Direction Angle Research Articles

Field measurement-based research on wind pressure interference effects of tracking photovoltaic arrays

This paper investigates the wind interference effect on the rear row of photovoltaic modules as wind passes through the front row in a multi-row tracking photovoltaic array. Through field wind pressure measurements, we comprehensively evaluated the wind pressure interference effect under various tilt angle and wind direction angles, including variations in the wind pressure coefficient, wind force coefficient, central axis torque coefficient, column base moment coefficient, and fluctuating wind pressure power spectrum. The results indicate that when the wind direction angle is perpendicular to the panel width (L), the interference effect on the rear row is more significant, observed as a shading effect on the rear wind pressure coefficient, wind force coefficient, central axis torque coefficient, and column base moment coefficient. The interference effect gradually weakens as the wind direction angle increases/decreases; in the small tilt angle range (0° < β < 15°), the interference effect on the rear row is minimal. Additionally, under high tilt angle conditions, the third row experienced relatively higher wind forces compared to the second row. The interference effect of the fluctuating wind pressure power spectrum primarily manifests in the variation of vortex shedding frequency, significantly affecting the frequency peak of the rear components in the high-frequency band. The sensitivity of vortex shedding to wind direction and tilt angle adds complexity to the wind-resistant design of tracked PV arrays. This study offers valuable insights for designing tracking photovoltaic arrays to withstand wind forces.

The Qibla Direction Problem in Large-Scale Maps and Its Representation with Geodetic Accuracy: The Case of Türkiye

In Islamic societies, knowing the direction of the Qibla is important in the planning of religious areas. In urban plans designed by practitioners where the Qibla direction is not considered, inconsistencies arise among religious areas. These inconsistencies reduce the project areas within the structures and cause loss of space. To address these inconsistencies, plan revisions are required. However, plan revisions extend the construction periods of projects and increase the projected costs. Adding the Qibla direction as a legend to large-scale maps (LSMs) used as base maps in the drawing of urban plans is an option that can be used to eliminate these inconsistencies. In this study, the Qibla direction for all LSMs in Türkiye's national mapping was calculated with geodetic accuracy to eliminate the mentioned inconsistencies. These calculations and the generated visual outputs are presented to users through the Map Qibla Direction Calculation Interface (MQDCI) developed in the MATLAB environment. When any coordinate data or the name of the relevant LSM is entered as input into the developed interface, the Qibla direction value for that map is provided to the user in this study. The developed interface allows the Qibla direction angle to be calculated and presented to the user with geodetic accuracy and instantly, without the need for measurements and calculations performed in the field. Although the developed interface is designed according to the Kaaba, which is the Qibla for Muslims, and Türkiye's geographical boundaries, it is also suitable for other religions in Türkiye or different religions in other countries. For this, it is sufficient to know the national mapping systems of the countries and the geographical coordinates of the Qibla in Christianity and Judaism

Inclined Aerial Image and Satellite Image Matching Based on Edge Curve Direction Angle Features

Optical remote sensing images are easily affected by atmospheric absorption and scattering, and the low contrast and low signal-to-noise ratio (SNR) of aerial images as well as the different sensors of aerial and satellite images bring a great challenge to image matching. A tilted aerial image and satellite image matching algorithm based on edge curve direction angle features (ECDAF) is proposed, which accomplishes image matching by extracting the edge features of the images and establishing the curve direction angle feature descriptors. First, tilt and resolution transforms are performed on the satellite image, and edge detection and contour extraction are performed on the aerial image and transformed satellite image to make preparations for image matching. Then, corner points are detected and feature descriptors are constructed based on the edge curve direction angle. Finally, the integrated matching similarity is computed to realize aerial–satellite image matching. Experiments run on a variety of remote sensing datasets including forests, hills, farmland, and lake scenes demonstrate that the effectiveness of the proposed algorithm shows a great improvement over existing state-of-the-art algorithms.

