Abstract The velocity of laser-induced shock waves affects the efficiency and efficacy of laser-based processes. The ability to accurately estimate shock wave velocity is critical for optimizing ...experimental combinations, creating laser-based systems, and assuring desired results. Traditional approaches to predict shock wave velocity involve empirical equations and analytical models based on simplified assumptions. However, these methods often lack accuracy and fail to capture the complex dynamics of laser-matter interactions. To overcome these limitations, we used a combination of an artificial neural network and a genetic algorithm to predict shock wave velocity. In this method, the neural network structure is dynamically designed. The optimization method does this by modifying the neural network's weights and figuring out the network's structure on our behalf. Based on the findings, our suggested technique worked very well; it surpassed other comparison methods by achieving the lowest average errors in terms of RMSE and MAE, which are 4.38 and 3.74, respectively. Moreover, the analysis has shown that our proposed method has a high level of reliability in predicting impulsive wave velocity using a neural network.
Using a focused ion beam TTX-NHT3 Nanoindentation tester with a load of 500 mN, we study the micromechanical properties of laser-deposited AlCoCrFeNiCu high entropy alloy coatings. The indentation ...tests conducted were used to examine the influence of laser power and scan speed on the elastic modulus and hardness of the alloy coatings using the Oliver & Pharr method. There were several indentation points impressed and used to extract the mechanical properties of the alloys, and the results of the alloy were compared with that of the A301 steel substrate. The results showed the mean value of the NanoHardness and Elastic modulus of the high entropy alloy were 2.769 GPa and 149 GPa, respectively. The Vickers hardness showed a 60% decline as the laser power increased from 1200 W to 1600 W. The hardness and the elastic modulus were proportional to each other, both increasing with a decrease in the indentation depth and laser power. The laser-deposited high entropy alloys were more resistant to plastic deformation and had improved mechanical properties than the steel substrate attributed to the solid-solution hardening and lattice distortion effect of the BCC phase structure and aluminium contents, respectively.
Abstract
Superhydrophobicity is also known as lotus effect which makes the water to roll off and bounce when liquid droplets resting on the surface. In nature it is used by plants for self-cleaning ...purpose and by animals for anti-adhesion skin. The superhydrophobic surface has been mimicked and used in the field of aerospace, textiles, power line, solar cell and so on. In this review we provide the basic theories of wetting, wetting transition models of superhydrophobicity, parameters of laser beam and post processing (heat treatment only) after laser irradiation related to contact angle. Laser parameters play a vital role in producing surface topography. The surface topography may be consists of ripples, dual surface roughness on the laser textured surface. Based on the magnitude of laser parameters the different surface morphology can be obtained. The surface morphology will vary for the different laser system such femto, pico or nano second laser system. The present review aims to report the understanding of laser parameters in order to texture the expected surface structure by controlling the laser parameters.
•The effects of process parameters and interactions on the laser repair performance of esophageal tissue were studied by designing laser power, scanning speed, defocusing amount and scanning path ...through orthogonal experiment.•The degree of thermal damage was assessed by calculating the esophageal microtissue characteristic parameters and the degree of collagen thermal deformation.•Laser power and interaction factor laser power and scanning path were the most important factors affecting the burst compression strength.•At laser power of 6 W, scanning speed of 150 mm/s, defocusing amount of 0 mm, and scanning path 3, the bursting pressure strength of esophageal tissue was highest at 93.3 mmHg, and the thermal damage of the tissue was minimum.
To study the influence of laser parameters on the mechanical properties and thermal damage of esophageal tissue, the experiment of laser repair of esophageal tissue incision is made. The effects of parameters including the laser power, scanning speed, defocusing amount, scanning path on the bursting pressure strength of esophageal tissue are analyzed. The influence of different energy densities on the appearance of esophageal tissue morphology, microstructure, and the degree of thermal denaturation of collagen is analyzed. The results showed that the laser power and the interaction factor of laser power × scanning path is the most important factor affecting the bursting pressure strength of esophageal tissues. The optimal parameters are laser power 6 W, scanning speed 150 mm/s, defocusing amount 0 mm, and scanning path 3, the highest bursting pressure strength of 93.3 mmHg is achieved. Meanwhile the esophageal tissues do not show obvious scarring, and the degree of thermal denaturation of tissue collagen is the smallest, which is only 1.6 × 10-5, the texture of the tissue microscopic images is uniformly changed, and the texture clarity is high.
The Sm2O3-activated barium calcium strontium borate (BCSrSm) glasses were prepared via the melt-quenching route, and investigates important parameters such as absorption spectra, excitation, and ...luminescence, lifetime decay and luminescent color. The absorption-spectra exhibits ten absorption transitions related to the ground state (6H5/2)-to-excited states. The JO-parameters trend obtained for BCSSm glasses is as Ω4 > Ω6 > Ω2. The lower value of Ω2 of Sm3+ ions indicates weaker samarium-oxygen-bond’s covalency. High optical gain and high figure of merit, predicting the amplification of the laser medium, are relatively larger for 4G5/2→6H7/2. The alteration in the local environment around Sm3+ ions influence transitions’ intensities. Concentration quenching effect was observed for 0.5 mol% of Sm3+-ions concentration. the measured values are 1.732–0.706 ms and decreases as the content increases from 0.1 to 1.5 mol%. The CIE chromaticity coordinates of all glasses locate in the orange region and CCT 1720 K, showing the promising candidature of the present glasses for orange laser materials and display-devices applications.
