Narrow Curves Research Articles

Modelling and application of yaw damper with frequency-selective damping on railway vehicles

In this study, a new mechanical yaw damper with frequency-selective damping (FSD) is investigated. The structure principle, modelling and simulation of the damper and its core component, the frequency-selective damping valve, are elaborated. Compared with the conventional damper, the static and dynamic characteristics of the FSD damper have been tested in the experimental bench, and the damping variation rate is proposed to evaluate the damping force variation. A physical parameter model of the yaw damper is established by using the AMESim software, and the simulation accuracy has been verified by comparing the simulated results with the experimental ones. A detailed analysis has been performed for the influence of key parameters of the FSD valve on the mechanical characteristics of the FSD damper. Finally, through the AMESim/Simpack co-simulation method, the dynamic performances of a high-speed locomotive equipped with the FSD yaw damper have been simulated. The results indicate that the FSD yaw damper improves the adaptive stability of railway vehicles in different wheel–rail matching states. In addition, the dynamic performance of the vehicle can be improved when passing through the turnout and narrow curves.

Insights into gas-solid flow structures in fluidized beds up to 1600 °C via analysis of gas residence time distributions

This study investigates gas residence time distributions (RTDs) in a fluidized bed of Al₂O₃ particles at temperatures ranging from ambient to 1600 °C, focusing on the impact of temperature on gas back-mixing and flow patterns. We find that at low temperatures (up to 300 °C), gas flows in a near-plug flow pattern, represented by narrow RTD curves with early peaks. As temperature increases to 600 °C, the RTD curves broaden, featuring delayed peaks due to bubble breakup and enhanced gas drag. Between 800 °C and 1200 °C, significant deviations from plug flow emerge, driven by stronger interparticle forces and increased gas transfer to the emulsion phase. Interestingly, beyond 1200 °C, the RTD curves shift back toward plug flow, influenced by intensified interparticle forces and physicochemical changes in the bed materials.

The Stunting Determinants in Toddlers from Landak Regency, West Kalimantan: A Cross-Sectional Study

Background: Stunting is a nutrition problem that can slow down the growth. With prevalence at 32.5%, Landak Regency in West Kalimantan has been designated as a stunting hotspot. The lack of a maximum penalty for the stunting case in Landak Regency is not based on factors causing the stunting itself, because there is no identifiable factor causing the stunting in certain area due to narrow roads and sharp curves. Objectives: The objective of this study was to identify causes and distribution of the stunting case in Landak Regency. Methods: A total of 330 households in Meranti, Sebangki, and Senakin were included in this cross-sectional study because they were at a risk of the stunting. Toddlers, mothers, health care, and environmental factors were among the found variables. The researchers employed a basic random sampling strategy for the sampling and used the secondary health center data to find out whether or not toddlers were stunted. Researchers in this study collected data on the independent variables by observing and interviewing participants. Using the chi-square test, the data was analyzed. Results: The results showed that determinants of the stunting in Landak Regency were the history of early breastfeeding initiation (p-value=0.032), exclusive breastfeeding (p-value=0.042), frequency of exclusive breastfeeding (p-value=0.040), the continued breastfeeding (p-value=0.024), complementary feeding (p-value=0.042), immunization history (p-value=0.007), infectious disease history (p-value=0.000), maternal height (p-value=0.046), delivery assistance (p-value=0.000), access to health services (p-value=0.004), the role of health workers (p-value=0.002), and family latrine ownership (p-value=0.000). Conclusions: Several factors were found to be associated with incidence of the stunting among toddlers in Landak Regency.

