Input Flow Research Articles

Development of a mathematical model for a compound technological complex of vanyukov melting in order to control the material and thermal regime

This article presents a mathematical model in the form of static equations of dependencies of input and output flows based on the equations of material and heat balance for the purposes of operational planning and control of the complex technological complex of Vanyukov melting (PV). Dynamic characteristics are presented for the purpose of controlling the thermal regime based on the technology of the developed melting process with blowing from below. As a result of the study, the developed mathematical model for controlling the smelting process when calculating the material flows of the charge will allow tracking changes in the thermal state of the smelting (by the copper content in the matte). This model can quite well describe the dynamics of the state of the process, both when establishing the impacts aimed at increasing the heating of the furnace, and at reducing its heating. Based on the equations, a computer model based on the dynamic programming method in the MATLAB software package has been developed. The scientific novelty lies in the fact that for the first time, the structure of a mathematical model has been developed that describes the processes occurring in the over-tuyere zone and the sludge zone of the smelting products.

Monitoring soil erosion on field slopes by terrestrial laser scanning and structure‐from‐motion

AbstractTerrestrial laser scanning (TLS) and structure‐from‐motion (SfM) photogrammetry are prevalent erosion monitoring techniques. However, their relative performance for field erosion monitoring remained unclear. In the study, five souring experiments were implemented on each of the three plots, consisting of hillslope and gully area, established on field slopes. The input flow for three hillslopes was 25, 55, and 85 L min−1 respectively while that for the gully area was 10 L min−1. TLS and SfM were used to monitor erosion processes, while their performance was assessed using manual measurements. Results showed that TLS and SfM produced generally sound and comparable soil loss estimates, with relative errors (REm) for the cumulative and consecutive sediment yield derived by the two techniques being −24.10% to +84.50% and −29.60% to +73.10% respectively. TLS estimated sediment yield more accurately than SfM for more intensively eroded areas, while the estimation accuracy of TLS was lower than SfM for less intensively eroded areas. On gully slopes, the two techniques broadly captured the spatial pattern of erosion and deposition, with inconsistency/errors emerging on areas with small topographic changes or caves; TLS generally produced more accurate rill length than SfM, with the REm for TLS being −2.18% to −0.16% and the REm for SfM being −7.09% to −1.49% respectively. TLS‐ and SfM‐derived rill networks were broadly consistent (Kappa coefficient was 0.42–0.79) and different in details. The SfM‐ and TLS‐derived level of detection was generally at the same order of magnitude. However, their spatial pattern on hillslopes was rather different, which informed a different erosion monitoring capacity of TLS and SfM on field hillslopes and needs further study. Overall, SfM provides a cost‐effective and powerful alternative to TLS for field erosion monitoring and a combined use of them may produce more satisfactory results.

Nature-based solutions for wastewater treatment and bioenergy recovery: A comparative Life Cycle Assessment

The aim of this study was to assess the environmental impacts of up-flow anaerobic sludge blanket (UASB) reactors coupled with high rate algal ponds (HRAPs) for wastewater treatment and bioenergy recovery using the Life Cycle Assessment (LCA) methodology. This solution was compared with the UASB reactor coupled with other consolidated technologies in rural areas of Brazil, such as trickling filters, polishing ponds and constructed wetlands. To this end, full-scale systems were designed based on experimental data obtained from pilot/demonstrative scale systems. The functional unit was 1 m3 of water. System boundaries comprised input and output flows of material and energy resources for system construction and operation. The LCA was performed with the software SimaPro®, using the ReCiPe midpoint method. The results showed that the HRAPs scenario was the most environmentally friendly alternative in 4 out of 8 impact categories (i.e. Global warming, Stratospheric Ozone Depletion, Terrestrial Ecotoxicity and Fossil resource scarcity). This was associated with the increase in biogas production by the co-digestion of microalgae and raw wastewater, leading to higher electricity and heat recovery. From an economic point of view, despite the HRAPs showed a higher capital cost, the operation and maintenance costs were completely offset by the revenue obtained from the electricity generated. Overall, the UASB reactor coupled with HRAPS showed to be a feasible nature-based solution to be used in small communities in Brazil, especially when microalgae biomass is valorised and used to increase biogas productivity.

