Title Angle Research Articles

Experimental study and new-proposed characterization of burning rate and flame geometry of gasoline pool fires with different aspect ratios

This study investigated the burning rate and the flame geometry of gasoline pool fires under crosswinds in the context of bridge vehicle fires. A 1:4 scale bridge fire platform was established. A total of 45 fire experiments were conducted on 9 gasoline pool with 1–2.2 aspect ratios under 0–2 m/s cross-wind. The influence mechanism of aspect ratio n on the characteristic parameters of pool fires was investigated. The results showed that the burning rate of gasoline pool ranges from 0.028 kg‧m−2‧s−1 to 0.064 kg‧m−2‧s−1, which increases with wind speed and pool size. When the wind speed exceeds 1 m/s, the title angle of the flame on the windward side is greater than 45° and is less affected by pool size. The wall heat conduction at wind downstream increases with aspect ratio when placing the longer side facing to cross flow. The correction factor Fr·n can be used to describe the competition between the air entrainment and the buoyancy in gasoline pool fire. A general model based on aspect ratio is proposed to quantify the burning rate and flame tilt characteristics of gasoline fires. The reliability and applicability of the model are compared with the existing experimental data.

Derotational distal femur osteotomy with medial patellofemoral ligament reconstruction can get good outcomes in the treatment of recurrent patellar dislocation with excessive TT-TG and increased femoral anteversion.

Surgery is the main treatment for recurrent patellar dislocation (PD). However, due to the complexity of anatomical factors, there is still a lack of consensus on the choice of combined surgical methods. This study aimed to compare the clinical and radiological outcomes of medial patellofemoral ligament reconstruction combined with derotational distal femur osteotomies (MPFLR + DDFO) and combined with tibial tubercle osteotomies (MPFLR + TTO) for recurrent PD with increased femoral anteversion angles (FAA) and excessive tibial tubercle-trochlear groove (TT-TG) distance. In this retrospective analysis, MPFLR + DDFO and MPFLR + TTO patients from 2015 to 2020 were included. Group A (MPFLR + DDFO, n = 42) and B (MPFLR + TTO, n = 46) were formed. Clinical outcomes included physical examinations, functional outcomes (Kujala, Lysholm, International Knee Documentation Committee (IKDC), visual analog scale (VAS) and intermittent and persistent osteoarthritis pain scale (ICOAP), Tegner scores), and complications. The Caton-Deschamps index (CD-I), patellar title angle, patellar congruence angle, patella-trochlear groove distance, TT-TG distance, and FAA were used to assess radiological outcomes. All clinical outcomes improved significantly in both groups, but Group A had significantly better postoperative scores than Group B (Kujala: 89.8 ± 6.4 vs. 82.9 ± 7.4, P < 0.01; Lysholm: 90.9 ± 5.1 vs. 81.3 ± 6.3, P = 0.02; IKDC: 87.3 ± 9.0 vs. 82.7 ± 8.0, P < 0.01; Tegner: 6.0 (5.0, 9.0) vs. 5.0 (4.0, 8.0), P = 0.01). However, there was no significant difference in the VAS and ICOAP scores between the two groups. No dislocation recurrences occurred. Radiological outcomes improved significantly in both groups, but Group A had better outcomes. After surgery, the patellar height of 88.5% (23/26) patients in Group A and 82.8% (24/29) patients in Group B was restored to normal (the Caton-Deschamps index <1.2). Both MPFLR + TTO and MPFLR + DDFO obtained satisfactory clinical and radiological outcomes in the treatment of recurrent PD with increased FAA and excessive TT-TG. However, the outcomes of MPFLR + DDFO were better and should be considered a priority. MPFLR + TTO may be not necessary for such patients.

