Static Restoration Research Articles

Smartwatch In-Air Signature Time Sequence Three-Dimensional Static Restoration Classification Based on Multiple Convolutional Neural Networks

In-air signatures are promising applications that have been investigated extensively in the past decades; an in-air signature involves gathering datasets through portable devices, such as smartwatches. During the signing process, individuals wear smartwatches on their wrists and sign their names in the air. The dataset we used in this study collected in-air signatures from 22 participants, resulting in a total of 440 smartwatch in-air signature signals. The dynamic time warping (DTW) algorithm was applied to verify the usability of the dataset. This paper analyzes and compares the performances of multiple convolutional neural networks (CNN) and the transformer using median-sized smartwatch in-air signatures. For the four CNN models, the in-air digital signature data were first transformed into visible three-dimensional static signatures. For the transformer, the nine-dimensional in-air signature signals were concatenated and downsampled to the desired length and then fed into the transformer for time sequence signal multi-classification. The performance of each model on the smartwatch in-air signature dataset was thoroughly tested with respect to 10 optimizers and different learning rates. The best testing performance score in our experiment was 99.8514% with ResNet by using the Adagrad optimizer under a 1×10−4 learning rate.

The role of texture and restoration mechanisms in defining the tension-compression asymmetry behavior of aged NiTi alloys fabricated by laser powder bed fusion

Tension-compression asymmetry is an inherent property of superelastic NiTi alloys linked to the microstructural evolutions and the stress induced martensite transformation during different deformation modes. Deep understanding of NiTi's asymmetry, a topic that is often overlooked in additive manufacturing, is imperative in designing functional parts that experience multiple deformation modes. Accordingly, in this paper, the asymmetry parameters, namely the critical stress for martensite transformation, transformation strain, and strain recoverability were measured for an aged material with optimum superelasticity, which was fabricated by two different scanning strategies. The acquired results were correlated to the changes in the developed texture components during laser powder bed fusion and subsequent annealing processes, highlighting the role of dynamic and static restoration mechanisms, respectively. The deviation of texture from <001>||building direction, caused by the occurrence of the restoration mechanisms during fabrication and subsequent aging, was found to be dissimilar for samples fabricated by 67° or 90° rotation angles, effectively impacting the behavior of the material in different deformation modes. For a sample with enhanced superelasticity, aged at 550°C for 6 h, 90° scanning strategy resulted in lower asymmetry and superior superelasticity in compression, while 67° rotations led to highest strain recoverability in tension, but an intensified asymmetrical behavior.

Recrystallization of Cu-30Zn brass during friction stir welding

The recrystallization process of Cu-30Zn brass during friction stir welding (FSW) was investigated. The microstructural evolution in the stirring period and the subsequent normal air-cooling period were separately studied by using stop-action technology, liquid nitrogen cooling, and subsequent heat treatment. During the stirring period, the initial large grains in the base material underwent serious shear deformation at elevated temperatures, resulting in the occurrence of dynamic recrystallization. The weld exhibited ultrafine grains with high dislocation density and a typical {111}<110> shear texture. The grain refinement mechanism was mainly attributed to discontinuous dynamic recrystallization, although several features of continuous dynamic recrystallization could also be found. In the subsequent normal air-cooling period, static restoration occurred and led to dislocation annihilation, selected grain growth, and appearance of annealing twins. The {111}<110> textural component partially changed into a {110}<001> Goss recrystallization texture. From these results, it was deduced that the brass experienced static restoration following dynamic recrystallization during FSW. The static restoration produced by the stirring remarkably influenced the microstructure. This study concluded that if the rapid cooling method is adopted during FSW, the static restoration process can be effectively restrained, and the microstructure of the joint can be significantly improved.

Stress relaxation behaviour of hot deformed austenite in high strength micro-alloyed pipeline steel

The objective of the present study is to investigate the static restoration of CMn(V-Nb-Ti) pipeline steel utilising comparative study of the stress relaxation and micro-alloying precipitates behaviour. The hot compression tests in temperature range of 850°C to 1,000°C, strains of 0.04, 0.1, 0.25, 0.4 and strain rates of 0.1 and 0.5 s−1 have been carried out and the hot flow stress of austenite has been evaluated by stress relaxation technique at annealing time intervals of 0.05 to 1000 s. The results indicate that at the specific deformation temperature of 850°C, the strain induced precipitation starts with the beginning of annealing time which retards recrystallisation. At higher temperatures than 900°C and strains more than 0.25 and 0.4, first recrystallisation occurs and then the plateau appears. The electron backscattering diffraction (EBSD) image also confirms the partial recrystallisation in a sample quenched at the end of the plateau.

