Mixing Rate Research Articles

Lane management for mixed traffic flow on roadways considering the car-following behaviors of human-driven vehicles to follow connected and automated vehicles

The widespread adoption of emerging connected and automated vehicles (CAVs) highlights the need for identifying the roadway capacity of mixed traffic flow with CAVs and human-driven vehicles (HDVs) for future traffic management. Previous studies focus on analyzing the impacts of CAV technologies on the mixed traffic capacity. However, research on how different car-following behaviors of HDVs to follow CAVs affect the mixed traffic capacity is still lacking. This study proposes an analytical formulation of the mixed traffic capacity based on the probability distributions of HDVs and CAVs and three types of behavior willingness (i.e., believer, neutral, and skeptic) of HDV-following-CAV in a mixed traffic environment. The sufficient conditions are derived for mixed traffic capacity to increase or decrease with the behavior willingness and CAV penetration rate. Based on that, an analytical lane management (LM) model is further proposed to determine the optimal number of CAV dedicated lanes (CDLs) and CAV non-dedicated lane (CNL) strategies that maximize the mixed traffic throughput, considering the mixed traffic demand, behavior willingness, and CAV penetration rate. The results from numerical experiments show that the proposed LM strategies can significantly improve mixed traffic throughputs by deploying optimal CDLs and CNL strategies, compared to one without the LM strategy. The mixed traffic throughputs improve and reduce as the trust willingness and skeptic willingness increase and decrease, respectively. Moreover, the increment in CAV penetration rate does not certainly correspond to the high mixed traffic throughputs. The behavior willingness and heterogeneous headways could be jointly considered to guarantee the positive influences of CAV penetration rate on the mixed traffic throughputs when implementing the LM strategy for the mixed traffic flow.

Smart scale-up of micromixers for efficient continuous biodiesel synthesis: A numerical study for process intensification

This study focuses on developing continuous processes for biodiesel synthesis, overcoming limitations of conventional batch reactions, such as biphasic reaction and thermodynamic equilibrium, and reducing production costs. While microreactors are promising for enhancing mixing and transfer rates at smaller scales, scaling up to larger channels results in decreased efficiency and product yield. Microfluidic devices, useful in continuous biodiesel production, lose mixing efficiency when scaled up, affecting product yield. The present study proposes a novel microreactor design with static elements, aiming to improve fluid mixing and reaction performance at higher volumes. The smart scale-up strategy includes an optimized micromixer design, enlarged channel cross-sectional area, and an additional obstacle-free channel. Using a Fractional Design followed by a Central Compound Rotational Design, optimal values for key design variables are identified. Computational tests show a high mixing index (M > 0.77) across a wide range of Reynolds numbers (Re = 0.1–100). Numerical simulations under optimal conditions indicate high conversions (>91 %) for residence times above 60 s. This design promises advancements in industrial-scale biodiesel production, with improved flow and reactant distribution, potentially reducing the number of micro/millidevices needed.

Harnessing the Carrier Solvent Complexity of Crop Biostimulant Liquid Formulations Using Locally Available Transesterified Waste Cooking Oil: Economic Recycling, Solvent Performance, and Bioefficacy Evaluation.

Locally sourced waste cooking oil (WCO) was successfully base-catalyzed and transesterified with methanol into biodiesel to produce biostimulant (nitrobenzene) formulations and replace high-risk carrier solvents. Ideal synthesis conditions were composed of 1% NaOH, MeOH/oil molar ratio (6:1), reaction temperature (65 °C), a 3 h mixing rate, and 97-98% yields. Gas chromatography-mass spectrometry (GC-MS) analysis identified five fatty acid methyl esters (FAMEs) including palmitic, linoleic, oleic, stearic, and eicosenoic acids with high solubilization and olfactory characteristics. Using anionic and nonionic emulsifiers in conjunction with recycled biodiesel, a stable emulsifiable concentrate (NB 35% EC) was created with greater storage stability, wettability, and spreading capabilities than those of organic solvent-based ones. The highest counts of fruits per plant (35.80), flowers per plant (60.00), yield per plant (3.56 kg), and yield per hectare (143.7 quintals) were recorded in treatments with 4 mL/L biodiesel-based EC in field bioassays. In addition to having superior biosafety, FAME-based EC exhibits minimal phytotoxicity and is less harmful to aquatic creatures. It was discovered that the average cost-effectiveness was 5.49 times less expensive than solvent-based EC. In order to utilize waste oils as a locally obtained, sustainable alternative solvent with a wide solubilization range, low ecotax profile, circular economy, and high renewable carbon index, this integrative technique was expanded.

