Rock refuses of mining and metallurgical production contain a considerable amount of non-ferrous, ferrous, precious, rare and trace metals and represent the man-made feedstock, that has been stockpiled and accumulated...
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Sleep stage scoring is used to evaluate one's overnight sleep process, which is important for clinical diagnosis. However, the visual inspection of sleep data is a laborious task and the scoring results may be sub...
Sleep stage scoring is used to evaluate one's overnight sleep process, which is important for clinical diagnosis. However, the visual inspection of sleep data is a laborious task and the scoring results may be subjective to different clinicians. The purpose of this paper is to develop an automatic sleep stage classification algorithm to reduce the artificial workload. The overnight sleep data are represented by the extracted features from time domain and frequency domain of EEG. An improved k-means clustering algorithm is proposed to classify overnight sleep data into five stages including awake (W), NREM (Non-Rapid Eye Movement) stage 1 (S1), NREM stage 2 (S2), slow-wave sleep (SS) and REM (Rapid Eye Movement). In the improved k-means clustering algorithm, the points with dense surrounding are selected as the original centers by using the concept of density for reference. Additionally, the cluster centers are updated according to `Three-Sigma Rule' during the iteration. The determination of cluster center selection was developed which can be adaptive to the actual cases and abate the singular points effect. The obtained results showed that the accuracy of proposed algorithm was satisfied; especially it can distinguish W, SS and REM effectively. Furthermore, the improved k-means algorithm had less number of misclassification and higher accuracy than the original algorithm.
In this Letter, we investigate a method for controlling the intensity of a light by another light in a periodically poled MgO-doped lithium niobate（PPMgLN） crystal with a transverse applied external electric field. ...
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In this Letter, we investigate a method for controlling the intensity of a light by another light in a periodically poled MgO-doped lithium niobate（PPMgLN） crystal with a transverse applied external electric field. The power of the emergent light can be modulated by the power ratio of the incident ordinary and extraordinary beams. The light intensity control is experimentally demonstrated by the Mach–Zehnder interference configuration, and the results are in good agreement with the theoretical predictions.
We demonstrate a new tunable MEMS-based WDM&OAM Fabry-Perot filter for simultaneous wavelength (WDM) and Orbital Angular Momentum (OAM) (de)multiplexing. The WDM&OAM filter is suitable for dense on-chip integr...
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ISBN:
(纸本)9781509067374
We demonstrate a new tunable MEMS-based WDM&OAM Fabry-Perot filter for simultaneous wavelength (WDM) and Orbital Angular Momentum (OAM) (de)multiplexing. The WDM&OAM filter is suitable for dense on-chip integration and dedicated for the next generation of optical interconnects utilizing all three degrees of freedom of the electromagnetic waves: wavelength, polarization, and OAM. The WDM&OAM filter consists of two Distributed Bragg Reflectors (DBRs), (see Fig. 1a,b): a bottom one fixed to the substrate and a movable top MEMS DBR. An applied tuning current, changing the resonator length, extends the top DBR and hence selects the central filter wavelength. A spiral phase mask on the top switches the OAM order by ±1, ±2, etc. For a detailed description of the structure and fabrication of the device, please refer to [1,2]. The MEMS filter shows a full-width at half-maximum (FWHM) bandwidth of about 0.2 nm and a free spectral range (FSR) of about 126 nm. The phase mask provides sufficient OAM state purity in a 35 nm window around 1550 nm, covering well the whole C-band.
The investigations complex for the explosive breaking effectiveness improvement is presented. The universal channel booster, a differential characteristic of which is the combination of the detonating explosive charge...
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The investigations complex for the explosive breaking effectiveness improvement is presented. The universal channel booster, a differential characteristic of which is the combination of the detonating explosive charge with a longitudinal cavity for the increasing the stable state of detonation is described.
Geomechanical conditions of use of the utilized tails of enrichment of metallic mineral raw materials as the hardening stowage mix are proved. The grounds for the geomechanical balance control of the mountain mass pre...
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The environmental humanization trends of mining engineering in technologically advanced countries are defined. The results of pioneer experiments on the extraction of metals using combined mechanochemical treatment in...
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Obtained by photoelastic method on the models made of optically active materials research findings of ore - hosting massif behavior where anthropogenic tension develops under the exploitation influence are given in th...
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Obtained by photoelastic method on the models made of optically active materials research findings of ore - hosting massif behavior where anthropogenic tension develops under the exploitation influence are given in the article. Conditions of massif elements action with tension arranging on hazard level of its deformability depending on critical tension are considered separately.
The problem of the frictional mechanical contact with slip and stick, also referred to as the Cattaneo-Mindlin problem, is an important topic in engineering, with applications in the modeling of particle-flow simulati...
The problem of the frictional mechanical contact with slip and stick, also referred to as the Cattaneo-Mindlin problem, is an important topic in engineering, with applications in the modeling of particle-flow simulations or in the study of contact between rough surfaces. In the frame of Linear Theory of Elasticity, accurate description of the slip-stick contact can only be achieved numerically, due to mutual interaction between normal and shear contact tractions. Additional difficulties arise when considering a viscoelastic constitutive law, as the mechanical response of the contacting materials depends explicitly on time. To overcome this obstacle, an existing algorithm for the purely elastic slip-stick contact is coupled with a semi-analytical method for viscoelastic displacement computation. The main advantage of this approach is that the contact model can be divided in subunits having the same structure as that of the purely elastic frictionless contact model, for which a well-established solution is readily available. In each time step, the contact solver assesses the contact area, the pressure distribution, the stick area and the shear tractions that satisfy the contact compatibility conditions and the static force equilibrium in both normal and tangential directions. A temporal discretization of the simulation windows assures that the memory effect, specific to both viscoelasticity and friction as a path-dependent processes, is properly replicated.
Existing solutions for the contact problem involving viscoelastic materials often require numerical differentiation and integration, as well as resolution of transcendental equations, which can raise convergence issue...
Existing solutions for the contact problem involving viscoelastic materials often require numerical differentiation and integration, as well as resolution of transcendental equations, which can raise convergence issues. The algorithm advanced in this paper can tackle the contact behaviour of the viscoelastic materials without any convergence problems, for arbitrary contact geometry, arbitrary loading programs and complex constitutive models of linear viscoelasticity. An updated algorithm for the elastic frictionless contact, coupled with a semi-analytical method for the computation of viscoelastic displacement, is employed to solve the viscoelastic contact problem at a series of small time increments. The number of equations in the linear system resulting from the geometrical condition of deformation is set by the number of cells in the contact area, which is a priori unknown. A trial-and-error approach is implemented, resulting in a series of linear systems which are solved on evolving contact areas, until static equilibrium equations and complementarity conditions are fully satisfied for every cell in the computational domain. At any iteration, cells with negative pressure are excluded from the contact area, while cells with negative gap (i.e. cells where the contacting bodies are predicted to overlap) are reincluded. The solution is found when pressure is stabilized in relation to the imposed normal load. This robust algorithm is expected to solve a large variety of contact problems involving viscoelastic materials.
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