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The performance of electrocoagulation (EC) was studied by conducting experiments for the removal of Reactive Orange 4 dye from its synthetic aqueous solution. The effect of operational parameters (initial solution pH, current density, inter-electrode distance, electrolysis time and retention time, solution temperature, conductivity and different electrode combinations) on the efficiency of EC was studied and the results were analysed in terms of colour removal efficiency (CRE), electrical energy consumption (EEC) and operating cost (OC). The effect of different anions on the efficiency of EC was studied by conducting experiments with electrolytes containing chloride, sulphate, carbonate and nitrate ions. The characterisation of EC generated sludge was performed using XRD. A maximum CRE of 95% was obtained for EEC of 1.7 kWh/m3 and OC of 0.45 US $/m3. It was found that the addition of electrolyte containing chloride ions resulted in higher CRE (93–95%) compared to electrolytes containing sulphate and carbonate ions as their presence can lead to passivation of the electrode surface & thereby resulting in a reduction in CRE (60% and 41%, respectively). The addition of sodium chloride as an electrolyte resulted in minimum EEC and OC. The Al/Al electrode combination provided the maximum CRE and least EEC & OC. The increase in solution temperature leads to reduction in CRE and CE due to formation of passive layer on the surface of electrodes. However, a reduction in cell potential and EEC was noticed with an increase in solution temperature. [ABSTRACT FROM AUTHOR]

Abstract This paper presents the effect of environmentally friendly additives on selected parameters and microbial degradation of Marine Diesel Oil (MDO). Microbiological contamination is a serious problem in MDO and other petroleum products. For this reason, it was decided to investigate the effects of environmentally friendly additives such as silver solution and colloidal nanosilver, as well as effective liquid microorganisms and ceramic tubes with different percentages of them in diesel oil (MDO) on its selected parameters and inhibition of bacterial and fungal growth. The tests were conducted on a mixture of fuel with four types of environmentally friendly additives at concentrations of 2% and 5%, and on fuel without any additives. The effect of the additives on selected diesel parameters, including flash point, water content and acid number, as well as density and kinematic viscosity, is presented. The diesel oil was also subjected to microbiological tests. It was found that the most beneficial additive that positively influenced diesel parameters and microbial degradation was a silver solution at a concentration of 2%. The lowest ignition temperature was obtained when ionic silver was used, i.e. 60 °C, which is closest to the value for pure diesel fuel. The addition of effective microorganisms in liquid form to the fuel in an amount of 2%, increases the ignition temperature to 62.2 °C and this is the highest value obtained in comparison with other additives. The lowest water content in the test samples was obtained for the effective microorganisms in ceramic form at − 0.0068%, while the highest value was obtained for the silver solution at 0.0123%. At 100 °C, the highest kinematic viscosity was obtained for EM in ceramic, at 1.11 mm2/s. While for pure oil it was 1.03 mm2/s. For pure diesel, a value of 1.1 × 106 cfu/1 dm3 for bacteria and 7.3 × 103 cfu/1 dm3 was obtained. For each type of mixture, a value of less than 1 × 102 cfu/1 dm3 for bacteria was obtained, while in terms of fungal counts in the mixtures, a decrease of 73 times is also observed for diesel mixed with effective microorganisms in liquid form and ceramics, 48 times less was recorded after the use of non-ionic silver. The use of these additives is an innovative solution that has a positive effect on slowing down microbial degradation, without any loss of diesel performance.

The field of energy harvesting has grown rapidly, with the huge development in low-power devices and the Internet of Things (IoT). With the intent of harvesting electrical energy for self-powered devices, piezoelectric technology is considered. In this study, we proposed several electrical and mechanical improvements to enhance the electrical energy produced through piezoelectricity. To determine the best electrical configuration to harvest piezoelectric energy, three harvesting electric circuits were proposed and tested using a piezoelectric material (PZT-5H) mounted directly on a vibration exciter. The harvested electrical energy by each circuit was determined at different excitation frequencies, from 20 to 50 Hz, with an excitation amplitude of 2 mm. The favorable electric circuit produced approximately 35 μJ of electrical energy at an excitation frequency of 50 Hz. This circuit was subsequently used for the remaining aspects of this work. To enhance the obtained electrical energy, a fixed-free metallic plate was used. First, free vibration was tried, imposing an excitation displacement of different values to the free end of the plate. The plate consisted of different materials: copper, aluminum, and steel. The PZT-5H was mounted at different positions on the plate. The harvested electrical energy was determined for each plate material, each piezoelectric material position, and each excitation displacement. The highest harvested energy was around 6 μJ. Second, forced vibration was tried, imposing an excitation amplitude of 0.5 mm at different excitation frequencies, from 10 to 50 Hz, to the fixed end of the plate. The plate was of different lengths. The highest harvested energy was around 540 μJ. Third, we showed that it is possible to further increase the harvested electrical energy by tuning the plate resonance to 50 Hz. The harvested energy was then around 1010 μJ. The obtained results allowed optimizing piezoelectric energy harvesting toward supplying low-power devices for different applications.

