Surface Projection Research Articles

3D Printed Metamaterial Absorber Based on Vanadium Dioxide Phase Transition Control Prepared at Room Temperature

AbstractThe thermal phase transition characteristics of vanadium dioxide can effectively regulate the absorption performance of metamaterial absorbers. A petal‐shaped metamaterial absorber is designed based on vanadium dioxide phase transition control and prepared metamaterial samples using surface projection micro stereolithography (PµSL) 3D printing technology. Then, vanadium dioxide thin films are coated on the surface of the metamaterial using the ultrasonic spraying method. The PµSL 3D printing technology makes it possible to prepare high‐precision complex samples, and the ultrasonic spraying method enables the coating of vanadium dioxide thin films at room temperature. To demonstrate the stability of this method, two different metamaterial structures are prepared: planar structure and hemispherical structure. In the experiment, a non‐contact heating method is used to regulate the temperature of the vanadium dioxide thin film, which made the temperature of the metamaterial sample controllable, stable, and uniformly heated. The experimental results show that the designed metamaterial absorber has excellent modulation performance and excellent switching characteristics, which proves the reliability of the method.

PHASE EQUILIBRIA IN THE Cu2Se - Cu3SbSe4 - Cu2SnSe3 SYSTEM

Copper-tin and copper-antimony chalcogenides have received increasing attention as promising thermoelectric materials due to their high efficiency and low toxicity. Many of these phases are synthetic analogues of natural copper chalcogenide minerals and have been drawing more interest for the development of new environmentally friendly materials. In this regarding, we studied phase equilibria in the Cu2Se - Cu3SbSe4 - Cu2SnSe3 system using Differential Thermal Analysis (DTA), Powder x-ray Diffraction (PXRD) and Scanning Electron Microscope (SEM). Based on experimental data, a number of polythermal sections, the solid-phase equilibria diagram at 600 K and a projection of the liquidus surface were constructed for the title system. The system has revealed limited regions of solid solutions based on ternary compounds Cu3SbSe4 (α) and Cu2SnSe3 (β). It has been established that the liquidus surface consists of three regions corresponding to primary crystallization (HT-Cu2Se), as well as α- and β-phases.

Experimental study on the effect of surface-projected conditions on the mechanical behavior of pile embedded in sand

Surface-projected piles, such as helical and under-reamed piles, are widely utilized in geotechnical engineering to enhance the load-carrying capacities of pile structures with surface projection part. Despite the use of a wide variety of surface-projected conditions, detailed investigations considering various dimensions and angles of surface-projected piles remain limited in the current literature. This study aims to assess the effects of surface-projected widths wp (10 mm, 20 mm, 40 mm) and angles θ (18°, 27°, 45°, 90°) on pile penetration resistance using a two-dimensional model and PIV analysis. Wider projections increased resistance, with a maximum of 1.84 kN—57% higher than conventional piles in the model ground. Penetration resistance was proportional to width at 90°; for wp = 20 mm, penetration resistance decreased with increasing θ, while for wp = 40 mm, it increased. Theoretical ultimate bearing capacity calculations emphasize differences from experimental results due to neglected shaft friction. Residual penetration resistance and particle displacement were observed for wp of 20 mm and 40 mm after failure. This study provides insights into optimizing surface-projected pile design and understanding ground failure mechanisms.

Methodology for determining the hardness and depth of the hardened layer (in Kazakh language)

The article discusses methods for determining the hardness and depth of the hardened layer. Stiffness is defined as the ratio of the amount of load to the surface area, projection area, or print volume. The following types of surface, projection and volumetric stiffness are distinguished:surface hardness-the ratio of the load to the surface area of the print; projection stiffness-the ratio of the load to the area of the print projection; volumetric stiffness-the ratio of the load to the print volume. Hardness is measured in three ranges: macro, micro, nano. Hardness is the degree to which mineralogy often encounters this when scratching one mineral with another. In addition, the hardness of a mineral is also known as the degree of resistance to the influence of external mechanical force. But the external mechanical effect itself will be slightly different, depending on how strongly the mineral resists.The article conducted research with examples of several methods for determining the hardness of the layer.

Development of performance indicator for metal-organic frameworks in atmospheric water harvesting

This study aims at developing a new set of performance indicators for atmospheric water generation (AWG) via metal organic frameworks (MOFs). Several field studies report specific setup paired with particular MOF but often lack evaluation on a common benchmark for AWG which is focused in this study. The article lays down a stepwise procedure by extracting information from in-vivo material characteristics such as water adsorption isotherms and kinetics, to model MOF behaviour in AWG, and produce four novel quantifiers to describe the complete systems performance in terms of uptake, thermodynamics, surface projection, and kinetics. A model MOF-801 AWG has also been evaluated for a proof of concept. Furthermore, three independent water adsorption experiments on MOF-801 from the literature are compared based on as-developed indicators and ranked according to the performance of the system.

