Indirect Production Research Articles

Global existence and boundedness in a chemotaxis system with indirect nonlinear signal production

Global existence and boundedness in a chemotaxis system with indirect nonlinear signal production

Global boundedness in a 3D quasilinear Keller-Segel-Stokes system with nonlinear sensitivity and indirect signal production

This paper is concerned with the Keller-Segel-Stokes system{nt+u⋅∇n=Δnm−∇⋅(n(1+n)−α∇v),vt+u⋅∇v=Δv−v+w,wt+u⋅∇w=Δw−w+n,ut=Δu+∇P+n∇ϕ,∇⋅u=0,(⁎) under no-flux/no-flux/no-flux/Dirichlet boundary conditions in smoothly bounded domains Ω⊂R3 with m>0 and α∈R. It is shown that for all suitably regular initial data an associated initial-boundary value problem (⁎) possesses at least one global boundedness weak solution provided m+α>109. We underline that the same results were established for the corresponding system with direct signal production in a well-known result if m+2α>2 and m>34 in [24] or m>43 and α=0 in [61] or m=1 and α>13 in [51]. Our result rigorously confirms that the indirect signal production mechanism genuinely contributes to the global solvability of the three-dimensional Keller-Segel-Stokes system.

Critical mass phenomena in higher dimensional quasilinear Keller–Segel systems with indirect signal production

In this paper, we deal with quasilinear Keller–Segel systems with indirect signal production, complemented with homogeneous Neumann boundary conditions and suitable initial conditions, where is a bounded smooth domain, and We show that in the case , there exists such that if either or , then the solution exists globally and remains bounded, and that in the case , if either or , then there exist radially symmetric initial data such that and the solution blows up in finite or infinite time, where the blow‐up time is infinite if . In particular, if , there is a critical mass phenomenon in the sense that is a finite positive number.

Process simulation and economic evaluation of an integrated production plant for methanol, acetic acid and DME synthesis via sugarcane bagasse gasification

Sugarcane bagasse is generated in large quantities in Brazil, and it could be gasified for the production of several chemicals, adding value to the sugar and ethanol production chain. The objective of this work is the simulation of an integrated plant for the production of three important chemicals through sugarcane bagasse gasification: methanol, acetic acid and DME. A sensitivity analysis was performed and showed how gasification temperature and steam-to-biomass ratio should be adjusted to favor one or another product (T = 900 °C and SB = 0.9 for methanol and indirect acetic acid and DME production; T = 950 °C and SB = 0.5 for direct DME production), and an economic analysis has shown that the installation of a multipurpose plant is feasible (paybacks of less than 5 years and multipurpose fashion not affecting the investment return) and how the process can be reconfigured depending on the economic scenario.

The Usage Status of Joetermel Energy in the World, Turkey and Djibouti

In recent years, with the increase in population and the development of technology in the world, the need for energy has been increasing day by day. With the rapid depletion of fossil fuel reserves such as oil, coal and natural gas and the increase in the population, renewable energy sources are gaining importance. Geothermal energy, one of the renewable energy sources, is currently used in various processes such as electricity generation, heating and drying. Geothermal Energy is a clean, cheap and environmentally friendly domestic underground renewable energy source. For this reason, the issue of assessing the situation of direct and indirect production and use of geothermal energy in the world, Turkey and Djibouti has gained importance.

How far do indirect signal production mechanisms regularize the three-dimensional Keller–Segel–Stokes system?

How far do indirect signal production mechanisms regularize the three-dimensional Keller–Segel–Stokes system?

