Effect Of Tilt Angle Research Articles

Influence of Surface Tilt Angle on a Chromatic Confocal Probe with a Femtosecond Laser

This paper presents an intentional investigation of the effect of the object tilt angle on the tracking local minimum method (TL method), which is the one for detecting the measurement target position of the object optical axis, in a chromatic confocal probe employing a differential dual-fiber-detector optical system with a mode-locked femtosecond laser as the light source. The effect of the object tilt angle on dual-detector confocal probes, and even chromatic confocal probes, has not been investigated in detail so far, although the effect of object tilt angle on scanning confocal probes has been studied. At first, to examine the influence of the object tilt angle on the TL method, a theoretical model is established, and numerical simulations are performed based on the established theoretical equation. Then, the effect of aberrations in confocal optics on the confocal response curve is investigated in experiments. Finally, investigations on the effect of the object tilt angle on the TL method are demonstrated in experiments.

Study of soiling on PV module performance under different environmental parameters using an indoor soiling station

Soiling of PV modules is a rather overlooked complex phenomenon and to better understand the phenomenon, the direction of research has now shifted towards studying soiling in controlled environment. In this work, the effect of tilt angle, humidity, temperature, and wind speed on soil deposition process and consequently the effect on PV module performance was investigated using recently developed homemade soiling station. Results showed that at tilt angles of 0⁰, 33.6⁰, and 60⁰, the corresponding soiling loss was 25.71%, 19.57%, and 15.8% respectively. Similarly, for temperature values of 25 °C, 40 °C, 55 °C, and 70 °C, the soiling loss was found to be 4.85%, 3.87%, 3.13 %, and 1.12% respectively. Furthermore, current gain due to air cleaning at 85% humidity was comparatively very low even at higher wind speeds owing to firm settlement of soil on module surface. Besides, at higher humidity levels self-cleaning patterns due to trickling of droplets with variations in tilt angles were also observed. These findings can help design and optimize the performance of outdoor PV systems and need to develop environment-specific cleaning systems for optimal performance of PV modules as well keeping the dominant contributing soiling factor in view.

Investigation of metallurgical characterization and mechanical properties of double-sided friction stir welding of aluminum 6061 T6 alloy

In the present study, the effect of tool tilt angle was investigated to appraise the metallurgical and mechanical behavior of double-sided friction stir welded joints of AA-6061 T6 alloy of 6 mm thick plates, using scrolled shoulder and frustum tool pin geometry. Two friction stir welded joints, with 0° (Joint J1) and 2° (Joint J2) tool tilt angles were fabricated using a fixed travel speed of 50 mm/min and tool rotational speed of 800 rpm. The metallurgical studies carried out by the electron backscattered diffraction showed that the incorporation of tool tilt angle resulted in the refinement of grains within the stir zone to a larger extent. The transverse tensile test results revealed that the joint efficiency of the J2 welded joint improved by 12% as compared to the J1 joint. The layered tensile specimens extracted from the different regions (first pass, second pass, and overlap region) of the stir zone of both the welded joints showed an appreciable variation in mechanical and metallurgical properties. The V-notch Charpy impact toughness test for J2 joint showed 16% higher toughness, with the presence of a 55% shear area fraction in the fractured impact specimens, as compared to the 30% for the J1 joint.

The Application of Balance Exercise Using Virtual Reality for Rehabilitation.

To prevent falls, it is important to devise a safe balance training program that can be easily performed. This study investigated whether tilting an image in virtual reality (VR) can generate a center-of-gravity sway. Five men and five women were asked to rest standing upright (control condition) and to rest standing upright with a head-mounted display showing a tilted virtual image (VR condition), and changes in their standing balance were observed. Standing balance was assessed by measuring the distance traveled by the center of pressure (COP) of each of the participants’ legs. In order to investigate the effects of different tilt speeds and angles on COP, four different images were displayed in VR: an image tilting to 10° moving at a rate of 1°/s; an image tilting to 20° moving 1°/s; an image tilting to 10° moving 10°/s; an image tilting to 20° moving 10°/s. Change in COP was significantly greater in the VR than in the control condition (p < 0.01), and a tilt of 10° moving 1°/s showed the greatest change in COP (p < 0.01). Tilting an image in VR while in a resting standing position can change an individual’s COP; thus, VR may be applied to balance training.

