Texture Density Research Articles

Hybrid-Light-Source Stereolithography for Fabricating Macro-Objects With Micro-Textures

Abstract Microscale surface structures are commonly found on macroscale bodies of natural creatures for their unique functions. However, it is difficult to fabricate such multi-scale geometry with conventional stereolithography processes that rely on either laser or digital micromirror device (DMD). More specifically, the DMD-based mask projection method displays the image of a cross section of the part on the resin to fabricate the entire layer efficiently; however, its display resolution is limited by the building area. In comparison, the laser-based vector scanning method builds smooth features using a focused laser beam with desired beam-width resolution; however, it has less throughput for its sequential nature. In this paper, we studied the hybrid-light-source stereolithography process that integrates both optical light sources to facilitate the fabrication of macro-objects with microscale surface structures (called micro-textures in the paper). The hardware system uses a novel calibration approach that ensures pixel-level dimensional accuracy across the two light sources. The software system enables designing the distribution and density of specific microscale textures on a macro-object by generating projection images and laser toolpaths for the two integrated light sources. Several test cases were fabricated to demonstrate the capability of the developed process. A large fabrication area (76.8–80.0 mm) with 50 μm micro-features can be achieved with a high throughput.

Effect of equal channel angular pressing on microstructure and mechanical performance of innovative nano MgO-added Mg-Zn-Ca composite as a biomaterial

Here, in order to implant the components in the human body, a novel composite biomaterial, the Mg-3Zn-0.2Ca composite with 0.6wt.%MgO, was processed by equal channel angular process (ECAP) with the route BC at 300℃. The evolutions of microstructure after ECAP significantly homogenized the grains. The results exhibit that the compressive strain at fracture (CSF) of the composites increased from 14.1% to 34.18% without sacrificing strength nearly. As the pass number for ECAP increasing, the added MgO and second phases turned smaller and distributed more evenly in the matrix. Meanwhile, the plastic deformation caused preferred orientation for recrystallized grains. The refinement of second phases and the variation of grain orientation by ECAP help to improve the mechanical properties of obtained composites. Furthermore, the ECAP method decreased texture density and activated more slip systems, hence the plasticity was also improved. In this study, the effects of grain refinement, microstructure homogenization, second phase distribution and grain orientation on microstructure evolution and mechanical performance during ECAP were investigated.

Experimental study on the effect of surface texture on tribological properties of nanodiamond films under water lubrication

The effect of nanoscale surface texture on the frictional and wear performances of nanocrystalline diamond films under water-lubricating conditions were comparatively investigated using a reciprocating ball-on-flat tribometer. Although the untreated nanocrystalline diamond film shows a stable frictional state with an average friction coefficient of 0.26, the subsequent textured films show a beneficial effect on rapidly reducing the friction coefficient, which decreased to a stable value of 0.1. Furthermore, compared with the nanocrystalline diamond coating, the textured films showed a large decreasing rate of the corresponding ball wear rate from 4.16 × 10−3 to 1.15 × 10−3 mm3/N/m. This is due to the fact that the hydrodynamic fluid film composed of water and debris can provide a good lubrication environment, so the entire friction process has reached the state of fluid lubrication. Meanwhile, the surface texture can greatly improve the hydrophilicity of the diamond films, and as the texture density increases, the water contact angle decreases from 94.75° of the nanocrystalline diamond film to 78.5° of the textured films. The proper textured diamond film (NCD90) exhibits superior tribological properties among all tested diamond films, such as short run-in period, low coefficient of friction, and wear rate.

