Processes

Open AccessArticle

Modeling Linkages among Urban Agglomeration, Construction Industry, Non-Renewable Energy, and Zero-Carbon Future

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Processes 2023, 11(4), 1040; https://doi.org/10.3390/pr11041040 (registering DOI) - 29 Mar 2023

Abstract

On the one hand, the twin perspectives of the construction industry and urban agglomeration proliferate economic prosperity. However, on the other hand, construction activities and increased population density give rise to environmental challenges. This study is an initial attempt to explore links between [...] Read more.

On the one hand, the twin perspectives of the construction industry and urban agglomeration proliferate economic prosperity. However, on the other hand, construction activities and increased population density give rise to environmental challenges. This study is an initial attempt to explore links between the construction industry, urban agglomeration, non-renewable energy utilization, carbon dioxide emissions (CO₂e), and economic output within a system of simultaneous equation modeling. This study develops modeling specifications to include the construction industry as a shifting factor and CO₂e as a determinant of technical efficiency. A heterogeneous fully modified ordinary least squares (FMOLS) technique, capable of providing concrete empirical outcomes even in the presence of modern panel-data econometric issues, is utilized for the data of China’s 30 provincial/ city divisions during the 2003–2019 period. It has been revealed that: (i) the influence of urban agglomeration on the economic output was heterogeneous, with an adverse link for China’s western part, neutrality connection for the central part, and favorable for China’s eastern part; and (ii) shifting from China’s western to eastern parts, the expansion of the construction industry has a significant impact on economic output, and, hence, has been described as “the Economic Effects of Urban agglomeration” for the Chinese economy. The policies of this study have crucial lessons for global economies. Full article

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Open AccessFeature PaperReview

Progress in Electroreduction of CO₂ to Form Various Fuels Based on Zn Catalysts

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Processes 2023, 11(4), 1039; https://doi.org/10.3390/pr11041039 (registering DOI) - 29 Mar 2023

Abstract

Carbon dioxide (CO₂) is one of the main greenhouse gases and the major factor driving global climate change. From the viewpoint of abundance, economics, non-toxicity, and renewability, CO₂ is an ideal and significant C1 resource, and its capture and recycling [...] Read more.

Carbon dioxide (CO₂) is one of the main greenhouse gases and the major factor driving global climate change. From the viewpoint of abundance, economics, non-toxicity, and renewability, CO₂ is an ideal and significant C1 resource, and its capture and recycling into fuels and chemical feedstocks using renewable energy is of great significance for the sustainable development of society. Electrochemical CO₂ reduction reactions (CO₂RRs) are an important pathway to utilize CO₂ resources. Zinc has been demonstrated as an effective catalyst for CO₂RRs. Numerous studies have focused on improving the efficiency of zinc-based catalysts by tuning their morphology and components, as well as controlling their oxidation states or doping. However, only a handful of reviews have evaluated the performance of Zn-based CO₂RR electrocatalysts. The present review endeavors to fill this research gap and introduces the recent progress in using CO₂RRs to create various fuels (carbon-containing substances or hydrocarbons) using zinc-based catalysts, including Zn monomers, Zn-containing bimetals, oxide-derived Zn catalysts, and single/dual Zn atom catalysts. The mechanism of the electroreduction reaction of CO₂ is discussed. Based on the previous achievements, the current stage and the outlook for future developments in the field are summarized. This review will provide a reference for future research on CO₂RRs to generate fuels using Zn-based catalysts and their commercialization. Full article

(This article belongs to the Special Issue State of the Art of Waste Utilization and Resource Recovery)

Open AccessArticle

Experimental Study on the Vibration Reduction Performance of the Spindle Rotor of a Rubbing Machine Based on Aluminium Foam Material

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Processes 2023, 11(4), 1038; https://doi.org/10.3390/pr11041038 (registering DOI) - 29 Mar 2023

Abstract

Larger vibration and noise often exist in agricultural machinery due to the harsh working environment and high power. The rubbing machine is one of the indispensable pieces of equipment in the agriculture and livestock industry, and it is affected by the vibration of [...] Read more.

