Effect Of Tilt Angle Research Articles

Enhancing UAV–SfM 3D Model Accuracy in High-Relief Landscapes by Incorporating Oblique Images

Complex landscapes with high topographic relief and intricate geometry present challenges for complete and accurate mapping of both lateral (x, y) and vertical (z) detail without deformation. Although small uninhabited/unmanned aerial vehicles (UAVs) paired with structure-from-motion (SfM) image processing has recently emerged as a popular solution for a range of mapping applications, common image acquisition and processing strategies can result in surface deformation along steep slopes within complex terrain. Incorporation of oblique (off-nadir) images into the UAV–SfM workflow has been shown to reduce systematic errors within resulting models, but there has been no consensus or documentation substantiating use of particular imaging angles. To address these limitations, we examined UAV–SfM models produced from image sets collected with various imaging angles (0–35°) within a high-relief ‘badland’ landscape and compared resulting surfaces with a reference dataset from a terrestrial laser scanner (TLS). More than 150 UAV–SfM scenarios were quantitatively evaluated to assess the effects of camera tilt angle, overlap, and imaging configuration on the precision and accuracy of the reconstructed terrain. Results indicate that imaging angle has a profound impact on accuracy and precision for data acquisition with a single camera angle in topographically complex scenes. Results also confirm previous findings that supplementing nadir image blocks with oblique images in the UAV–SfM workflow consistently improves spatial accuracy and precision and reduces data gaps and systematic errors in the final point cloud. Subtle differences among various oblique camera angles and imaging patterns suggest that higher overlap and higher oblique camera angles (20–35°) increased precision and accuracy by nearly 50% relative to nadir-only image blocks. We conclude by presenting four recommendations for incorporating oblique images and adapting flight parameters to enhance 3D mapping applications with UAV–SfM in high-relief terrain.

Temperature Distribution During Friction Stir Welding of AA2014 Aluminum Alloy: Experimental and Statistical Analysis

FSW has shown great potential to weld AA2014 heat-treatable aluminum alloy. But the effectiveness of joint in FSW depends on the temperature distribution across the length and width of weld zone. The present study aims to investigate the temperature distribution during FSW of AA2014 alloy. The temperatures were recorded at eight different positions by inserting K-type thermocouples on pre-drilled AA2014 alloy under different process parameters like tool rotation (N), welding speed (v) and tilt angle. These temperatures were recorded using two thermocouple layouts: First layout was “equal distance and same depth” on advancing side (AS) whereas second layout was “equal distance and varying depth” on retreating side (RS). Experimental results showed that by increasing the N/v ratio, the peak temperature increased whereas the peak temperature decreased by decreasing the N/v ratio. On the other hand, effect of tool tilt angle on peak temperature was also found to be significant and confirmed by experimental as well as statistical analysis. Furthermore, it was concluded that temperature was higher on AS compared to the RS. The conclusion drawn from statistical analysis was in good agreement with experimental results.

Effect of tool tilt angle on cutting characteristics in micro-ball end milling

Effect of tool tilt angle on cutting characteristics in micro-ball end milling

Effect of tilt angle on the multi-pipe channel with sinusoidal/curved walls – numerical modelling based on finite volume method

PurposeThis paper aims to investigate the two-dimensional numerical modeling of fluid flow and heat transfer in a fluid channel.Design/methodology/approachThe channel is filled with the CuO-water nanofluid. The KKL model is used to estimate the dynamic viscosity and considering Brownian motion. On the other hand, the influence of CuO nanoparticles’ shapes on the heat transfer rate is taken account in the simulations. The channel is included with several active pipes with hot and cold temperatures. Furthermore, the external curved and sinusoidal walls have cold and hot temperatures, respectively.FindingsThree different tilt angles are considered with similar boundary and operating conditions. The Rayleigh numbers, solid volume fraction of CuO nanoparticles in the pure water and the tilt angles are the governing parameters. Different cases studies, such as streamlines, heat transfer rate, local and total entropy generation and heatlines, are analysed under influences of these governing parameters.Originality/valueThe originality of this work is investigation of fluid flow, heat transfer and entropy generation within a nanofluid filled channel using FVM.