Concentration‐driven morphology change of a self‐aggregated amino acid‐inspired fluorescence‐active copolymer for sustained release of hydrophobic drug

AbstractThe development of amphiphiles for sustained drug delivery represents a promising approach in biomedical fields. Polymeric self‐assembly with a hydrophobic core offers plenty of opportunities to encapsulate hydrophobic drugs for facilitating targeted delivery to the specific sites of action. Herein, N‐Boc tryptophan has been used to develop a hydrophobic monomer, Boc‐tryptophan‐HEMA (HBT). The HBT monomer has further been grafted on modified alginic acid through the RAFT technique to synthesize a unique amphiphilic copolymer with fluorescence characteristics. The advanced polymer chromatography demonstrates a narrow distribution curve, signifying the living nature of polymerization. The copolymer has exhibited self‐aggregation behavior with two distinct shapes at two different critical aggregation concentrations (CAC). The concentration‐dependent shape variation has been investigated using FESEM and TEM analyses, further supported by a small‐angle x‐ray scattering analysis. The self‐aggregation behavior of the copolymer facilitates the uptake of a model hydrophobic drug (naproxen) and its release in a sustained manner with varied rates at two different concentrations.

Investigation of tribological behavior of coated and untreated rail steels under wet conditions

Rails are exposed to more stresses, especially in the regions of narrow radius curves and switch passages. Therefore, the tribological features of these regions are important. In this study, the effect of boronization on tribological properties was examined. For this purpose, experiments were carried out on samples boronized at 800 °C for 2 h and 8 h and on untreated samples. With these experiments, the friction coefficient, volume loss and surface roughness values of the samples under wet conditions were examined. In addition, the microstructures of the material after boriding were observed by SEM and EDX. The variance and regression method (ANOVA) was used for the statistical analysis of the experimental results. After SEM examinations, a coating layer of ∼22 μm (FeB) and ∼48 μm (FeB+Fe2B) were obtained on the surface of the rail steels boronized for 2 and 8 h, respectively. The microhardness of the rail steels, which was ∼300 HV for the untreated sample, increased to ∼1900 HV and ∼2400 HV with the boronizing process boronized for 2 and 8 h, respectively. According to the ANOVA results, the effects of the boronizing process on the decrease of the friction coefficient and the volume loss were calculated as 42% and 46%, respectively. Finally, according to the corrosion results, the corrosion resistance of the boronized rail steels decreased with the boride layer formed.

Surface plasmon resonance in gold-silver bilayer coated D-shaped multimode optical fiber: An approach to refractive index sensing

This paper presents the surface plasmon resonance (SPR) characteristics of D-shaped silica multimode optical fiber coated with bilayer silver-gold film. The effect of various coating thicknesses on the SPR characteristics was investigated through simulation using COMSOL Multiphysics. The inner layer Ag thickness varied from 20 nm to 60 nm, and the outer layer Au thickness ranged from 5 nm to 25 nm. Prior simulation results indicated that a single-layer silver (Ag) coating produces a narrower plasmonic curve than a single-layer gold (Au) coating. The confinement loss and the resonance wavelengths were simulated for the sensing medium with a refractive index (RI) range of 1.40–1.45. The simulation results show that the Ag/Aubilayers coated sensorshavebetter full-width-half-maximum (FWHM) and figure-of-merit (FOM) than the single-layer coated sensors. The Ag/Au with a 40 nm/5 nm thickness exhibits the highest confinement loss, with a wavelength sensitivity of 10 000 nm/RIU and a figure-of-merit (FOM) of 500 RIU−1. The proposed sensor using a D-shaped optical fiber coated with Ag/Au layers has a high potential for remote sensing applications involving chemical liquids, offering robust and accurate measurements within the tested refractive index range.