Larger vibration and noise often exist in agricultural machinery due to the harsh working environment and high power. The rubbing machine is one of the indispensable pieces of equipment in the agriculture and livestock industry, and it is affected by the vibration of large constraints on its promotion and use. To reduce the vibration of the rubbing machine, the vibration characteristics of the spindle rotor were first analysed by modal simulation, thus determining the larger contributions to the spindle rotor vibration. Second, aluminium foam material was installed in the large deformation part of the spindle rotor. Its vibration reduction and energy absorption characteristics were used to optimise the vibration reduction design by increasing the damping. Third, a steel ball impact test was conducted to analyse the vibration characteristics of the optimised spindle rotor. The results show that the maximum impact accelerations were reduced by 28.4% and 64.75% in the axial and radial directions, respectively, and the impact energies were reduced by 67.3% and 90.65% in the axial and radial directions within 2 s of impact collision, respectively, indicating that the optimised spindle rotor damping increased significantly. In addition, the vibration reduction effect of the optimised rubbing machine was verified by a bench test. By measuring the change degree of the static component of the spindle rotor vibration, the axial, radial, and vertical vibrations of the spindle rotor were improved by 5.78%, 10.32%, and 23.96%, respectively. Therefore, optimising the spindle rotor with aluminium foam material can reduce the vibration generated during the impact of the material on the spindle rotor. The rubbing machine’s vibration, damping, and energy absorption were also realised in real working conditions. Full article

(This article belongs to the Section Manufacturing Processes and Systems)

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Open AccessArticle

Machining of Custom-450 Grade Stainless Steel Using TiAlSiN-Coated Tungsten Carbide Tool Inserts

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Processes 2023, 11(4), 1037; https://doi.org/10.3390/pr11041037 (registering DOI) - 29 Mar 2023

Abstract

Turning operations using single-point cutting tools have been one of the earliest and most used methods for cutting metal. It has been widely studied for cutting forces and workpiece surface roughness to affect turning operations. When cutting metal, the cutting tool needs to [...] Read more.

Turning operations using single-point cutting tools have been one of the earliest and most used methods for cutting metal. It has been widely studied for cutting forces and workpiece surface roughness to affect turning operations. When cutting metal, the cutting tool needs to be tougher than the workpiece so it can resist high temperatures and wear while the operation is conducted. The mechanical qualities of martensitic stainless steel (MSS) grade Custom-450 can be significantly enhanced by heat treatment processes, which also provide it with an outstanding corrosion-resistance material. It has excellent resistance to rusting and pitting in a saltwater environment. Nuclear power reactors, screens for the pulp and paper sector, chemical processing, and power generation are just a few industries that require Custom-450 grade steel. To increase the workpiece’s machinability, dimensional precision, and appealing surface finish, the cutting tool industries have recently demonstrated a great interest in developing hard coatings and cutting tool technology. In the present study, Custom-450 grade stainless steel was used for machining (turning operation), using a tungsten carbide tool insert coated with TiAlSiN using the physical vapor deposition (PVD) method. The machining parameters such as the speed, feed, and depth of cut (DOC) were varied Surface roughness and various forces (cutting force, thrust force, and feed force) were evaluated by varying these three parameters. The depth of cut is the main factor affecting the surface roughness. More plastic deformation may lead to a rougher surface as a result. The tungsten carbide insert wear decreased with an increase in the cutting speed. An increase in feed considerably accelerates the tool wear of the inserts. As the depth of cut grows, the likelihood of tool wear also increases. The depth of cut, however, has a greater effect on tool wear than anything else. Therefore, the surface roughness in the sample is reduced as the cutting speed is increased. Full article

(This article belongs to the Section Manufacturing Processes and Systems)

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Open AccessReview

Modeling Strategies for Crude Oil-Induced Fouling in Heat Exchangers: A Review

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Obaid ur Rehman

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Marappa Gounder Ramasamy

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Nor Erniza Mohammad Rozali

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Shuhaimi Mahadzir

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Ali Shaan Manzoor Ghumman

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Abdul Hannan Qureshi

Processes 2023, 11(4), 1036; https://doi.org/10.3390/pr11041036 (registering DOI) - 29 Mar 2023

Abstract

Semi-empirical fouling models have proven more effective in predicting the fouling behavior of crude oils in heat exchangers. These models have aided refineries in optimizing operating conditions to minimize or eliminate fouling in preheat exchangers. Despite their complexity, the models continue to improve [...] Read more.