U–Pb zircon dating, Sr-Nd whole-rock and Lu-Hf zircon isotope analyses of the Eocene Arslandede pluton, Eastern Pontides, NE Turkey: Implications for mantle source and magma evolution

The Eastern Pontide Orogenic Belt (EPOB) hosts numerous plutonic bodies with different dimensions, compositions and ages ranging from Paleozoic to Late Eocene in NE Turkey. U-Pb zircon dating suggests that the Arslandede pluton crystallized at 44.50 ± 0.29 Ma, corresponding to the Lutetian (Middle Eocene) period. Rocks of this pluton have monzonitic character, with compositions ranging from monzodiorite to granite (SiO2 = 49˗71 wt%). The studied monzonitic rocks have I-type, metaluminous and shoshonitic character and are enriched in large-ion lithophile elements (LILEs). The rare earth elements (REEs) have concave up shape (LaN/YbN = 6.64–11.57) and show negative to slightly positive Eu anomalies (EuN/Eu* = 0.37–1.24). 87Sr/86Sr(i) values of 0.704801–0.705102 and εNd(i) values of 1.01–1.34 correspond to the mantle series on isotope ratio diagrams. Positive εHf(i) values (5.01–14.91) plot between the depleted mantle and the chondritic evolution lines. The petrological features of the rocks from the Arslandede pluton show that fractional crystallization with low rates of assimilation and/or magma mixing were effective during crystallization. All data show that the magma source of the pluton derived from an enriched lithospheric mantle and emplaced into the crust after differentiation in a deep seated magma chamber contaminated by relatively small proportions of crustal rocks.

Medicare skilled nursing facilities' occupancy and payer source: The moderating role of financial performance.

While extensive research has focused on patient outcomes in skilled nursing facilities, a critical gap remains in understanding factors influencing their managerial performance, particularly occupancy rates. This study examines the occupancy rates of skilled nursing facilities and assesses the significance of two important drivers of managerial performance that have not received sufficient attention-the influence of payer mix and total profit margin. Specifically, we focused on the role played by a nursing home's financial performance (as assessed by profit margin) in influencing the relationship between payer mix and occupancy rate among skilled nursing facilities. Data were extracted from the 2019 to 2020 Joint Annual Report of Nursing Homes for a sample of 612 skilled nursing facilities in Tennessee, USA. Regression analysis was performed by fitting a generalized estimating equation of occupancy rate. Compared to skilled nursing facilities in the lowest quartile of profit margin, for example, those in the highest quartile had approximately 18 percentage points higher occupancy rates per unit increase in resident days of care covered by traditional Medicare (β = 0.18, p = 0.0028). Similarly, skilled nursing facilities in the second highest quartile of profit margin had a higher occupancy rate by approximately 23 percentage points per unit increase in Medicare Advantage (β = 0.23, p = 0.0375) when compared to those in the lowest quartile of profit margin. Skilled nursing facilities with stronger financial performance generally have higher occupancy rates, particularly notable in relation to an upswing in payer sources such as traditional Medicare and Medicare Advantage, when compared to skilled nursing facilities with weaker profitability. Given the increasingly larger role of Medicare in long-term care funding, policymakers and nursing home managers may find it useful to consider our findings when evaluating opportunities to enhance managerial performance of skilled nursing facilities.

