Using cationic and anionic polymerization of 1,1,3,3-tetramethyl-2-oxa-1,3-disilacyclopentane (
I
) and 1,1,3,3-tetramethyl-2-oxa-1,3-disilacyclohexane (
II
), ...α,ω-dihydroxypolydimethylsildimethyleneand α,ω-dihydroxypolydimethylsiltrimethylenedimethylsiloxanes (
III
and
IV
, respectively) were synthesized. The polymer materials for the flat membranes
MI
and
MII
with stable mechanical properties were produced via crosslinking condensation of tetraethoxysilane and the terminal hydroxyl groups of
III
and
IV
. Methane and butane were applied to demonstrate the gas transport properties of these membranes. It was shown that compared to PDMS, the synthesized
MI
and
MII
have a higher butane/methane ideal selectivity at high permeability coefficients (7800 and 6600 Barrer, respectively). An increase in butane/methane selectivity is achieved due to the high coefficients of butane solubility in the membrane materials.
The
1
H nuclear magnetic resonance (NMR) spectroscopy, NMR imaging, and pulsed field gradient NMR (PFG NMR) were applied for comparative study of moisture–polymer composite materials (PCM) ...interaction. The water uptake in PCM reinforced by aramid and carbon fibers was measured by NMR spectroscopy techniques. The aramid fiber-reinforced PCM absorbs water more intensively compared with PCM reinforced by carbon fiber, but both of them are retaining water inside of pores without formation of chemical bonds. Using NMR imaging the spatial distribution of water absorbed was visualized; preferable water pathways and influence of surface treatment on water-resistant properties were revealed. It was found that the surface rough treatment sufficiently improves the water absorption, but penetration of water molecules is still occurring only through the surfaces and it happens within a thin layer. PFG NMR technique revealed influence of pore structure on moisture–PCM interaction; it was found that additionally to strong hydrophobic properties of carbon fiber, the smaller total volume of pores sufficiently decrease the water uptake. Results achieved in this work demonstrate efficiency of NMR methods applied all together for investigation of PCM, and information obtained is practically important when designing advanced PCM with required properties.
Energy supply to remote areas remains a technical and social challenge. Construction of transmission lines to provide electricity to such areas is expensive and not always possible. One of the ...promising areas in this area is local energy generation based on local resources, in particular small watercourses, using small hydroelectric power plants. Small hydroelectric power plants are small hydropower facilities that use the energy of small watercourses to generate electricity. They have a number of advantages over traditional energy sources, such as environmental friendliness, low operating costs and high efficiency. However, the widespread introduction of small hydroelectric power plants is hampered by the lack of mass production of small hydraulic turbines and difficulties in designing low-power plants. Designing hydraulic turbines is a complex task that requires solving the inverse problem of hydrodynamics and finding the optimal shape of the flow path. To simplify the design of hydraulic turbines in the modern world, specialized software is used using various methods, including flow analysis, energy loss and blade shape optimization. This article based on an analysis of existing methods for designing and using a mathematical model of a hydraulic turbine with simplified blades, proposes a method for designing and analyzing the theoretical characteristics of the resulting hydraulic turbine. In conclusion, taking into account the use of the methodology for designing a hydraulic turbine for given parameters, its assessment is given, as well as ways to possibly improve the accuracy of the results obtained. Possible areas of application of the outlined design methodology are indicated.
Based on the results of X-ray phase analysis, an isothermal section of the quasi-ternary system Ag2S-CdS-SnS2 at 298 K was constructed. The existence of the Ag2CdSnS4 compound was confirmed, and a ...new quaternary phase Ag2CdSn3S8 was discovered. The crystal structure of both compounds was refined using X-ray powder method. Ag2CdSnS4 crystallizes in the orthorhombic space group Cmc2(1) with the unit cell parameters a=0.41015(3), b=0.70224(4), c=0.66946(4) nm (R(I)=0.0550). The Ag2CdSn3S8 crystal structure refines well in both the tetragonal structure of the rhodostannine type (space group I4(1)/a, a=0.76163(6), c=1.0771(2) nm, R(I)=0.0750) and the cubic structure of the chalcospinel type (space group Fd3m; a = 1.07635(2) nm, R(I) =0.0781). The phase diagram of the Ag8SnS6-CdS section was constructed, which is of the eutectic type. The eutectic point coordinates are ~47 mol.% CdS and 1082 K.
