Overlap Rate Research Articles

Manipulating scanning strategies towards controlled microstructure of laser remelted Mg–3Al–1Zn alloy

Various laser scanning strategies of multitrack products, consisting of a default Raster pattern (R1), a Raster pattern with a changed line order (R2), and a default Zigzag pattern (Z1), with different overlap rates ranged from 0.7 to 0.5, have been conducted to investigate microstructure evolution for Mg–3Al–1Zn alloy. As the overlap rate changes from 0.7 to 0.5, the average grain size decreases and the texture is slightly concentrated, except for R2 pattern. For effect of different scanning pattern, a relatively small average grain size can be obtained using the R1, R2 patterns compared to using the Z1 pattern; a relatively weak texture can be obtained using the R1, Z1 patterns compared to using the R2 pattern. The utilization of Z1 pattern results in a further texture weakening compared to that of the R1 pattern. Microstructure evolution of scanning strategy is mainly determined by low-undercooling-required epitaxial growth along temperature gradient directions at the solid/liquid interface. Combined with computational thermal-fluid dynamics simulation, a strong fluid flow within the molten pool promotes side expansion of the molten pool, resulting in the larger overlap area, the corresponding three-times remelting domain and continuous deflections of grain major axes.

Optimization model for multibeam sounding line deployment based on genetic algorithm

Multibeam sounding technology is a cutting-edge method used for measuring underwater topography, widely applied across various fields. The actual seafloor terrain often exhibits significant fluctuations, leading to challenges such as insufficient coverage in shallow areas and excessive overlap in deep-water zones, resulting in inefficient operations. Rational selection of line spacing helps improve measurement efficiency and ensures data integrity. In this paper, taking the 2023 National College Student Mathematical Modeling Competition Problem B as a background, we conduct a thorough analysis of the variation patterns of the coverage width of multibeam sounding strips with respect to various parameters. We establish models for ocean depth and coverage width, determining how the strip coverage width changes with distance and the angle between survey lines in different scenarios. Finally, employing genetic algorithms and differential methods, we identify decision variables, objective functions, and constraints to formulate a nonlinear programming model. Through iterative searches, we obtain an optimal sounding line deployment plan that maximizes coverage of the target sea area while keeping the overlap rate below 20%. The calculated missed measurement error is approximately 32.774%, and the overlap rate is around 10.477%, indicating a high level of model accuracy.

Construction of line Layout Model Based on Geometric Deduction and Constrained Heuristic Search

Based on problem B of the National Mathematical Contest in Modeling for College Students in 2023, this paper establishes a model through geometric deductive deduction, and establishes and solves an optimal model of survey line layout through constrained heuristic algorithm. In problem 1, a mathematical model of coverage width and overlap rate is established based on triangle relation and triangle sine theorem by finding the mathematical relationship between target quantity and known quantity. In problem 2, the angle between the known direction of the survey line and the projection of the normal direction of the submarine slope on the horizontal plane is . We can imagine a surface perpendicular to the direction of the measurement line, and then find the slope of the imaginary surface according to the geometric relationship, and replace the slope Angle of problem 1 with the imaginary slope Angle to obtain the mathematical model of the coverage width. Based on this, the constraints of the Angle and overlap rate of the line are added, and the problem 3 is simplified into the optimization problem of multiple routes in problem 2. Finally, by changing the parameter setting of slope Angle in the model, the sensitivity analysis is carried out, and it is found that the model is stable and reliable.To sum up, the problems from one to four are gradually deepened and progressively advanced, and the development of Marine survey field is facilitated by establishing a model of depth survey line layout.

Research on Multibeam Bathymetric System Based on Greedy Algorithm and Variable Step Size Traversal Algorithm

Multi-beam bathymetry system is an advanced technology to measure the seabed based on single-beam bathymetry. In this paper, the greedy algorithm and variable step traversal method will be used to establish the mathematical models of coverage width and overlapping rate of adjacent strips of multi-beam sounding, and the best scheme of survey line layout will be designed by establishing the optimization model. According to the established mathematical model of overlap rate, the mathematical model of coverage width of multi-beam sounding in three-dimensional rectangular waters is optimized. Finally, according to the real life, with the overlapping rate of adjacent strips within 10% to 20% as the limiting condition and the minimum total length of survey lines as the objective function, a single-objective optimization model is established. Then, Python is used to solve the problem through greedy algorithm and variable step-size traversal algorithm, and it is found that the included angle of survey line direction in the optimal scheme is 90, and the minimum total length of survey line is 68 nautical miles. Stability analysis is carried out by changing the constraint range of overlap rate.