Increasing the Q-factor of resonant cantilevers in magnetic force microscopy through helium gas flow

To obtain high-resolution magnetic force microscopy (MFM) images, it is essential to have a cantilever with a high-quality factor. However, conventional vibrating cantilevers typically have quality factor values in the range of a few hundred, which limits their sensitivity for MFM measurements. To address this limitation, numerous studies have explored methods to enhance the quality factor in different environments, including vacuum, air, and liquid. This study introduces a novel approach for improving the quality factor using flowing helium gas. By selecting helium gas with a low viscosity coefficient, we successfully achieved a higher quality factor (Q-factor) of MFM microcantilever oscillations at room temperature in one atmosphere compared with the Q-factor in air. This provides a potential approach for achieving high-resolution MFM measurements under room temperature conditions. By optimizing the gas flow rate at room temperature in one atmosphere, we successfully obtained a higher MFM cantilever oscillation Q-factor and clearer MFM images compared with the air. The experimental results revealed a long and narrow resonant curve, and the quality factor significantly increased to 778.2, which is 3.8 times higher than that observed in air 205.4. Furthermore, systematic investigations demonstrated the capability of this approach to produce high-resolution MFM images of videotape track patterns under the optimized helium gas flow rate of 60 mm/s.

Stability of the atomic arrangement in Laves phases Be2Fe1–xOsx (0 ≤ x ≤ 0.75) and Be2Fe1–xRux (x[formula omitted] 0.5)

The binary Be2Fe, which crystallizes in the C14-structure type hexagonal Laves phase, can dissolve a large amount of Os as a third element, without changing the crystal structure (about ¾ of Fe can be replaced by Os). A study of the homogeneity range for the Be2Fe1–xOsx Laves phase, shows an increase of the lattice parameters with an increase of the Os content. When Ru substitutes Fe in Be2Fe, a temperature- and composition-dependent transformation from the C14 to the cubic C15 Laves phase is observed, with a narrow homogeneity range. Formation energy calculations revealed that the C14-structure type is energetically favored when Os substitutes Fe in Be2Fe, while a structural phase transition is observed between Be2Fe (C14) and Be2Fe0.5Ru0.5 (C15), all in good agreement with the experimental results. A strong charge transfer from Be to Os or Ru is observed from the analysis of electron density within the Quantum Theory of Atoms in Molecules (QTAIM) framework. A formation of multiatomic bonds is found from the electron localizability approach. Be2Fe1–xOsx undergoes a transition to a disordered ferromagnetic state at TC= 350 K and behaves like a ferromagnet with a non-collinear magnetic structure (not all domains polarized along field). Be2Fe1–xRux orders ferromagnetically below TC= 340 K and the very narrow hysteresis curves show that Be2Fe1–xRux is a soft ferromagnet.

Experimental Study on Reduction of Curve Squeal Noise on Mountain Tram Wheels on Sharp Curves Using Lubricant

Curve squeal noise is an intense tonal noise that occurs when a train goes through a narrow curve and is generated by the wheel contacting the rail. The squealing noise is an issue in mountain tram development projects. In this study, 1:7.5 scaled equipment is proposed to produce the squealing noise based on rolling speed, rolling direction, angle of attack, and preload ratio. Solid-stick lubricant is used as a mitigation method. The similarity law is applied and a finite element analysis code is used to compare the natural frequency of full-scale and small-scale results. The results show that the scaled equipment can generate squealing noise and that rolling backward direction has a higher possibility of generating squealing noise. Moreover, the frequency similarity approach is verified, and the solid stick lubricant is found to successfully mitigate the squealing noise even at high rolling speed and angle of attack.

Study on railway curve squeal using a rigid-flexible coupling model of vehicle and track

Squeal noise occurring in narrow curves is one of the most annoying noise issues for people living by the railway track. When vehicles pass through those curves, squeal noise is mainly generated due to the large, high-frequency, lateral sliding friction force. To investigate generation mechanism of curve squeal, a three-dimensional (3D) vehicle-track interaction model with a flexible wheelset and a flexible curved track is built in a multi-body simulation tool in this paper. Compared to conventional rigid models, this model allows to obtain the high frequency friction force between wheel and rail. This calculated friction force in the frequency domain is analyzed to identify the major modes. Those modes are compared with the modal properties of the wheelsets and rails in order to determine which of their modes have the main contribution to the friction force and the squeal noise. In addition, a parametric study is performed to study the influence of vehicle speed, curve radius, wheel/rail friction coefficient and further parameters on the dominant modes of friction forces.

