Observation of the Velocity Variation of an Explosively-Driven Flat Flyer Depending on the Flyer Width

Lim proposed a theoretical study on the velocity profile of an explosively-driven flat flyer affected by the rarefaction (or release wave) intrusion during the metal’s projection. This work shows somewhat reasonable agreement in a given range. However, this work is limited only in the early stage of detonation (~3 µs), and the larger scaled flyer projection (or extended time duration) behavior is needed for an engineering perspective. As continued work originating from this investigation, the velocity profile of explosively-driven flyers with different widths is studied based on multiple different approaches which include hydrocode simulation, the Gurney model, and Baum’s side loss correction (or effective charge mass approach), followed by a series of field experiments. In this study, the focus is on the observation of the flat flyer velocity (or terminal velocity) variation, depending on the width of the flyers which vary from 12, 25, 50, and 75 mm (or 100 mm). The terminal velocity profile variation, depending on the flyer width, is observed, and a general trend is identified.

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Tephra4D: A Python-Based Model for High-Resolution Tephra Transport and Deposition Simulations—Applications at Sakurajima Volcano, Japan

Atmosphere ◽

10.3390/atmos12030331 ◽

2021 ◽

Vol 12 (3) ◽

pp. 331

Author(s):

Kosei Takishita ◽

Alexandros P. Poulidis ◽

Masato Iguchi

Keyword(s):

Scale Effects ◽

Three Dimensional ◽

Particle Diameter ◽

Terminal Velocity ◽

Diameter Distribution ◽

Velocity Variation ◽

Small Scale ◽

Modified Model ◽

Sakurajima Volcano ◽

Ash Transport

Vulcanian eruptions (short-lived explosions consisting of a rising thermal) occur daily in volcanoes around the world. Such small-scale eruptions represent a challenge in numerical modeling due to local-scale effects, such as the volcano’s topography impact on atmospheric circulation and near-vent plume dynamics, that need to be accounted for. In an effort to improve the applicability of Tephra2, a commonly-used advection-diffusion model, in the case of vulcanian eruptions, a number of key modifications were carried out: (i) the ability to solve the equations over bending plume, (ii) temporally-evolving three-dimensional meteorological fields, (iii) the replacement of the particle diameter distribution with observed particle terminal velocity distribution which provides a simple way to account for the settling velocity variation due to particle shape and density. We verified the advantage of our modified model (Tephra4D) in the tephra dispersion from vulcanian eruptions by comparing the calculations and disdrometer observations of tephra sedimentation from four eruptions at Sakurajima volcano, Japan. The simulations of the eruptions show that Tephra4D is useful for eruptions in which small-scale movement contributes significantly to ash transport mainly due to the consideration for orographic winds in advection.

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Growth responses of Leymus chinensis (Trin.) Tzvelev to sheep saliva after defoliation

The Rangeland Journal ◽

10.1071/rj09061 ◽

2010 ◽

Vol 32 (4) ◽

pp. 419 ◽

Cited By ~ 5

Author(s):

Xing Teng ◽

Lei Ba ◽

Deli Wang ◽

Ling Wang ◽

Jushan Liu

Keyword(s):

