Mixed Fraction Research Articles

Discriminating between different scenarios for the formation and evolution of massive black holes with LISA

Electromagnetic observations have provided strong evidence for the existence of massive black holes in the center of galaxies, but their origin is still poorly known. Different scenarios for the formation and evolution of massive black holes lead to different predictions for their properties and merger rates. LISA observations of coalescing massive black hole binaries could be used to reverse engineer the problem and shed light on these mechanisms. In this paper, we introduce a pipeline based on hierarchical Bayesian inference to infer the mixing fraction between different theoretical models by comparing them to LISA observations of massive black hole mergers. By testing this pipeline against simulated LISA data, we show that it allows us to accurately infer the properties of the massive black hole population as long as our theoretical models provide a reliable description of the Universe. We also show that measurement errors, including both instrumental noise and weak lensing errors, have little impact on the inference.

Characterizing plastics from large household appliances: Brominated flame retardants, other additives and density profiles

Large household appliances contain substantial amounts of plastics. At their end of life, these appliances are processed in waste electrical and electronic equipment (WEEE) treatment plants where a mixed plastic fraction is generally obtained after mechanical processing. This paper presents the results of a study conducted to investigate whether the practice of recycling these plastic streams without decontamination can be continued after the introduction of the 1000 mg/kg threshold value for the sum of polybrominated diphenyl ethers (PBDEs) in the 2019 recast of the European POP regulation. 25 samples of shredded mixed plastics from large household appliances were collected and analysed by two independent chemical laboratories with regard to various Brominated Flame Retardants (BFRs), heavy metals and tracers of common plastic additives. Results show that the currently applicable threshold values for recycling regarding heavy metals and BFRs are not exceeded in any of the analysed samples. However, relevant amounts of PBDEs (up to 791 mg/kg), tetrabromobisphenol-A (up to 1470 mg/kg) and antimony (up to 1200 mg/kg) were detected, all of which are currently under consideration for more stringent regulation in the EU. Results further show that due to limitations in analytical precision and representative sampling, the quantification of legacy substances in mixed WEEE plastic fractions is very challenging and the level of confidence with which decisions regarding legal compliance for recycling are taken is limited. It is strongly recommended that these challenges are taken into account when new threshold values are defined in order to enable a clean circular economy.

Statistical characteristics of turbulent mixing in spherical and cylindrical converging Richtmyer–Meshkov instabilities

In this paper, the Richtmyer–Meshkov instabilities in spherical and cylindrical converging geometries with a Mach number of approximately 1.5 are investigated by using the high resolution implicit large eddy simulation method, and the influence of the geometric effect on the turbulent mixing is investigated. The heavy fluid is sulphur hexafluoride (SF6), and the light fluid is nitrogen (N2). The shock wave converges from the heavy fluid into the light fluid. The Atwood number is 0.678. The total structured and uniform Cartesian grid node number in the main computational domain is 20483. In addition, to avoid the influence of boundary reflection, a sufficiently long sponge layer with 50 non-uniform coarse grids is added for each non-periodic boundary. Present numerical simulations have high and nonlinear initial perturbation levels, which rapidly lead to turbulent mixing in the mixing layers. Firstly, some physical-variable mean profiles, including mass fraction, Taylor Reynolds number, turbulent kinetic energy, enstrophy and helicity, are provided. Second, the mixing characteristics in the spherical and cylindrical turbulent mixing layers are investigated, such as molecular mixing fraction, efficiency Atwood number, turbulent mass-flux velocity and density self-correlation. Then, Reynolds stress and anisotropy are also investigated. Finally, the radial velocity, velocity divergence and enstrophy in the spherical and cylindrical turbulent mixing layers are studied using the method of conditional statistical analysis. Present numerical results show that the geometric effect has a great influence on the converging Richtmyer–Meshkov instability mixing layers.