Spraying is currently one of the main methods of pesticide application worldwide. It converts the pesticide solution into fine droplets through a sprayer, which then deposit onto target plants. Therefore, in the process of pesticide application, improving the effectiveness of spraying while minimizing or preventing crop damage has become a key issue. Combining the advantages of electrostatic spraying technology with the characteristics of ground boom sprayers, a contact-type electrostatic boom spraying system based on a rod–plate electrode structure was designed and tested on a self-propelled boom sprayer. The charging chamber was designed based on the characteristics of the rod–plate electrode and theoretical analysis. The reliability of the device was verified through COMSOL numerical simulations, charge-to-mass ratio, droplet size, and droplet size spectrum measurements, and a droplet size prediction model was established. The deposition characteristics in soybean fields were analyzed using the Box–Behnken experimental design method. The results showed that the rod–plate electrode structure demonstrated its superiority with a maximum spatial electric field of 2.31 × 106 V/m. When the spray pressure was 0.3 MPa and the charging voltage was 8 kV, the droplet size decreased by 26.6%, and the charge-to-mass ratio reached 2.88 mC/kg. Field experiments showed that when the charging voltage was 8 kV, the spray pressure was 0.3 MPa, the traveling speed was 7 km/h, and the number of deposited droplets was 8517. This study provides some basis for the application of electrostatic spraying technology in large-scale field operations. [ABSTRACT FROM AUTHOR]

One of the well-known processes utilized in the modern business for permanently identifying products, including specifications and logo branding of any organization or institute, is laser marking. Little effort has been made to optimize the different geometrical characteristics of laser marked surfaces which is needed for applications in laser marking of any product identity. In this work efforts were made to develop the mathematical model of the responses, analyse the parametric influence on the marking characteristics and to find the optimal setting of process variables for marking the surface of 304 stainless steel using a fibre laser with a beam spot diameter of 21 µm. The single- and multi-objective optimization were carried out on the responses using desirability function analysis. Results revealed that for multi-objective optimization a laser power of 10.6 W, duty cycle of 56.86%, scan rate of 7 mm/s and pulse rate of 60 kHz should be set for more advantageous marking features for marking a triangular shape. [ABSTRACT FROM AUTHOR]

A significant and sustainable feedstock for many value added products is levulinic acid, which is basically a short‐chain fatty acid. The current study aims to comprehend how multiple factors affect the hydrothermal reactions that convert glucose to levulinic acid. Glucose can be readily obtained from lignocellulosic biomass and hence it is selected in the work as representative sustainable source. The effect of various operating parameters, including time (0–180 min), temperature (140–180°C), nitrogen pressure (0–25 bar), glucose concentration (3%–10%), agitation speed (100–300 RPM), and acid concentration (2%–6%); use of different salts (NaCl, AlCl3 6H2O, FeCl3); and different acids (HCl, H3PO4, H2SO4) on the reaction progress has been studied in a batch autoclave reactor. It was elucidated that pressure (only nitrogen purge was essential for reaction progress) or salt content changes did not affect sugar conversion significantly. The process was seriously influenced by the presence of acids, mostly in the form of homogeneous catalysts, and the most significant results were obtained for H2SO4. The highest levulinic acid yield (39.7 g/g) at 90 min, with nearly complete sugar conversion, was obtained under the ideal conditions of 160°C, 5% sugar loading, and 5% H2SO4 concentration. The current study indicates that the two primary operating parameters in this conversion process are temperature and time, with higher temperature and lower sugar concentration showing a rising tendency in sugar conversion. Overall, the study establishes a sustainable process for levulinic acid synthesis. [ABSTRACT FROM AUTHOR]