Annoyance of railway curve squeal

Trains passing through a curve frequently produce the so-called curve squeal, which are salient noise components (typically either tonal or transient) covering a wide frequency range. Although the main underlying acoustical mechanisms are well known, due to the large variety of curve squeal characteristics, their effects on acoustic parameters and in particular on the perception are difficult to quantify. The work presented here aims at investigating the effects of acoustically described curve squeals on the perceived annoyance, tested in the laboratory with 30 listeners. Measurements of curve squeal at distances of 7.5, 25, and 50 m in three narrow curves were obtained. By means of so-called frame multipliers, time-variable salient features were manipulated and combined with a number of clean rolling noises to simulate squeals with parameters obtained from existing emission measurements. The annoyance ratings showed that the perception of curve squeal can be considerably altered compared to that of regular passby noises. A model was developed for the annoyance equivalent level adjustment from a clean rolling noise based on the contrast of high and mid-frequency energy. The model predictions can serve as a basis to establish rating levels predicting the perceived annoyance of railway curve squeal.

Analysis of the effect of hydrate on water retention curves in gas hydrate-bearing sediments using gas drainage combined with NMR

Water retention curves play a critical role in numerical simulations for predicting fluid production and sediment deformation behaviors in gas hydrate-bearing sediments (GHBSs). This study uses a new testing assembly that combines gas drainage and low-field nuclear magnetic resonance (NMR) tests to determine the water retention curves of artificially synthesized clay silty specimens. The effect of hydrate on the pore size distributions and water retention curves is analyzed via NMR transverse relaxation time curve distributions, and the mechanism of changes in the water retention curve parameters is further discussed. The results show that hydrate formation decreases the proportion of pores with sizes greater than 15 μm and increases the proportion of pores with sizes less than 3.5 μm in clay silty sediments. Hydrate formation increases capillary pressure and prevents available water migration. The presence of hydrate exponentially increases the normalized capillary pressure but exponentially decreases the normalized curve shape factor, yielding narrower curve distributions. The gas entry pressure and curve shape factor exhibit linear correlations with the pore size distribution parameters. The results imply that the changes in the water retention curves are strongly related to the initial pore size distributions. This study offers a deep understanding of capillary effects-related water retention characteristics and their underlying links with the pore size distributions, and demonstrates that low-field NMR has great potential for characterizing water retention curves of GHBSs.

Key Role Effect of Samarium in Realizing Zero Thermal Quenching and Achieving a Moisture-Resistant Reddish-Orange Emission in Ba3LaNb3O12:Sm3.

The strategy to enhance phosphor stability against thermal quenching and moisture conditions will contribute to controlling the feature of phosphor-converted white-light-emitting diodes (pc-WLEDs). Herein, an effective strategy is achieved with the incorporation of Sm3+ ions, and a robust reddish-orange emission (no thermal quenching up to 498 K) is obtained based on Ba3LaNb3O12 as a host. In light of excitation by near-ultraviolet irradiation at 408 nm, Ba3LaNb3O12:Sm3+ gives rise to a typical signal ascribed to the 4G5/2 → 6HJ/2 (J = 5, 7, 9, and 11) transitions of Sm3+ ions. The concentration quenching effect is observed when the Sm3+ content exceeds 10%, and the quenching mechanism is caused by electronic dipole-dipole interactions. Based on the narrow emission curves, a very high color purity (92.4%) could be recorded. The Sm3+ substitution at the Ba2+/La3+ site leads to a rigid structural lattice and abundant electron-trapping centers for the Sm3+ ions, which will be responsible for the zero-thermal-quenching phenomenon. In addition, oleic acid (OA) is selected to form a hydrophobic covering surface structure to protect Ba3LaNb3O12:Sm3+, which can assist in improving the moisture resistance. The most favorable parameters concerning the warm-light emission (a high general color rendering index, Ra, of 85.7 and a low correlated color temperature, CCT, of 4965 K) can be achieved in pc-WLEDs containing an OA-modified sample. Moreover, its luminous efficiency, LE, can maintain 82.9% of its initial value after 120 h under controlled environmental conditions of 85 °C and 85% humidity. These results pave a new way to optimize the sample as a potential candidate for red-emitting materials.