Effect of energy distribution on laser cleaning quality of 30Cr3 ultra-high strength steel

30Cr3 is a novel ultra-high strength steel (UHSS) with excellent strength and plastic toughness, which has been mainly used in aerospace shells and stressed parts. Currently, there is still a lack of systematic research and comprehensive evaluation on the laser cleaning of this particular material. In this study, a nanosecond pulsed laser was employed for the cleaning process. First, the energy distribution model was derived, the influence of the spatial and temporal distribution of laser energy on the cleaning quality was discussed, and the cleaning experiment was conducted. The results showed that a laser energy density of 15 J/cm2, combined with the beam overlap rate 52% in the x-direction and 61% in the y-direction, can effectively remove the oxide layer and thoroughly expose the natural metal matrix. Then, under the optimum parameters, the oxygen content decreased from 22.3% to 3.4%, the Fe content increased from 54.5 to 83.4%, the Fe3+ peak disappeared in the X-ray photoelectron spectroscopy (XPS), a remelted layer of only 1 μm was observed. Last, the roughness was slightly reduced from 3.573 μm to 2.985 μm, the hardness was restored to the original hardness level of the substrate (∼260 HV), and the electron back scatter diffraction (EBSD) showed that the structure hardly changed after cleaning, the grain size was comparable to that of the matrix. These findings indicated that laser cleaning can effectively remove the oxide layer of 30Cr3 UHSS without damaging the properties of the base material, which has promising application in the cleaning of UHSS.

Genetic Algorithm Based Path Planning for Seawater Depth Data Measurement in Real Scenarios

In this paper, firstly, the movement direction of the measuring ship is clarified, and according to the requirements of factors such as the range of overlap rate is controlled at 10% to 20% and the sea area is completely covered, the optimization equation system is derived, and the objective function is derived through the requirements, and the optimal solution can be derived from the two associations as the 34 measuring lines and the total length of 68 nautical miles of the shortest measuring lines. Using genetic algorithm to examine the real scene of seawater depth data measurement path planning, the length of the measurement line and coverage as an assessment index of the algorithm's subsequent optimization of the object of choice. Through the simulation of genetic mutation, crossover and selection operations, the total length of the shortest survey line is 21.5261 nautical miles, the percentage of missed sea area is 1.6%, and the overlap rate is 13.12% after the iterative solution of the genetic algorithm.

The overlap rate influences the microstructure and properties of laser-cladded Fe-Ni-Ti composite coatings

The overlap rate has a significant impact on the quality and performance of laser cladding coatings. In order to prepare high wear-resistant laser cladding coatings. Single and multi-pass Fe-Ni-Ti composite coatings were prepared on the surface of 45 steel using a semiconductor laser. The microstructure and phase composition of the fusion layers were analyzed using metallographic microscopy, XRD diffraction, scanning electron microscopy, and energy dispersive spectrometry. Friction coefficients and microhardness of fusion layers with different overlap ratios were tested using a multifunctional surface performance tester and a microhardness tester. The wear performance of coatings with different overlap ratios was tested using a wear testing machine.The results indicate that when 6% Ti was simultaneously added to the Invar alloy matrix during the laser fusion of Fe-Ni-Ti alloy coatings, the phase composition of the fusion layer mainly consists of γ-[Fe, Ni] austenite, Fe3Ni2, α-Fe, and other metallic compounds. Simultaneously, in-situ formation of TiC reinforcement is dispersed in the matrix of γ-[Fe, Ni] solid solution. When the overlap ratio is 46%, the fusion layer exhibits a uniform, dense structure with fewer defects and higher coating hardness, resulting in improved wear resistance. At this point, the microhardness of the fusion layer is 450 HV, 1.5 times that of the substrate material and 2.2 times that of the base material. The friction coefficient on the coating surface is 0.412, with a percentage weight loss of 0.17%. The wear theory of the cladding layer is mainly adhesive wear, which also includes abrasive wear.