OPR1000 TI-SGTR 사고 MELCOR 해석의 자연순환유동 입력인자 생산을 위한 CFD 해석

We performed a 3-dimensional CFD analysis of a natural convective flow in the steam generator (SG) inlet plenum of an optimized power reactor 1000 MWe (OPR1000) to generate input parameters of the MELCOR code, a 1-dimensional lumped parameter code, which will be used in analyzing the temperature induced steam generator tube rupture (TI-SGTR) accident. The input parameters used in the MELCOR calculation will account for a 3-dimensional effect in the natural convective flow in the SG inlet plenum. To produce a credible CFD analysis result, we first established a CFD analysis methodology, which is developed from validation analyses against the steam generator design data of the OPR1000 and the Westinghouse 1/7 scaled-down test data, for the thermal mixing flow calculation between the SG and the reactor pressure vessel in the OPR1000. Though this CFD analysis, we produced the MELCOR input parameters, the recirculation ratio 1.96, thermal mixing fraction 0.79, discharge coefficient 0.13, and hot tube fraction 0.40, with an error range of approximately 10% to 25%. The input parameters will be used in the MELCOR analysis to evaluate a radioactive material release from broken SG tubes during the TI-SGTR accident.

New insights on binary black hole formation channels after GWTC-2: young star clusters versus isolated binaries

ABSTRACT With the recent release of the Second Gravitational Wave Transient Catalog (GWTC-2), which introduced dozens of new detections, we are at a turning point of gravitational wave astronomy, as we are now able to directly infer constraints on the astrophysical population of compact objects. Here, we tackle the burning issue of understanding the origin of binary black hole (BBH) mergers. To this effect, we make use of state-of-the-art population synthesis and N-body simulations, to represent two distinct formation channels: BBHs formed in the field (isolated channel) and in young star clusters (dynamical channel). We then use a Bayesian hierarchical approach to infer the distribution of the mixing fraction f, with f = 0 (f = 1) in the pure dynamical (isolated) channel. We explore the effects of additional hyperparameters of the model, such as the spread in metallicity σZ and the parameter σsp, describing the distribution of spin magnitudes. We find that the dynamical model is slightly favoured with a median value of f = 0.26, when σsp = 0.1 and σZ = 0.4. Models with higher spin magnitudes tend to strongly favour dynamically formed BBHs (f ≤ 0.1 if σsp = 0.3). Furthermore, we show that hyperparameters controlling the rates of the model, such as σZ, have a large impact on the inference of the mixing fraction, which rises from 0.18 to 0.43 when we increase σZ from 0.2 to 0.6, for a fixed value of σsp = 0.1. Finally, our current set of observations is better described by a combination of both formation channels, as a pure dynamical scenario is excluded at the $99{{\ \rm per\ cent}}$ credible interval, except when the spin magnitude is high.

Oryza Ceramide®, a rice-derived extract consisting of glucosylceramides and β-sitosterol glucoside, improves facial skin dehydration in Japanese subjects

Background and objective: The ingestion of plant-derived glucosylceramides (GlcCer) has been reported to contribute to skin barrier function and hydration of the epidermis. b-sitosterol glucoside (BSG) colocalized with GlcCer in the rice hydrophobic fraction has been shown to increase ceramides in the stratum corneum in vitro. Although clinical studies demonstrated that GlcCer reduced transepidermal water loss (TEWL), the contribution of BSG to epidermal dehydration when applied with GlcCer remains unknown. Therefore, we herein conducted a clinical trial on the effects of a rice-derived mixed fraction of GlcCer and BSG (Oryza Ceramide®) on TEWL and other skin parameters. Methods: A randomized, double-blind, placebo-controlled study design was used. Oryza Ceramide® (type PCD, 40 mg daily) containing 1.2 mg of GlcCer and 40 mg of BSG was used as the active sample. We enrolled 44 healthy Japanese women with epidermal dehydration. All subjects were randomly allocated to an active group (n=22) or placebo group (n=22) using a computerized random number generator. Capsules containing the active sample or placebo were administered for 12 weeks between August and December 2020. Cheek TEWL after 12 weeks was assessed as the primary outcome, and TEWL on a different part of the skin and various skin parameters, including epidermal moisture, pigmentation, pores, and elasticity, were measured before and after 4, 8, and 12 weeks of the intervention. Blood, urine, and body parameters were also examined to evaluate safety.Results: Forty-four subjects completed the trial, and the per protocol set comprised 22 each in the active and placebo groups. Cheek TEWL significantly reduced after the Oryza Ceramide® intervention for 4 and 12 weeks. Among the secondary outcomes examined, lip moisture (12 weeks) and visible pore number (4 weeks) were improved by Oryza Ceramide®. Laboratory tests revealed no abnormalities to suggest any adverse effects of Oryza Ceramide®.Conclusions: Oryza Ceramide® (40 mg/day) consisting of GlcCer and BSG improved facial TEWL, lip moisture, and visible pores, and these effects may be attributed to increases in epidermal ceramides. The combination of rice GlcCer and BSG appears to be beneficial for improving facial skin conditions.Trial Registration: UMIN-CTR: UMIN000041295Foundation: The study was funded by Oryza Oil & Fat Chemical Co., Ltd. and Aichi Prefectural Subsidies for Research and Development of Creative Products in 2020.Keywords: rice; glucosylceramide; β-sitosterol glucoside; trans epidermal water loss; pore