Human papillomavirus prevalence and genotype distribution in Liaocheng men between 2016 and 2022.

Human papillomavirus (HPV) infection can lead to HPV-related cancer in men, including the anus, penile, and oropharyngeal cancers and precancerous lesions. This study retrospectively investigated HPV prevalence and genotype distribution in Liaocheng men between 2016 and 2022. The total HPV positive rate was 64.87% (2388/3681, 95% confidence interval [CI]: 63.32%-66.40%), where high risk (HR)-HPV and low risk (LR)-HPV accounted for 42.49% (1564/3681, 95% CI: 40.90%-44.09%) and 69.71% (2566/3681, 95% CI: 68.20%-71.17%), respectively. The mixed HPV infection rate of two and more genotypes was 35.72%. The infection rate of HR-HPV increased with the number of positive cases annually from 2016 (16.91%) to 2022 (46.59%). The most common HR-HPV genotypes were HPV16 (11.60%), HPV52 (6.95%), and HPV59 (6.28%), whereas the least common HR-HPV was HPV26. The most common LR-HPV genotypes were HPV6 (56.99%), HPV11 (23.79%), and HPV43 (6.37%). The 9 v HPV vaccine preventable for LR-HPV and HR-HPV accounted for 80.78% and 30.40%, respectively, in this study. Most HPV-positive patients aged 1-86 were in the 30-39 age group. This study confirmed that HPV prevalence in Liaocheng men was common and diverse. HPV16, HPV52, and HPV59 are widely distributed in Liaocheng men, and the male HR-HPV infection rate remained high in this region. Regarding public health and cancer prevention, it is recommended and effective to include the HPV vaccination in the national vaccination program for men.

Synergistic effect study of Chlorella vulgaris and polyethylene in co-pyrolysis process based on kinetic and thermodynamic analysis

The co-pyrolysis of algae and plastics shows great potential for bio-oil production. In this study, thermogravimetric analyzer was used to investigate the pyrolysis behavior of Chlorella vulgaris (CV) and polyethylene (PE) at different mixed ratios and heating rates. Their synergistic effects were discussed through kinetic and thermodynamic analyses. According to the thermogravimetric (TG) and Derivative thermogravimetric (DTG) curves, the co-pyrolysis process can be divided into five stages, corresponding to the decomposition of moisture, carbohydrates, proteins, lipids, and biochar, respectively. In the fifth stage, a clear synergistic effect is observed, with the highest ∆TG reaching about 4%. During the co-pyrolysis process, the average activation energy of the mixtures is much lower than expected, indicating the presence of a synergistic effect in co-pyrolysis. Among them, 3CV1PE is the optimal mixing ratio, with the average activation energy of 3CV1PE being 6% lower than that of CV pyrolysis alone. The master plots revealed that the power law reaction models (P3 and P4) are suitable for describing the experimental behavior of mixtures with higher CV content, while the third-order (F3) and eighth-order model (F8) are more appropriate for the decomposition reaction with higher PE content. The calculation of thermodynamic parameters further show that the co-pyrolysis of CV and PE is beneficial to the decomposition process, and the mixed ratio of 3:1 is the most favorable for the reaction. Results obtained in this work are valuable for guiding research on the co-pyrolysis of biomass and plastics.

Synthesis and characterization of new electrospun medical scaffold-based modified cellulose nanofiber and bioactive natural propolis for potential wound dressing applications.

