimentally validated through in situ measurements of temperatures at multiple locations in the substrate as well as displacement at the free end of the substrate during and immediately following the deposition process. The results in this paper demonstrate that the finite element predictions have good agreement with the experimental measurements of both temperature and distortion history. The maximum prediction error for temperature is 5% for single-layer samples and 6% for multilayer samples, while the distortion prediction error is about 12% for single-layer samples and less than 4% for multilayer samples. In addition, this study shows the effectiveness of including a stress relaxation temperature at 500 °C during FE modeling to allow for better prediction of the low cross-layer accumulation of distortion in multilayer deposition of NAB. [ABSTRACT FROM AUTHOR]

The unsupervised enhancement technology for underwater images is mainly oriented towards specific distortion factors and exhibits limited adaptability towards various underwater distorted images. The content attribute(structure) of the image will migrate and change with the style attribute(appearance), resulting in an uncontrolled enhancement effect and affecting the stability and accuracy of subsequent environmental perception and processing. To address this issue, an unsupervised controllable enhancement method of underwater images based on multi-domain attribute representation disentanglement(MARD) was proposed in the paper. First, a framework of multi-domain unified representation disentanglement cycle-consistent adversarial translations was designed, thereby enhancing the algorithm’s adaptability to multiple distortion factors. Subsequently, a dual-encoding and conditional decoding network structure was constructed. Finally, a series of losses for MARD was designed to enhance the independence and controllability of quality, content, style, and other attribute representations. Experimental results demonstrate that the proposed algorithm not only eliminates various distortions such as color aberration, blur, noise, and low illumination in underwater images but also quantify the image style codes by linear interpolation for controllable enhancement of underwater images.

The increasing role of high-precision weapons (HPW) in the weapons system of foreign countries means the need to improve the means and methods of complex camouflage of troops, an integral part of which is the use of aerosols. The article is a continuation of research on the assessment of the effectiveness of camouflage of objects with aerosols based on the calculation of the proportion of space hidden (screened) by aerosol particles for the free passage of visible light carrying information about the object and the surrounding background. According to the authors, when recognizing an object through a moving aerosol structure, in addition to the proportion of free space, its structure also influences camouflage, namely the size of the cells from minimum to maximum, which together make up this space.The purpose of the work is to assess a new camouflage factor, that is, the nature of the distribution in an aerosol cloud of the structure of free space depending on the density of the aerosol (integral concentration, g/m2) along the line of sight (observation) and the size of its particles, μm.Research method. Theoretical modeling of the passage of light through an aerosol cloud using a PC.Discussion. The calculations performed on a PC show the existence of a probabilistic distribution of free space cells by their size (size and area), which make up the total value of free space, previously estimated by us as a whole. The unevenness of the cell size is due to turbulence of the surface air layer with aerosol distributed in it. The calculations showed that the cell size is extremely small: no more than 100 μm.Conclusion. The small size of the cells and their dynamic distribution in space during the propagation of the aerosol cloud can be considered in mathematical terms as an additional term of the probability of camouflage, due to the non-perception (non-distinction) of the camouflaged objects. The term is new and, perhaps, requires clarification, both theoretically and during experiments in an aerosol chamber. But its meaning lies in the existence of a minimum limiting solid angle of difference (perception) by the human eye of pixels of visible information through the moving structure of an aerosol cloud at a certain observation range.

The present work presents a series of experimental distortion analysis of square shipbuilding steel plates with an attached stiffener. Two approved fillet welding configurations are applied to attach the stiffener using shielded metal arc welding at Port Said Shipyard. The specimens are welded using continuous and intermittent chain fillet welding for variant plating thicknesses with constant stiffener geometrical configurations, where two welding passes are applied. The effect of different fillet welding geometry on the induced initial imperfection amplitudes for different base plating thicknesses is investigated. The imperfection shapes are tracked, and the amplitudes are measured during and after the welding process. The imperfection amplitudes for each plating thickness and welding geometry are analyzed considering both preheat after the first pass and heat relief. Several relationships considering the welding time and the amount consumed electrodes are performed for different plating thicknesses and welding geometries. A comparison between existing empirical formulations and the observed results is performed in the form of plate slenderness, showing reasonable conclusions.

