scholarly journals How to Quantify the Dynamics of Single (Straight or Sinuous) and Multiple (Anabranching) Channels from Imagery for River Restoration

2021 ◽  
Vol 11 (17) ◽  
pp. 8075
Author(s):  
Gilles Arnaud-Fassetta ◽  
Gabriel Melun ◽  
Paul Passy ◽  
Guillaume Brousse ◽  
Olivier Theureaux
Keyword(s):  
High Energy ◽  
Channel Length ◽  
Full Potential ◽  
Stream Power ◽  
Metric Analysis ◽  
Geomorphological Changes ◽  
Agricultural Areas ◽  
Mediterranean France ◽  
Active Channel ◽  
Section Analysis

Since the 2000s, European rivers have undergone restoration works to give them back a little more ‘freedom space’ and consolidate the hydro-sedimentary continuum and biological continuity as required by the Water Framework Directive (WFD). In high-energy rivers, suppression of lateral constraints (embankment removal) leads to geomorphological readjustments in the modification of both the active-channel length and active-channel width. The article provides a new methodological development to overcome the shortcomings of traditional methods (based on diachronic cross-section analysis) unable to simultaneously take into account these geometric adjustments after active-channel restoration. It allows us to follow and precisely quantify the geomorphological changes of the active channel faced to the stakes (i.e., structures or urbanized, recreation or agricultural areas) in the floodplain. The methodology proposes three new indicators (distance from active channel to stakes or floodplain margins as indicator 1; distance from stakes to active channel as indicator 2; diachronic distance as indicator 3) and a metric analysis grid in the 2D Euclidean space. It is applied to the Clamoux River (order 4, Strahler; bankfull, specific stream power: 280 W/m2) in the Aude watershed (Mediterranean France). The paper shows the full potential of this methodological protocol to be able to meet managers’ expectations as closely as possible within the framework of the multi-annual active-channel monitoring.

scholarly journals Mathematical Model of Pressure Formation Process along the Helix Channel Length of Screw Grinder

2020 ◽  
Author(s):  
Valery Pelenko ◽  
Ilkhom Usmanov ◽  
Vyacheslav Pokholchenko ◽  
Irina Smirnova
Keyword(s):  
Energy Consumption ◽  
Mathematical Description ◽  
Analytical Description ◽  
High Energy ◽  
Channel Length ◽  
Operating Conditions ◽  
Technical Equipment ◽  
Mining Equipment ◽  
Technological Parameters ◽  
Total Energy Consumption

The improvement of the technical equipment effectiveness is currently becoming particularly important. This applies not only to large and high-energy-intensive machines, but also to household appliances, the total energy consumption of which often exceeds the energy consumption of the overall equipment. These types of devices include, in particular, grinding and cutting equipment. The mathematical description of the processes carried out on this equipment is generalized and can be extended to a wider class of machines, including waste processing and mining equipment. The technological parameters, the design of screw grinders, and the processes of movement, deformation, extrusion and cutting carried out in them are characterized by a significant number of factors affecting the energy intensity. The main ones are the geometric parameters of the screw, machine’s body, cross knife, grinding plate’s thickness, the number and diameter of holes in it, as well as the product’s physical-mechanical characteristics and operating conditions. The most important for the mathematical description are the zones and processes where the main share of the consumed power is spent. The complexity of their analytical description is due to a simplified consideration of either individual technological zones of grinders’ existing designs, or the use of unreasonable simplifications.

scholarly journals Metal-Water mixtures for Propulsion and Energy-Conversion Applications: Recent Progress and Future Directions

2018 ◽  
Vol 20 (1) ◽  
pp. 53 ◽  
Author(s):  
Dilip Sundaram
Keyword(s):  
Particle Size ◽  
Energy Conversion ◽  
Experimental Studies ◽  
High Energy ◽  
High Energy Density ◽  
Full Potential ◽  
Predictive Tool ◽  
Practical Applications ◽  
Relative Safety ◽  
Metal Water

The metal-water system is attractive for propulsion and energy-conversion applications. Of all metals, aluminum is attractive due to its high energy density, relative safety, and low cost. Experimental studies provide new insight on the combustion and propulsive behaviors. The burning rate is found to be a strong function of both pressure and particle size. Furthermore, there is a wide scatter in the measured pressure exponents due to differences in particle size, pressure, pH, and equivalence ratio. A major problem with Al/H2O mixtures is incomplete combustion and poor impulses, thereby rendering Al/H2O mixtures unsuitable for practical applications. Efforts to improve the performance of Al/H2O mixtures have only met with moderate success. Although experiments have revealed these new trends, not much is offered in terms of the underlying physics and mechanisms. To explore the combustion mechanisms, theoretical models based on energy balance analysis have been developed. These models involve numerous assumptions and many complexities were either ignored or treated simplistically. The model also relies on empirical inputs, which makes it more a useful guide than a predictive tool. Future works must endeavor to conduct a more rigorous analysis of metal-water combustion. Empirical inputs should be avoided and complexities must be properly treated to capture the essential physics of the problem. The model should help us properly understand the experimental trends, offer realistic predictions for unexplored conditions, and suggest guidelines and solutions in order to realize the full potential of metal-water mixtures.