Investigating the Optimum Tilt Angle of PV Modules in Al-Sherouk City, Cairo

Energy is a crucial element that can ensure the quality of life for citizens. The consumption of energy by citizens is increasing rapidly, and future existence also became reliant on the sufficient availability of energy and its sources. Nevertheless, energy consumption is becoming a major concern due to the increase in usage rates and the lack of sufficient renewable sources of energy. Nowadays, the technological advancement that lies in the use of Photovoltaic Panels can help in generating energy and take the advantage of the sun especially in Egypt. The usage of PV’s relies on multiple factors that can ensure the highest potential generation of energy. Therefore, several studies investigated these factors including the optimum titling angle that can be different according to the location and orientation of the panel. Modifying the titling angle can play a significant role in generating high rates of power depending on the measurements and calculations. The aim of this paper was to investigate the efficient titling angle that can be used for PV panels that are installed in Al-Sherouk City in Egypt. The methodology involved the implementation of an experimental investigation that is based on position 2 similar PV panels to estimate the power generation over a period of 2 days from 9 am to 4 pm. The findings have shown that the theoretical and experimental results were similar, and the optimum tilting angle was determined to range between 54.7 degrees and 8.16 degrees. The study demonstrated the differences between an adjusted and a fixed angle, and the variable titled angle can generate more energy than the fixed one. This paper contributes to the body of knowledge by presenting the significance of a variable tilting angle to generate more power than relying on a fixed angle as demonstrated by many previous studies.

Electromechanical analysis of a self-sensing torsional micro-actuator based on CNTs reinforced piezoelectric composite with damage

Electromechanical microstructures are increasingly attractive for various applications of smart devices. However, electrostatic actuator is sensitive to pull-in instability caused by microscopic dispersion forces, taking risks of stiction, adhesion, and even failure. Making micro-actuators self-sensing is a promising strategy for active modulation of device design. Although some progress has been made for respective sensing and actuating, it is still challenging to build integrating sensing-actuating device. In this work, we proposed one self-sensing actuating composite structure for constructing an electrostatic torsional actuator. We modelled composite nanobeams capable of self-adjusting pull-in titling angle of micro-actuator based on strain gradient theory with size dependency and damage. Theoretical and numerical results showed good agreements and verified the accuracy of proposed model in this paper. The variation of CNTs volume fraction can tune torsional stiffness of torsional nanobeam, and thus increase the stable working range of micromirror. By introducing piezoelectric layers into laminated torsional structures, the working state and the damage of device can be sensed and driven by piezoelectric effect, and the stability can be adjusted and predicted to avoid pull-in instability. This work can contribute to structural optimization of electromechanical devices.

Dust accumulation on solar photovoltaic panels: An investigation study on power loss and efficiency reduction

This study mainly focuses on understanding the properties of dust particle deposition (cement, brick powder, white cement, fly ash, and coal) on a solar PV panel under dry conditions in an indoor environment to record the percentage efficiency reduction profile. For the experimental study, a solar PV panel is manually drifted at three different tilted angles (0?, 15?, and 30?) with respect to five different dust samples taken to replicate dry conditions. To maintain optimal power storage by ensuring maximum ray reflection as the angle of inclination of the solar PV panel changes. It entails long-term postoperative improvement of the solar PV module by increasing feasibility and meeting user needs. From the experiment result, it is observed that percent of power loss of each dust particle is measured accurately such as cement (0.067), brick (0.190), white cement (0.163), fly ash (0.164), and coal (0.177), consolidated for three different tilt angles. Similarly, percent of power efficiency of each dust particle is measured accurately for three different tilt angles such as cement (76.689%), brick (61.822%), white cement (52.792%), fly ash (59.859%), and coal (75.381%), respectively.

A liquid medium annealing strategy for highly [041]/[141]-oriented planar antimony sulfide solar cells with 7.23% efficiency

Antimony sulfide (Sb2S3) is regarded as one of candidate materials for tandem top cells with silicon based solar cells due to its non-toxicity, appropriate bandgap, high absorption coefficient and good stability. However, restricted by the difficulty of carrier transportation caused by unfavorable orientations of Sb2S3, the power conversion efficiency (PCE) is still relatively low. In this work, a new annealing method, called liquid medium annealing (LMA), is developed to versatilely regulate the orientation of Sb2S3 films by controlling the concentration of Se22--OAm. Compared with conventional vapor-assisted annealing, a highly [041]/[141] oriented Sb2S3 film with unique title angles can be skillfully prepared by LMA with top-down model, which facilitates the photo-induced carrier separation along (Sb4S6)n ribbon. Meanwhile, such a LMA tactic can effectively tailor the band alignment at back contact by raises the valence band maximum (VBM) of Sb2S3, and then reducing hole collection barrier. Finally, a high PCE of 7.23% is achieved and considered the first echelon in planar Sb2S3 solar cells.

