Estimation of peak wave period from surface texture motion in videos

Wave information retrieval from videos captured by a single camera has been increasingly applied in marine observation.However,when the camera observes ocean waves at low grazing angles,the accurate extraction of wave information from videos will be affected by the interference of the fine ripples on the sea surface.To solve this problem,this study develops a method for estimating peak wave periods from videos captured at low grazing angles.The method extracts the motion of the sea surface texture from the video and obtains the peak wave period via the spectral analysis.The calculation results captured from real-world videos are compared with those obtained from X-band radar inversion and tracking buoy movement,with maximum deviations of 8%and 14%,respectively.The analysis of the results shows that the peak wave period of the method has good stability.In addition,this paper uses a pinhole camera model to convert the displacement of the texture from pixel height to actual height and performs moving average filtering on the displacement of the texture,thus conducting a preliminary exploration of the inversion of significant wave height.This study helps to extend the application of sea surface videos.

Targeting new ways for large-scale,high-speed surface functionalization using direct laser interference patterning in a roll-to-roll process

Direct Laser Interference Patterning(DLIP)is used to texture current collector foils in a roll-to-roll process using a high-power picosecond pulsed laser system operating at either fundamental wavelength of 1064 nm or 2nd harmonic of 532 nm.The raw beam having a diameter of 3 mm@1/e^(2) is shaped into an elongated top-hat intensity profile using a diffractive so-called FBS■-L element and cylindrical telescopes.The shaped beam is split into its diffraction orders,where the two first orders are parallelized and guided into a galvanometer scanner.The deflected beams inside the scan head are recombined with an F-theta objective on the working position generating the interference pattern.The DLIP spot has a line-like interference pattern with about 15μm spatial period.Laser fluences of up to 8 J cm^(-2) were achieved using a maximum pulse energy of 0.6 mJ.Furthermore,an in-house built roll-to-roll machine was developed.Using this setup,aluminum and copper foil of 20μm and 9μm thickness,respectively,could be processed.Subsequently to current collector structuring coating of composite electrode material took place.In case of lithium nickel manganese cobalt oxide(NMC 622)cathode deposited onto textured aluminum current collector,an increased specific discharge capacity could be achieved at a C-rate of 1℃.For the silicon/graphite anode material deposited onto textured copper current collector,an improved rate capability at all C-rates between C/10 and 5℃ was achieved.The rate capability was increased up to 100%compared to reference material.At C-rates between C/2 and 2℃,the specific discharge capacity was increased to 200 mAh g^(-1),while the reference electrodes with untextured current collector foils provided a specific discharge capacity of 100 m Ah g^(-1),showing the potential of the DLIP technology for cost-effective production of battery cells with increased cycle lifetime.

Texturing and evaluation of concrete pavement surface:A state-of-the-art review

Concrete pavement is accompanied by two major functional properties,namely noise emission and friction,which are closely related to pavement surface texture.While several technologies have been developed to mitigate tirepavement noise and improve driving friction by surface texturization,limited information is available to compare the advantages and disadvantages of different surface textures.In this study,a state-of-the-art and state-of-thepractice review is conducted to investigate the noise reduction and friction improvement technologies for concrete pavement surfaces.The commonly used tests for characterizing the surface texture,skid resistance,and noise emission of concrete pavement were first summarized.Then,the texturing methods for both fresh and hardened concrete pavement surfaces were discussed,and the friction,noise emission and durability performances of various surface textures were compared.It is found that the next generation concrete surface(NGCS)texture generally provides the best noise emission performance and excellent friction properties.The exposed aggregate concrete(EAC)and optimized diamond grinding textures are also promising alternatives.Lastly,the technical parameters for the application of both diamond grinding and diamond grinding&grooving textures were recommended based on the authors'research and practical experience in Germany and the US.This study offers a convenient reference to the pavement researchers and engineers who seek to quickly understand relevant knowledge and choose the most appropriate surface textures for concrete pavements.

