Release Angle Research Articles

Analysis of Performance and Emission of Diesel Engines Operating on Palm Oil Biodiesel

<div class="section abstract"><div class="htmlview paragraph">Fast consumption of fossil fuels is demanding researchers to find few potential alternative fuels that meet sustainable energy demand in the near future with least environmental impact. Future energy system needs to be cost-efficient, renewable, and safe to handle. Biodiesel is expected to be the future energy source that meets all the environmental norms. The use of biodiesel in Internal Combustion (IC) engines represents an alternative clean energy source compared to hydrocarbon fuels that generate emissions such as carbon dioxide (CO<sub>2</sub>), carbon monoxide (CO), nitrogen oxides (NO<sub>X</sub>), Sulfur Oxides (SO) and particulate matters (PM). This paper describes the importance of Palm Oil Diesel (POD) as an alternative fuel source for diesel engines. Simulations are carried out with ANSYS FORTE software with POD. The engine chosen is a 26-kW diesel-gen-set. The engine geometry is drawn in SOLIDWORKS using dimensions of the actual diesel engine. Then, the geometry is imported in ANSYS FORTE and simulations are carried out with diesel and compared with the experimental data which shows around 97% accuracy. Then, a CHEMKIN file is created to use POD in ANSYS FORTE. Thereafter, simulations are carried out with POD with standard engine settings and compared with diesel. The engine performances are lower with POD due to lower calorific value, higher viscosity, higher density and heavier molecules present in POD. POD has a higher cetane number which is beneficial from the combustion point of view. In-cylinder pressure, temperature and accumulated heat release vs. crank angle are plotted to find out the combustion characteristics of POD and compared with diesel. The liquid and vapor penetration length, droplet size and mass are also plotted and compared with diesel.</div></div>

Kinematic bidimensional analysis of the propulsion technique in wheelchair rugby athletes.

Wheelchair rugby is a sport ideated for individuals with cervical spinal cord injury (CSCI) which is extremely important for maintaining their neuromuscular abilities and improving their social and psychological wellbeing. However, due to the frequent changes in direction and speed it considerably stresses the players’ upper limbs. 13 athletes have undergone two sports-related tests on an inertial drum bench and several kinematic parameters have been registered. Most athletes use a semi-circular pattern which is considered protective for the upper limb. With increasing speed, range of motion (ROM) increases. Release angles increment and contact angles reduce, displacing the push angle forward to increase speed. Instead, the more anterior late push angle used to increase velocity is a factor which further loads the shoulder joint. However, other factors affecting propulsion technique, such as posture and wheelchair set up should be studied to further reduce loading on the upper limb.

RETRACTED ARTICLE: Development of novel and efficient approach for analyzing and monitoring the movement parameters for javelin athletes based on internet of things

The javelin is one of the well-received track and field events, which are available from the origin of the human race. The people from the old civilization used the spear-like structure for hunting animals and a soldier to kill enemies in the Warfield used later spear. Due to the development of the human race, the skill of throwing spear was added to the sports category. It is named as Javelin, and all countries play it over the world. The ultimate goal of Javelin throw is to throw a javelin with exposed hands with the highest force so that it will achieve the maximum distance in a given area. Several factors need to be considered for playing this game effectively, they are physiological parameters, a movement (or) release parameters, and injury parameters of javelin athletes. In the proposed work, we design a device, which is used to measure the movement, or release parameters of a javelin by using various sensors and these measured parameters are sent to a cloud server with the help of Wi-Fi device for maintaining a database. The coach or athlete can view the release parameters of javelin such as the angle of release, the height of release and speed of release in real-time through the application called Real-Time Sports Training for Javelin Athletes (ROSOTO-JAV). By monitoring and analyzing, certain throw and provide auto feedback to the athlete along with their parameters to improve their performance in future using the IoT technology.

Research on the looping pendulum phenomenon

The phenomenon of the looping pendulum proposed by the International Young Physicists’ Tournament in 2019 is investigated experimentally and theoretically. By dividing the looping pendulum phenomenon into two physical stages, and establishing physical models, the effects of mass ratio, thread length, initial release angle, and friction coefficient on the dropping height, velocity of the heavy load, and trajectory of the light load in the phenomenon are numerically simulated. Furthermore, experiments are carried out to verify the theoretical predictions. The experimental results are consistent with the results of the theoretical analysis.