Anti-androgenic compounds in breast milk and cryptorchidism among Norwegian boys in the HUMIS birth cohort

The prevalence of cryptorchidism has increased over the past decades, yet its origins remain poorly understood. Testis descent is dependent on androgens and likely affected by endocrine disrupting compounds (EDCs), targeting the androgen receptor (AR). We investigated the association between anti-androgenic activity, not derived from natural hormones, in maternal breast milk and impaired testis descent among boys. We performed a case-control study based on 199 breast milk samples from 94 mothers of cryptorchid boys and 105 random non-cryptorchid boys participating in the Norwegian HUMIS (Human Milk Study) cohort. For each participant, apolar, and polar fractions were extracted, and combined to reconstitute a mixture. Anti-androgenic activity was measured in all three fractions using the human cell-based in vitro anti-AR CALUX® assay and expressed in μg of flutamide equivalent, a well-known antiandrogen. Results from fraction analyses were compared among boys with cryptorchidism and controls using multiple logistic regression, controlling for appropriate confounders identified using a directed acyclic graph. Children's daily exposure to anti-androgenic EDCs through breastfeeding was estimated to 78 μg flutamide eq./kg of body weigh/day. The activity was higher in the polar fraction (1.48 ± 1.37 μg flutamide eq./g of milk) mainly representing non-persistent chemicals, in contrast to other fractions. However, the activity in the polar extracts was decreased when in mixtures with the apolar fraction, indicating synergistic interactions. No significant difference in the activity was observed according to cryptorchid status for polar, apolar or mixed breast milk fractions. The study showed anti-androgenic activity in nearly all human milk samples, and at levels higher than the advisory threshold. However, no significant association was observed between cryptorchidism and antiandrogenic activity measured in either polar, apolar, or mixture fractions derived from breast milk.

Functional and Patient-Centered Treatment Outcomes with Mandibular Overdentures Retained by Two Immediate or Conventionally Loaded Implants: A Randomized Clinical Trial.

This study aims to assess the treatment outcomes (functional and subjective) of mandibular overdentures retained on two implants with or without an immediate loading protocol. In this randomized clinical trial, twenty fully edentulous patients were treated with a mandibular two-implant-retained overdenture and a complete new maxillary denture. In half of the sample, the implants were loaded immediately by means of VulkanLoc® abutments after emplacement of the implant, but in the counterparts, these VulkanLoc® abutments were connected to implants two months after the surgery (conventional protocol), and until that time the dentures were retained by healing abutments. Treatment outcomes were assessed at two, six, and twelve months after surgery. Functional outcomes were calculated according to masticatory performance, estimated by the mixed fraction of a two-coloured chewing gum after five, ten, and fifteen chewing strokes, by the occlusal force recorded by pressure-sensitive sheets, and by the bioelectrical muscular activity. The subjective outcomes of the treatment were assessed using both the oral satisfaction scale (visual analogue scale) and the Spanish version of the Oral Health Impact Profile (OHIP-20). The findings of the present study show that new complete dentures resulted in significant improvements in chewing ability, patient satisfaction, and oral health-related quality of life and that subsequent implant-retained overdentures produced further and faster significant improvements. The loading protocol may influence those positive self-reported outcomes rather than the objective functional evaluations.