Stress relaxation behaviour of hot deformed austenite in high strength micro-alloyed pipeline steel

The objective of the present study is to investigate the static restoration of CMn(V-Nb-Ti) pipeline steel utilising comparative study of the stress relaxation and micro-alloying precipitates behaviour. The hot compression tests in temperature range of 850°C to 1,000°C, strains of 0.04, 0.1, 0.25, 0.4 and strain rates of 0.1 and 0.5 s−1 have been carried out and the hot flow stress of austenite has been evaluated by stress relaxation technique at annealing time intervals of 0.05 to 1000 s. The results indicate that at the specific deformation temperature of 850°C, the strain induced precipitation starts with the beginning of annealing time which retards recrystallisation. At higher temperatures than 900°C and strains more than 0.25 and 0.4, first recrystallisation occurs and then the plateau appears. The electron backscattering diffraction (EBSD) image also confirms the partial recrystallisation in a sample quenched at the end of the plateau.

In-Situ Synchrotron X-Ray Diffraction of Ti-6Al-4V During Thermomechanical Treatment in the Beta Field

This work aims to identify the mechanisms of restoration occurring in Ti-6Al-4V during hot plastic deformation and subsequent heat treatment. The allotropic phase transformation that occurs during cooling distorts the interpretation of the restoration mechanisms taking place at high temperatures. Therefore, analysis of deformed samples by conventional microscopy have led to controversies in the interpretation of the main dynamic restoration mechanism. Additionally, static restoration of the microstructure can occur during slow cooling, modifying the microstructure. These facts were mainly the reasons why discontinuous dynamic recrystallization and/or dynamic recovery has been reported as the main dynamic restoration mechanism for Ti-6Al-4V. In this work, we use in-situ synchrotron X-ray diffraction combined with conventional microscopy to determine the dynamic and static mechanisms of restoration during and after deformation at different strain rates. The results show dynamic recovery as main mechanism of restoration during deformation in the β field, denoted by sub-grain formation and a misorientation dependency of the strain rate. After deformation, static recrystallization, grain growth, and coarsening of the β grains can be observed, especially at strain rates higher than 0.1s−1. It is also demonstrated that the nucleation of new grains can occur within the very first seconds of the isothermal heat treatment.

Determination of static recrystallization and recovery parameters for steel by fitting model to stress relaxation data

A model for static recrystallization by Zurob et al. [1] has been fitted to experimental stress relaxation [2] data obtained on a low-alloyed steel using a Gleeble thermomechanical simulator. The model has been implemented as an algorithm that calculates the stress relaxation as a function of time, including physical descriptions of the recovery and recrystallization processes. The activation energy and volume were used as fitting parameters for recovery, and the activation energy of diffusion and nucleation site density were used as the fitting parameters for recrystallization. The four fitting parameters were determined from the experimental data by applying the Nelder-Mead algorithm within Matlab software. It can be concluded from the preliminary results that Zurob’s model can be successfully fitted to the stress relaxation data in order to illustrate the static restoration characteristics and kinetics in carbon steels using these fitting parameters.

Continuous dynamic recrystallization during hot torsion of an aluminum alloy.

Most commercial aluminum alloys are characterized by dynamic recrystallization at very large deformations in a continuous manner. The present study deals with the characterization and modeling of the evolution of the microstructure of an aluminum wrought alloy at large plastic deformations. Hot torsion tests of the AA6082 aluminum alloy are carried out using the thermomechanical simulator Gleeble®3800 in a wide range of temperatures and strain rates. The use of water quenching immediately after deformation avoids any static restoration during cooling. Microstructural investigations are carried out by means of electron back scattered diffraction using a scanning electron microscope to determine the grain and subgrain structures, as well as the misorientation distributions. In-situ synchrotron radiation tests during hot torsion are used to confirm the continuous dynamic recrystallization (CDRX) by the evidence of the conversion of low angle boundaries (LAGBs) into high-angle boundaries (HAGBs) and the formation of new texture. Experimental investigations show that CDRX starts with the formation of LAGBs at low strains (center of the sample). By subsequent straining (close to the surface of the sample), the accumulation of dislocations at the LAGBs causes an increase in their misorientation until a critical value is reached and LAGBs transforms into HAGBs. The developed model consists of a microstructural model, equation rates and constitutive equations. The microstructure is described by three internal variables. Their rates are evaluated using the Kocks-Mecking model. The modelled and experimental flow stresses show softening due to the consumption of dislocations and the continuous formation of new HAGBs.