Effect of the Tool Tilt Angle on the Heat Generation and the Material Flow in Friction Stir Welding

This work studies the effect of the tool tilt angle on the generated heat and the material flow in the work pieces joint by Friction Stir Welding (FSW). An apropos kinematic framework together with a two-stage speed-up strategy is adopted to simulate the FSW problem. The effect of tilt angle on the FSWelds is modeled through the contact condition by modifying an enhanced friction model. A rotated friction shear stress is proposed, the angle of rotation depending on the process parameters and the tilt angle. The proposed rotation angle is calibrated by the experimental data provided for a tilt angle 2.5°. The differences of generated heat and material flow for the cases of tool with tilt angle of 0° and 2.5° are discussed. It is concluded that due to the higher temperature, softer material and greater frictional force in the trailing side of the tool, the material flow in the rear side of the FSW tool with the title angle is considerably enhanced, which assists to prevent the generation of defect.

Effect of top cover tilt angle with ground surface on productivity of basin type solar distillation unit

Basin type solar stills were made with two types of top cover, transparent PVC sheet and another with glass sheet. A soaked black towel was at the base which was heated through green-house effect and contributed to the water for distillation. Productivity of these two basin type solar stills were studied at different tilt angles of the top transparent cover with ground surface (13o, 23o and 35o). The average amount of distilled water produced increased with the tilt angles for both types of cover materials, that for glass being much higher than that for PVC cover.Bangladesh Journal of Medical Physics Vol.10 No.1 2017 40-46

Experimental Investigation on the Tilt Helical Milling of Carbon Fiber Reinforced Plastics (CFRP)

Carbon fiber reinforced plastics (CFRP) has been widely used in various aircraft structural components. However, it is difficult for conventional methods such as drilling and helical milling to meet the requirements on high quality and efficient holes creation. Hence a so-called tilt helical milling (THM) method has been proposed. This new method is performed by replacing the revolving motion of the tool in conventional helical milling (CHM) with a conical pendulum motion, in which the tool axis is tilted towards the hole axis at a certain angle. As a step toward the establishment of the new method, in this work, the fundamental drilling characteristics of CFRP by the THM is elucidated by experimentally investigating the effects of tilt angle on thrust force and delamination factor. The obtained experimental results demonstrated that thrust force and delamination factor can be reduced with THM technique. In addition, THM can achieve better hole surface finish than CHM.

Influence of Tool Tilt Angle on the Formation of Friction Stir Processing Zone in Cast Magnesium Alloy ZK60/SiCp Surface Composites

Cast ZK60 magnesium alloy has significant beneficial properties including high strength-to-weight ratio. Poor surface properties such as low friction and wear resistance restrict the use of this alloy in structural applications. Therefore, it is very much essential to adopt surface engineering to enhance this alloy’s surface properties. Friction stir processing is one of the potential thermo-mechanical processing techniques that alters the microstructural and tribological properties of the material. In the present study, ZK60/SiCp was fabricated by means of FSP. Tool tilt angle is a critical process parameter which influences the material flow, and particle breakup and distribution in the processed zone. In this work, an attempt has been made to understand the effects of tool tilt angle (ranges 0°–4°) on the grain refinement of matrix and the distribution of SiC particles. It is shown that the FSPed materials zone produced using the tilt angle 2° exhibited higher hardness (125 Hv); this was attributed to the optimization of heat generation, material flow, grain boundary strengthening, and homogeneous particle distribution.

Heat transfer characteristic of an ultra-thin flat plate heat pipe with surface-functional wicks for cooling electronics

A novel ultra-thin aluminum flat plate heat pipe (UAFHP) with dimensions of 120 × 120 × 2 mm was developed for the thermal management of concentrated electronic equipment. An evaporator container with support posts and a filling hole was manufactured integrally by the stamping method. The surface-functional wicks, which were fabricated by a micro-milling method, consisted of array orthogonal microgrooves and the groove surfaces were covered with grain-like microstructures. The effects of heat load, cooling-water temperature, and tilt angle on the heat transfer characteristic of UAFHP, including its thermal response performance, temperature distribution and thermal resistance, were investigated experimentally. The results showed that UAFHP exhibits a favorable thermal response performance and heat transfer performance. It can effectively dissipate 160 W and has a minimum thermal resistance of 0.156 °C/W in the horizontal orientation. Moreover, when the cooling-water temperature decreases, the wall temperature of UAFHP decreases while the thermal resistance of UAFHP increases. In addition, small tilt angles (θ ≤ 30°) have a negligible effect on the heat transfer characteristic of UAFHP. Compared with the flat plate heat pipes reported in the literature, UAFHP could significantly meet the requirements of thermal management of concentrated ultra-slim portable electronic equipment because of its advantages such as light weight, favorable heat transfer characteristic, ease of fabrication and low cost.