The field of energy harvesting has grown rapidly, with the huge development in low-power devices and the Internet of Things (IoT). With the intent of harvesting electrical energy for self-powered devices, piezoelectric technology is considered. In this study, we proposed several electrical and mechanical improvements to enhance the electrical energy produced through piezoelectricity. To determine the best electrical configuration to harvest piezoelectric energy, three harvesting electric circuits were proposed and tested using a piezoelectric material (PZT-5H) mounted directly on a vibration exciter. The harvested electrical energy by each circuit was determined at different excitation frequencies, from 20 to 50 Hz, with an excitation amplitude of 2 mm. The favorable electric circuit produced approximately 35 μJ of electrical energy at an excitation frequency of 50 Hz. This circuit was subsequently used for the remaining aspects of this work. To enhance the obtained electrical energy, a fixed-free metallic plate was used. First, free vibration was tried, imposing an excitation displacement of different values to the free end of the plate. The plate consisted of different materials: copper, aluminum, and steel. The PZT-5H was mounted at different positions on the plate. The harvested electrical energy was determined for each plate material, each piezoelectric material position, and each excitation displacement. The highest harvested energy was around 6 μJ. Second, forced vibration was tried, imposing an excitation amplitude of 0.5 mm at different excitation frequencies, from 10 to 50 Hz, to the fixed end of the plate. The plate was of different lengths. The highest harvested energy was around 540 μJ. Third, we showed that it is possible to further increase the harvested electrical energy by tuning the plate resonance to 50 Hz. The harvested energy was then around 1010 μJ. The obtained results allowed optimizing piezoelectric energy harvesting toward supplying low-power devices for different applications. [ABSTRACT FROM AUTHOR]

The objective of the present study was to analyze the removal efficiency of red dye 40 by electrocoagulation process using aluminum electrodes. The methodology used includes a first stage taking into account the operating parameters of the electrolyte concentration (0-0.5 g/L NaCl), pH of the solution (4.5-9.1), number of electrodes (2-4), distance between electrodes (1-2 cm), with the best results of this stage, a multilevel factorial experimental design with two variables was performed: (10, 15 and 20) V voltages and electrocoagulation duration of (3, 6, 10, 20, 40 and 60) min. The results show the main role of several parameters to maximize the removal efficiency and minimize the energy consumption. According to the experimental results, the maximum removal efficiency obtained is 85.29 % with an energy consumption of 14.08 kJ. [ABSTRACT FROM AUTHOR]

Intensified cavitation‐assisted biogas production from sustainable feedstock has been discussed describing the working principles and governing mechanisms for intensification. Various methods of biogas production discussed in the work include activated sludge processes, membrane bioreactor (MBR), and processes involving methanogenic and sulfate‐reducing microorganisms. Design aspects of cavitational reactors (sonochemical and hydrodynamic cavitation) have been presented with detailed understanding into effect of several operational parameters, such as the biomass‐to‐water ratio, operating pressure, treatment duration, operating temperature, power dissipation, and so on. Selection of optimum parameters is crucial to improve the performance and observed intensification from such processes. The possible benefits in terms of applicability to various types of biomass, efficiency, higher yields, and energy‐saving as compared to the conventional production processes have been demonstrated. Overall, cavitation‐assisted techniques are very effective in increasing biogas production and have significant potential for commercial applications, which would result in significant cost savings. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the effects of soil penetration resistance, tillage depth, and operating speeds on the deformation and fatigue of the subsoiling shovel based on the real-time measurement of tractor-operating conditions data. Various types of sensors, such as force, displacement, and angle, were integrated. The software and hardware architectures of the monitoring system were designed to develop a field operation condition parameter monitoring system, which can measure the tractor's traction force of the lower tie-bar, the real-time speed, the latitude and longitude, tillage depth, and the strain of the subsoiling shovel and other condition parameters in real-time. The time domain extrapolation method was used to process the measured data to obtain the load spectrum. The linear damage accumulation theory was used to calculate the load damage of the subsoiling shovel. The magnitude of the damage value was used to characterize the severity of the operation. The signal acquisition test and typical parameter test were conducted for the monitoring system, and the test results showed that the reliability and accuracy of the monitoring system met the requirements. The subsoiling operation test of the system was carried out, which mainly included two kinds of soil penetration resistances (1750 kPa and 2750 kPa), three kinds of tillage depth (250 mm, 300 mm, and 350 mm), and three kinds of operation speed (4 km/h low speed, 6 km/h medium speed, and 8 km/h high speed), totaling 18 kinds of test conditions. Eventually, the effects of changes in working condition parameters of the subsoiling operation on the overall damage of subsoiling shovels and the differences in damage occurring between the front and rear rows of subsoiling shovels under the same test conditions were analyzed. The test results show that under the same soil penetration resistance, the overall damage sustained by the subsoiling shovels increases regardless of the increase in the tillage depth or operating speed. In particular, the increase in the tillage depth increased the severity of subsoiling shovel damage by 19.73%, which was higher than the 17.48% increase due to soil penetration resistance and the 13.07% increase due to the operating speed. It should be noted that the front subsoiling shovels consistently sustained more damage than the rear, and the difference was able to reach 16.86%. This paper may provide useful information for subsoiling operations, i.e., the operational efficiency and the damage level of subsoiling shovels should be considered. [ABSTRACT FROM AUTHOR]