Recently, the design of polymer nanofibers using the electrospinning process has attracted much interest. Particularly the use of natural polymers has promoted many advantages in their biomedical applications. However, the combination of multiple natural polymers remains a great challenge in terms of electrospun production and applied performance. From this perspective, the current investigation highlights the study of the preparation of electrospun nanomaterial scaffolds based on combined natural polymers for improved wound healing performance. First, we have synthesized a crosslinked polymer by reacting microcrystalline cellulose (MC) and chitosan (CS) biopolymer via the intermediate of citric acid as a crosslinking agent. Then a natural propolis biomolecule was incorporated into the polymer network. Different MC/CS blend ratios of 90/10 and 70/30 were then used and various machine parameters were optimized to obtain nanofiber scaffolds with excellent strength and structures. SEM, IR, physicochemical, mechanical, and morpho-logical characterization were then performed. SEM evaluation revealed homogeneous and bead-free nanofibrous structures, with well-defined morphology and a random deposition that could accurately mimic the extracellular matrix of native skin. The calculated average nanofiber diameters for the MC/CS blend ratios at 90/10 and 70/30 were 431.4 and 441.2 nm, respectively. The results showed that when the chitosan amount increased, larger nanofibers with narrow diameter distribution appeared. The prepared nanomaterials had a significant and close water vapor permeability of about 1735.12 and 1698.52 g per m per day for the two blend ratios of 90/10 and 70/30, respectively. The examination of swelling behavior revealed a noteworthy enhancement in hydrophilicity, a necessary attribute for improved healing efficacy. FT-IR analysis confirmed the success and the stability of the chemical crosslinking reaction between the two biopolymers before nanofiber conception. Excellent mechanical properties were acquired, based on the chitosan content. Both developed nanofiber scaffolds exhibited high tensile strength and Young's modulus values. The incorporation of 30% chitosan versus 10% results in an increase in tensile strength of 11% and 14% in Young's modulus. Therefore, we could adjust the different mechanical properties simply by varying the mixing rate of the electrospun polymers. Using epithelial HepG2 cells, viability and kinetic cell adhesion assays were assessed to obtain biological evaluation. No cytotoxicity was observed and good cytocompatibility was confirmed. Functionalized nanofiber biomaterials with different MC/CS ratios substantiated significant bactericidal effectiveness against Gram-positive and Gram-negative bacterial culture strains. The novel functional electrospun wound dressing scaffold demonstrated effective and promising biomedical performance, healing both acute and chronic wounds.

Validation of the Psychometric Properties of the Practice Environment Scale of Nursing Work Index (PES-NWI) Questionnaire in the Context of Kenya’s Nursing Organizational Work Culture

BackgroundThe global shortage of nurses is posing a significant threat to the provision and sustainability of quality health care services worldwide. The importance of nursing organizational culture and validated tools to accurately measure it, is of paramount importance in mitigation of this shortage, especially in Low- and middle-income-countries like Kenya. MethodologyThis was a cross-sectional online validation survey among 212 nursing personnel working in various healthcare facilities across Kenya. The aim of the study was to assess the validity and reliability of the psychometric properties of the Practice Environment Scale of Nursing Work Index within the framework of nursing organizational culture in Kenya and determine how Kenyan nurses rate their organizational culture. Data was analyzed using SPSS version 28. Cronbach’s alpha was used to determine reliability while Exploratory Factor Analysis and Confirmatory Factor Analysis were used to test validity. ResultsThe 5-structure of Lake’s PES-NWI was unsupported by confirmatory factor analysis and a new 7-Factor Kenyan PES-NWI version was created. The new tool was reliable and with acceptable fit. Participants showed a mixed rating of their organizational culture with overall organizational culture largely rated neutral (M = 2.51, SD = 1.01). ConclusionThe Kenyan PES-NWI is a valid and reliable tool that could be used to assess organizational culture. The study highlighted the critical need to further develop context-specific tools to accurately measure nursing organizational culture work environments particularly in Low and-Middle-Income countries like Kenya facing significant nursing shortages. As nursing becomes increasingly dynamic and complex, it is essential for nursing and healthcare researchers to re-validate research tools to continuously improve them.