Effect of Tool Positioning Factors on the Strength of Dissimilar Friction Stir Welded Joints of AA7075-T6 and AA6061-T6.

Friction Stir Welding (FSW) is a solid-state bonding technique. There are many direct and indirect factors affecting the mechanical and microstructural properties of the FSW joints. Tool offset, tilt angle, and plunge depth are determinative tool positioning in the FSW process. Investigating the effect of these factors simultaneously with other parameters such as process speeds (rotational speed and translational speed) and tool geometry leads to a poor understanding of the impact of these factors on the FSW process. Because the three mentioned parameters have the same origin, they should be studied separately from other process parameters. This paper investigates the effects of tilt angle, plunge depth, and tool offset on Ultimate Tensile Stress (UTS) of joints between AA6061-T6 and AA7075-T6. To design the experiments, optimization, and statistical analysis, Response Surface Methodology (RSM) has been used. Experimental tests were carried out to find the maximum achievable UTS of the joint. The optimum values were determined based on the optimization procedure as 0.7 mm of tool offset, 2.7 degrees of tilt angle, and 0.1 mm of plunge depth. These values resulted in a UTS of 281 MPa. Compared to the UTS of base metals, the joint efficiency of the optimized welded sample was nearly 90 percent.

Numerical Prediction and Suppression of Thermoacoustic Longitudinal Mode in Annular Combustor

Many industrial applications, such as gas turbines or aeroengines, are subject to thermoacoustic instability, especially in the lean combustion regime. In this paper, the linearized Navier–Stokes equations (LNSEs) framework is applied to predict the acoustic liner damping effects with real geometry and different bias flow velocities. The results show that the LNSEs can capture the tilt angle effect of the orifice or grazing and bias flow coupling phenomenon. The forced large-eddy simulation results of premixed methane flame present the same trend in gain and phase of the flame transfer function with the equation. Then, the flame response model is coupled into the Helmholtz and LNSE solvers. The mean flow from Reynolds-averaged Navier–Stokes calculation is used in the LNSEs, and no assumption of liner geometry is made. The linear stability analysis reveals that the velocity fluctuation in the combustion is also damped when a stable acoustic mode is achieved with the acoustic liner. The flame dynamic, the hydrodynamic, and the acoustic phenomena can all be considered when using the LNSEs. This indicates that the LNSEs may allow us to consider a more complex mechanism that can affect the thermoacoustic inability in the combustor system and help us to design better dampers to control.

Modeling photovoltaic-electrochemical water splitting devices for the production of hydrogen under real working conditions

Photoelectrochemical splitting of water is potentially a sustainable and affordable solution to produce hydrogen from sun light. Given the infancy stage of technology development, it is important to compare the different experimental concepts and identify the most promising routes. The performance of photoelectrochemical devices is typically measured and reported under ideal irradiation conditions, i.e. 1 sun. However, real-life operating conditions are very different, and are varying in time according to daily and seasonal cycles. In this work, we present an equivalent circuit model for computing the steady state performance of photoelectrochemical cells. The model allows for a computationally efficient, yet precise prediction of the system performance and a comparison of different devices working in real operating conditions. To this end, five different photoelectrochemical devices are modeled using experimental results from literature. The calculated performance shows good agreement with experimental data of the different devices. Furthermore, the model is extended to include the effect of illumination and tilt angle on the hydrogen production efficiency. The resulting model is used to compare the devices for different locations with high and low average illumination and different tilt angles. The results show that including real illumination data has a considerable impact on the efficiency of the PV-EC device. The yearly average solar-to-hydrogen efficiency is significantly lower than the ideal one. Moreover, it is dependent on the tilt angle, whose optimal value for European-like latitude is around 40°. Notably, we also show that the most performing device through the whole year might not necessarily be the one with highest sun-to-hydrogen efficiency for one-sun illumination.