Hot torsion behavior of SP-700 near beta titanium alloy in single and dual phase regions

Abstract Hot deformation behavior of the SP-700 alloy is studied through continuous and interrupted hot torsion testing carried out at 850 and 1 000 °C at different pass-strains and inter-pass times. The flow curves of SP-700 alloy showed the discontinuous yield stress, which is followed by the steady state region. The dominant mechanism of softening in hot deformation at 1 000 °C was dynamic recrystallization (DRX), whereas at 850 °C serration and tanglement of the grain boundaries were observed. Nevertheless, the microstructure of the sample twisted at 850 °C indicated the occurrence of DRX and the formation of fine grains in the vicinity of grain boundaries and triple points by the bulging mechanism. With an increase in the pass-strain of interrupted torsion at 1 000 °C, due to the increase in driving force for nucleation and growth of new grains, the kinetics of static restoration increased. However, due to the completion of DRX, the kinetics rate of static restoration at steady state strain (∊ s) was lower than that of the former state. The β → α phase transformation at 850 °C was found to be another factor contributing in fractional softening.

Interplay Between Superconductivity and Magnetism in Cu-Doped FeSe Under Pressure

Superconductivity in iron selenide is very sensitive to any dopants at levels of only a few percent. Here, we demonstrate how iron substitution by copper destroys superconductivity in FeSe, and argue why superconductivity reemerges under pressure. Detailed Mossbauer spectroscopy studies on 57Fe-enriched Cu0.04Fe0.97Se reveal that at low temperatures part of the iron sites is magnetically ordered, and static magnetic moments destroy the superconducting pairing. Application of pressure leads to a collapse of the static magnetism and restoration of superconductivity with the maximal T c value at pressure ∼ 8 GPa. The further pressure increase provokes a structural tetragonal-to-hexagonal phase transition and disappearance of superconductivity similarly to FeSe. The hyperfine parameters of the non-superconducting hexagonal phase of Cu0.04Fe0.97Se reveal a less covalent character of Fe–Se bonds and a noticeable higher value of the electric field gradient comparing to the tetragonal phase.

Abstract: 15.20 Revisited Fascia Lata In Facial Palsy

INTRODUCTION: Fascia lata suspension for static surgical treatment of the nasolabial region in long-standing facial paralysis is well established. The objective of this study was to evaluate, from a retrospective viewpoint, the functional and cosmetic effectiveness of static suspension in facial paralysis by introducing a new way to insert the fascial graft in patients with different indications, such as: onset of paralysis, age, general conditions, etiopathogenesis, expectations, and combination with reanimation procedures. We considered the stability, in time, of the results of this ancillary procedure present in every facial reconstructive surgeonÕs armamentarium, and we thought it should be re-evaluated and utilized either alone or in combination with techniques that reanimate the paralyzed face. MATERIALS AND METHODS: In our series, 55 patients with facial paralysis underwent static suspension with fascia lata, advanced in the same fashion as the temporalis muscle in Labbé’s myoplasty, between February 2009 and November 2015. The surgical technique is reported together with preoperative and postoperative records (photographs and videos reviewed for feasibility of the technique), symmetry, aesthetic results. Complications, need for further minor revisions, patients degree of satisfaction and role in improvement of the facial reanimation techniques were also considered. RESULTS: In all the patients the procedure was uneventful and none developed surgery-related complications, including donor-site problems. During follow-up, all the patients achieved improved symmetry at rest and showed satisfaction. The cosmetic outcome was satisfactory, too. Eight patients needed small revision in local anaesthesia. CONCLUSIONS: The results show immediate, aesthetic, stable in time improvement, thus confirming this method as a simple technique for static restoration in patients who have lost any functional reconstructive possibility. The method also works in patients who underwent facial reanimation requiring slight aesthetic improvement. The application of the modified technique has led to a new appraisal and re-evaluation of an almost obsolete method.

