Today, more and more the wide application is getting the micro-/radio- wave defense materials. Many of them are produced by the methods of deep syntesis electromagnetic elements containing substances ...what going to its expensivity. This article include information about electromagnetic/non-electromagnetic disperse components composition method practice. It makes possible to get available dry mixes for surface plastering with effective micro-/radio- wave defense in range of 2... 8 GHz.
•Multiple exposures and their combined effects require better risk management.•Precautionary approaches and intermediate measures could already be applied.•A European strategy is needed to address ...the research and policy needs.
The number of anthropogenic chemicals, manufactured, by-products, metabolites and abiotically formed transformation products, counts to hundreds of thousands, at present. Thus, humans and wildlife are exposed to complex mixtures, never one chemical at a time and rarely with only one dominating effect. Hence there is an urgent need to develop strategies on how exposure to multiple hazardous chemicals and the combination of their effects can be assessed. A workshop, “Advancing the Assessment of Chemical Mixtures and their Risks for Human Health and the Environment” was organized in May 2018 together with Joint Research Center in Ispra, EU-funded research projects and Commission Services and relevant EU agencies. This forum for researchers and policy-makers was created to discuss and identify gaps in risk assessment and governance of chemical mixtures as well as to discuss state of the art science and future research needs. Based on the presentations and discussions at this workshop we want to bring forward the following Key Messages:•We are at a turning point: multiple exposures and their combined effects require better management to protect public health and the environment from hazardous chemical mixtures.•Regulatory initiatives should be launched to investigate the opportunities for all relevant regulatory frameworks to include prospective mixture risk assessment and consider combined exposures to (real-life) chemical mixtures to humans and wildlife, across sectors.•Precautionary approaches and intermediate measures (e.g. Mixture Assessment Factor) can already be applied, although, definitive mixture risk assessments cannot be routinely conducted due to significant knowledge and data gaps.•A European strategy needs to be set, through stakeholder engagement, for the governance of combined exposure to multiple chemicals and mixtures. The strategy would include research aimed at scientific advancement in mechanistic understanding and modelling techniques, as well as research to address regulatory and policy needs. Without such a clear strategy, specific objectives and common priorities, research, and policies to address mixtures will likely remain scattered and insufficient.
Finite Mixture Models McLachlan, Geoffrey J; Lee, Sharon X; Rathnayake, Suren I
Annual review of statistics and its application,
03/2019, Letnik:
6, Številka:
1
Journal Article
Recenzirano
The important role of finite mixture models in the statistical analysis of data is underscored by the ever-increasing rate at which articles on mixture applications appear in the statistical and ...general scientific literature. The aim of this article is to provide an up-to-date account of the theory and methodological developments underlying the applications of finite mixture models. Because of their flexibility, mixture models are being increasingly exploited as a convenient, semiparametric way in which to model unknown distributional shapes. This is in addition to their obvious applications where there is group-structure in the data or where the aim is to explore the data for such structure, as in a cluster analysis. It has now been three decades since the publication of the monograph by
McLachlan & Basford (1988)
with an emphasis on the potential usefulness of mixture models for inference and clustering. Since then, mixture models have attracted the interest of many researchers and have found many new and interesting fields of application. Thus, the literature on mixture models has expanded enormously, and as a consequence, the bibliography here can only provide selected coverage.
The SAFT-VR DFT formalism, which has recently been extended to mixtures F. Llovell et al., J. Chem. Phys. 133 (2010) 024704, is applied to the interfacial properties of a wide variety of binary ...mixtures that are of relevance to enhanced oil recovery and carbon dioxide sequestration. The approach is based on the statistical associating fluid theory for attractive potentials of variable range (SAFT-VR) and includes a formal density functional theory (DFT) treatment, where the different terms of the equation of state are separated in order to describe the short and long-range interactions of the inhomogeneous fluid. The structural correlations between the particles are taken into account following the ideas of Toxvaerd S. Toxvaerd, J. Chem. Phys. 64 (1976) 2863 with the application of appropriate van der Waals mixing rules. Binary mixtures of short and long chain n-alkanes, n-alkanes+carbon dioxide, water+carbon dioxide and water+n-alkanes are investigated over wide ranges of temperature and pressure. The molecular parameters for each pure compound are obtained by comparison with vapour–liquid equilibrium data. A binary parameter is used to account for the unlike dispersive energy interactions and provide a representation of the bulk fluid phase equilibrium properties of the mixtures. No additional intermolecular parameters are required in the implementation of the DFT for the interfacial properties of the systems. The predictions for the vapour–liquid and liquid–liquid interfacial tensions are generally found to be in good quantitative agreement with experimental data. Selected density profiles exhibiting noteworthy adsorption features (such as preferential surface adsorption or depletion) are highlighted. The degree of hydrogen bonding along the interface is also reported for the aqueous mixtures studied.
•Helmholtz-energy based, multiparameter mixture model.•Mixtures of carbon dioxide, water, nitrogen, oxygen, argon, and carbon monoxide.•Improved calculation of complex phase-equilibria (VLE, LLE, ...VLLE).•Thermodynamic properties for Carbon Capture and Storage (CCS) processes.•Also applicable to humid air, humid gases, and combustion gases.
An equation of state for thermodynamic properties of humid gases, combustion gases, and CO2-rich mixtures typical for Carbon Capture and Storage (CCS) processes, the EOS–CG mixture model, is presented in this work. This model uses the mathematical approach of the GERG-2008 equation of state by Kunz and Wagner (2012), and presents new mixing parameters for mixtures of carbon dioxide, water, nitrogen, oxygen, argon, and carbon monoxide. The EOS–CG model covers a wide temperature and pressure range in the vapour, liquid, and supercritical regions, and is valid over the full composition range. It improves the calculation of complex phase boundaries of binary and multi-component mixtures, where water and/or carbon dioxide is involved, as compared to established models such as the Lee–Kesler–Plöcker equation, the Soave–Redlich–Kwong model, and the GERG-2008.