Plant Growth ◽

Aboveground Biomass ◽

Field Experiments ◽

Perennial Grass ◽

Leaf Length ◽

Leymus Chinensis ◽

Growth Responses ◽

Time Duration ◽

Positive Effects ◽

Leaf Weight

Many studies indicated that saliva from herbivores might be involved in plant growth responses when plants have been grazed. However, there is currently no general agreement on whether saliva can affect plant growth. Our aims were to determine the growth response of plants to sheep saliva after defoliation under diverse environmental conditions (different sward structures), and whether the effect of saliva is influenced by time (duration) after its application. We conducted field experiments with clipping treatments and the application of sheep saliva to the damaged parts of tillers to simulate sheep grazing on the perennial grass Leymus chinensis (Trin.) Tzvelev during the early growing seasons. Results demonstrated that clipping with saliva application significantly increased tiller numbers 8 weeks after treatments in comparison with clipping alone. A key finding is that the effect of sheep saliva on plant growth was short-lived. Clipping with saliva application increased leaf weight in the second week, while clipping alone had no effect. Moreover, clipping with saliva application promoted the elongation of new leaves (not the old ones) in the first week whereas clipping alone was ineffective. Results also showed that there were no differences between clipping with saliva application and clipping alone for relative height growth rate and aboveground biomass. Therefore, we concluded that saliva application to clipping treatment would produce an additional effect compared to clipping alone for the plant and the positive effects are time dependent. The additional effects primarily embodied in the individual level of plant, such as the changes of leaf weight and leaf length. Beyond the level, the effects of saliva only produced many more tiller numbers rather than the accumulation of aboveground biomass.

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Incorporating biomarkers in ecological risk assessment of chemical contaminants of soils

Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie ◽

10.4102/satnt.v26i2.129 ◽

2007 ◽

Vol 26 (2) ◽

pp. 120-137

Author(s):

A. J. Reinecke ◽

S. A. Reinecke ◽

M. S. Maboeta ◽

J. P. Odendaal ◽

R. Snyman

Keyword(s):

Risk Assessment ◽

South African ◽

Field Experiments ◽

Early Stage ◽

Population Level ◽

Diagnostic Tools ◽

Future Research ◽

Chemical Contaminants ◽

Toxic Response ◽

Future Research Directions

Soil is an important but complex natural resource which is increasingly used as sink for chemicals. The monitoring of soil quality and the assessment of risks posed by contaminants have become crucial. This study deals with the potential use of biomarkers in the monitoring of soils and the assessment of risk resulting from contamination. Apart from an overview of the existing literature on biomarkers, the results of various of our field experiments in South African soils are discussed. Biomarkers may have potential in the assessment of risk because they can indicate at an early stage that exposure has taken place and that a toxic response has been initiated. It is therefore expected that early biomarkers will play an increasing role as diagnostic tools for determining exposure to chemicals and the resulting effects. They may have predictive value that can assist in the prevention or minimising of risks. The aim of this study was to investigate the possibilities of using our results on biomarker responses of soil dwelling organisms to predict changes at higher organisational levels (which may have ecological implications). Our recent experimental results on the evaluation of various biomarkers in both the laboratory and the field are interpreted and placed in perspective within the broader framework of response biology. The aim was further to contribute to the development and application of biomarkers in regulatory risk assessment schemes of soils. This critical review of our own and recent literature on biomarkers in ecotoxicology leads to the conclusion that biomarkers can, under certain conditions, be useful tools in risk assessment. Clear relationships between contamination loads in soil organisms and certain biomarker responses were determined in woodlice, earthworms and terrestrial snails. Clear correlations were also established in field experiments between biomarker responses and changes at the population level. This indicated that, in spite of the fact that direct mechanistic links are still not clarified, biomarkers may have the potential to provide early indications of forthcoming changes at higher organisational levels. Ways are proposed in which biomarkers could be used in the future in risk assessment schemes of soils and future research directions are suggested.

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Transient Dynamics Measurement of Light-material Interaction for Laser Optics

EPJ Web of Conferences ◽

10.1051/epjconf/201921503005 ◽

2019 ◽

Vol 215 ◽

pp. 03005

Author(s):

Zhichao Liu ◽

Feng Geng ◽

Yaguo Li ◽

Qinghua Zhang ◽

Jian Wang ◽

...

