Showing papers on "Tilt (optics) published in 2021"

Effect of tilt angle on the performance and electrical parameters of a PV module: Comparative indoor and outdoor experimental investigation

Abstract: Photovoltaic (PV) system's performance is significantly affected by its orientation and tilt angle. Experimental investigation (indoor and outdoor) has been carried out to trace the variation in PV performance and electrical parameters at varying tilt angles in Malaysian conditions. There were two experimental modus: 1) varying module tilt under constant irradiation level, 2) varying irradiation intensity at the optimum tilt set up. For the former scheme, the irradiation level was maintained at 750 W/m2, and for the later arrangement, the module tilt angle was varied from 0o to 80o by means of a single-axis tracker. Results show that under constant irradiation of 750 W/m2, every 5o increase in tilt angle causes a power drop of 2.09 W at indoor and 3.45 W at outdoor. In contrast, for the same condition, efficiency decreases by 0.54% for indoor case and by 0.76% at outdoor. On the other hand, for every 100 W/m2 increase in irradiation, solar cell temperature rises by 7.52°C at indoor and by 5.67°C at outdoor. As of module electrical parameters, open-circuit voltage, short-circuit current, maximum power point voltage and maximum power point current drops substantially with increasing tilt angle, whereas fill factor drops rather gradually. Outdoor experimental investigation confirms that the optimum tilt angle at Malaysian conditions is 15o and orienting a PV module this angle will maximize the sun's energy captured and thereby enhance its performance.

Space-time wave packets violate the universal relationship between angular dispersion and pulse-front tilt.

Abstract: Introducing angular dispersion into a pulsed field tilts the pulse front with respect to the phase front. There exists between the angular dispersion and pulse-front tilt a universal relationship that is device-independent, and also independent of the pulse shape and bandwidth. We show here that this relationship is violated by propagation-invariant space–time (ST) wave packets, which are pulsed beams endowed with precise spatiotemporal structure corresponding to a particular form of angular dispersion. We demonstrate theoretically and experimentally that ST wave packets represent, to the best of our knowledge, the first example in optics of non-differentiable angular dispersion, resulting in pulse-front tilt that depends on the square-root of the pulse bandwidth.

Assessment the potential solar energy with the models for optimum tilt angles of maximum solar irradiance for Iraq

Abstract: This work aims to assess the potential solar energy and determine the optimum tilt angles of maximum solar irradance in Iraq. The south-facing optimum tilt angle has been determined for eighteen cities of Iraq for estimation the solar radiation capacity. The optimisation process is performed by using hourly experimental solar radiation data for nineteen years. The results demonstrated that the maximum solar radiation can be collected with the tilt angle from 0° to 64°, where the optimum angle is evaluated/determined by searching for the values of the maximum total hourly-daily irradiance with the 1° resolution. The optimum tilt angle values increased during winter and decreased during summer, marking the highest values in January and December and the lowest values in June and July for all cities. The cities in the north of Iraq have higher optimum tilt angles values than those in the middle and south parts. Furthermore, a three general models are developed and validated for obtaining monthly and yearly optimum tilt angles positioning for estimation maximum irradiance.

On the performance of phase-based filters for enhancing lateral boundaries of magnetic and gravity sources: a case study of the Seattle uplift

Abstract: Determining lateral boundaries of the potential field source is a common feature in interpreting magnetic and gravity data. There are many different phase based filters to determine the boundaries of the source. The purpose of this study is to compare the performance of phase-based filters such as tilt derivative, theta map, normalized horizontal derivative, tilt derivative of the horizontal derivative, tilt derivative of the total gradient, improved theta and horizontal gradient of a modified version of tilt derivative. In order to obtain optimum results, these filters were tested on synthetic magnetic and gravity anomaly data and also aeromagnetic anomaly from the Seattle Uplift (SU), Washington, United States of America. The results show that the tilt derivative of the horizontal derivative method revealed better detection of the source edges compared to the results by the other filters. These results demonstrate that the tilt derivative of the horizontal derivative method is a useful tool for the qualitative interpretation of magnetic and gravity data.