Influence of pseudoboehmite on the performance of shaped mordenite catalyst for dimethyl ether carbonylation

As a key step of indirect production of ethanol from syngas, the carbonylation of dimethyl ether (DME) has attracted much attention. It is of great importance to develop shaped catalyst with high efficiency and strong mechanical properties to promote the process industrialization. Extruded mordenite (MOR) has been used as the catalyst for industrial DME carbonylation. In this work, the effect of properties and content of pseudoboehmite as a binder on mechanical strength and catalytic performance of the extruded MOR were systematically studied. Combining TG, XRD, N2 adsorption, and rheological property analysis etc., we found that the interlayer water content of pseudoboehmite affect peptization process, which leads to the difference in mechanical strength and pore structure. Then, the DME carbonylation performance of the extruded MOR was discussed based on textural parameters and acidic properties. Further, DME diffusion experiments were conducted and analyzed by using standard and the time-fractional diffusion models respectively. As a result, the influence of pseudoboehmite on mass transfer performance was quantitatively analyzed. The results will provide important guidance for the development of shaped zeolite catalysts in industry.

A combined production technology for ethylene and hydrogen with an ethane cracking center and dielectric barrier discharge plasma reactor

Dielectric barrier discharge (DBD) plasma technology for non-oxidative CH4 conversion is considered a promising alternative to fossil fuel-based thermochemical counterparts for ethylene production. Herein, we propose a combined production technology for ethylene and hydrogen using shale gas, which consists of an ethane cracking center (ECC) and a DBD plasma reactor. Our plasma-assisted catalytic CH4 conversion reaction facilitates the control of product selectivity by adjusting the particle size and enhances ethylene production compared to conventional ECCs. To demonstrate the economic feasibility of the proposed process, we evaluated 9 and 16 catalysts for direct and indirect ethylene production, respectively. The energy demand of the DBD plasma reactor was estimated using an equivalent electrical circuit model. Most importantly, the levelized costs of ethylene production are assessed by technoeconomic analysis associated with individual system components, based on the two different ethylene production strategies. Furthermore, sensitivity analysis showed a potential linkage with the electricity produced from a renewable energy system. The results of this analysis support the feasibility of the DBD plasma-assisted catalytic reaction process integrated with ECC for energy-efficient CH4-conversion into high-value products.

A Short-run Indirect Production Function

A Short-run Indirect Production Function

Indirect Z-scheme hydrogen production photocatalyst based on two-dimensional GeC/MoSi2N4 van der Waals heterostructures

The stacked two-dimensional materials with suitable band gap are crucial for photocatalytic hydrogen production. Here, using first-principles calculations, the GeC/MoSi2N4 heterojunction with a band gap of 1.80 eV is calculated thoroughly. The indirect band alignment of Z-scheme and high carrier mobility boost the separation of electron-hole pairs, allowing more electrons and holes participating in the reactions. Additionally, the band-edge potential perfectly satisfies the requirements for redox potential of water splitting. Furthermore, the Gibbs free energy (−0.552 eV) close to zero indicates the heterojunction can conduct HER exceedingly well, providing a guarantee for photocatalytic hydrogen production. Remarkably, the light absorption coefficient peak is about 1.39 × 105 cm−1 within the visible light range enables the heterojunction to absorb more visible light from the spectrum. In short, results demonstrate the GeC/MoSi2N4 heterojunction is a promising photocatalyst for visible light water splitting, which will pave the way for the development of water splitting hydrogen production.

Investigation of Z-boson decay into and baryons within the NRQCD factorization approach* *Supported in part by the Natural Science Foundation of China (12265010) and the Project of Guizhou Provincial Department of Education (KY[2021]030)

Z-boson decay provides a good opportunity to search for the baryon because a large number of its events can be collected at high energy colliders. In this paper, we perform a complete investigation of the indirect production of the and baryons via the Z-boson decay process with a quark under the NRQCD factorization approach. After considering the contribution from the diquark states , , , and , the calculated branching fractions are and . Furthermore, the and production events are predicted to be of the order of and at the LHC collider, and the order of and for the CEPC collider. We then estimate the production ratio for with in Z-boson decay, that is, and , respectively. Finally, we present the differential decay widths of and with respect to and z distributions and analyze the uncertainties.