Study of the motion and interaction of micro-swimmers with different scales in Poiseuille flow

We conducted numerical simulations using the immersed boundary–lattice Boltzmann method to investigate the motion and interaction of microswimmers of different scales in Poiseuille flow. The squirmers self-propelling via generating surface waves were used as the model for microswimmers. The movement of two squirmers with different scale ratios (0.6–1.5), swimming Reynolds numbers (0.1–2.0), swimming strength (1–7), and blockage ratios (0.125–0.25) in Poiseuille flow was studied. Five classical motion patterns were identified: periodic tumbling, steady motion, periodic oscillation, damped oscillation, and chaotic motion modes. Initially, we examined the interaction between a pair of squirmers of the same scale and elucidated the causes of their different motion pattern transitions using the pressure distribution, direction angle, and swimming velocity of the squirmers. We investigated the variation of transport velocity with blockage ratio and swimming strength. A pair of squirmers with small ratios tended to migrate in a stable motion pattern, while those with large ratios showed a high tendency to change their motion patterns. Pushers with an increasing swimming Reynolds number were adsorbed to the wall and migrated stably along the wall.

Dynamics of zinc dendritic growth in aqueous zinc-based flow batteries: Insights from phase field-Lattice-Boltzmann simulations

This paper employs a phase-field-Lattice-Boltzmann method incorporating ion transport mechanisms in the electrolyte, including diffusion, electromigration and convection, to investigate the growth of Zn dendrite in aqueous zinc-based flow batteries. It was found that during electrodeposition, Zn2+ ions enrich in front of the dendrite tip to form a boundary layer of Zn2+ ion concentration due to diffusion and electromigration under the static state u=0.0m/s, resulting in the so called “tip effect”. Predicted results show that both the exchange current density and the diffusion coefficient have similar effect to the deposited dendritic growth dynamics according to the Damkohler number. It can be found that the growth pattern of deposited zinc dendrites is significantly influenced by the existing electrolyte forced flow. Predicted results show that the increase in flow rate results in the advective transport of Zn2+ ions in the electrolyte, which consequently leads to a reduction in the actual growth direction angle. This facilitates the formation of a dendrite-free deposition pattern and improves the performance and stability of the battery. Moreover, the competitive growth of polycrystalline grains during electrodeposition was investigated under the static state and the flowing state. Results show that the unfavorably orientated dendrites always lie behind the favorably orientated ones during electrodeposition.

Analysis of Acoustic Surface Wave Focused Unidirectional Interdigital Transducers Using Coupling-of-Mode Theory.

In cell or droplet separation, high acoustic wave energy of a surface acoustic wave (SAW) device is required to generate sufficient acoustic radiation force. In this paper, the electrode width-control floating electrode focused unidirectional interdigital transducer (EWC-FEFUDT) is proposed due to its enhanced focusing properties. The performance of the EWC-FEFUDT is investigated using the Coupling-of-Mode (COM) theory, and the COM parameter is extracted using the Finite Element Method (FEM). The four different forbidden band edge frequencies account for the unidirectionality of the proposed EWC-FEFUDT. A direction angle of ϕκ-ϕζ=44.5° of the EWC-FEFUDT (Design 3) is obtained, being fairly close to the optimum value of 45°. The EWC-FEFUDT (Design 3) has a lower insertion loss (IL) of -5.1 dB and greater unidirectionality (20 × log10(D) = 13.8 dB). The SAW maximum amplitude of the EWC-FEFUDT (Design 3) is increased by about 1.5×10-4 µm compared to that of the focused interdigital transducers (FIDTs). The maximum acoustic pressure of the EWC-FEFUDT is an order of magnitude higher than that of FIDTs. The EWC-FEFUDT exhibits enhanced focusing properties. The proposed EWC-FEFUDT may provide an alternative method for cell or droplet separation in an efficient manner.

