Entry Angle Research Articles

Design and Test of Single-Disc Opener for No-Till Planter Based on Support Cutting

To solve the problem of low straw-cutting efficiency of single-disc openers of no-till planters under conditions of high soil moisture content, a single-disc furrowing and straw-cutting device was designed based on the support-cutting principle. To improve the straw-cutting ability of the disc opener when it operates under high-moisture-content soil conditions and to make sure that the straw that is not cut by the disc coulter can be cut smoothly by the disc opener, the support shovel was designed, and the operation mechanism of the support shovel device was analyzed. The soil moisture content, the support shovel’s entry angle, the support shovel’s entry gap angle, and the support shovel’s tip margin were identified as the factors influencing the device design through the theoretical analysis of the furrowing and straw-cutting device. Through the discrete element method (DEM), a single-factor simulation test was first conducted to analyze how different soil moisture contents affected the device’s ability to cut straw, and the results showed that the number of broken bonds was lowest when the soil moisture content was 20 ± 1%, and the time taken for the straw to be wholly cut off was also the longest. Then, a quadratic orthogonal simulation test was conducted to construct a regression model and optimize the parameters at the soil moisture content of 20 ± 1%, and the results revealed that the significant order of each factor’s influence on the number of broken bonds is as follows: entry gap angle, entry angle, and shovel tip margin. In addition, the device’s overall operation quality was better when the entry angle was 49°, the entry gap angle was 0°, and the shovel tip margin was 10 mm. At this time, the number of broken bonds was predicted to be 506. Finally, the simulation validation test was run, and the number of broken bonds was obtained to be 478, with a relative error of 5.6% from the predicted value. According to the optimal parameters to complete the device trial production and field test, the results show that the average cut-off rate of the device is 71.7%, the stability coefficient of the furrowing depth is 90.87%, and the performance of the furrow opening is excellent, which meets the requirements of a no-tillage seeding operation. This study can provide a reference for the design and improvement of no-tillage seeding machines under conditions of high soil moisture content.

Effect of backstroke ledge on backstroke start technique for water entry

ABSTRACT This study aimed to investigate how the use of a backstroke ledge (BSL) affects backstroke start performance in terms of flight distance and water entry posture in competitive backstroke swimmers. Ten male swimmers performed a maximum of 15 m in backstroke, starting with or without a BSL. Two 120 Hz and one 60 Hz video cameras were used to analyse the kinematic variables and angular momentum of the whole body. Using a BSL reduced the time to reach 5 and 15 m compared with not using a BSL (p < 0.04). Using a BSL heightened vertical position of the centre of mass (CM) at take-off, lengthened flight distance, and increased angular momentum (p < 0.02). Additionally, the lower limb entry angle was larger, and the hole entry posture angle was smaller with a BSL than without a BSL (p < 0.04). These results suggest that a high CM position at the start of the backstroke with a BSL increased the flight distance, and a large angular momentum enabled hole entry as well as improved the horizontal velocity after water entry. Hence, increases in flight distance and velocity after water entry were contributing factors in improving the start performance of the backstroke when using a BSL.

3D simulation of percutaneous sustentaculum tali screw insertion in calcaneal fractures