Biomass-derived biocrude is gaining greater recognition from people in general as an alternative fuel source to traditional fossil fuels. Worldwide, a great deal of research is being done to develop fuels made from sustainable biomass in order to replace the current conventional energy sources. Waste sludge has been thought of as a viable raw biomass source because of its accessibility, affordability, high lignin content, and higher heating value. Additionally, considering sludge contains a high proportion of moisture and water acts as a catalyst during the hydrothermal liquefaction (HTL) process, it is the best choice for thermochemical conversion. From the ultimate component value ranges obtained from elemental analysis, it can be demonstrated that the C, H, and higher heating value (HHV) of petrocrude are approximately 8.78%, 23.5%, and 10.66% higher than those of biofuel. According to the overall analysis, co-liquefaction of waste vegetable oil and swine manure can result in 87.97% bio-oil at 340 °C. The temperature, retention period, inclusion of catalysts, and use of solvents, however, can all affect this proportion. To support this illustration, it has been assessed from the study that municipal wet sewage sludge can produce an HHV of 28.52 MJ/kg when water is used as the solvent. However, 34.14 MJ/kg, or 16.5% more than the previous one, can be produced for the same amount of biomass, when the mixture of water and methanol serves as the solvents. This review article highlights an array of waste sludge categories, their chemical properties, and their conversion through the HTL process. It also features a Van Krevlen diagram with a graphical representation of essential operating parameters. This review research illustrates one of the best strategies for producing biofuel in which waste sludge can be used as raw material through the HTL conversion process, considering the prospective mass commercial production of biocrude oil. [ABSTRACT FROM AUTHOR]

In India, air conditioning is essential in the truck driver's cabin during the summer. An air conditioning system powered by the vehicle's engine adds to the engine's workload, resulting in higher fuel demand and more emissions. An adsorption chiller that runs on engine exhaust is designed here to lower the interior temperature of a truck cabin to address the above-mentioned issue. Here, an adsorption air conditioner system's effectiveness is forecast using a lumped analytical technique. During the adsorption process, heat from the adsorber bed is absorbed by cold water and released into the radiator. The desorber bed has been heated using hot water as a heat transfer medium from the engine exhaust heat. The analysis was carried out using the adsorption kinetic equation at adsorption equilibrium. The influence of inlet water flow rate, temperature and switching time (adsorber process to desorber process and vice versa) on adsorption chiller performance has been studied here. According to simulation results, the proposed adsorption chiller can be used to keep the driver cabin cool during summer for operational conditions adopted during the simulation. The adsorption air conditioner's highest coefficient of performance (COP), as determined by this investigation, was found to be 0.214. [ABSTRACT FROM AUTHOR]