Heat conduction joining with the multispot focusing lens

AbstractDespite the rapid development of modern lasers, the Gaussian intensity distribution often leads to problems, especially in laser material processing. When welding wide weld seams, a top‐hat profile would often make much more sense in order to heat the weld seam as homogeneously as possible. In narrow curves, the different feed rates on the inside and outside of a wide weld seam result in further inhomogeneity. For this reason, a special optical system was developed that delivers homogeneous intensity distribution – both in straight lines and in narrow curves. The intensity distribution of a wide top‐hat profile can be changed locally and temporally by nine parallel beams. The welding head is installed on a robotic arm that travels along the weld seam and temperature homogeneity of >90 % within the spot can be achieved.

Continuous production of 3,5,5-trimethylhexanoyl chloride and CFD simulations of single-phase flow in an advanced-flow reactor

BackgroundThe combination of flow chemistry and microreactor technology is emerging in the modern chemical industry. It can link chemical engineering, organic synthesis, and green chemistry, which provides a safety guarantee for dangerous chemical processes. MethodIn view of the advantages of continuous flow synthesis, a more efficient method for the synthesis of 3,5,5-trimethylhexanoyl chloride from triphosgene and 3,5,5-trimethylhexanoic acid catalyzed by N, N-dimethylformamide was obtained by using silicon carbide microreactor, which was reported for the first time. Computational fluid dynamics (CFD) simulation of single-phase flow in an advanced microreactor was carried out with OpenFOAM software. The flow lines, lag zone, velocity distribution, pressure field, and residence time distribution (RTD) were obtained at different flow rates (5–100 mL/min). Significant findingsA continuous flow process for the 3,5,5-trimethylhexanoyl chloride with a 91% isolated yield has been reported. Triphosgene and 3,5,5-trimethylhexanoic acid were used as starting materials to achieve excellent results in the silicon carbide flow reactor, which could tolerate the corrosion of chloride ions at 55 ℃ and 0.8 MPa. In the continuous flow process, based upon the cyclic feed reaction method, the product was obtained with sufficiently high 3,5,5-trimethylhexanoic acid conversion (> 99%) and product 3,5,5-trimethylhexanoyl chloride selectivity (95%). The throughput reached 0.35 kg/h, and the purity of the final product was greater than 90% by distillation, which was in accordance with the needs of production. This new process using more polar tetrahydrofuran as the solvent was time- and cost-effective, and the obtained product had a higher yield, brighter color, and less impurity. With the increase of the flow velocity, the stagnation area and the swirling intensity increased slightly, but the velocity and pressure distribution in each mixing unit were relatively uniform. Additionally, the reactor had symmetric RTDs at all flow rates. Due to the larger flow rate, the Peclet number was increased and the axial dispersion was reduced, with the result of a narrower RTD curve.

Enhanced induction heating and self-healing performance of recycled asphalt mixtures by incorporating steel slag