Synergistic effect of textured piston ring and nano-lubricant on performance parameters and emissions of IC engine

Internal combustion (IC) engine is a prime emitter of greenhouse gases. The piston ring-cylinder liner pair plays a critical role in engine performance and exhaust emissions. Moreover, it accounts for major engine losses. The texturing on the piston ring and nano-material blended engine oil (nano-lubricant) have demonstrated promising results in their respective investigations on the IC engine. So far, most of the studies have been conducted on one of these approaches. Therefore, in this study synergistic effect of textured piston ring and nano-lubricant is investigated on performance parameters (fuel consumption, brake thermal efficiency, and brake specific fuel consumption) and engine emissions. The upper top compression piston ring is textured partially, and the nano-lubricant is prepared using silicate complexes nano-material [Mg6SiO10(OH)8] of 1% by weight with multi-grade engine oil (20W-40). The laser surface texturing technique (LST) is used to produce cylindrical textures on the piston ring with 6% texture density and 7.5% aspect ratio. Experiments have been conducted on a single-cylinder, direct injection, air-cooled, naturally aspirated compression ignition engine. All tests have been performed under different loading conditions (20%, 40%, 60%, 80% and 100% of full load). The synergistic effect of partially textured piston ring and nano-lubricant showed lower fuel consumption up to 4.58%, and nano-lubricant showed fuel reduction up to 3.23%. Furthermore, the exhaust emissions (CO, HC, and NOx) demonstrated a reduction that ranges from 0.24% to 10% compared to baseline data.

Effect of FSP parameters on microstructure evolution and mechanical properties of AZ31 magnesium alloy

To investigate the microstructure evolution and mechanical properties of materials treated by friction stir processing process at various the shoulder sizes and rotating speeds of the tool, a series of friction stir processing experiments were carried out on the AZ31 magnesium alloy with thickness of 4mm by using tool shoulder sizes of 12, 16 and 18mm, and two kinds of rotating speeds of 750r/min and 1500r/min with a constant feed speed of 60mm/min were supplied. Based on the analysis of morphology and mechanical properties of the materials, results demonstrated that reduction of tool shoulder size and rotating speed would contribute to more remarkable the grain refinement effect and affect the strong texture and extreme density strength of the material, leading to higher microhardness. However, lower mechanical properties of yield strength and tensile strength were obtained at these parameters owing to the existence of internal organization defect and stronger defect sensitivity of it. All of the findings would further deepen the understanding of the technique of friction stir processing and contribute to the application of AZ31 magnesium alloy treated by friction stir processing.

Relationships and Spatial Structure of Soil Physical Properties in a Ten-Year Corn-Cotton Rotation Field

This study quantified the relationships between soil, textural, and hydraulic properties at the field-scale for a conventional tilled Memphis silt loam that had undergone a 10-year corn and cotton rotation and described their spatial variability. Composite soil samples collected from the plow layer at 272 nodes on 15 x 15 m grids were analyzed for texture and bulk density. These values were used as pedotransfer functions to predict unsaturated (Ko) and saturated hydraulic (Ks) conductivities as well as the van Genuchten curve shape parameters α and n. Regression analyses quantified relationships between the measured and model predicted soil properties. While correlations between textural and model predicted soil properties including bulk density were significant (p<0.05), those between sand and clay, clay and n, clay and α were not. Sand and silt appeared to be better predictors of soil hydraulic conductivity and the van Genuchten curve shape parameters for the soil investigated. Spatial dependence was strong for sand, silt, bulk density, Ko, α and n, and moderate for clay and Ks.

James Dashow: Archimedes—A Planetarium Opera

James Dashow: Archimedes—A Planetarium Opera

Changes in soil water holding capacity and water availability following vegetation restoration on the Chinese Loess Plateau

