Separate Curves Research Articles

RepDilPCR: a tool for automated analysis of qPCR assays by the dilution-replicate method

BackgroundThe dilution-replicate experimental design for qPCR assays is especially efficient. It is based on multiple linear regression of multiple 3-point standard curves that are derived from the experimental samples themselves and thus obviates the need for a separate standard curve produced by serial dilution of a standard. The method minimizes the total number of reactions and guarantees that Cq values are within the linear dynamic range of the dilution-replicate standard curves. However, the lack of specialized software has so far precluded the widespread use of the dilution-replicate approach.ResultsHere we present repDilPCR, the first tool that utilizes the dilution-replicate method and extends it by adding the possibility to use multiple reference genes. repDilPCR offers extensive statistical and graphical functions that can also be used with preprocessed data (relative expression values) obtained by usual assay designs and evaluation methods. repDilPCR has been designed with the philosophy to automate and speed up data analysis (typically less than a minute from Cq values to publication-ready plots), and features automatic selection and performance of appropriate statistical tests, at least in the case of one-factor experimental designs. Nevertheless, the program also allows users to export intermediate data and perform more sophisticated analyses with external statistical software, e.g. if two-way ANOVA is necessary.ConclusionsrepDilPCR is a user-friendly tool that can contribute to more efficient planning of qPCR experiments and their robust analysis. A public web server is freely accessible at https://repdilpcr.eu without registration. The program can also be used as an R script or as a locally installed Shiny app, which can be downloaded from https://github.com/deyanyosifov/repDilPCR where also the source code is available.

A-021 Evaluation of a Novel N Terminal Pro B Type Natriuretic Peptide Assay as an aid in the Diagnosis of Acute Heart Failure in the Emergency Department

Abstract Background The signs and symptoms of acute heart failure (AHF) may overlap with other conditions and lead to diagnostic difficulty in the undifferentiated patient with dyspnea. The particularly high negative predictive value (NPV) of natriuretic peptides (NPs) in excluding AHF have rendered these assays especially useful in evaluating dyspnea in acute care setting. This study was conducted to assess the diagnostic performance of a novel N-terminal pro-B type natriuretic peptide (NT-proBNP) assay in the intended use patient population in the emergency department (ED). Methods A multicenter study was conducted in the U.S. on individuals presenting to the ED with dyspnea and a suspicion of AHF. Blood specimens were collected and tested using the Beckman Coulter Access NT-proBNP assay on the DxI 9000 Immunoassay Analyzer. Test results were compared to an adjudicated diagnosis clinical endpoint performed by an independent Clinical Events Committee blinded to the Access NT-proBNP result. Performance included NPV and sensitivity of an age-independent cut point of <300 ng/L to exclude AHF, and the positive predictive value (PPV) of the age-dependent cut points of >450, >900, and >1800 ng/L for ages <50 years, 50-75 years, and >75 years, respectively, for the diagnosis of AHF. The sample size required to achieve a 95% two tailed confidence interval (CI) was 150 subjects per age group to provide clinical performance at 90% (±10%) sensitivity. Sample size was based upon CLSI EP24-A2, Assessment of the Diagnostic Accuracy of Laboratory Tests Using Receiver Operating Characteristic Curves. Sensitivity and specificity were calculated at a series of cutoff points and plotted in separate receiver operation curves (ROC) for an overall age-independent rule-out analysis and for individual age-dependent groups separately. Area under the receiver operator characteristic curve (AUROC) was reported with 95% 2-sided CI. NPV and PPV with respective 95% 2-sided score CI was computed for the overall age-independent cut point and for each age group cohort. Results Of 490 enrolled patients, 41% were adjudicated with AHF with a median (Q1, Q3) age of 60 (47-76) years, and distributions of 46.1% female, 60.8% White and 38.2% Black. The assay had an AUROC for AHF of 0.88 (P<0.001), comparable to other commercially available NT-proBNP assays. The rule-out cut point of <300 ng/L had 96% sensitivity and NPV of 95%. Age-dependent cut points had sensitivity of 84%, 90%, and 87%, specificity of 81%, 70% and 61%, and PPV of 72%, 62%, and 74%, respectively. Conclusions The Access NT-proBNP assay demonstrated high clinical performance in the diagnosis and exclusion of acute HF in the undifferentiated dyspneic patient population and performed similarly well to validated assays used in current clinical practice. Given the continued increase in importance and reach of natriuretic peptide testing, these results are useful to extend availability of this assay to a larger audience.

