Detailed Scheme Research Articles

Mathematical Modeling and Experiments on Pyrolysis of Walnut Shells Using a Fixed-Bed Reactor

Pyrolysis is a low-emission and sustainable thermochemical technique used in the production of biofuels, which can be used as an alternative to fossil fuels. Understanding the kinetic characterization of biomass pyrolysis is essential for process upscaling and optimization. There is no accepted model that can predict pyrolysis kinetics over a wide range of pyrolysis conditions and biomass types. This study investigates whether or not the classical lumped kinetic model with a three-competitive reaction scheme can accurately predict the walnut shell pyrolysis product yields. The experimental data were obtained from walnut shell pyrolysis experiments at different temperatures (300–600 °C) using a fixed-bed reactor. The chosen reaction scheme was in good agreement with our experimental data for low temperatures, where the primary degradation of biomass occurred (300 and 400 °C). However, at higher temperatures, there was less agreement with the model, indicating that some other reactions may occur at such temperatures. Hence, further studies are needed to investigate the use of detailed reaction schemes to accurately predict the char, tar, and gas yields for all types of biomass pyrolysis.

Snow Level From Post‐Processing of Atmospheric Model Improves Snowfall Estimate and Snowpack Prediction in Mountains

AbstractIn mountains, the precipitation phase greatly varies in space and time and affects the evolution of the snow cover. Snowpack models usually rely on precipitation‐phase partitioning methods (PPMs) that use near‐surface variables. These PPMs ignore conditions above the surface thus limiting their ability to predict the precipitation phase at the surface. In this study, the impact on snowpack simulations of atmospheric‐based PPMs, incorporating upper atmospheric information, is tested using the snowpack scheme Crocus. Crocus is run at 2.5‐km grid spacing over the mountains of southwestern Canada and northwestern United States and is driven by meteorological fields from an atmospheric model at the same resolution. Two atmospheric‐based PPMs were considered from the atmospheric model: the output from a detailed microphysics scheme and a post‐processing algorithm determining the snow level and the associated precipitation phase. Two ground‐based PPMs were also included as lower and upper benchmarks: a single air temperature threshold at 0°C and a PPM using wet‐bulb temperature. Compared to the upper benchmark, the snow‐level based PPM improved the estimation of snowfall occurrence by 5% and the simulation of snow water equivalent (SWE) by 9% during the snow melting season. In contrast, due to missing processes, the microphysics scheme decreased performances in phase estimate and SWE simulations compared to the upper benchmark. These results highlight the need for detailed evaluation of the precipitation phase from atmospheric models and the benefit for mountain snow hydrology of the post‐processed snow level. The limitations to drive snowpack models at slope scale are also discussed.

Astraeus – VI. Hierarchical assembly of AGN and their large-scale effect during the Epoch of Reionization

ABSTRACT In this work, the sixth of a series, we use the seminumerical rAdiative tranSfer coupling of galaxy formaTion and Reionization in N-body dark-matter simUlationS (astraeus) framework to investigate the nature of the sources that reionized the Universe. We extend astraeus, which already couples a galaxy formation semi-analytical model with a detailed seminumerical reionization scheme, to include a model for black-hole formation, growth, and the production of ionizing radiation from associated active galactic nuclei (AGNs). We calibrate our fiducial AGN model to reproduce the bolometric luminosity function at z ≃ 5, and explore the role of the resulting AGN population in reionizing the Universe. We find that in all the models yielding a reasonable AGN luminosity function, galaxies dominate overwhelmingly the ionizing budget during the Epoch of Reionization, with AGN accounting for 1–10 per cent of the ionizing budget at z = 6 and starting to play a role only below z ≲ 5.

