Range Of Distances Research Articles

Flow and heat transfer characteristics of an impinging jet augmented with swirl

Jet impingement cooling techniques using conventional nozzles, round jets, and swirling jets are effective heat transfer methods extensively used for various industrial applications. This work proposes a geometrical mechanism that generates augmented swirling and round jets for enhanced heat transfer. The proposed geometry has an axial inlet port and three tangential inlet ports. The total flow is partitioned through these inlet ports using different split ratios (SR), resulting in a single augmented flow comprising swirling and round jets. The impingement heat transfer from a heated flat plate is modelled using steady 3-D RANS based numerical simulations. Also, computations for conventional round jets and swirling jets generated by an in-house developed vane-swirler are performed for the Reynolds number range of 6000–15,000, and for a range of jet-plate distance H = 1.5–4 times the jet diameter D. The optimum conditions for maximum heat transfer for various configurations of jets are presented. From this numerical study, the proposed augmented jet is found to enhance the impingement heat transfer rate at an optimal condition of split ratio (SR-4) and dimensionless jet-plate distance (H/D = 1.5) compared to conventional round jets as well as swirl jets generated by vane swirlers.

Locating Anchor Drilling Holes Based on Binocular Vision in Coal Mine Roadways

The implementation of roof bolt support within a coal mine roadway has the capacity to bolster the stability of the encompassing rock strata and thereby mitigate the potential for accidents. To enhance the automation of support operations, this paper introduces a binocular vision positioning method for drilling holes, which relies on the adaptive adjustment of parameters. Through the establishment of a predictive model, the correlation between the radius of the target circular hole in the image and the shooting distance is ascertained. Based on the structural model of the anchor drilling robot and the related sensing data, the shooting distance range is defined. Exploiting the geometric constraints inherent to adjacent anchor holes, the precise identification of anchor holes is detected by a Hough transformer with an adaptive parameter-adjusted method. On this basis, the matching of the anchor hole contour is realized by using linear slope and geometric constraints, and the spatial coordinates of the anchor hole center in the camera coordinate system are determined based on the binocular vision positioning principle. The outcomes of the experiments reveal that the method attains a positioning accuracy of 95.2%, with an absolute error of around 1.52 mm. When compared with manual operation, this technique distinctly enhances drilling accuracy and augments support efficiency.

Analysis of Automated Emergency Braking System to Investigate Forward Collision Condition Using Scenario-Based Virtual Assessment

In the recent trend of automotive technologies, active safety systems for vehicles have become one of the key elements to reduce road traffic conditions. Automated vehicles are known as one of the active safety systems to minimize road traffic congestion and unwanted road hazardous situations. Generally, automated vehicles are designed using advanced driving assistance system (ADAS) technology to enhance the safety capability of the vehicles. Moreover, automated vehicles are designed to adopt multiple scenarios with different types of traffic situations. Generally, the performance of automated vehicles is evaluated to adapt with various road conditions and different type of traffic conditions, autonomously. Nonetheless, most of the safety testing was conducted in a controlled environment and with less traffic conditions. Moreover, this technology is tested in developed countries and mostly evaluated for highway driving scenarios, with less pedestrians and motorist’s road users. On the other hand, in developing countries such as Malaysia, most of the automotive researchers have initiated research related to automated vehicle based on controlled environment only. One of the primary focuses for the current automotive researchers is to reduce road accidents due to frontal collision. Thus, automated emergency braking systems have been heavily investigated by most developers to minimize road accidents. Most of the researchers analyze the system in terms of theoretical based simulation and tested using actual vehicle for physical testing. However, this type of testing is not sufficient to optimize the performance of automatedemergency braking systems for developing countries. Therefore, this study focuses on scenario-based virtual assessment to evaluate the capability of autonomous vehicles using automated emergency braking system without causing road casualties with the distance range is 4.5m to 0.5m depending on vehicle speed.

