Machine Learning Algorithms for Prediction of the Quality of Transmission in Optical Networks

Increasing demand in the backbone Dense Wavelength Division (DWDM) Multiplexing network traffic prompts an introduction of new solutions that allow increasing the transmission speed without significant increase of the service cost. In order to achieve this objective simpler and faster, DWDM network reconfiguration procedures are needed. A key problem that is intrinsically related to network reconfiguration is that of the quality of transmission assessment. Thus, in this contribution a Machine Learning (ML) based method for an assessment of the quality of transmission is proposed. The proposed ML methods use a database, which was created only on the basis of information that is available to a DWDM network operator via the DWDM network control plane. Several types of ML classifiers are proposed and their performance is tested and compared for two real DWDM network topologies. The results obtained are promising and motivate further research.     

Real-World Data Difficulty Estimation with the Use of Entropy

In the era of the Internet of Things and big data, we are faced with the management of a flood of information. The complexity and amount of data presented to the decision-maker are enormous, and existing methods often fail to derive nonredundant information quickly. Thus, the selection of the most satisfactory set of solutions is often a struggle. This article investigates the possibilities of using the entropy measure as an indicator of data difficulty. To do so, we focus on real-world data covering various fields related to markets (the real estate market and financial markets), sports data, fake news data, and more. The problem is twofold: First, since we deal with unprocessed, inconsistent data, it is necessary to perform additional preprocessing. Therefore, the second step of our research is using the entropy-based measure to capture the nonredundant, noncorrelated core information from the data. Research is conducted using well-known algorithms from the classification domain to investigate the quality of solutions derived based on initial preprocessing and the information indicated by the entropy measure. Eventually, the best 25% (in the sense of entropy measure) attributes are selected to perform the whole classification procedure once again, and the results are compared.     

Two-photon annihilation rate of the positronic HCN molecule

Positron binding by the HCN molecule was studied within a modified adiabatic approximation. This approach, in which the positron is treated as a light pseudonucleus with fractional charge, leads to the binding energy of 0.65?mHartree. Using effective positron mass which reproduces the Quantum Monte Carlo binding energy gives an estimation of the two-photon annihilation rate of e ⁺HCN, equal to 0.091?ns^?1.     

Self-organisation of di(perfluorohexyl)hexane in Langmuir and LB films

Symmetrical triblock semifluorinated n-alkane, di(perfluorohexyl)hexane of the formula F(CF₂)₆(CH₂)₆(CF₂)₆F (abbreviated F₆H₆F₆), has been synthesised and investigated at the air/water interface. Our results show for the first time that this unusual film-forming material, completely hydrophobic in nature and possessing no polar group, is capable of stable film formation at the free water surface. The surface pressure–area isotherm of the studied compound exhibited two regions: corresponding to monotonous pressure rise, followed by a pseudo-plateau region. Visualisation of film structure with Brewster angle microscope (BAM) proved the formation of domains within the pseudo-plateau region. A closer insight into the structure of these domains with atomic force microscope (AFM) proved their ordered, circular shape. The average area of F₆H₆F₆ domain was found to depend on surface pressure value, as it is 4.98 ± 1.75 μm² at π = 1.2 mN/m to 16.54 ± 0.31 μm² at π = 1.7 mN/m. Following performed quantum-chemical calculations, it can be concluded that the observed surface aggregates from F₆H₆F₆ are formed by linear conformers with shifted CF and CH parts. The calculated domain thickness is between 20 and 21 Å, which perfectly agrees with the experimental value estimated from AFM measurements (20.3 ± 1.4 Å).     

Photothermally Induced Bistability of Emission of Yb-doped Ca4NdO(BO3)3 Single Crystals

We report on studies of changes in the emission spectra (excited at 808 nm) of the Yb-doped Ca₄NdO(BO₃)₃ single crystals due to the photothermal effects caused by the pulsed Nd:YAG laser. Increase of the sample's surface temperature after laser treatment leads to significant enhancement of the 1040 to 1060 nm emission (ascribed to the Nd^{3+ 4}F_3/2 → ⁴I_9/2, ⁴I_11/2 transitions) and simultaneous decrease of the 975 to 1050 nm emission (corresponding to the Yb^{3+ 2}F_5/2 → ²F_7/2 transition). We explain such an increase of the Nd³⁺ luminescence by thermally activated Yb³⁺ → Nd³⁺ energy transfer.     