A new impact-absorbing material is being developed to protect vulnerable road users in urban areas and has been produced and tested, mechanically and environmentally in the laboratory. The main ...constituent of this innovative material is the rubber recycled from end-of-life tyres to foster a circular use of resources and exploit rubber’s elastic properties. The study aims to provide a complete Uniaxial Compression Test (UCT) and leaching analysis of the material to propose and optimise a mix that is mechanically sound, durable, and respectful of the environment, in view of in-situ applications. Therefore, the UCT and Dynamic Surface Leaching Test (DSLT) were carried out on rubberised asphalt specimens with different mix designs. The 64 days cumulative concentrations of leached heavy metals and trace elements from unit surface of specimens were calculated and quantified, according to the CEN/TS 16637 standard. In parallel, thanks to a specific mechanical characterisation, compressive stress–strain curves were obtained, and the relaxation and elastic modulus were evaluated. The results from the compression tests showed that the A-mixes have the best elastic and absorbing behaviour, especially those made with an SBS-modified bituminous emulsion (A4). The results from DSLT showed that the cumulative concentration of released elements, per unit surface of specimens were lower than the Dutch Soil Quality Decree (SQD) thresholds, taken as a reference. The low and early release of leachant observed for the mixtures, especially A4 as the most promising one, leave the possibility to handle the leaching with several solutions, including rubber coating treatment or water washing before their incorporation into the mix to limit and prevent their leaching while permitting very high injury reduction performances.
The water‐methanol mixture density at 293.15–303.15 K and atmospheric pressure was predicted by using molecular dynamics (MD) simulation and empirical data. To compute van der Waals and electrostatic ...interactions, the Ewald summation and atom‐based approaches were used. Then, Jouyban‐Acree (J‐A) and density correlation methods for two‐component mixtures were applied for MD simulation results at various temperatures and methanol mole fractions. The COMPASS force field was the best to envisage the mixture density. The average absolute relative deviation (AARD) for J‐A and density correlation models was estimated at 0.12 and 0.15 %, respectively. Based on the MD simulation and experimental data, the AARD for the water‐methanol mixture density at 293.15, 298.15, and 303.15 K was 4.25, 4.37, and 4.8 %, respectively.
Empirical data and molecular dynamics (MD) simulation were used to predict the density of water‐methanol mixtures at 293.15, 298.15, and 303.15 K and atmospheric pressure. The MD simulation results were analyzed by using the Jouyban‐Acree and density correlation methods for two‐component mixtures. The COMPASS force field provided the most accurate data for predicting the density of the mixture.
Mixtures of skew-t factor analyzers Murray, Paula M.; Browne, Ryan P.; McNicholas, Paul D.
Computational statistics & data analysis,
09/2014, Letnik:
77
Journal Article
Recenzirano
Odprti dostop
A mixture of skew-t factor analyzers is introduced as well as a family of mixture models based thereon. The particular formulation of the skew-t distribution used arises as a special case of the ...generalized hyperbolic distribution. Like their Gaussian and t-distribution analogues, mixtures of skew-t factor analyzers are very well-suited for model-based clustering of high-dimensional data. The alternating expectation–conditional maximization algorithm is used for model parameter estimation and the Bayesian information criterion is used for model selection. The models are applied to both real and simulated data, giving superior clustering results when compared to a well-established family of Gaussian mixture models.
•A mixture of skew-t factor analyzers is introduced.•A family of parsimonious mixtures of skew-t factor analyzers is developed.•The models are well-suited for clustering high-dimensional data.•Mixture components can be asymmetric and/or heavy tailed, as required.•The models can also be applied for classification or discriminant analysis.
With the advancement of new power systems, an increasing number of new energy power stations and nonlinear loads are connecting to the grid. This has led to a more serious problem of harmonic ...pollution, with an increase in harmonic sources within the power grid. Estimating the harmonic impedance on the utility side is crucial for assessing harmonic emissions and evaluating harmonic contributions. However, existing methods have some shortcomings in terms of estimation accuracy and robustness. This paper proposes a method for estimating harmonic impedance on utility side based on the Laplace mixture model (LMM) to address these issues. In the proposed method, the LMM of the utility side harmonic current is formulated, and the harmonic impedance on the utility side is subsequently estimated using the maximum likelihood estimation (MLE) and expectation maximization (EM) algorithms. The proposed method demonstrates high estimation accuracy, as it exhibits smaller estimation errors in both simulation and field test cases compared to other estimation methods. Furthermore, even when background harmonics are significant, the proposed method maintains its accuracy.
Abstract
We studied the behavior of mixtures of
173
Yb (with symmetry up to SU(6)) and
171
Yb (up to SU(2)) fermionic isotopes loaded in one-dimensional (1D) optical lattices. To do so, we solved the ...Schrödinger equation describing different systems using a diffusion Monte Carlo technique. We considered continuous Hamiltonians in which the interactions between atoms of different species (isotopes and/or spins) were modeled by contact potentials with parameters derived from their experimental scattering lengths. This implies that we can find both attractive and repulsive interactions between fermion pairs in the same cluster. The strength of those interactions can be changed by varying the transverse confinement, leading to different cluster behaviors. Only balanced clusters, i.e. with the same number of
173
Yb and
171
Yb atoms were considered. We found that the standard state for these clusters is a metallic-like one with different populations of
173
Yb–
171
Yb molecule-like pairs in each optical lattice potential well. However, for big enough clusters, insulator-like states are also possible.
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