A novel Separated Heat Pipe (SHP) system incorporating two magnetic spheres (SHPMS) was proposed for power generation (US Patent 11365653B2, 2022) using low-grade thermal energy, or offering both reliable emergency power and efficient heat transfer for spent fuel pools. This paper reports the experimental investigation on flow and heat transfer characteristics of the SHP, providing a foundation for the R&D of SHPMS. The SHP system features a unique shell-and-tube condenser structure, where the tube side serves as the cooling coil, while the shell side functions as the condenser chamber, with the dual roles of liquid storage and surge tank. The study researched the stability and heat transfer performance of the SHP under various parameters, including filling ratios ranging from 17 % to 98 %, cooling temperatures between 14 °C and 22 °C, and system pressures from 630 to 830 kPa. Analysis of instantaneous temperature, pressure, and flow patterns reveals the absence of high-frequency oscillations or alternating flow patterns, indicating that the condenser's condensing chamber may eliminate the instability in the SHP. Comparative analysis of the heat transfer coefficient and thermal resistance indicates that higher filling ratios and system pressures impair heat transfer performance, with optimal results at lower filling ratios (17 %–55 %) and pressure (630 kPa), where the higher heat transfer coefficient and lower thermal resistance were observed. Cooling temperatures showed little impact on heat transfer, allowing it to be chosen based on safety and energy efficiency needs. This study provides a new perspective on SHP systems with compressible volume condenser, offering a potential solution to address the instability challenges of SHP and the selection of operation parameters.

Abstract Feed wastage is one of the major concerns in aquaculture practice. A simple and unique floating fish feeder with drum-type metering mechanism was developed, which addresses this concern. A drum-type metering mechanism is an easy, effective, low cost metering method with low energy requirement. Optimizing the feed rate for any metering systems is a necessary pre-requisite to ensure proper feeding. In this study, the operating parameters of the drum-type feed metering unit have been optimized to achieve the desired feed rate. The influence of three independent parameters (number of metering holes, shaft speed and drum fill level) on the dependent parameter (feed rate) was studied and optimized using response surface methodology. A multilevel full factorial design approach has been adopted for the experimental design. The effect of variation in operating parameters was investigated experimentally and a response surface model was developed from experimental data. The fit of the model was expressed by an R 2 value of 0.879. The optimal solutions obtained from the model with high desirability values were further used for validation experiments in aquaculture pond and found to be acceptable. It was observed that low shaft speeds and drum fill levels led to better feeding. The best settings recommended for the feeder operation were 24 metering holes, 31 % drum fill level and 30 rpm shaft speed. The feeder was found to improve feed application and reduce feed wastage. This kind of low-cost feeding systems is expected to encourage adoption of mechanized feeding among small and marginal farmers.

Production of soluble dry extracts from sea buckthorn raw materials is relevant and promising for enterprises of the Republic of Buryatia. The authors have selected technological equipment for obtaining dry extracts: extractor, concentrator, dryer. The possibility of using vacuum-pulse action and the influence of technological factors on the yield of water-soluble substances from sea buckthorn leaves and shoots has been studied. The operating parameters of the technological process have been determined experimentally under production conditions: temperature 45–50 °C, total duration of extraction, concentration and drying 79–111 minutes. The process of obtaining dry extracts is carried out in three stages: water extraction; filtration and concentration; drying in a vacuum pulse dryer. The resulting experimental sample of dry extract from sea buckthorn leaves and shoots is a free-flowing crystalline powder with a moisture content of 4–6 %, highly soluble in water, having high organoleptic characteristics – a natural, well-defined aroma characteristic of sea buckthorn, light brown color. The use of low temperatures and vacuum-pulse modes at the stages of the technological process predicts high safety of thermolabile biologically active substances in the product. The process of obtaining dry extracts from sea buckthorn leaves and shoots has been studied. The results of the studies prove the possibility of producing a dry extract with high organoleptic characteristics using the developed by the authors' technology by equipment whose vacuum-pulse operating modes have a positive effect on the yield of extractives and help reduce time costs along with the intensification of heat and mass exchange processes in sea buckthorn raw materials.

This study aims to provide an overview of the growing need for renewable energy conversion and aligns with the broader context of environmentally friendly energy, specifically through producing syngas from biomass. Unlike natural gas, which is mainly composed of methane, syngas contains a mixture of combustible CO, H2, and CnHm. Therefore, optimizing its production requires a thorough examination of various operational parameters such as the gasifying agent, the equivalence ratio, the biofuel type, and the state, particularly in densified forms like pellets or briquettes. As new biomass sources are continually discovered and tested, operational parameters are also constantly evaluated, and new techniques are continuously developed. Indeed, these techniques include different gasifier types and the use or non-use of catalysts during biofuel conversion. The present study focuses on these critical aspects to examine their effect on the efficiency of syngas production. It is worth mentioning that syngas is the primary gaseous product from gasification. Moreover, it is essential to note that the pyrolysis process (prior to gasification) can produce, in addition to tar and char, a mixture of gases. The common feature among these gases is their versatility in energy generation, heat production, and chemical synthesis. The analysis encompasses the resulting gas features, including the yield and composition, mainly through the hydrogen-to-carbon monoxide ratio and the carbon monoxide-to-carbon dioxide ratio, as well as the lower heating value and considerations of the tar yield. [ABSTRACT FROM AUTHOR]