Nano Yttrium-90 and Rhenium-188 production through medium medical cyclotron and research reactor for therapeutic usages: A Simulation study

The main goal of the coordinated project development of therapeutic radiopharmaceuticals of Y-90 and Re-188 is to exploit advancements in radionuclide production technology. Here, direct and indirect production methods with medium reactor and cyclotron are compared to evaluate derived neutron flux and production yield. First, nano-sized 186W and 89Y specimens are suspended in water in a quartz vial by FLUKA simulation. Then, the solution is irradiated for 4 days under 9E+14 n/cm2/s neutron flux of reactor. Also, a neutron activator including three layers—lead moderator, graphite reflector, and polyethylene absorbent— is simulated and tungsten target is irradiated by 60 MeV protons of cyclotron to generate induced neutrons for 188W and 90Sr production via neutron capture. As the neutron energy reduced, the flux gradually increased towards epithermal range to satisfy (n/2n,γ) reactions. The obtained specific activities at saturation were higher than the reported experimental values because the accumulated epithermal flux and nano-sized specimens influence the outcomes. The beta emitters, which are widely utilized in brachytherapy, appeal an alternative route to locally achieve a rational yield. Therefore, the proposed method via neutron activator may ascertain these broad requirements.

Boundedness in a chemotaxis-fluid system involving a gradient-dependent flux limitation and indirect signal production mechanism

This paper is concerned with the Keller-Segel-Stokes system(⁎){nt+u⋅∇n=Δn−∇⋅(nf(|∇v|2)∇v),vt+u⋅∇v=Δv−v+w,wt+u⋅∇w=Δw−w+n,ut=Δu+∇P+n∇ϕ,∇⋅u=0, under no-flux/no-flux/no-flux/Dirichlet boundary conditions in smoothly bounded domains Ω⊂R3, with given suitably regular functions f and ϕ, as well as f satisfies f(|∇v|2)≤Kf(1+|∇v|2)−α2. It is shown that for all suitably regular initial data an associated initial-boundary value problem (⁎) possesses a globally defined bounded classical solution provided α>14. We underline that the same results were established for the corresponding system with direct signal production in a well-known result if α>12 in [50]. Our result rigorously confirms that the indirect signal production mechanism genuinely contributes to the global solvability of the three-dimensional Keller-Segel-Stokes system.

Global existence and boundedness of solutions to a two-species chemotaxis-competition system with singular sensitivity and indirect signal production

Global existence and boundedness of solutions to a two-species chemotaxis-competition system with singular sensitivity and indirect signal production

Persistence and boundedness in a two-species chemotaxis-competition system with singular sensitivity and indirect signal production.

This paper deals with a two-species chemotaxis-competition system involving singular sensitivity and indirect signal production: $ \begin{equation*} \begin{cases} u_{t} = \nabla\cdot(D(u)\nabla u)-\chi_1\nabla\cdot(\frac{u}{z^{k}}\nabla z)+\mu_1 u(1-u-a_1v), &x\in\Omega,\ t>0,\\ v_{t} = \nabla\cdot(D(v)\nabla v)-\chi_2\nabla\cdot(\frac{v}{z^{k}}\nabla z)+\mu_2 v(1-v-a_2 u), &x\in\Omega,\ t>0,\\ w_{t} = \Delta w-w+u+v,&x\in\Omega,\ t>0,\\ z_{t} = \Delta z-z+w,&x\in\Omega,\ t>0,\\ \end{cases} \end{equation*} $ where $ \Omega\subset R^{n} $ is a convex smooth bounded domain with homogeneous Neumann boundary conditions. The diffusion functions $ D(u), D(v) $ are assumed to fulfill $ D(u)\geq(u+1)^{\theta_1} $ and $ D(v)\geq(v+1)^{\theta_2} $ with $ \theta_1, \theta_2 > 0 $, respectively. The parameters are $ k\in (0, \frac{1}{2})\cup (\frac{1}{2}, 1] $, $ \chi_ {i} > 0, (i = 1, 2) $. Additionally, $ \mu_{i} $ should be large enough positive constants, and $ a_i $ should be positive constants which are less than the quantities associated with $ |\Omega| $. Through constructing some appropriate Lyapunov functionals, we can find the lower bounds of $ \int_{\Omega}u $ and $ \int_{\Omega}v $. This suggests that any occurrence of extinction, if it happens, will be localized spatially rather than affecting the population as a whole. Moreover, we demonstrate that the solution remains globally bounded if $ \min\{\theta_1, \theta_2\} > 1-\frac{2}{n+1} $ for $ n\geq2. $.