scholarly journals Accurate Prediction of Band Structure of FeS2: A Hard Quest of Advanced First-Principles Approaches

2021 ◽  
Vol 9 ◽  
Author(s):  
Min-Ye Zhang ◽  
Hong Jiang
Keyword(s):  
Band Structure ◽  
First Principles ◽  
High Energy ◽  
Accurate Prediction ◽  
Band Gaps ◽  
Full Potential ◽  
Band Structures ◽  
Electronic Band ◽  
Fundamental Band ◽  
Hybrid Functionals

The pyrite and marcasite polymorphs of FeS2 have attracted considerable interests for their potential applications in optoelectronic devices because of their appropriate electronic and optical properties. Controversies regarding their fundamental band gaps remain in both experimental and theoretical materials research of FeS2. In this work, we present a systematic theoretical investigation into the electronic band structures of the two polymorphs by using many-body perturbation theory with the GW approximation implemented in the full-potential linearized augmented plane waves (FP-LAPW) framework. By comparing the quasi-particle (QP) band structures computed with the conventional LAPW basis and the one extended by high-energy local orbitals (HLOs), denoted as LAPW + HLOs, we find that one-shot or partially self-consistent GW (G0W0 and GW0, respectively) on top of the Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation with a converged LAPW + HLOs basis is able to remedy the artifact reported in the previous GW calculations, and leads to overall good agreement with experiment for the fundamental band gaps of the two polymorphs. Density of states calculated from G0W0@PBE with the converged LAPW + HLOs basis agrees well with the energy distribution curves from photo-electron spectroscopy for pyrite. We have also investigated the performances of several hybrid functionals, which were previously shown to be able to predict band gaps of many insulating systems with accuracy close or comparable to GW. It is shown that the hybrid functionals considered in general fail badly to describe the band structures of FeS2 polymorphs. This work indicates that accurate prediction of electronic band structure of FeS2 poses a stringent test on state-of-the-art first-principles approaches, and the G0W0 method based on semi-local approximation performs well for this difficult system if it is practiced with well-converged numerical accuracy.

scholarly journals The Physical and Morphological Properties of Kenaf/ Epoxy Fibres in Coating Treatment Process

2019 ◽  
Vol 16 (2) ◽  
pp. 43 ◽  
Author(s):  
Muhammad Mustakim Mohd Ghaztar ◽  
Nik Noor Idayu Nik Ibrahim ◽  
Sarani Zakaria ◽  
Ahmad Zafir Romli
Keyword(s):  
Energy Demand ◽  
Cost Effective ◽  
Treatment Method ◽  
High Energy ◽  
Natural Fibre ◽  
Morphological Properties ◽  
Fibre Coating ◽  
Acceptable Method ◽  
Section Analysis ◽  
Kenaf Fibres

Natural fibre is an economical material that often used in various applications due to its low in density, non-abrasiveness in processing and biodegradable. But, its usage in various applications is still limited due to the low in overall properties. The acceptable method to improve the properties of the fibres is by chemical treatment method that is costly, meticulous process and high energy demand. Thus, a new, simple and cost-effective fibre coating treatment method was developed which was able to improve the physical and morphological properties that open a new path for natural based materials to be used in a more robust application. In this study, the physical and morphological properties of various coated Kenaf fibres were analysed to comprehend the cutting behaviour of coated fibres after subjected to the pulverisation process. The Kenaf fibres were individually immersed in 1:4, 1:5 and 1:6 epoxy to acetone coating solutions prior cured, and pulverised consecutively using 5 mm, 1 mm, 0.5 mm and 0.25 mm mesh sizes aperture. The morphological characteristic was analysed using polarised optical and scanning electron microscope. The result showed that 1:6 coating ratio solution able to effectively coat the fibres’ aspect ratio that forming individual coated fibre which in long length pulverised fibres. Moreover, the low viscous 1:6 solution able to penetrate inside fibre structure that supported by density and fibre cross-section analysis compare to the other solutions. In future, this analysis is crucial to give insight on the coated fibres behaviour after subjected to the mechanical means of cutting process that later relates to the reinforcing mechanism in the composite samples.