The impact of socioeconomic status on overall survival in patients at a radiation oncology center: A retrospective study.

147 Background: There are few reports examining the impact of socioeconomic status (SES), as indicated by the Area Deprivation Index (ADI), on overall survival (OS) in radiation oncology patients, making this an important area of investigation. This study aims to investigate the influence of ADI on OS in radiation oncology patients, while controlling for stage and other relevant variables. Methods: This retrospective study analyzed data from radiation oncology patients treated at a large multi-site single-institution center from October 2006 to January 2024. Demographic and treatment information, including age, gender, race, insurance status, comorbidity index (CCI), mental health disorders (MHD), treatment intent, cancer type, and stage, were collected. The ADI was used to measure SES and was gathered from the Neighborhood Atlas. Kaplan-Meier curves were generated for all patients, with separate curves for different cancer types. The impact of demographic, clinical, and socioeconomic factors on OS was assessed using a Cox proportional hazards multivariable (MVA) logistic regression analysis. The model was stratified by treatment intent, cancer type, stage, insurance status, and CCI. Results: In this comprehensive analysis of 7343 patients, the median follow-up was 12.00 months (IQR: 1.8–36.82). Most patients were breast cancer (30.2%), over 65 years old (60.5%), and had an ADI below the mean (55.5%), indicating lower socioeconomic disadvantage. Kaplan-Meier analysis showed that 5-year OS rates were significantly lower for the fourth quartile ADI group (85.1%) compared to the first quartile ADI group (94.0%) (p<0.001). Among different cancer types, significant differences in OS were observed for breast cancer (p=0.002) and miscellaneous (uncategorized) cancers (p=0.005), with lung cancer showing a trend towards significance (p=0.053). The MVA revealed that patients in both the third quartile (hazard ratio (HR)=1.343, 95% CI: 1.029–1.752, p=0.030) and fourth quartile (HR=1.403, 95% CI: 1.075–1.829, p=0.013) of ADI had significantly higher likelihood of mortality compared to those in the first ADI quartile. Conclusions: SES, as measured by ADI, significantly impacts OS in radiation oncology patients. Poorer patients, indicated by higher ADI, exhibited worse survival outcomes despite controlling for cancer type, stage, treatment intent, CCI, MHD, and insurance status. These findings underscore the need for targeted interventions to address socioeconomic disparities in cancer care to improve survival outcomes for disadvantaged populations.

Combined light curve and radial velocity analysis of the neglected contact binary S Ant

We present the first combined photometric and spectroscopic solution of the bright southern contact binary S Ant based on the Transiting Exoplanet Survey Satellite (TESS) light curve and the radial velocities from the David Dunlap Observatory survey. S Ant is a W UMa type binary in deep contact, with a mass ratio of 0.34 and a relatively massive and hot F-type primary. Beside the standard modeling of the phase-binned light curve, we also perform “seasonal modeling” where we treat each of the 83 orbital cycles present in the TESS data as a separate light curve. The resulting ensemble of solutions shows evidence of quasi-periodic migration of a long-lived, dark, polar spot. The migration is confirmed independently by eclipse time variations which display remarkably strong correlation with the spot location.