Keyword(s):

Physical Mechanism ◽

Early Stage ◽

Laser Damage ◽

Time Duration ◽

Optical Elements ◽

Time Resolved ◽

Nanosecond Pulsed Laser ◽

Laser Induced Damage ◽

Light Material ◽

Physical Quantities

Laser damage performance is an important parameter to evaluate the quality of high power laser optical components. Understanding the physical mechanism of the interaction between laser and optical material is of great significance for improving the laser damage resistance of optical elements. For nanosecond pulsed laser, the time duration of laser-induced damage is ultra-short, and the measurement of related physical quantities is very difficult. Therefore, the Time Resolved Pump and Probe (TRPP) technique can effectively solve this problem. TRPP shadow imaging can obtain the transient dynamic information in range of picosecond to microsecond, including the plasma formation in the early stage, the shock wave propagation, the crack expanding, material ejection and other phenomena. Moreover, the ultra-fast physical quantities can be accurately measured by employing two detective beams with perpendicular polarization directions, for example S and P polarization light. All those information provides effective experimental data to reveal the physical mechanism of damage process.

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Diffusive mixing through velocity profile variation in microchannels

Experiments in Fluids ◽

10.1007/s00348-010-0954-5 ◽

2010 ◽

Vol 50 (3) ◽

pp. 535-545 ◽

Cited By ~ 8

Author(s):

Ehsan Yakhshi-Tafti ◽

Hyoung J. Cho ◽

Ranganathan Kumar

Keyword(s):

Velocity Profile ◽

Profile Variation ◽

Diffusive Mixing

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Dormancy in peach (Prunus persica) flower buds. VI. Effects of gibberellins and an acylcyclohexanedione (trinexapac-ethyl) on bud morphogenesis in field experiments with orchard trees and on cuttings

Canadian Journal of Botany ◽

10.1139/b02-051 ◽

2002 ◽

Vol 80 (6) ◽

pp. 664-674 ◽

Cited By ~ 13

Author(s):

Herminda Reinoso ◽

Virginia Luna ◽

Carlos Dauría ◽

Richard P Pharis ◽

Rubén Bottini

Keyword(s):

Field Experiments ◽

Prunus Persica ◽

Developmental Stages ◽

Early Stage ◽

Competitive Inhibitor ◽

Flower Bud ◽

Bud Development ◽

Morphological Alterations ◽

Floral Bud ◽

Ga Biosynthesis

The effects of several gibberellins (GAs), exo-16,17-dihydro GA5, 2,2-dimethyl GA4, and GA3, and trinexapac-ethyl (an acylcyclohexanedione inhibitor of late-stage GA biosynthesis), were assessed for their effects on flower bud development during and after winter dormancy in peach (Prunus persica (L.) Batsch.) in three field trials and one experiment using cuttings. At late developmental stages, GA3 hastened floral bud development and shortened the time to anthesis, whereas early-stage applications of GA3 either had no effect or delayed floral bud development. In contrast, an exceptionally growth-active GA, 2,2-dimethyl GA4, promoted floral bud development (tested only on cuttings) across a range of application dates. However, it also induced a high percentage of bud abscission and remaining buds had a necrotic gynoecium and alterations in the androecium. Surprisingly, trinexapac-ethyl also promoted floral bud development, although it was not as effective as GA1. Trinexapac-ethyl-treated buds also showed morphological alterations and gynoecium necrosis. However, the best and most consistent treatment for enhancing floral bud development and hastening flower anthesis was 16,17-dihydro GA5. It stimulated floral bud development in up to 80% of the treated buds. Further, the promotive effect of 16,17-dihydro GA5 was maintained through to anthesis across three years of field experiments on intact trees, as well as with cuttings. Whether 16,17-dihydro GA5, a competitive inhibitor of the 3β-hydroxylation step in GA biosynthesis, acts per se, acts via a metabolite (such as 16,17-dihydro GA3), or acts by modifying endogenous GA metabolism is not yet known.Key words: gibberellins, trinexapac-ethyl, floral bud morphogenesis, peach.

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Study on the Calculation Method of the Diffusion Range of Grouting Slurry for a High-speed Railway Ballastless Track Subgrade

Advances in Civil Engineering ◽

10.1155/2021/5279479 ◽

2021 ◽

Vol 2021 ◽

pp. 1-8

Author(s):

Changwei Yang ◽

Jinhao Guo ◽

Shaowei Wei ◽

Liang Zhang ◽

Sifeng Li ◽

...