Atomic Layer Deposition of Thin Films onto 3D Nanostructures: The Effect of Wall Tilt Angle and Aspect Ratio of Trenches

A theoretical model predicting the spatial profile of a film grown on walls by atomic layer deposition (ALD) is developed. The possible initial nonverticality of trench walls and the dynamic variation of the aspect ratio of the structure in the process of film growth in nanosized trenches are considered in this model. The dependence of the resulting film thickness and conformity on ALD process parameters is studied theoretically.

Laser ultrasonic technology for residual stress measurement of 7075 aluminum alloy friction stir welding

Friction stir welding (FSW) is widely used in the welding of aluminum alloys for aerospace applications, because of its low energy consumption, high efficiency and good mechanical properties. However, the problems of deformation, cracking and fatigue degradation caused by residual stress remain to be solved. In this paper, the residual stress in 7075 aluminum alloy FSW has been measured with laser ultrasonic technology. According to the FSW process and the characteristics of thin plate structure, the residual stress of aluminum alloy sheet is simplified to plane stress state. The pre-stress loading method is proposed and the acoustoelastic constants are obtained. With the known acoustoelastic constants, the longitudinal and transverse FSW residual stresses are measured with the laser ultrasonic. The result shows that the residual stress distribution is obviously asymmetrical and the residual stress on the advancing side is greater than that on the retreating side. The transverse residual stress is smaller than the longitudinal residual stress. Then, the influence of welding speed, rotational speed, tool tilts angle and plunge depth on residual stress is discussed. The results show that the welding speed has great influence on the residual stress, while the influence of the rotational speed on the residual stress is relatively small. When the welding speed is low, the influence of the rotational speed on the stress is more obvious than when the welding speed is higher. For the appropriate range which is determined according to the engineering experience, the effect of tool tilt angle and plunge depth on maximum longitudinal residual stress can be ignored. The research of this paper is of great significance to the application of laser ultrasonic technology in the quality inspection of welded parts and the optimization of FSW process.

Removal of emulsified oil from polymer-flooding sewage by an integrated apparatus including EC and separation process

Removing emulsified oil from polymer-flooding sewage (PFS) is a tough problem during oil field exploitation as the viscosity and emulsification degree of the oily sewage increased with the addition of polymer in the recovery process. This study aimed to propose an integrated apparatus composed of reaction and enhanced settlement process for small footprint and high settlement efficiency. The effects of current density, flow rate and tilt angles of parallel-plate electrodes (APE) were explored using the integrated apparatus in a continuous system. Furthermore, the comparison between field and laboratory experiments was performed. The results showed that the integrated apparatus had higher removal efficiency. For a given current density of 14 mA cm−2, flow rate of 5 L h−1 and APE 80°, the oil and turbidity removal rate of simulated sewage were 96.32% and 97.3%, respectively. Meanwhile, the energy consumption was 2.32 kWh m−3. For on-site sewage, the treatment effects were better and the removal rate of oil and turbidity were 97.2% and 98.2%, respectively. In addition, it was found that the entire EC process was divided into reactive stage and stable stage. The higher the current density, the better purification effect and the shorter time required to reach the stable. As current density increased from 7 to 14 mA cm−2, the stable time decreased from 100 to 40 min while current density increased from 14 to 28 mA cm−2, the stable time changed a little with the removal increased less than 5%. Besides, the results showed that the final removal decreases with the increase of APE, but except APE ɑ which was defined as a special orientation of electrode when the upper end of anode and the lower end of cathode are in a vertical line (Liu et al., 2017) and that a smaller flow rate required longer time to reach the steady stage with a satisfactory purification effect.