Model of Surface Texture for Honed Gear Considering Motion Path and Geometrical Shape of Abrasive Particle

Gear power-honing is mainly applied to finish small and medium-sized automotive gears,especially in new energy vehicles.The distinctive curved surface texture greatly improves the noise emission and service life of honed gears.The surface texture for honed gear considering the motion path and geometrical shape of abrasive particles has not been investigated.In this paper,the kinematics of the gear honing process is analyzed,and the machining marks produced by the abrasive particles of honing wheel scratching abrasive particles against the workpiece gear are calculated.The tooth surface roughness is modeled considering abrasive particle shapes and material plastic pile-ups.This results in a mathematical model that characterizes the structure of the tooth surface and the orientation of the machining marks.Experiments were used to verify the model,with a maximum relative error of less than 10%when abrasive particles are spherical.Based on this model,the effects of process parameters on the speeds of discrete points on the tooth flank,orientations of machining marks and roughness are discussed.The results show that the shaft angle between the workpiece gear and the honing wheel and the speed of the honing wheel is the main process parameters affecting the surface texture.This research proposes a surface texture model for honed gear,which can provide a theoretical basis for optimizing process parameters for gear power-honing.

Generating micro/nanostructures on magnesium alloy surface using ultraprecision diamond surface texturing process

The lightness and high strength-to-weight ratio of the magnesium alloy have attracted more interest in various applications.However,micro/nanostructure generation on their surfaces remains a challenge due to the flammability and ignition.Motivated by this,this study proposed a machining process,named the ultraprecision diamond surface texturing process,to machine the micro/nanostructures on magnesium alloy surfaces.Experimental results showed the various microstructures and sawtooth-shaped nanostructures were successfully generated on the AZ31B magnesium alloy surfaces,demonstrating the effectiveness of this proposed machining process.Furthermore,sawtooth-shaped nanostructures had the function of inducing the optical effect and generating different colors on workpiece surfaces.The colorful letter and colorful flower image were clearly viewed on magnesium alloy surfaces.The corresponding cutting force,chip morphology,and tool wear were systematically investigated to understand the machining mechanism of micro/nanostructures on magnesium alloy surfaces.The proposed machining process can further improve the performances of the magnesium alloy and extend its functions to other fields,such as optics.

Impressive strides in amelioration of corrosion behavior of Mg-based alloys through the PEO process combined with surface laser process: A review

The unsatisfactory corrosion properties of Mg-based alloys pose a significant obstacle to their widespread application. Plasma electrolytic oxidation(PEO) is a prevalent and effective coating method that produces a ceramic-like oxide coating on the surface of Mg-based alloys,enhancing their resistance to corrosion. Research has demonstrated that PEO treatment can substantially improve the corrosion performance of alloys based on magnesium in the short term. In an effort to enhance the corrosion resistance of PEO coatings over an extended period of time, researchers have turned their attention to the use of laser processes as both pre-and post-treatments in conjunction with the PEO process. Various laser processes, such as laser shock melting(LSM), laser shock adhesion(LSA), laser shock texturing(LST), and laser shock peening(LSP), have been investigated for their potential to improve PEO coatings on Mg substrates and their alloys. These laser melting processes can homogenize and alter the microstructure of Mg-based alloys while leaving the bulk material unchanged, thereby modifying the substrate surface. However, the porous and rough structure of PEO coatings, with their open and interconnected pore structure, can reduce their long-term corrosion resistance. As such, various laser processes are well-suited for surface modification of these coatings. This study will first examine the PEO process and the various types of laser processes used in this process, before investigating the corrosion behavior of PEO coatings in conjunction with laser pre-and post-treatment processes.

Compression of surface texture acceleration signal based on spectrum characteristics

Background Adequate data collection can enhance the realism of online rendering or offline playback of haptic surface textures.A parallel challenge is to reduce communication delays and improve storage space utilization.Methods Based on the similarity of the short-term amplitude spectrum trend,this study proposes a frequency-domain compression method.A compression framework is designed,which first maps the amplitude spectrum into grayscale images,compresses them with a still image compression method,and then adaptively encodes the maximum amplitude and part of the initial phase for each time window to achieve the final compression.Results The comparison between the original signal and the recovered signal shows that when the time-frequency similarity is 90%,the average compression ratio of our method is 9.85%in the case of a single interaction point.The subjective score for similarity was found to be high,with an average of 87.85.Conclusions Our method can be used for offline compression of vibrotactile data.For multi-interaction points in space,the trend similarity grayscale image can be reused,and the compression ratio is further reduced.