Semi-empirical fouling models have proven more effective in predicting the fouling behavior of crude oils in heat exchangers. These models have aided refineries in optimizing operating conditions to minimize or eliminate fouling in preheat exchangers. Despite their complexity, the models continue to improve in approximating real behavior by taking into account previously neglected aspects. This paper summarizes these findings from various studies along with highlighting different factors which were considered to enhance the predictability of the models. A critical analysis is presented to emphasize that activation energy in the deposition term varies depending on the physical processes involved and may not conform to the precise definition of activation energy. Two primary modeling approaches for crude oil fouling have emerged, i.e., deterministic and threshold models. Threshold models have gained more attention due to their fewer adjustable parameters. The stability or compatibility of crude oils has a substantial impact on asphaltene deposition, which is a major contributor to fouling. However, incorporating this factor into fouling models has received little attention. The inclusion of parameters for inorganic fraction and ageing has increased predictability by accurately estimating the fouling thickness. The use of CFD to analyze fouling mechanisms is promising, particularly for complex geometries. The dynamic and moving boundary modeling approach has potential to broaden the applicability of fouling models. Full article

(This article belongs to the Special Issue New Advances in Heat Transfer and Fluid Flow)

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Open AccessArticle

GCCSwin-UNet: Global Context and Cross-Shaped Windows Vision Transformer Network for Polyp Segmentation

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Processes 2023, 11(4), 1035; https://doi.org/10.3390/pr11041035 - 29 Mar 2023

Abstract

Accurate polyp segmentation is of great importance for the diagnosis and treatment of colon cancer. Convolutional neural networks (CNNs) have made significant strides in the processing of medical images in recent years. The limited structure of convolutional operations prevents CNNs from learning adequately [...] Read more.

Accurate polyp segmentation is of great importance for the diagnosis and treatment of colon cancer. Convolutional neural networks (CNNs) have made significant strides in the processing of medical images in recent years. The limited structure of convolutional operations prevents CNNs from learning adequately about global and long-range semantic information interactions, despite the remarkable performance they have attained. Therefore, the GCCSwin-UNet framework is suggested in this study. Specifically, the model utilizes an encoder–decoder structure, using the patch-embedding layer for feature downsampling and the CSwin Transformer block as the encoder for contextual feature extraction. To restore the feature map’s spatial resolution during upsampling operations, a symmetric decoder and patch expansion layer are also created. In order to help the backbone module to do better feature learning, we also create a global context module (GCM) and a local position-enhanced module (LPEM). We conducted extensive experiments on the Kvasir-SEG and CVC-ClinicDB datasets, and compared them with existing methods. GCCSwin-UNet reached remarkable results with Dice and MIoU of 86.37% and 83.19% for Kvasir-SEG, respectively, and 91.26% and 84.65% for CVC-ClinicDB, respectively. Finally, quantitative analysis and statistical tests are applied to further demonstrate the validity and plausibility of our method. Full article

(This article belongs to the Special Issue Application of Artificial Intelligence in Medical Assisted Decision System)

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Open AccessArticle

Synthesis of Aluminum Nitride Using Sodium Aluminate as Aluminum Source

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Processes 2023, 11(4), 1034; https://doi.org/10.3390/pr11041034 - 29 Mar 2023

Abstract

At present, the carbothermal reduction and nitridation process is an important method for the large-scale preparation of aluminum nitride powder in industry, but the tremendous energy consumption caused by long-term high temperatures seriously restricts its practical application. To solve this problem, the (NaAlO [...] Read more.

At present, the carbothermal reduction and nitridation process is an important method for the large-scale preparation of aluminum nitride powder in industry, but the tremendous energy consumption caused by long-term high temperatures seriously restricts its practical application. To solve this problem, the (NaAlO₂+C) mixture with a mole ratio of NaAlO₂:C = 1:3 was prepared based on sodium aluminate and carbon black which has been ball milled with anhydrous ethanol as a grinding liquid. The crystal structure evolution and nitridation reaction behavior of sodium aluminate at 800–1600 °C under a nitrogen atmosphere in the presence of carbon were systematically studied employing XRD, SEM, and ICP-MS. The results showed that: high energy θ-Al₂O₃, η-Al₂O₃ can be excited by heating sodium aluminate to 1400 °C under a nitrogen atmosphere in the presence of carbon. The transformation process between sodium aluminate and aluminum nitride is carried out via the direct nitridation of θ-Al₂O₃, η-Al₂O₃. Benefiting from the direct nitridation of η-Al₂O₃ and θ-Al₂O₃, high-purity aluminum nitride powder with a particle size of 0.50 ± 0.18 μm was synthesized at 1400 °C. This work provides a new path for reduced energy consumption in the aluminum nitride industry. Full article

(This article belongs to the Special Issue Controllable Preparation and Application of Metal Compounds)

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Open AccessArticle

One-Pot Syntheses of PET-Based Plasticizer and Tetramethyl Thiuram Monosulfide (TMTS) as Vulcanization Accelerator for Rubber Production

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Aleksandar Marinković

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Milutin Milosavljević

Processes 2023, 11(4), 1033; https://doi.org/10.3390/pr11041033 - 29 Mar 2023

Abstract

Styrene-butadiene (SBR) and acrylonitrile-butadiene (NBR) rubber blends with tetramethyl thiuram disulfide (TMTD) and tetramethyl thiuram monosulfide (TMTS) accelerators and environmentally friendly plasticizers, obtained from PET recycling and biobased resources (LA/PG/PET/EG/LA), were prepared. The mechanical properties of the obtained rubber products were tested and [...] Read more.