Due to the tool-less fabrication of parts and the high degree of geometric design freedom, additive manufacturing is experiencing increasing relevance for various industrial applications. In particular, the powder bed fusion of metals using a laser beam (PBF-LB/M) process allows for the metal-based manufacturing of complex parts with high mechanical properties. However, residual stresses form during PBF-LB/M due to high thermal gradients and a non-uniform cooling. These lead to a distortion of the parts, which reduces the dimensional accuracy and increases the amount of post-processing necessary to meet the defined requirements. To predict the resulting residual stress state and distortion prior to the actual PBF-LB/M process, this paper presents the finite-element-based simulation tool AscentAM with its core module and several sub-modules. The tool is based on open-source programs and utilizes a sequentially coupled thermo-mechanical simulation, in which the significant influences of the manufacturing process are considered by their physical relations. The simulation entirely emulates the PBF-LB/M process chain including the heat treatment. In addition, algorithms for the part pre-deformation and the export of a machine-specific file format were implemented. The simulation results were verified, and an experimental validation was performed for two benchmark geometries with regard to their distortion. The application of the optimization sub-module significantly minimized the form deviation from the nominal geometry. A high level of accuracy was observed for the prediction of the distortion at different manufacturing states. The process simulation provides an important contribution to the first-time-right manufacturing of parts fabricated by the PBF-LB/M process.

This review covers 17 Pt(II) complexes of the compositions: Pt(ƞ3-N1C1N2)(PL), Pt(ƞ3-S1C1S2)(PL), Pt(ƞ3-S1B1S2)(PL), Pt(ƞ3-S1S2O1)(PL), Pt(ƞ3-O1N1C1)(PL), Pt(ƞ3-O1N1S1)(PL) and Pt(ƞ3-C1N1S1)(PL). These complexes crystallized in three crystal classes: monoclinic (8 examples), triclinic (8 examples) and orthorhombic (1 example). The heterotridentate ligands creates 5 + 5-membered metallocyclic rings (most common) and 5 + 6-membered. The heterotridentate ligands with monodentate P ligands build up a distorted square-planar geometry about Pt(II) atoms. The Pt–L and L–Pt–L were analyzed. The τ4 parameter which indicate a degree of distortion growing in the sentence: 0.057 Pt(ƞ3-O1N1S1)(PL) < 0.066 Pt(ƞ3-S1C1S2)(PL) < 0.149 Pt(ƞ3-S1S2O1)(PL) < 0.158 Pt(ƞ3-O1N1C1)(PL) < 0.160 Pt(ƞ3-C1N1S1)(PL) < 0.162 Pt(ƞ3-S1B1S2)(PL) < 0.165 Pt(ƞ3-N1C1N2)(PL). [ABSTRACT FROM AUTHOR]

Due to the tool-less fabrication of parts and the high degree of geometric design freedom, additive manufacturing is experiencing increasing relevance for various industrial applications. In particular, the powder bed fusion of metals using a laser beam (PBF-LB/M) process allows for the metal-based manufacturing of complex parts with high mechanical properties. However, residual stresses form during PBF-LB/M due to high thermal gradients and a non-uniform cooling. These lead to a distortion of the parts, which reduces the dimensional accuracy and increases the amount of post-processing necessary to meet the defined requirements. To predict the resulting residual stress state and distortion prior to the actual PBF-LB/M process, this paper presents the finite-element-based simulation tool AscentAM with its core module and several sub-modules. The tool is based on open-source programs and utilizes a sequentially coupled thermo-mechanical simulation, in which the significant influences of the manufacturing process are considered by their physical relations. The simulation entirely emulates the PBF-LB/M process chain including the heat treatment. In addition, algorithms for the part pre-deformation and the export of a machine-specific file format were implemented. The simulation results were verified, and an experimental validation was performed for two benchmark geometries with regard to their distortion. The application of the optimization sub-module significantly minimized the form deviation from the nominal geometry. A high level of accuracy was observed for the prediction of the distortion at different manufacturing states. The process simulation provides an important contribution to the first-time-right manufacturing of parts fabricated by the PBF-LB/M process. [ABSTRACT FROM AUTHOR]

