Synthesis and Properties of Novel Surface Active Maleic Monomer Containing Phosphate Group

A novel surface active monomer （surfmer） containing poly（ethylene glycol） chain and terminated phosphate group was synthesized. The copolymerization of synthesized surfmer with NVP （N-vinylpyrrolidone） and with NVP and VEP （5-tert-butylperoxy-5-methyl-2-hexene-3-yne monomer） led to formation of corresponding surface-active copolymers. The capability of application of resulted copolymers as surface active macroinitiators of emulsion polymerization of styrene and as components of polymeric scaffolds was investigated.     

Possibility of graphene growth by close space sublimation

Carbon films on the Si/SiO₂ substrate are fabricated using modified method of close space sublimation at atmospheric pressure. The film properties have been characterized by micro-Raman and X-ray photoelectron spectroscopy and monochromatic ellipsometry methods. Ellipsometrical measurements demonstrated an increase of the silicon oxide film thickness in the course of manufacturing process. The XPS survey spectra of the as-prepared samples indicate that the main elements in the near-surface region are carbon, silicon, and oxygen. The narrow-scan spectra of C1s, Si2p, O1s regions indicate that silicon and oxygen are mainly in the SiO _x (x ≈ 2) oxide form, whereas the main component of C1s spectrum at 284.4 eV comes from the sp²-hybridized carbon phase. Micro-Raman spectra confirmed the formation of graphene films with the number of layers that depended on the distance between the graphite source and substrate.     

Optimization of the Active Composition of the Wind Farm Using Genetic Algorithms

The article presents the results of research on the possibilities of using genetic algorithms for solving the multicriteria optimization problem of determining the active components of a wind farm. Optimization is carried out on two parameters: efficiency factor of wind farm use (integrated parameter calculated on the basis of 6 parameters of each of the wind farm), average power deviation level (average difference between the load power and energy generation capabilities of the active wind farm). That was done an analysis of publications on the use of genetic algorithms to solve multicriteria optimization problems. Computer simulations were performed, which allowed us to analyze the obtained statistical data and determine the main optimization indicators. That was carried out a comparative analysis of the obtained results with other methods, such as the dynamic programming method; the dynamic programming method with the general increase of the set loading; the modified dynamic programming method, neural networks. It is established that the average power deviation for the genetic algorithm and for the modified dynamic programming method is located at the same level, 33.7 and 28.8 kW, respectively. The average value of the efficiency coefficient of wind turbine used for the genetic algorithm is 2.4% less than for the modified dynamic programming method. However, the time of finding the solution by the genetic algorithm is 3.6 times less than for the modified dynamic programming method. The obtained results provide an opportunity to implement an effective decision support system in energy flow management.     

Electronically reconfigurable superimposed waveguide long-period gratings

The perturbation to the refractive index induced by a periodic electric field from two systems of interdigitated electrodes with the electrode-finger period l is analyzed for a waveguide with an electro-optically (EO) active core-cladding. It is shown that the electric field induces two superimposed transmissive refractive-index gratings with different symmetries of their cross-section distributions. One of these gratings has a constant component of an EO-induced refractive index along with its variable component with periodicity l, whereas the second grating possesses only a variable component with periodicity 2l. With the proper waveguide design, the gratings provide interaction between a guided fundamental core mode and two guided cladding modes. Through the externally applied electric potential, these gratings can be independently switched ON and OFF, or they can be activated simultaneously with electronically controlled weighting factors. Coupling coefficients of both gratings are analyzed in terms of their dependence on the electrode duty ratio and dielectric permittivities of the core and cladding. The coupled-wave equations for the superimposed gratings are written and solved. The spectral characteristics are investigated by numerical simulation. It is found that the spectral characteristics are described by a dual-dip transmission spectrum with individual electronic control of the dip depths and positions. Within the concept, a new external potential application scheme is described in which the symmetry of the cross-sectional distribution of the refractive index provides coupling only between the core mode and the cladding modes, preventing interaction of the cladding modes with each another. This simple concept opens opportunities for developing a number of tunable devices for integrated optics by use of the proposed design as a building block.     