Analysis of continuous data assimilation scheme for the Navier–Stokes equations using variational multiscale method

In this study, we analyse a continuous data assimilation (CDA) scheme which enables us to combine an observable data with a numerical method to obtain better solutions in which these solutions are also closely similar to the current state of the system. The scheme is applied on a Navier–Stokes system which is discretized with two-step Backward Differentiation Formula (BDF2) in time and finite element in space. In order to improve the accuracy and prevent some non-physical oscillations due to the effect of small viscosity and the dominance of convection, a projection based variational multiscale method (VMS) has also been applied to the system. We present the long-time stability and long-time convergence analyses of the scheme in details and several numerical tests in order to support theoretical findings and demonstrate the promise of the method.

EXPLORE THE MECHANISM OF QUANTUM DOTS AS FLUORESCENT SENSOR TO DETECT HEAVY METAL IONS USING A SYNCHRONOUS FLUORESCENCE POLARIZATION TECHNIQUE

By combining synchronous fluorescence (SF) spectroscopy and fluorescence polarization (FP) technology, a new spectral technique, termed synchronous fluorescence polarization (SFP) can be obtained. It inherits the advantages of both, such as high sensitivity, less sample demand, rapid detection, and so on. This concept has been proposed before without implementation details. In this work, a detailed implementation scheme of the technology is proposed, including the hardware requirements of the instrument, the measurement and calculation of the instrument correction factor G-factor, the spectral acquisition, the removal of inner filter effect (IFE), the removal of solvent background and the calculation and analysis of anisotropy. Furthermore, exploring the mechanism of quantum dots (QDs) as fluorescent sensor to detect heavy metal ions was taken as an example to introduce the application of the SFP method. Through detecting SF anisotropy, the mechanism of QDs probing [Formula: see text] ion was explained. If an appropriate fluorescent polarization enhancer is chosen, SFP can be used for quantitative detection. This work provides a specific implementation scheme of the SFP technology for the first time, which expands the application of fluorescence technology.

Plasma-Catalysis of Nonoxidative Methane Coupling: A Dynamic Investigation of Plasma and Surface Microkinetics over Ni(111).

A heterogeneous catalytic microkinetic model is developed and implemented in a zero-dimensional (0D) plasma model for the dynamic study of methane nonoxidative coupling over Ni(111) at residence times and power densities consistent with experimental reactors. The microkinetic model is thermodynamically consistent and is parameterized based on the heats of chemisorption of surface species on Ni(111). The surface network explicitly accounts for the interactions of plasma species, namely, molecules, radicals, and vibrationally excited states, with the catalyst active sites via adsorption and Eley-Rideal reactions. The Fridman-Macheret model is used to describe the enhancement of the rate of the dissociative adsorption of vibrationally excited CH4, H2, and C2H6. In combination with a previously developed detailed kinetic scheme for nonthermal methane plasma, 0D simulation results bring insights into the complex dynamic interactions between the plasma phase and the catalyst during methane nonoxidative coupling. Differential turnover frequencies achieved by plasma-catalysis are higher than those of equivalent plasma-only and catalysis-only simulations combined; however, this performance can only be sustained momentarily. Hydrogen produced from dehydrogenation of ethane via electron collisions within the plasma is found to quickly saturate the surface and even promote the conversion of surface CH3* back to methane.

General classification of the document: suggestions for improvement

The purpose of the article is to optimise the scheme of the general classification of the document and continue the discussion for the development of the typology of the document. Research methodology is based on the application of a complex of theoretical and empirical methods of general scientific cognition, as well as on special methods, in particular, analysis, synthesis, comparative and logical methods, the method of visualisation of research results, systematic, and informational and communicational approaches when building a general classification of the document. The scientific novelty of the work lies in the fact that the article, based on the general classification of the document proposed by famous Ukrainian researcher Professor G. M. Shvetsova-Vodka, the classifications of the leading experts in document studies, and our own scientific investigations, outlines a number of proposals for solving the most important issues of document typology, and presents a detailed classification scheme of the document. Conclusions. The proposed block document classification scheme reflects the latest views of scholars on its nature as a social-communication phenomenon, on the architecture of the block classification scheme and the facets of dividing documents according to the most important feature of their classification, which create a certain block. The research is aimed to develop the general theory of the document, taking into account the classification features inherent in all documents regardless of their purpose. As a result of the conducted research, the characteristics by which the general classification of the document should be carried out, the names and sequence of the blocks, the content of the facets and sub-facets that make up the general multi-faceted classification, and the characteristics of individual types of the document have been specified. Keywords: document science, document typology, general classification, research directions, features of information recording.