Despite the several significant features of the S2C/OCC systems that were mentioned before, the system implementation is difficult due to several issues such as different sources of noise that degrade the performance of the S2C/OCC communication system. This system is affected by several noise sources which include optical noise such as normal light-emitting and light ambient sources, whereas electrical noise comes from electronic components. Moreover, interference is another problem for the S2C/OCC systems, as would other imperfections. The OCC system for multiple cell transmitters and imaging cell receivers supports the data detection techniques, including the decoding and sampling techniques that are tested experimentally under different conditions. The impact of the S2C system impairments such as the ambient light, blur phenomenon, and perspective distortion are tested experimentally. As mentioned previously, the proposed combination of RS-FEC with CC-FEC is an appropriate technique for effective consecutive data transmission, particularly supportive of the S2C/OCC system. [ABSTRACT FROM AUTHOR]

Millimeter-wave (mmWave) antenna arrays are pivotal components in modern wireless communication systems, offering high data rates and improved spectrum efficiency. However, the performance of mmWave antenna arrays can be significantly affected by structural distortions, such as mechanical deformations and environmental conditions, which may lead to deviations in beamforming characteristics and radiation patterns. In this paper, we present a comprehensive sensitivity study of mmWave antenna arrays to structural distortion, employing a coupled structural–electromagnetic statistical concept. The proposed model integrates structural analysis techniques with electromagnetic simulations to assess the impact of structural distortions on the performance of mmWave antenna arrays. In addition, the model incorporates random element positioning, making it easy to analyze radiation pattern sensitivity to structural deformation. Demonstrating the applicability of the model, a 10 × 10 microstrip patch antenna array is designed to assess the performance of the model with a random position error and saddle shape distortion. The results of the model are then compared against the acceptable results from the HFSS software (version 13.0), where a good agreement is observed between the two results. The results show the gain variation and sidelobe level under various degrees of distortion and random errors, respectively. These results provide a guide for design, deployment, and optimization of mmWave communication networks in real-world environments. In addition, the model provides valuable insights into the trade-offs between antenna performance, structural integrity, and system reliability, paving the way for more efficient and dependable mmWave communication systems in the era of 5G and beyond. [ABSTRACT FROM AUTHOR]

Objective: Distances and angles measured from long-leg radiographs (LLR) are important for surgical decision-making. However, projectional radiography suffers from distortion, potentially generating differences between measurement and true anatomical dimension. These phenomena are not uniform between conventional radiography (CR) digital radiography (DR) and fan-beam technology (EOS). We aimed to identify differences between these modalities in an experimental setup. Materials and methods: A hemiskeleton was stabilized using an external fixator in neutral, valgus and varus knee alignment. Ten images were acquired for each alignment and each modality: one CR setup, two different DR systems, and an EOS. A total of 1680 measurements were acquired and analyzed. Results: We observed great differences for dimensions and angles between the 4 modalities. Femoral head diameter measurements varied in the range of > 5 mm depending on the modality, with EOS being the closest to the true anatomical dimension. With functional leg length, a difference of 8.7% was observed between CR and EOS and with the EOS system being precise in the vertical dimension on physical-technical grounds, this demonstrates significant projectional magnification with CR-LLR. The horizontal distance between the medial malleoli varied by 20 mm between CR and DR, equating to 21% of the mean. Conclusions: Projectional distortion resulting in variations approaching 21% of the mean indicate, that our confidence on measurements from standing LLR may not be justified. It appears likely that among the tested equipment, EOS-generated images are closest to the true anatomical situation most of the time. [ABSTRACT FROM AUTHOR]