Styrene-butadiene (SBR) and acrylonitrile-butadiene (NBR) rubber blends with tetramethyl thiuram disulfide (TMTD) and tetramethyl thiuram monosulfide (TMTS) accelerators and environmentally friendly plasticizers, obtained from PET recycling and biobased resources (LA/PG/PET/EG/LA), were prepared. The mechanical properties of the obtained rubber products were tested and compared with those of commercial dioctyl terephthalate (DOTP). TMTS was prepared by simple and efficient one-pot synthesis from dimethylamine, carbon disulfide, potassium cyanide, and ammonium chloride as catalysts in recycled isopropanol/water azeotrope as solvent. In a comparative study, methoxide, ethoxide, iodide, and amide ions were also used. The two-step reaction mechanism of TMTS synthesis involves the oxidation of the amine salt of dimethyldithiocarbamic acid to TMTD by hydrogen peroxide and sulfur elimination from the TMTD disulfide bond. Potassium cyanide appears to be the most efficient nucleophile. The simplicity of operation, mild reaction conditions, solvent recycling, high yields, and applicability to the industrial level are the advantages of this process. Shore hardness, tensile strength, and compression test results of vulcanized blends before and after aging showed similar properties for both accelerators, while somewhat better results were obtained with LA/PG/PET/EG/LA plasticizer. Full article

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Open AccessArticle

Efficient Non-Destructive Detection of Interface Adhesion State by Interfacial Thermal Conductance: A Molecular Dynamics Study

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Processes 2023, 11(4), 1032; https://doi.org/10.3390/pr11041032 - 29 Mar 2023

Abstract

The state of interface adhesion, as measured by the void ratio, is a critical factor affecting the adhesion strength and heat dissipation efficiency of a system. However, non-destructive and rapid detection of the adhesion process remains a challenge. In this study, we used [...] Read more.

The state of interface adhesion, as measured by the void ratio, is a critical factor affecting the adhesion strength and heat dissipation efficiency of a system. However, non-destructive and rapid detection of the adhesion process remains a challenge. In this study, we used all-atom molecular dynamics simulations to investigate the interfacial thermal conductance of silicon and polymer at various adhesion void ratios, with the aim of achieving non-destructive and rapid detection of the adhesion process. Our results demonstrate a linear relationship between the interfacial thermal conductance and effective contact area at different temperatures, enabling the numerical value of interfacial thermal conductance to serve as an indicator of interfacial adhesion state. Furthermore, we also output the surface temperature of the adhesive interface. The non-uniformity of the surface temperature evolution can be used to identify the location of bubbles on the adhesive surface, which further reflects the bonding state of the interface. This project presents a novel approach and research framework for the non-destructive and rapid testing of the adhesion processes. Full article

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Open AccessArticle

CNC Turning of an Additively Manufactured Complex Profile Ti6Al4V Component Considering the Effect of Layer Orientations

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Processes 2023, 11(4), 1031; https://doi.org/10.3390/pr11041031 - 29 Mar 2023

Abstract

Electron beam melting (EBM) is one example of a 3D printing technology that has shown great promise and advantages in the fabrication of medical devices such as dental and orthopedic implants. However, these products require high surface quality control to meet the specifications; [...] Read more.

Electron beam melting (EBM) is one example of a 3D printing technology that has shown great promise and advantages in the fabrication of medical devices such as dental and orthopedic implants. However, these products require high surface quality control to meet the specifications; thus, post-processing, such as with machining processes, is required to improve surface quality. This paper investigates the influence of two-part orientations of Ti6Al4V EBM parts on the CNC machining (turning) process. The two possible EBM part orientations used in this work are across EBM layers (AL) and parallel to the EBM layer (PL). The effect of the EBM Ti6Al4V part orientations is examined on surface roughness, power consumption, chip morphology, tool flank wear, and surface morphology during the dry turning, while using uncoated carbide tools at different feed rates and cutting speeds. The results showed that the AL orientation had better surface quality control and integrity after machining than PL orientation. Using the same turning parameters, the difference between the roughness (Ra) value for AL (0.36 μm) and PL (0.79 μm) orientations is about 54%. Similarly, the power consumption in AL orientation differs by 19% from the power consumption in PL orientation. The chip thickness ratio has a difference of 23% between AL and PL orientations, and the flank wear shows a 40% difference between AL and PL orientations. It is found that, when EBM components are manufactured along across-layer (AL) orientations, the impact of part orientation during turning is minimized and machined surface integrity is improved. Full article