Tribological properties of the beetle leg joints

Tribological properties of femoro-tibial leg joints in two beetles,darkling beetle Zophobas morio and Congo rose chafer Pachnoda marginata were studied.Very low friction of 0.004 was revealed by the direct measurements in the joint.It is assumed that semi-solid lubricant functioning as in technical bearings is one of the leading factors of the friction minimization.Dependence of the surface texture and physical chemical properties(hydrophobicity)on the cuticle friction was analysed.Contribution of the surface texture to the tribological properties of contacting surfaces was examined by the measurement in the tribosystem“contacting surface/glass”.It is supposed that coefficient of friction(COF)decreases with decrease of surface roughness.At the same time,no statistically significant correlation was found between the hydrophobicity of the surface and the value of the friction coefficient.

Sliding wear characteristics of solid lubricant coating on titanium alloy surface modified by laser texturing and ternary hard coatings

Titanium alloys are poor in wear resistance and it is not suitable under sliding conditions even with lubrication because ofits severe adhesive wear tendency.The surface modifications through texturing and surface coating were used to enhance the surfaceproperties of the titanium alloy substrate.Hard and wear resistant coatings such as TiAlN and AlCrN were applied over texturedtitanium alloy surfaces with chromium as interlayer.To improve the friction and wear resisting performance of hard coatings further,solid lubricant,molybdenum disulphide(MoS2),was deposited on dimples made over hard coatings.Unidirectional sliding weartests were performed with pin on disc contact geometry,to evaluate the tribological performance of coated substrates.The tests wereperformed under three different normal loads for a period of40min at sliding velocity of2m/s.The tribological behaviours ofmulti-layer coatings such as coating structure,friction coefficient and specific wear rate were investigated and analyzed.The lowerfriction coefficient of approximately0.1was found at the early sliding stage,which reduces the material transfer and increases thewear life.Although,the friction coefficient increased to high values after MoS2coating was partially removed,substrate was stillprotected against wear by underlying hard composite layer.

Mechanical Properties and Microstructure of Bionic Non-Smooth Stainless Steel Surface by Laser Multiple Processing

Laser multiple processing, i.e. laser surface texturing and then Laser Shock Processing (LSP), is a new surface processing technology for the preparation of bionic non-smooth surfaces. Based on engineering bionics, samples of bionic non-smooth surfaces of stainless steel 0Crl 8Ni9 were manufactured in the form of reseau structure by laser multiple processing. The mechanical properties (including microhardness, residual stress, surface roughness) and microstructure of the samples treated by laser multiple processing were compared with those of the samples without LSP The results show that the mechanical properties of these samples by laser multiple processing were clearly improved in comparison with those of the samples without LSP The mechanisms underlying the improved surface microhardness and surface residual stress were analyzed, and the relations between hardness, comnressive residual stress and roughness were also presented.

Evaluation of surface textures and skid resistance of pervious concrete pavement

Surface textures had long been recognized as primary factors to provide the skid resistance on pavements; however, no measurement of skid resistance on pervious concrete pavement with various surface texture parameters had been made. Fractal geometry was introduced in the present work to accurately simulate transect contour curves of pervious concrete specimens through fractal interpolation. It is proved that its fractal dimension (D) can be adopted to measure the skid resistance on pervious concrete pavement, overcoming the shortcomings of both macrotexture depth (DT ) and British portable pendulum number (NBP). Combined with Fujikawa-Koike tire/road contact model, the optimization method of all surface textures was recommended for designing and constructing excellently skid-resistant and noise-absorptive pervious concrete pavement. In addition, evaluating of the abrasion process and attenuation of the surface textures on concrete pavement slabs was also the focus of this work based on accelerated abrasion test. Results show that the surface textures on pervious concrete pavement slabs is extremely durable, compared to those on conventional grooved or exposed aggregate concrete pavement slabs.

Experimental Study on Wear Performance and Oil Film Characteristics of Surface Textured Cylinder Liner in Marine Diesel Engine

It is of a vital importance to reduce the frictional losses in marine diesel engines. Advanced surface textures have provided an e ective solution to friction performance of rubbing pairs due to the rapid development of surface engineering techniques. However,the mechanisms through which textured patterns and texturing methods prove beneficial remains unclear. To address this issue,the tribological system of the cylinder liner?piston ring(CLPR) is investigated in this work. Two types of surface textures(Micro concave,Micro V?groove) are processed on the cylinder specimen using di erent processing methods. Comparative study on the friction coe cients,worn surface texture features and oil film characteristics are performed. The results demonstrate that the processing method of surface texture a ect the performance of the CLPR pairs under the specific testing conditions. In addition the micro V?groove processed by CNCPM is more favorable for improving the wear performances at the low load,while the micro?con?cave processed by CE is more favorable for improving the wear performances at the high load. These findings are in helping to understand the e ect of surface texture on wear performance of CLPR.