Flame Anchoring of an H2/O2 Non-Premixed Flamewith O2 Transcritical Injection

The article is devoted to the analysis of the flame anchoring mechanism in the test case MASCOTTE C-60 RCM2 on supercritical hydrogen/oxygen combustion at 60 bar, with transcritical (liquid) injection of oxygen. The case is simulated by means of the in-house parallel code HeaRT in the three-dimensional LES framework. The cubic Peng–Robinson equation of state in its improved translated volume formulation is assumed. Diffusive mechanisms and transport properties are accurately modeled. A finite-rate detailed scheme involving the main radicals, already validated for high-pressure H2/O2 combustion, is adopted. The flow is analysed in terms of temperature, hydrogen and oxygen instantaneous spatial distributions, evidencing the effects of the vortex shedding from the edges of the hydrogen injector and of the separation of the oxygen stream in the divergent section of its tapered injector on the flame anchoring and topology. Combustion conditions are characterised by looking at the equivalence ratio and compressibility factor distributions.

Fully homomorphic encryption-based privacy-preserving scheme for cross edge blockchain network

The growing development of blockchain technology has led to the emergence of blockchain applications for various fields. One significant use of blockchain technology is the edge blockchain network, which is a blockchain network made up of connected edge computer nodes. However, on-chain privacy data leaking is a concern on the present edge blockchain network. The demand for collaborative interaction amongst edge computing nodes in many domains is growing more critical as the Internet of Things continues to evolve. In this paper, we propose a data privacy-preserving scheme for cross edge blockchain network, which uses the privacy protection technology of fully homomorphic encryption to encrypt the data on the chain to ensure the “available and invisible” of the on-chain privacy data. First of all, this paper designs a cross edge blockchain model and give details of the interaction and privacy computing process in the cross edge blockchain. a distributed private key sharing scheme is designed in this work to provide the relay chain’s auditable functionality. Subsequently, we describe the security of the scheme in detail. Finally, we implement this scheme using the CKKS algorithm. Through simulation experiments, we evaluate the performance of the instantiation process of the scheme. The test results manifest that the proposed scheme has excellent practicability and security.

A flexible and efficient tooling design technology for aircraft fuselage panel assembly

PurposeRegarding the assembly of the fuselage panel, this paper aims to illustrate a design of pre-assembly tooling of the fuselage panel for the automatic drilling riveting machine. This new prototype of pre-assembly tooling can be used for different types and sizes of fuselage panels. Also, apply to the automated drilling and riveting machine of the fuselage panels.Design/methodology/approachBased on the different structures of the fuselage panel, the position of the preassembly tooling components, location of the clamp and position of the fuselage panel are determined. After that, the overall structure of the preassembly tooling is designed, including the movable frame and the cardboard. The cardboard positioning module and the clamping module formulate a detailed design scheme of preassembly tooling for the fuselage panel. The structure of the pre-assembled tooling is optimized by static analysis. The result of the overall design is optimized by using MATLAB and CATIA-V5 software, and the results meet the condition of the design requirements.FindingsThe traditional assembly process of the fuselage is to install the fuselage panel on the preassembly tooling for positioning the hole and then install it on the automated drilling and riveting tooling for secondary tooling. Secondary tooling can consume assembly errors of the fuselage panel. The new prototype of flexible tooling design for the fuselage panel not only avoids the secondary tooling error of the fuselage panel but also meets the preassembly of different types of fuselage panels.Research limitations/implicationsThe further development of the flexible tooling design of the fuselage panel is to reduce the error of sliding tooling due to friction of the sliding components. Because if the assembly cycle is increased, the sliding parts will lose material due to corrosion. As a result, the repeated friction force is the root cause of the positioning error of sliding parts. Therefore, it is necessary to engage less corrosive material. Also, the lubricant may be used to reduce the corrosion in minimizing the positioning error of the sliding tool components. In addition, it is important to calculate the number of assembly cycles for efficient fuselage panel assembly.Originality/valueAccording to the structure and assembly process characteristics of the fuselage panel, the fuselage panel preassembly tooling can optimize the assembly process of the fuselage panel and have certain practical application values.