Changes in land use type can lead to variations in soil water characteristics. The objective of this study was to identify the responses of soil water holding capacity (SWHC) and soil water availability (SWA) to land use type (grassland, shrubland and forestland). The soil water characteristic curve describes the relationship between gravimetric water content and soil suction. We measured the soil water characteristic parameters representing SWHC and SWA, which we derived from soil water characteristic curves, in the 0–50 cm soil layer at sites representing three land use types in the Ziwuling forest region, located in the central part of the Loess Plateau, China. Our results showed that the SWHC was higher at the woodland site than the grassland and shrubland, and there was no significant difference between the latter two sites, the trend of SWA was similar to the SWHC. From grassland to woodland, the soil physical properties in the 0–50 cm soil layer partially improved, BD was significantly higher at the grassland site than at the shrubland and woodland sites, the clay and silt contents decreased significantly from grassland to shrubland to woodland and sand content showed the opposite pattern, the soil porosity was higher in the shrubland and woodland than that in the grassland, the soil physical properties across the 0–50 cm soil layer improved. Soil texture, porosity and bulk density were the key factors affecting SWHC and SWA. The results of this study provide insight into the effects of vegetation restoration on local hydrological resources and can inform soil water management and land use planning on the Chinese Loess Plateau.

Visual detection of tobacco packaging film based on apparent features

The main purpose of this article is to study the detection of transparent film on the surface of tobacco packs. Tobacco production line needs an industrial robot to remove the transparent film in the process of unpacking. Therefore, after the industrial robot removes the transparent film, it is necessary to use machine vision technology to determine whether there is transparent film residue on the surface of tobacco packaging. In this article, based on the study of the optical features of semitransparent objects, an algorithm for detecting the residue of transparent film in tobacco packs based on surface features is proposed. According to the difference of surface features between tobacco and film, a probability distribution model considering highlights, saturation, and texture density is designed. Because the probability distribution model integrates many features of tobacco and film, it is more reasonable to distinguish the tobacco film regions. In this article, an appropriate foreground box with a trapezoidal mask and image segmentation algorithm GrabCut is used to segment the foreground area of tobacco pack more accurately, and the possible film area is obtained by image differential and morphological processing. Finally, on the basis of comparing the effect of various machine learning algorithms on the image classification of possible film regions, support vector machine based on color features is used to judge the possible film region. Application results of the system show that the method proposed in this article can effectively detect whether there is film residue on the surface of tobacco pack.

The Potential of Palm Oil Mill Effluent for Improving the Water Infiltration Rate in Lateritic Soil

Poor soil drainage of the lateritic soil is due to its clayey texture and high bulk density. Palm oil mill effluent (POME) may be administrated to increase the water infiltration rate and improve the drainage of the lateritic soil. The share farm of the Faculty of Plantation and Agrotechnology, UiTM Jasin was treated with various volume of POME for 16 weeks by using Completely Randomized Design (CRD). Overall, treatment of POME did not increased water infiltration rate. The bulk density of the lateritic soil that was treated with POME is suitable for agriculture. Treatment 1 (2L) gave 68 mm/hour of water infiltration rate and 1.25 g/cm3 of bulk density with 0.570 and 0.451 of p-values respectively which is acceptable with the consideration of cost benefits, cost inputs, and profit to the industry. The results shown were not significant might be due to types and soil textures, duration for the research to be completed, and also climate change factors.

Tribological response of laser-textured Ti6Al4V alloy under dry conditions and lubricated with Hank’s solution

A nanosecond laser was used to define different morphologies of a Ti6Al4V surface: lines, crosshatching and dimples. We analysed the influence of the surface morphology, texture density and orientation (parallel, perpendicular and at 45°) on the friction/wear under dry and lubricated (Hank’s solution) sliding conditions to evaluate the specific laser texturing of Ti alloys for biomedical applications. Under dry conditions, the lowest steady-state coefficient of friction was measured for dimples, whereas in Hank’s solution the lines and crosshatching showed better frictional characteristics after running-in and the removal of the bulges around the laser textures. In terms of wear resistance, the low-density lines pattern and particularly the dimples were the most promising in contact situations likely to occur during starved/dry-lubrication conditions.