Basketball players minimize the effect of motor noise by using near-minimum release speed in free-throw shooting

The aim of this study was to clarify the strategy used by basketball players during free-throw shooting to improve performance in the presence of motor noise. Two possible hypotheses were examined: the players minimize the release speed to decrease signal-dependent noise or the players maximize the shot success probability by accounting for their variability. Eight collegiate players and one professional player participated in this study by attempting shots from the free-throw line using a motion capture system. The solution manifold consisting of ball parameters at release was calculated and the optimal strategy was simulated by considering ball parameter variability; this result was compared with the actual data. Our results showed that participants selected the solution of near-minimum release speed. The deviation of the measured release angle from the minimum-speed angle was close to zero (2.8±3.1∘). However, an increase in speed-dependent noise did not have a significant influence on the ball landing position through simulation. Additionally, the effect of release angle error on the ball landing position was minimum when using the minimum speed strategy. Therefore, the players minimize the release speed to minimize the effect of the release error on performance, instead of minimizing the speed-dependent noise itself. In other words, the strategy is "near-minimum-speed strategy" as well as "minimum-error-propagation strategy". These findings will be important for understanding how sports experts deal with intrinsic noise to improve performance.

Shape design for stabilizing microparticles in inertial microfluidic flows

Design of microparticles which stabilize at the centerline of a channel flow when part of a dilute suspension is examined numerically for moderate Reynolds numbers ($10 \le Re \le 80$). Stability metrics for particles with arbitrary shapes are formulated based on linear-stability theory. Particle shape is parametrized by a compact, Non-Uniform Rational B-Spline (NURBS)-based representation. Shape-design is posed as an optimization problem and solved using adaptive Bayesian optimization. We focus on designing particles for maximal stability at the channel-centerline robust to perturbations. Our results indicate that centerline-focusing particles are families of characteristic "fish"/"bottle"/"dumbbell"-like shapes, exhibiting fore-aft asymmetry. A parametric exploration is then performed to identify stable particle-designs at different k's (particle chord-to-channel width ratio) and Re's ($0.1 \le k \le 0.4, 10 \le Re \le 80$). Particles at high-k's and Re's are highly stabilized when compared to those at low-k's and Re's. A comparison of the modified dumbbell designs from the current framework also shows better performance to perturbations in Fluid-Structure Interaction (FSI) when compared to the rod-disk model reported previously (Uspal & Doyle 2014) for low-Re Hele-Shaw flow. We identify basins of attraction around the centerline, which span larger release-angle-ranges and lateral locations (tending to the channel width) for narrower channels, which effectively standardizes the notion of global focusing in such configurations using the current stability-paradigm. The present framework is illustrated for 2D cases and is potentially generalizable to stability in 3D flow-fields. The current formulation is also agnostic to Re and particle/channel geometry which indicates substantial potential for integration with imaging flow-cytometry tools and microfluidic biosensing-assays.

A combined physical and DEM modelling approach to improve performance of rotary dryers by modifying flights design

To characterize the drying process in the Gol-E-Gohar pelletizing plant ball mill the material veiling profile (material showering) was studied by physical modeling and DEM. To simulate the trajectory of particles in the dryer in a reasonable period of time the GPU parallel processing was implemented in the DEM codes. After calibration of DEM parameters by using the model dryer, various flight designs were then employed in the simulation to find an appropriate veiling profile. It was found that by decreasing the release angle of flights from 70° to less than 40° the coverage of hot gas tunnel cross section by particles increases from 41.6% to 89.6%. The simulations also indicated that by changing the flight edge from the raised edge to the rectangular tooth-like type, the coverage of hot gas tunnel cross section could reach 97.1% and more uniform veiling profile could be obtained. Evaluation of the grinding performance over a period of 15 months showed an increase of 17 t/h in the throughput in the case of the new flights in mill No. 1 while for the same period, mill No.2 experienced a decrease of 7 t/h in the throughput with the original flights for the same feed.

Attaching mass to the upper arm can increase throw distance in a modified javelin throw

The effectiveness of the whip-like coordination in throwing might be influenced by the inertial properties of the athlete's arm. This preliminary study investigated the acute effect of attaching mass to the upper arm on the distance achieved in a modified javelin throw. The aim was to identify the optimum upper arm mass that maximizes throw distance. Three well-trained adult male athletes performed maximum-effort throws with an 800-g javelin training ball. A wide range of masses (0-1.5 kg) were attached to the upper arm and a 2D video analysis was used to obtain measures of the projection variables for each attached mass. All three athletes showed an effect of attached arm mass on throw distance, and with the optimum mass the athlete's throw distance was increased by 2.2 m, 1.2 m, and 0 m (7%, 4%, and 0%) respectively. The optimum mass was specific to the athlete (0.6 kg, 0.2 kg, and 0 kg) and changes in throw distance were mostly due to changes in release velocity rather than changes in release angle or release height. The experimental results were broadly similar to those obtained using a simple 2D mathematical model of throwing. These results indicate that some javelin throwers might see an increase in throwing performance when a mass is attached to their upper arm. However, the relationship between upper arm mass and throwing performance should be investigated further with studies on more athletes, projectiles of different mass, and other throwing events.