BackgroundIn calcaneal fractures, the percutaneous screw fixation (PSF) is currently considered to be the better choice, but it is difficult to accurately place the screw into the sustentaculum tali (ST) during the operation. In this study, the ideal entry point, angle, diameter and length of the screw were calculated by simulating the operation process.MethodsWe retrospectively collected the calcaneus computed tomography (CT) scans of 180 adults, DICOM-formatted CT-scan images of each patient were imported into Mimics software to establish calcaneus model. Virtual screws were placed on the lateral of the posterior talar articular surface (PTAS), the lateral edge of the anterior process of calcaneus (APC), and the calcaneal tuberosity, respectively, the trajectory and size of the screws were calculated.ResultsThe mean maximum diameter of the PTAS screw was 42.20 ± 3.71 mm. The vertical distance between the midpoint of the APC optimal screw trajectory and the lowest point of the tarsal sinus was 10.67 ± 1.84 mm, and the distance between the midpoint of the APC optimal screw trajectory and the calcaneocuboid joint was 5 mm ~ 19.81 ± 2.08 mm. The mean maximum lengths of APC screws was 44.69 ± 4.81 mm, and the Angle between the screw and the coronal plane of the calcaneus from proximal to distal was 4.72°±2.15° to 20.52°±3.77°. The optimal point of the maximum diameter of the calcaneal tuberosity screw was located at the lateral border of the achilles tendon endpoint. The mean maximum diameters of calcaneal tuberosity screws was 4.46 ± 0.85 mm, the mean maximum lengths of screws was 65.31 ± 4.76 mm. We found gender-dependent differences for the mean maximum diameter and the maximum length of the three screws.ConclusionsThe study provides effective positioning for percutaneous screw fixation of calcaneal fractures. For safer and more efficient screw placement, we suggest individualised preoperative 3D reconstruction simulations. Further biomechanical studies are needed to verify the function of the screw.

Hemoliz Nedeni Olarak Diyalizörler

Objective: Hemolysis is a rare adverse effect of hemodialysis. ıt is induced by chemical pollution, heat, or mechanical harm to clogged hemodialysis lines. Lactate dehydrogenase transforms pyruvate to lactate in the absence of oxygen to make energy. LDH serum levels are raised due to tissue breakdown. A number of clinical illnesses, such as hemolytic disorders, are associated with high serum LDH.&#x0D; Both the Rexeed and Leoceed dialyzers are made by AsahiKASEI. They had the same membrane architecture and permeability, but blood entry angle, chamber length, and hole count varied. The aim of this study is to examine if dialyzer design affects hemolysis.&#x0D; Materials and Methods: A total of 142 patients who were chronically undergoing hemodialysis therapy at the ……………….for a total of 12 hours per week were included. A retrospective examination of the patients was performed. The pre-HD and post-HD LDH levels of individuals who had undergone hemodialysis with both dialyzers during separate sessions of hemodialysis were compared.&#x0D; Results: A hundred forty two patients (63% female) on hemodialysis (HD) treatment were enrolled in the study. Twenty eight patients (20%) had diabetes, 45 had hypertension (32%) and 16 had ischemic heart disease (11%) as a comorbid condition.&#x0D; When LDH difference is compared between groups Leoceed dialyzer group) had statistically significantly higher LDH difference when compared with Rexeed dialyzer group (49.1±20 U/l vs229.8±24.45 U/l;p=0.008). (Table 2).&#x0D; Conclusion: It is possible that the design of the dialyzer contributes in some way to the cell damage that is caused by the larger serum LDH increase in the Leoceed dialyzer. In order to carry out corrective studies on dialyzer design, it would be helpful to analyze the impact of dialyzer design on cell damage using a larger series of patients.

Multi-GPU multi-resolution SPH framework towards massive hydrodynamics simulations and its applications in high-speed water entry

We propose a multi-phase, multi-resolution SPH method for fluid/solid interaction with multi-GPU implementation and dynamic load balancing following the movement of the refinement regions. The primary design goal of this framework is to maintain the efficiency of the single-resolution SPH model running on a single GPU. To this end, a multi-background mesh is introduced, and the domain is regarded as a nested multi-domain with different resolutions. Validation using both a δ-SPH and Riemann SPH model is shown, and applications to the simulation of the water entry of a projectile with a high Froude number are considered, with comparisons to experimental data from three challenging test cases, showing the proposed model's ability to correctly reproduce the free surface evolution on water entry, the motion of the projectile, and the formation and evolution of multiple cavities depending on entry angle and velocity. An analysis of the computational performance and resolutions achieved (up to 120 million particles) is also provided across several test cases.