Performance Evaluation of Amplitude- and Phase-Based Methods for Estimating Edges of Potential Field Sources

Abstract: Edges of potential field sources often denote geologic features and are therefore a problem of fundamental importance in geological interpretation. There are many different methods for locating the source edges, most of which are based on the derivatives of the potential field data. In general, these methods can be divided into two main groups, namely amplitude-based methods and phase-based methods. This study compares the performance of popular amplitude- and phase-based edge detection methods such as total horizontal gradient, analytic signal (also called total gradient), enhanced analytic signal, directional analytic signal, tilt derivative, theta map, horizontal tilt angle, hyperbolic tilt angle, and enhanced total horizontal gradient. The methods are tested on synthetic magnetic data, as well as synthetic gravity data with and without noise. Furthermore, the methods are also applied to real magnetic and gravity data sets from northeast Vietnam as practical examples. The results show that the enhanced total horizontal gradient performs better than other methods under almost all scenarios.

3D Printed Interdigitated Capacitor based Tilt Sensor

Abstract: This paper presents a tilt sensor comprising of 3D printed capacitive sensors located at the four ends of a ‘+’ shaped channel to provide the orientation of objects by using the capacitive fluid level measurement concept. The interdigitated capacitive sensors were developed by 3D printing and the channel was filled with ecoflex and silicone oil to obtain two variants of tilt sensor. The results show a change in the capacitance of ~11.5% and ~9.53% for ecoflex and silicone oil-based sensors respectively. A drift of ~2.6% is observed for ecoflex and ~0.16% for silicone oil. Considering the lower viscosity and the lower drift, the silicone oil-based tilt sensors were further investigated and two tilt sensors with varying silicone volumes (1ml and 1.5ml) were fabricated and compared for tilt angles ranging from 0° to 30°. The result from all four interdigitated capacitive sensors in the tilt sensing structure show similar rate of change in capacitance (~0.67% per degree increase in the tilt angle) with a standard deviation of ~±0.1%. However, the sensor with higher volume of silicone oil (1.5ml) saturated at a tilt angle of ~20° which is ~10° smaller than the response of the sensor fabricated with 1ml of silicone oil (saturated at 30°). We also demonstrate the possibility of extending the sensor range by optimizing the volume of fluid and the channel’s fluid capacity. With integration of fabricated tilt sensor with a robots’ body, white cane or smart objects etc., it will be possible to obtain the information about orientation.

Quantification of wake shape modulation and deflection for tilt and yaw misaligned wind turbines

Abstract: Misaligned wind turbine rotors redirect the wake, and manipulate the wake shape by introducing a counter-rotating vortex pair. This mechanism is of great interest for improving wind farm power output through static or dynamic misalignment. In this study, cross-plane stereo-particle image velocimetry measurements are used to characterize the wake evolution for tilt misalignment and verify differences with yaw misalignment. Blockage from the ground, shear in the velocity profile, turbulence levels, hub-vortices and tip-vortices are found to strongly affect wake evolution for a tilted wind turbine resulting in a non-symmetric behaviour for upwards deflecting or downwards deflecting tilt. The downwards deflection of a negatively tilted wind turbine is found to result in the most benefits for wake recovery and power availability downstream through increased wake-curling, faster wake-recovery, and downdraft of high-momentum flow.

Novel 3D-printed biaxial tilt sensor based on fiber Bragg grating sensing approach

Abstract: In this work, a novel 3D-printed biaxial sensor system for tilt measurement, based primarily on the use of four Fiber Bragg Grating (FBG) devices, has been developed and its performance characterized. The tilt sensor system created is of a compact design and relatively small dimensions, making it ideally suited to a variety of industrial applications. In the system developed, the four FBGs used were spliced in a serial formation and attached to four different sides of the sensor structure designed, to allow biaxial measurements to be made. The wavelengths' shift of the FBGs used were monitored as a function of the tilt of the device, using an Optical Spectrum Analyzer (OSA) for this development work. In the sensor, an average FBG-based responsivity of 0.01 nm/° of tilt was measured for each of the different FBGs used. To provide compensation for temperature changes in the system itself, a further FBG-based approach was used (in which they were configured to be insensitive to the effect of the tilt). They were thus calibrated by being exposed to a range of operational temperatures for the system, showing, as a result, a calibration of 0.011 nm/°C. Prior work on the sensor system had proved it to be highly linear in response, over the tilt range of 0° ± 90°. The experimental results obtained from the performance characterization indicate that the small, compact design of this type yields excellent responsivity, compared to other larger and more complex designs discussed in the literature. The sensor system was also relatively easy to fabricate using the 3D-printing method, creating in that way an inexpensive, temperature-compensated tilt monitoring device that had a wide variety of potential industrial applications.