Flash Proton Radiography

2015 ◽  
Vol 08 ◽  
pp. 165-180 ◽  
Author(s):  
Frank E. Merrill
Keyword(s):  
Temporal Structure ◽  
National Laboratory ◽  
High Energy ◽  
Full Potential ◽  
X Rays ◽  
Alamos National Laboratory ◽  
Proton Radiography ◽  
Los Alamos ◽  
Los Alamos National Laboratory ◽  
Wide Range

Protons were first investigated as radiographic probes as high energy proton accelerators became accessible to the scientific community in the 1960s. Like the initial use of X-rays in the 1800s, protons were shown to be a useful tool for studying the contents of opaque materials, but the electromagnetic charge of the protons opened up a new set of interaction processes which complicated their use. These complications in combination with the high expense of generating protons with energies high enough to penetrate typical objects resulted in proton radiography becoming a novelty, demonstrated at accelerator facilities, but not utilized to their full potential until the 1990s at Los Alamos. During this time Los Alamos National Laboratory was investigating a wide range of options, including X-rays and neutrons, as the next generation of probes to be used for thick object flash radiography. During this process it was realized that the charge nature of the protons, which was the source of the initial difficulty with this idea, could be used to recover this technique. By introducing a magnetic imaging lens downstream of the object to be radiographed, the blur resulting from scattering within the object could be focused out of the measurements, dramatically improving the resolution of proton radiography of thick systems. Imaging systems were quickly developed and combined with the temporal structure of a proton beam generated by a linear accelerator, providing a unique flash radiography capability for measurements at Los Alamos National Laboratory. This technique has now been employed at LANSCE for two decades and has been adopted around the world as the premier flash radiography technique for the study of dynamic material properties.

scholarly journals Islands of the upper River Ob: morphometric characteristic, evolution and dynamics

2019 ◽  
pp. 80-90 ◽  
Author(s):  
G. B. Golubtsov ◽  
R. S. Chalov
Keyword(s):  
Channel Length ◽  
Morphological Aspect ◽  
Channel Stability ◽  
Channel Deformations ◽  
River Islands ◽  
Lateral Channel ◽  
Empirical Relations ◽  
Active Channel ◽  
Channel Type

The studied reach of the upper River Ob is quite complicated in the morphological aspect and characterized by very low channel stability and high discharge of sand load. Unconstrained conditions for lateral channel migration promotes active channel deformations not only at long-term scale, but also seasonally. Channel deformations contribute to the transformation of the channel and its morphodynamic type in time. The upper River Ob is intensively used as a water course, so any reorganization of the channel and river islands should be taken into account to support navigation. Morphometric and morphodynamic analysis of the islands made it possible to develop their morphological classification. Morphometric parameters of islands, being associated with the characteristics of the channel itself, are one of the main classification features. Empirical relations were obtained that link the dimensions (Lo, Bo) and shape of islands (Lo/Bo) with the morphodynamic channel type and its stability, the degree of branching of the channel (number of islands no per 1 km of channel length x). The features of island dynamics are also determined by the morphodynamic type of the channel and are associated with the morphometric characteristics of the islands themselves and their position in the channel, which determines the transgressive, regressive and transverse shift or their stable position in time.

scholarly journals Devitrification reduces beam-induced movement in cryo-EM

IUCrJ ◽  
2021 ◽  
Vol 8 (2) ◽  
pp. 186-194
Author(s):  
Jan-Philip Wieferig ◽  
Deryck J. Mills ◽  
Werner Kühlbrandt
Keyword(s):  
High Resolution ◽  
Structure Determination ◽  
High Energy ◽  
Full Potential ◽  
High Energy Electrons ◽  
High Resolution Structure ◽  
Image Blurring ◽  
Particle Images ◽  
Resolution Structure

As cryo-EM approaches the physical resolution limits imposed by electron optics and radiation damage, it becomes increasingly urgent to address the issues that impede high-resolution structure determination of biological specimens. One of the persistent problems has been beam-induced movement, which occurs when the specimen is irradiated with high-energy electrons. Beam-induced movement results in image blurring and loss of high-resolution information. It is particularly severe for biological samples in unsupported thin films of vitreous water. By controlled devitrification of conventionally plunge-frozen samples, the suspended film of vitrified water was converted into cubic ice, a polycrystalline, mechanically stable solid. It is shown that compared with vitrified samples, devitrification reduces beam-induced movement in the first 5 e Å−2 of an exposure by a factor of ∼4, substantially enhancing the contribution of the initial, minimally damaged frames to a structure. A 3D apoferritin map reconstructed from the first frames of 20 000 particle images of devitrified samples resolved undamaged side chains. Devitrification of frozen-hydrated specimens helps to overcome beam-induced specimen motion in single-particle cryo-EM, as a further step towards realizing the full potential of cryo-EM for high-resolution structure determination.