Analysis of Peak Ground Acceleration Attenuation Characteristics in the Pazarcik Earthquake, Türkiye

This study collected acceleration records and station reports from 379 strong-motion stations triggered by the Mw7.7 earthquake in Pazarcik, Türkiye, on 6 February 2023. A total of 451 horizontal and 194 vertical strong-motion acceleration records with complete waveforms and reasonable data were selected to establish appropriate equations for predicting seismic parameters. Two iterative algorithms, specifically the optimization algorithm and orthogonal distance regression, were employed to formulate prediction equations for PGA and EPA in the NS (north–south), EW (east–west), and vertical directions. Furthermore, a comparative analysis of the attenuation curves for PGA and EPA was conducted within the vertical and horizontal directions. The results indicated that the observed and predicted values of vertical PGA and EPA at the same fault distance were approximately 0.577–0.673 times those of horizontal PGA and EPA. The ratio range calculated in our study aligns closely with previous research results, slightly more than 2/3 only in the vicinity of fault zones. The analysis demonstrated that the horizontal PGA value of the soil site at the same fault distance was approximately 1.46 times that of the bedrock site, while the vertical PGA value was only 1.12 times. The comparison of attenuation relationships revealed that within the fault distance range of 20 km to 100 km, the horizontal PGA of the Wenchuan earthquake was approximately 1.26–2.16 times that of the Pazarcik earthquake, and the ratio increased with an increasing fault distance.

Impact of task constraints on a 3D visuomotor tracking task in virtual reality

Objective: The aim of the present study was to evaluate the impact of different task constraints on the participants’ adaptation when performing a 3D visuomotor tracking task in a virtual environment.Methods: Twenty-three voluntary participants were tested with the HTC Vive Pro Eye VR headset in a task that consisted of tracking a virtual target moving in a cube with an effector controlled with the preferred hand. Participants had to perform 120 trials according to three task constraints (i.e., gain, size, and speed), each performed according to four randomized conditions. The target-effector distance and elbow range of movement were measured.Results: The results showed an increase in the distance to the target when the task constraints were the strongest. In addition, a change in movement kinematics was observed, involving an increase in elbow amplitude as task constraints increased. It also appeared that the depth dimension played a major role in task difficulty and elbow amplitude and coupling in the tracking task.Conclusion: This research is an essential step towards characterizing interactions with a 3D virtual environment and showing how virtual constraints can facilitate arm’s involvement in the depth dimension.

Combination of arthroscopic biologic tuberoplasty and bursal acromial reconstruction

BackgroundRecently, among the various method for irreparable rotator cuff tears, the “tension-free allodermis graft technique” has been introduced as a method for arthroscopic biologic tuberoplasty(ABT) and bursal acromial reconstruction(BAR).The objective was to analyze the outcomes of ABT and BAR combination surgical technique. MethodsEighteen cases who underwent simultaneous ABT and BAR procedures were retrospectively recruited. Before the surgery and at one year post-surgery, the researchers assessed the patients' Visual Analog Scale(VAS), American Shoulder and Elbow Surgeons(ASES) scores, pain scores, range of motion(ROM), retear, and acromiohumeral distance (AHD). ResultsOne year post-surgery, both the VAS pain scores, ASES scores, and ROM showed statistically significant improvement compared to before the surgery. Upon reviewing the radiological results, the AHD significantly improved from 4.3 ± 4.1 mm before surgery to 9.2 ± 1.9 mm at one year post-surgery (p < 0.001). Moreover, in the one year follow-up, there was no observed failure of the allodermis graft in any of the cases. ConclusionThe combination of ABT and BAR demonstrated significantly improved clinical outcomes after surgery, showing a substantial increase in AHD and preventing graft failure effectively.

A Feasibility Study on Extension of Measurement Distance in Vision Sensor Using Super-Resolution for Dynamic Response Measurement.

The current civil infrastructure conditions can be assessed through the measurement of displacement using conventional contact-type sensors. To address the disadvantages of traditional sensors, vision-based sensor measurement systems have been derived in numerous studies and proven as an alternative to traditional sensors. Despite the benefits of the vision sensor, it is well known that the accuracy of the vision-based displacement measurement is largely dependent on the camera extrinsic or intrinsic parameters. In this study, the feasibility study of a deep learning-based single image super-resolution (SISR) technique in a vision-based sensor system is conducted to alleviate the low spatial resolution of image frames at long measurement distance ranges. Additionally, its robustness is evaluated using shaking table tests. As a result, it is confirmed that the SISR can reconstruct definite images of natural targets resulting in an extension of the measurement distance range. Additionally, it is determined that the SISR mitigates displacement measurement error in the vision sensor-based measurement system. Based on this fundamental study of SISR in the feature point-based measurement system, further analysis such as modal analysis, damage detection, and so forth should be continued in order to explore the functionality of SR images by applying low-resolution displacement measurement footage.