Numerical study on the influence of initial conditions on quasi-periodic oscillation of double pendulum system

The double pendulum system is a common and typical model to investigate nonliner dynamics due to its various and complex dynamical phenomenon. In this paper, the effects of several parameters on the system was studied, such as the length and the initial release angle of the pendulums. Though the Swing length - frequency diagram, the details of ocsillation was researched and a non-smooth inflection point was observed on the curve.

Kinematical Analysis of Off-Spin Bowling at Club level Cricket

Cricket is the most famous game but no research work in cricket in the field of biomechanics. The aim of study was to find out the relationship of body segments angles, height of release, angle of release and average speed with deviation of ball. Eight males off spin bowlers has to bowl six legal deliveries. Descriptive statistics was used for describing the data. Pearson product moment correlation was used for the various relationship of the variable to the deviation of the ball. Angle of release (r=0.895**), average velocity (r=0.852), ankle joint left (r=.604), knee joint left (r=0.642), shoulder joint left (r=-.610) and elbow joint left (r=-.694) were significantly correlated to the deviation of the ball. Result shows that the balls bowled by bowlers with greater angle of release, on higher speeds and with extended left ankle angle were deviate more. Ball deviate more with lesser left shoulder and elbow angles.

Laboratory experiments evaluating sedimentation and mound formation of obliquely discharged sand particles in stagnant water

Many parameters are involved in the deposition of a known mass of sand particles discharge from oblique pipes used in a range of engineering applications. Existing knowledge is not sufficient to accurately predict sediment mound dimensions and development from vertical and horizontal pipes. To better understand deposition patterns, laboratory experiments were done to investigate the development of subaqueous sand deposits from oblique pipes in stagnant water. Factors including nozzle diameter, release angle, release height, and sand mass were evaluated. It was found that nozzle size plays the most important role in shape formation and mound development. Release angle and release height were secondarily important. Five different shape patterns were observed and denoted as circular, ellipse, circular-ring, ellipse-ring, and pear-shaped. The scour hole diameter in the middle of the sediment mound was predicted using engineering assumptions and available semi-empirical correlations from the literature. It was found that the existing formulations can accurately predict the size of the scour hole for large release angles (θ = 60°). An aspect ratio of L/do was defined to combine the effect of nozzle size, do, and sand mass where L is the equivalent length of sand particles in a pipe. It was found that the mass balance equation can predict the deposition for L/do < 100. For higher aspect ratios, semi-empirical formulations were developed to predict the deposition length, width, height, and area with ±10% error.

Changes on movement control of dart throwing under distance and target weight constraints

The aim of the study was to verify the effects of dart weight and target distance on kinematic variables of the movement control of the underarm dart throwing task. Four women and one man performed the task of throwing a dart at two horizontal circular targets located at 2m (Nt) and 3m (Ft) away, with two different weights, 22g (Ld) and 44g (Hd). On the first phase of the experiment, the human volunteers performed 200 trials per day during four sessions. On the fifth day, it had 40 more trials in a pseudo random order that were recorded and analysed. A high precision camera recorded the kinematic variables amplitude of the movement (AOM), release height, movement time, release velocity and release angle, with a frequency of acquisition of 100 Hz. Performance was measured by the distance from the actual dart position to the target bull’s eye. The analysis revealed that increasing the mass of the dart diminished only the release angle. However, increasing the distance of the target increased in the AOM and the movement time of the arm, the release velocity of the dart and increased the absolute error. The results show that the motor control system has ability to deal with external constraints adjusting control strategies, which is represented by kinematic features. Moreover, our results suggests that varying the mass of implements, as a constraint may be a good candidate to improve the analysis for both motor control and ability during practice.