Hydrogen from catalytic non-thermal plasma-assisted steam methane reforming reaction

Steam methane reforming reaction was carried out in a dielectric barrier plasma reactor. A systematic study is conducted to understand the influence of input power, flow rate, and water for the conversion, yield, and selectivity of the reaction over strategically designed catalysts. In particular, the production rate and selectivity of the products (H2, CO and C2 hydrocarbons) are monitored. CeO2 was used as packing material, mixed with oxides of manganese or copper and their combination. The optimum Cu/CeO2 catalyst illustrated the production rate of 248.7 μmolg−1h−1 and 11.25 μmolg−1h−1 for H2, and CO, respectively at specific energy input of 19.8 JL-1. DFT calculations exhibit apparent change in electronic structure of the CeO2 after inclusion of oxides of manganese and copper that enhance interaction with methane. Based on these findings, a plausible mechanism is elucidated which can help to design catalyst for other applications in non-thermal plasma atmosphere.

Experimental test analysis of hydram pump flow rate using L9 Taguchi at fish pond aquaculture

Good water quality in fish nursery cultivation greatly influences the harvest quality. Temperature and Ph can be maintained properly with proper air circulation. The main problem is that the best flow rate quality in fish ponds of 0.123m3/second is only achieved through the flow from the dam. In this study, the installation of hydram pumps in fish ponds was carried out with the angle of assessing the inflow and discharge to adjust to variations in the diameter of the inlet and outlet pipes, the height of the inlet pipe, and the height of the tank. The experimental design used L9 orthogonal array Taguchi with four replicas. The result of this study was that the maximum value of the input flow rate was 305.73 cm3/second, and the discharge flow rate was 40.35 cm3/second. The maximum value was in the 8th composition; namely, the variation of the inlet pipe height was 200 in, the outlet pipe height was 350 cm, the inlet pipe diameter was 1 in, and the outlet pipe diameter was ½ in.

Management of self-healing processes of computer nodes of the information circuit of hydraulic systems with template changes in the input flow of applications

This article discusses the approaches of managing the processes of self-healing of computer nodes of the information circuit of hydraulic systems with pattern changes in the input flow of applications. The approach is based on the use of queuing systems. The application of the proposed approach to all computer nodes of the information infrastructure of hydraulic systems makes it possible to improve the efficiency of complex hydraulic systems as a whole.

Life cycle assessment of a novel strategy based on hydrothermal carbonization for nutrient and energy recovery from food waste

In this work, a novel strategy for food waste valorization was evaluated from an environmental life-cycle perspective. A system based on acid-assisted hydrothermal carbonization of food waste combined with the exploitation of hydrochar by combustion and process water through nutrient recovery stage and subsequent anaerobic digestion, was assessed and compared with stand-alone anaerobic digestion as the reference system. This combination of processes aims to recover both nutrients in a stage of struvite precipitation from process water and energy through hydrochar and biogas combustion. Both systems were modeled in Aspen Plus® to identify and quantify their most relevant input and output flows and subsequently evaluate their environmental performance through the life cycle assessment methodology. The novel combined system was found to generally involve a more favorable environmental performance than the reference stand-alone configuration, which would be closely linked to the substitution of hydrochar for fossil fuels. In addition, the impacts associated with soil application of the struvite produced in the integrated process would also be reduced compared to the use of the digestate generated in the stand-alone anaerobic digestion process. Following these results and the evolving regulatory framework for biomass waste management, mainly in the field of nutrient recovery, combined process based on acid-assisted hydrothermal treatment plus nutrient recovery stage and anaerobic digestion is concluded to be a promising circular economy concept for food waste valorization.