Ideal entry point and direction of retrograde intramedullary nailing of the tibia

PurposeTo determine the ideal entry point and direction of retrograde intramedullary nailing of the tibia.MethodsThe imaging data of patients with distal tibial fractures from June 2020 to December 2021 in our hospital were collected, and computer-aided design was performed. The relevant data were imported into the software for processing, so as to obtain a distal tibial fracture model and simulate the retrograde intramedullary nail placement in the tibia. The entry points and angles at which the intramedullary nail could be inserted successfully and the fracture could be maintained in good alignment were overlapped and counted to obtain the safe entry range and angle. The center of this safe range is the ideal entry point for retrograde intramedullary nailing of the tibia, and the mean value of the angle is the ideal direction of entry.ResultsThe ideal entry point of the retrograde intramedullary nailing was located at the midpoint of the medial malleolus in the C-arm fluoroscopic anteroposterior (AP) and lateral view. The ideal nail entry direction was located at the anatomic axis of the medial malleolus in the AP position and at the anatomic axis of the distal tibial metaphysis in the lateral position.ConclusionThe ideal point and direction of nail insertion for retrograde tibial intramedullary nailing is a "double midpoint, double axis" approach.

Deformation Responses of Extruded Zinc Alloy

Severe plastic deformation (SPD) is a technique used to obtain ultrafine grains (UFGs). However, this technology is expensive and time consuming. In this study, conventional deformation technique is used to study the deformation responses of extruded zinc alloy for fine grain development with varying die entry angles. Zinc alloy samples were cast into cylindrical billets in sand mould, the samples were machined and tapered at the edges to allow for easy entry into the die for the extrusion process. The die and tools materials were made from mild steel with the die entry angles of 15o, 30o, 45o, 60o, 75o and 90o respectively. Prior to extrusion, the samples were annealed at 400°C because of its hexagonal close packed (HCP) structure for ease of deformation. After annealing, the plastic deformation of alloy samples occurred at 350°C as the deformation was not feasible at ambient temperature (32°C). The extrusion was done with the aid of a hydraulic press machine that applies pressure on a cylindrical punch and forces the billet through the extrusion die. Extruded zinc recorded the highest extrusion stress of 192MPa at 45° die entry angle with fine grains neatly distributed in the matrix and at 60° die entry angle, the tensile strength and hardness are 177MPa and 95HV respectively with improved ductility. The microstructure of Zn alloy showed equally distributed dendrite-like second phase intermetallic in the matrix.

Experimental study on ballistic stability of truncated cone projectile in high-speed oblique water entry

In this paper, the high-speed photography technique was used to study the high-speed oblique water entry of truncated cone projectiles, and the effects of nose shape, projectile velocity and entry angle on the cavity and ballistic characteristics of oblique water entry were discussed. The experimental results show that the influence of nose shape on the oblique water entry cavity and ballistic characteristics is related to the nose wetted area. For the same type of projectile, with the increase of projectile velocity, the cavity size becomes larger at the same penetration displacement and the surface closure time gets longer. Moreover, with the increase of entry angle, the surface closure time decreases, the velocity attenuation gets faster, at the same penetration displacement the cavity opening length becomes shorter and the cavity asymmetry weakens. Additionally, the results indicate that the trajectory stability of the truncated cone projectile varies under different water entry velocities and attitude angles.

Numerical simulation of subsonic and transonic water entry with compressibility effect considered

The purpose of this study is to analyze the subsonic and transonic water entry of the axisymmetric body with compressibility effect considered. The water-entry processes of axisymmetric body are numerically investigated, with Tait state equation and energy equation used to describe the compressibility of the liquid. Reasonable agreement has been obtained between the numerical results and the experimental measurements of trajectory, velocity and acceleration. The cavity evolution and dynamic characteristics of subsonic cases are investigated for vertical and oblique water-entry. The results show that the maximum drag coefficient of the oblique water entry is lower, and it is affected by a large moment which causes pitch angle and trajectory inclination angle to change significantly. In the oblique transonic conditions, the effect of compressibility of the liquid on the dynamic flow characteristics is analyzed. On this basis, the influence of entry angle on the hydrodynamic characteristics is investigated. It is concluded that the water-entry angle has a more significant influence on the trajectory characteristics.