Basal slip localization in zinc single crystals. The Considère analyses

The tensile and compression tests were performed on zinc single crystals oriented for slip in the basal slip system. During the first stage of the stress–strain curve, the localized necking was typical of strain localization in the tensile specimens. Single or multiple necks were formed along the specimen length. The range of temperatures and the strain rates for single necking of the sample was determined. The formation of such necking depends on strain hardening characteristics and can be predicted by the Considère criterion. On the other hand, propagation of the necked area along the sample length was not predictable by this criterion. Localized sliding and specimen kinking was indicative of the strain localization observed for different specimens compressed under the same conditions, i.e. temperature and strain rate. A decrease in the compression force and in the cross-sectional area with anvil displacements produced localized sliding. On the other hand, a continuous increase in the compression force was representative of tests leading to specimen kinking.     

Microstructure and mechanical properties of nano-Y2O3 dispersed ferritic steel synthesized by mechanical alloying and consolidated by pulse plasma sintering

Ferritic steel with compositions 83.0Fe–13.5Cr–2.0Al–0.5Ti (alloy A), 79.0Fe–17.5Cr–2.0Al–0.5Ti (alloy B), 75.0Fe–21.5Cr–2.0Al–0.5Ti (alloy C) and 71.0Fe–25.5Cr–2.0Al–0.5Ti (alloy D) (all in wt%) each with a 1.0?wt% nano-Y₂O₃ dispersion were synthesized by mechanical alloying and consolidated by pulse plasma sintering at 600, 800 and 1000°C using a 75-MPa uniaxial pressure applied for 5?min and a 70-kA pulse current at 3?Hz pulse frequency. X-ray diffraction, scanning and transmission electron microscopy and energy disperse spectroscopy techniques have been used to characterize the microstructural and phase evolution of all the alloys at different stages of mechano-chemical synthesis and consolidation. Mechanical properties in terms of hardness, compressive strength, yield strength and Young's modulus were determined using a micro/nano-indenter and universal testing machine. All ferritic alloys recorded very high levels of compressive strength (850–2850?MPa), yield strength (500–1556?MPa), Young's modulus (175–250?GPa) and nanoindentation hardness (9.5–15.5?GPa), with up to 1–1.5 times greater strength than other oxide dispersion-strengthened ferritic steels (<1200?MPa). These extraordinary levels of mechanical properties can be attributed to the typical microstructure of uniform dispersion of 10–20-nm Y₂Ti₂O₇ or Y₂O₃ particles in a high-alloy ferritic matrix.     

Helical twisting power of antiferroelectric chiral terphenyls in different matrices

To determine the influence of chemical structure on the Helical Twisting Power (HTP), we tested four optically active dopants having a terphenyl rigid core and the same chiral centre but differing in the length of nonchiral terminal chain and the substitution of benzene rings with fluorine atoms. The compounds were added to different achiral liquid crystalline matrices: nematic and smectic C. It was found that HTP as well as its temperature variation depends on the kind of used matrices. It gives a conclusion that information about HTP obtained in one matrix cannot be uncritically transferred to another one.     

Two-point Padé approximants for formal Stieltjes series

We prove that certain two-point Padé approximants occupying the diagonal of the Padé table form monotone sequences of lower and upper bounds uniformly converging to a Stieltjes function. The results can be applied to the theory of inhomogeneous media for the calculation of the bounds on the effective transport coefficients of heterogeneous materials.     

A Goal Programming model of the reference point method

Real-life decision problems are usually so complex they cannot be modeled with a single objective function, thus creating a need for clear and efficient techniques of handling multiple criteria to support the decision process. The most commonly used technique is Goal Programming. It is clear and appealing, but in the case of multiobjective optimization problems strongly criticized due to its noncompliance with the efficiency (Pareto-optimality) principle. On the other hand, the reference point method, although using similar control parameters as Goal Programming, always generates efficient solutions. In this paper, we show how the reference point method can be modeled within the Goal Programming methodology. It allows us to simplify implementations of the reference point method as well as shows how Goal Programming with relaxation of some traditional assumptions can be extended to a multiobjective optimization technique meeting the efficiency principle.