FARKLI EĞİM AÇILARINDA GÜNEŞ KOLLEKTÖRLERİNİN ENERJİ VE EKSERJİ ANALİZİ: ERZİNCAN İLİ ÖRNEĞİ

Güneş kollektörleri kullanım suyu ısıtma uygulamalarında sıklıkla kullanılmaktadır. Tasarım aşamasında güneş kollektörlerinin en uygun eğim açısında konumlandırılması güneş enerjisinden verimli faydalanılması için önemlidir. Bu çalışmada, Erzincan ilinde konumlandırılan bir güneş kollektörünün eğim açısının aylık/günlük ortalama ışınım değerlerine, su çıkış sıcaklığına, enerji ve ekserji verimlerine etkisi teorik olarak incelenmiştir. Optimum güneş kollektörü eğim açısının en yüksek ve en düşük değerlerinin Aralık ve Haziran aylarında sırasıyla 63° ve 0° olduğu görülmüştür. Erzincan için önerilen (27.14°) ve hesaplanan eğim açıları için günlük ortalama saatlik ışınım değerleri karşılaştırılmış olup en büyük değişimin Ocak ayında %26 olduğu görülmüştür. Buna ek olarak, güneş kollektörünün enerji ve ekserji verimleri hesaplanmış olup optimum eğim açıları için en yüksek verimleri sırasıyla %74.2 ve %9.7 olarak belirlenmiştir.

Optimum Solar Panel Orientation and Performance: A Climatic Data-Driven Metaheuristic Approach

This study presents an optimization platform based on the climatic data provided by the National Renewable Energy Laboratory (NREL) to determine the optimum solar panel orientation. Our optimization model is simpler to use than the clearness index model since there is no need to calculate the extraterrestrial insolation on a horizontal flat plate and the shape factor. This optimization approach is based on the hourly climatic data. It determines the optimum tilt angle and azimuth angle of a solar panel for the maximum power generation, considering the diurnal variation of climatic conditions. The hourly evaluation of insolation allows setting up a solar panel azimuth angle that responds to the peak power demand. The main data that impacts the solar panel performance consists of the solar direct normal incident (DNI), direct horizontal incident (DHI), global horizontal incident (GHI), ambient temperature, wind speed, and ground albedo, all of which were obtained from the NREL database for over twenty years. The accuracy of the optimization platform introduced in this study is scrutinized by investigating the three locations in the United States with different climatic conditions. The results based on the present optimization model show higher PV power than the general rule of thumb for south-facing panels with title angles the same as the latitude of the location. Moreover, the effect of deviations from optimum panel orientation is discussed to show the versatility of our technique. Our optimization model is easy-to-use, computationally efficient, and capable of being applied to other locations worldwide.

Test-Retests Reliability of Digital Photography in Measuring Quadriceps-Angle and Pelvic Tilt Angle in Healthy Population