Photogrammetry is a useful tool to assess the aesthetic outcome after excision and reconstruction of the nose skin tumors

BackgroundobjectivePost-oncological nasal reconstruction presents both aesthetic and functional challenges. While established methods exist for quantitatively evaluating functional results following surgery, equivalent systems for assessing aesthetic outcomes are lacking. Three-dimensional (3D) photogrammetry, already used in maxillofacial and orthodontic surgery for aesthetic evaluation, overcomes some limitations of traditional methods like direct anthropometry. However, its applicability in oncological facial reconstruction has not yet been explored. In our study, we applied the 3dMDtrio™ system for the quantitative analysis of line and surface modifications following nasal reconstruction. MethodsWe conducted a prospective observational study enrolling patients with skin neoplasms located on the nose undergoing surgical excision and reconstruction. Using the 3dMDtrio™ system, we measured the dimensions and projections of nasal surfaces and the positions of specific landmarks before and after surgery. The surface measurements were then correlated with aesthetic evaluations performed by three plastic surgeons, not involved in the procedure, using a 5-point Likert scale. ResultsWe included 33 patients with a mean age of 71 years, ranging from 40 to 94. We obtained complete documentation of all postoperative measurements for 21 patients. We observed significant changes in the positions of the landmarks post-surgery, limited to the right ala and nasion. The average nasal surface area was 4674.41 mm2 ± 477.24 mm2 before surgery and 4667.95 mm2 ± 474.12 mm2 after surgery, with no significant discrepancies. The evaluation using the Likert scale revealed an average score of 3.04 ± 0.48, with a significant negative correlation to the measured surface changes. ConclusionOur findings suggest that 3D photogrammetry can be considered a valid method for objectively assessing volumetric changes associated with post-oncological nasal reconstructive surgery.

Investigation of the Er-Sb-Te system

Methods of physicochemical analysis, namely differential thermal analysis (DTA), high temperature differential thermal analysis (HTTA), X-ray phase analysis (XRD), microstructural analysis (MSA) and microhardness measurements are used to determine the nature of the physicochemical interaction in the Er-Sb-Te ternary system.. Phase diagrams of the following quasi-binary Er2Te3-Sb2Te3, ErTe-Sb2Te3, ErTe-SbTe, ErTe-Sb and non-quasi-binary Er-Sb2Te3, D (ErSb3Te5,5)-Te sections are presented for the first time. It has been established that at a component ratio of 1:1 in the Er2Te3-Sb2Te3 system, a new ternary phase with the composition ErSbTe3 is formed, which crystallizes in the hexagonal syngony with unit cell parameters: a=0.408; c=3.045 nm. In the system based on Sb2Te3, solid solutions are formed, the boundaries of which are up to 3 mol% Er2Te3 at room temperature, and at the eutectic temperature it reaches about 8 mol% Er2Te3. The ternary combination of ErSbTe3 with an α-solid solution forms a eutectic, the coordinates of which are 20 mol % Er2Te3 and 800 K. The liquidus of the ErTe-Sb2Te3 system consists of two branches of primary crystallization of an α-solid solution based on Sb2Te3 and an Er2Te3 compound. In the ErTe-Sb2Te3 section, a region of homogeneity is also formed based on Sb2Te3 up to 5 mol % ErTe. The system state diagram is of the simple eutectic type. Eutectic coordinates 25 mol% ErTe and 850K. In the ErSb – ErTe and Sb – ErTe systems, no new ternary phases and homogeneity regions have been found. Eutectic coordinates in the ErSb – ErTe system; 50mol % ErTe and 1200K, and in the second system (Sb – ErTe) a degenerate eutectic is observed (at 900K). The cut Sb2Te3-Er intersects three, and D-Te two subordinate triangles. In both systems, ternary eutectic and peritectic invariant reactions occur at different temperatures. A projection of the liquidus surface of the Er-Sb-Te ternary system is also constructed, which consists of fourteen fields of primary crystallization of phases, separated by 25 monovariant equilibrium curves. Monovariant curves intersect at 11 nonvariant points, five of which are eutectic and six are peritectic.