Vinasse is acidic, dark brown wastewater obtained as a residue from the alcohol distillation process, the main component of which is water, in addition to mineral nutrients and a high organic load. Electrocoagulation (EC) is a technology that generates coagulating substances in situ by oxidizing sacrificial anodes through an electric current applied to the electrodes. During the last decade, the electrocoagulation process has been intensively investigated in several reviews, due to its ease of operation, versatility, sustainability and low environmental impact. The objective of the present work has been to make a general review of the EC process, its principle, reaction mechanism and operating parameters involved in the electrocoagulation process. In this research, the PRISMA method was used for the analysis of articles from different databases such as Scopus, ScienceDirect and Google Scholar. This review collects numerous studies of the EC process in stillage wastewater treatment and makes a comparison between these experimental results mainly in terms of chemical oxygen demand removal. In addition, this review makes a comprehensive analysis of EC coupled to other processes, taking into account their operating parameters and stillage contaminant removal efficiency. The conclusion of this research points out that electrocoagulation coupled with other treatment processes is very necessary because it reduces energy consumption and increases the rate of pollutant removal from wastewater. [ABSTRACT FROM AUTHOR]

Feed wastage is one of the major concerns in aquaculture practice. A simple and unique floating fish feeder with drum-type metering mechanism was developed, which addresses this concern. A drum-type metering mechanism is an easy, effective, low cost metering method with low energy requirement. Optimizing the feed rate for any metering systems is a necessary pre-requisite to ensure proper feeding. In this study, the operating parameters of the drum-type feed metering unit have been optimized to achieve the desired feed rate. The influence of three independent parameters (number of metering holes, shaft speed and drum fill level) on the dependent parameter (feed rate) was studied and optimized using response surface methodology. A multilevel full factorial design approach has been adopted for the experimental design. The effect of variation in operating parameters was investigated experimentally and a response surface model was developed from experimental data. The fit of the model was expressed by an R2 value of 0.879. The optimal solutions obtained from the model with high desirability values were further used for validation experiments in aquaculture pond and found to be acceptable. It was observed that low shaft speeds and drum fill levels led to better feeding. The best settings recommended for the feeder operation were 24 metering holes, 31 % drum fill level and 30 rpm shaft speed. The feeder was found to improve feed application and reduce feed wastage. This kind of low-cost feeding systems is expected to encourage adoption of mechanized feeding among small and marginal farmers. [ABSTRACT FROM AUTHOR]

Processing fine and ultrafine coal particles from primary resources is essential for sustainable development. As one of the most recently developed enrichment equipment, cyclonic microbubble flotation columns (FCMC) showed high efficiency in upgrading various fine minerals. However, understanding the effect of FCMC operating variables on coal upgrading process responses remains a black box and needs fundamental assessments. To fill the gap, this study examined the influence of circulating pump pressure and froth height on the recovery of different coal particle size ranges to assess and explore fundamental FCMC performance. The experimental results established that increased froth height would simultaneously reduce the collection and froth recovery. Coarse particles in the high froth height were detached due to bubble coalescence or rupture, while the liquid drainage reduced fine particle pollution of froth products. Increasing circulating pump pressure would increase the collection zone's turbulence, lead to coarse particle detachment, and reduce collection recovery. Meanwhile, increasing circulating pump pressure could promote froth stability and decrease froth detachment in the froth zone. The calculated first-order rate constant (kc) confirmed that the flotation rate constants of coarse (−0.5 + 0.25 mm) and fine (−0.074 mm) particles were low, while the intermediate particles (−0.125 + 0.074 mm) had faster flotation kinetics. [ABSTRACT FROM AUTHOR]