Finite element simulation analysis of flow heat transfer behavior and molten pool characteristics during 0Cr16Ni5Mo1 laser cladding

0Cr16Ni5Mo1 super martensitic stainless steel has excellent weldability and is an economical material with a high life cycle and low cost, but there are few researches and applications of this material in additive manufacturing. In order to realize the application of 0Cr16Ni5Mo1 large-area laser cladding technology, the multi-track lap cladding of the material was studied. In this work, a multi-physical finite element model of multi-layer multi-track laser cladding was established, taking into account thermodynamic processes such as phase transition, Marangoni convection, and buoyancy. The flow and heat transfer behavior of 0Cr16Ni5Mo1 in multi-layer multi-track laser cladding process and the characteristics of the molten pool are studied. The research focused on the flow heat transfer behavior and molten pool characteristics of 0Cr16Ni5Mo1 during multi-layer multi-track laser cladding. The discussed aspects include the evolution history of the temperature field within the molten pool, flow field characteristics, molten pool dimensions, and dilution ratio under various laser powers and overlap rates. The results show that with the increase of overlap rate, the morphology of molten pools in different clad tracks will also change, and the flow rate, dilution ratio, and length of molten pools in the second track are negatively correlated, while the temperature and height of molten pools are positively correlated. As the laser power increases, all the characteristic quantities are positively correlated with it.

Application of Python-Based Abaqus Secondary Development in Laser Shock Forming of Aluminum Alloy 6082-T6.

Aluminum alloy 6082-T6 is an important material for manufacturing the outer skin of high-speed trains, and laser shock forming can realize the rapid forming of complex-shaped plates. In order to improve the efficiency of the simulation modeling of laser shock forming for aluminum alloy 6082-T6, Python scripting language was used for the secondary development of Abaqus. A plugin was utilized to simulate and analyze the laser shock forming process of aluminum alloy 6082-T6. The coordinates of the plate after laser impact molding were measured using a coordinate measuring machine to calculate the arc bow height of the plate. The accuracy of the simulation model was verified by comparing with the simulation results. The deformation characteristics of plastic strain and arc height of aluminum alloy 6082-T6 under different laser process parameters were analyzed. The simulation plugin has a concise interface, high operability, and accurate results with the other parameters unchanged. When the laser energy is 5 J, 6 J, and 7 J, the corresponding arc heights are 5.9 mm, 6.6 mm, and 7.2 mm, respectively. As the thickness of the sheet increases, the deformation changes from concave at 1 mm to convex at 2 mm, 3 mm, 4 mm, and 5 mm. As the spot size increases from 1 mm to 5 mm, the transmission mode of the shock wave gradually changes from spherical wave to planar wave, and the arc height of the sheet increases from 4.6 mm to 8.2 mm. With the increase in the spot overlap rate, the impact area accumulates residual stress, and the arc height of the sheet is 5.7 mm, 6.6 mm, 7.3 mm, and 8.5 mm, respectively. The secondary development of ABAQUS 2021 using Python 3.6 scripting language has improved the efficiency of simulation modeling and provided reference for rapidly predicting the deformation characteristics of aluminum alloy 6082-T6 under different laser process parameters.

Effect of overlap rate on the microstructure and corrosion behavior of pure copper laser cladding

Effect of overlap rate on the microstructure and corrosion behavior of pure copper laser cladding

Optimization of laser-texturing process parameters of Ti6Al4V alloys using metaheuristic algorithms