Scenario analysis of phosphorus flow in food production and consumption system in the Mwanza region, Tanzania

Since the mineral, phosphorus (P), has dual properties of being limited resources for use, and being a pollutant for studying sustainable management of anthropogenic P flows in wetlands and soils, currently P receives the highest interests among researchers around the world. This study has successfully mapped P flows for a reference year (2017) and a future year (2030) using different scenarios of food production and consumption system (hereafter ‘system’) in the Mwanza region (Tanzania). The results showed that the total P input and output for 2017 alone were 9770 t and 7989 t, respectively. However, as high as 1781 tP accumulated in the system and the potentially recyclable P found, is yet to be recovered due to economic reasons and the lack of market. The main anthropogenic P input to the system occurred via imported feed, fertilizer, and crop food, accounting for about 99.72 % of the total input flow. The output was comprised of animal products exported with 3428 tP, and various P-contained wastes which were lost to water bodies with 4561tP. Analysis of the 2030 scenario showed that setting P management objectives from different perspectives such as the total P budget balance, potential recyclable P, and P emission, can help develop differentially preferred management strategies and measures in the Mwanza region. The combination of diet change, precision feeding, and integrated waste management practices presents the best prospects for decreasing P budget and losses, and the amount of P that can be potentially recovered from the system. We propose a package of integrated P management measures for the Mwanza region. Given the similarity of regional socio-economic development background around the Lake Victoria basin, the model can be used to guide the study of anthropogenic P flow analysis in other areas along the shore of Lake Victoria (Africa).

Investigation of Histamine Removal by Electrodialysis from the Fermented Fish Sauce and Its Effects on the Flavor.

Histamine is one of the most concerned safety indicators in fish sauce. Considering its charge property, electrodialysis (ED) was used to control the histamine in fish sauce, and studies were focused on three operating parameters: input current, pH, and flow velocity. A Box-Behnken design and response surface methodology was adopted to derive a statistical model, which indicated that 5.1 A input current, pH 3.8, and 40 L∙h-1 flow velocity were optimal operation conditions. Under this condition, the histamine removal rate reached 53.41% and the histamine content met the allowable histamine limit of below 400 mg·kg-1 in fish sauce, while the amino nitrogen (ANN) loss rate was only 15.46%. In addition, amino acids and volatile compounds changed differently during ED. As a result, with decreased histamine, the fish sauce after ED was also less salty and less fishy. The study first explored utilizing ED to remove histamine from fish sauce, which has positive implications for promoting the safety of aquatic products.

RELAP5-CFX COUPLING MODULE: TESTING ON SIMPLE THERMOHYDRAULIC MODELS

The modern direction in the study of the safety of nuclear power plants is to ensure the maximum level of detail in process modeling with a satisfactory level of computational resources. One of the approaches of such task solving is the coupled use of special software with the required levels of detail, for example, systemic thermohydraulic codes with computational hydrodynamics codes.
 This article describes the developed coupling module between the system thermohydraulic code RELAP5/Mod. 3.2 and the CFX computational hydrodynamics code, using an external explicit interfacing scheme without overlap, in which CFX acts as the main code and RELAP5 as the secondary one. The development of this module is part of the work on integrated coupled modeling of severe accidents and makes it possible to model the defining processes and phenomena that occur during a severe accident within the reactor vessel using the CFD model, and the elements of the reactor unit using the RELAP5 model with an acceptable cost of resources and with a high level of detail. To check the coupling technology, the module was tested on simplified models containing serially connected RELAP5- and CFD-models of horizontal pipes, as well as on a closed loop. In view of the further use of the interface module on a full-fledged model of the VVER-1000, testing is performed for three main interface types: "input flow", "output flow" and their combination "input/output flow" on a closed loop. After completion of the testing, the accuracy and credibility of the results of the coupled calculations was evaluated by comparing them with the results of autonomous RELAP5 calculations. Results of the tests calculations support the possibility of using the RELAP5-CFX coupling module on more complex and large-scale RELAP5 and CFD models.