Aim: Capturing body images through digital photography method for calculation of quadriceps angles and pelvic position in clinical assessment is an inexpensive method. The aim of this study is to evaluate the reliability of measuring Q-angle and pelvic tilt angle with digital camera and Microdicom software. Place and duration: University of Lahore and Tehran University of medical sciences, from June 2020 to June 2021 Methods: Bilateral lower limbs of fifteen healthy asymptomatic subjects were considered for calculations of desired angles. A 13-megapixel camera was used to capture images of quadriceps angle (q-angle) measurement in an anterior view and for pelvic angle measurement image in lateral view along with specific landmark markers on the body were captured. Images were transferred to Microdicom software for calculating desire angles. Three trails of procedures and Intra-class Correlation Coefficient (ICC) with 95% Confidence Interval (CI), Munro’s classification for reliability coefficients were used for the description of degrees. Standard error of measurement (SEM) was also calculated. Results: The Intra-class correlation coefficient values for right side Q- angle was 0.949(0.878-.981) and for left side it was 0.924(0.819-0.972) and &lt;0.005 significant p-value. The ICC results for measuring pelvic title angle in the right side .990 (.975-.996) and left legs were .991 (.974-.997). Showing that the results were highly reliable and significant (p&lt;0.005). Conclusions: The q-angle and pelvic angle measured with digital image have excellent consistency and reliability. Keywords: angle, asymptomatic, Images, pelvic, quadriceps

OPTIMIZATION OF DISSIMILAR FRICTION STIR WELDED ALUMINUM PATES (2024 T3 AND 7075T6) BY USING DIFFERENT METHODS

Friction stir welding (FSW) has many advantages when compared with another fusion welding. The experimental analysis and optimization of friction stir welding (FSW) were done to obtain desired mechanical properties of dissimilar aluminum welded plates (2024T3 and 7075T6). The friction stir welding process was done on aluminum plates (2024T3 and 7075T6) for different three rotating speeds (710, 1120 and 1800), three welding speeds (25, 50 and 77), three different steel tools (Square, cylindrical and Hexagonal) and 2° title angle. The different tests of welding were done according to the orthogonal matrix of experimental design analysis, then a tensile test was done to calculate the ultimate stress to get the welding efficiency. The optimum welding environment led to the maximum efficiency was obtained by these methods (Taguchi, Particle Swarm Optimization and new modified Particle Swarm Optimization). Particle swarm optimization (and its new modification) used an artificial neural network to find the relation between the input and output parameters. The results showed that when the rotating speed is increased and welding speed is decreased (but this conclusion depends on tool shape) the welding efficiency is increased. The present study showed that the modified PSO is the best method to find the optimum welding environment as compared with experimental results

Evaluating the fish aggregation effect of wind turbine facilities by using scientific echo sounder in Nanlong wind farm area, western Taiwan

During the stages of construction and operation of the wind power facilities, fishery and fishery resources in the wind farm areas will certainly be changed greatly. One of the major concern is the aggregation effect of wind turbines facility. We use scientific echo sounder together with scuba diving to survey fish aggregations in the wind farm areas. In order to obtain echoes very near the facility, we use tilt beam angle instead of traditional vertical one. Variation of target strength varies while using tilted beam angle were discussed both by ex-situ and in-situ experiment. In ex-situ experiment, we measured TS of sample fish in different attacking beam angle in three different rotation planes, and conducted by setting four different beam angles to detect free-swimming fishes in a cage. We found that fish length estimated by different title angle varied greatly, but maintained linear relationship with target strength at tilt angle of 30o and 60o. In in-situ experiment, we developed a special trackline for acoustic survey using 60o tilt beam angle together with scuba diving observation to evaluate fish aggregation effect among two wind turbines, a wind tower and a neighboring artificial reefs in the Nanlong wind farm. The results showed that in the core area (< 20 m) near the facilities the target strength distribution patterns and values were consistent with the fish length distribution from scuba diving data. In the joint surveys, we observed that the wind turbines had relatively better fish aggregation effect than nearby neighboring wind towers and artificial reefs.

Flexoelectric and dielectric effects in uniform lying helix cholesteric liquid crystals

ABSTRACT Both flexoelectric effect and dielectric effect affect the director of uniform lying helix (ULH) cholesteric liquid crystals (CLCs). By using a finite-difference iterative method to solve the numerical solution of the Euler equations, we investigate the polar angle and the tilt angle of the director affected by the coupling of flexoelectric effect and dielectric effect. We find that flexoelectric effect and dielectric effect can be quantitatively analysed, and dielectric effect makes the director changes nonuniformly in the helix plane and inclines unevenly with respect to the helix plane. We conclude that the tilt angle is not affected by the dielectric effect under one-constant approximation. In nonequal elastic constants, the influence of dielectric effect on tilt angle is different. Under the same electric field and dielectric anisotropy, the decrease of K 33 or K 22 can increase the title angle, and K 33 has more influence on the title angle than K 22. Remarkably, our method provides a more accurate theory basis for the rotation of the optic axis in ULH CLCs.