Cooperative effect of surface alloying and laser texturing on tribological performance of lubricated surfaces

The cooperative effect of laser surface texturing(LST) and double glow plasma surface alloying on tribological performance of lubricated sliding contacts was investigated.A Nd:YAG laser was used to generate microdimples on steel surfaces. Dimples with the diameter of 150μm and the depth of 30-35μm distributed circumferentially on the disc surface.The alloying element Cr was sputtered to the laser texturing steel surface by double glow plasma technique.A deep diffusion layer with a thickness of 30μm and a high hardness of HV900 was formed in this alloy.Tribological experiments of three types of samples(smooth,texturing and texturing+alloying) were conducted with a ring-on-disc tribometer to simulate the face seal.It is found that,in comparison with smooth steel surfaces,the laser texturing samples significantly reduce the friction coefficient.Moreover,the lower wear rate of the sample treated with the two surface techniques is observed.

Effect of laser textured surface with different patterns on tribological characteristics of bearing material AISI 52100

Chrome steels are used in bearings since they possess high strength and wear resistance.However,when those parts are in service,failure happens due to sliding friction before the lifetime.To improve the durability of the American Iron and Steel Institute(AISI)52100 chromium steel,in this work,the effect of laser surface texturing(LST)was analyzed.With the different patterns of circle and ellipse comparing with the untextured samples,the wear behavior was investigated using the pin-on-disc tribometer.The lubricant used for wear analysis is semisolid lithium grease National Lubricating Grease Institute lubricant(SKF NLGI-3).Sliding wear analysis was conducted at different loads of 10 N,30 N and 50 N for the sliding speed of 750 r/min and 1400 r/min.The wear morphology was analyzed using a scanning electron microscope(SEM).The roughness of the samples was found using a white light interferometer.The effect of different patterns like circle and ellipse,alter the friction and wear properties of chromium alloy was observed compared with the untextured samples.LST shows considerable reduction in friction and wear for ellipsoidal pattern compared with the circular pattern because of wear debris and lubricant getting trapped.

Classification of wood surface texture based on Gauss-MRF Model

The basal theory of Gauss-MRF is expounded and 2-5 order Gauss MRF models are established. Parameters of the 2-5 order Gauss-MRF models for 300 wood samples＇ surface texture are also estimated by using LMS. The data analysis shows that： 1） different rexture parameters have a clear scattered distribution, 2） the main direction of texture is the direction represented by the maximum parameter of Gauss-MRF parameters, and 3） for those samples having the same main direction, the finer the texture is, the greater the corresponding parameter is, and the smaller the other parameters are; and the higher the order of Gauss-MRF is, the more clearly the texture is described. On the condition of the second order Gauss MRF model, parameter B1, B2 of tangential texture are smaller than that of radial texture, while B3 and B4 of tangential texture are greater than that of radial texture. According to the value of separated criterion, the parameter of the fifth order Gauss-MRF is used as feature vector for Hamming neural network classification. As a result, the ratio of correctness reaches 88%.

Use of digital image analysis combined with fractal theory to determine particle morphology and surface texture of quartz sands

The particle morphology and surface texture play a major role in influencing mechanical and hydraulic behaviors of sandy soils. This paper presents the use of digital image analysis combined with fractal theory as a tool to quantify the particle morphology and surface texture of two types of quartz sands widely used in the region of Vitória, Espírito Santo, southeast of Brazil. The two investigated sands are sampled from different locations. The purpose of this paper is to present a simple, straightforward,reliable and reproducible methodology that can identify representative sandy soil texture parameters.The test results of the soil samples of the two sands separated by sieving into six size fractions are presented and discussed. The main advantages of the adopted methodology are its simplicity, reliability of the results, and relatively low cost. The results show that sands from the coastal spit(BS) have a greater degree of roundness and a smoother surface texture than river sands(RS). The values obtained in the test are statistically analyzed, and again it is confirmed that the BS sand has a slightly greater degree of sphericity than that of the RS sand. Moreover, the RS sand with rough surface texture has larger specific surface area values than the similar BS sand, which agree with the obtained roughness fractal dimensions. The consistent experimental results demonstrate that image analysis combined with fractal theory is an accurate and efficient method to quantify the differences in particle morphology and surface texture of quartz sands.