Laser micromachining has been used as an alternative to producing microfluidics structures and simplifying the conventional soft lithography process. In this paper we characterize the excimer laser micromachining parameters and demonstrate its application by producing several microfluidic structures in polydimethylsiloxane (PDMS). The parameters include the number of laser pulses, laser energy and rectangular variable aperture (RVA) in both x- and y-directions. We found that the laser energy and pulse rate affect the depth of micromachining d channels, while RVA in both x- and y-directions affects the width of the channels. Repetition of laser scan does not change the channel width but significantly changes the channel depth. Proper adjustment for laser energy and pulse rate is required to fabricate a desired channels depth. In order to demonstrate the microfabrication capability of an excimer laser with the optimal operating parameters, several microfluidic structures were micromachining d into PDMS with a KrF excimer laser. [ABSTRACT FROM AUTHOR]

Advanced carbon emission factors of a power grid can provide users with effective carbon reduction advice, which is of immense importance in mobilizing the entire society to reduce carbon emissions. The method of calculating node carbon emission factors based on the carbon emissions flow theory requires real-time parameters of a power grid. Therefore, it cannot provide carbon factor information beforehand. To address this issue, a prediction model based on the graph attention network is proposed. The model uses a graph structure that is suitable for the topology of the power grid and designs a supervised network using the loads of the grid nodes and the corresponding carbon factor data. The network extracts features and transmits information more suitable for the power system and can flexibly adjust the equivalent topology, thereby increasing the diversity of the structure. Its input and output data are simple, without the power grid parameters. We demonstrated its effect by testing IEEE-39 bus and IEEE-118 bus systems with average error rates of 2.46% and 2.51%. [ABSTRACT FROM AUTHOR]

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The internal reaction state of air-cooled proton exchange membrane fuel cell (PEMFC) is the key factor affecting the output performance and stability of the cell. By developing an in-situ testing device for the reaction state of air-cooled fuel cell, the real-time measurement of cell temperature and current density is realized, and the influence mechanism of hydrogen outlet pulse interval, hydrogen inlet pressure and cathode wind speed on the performance of the cell is revealed. The results show that the distribution of temperature and current density in air-cooled cells is uneven. The temperature difference can reach 20 °C, and the current density difference reaches 400 mA/cm2 when the average current density is 500 mA/cm2. As the interval between pulses decreases and the inlet pressure increases, the performance of the hydrogen outlet area and the uniformity of the distribution increase, which can reduce the fluctuation of current density in the cells and improve output stability. If the cathode wind speed is too low, the temperature in central areas is high, and the temperature distribution uniformity is reduced. However, excessive wind speed causes the generating water to be blown away. The water content of the proton exchange membrane thus decreases, and the uniformity of the current density distribution deteriorates.

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Copyright of Chemical Engineering (China) / Huaxue Gongcheng is the property of Hualu Engineering Science & Technology Co Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The operating conditions of the sedimentation tanks are very critical for wastewater treatment. The effects of operating parameters (inlet velocity, inlet sludge concentration and reflux ratio) on the settling performance of a vertical sedimentation tank (VST) are investigated using Mixture and RNG k-ε numerical simulation methods. In order to verify the suitability and accuracy of the selected numerical model, the experimental values are compared with the simulated values and the results show that the average relative error is 8.63%. That means the selected numerical model are reliable for describing the flow behavior of the VST. The simulation results indicate that the inlet velocity, inlet sludge concentration and reflux ratio have significant influences on the settling performance of the VST. When the inlet velocity and the inlet sludge concentration are kept at the low level, the sludge has enough time to settle down. However, the sludge easily flows out from the tank since the inlet velocity and the inlet sludge concentration are sharply increased. Meanwhile, the reflux ratio should be kept at the appropriate level to prevent the suspending sludge. Therefore, it is recommended to maintain the inlet velocity of below 0.3 mm/s, an inlet sludge concentration of below 2056 mg/L, and a reflux ratio of below 80% to ensure the effluent quality meets the Chinese discharge standards. In the future, the recommended operating conditions can be applied for large-scale vertical secondary sedimentation tanks without flocculation. [ABSTRACT FROM AUTHOR]