Effects of rotational velocity and hold time at folding posture on time-dependent release behavior of creased white-coated paperboard

In this work, a folding experiment was performed to investigate the time-dependent creasing characteristics of white-coated paperboard of 0.3mm thickness. After folding up to the tracking angle of 90° under a specified rotational velocity, the creased part was hold for a chosen short time (0~20s) and the time-dependent release behavior of folding angle was experimentally investigated for the elapsed release time of 10s. When using the paperboard scored with a specified indentation depth, both the hold time of folded posture of creased part and the rotational velocity of fixture were varied. The folding angle of the paperboard was measured by a CCD camera of digital microscope and the bending moment resistance was measured by a load cell of bending test apparatus in the folding experiment. Through the experiment, it was found that the time-dependent release angle consisted of the hold time based intercept part and the creep-recovery based gradient part as a logarithmic function of the elapsed release time. When varying the folding velocity against a fixed unfolding velocity, the unfolded released behavior was isolated by the hold time from the first half folding velocity. Seeing the drop rate of bending moment at the tracking position and the dependency of initial release angle on the rotational velocity, a transient state and quasi-stationary state of bending moment relaxation were revealed.

A Bilateral Comparison of the Underlying Mechanics Contributing to the Seated Single-Arm Shot-Put Functional Performance Test.

Functional performance tests (FPTs) are tools used to assess dynamic muscle strength and power. In contrast to the lower extremity, fewer FPTs are available for the upper extremity. The seated single-arm shot put test has the potential to fill the void in upper extremity FPTs; however, the underlying mechanics have not been examined and, therefore, the validity of bilateral comparisons is unknown. To examine the effects of upper extremity dominance and medicine-ball mass on the underlying mechanics of the seated single-arm shot put. Crossover study. Biomechanics laboratory. Fifteen women (age = 23.6 ± 2.1 years, height = 1.65 ± .07 m, mass = 68.1 ± 11.7 kg) and 15 men (age = 24.3 ± 4.0 years, height = 1.80 ± 0.06 m, mass = 88.1 ± 16.4 kg), all healthy and physically active. Seated single-arm shot-put trials using the dominant and nondominant limbs were completed using three 0.114-m-diameter medicine-ball loads (1 kg, 2 kg, 3 kg). Customized touch-sensitive gloves, synchronized with kinematic data of the hands, signaled ball release, so that release height, release angle, and peak anterior and vertical velocity could be quantified for each trial. In addition, the horizontal range from release to first floor impact was recorded. The dominant-limb horizontal ranges were 7% to 11% greater ( P < .001) than for the nondominant limb for each of the 3 ball masses. No bilateral release-height or -angle differences were revealed ( P ≥ .063). Release velocities were 7.6% greater for the dominant limb than the nondominant limb ( P = .001). Our results support the use of the seated single-arm shot put test as a way to compare bilateral upper extremity functional performance. The near-identical release heights and angles between the dominant and nondominant limbs support the interpretation of measured bilateral horizontal-range differences as reflecting underlying strength and power differences.

Analysis of the separation angle between the thorax and pelvis, and its association with performance in the hammer throw

The hammer throw is perhaps one of the most misunderstood and difficult events to learn in track and field. Improvements in technique are focused on strategies designed to increase implement release velocity. The purpose of this cross-sectional investigative study was to examine the association between the angle of separation between the thorax and pelvis and performance in the hammer throw. Two male and four female throwers were used to assess positional data of the hammer, thorax, and pelvis. Hammer positional data were used to determine linear hammer speed at release, release angle, and release height. Thorax and pelvis positional data were used to determine thorax rotation relative to the pelvis (separation angle). The association between values of separation angle at key instances and performance was examined. Performance was determined by distance thrown (55.69 ± 3.42 m). Release speeds (24.32 ± 0.70 m/s) were also examined as a contributory factor towards performance and were included to account for instances where throwers released the hammer using sub-optimal release heights and angles which negatively affected distance thrown. The separation angle at its smallest within each turn was found to have a strong negative association with the performance indicators, especially in the first two turns (significant correlates ranged from −0.82 to −0.97). This finding indicates when throwers reduced the separation to a smaller value, performance was enhanced. Separation angle was at its smallest in double support. This suggests that throwers may improve performance by reducing the separation angle during double support phases.