Global boundedness of classical solutions to a Keller-Segel-Navier-Stokes system involving saturated sensitivity and indirect signal production in two dimensions

<abstract><p>This paper is concerned with the following Keller–Segel–Navier–Stokes system with indirect signal production and tensor-valued sensitivity:</p> <p><disp-formula> <label/> <tex-math id="FE11111"> \begin{document}$ \left\{\begin{array}{*5{lllll }} n_{t}+u \cdot \nabla n=\Delta n-\nabla \cdot(n S(x,n,v,w) \nabla v), \quad &x \in \Omega, t>0, \\ v_{t}+u \cdot \nabla v=\Delta v-v+w, \quad &x \in \Omega, t>0, \\ w_{t}+u \cdot \nabla w=\Delta w-w+n, \quad &x \in \Omega, t>0, \\ u_{t}+\kappa(u \cdot \nabla) u+\nabla P=\Delta u+n \nabla \phi, \quad &x \in \Omega, t>0, \\ \nabla \cdot u=0, \quad &x \in \Omega, t>0, \end{array}\right. \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (♡)$\end{document} </tex-math> </disp-formula></p> <p>in a bounded domain $ \Omega\subset \mathbb{R}^2 $ with smooth boundary, where $ \kappa \in \mathbb{R} $, $ \phi \in W^{2, \infty}(\Omega) $, and $ S $ is a given function with values in $ \mathbb{R}^{2\times2} $ which satisfies $ |S(x, v, w, u)|\leq C_{S}(n+1)^{-\alpha} $ with $ C_{S} > 0 $. If $ \alpha > 0 $, then for any sufficiently smooth initial data, there exists a globally classical solution which is bounded for the corresponding initial-boundary value problem of system (♡).</p></abstract>

Boundedness in a three-dimensional chemotaxis-Stokes system involving a subcritical sensitivity and indirect signal production

Boundedness in a three-dimensional chemotaxis-Stokes system involving a subcritical sensitivity and indirect signal production

Long time behavior of the solution to a chemotaxis system with nonlinear indirect signal production and logistic source

This paper is devoted to studying the following quasilinear parabolic-elliptic-elliptic chemotaxis system { u t = ∇ ⋅ ( φ ( u ) ∇ u − ψ ( u ) ∇ v ) + a u − b u γ , x ∈ Ω , t > 0 , 0 = Δ v − v + w γ 1 , x ∈ Ω , t > 0 , 0 = Δ w − w + u γ 2 , x ∈ Ω , t > 0 , with homogeneous Neumann boundary conditions in a bounded and smooth domain Ω ⊂ R n ( n ≥ 1 ) , where a , b , γ 2 > 0 , γ 1 ≥ 1 , γ > 1 and the functions φ , ψ ∈ C 2 ( [ 0 , ∞ ) satisfy φ ( s ) ≥ a 0 ( s + 1 ) α and | ψ ( s ) | ≤ b 0 s ( 1 + s ) β − 1 for all s ≥ 0 with a 0 , b 0 > 0 and α , β ∈ R . It is proved that if γ − β ≥ γ 1 γ 2 , the classical solution of system would be globally bounded. Furthermore, a specific model for γ 1 = 1 , γ 2 = κ and γ = κ + 1 with κ > 0 is considered. If β ≤ 1 and b > 0 is large enough, there exist C κ , μ 1 , μ 2 > 0 such that the solution ( u , v , w ) satisfies ‖ u ( ⋅ , t ) − ( b a ) 1 κ ‖ L ∞ ( Ω ) + ‖ v ( ⋅ , t ) − b a ‖ L ∞ ( Ω ) + ‖ w ( ⋅ , t ) − b a ‖ L ∞ ( Ω ) ≤ { C κ e − μ 1 t , if κ ∈ ( 0 , 1 ] , C κ e − μ 2 t , if κ ∈ ( 1 , ∞ ) , for all t ≥ 0. The above results generalize some existing results.