Tilt mapping for zigzag-shaped concrete panel in retaining structure using terrestrial laser scanning

Abstract: Traditional monitoring systems are not able to monitor the global behavior of large retaining structures, and terrestrial laser scanning was performed for monitoring a retaining structure for this paper. The three-dimensional point cloud was obtained by scanning at seven locations with seven reference targets to cover the retaining structure having 180 m length and 25 m high. To evaluate the long-term behavior of the retaining structure, point clouds obtained by performing eight laser scanning at the same locations over 4 years were compared with each other. In this paper, the tilt mapping method was applied to define the global behavior of the entire retaining structure. The P2P-TA (Plane-to-Plane-Tilt Angle) comparison method was used to calculate the tilt angle by comparing the normal vectors of the planes created by the point clouds, because simple comparison methods are not able to be applied to compare points clouds of zigzag-shaped concrete panels. A laboratory test was conducted to determine the applicability of laser scanning and P2P-TA analysis, and the error range was conservatively set to 0.15°. The results of laser scanning and P2P-TA analysis applied to 231 concrete panels are shown in the tilt mapping of the retaining structure. The differential tilt angle was significantly increased every year at the bottom of the concrete panel adjacent to the tunnel. It can be seen that the concrete panel having a large differential tilt angle affects the differential tilt angles of others, because it is linked to other concrete panels.

Sunspot tilt angles revisited: Dependence on the solar cycle strength

Abstract: The tilt angle of sunspot groups is crucial in the BL type dynamo. Some studies have shown that the tilt coefficient is anti-correlated with the cycle strength. If the anti-correlation exists, it will be shown to act as an effective nonlinearity of the BL-type dynamo to modulate the solar cycle. However, some studies have shown that the anti-correlation has no statistical significance. We aim to investigate the causes behind the controversial results of tilt angle studies and to establish whether the tilt coefficient is indeed anti-correlated with the cycle strength. We first analyzed the tilt angles from DPD. Based on the methods applied in previous studies, we took two criteria to select the data, along with the linear and square-root functions to describe Joy's law, and three methods to derive the tilt coefficients for cycles 21-24. This allowed us to evaluate different methods based on comparisons of the differences among the tilt coefficients and the tilt coefficient uncertainties. Then we utilized Monte Carlo experiments to verify the results. Finally, we extended these methods to analyze the separate hemispheric DPD data and the tilt angle data from Kodaikanal and Mount Wilson. The tilt angles exhibit an extremely wide scatter due to both the intrinsic mechanism for its generation and measurement errors, for instance, the unipolar regions included in data sets. Different methods to deal with the uncertainties are mainly responsible for the controversial character of the previous results. The linear fit to the tilt-latitude relation of sunspot groups with $\Delta s>2.5$ of a cycle carried out without binning the data can minimize the effect of the tilt scatter on the uncertainty of the tilt coefficient. Based on this method the tilt angle coefficient is anti-correlated with the cycle strength with strong statistical significance.