A new modified direct method for determining the mode I delamination traction-separation law

A new equation was developed for the crack-tip separation in the double cantilever beam (DCB) specimen, which has been standardised for mode I delamination of composites. The very simple closed-form equation is based on a pseudo-elastic beam model and on the effective crack concept. Moreover, it only requires the common load–displacement data up to crack initiation and easy to obtain elastic moduli. Strain-energy release rate versus crack-tip separation curves can then be differentiated for obtaining the tractions, as in the classical direct method. Numerical results for piecewise linear traction-separation laws (TSL) showed good accuracy of strain-energy release rate versus crack-tip separation curves predicted. Application to two carbon/epoxy materials gave very promising TSL results, including cohesive strengths similar to transverse tensile strengths and post-peak steep traction decreases.

Evaluation of Corrosion and Its Impact on the Mechanical Performance of Al-Steel Joints.

Aluminum-steel joints are increasingly used in the automotive industry to meet the requirements for energy saving and emission reduction. Among various joining technologies, self-pierce riveting (SPR) and resistance spot welding (RSW) are two well-established technologies for fabricating dissimilar joints with stable and high mechanical performance. However, corrosion will occur in these joints inevitably due to different electrochemical properties, which can degrade the surface quality and the mechanical performance, such as strength. This paper presents a method of understanding the corrosion mechanisms in joining aluminum and steel. For this understanding, a hybrid method combining experimental observations, mechanical properties identification, and analytical approaches was used to assess the evolution of the impact of corrosion on the joining performance, such as traction separation curves. The study was conducted on common combinations used in the vehicles, e.g., a 1.2 mm thickness aluminum alloy (AA 6022) and 2.0 mm thickness hot deep galvanized steel (HDG HSLA 340) joined by SPR and RSW. After the fabrication of these joints, accelerated cyclic corrosion tests of up to 104 cycles were performed, which reproduced the environmental conditions to which a vehicle was exposed. By investigating the microstructural evolution within the joints, the corrosion mechanisms of SPR and RSW joints were revealed, including the initiation and propagation. Moreover, the intrinsic impact of the corrosion on the mechanical performance, including the strength, axial stiffness, and crashworthiness, was analyzed by performing a lap-shear test. It showed that as corrosion proceeds, the fracture modes and mechanical performance are affected significantly.

A Comparison Theorem for Semi-Abelian Schemes over a Smooth Curve

We compare flat cohomology to crystalline syntomic complexes with coefficients in two cases: (1) p p -divisible groups over a separated F p \mathbb {F}_p -scheme with local finite p p -bases, (2) semi-abelian schemes over a separated irreducible smooth curve.

Introducing emissivity directionality to the temperature-emissivity separation algorithm

Natural surfaces are mostly anisotropic emitters, contributing to the anisotropic behavior of Land Surface Temperature (LST). This characteristic of thermal infrared emissivity is well known and several studies have tried to simulate this behavior either with physical or empirical models. However, given the high heterogeneity of land surfaces, the translation of the angular dependence of emissivity as provided from measurements or models into satellite pixel scale anisotropy is generally very difficult. Here we propose a reformulation of the Mean Minimum-Maximum Difference (MMD) curve of the Temperature-Emissivity Separation (TES) algorithm to allow a correct adjustment of the TES retrievals by taking into account the emissivity angular distribution. For that purpose, the Multi-Sensor method is used to obtain directional emissivities at different sites in the Saharan and Namib desert. The data is then used to calibrate the view-angle dependence of the new MMD formulation. The TES retrievals obtained with the new formulation show a good agreement with the Multi-Sensor data. Results also suggest that the new coefficients of the MMD can be applied to other sensors with similar spectral channels. The new angle-dependent emissivities may lead to a reduction of LST bias as high as 2 K for view angles above 50o. The proposed formulation is currently only valid over barren surfaces.