ПРОГНОЗНІ ОЦІНКИ ВРОЖАЙНОСТІ ТА НЕПРЯМИХ ВТРАТ ВИРОБНИЦТВА ОСНОВНИХ СІЛЬСЬКОГОСПОДАРСЬКИХ КУЛЬТУР В УКРАЇНІ У 2023 РОЦІ В УМОВАХ ВОЄННОГО СТАНУ

Summary The purpose of the work is to highlight the results of forecasting the yield and production of the main agricultural crops in 2023 based on the operational data of remote agromonitoring and the assessment of indirect losses of the gross harvest of grain and leguminous crops in Ukraine under martial law. Methods and materials. Predictive estimates of the yield of agricultural crops are calculated on the basis of statistical data on their productivity for the period 2000-2022 and remote agricultural monitoring data (NDVI indices) on the state of crops in Ukraine in the spring of 2023. Standard methods of correlation-regression analysis were used to establish relationships between NDVI indicators and regional average yield values of the main field crops. Potential indirect production losses of the group of grain and leguminous crops in Ukraine in 2023 were calculated based on the dynamics of the reduction of sowing and harvesting areas in the conditions of martial law and, accordingly, from the losses for the country’s agrarian sector due to the lack of potential profit from the sale of grain, estimated at domestic purchase prices. Results. According to estimates based on actual winter sowing volumes and spring sowing rates, the harvested area of grain and leguminous crops in 2023 is expected to be about 10.4 million hectares. The average yield of grain and leguminous crops in Ukraine as a whole is predicted with a probability of 80-85% at the level of 47-49 t/ha, which according to preliminary estimates is close to last year’s value and the average indicators of the pre-war level. At the same time, the gross harvest of grain and leguminous crops is expected at the level of 48.4-50.5 million tons, compared to the average pre-war level of 75 million tons. That is, the losses from military aggression only for the loss of production of this group of crops currently reach about 25-24 million tons or more than UAH 150 billion. Conclusions. Military aggression against Ukraine will have negative consequences for the cultivation of agricultural crops in 2023, mainly due to the shortage of mineral fertilizers, pesticides and other means of production, the general reduction of sown areas and a number of other negative economic consequences, however, the projected production volumes of grain crops are currently sufficient to ensure needs of the Ukrainian population.

Indirect Production of Chromium Carbides Film on Low Alloy Steel

Chromium carbide coatings deposited on mechanical parts by different techniques have an interesting hardness, wear-resistant and corrosion resistance. Some studies show that chromium carbides produced by physical vapor deposition methods and revealed a superior hardness present a poor adherence to their substrates. The objective of this study is to indirectly obtain a hard, and adherent coating of chromium carbide by using a conversion treatment including carburizing treatment of steel substrate, deposition of a pure chromium layer, and annealing treatment of coated carburized steel under a carbonic gas atmosphere. Treatment temperature has an effect on the partial or complete conversion of chromium film as a result of the diffusion and precipitation process. The transformation rate of chromium into both chromium carbide layers was investigated. For 1 h of holding treatment, chromium film was totally transformed at 900 °C into chromium carbide film which presented high hardness and excellent adhesion.