A laser welding with wire filler feeding was developed to replace traditional arc welding process for joining aluminium alloy railcar body components. A three-dimensional (3D) thermo-elastic-plastic finite element (FE) model was applied to compute the plastic strains of weld zone in a downsized aluminium alloy plate with butt-joint, T-joint and fillet-joint configurations, respectively, combined with corresponding experimental validations. The achieved plastic strains at the weld zone were then input as inherent strain loadings into elastic structural FE model of fully sized aluminium alloy railcar body components to predict the welding induced distortion with the experimentally measured out-of-plane distortions. The experimentally validated FE model was then further applied for optimizing the inverse pre-deformation of plates to counteract the welding induced deformation, finally to mitigate the welding distortion issues. [ABSTRACT FROM AUTHOR]

Wire arc additive manufacturing (WAAM) is a proven technology in metal additive manufacturing (AM), which can produce large-scale components at a faster production rate. Since WAAM adopts a welding heat source for metal deposition over the substrate, severe thermal gradients develop around the deposition resulting in residual stresses in the substrate, thereby distorting the substrate. In the case of area filling in metal AM processes, heat accumulation is progressive and a large amount of heat is accumulated at the end of the deposition. This leads to thermal imbalance over the substrate and an increase in the shrinkage forces during cooling, thereby causing higher distortion. This paper mainly deals with the mitigation of distortion in the substrate for area filling caused by the thermal imbalance over the substrate. This thermal imbalance is addressed in two ways; a) by selectively insulating and b) by selectively conducting the heat from the substrate. Simulations are conducted to study the thermal evolution during area filling and counterbalance the heat by insulating and conducting the substrate selectively during experimental deposition. A comparative assessment of distortions of the full conduction, full insulation, selective conduction and selective insulation cases is detailed. The selective thermal management strategy showed lower thermal imbalance over the substrate resulting in lower distortion. [ABSTRACT FROM AUTHOR]

Gas tungsten arc welding employs the Taguchi method to reduce thermal distortions in the welded structures which are used in many industrial applications including marine, offshore, petrochemical and automobile sectors. Using a vernier height gauge, we calculated the amount of transverse deformation caused by the GTA welding procedure. An L8 orthogonal array is used with the welding current, weld root gap, gas flow rate, and welding speed as the critical parameters for four noise sources. Finding the average, standard deviation, and solution effectiveness are the three main goals of the Analysis of Variance. According to the results of these analyses, weld distortion may be significantly influenced by weld parameters. Lower thermal strain values were observed when higher welding current and gas flow rate is maintained. The optimal degree of distortion is believed to be two degrees. Controlling welding speed and root gap resulted in a 37% contribution with a 90% confidence on distortion, indicating that these parameters are crucial to producing a reliable design. [ABSTRACT FROM AUTHOR]

The current study aims to investigate the effect of the hybrid thermal tensioning technique transient thermal tensioning and trailing intensive cooling (TTT–TIC) on residual stresses and distortion of titanium Ti-5Al-2.5Sn and stainless steel 304 gas tungsten arc welded (GTAW) joints using Nb–Cu composite filler. The two preheating oxyacetylene torches are used for in-situ heating at TTT condition whereas compressed CO2 has been employed for in-situ trailing cooling of weld at TIC condition. The residual stresses and distortion have been evaluated at the distance between preheating torches (DA) in the case of TTT, the distance between the cooling source and the welding torch (DB) in case of TIC, and optimal distances DA and DB in case of hybrid TTT–TIC condition. The minimum values of tensile residual stresses and distortion of 98 MPa and 0.904 mmm on SS side, and 84 MPa and 0.425 mm on Ti side have been obtained at TTT–TIC condition. A significant percentage reduction in tensile residual stresses has been attained at novel TTT–TIC of 60% on SS side, and 63.48% on Ti side than conventional GTAW, 14.7% on SS side and 18.4% on Ti side than TIC condition, 52.20% on SS side and 56.02% on Ti side than TTT condition at hole depth of 0.3 mm on both plates. In the case of TTT–TIC, a percentage reduction in transverse distortion of 43.61, 24.81, and 32.09% have been achieved over the conventional GTAW, TIC, and TTT conditions respectively. In case of longitudinal distortion, the 57.07% reduction in distortion on Ti and 45.87% on SS side under the TTT–TIC method have been achieved. [ABSTRACT FROM AUTHOR]