Individual chaotic behaviour of the S-stars in the Galactic centre

Located at the core of the Galactic centre, the S-star cluster serves as a remarkable illustration of chaos in dynamical systems. The long-term chaotic behaviour of this system can be studied with gravitational N-body simulations. By applying a small perturbation to the initial position of star S5, we can compare the evolution of this system to its unperturbed evolution. This results in two solutions that diverge exponentially, defined by the separation in position space δr, with an average Lyapunov timescale of ∼420 yr, corresponding to the largest positive Lyapunov exponent. Even though the general trend of the chaotic evolution is governed in part by the supermassive black hole Sagittarius A∗ (Sgr A∗), individual differences between the stars can be noted in the behaviour of their phase-space curves. We present an analysis of the individual behaviour of the stars in this Newtonian chaotic dynamical system. The individuality of their behaviour is evident from offsets in the position space separation curves of the S-stars and the black hole. We propose that the offsets originate from the initial orbital elements of the S-stars, where Sgr A∗ is considered in one of the focal points of the Keplerian orbits. Methods were considered to find a relation between these elements and the separation in position space. Symbolic regression provides the clearest diagnostics for finding an interpretable expression for the problem. Our symbolic regression model indicates that ⟨δr⟩ ∝ e2.3, implying that the time-averaged individual separation in position space increases rapidly with the initial eccentricity of the S-stars.

Adhesive forces between hydroxylated graphene and a single anisole: Atomic force spectroscopy experiment and molecular dynamics simulation

Measuring and understanding interaction forces between hydroxylated graphene (G-OH) and aromatic compounds is significant for the applications of composites based on G-OH, such as 3D graphene derivatives preparation and wastewater treatment. In this research, the adsorption/separation mechanical behavior of anisole on graphene and G-OH surfaces was investigated by atomic force microscopy (AFM) experiments and molecular dynamics (MD) simulations. The adsorption and separation curves of anisole on graphene and G-OH surfaces were obtained by experiments, and the adhesive forces of a single anisole were achieved by the Poisson statistics method. It is found that there are two types of adhesive forces between anisole and G-OH. For graphene and anisole, two extreme values are got by the adsorption and separation processes, and the adhesive force obtained by the separation process is approximately equal to one type of adhesive force between anisole and G-OH. Furthermore, MD simulation results reveal that the maximum adhesive force of anisole on the G-OH surface depends on its position relative to the hydroxyl group, and anisole has a greater affinity near the hydroxyl group. The position and planar angle of the anisole conformations cause the difference in adhesive forces.

Insights from a Comprehensive Capacity Expansion Planning Modeling on the Operation and Value of Hydropower Plants under High Renewable Penetrations

This paper presents a quantitative assessment of the value of hydroelectric power plants (HPPs) in power systems with a significant penetration of variable renewable energy sources (VRESs). Through a capacity expansion planning (CEP) model that incorporates a detailed representation of HPP operating principles, the study investigates the construction and application of HPP rule curves essential for seasonal operation. A comparative analysis is also conducted between the proposed rule curve formulation and alternative modeling techniques from the literature. The CEP model optimizes installed capacities per technology to achieve predefined VRES penetration targets, considering hourly granularity and separate rule curves for each HPP. A case study involving twelve reservoir hydropower stations and two open-loop pumped hydro stations is examined, accounting for standalone plants and cascaded hydro systems across six river basins. The study evaluates the additional generation and storage required to replace the hydropower fleet under high VRES penetration levels, assessing the resulting increases in total system cost emanating from introducing such new investments. Furthermore, the study approximates the storage capabilities of HPPs and investigates the impact of simplified HPP modeling on system operation and investment decisions. Overall, the findings underscore the importance of reevaluating hydro rule curves for future high VRES penetration conditions and highlight the significance of HPPs in the energy transition towards carbon neutrality.