The key determinant for forming pollen density and using crop barriers to mitigate wind-blown pollen dispersal in alfalfa (Medicago sativa L.)

The potential for commercial cultivation of genetically engineered (GE) alfalfa has raised ecological concerns due to the possibility of introgression of GE alleles into conventional populations. The main objectives of this study were to determine the key affecting factors (i.e. size of pollen source, number of pollinating bees) on forming alfalfa pollen cloud density and test the mitigating effect using maize barrier rows on alfalfa pollen dispersal. The results showed that the mean pollen densities of alfalfa pollen source (Ø = 10 or 20 m) were statistically similar when treated with the same number of worker bumblebees and increased accordingly with increasing the worker bees (887 and 853 pollens m−3 h−1 for Ø = 10 and 20 m with 100–150 worker bees, respectively; 1040 and 1070 pollens m−3 h−1 for the two plots with 200–300 worker bees, respectively), demonstrating that the number of worker bees but not the size of the pollen source was the key determinant for forming alfalfa pollen density. A maize barrier row established at 0.5 m from the alfalfa edge consistently decreased downwind pollen densities (percent pollen density of pollen source) to 0.2–4.4 % at 1–9 m compared to 3.4–25.4 % and 7.5–37.8 % at the same distance range for the upwind and downwind sites without maize barrier rows, respectively. Based on the pods formed on the emasculated alfalfa flowers (due to pollen dispersal) located at various distances from the pollen source and subsequent prediction model, the pollen density threshold value for fertilizing alfalfa recipient under the wind-blown condition was determined of 65.8 pollens m−3 h−1 at 14.7 m from the pollen source edge. The results would help in understanding the pollination biology (minimum pollen density for fertilizing alfalfa recipient ovule) and the process of pollen-mediated gene flow and helpful in developing management strategies to reduce the pollen density and thus mitigate the gene flow in alfalfa.

Aging increases proprioceptive error for a broad range of movement speed and distance estimates in the upper limb.

Previous work has identified age-related declines in proprioception within a narrow range of limb movements. It is unclear whether these declines are consistent across a broad range of movement characteristics that more closely represent daily living. Here we aim to characterize upper limb error in younger and older adults across a range of movement speeds and distances. The objective of this study was to determine how proprioceptive matching accuracy changes as a function of movement speed and distance, as well as understand the effects of aging on these accuracies. We used an upper limb robotic test of proprioception to vary the speed and distance of movement in two groups: younger (n = 20, 24.25 ± 3.34 years) and older adults (n = 21, 63 ± 10.74 years). The robot moved one arm and the participant was instructed to mirror-match the movement with their opposite arm. Participants matched seven different movement speeds (0.1-0.4 m/s) and five distances (7.5-17.5 cm) over 350 trials. Spatial (e.g., End Point Error) and temporal (e.g., Peak Speed Ratio) outcomes were used to quantify proprioceptive accuracy. Regardless of the speed or distance of movement, we found that older controls had significantly reduced proprioceptive matching accuracy compared to younger control participants (p ≤ 0.05). When movement speed was varied, we observed that errors in proprioceptive matching estimates of spatial and temporal measures were significantly higher for older adults for all but the slowest tested speed (0.1 m/s) for the majority of parameters. When movement distance was varied, we observed that errors in proprioceptive matching estimates were significantly higher for all distances, except for the longest distance (17.5 cm) for older adults compared to younger adults. We found that the magnitude of proprioceptive matching errors was dependent on the characteristics of the reference movement, and that these errors scaled increasingly with age. Our results suggest that aging significantly negatively impacts proprioceptive matching accuracy and that proprioceptive matching errors made by both groups lies along a continuum that depends on movement characteristics and that these errors are amplified due to the typical aging process.