Effect of shape/size and distribution of microgeometries of textures on tribo-performance of crankpin bearing

The effect of the shape/size and distribution of microgeometries of textures on improving the tribo-performance of crankpin bearing is proposed. Based on a combined model of the slider-crank mechanism dynamic and hydrodynamic lubrication, the distribution density, area density, and shape of spherical textures, square-cylindrical textures, wedge-shaped textures, and a hybrid between spherical texture and square-cylindrical texture on the crankpin bearing's tribo-performance are investigated under different operating conditions of the engine. The tribological characteristic of the crankpin bearing is then evaluated via the indexes of the oil film pressure p, asperity contact force, friction force, and friction coefficient of the crankpin bearing. The research results show that the distribution density with n = 12 and m = 6, and area density with α = 30% of various microtextures have an obvious effect on ameliorating the crankpin bearings tribo-performance. Concurrently, at the mixed lubrication region, the shape of the square-cylindrical texture on improving the tribo-performance is better than the other shapes of the spherical texture, wedge-shaped texture, and spherical and square-cylindrical texture. Particularly, all the average values of the asperity contact force, friction force, and friction coefficient with a square-cylindrical texture are significantly reduced by 14.6%, 19.5%, and 34.5%, respectively, in comparison without microtextures. Therefore, the microtextures of the spherical texture applied on the bearing surface can contribute to enhance the durability and decrease the friction power loss of the engine.

Potential ecological risk index for metals in a grazing area, Guasca, Cundinamarca

The presence of metals in soils used for primary economic activities can negatively impact the environment and public health. This research identified soil contamination by heavy metals (Lead, Copper, Zinc, and Manganese) by examining physical and chemical properties (Phosphorus, Potassium, organic carbon, cation exchange capacity, pH, texture, and bulk density) of the area during the dry and rainy seasons of 2017. Composite samplings of soil were carried out in both seasons, in order to obtain a representative value of the soil in certified laboratories. Thereafter, through interpolation by means of the Kriging method, a spatial scale of metal concentrations was conducted. This led to the conclusion that the study area has an acceptable environmental quality (5.8-6.9) for its current use of grazing. Likewise, the area presents a medium level (75.37), pursuant to the Potential Ecological Risk Index (RI) for the dry season, and a very high risk (195.04) during the rainy season. These estimates are directly related to lead concentrations, introduced to the soil of the area by human development activities and by contributions of parent material to the soil surface layers, through natural processes of weathering.

Responses of Soil Infiltration to Water Retention Characteristics, Initial Conditions, and Boundary Conditions

(1) Background: Simulation of soil water infiltration process and analysis of its influencing factors are important for water resources management. (2) Methods: In this study, the relative contributions of the soil water retention characteristics (SWRC) estimation, initial water content, and constant pressure head at upper boundary to the cumulative infiltration under various soil conditions were quantified based on the 1-D Richards’ equation and 900 scenarios. Scenario simulations were performed for two SWRC estimation methods (Jensen method and Rosetta); three different initial water contents (0.15, 0.20, and 0.25 cm3/cm3); five different constant pressure heads (0.5, 1, 2, 4, and 8 cm); and thirty soil samples with varying texture and bulk density. (3) Results: Rosetta representing the drying branch of the SWRC yielded higher simulated cumulative infiltration compared with the Jensen method representing the wetting branch of the SWRC. However, the Jensen method–predicted cumulative infiltration fluxes matched well with the measured values with a low RMSE of 0.80 cm. (4) Conclusions: The relative contribution of the SWRC estimation method to cumulative infiltration (19.1–72.2%) was compared to that of constant pressure head (14.0–65.5%), and generally greater than that of initial water content (2.2–29.9%). Findings of this study have practical significance for investigating the transport of water, nutrients, and contaminants in the unsaturated zone.