Geosynthetic clay liner (GCL) is commonly used in cover system of engineered landfill to limit migration of gases and infiltration of water. In engineered landfill, gas transfer occurs by advection and diffusion, which may take place at different time frames or simultaneously depending on placement conditions. Hence, efficacy of GCL as a gas barrier under advection and diffusion needs to be assessed at various geoenvironmental settings. In the present study, the gas flow response of GCL under advection and diffusion were evaluated at various apparent degrees of saturation, distortion levels, hydrating fluids, and wet-dry cycles using custom-designed test apparatus. Gas permeability and gas diffusion coefficient of GCL were found to decrease by four and three orders of magnitude respectively with an increase in apparent degree of saturation from 7% to 80%. Gas permeability and gas diffusion coefficient were increased with an increase in distortion levels. With an increase in wet-dry cycles 1 to 5, gas permeability and gas diffusion of GCL were increased marginally when hydrated with distilled water while increased by one order of magnitude for hydrated with 0.0125 M CaCl2 solution. The obtained results were compared with published results and found to be in good agreement. [ABSTRACT FROM AUTHOR]

Wire arc additive manufacturing (WAAM) is a direct energy deposition additive manufacturing technique. In this, the system comprises numerous variables that make a difference to the shape, morphology and mechanical behaviours of the WAAM processed Ti–6Al–4 V bead. The travel speed, wire feed speed, heat input and shielding gas flow rate are the most influential variables among them that can be found in the literature. WAAM is a material deposition technique that uses multiple thermal cycles or repeated heat treatments during the entire process. As a consequence of which, an uneven dissemination of microstructure, anisotropy in mechanical properties, high residual stresses and distortion of parts are some of the challenges during the implementation of WAAM on Ti–6Al–4 V. With the ongoing need to reduce the cost of manufacturing Ti–6Al–4 V parts, WAAM system should overcome these challenges to get the good part dimensions and qualities of the manufactured Ti–6Al–4V alloy components. This review presents an overview of the current and common issues that the WAAM system encounters while fabricating Ti–6Al–4 V parts. In addition, an attempt is made to discuss the existing possible solutions to these issues. The review begins by introducing the effect of different process parameters like travel speed, wire feed speed, heat input and shielding gas flow rate on the geometry of the deposited materials. In addition, the morphology and mechanical properties of the WAAM-manufactured Ti-6Al-4 V alloy components have been discussed, followed by the influence of different post-thermal treatments which try to optimise the microstructure and enhance the mechanical properties of the deposited materials. Moreover, distortions and residual stresses which are associated with the WAAM systems and the methods to minimise them are discussed. [ABSTRACT FROM AUTHOR]