(This article belongs to the Special Issue Computer-Aided Manufacturing Technologies in Mechanical Field)

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Open AccessArticle

Low Permeability Gas-Bearing Sandstone Reservoirs Characterization from Geophysical Well Logging Data: A Case Study of Pinghu Formation in KQT Region, East China Sea

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Processes 2023, 11(4), 1030; https://doi.org/10.3390/pr11041030 - 29 Mar 2023

Abstract

The Pinghu Formation is a low permeability sandstone reservoir in the KQT Region, East China Sea. Its porosity ranges from 3.6 to 18.0%, and permeability is distributed from 0.5 to 251.19 mD. The relationship between porosity and permeability was poor due to strong [...] Read more.

The Pinghu Formation is a low permeability sandstone reservoir in the KQT Region, East China Sea. Its porosity ranges from 3.6 to 18.0%, and permeability is distributed from 0.5 to 251.19 mD. The relationship between porosity and permeability was poor due to strong heterogeneity. This led to the difficulty of quantitatively evaluating effective reservoirs and identifying pore fluids by using common methods. In this study, to effectively evaluate low permeability sandstones in the Pinghu Formation of KQT Region, pore structure was first characterized from nuclear magnetic resonance (NMR) logging based on piecewise function calibration (PFC) method. Effective formation classification criteria were established to indicate the “sweet spot”. Afterwards, several effective methods were proposed to calculate formation of petrophysical parameters, e.g., porosity, permeability, water saturation (S_w), irreducible water saturation (S_wirr). Finally, two techniques, established based on the crossplots of mean value of apparent formation water resistivity (R_wam) versus variance of apparent formation water resistivity (R_wav)—S_w versus S_wirr—were adopted to distinguish hydrocarbon-bearing formations from water saturated layers. Field applications in two different regions illustrated that the established methods and techniques were widely applicable. Computed petrophysical parameters matched well with core-derived results, and pore fluids were obviously identified. These methods were valuable in improving low permeability sandstone reservoirs characterization. Full article

(This article belongs to the Special Issue Rock Physics, Well Logging, and Formation Evaluation in Energy Exploration Systems)

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Open AccessFeature PaperArticle

Engineered Biomaterials for Reducing Phosphorus and Nitrogen Levels from Downstream Water of Aquaculture Facilities

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Processes 2023, 11(4), 1029; https://doi.org/10.3390/pr11041029 - 29 Mar 2023

Abstract

The United States (U.S.) has a nearly USD 17 billion seafood trade deficit annually. However, the U.S. aquaculture industry faces strict micronutrient (e.g., phosphorus and nitrogen) level mandates that negatively impact fish production, especially for the state of Idaho, which produces 70–75% of [...] Read more.

The United States (U.S.) has a nearly USD 17 billion seafood trade deficit annually. However, the U.S. aquaculture industry faces strict micronutrient (e.g., phosphorus and nitrogen) level mandates that negatively impact fish production, especially for the state of Idaho, which produces 70–75% of the nation’s rainbow trout. This study investigates the sustainability benefits of producing engineered biomaterials from lignocellulosic-based feedstocks near collection sites via portable biorefineries for use by fish farms to reduce eutrophication (oversupply of micronutrients) impacts. In this study, sustainability assessments are performed on a case study in southern Idaho, the largest U.S. commercial producer of rainbow trout. The results show that 20 and 60 min of water treatment, using small particle size biomaterial from lodgepole pine, has the highest total phosphorus removal rate, at 150–180 g of phosphorus per 1 metric ton of engineered biomaterials. The results of techno-economic and environmental impacts studies indicate that pinewood-based biomaterials production cost ranges from USD 213 USD 242 per ton and reduces the eutrophication potential by 5–17 kg PO₄eq/ton. Additionally, the environmental impact results show that the total greenhouse gas emission for biomaterial production is 47–54 kg CO₂eq/ton; however, the used biomaterials after water treatment can be sold for around USD 850 per ton as nutrient-rich soil conditioners. This study concluded that engineered biomaterials from lignocellulosic-based feedstocks could be a sustainable solution to the challenge that aquaculture faces, particularly capturing micronutrients from eutrophic water and reusing them as fertilizers. Full article

(This article belongs to the Special Issue Advances in Value-Added Products from Waste)

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Open AccessArticle

A Novel Security Framework for the Enhancement of the Voltage Stability in a High-Voltage Direct Current System

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Ibrahim Alsaduni

Processes 2023, 11(4), 1028; https://doi.org/10.3390/pr11041028 - 28 Mar 2023

Abstract

Due to financial limitations, power systems are being operated closer to their stability boundaries. Voltage stability analysis is crucial to preserve a power system’s equilibrium. However, this impacts a system’s dependability and security, and maintaining a power system’s voltage stability is a difficult [...] Read more.