Manufacturing microscale textures can reduce friction and wear compared with smooth surfaces. In laser surface texturing, the resulting texture geometry is directly affected by laser parameters such as laser power, scanning speed and overlap rate. Therefore, finding the optimal parameter settings to improve the process performance is crucial. One of the biggest challenges encountered during the optimization stage is accurately determining the functional relationship between surface quality and process parameters. Another significant problem is solving the nonlinear equation system. This study aims to investigate the effect of laser-textured surfaces on the tribological behavior of titanium Ti6Al4V. Optimization of laser texture process parameters using metaheuristic algorithms is a hot topic. The first contribution of this study is the modeling of the contact angle, kurtosis and skewness quality parameters of Ti6Al4V titanium alloy based on the polynomial curve fitting method as a function of laser power, laser speed and overlap rate. Another significant contribution is to optimize the proposed nonlinear regression models using metaheuristic approaches such as genetic algorithm, particle swarm optimization, whale optimization algorithm, gray wolf optimization, equilibrium optimizer, teaching-learning-based optimization, student psychology-based optimization (SPBO), slime mould algorithm and social network search. The reason for using many metaheuristics is to test the effectiveness of different metaheuristic methods in solving this problem. Analysis of variance was performed to evaluate experimental data and compare the success of optimization methods. The results revealed that the proposed metaheuristic methods can be applied to the related problem. It has been observed that the methods give identical results. Among these methods, the SPBO method provided the best performance in the optimization of all laser output parameters.

Study of the effect of overlap rate on the failure form, microstructure and wear resistance of multilayer laser cladding on grey cast iron surfaces

Laser cladding is less used in the repair of cast iron parts. In this paper, multiple layers of austenitic stainless steel powders with different overlap rates were laser clad by the process of adding a transition layer to explore the feasibility of multilayer cladding of grey cast iron. The study results show that the higher cladding layers tends to cause cracking and warping of substrate, and the increased overlap rate of the Ni transition layer can effectively inhibit these failures. The wear mass of Fe-based coatings with 33.3%∼66.7% overlap was 1.00–2.68 mg. After wear, the Fe2p and Ni2p potentials were shifted, the intensity of the O1s characteristic peaks increased, and the wear oxidation increased wear quality loss.

Spatial Pattern of Intraprostatic Recurrence after Definitive External-Beam Radiation Therapy for Prostate Cancer: Implications for Focal Boost to Intraprostatic Dominant Lesion

Background/PurposeWe retrospectively investigated spatial pattern associations between primary and recurrent tumor sites following definitive external-beam radiation therapy (EBRT) for prostate cancer, using positron emission tomography/computed tomography (PET/CT) with a prostate-specific membrane antigen (PSMA)-targeted probe, 18F-FSU-880. MethodsAmong the patients who received PET/CT with 18F-FSU-880 in a phase 2 trial, which evaluated the tumor detection efficacy of PSMA-PET/CT for recurrent prostate cancer, patients with local intra-prostatic recurrence detected by PSMA-PET/CT following definitive EBRT were retrospectively analyzed. The prostate and seminal vesicles were divided into 14 sections in total. Two diagnostic radiologists separately re-evaluated the intra-prostatic location of the primary tumor on magnetic-resonance imaging and that of the recurrent tumor on PSMA-PET/CT, respectively, and the rate of overlap between primary and recurrent tumors was calculated. The overlap rate was defined as “the number of sections which overlapped between the primary tumor and recurrent tumor” divided by “the total number of sections of recurrent tumor”. A recurrent tumor was considered to be at the same location with an overlap rate equal to or greater than 75%, and a partial overlap was defined as an overlap rate between 25 and 74%. ResultsTwelve patients had local recurrence detected by PSMA-PET/CT. The median time to the diagnosis of local recurrence was 9.1 (range: 2.2–12.3) years after definitive EBRT.The recurrent tumor was detected at the same location in 25.0%, and a partial overlap was noted in 41.7%. ConclusionsLocal intra-prostatic recurrence after definitive EBRT often occurs at the same site or at a partially overlapping site adjacent to the primary IPDL. Our results support the merit of focal dose-escalation for intra-prostatic dominant lesions in definitive EBRT.

Multi-Beam Line Measurement Model Based on Analytic Geometry

The multi-beam sounding system has a wider coverage area and efficiency than the single-beam sounding system, and has been used in a variety of offshore operations. However, the design of flat sea area survey method can not meet the real seabed relief, so it is of great significance to study a multi-beam sounding system line planning model for different seabed topography to improve the measurement efficiency and accuracy in sea area exploration and other applications. In this paper, under the condition of real terrain, the linear model of the Angle of the fixed multi-beam transducer is studied with appropriate simplification. Based on the analytic geometric relationship, the functional expressions between the coverage area and overlap rate and the parameters of the transducer's open Angle, slope Angle and sea water depth are given, and the parameter model of the submarine landform linear model with a certain slope is established.

