Effect of Scraper Geometry on Scraping HAP/ZrO2 Slurry in Digital Light Processing

Digital light processing (DLP) can be used to form HAP/ZrO2 mixed ceramic slurry. In the printing technology, the scraper geometry has an important effect on the scraping process; thus, it is necessary to conduct analysis. A modified lattice Boltzmann method (LBM) is proposed to conduct the numerical simulations according to the non-Newtonian behavior of the slurry. The Cross behavior of the slurry is viewed as a special external force; then, the traditional LBM including the true external force can be utilized effectively. The triangle, rectangle, trapezium, and rounded rectangle are the main considered section geometries of the scraper. When the flow velocity is set to 0.1 m/s, the results show that the maximum velocity occurs near the bottom surface of the scraper. In four situations, the velocity peak of the triangle case is 0.6270 m/s, which is the maximum, and much larger than the flow velocity of 0.1 m/s. The velocity peak of the rectangle case is 0.0466 m/s, which is the minimum. Although the velocity peak of the rounded rectangle case is 0.0556 m/s, the second velocity peak is 0.0465 m/s; the difference is smaller than that of the rectangle case. In addition, the streamlines figures show that the sharp corner leads to the obvious velocity change. In summary, the rounded rectangle is considered to be more suitable for scraping the HAP/ZrO2 mixed slurry.

Analysis of Grip Amplitude on Velocity in Paralympic Powerlifting

(1) Background: Paralympic Powerlifting (PP) is a Paralympic modality that is predominantly about developing maximal force, as there are athletes who lift three times their body weight. Our objective was to evaluate the averages of the velocity for 30% and 50% of 1 Maximum Repetition (1 RM) on different amplitudes of the footprint in PP athletes; (2) Methods: The intervention happened over two weeks, with the first being devoted to the familiarization and testing of 1 RM, while in the second week, through the use of a linear Encoder, tests of velocity average (VA), velocity average propulsive (VAP), and velocity peak (VP) were carried out with loads of 30% and 50% of a maximum repetition 1 RM for 1× of the biacromial distance (BAD) 1.3 × BAD, 1.5 × BAD; (3) Results: There was a significant difference in the average velocity of 1 × BAD (1.16 ± 0.14 m/s, 1.07–1.26 IC; η2p 0.20) when compared to 1.3 × BAD (1.00 ± 0.17 m/s, 0.90–1.09 IC; η2p 0.20) over 30% of 1 RM. For the other velocity variables for 30% and 50% of 1 RM with different grip amplitudes, there were no significant differences; (4) Conclusions: In PP, the 1 × BAD footprint contributes significantly to VA at 30% of 1 RM when compared to the 1.3 × BAD and 1.5 × BAD footprints. For loading at 50% of 1 RM the VA, VAP and VP decreased when compared to 30% of 1 RM, to the extent that the VAP and VP generated with the 1.3 × BAD and 1.5 × BAD footprints were higher than those with 1 × BAD, other than for VA 50% of 1 RM, where the 1 × BAD footprint was superior to the others.

Between-session reliability of performance and asymmetry variables obtained during unilateral and bilateral countermovement jumps in basketball players

This study aimed to evaluate the between-session reliability of single-leg performance and asymmetry variables during unilateral and bilateral countermovement jumps (CMJ). Twenty-three basketball players completed two identical sessions which consisted of four unilateral CMJs (two with each leg) and two bilateral CMJs. Mean and peak values of force, velocity and power, impulse, and jump height were obtained separately for each leg using a dual force platform. All performance variables presented an acceptable reliability (CVrange = 4.05–9.98%) with the exceptions of jump height for the unilateral CMJs and mean power, peak velocity, peak power, and impulse for the left leg during the bilateral CMJ (CV≥11.0%). Nine out of 14 variables were obtained with higher reliability during the unilateral CMJ (CVratio≥1.16), and 4 out of 14 during the bilateral CMJ (CVratio≥1.32). Asymmetry variables always showed an unacceptable reliability (ICCrange = 0.15–0.64) and poor/slight levels of agreement in direction (Kapparange = -0.10 to 0.15) for the unilateral CMJ, while an acceptable reliability (ICCrange = 0.74–0.77) and substantial levels of agreement in direction (Kapparange = 0.65 to 0.74) were generally obtained for the bilateral CMJ. These results suggest that single-leg performance can be obtained with higher reliability during the unilateral CMJ, while the bilateral CMJ provides more consistent measures of inter-limb asymmetries.