Recycling reclaimed asphalt pavement (RAP) has attracted extensive attention for its environmental sustainability. As a typical industrial solid waste, steel slag with magnetic phase can facilitate the induction healing efficiency of asphalt mixtures. However, few researches focused on the healing characteristics of recycled asphalt mixtures with steel slag. Hence, this issue deserves systematic investigation. In this study, the chemical composition and static magnetic properties of steel slag with different particle size were estimated. And the induction heating performance, healing efficiency, multiple healing characteristic and healing rate after aging of their recycled asphalt mixtures were determined. The results indicate that magnetic hysteresis loops of steel slags reveal the typical narrow S-type curves, representing their magnetically soft characteristic with low coercivity. The highest Fe content and superior static magnetic properties are discovered in ASSF with particle sizes of 9.5–16 mm, and its saturation magnetization and coercivity gain up to 2.13 emu/g and 148.09 Oe. The ascending particle size of steel slag incorporated in recycled asphalt mixtures accelerates its induced temperature increment, effective heating depth and healing efficiency in contrast to the RAP addition. R7 with all component steel slag possesses the highest fracture energy of 685 J/m2 and HRE of 51.6% after healing. Healing rate of recycled asphalt mixtures grows in the previous four cycles and then start to reduce during the fifth cycle. R40 demonstrates the maximum HRS of 57.9% after the fourth cycle with a 10.7% diminution than R0, which maintains a desirable level. Long term aging boosts the attenuation degree of the self-healing performance for RAM with the increase of RAP dosage. HRAS of R40 undergone aging declines by 21.3% and merely reaches 29.1% due to the faster aging rate and inferior diffusion velocity into the cracks of recycled asphalt in recycled asphalt mixtures.

Separation of seismic multiple reflection-refraction based on morphological component analysis with high-resolution linear Radon transform

Investigating coherent noise attenuation is a continuing concern within seismic signal processing. As a common type of linear coherent noise, the multiple reflection-refraction (MRR) occurs in seismic records in which low-velocity strata overlie high-velocity strata, such as deserts, the Loess Plateau, etc. Due to its high velocity and strong energy, MRR seriously distorts the reflections and affects the interpretation. MRR has linear morphological characteristics on the shot gathers. Thus, a linear Radon transform with a surgical mute is usually applied to suppress MRR. However, significant numbers of shallow reflections are removed unintentionally in the [Formula: see text] domain when reflections overlap MRR. Therefore, a robust method that reduces the leakage of reflection energy is required. We have developed a novel method to attenuate MRR by examining the morphological difference between MRR and useful signals in the [Formula: see text] domain. MRRs are oblique linear events on the shot records, whereas the useful signals are quasi-hyperbolic events under the assumption of horizontal layers. After the high-resolution linear Radon transform, MRRs are ideally mapped into point features, whereas the useful signals are aligned with narrow curve bands in the ellipse. To better separate them in the [Formula: see text] domain, we use the morphological component analysis (MCA) theory and select the 2D stationary wavelet transform and the shearlet transform as sparse representation subdictionaries of point features and curved features, respectively. After MCA separation, we apply the inverse Radon transform to the separated MRRs and subtract them from the original seismic data. Subtraction can better preserve the amplitude of reflections. We use synthetic data and field data to illustrate the effectiveness of our method and demonstrate that making full use of the preceding morphological differences can improve the results of MRR attenuation.

Uncertainties in projections of climate extremes indices in South America via Bayesian inference

AbstractHistorical simulations and projections of climate extremes indices of precipitation and temperature were analysed over South America until the end of the 21st century through 31 general circulation models (GCMs) under four Representative Concentration Pathways. Simulations were compared with reanalysis data, and a Bayesian inference method was used to assess the uncertainties involved in the multi‐model climate projections. Regarding the precipitation extremes indices, the GCMs' simulations reasonably approached the reanalysis data, but with heterogeneous biases, both in sign and in the location of the highest values. The temperature extremes indices presented the smallest biases when compared to precipitation. Projections show a gradual growth of precipitation extremes events as the analysed radiative forcing scenario increases, both in magnitude and extent, over a large part of South America. Projections also indicate a decrease in cold days and nights and an increase in warm days and nights, more pronounced in the equatorial region. Bayesian inference method smoothed changes in precipitation extremes events, both in magnitude and extent, compared to the simple GCMs' ensemble mean. There was no considerable variation in the temperature indices when applying the Bayesian inference. Finally, the probability density functions resulted in a predominance of multimodal and wide curves for the precipitation indices, showing great uncertainties in the GCMs' results, differently from those for the temperature indices, where the GCMs presented good agreement represented through unimodal and narrow curves.