Prediction Method for High-Speed Laser Cladding Coating Quality Based on Random Forest and AdaBoost Regression Analysis.

The initial melting quality of a high-speed laser cladding layer has an important impact on its post-treatment and practical application. In this study, based on the repair of hydraulic support columns of coal mining machines, the influence of high-speed laser cladding process parameters on the quality of Fe-Cr-Ni alloy coatings was investigated to realize the accurate prediction of coating quality. The Taguchi orthogonal method was used to design the L25(56) test. The prediction models of the relationship between the cladding process and the coating quality were established using the Random Forest (RF) and AdaBoost (Adaptive Boosting, AB) algorithms, respectively. Then, the prediction accuracy of the two models was compared, and the process parameter features were screened for importance evaluation. The results show that the AB prediction model is more accurate than the RF prediction model and more sensitive to abnormal data. The importance evaluation based on the AdaBoost model shows that the scanning speed has a great influence on the height and surface roughness of the coating. On the other hand, the overlap rate is the most important factor in controlling the dilution ratio and near-surface grain size of high-speed laser melting coatings. In addition, the micro-hardness of the coating and the thermal effect of the substrate can be effectively enhanced by adjusting the laser power and scanning speed. Finally, it was verified that the AB prediction model could accurately estimate the quality indexes of the coating with a prediction error less than 6%. The results show that it is feasible to predict the quality of high-speed laser cladding with the AB algorithm. It provides a basis for the adjustment of process parameters in the subsequent quality control process of cladding.

Wood-inspired metamaterial catalyst for robust and high-throughput water purification

Continuous industrialization and other human activities have led to severe water quality deterioration by harmful pollutants. Achieving robust and high-throughput water purification is challenging due to the coupling between mechanical strength, mass transportation and catalytic efficiency. Here, a structure-function integrated system is developed by Douglas fir wood-inspired metamaterial catalysts featuring overlapping microlattices with bimodal pores to decouple the mechanical, transport and catalytic performances. The metamaterial catalyst is prepared by metal 3D printing (316 L stainless steel, mainly Fe) and electrochemically decorated with Co to further boost catalytic functionality. Combining the flexibility of 3D printing and theoretical simulation, the metamaterial catalyst demonstrates a wide range of mechanical-transport-catalysis capabilities while a 70% overlap rate has 3X more strength and surface area per unit volume, and 4X normalized reaction kinetics than those of traditional microlattices. This work demonstrates the rational and harmonious integration of structural and functional design in robust and high throughput water purification, and can inspire the development of various flow catalysts, flow batteries, and functional 3D-printed materials.

Uncommon de novo EGFRT790M-Mutant NSCLC characterized with unique genetic Features: Clinical response and acquired resistance to the third-generation EGFR-TKIs treatment

IntroductionThe literature on de novo EGFRT790M-mutant patients diagnosed with lung cancer is limited, and there is currently no consensus concerning the most effective treatment protocols. This study aimed to investigate the genomic characteristics of de novoEGFRT790M-mutant non-small cell lung cancer (NSCLC) and provide insights into its clinical response and resistance mechanism to third-generation EGFR-TKIs. MethodsNext-generation sequencing was utilized to screen a substantial cohort of 4,228 treatment-naïve patients from the Mygene genomic database to identifythe de novo EGFR-T790M mutation. Meanwhile, we recruited 83 individuals diagnosed with lung cancer who harbored de novo EGFRT790M mutation in the real world. In addition, 166 patients who acquired EGFR-T790M mutation after becoming resistant to first- or second-generation EGFR-TKIs were included as a comparison cohort. ResultsDe novo EGFRT790M mutation identified by next-generation sequencing is rare (∼1.3 %) in Chinese lung cancer patients. The relative variant allele frequency (VAF) of de novo EGFRT790M mutation was either comparable to or significantly lower than those of EGFR-activating mutations. Patients with de novo-T790M mutations exhibited less favorable clinical outcomes when administered third-generation EGFR-TKIs as first-line therapy thanthose with 19del mutationsdue to a high overlap rate in EGFR p.L858R mutation. In patients with a de novo EGFRT790M mutation, no correlation was observed between T790M clonality and treatment outcomes with third-generation EGFR-TKIs. In contrast, the sub-clonality of the T790M mutation detrimentally affected the third-generation EGFR-TKI treatment efficacy in patients with acquired T790M mutation. Potential resistance mechanisms of third-generation EGFR TKIs in NSCLC patients with de novo or acquired EGFRT790M mutations included EGFR p.C797S in cis or EGFR p.E709X mutation, as well as activation of bypass pathways. ConclusionsThe present study characterized the uncommon but unique de novo EGFRT790M-mutant NSCLC and laid a foundation for designing future clinical trials in the setting of uncommon EGFR mutation.