Effect of non-thermal plasma dielectric barrier discharge reactor on the quality of biomass gasification product gas from the gasifier

The primary goal of this research is to determine the effect of key processing parameters of dielectric barrier discharge (DBD) reactor on the components concentration of the fuel gas produced during the biomass gasification. By changing key processing parameters such as plasma input power, flow rate, and temperature, the performance of the DBD reactor is assessed. When the power is increased from 5 to 40 W, the concentrations of CO2 and H2 decrease to 12.9% and 18.5%, respectively, while the concentration of CO increases to 17.2%. At 40 W and 65 ml/min, the amount of tar compound significantly drops from 33 g/Nm3 to less than 1 g/Nm3. However, as input power increases, the concentration of C1–C5 hydrocarbons also tends to rise. The highest concentration of C1–C5 was around 0.60% at 40 W. As the flow rate increases, the concentration of CO2 increases while the concentration of CO tends to decrease at all measured power levels, the maximum concentration of CO2 was at 120 ml/min, whereas the minimum concentration of CO is seen under same conditions. With an increase in flow rate, the concentration of CH4 shows a decreasing tendency. It is seen that at 40 W, the concentration of CO and H2 drops as the temperature rises up to 400 °C. In contrast, there is a rising trend in the concentration of CO2, CH4, and tar compounds while increasing temperature. Hence, the DBD reactor appears to have a profound influence on a gas component produced during biomass gasification.

Dynamic Modeling of the Trophic Status of an Urban Tropical Wetland under ENSO Conditions

The climate variability associated with the ENSO phenomenon has a significant impact on wetlands, affecting the total precipitation input and hydrological flows of these ecosystems. The objective of this paper is to study the trophic status variation of an urban tropical wetland under ENSO conditions, through dynamic modeling. The results suggest an increase in precipitation, by 3.32 times, during the La Niña phase compared to the El Niño phase. Wetland input total phosphorus (TP) concentrations are 1.85 times lower during La Niña. This is probably due to a dilution effect exerted by the increase in surface runoff volumes from the basin. The findings suggest a reduction in wetland hydraulic retention time (HRT) during La Niña (1.33 times) compared to El Niño. This trend causes the TP concentration inside the wetland to decrease, possibly due to an increase in the water volume stored (dilution), and by the exit of this nutrient due to a shorter hydraulic renewal (HRT/La Niña < HRT/El Niño). The occurrence of a high input of TP concentration to the wetland does not necessarily indicate a high trophic status index (TSI). This is because the trophic status of the wetland is possibly more associated with HRT rather than input TP concentration. The trophic status of the wetland during the La Niña tends to be eutrophic. Lastly, under ENSO scenarios, the use of Aizaki’s method is suggested, because it considers HRT as a decisive factor for the calculation of wetland trophic status.

Numerical simulation on the deposition characteristics of MSWI fly ash particles in a cyclone furnace

In melting municipal solid waste incineration (MSWI) fly ash by cyclone furnace, the deposition characteristics of particles affect the slag flow and the secondary MSWI fly ash formation. In this study, the composition mechanism based on critical viscosity is selected as the particle deposition model to predict the deposition and rebound of particles on the furnace wall. The Riboud model with an accurate viscosity prediction performance is selected, then the particle deposition model is integrated into a commercial computational fluid dynamics (CFD) solver through the user-defined function (UDF) to realize the coupling of particle motion and deposition process. The results show that under the same case, the deposition rate decreases obviously with the increase of MSWI fly ash particle size. And the escape rate reaches a maximum at particle size 120 μm. Controlling the particle size of fly ash particles within 60 μm can effectively reduce the generation of secondary MSWI fly ash. During the forward movement of the fly ash inlet position, the escape of MSWI fly ash particles with large particle sizes has been significantly weakened. This measure not only lowers the post-treatment cost but also dramatically reduces the pretreatment step of MSWI fly ash before the melting and solidification process. In addition, the deposition rate and quality will reach the maximum values, respectively, along with gradually increasing MSWI fly ash input flow. Overall, this study has the guiding significance for reducing the pretreatment steps and post-treatment costs of MSWI fly ash by melting in the cyclone furnace.