Keyword(s):

High Speed ◽

Theoretical Study ◽

Early Stage ◽

Soil Mass ◽

High Speed Railway ◽

Grouting Pressure ◽

Diffusion Curve ◽

Practical Engineering ◽

Simulation Results ◽

Diffusion Form

Grouting engineering is the most convenient and quick way to deal with postconstruction settlement. Based on the investigation of the Beijing Shenyang high-speed railway in the early stage, the microdestructive force of grout on the soil mass in the process of grouting with the method of fluid solid coupling theory was analyzed. The numerical simulation results show that, in the grouting process, the greater the grouting pressure, the wider the diffusion range of the slurry and the greater the damage to the microscopic contact force of the slurry to the soil; in addition, when the grouting pressure is below 0.15 MPa, the diffusion form of the slurry in the soil is osmotic grouting; when the pressure is about 0.3 MPa, the diffusion form of the slurry in the soil is compacted grouting; on the basis of the simulation results, a deeper research is carried out, and the calculation formula of the slurry diffusion curve is obtained. It fills in the blank of the theoretical study of the slurry diffusion curve. In this paper, the diffusion formula of grouting slurry can be used in the theoretical study of clay grouting, and it can be used as a reference for practical engineering.

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Time-series Multi-spectral Imaging in Soybean for Improving Biomass and Genomic Prediction Accuracy

10.1101/2021.09.30.462675 ◽

2021 ◽

Author(s):

Kengo Sakurai ◽

Yusuke Toda ◽

Hiromi Kajiya-Kanegae ◽

Yoshihiro Ohmori ◽

Yuji Yamasaki ◽

...

Keyword(s):

Genomic Prediction ◽

Prediction Accuracy ◽

Field Experiments ◽

Developmental Stages ◽

Early Stage ◽

Vegetation Indices ◽

Optimal Timing ◽

Growth Stages ◽

Ms Imaging ◽

Irrigation Levels

Multi-spectral (MS) imaging enables the measurement of characteristics important for increasing the prediction accuracy of genotypic and phenotypic values for yield-related traits. In this study, we evaluated the potential application of temporal MS imaging for the prediction of above-ground biomass (AGB) and determined which developmental stages should be used for accurate prediction in soybean. Field experiments with 198 accessions of soybean were conducted with four different irrigation levels. Five vegetation indices (VIs) were calculated using MS images from soybean canopies from early to late growth stages. To predict the genotypic values of AGB, VIs at the different growth stages were used as secondary traits in a multi-trait genomic prediction. The accuracy of the prediction model increased starting at an early stage of growth (31 days after sowing). To predict phenotypic values of AGB, we employed multi-kernel genomic prediction. Consequently, the prediction accuracy of phenotypic values reached a maximum at a relatively early growth stage (38 days after sowing). Hence, the optimal timing for MS imaging may depend on the irrigation levels.

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Organic chemistry in the innermost, infalling envelope of the Class 0 protostar L483

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833214 ◽

2019 ◽

Vol 629 ◽

pp. A29 ◽

Cited By ~ 20

Author(s):

Steffen K. Jacobsen ◽

Jes K. Jørgensen ◽

James Di Francesco ◽

Neal J. Evans ◽

Minho Choi ◽

...