Adhesion forces between a parabolic-shaped AFM tip scanning a grooved gold surface: Comparison of a model and an experiment

Adhesion forces largely depend on the precise geometry of contact between two surfaces; however, this relationship has not yet been systematically studied. In this paper, the adhesion forces between a parabolic-shaped tip and a grooved gold surface were measured on an atomic force microscope (AFM) under ambient conditions. Experimental results show that the fluctuation in mean adhesion force corresponds to the substrate's profile (which is symmetric), yet is asymmetric. A numerical model is proposed based on geometry of the contact zone. Adhesion force was found to be largely dependent on the combined effects of tip radius, profile and tilt angle, and the concavity, principal curvatures and slope of the substrate surface. Moreover, adhesion force is increased by the superposition of the concave upward profile, and vice versa; while its variation in magnitude depends on the principal curvature. The adhesion force increases if the tip's contact point becomes further away from its vertex due to the slope of the curved sample. The slope has an additional effect due to the difference between the contact normal and pull-off directions. The adhesion force distribution is asymmetric for a tilted tip due to the asymmetric distribution of contact points on the tip. The modelled results of the adhesion forces estimated to occur while scanning along the curved surface are in reasonable accordance with the experimental results. The proposed model may allow better quantitative comparisons of adhesion forces measured experimentally and those estimated theoretically.

Influence of Tool Tilt Angle on Material Flow and Defect Generation in Friction Stir Welding of AA2219

Heat treatable aluminium alloy AA2219 is widely used for aerospace applications, welded through gas tungsten and gas metal arc welding processes. Welds of AA2219 fabricated using a fusion welding process suffers from poor joint properties or welding defects due to melting and re-solidification. Friction stir welding (FSW) is a solid-state welding process and hence free from any solidification related defects. However, FSW also results in defects which are not related to solidification but due to improper process parameter selection. One of the important process parameters, i.e., tool tilt angle plays a critical role in material flow during FSW, controlling the size and location of the defects. Effect of tool tilt angle on material flow and defects in FSW is ambiguous. A study is therefore taken to understand the role of tool tilt angle on FSW defects. Variation in temperature, forces, and torque generated during FSW as a result of different tool tilt angles was found to be responsible for material flow in the weld, controlling the weld defects. An intermediate tool tilt angle (1o-2o) gives weld without microscopic defect in 7 mm thick AA2219 for a given set of other process parameters. At this tool tilt angle, x-force, and Z- force is balanced with viscosity and the material flow strain rate sufficient for the material to flow and fill internal voids or surface defects in the weld.

The Variation Effect of Collector Tilt Angle on the Heat Pipe Solar Collector Performance

The thermal performance of FPHPSC has been studied experimentally and theoretically. The collector consists of copper absorber plate, single glass cover, glass wool insulation and aluminum case, ten wickless heat pipes of 12.7 mm inner diameter. The experimental studies of collector performance have been performed on four different CTA (22°, 32°, 45° and 60°). The relation between the solar intensity and the collector energy losses are also discussed. The collector are tested under the climate condition of Kut city (32.602 latitude and 45.752 longitude). It is investigated that the increasing of CTA increase the efficiency of collector up to certain limit after that the efficiency decreases with the increasing of tilt angle of collector. A computer program which is based on VISUAL BASICE language (version 6) is made for the theoretical analysis. The experimental results agree reasonably with the theoretical predictions.

Mobile advertising: The effect of tablet tilt angle on user’s purchase intentions

ABSTRACTWith the advent of mobile screens, online advertisements are viewed on screens held in various positions, from horizontal (such as when the tablet is rested on a table or on the knees) to vertical (when placed on an easel, for example), allowing the viewer to see the advertisement in different body postures. Based on the theory of embodied cognition, we present two experimental studies in which we show (1) that mobile device tilt angle impacts purchase intention of advertised products, (2) that purchase intention is increased when device tilt angle allows viewers to stand in a body posture that is consistent with the image perspective, and (3) that mental simulation process mediates this effect. The results contribute to a better understanding of the conditions of advertising effectiveness on mobile devices.