Due to financial limitations, power systems are being operated closer to their stability boundaries. Voltage stability analysis is crucial to preserve a power system’s equilibrium. However, this impacts a system’s dependability and security, and maintaining a power system’s voltage stability is a difficult challenge. Additionally, the inverters and converters in a high-voltage direct current (HVDC) system use a significant amount of reactive power, which exacerbates voltage instability. In this study, a new algorithm called Adaptive Neural Spider Monkey (ANSMA) was developed to improve the voltage stability security in an HVDC system. Additionally, the proposed ANSMA maintains voltage stability while scheduling the loads in the generator. Moreover, applying artificial-intelligence-related energy systems to these issues is considered an efficient solution. Fuzzy, neural, ANN, and other improvements in artificial intelligence approaches, along with power semiconductor devices, have significantly impacted the ability to detect defects in HVDC systems. Furthermore, MATLAB/Simulink is used in the implementation of this developed ANSMA model. After this, the parameters are calculated, and the resulting methodology is tested on an IEEE 50-bus system. Finally, the simulation results are verified using currently used techniques to assess the effectiveness of the suggested ANSMA model. Full article

(This article belongs to the Special Issue Application of Artificial Intelligence and Data Mining in Energy System)

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Open AccessArticle

Development of a Zeolite H-ZSM-5-Based D-μSPE Method for the Determination of Organophosphorus Pesticides in Tea Beverages

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Processes 2023, 11(4), 1027; https://doi.org/10.3390/pr11041027 - 28 Mar 2023

Abstract

In this study, a novel dispersive micro-solid phase extraction (D-μSPE) technique with H-ZSM-5 zeolite as an adsorbent was developed for the determination of 21 trace pesticides in tea beverages. The adsorption and desorption of H-ZSM-5 zeolites were investigated based on structural characteristics and [...] Read more.

In this study, a novel dispersive micro-solid phase extraction (D-μSPE) technique with H-ZSM-5 zeolite as an adsorbent was developed for the determination of 21 trace pesticides in tea beverages. The adsorption and desorption of H-ZSM-5 zeolites were investigated based on structural characteristics and adsorption properties similar to those of H-beta zeolites. In combination with the properties of the adsorbates, it was explained that the adsorption reaction occurred on the microporous surface and mesopores of H-ZSM-5. Based on optimal parameters, the beverage samples were extracted by 50 mg of zeolite within 1 min. The zeolite was eluted with 2 mL of an acetonitrile-water mixture after separation, and the eluent was filtered prior to HPLC-MS/MS analysis. The D-μSPE protocol demonstrated acceptable accuracy and precision, with recoveries between 62.1% and 106.6% and relative standard deviations of 1.4% to 12.6%, as validated by analytical reliability. The correlation coefficient in the linear range of 0.2–50 ng·mL⁻¹ was greater than 0.98, with limits of detection of 0.05–0.1 ng·mL⁻¹ and limits of quantification of 0.1–0.2 ng·mL⁻¹. The matrix effects ranged from 76.2% to 112.7%. The results indicate that the novel D-μSPE technique based on H-ZSM-5 is a rapid, simple, green and economical method for the determination of pesticide residues in tea beverages. The proposed method achieved simultaneously low adsorbent dosage, 20-fold enrichment factor, rapid pre-concentration in 12 min, minimal organic wastes, and effective reduction of matrix interference. Full article

(This article belongs to the Special Issue Applications of Chromatographic Separation Techniques in Food and Chemistry)

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Open AccessFeature PaperArticle

Analysis of Inner Flow in a Multi-Stage Double-Suction Centrifugal Pump Using the Detached Eddy Simulation Method

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Processes 2023, 11(4), 1026; https://doi.org/10.3390/pr11041026 - 28 Mar 2023

Abstract

In order to analyze the inner flow in a multi-stage double-suction centrifugal pump, which is regarded as a common way of knowing the current characteristics of the pump and as the basis of optimization for better performance, a numerical simulation considering the velocity [...] Read more.