Debris flows recorded in the Moscardo catchment (Italian Alps) between 1990 and 2019

This paper presents debris-flow data recorded in the Moscardo Torrent (eastern Italian Alps) between 1990 and 2019. In this time interval, 30 debris flows were observed: 26 of them were monitored by sensors installed on the channel, while four were only documented through post-event observations. Monitored data consist of debris-flow hydrographs, measured utilizing ultrasonic sensors, and rainfall. Debris flows in the Moscardo Torrent occur from early June to the end of September, with higher frequency in the first part of summer. The paper presents data on triggering rainfall, flow velocity, peak discharge, and volume for the monitored hydrographs. Simplified triangular hydrographs and dimensionless hydrographs were derived to show the basic features of the debris flows in the Moscardo Torrent (time to peak, surge duration, flow depth) and permitting comparison with other instrumented catchments. The dataset is made available to the public with the following DOI: https://doi.org/10.1594/PANGAEA.919707.

CFD Analysis on the Effects of Different Coal on Combustion Characteristics in Coal-fired Boiler

Coal quality is essential for the optimum functioning of coal-fired power plants. One of the issues associated with coal quality deterioration is poor combustion behaviour which could result in ash deposition and environmental issues. This paper presents a CFD investigation of flow and combustion process in a full-scale furnace. Three different sub-bituminous coals with different properties were tested namely Coal A, B and C. The aim is to predict the combustion performance of these coals by observing its flow, temperature and species concentration inside the furnace. The exact boiler furnace geometry obtained from boiler operator was translated into CFD model with very little modification made for optimizing mesh. Grid dependency test carried out prior to the work shows the current mesh scheme is sufficient to accurately resolve the flow field. The results of the study show that combustion temperature for Coal B is the highest at approximately 1400°C. Coal C is predicted to give the highest velocity peak at certain regions of the furnace and interestingly enough, the same coal shows the shortest flame length and thus requiring additional flow to achieve the same penetration compared to other coals. Tracing of oxygen concentration inside the furnace show minimum oxygen left in the rear pass given by Coal A, indicating optimum combustion.

Statistical deprojection of intervelocities, interdistances, and masses in the Isolated Galaxy Pair Catalog

Aims. In order to study the internal dynamics of actual galaxy pairs, we need to derive the probability distribution function (PDF) of true 3D, orbital intervelocities and interdistances between pair members from their observed projected values along with the pair masses from Kepler’s third law. For this research, we used 13 114 pairs from the Isolated Galaxy Pair Catalog (IGPC). Methods. The algorithms of statistical deprojection previously elaborated were applied to these observational data. We derived the orbital velocity PDFs for the whole catalog and for several selected subsamples. The interdistance PDF is deprojected and compared to the analytical profiles expected from semi-theoretical arguments. Results. The PDF of deprojected pair orbital velocities is characterized by the existence of a main probability peak around ≈150 km s−1 for all subsamples of the IGPC as well as for the Uppsala Galaxy Pair Catalog. The interdistance PDFs of both the projected and deprojected data are described at large distances by the same power law with exponent ≈ − 2. The whole distributions, including their cores, are fairly fitted by King profiles. The mass deprojection yields a mass/luminosity ratio for the pairs of M/L = (30 ± 5) in solar units. Conclusions. The orbital velocity probability peak is observed at the same value, ≈150 km s−1, as the main exoplanet velocity peak, which points toward a possible universality of Keplerian structures, whatever the scale. The pair M/L ratio is just seven times the standard ratio for luminous matter, which does not require the existence of nonbaryonic dark matter in these systems.

Debris flows recorded in the Moscardo catchment (Italian Alps) between 1990 and 2019

This paper presents debris-flows data recorded in the Moscardo Torrent (eastern Italian Alps) between 1990 and 2019. In this time interval, 30 debris flows were observed, 26 of them were monitored by sensors installed on the channel, while four were only documented through post-event observations. Monitored data consist of debris-flow hydrographs, measured utilizing ultrasonic sensors, and rainfall. Debris flows in the Moscardo Torrent occur from early June to the end of September, with higher frequency in the first part of summer. The paper presents data on triggering rainfall, flow velocity, peak discharge, and volume for the monitored hydrographs. Simplified triangular hydrographs and dimensionless hydrographs were derived to show the basic features of the debris flows in the Moscardo Torrent (time to peak, surge duration, flow depth) and permitting comparison with other instrumented catchments. The dataset is made available to the public with the following DOI: https://doi.pangaea.de/10.1594/PANGAEA.919707 .