Effects of functional type and angular configuration on reflectance anisotropy of aquatic vegetation in ultra-high resolution hyperspectral imagery

ABSTRACT Imaging spectroscopy and lightweight unmanned aerial vehicles (UAVs) have revolutionized remote sensing of vegetation, by providing high spectral and spatial resolution data. Comprehensive wetland monitoring should be based on reliable mapping of biophysical aquatic vegetation parameters, which in turn requires low bias in measured spectra, e.g. minimization of reflectance anisotropy. This study aims to quantitatively investigate how sensor scan direction and solar zenith angle (SZA) affect vegetation spectra over two dominant aquatic plants, Phragmites australis and Nuphar lutea, representing different functional types (i.e. emergent and floating) with divergent canopy structure and affinity with water, using data collected with a hyperspectral (400–1000 nm range) push-broom sensor mounted on a UAV. Anisotropy factor (ANIF), mean reflectance scatterplots and regression analysis were used for assessing the magnitude of spectral anisotropy at both pseudo-leaf and canopy scales. Our findings showed more accentuated anisotropic behaviour in the visible than near-infrared domain at SZA < 60° as the scan direction approaches that of solar principal plane. The increase in reflectance in near-forward direction affects the spectra of floating-leaved N. lutea at both leaf and canopy scales, suggesting the presence of water (as a film over leaves or as canopy background) as a likely anisotropy driver. Backward hotspot is evident in canopy spectra of emergent P. australis, with driving mechanisms similar to terrestrial species (i.e. shadow-hiding). At SZA > 60°, reflectance anisotropy appears to be negligible, independent of functional type and scan direction. This research underscores the importance of considering sun-target-sensor geometry in remote sensing studies on aquatic vegetation.

Comparison of fatigue lifetime of new generation CAD/CAM crown materials on zirconia and titanium abutments in implant-supported crowns: a 3D finite element analysis.

Due to the dynamic character of the stomatognathic system, fatigue life experiments simulating the cyclic loading experienced by implant-supported restorations are critical consideration. The aim of this study was to examine the effect of different crown and abutment materials on fatigue failure of single implant-supported crowns. Models were created for 10 different designs of implant-supported single crowns including two zirconia-reinforced lithium silicates (crystallized and precrystallized), monolithic lithium disilicate, polymer-infiltrated ceramic networks, and polyetheretherketone supported by zirconia and titanium abutments. A cyclic load of 179 N with a frequency of 1 Hz was applied on palatal cusp of a maxillary first premolar at a 30° angle in a buccolingual direction. In the models with titanium abutments, the polymer-infiltrated ceramic network model had a lower number of cycles to fatigue failure values in the implant (5.07), abutment (2.30), and screw (1.07) compared to others. In the models with zirconia abutments, the crystallized zirconia-reinforced lithium silicate model had a higher number of cycles to fatigue failure values in the abutment (8.52) compared to others. Depending on the fatigue criteria, polyetheretherketone implant crown could fail in less than five year while the other implant crowns exhibits an infinite life on all models. The type of abutment material had an effect on the number of cycles to fatigue failure values for implants, abutments, and screws, but had no effect on crown materials. The zirconia abutment proved longer fatigue lifetime, and should thus be considered for implant-supported single crowns.

Influence of SV Wave Oblique Incidence on the Dynamic Response of Arch Dams Under Canyon Contraction

Current dynamic response analyses of arch dams under an oblique incidence of seismic waves have overlooked the effects of canyon contraction deformation. This study investigated the influence of the incident direction and incident angle of seismic waves on the comprehensive displacements, as well as the damage, of arch dams under canyon contraction conditions. When SV waves are incident obliquely along the river direction, the peak displacements of the dam crest and arch crown beam increase with increasing canyon contraction. The displacement of the dam reaches its maximum when the incident angle is 0°, indicating that the SV wave vertical incidence is the most unfavourable incidence mode affecting the displacement. Dam damage cracking is most severe in the case of a canyon contraction of 60 mm and an incidence angle of 0°. The dam damage cracking index in this case increases only by 7.6% compared to a canyon contraction of 0 mm and an angle of incidence of 0°. However, the change in canyon contraction when a seismic wave is incident obliquely can cause serious damage cracking to the dam. When the SV wave is incident obliquely along the cross-river direction, the dam damage cracking index in this case increases by 110% compared to the case where the canyon contraction is 0 mm, and the incidence angle is 0°. Therefore, it is necessary to comprehensively consider the influences of canyon contraction and the oblique incidence of seismic waves in the seismic design and safety review of arch dams.