Objectives: In April 2020, standard two-dimensional (2D) full-field digital mammograms were replaced with digital breast tomosynthesis (DBT) and synthesised 2D views for symptomatic breast clinics. This study aimed to evaluate the positive predictive value (PPV) for malignancy in DBT-detected Architectural distortion (AD). Methods: All mammogram reports with the word "distortion" were assessed between April 2020 and October 2022. There were 458 mammograms with the word "distortion." After excluding mammograms with no distortion (n = 128), post-surgical distortion (n = 173), distortion with mass (n = 33), and unchanged distortion (n = 14), there were 111 patients with pure distortion. Correlation with histopathology was obtained where possible. All patients were followed for a minimum of 2 years. Results: Forty-two out of 111 patients (37.84%) with AD had a normal ultrasound (US) and were discharged. Fifty-five (49.5%) patients had sonographic correlation corresponding to the distortion, leading to US-guided biopsy. Thirteen (23.6%) had tomosynthesis-guided biopsy, and one had a skin biopsy. The PPV for malignancy was 42.34%. Malignancy diagnoses were higher with US-guided biopsies than tomosynthesis-guided biopsies, 78.1% and 30%, respectively. Conclusion: With a total malignancy rate of 42.34%, DBT-detected AD has a high enough PPV for malignancy to justify selective tissue sampling if a sonographic correlate is present or with suspicious mammograms. The chances of malignancy are higher when a sonographic correlate corresponding to AD is present. Advances in knowledge: AD on DBT/synthesized mammograms views in symptomatic breast clinic patients justifies selective sampling. [ABSTRACT FROM AUTHOR]

Sanjay Leela Bhansali's Padmaavat, a Bollywood period drama, engendered a variety of conversations about identity, history, etc. in India. This article examines the ways in which the reception of the film performatively produced a genre of history in the Indian public sphere. Such performative productions of history as a genre runs counter to the prevalent notion of history as pre-given with concrete referents and past incidents. The allegation of "distortion" (of "history") is mobilized as a psychoanalytic resource to demonstrate this point. In the process, I note how the existing approaches to Hindu nationalism are inadequate in their critical clarity. [ABSTRACT FROM AUTHOR]

The residual stress creates deleterious effects on joint properties of dissimilar welding due to differential thermophysical properties and mechanical constraints of dissimilar thickness. Accounting of solid-state phase transformation (SSPT) through the understanding of solidification behavior enhances the prediction accuracy of residual stress. The characterization of microstructural features improves the fundamental understanding of the residual stress evaluation. An attempt is made to comprehend the dependence of heat input on phase transformation and its effect on the generation of compressive residual stress in dissimilar welding. Three distinct heat inputs of 52, 63, and 77 J/mm are considered in micro-plasma arc welding (µ-PAW) of SS316L and SS310 with thicknesses of 800 µm and 600 µm, respectively. The measurement of residual stress is performed using the X-ray diffraction (XRD) method. The variation of δferrite from 11.2 to 7.9% is analogous to the variation of average δferrite lath size from 412 to 1040 nm, where inter-dendritic spacing varies from ~ 10 µm to ~ 20 µm. The solidification mode is identified as ferritic-austenitic (FA), which results in the formation of skeletal and lathy δferrite structures. Electron Backscatter Diffraction (EBSD) results show an increase in heat input leads to an increase in low-angle grain boundaries that results in a rise in the residual stress value. The phase fraction and residual stresses are computed employing a finite element (FE) based thermal-metallurgical-mechanical (TMM) model including the effect of SSPT. The reasonable agreement between the computed and experimental measurements with a maximum error of ~ 8.5% in weld size, ~ 7.5% in peak temperature, ~ 16% in retained δferrite, ~ 17% in residual stress, and ~ 5% in distortion demonstrates the reliability of the developed model. A lower level of heat input (52 J/mm) allows the formation of a high amount of δferrite, which generates comparatively more compressive stress as a disparity in thermal expansion coefficient α Ni ∼ 1.6 α Cr aids in the reduction of residual stress. [ABSTRACT FROM AUTHOR]