Rainfall types in the lifecycle of a stationary cloud cluster during the Indian Summer Monsoon: An investigation with numerical simulations and radar observation

The performance of three microphysics schemes (WRF Double Moment 6-class (WDM6), Morrison double moment (MORR), and spectral bin microphysics (Fast version) (SBMF)), with increasing complexities, in simulating various rainfall-types during the lifecycle of a tropical continental mesoscale cloud cluster (CC) are presented in this study. The CC spent its entire lifetime over the surveillance area of a polarimetric C-band radar, over the peninsular Indian region in a monsoon environment. Observed and simulated rainfall properties throughout the lifecycle of the CC are intercompared. A rainfall-type categorization algorithm has been applied to the observed and model simulated reflectivity fields. Microphysics scheme with the least complexities produced the highest convective rainfall-type, lowest stratiform rainfall-type, and a remarkable early cessation of the CC. With increasing complexities, the microphysics schemes are found to represent the rainfall-types more close to radar observations. Major differences are noted during the mature and dissipation phases, especially in the stratiform rainfall-type. The rainfall-types derived from radar, as well as three simulations with WDM6, MORR, and SBMF schemes, showed ~18%, ~54%, ~41%, and ~29% of convective rainfall fraction (including isolated convective categories), ~14%, ~33%, ~18%, and ~20% of mixed rainfall fraction and ~68%, ~13%, ~42%, and ~50% of stratiform rainfall fraction respectively during the lifecycle of the CC. The accumulated rainfall derived from radar observations, using a blended rainfall estimation algorithm, indicated substantial differences in the observed and simulated rainfall pattern. The lower moment scheme has a tendency to produce more lighter as well as heavy rainfall compared to the higher moment schemes.

Leaching of Chlorides, Sulphates, and Phosphates from Ashes Formed as a Result of Burning Conventional Fuels, Alternative Fuels, and Municipal Waste in Household Furnaces

The aim of the study was to assess leaching of Cl−, SO42−, and PO43− from ashes formed in household furnaces. The ashes were obtained following the combustion of conventional fuels, namely wood and hard coal, and alternative fuels with various fractions of municipal waste in a household boiler. Aqueous leachates of the ashes were used to determine concentrations of chlorides by titration (Mohr’s method) (21.3–3049.6 mg/dm3), sulphates by the gravimetric method (12.2–244.1 mg/dm3), and phosphates by spectrophotometry (0.01–67.2 mg/dm3). It was found that co-combustion of municipal waste with plastic-coated paper cartons, diapers, or a mixed waste fraction leaves the greatest amount of ashes on the furnace grate. The highest amounts of Cl−, SO42−, and PO43− were leached from ashes generated from burning a mix of wood and coals, or wood alone (different species). The addition of municipal waste to the process of burning the conventional and alternative fuels studied did not significantly increase Cl−, SO42−, and PO43− content in aqueous extracts of ashes, the exception being diapers and plywood. In light of the study results, it was concluded that all the ashes could be reused (as an additive to concrete) except for the ash generated from the combustion of a mixed municipal waste fraction and coal (due to the content of Cl−) and diapers (due to the content of PO43−). It was demonstrated that Cl−, SO42−, and PO43− content in the entire set of samples and in individual ash groups is highly heterogeneous and variable.

Assessment of nanofluid on the performance and energy-environment interaction of Plate-Type-Heat exchanger

Upgrading the performance of the heat exchanger by ameliorating the thermal properties of the working fluid can be achieved by mixing nano-sized solid particles with the base fluid. The present study reports the impact of mixing metallic oxide nanoparticles with distilled water on the heat transfer, heat loss, and effectiveness of Plate-type Heat Exchanger (PHE). A comparison of two types of particles, namely: TiO2 and Al2O3 at various Volume Fractions (VoF) is experimentally evaluated. The effect of flow rate of the nanofluid and concentration of dispersed nanoparticles on the exchanger characteristic and performance is also addressed. A mathematical model is developed to process the experimental data of the pure fluid as well as the two nanofluids at various volume concentration and flowrates.The results show that the energy transfer between the two fluids is enhanced when nanofluid replaces the conventional fluid at a specified Reynolds number. The performance also ameliorates with augmentation in VoF of the nanoparticle. The outcome of the analysis also ascertains that Aluminum Oxide behaves better than Titanium Oxide in terms of improving PHE performance at relatively high Reynolds number. At Re ~ 15000, mixing 3% VoF of TiO2 with the base fluid increases the effectiveness of the exchanger by ~ 13% while the upgrade touches ~ 23% for same mixing fraction of Al2O3. The analysis of the current research shows that mixing 3% of Aluminum Oxide with distilled water could increase the heat leak factor up to 40% at Re = 12000 while at the same concentration of Titanium Oxide the heat leak factor approaches 45%. However, when the Reynolds number approaches 14000, the heat leak factor of Al2O3 is almost doubled whereas the magnitude of TiO2 is barely augmented to 50%.