A data-driven approach combining together the experimental laser soldering, finite element analysis and machine learning, has been utilized to predict the morphology of interfacial intermetallic ...compound (IMC) in Sn-xAg-yCu/Cu (SAC/Cu) system. Six types of SAC solders with varying weight proportion of Ag and Cu, have been processed with fiber laser at different magnitudes of power (30−50 W) and scan speed (10−240 mm/min), and the resultant IMC morphologies characterized through scanning electron microscope are categorized as prismatic and scalloped ones. For the different alloy composition and laser parameters, finite element method (FEM) is employed to compute the transient distribution of temperature at the interface of solder and substrates. The FEM-generated datasets are supplied to a neural network that predicts the IMC morphology through the quantified values of temperature dependent Jackson parameter (αJ). The numerical value of αJ predicted from neural network is validated with experimental IMC morphologies. The critical scan speed for the morphology transition between prismatic and scalloped IMC is estimated for each solder composition at a given power. Sn-0.7Cu having the largest critical scan speed at 30 W and Sn-3.5Ag alloy having the largest critical scan speed at input power values of 40 W and 50 W, thus possessing the greatest likelihood of forming prismatic interfacial IMC during laser soldering, can be inferred as most suitable SAC solders in applications exposed to shear loads.
•Various colors were achieved on the Ti-based metallic glass by nanosecond laser irradiation.•Periodic wrinkles appeared on the colored surfaces with the decreasing overlap rate.•The coloration ...mechanism was discussed by analyzing surface morphology and chemical composition.
Laser coloration is an emerging technique for surface functionalization of metallic glasses (MGs). Understanding the influence of laser parameters on surface color of MGs will accelerate their commercialization. Herein, surface coloration was conducted on a Ti-based MG, and the hue–saturation–intensity (HSI) color space was employed to evaluate color variation. Various colors were achieved by varying the average power and scanning speed in an ambient atmosphere. The results indicated that the overlap rate and number of repetitive scans had a negligible effect on the color and significantly changed the microscopic morphology. The irradiated surfaces were yellowish and colorless in nitrogen and argon atmospheres. Furthermore, the effect of morphology on the surface color and the mechanism of surface coloration were examined. This study demonstrates that nanosecond laser irradiation is an effective method for achieving surface coloration of MGs, which is expected to enrich the surface functionality of MG products.
Laser texture has been widely used in the fields of mechanical production， precision medical treatment， and material surface modification， because of its high precision， high speed， and low ...environmental pollution.Over the past 30 years， related researches have entered a stage of vigorous development， with the emergence of ultrafast laser texture technology.However， due to the wide variety of geometric topography and various arrangements and combinations，problems such as poor universality of parameter design in different materials still hinder the development of laser textured friction reduction research.Therefore， this work reviewed the development history of laser texture friction reduction researches from the aspects of geometrictopography， dimensional parameters， laser parameters， lubrication conditions， etc.The influences of the laser texture’s geometry topography， parameters and working conditions on the tribological properties were discussed， and the friction reduction mechanism of the laser texture un
This study reports a detailed evaluation of how key parameters of operation influence the measurement of sulfur isotopes using laser ablation multiple collector inductively coupled plasma mass ...spectrometry (LA-MC-ICP-MS). Sulfur isotopes are observed to display a fractionation up to 2‰ δ34S during analysis of pyrite with different laser parameters using a 193nm ArF excimer laser. In order to understand why the laser parameters affect S isotope fractionation when measuring S isotopes in pyrite, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) techniques were used to characterize debris formed during the ablation of pyrite, i.e., morphology and speciation of phases. The results show that pyrite decomposes to two phases: ball-like troilite (FeS) and a sulfur-rich floc-like agglomeration surrounding the troilite. The measured δ34S values vary due to the different proportions of troilite balls and the floc-like material generated under different laser parameters. The proportion of troilite and S was evaluated with a LA-(Quadrupole)-ICP-MS through direct comparison of the counts per second (CPS) ratio of 56Fe to 32S. In contrast to pyrite, natural pyrrhotite shows no decomposition process and the particle size of the debris from pyrrhotite is nearly 10 times larger than that of pyrite (~5μm for pyrrhotite compared to <1μm for pyrite). Therefore, a biased analysis of pyrite may happen using laser ablation although this problem can be minimized using high raster velocity. Last but not least, we provide a case study of S isotope mapping using high raster velocity, which extends the application of the in-situ S isotope analysis technique. The results here carry implications for the choice of settings needed to obtain accurate LA-MC-ICP-MS S-isotope maps of pyrite.
Display omitted
Eu3+ ions were successfully doped in two restricted matrices; Silica sol-gel matrix and silica-ethylene glycol (EG) hybrid matrix (modified sol-gel matrix) with different concentrations to produce ...transparent silica xerogel Eu samples having no cracking and to select the optimum concentration which then doped with different concentrations of ZnO (as sensitizer) via modified sol-gel method to produce Eu composite zinc oxide. The concentration 2.5wt% was detected as optimum concentration of Eu3+and 0.625% wt for ZnO in modified sol-gel matrix. The compositional dependences of Judd–Ofelt and laser parameters of Eu3+ ions in studied matrices were evaluated and discussed. The FTIR spectrum of the prepared restricted samples was recorded and all structural changes in the samples prepared have been studied. The experimental dipole strengths were calculated from the areas under the absorption bands. The evaluated Judd-Ofelt parameters (Ωλ), using the observed spectral intensities, have been used to calculate various laser parameters viz., spontaneous emission probability (A), radiative life time (τ), fluorescence branching ratio (β) and stimulated emission cross section (σp). The effects of EG and ZnO on optical and lasing parameters of the samples were also discussed.
PDF