Asymmetric flow action on hydrodynamics and structural dynamics for high-speed oblique water entry of the semi-sealed cylindrical shell

To study the hydrodynamics and structural characteristics, numerical simulation of the oblique water-entry process of the semi-sealed and completely sealed cylindrical shell is carried out based on a Star-CCM+ and ABAQUS collaborative simulation method described in this paper. The results show that when the internal fluid pours out of the shell, the jet formed below the shell is asymmetrically distributed, resulting in a significant change in the attitude angle of the shell. This, in turn, causes the upstream surface of the shell to hit the side wall of the cavity, further changing in the attitude angle. The force and stress of the shell with an water entry angle θ0 = 90° is found to be greater than that of the shells with other oblique water entry angles. Additionally, the trajectories of the shells at different water entry angles move upward after reaching the inflection point, and the range of upward movement increases gradually with the decrease of the water entry angle. In summary, the asymmetric flow caused by an hollow structure has a profound impact on the high-speed oblique water entry of the semi-sealed cylindrical shell, causing changes in its trajectory, cavity evolution, and structural characteristics.

Preatmospheric Detection of a Meter-sized Earth Impactor

On 2020 September 18 U.S. Government (USG) sensors detected a bolide with peak bolometric magnitude of −19 over the Western Pacific. The impact was also detected by the Geostationary Lightning Mapper instrument on the GOES-17 satellite and infrasound sensors in Hawaii. The USG measurements reported a steep entry angle of 67° from horizontal from a radiant 13° east of north and an impact speed of 11.7 km s−1. Interpretation of all energy yields produces a preferred energy estimate of 0.4 kt TNT, corresponding to a 23,000 kg, 3 m diameter meteoroid. A postimpact search of telescopic images found that the Asteroid Terrestrial-impact Last Alert System survey captured the object just 10 minutes prior to impact at an Earth-centered distance of nearly 11,900 km with apparent magnitude m = 12.5. The object appears as a 0.44° streak originating on the eastern edge of the image, extending one-third of the USG state-vector-based prediction of 1.26° over the 30 s exposure. The streak shows brightness variability consistent with small asteroid rotation. The position of Earth’s shadow, the object’s size, and its consistency with the reported USG state vector confirm the object is likely natural. This is the eighth preatmospheric detection of a near-Earth asteroid (NEA) impactor and the closest initial telescopic detection prior to impact. The high altitude of peak fireball brightness suggests it was a weak object comparable in many respects with 2008 TC3 (the Almahata Sitta meteorite), with an absolute magnitude H = 32.5 and likely low albedo. Therefore, we suggest the NEA was a C-complex asteroid.

Numerical and experimental investigation of a Mg/N2O powdered fuel rocket engine

Powdered metal fuel rocket engines, utilizing high energy density metal powder as fuel, have great potential in the development of propulsion systems for upper-stage rockets, and thrusters for attitude or trajectory control. The main challenges of this rocket engine technology currently lie in the realization of stable powder fuel supply, quick engine start-up, and high combustion efficiency. In this paper, we present a computational analysis of the reactive flow in a Mg/N2O powdered metal fuel rocket engine. Consideration in this work includes effects of a flame holder, mass flow rate ratio and entry angle of N2O on combustion efficiency. Based on the numerical simulation results, an experimental Mg/N2O powdered metal fuel rocket engine was designed, and working processes of the engine were investigated through hot fire tests with Mg powder as fuel and N2O as oxidant. A ground test system, consisting of a high-precision test bench, a fuel feed unit, an oxidant feed unit, and a measurement and control unit, was established. The test results show that the combustion of Mg powder and N2O can be sustained.

A IMPORTÂNCIA DO SERVIÇO DE TRÁFEGO DE EMBARCAÇÕES PARA NAVEGAÇÃO EM ÁGUAS INTERIORES

A marine traffic control system (VTS) is defined as the service provided by the officer responsible for marine traffic in a given area. Typical services are based around helping ships enter and pass through a traffic area such as a port or canal. These areas are defined as high risk and therefore, without the said officer, they have a high probability of accidents. Thus, the service consists of identifying the different points of risk, be it the distance between two ships, the speed, the angle of entry, etc. to assign levels of danger and a protocol on how to react in each circumstance. Identifying hazards in time is your goal. This study aims to describe the importance of the VTS for navigation in inland waters, which is done through a qualitative bibliographical research. In the end, it was concluded that for maritime navigation in inland waters to be carried out safely, it is necessary to use the VTS, and in Brazil Porto Açu was the first to have the system and currently, others are in the process of being implemented.