Incising and Double Impregnation of Beech Sleepers—Investigation of an Alternative Preservation System for Wooden Railway Sleepers

For nearly 200 years wooden railway sleepers are impregnated with creosote. After initially using vacuum pressure processes for impregnation, empty-cell processes have been developed quickly and are used until today. Because of political developments and its alarming properties against human health and environment the use of creosote is already restricted to certain industrial and commercially used products and will probably be banned on the European market and elsewhere in the near future. Today, most of the sleepers in track are concrete sleepers, but wooden sleepers are still essential for particular applications such as tracks with narrow curve radii, mountain tracks with uneven underground conditions and low ballast bed thicknesses, for switches, for railway bridges and for shunting stations. Without a successor product, wooden sleepers have to be installed either again without adequate protection against wood destroying organisms or will possibly be replaced by sleepers made from alternative materials like concrete, steel or polymers. The Fürstenberg-System-Sleeper, which combines a mechanical pre-treatment (incising), a double impregnation of sleepers including an alternative oily wood preservative and a water-borne copper salt as well as a modernized quality control shall on the one hand serve as an alternative to creosoted sleepers and on the other hand ensure future use of wooden sleepers in track superstructure. Incising reduced the formation of checks regarding their length, width, and depth in sleepers made from European beech (Fagus sylvatica L.) until they are sufficiently seasoned for impregnation. A decrease of the seasoning speed was not observed. During seasoning, the average global moisture content (MC) as well as the local MC showed hardly any differences between incised and not incised sleepers. Additionally, incising showed no influence on the dimensional stability, which would have reduced the number of sleepers being culled based on excessive deformation. Furthermore, positive effects on preservative retention and penetration were observed, where incising doubled the penetration depth up to over 30 mm and increased the mean retention from 46.5 to 72.0 kg/m3. During double impregnation with the water-borne preservative first and the oily preservative afterward, it became evident, that a gross weight of at least 950 kg/m3 was needed for penetrating the peripheral area of the sleepers to achieve an additional homogenous envelope treatment during the second impregnation with an average retention of approximately 30 kg/m3.

Tuning the Metal-Insulator Transition Properties of VO2 Thin Films with the Synergetic Combination of Oxygen Vacancies, Strain Engineering, and Tungsten Doping.

Vanadium oxide (VO2) is considered a Peierls–Mott insulator with a metal–insulator transition (MIT) at Tc = 68° C. The tuning of MIT parameters is a crucial point to use VO2 within thermoelectric, electrochromic, or thermochromic applications. In this study, the effect of oxygen deficiencies, strain engineering, and metal tungsten doping are combined to tune the MIT with a low phase transition of 20 °C in the air without capsulation. Narrow hysteresis phase transition devices based on multilayer VO2, WO3, Mo0.2W0.8O3, and/or MoO3 oxide thin films deposited through a high vacuum sputtering are investigated. The deposited films are structurally, chemically, electrically, and optically characterized. Different conductivity behaviour was observed, with the highest value towards VO1.75/WO2.94 and the lowest VO1.75 on FTO glass. VO1.75/WO2.94 showed a narrow hysteresis curve with a single-phase transition. Thanks to the role of oxygen vacancies, the MIT temperature decreased to 35 °C, while the lowest value (Tc = 20 °C) was reached with Mo0.2W0.8O3/VO2/MoO3 structure. In this former sample, Mo0.2W0.8O3 was used for the first time as an anti-reflective and anti-oxidative layer. The results showed that the MoO3 bottom layer is more suitable than WO3 to enhance the electrical properties of VO2 thin films. This work is applied to fast phase transition devices.