Tilt Angle’s Effects on Free Convection Heat Transfer Coefficient inside a Water-Filled Rectangular Parallelepiped Enclosure

The effect of tilt angle on free convection heat transfer is investigated experimentally inside a rectangular parallelepiped cavity filled with water. The cavity had the dimensions S × S × H (m3), where S was the inside length, and H was the inside height of the cavity. The lower surface was subject to constant heat flux, and the upper surface was cooled by a stream of ambient air. The free convection heat transfer data were generated using different uniform heat fluxes. Four tilt angles were considered: 0°, 30°, 60°, and 90°. The surface temperature measurements were collected 10 h after the experimental run to ensure that a steady-state was reached. It was noticeable that the free convection heat transfer strongly depended on the tilt angle and the modified Rayleigh numbers. The 3D results showed that the Nusselt number reached a maximum at 60° at a fixed modified Rayleigh number. An enhancement in the Nusselt number at any tilt angle was observed over that of a zero tilt angle, and the percent of enhancement was 7.92–62.38%, depending on the modified Rayleigh numbers and the tilt angle. It was also observed that as the modified Rayleigh number increased, the temperature uniformity on both the hot and cold surfaces was disturbed. Furthermore, an empirical correlation between the modified Rayleigh numbers and Nusselt numbers was obtained for each angle. Moreover, two overall general correlations are obtained to cover the four tilt angles (i.e., 0°, 30°, 60°, and 90°) and the modified Rayleigh numbers, which should be helpful for engineering applications.

Tilt Angle Effect on Friction Stir Welding Conditions

In this paper, the effect of tool tilt angle on heat generation and forging force for 1050 aluminum plates, welded by friction stir butt welding, were investigated. Usage of the welding tool with and without pin made it possible to elucidate the particularly reactions of the pin and shoulder on tilt angle variation. For this purpose, tool tilt angle was varied from 0⁰ to 3⁰ under other constant parameters, such as tool geometry and of tool traverse-rotation speed ratio. For the estimation shoulder work pieces interaction the Reynolds lubricant film theory equations were used. The results indicate that the tilt angle is an effective factor on material forging and heat generation behind the pin in the Advancing Side (AS). Recorded peak temperatures were varied from 312 °C to 442 °C in the weld centre.

Performance Evaluation of a MW-Size Grid-Connected Solar Photovoltaic Plant Considering the Impact of Tilt Angle

This paper presents a study for the estimation of generation from a large-scale, grid-interfaced solar PV plant using the PVsyst software. This study aims to investigate the effect of tilt angle on the performance of the grid-integrated solar PV plant. Two types of tilt angle test plants, i.e., a fixed tilt angle of 30° (1 MW) and two seasonal tilt angles, in summer 13° and in winter 30° (2.5 MW), have been selected at the same location in Bikaner, India. The performance of the proposed test solar power plants, rated at 1 MW (fixed tilt angle) and 2.5 MW (two seasonal tilt angles), is established by comparing the results obtained using the PVsyst software with the practical data of annual solar insolation. It is established that the radiation incident on PV modules will increase by 2.41% if two seasonal tilt angles are considered. Hence, the annual capacity utilization factor (CUF) has increased by 0.26%. Furthermore, it is established that the proposed method’s performance is superior compared to the statistical methods reported in the literature.

Effect of Tilt Angle and Plunge Depth of Welding Tool on Friction Stir Lap Welding of Steel Sheet and Aluminum Alloy Sheet

Effect of Tilt Angle and Plunge Depth of Welding Tool on Friction Stir Lap Welding of Steel Sheet and Aluminum Alloy Sheet

Effects of Head Tilt and Kana Optotype Presentation Angle on Visual Acuity

Effects of Head Tilt and Kana Optotype Presentation Angle on Visual Acuity

Wind loads on roof-mounted isolated solar panels of tall buildings through wind tunnel testing

A series of pressure tests were conducted to systematically investigate the wind loads on isolated solar panels mounted on the rooftops of tall buildings. The effects of panel location, tilt angle (β = 15°, 30°, and 45°), and building height (H = 24, 48, 72, and 96 m) were examined. Peak loads from taps were found two times as large as that from modules and panels. An increase in H induced a decrease in the largest mean and negative peak net panel force coefficients, which is attributed to the enhanced two-dimensionality of flows for buildings with lower heights. Specifically, the largest most critical negative peak net panel force coefficients at H = 24 m were approximately 20% larger than those at H = 96 m. Attention should be paid to wind loads on roof-mounted solar panels attached to buildings with lower heights. Besides, buildings with lower heights tend to cause more significant fluctuations of wind pressure on solar panels. Moreover, rooftop solar panels on buildings with lower heights are likely to have positive mean panel force coefficients due to the flow reattachment over roofs.