Understanding the influence of fluid flow regime on plasma morphology and dose delivery at the plasma–liquid interface

Plasma-based water purification involves the transport of reactive species across the gas–liquid interface. This process is limited by slow diffusion driven mass transport of reactive species across the interface. Additionally, the plasma gas–liquid contact area is typically limited, contributing to reduced dose delivery. These key factors make it difficult to scale up the treatment process to input flows of industrial interest. In this work, turbulence is explored as a means to introduce a fine grain structure, thus greatly increasing the interfacial surface area, leading to large property gradients and more efficient mass transport. Such a fine scale structure can also enhance the local electric field. The test apparatus explored in this work is the packed bed reactor that places thin water jets into contact with plasma. It is theorized that introducing turbulence, via increasing Reynolds number in such thin jets, may enhance the effective plasma dose at fixed plasma power. In this work, changes in the flow regime, from laminar to turbulent, of water jets in a packed bed water reactor (PBR) configuration are investigated experimentally. Methylene blue dye, a model contaminant, was tested in the PBR to demonstrate enhanced treatment via reduced treatment times. Plasma surface morphology around the jets noticeably changed with the flow regime, and turbulent flow demonstrated a faster hydrogen peroxide uptake, along with slower temperature, electrical conductivity, and a pH change in a batch treatment process, compared to laminar flow. The dye was destroyed significantly faster in the turbulent flow, indicating an increased effective plasma dose.

Dynamic areas strategy design for variable speed limiting at fixed freeway bottlenecks

Variable speed limit (VSL) control of freeway traffic is expected to improve traffic mobility and safety, especially at bottlenecks. However, unstable input flow makes the VSL less effective when the number of speed limit areas is fixed. In this paper, we first analyze the speed limit effect of the fixed speed limit area, then strengthen the VSL control effect by changing the number of speed limit areas, and finally propose a dynamic speed limit area strategy. This strategy redefines the speed limit areas and divides them into three types: normally open speed limit area, auxiliary speed limit area, and buffer speed limit area, which takes into account the transmission capability of the road and alleviates the speed difference. The effects of the VSL control strategy are evaluated using a cell transmission model. The proposed strategy uses the predictive control method to optimize the speed limit value and the number of speed limit areas. Two scenarios that considered both stable and fluctuating traffic demands are evaluated. The results show that the dynamic speed limit areas strategy can improve the safety and efficiency of the freeway.

Optimal threshold strategies for retrial systems with queue

In this article, we deal with Markov models of multi-channel [M|M|m|m+n](∞)–systems with repeated calls and queues with a variable rate of input flow controlled by threshold strategies without restrictions on the capacity of the orbit. An effective calculating algorithm for the characteristics of such systems in stationary regimes is proposed. First, stationary probabilities for a truncated model are investigated. Second, the obtained result is extended to a general model with an infinite number of servers. For threshold control strategies the optimization problem of the total income of the system is formulated and solved. In a particular case with one server and one place in the queue, the direct formulas for stationary probabilities are obtained, and the rate of convergence of the stationary distribution of a finite system to that of an infinite system under threshold strategies are estimated.

Accuracy of Estimation of the Vector of Queue Lengths for Open Jackson Networks

The accuracy of approximation of the vector of queue lengths for an open Jackson network with regenerative input flow and unreliable servers is estimated. A theorem on the accuracy of approximation of the vector of queue lengths in open Jackson networks is put forward, i.e., an estimate for the probability of deviations of the norm of the difference between the process of queue lengths and the constructed reflected Brownian motion is obtained. As a corollary, an estimate of the Wasserstein distance is given.