Regional spectral characteristics, quality factor and site responses in western-central Sichuan, China (II): Application to stochastic ground motion simulation

The stochastic finite-fault approach was used to model the 2022 Luding earthquake with a magnitude of Mw 6.6 in China at 16 selected near-field stations. To investigate the impact of the site effect on the synthetic results, two models were taken into account: One model was obtained from the generalized inversion technique, and the other model was obtained from the horizontal-to-vertical spectral ratio method. The high-frequency attenuation parameter was estimated to be 0.040 s and the value of 4.0 MPa for the stress parameter was adopted. Comparisons of the recorded and simulated Fourier amplitude spectrum, pseudospectral acceleration, peak ground acceleration, and peak ground velocity were performed to investigate the capability of the selected input parameters. In addition, the model bias, simulated peak ground acceleration and peak ground velocity were calculated by the local site amplification estimated by the two methods. The results show that the site effects estimated by the generalized inversion technique can well simulate the high-frequency response spectra and Fourier amplitude spectrum and can provide peak ground acceleration and peak ground velocity values consistent with the recorded values, while the local site amplification roughly calculated by the horizontal-to-vertical ratio method underestimates the main ground motion characteristics. Furthermore, strong-motion records with the same magnitude but different hypocentral distance ranges in the generalized inversion technique are used to estimate near-surface site effects, which shows that the distance range has a small impact on the estimation of local site amplification. Model parameters that performed well in this study provide confidence in understanding and quantifying seismic hazards in the Luding area from earthquake scenarios with different magnitudes.

Vibration Response of Soil under Low-Frequency Vibration Using the Discrete Element Method

The vibration response of soil is a key property in the field of agricultural soil tillage. Vibration components of tillage machinery are generally used to reduce tillage resistance and improve work efficiency, and the pressure variation under low-frequency vibration will affect the fragmentation and dispersion of farmland soil. However, the gradient of pressure variation, frequency domain response, and effective transmission range is unclear. A new method based on the DEM (discrete element method) is presented to study the vibration response and pressure transmission under low-frequency vibration. Bench test results have shown that peak pressure positively correlates with the vibration frequency and attenuates rapidly at a vibration distance of 100 to 250 mm. The resulting data were also selected to determine the simulation model’s parameters. Amplitude, vibration frequency, and soil depth were used as test factors in single-factor simulation tests, and their effects on the peak pressure, frequency domain response, and effective transmission distance were analyzed. The results showed a positive relationship between the peak pressure and the test factors. The peak pressure increased with a maximum gradient of 19.02 kPa/mm at a vibration distance of 50 mm. The amplitude, vibration frequency, and soil depth positively correlated with the dominant frequency amplitude. The main frequency was independent of amplitude and soil depth. At a vibration distance of 250 mm, the dominant frequency was approximately twice the vibration frequency at 7–11 Hz and approximately equal to the vibration frequency at 13–15 Hz. Multiple exponential functions were used to fit the peak pressure attenuation function, obtaining an effective transmission distance range of 347.15 to 550.37 mm for the 5 kPa cut-off pressure. For a soil depth of 300 mm, the vertical shear wave diffusion angle was greater than the horizontal shear wave diffusion angle. This study clarifies the vibration response of soil under low-frequency vibration, which helps to design vibration-type, soil-engaging components of tillage machinery and match vibration parameters for energy-saving and resistance reduction purposes in soil tillage.

Quasi-experimental study finding no localised gun crime or call reduction after gun buybacks in Philadelphia

IntroductionGun buyback programmes have been popular in the USA since the 1970s. Studies show that they have no effect on citywide gun crime rates, but more microlevel examinations around gun...

Small-size LD-based automobile headlamp design with long illumination distance and wide illumination range.

Due to the large size of an automobile headlamp that has a laser as the light source, it is difficult to reflect the advantages of high laser brightness into the effect of automobile illumination, so it has not been promoted. We propose a laser headlamp system that integrates low-beam and high-beam structures with superior illumination effects (longer illumination distance and wider illumination range) by designing freeform optical components and optical structure. The small-volume headlamp can meet the requirements of the Economic Commission for Europe regulation (ECE) R112. The structure volume of the headlamp proposed in this study is only 100∗70∗70m m 3, and the maximum luminance is 120lx (simulation result) and 78.5lx (test result). The view angle of the low beam is 13.6°, and the high beam is 15.6°, indicating that the solution is suitable for automotive illumination.