GeTe–Bi<sub>2</sub>Te<sub>3</sub>–Te System

Alloys of the GeTe–Bi2Te3–Te system, synthesized using a special technique that makes it possible to obtain them in a state as close as possible to equilibrium, have been studied using the methods of differential thermal and X-Ray diffraction analysis, as well as scanning electron microscopy. A solid-phase equilibria diagram, a projection of the liquidus surface, some polythermal sections and an isothermal section at 300 K of the phase diagram were constructed. The fields of primary crystallization of phases, types and coordinates of non— and monovariant equilibria are determined. It has been established that monovariant equilibria on curves emanating from the peritectic and eutectic points of the GeTe–Bi2Te3 boundary system undergo transformations at certain transition points. Near the tellurium corner of the concentration triangle, a cascade of invariant transition reactions has been identified, characterizing the joint crystallization of two-phase mixtures of telluride phases and elemental tellurium.

Performance of hydraulic structures during 6 February 2023 Kahramanmaraş, Türkiye, earthquake sequence

The earthquake sequence that occurred on 6 February 2023 in Türkiye, Kahramanmaraş, had a significant impact on 140 dams, most of which are located within a distance of 50 km from surface projection of the fault rupture. These dams experienced moderate to high levels of seismic intensity, with peak ground acceleration (PGA) estimated to vary between 0.1 and 1.3 g during the Pazarcık earthquake and 0.15 to 0.45 g during the Elbistan earthquake, depending on their proximity to the fault rupture. Although all dams were able to maintain water-retaining capabilities, some of them suffered from moderate to large permanent deformations. As part of the emergency response measures, the water levels at two of these dams, namely Sultansuyu and Arıklıkaş, were lowered in a controlled manner. Following the earthquakes, a comprehensive survey of all hydraulic structures within the influence zone was conducted, and the findings are represented in this study. These findings revealed that earthfill and rockfill dams sustained more significant damage compared with concrete dams, particularly in areas close to the fault rupture, where the shaking intensity was most pronounced. The amount of permanent displacements was observed to consistently increase with the height of the dam’s transverse section.

Multi-archive record of late Quaternary paleoseismicity along the surface projection of the 2017 Pohang earthquake seismogenic fault, SE Korea

Multi-archive record of late Quaternary paleoseismicity along the surface projection of the 2017 Pohang earthquake seismogenic fault, SE Korea

Experimental determination and thermodynamic reassessment of the Al–Cr–Ru ternary system

The isothermal sections at 950 °C and 1150 °C of Al–Cr–Ru ternary system were determined experimentally by equilibrium alloy method, combined with X-ray diffraction, scanning electron microscopy and energy-dispersive spectrometric. Nine and eight three-phase equilibria were confirmed at the 950 °C and 1150 °C isothermal sections of the Al–Cr–Ru ternary systems, respectively. The liquids surface projection of the Al–Cr–Ru ternary system was determined by identifying the microstructures of the as-cast alloys, and seven primary solidification regions were determined in the liquids surface projection. Besides, the ternary compound τ2 was identified as end-centered monoclinic structure by transmission electron diffraction analysis. The lattice parameters of the τ2 phase are a = 0.5175 nm, b = 1.7532 nm, c = 0.5150 nm and α = γ = 90°, β = 79.167°. Based on the available data of the Al–Cr–Ru ternary system and related binary systems, thermodynamic reassessment of the Al–Cr–Ru ternary system was performed using the Calculation of Phase Diagram approach. A new thermodynamic database for the Al–Cr–Ru ternary system was obtained, and the experimental data are consistent well with the calculated results.

Experimental Determination of the Isothermal Sections and Liquidus Surface Projection of the Co–V–Zr System

Experimental Determination of the Isothermal Sections and Liquidus Surface Projection of the Co–V–Zr System