Selective oligomerization of isobutylene in mixed C4 catalyzed by supported Fe(NO3)3/β catalyst

AbstractBACKGROUNDMethyl tert‐butyl ether (referred to as MTBE) is harmful to the environment and hence its use is limited in China. To avoid the waste of isobutylene as MTBE raw material and improve the utilization rate of isobutylene in mixed C4 fraction, supported Fe(NO3)3/β molecular sieve catalysts with different active components were prepared by the equal volume impregnation method. The catalysts were analyzed by X‐ray diffraction (XRD), Thermogravimetric analysis (TG), Temperature programmed desorption of NH3, Brunauer–Emmett–Teller analysis and scanning electron microscopy, and the catalytic performance of catalysts with mixed C4 fractions as raw materials and different active component loadings for selective oligomerization of isobutylene was investigated in a fixed bed reactor.RESULTSThe results show that the catalyst has the best catalytic performance when the active component loading was 6%, the reaction temperature was 60 °C, the reaction pressure was 1 MPa and the reaction space velocity was 1.5 h−1.CONCLUSIONThe conversion rate of isobutylene was >90%, the selectivity of C8 olefin was ≈80% and there was almost no loss of n‐butene. © 2021 Society of Chemical Industry (SCI).

Recycling Potential for Non-Valorized Plastic Fractions from Electrical and Electronic Waste

This paper describes a study for waste of electrical and electronic equipment (WEEE) to characterise the plastic composition of different mixed plastic fractions. Most of the samples studied are currently excluded from material recycling and arise as side streams in state-of-the-art plastics recycling plants. These samples contain brominated flame retardants (BFR) or other substances of concern listed as persistent organic pollutants or in the RoHS directive. Seventeen samples, including cathode ray tube (CRT) monitors, CRT televisions, flat screens such as liquid crystal displays, small domestic appliances, and information and communication technology, were investigated using density- and dissolution-based separation processes. The total bromine and chlorine contents of the samples were determined by X-ray fluorescence spectroscopy, indicating a substantial concentration of both elements in density fractions above 1.1 g/cm3, most significantly in specific solubility classes referring to ABS and PS. This was further supported by specific flame retardant analysis. It was shown that BFR levels of both polymers can be reduced to levels below 1000 ppm by dissolution and precipitation processes enabling material recycling in compliance with current legislation. As additional target polymers PC and PC-ABS were also recycled by dissolution but did not require an elimination of BFR. Finally, physicochemical investigations of recycled materials as gel permeation chromatography, melt flow rate, and differential scanning calorimetry suggest a high purity and indicate no degradation of the technical properties of the recycled polymers.

Brain Protein Synthesis and Cell Proliferation in Sulfur Amino Acid Restricted Mice

Protein homeostasis (proteostasis) is the maintenance of the proteome through cellular pathways that are involved in protein synthesis, folding, trafficking, and degradation. Loss of proteostasis is considered one of the hallmarks of aging, and is a driver for age-related neurodegenerative diseases. In order to conserve healthy brain function throughout the lifespan, proteostasis must be maintained. We previously reported that dietary sulfur amino acid restriction (SAAR), a life-/healthspan extending treatment, activates mechanisms that maintain proteostasis in the liver. However, it is unknown if SAAR activates mechanisms promoting proteostatic maintenance in the brain. To address this knowledge gap, wild-type male C57Bl/B6 mice were fed one of four diets: Regular fat control, regular fat SAAR, high fat control, and high fat SAAR. Mice consumed deuterium enriched water, which was used to measure long term rates of newly synthesized proteins and DNA. Brains were collected at days 1, 3, 7, 14, 21, and 35 of treatment. Mitochondrial, cytosolic, and mixed fractions of pulverized frontal cortex were analyzed for rates of protein synthesis and cell proliferation using GC/MS. Data collection is ongoing, however based on preliminary and previous studies analyzing liver and brain, we anticipate that under SAAR, protein synthesis rates will be maintained in select tissue fractions despite slower rates of cell proliferation compared to mice without SAAR.