Directional Droplet Spreading Transport Controlled on Tilt‐Angle Pillar Arrays

AbstractThe controllable unidirectional spreading of droplet on tilt‐angle pillar arrays (TPAs) composed of epoxy resin (TDE‐85) and polyethylene glycol is presented. TPAs are fabricated via soft lithography with multimolding steps that coupled with a directional heat‐pressing and temperature controlling process, in which tilt‐angle structures are generated by using temperature‐responsive shape memory polymers and then act as mold. TPAs with different tilt angles (e.g., unidirection and opposite directions) are thereby obtained. It is found that the TPAs propel the droplet directional spreading or droplet contrasting spreading effectively. On the wettability‐optimized TPAs, the droplet can achieve the strong anisotropy with high length/width ratios (i.e., 11/1). Furthermore, unique TPAs with contrasting tilt angles can achieve the two droplets to form the contrasting spreading so as to gather together as a microreactor. It is revealed that such controlled spreading ability of TPAs is attributed to the cooperation of gradient surface energy resulted from the effect of tilt angles and the controllable surface wettability. The findings offer insights into the design of novel fluid‐controlling surfaces, which can be extended to some realms, e.g., microfluidics or microreactors.

On the temporal modelling of solar photovoltaic soiling: Energy and economic impacts in seven cities

This work developed a framework to predict the energy and economic impacts of solar photovoltaic soiling. This framework includes the effects of relative humidity, precipitation and tilt angle on solar photovoltaic soiling. A concept of relative net-present value change was introduced to determine the optimal cleaning interval. The uncertainties in the economic analysis were accounted for using a Monte Carlo simulation method. The framework was used to study the soiling-induced efficiency and economic losses of solar photovoltaic modules in seven cities (i.e. Taichung, Tokyo, Hami, Malibu, Sanlucar la Mayor, Doha, and Walkaway). Overall, the efficiency loss (in ascending order) for Tokyo/Walkaway < Taichung < Sanlucar la Mayor < Malibu/Hami < Doha for a one-year study period. Doha experiences an efficiency loss over 80% for a 140-day exposure, while Tokyo has an efficiency loss less than 4% for a one-year exposure. Malibu has longest optimal cleaning intervals (70 days for manual cleaning and 49 days for machine-assisted cleaning) that leads to the relative net-present value changes of 1.7% and 1.1%. Doha has the shortest optimal cleaning intervals (23 days for manual cleaning and 17 days for machine-assisted cleaning) that leads to the relative net-present value changes of 21% and 19%. The work serves as an effective tool for designing optimal cleaning protocols for solar photovoltaic systems.

Effects of tool tilt angle on the in-process heat transfer and mass transfer during friction stir welding

Tool tilt angle in friction stir welding (FSW) is an important factor that influences the joint quality, but the underlying mechanism has not been fully understood due to the lack of in-process observation. In this study, we present a CFD model, in which a geometrical model and an incomplete contact boundary condition are proposed, to investigate the effects of tool tilt angle on the in-process heat transfer and mass transfer during FSW. Three effects of tool tilt angle on heat transfer and mass transfer have been concluded based on the simulation results. First, a higher temperature is generated by the tilt welding tool on the advancing side (AS), which is attributed to the incomplete contact at the shoulder/workpiece interface. Second, the tilt welding tool generates a higher frictional force at the tool/workpiece interface, which significantly improves the interfacial material flow velocity behind the tool. Third, the tilt welding tool generates a stronger stirring action to the material in the vicinity of the welding tool, which is beneficial for the mixing of materials and the formation of friction stir welds. The approaches and concepts in this study can be used for the optimization of the application of tool tilt angle in FSW.

Heat dissipation characteristics from photovoltaic cells within the partitioned or non-partitioned glazed cavity to the windy environment

Abstract A numerical model, whose computation domain contains the glazed shallow cavity and surrounding wind field, has been proposed to investigate the characteristics of heat dissipation from photovoltaic cells within the glazed cavity to the windy environment. To reflect the actual working characteristics, both the photoelectric conversion characteristic and surface radiation were considered. The temperature distribution of PV cells particularly the hot spot temperature has been displayed to reveal the effect of tilt angle (α) and wind velocity (v). Then a thorough analysis was presented in virtue of visualized results, convection Nusselt number inside the cavity (Nucin) and total heat loss coefficient (Ut). Meanwhile, efforts were also performed to compare the partitioned and non-partitioned cavities. Results show that hot spot position at α = 15° has the obvious diversity due to the variation of wind velocity. Unlike the increased Nucin, total heat loss coefficient of PV cells at v = 5 m/s decreases when the tilt angle shifts from 15° to 30°. Further, it is found that hot spot temperature difference between the three cells shrinks in the partitioned cavity, and the partition indeed contributes to the improvement of PV cells temperature uniformity, which plays a positive role in the protection of PV cell property.