Influence of a saltwater film on a radio-transparent dome on the amplitude-phase distribution of a millimeter-range antenna

Transition of communication systems installed on naval ships to the millimeter range requires an analysis of the effect of the saltwater film formed on the radio-transparent dome (RTD) on the radiotechnical characteristics of the mirror antenna. The latter are determined by the amplitude-phase distribution in the antenna aperture, so the topic of research is relevant. The objective of the article is to analyze the effect of the salt-water film on the surface of a marine mounted RTD, as well as the effect of millimeter wavelength antenna placement inside the RTD on the distortion of the field generated in the outer region. It has been shown that when installing millimeter-wave range antennas on a naval ship under a radio-transparent dome it is necessary to consider the distortions introduced by the water film on the dome surface into the generated amplitude-phase distribution when calculating the radio technical characteristics. We do so because most of the known methods for calculating the directivity characteristics of mirror antennas are based on the known amplitude-phase distribution in the antenna aperture. In the paper, the influence of the spherical dome wall and the saltwater film on the amplitude-phase distribution is taken into account as follows. Distortions in the amplitude distribution are caused by energy losses of the electromagnetic wave due to the passage of the curved dielectric wall at different angles. Phase distribution losses are due to the phase shift from the original phase as the dome wall is passed through at different angles. The angles of radio wave entry into the dome wall depend on the location of the antenna inside the radio-transparent dome. The electrical parameters of the saltwater film are determined using the well-known ITU methodology, while its thickness is found using the Gibbs formula, assuming that sea spray is similar to the intensity of drizzle rain. The studies have been conducted for the highest stiffness mode. Studies for a single-mirror antenna with a parabolic reflector 5.4 m in diameter and a radio-transparent dome 18 m in diameter showed that the water film influence is manifested in the phase front distortion, as well as a symmetry violation of the generated amplitude distribution. The degree of water salinity is manifested mainly in the distortion of the phase distribution. This is due to the fact that the electrical parameters of salt and fresh water do not differ much. The detected distortions are stronger for the horizontally polarized waves and in the case when the antenna swing center is offset with respect to the dome symmetry line. The detected patterns allow to give a scientific justification for the choice of the amplitude-phase distribution of the mirror antenna when installing it inside the RTD on the naval ship.

Accuracy of robot-assisted stereotactic MRI-guided laser ablation in children with epilepsy.

Robot-assisted (RA) stereotactic MRI-guided laser ablation has been reported to be a safe and effective technique for the treatment of epileptogenic foci in children and adults. In this study the authors aimed to assess the accuracy of RA stereotactic MRI-guided laser fiber placement in children and to identify factors that might increase the risk of misplacement. A retrospective single-institution review of all children from 2019 to 2022 who underwent RA stereotactic MRI-guided laser ablation for epilepsy was undertaken. Placement error was calculated at the target by measuring the Euclidean distance between the implanted laser fiber position and the preoperatively planned position. Collected data included age at surgery, sex, pathology, date of robot calibration, number of catheters, entry position, entry angle, extracranial soft-tissue thickness, bone thickness, and intracranial catheter length. A systematic review of the literature was also performed using Ovid Medline, Ovid Embase, and the Cochrane Central Register of Controlled Trials. In 28 children with epilepsy, the authors assessed 35 RA stereotactic MRI-guided laser ablation fiber placements. Twenty (71.4%) children had undergone ablation for hypothalamic hamartoma, 7 children (25.0%) for presumed insular focal cortical dysplasia, and 1 patient (3.6%) for periventricular nodular heterotopia. Nineteen children were male (67.9.%) and 9 were female (32.1%). The median age at the time of the procedure was 7.67 years (IQR 4.58-12.26 years). The median target point localization error (TPLE) was 1.27 mm (IQR 0.76-1.71 mm). The median offset error between the planned and actual trajectories was 1.04° (IQR 0.73°-1.46°). Patient age, sex, pathology and the time interval between date of surgery and robot calibration, entry position, entry angle, soft-tissue thickness, bone thickness, and intracranial length were not associated with the placement accuracy of the implanted laser fibers. However, the number of catheters placed did correlate with the offset angle error on univariate analysis (ρ = 0.387, p = 0.022). There were no immediate surgical complications. Meta-analysis indicated that the overall pooled mean TPLE was 1.46 mm (95% CI -0.58 to 3.49 mm). RA stereotactic MRI-guided laser ablation for epilepsy in children is highly accurate. These data will aid surgical planning.