Global Prediction of Soil Saturated Hydraulic Conductivity Using Random Forest in a Covariate‐Based GeoTransfer Function (CoGTF) Framework

AbstractSaturated hydraulic conductivity (Ksat) is a key soil hydraulic parameter for representing infiltration and drainage in land surface models. For large scale applications, Ksat is often estimated from pedotransfer functions (PTFs) based on easy‐to‐measure soil properties like soil texture and bulk density. The reliance of PTFs on data from uniform arable lands and the omission of soil structure limits the applicability of texture‐based predictions of Ksat in vegetated lands. To include effects of terrain, climate, and vegetation in the derivation of a new global Ksat map at 1 km resolution, we harness technological advances in machine learning and availability of remotely sensed surrogate information. For model training and testing, a global compilation of 6,814 geo‐referenced Ksat measurements from the literature was used. The accuracy assessment based on spatial cross‐validation shows a concordance correlation coefficient (CCC) of 0.16 and a root mean square error (RMSE) of 1.18 for log10 Ksat values in cm/day (CCC = 0.79 and RMSE = 0.72 for non‐spatial cross‐validation). The generated maps of Ksat represent spatial patterns of soil formation processes more distinctly than previous global maps of Ksat based on easy‐to‐measure soil properties. The validation of the model indicates that Ksat could be modeled without bias using Covariate‐based GeoTransfer Functions (CoGTFs) that harness spatially distributed surface and climate attributes, compared to soil information based PTFs. The relatively poor performance of all models in the validation (low CCC and high RMSE) highlights the need for the collection of additional Ksat values to train the model for regions with sparse data.

Evaluation and Biological properties maps of Gypsiferous Soil using Geomatic techniques, Tikrit city, Salahaldin, Iraq

This study was conducted to prepare a map of the biological properties in the gypsiferouse soil using geomatic techniques at the Tikrit city site. (20) soil samples of the surface layer of gypsum soil were collected randomly according to differently in the nature of agricultural exploitation as survey study. Analyses and measurements of physical (texture and bulk density) and chemical characteristics were carried out: pH, EC, O.M, CaSO4.2H2O and the bacteria and fungi numbers were estimated by methods Certified in the laboratory. Used satellite Images acquired at 24Feb.2019 and 20sep.2019 were used and processed digitally and calculated the following vegetation indicators as follows: NDVI, OSAVI, LAI and LST. Maps of the biological properties (Bacteria and Fungi) were prepared using the Kriging interpolation according to The Spheroidal Model in the ArcGIS Ver environment.10.2. The show results the effect of gypsum content in the bacteria and fungi with the R2 (0.75 and 0.79). The results reached the importance of indices in evaluating the state and activity of bacteria as a positive regression relationship between the NDVI, LAI and OSAVI with the numbers of bacteria and fungi range (0.49-0.80) and were negative regression with the earth’s surface temperature LST. Therefore, spectral indices has proved important in spatial forecasting of the distribution and activity of organisms and the control of seasonal changes in soil surface.

Formability and mechanism of pulsed current pretreatment–assisted laser impact microforming

Pulsed current treatment was introduced into the laser impact microforming technology to improve the formability of laser impact forming. A pulsed current pretreatment–assisted laser impact microforming technology is proposed, and the formability and mechanism of such composite technology are discussed. In this study, the mechanical properties of H62 brass before and after pulse treatment were tested. The effect of pulsed current treatment on the formability of the material under high strain rate was studied by a laser impact free microbulging experiment. Moreover, the mechanism of pulsed current influence on the material’s formability was analyzed from the aspects of microstructure, texture evolution process, and grain size and morphology. Results showed that the elongation of the material was increased obviously, the flow stress during the tensile process was decreased significantly after pulsed current treatment, and the fracture form of the material gradually evolved from brittle fracture to ductile fracture. The forming height of samples under high strain rate improved greatly which may be due to the high-density pulsed current treatment that significantly alleviated the dislocation entanglement in the material. Owing to the weaker orange-peel effect which is induced by smaller recrystallized grains and lower maximum density of texture, the surface quality of formed parts after pulsed current treatment increased remarkably. In addition, the more uniform section thickness distribution of formed parts was observed, which may stem from obviously refined grains after pulsed current treatment improved the fluidity of the grains in a high–strain rate deformation process.