Blasting-Induced Vibration Response of the Transition Section in a Branching-Out Tunnel and Vibration Control Measures

Blasting-induced vibration during the excavation of transition section in a branching-out tunnel causes damage and hence affects the safety and stability of the supporting structure and surrounding rock. To examine the effects of excavation and blasting of the transition section in the posterior tunnel on the supporting structures of the anterior tunnel, the influences of the blasting-induced vibration in the posterior tunnel on the anterior tunnel were analyzed under different surrounding rock levels, excavation techniques, distances from explosive source, and net spans. This method was performed by combining numerical simulation with blasting-induced vibration monitoring according to the construction characteristics of the transition section in a branching-out tunnel of a highway. A control technique was investigated to assure the safety and stability of the anterior tunnel during the excavation and blasting of the posterior tunnel. Results demonstrate that (1) the vibration velocity peak behind the blasting excavation surface of the tunnel is higher than that in front. These results suggest paying much attention in monitoring vibration velocity within 10 m behind the excavation surface. (2) The blasting-induced vibration velocity peak on the spandrel at the side that faces the blasting in the anterior tunnel is 2.0–2.5 times than that at the side behind the blasting. Moreover, the blasting-induced vibration velocity peak on the haunch at the side that faces the blasting in the anterior tunnel is 6-7 times than that at the side behind the blasting. (3) Instead of the full-face excavation method, the use of center cross diagram (CRD) technique or side wall pilot tunnel method is suggested for the excavation of surrounding rocks of IV-level, V-level, and III-level with a net span smaller than 3 m. (4) Vibration control measures, such as double wedge-shaped cut blasting and floor blast-hole staged detonation, were adopted by designing and optimizing blasting parameters (e.g., total explosives, maximal segment explosive quantity, detonation order, and detonation interval) in posterior tunnel. According to the test, the blasting-induced vibration velocity peak, which is monitored in the anterior tunnel, can be controlled within 10 cm/s to assure the safety and stability of the supporting structure and surrounding rocks of the tunnel.

Effect of object weight and experience on the organization of object management tasks in infants of 10 months of age

Introduction: Little is known about the real impact the practice of manipulating objects on the development of infants perception-action and it is assumed that this newly acquired knowledge is useful for planning future actions. Objective: To analyse the effects of controlled practice on the tasks of reaching and transporting objects in 10-month-old infants when the weight of the object was changed. Methods: Sixteen infants were divided into two groups: heavy/ light group (HLG) and light/heavy group (LHG). The task consisted in reaching, grasping, and lifting a lighter or heavier bar 9 times. On the tenth trial, the object weight was switched to the heavier or lighter weight object (whichever was opposite to the object weight experienced in the first 9 trials) to assess whether infants had learned and adapted their object-directed movement strength to the initial weight condition practiced during the first 9 trials. Results: No significant differences were found when comparing the reaching and lifting phases within groups (LHG, P = 0.06 and HLG, p = 0.41). However, group comparisons revealed that HLG infants presented increased velocity peak (p = 0.01) during the trials. Conclusion: The reaching and object lifting trials of the infants throughout the attempts were very variable, indicating that, possibly, at 10 months of age, infants present transitions from one organizational state to another. However, it is necessary to carry out more detailed investigations on reaching and lifting actions of objects to understand the processes involved in these transition periods.

Gas velocity structure of the Orion A integral-shaped filament

ABSTRACT We present analysis of the gas kinematics of the integral-shaped filament (ISF) in Orion A using four different molecular lines, 12CO (1−0), 13CO (1−0), NH3 (1,1), and N2H+ (1−0). We describe our method to visualize the position–velocity (PV) structure using the intensity-weighted line velocity centroid, which enables us to identify structures that were previously muddled or invisible. We observe a north-to-south velocity gradient in all tracers that terminates in a velocity peak near the centre of the Orion Nebula Cluster (ONC), consistent with the previously reported ‘wave-like’ properties of the ISF. We extract the velocity dispersion profiles and compare the non-thermal line widths to the gas gravitational potential. We find supersonic Mach number profiles, yet the line widths are consistent with the gas being deeply gravitationally bound. We report the presence of two 12CO velocity components along the northern half of the ISF; if interpreted as circular rotation, the angular velocity is $\omega =1.4\, {\rm Myr}^{-1}$. On small scales we report the detection of N2H+ and NH3 ‘twisting and turning’ structures, with short associated time-scales that give the impression of a torsional wave. Neither the nature of these structures nor their relation to the larger scale wave is presently understood.