The Effect of Azimuth and Tilt Angle Changes on the Energy Balance of Photovoltaic System Installed in the Southern Slovakia Region

Abstract: Energy balance of the photovoltaic system is influenced by many factors. In this article the effect of tilt and azimuth angle changes of the photovoltaic system energy production is analyzed. These parameters have significant impact on the amount of solar radiation which hits on the photovoltaic panel surface and therefore also on the energy absorbed by the module surface. The main aim of research was identification of the optimal position of photovoltaic system installation in the southern Slovakia regions. The experimental apparatus had two setups consisting of polycrystalline photovoltaic modules. The first setup was used for identification of the tilt angle changes in the range (0–90°). The second one was focused on the detection of the azimuth angle effect to the energy production. The measurement results were statistically processed and mathematically analyzed. Obtained dependencies are presented as two-dimensional and three-dimensional graphical relations. Regression equations characterize time relations between the tilt or azimuth angle and the energy produced by the photovoltaic system in Southern Slovakia. Obtained simplified mathematical model was verified by analytical model. Presented models can be used for the dimensioning and optimization of the photovoltaic system energy production.

Determining Optimum Tilt Angle for 1 MW Photovoltaic System at Sukkur, Pakistan

Abstract: Solar energy is directly converted into electrical energy by using photovoltaic (PV) panels. The efficiency of PV panel varies with its orientation and tilt angle with the horizontal plane. In this paper, we investigate the optimum tilt angle of solar panels installed at Sukkur IBA University. The optimum angle for tilted surfaces varying from 0° to 90° in steps of 1° was calculated for the values of which the daily total solar radiation was maximum for a specific period. It was found that the optimum tilt angle changed between 0° and 61.1° throughout the year in Sukkur IBA University, Sindh Pakistan ( N, E). For calculating irradiance, optimal fixed (15 and 29.5 degrees) and variable tilt angles are used for every month of year 2019. The irradiance calculated at 15 degrees tilt angle is compared with the fixed angle of 29.5 and variable angles. It was found that optimal tilt angle for the region of Sukkur located in northern Pakistan is to be 29.5 degrees.

Research on Model Predictive Control for Automobile Active Tilt Based on Active Suspension

Abstract: To improve the handling stability of automobiles and reduce the odds of rollover, active or semi-active suspension systems are usually used to control the roll of a vehicle. However, these kinds of control systems often take a zero-roll-angle as the control target and have a limited effect on improving the performance of the vehicle when turning. Tilt control, which actively controls the vehicle to tilt inward during a curve, greatly benefits the comprehensive performance of a vehicle when it is cornering. After analyzing the advantages and disadvantages of the tilt control strategies for narrow commuter vehicles by combining the structure and dynamic characteristics of automobiles, a direct tilt control (DTC) strategy was determined to be more suitable for automobiles. A model predictive controller for the DTC strategy was designed based on an active suspension. This allowed the reverse tilt to cause the moment generated by gravity to offset that generated by the centrifugal force, thereby significantly improving the handling stability, ride comfort, vehicle speed, and rollover prevention. The model predictive controller simultaneously tracked the desired tilt angle and yaw rate, achieving path tracking while improving the anti-rollover capability of the vehicle. Simulations of step-steering input and double-lane change maneuvers were performed. The results showed that, compared with traditional zero-roll-angle control, the proposed tilt control greatly reduced the occupant’s perceived lateral acceleration and the lateral load transfer ratio when the vehicle turned and exhibited a good path-tracking performance.

Modulation of Magnetospheric Substorm Frequency: Dipole Tilt and IMF B y Effects

Abstract: Using five independent substorm onset lists, we show that substorms occur more frequently when the Interplanetary Magnetic Field (IMF) By component and the dipole tilt angle Ψ have different signs ...

Determination of the optimum tilt angle for photovoltaic modules in Senegal

Abstract: This paper deals with finding the optimum tilt angle of solar panels for solar energy applications. The objective is to maximize the output electrical energy of the photovoltaic (PV) modules. A mathematical model was used to determine the optimum tilt angle of solar collectors in Senegal on a daily and monthly basis, as well as for a specific period. Then, the configuration of the optimum tilt angle was analyzed by studying four specific cases in different typical climatic zones in Senegal. On a horizontal plane, the sun spends more time in the south than in the north. This means that in Senegal, the optimum tilt angle is often set equal to latitude. On the other hand, the optimum latitude angle is only for annual optimization. This study shows that the optimum tilt angle equal to latitude does not produce maximum output. For monthly optimum tilt angle, only the month of November gives tilt optimum angles equal to latitude. It is preferable to change the tilt angle of solar conversion systems monthly instead of fixing them, to gain more energy. Keys words: Solar energy, solar panels, tilt angle, orientation solar panel, latitude, geometry.