This study explores the numerical analysis of effective stress and distortion (dimensional variations) in bulk deposited structures of Inconel 625 alloy with seven different deposition strategies using wire arc additive manufacturing (WAAM) process. Due to the challenges in detecting in-situ stress changes during bulk deposition, numerical analysis is employed to approximate stress distribution. The goal is to investigate stress and distortion (dimensional variations) in the build direction (BD), longitudinal and transverse directions, and understand their impact on anisotropy and asymmetry. The findings reveal distinct patterns in effective stress, with initial decrease in bottom, followed by a gradual increase at the middle and rapid increase thereafter, regardless of deposition strategies. Parallel and contour deposition strategies exhibit lower effective stress compared to spiral strategies. Distortion (dimensional variations) along the BD increases with height, and parallel strategies result in higher distortion. The parallel strategies show increasing distortion from one edge to the other, while spiral and contour strategies lead to high distortion at the center. The parallel and contour deposition strategies exhibit higher compressive stress at the bottom and middle compared to the spiral strategies. Anisotropy analysis indicates higher stress anisotropy in parallel and contour patterns, but lower distortion anisotropy compared to spiral patterns. Empirical equations are developed to understand the relationship between stress, distortion (dimensional variations) and hardness. The study suggests that higher effective stress can adversely affect material yielding behavior. This study undertakes a comparison between FEA and analytical model which reveals a close alignment in the residual stress distributions in the build direction. [Display omitted] ● Residual stress and distortion behaviour of seven deposition strategies are numerically analyzed. ● Residual stress in bulk deposition decreases at bottom, increases in middle and top. ● Parallel strategies result in lower horizontal stress and distortion compared to spiral and contour. ● The compressive stress in the parallel and contour strategies is significantly higher than that the spiral. ● Parallel and contour strategies exhibit greater stress anisotropy but lower distortion anisotropy. [ABSTRACT FROM AUTHOR]

Aeronautical parts located in hot engine zones may be made of Inconel 718: a material known for its poor machinability. This results during machining in high levels of thermo-mechanical loading, located in machined subsurface. This loading may affect the surface integrity and residual stresses may lead to part distortion in some cases. Certain geometric features, such as scalloped housings or thin walls on turbomachinery, are obtained by flank milling. This study demonstrates that residual stresses during Inconel 718 flank milling can lead to part distortion and proposes a methodology to characterize involved phenomena. Instrumented machining of beam-type workpiece allows to quantify these geometric deviations and the stresses introduced into the subsurface by the milling process. The specimens are characterized before and after the finishing operation: distortion is assessed by measuring the straightness of the specimen and its stress state using the XRD method. The studied parameters are the cutting conditions, such as cutting speed, feed and flank wear. It is therefore possible to conclude which parameters have an impact on specimen distortion and on the stress level in the work material, then the approach to use perform the reduction of workpiece distortion. [ABSTRACT FROM AUTHOR]

In this paper, we give an estimate of the upper bound of the inner radius for a complete Finsler measure space (M , F , d μ) of weighted Ricci curvature bounded from below, in terms of the d μ -mean curvature bound of the boundary. We also prove the rigidity result that when the boundary is compact, the upper bound is achieved if and only if M is isometric to a forward Finsler geodesic ball of vanishing radical flag curvature. [ABSTRACT FROM AUTHOR]

T he interferometric Shuttle Radar Topography Mission (SRTM) satellite's digital elevation model (DEM) is an important tool for studying topographic features on a medium-spacing scale. Data were collected and processed using the satellite's orbital and navigation parameters with selected global GPS stations for verification. Distortion may be expressed by surveying measurements, such as position, distance, area, and shape. This study focuses on this distortion and proposes a new registration method to reduce its effect. Because of generality, the purpose shapes were excluded from this study. The proposed registration method depends on precise GPS control points that act as the ground truth for describing the considered surveying measurements. The processing was carried out using deep artificial neural networks (DANN) to produce a new registered DEM. A comparison was made between the original DEM and the new one, focusing on the selected surveying measurements. Another comparison was made between the GPS coordinates and SRTM polynomials to determine the potential of the proposed system. Some statistical investigations were applied to determine the level of significance of the distortion in each surveying measurement. The study shows that the distortion is highly significant; therefore, the proposed registration method is recommended to fix the distortion. An important finding is the enhancement in local coordinates scope. [ABSTRACT FROM AUTHOR]