Energy Consumption Analysis of a Rolling Mechanism Based on a Five-Bow-Shaped-Bar Linkage

To reveal the relationship between the center of mass (CoM) trajectory of a closed five-bow-shaped-bar linkage and its energy consumption, this paper presents a trajectory planning method based on the workspace of the CoM. Using different height points located on the symmetric centerline of the workspace of the CoM as via points, the CoM trajectory is planned by combining cubic polynomials with Bézier curves based on quadratic Bernstein polynomials. Herein, the system energy consumption is obtained by integrating the product of generalized velocity and generalized force versus time, where the generalized force is calculated by Lagrange’s equation including the Rayleigh dissipation function. Then, two schemes of dynamic rolling are proposed to compare, and the theoretical results show that the system consumes less energy under the sinusoid scheme when the via point height is lower and the via point of higher height is more suitable under the modified trapezoidal curve scheme. Furthermore, this paper combines the locomotion simulation software to design the locomotion of the mechanism’s CoM trajectory under two schemes in detail and verifies the correctness of the theoretical results.

Design of DC Magnet Power Supply System for ITER Static Magnetic Field Test Facility

International Thermonuclear Experimental Reactor (ITER) static magnetic field (SMF) test facility requires a dc power supply with low voltage, high current, and low harmonics under high power density. Due to the limitation of switching loss, there is a contradiction between the output current capability and the output ripple. Large output current usually leads to low switching frequency, and low switching frequency will generate a large number of harmonics. To solve the problems, a topology based on the interleaving parallel buck converter is used and tested in this article. Moreover, the topology is realized with only a small number of switching metal–oxide–semiconductor field-effect transistors (MOSFETs). This article introduces the system design scheme and control method in detail. The analysis of harmonic and simulation is carried out. The validity of the proposed scheme and control strategy was confirmed by experiments, and the power supply system can supply a large current of 12.23 kA and has the ability of low ripple.

Average Cloud Droplet Size and Composition: Good Assumptions for Predicting Oxidants in the Atmospheric Aqueous Phase?

Chemical models that describe the atmospheric multiphase (gas/aqueous) system often include detailed kinetic and mechanistic schemes describing chemical reactions in both phases. The present study explores the importance of properties including the chemical composition of droplet populations, such as pH value and iron present in only a few droplets, as well as droplet size and their distribution. It is found that the assumption of evenly distributed iron in all cloud droplets leads to an underestimate by up to 1 order of magnitude of OH concentrations in the aqueous phase, whereas the predicted iron(II)/iron(total) ratio is overestimated by up to a factor of 2. While the sulfate mass formed in cloud droplets is not largely affected by any of the assumptions, the predicted secondary organic aerosol mass varies by an order of magnitude. This sensitivity study reveals that multiphase chemistry model studies should focus not only on chemical mechanism development but also on careful considerations of droplet properties to comprehensively describe the atmospheric multiphase chemical system.