In order to analyze the inner flow in a multi-stage double-suction centrifugal pump, which is regarded as a common way of knowing the current characteristics of the pump and as the basis of optimization for better performance, a numerical simulation considering the velocity field distribution characteristics and pressure fluctuation propagation law using the detached eddy simulation method was conducted. Additionally, the principle of entropy generation was put to use to quantify and compare the energy loss of different components. The results reveal that the existence of unstable flow structures in the first-stage impeller and a large number of vortical structures in the back-channel result in reduced operational efficiency of the pump. Furthermore, the pressure fluctuation intensity reaches its maximum with 0.15 at the blade trailing edge, which propagates to the tongue region of the forward flow channel and the double-volute under the low rates condition. Additionally, the main frequency of the monitoring points in the inter-stage flow channel and volute is basically located at a frequency of 198.667 Hz, which is twice the blade frequency. Consequently, the wall entropy production accounting for nearly 25% cannot be ignored and that the loss mainly occurs in the double-volute and the inter-stage flow channel due to the occurrence of irregular flow in the above components with more than 50%. The outcomes of this research present a valuable point of reference for the optimization of structural design in multistage turbomachines with various applications. Full article

(This article belongs to the Special Issue Advanced Simulation and Experiment Methods of Flow Instability in Hydraulic Machinery)

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Open AccessArticle

In Vitro Hypoglycemic Potential, Antioxidant and Prebiotic Activity after Simulated Digestion of Combined Blueberry Pomace and Chia Seed Extracts

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Elena Mihai

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Bogdan-Stefan Negreanu-Pirjol

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Oana Craciunescu

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Teodora Ciucan

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Andreea Iosageanu

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Ana-Maria Seciu-Grama

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Ticuta Negreanu-Pirjol

Processes 2023, 11(4), 1025; https://doi.org/10.3390/pr11041025 - 28 Mar 2023

Abstract

This study aimed to evaluate the hypoglycemic potential, antioxidant activity and prebiotic activity of a hydroalcoholic extract of blueberry pomace (BP), an aqueous extract of chia seeds (CS) and a novel combination of BP–CS extracts (BCM) for further use as ingredient of functional [...] Read more.

This study aimed to evaluate the hypoglycemic potential, antioxidant activity and prebiotic activity of a hydroalcoholic extract of blueberry pomace (BP), an aqueous extract of chia seeds (CS) and a novel combination of BP–CS extracts (BCM) for further use as ingredient of functional food. Spectrometric and HPLC analyses were used to characterize the total phenolic and flavonoid content and composition of BP, while CS was analyzed for total carbohydrate content. Data showed that the BCM mixture exerted an inhibition of α-amylase activity, which was 1.36 times higher than that of BP and 1.25 higher than CS extract. The mixture also showed better scavenging activity of free DPPH radicals than individual extracts, and had an IC₅₀ value of 603.12 µg/mL. In vitro testing indicated that both serum- and colon-reaching products of simulated intestinal digestion of BCM presented the capacity to protect Caco-2 intestinal cells against oxidative stress by inhibition of reactive oxygen species production. In addition, the colon-reaching product of BCM digestion had the capacity to significantly (p < 0.05) stimulate the growth of Lactobacillus rhamnosus and Lactobacillus acidophilus, revealing a prebiotic potential. All these results indicated that improved biological activity of the novel combination of BP and CS extracts could be due to the synergistic action of constituents. The combination is recommended for further testing and the development of novel functional food for controlling type 2 diabetes and gastrointestinal conditions. Full article

(This article belongs to the Special Issue Process Design, Analysis and Medicinal Importance of Nutraceuticals)

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Open AccessArticle

Rail Magnetic Flux Leakage Detection and Data Analysis Based on Double-Track Flaw Detection Vehicle

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Processes 2023, 11(4), 1024; https://doi.org/10.3390/pr11041024 - 28 Mar 2023

Abstract

The rapid development of the railway industry has brought convenience to people’s lives. However, with the high speed, high frequency and heavy load characteristics of rail use, the safety of rail is seriously threatened. In this paper, a magnetic flux leakage testing (MFL) [...] Read more.