Room temperature superelastic responses of NiTi alloy treated by two distinct thermomechanical processing schemes

The room temperature superelastic response of NiTi alloy was investigated through two distinct thermomechanical processing (TMP) approaches. In the first TMP route, the experimental material was primarily cold compressed (up to true strains of 0.2 and 0.5) and then annealed at different temperatures (400 and 500°C) for 10, 30, 60 and 120min. In the second TMP course however, the material was hot compressed at temperatures of 700, 800 and 900°C up to the true strains of 0.2 and 0.5. The results indicated that the cold pressing to true strain of 0.5 followed by annealing at 400°C for 60min on the one hand, and hot pressing at 800°C to true strain of 0.5 on the other hand, were ended to the higher superelasticity effects (2.1% and 3.5% residual strain, respectively) in the courses of applied TMP routes. The detailed analysis showed that the superelasticity was improved at room temperature in the former one through increasing the critical stress for dislocation slip due to the occurrence of static restoration processes and the presence of higher austenite fraction. In the latter case however, the improvement was related to the occurrence of dynamic restoration processes; these were justified by microstructural examinations, precise flow curves analyses and the high transformation enthalpy in the second approach. The overall results directed to the capability of hot deformation to improve the superelasticity effects, which were enhanced formerly by conventional cold processing followed by subsequent annealing methods.

Dynamic and static change of grain size and texture of copper during friction stir welding

To comprehensively understand the microstructural evolution during friction stir welding (FSW), the plastic deformation stage and the post-annealing stage of the FSW were separated by a stop action technique associated with liquid CO2 cooling and a subsequent annealing treatment. During the plastic deformation stage, the initial large grains in the base metal were subdivided with the increasing strain and temperature, and the stir zone showed ultrafined grains with a large quantity of low angle boundaries and a symmetrical simple shear texture. During the subsequent annealing stage, static recrystallization occurred, which led to the selected grain growth, and disappearance of dislocations, that produced the simple shear texture change. The stir zone showed a recrystallized-like structure in appearance caused by the static continuous and discontinuous recrystallization. The static restoration caused by the post-annealing effect can significantly affect the microstructure, which is produced by the plastic deformation, and it should not be ignored when discussing the microstructure evolution of the FSW.

Domenico Fontana and the entrance of mechanics in architecture

AbstractThe analysis of archival documents related to the static restoration of the abacus of Marcus Aurelius Column and the reading of the description of the operations performed to move the Vatican Obelisk allow illustrating the mastery that Domenico Fontana exhibits about the statics of elementary machines – deriving from the knowledge of the technical literature of the second half of the sixteenth century – and his ability to exploit it as a support in the phase of structural invention. (© 2015 Wiley‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Video Image Restoration Based on Sparse Representation

The sparse representation, as a powerful model, has been successfully used in image processing. Considering that the sparse representation can be used in static image restoration, we propose a video image restoration method on sparse representation. In our algorithm we use a ternary function to express a video image. Adaptively selecting the dictionary by using the Principal Component Analysis (PCA) strategy and getting the sparse coding coefficients by the continuous iteration, finally we get the restored video image. The restored results by our method are compared with those by the other three methods. They are the wiener filter, the blind deconvolution, and the learning model method of natural image patches [7]. In order to better assess the quality of the video image restoration we use both the subjective evaluation and the objective evaluation. Extensive experiments show that our proposed method is effective and superior to the other methods.

Don't Give up Just Yet: Maintaining Species, Services, and Systems in a Changing World

Sandler’s paper, ‘Climate change and ecosystem management’ (2013), takes a clear-eyed and sober look at conservation via static reserves and ecosystem restoration in the context of climate change. It is a necessary discussion; while following traditional management practices is, in some ways, comforting and simple, the consequences of climate change throw those practices into a questionable light. Climate change makes achievement of their objectives extremely unlikely, and so their goals must change—losing their speciesprotection emphasis and falling back on more general goals of human interdependence, natural settings, and the like. We must revisit the goals of ecosystem management, better align our planning with the reality of climate change, and decide how interventionist our management should be. This paper is an excellent contribution, and this commentary (and its somewhat devil’s advocate approach) is offered in the spirit of debate. Sandler’s thesis is that species-specific or restoration oriented reserve planning goals are not justified, and therefore those goals must change. This lack of justification follows from the inherent difficulty of preserving species—it is not practical in a changing climate—and a shifting ecological context which decreases the value of those species. This commentary will address the practical and valuation argument, and then talk about some limitations of this approach—namely that ecosystem processes and services are not contingent on species in the first place, leading to some overly bleak conclusions.