Effect of orientation and tilt angles of solar collectors on their performance: Analysis of the relevance of general recommendations in the West and Central African context

Installing solar panels or collectors with optimum orientation and tilt angles to maximise energy generation over a specific period is important to improve the economics of solar systems, and hence, their large-scale utilisation. As a general rule, for installations aiming at maximum annual solar production in the intertropical region, it is recommended to point the panel towards the Equator at a tilt angle equal to the local latitude. However, there are several situations where it is difficult or even impossible to follow these general recommendations, for example in case of the presence of an obstacle creating shading, inadequate orientation or slope of the roofs, or when roofs are inaccessible. This raises the question of the impact of non-compliance with the general recommendations on solar systems’ performance. We have used RETScreen software for the calculation of annual average irradiation on tilted panels in various locations in West and Central Africa, namely in the capital cities (latitudes between 0° N and 15° N). For each site, the maximum annual solar irradiation is simulated and taken as a reference value. The annual irradiations for various orientations and tilt angles were then recorded and compared to the reference. It appears that in West and Central Africa, a moderate deviation (up to 20°) from the optimal orientation and inclination does not significantly influence the incident solar radiation (reduction in irradiation < 5%). Construction of structures dedicated to solar installations or architectural modification to comply with general recommendations is therefore generally not justified. A set of diagrams and tables, which allow us to quickly determine the percentage of incident solar radiation on a solar panel based on its orientation and tilt angle compared to the optimal tilt and orientation for any capital city in West and Central Africa, is provided.

Tool tilt angle induced variation of shoulder-workpiece contact condition in friction stir welding

The effect of tool tilt angle has not been appropriately considered in modelling friction stir welding process. In this study, the expressions to determine incomplete contact region caused by tool tilt were derived and experimentally verified. Correspondingly, the axial stress, slip rate, friction coefficient were modified separately in complete and incomplete contact regions. It was found that with the increase of tool tilt angle from 1.5° to 4°, the material flow ability towards the advancing side was enhanced at trailing side, the temperature at shoulder/workpiece interface increased from 788 to 810 K, while that at pin/workpiece interface increased from 777 to 802 K. The calculated interface temperature and the thermo-mechanically affected zone boundary were in good agreement with the measured ones.

Charge Transport in Full-Size HVDC Cable Joint with Modeling of XLPE/EPDM Interface

Charge transport in high-voltage direct-current (HVDC) cable joint with complicated structure has not been profoundly investigated. In this study, a two-dimensional electrothermal coupled charge transport model combining finite element method (FEM) and bipolar charge transport algorithm is proposed, and the effects of temperature gradient and stress cone tilt angle on charge transport and electric field distribution in a 320 kV HVDC cable joint is investigated by this model. In the simulation, the interfacial area between the cross-linked polyethylene (XLPE) cable insulation and the ethylene-propylene-diene monomer (EPDM) joint insulation is specially modeled with different trap parameters from XLPE and EPDM. To obtain the simulation parameters, simultaneous measurements of space charge and relaxation current are performed on XLPE/EPDM double-layer samples, XLPE single-layer samples, and EPDM single-layer samples. It is found that with the increase of temperature gradient, more positive charges are injected and migrate from the inner side of XLPE insulation to the interface, thus, the charges accumulated at the interface change from negative to positive under large temperature gradient. At the same time, the position of the maximum electric field changes from the inner side of XLPE insulation to the root area of the stress cone at the interface. With the increase of the stress cone tilt angle, both the positive charges in XLPE insulation and the negative charges near the stress cone become less, and the overall maximum electric field first decreases and then increases under 20°C temperature gradient.