The Structural Design and Analysis of the Multi Nozzle Relay Air-Jet Inserting System by Profile Reed Guiding for 3D Weaving Machine

Introduction: Based on the literature, this article designs a parameterized simulation model of a multi-layer jet weft insertion system by profiles reed guidance for a 3D loom on the PTC Creo9.0 platform, including the main supersonic nozzle, supersonic auxiliary nozzle (relay nozzle), and multi-slot profiles reed components. Method: Based on the existing basic theory, experimental results, and empirical data of turbulent jet, the parameters of the multi-layer jet weft insertion system, as well as the structural parameters and the relative positions of the main, auxiliary nozzle and profile reed components, such as the center distance of each layer's main nozzle, auxiliary nozzle spacing, auxiliary nozzle installation angle, spray direction angle, and spray angle, have been determined preliminarily. Result: Further, the basic flow field parameters, such as the supply pressure of the main and auxiliary nozzles and the shape of multi-layer profile reeds, have been determined optimally on the Virtual Prototype Collaborative Simulation Platform (PTC Creo9.0/ANSYS Workbench/Fluent 2024R1), and the rationality of the structural design also been verified; on the premise of ensuring that the airflow velocity of each layer's profiles groove meets the requirements of weft insertion, the design and simulation calculation is repeatedly modified, and the optimal structural design parameters of the multi-layer weft insertion system and nozzle is finally determined. Conclusion: To explore the feasibility of multi-layer jet weft insertion, the design of threedimensional multi-layer jet weft insertion looms has laid a theoretical foundation, laying a good foundation for the emergence and industrial manufacturing of three-dimensional multi-layer jet weft insertion looms, and providing an important reference for the innovative design of threedimensional multi-layer water jet weft insertion looms.

Evaluation and correction methods for geometric errors of hydrostatic thrust bearings

The value and direction angle of the perpendicularity error of the thrust surface and bearing bush in hydrostatic thrust bearings directly affect the motion accuracy. In this paper, a rapid onsite measurement method and evaluation model for the value and direction angle of the perpendicularity error of the thrust surface and bearing bush in hydrostatic thrust bearings are presented. The method is validated by comparing experimental measurements with those obtained using a CMM. An analysis of the perpendicularity errors before and after correction shows that at different speeds (10 rpm, 30 rpm, and 50 rpm), the errors in the mean axial and tilt displacements of the thrust bearing are reduced by 68.41% and 35.44%, respectively.

Research on damage assessment and visualization technology of anti-ship missiles on typical ships

Abstract To improve the damage assessment efficiency of anti-ship weapons, the target vulnerability model of typical ships is introduced, and the damage level is classified into severe and moderate damage according to the functional characteristics of the ships. The damage probability calculation model of typical ships is constructed, and the damage assessment system of anti-ship missiles on typical ships is built based on the Unity3D engine. The system can achieve the parameter input of the anti-ship missile, the calculation of the damage probability of the anti-ship missile on typical ships, and the visualization of the damaging effect. For an example of an anti-ship missile analysis, the system visualizes the damage effect of the anti-ship missile on a typical ship, sets the combat tribal speed to 1, 450 m/s and CEP to 10 m, and calculates the damage probability of the anti-ship missile on a typical ship at three different aiming points under the conditions of the bullet-eye meeting with the direction angle of the scattering of fragments of 90° and the angle of fall of 20°. The results show that aiming point 2 has the highest probability of destroying the ship. The designed system is functionally complete and can provide support for the damage assessment of typical ships by anti-ship missiles, and the idea of system development can provide a reference for the design of damage assessment software.

Considering the Bottom Edge Cutting Effect of the Carbon Fiber Reinforced Polymer Milling Force Prediction Model and Optimization of Machining Parameters.