The main purpose of this paper, is to introduce a new subclass of analytic functions involving Polylogarithm functions and obtain coefficient inequalities, distortion properties, extreme points, radii of starlikeness and convexity, Hadamard product, and convolution and integral operators for the class. [ABSTRACT FROM AUTHOR]

The problem of autism is wide spreading nowadays all over the world. The paper has tackled one of the main problems of autistic children that is poor pronunciation. This paper tries to figure out the reasons behind the pronunciation problems of autistic children and how to deal with such problems. The main objectives of the study are to find out the meaning of autism in general, stating the main symptoms of autistic children, specifying the problem of articulation and proposing the suitable ways of treatment to improve the autistic children’s articulation. The data of the study consists of a recorded speech of nine students in the Hama’em Al Salam Centre for the treatment of autistic children. A form has been designed for this purpose to identify the specific articulation problems of those autistic children. The data have been recorded along one year of observation. After analyzing the data, the researcher has reached a conclusion that the reasons behind those problems in articulation are psychological ones which make the child does not want to exert extra effort to pronounce the words correctly, this is why they apply certain processes to make their speech less effortful such as deletion, substitution, assimilation or distortion. The paper proposes some solution to solve this problem of autistic children in order to make their speech as normal as possible. Key words: Autism, articulation, distortion, substitution, deletion, defects.

Storage tanks are essential components in various industries, particularly in power generation, where they are utilized for oil storage. The stress developed within these tanks due to internal pressure significantly influences their useful life and buckling behaviour during service. In this study, finite element analysis is employed to investigate the stress development and buckling behaviour of a fixed, closed-rooftop cylindrical oil storage tank used in a power generation company when filled and half-filled with diesel. The stress analysis results reveal that the stress developed in the tanks under both operating conditions considered is below the yield stress of the tank material. This suggests that, under these conditions, the tank is poised to have an infinite useful life, as long as it is not subjected to external pressure. The eigenvalue buckling analysis indicates that the during buckling of the storage tank the maximum displacement in the filled tank will occur in the middle if the bifurcation point is reached while the maximum displacement in the half-filled tank varies depending on the mode being considered. Based on the finite element analysis, it is concluded that the oil storage tank, under the specified conditions, experiences stresses below the yield point, thus, ensuring an extended useful life.

In immersive VR, a self-avatar that replicates the user’s movements and is viewed from a first-person perspective can substitute the real body. If the avatar’s movements are sufficiently synchronized with the user’s actual movements, the user can experience a sense of embodiment over the avatar. Recent studies have shown that discrepancies between the movements of the avatar and those of the user can be well tolerated while maintaining high levels of embodiment. The point at which a distortion is perceived (detection threshold) and its impact on the level of embodiment has not been studied in lower limb tasks such as gait. This study aimed to identify a detection threshold of gait asymmetry by unilaterally manipulating the step length of a self-avatar, and the effect of this detection on perceived embodiment. A real-time step length distortion model was developed, and a detection threshold between actual and avatar’s gait movement was assessed on thirty healthy participants. The step length was manipulated to introduce gait asymmetry (ascending condition) or start from a large asymmetry that was gradually decreased (descending). The results showed that, on average, the avatar’s step length could be increased by up to 12% before the participants detected the distortion. Furthermore, in the descending condition, they detected increases that were above 9%. The point of detection had no effect on the sense of embodiment as participants still reported being embodied in their avatars, even when they consciously detected the step length distortion. The sense of embodiment was closely correlated with the level of distortion; as distortion increased, embodiment decreased, and vice versa. For a given distortion level, embodiment was similar whether in the ascending or descending condition. This suggests that embodiment can be achieved even when the avatar’s spatial alignment initially differs from the participants’, provided that alignment is gradually restored. These results provide valuable insights into participants’ ability to tolerate movement discrepancies in embodied avatar experiences during gait in virtual environments, with potential applications in motor training and gait rehabilitation.