Effect of Different Laser Parameters on Surface Physical Characteristics and Corrosion Resistance of 20 Steel in Laser Cleaning

The rusting of metals brings huge losses to the industry every year, and post-treatment of rusted metals to restore their properties to the initial state is a hot topic of current research. In particular, 20 steel, which is widely used in various structural components such as ships, is prone to oxidation in atmospheric environment. Therefore, in this study, a nanosecond pulsed laser was used to remove the rust layer on the surface of 20 steel. The effects of different energy densities and spot overlap rates on the roughness, surface morphology, chemical composition, microhardness and corrosion resistance of the rust layer were analyzed. The results showed that the best cleaning effect was achieved at an energy density of 4.26 J/cm2 and a spot overlap rate of 75%. Under these conditions, the rust layer was completely removed without damage to the substrate, and it even improved the corrosion resistance of 20 steel. At energy densities of 1.42 J/cm2 and 2.84 J/cm2, the rust layer was not completely removed, while at 5.68 J/cm2, the rust layer was removed but the substrate was damaged. In addition, the mechanism of rust removal and substrate damage is discussed.

Multi-View consistency-based point cloud registration method with low overlap rate

Accurate and efficient workpiece measurement is crucial for workpiece processing and quality monitoring. Non-contact optical measurement methods have gained more attention due to their simplicity, efficiency, and flexibility compared to complicated and inefficient contact measurement methods. Multi-view registration of measurement data is a key issue in workpiece measurement, as it relies on the system’s geometric accuracy and motion stability, presenting challenges such as the insufficient overlap of multi-viewpoint cloud data and cumulative error. To address these challenges, this paper proposes a multi-view planning and registration algorithm with a low overlap rate. The multi-view planning algorithm employs a greedy method to plan the scanning viewpoints of the workpiece to obtain complete point cloud data efficiently. The multi-view registration algorithm extracts features using a multi-scale geometric feature extraction network, matches the features based on the Hungarian algorithm, builds a graph, and optimizes workpiece positions based on the G2O algorithm for multi-view registration, effectively reducing cumulative error. Measurement experiments on blade workpieces confirm the feasibility of the proposed algorithms.

Size effect of femtosecond laser helical drilling on nickel-based single crystal superalloy

Femtosecond laser has gradually become a reliable tool for processing high-quality film cooling holes (FCHs) of turbine blades in recent years. However, in the case of turbine blades with a variety of aperture drilling requirements, the influence of aperture on drilling quality and its internal causes are ignored. In this paper, the “size effect” of different aperture holes prepared by femtosecond laser helical drilling method was analyzed and compared in terms of geometric features, machining efficiency, hole wall ablation and drilling evolution process, and the formation mechanism of the “size effect” were revealed from the aspects of removal efficiency, laser spot overlap rate, energy shielding effect and residues discharge capacity. The results show that with the increase of laser scanning diameter D, the taper of the hole increases, the drilling efficiency increases first and then decreases, and the surface of hole wall is transformed from microvoids, microcracks and adhesive oxide residues into a regular nanostripes. The increase of D makes the radial spot overlap rate Pr decrease significantly, and Pr seriously affects the removal efficiency and thermal effect on the hole wall, which should be adjusted according to different apertures. Thermal accumulation and laser energy utilization rate attenuation caused by the energy shielding effect are the most important factors that deteriorate the processing quality and reduce the processing efficiency during femtosecond helical drilling. Therefore, for smaller aperture drilling, the strategy of process adjustment is to increase residues discharge capacity.