Triple points and phase transitions of D-dimensional dyonic AdS black holes with quasitopological electromagnetism in Einstein–Gauss–Bonnet gravity

By considering the negative cosmological constant Λ as a thermodynamic pressure, we study the thermodynamics and phase transitions of the D-dimensional dyonic AdS black holes (BHs) with quasitopological electromagnetism in Einstein–Gauss–Bonnet (EGB) gravity. The results indicate that the small/large BH phase transition that is similar to the van der Waals (vdW) liquid/gas phase transition always exists for any spacetime dimensions. Interestingly, we then find that this BH system exhibits a more complex phase structure in 6-dimensional case that is missed in other dimensions. Specifically, it shows for D = 6 that we observed the small/intermediate/large BH phase transitions in a specific parameter region with the triple point naturally appeared. Moreover, when the magnetic charge turned off, we still observed the small/intermediate/large BH phase transitions and triple point only in 6-dimensional spacetime, which is consistent with the previous results. However, for the dyonic AdS BHs with quasitopological electromagnetism in Einstein–Born–Infeld (EBI) gravity, the novel phase structure composed of two separate coexistence curves observed by Li et al. [Phys. Rev. D 105 104048 (2022)] disappeared in EGB gravity. This implies that this novel phase structure is closely related to gravity theories, and seems to have nothing to do with the effect of quasitopological electromagnetism. In addition, it is also true that the critical exponents calculated near the critical points possess identical values as mean field theory. Finally, we conclude that these findings shall provide some deep insights into the intriguing thermodynamic properties of the dyonic AdS BHs with quasitopological electromagnetism in EGB gravity.

Synthesis of Raspberry-like Nanoparticles via Surface Grafting of Positively Charged Polyelectrolyte Brushes: Colloidal Stability and Surface Properties.

A method to synthesize stable, raspberry-like nanoparticles (NPs), using surface grafting of poly(glycidyl methacrylate) (PGMA) brushes on a polystyrene (PS) core with varying grafting densities, is reported. A two-step functionalization reaction of PGMA epoxide groups comprising an amination step first using ethylene diamine and then followed by a quaternization using glycidyltrimethylammonium chloride generates permanently and positively charged polyelectrolyte brushes, which result in both steric and electrostatic stabilization. The dispersion stability of the brush-bearing NPs is dramatically improved compared to that of the pristine PS core in salt solutions at ambient (25 °C) and elevated temperatures (60 °C). Additionally, the grafted polyelectrolyte chains undergo a reversible swelling in the presence of different ionic strength (IS) salts, which modulate the surface properties, including roughness, stiffness, and adhesion. An atomic force microscope under both dry and wet conditions was used to image conformational changes of the polyelectrolyte chains during the swelling and deswelling transitions as well as to probe the nanomechanical properties by analyzing the corresponding force-sample separation curves. The quaternized polyelectrolyte brushes undergo a conformational transition from a collapsed state to a swelled state in the osmotic brush (OB) regime triggered by the osmotic gradient of mobile ions to the interior of the polymer chain. At IS ∼ 1 M, the brushes contract and the globules reform (salted brush state) as evidenced by an increase in the surface roughness and a reduction in the adhesion of the brushes. Beyond IS ∼ 1 M, quartz crystal microbalance with dissipation monitoring measurements show that salt uptake continues to take place predominantly on the exterior surface of the brush since salt adsorption is not accompanied by a size increase as measured by dynamic light scattering. The study adds new insights into our understanding of the behavior of NPs bearing salt-responsive polyelectrolyte brushes with adaptive swelling thresholds that can ultimately modulate surface properties.

