Economic Feasibility Evaluation of Building Passive Houses

The research presents an improved method of rational design of energy-efficient low-rise residential buildings according to their life cycle. The mathematical model for finding the optimal version of draft power-efficient residential building has been developed. For conditions of Ukraine the optimization problem has been set and solved （finding the optimal version of the draft energy-efficient buildings）. The calculations prove the fact that the construction of passive houses in Ukraine today is economically feasible. Scientific and practical regulations, outlined in the research, can be used by all participants of the investment programs, and energy-efficiency projects, renovation projects and developing normative-technical documents.     

Adsorption of hydrogen sulfide on graphite derived materials modified by incorporation of nitrogen

Adsorbents for hydrogen sulfide were prepared by heat treatment at 950 °C of spent graphite oxide based materials previously used as ammonia removal media. The materials were characterized using adsorption of nitrogen, potentiometric titration, thermal analysis, FTIR and XRD. The dynamic adsorption experiments showed an enhanced adsorption capacity owing to the presence of basic nitrogen functionalities. Although on the surface of adsorbents hydrogen sulfide was mainly oxidized to elemental sulfur small amount of SO₂ was also formed. The removal capacity was found to depend on the dispersion of nitrogen containing species, which is governed by the porosity and structure of the adsorbents. The amount of nitrogen incorporated depends on the amount of ammonia on the surface and on the surface reactivity. The latter is determined by the amount of oxygen containing groups and the level of structural heterogeneity.     

Effects of surface chemistry on the reactive adsorption of hydrogen cyanide on activated carbons

Two activated carbons of different origins were modified by heating at 950 °C either with or without previous urea impregnation. The treatment causes changes in surface chemistry and porosity. The materials obtained were used as adsorbents for hydrogen cyanide in dry air at ambient conditions. The samples before and after adsorption were characterized using nitrogen adsorption, potentiometric titration, elemental analysis and thermal analysis. On selected samples extraction was carried out to identify surface reaction products soluble in alcohols. The results indicated differences in the amount adsorbed and the products of surface reactions on specific surface features. The presence of nitrogen incorporated in the carbon matrix leads to an enhanced performance owing to the basic environment and the ability of the surface to activate oxygen. These lead to complex surface reactions in which the derivatives of hydrogen cyanide form oxamide, and are incorporated in the carbon matrix, or are deposited as the bulky insoluble polymers of paracyanogen on the surface. The reactions mainly occur in pores with sizes between 10 and 20 Å where the functional groups can be present and HCN, or its derivatives, and water can take part in the reactions.     

Adsorption of dibenzothiophenes on activated carbons with copper and iron deposited on their surfaces

Three polymer-derived carbons with iron and different amounts of copper on the surface were investigated as adsorbents of dibenzothiophene (DBT) and 4, 6-dimethyldibenzothiophene (DMDBT) from simulated diesel fuel. To characterize the initial and exhausted carbons nitrogen adsorption, elemental analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermal analysis (TA) were applied. The selectivities for DBT and DMDBT were calculated with reference to naphthalene. In spite of the enhancement in selectivity for DBT and DMDBT removal caused by iron and copper species, the results indicate that the volume of micropores is the main factor governing the amount adsorbed. Oxidation of benzothiophenes is likely promoted by iron oxide and copper/copper oxide highly dispersed on the surface. The oxidation products are then selectively adsorbed on the surface of carbon in larger pores where metal species and heteroatoms are the active centers for adsorption of polar species.     

Ultrashort pulse propagation in uniform and nonuniform waveguide long-period gratings

We conduct a detailed theoretical analysis of ultrashort pulse propagation through waveguide long-period grating (LPG) structures operating in the linear regime. We first consider the case of uniform LPGs, and we also investigate the effect of the typical grating nonuniformities, e.g., grating profile apodization, grating period chirping, and discrete phase shifts, on the spectral and temporal behavior of LPG structures. The two interacting modes are analyzed separately, and advanced representation tools, namely, space-wavelength and space-time diagrams (where space refers to the longitudinal grating dimension), are used to provide a deeper insight into the physics that determines the pulse evolution dynamics through the grating structures under analysis. In addition to its intrinsic physical interest, our study reveals the strong potential of LPG-based devices for optical pulse reshaping operations in the subpicosecond regime.     

One-pot preparation of functionalized nanostructured carbons

Functionalized nanostructured carbons were obtained by template method using sucrose as carbon precursor and silica gel SG60 as structure directing agent. To introduce acid groups into carbon a different amount of phosphoric acid was added to sucrose (impregnation ratio 0–1) before filling the pores of silica gel. After carbonization at 800 °C silica template was removed by dissolution in HF. Carbons were characterized by SEM/EDX, nitrogen adsorption at 77 K and acid–base titration. Pore size distributions (PSD) indicated that carbons obtained at impregnation (IR) of 0–0.75 have pores with size less than 4 nm due to crack during carbonization and activating action of phosphoric acid. Templated pores with 5.1 nm are observed in all carbons. PSD significantly changed at IR = 1 showing additional large mesopores of 8.2 nm. Acid–base titration revealed very high concentration of acid surface groups (4.1–4.7 mmol/g), significant amount of which (46 ± 3%) belongs to phosphate groups (pK = 2.3 ± 0.1). Another surface groups are weak carboxylic (pK = 5.9 ± 0.3), lactone and/or enol (pK = 7.2 ± 0.2, pK = 8.8 ± 0.3) and phenol groups (pK = 10.5 ± 0.3). SEM showed smooth carbon surface up to impregnation ratio 0.5 and increasing roughness at higher amount of phosphoric acid.     

Surface properties of porous carbons obtained from polystyrene-based polymers within inorganic templates: role of polymer chemistry and inorganic template pore structure

Three inorganic adsorbents were applied as templates to produce porous carbons from polystyrene-based organic polymers. As matrices, amorphous silica gel, mesoporous alumina and microporous zeolite 13X were used. Organic precursors were polystyrene sulfonic acid (co-maleic acid) sodium salt and polystyrene co-maleic acid isobutyl/methyl mixed ester. The impregnated templates were carbonized at 800 °C. After removal of inorganic matrices porous carbons were obtained. Materials were characterized by adsorption of nitrogen, thermal analysis, potentiometric titration and SEM. Owing to the template carbonization, highly mesoporous carbons were obtained (S_BET up to 1500 m²/g, V_t up to 3 cm³/g) with majority of pores with sizes between 20–200 Å. Although the carbons were not replicas of their matrices, the carbonization within the confined space with utilization of self-released pore formers resulted in unique carbonaceous materials with very acidic surface. That acidity is linked to either exothermic effect of sodium reactivity with moist air or susceptibility for air oxidation of small graphene layers formed in the confined pore space.     

Investigation of influence of constraints with radius links on locomotive axle load distribution and wheelset steering ability

The problem of improving the tractive and dynamic performance of locomotives by means of using axle boxes with inclined radius links was investigated. The kinematics of axle boxes with different variants (different angles) and designs of inclined radius links, based on the vector contour method for link mechanisms, was studied. The results of a bogie design with vertically inclined radius links were used for the improvement of vertical load distribution for locomotives. The behavior of a locomotive running in a curve is more complicated because the lateral forces appear between a flange of the wheel and the head of the rail in the contact zone, and the values of wheel slip are higher than for straight sections of track. These two factors are the main reasons for wheel wear. Theoretical and experimental investigations to reduce wear and to improve vehicle dynamics were made, and the results obtained show that an effective solution can be reached by the use of inclined links to the longitudinal axis of a bogie in the horizontal plane. Questions about the development of a bogie with a radial installation and active steering are discussed.