Double-hit compression behavior of TWIP steels

The study of hot deformation characteristics of high-Mn twinning induced plasticity (TWIP) steels is of great importance due to their superior mechanical properties and potential applications for structural applications. In the present work, the static restoration behavior of 29 wt% Mn TWIP steel has been investigated using the double-hit compression testing technique. The tests were performed at 950–1150 °C under constant strain rate (0.1 s−1). The results indicated a hardening behavior when the second pass deformation was applied after the interpass time. To justify the strengthening behavior different mechanisms were considered. The static strain aging phenomenon, involving interactions between interstitial atoms (carbon atoms) and dislocations were believed to be the main reasons of interpass hardening in this study. The retardation of restoration processes due to the formation of high frequency annealing twins during interpass time as planar obstacles to the dislocation glide were believed as other reasons to explain this phenomenon.

Microstructure development in hot deformed AA6082

Age hardenable aluminium alloys are suitable for hot deformation at temperatures between 300 and 600°C, depending on the alloy and on the process. During thermo mechanical processes, dynamic and/or static restoration mechanisms take place. In this work, hot compression tests of hot rolled AA6082 and of a hot extruded AA6082 were carried out by means of a Gleeble® 1500 thermo-mechanical system, between 450 and 550°C and at 0.1–10s−1 of strain rate followed by fast cooling. The materials were thermo-mechanically processed before hot deformation to transform the complex initial microstructure into a fully recrystallized microstructure. Some compression tests of non recrystallized samples were carried out for comparison. All the samples were examined using electron backscatter diffraction (EBSD), followed by a determination of grain size and subgrain size distributions as well as of the local misorientation distribution. The as received samples showed a duplex microstructure consisting of elongated grains oriented in the rolling and extrusion directions, and some small recrystallized grains. The main restoration mechanism for all the materials is shown to be dynamic recovery, and the Zener–Hollomon parameter, as well as the flow stress was correlated to the subgrain size. The hot rolled material flow behaviour was sensitive to the initial microstructure, and geometric dynamic recrystallization was found.

Study of fractional softening of AZ31 magnesium alloy under multistage hot deformation

In the present study flow softening behaviour of AZ31 magnesium alloy was investigated by double hit compression tests in the temperature range 250–400°C and strain rate range 10–3–10–1 s–1. The tests were conducted with delay times varying 4–250 s after achieving the critical strain ϵc in each deformation condition. It has been found that static restoration processes (recovery and recrystallisation) were intensely depended on strain rate and deformation temperature. Fractional softening values increased with increasing strain rate and deformation temperature. Accordingly the softening curves were divided into three regions. The softening in the short interpass times was attributed to the occurrence of static recovery and followed by static recrystallisation and grain growth as dominant softening mechanisms for the second and third regions respectively. In addition static recrystallisation kinetics was interpreted by Avrami equation. Analysis of the results indicated that Avrami constant was changed by varying temperature.

Locally reconfigurable p-cycle networks for dual-failure restoration

p-Cycle reconfiguration methods (for instance complete, incremental, or dynamic-repair) based on the first event adaptive restoration model provide a promising approach for improving the dual-failure restorability characteristics of static p-cycle methods based on the static preplanned restoration model. However, if the reconfiguration process triggered by the first failure is not completed before a second failure occurs, p-cycle reconfiguration methods fail to achieve 100% dual-failure restorability and reduce to the static p-cycle methods which do not take advantage of the spare capacity to be reconfigured. In this study, we propose to use a new restoration model designated as first event locally adaptive restoration model with a coordinated re-restoration effort. This model is aimed to limit the reconfiguration scope to a local p-cycle where the spare capacity is only reconfigured on its straddling links for reducing the reconfiguration overhead (i.e., the average number of reconfigured links during the reconfiguration time.) According to this model, a two-phase locally reconfigurable p-cycle method is proposed. Only the straddling links of the local p-cycle affected by the first failure are reconfigured in the first phase. The second phase is not initialized until the second failure really occurs in the affected local p-cycle. The second phase is to enable the dual-failure restorations with a coordinated re-restoration effort for the first failed link from its original end nodes for any damage that the second failure causes to previously deployed restoration paths. The objective of the proposed method is to maximize the dual-failure restorability within a limited reconfiguration scope. We evaluate the correlation between the normalized spare capacity cost and the dual-failure restorability. The results show that the proposed local reconfiguration heuristic method improves the average dual-failure restorability of the 9n17s and Cost 230 networks by 45.1% and 20.1%, respectively, relative to the static p-cycles method and achieves closely the optimal value obtained using integer linear programming (ILP). Additionally, the spare capacity cost of the proposed local reconfiguration method is smaller than that of previous p-cycle reconfiguration methods in the two test networks.