A recurrent neural network model for structural response to underwater shock

Simulating the dynamic response of structures to shock involves numerical models that can require significant effort and computational resources to create and solve. This can make accurate naval platform vulnerability analyses involving a large number of simulations impractical and motivates the development of efficient surrogate models for shock and blast effects. This paper presents a novel approach to predicting the response of a floating structure to underwater shock based on machine learning (ML). Velocity time-series for a rigid floating plate subjected to underwater shock and cavitation effects are calculated for a range of charge mass, standoff distance and plate mass per unit area values using a coupled Eulerian–Lagrangian (CEL) numerical model. The computed motions are used to train a recurrent neural network (RNN) to predict the plate response including the effect of reloading due to the cavitation closure pulse. The RNN predicts plate responses from a test set of CEL model instances with a mean value of mean-squared errors between the ML and CEL model velocities, normalized with respect to the velocity ranges, of 1.5 × 10-4.

A system of FRET dyes designed to assess the degree of nano-scale contact between surfaces for interfacial adhesion

HypothesisInterfacial adhesion caused by intermolecular forces only occur between surfaces at nano-scale contact (NSC), i.e., 0.1–0.4 nm and can be evaluated using Forster resonance energy transfer spectroscopy (FRET). For this, a suitable pair of fluorescent dyes must be selected, which spectroscopic properties will determine the FRET system performance. Here, we present a brand-new FRET dye system specifically designed to measure NSC in the distance range relevant for van-der-Waals and hydrogen bonding, i.e., below 1 nm. ExperimentsWe propose the FRET pair: 7-Amino-4-methyl-cumarin (C120) and 5(6)-Carboxy-2′,7′-dichlor-fluorescein (CDCF) with high quantum yield (QY, QYC120 = 0.91 and QYCDCF = 0.64) and a distance detection range of 0.6–2.2 nm (0.1 mM). Adhered-thin films with increasing NSC degrees are produced with ascending pressure from 1.5 to 150 bar. To validate the proposed FRET measurement, we are correlating the bonded films interfacial adhesion (separation energy) to the measured FRET intensity, indicating its degree of NSC. FindingsWe find that the proposed dyes are producing the desired FRET signal in adhered-thin films, for an interaction range of 0.6–2.2 nm, with high sensitivity due to the dye’s high quantum yields. The increasing adhesion in these films is only caused by its increase in NSC. We find that the adhesion strength, measured as the separation energy between the films, is correlated to the measured FRET signal. Hence, the introduced FRET system is accurately able to measure the degree of NSC between soft surfaces.

The relationship between freight and passenger train noise levels and distance on the Sydney Metropolitan Rail Network across 281 measurement sites

Transport for NSW undertakes noise monitoring at a range of distances and locations around the NSW Government-managed rail network. The monitoring quantifies noise levels from freight and passenger train operations and informs delivery of noise reduction programs including the Transport for NSW’s Freight Noise Attenuation Program, which was launched in 2015. Comprehensive noise monitoring over a typical period of two weeks has been undertaken at 281 representative locations adjacent the passenger and freight rail network around Sydney. Results were analyzed to determine the LAE noise levels from each freight and passenger train passby, and the average weekday LAeq(15hour) daytime and LAeq(9hour) night-time levels. Curves of best fit are presented that illustrate the relationship between freight and passenger train noise levels and the distance to the near track. These curves of best fit can be utilised by Government agencies and acoustic practitioners to quantify the potential noise impact of freight and passenger train operations at a range of distances and locations close to the NSW Government-managed rail network and identify appropriate noise mitigation measures.

The measurement of responsivity of infrared photodetectors using a cavity blackbody

For the measurement of responsivity of an infrared photodetector, the most-used radiation source is a blackbody. In such a measurement system, distance between the blackbody, the photodetector and the aperture diameter are two parameters that contribute most measurement errors. In this work, we describe the configuration of our responsivity measurement system in great detail and present a method to calibrate the distance and aperture diameter. The core of this calibration method is to transfer direct measurements of these two parameters into an extraction procedure by fitting the experiment data to the calculated results. The calibration method is proved experimentally with a commercially extended InGaAs detector at a wide range of blackbody temperature, aperture diameter and distance. Then proof procedures are further extended into a detector fabricated in our laboratory and consistent results were obtained.