Development of a dual sideway-share subsurface tillage implement: Part 2. Effect of tool geometry on tillage forces and soil disturbance characteristics

Simulation of tillage tool-soil interactions provides opportunities to accelerate new equipment design and evaluate its performance. The dual bent blade subsurface tillage implement which its performance has been evaluated in the field, is a new conservation tillage tool deserving its soil cutting efficiency to be improved by optimizing its geometry using discrete element method (DEM) modeling. In order to achieve this objective, the effect of share size (5.9, 7.6, 11.3, 16.8, 22.6 and 28.2 cm), rake angle (7.5°, 15°, 25°, 30°, 35° and 40°), tilt angle (10°, 20°, 25°, 30°, 35° and 40°), and shank rake angle (45°, 60°, 75°, 90° and 97.5°) of the tool plowing at 150 mm depth, on soil cutting forces and soil disturbance characteristics were investigated using the validated DEM model developed in part 1 of this study. Results showed that the draft and vertical forces increased with increasing share size, while the specific resistance (SR) decreased. With increasing share rake angle, the draft force, SR, upward vertical force and the degree of soil pulverization increased. The minimum SR of the tool was at the tilt angle of 20°. But at this tilt angle, the uniformity of the cutting-depth for a long share-size was low, due to greater lateral bending of the share. As the rake angle of the shank decreased, the draft and vertical upward forces decreased. DEM simulation results showed that an efficient non-inversion tillage implement design can be achieved by developing a dual sideway-share subsurface tillage tool having a total cutting width of 53 cm with the rake and tilt angles of 15° and 10°, respectively, and attached to a 75°-rake-angle shank and plowing 150 mm deep in a sandy clay loam soil.

Numerical Analysis of Drag Reduction Characteristics of Biomimetic Puffer Skin: Effect of Spinal Height and Tilt Angle.

Based on the migratory phenomenon of the puffer and the cone-shaped structures on its skin, the effects of spinal height and tilt angle on the drag reduction characteristics is presented by numerical simulation in this paper. The results show that the trend of total drag reduction efficiency changes from slow growth to a remarkable decline, while the viscous drag reduction efficiency changes from an obvious increase to steady growth. The total and viscous drag reduction efficiencies are 19.5% and 31.8%, respectively. In addition, with the increase in tilt angle, the total drag reduction efficiency decreases gradually; the viscous drag reduction efficiency first increases and then decreases, finally tending to be stable; and the total and viscous drag reduction efficiency reaches 20.7% and 26.7%, respectively. The flow field results indicate that the pressure drag mainly originates at the front row of the spines and that the total pressure drag can be effectively controlled by reducing the former pressure drag. With the increase in low-speed fluid and the reduction in the near-wall fluid velocity gradient, the viscous drag can be weakened. Nevertheless, the drag reduction effect is achieved only when the decrement of viscous drag is greater than the increment of pressure drag. This work can serve as a theoretical basis for optimizing the structure and distribution parameters of spines on bionic non-smooth surfaces.

Effect of Welding Parameters on Mechanical Properties of Friction Stir Welding of Dissimilar Metals- A Review

This review article summarizes the extensive research works carried out on welding parameters (tool rotational speed, traverse speed, pin profile, axial force and tilt angle) effect on mechanical properties of FSW of dissimilar alloys. Extensive studies were being carried out by joining different materials using friction stir welding for different automobile and aerospace applications. FSW process takes place in the solid stage below the melting point of the metals to be joined and numerous materials including, aluminum, bronze, copper, titanium, steel, magnesium, and plastic can be welded. FS welded joints gives more strength and toughness when compared to fusion welded joints. FS welding technique is being used in many research institutes and production companies in the world.

Investigating the combined effects of mirror tilting and position on rutile crystal growth using the infrared convergent-heating floating zone method

Herein, the combined effects of tilt angle (θ) and position (MP) of mirror-lamp (M−L) systems on rutile crystal growth were examined using the infrared convergent-heating floating zone (IR-FZ) method. A θ value of 5.0° was effective in increasing the diameters of both the feed rod and grown crystal, yielding a grown crystal diameter of 21 mm using a feed rod with a diameter of 22 mm at MP = 0 mm. Therefore, the convergent position of the M−L system lies on the rotation axes of the feed rod and grown crystal. The grown crystal diameter was increased by θ and MP optimization. The maximum diameter of the grown crystal achieved to 24 mm in the condition of the θ = 7.5° and MP = 4 mm, using a feed rod with a diameter of 25 mm.