Infratentorial hypoperfusion in multiple sclerosis

AbstractObjectivesLong‐term disability in patients with multiple sclerosis (MS) results from axonal degeneration in the central nervous system, which might follow hypoperfusion in neurodegenerative diseases. This study aimed to clarify the distribution and clinical significance of brain hypoperfusion in patients with MS.MethodsWe measured brain hypoperfusion in eight patients with relapsing–remitting MS using N‐isopropyl‐p‐iodine‐123‐iodoamphetamine single‐photon emission computed tomography with three‐dimensional stereotactic surface projection and stereotactic extraction estimation; moreover, we examined its clinical relevance.ResultsWe detected marked hypoperfusion in the brainstem and cerebellum relative to that in the cerebrum. Each infratentorial segment, the midbrain, pons, and cerebellar anterior and posterior lobes, showed more severe hypoperfusion than the frontal and parietal lobes (n = 8). This was attributed mainly to oligoclonal band (OCB)‐negative patients (n = 3), even when OCB‐positive patients (n = 5) showed a similar trend. Consistently, OCB‐negative patients had lower blood flow at the pons, and cerebellar anterior and posterior lobes than OCB‐positive patients; however, both groups showed comparable hypoperfusion in the cerebral lobes. Hypoperfusion at the posterior cerebellar lobe and pons was correlated with poor performance in the Trail Making Test Part B (n = 6), indicating cognitive cerebellar dysfunction and cerebrocerebellar conductive disturbances.ConclusionsPatients with relapsing–remitting MS had lower infratentorial perfusion, which strongly links to OCB‐negativity. The distribution of brain hypoperfusion detected by N‐isopropyl‐p‐iodine‐123‐iodoamphetamine single‐photon emission computed tomography indicated pathological heterogeneity in relapsing–remitting MS. The infratentorial hypoperfusion is possibly associated with neurodegeneration.

Liquidus surface projection and isothermal section at 1500 °C of (Mo-5Nb)-Ti-C pseudo-ternary system

The liquidus surface projection and isothermal section at 1500 °C of the (Mo-5Nb)-Ti-C pseudo-ternary system were experimentally determined. X-ray diffraction analysis and scanning electron microscopy in conjunction with electron-probe microanalysis were carried out to analyze the solidification behavior and phase constituents. The replacement of 5 at.% Mo with Nb was found to negligibly affect the solidification path or the formation of new phases. However, the quasi-peritectic point U2 shifted closer to the (Mo-5Nb)-C border in the liquidus surface projection than in the Mo-Ti-C system. The BCC single-phase region, BCC + TiC two-phase region, and BCC + Mo2C + TiC three-phase region were determined in the isothermal section at 1500 °C. The replacement of 5 at.% Mo with Nb was found to expand the BCC + TiC two-phase region and narrow the BCC + Mo2C + TiC three-phase region by stabilizing the TiC phase. Therefore, the addition of Nb to the Mo-Ti-C system expanded the compositional range of the BCC + TiC two-phase region, leading to variable properties of TiC-dispersed BCC-based alloys and BCC-TiC cermets.

Utility of combining multiple parameters of 123I-IMP SPECT and voxel-based morphometry MRI using a multiparametric scoring system for differentiating dementia with Lewy bodies from Alzheimer's disease.

Brain magnetic resonance imaging voxel-based morphometry (VBM) and perfusion single-photon emission computed tomography (SPECT) are useful for differentiating dementia with Lewy bodies (DLB) from Alzheimer's disease (AD). To determine whether combining multiple parameters of VBM and SPECT using a multiparametric scoring system (MSS) improves diagnostic accuracy in differentiating DLB from AD. In total, 23 patients with DLB and 57 patients with AD underwent imaging using a voxel-based specific regional analysis system for AD (VSRAD), an easy Z-score imaging system, and a Z-Graph using three-dimensional stereotactic surface projection. The cutoff values were determined using the receiver operating characteristic curve to differentiate DLB from AD for all parameters. Patients were scored 1 (DLB) or 0 (AD) for each statistically significant parameter, according to a threshold. The total score was determined for each case to obtain a cutoff value for the MSS. The mean Z-scores in the medial temporal lobes using the VSRAD were significantly lower in patients with DLB than in those with AD. Each Z-score of the summed Z-scores in all four segmented regions of the occipital lobes using the Z-Graph was significantly higher in patients with DLB than in those with AD. Among the five parameters, the highest accuracy was 80% for the Z-score of the summed Z-scores in the left medial occipital lobe. For the MSS, a cutoff value of four improved the diagnostic accuracy to 82%. MSS was more accurate than any single parameter of VBM or SPECT in differentiating DLB from AD.

Temperature dependence of tribological properties in NiTi shape memory alloy: A nanoscratching study

The molecular dynamics method was used to simulate nanoscratching of a monocrystalline NiTi shape memory alloy (SMA) under various temperatures. Parameters, including the normal force, tangential force, friction coefficient, contact area, scratching hardness, atomic displacement, atomic structure, and surface morphology, were comprehensively studied to understand the friction mechanism of the NiTi SMA during operation. It was verified that the temperature dependence of the tribological properties of the NiTi SMA is mainly attributed to the temperature dependence of the tangential force.The beginning temperature of the reverse martensitic transition (As) is the critical temperature for the transition of tribological properties. Below this temperature, the sliding contact region exhibits good normal/tangential projection symmetry, with the atoms on the contact surface arranged in order. A wide range of martensitic strain coordination occurs in the contact region, leading to a low friction coefficient and minimal wear. When the temperature exceeds this threshold, the asymmetry of the contact surface projection gradually increases. The atoms on the contact surface exhibit amorphous atomic characteristics, causing the influence domain of martensitic transformation of scratches to gradually decrease and the friction coefficient to increase. This study offers insights into the atomic-scale perspective for analyzing the temperature-dependent friction behavior of NiTi SMA induced by phase transition.