The rapid development of the railway industry has brought convenience to people’s lives. However, with the high speed, high frequency and heavy load characteristics of rail use, the safety of rail is seriously threatened. In this paper, a magnetic flux leakage testing (MFL) detection technology of rail based on a double-track flaw detection vehicle is introduced in detail, which can effectively detect the damage of rail top surface, which is the blind area of ultrasonic detection. The magnetic dipole model is used to analyze that the leakage magnetic field in the direction of Bx and Bz above the damage is related to the depth and width of the damage. The relationship between the depth of the damage and the leakage magnetic field is quantitatively studied for the damage with fixed width but varying depth. The finite element simulation tool is used to model and simulate the damage at different depths. After analyzing the different characteristic values, it is found that the peak value of magnetic leakage signal has a certain correlation with the depth of damage, and the natural logarithm function is fitted out—VBx = 0.1451ln(b) + 0.2705, VBz = 2.7787ln(b) + 0.0087. In order to verify the prediction function of the injury depth fitted by the simulation data, the human injury with different depths was processed and the dual-track flaw detector was used to carry out the experiment of high-speed detection environment. The peak-to-peak fitting of the magnetic leakage signals in the direction of Bx and Bz of the experimental results shows that the peak-to-peak variation rule is roughly in line with the natural logarithm function in the simulation. The correlation between the fitting results of the experimental data and the simulation fitting function is analyzed using the Pearson coefficient. The Pearson coefficient in the direction of Bx is ρx = 0.91386. The Pearson coefficient of the Bz direction is ρz = 0.98597, the peak-to-peak value of Bx and Bz direction is positively correlated with the depth of damage and the fitting effect of the Bz direction is better than that of the Bx direction. Full article

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Open AccessArticle

Economic, Exergoeconomic and Exergoenvironmental Evaluation of Gas Cycle Power Plant Based on Different Compressor Configurations

by

Hamad H. Almutairi

,

Abdulrahman S. Almutairi

,

Suleiman M. Suleiman

,

Abdulrahman H. Alenezi

,

Khalid A. Alkhulaifi

and

Hamad M. Alhajeri

Processes 2023, 11(4), 1023; https://doi.org/10.3390/pr11041023 - 28 Mar 2023

Abstract

The decision-making process behind the selection of a gas turbine engine (GT) is crucial and must be made in accordance with economic, environmental, and technical requirements. This paper presents the relevant economic, exergoeconomic and exergoenvironmental analyses for four GT engines with different compressor [...] Read more.

The decision-making process behind the selection of a gas turbine engine (GT) is crucial and must be made in accordance with economic, environmental, and technical requirements. This paper presents the relevant economic, exergoeconomic and exergoenvironmental analyses for four GT engines with different compressor configurations. The GT engine configurations are identified according to the type of compressor: axial, axial-centrifugal, two-stage centrifugal, and centrifugal-centrifugal. The performances of the four GT engines were validated against manufacturer supplied data using specialized software. The economic analysis, a detailed life cycle costing considering the cost to be paid per unit net power obtained from the GT, and subsequent shortest payback period showed that the GT with centrifugal-centrifugal compressor was most economically feasible. This was followed, in order, by the GT-axial, GT-axial-centrifugal, and finally the GT-two-stage centrifugal configuration, where the cost of ownership for a 20 year plan ranges between 8000 USD/kW to about 12,000 USD/kW at different operational scenarios during the life cycle costing. Exergoeconomic assessment provided useful information to enhance the cost-effectiveness of all four systems by evaluating each component separately. The axial-centrifugal configuration registered the lowest CO₂ emissions (about 0.7 kg/kWh); all environmental indicators confirmed it is the most environmentally friendly option. Full article

(This article belongs to the Topic Exergy Analysis and Its Applications – 2nd Volume)

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Open AccessArticle

Mechanical Behavior of Gas-Transmission Pipeline in a Goaf

by

,

,

,

and

Processes 2023, 11(4), 1022; https://doi.org/10.3390/pr11041022 - 28 Mar 2023

Abstract

To solve the safety hazard of a buried gas pipeline caused by subsidence of a mined-out area, a three-dimensional model of a buried pipeline in a mined-out area was established using geological parameters and the finite-element software ABAQUS. The effects of the friction [...] Read more.

To solve the safety hazard of a buried gas pipeline caused by subsidence of a mined-out area, a three-dimensional model of a buried pipeline in a mined-out area was established using geological parameters and the finite-element software ABAQUS. The effects of the friction coefficient of the pipe and soil, the coal-seam dip angle, and the horizontal angle on the mechanical behavior of the pipe under varying widths of goaf area were investigated. The results indicate that the maximum equivalent stress of the pipeline is negatively correlated with the horizontal angle. Concerning longitudinal mining, the pipeline exhibits a high-stress zone when the mining length is >200 m, the surface displacement appears in a small range when the mining length is 40 m, and the stratum displacement range increases gradually with the increase in the mining length. When the width of the goaf is constant, the maximum equivalent stress of the pipeline is positively correlated with the tube-soil friction coefficient and negatively correlated with the coal seam dip angle. The position of maximum stress gradually tends to appear near the uphill side of the coal seam, with an increase in the coal seam dip angle. Full article

(This article belongs to the Topic Multi-Phase Flow and Unconventional Oil/Gas Development)

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