Simulations of three-layer Richtmyer–Meshkov mixing in a shock tube

The Richtmyer–Meshkov instability causes perturbations to grow after a shock traverses a fluid density interface. This increases the mixing rate between fluid from either side of the interface. We use the Flash Eulerian hydrodynamic code to investigate alterations when a thin third layer of intermediate density is placed along the interface, effectively creating two adjacent unstable interfaces. This is a common occurrence in engineering applications where a thin barrier initially separates two materials. We find that the width of the mixing layer is similar or slightly reduced; however, the total mass of mixed material can actually increase. The mixing layer becomes more compact and efficient. However, the normalized mixed mass decreases, meaning that finger entrainment becomes more important than in the simple two-layer case. The effect of adding the central layer appears to decrease when the Atwood number is decreased. The Flash results are also benchmarked against two-layer experimental data from a shock tube at the University of Arizona.

On the effect of injection pressure on spray combustion and soot formation processes of gasoline/second generation biodiesel blend

70GB, which comprises 70% gasoline and 30% biodiesel, shows excellent potential for application in gasoline compression ignition due to its superior lubrication capability, renewability, environmental friendliness, high ignitability contributed by biodiesel namely as Hydrogenated catalytic biodiesel (HCB), and high volatility conferred by gasoline. However, the spray combustion and emission characteristics of 70GB fuel have not yet been quantitatively evaluated. In this work, we performed a comprehensive simulation focusing on the ignition delay, heat release rate, flame lift-off length, flame structure, and soot formation of 70GB in a constant volume chamber under various fuel injection pressure. Numerical results showed that, different injection pressure strongly impact the HRR without affecting the maximum temperature. Increasing the injection pressure from 80 to 120 Mpa, increased the heat release rates by 23. %. The ignition delay was marginally affected by increasing injection pressure, while a 5.7 mm increase in flame lift-off length observed with higher injection pressure. Additionally, 65% lower soot formation was typically predicted for higher injection pressure 120MPa. In particular, the soot mass is primarily controlled by enhancing the atomization and evaporation processes, as well as improving fuel-air mixing rate, which was achieved by increasing the injection pressure. Furthermore, the role of soot oxidation was insignificant in reducing soot with increasing injection pressure, while the soot initiation step and soot surface growth step play an important role in soot suppression with increasing injection pressure for 70G fuel.

Numerical Analysis for Effects of Grid Spacer Vane on Flow-Thermal Characteristics of Two Phase Flow in a 5×5 Rod Bundle

Numerical Analysis for Effects of Grid Spacer Vane on Flow-Thermal Characteristics of Two Phase Flow in a 5×5 Rod Bundle

混秸带翼凿式犁关键部件扰动规律的研究

Understanding the soil-straw disturbance pattern of the key component parameters of the straw mixing winged chisel plow is the key to designing and optimizing the straw mixing winged chisel plow (a chisel plow for mixing and mulching straw). In this study, a straw-soil-winged chisel plow interaction model was established, and the working principle, key components of the winged chisel plow were determined based on soil bin experiment and theoretical analysis. Discrete element method (DEM) was used to study the influence of disturbance pattern of key components of the winged chisel plow on soil-straw displacement, straw mixing rate and draught force. The results show that the main components of the winged chisel plow that affect the operating efficiency of the implement are the soil lifting plate height, the wing mounting height and the wing width. The height of the soil lifting plate affects the efficiency of the winged chisel plow in secondary disturbance of soil-straw and its own performance in turning over soil, with an optimal range of 110 mm-170 mm. The installation height of the wing mounting mainly affects the position of the soil lifting plate in the soil layer. In order to achieve the best operating effect, the position of the soil lifting plate needs to meet the "lower lifting and upper turning" requirement. The optimal installation height of the wing mounting is 95 mm-145 mm. The width of the wing mainly affects the working width of the implement, and its optimal value is 180 mm-220 mm. The width of the wing mainly affects the working width of the implement, and its optimal value is 180 mm-220 mm. The established simulation relative error is within 12.60%, which can better study the disturbance pattern of soil-straw. This study may provide a reference for optimizing and designing wing-type chisel plows and subsoil shovels.