Methodology to generate earthquake-tsunami fragility surfaces for community resilience modeling

Community resilience analysis and performance-based tsunami design methods typically use separate fragility curves for earthquake and near-field tsunami hazards to predict damage, neglecting the direct cascading effects of the earthquake damage on the subsequent tsunami damage analysis for coastal communities. This paper presents an improved two-phase successive analysis that can incorporate the most significant sources of uncertainties in structural modeling and hazards. However, generating multi-hazard 3D fragility surfaces that fully incorporate uncertainties through Monte Carlo Simulation requires millions of successive nonlinear analyses, which can be computationally intensive. To address this issue, a multi-distributed and parallel processing architecture was used and summarized herein. This methodology has been applied to a 4-story RC building as an illustrative example and demonstrated to be highly efficient and scalable in generating near-continuous fragility surfaces for earthquake and tsunami hazards, reducing the expected computational time by over 98%. Due to their near-continuous characteristic, these surfaces are easier to implement in resilience frameworks and applications. The fragility surfaces also feature earthquake-only and tsunami-only 2D fragility curves along the intensity measure axis boundaries, making them versatile for use in resilience frameworks that focus on a single hazard or both earthquake and tsunami hazards. Therefore, the proposed method is scalable making it helpful in developing fragility models for building portfolios to be used at the community resilience modeling of full coastal cities.

Thermodynamics and Phase Transitions of Dyonic AdS Black Holes in Gauss-Bonnet-Scalar Gravity

In this paper, by treating the cosmological constant as a thermodynamic pressure, we study the thermodynamics and phase transitions of the dyonic AdS black holes in Gauss-Bonnet-Scalar gravity, where the conformal scalar field is considered. In a more general extended phase space, we first verified the first law of black hole thermodynamics, and find that it is always true. Meanwhile, the corresponding Smarr relation is also obtained. Then, we found that this black hole exhibits interesting critical behaviors in six dimensions, i.e., two swallowtails can be observed simultaneously. Interestingly, in a specific parameter space, we observed the small/intermediate/large black hole phase transitions, with the triple point naturally appearing. Additionally, the small/large black hole phase transition, similar to the liquid/gas phase transition of the van der Waals fluids, can also be found in other parameter regions. Moreover, we note that the novel phase structure composed of two separate coexistence curves discovered in the dyonic AdS black holes in Einstein-Born-Infeld gravity disappears in Gauss-Bonnet-Scalar gravity. This suggests that this novel phase structure may be related to gravity theory, and importantly, it is generally observed that the triple point is a universal property of dyonic AdS black holes. On the other hand, we calculated the critical exponents near the critical points and found that they share the same values as in mean field theory. Finally, it is true that these results will provide some deep insights into the interesting thermodynamic properties of the dyonic AdS black holes in the background of conformal scalar fields.

Persons chronically exposed to low doses of ionizing radiation: A cytogenetic dosimetry study

The dosimetry and control of exposure for individuals chronically exposed to ionizing radiation are important and complex issues. Assessment may be optimized by evaluating individual adaptation and radiosensitivity, but it is not possible for a single model to account for all relevant parameters. Our goal was to develop approaches for the calculation of doses for persons chronically exposed to ionizing radiation, taking their radiosensitivities into consideration. On the basis of ex vivo radiation of blood samples, dose-effect models were constructed for dose ranges 0.01–2.0 and 0.01–0.4 Gy, using different cytogenetic criteria. The frequencies of "dicentric chromosomes and rings" at low doses are too low to have predictive value. The different responses of subjects to radiation made it possible to categorize them according to their radiosensitivities and to generate separate dose-effect curves for radiosensitive, average, and radioresistant individuals, reducing the amount of error in retrospective dosimetry.

A Comparison of the Effectiveness Between Trabeculectomy and Minimally Invasive Glaucoma Surgeries