Effects of spherical-platform texture parameters on the tribological performance of water-lubricated bearings

Water-lubricated bearings are essential parts of marine propulsion systems. However, severe friction and wear of water-lubricated bearings usually occur under marine running conditions. Surface texture technology has been verified as an effective method for improving material tribological properties and been successfully applied in many fields. Here, the effects of surface spherical-platform texture parameters on the tribological performance of water-lubricated bearings were investigated using 9 types of spherical-platform textured high density polyethylene (HDPE) specimens, manufactured using 3D printer technology. Two groups of tests with different applied loads and rotational speeds were performed to simulate low-speed and heavy-load conditions of water-lubricated bearings. By analyzing the friction coefficient, wear mass loss, and surface topography, spherical-platform textures were concluded to have had a positive effect on the tribological performance of water-lubricated bearings. Specimens with 1/2 spherical-platform texture showed the best ability to promote the wedge-shaped effect and cavitation effect of lubrication, which improved the bearing tribological performance. This study provided an experimental foundation for optimizing the surface texture of water-lubricated bearings.

Mutual Influence of The Orchestra and Concerto Principle in The 16th – First Half of The 17th Centuries

The interaction between the evolution of the orchestra and the concerto at the end of the late 16th — first half of the 17th centuries has been considered. Three levels of interaction are revealed. The first one is the basso continuo. There is little attention paid to the importance of this technique for the formation of the orchestra: the impact on the formation of instrumentalists’ collectives through the appearance of a homophonic way of presentation; combining different forces of sound of instruments; strengthening the bass line as a solid foundation for the entire vertical structure. The second level is the concerto principle. It is emphasized that during the 16th century the concerto meant ―ensemble‖ of any configuration. The strengthening of the instrumental component in the works of M. Uccellini, I. Baccusi, A. and J. Gabrieli, A. Banchieri had an impact on the transformation of the concerto principle. Initially, the principle appeared through the opposition of pitches and density of texture, eventually extends to the comparison of instrumental, mixed vocal-instrumental and vocal groups, thus stimulating contrast in the middle of an instrumental groups such as ensemble and orchestra. The third level of the interaction is embodied in the genre of madrigal (C. Monteverdi). It seems that the release of instruments, the diversification of their functions, the rejection of the permanent exact duplications and the increased role of the timbre obviously require an instrumental body as a stable structure for the implementation of all above mentioned. The development of musical instruments, the diversification of their functions, the use of sinfonia and ritornellos in the choral composition became a driven force for the modification of the concerto principle resulted in the intensification of the competitive origin in the orchestra with each decade. All the above encourages to revise the depth of interaction between the orchestra and concerto. The orchestra as an organized and multi-instrumental collective, designed to exhibit music beyond the church or theatrical genres, becomes the institutional basis for the embodiment of the concerto principle in a particular genre of the instrumental concerto.

Study on the Influence of Surface Texture on the Dynamic Performance of Sliding Bearing

Rotor bearing system is an important part of mechanical equipment. The vibration of equipment caused by rotor system has become a more important problem in engineering. In this paper, the texture technology of the inner surface of the bearing is studied to explore the influence of the surface texture on the vibration reduction characteristics of the bearing. The results show that reasonable texture parameters and texture distribution can reduce the friction of the bearing and increase the end discharge. There is an optimal texture density and texture region. In this paper, a bearing test platform is set up to test and study the tiles with different surface texture. The test results show that the amplitude of the axis orbit of the sliding bearing with texture is significantly reduced, the principal stiffness and cross stiffness of the textured bearing are larger than those without texture, the damping is slightly larger under high speed and light load than that without texture, and the texture has obvious damping effect on the bearing shell.