Effects of the addition of graphite oxide to the precursor of a nanoporous carbon on the electrochemical performance of the resulting carbonaceous composites

Composites of reduced graphite oxide and nanoporous sodium-salt-polymer-derived carbons were prepared with 5 or 20 weight% graphite oxide. The materials were characterized using the adsorption of nitrogen, SEM/EDX, elemental analysis and potentiometric titration. DC conductivity was also measured. The performance of the carbon composites in energy storage was linked to their surface features and the effects of the graphene phase addition on these features. Even though the graphene phase increases the electronic conductivity of all materials, the porosity, and especially pores smaller than 0.8 nm, is the main factor governing the capacitive behavior. Owing to the sodium in the carbon precursor and the presence of graphene layers, unique small pores, similar in size to the electrolyte ions are developed in the resulting composites. These pores increase the capacitance by an electrical double layer mechanism. The composites obtained exhibit noticeable redox reactions due to the presence of oxygen and sulfur in the carbon matrix. An increase in the heat treatment temperature increases the capacitance retention ratio at higher currents owing to an increase in the conductivity and chemical stability of the surface.     

Assessment of four modifications of a novel indexing technique for case‐based reasoning

In this article, we investigate four variations (D‐HS^M, D‐HS^W, D‐HS^E, and D‐HS^EW) of a novel indexing technique called D‐HS designed for use in case‐based reasoning (CBR) systems. All D‐HS modifications are based on a matrix of cases indexed by their discretized attribute values. The main differences between them are in their attribute discretization stratagem and similarity determination metric. D‐HS^M uses a fixed number of intervals and simple intersection as a similarity metric; D‐HS^W uses the same discretization approach and a weighted intersection; D‐HS^E uses information gain to define the intervals and simple intersection as similarity metric; D‐HS^EW is a combination of D‐HS^E and D‐HS^W. Benefits of using D‐HS include ease of case and similarity knowledge maintenance, simplicity, accuracy, and speed in comparison to conventional approaches widely used in CBR. We present results from the analysis of 20 case bases for classification problems and 15 case bases for regression problems. We demonstrate the improvements in accuracy and/or efficiency of each D‐HS modification in comparison to traditional k‐NN, R‐tree, C4,5, and M5 techniques and show it to be a very attractive approach for indexing case bases. We also illuminate potential areas for further improvement of the D‐HS approach. © 2007 Wiley Periodicals, Inc. Int J Int Syst 22: 353–383, 2007.     

Robust design and manufacturing of ceramic laminates with controlled thermal residual stresses for enhanced toughness

Boron carbide-silicon carbide ceramic composites are very promising armor materials because they are intrinsically very hard. However, their fracture toughness is not very high. Their ballistic performance could be significantly increased if the brittleness of these materials could be decreased. Here we report development of boron carbide-silicon carbide layered ceramics with controlled compressive and tensile stresses in separate layers. Such B₄C-SiC laminates with strong interfaces can provide high apparent fracture toughness and damage tolerance along with high protection capabilities. The theory of heterogeneous layered systems was used to develop optimal design parameters allowing the evaluation and maximization of apparent fracture toughness. The layered composites were designed in a way to achieve high compressive residual stresses in thin B₄C-SiC based layers and low tensile residuals stresses in thick B₄C layers. The residual stresses were controlled by the phase composition of layers and the layers thickness. The estimated apparent fracture toughness was calculated for both three layered and nine layered composites. B₄C-30 wt%SiC/B₄C laminates were made based on the optimized design for high apparent fracture toughness. Processing of laminates involved preprocessing of powders, forming green tapes and hot pressing. Work is in progress to measure fracture toughness of laminates, as well as their strength, hardness and the ballistic performance.     

Contribution to quantification of highly inhomogeneous microstructures

In highly inhomogeneous microstructures with a wide range of grain sizes, the problem arises of defining an effective average grain size. An original method for the estimation of effective average grain size and a parameter describing the homogeneity of microstructure are presented. The coefficients of homogeneity for equiaxed and columnar microstructures are calculated. The effective average grain size is calculated as a weighted sum of the average grain sizes of homogeneous grain groups.     

The hydrogenation of fatty oils with palladium catalyst. IV. Pilot-plant preparation of shortening stocks

Summary Shortening stocks obtained in the pilot plant differ slightly from those obtained in the laboratory under nominally the same conditions. Pilot-plant processing is easily controlled to give a commercially attractive shortening at a cost competitive with nickel. By repeated re-use 1 g. of 5% palladium on earbon catalyst will hydrogenate about 18 kg. of oil to a satisfactory product, and 1 g. of 2% palladium on carbon catalyst about 11 kg. of oil.