Parametric studies and optimal design of the exponents collocation of a segmented acoustic black hole beam

Acoustic black hole (ABH) is a promising way to deal with the flexural vibration of different structures. By utilizing power-law profiles in extremities of structures, ABH could gradually reduce the phase velocity of the propagating flexural waves and realize the capture of waves in the ABH portion. However, it is difficult to manufacture an efficient ABH extremity in practical implementations, and the existence of truncation always leads to greatly reduction of ABH effect at the range of desired frequencies. In this paper, parametric studies of segmented ABH beams have been carried out to investigate how different ABH portions’ exponents affect the vibration attenuation performance of the segmented ABH beam, thus further optimizing the exponents collocation design to get the better ABH effect around the desired frequencies. The detailed meshing scheme has been first studied to guarantee the accuracy of the numerical simulation model. Then, the mobility of different segmented ABH beams with varying exponents collocations are compared to show the influence of power-law exponent changes of the first and second ABH portions on their vibration attenuation performance. Additionally, the energy ratio and reflection coefficient have also been calculated to reveal the underlying physical mechanism. Furthermore, the radial basis function based neural network and simulated annealing method are used to establish the surrogate model and optimize exponents collocation. The optimized segmented ABH beam exhibits more perfect vibration attenuation performance because of possessing lower reflection coefficient. Finally, an experiment has been completed to validate the optimization result.

Quality control tests on the new front-end electronics for the Schwarzschild–Couder Telescope

One of the proposed Medium-Sized Telescopes for the Cherenkov Telescope Array is the dual mirror optics Schwarzschild–Couder Telescope (SCT). The prototype SCT camera is currently equipped with 24 SiPM modules each one made of 64 pixels. The upgrade of the current camera is in progress, with the aim of fully equipping the 177 SiPM modules. A new front-end electronics is being developed and tested in order to improve the noise performance and match CTA requirements. In this process, 11328 SiPMs and the related electronics will be tested in the laboratories before the assembly on the telescope camera. The SiPM Multichannel ASIC for high Resolutions Cherenkov Telescope (SMART) has been developed by INFN to amplify the SiPM signals to be digitized and inserted in the trigger logic based on the TeV Array with GSa/s sampling and Experimental Trigger Application Specific Integrated Circuit (TARGET ASICs). An experimental setup has been devised to test about 750 SMART, which will be used to equip the full camera of the prototype SCT. Each SMART was tested for proper operation in response to a laser pulse. In this contribution we present a detailed scheme of the test bench and the first results obtained on the quality control measurements.

Reliable PUF-based mutual authentication protocol for UAVs towards multi-domain environment

With the widespread application of unmanned aerial vehicles (UAVs), the discussion about the various security and privacy issues of UAVs have never stopped. Physical Unclonable Function (PUF) is inherently unclonable and tamper-proof, many authentication and key agreement protocols based on PUF for UAVs have been proposed in the past. But they can only be suitable for mutual authentication between a single ground station and multiple UAVs. Not only does this centralized authentication method have a single point of failure, but also cannot adapt to the increasing demand for UAV authentication in multi-domain settings. In this paper, we propose a novel lightweight mutual authentication scheme based on PUF which is resistant to well-known attacks such as node tampering attacks, and cloning attacks, etc. Furthermore, we realized cross-domain authentication for UAVs, ensuring secure and efficient communication for UAVs in different domains. We have demonstrated the correctness of our scheme in detail, and carried out experimental analysis. The results show that our scheme is sufficiently secure and effective, and is suitable for UAVs in a multi-domain environment.