Performance evaluation of different photovoltaic (PV) modules: A case study

Climate change and global warmings are the main challenges for today and the future nations from the health and environment perspectives. Energy generation utilizing fossil fuel is the leading cause of these issues. On its opposite side, elimination or suppression of fossil fuel utilization by introducing clean and abundant renewable energy resources could be the best solution. In general, renewable energies have low efficiency and high capital cost compared to conventional fossil fuel-based energy supply. Therefore, without considering proper approaches and techniques, it is not encouraging to supply energy through renewable energy resources. Conquering the problem, we need to find the best method and ways to create cheap and efficient energy by renewable sources as possible. In this paper, a methodology is investigated and proposed to simultaneously save energy and cost considering useful parameters such as the effect of different modules, temperature, location, and tilt angle. An estimation-based tool developed by National Renewable Energy Laboratory (NREL) known as PV Watts, which is utilized in this paper. A 10 kW photovoltaic system with three different modules in two different locations Kabul and Kandahar in Afghanistan is selected as a case study. From the results, it is found that selection of a specific module for a specific region with different temperatures and appropriate title angles has a significant effect on the performance of photovoltaic systems. It is worthy of mention that before implementing a photovoltaic system, different aspects of the system should be evaluated using proper software/tools in order ...

Thermally induced generation and annihilation of magnetic chiral skyrmion bubbles and achiral bubbles in Mn–Ni–Ga magnets

Magnetic chiral skyrmion bubbles and achiral bubbles are two independent magnetic domain structures, in which the former with an equivalent winding number to skyrmions offer great promise as information carriers for further spintronic devices. Here, in this work, we experimentally investigate the generation and annihilation of magnetic chiral skyrmion bubbles and achiral bubbles in the Mn–Ni–Ga thin plate by using Lorentz transmission electron microscopy (L-TEM). The two independent magnetic domain structures can be directly controlled after field cooling manipulation by varying the titled angles of external magnetic fields. By imaging the magnetization reversal with increasing temperature, we found an extraordinary annihilation mode of magnetic chiral skyrmion bubbles and a non-linear frequency for the winding number reversal. The quantitative analysis of such dynamics was performed by using L-TEM to directly determine the barrier energy for the magnetization reversal of magnetic chiral skyrmion bubbles.

Vibration characteristics analysis of magnetically suspended rotor in flywheel energy storage system

The detailed relationship between the vibration characteristics of the magnetically suspended rotor (MSR) and system parameters is modeled and analyzed experimentally in this article. The results indicate that the stiffness of the MSR is tunable by regulating the proportional coefficient of the control system such that the desirable natural frequency of the MSR can be achieved. Damping of the MSR is also controllable by regulating the derivative coefficient of the control system. Therefore, the natural frequency of the rotor can be tuned far away from the working frequency in order to avoid the resonant vibration, and the transmissibility amplitude can be mitigated by tuning the damping. Furthermore, the tilting responses of the MSR with different disturbances are analyzed. The results show that the tilting angle of the MSR decreases with the rotational frequency when the impulse disturbance is imposed on the MSR, but the titling angle increases with the rotational frequency when the harmonic disturbance is acting on the MSR. As a result, the vibration analysis and control of the MSR can be realized based on the tilting angle response. Both simulation and experiment are conducted to verify that the torque generated by the radial active magnetic bearing can suppress the vibration of the MSR.