Turbulence Properties of Interplanetary Coronal Mass Ejections in the Inner Heliosphere: Dependence on Proton Beta and Flux Rope Structure

Interplanetary coronal mass ejections (ICMEs) have low proton beta across a broad range of heliocentric distances and a magnetic flux rope structure at large scales, making them a unique environment for studying solar wind fluctuations. Power spectra of magnetic field fluctuations in 28 ICMEs observed between 0.25 and 0.95 au by Solar Orbiter and Parker Solar Probe have been examined. At large scales, the spectra were dominated by power contained in the flux ropes. Subtraction of the background flux rope fields increased the mean spectral index from −5/3 to −3/2 at kd i ≤ 10−3. Rope subtraction also revealed shorter correlation lengths in the magnetic field. The spectral index was typically near −5/3 in the inertial range at all radial distances regardless of rope subtraction and steepened to values consistently below −3 with transition to kinetic scales. The high-frequency break point terminating the inertial range evolved approximately linearly with radial distance and was closer in scale to the proton inertial length than the proton gyroscale, as expected for plasma at low proton beta. Magnetic compressibility at inertial scales did not show any significant correlation with radial distance, in contrast to the solar wind generally. In ICMEs, the distinctive spectral properties at injection scales appear mostly determined by the global flux rope structure while transition-kinetic properties are more influenced by the low proton beta; the intervening inertial range appears independent of both ICME features, indicative of a system-independent scaling of the turbulence.

A Systematic Observational Study on Galactic Interstellar Ratio 18O/17O. II. C18O and C17O J = 2–1 Data Analysis

To investigate the relative amount of ejecta from high-mass versus intermediate-mass stars and to trace the chemical evolution of the Galaxy, we have performed a systematic study of Galactic interstellar 18O/17O ratios toward a sample of 421 molecular clouds with IRAM 30 m and the 10 m Submillimeter Telescope, covering a galactocentric distance range of ∼1–22 kpc. The results presented in this paper are based on the J = 2–1 transition and encompass 364 sources showing both C18O and C17O detections. The previously suggested 18O/17O gradient is confirmed. For the 41 sources detected with both facilities, good agreement is obtained. A correlation of the 18O/17O ratios with heliocentric distance is not found, indicating that beam dilution and linear beam sizes are not relevant. For the subsample of IRAM 30 m high-mass star-forming regions with accurate parallax distances, an unweighted fit gives 18O/17O = (0.12 ± 0.02)R GC + (2.38 ± 0.13) with a correlation coefficient of R = 0.67. While the slope is consistent with our J = 1–0 measurement, the ratios are systematically lower. This should be caused by larger optical depths of C18O 2–1 lines with respect to the corresponding 1–0 transitions, which is supported by RADEX calculations and the fact that C18O/C17O is positively correlated with 13CO/C18O. When we consider that optical depth effects with C18O J = 2–1 typically reach an optical depth of ∼0.5, the corrected 18O/17O ratios from the J = 1–0 and J = 2–1 lines are consistent. A good numerical fit to the data is provided by the MWG-12 model, which includes both rotating stars and novae.

Assessment and Mechanism Analysis of Forest Protection against Rockfall in a Large Rock Avalanche Area

Trees in forests can obstruct falling rocks and serve as a natural barrier to reduce the velocity of falling rocks. Recently, there has been growing interest in utilizing forests to safeguard against potential rockfall. Nevertheless, there is a dearth of research regarding the impact of rock size and forest structure on forest preservation against rockfall. This study takes the Jiweishan rock avalanche that occurred in China in June 2009 as an example to discuss the protection mechanism of forests against rockfall in rock avalanche disasters. Three sizes of rockfalls from the Jiweishan rock avalanche were simulated and analyzed with and without forests using Rockyfor3D software. The findings indicate that forests can mitigate the energy impact of falling rocks. Especially in the debris flow area of rock avalanches, the protective effect of trees on small-sized falling rocks is most obvious, reducing the runout distance and damage range of the debris flow. Moreover, the protective effect of forest structures on rockfall risk was explored. It was found that broad-leaved forests had the best protection against falling rocks, followed by coniferous broad-leaved mixed forests, and coniferous forests had the worst protective effect. Furthermore, increasing forest planting density and tree diameter at breast height (DBH) can result in better protection against rockfall. Thus, rational planning of forest species and planting density in areas of rockfall can effectively reduce the threat of rockfall risk. The research ideas in this study can provide a basis for evaluating the mitigation of rockfall hazards by forests and provide a reference for constructing and planning protective forests in rockfall and rock avalanche hazard areas.