Joint constraints on the field-cluster mixing fraction, common envelope efficiency, and globular cluster radii from a population of binary hole mergers via deep learning

The recent release of the second Gravitational-Wave Transient Catalog (GWTC-2) has increased significantly the number of known GW events, enabling unprecedented constraints on formation models of compact binaries. One pressing question is to understand the fraction of binaries originating from different formation channels, such as isolated field formation versus dynamical formation in dense stellar clusters. In this paper, we combine the $\texttt{COSMIC}$ binary population synthesis suite and the $\texttt{CMC}$ code for globular cluster evolution to create a mixture model for black hole binary formation under both formation scenarios. For the first time, these code bodies are combined self-consistently, with $\texttt{CMC}$ itself employing $\texttt{COSMIC}$ to track stellar evolution. We then use a deep-learning enhanced hierarchical Bayesian analysis to constrain the mixture fraction $f$ between formation models, while simultaneously constraining the common envelope efficiency $\alpha$ assumed in $\texttt{COSMIC}$ and the initial cluster virial radius $r_v$ assumed in $\texttt{CMC}$. Under specific assumptions about other uncertain aspects of isolated binary and globular cluster evolution, we report the median and $90\%$ confidence interval of three physical parameters $(f,\alpha,r_v)=(0.20^{+0.32}_{-0.18},2.26^{+2.65}_{-1.84},2.71^{+0.83}_{-1.17})$. This simultaneous constraint agrees with observed properties of globular clusters in the Milky Way and is an important first step in the pathway toward learning astrophysics of compact binary formation from GW observations.

Techno-economic assessment of mechanical recycling of challenging post-consumer plastic packaging waste

Increasing plastic recycling rates is crucial to tackle plastic pollution and reduce consumption of fossil resources. Recycling routes for post-consumer plastic fractions that are technologically and economically feasible remain a challenge. Profitable value chains for recycling mixed film and tray-like plastics have hardly been implemented today, in sharp contrast to recycling of relatively pure fractions such as polyethylene terephthalate and high-density polyethylene bottles.This study examines the economic feasibility of implementing mechanical recycling for plastic waste such as polypropylene, polystyrene, polyethylene films and mixed polyolefins. In most European countries these plastic fractions are usually incinerated or landfilled whilst in fact technologies exist to mechanically recycle them into regranulates or regrinds.Results show that the economic incentives for the recycling of plastic packaging depend predominantly on the product price and product yield. At current price levels, the most profitable plastic fraction to be recycled is PS rigids, with an internal rate of return of 14%, whereas the least profitable feed is a mixed polyolefin fraction with a negative internal rate of return in a scenario with steadily rising oil prices. Moreover, these values would be substantially reduced if oil prices, and therefore plastic product prices decrease. Considering a discount rate of 15% for a 15-year period, mechanical recycling is not profitable if no policy changes would be imposed by governments. Clearly low oil prices may jeopardize the mechanical recycling industry, inducing the need for policies that would increase the demand of recycled products such as imposing minimal recycled content targets.