Background and Hypothesis: Glaucoma affects 3 million Americans and is the second most common cause of blindness globally, after cataracts. It involves the degeneration of the optic nerve, often associated with increased eye pressure, leading to vision loss. Trabeculectomy was traditionally the standard surgical approach for managing glaucoma progression once medication and laser had failed. Recently, minimally invasive glaucoma surgeries (MIGS) have gained FDA approval for mild and moderate cases and are being implemented in practice. We hypothesize that MIGS procedures are just as effective as trabeculectomy in mild, moderate, and severe cases of glaucoma.
 Experimental Design or Project Methods: Using data from IU Health, patients that underwent either a MIGS procedure or a trabeculectomy for open-angle glaucoma at least a year ago were identified. Visual field data was used to stage their glaucoma. Any future glaucoma surgery was noted. Using this information, three separate Kaplan-Meier curves at 95% confidence intervals were created corresponding to each stage of glaucoma with a second surgery defined as a failure and a survival analysis was done to visualize the difference between these surgical approaches.
 Results: The sample included 119 patients and 179 eyes with a mean age of 80 and 57% females. The study had 80% power at a two-sided 5% significance level. Based on the survival analysis, there were no significant differences between trabeculectomy and MIGS in mild and moderate glaucoma (p=0.69 and 0.97 respectively). In severe glaucoma, MIGS had a lower failure rate compared to trabeculectomy (p=0.026).
 Conclusion and Potential Impact: The research comparing trabeculectomy to MIGS is still relatively new and this study shows the safety and efficacy of MIGS procedures. If confirmed, this study could potentially change the standard of care to MIGS for all stages of open-angle glaucoma.

Molecular dynamics simulation-based study to analyse the properties of entrapped water between gold and graphene 2D interfaces.

Heterostructures based on graphene and other 2D materials have received significant attention in recent years. However, it is challenging to fabricate them with an ultra-clean interface due to unwanted foreign molecules, which usually get introduced during their transfer to a desired substrate. Clean nanofabrication is critical for the utilization of these materials in 2D nanoelectronics devices and circuits, and therefore, it is important to understand the influence of the "non-ideal" interface. Inspired by the wet-transfer process of the CVD-grown graphene, herein, we present an atomistic simulation of the graphene-Au interface, where water molecules often get trapped during the transfer process. By using molecular dynamics (MD) simulations, we investigated the structural variations of the trapped water and the traction-separation curve derived from the graphene-Au interface at 300 K. We observed the formation of an ice-like structure with square-ice patterns when the thickness of the water film was <5 Å. This could cause undesirable strain in the graphene layer and hence affect the performance of devices developed from it. We also observed that at higher thicknesses the water film is predominantly present in the liquid state. The traction separation curve showed that the adhesion of graphene is better in the presence of an ice-like structure. This study explains the behaviour of water confined at the nanoscale region and advances our understanding of the graphene-Au interface in 2D nanoelectronics devices and circuits.

Моделирование аэродинамики закрученного турбулентного потока в воздушно-центробежном классификаторе

Centrifugal air classifiers are the promising devices for fractional separation of powders by size. Large particles of a powder material are thrown to the periphery due to the predominance of centrifugal forces over aerodynamic forces. This paper studies the aerodynamics of a swirling turbulent flow for different working area designs of the classifier. Turbulence is simulated using the RANS method and the Wilcox turbulence model. To determine the efficiency of the classification of the powder material and to obtain a separation curve using the Tromp method, two calculation methods, i.e., trajectory and probabilistic methods, are proposed. The obtained results are validated with experimental data and through various test studies. Analysis of the numerical study of fine powder classification has shown the viability of the proposed geometry for a separation chamber in comparison with the traditional geometry. The most optimal mode of aerodynamic characteristics of the centrifugal classifier is revealed to obtain the best sharpness of particle size separation.

Asymmetric separation of variables for the extended Clebsch and Manakov models

In the present paper we develop a method of the vector fields Zi[8] of the bi-hamiltonian theory of separation of variables. Using a modification of this method we construct non-Stäckel asymmetric variable separation for three-dimensional extension of the Clebsch model, which is bi-hamiltonially equivalent to the system of interacting Manakov (Shottky-Frahm) and Euler tops. Our SoV is unusual: it is characterized by two curves of separation of different genus. We explicitly construct coordinates and momenta of separation, the corresponding reconstruction formulae and the Abel-type quadratures for the considered three-dimensional extension of the Clebsch and Manakov tops.