A reduced kinetic scheme for methyl methacrylate gas-phase combustion

Gas-phase combustion of methylmethacrylate (MMA) monomer is an essential stage of solid polymethylmethacrylate (PMMA) combustion, which is of interest in many applications. A skeletal kinetic scheme for MMA combustion in air is proposed including 44 irreversible elementary reactions for 29 species. The mechanism is derived from the reduced kinetic scheme for MMA oxidation comprised of 263 reactions for 66 components. In this work, the mechanism predictive capabilities are demonstrated by solving the self-ignition problem, as well as the premixed flame propagation problem for MMA-air mixtures. It is shown that the skeletal mechanism overpredicts the ignition delay times due to significant simplification of the MMA decomposition stage reaction pathways. The flame propagation speed is predicted reasonably for lean and nearly-stoichiometric mixtures, but overpredicted for fuel-rich mixtures. Also, a diffusion flame representing the cup burner of liquid MMA is simulated in two-dimensional statement of the problem, the results are shown to agree well with the measurements and numerical simulations performed earlier on the basis of a detailed kinetic scheme. The skeletal mechanism can be used in the numerical simulations of gas-phase combustion of MMA, including the problems of flame propagation over the solid PMMA polymer.

Assessments and analysis of lumped and detailed pyrolysis kinetics for biomass torrefaction with particle-scale modeling

A one-dimensional model with consideration of internal and external heat transfer, particle shrinkage, moisture evaporation, and pyrolysis kinetics is developed to predict biomass torrefaction behaviors. Three different kinetic schemes (i.e. a lump kinetic scheme and two detailed kinetic schemes (Andrés Anca-Couce and IngwaldObernberger, 2016, and Debiagi et al., 2018) are evaluated to find the suitable pyrolysis kinetics for biomass torrefaction process. The modeling results are compared with single beechwood particle torrefaction experiments. The results show that the detailed kinetic scheme proposed by Debiagi et al. shows the best performance among the three kinetic schemes, and it can correctly predict particle shrinkage, particle conversion, mass loss history, and biochar C/H/O compositions, while the lump kinetic scheme underestimates torrefaction rates and particle shrinkage degree at low temperature conditions (280–370 °C), and the kinetic scheme proposed by Andrés and Ingwald underestimates carbon concentration and overestimates the oxygen concentration of torrefied wood at high temperature conditions (370, 400, and 430 °C). Therefore, the kinetic scheme of Debiagi et al. is considered to be the most promising kinetics in particle-scale modeling of the torrefaction process. A sensitivity analysis is also performed to evaluate the effects of modeling parameters on modeling results as well as study the control mechanism of torrefaction process. The results show that modeling results are significantly influenced by parameters involved with external and external heat transfer related, boundary conditions, and reaction rate, indicating torrefaction process of large particles is controlled by both internal and external heat transfer, and kinetics.

Monitoring the photochemistry of a formazan over 15 orders of magnitude in time.

2,3,5-triphenyltetrazolium chloride (TTC) may convert into phenyl-benzo[c]tetrazolocinnolium chloride (PTC) and 1,3,5-triphenylformazan (TPF) under irradiation with light. The latter reaction, albeit enzymatically rather than photochemically, is used in so-called TTC assays indicating cellular respiration and cell growth. In this paper, we address the photochemistry of TPF with time-resolved spectroscopy on various time scales. TPF is stabilized by an intramolecular hydrogen bond and switches photochemically via an E-Z isomerization around an N=N double bond into another TPF-stereoisomer, from which further isomerizations around the C=N double bond of the phenylhydrazone group are possible. We investigate the underlying processes by time-resolved spectroscopy in dependence on excitation wavelength and solvent environment, resolving several intermediates over a temporal range spanning 15 orders of magnitude (hundreds of femtoseconds to hundreds of seconds) along the reaction path. In a quantum-chemical analysis, we identify 16 stable ground-state isomers and discuss which ones are identified in the experimental data. We derive a detailed scheme how these species are thermally and photochemically interconnected and conclude that proton transfer processes are involved.

Research on Online and Offline Integrated Teaching Mode of Artificial Intelligence Courses Based on Flying Paddle AI Studio Platform

At present, there are many problems in the teaching of deep learning courses, the most important of which is that it is difficult to carry out experiments in an orderly manner. To solve this problem, this paper puts forward an online experiment scheme based on Baidu Flying Paddle AI Studio platform, so as to realize the teaching mode of online and offline integration. This paper introduces the specific implementation scheme in detail.