Impact of X-ray induced radiation damage on FD-MAPS of the ARCADIA project

2022 ◽  
Vol 17 (01) ◽  
pp. C01035
Author(s):  
C. Neubüser ◽  
T. Corradino ◽  
S. Mattiazzo ◽  
L. Pancheri
Keyword(s):  
Power Consumption ◽  
Radiation Damage ◽  
High Energy ◽  
Full Potential ◽  
Sensor Design ◽  
Charge Collection Efficiency ◽  
X Ray ◽  
Active Pixel ◽  
Wide Range ◽  
The Impact

Abstract Recent advancements in Monolithic Active Pixel Sensors (MAPS) demonstrated the ability to operate in high radiation environments of up to multiple kGy’s, which increased their appeal as sensors for high-energy physics detectors. The most recent example in such application is the new ALICE inner tracking system, entirely instrumented with CMOS MAPS, that covers an area of about 10 m2. However, the full potential of such devices has not yet been fully exploited, especially in respect of the size of the active area, power consumption, and timing capabilities. The ARCADIA project is developing Fully Depleted (FD) MAPS with an innovative sensor design, that uses a proprietary processing of the backside to improve the charge collection efficiency and timing over a wide range of operational and environmental conditions. The innovative sensor design targets very low power consumption, of the order of 20 mW cm−2 at 100 MHz cm−2 hit flux, to enable air-cooled operations of the sensors. Another key design parameter is the ability to further reduce the power regime of the sensor, down to 5 mW cm−2 or better, for low hit rates like e.g. expected in space experiments. In this contribution, we present a comparison between the detector characteristics predicted with Technology Computer Aided Design (TCAD) simulations and the ones measured experimentally. The comparison focuses on the current-voltage (IV) and capacitance-voltage (CV) characteristics, as well as noise estimated from in-pixel capacitances of passive/active pixel matrices. In view of the targeted applications of this technology, an emphasis is set on the modeling of X-ray induced radiation damage at the Si-SiO2 interface and the impact on the in-pixel sensor capacitance. The so-called new Perugia model has been used in the simulations to predict the sensor performance after total ionizing doses of up to 10 Mrad.

Electronic Structure of Native Point Defects in Zngep2

2003 ◽  
Vol 799 ◽  
Author(s):  
Xiaoshu Jiang ◽  
M. S. Miao ◽  
Walter R. L. Lambrecht
Keyword(s):  
Point Defects ◽  
Density Functional ◽  
Chemical Potential ◽  
Local Density ◽  
High Energy ◽  
Orbital Method ◽  
Full Potential ◽  
Epr Spectrum ◽  
Functional Theory ◽  
Native Point Defects

ABSTRACTFirst-principles calculations are presented for various native point defects in ZnGeP2 us-ing a full-potential linearized muffin-tin orbital method in the local density approximation to density functional theory. Under Zn-poor conditions, the lowest Gibbs energy defects are found to be the Gezn antisite and Vzn. The Vae is found to have high energy of formation under any chemical potential conditions and is unstable towards formation of a Vzn and ZnGe pair. It is shown that the V−Zn cannot account for the ALI EPR spectrum commonly associated with this vacancy and an alternative model consisting of a Vzn – GeZn – Vzn is tentatively proposed.

scholarly journals Influence of Electrolyte on the Electrode/Electrolyte Interface Formation on InSb Electrode in Mg-Ion Batteries

Molecules ◽  
2021 ◽  
Vol 26 (18) ◽  
pp. 5721
Author(s):  
Irshad Mohammad ◽  
Lucie Blondeau ◽  
Jocelyne Leroy ◽  
Hicham Khodja ◽  
Magali Gauthier
Keyword(s):  
Surface Layer ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Degradation Products ◽  
High Energy ◽  
Model Material ◽  
Ex Situ ◽  
Full Potential ◽  
Magnesium Ion Batteries ◽  
The Stability

Achieving the full potential of magnesium-ion batteries (MIBs) is still a challenge due to the lack of adequate electrodes or electrolytes. Grignard-based electrolytes show excellent Mg plating/stripping, but their incompatibility with oxide cathodes restricts their use. Conventional electrolytes like bis(trifluoromethanesulfonyl)imide ((Mg(TFSI)2) solutions are incompatible with Mg metal, which hinders their application in high-energy Mg batteries. In this regard, alloys can be game changers. The insertion/extraction of Mg2+ in alloys is possible in conventional electrolytes, suggesting the absence of a passivation layer or the formation of a conductive surface layer. Yet, the role and influence of this layer on the alloys performance have been studied only scarcely. To evaluate the reactivity of alloys, we studied InSb as a model material. Ex situ X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy were used to investigate the surface behavior of InSb in both Grignard and conventional Mg(TFSI)2/DME electrolytes. For the Grignard electrolyte, we discovered an intrinsic instability of both solvent and salt against InSb. XPS showed the formation of a thick surface layer consisting of hydrocarbon species and degradation products from the solvent (THF) and salt (C2H5MgCl−(C2H5)2AlCl). On the contrary, this study highlighted the stability of InSb in Mg(TFSI)2 electrolyte.

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