This paper presents the results of a study performed on silica sand samples to determine the effect of operating parameters (collector type and dosage, solids content in the pulp, pulp pH and air flow rate) on the concentrate grade and mass recovery in laboratory-scale column flotation. Through the analysis of variance (ANOVA), it was determined that the pulp pH had a significant impact on all four of the observed grade parameters (mass contents of SiO2, Al2O3, Fe2O3 and TiO2 in the concentrate). Air flow rate had a significant impact on the mass contents of SiO2 and Al2O3. The solids content in the pulp only significantly affected the mass content of Fe2O3. The mass recovery was significantly influenced by the pulp pH, with a high level of significance (p-value (p) = 0.002917), as well as by the air flow rate (p = 0.010285). On the basis of a model of the relationship between the respective grade parameters and tested operating variables, it was determined that with the use of the Aeromine 3030C collector (at a dosage of 500 g/t) the highest-grade concentrate regarding the mass contents of SiO2, Al2O3 and TiO2 was achieved with a pulp pH within a range from 2.4 to 3 and an air flow rate above 26 L/h. The lowest mass content of Fe2O3 in the concentrate was achieved at a pulp pH in a range from 2.2 to 2.8 and a solids content in the pulp between 2.0% and 3.5%. [ABSTRACT FROM AUTHOR]

High-power diesel engine turbochargers predominantly utilize floating ring bearings as their primary supporting components. To further enhance their load capacity, multi-lobe noncircular bearings have been progressively employed. This study focuses on the investigation of noncircular three-lobe SFRBs (semi-floating ring-bearing structures) in marine turbochargers. Employing the half-step center Finite Difference Method (FDM) and the Newton–Raphson iterative procedure, the impact of operational parameters such as the journal speed, external load, oil supply pressure, and oil supply temperature on the static and dynamic characteristics of the inner oil film is analyzed. Subsequently, the accuracy of the theoretical model is validated through a comparative analysis of simulation results obtained from Dyrobes and Fluent. The findings indicate that as the oil supply pressure and temperature increase, the temperature rise and maximum oil film pressure of the three-lobe SFRBs gradually decrease, while the oil film thickness progressively increases, thereby significantly improving the lubrication state. The load capacity of the three-lobe SFRBs is primarily sustained by the bottom tile, where wall friction is most likely to occur. Additionally, within the actual speed range, the stiffness and damping of the three-lobe SFRBs exhibit noticeable nonlinear characteristics. [ABSTRACT FROM AUTHOR]

The operating parameters of the active direct methanol fuel cell (DMFC) are essential factors affecting its power delivery performance. Different operating parameters lead to variations in the amount of methanol crossover in a DMFC, which might cause overpotential and cathode catalyst poisoning. Due to the complexity of the DMFC system, changes in operating conditions, and correlations among these parameters, it is challenging to maintain output power density while reducing the negative effects of methanol crossover. This paper proposes an adaptive joint optimization method for fuel cell operating parameters. The principle operating parameters are selected by the orthogonal tests, which include an adaptive numerical simulation and multiobjective optimization regarding cell output power density and methanol crossover. The selected parameter combinations are verified by an evaluation model that quantifies the influences of operating parameters on the active DMFC power density and its methanol crossover, where the nonlinear mapping function for the two optimization objectives is obtained. The nondominated sorting genetic algorithm‐II (NSGA‐II) is applied to rapidly obtain the optimal combination. The results show that with the optimal parameters, the maximum power density is increased by 16.7% and the methanol crossover is reduced by 35.1%. [ABSTRACT FROM AUTHOR]

This article explores the impact of operating parameters on the classification efficiency of a rotor classifier. Based on the experimental data of calcined petroleum coke classification, a single-factor experimental analysis is conducted to find the relationship between operating parameters and classification performance. The cut size becomes progressively smaller as the rotor speed and feeding speed increase, and progressively larger as the inlet air volume increases. Newton's classification efficiency and classification accuracy decreased with the increase in feeding speed. The range analysis of the orthogonal experiment shows that the rotor speed and inlet air volume have significant effects on the classification performance, but the effect of feed speed is relatively weak. In addition, the optimal combination of operating parameters is obtained by optimizing the operating parameters. Newton's classification efficiency under this combination is estimated, and the estimated value is 82%. The verification experiment reveals that the Newton's classification efficiency is 83.5%, which is close to the estimated value. Meanwhile, the classification accuracy is 0.626. This study provides theoretical guidance for the industrial production of calcined petroleum coke and accumulates basic experimental data for the development of air classifiers. [ABSTRACT FROM AUTHOR]