AntiHalluciNet: A Potential Auditing Tool of the Behavior of Deep Learning Denoising Models in Low-Dose Computed Tomography.

Gaining the ability to audit the behavior of deep learning (DL) denoising models is of crucial importance to prevent potential hallucinations and adversarial clinical consequences. We present a preliminary version of AntiHalluciNet, which is designed to predict spurious structural components embedded in the residual noise from DL denoising models in low-dose CT and assess its feasibility for auditing the behavior of DL denoising models. We created a paired set of structure-embedded and pure noise images and trained AntiHalluciNet to predict spurious structures in the structure-embedded noise images. The performance of AntiHalluciNet was evaluated by using a newly devised residual structure index (RSI), which represents the prediction confidence based on the presence of structural components in the residual noise image. We also evaluated whether AntiHalluciNet could assess the image fidelity of a denoised image by using only a noise component instead of measuring the SSIM, which requires both reference and test images. Then, we explored the potential of AntiHalluciNet for auditing the behavior of DL denoising models. AntiHalluciNet was applied to three DL denoising models (two pre-trained models, RED-CNN and CTformer, and a commercial software, ClariCT.AI [version 1.2.3]), and whether AntiHalluciNet could discriminate between the noise purity performances of DL denoising models was assessed. AntiHalluciNet demonstrated an excellent performance in predicting the presence of structural components. The RSI values for the structural-embedded and pure noise images measured using the 50% low-dose dataset were 0.57 ± 31 and 0.02 ± 0.02, respectively, showing a substantial difference with a p-value < 0.0001. The AntiHalluciNet-derived RSI could differentiate between the quality of the degraded denoised images, with measurement values of 0.27, 0.41, 0.48, and 0.52 for the 25%, 50%, 75%, and 100% mixing rates of the degradation component, which showed a higher differentiation potential compared with the SSIM values of 0.9603, 0.9579, 0.9490, and 0.9333. The RSI measurements from the residual images of the three DL denoising models showed a distinct distribution, being 0.28 ± 0.06, 0.21 ± 0.06, and 0.15 ± 0.03 for RED-CNN, CTformer, and ClariCT.AI, respectively. AntiHalluciNet has the potential to predict the structural components embedded in the residual noise from DL denoising models in low-dose CT. With AntiHalluciNet, it is feasible to audit the performance and behavior of DL denoising models in clinical environments where only residual noise images are available.

Effects of Silica-Biochar, Bentonite and Diatomite Ratios on Properties of Controlled Release Fertilizer

Controlled slow release fertilizer (CRF) in this study was produced by mixing Silica-Biochar (SB), Bentonite (B), and Diatomite (D) at different ratios with N, P, K form customized crystal membrane to control the dissolution of N, P, K into water. Research results show that the mixing rate of SB and B significantly affects the pelleting process, decay rate, hardness, and air hygroscopicity of CRF fertilizer. The decay rate is more than 20% after 13 and 5 days and greater than 80% after 17 and 9 days, respectively with SB mixing ratio of 30 and 40%. The maximum hardness of CRF fertilizer was 3.2 kg/cm2 and the smallest was 1.6 kg/cm2 respectively with the SB used ratio of 30 and 40%. With the mixing rate of SB at 30%, the resulting CRF fertilizer has the smallest hygroscopicity. With the mixing rate of B at 5%, the resulting decay rate of CRF was the smallest. The mixing rate of B did not affect the air hygroscopicity of CRF fertilizers. The different mixing rates of diatomite used did not affect the decay rate, hardness, and air hygroscopicity of CRF fertilizers.&#x0D;

Clinical evaluation of a multiplex droplet digital PCR for pathogen detection in critically ill COVID-19 patients with bloodstream infections