Progression of heavy plates from stable falling to tumbling flight

This study examines the transition of stable falling to tumbling flight for freely falling heavy plates in a two-dimensional viscous fluid, solved via direct numerical simulation with the immersed boundary method. The simulations are performed at a range of Reynolds number ($Re$) of up to 500 and a dimensionless moment of inertia ($I^{\ast }$) up to 10. It is found that a plate may settle to stable falling or develop into tumbling descent depending on the initial angle of release $\unicode[STIX]{x1D703}_{0}$. The characteristics and performance that distinguish two flight states are investigated. This bistability is analysed with phase portraits and the region mapped across the regime of $I^{\ast }$ and $Re$ at a specific thickness ratio. In determining the flight state, the respective critical $\unicode[STIX]{x1D703}_{0}$ is found to follow a power law through $I^{\ast }$ and $Re$. It is suggested that the changing slope of the lift curve that the plate undergoes sets the two flight states apart. Flow fields also reveal that the recirculation behind the plate is confined by the vortex structures and provides an additional rotation to the plate. An experiment is performed suggesting that bistability also occurs at Re ${\sim}O(10^{4})$. Other shapes are also simulated and the different bistable effects are discussed.

Accelerated Decline in Javelin Throwing Performance in Master Athletes 70 Years and Older - Do Changes in Technique Play a Role?

While many older adults are immobile and frail, others still participate in competitive sports. World records of javelin throw decrease with increasing age. It is, however, unknown 1) whether the decline is linear or, as in sprint performance, accelerates beyond the age of 69; and 2) to what extent frailty-related changes in throwing technique contribute to decreasing performance. We plotted current world records against age and assessed the performance of 27 male javelin throwers 69 years and older during three master athletics championships. Three to six throws were filmed, and the best throw of each athlete selected. A step-wise linear regression was applied to assess contributions of age, angle of release, angle of attitude, angle of attack and elbow angle just before the pull to performance. The ageing-related decline in javelin-throw performance accelerated after age 69. Age was the main predictor of performance (adjusted R 2 =0.68), with a small contribution of elbow angle (adjusted R 2 increased to 0.76) and angle of attack (R 2 =0.82; all P<0.001) in the older athletes. None of the technique-related parameters correlated with age. Although the technique had some influence on javelin-throwing performance, the accelerated decline was not associated with a characteristic ageing-related change in technique.

Experimental investigation of generic ice block trajectories under freestream conditions

An experimental database of trajectories featuring idealized, simplified artificial ice blocks under freestream conditions has been created. It includes a variation of key parameters such as the ice block geometry, density, freestream velocity and release angle of attack. The ice block’s position and attitude were optically tracked using a system of two high-speed cameras and a dedicated post-processing routine. The work performed in the scope of the EU co-funded research project STORM aims at the validation and further development of current simulation tools for ice release and ice block trajectories in terms of their ability to cope with the high complexity and randomness of this phenomenon. These tools of different level of fidelity are currently used during the aircraft certification process to estimate the threat of large ice pieces released from the aircraft’s surface impacting into downstream components. The major experimental findings are discussed in this article alongside first promising results from numerical trajectory simulations.

Does shortening the pitch make junior cricketers bowl better?

ABSTRACTIn order to get bounce and movement seam bowlers need to bowl the ball “into” the pitch. Standard deliveries by elite players are typically projected at around 7° below horizontal. In contrast, young players currently often need to release the ball almost horizontally in an effort to get the ball to bounce close enough to the batter. We anticipated that shortening the pitch could be a simple way to help young bowlers to release the ball at a better angle and with more consistency. Twenty county or best in club age group under 10 and under 11 seam bowlers were analysed bowling indoors on two different pitch lengths. They were found to project the ball on average 3.4° further below horizontal on a 16 yard pitch compared with a 19 yard pitch, while ball speed and position at release changed negligibly. Pitch length did not affect the consistency of the release parameters. The shorter pitch led to a ball release angle closer to that of elite bowlers without changing release speed, and this should enable players to achieve greater success and develop more variety in their bowling.

An Investigation on the Effects of Different Stratifications on Negatively Buoyant Jets

Negatively buoyant jets develop when fluids are released upwards into a lighter fluid or, vice versa, downwards into a heavier fluid. There are many engineering applications, such as the discharge, via submerged outfalls, of brine from desalination plants into the sea. Some concerns are raised about the potential negative environmental impacts of this discharge. The increase in salinity is the major cause for environmental impact, as it is very harmful to many marine species. The diffusers for brine discharge are typically inclined upwards, to increase the path before the brine reaches the sea bottom, as it tends to fall downwards driven by negative buoyancy. The negatively buoyant jet that develops conserves axisymmetry only when released vertically, so that it is not possible to use the well-known equations for axisymmetric jets. The main target of this paper is to investigate on a laboratory model the effects of different stratifications on the features of negatively buoyant jets. This has been done via a LIF (Light Induced Fluorescence) technique, testing various release angles on the horizontal and densimetric Froude numbers. Except for the initial stage, a different widening rate for the upper boundary and the lower boundary has been highlighted.