Origins of major and minor ash constituents of solid recovered fuel for co-processing in the cement industry

Solid recovered fuel (SRF) ash consists of element oxides, which are valuable materials for cement manufacturers. When SRF is co-processed in the cement industry, its mineral content is incorporated into the clinker. Therefore, from a technical perspective, SRF ash is recycled. However, since recycling processes for materials that may be present in SRF exist, and since recycling goals are defined for different waste types, understanding the origin of these ash constituents and the contribution of different materials to the Recycling-index (R-index, i.e., the material-recyclable share of SRF) is important. In this work, the origins of Al, Ca, Fe, Si, Ti, Mg, Na, K, S, and P were first reviewed. Subsequently, ten SRF samples were sorted, and the ash content and composition of the sorting fractions (e.g., <10 mm, plastics, paper&cardboard) determined. Additionally, selected samples of polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), polyvinyl chloride (PVC), liquid packaging board (LPB), wood, and paper&cardboard (P&C) extracted from SRF were investigated. The results demonstrated that the materials that contributed most of the valuable oxides and ash content, and thereby to the R-index of SRF, are mixed or composite fractions, for example, the fine fraction, composites, and the sorting residues. Except for the composite LPB, no other material recovery options exist for most of these fractions. For this reason, the recycling of mixed and soiled materials or residues in the cement industry may be considered a complementary option to existing recycling processes.

Optimization method for the component of aviation kerosene surrogate fuels based on chemical reactor network model

On the basis of the simulation results of premixed jet flame using liquid hydrocarbon fuel, an optimization method for the component of aviation kerosene surrogate fuels based on chemical reactor network (CRN) model is proposed. Firstly, computational fluid dynamics (CFD) numerical simulation is carried out for three hydrocarbon fuel jet flames of n-dodecane (C12H26), n-decane (C10H22), n-heptane (C7H16) to obtain the characteristics of the temperature field under different working conditions. Based on this, the CRN partition topological geometry of jet flame is generated. The genetic algorithm is used to optimize the parameters of each reactor, and the algebraic relationship between the CRN parameter and the inlet parameters (dimensionless inlet temperature, Reynolds number and mixing fraction) is obtained. Then, topological geometry of the CRN which is suitable for different working conditions is established, and the best CRN model of hydrocarbon fuel jet flame is constructed. Combined with the experimental data, the optimal proportion of three-component surrogate fuels is determined by the above method. As a result, the optimal ratio is 56.41% C12H26, 26.36% C10H22 and 17.23% C7H16. Finally, the CFD numerical simulation was performed and the results agreed well with the experimental data, indicating the effectiveness of optimization method for the CRN-based aviation kerosene surrogate fuels. This method can be applied to the component optimization of aviation kerosene surrogate fuels.

Study of Jatropha curcas Linn and Olea europaea as Bio-Oil Lubricant to Physical Properties and Wear Rate

This paper presents a study on the effect of the mixed volume fraction of Jatropha curcas Oil (JCO) and Olea europea or extra virgin olive oil (EVOO) on the physical properties of the oil, especially viscosity, density and water content. This study also presents the mechanical properties examination result, especially its effect on the wear rate of the pin on disc tribometer results on ST 41 steel specimens, using optical microscopy. The independent variables used were variations of the oil mixture: 0, 20, 40, 60, 80 and 100% EVOO. With the increase in the percentage of the EVOO mixture in JCO, the density decreases. The result of water content in a higher percentage of JCO, the higher the water content value of 0.1217%. Pure JCO has the higher viscosity value of 1.9084 m2/s. The higher the percentage of JCO, the lower the wear rate value obtained. In the tribometer test, the pin on disk mixture of pure JCO has the lower wear value of 5.09 m2/s.

Numerical investigation of the impacting and freezing process of a single supercooled water droplet

In order to study the mechanism of ice formation after water droplets produced by splashing waves attach to ship superstructure in cold ocean regions, a numerical framework that considers the effect of supercooling degree on the meso-scale water droplet freezing is developed to explore the freezing mechanism of water droplets after impacting. This model can track the solid–liquid and air–liquid interface together using a coupled volume-of-fluid and level set multiphase method and Enthalpy-Porosity phase change method. The model introduces a mixed fraction to describe the problem of three-phase unification. The simulation results of the center freezing height and droplet spreading factor in this paper are consistent with the experimental results in related literature, which verifies the accuracy of the framework. The study includes a detailed description of the dynamic and thermodynamics mechanism of the water droplet. The influence factors of droplet impacting and freezing process are analyzed. The analysis results show that the surface wettability, supercooling degree, and impact velocity have a great influence on the freezing behavior of droplets. This model can deepen the understanding of icing mechanism on ship superstructure surface, provide an indication for engineers to develop an accurate prediction method of ice accretion on ship superstructure surface.