BackgroundNosocomial bloodstream infections (nBSI) have emerged as a clinical concern for physicians treating COVID-19 patients. In this study, we aimed to evaluate the effectiveness of a multiplex ddPCR in detecting bacterial pathogens in the blood of COVID-19 critically ill patients.MethodsThis prospective diagnostic study included RT-PCR-confirmed COVID-19 patients admitted to our hospital from December 2022 to February 2023. A multiplex ddPCR assay was used to detect common bacterial pathogens and AMR genes in blood samples of the patients, along with antimicrobial susceptibility testing (AST). The diagnostic performance of the ddPCR assay was evaluated by comparing the results with those obtained through blood culture and clinical diagnosis. Additionally, the ability of ddPCR in detecting bacterial resistance was compared with the AST results.ResultsOf the 200 blood samples collected from 184 patients, 45 (22.5%) were positive using blood culture, while 113 (56.5%) were positive for bacterial targets using the ddPCR assay. The ddPCR assay outperformed blood culture in pathogen detection rate, mixed infection detection rate, and fungal detection rate. Acinetobacter baumannii and Klebsiella pneumoniae were the most commonly detected pathogens in COVID-19 critically ill patients, followed by Enterococcus and Streptococcus. Compared to blood culture, ddPCR achieved a sensitivity of 75.5%, specificity of 51.0%, PPV of 30.9%, and NPV of 87.8%, respectively. However, there were significant differences in sensitivity among different bacterial species, where Gram-negative bacteria have the highest sensitivity of 90.3%. When evaluated on the ground of clinical diagnosis, the sensitivity, specificity, PPV and NPV of ddPCR were 78.1%, 90.5%, 94.7%, and 65.5%, respectively. In addition, the ddPCR assay detected 23 cases of blaKPC, which shown a better consistent with clinical test results than other detected AMR genes. Compared to blaKPC, there were few other AMR genes detected, indicating that the application of other AMR gene detection in the COVID-19 critically ill patients was limited.ConclusionThe multiplex ddPCR assay had a significantly higher pathogen detection positivity than the blood culture, which could be an effective diagnostic tool for BSIs in COVID-19 patients and to improve patient outcomes and reduce the burden of sepsis on the healthcare system, though there is room for optimization of the panels used.- Adjusting the targets to include E. faecalis and E. faecium as well as Candida albicans and Candida glabrata could improve the ddPCR' s effectiveness. However, further research is needed to explore the potential of ddPCR in predicting bacterial resistance through AMR gene detection.

High shear reactor for glycerolysis—Interesterification palm stearin‐olein blend: Reaction kinetics and physical properties

AbstractStructured lipids containing high monoacylglycerol (MAG) and diacylglycerol (DAG) (SLs‐MDAG) were synthesized by chemical glycerolysis‐interesterification using sodium metasilicate as the catalyst in High Shear Reactor (HSR). The objective of this research was to investigate the effect of temperature on the glycerolysis‐interesterification kinetics at relatively low temperatures in an HSR and the physical product properties. The reaction was performed using immiscible and highly viscous reactants at various temperatures (80–120°C) and a mixing rate of 2000 rpm for 5 h. Results showed that the reaction rate constant exponentially increased as temperature increased. Triacylglycerol (TAG) conversion was 2.5 fold greater at 110 and 120°C compared to lower reaction temperatures (80 and 90°C). MAG and DAG increased by about 18.3% and 13.4%, respectively, as the reaction temperature increased from 80 to 120°C. The product's melting point, hardness, and color were also improved by increasing temperature. In summary, SLs‐MDAG could be produced at a relatively low temperature (110°C) using HSR. The glycerolysis‐interesterification kinetic displayed an exponential relationship, even though it did not precisely fit the Arrhenius model.