Experimental investigations of 9 mol.% Mo5SiB2 isopleth phase diagram in Mo–Mo5SiB2–TiC pseudo-ternary system

The present work focuses on gaining a systematic understanding of the microstructure variation and solidification reactions of alloys in the Mo-rich portion of the Mo–Mo5SiB2(T2)–TiC pseudo-ternary system. A series of MoSiBTiC alloys with 9 mol% T2 were selected from the vicinity of the Mo–TiC binary and Mo–Mo5SiB2(T2)–TiC ternary eutectic point to carefully examine the solidification pathway and phase diagram. The solidification reaction temperature of the alloys was detected via an ultra-high-temperature thermal analysis method using blackbody radiation. Solidification was observed in situ using an electromagnetic levitation (EML) apparatus, and the microstructure evolution of solidified EML samples under different thermal histories was characterized. The results provide an experimentally based reassessment of the liquidus surface projection. The primary Moss phase region is shown to be larger than indicated in previously reported data, and a Mo2B primary region should exist in the triangle. As the main result of the investigation of the solidification pathway of a series of MoSiBTiC alloys, an isopleth phase diagram with 9 mol.% T2 in Mo–Mo5SiB2(T2)–TiC pseudo-ternary system is presented.

Experimental determination and thermodynamic optimization of the Nb–V–Zr system

A comprehensive thermodynamic description for each phase is essential for designing of the novel Zr-based nuclear materials. The construction of the experimental liquidus surface projection and isothermal section of the Nb–V–Zr system was established through analyzing solidification microstructures and phase constituents. The stability of the τ phase with C14-structure was established by investigating the composition range of Nb in τ, which was measured to be between 19.8 and 40.5 at.% at 1473 K. The solubility of Nb in λ2 with the C15-type was ∼ 16.9 at.% at 1473 K. The liquidus surface projection showed primary solidification areas of bcc(Nb,V,Zr), λ2 and τ. The thermodynamic parameters were derived combining the CALPHAD method with experimental results from phase diagram data in this work and the literatures. Solution phases, including liquid, bcc, and hcp, were regarded as substitutional solutions. Considering the crystal structures and solid solubility of intermetallic compounds, λ2 and τ were modeled as (Nb,V,Zr)2(Nb,V,Zr) using two-sublattice model. A set of self-consistent thermodynamic parameters of the Nb–V–Zr system was obtained, which will provide theoretical guidance for the design of Zr-based nuclear materials.

EXPERIMENTAL STUDY OF THE PHASE EQUILIBRIA IN THE SnTe–Sb2Te3–Te SYSTEM

Phase equilibria of the SnTe–Sb2Te3–Te portion of the Sn–Sb–Te ternary system have been experimentally investigated using differential thermal analysis (DTA), powder X-ray diffraction (XRD), and microstructural analysis methods. Based on the measured experimental results and literature information, isothermal sections at 500 K, liquidus surface projection, and several vertical sections of the phase diagram were plotted. The 500 K phase diagram of this system consists of 2 single-phase regions, 2 two-phase regions, and 3 three-phase regions. The liquidus surface projection is represented by the primary crystallization fields of 5 phases. The primary crystallization fields of all phases, the types, and coordinates of non- and monovariant equilibria were determined. Obtained experimental data can be valuable input for design for Sn–Sb–Te-based alloys

Exploring Quaternion Neural Network Loss Surfaces

This paper explores the superior performance of quaternion multi-layer perceptron (QMLP) neural networks over real-valued multi-layer perceptron (MLP) neural networks, a phenomenon that has been empirically observed but not thoroughly investigated. The study utilizes loss surface visualization and projection techniques to examine quaternion-based optimization loss surfaces for the first time. The primary contribution of this research is the statistical evidence that QMLP models yield smoother loss surfaces than real-valued neural networks, which are measured and compared using a robust quantitative measure of loss surface “goodness” based on estimates of surface curvature. Extensive computational testing validates the effectiveness of these surface curvature estimates. The paper presents a comprehensive comparison of the average surface curvature of a tuned QMLP model and a tuned real-valued MLP model on both a regression task and a classification task. The results provide strong support for the improved optimization performance observed in QMLPs across various problem domains.