Developing a model for predicting optimum daily tilt angle of a PV solar system at different geometric, physical and dynamic parameters

Abstract: Capturing the solar radiation that passed through the Earth’s atmosphere and received by solar panels depends on several parameters. In this paper, all governing parameters of the total daily solar...

Performance evaluation of a solar water heating system with glass-covered parabolic trough concentrators, under different system tracking modes

Abstract: The thermal performance of a new type of solar water heater system consists of an array of parabolic trough collectors was studied. In CFD simulation of the system, a practical mathematical model was proposed that the realistic non-uniform solar flux distribution obtained by optical analysis is implemented in thermal modeling of the system. The system performance was investigated in three different tracking modes, stationary south-face, tilted N–S axis with daily tilt adjustment, and full tracking mode under the complexity of non-uniform solar flux distribution on the outer surface of the water pipe. The system was studied experimentally in Isfahan, Iran, with latitude and longitude of 32.6539° N, 51.6660° E, respectively. In experiments, the inlet water mass rate in the range of 0.005–0.15 kg s−1, and inlet temperature in the range of 20–40 °C was investigated. The system’s average daily thermal efficiency at full tracking mode is greater than 60%, and at optimal conditions, the efficiency of more than 70% is also achievable. For the N–S axis with daily tilt adjusted equal to noontime zenith angle, its performance is greater than 45% and for the system at stationary mode with a tilt angle equal to local latitude is less than 40%. Results indicate that the system performance is severely affected by tracking errors, and the effect of these errors in tilt adjustment is more significant than surface azimuth adjustment. At full tracking mode, an accuracy error of 6° in tilt adjustment leads to a reduction of 10% in the system thermal efficiency, while the accuracy error up to 20° in azimuth adjustment has no significant effect on its performance.

Automated Measurement of Highly Divergent Optical Wavefronts With a Scanning Shack–Hartmann Sensor

Abstract: In this article, a Shack–Hartmann wavefront sensor is combined with a mechatronic positioning system to overcome the limited dynamic range of the Shack–Hartmann sensor (SHS) by repositioning and reorienting the SHS. Feedback loops to ensure a tangential orientation of the wavefront sensor in every measurement position and a measurement strategy that compensates for tip and tilt between wavefront and sensor are described and implemented. A framework that estimates the admissible measurement trajectories by relating the positioning errors caused by misalignments of the stages to the parameters of the wavefront sensor is developed. It is demonstrated that the setup is capable of directly measuring a highly divergent optical wavefront by combining wavefront data and positioning data acquired along the wavefront generated by a microscope objective with numerical aperture (NA) of 0.45.

Automobile active tilt based on active suspension with H∞ robust control:

Abstract: Automobile roll control aims to reduce or achieve a zero roll angle. However, the ability of this roll control to improve the handling stability of vehicles when turning is limited. This study prop...

Coherent beam combination of seven 1.5 µm fiber amplifiers through up to 1 km atmospheric turbulence: near- and far-field experimental analysis.

Abstract: A laser testbed based on active coherent beam combination (CBC) of seven 1.5 µm, 3 W fiber amplifiers was developed for applications requiring high power such as power density deposition on targets or free space laser communication. For the first time to our knowledge, the frequency-tagging locking of optical coherence by single-detector electronic-frequency tagging technique was implemented in the field in real atmospheric turbulence conditions in a target-in-the-loop configuration. Successful combination was achieved after horizontal propagation of 311 m and 1 km, at 1.5 m above the ground, while the estimated average turbulence strength was Cn2∼4.10−14m−2/3. We present the CBC laser bench and an embedded near-field interferometer called PISTIL (PISton and TILt) able to measure the relative phase shift of each emitter. We show that this measurement can provide information on relative turbulence-induced phase variation of the combined laser beams. In particular, the far-field beam envelope wandering can be estimated through this diagnosis. Results are supported by an analytical model and confirmed by numerical post-analysis of measured far-field interference. This additional interferometer may improve CBC beam pointing through turbulence.