The milling force plays a pivotal role in CFRP milling. Modeling of the milling force is helpful to explore the changing law, optimize the processing parameters, and then reduce the appearance of defects. However, most of the existing models ignore the effect of the bottom edge. In this paper, the prediction of milling force in CFRP milling processes is taken as the research object. By analyzing the milling mechanism and considering the end milling cutter's bottom cutting edge, the prediction model of milling force was established. Based on the experimental data and simulation data of milling force, the milling force coefficient was obtained by inverse calculation. Subsequently, the predicted cutting force was compared with the experimental cutting force, showing a maximum error of 14.5%, which is within a reasonable range, and the correctness of the model was verified. Furthermore, combined with the delamination damage and the milling force prediction model, a multi-objective optimization model of milling parameters was established, and the genetic algorithm was used to solve the model. The unidirectional carbon fiber plate with a fiber direction angle of 45° was selected as the optimization example. The minimum delamination damage was obtained under the cutting conditions of a spindle speed of 4903.1569 r/min, feed rate per tooth of 0.01 mm/z, and an axial depth of cut of 0.5 mm, and the experimental verification was carried out. The feasibility of the genetic algorithm in CFRP milling parameter optimization modeling was also verified.

Implicit motor adaptation patterns in a redundant motor task manipulating a stick with both hands.

The remarkable ability of the motor system to adapt to novel environments has traditionally been investigated using kinematically non-redundant tasks, such as planar reaching movements. This limitation prevents the study of how the motor system achieves adaptation by altering the movement patterns of our redundant body. To address this issue, we developed a redundant motor task in which participants reached for targets with the tip of a virtual stick held with both hands. Despite the redundancy of the task, participants consistently employed a stereotypical strategy of flexibly changing the tilt angle of the stick depending on the direction of tip movement. Thus, this baseline relationship between tip-movement direction and stick-tilt angle constrained both the physical and visual movement patterns of the redundant system. Our task allowed us to systematically investigate how the motor system implicitly changed both the tip-movement direction and the stick-tilt angle in response to imposed visual perturbations. Both types of perturbations, whether directly affecting the task (tip-movement direction) or not (stick-tilt angle around the tip), drove adaptation, and the patterns of implicit adaptation were guided by the baseline relationship. Consequently, tip-movement adaptation was associated with changes in stick-tilt angle, and intriguingly, even seemingly ignorable stick-tilt perturbations significantly influenced tip-movement adaptation, leading to tip-movement direction errors. These findings provide a new understanding that the baseline relationship plays a crucial role not only in how the motor system controls movement of the redundant system, but also in how it implicitly adapts to modify movement patterns.

Implicit motor adaptation patterns in a redundant motor task manipulating a stick with both hands

The remarkable ability of the motor system to adapt to novel environments has traditionally been investigated using kinematically non-redundant tasks, such as planar reaching movements. This limitation prevents the study of how the motor system achieves adaptation by altering the movement patterns of our redundant body. To address this issue, we developed a redundant motor task in which participants reached for targets with the tip of a virtual stick held with both hands. Despite the redundancy of the task, participants consistently employed a stereotypical strategy of flexibly changing the tilt angle of the stick depending on the direction of tip movement. Thus, this baseline relationship between tip-movement direction and stick-tilt angle constrained both the physical and visual movement patterns of the redundant system. Our task allowed us to systematically investigate how the motor system implicitly changed both the tip-movement direction and the stick-tilt angle in response to imposed visual perturbations. Both types of perturbations, whether directly affecting the task (tip-movement direction) or not (stick-tilt angle around the tip), drove adaptation, and the patterns of implicit adaptation were guided by the baseline relationship. Consequently, tip-movement adaptation was associated with changes in stick-tilt angle, and intriguingly, even seemingly ignorable stick-tilt perturbations significantly influenced tip-movement adaptation, leading to tip-movement direction errors. These findings provide a new understanding that the baseline relationship plays a crucial role not only in how the motor system controls movement of the redundant system, but also in how it implicitly adapts to modify movement patterns.