On Friction, Heat Input, and Material Flow Initiation during Friction Stir Welding: Tool and Process Optimization

The Friction Stir Welding (FSW) process depends entirely upon mechanical contact between the tool and the workpiece. As a result of this, all process phenomena and process outcomes such as weld geometry and mechanical properties are governed by FSW’s frictional system. The following work characterizes this system with a focus on process initialization, heat input and material flow. For this purpose, an experimental program for the isolated investigation of the frictional system was carried out. Short-term effects such as contact initiation, run-in behavior and frictional transitions are considered as well as the influences of process parameters and geometry. The system and its behavior are analyzed quantitatively and qualitatively by experiments altering the normal pressure, relative velocity, and tool geometry. The experiments demonstrate a self-similar behavior of the process, including an important wear transition which initiates the material flow, and a subsequent equilibrium of forces, heat balance, and temperatures. The interaction between the tool and the welded material is described, as is the link between the frictional interface and material flow initialization. Based on these findings, recommendations are provided for process optimization and tool design.

Piezoelectric micropump with integrated elastomeric check valves: design, performance characterization and primary application for 3D cell culture.

This paper reports on the study of a piezoelectric actuated micropump with integrated elastomeric check valves that can transport small amounts of fluid in a highly controllable manner. The proposed micropump consists of a piezoelectric actuated fluid chamber with two integrated elastomeric check valves for regulating input and output flow direction, while restricting backflows. The actuation, fluid dynamic response and fluid-structure interactions at various working cycles are studied through a fully coupled multiphysics simulation (solid mechanics, electrostatic and fluid flow). The pump bodies are manufactured by micromachining of PMMA sheets, while the middle elastomeric membrane and diaphragm are fabricated by spin-coating PDMS. The experimental results confirm that the micropump can provide sufficiently low-velocity outflow for biomedical applications between 3.4 - 41.8µl/min. The performance of the micropump is improved significantly through a convenient geometric modification of an off-the-shelf piezoelectric brass disc. Furthermore, the combination of this micropump with the 3D cell-culture microfluidic chip realizes the dynamic culture of cells encapsulated in 3D hydrogels with a continuous flowing medium, which offers the potential for changing the traditional mode of 3D cell culture with a static supply of nutrition and factors.

Design and Construction of a Prototype for Arsenic Retention in Mining-Contaminated Waters by Application of Nanoparticles-Based Technosols

A large number of heavy metals are usually contained in mine-derived liquids, which could cause contamination of surrounding water sources. Due to the detrimental effects on the environment and health, conventional treatments have been employed to capture heavy metals in mining-polluted streams. This study shows the results of the operation of a built prototype for the retention of arsenic contained in waters contaminated by mining activities using Technosols (mixtures of local soil with nanoparticles). Our team previously run laboratory tests using fixed-bed columns to find out the best dose of the Technosol (97% soil + 3% nanoparticles). Based on these results, the sizing and building of a scale model were conducted, which in turn was used to evaluate the performance of the treatment in a concrete channel packed with reactive barriers. Variations in water volume, barrier separation and gate opening were tested to analyze the behavior of the proposed system and to obtain the most optimal hydraulic retention time that allowed the prototype to reach an arsenic retention level of a minimum of 70%. Moreover, to analyze the procedure under conditions of high arsenic contamination, samples of mine tailings were enriched with the toxic metalloid. It was found that the content of Fe in the local soil allowed adsorption of the contaminant, which was subsequently compared with the increase in the uptake of As due to the Fe/FeS multicomponent nanoparticles (NPs), dosed in the Technosol in a proportion of 97% soil + 3% NPs. The best treatment achieved 70.5% of As removal in ten cycles with a volume of 44 L. Tests were run at a maximum input flow rate of 43.8 L·min−1, an output flow rate of 13.2 L·min−1, a speed of 6.0 m·min−1 and a hydraulic retention time of 3.4 min per cycle. Results of arsenic retention using this prototype suggest that this simple and inexpensive technological setup could be scaled up to a functional field application to effectively capture the toxic metalloid.