Bazı Magnezyum Alaşımlarında Sürünme Hızı, Termal İletkenlik ve Karışım Entalpisi Arasındaki İlişkinin İncelenmesi

Magnesium (Mg) and its alloys are known for their high specific strength, but they have limitations that need to be addressed to expand their range of industrial use. One major limitation is their high temperature performance, which requires improvement for them to be used in industries such as aviation where creep resistance is important. In this study, we investigated the creep behavior of several Mg alloys, including the commercially used AZ series (AZ31, AZ61, and AZ91), as well as the AM50, AX52, and AE42 alloys. We studied the relationship between the creep rate of these alloys and two material properties: thermal conductivity and enthalpy of mixing. By analyzing these properties, we can compare and evaluate newly developed or existing alloys in terms of their creep behavior. When the obtained results are interpreted in general, a linear relationship is found between the creep rate, thermal conductivity and enthalpy of mixing as a general trend.

N2 injection to enhance gas drainage in low-permeability coal seam: A field test and the application of deep learning algorithms

N2 injection to enhance coal seam gas drainage is an effective technology for coalbed methane recovery. Nevertheless, there is a limited body of research addressing the application of ECBM technology for gas management in low permeability coal seams within underground coal mines, and the effect is uncertain. Additionally, numerical simulators have been challenged to accurately predict methane emissions during gas injection and replacement. In this study, firstly, an underground field trials of N2 injection replacement in a coal mine with low-permeability coal seams in China were conducted, and a comparative analysis of “N2 injection to enhance gas drainage” and “conventional drainage” technique was performed. The result show that injecting pressurized N2 into a low-permeability coal seam could increase the pressure gradient to promote the directional flow of free gas from the coal seam cracks to the gas-production boreholes. After N2 injection, the mixed flow rate and CH4 flow rate significantly increased. Additionally, the gas content in the coal seam in the experimental area significantly decreased. Secondly, the lag-effect was discussed. Upon discontinuation of N2 injection, the gas-producing mixed flow initially increased slightly, then gradually decreased, and eventually settled at a high level. Despite the attenuation of N2 injection volume, the CH4 flow rate continued to increase during intermittent injection and remained high after gas injection discontinuation. Finally, three deep learning algorithms (BP, LSTM, and TCN) were employed to predict the dynamic change of gas drainage in coal seams displaced by N2 injection, based on the results of the field test. The results indicated that deep learning algorithms exhibited superior prediction performance. The TCN model demonstrated the lowest approximation error rate, displaying optimal performance in predicting the CH4 flow rate during nitrogen injection for enhanced gas drainage. Additionally, it exhibited good applicability to other similar field test results.

CFD Analysis of Effects of Grid Spacer Vane on Thermal-Hydraulic Performance of Fluid in a 5×5 Fuel Channel

A grid spacer with a vane is an influential segment in reactor fuel channels. A vane produces significant effects on flow mixing and augmentation of heat transfer in subchannnels. The purpose of this work was to do a computational fluid dynamics (CFD) analysis on the effects of a grid spacer vane on the thermal-hydraulic performance of fluid in a 5×5 fuel channel. A square array of a 5×5 fuel channel was used for this analysis with a pitch–to–rod diameter ratio of 1.33 and a blockage ratio of the grid spacer of 0.16. The relative study was made for the thermal-hydraulic performance among a grid spacer with a vane, a grid spacer (without a vane), and without a grid spacer (bare bundle). Analyses were made for fluid pressure of 15.5 MPa, inlet temperature of 583 K, and velocity of 4.74 m/s. The SST k-ω and RNG k-ε turbulence models were used to analyze flow phenomena and thermal performance. CFD results were validated with experiment data and were also compared with correlations proposed by researchers. The results were analyzed by different methods such as data curves, streamlines, and vector and contour plots. The results show that the strong characteristics of swirl flow in subchannels cause a greater mixing rate of turbulent flow, which hence improves heat transfer performance. The swirl ratio was observed maximum close downstream to a grid spacer with a vane. Grid spacer effects on heat transfer were noticed from z/Dh = 0 to 20 in downstream.