Comparison of the Skin-to-Epidural Space Distance at the three Thoracic levels in Children using Magnetic Resonance Imaging for Epidural Anesthesia

Background: Several ways were used to assess the distance from the skin to the epidural space, with the aim of increasing the success of the technique. MRI is the most significant technological advancement in the diagnostic examination of the pediatric spine. The aim of this study was to evaluate the distance between the skin and the epidural space through MRI at three thoracic segments in children aged 0 to 13 years. Methods: Retrospective study with 105 children aged 0 to 13 years in the supine position underwent MRI, and the 2nd, 5th, and 10th thoracic segments were measured. The following parameters were evaluated: skin and the epidural space; needle entry angle between the skin and intervertebral space; and distance corrected by an angle between skin and the epidural space. To compare the proposed data between the samples, we used the Kruskal-Wallis test. The Kruskal-Wallis rank test is a non-parametric method for testing whether samples come from the same distribution. Results: This study evaluated 60 male and 45 female children. The mean distance between Skin-EpiS was 29.27 mm at T2, 26.52 mm at T5, and 24.28 mm at T10, with a significant difference, being the greatest distance found in T2. The Skin-EpiS at T10 was shorter than the other two measurements. Regarding needle entry angle between skin and the three intervertebral spaces, the smallest angle was observed (T2=27.16º) significantly smaller than in the other two spaces (T5=38.68º, T10=39.08º). However, this difference in angle did not result in a significant difference in the distance between the skin and epidural space corrected by the entry angle in the three intervertebral spaces, being practically the same, T2=33.0 mm, T5=34.60 mm, T10=32.1 mm. Conclusion: Precise Skin-EpiS distance information can facilitate accurate needle placement in children’s epidural space and thus decrease the risk of complications. This study in children aged 0 to 13 years provided important information for performing single shots or continuous thoracic epidurals, reducing the potential for complications during its performance.

Evaluation of Surgical Indications for Full Endoscopic Discectomy at Lumbosacral Disc Levels Using Three-Dimensional Magnetic Resonance/Computed Tomography Fusion Images Created with Artificial Intelligence.

Background and Objectives: Although full endoscopic lumbar discectomy with the transforaminal approach (FED-TF) is a minimally invasive spinal surgery for lumbar disc herniation, the lumbosacral levels present anatomical challenges when performing FED-TF surgery due to the presence of the iliac bone. Materials and Methods: In this study, we simulated whether FED-TF surgery could be safely performed on a total of 52 consecutive cases with L5-S1 or L5-L6 disc herniation using fused three-dimensional (3D) images of the lumbar nerve root on magnetic resonance imaging (MRI) created with artificial intelligence and of the lumbosacral spine and iliac on computed tomography (CT) images. Results: Thirteen of the fifty-two cases were deemed operable according to simulated FED-TF surgery without foraminoplasty using the 3D MRI/CT fusion images. All 13 cases underwent FED-TF surgery without neurological complications, and their clinical symptoms significantly improved. Conclusions: Three-dimensional simulation may allow for the assessment from multiple angles of the endoscope entry and path, as well as the insertion angle. FED-TF surgery simulation using 3D MRI/CT fusion images could be useful in determining the indications for full endoscopic surgery for lumbosacral disc herniation.