Effect of resultant force direction in single point diamond turning of (111)CaF2

On-axis single point diamond turning experiments were performed on (111)CaF2 to investigate the effect of the resulting force system on the single crystal response. The cutting and thrust forces were measured and the resulting surface topography was characterized. The Schmid factors and fracture factors were calculated, and their ratio SfFf*was determined as a function of cutting direction and resultant force angle. It was found that this approach can be used to predict the number and location of resulting fracture lobes on the surface with respect to the lattice orientation. Two regimes with different topography were predicted when turning (111)CaF2, depending on the resultant force angle.

Numerical assessment of incoming atmospheric boundary layer effects generated by various approaches on ship airwake turbulence characteristics

The unsteady and extensively separated turbulent airwake flows around a ship’s deck significantly impact helicopter pilot performance during shipboard operations. Hence, incorporating realistic, unsteady incoming mainstream conditions such as the atmospheric boundary layer (ABL), is crucial in numerical simulations of the ship airwake. This study employed delayed detached eddy simulations (DDES) to evaluate the effect of steady and unsteady ABL modeling methods on the turbulent flow characteristics of the ship airwake. A 1:12.5 scaled Simple Frigate Shape 1 (SFS1) ship model was utilized in the numerical simulations, and three distinct ABL profiles (one steady and two unsteady) were simulated at two different wind direction angles (HW and RW30). Synthetic and turbulator modeling methods were utilized to generate the unsteady ABL profiles. Time-averaged and instantaneous flow fields calculated by various ABL profiles were compared with experimental data at multiple points within the ship airwake. The numerical findings indicated that while the time-averaged data remained unaffected by the ABL profile presence, the instantaneous flow quantities experienced significant alterations, especially under the red wind condition. The introduction of an unsteady ABL profile was shown to augment the unsteadiness and fluctuation of the flow field within the ship airwake compared to the steady ABL scenario. Cross-correlation analyses between the velocity fields computed using steady and unsteady ABL profiles unveiled distinct patterns and behaviors of flow structures over the deck. Moreover, evaluation of the velocity and pressure fields of unsteady ABL across time/space domains revealed incremented turbulence and disturbances over the flight deck, intensifying with wind direction angle. The synthetic ABL modeling approach was found to deliver promising outcomes in comparison to the turbulator method, while requiring significantly lower computational resources.

Stress distribution of customized abutment material and angles in dental implant systems: A finite element analysis

Aim: Dental implants and abutments are often made from titanium for its biocompatibility and excellent material properties. However, in patients with thin gingival biotypes, titanium abutment margins may be visible and aesthetically unpleasing. This study aims to use finite element analysis to evaluate stress distribution in implant components, restoration materials, and biological tissues for implants placed at different angles using various customized abutment materials. Methodology: 3D models of a three-member implant-supported fixed prosthesis were created using SolidWorks, with implants placed at positions 44 (4I) and 46 (6I). These models were imported into EXOCAD to design prosthetic restorations on custom abutments at three angles: straight (KD0), 10 degrees (KD10), and 20 degrees (KD20). Abutments were made from alumina (AL), titanium (TI), and zirconia (ZI). A 150N load was applied to the occlusal table at a 30° angle in the buccolingual direction. Stress distribution was measured as von Mises Stress values (vMS). Results: For implants, the lowest vMS value was observed in the KD0-AL group (4I: 9.984 MPa, 6I: 22.91 MPa), while the highest vMS value was found in the KD20-TI group (4I: 25.30 MPa, 6I: 42.03 MPa). Custom abutment and custom abutment screws (in general) showed higher vMS values in AL material and lower vMS values in TI material. In contrast, for cortical bone and restoration material, higher vMS values were observed in the TI material and lower vMS values in the AL material. Conclusion: Dental implants require effective stress distribution from occlusal loads to ensure long-term success. Excessive stress on the abutment and abutment screw can compromise the prosthetic outcome. Therefore, titanium (TI) abutments are preferred in the posterior region for their durability, despite being less aesthetically pleasing. Additionally, a higher implant angle reduces strength, negatively impacting the implant's performance.