Surface texturing for adaptive Ag/MoS_2 solid lubricant plating

The objective of this research is to prepare specially designed surface texture on hard steel surface by electrochemical micromachining (EM) and to incorporate electroless plated Ag/MoS2 solid lubricant coating into the dimples of EM textured steel surface to effectively reduce friction and wear of steel-steel contacts. The friction and wear behavior of the Ag/MoS2 solid lubricant coating on EM textured steel surface was evaluated in relation to the size and spacing of the dimples thereon. The microstructure of as-plated Ag/MoS2 solid lubricant coating and the morphology and elemental composition of the worn coating surface and counterface steel surface were analyzed by means of optical microscopy, scanning electron microscopy, and energy dispersive spectrometry. It is found that electroless plated Ag/MoS2 coating is able to greatly reduce the friction and wear of the EM textured steel disc coupled with GCr15 steel ring, mainly because of the formation of solid self-lubricating layer on the EM textured steel surface and of transferred lubricating film on counterface steel surface. The diameter and spacing of the dimples are suggested as 500 μm for acquiring the best wear resistance of the hard steel discs after electrochemical micromachining treatment and electroless plating of Ag/MoS2 solid lubricating coating.

Surface and Texture Properties of Tb-Doped Ceria-Zirconia Solid Solution Prepared by Sol-Gel Method

The three-way catalysts （TWCs） promoters Ce0.6Zr0.4- x TbxO2-y were prepared by sol-gel method. BET surface areas analysis indicated that an increase of the dopant Tb content from x = 0.05 to x = 0.15 favors an increase of surface area from 66.8 to 80.4 m^2· g^-1 compared with the undoped sample Ce0 .6oZr0.40O2 65.1 m^2·g^- 1 after calcination at 650℃. Transmission electron microscopy （TEM） observation indicated that the doped samples have a higher thermal stability. The XRD and Raman spectra confirmed that the Ce0.6Zr0.4-xTbxO2-y cubic solid solution is formed. XPS analysis revealed that Ce and Tb mainly existed in the form of Ce^4＋ and Tb^3 ＋ , and Zr existed in the form of Zr^4＋ on the surface of the samples. The doped samples were homogenous in composition ; the introduction of Tb into the CeO2-ZrO2 promoters resuited in the formation of a solid solution, and the concentration of surface lattice oxygen was increased.

Evolution of aggregate surface texture due to tyre-polishing

Three kinds of aggregates were polished by genuine pneumatic rubber tyres.The initial states of surface texture and dynamic friction coefficient were measured and their developments in polishing process were monitored.The characterizations of height distribution and power spectral density of aggregate surface texture were estimated.The changes of micro-texture were also investigated based on a fractal filtering method with sound theoretical backgrounds of rubber friction on rough surfaces.Global height reduction and differential removal of mineral component are observed in polishing process.It is concluded that the tyre-polishing action plays the critical roles in the micro-scale texture,and the evolution of friction of aggregate is governed by the micro-texture changes due to the differential removal of mineral component.

Friction Characteristics of Nanoscale Sliding Contacts between Multi-Asperity Tips and Textured Surfaces

Nanoscale sliding contacts of smooth surfaces or between a single asperity and a smooth surface have been widely investigated by molecular dynamics simulations, while there are few studies on the sliding contacts between two rough surfaces. Actually, the friction of two rough surfaces considering interactions between more asperities should be more realistic. By using multiscale method, friction characteristics of two dimensional nanoscale sliding contacts between rigid multi-asperity tips and elastic textured surfaces are investigated. Four nanoscale textured surfaces with different texture shapes are designed, and six multi-asperity tips composed of cylindrical asperities with different radii are used to slide on the textured surfaces. Friction forces are compared for different tips, and effects of the asperity radii on the friction characteristics are investigated. Average friction forces for all the cases are listed and compared, and effects of texture shapes of the textured surfaces are discussed. The results show that textured surface II has a better structure to reduce friction forces. The multi-asperity tips composed of asperities with R=20r0 （r0=0.227 7 nm） or R=30r0 get higher friction forces compared with other cases, and more atoms of the textured surfaces are taken away by these two tips, which are harmful to reduce friction or wear. For the case of R=10ro, friction forces are also high due to large contact areas, but the sliding processes are stable and few atoms are taken away by the tip. The proposed research considers interactions between more asperities to make the model approach to the real sliding contact problems. The results will help to vary or even control friction characteristics by textured surfaces, or provide references to the design of textured surfaces.