The effects of lower extremity muscle strength characteristics on grab and track start performance in young competitive swimmers

BACKGROUND: Limited data exist regarding segmental contributions of lower extremity muscles to the swim start performance during different start techniques in young swimmers. OBJECTIVE: To determine the differences in the kinematic parameters between the grab start (GS) and track start (TS) techniques and assess the interactions between the lower limb muscle strength and swim start performance. METHODS: A total of 40 swimmers, 20 girls (age: 13.70 ± 1.80 y, height: 161.65 ± 8.28 cm, body weight: 53.70 ± 8.65 kg) and 20 boys (age: 13.90 ± 1.45 y, height: 160.95 ± 12.70 cm, body weight: 52.95 ± 12.64 kg), 13–16 y of age, at the competitive level were recruited. Ankle, hip, and knee muscles were tested isokinetically at 60∘/s and the tests were spread over 24 h to avoid fatigue. Several elements relating to GS and TS were measured using a motion pick-up video camera. RESULTS: The angle of entry (EA) at water and knee joint angle (KA) were significantly greater during GS both for boys (EA: 44.18 ± 1.07∘ vs. 43.03 ± 1.28∘; KA: 112.10 ± 15.25∘ vs. 107.21 ± 21.13)∘ and girls (45.09 ± 1.28∘ vs. 43.36 ± 1.55∘; KA: 103.08 ± 11.21∘ vs. 97.45 ± 19.52∘, p&lt; 0.05). Flight time (FT), flight distance (FD), KA, and flight velocity (FV) were significantly higher for boys both during GS and TS, whereas EA was significantly lower for boys during GS compared to girls (p&lt; 0.05). Lower limb strength performance was positively significantly correlated with FT, FD, and FV both during GS and TS (p&lt; 0.05). Hip muscle strength was inversely correlated with the EA both during GS and TS (p&lt; 0.05). The combination of the knee, ankle, and hip extensor and flexor muscle strengths had a greater effect during GS (35% vs. 29%) in RT, (48% vs. 46%) in FT, (59% vs. 57%) in FD, and (63% vs. 57%) in FV compared to the TS. CONCLUSIONS: Incorporating lower body strength training into the swimming training schedule may improve swim start performance variables during grab start and track start techniques.

Modelling the optical energy profile of the 2021 October Jupiter impact flash

ABSTRACT We have conducted numerical simulations to reproduce the observed optical energy profile of the 2021 October 15 (ut) impact flash on Jupiter, which was the largest and the most well-observed flash event detected by ground-based movie observations. The observed long-duration (∼5.5 s) optical emission can be reproduced by an impact of an object with an exceptionally small angle of entry relative to the horizontal. The apparent lack of the impact debris feature despite the large impact object was possibly due to the shallower angle of entry (≤12°), which resulted in the lower ablation per unit volume at altitudes higher than $50 \, {\rm km}$, and the volume densities of the ablated materials were too low to allow the debris particulates to coagulate. The absence of temporal methane absorption change in the observed flash spectrum is consistent with the best-fitting results. The model better fits the observed optical energy profile for weaker material (cometary and stony) cases than for metallic ones. Based on the simulation results, prospects for future observations of impact flashes are discussed.

Towards energy efficient milling of variable curved geometries

Development of energy efficient machining is the present focus to industries for reduction of energy consumption and making the manufacturing system more sustainable. The continuous fluctuation in force profile during machining of variable curved components creates a barrier in stable machining and in cutting power consumption. The fluctuation in force profile happens due to alteration in chip load in the presence of workpiece curvature. The current research work intends to develop an energy efficient machining strategy for milling of variable curved components where more uniform cutting force and power profiles are accomplished due to constant chip load along the peripheral length of curved geometry. The proposed strategy is compared with conventional cutting in order to confirm the acceptability of the present algorithm. The proposed algorithm involves mechanics of milling, cutting forces and cutting power consumption. It is formulated based on constant chip load by regulating entry angle of milling cutter according to workpiece curvature along the peripheral length. Thus, the cutting power fluctuation occurred due to variation of workpiece curvature is reduced by regulating tool-workpiece engagement. The energy consumption during machining is reduced almost 22 % using the proposed approach. It results into developing an energy efficient machining strategy for milling of variable curved geometry. It also provides stable machining process and increased tool life by reducing tool wear due to reduction of force fluctuation during metal removal process.