Keyword(s):

Organic Chemistry ◽

Angular Momentum ◽

Velocity Profile ◽

Large Scale ◽

Organic Molecules ◽

Early Stage ◽

Momentum Conservation ◽

High Angular Resolution ◽

Gas Kinematics ◽

Complex Organic

Context. Observations of the innermost regions of deeply embedded protostellar cores have revealed complicated physical structures as well as a rich chemistry with the existence of complex organic molecules. The protostellar envelopes, outflow, and large-scale chemistry of Class 0 and Class I objects have been well studied, but while previous works have hinted at or found a few Keplerian disks at the Class 0 stage, it remains to be seen if their presence in this early stage is the norm. Likewise, while complex organics have been detected toward some Class 0 objects, their distribution is unknown as they could reside in the hottest parts of the envelope, in the emerging disk itself, or in other components of the protostellar system, such as shocked regions related to outflows. Aims. In this work, we aim to address two related issues regarding protostars: when rotationally supported disks form around deeply embedded protostars and where complex organic molecules reside in such objects. We wish to observe and constrain the velocity profile of the gas kinematics near the central protostar and determine whether Keplerian motion or an infalling-rotating collapse under angular momentum conservation best explains the observations. The distribution of the complex organic molecules is used to investigate whether they are associated with the hot inner envelope or a possible Keplerian disk. Methods. We observed the deeply embedded protostar, L483, using Atacama Large Millimeter/submillimeter Array (ALMA) Band 7 data from Cycles 1 and 3 with a high angular resolution down to ~0.1′′ (20 au) scales. We present new HCN J = 4–3, HCO+ J = 4–3, CS J = 7–6, and H13CN J = 4–3 observations, along with a range of transitions that can be attributed to complex organics, including lines of CH3OH, CH3OCHO, C2H5OH, NH2CHO, and other species. Results. We find that the kinematics of CS J = 7–6 and H13CN J = 4–3 are best fitted by the velocity profile from infall under conservation of angular momentum and not by a Keplerian profile. The only discernible velocity profile from the complex organics, belonging to CH3OCHO, is consistent with the infall velocity profile derived from CS J = 7–6 and H13CN J = 4–3. The spatial extents of the observed complex organics are consistent with an estimated ice sublimation radius of the envelope at ~50 au, suggesting that the complex organics exist in the hot corino of L483, where the molecules sublimate off the dust grain ice mantles and are injected into the gas phase. Conclusions. We find that L483 does not harbor a Keplerian disk down to at least 15 au in radius. Instead, the innermost regions of L483 are undergoing a rotating collapse and the complex organics exist in a hot corino with a radius of ~40–60 au. This result highlights that some Class 0 objects contain only very small disks, or none at all, and the complex organic chemistry take place on scales inside the hot corino of the envelope in a region larger than the emerging disk.

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Experimental Study on the Characteristics of Fire Smoke Movement in Ultra Thin and Tall Atriums by Hot Smoke Test

E3S Web of Conferences ◽

10.1051/e3sconf/20197901007 ◽

2019 ◽

Vol 79 ◽

pp. 01007 ◽

Cited By ~ 1

Author(s):

Hao Zhang ◽

Cuifeng Du ◽

Jingji Li ◽

Jian Chen ◽

Hongwen Li

Keyword(s):

Early Stage ◽

Linear Trend ◽

Side Wall ◽

Test Method ◽

Velocity Variation ◽

Width Ratio ◽

Enhancement Effect ◽

Smoke Movement ◽

Smoke Plume ◽

Smoke Test

The characteristics of smoke natural filling in ultra thin and tall atriums were investigated by hot smoke test method. For the fire located on the atrium ground, the smoke touched the side wall first and then extended both upwards and downwards. The smoke plume rising velocity variation can be divided into four stages, different from the normal law in large spaces. In the very early stage of natural filling, the smoke concentration near the height of wall touching point was highest and maintained at a high level in the whole process. The linear trend of temperature increasing in plume center above the height of touching point was broken, far less than the theoretical predictions, which verified the enhancement effect of boundary heat exchange caused by plume restriction. The variation tendencies of smoke density and temperature were similar during the hot smoke test,and there existed a good linear relation between these two parameters. The height-width ratio was calculated as 3.2 averagely by the test results when smoke plume would likely touch atrium walls, and it was very close to the theoretically derived value. This ratio can be used as the definition condition for ultra thin and tall atriums.

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