A comparison between simulation and empirical methods to determine fixed versus sun-tracking photovoltaic panel performance

This paper presents a comparison between a simulation and an empirical method to determine the performance of fixed versus sun-tracking photovoltaic (PV) panels. A comparison is also done of the breakeven point for the extra cost of implementing a dual-axis tracking system in three scenarios (one panel, four panels, and nine panels). Measurements and comparisons in both the simulation and the empirical approaches included realistic energy generation and associated benefits/costs of two similar solar panels, where one is oriented by accurate manual sun tracking and the other is in a fixed horizontal position on four selected days in four seasons. The empirical results show that a single panel sun-tracking system will never reach a breakeven point, while four panels and nine panels will reach the breakeven point in 8 and 18 years, respectively. The simulation results were about 15% less than the empirical results (never, 7, and 15 years for one, four, and nine panels, respectively). Additionally, the use of sun-tracking mechanisms is more effective for winter months compared to summer months. This is due to the Earth's titling angle and the sun being at the highest point in the sky, with sun-tracking and fixed-horizontal panels in a more similar position in the summer compared to winter.

A comparison between simulation and empirical methods to determine fixed versus sun-tracking photovoltaic panel performance

This paper presents a comparison between a simulation and an empirical method to determine the performance of fixed versus sun-tracking photovoltaic (PV) panels. A comparison is also done of the breakeven point for the extra cost of implementing a dual-axis tracking system in three scenarios (one panel, four panels, and nine panels). Measurements and comparisons in both the simulation and the empirical approaches included realistic energy generation and associated benefits/costs of two similar solar panels, where one is oriented by accurate manual sun tracking and the other is in a fixed horizontal position on four selected days in four seasons. The empirical results show that a single panel sun-tracking system will never reach a breakeven point, while four panels and nine panels will reach the breakeven point in 8 and 18 years, respectively. The simulation results were about 15% less than the empirical results (never, 7, and 15 years for one, four, and nine panels, respectively). Additionally, the use of sun-tracking mechanisms is more effective for winter months compared to summer months. This is due to the Earth's titling angle and the sun being at the highest point in the sky, with sun-tracking and fixed-horizontal panels in a more similar position in the summer compared to winter.

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.

Simple structure THz metamaterial with broadband double-negative refraction

A broadband negative-refractive index metamaterial, composited of two square-shaped aluminum apertures with different title angles etched on both sides of polyimide substrate, has been proposed. The calculated results indicate that the coupling between the titled and untitled square-shaped apertures is more conducive to the high-pass and broadband transmission than the combination of two untitled structure. The high-pass band of metamaterial increases from 0.43 to 0.76 THz with the increasing aperture width from 30.0 to 35.0 μm, meanwhile, the maximum bandwidths of double-negative refraction and negative-refractive index can reach up to 0.58 and 0.78 THz, respectively. The highpass transmission mainly locates at the double-negative refraction region. Furthermore, the negative refraction of the NIMs has been verified by the classical method of the wedge, and the results show many unique properties of the symmetric slab waveguide based on the proposed NIM.

An investigation of channel blockage effects on hydrogen mass transfer in a proton exchange membrane fuel cell with various geometries and optimization by response surface methodology

A 2D mathematical modeling was developed to analyze the mass transport in a proton exchange membrane fuel cell. The pin fins were inserted in the flow channel to improve reactant gas distribution in the gas diffusion layer (GDL). The effect of rectangular and triangular shape of fins and different title angles of 4, 6 and 8° on the reactant gas transport were examined. The results showed that performance of rectangular fins are better than triangular fins due to increasing reactant spread over the GDL. The effect of three independent factors including length and width of blocks and hydrogen gas velocity on the response (hydrogen gas diffusion to GDL and pressure drop in anode channel) was investigated using analysis of variance (ANOVA). The results showed that block height and hydrogen gas velocity are the most important factors affecting the responses. Also, response surface methodology (RSM) method was used to predict the optimal conditions to achieve the minimum the pressure drop and maximum the total flux magnetic H2 to GDL in anode channel. The result of the optimization process shows that a gas velocity of 4.22 m/s and the block with height and width of 3 mm are the optimal conditions.