Power performance optimization of twin vertical axis wind turbine for farm applications

Twin Vertical Axis Wind Turbines (VAWTs) appear to be the potential candidates for enhancing the power density of wind farms. Earlier twin-VAWT studies were mainly focused on carrying out the parametric study of one or two twin-VAWT variables together while treating the other variables as fixed. Since twin-VAWT variables strongly influence each other, therefore, this approach led to reporting conflicting optimal combinations of twin-VAWT variables for optimizing its power performance. Furthermore, previous studies considered higher rotor solidities, which is not desirable from a power generation perspective and it also reduces turbine lifespan. Using L16 (45) Taguchi orthogonal array along with a modified superposition model, this research optimized the power performance of twin-VAWT considering together, solidity ratio (σ), pitch angle (β), wind direction angle (δ), turbine spacing ratio (S/D) and rotational direction (φ) of the rotor as design variables. Unsteady CFD was employed to ascertain the power performance of orthogonal array designs followed by the orthogonal analysis for the optimum tip-speed ratios (TSRs) and power coefficients. Based upon the relative impact of the design variables on the mean optimum TSR, the variables were ranked as: (σ) > (δ) > (φ) > (β) and (S/D). On the other hand, a different trend for the relative impact of the design variables on the power performance was found: (β) > (δ) > (σ) > (φ) > (S/D). The orthogonal analysis optimum twin-VAWT configuration showed a positive synergistic interaction at TSRs > 2.5 and negative synergistic interaction at TSRs ≤ 2.5 in comparison to its standalone counterpart. Moreover, the orthogonal analysis’s optimum twin-VAWT underperformed by 4.7 % when compared with the best orthogonal array design at their respective optimum TSRs, indicating a sub-optimal design resulting from Taguchi orthogonal analysis. The incapability of orthogonal analysis to include the interaction effects among variables resulted in the sub-optimal twin-VAWT design. Linear graph method highlighted the presence of strong interaction effects among the design variables. For five design variables with four levels each (45), a full factorial Design of Experiments (DoE) of 1024 cases was constructed to include the interaction effects. Signal-to-noise ratios of full factorial DoE cases were predicted by the modified superposition model. The highest predicted signal-to-noise ratio among 1024 cases identified the best orthogonal array design as the actual optimum twin-VAWT configuration. The increase in power efficiency of twin-VAWT in comparison to its standalone counterpart was observed as the TSR was increased with the maximum power enhancement by 23 % at TSR 4.25. Furthermore, the optimal twin-VAWT configuration exhibited an optimal TSR of 3.5, contrasting with the standalone VAWT's optimal TSR of 3.0. This shift extended the power performance envelope of the optimum twin-VAWT, allowing for energy extraction across a broader range of TSR values. The undertaken study highlights the prospects of twin-VAWTs for increasing the farm power density.

Direct Normal Irradiance Prediction-Based Optimum Interval Tilt Angles for Enhancement of Energy Output, Levelized Cost of Energy, and CO2 Emission in a Grid-Connected Photovoltaic System

Abstract The tilt angle of photovoltaic (PV) panels is a crucial determinant of their performance and can be adjusted using different tracking methods. Periodically changing the tilt angle strikes a practical balance between efficiency and cost. This work introduces a bi-directional long short-term memory (Bi-LSTM)-based direct normal irradiance (DNI) prediction to estimate the time intervals for the tilt angle adjustments. DNI prediction involves 22-year (2000–2022) historical time series data and the Bi-LSTM deep learning model to predict DNI at different time frames for the location Madurai, India. Using the predicted DNI, tilt angle-based DNI is mapped using the tilt angle correlation through a nearest neighborhood interpolation method. DNI potential over a specific period is utilized to find the optimum time intervals for the tilt angle adjustments. The simulation study of this work is implemented with a 5 kW grid-connected solar PV system using pvsyst software. The effectiveness of the proposed methodology is evaluated based on the improvements in power output, levelized cost of energy (LCOE), and carbon emission reductions and compared with other existing methods. The results showed that using the proposed optimal tilt angle intervals led to a 10.31% increase in PV output power, the lowest LCOE at 3.61 c/kW h, and 8.363 tCO2/year carbon emissions.