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•An Electrochemical-Chemical-Electrochemical mechanism of carbon dioxide electroreduction in molten salts is proposed.•The electroreduction of CO2 to solid phase carbon in molten ...chlorides can be taken as the basis of electrochemical synthesis of various nanoscale carbonaceous materials: multiwalled tubes, fibers, amorphous carbon and crystalline graphite.•The possibility of doping nanostructured carbon materials with metals (Fe, Pt) in one step during synthesis has been shown.
Electrochemical synthesis in molten salts has great possibilities for the production of various carbonaceous materials (graphite, graphene, ultra-fine amorphous carbon, doped and undoped carbon nanotubes and fibers) in one step in the form of films and ultra-fine powders. Carbon dioxide dissolved in molten salts under excess pressure can be a carbon precursor during the synthesis. The peculiarities of electrochemical reduction of carbon in solid state from CO2 were studied by cyclic votammetry. The mechanisms of cathodic and anodic processes were suggested. The conditions (composition of electrolytic bath, temperature, cathodic current density, bath potential) of electrochemical synthesis of nanoscale carbon materials were determined. The properties of the produced carbon-containing products were analyzed by XRD, SEM, TEM, ED, Raman spectroscopy. A correlation of product properties with synthesis conditions and parameters has been made.
The NICA accelerator complex is developed on the JINR base in Dubna for performing physical experiments on colliding beams of heavy ions. It consists of the injection complex, booster synchrotron, ...upgraded Nuclotron synchrotron, and heavy-ion collider. The booster is currently under assembly. The system, developed at the LHEP JINR to perform precise temperature measurements of superconducting magnets of the booster synchrotron, is described. The thermometry system includes more than 240 resistive TVO-type temperature sensors, the National Instruments data acquisition system, software based on Tango Controls technology, and a web-client application.
Introduction
.
Shipping, as one of the infrastructural transport communications, is a strategic branch of the economy of the Russian Federation. The timely delivery of goods, equipment, materials and ...raw materials to consumers depends on the reliability of shipping facilities operation. Therefore, ensuring safety, preventing man-made and natural destructive events are urgent and priority tasks of the owners of such facilities. Among the incidents that can cause significant direct and indirect damage, the most dangerous are fires. In this regard, in order to make management decisions on fire safety, it is necessary to know the situation with fires, to understand their social and economic consequences, to be able to identify possible causes for fires both at construction infrastructure facilities (shipyards, docks, port facilities) and on watercraft. At the same time, an important component in making such decisions is the study of the effectiveness of the fire alarm as a primary element in the general technological systems of fire automation on shipping facilities.
Problem Statement
.
The objective of the study is to analyze the causes of fires and the operation of fire alarm systems at shipping facilities.
Theoretical Part
.
Based on statistical data on fires and their consequences for 2017-2021, the social (the number of dead and injured people) and economic (direct material damage) consequences of fires at shipyards, port facilities, watercraft (ships, boats, vessels) and docks are analyzed. Estimates of the effectiveness of fire alarm systems at shipping facilities are given.
Conclusions
.
The efficiency of fire alarm systems at all shipping facilities is on average at the level of 90%. At the same time, for sea and river vessels, this figure is about 82%, for port facilities it is almost 100%. But despite such a high level of fire alarm systems, it is not possible to avoid social and material consequences of fires. In addition, it should be noted that most fires occur at shipping facilities that are privately owned. At shipyards, port facilities and docks, fires on private property account for 71% of the total number of fires. On private sea and river vessels, the proportion of fires reaches 90%.
The effect of the nature of the pore-forming agent (polyethylene glycol, ethylene glycol, diethylene glycol, glycerol) on the structure and performance of hollow fiber membranes spun from polysulfone ...solutions in N,N-dimethylacetamide was studied. The membranes have been characterized using various methods (determination of gas permeability and water entry pressure, scanning electron microscopy, contact angle measurement). To increase the hydrophobicity of the selective layer of hollow fibers, a procedure for applying a modifying polydimethylsiloxane layer onto the inner surface of the fiber has been developed, which has made it possible to increase the contact angle from 75°–77° to 115°–151° with retaining their gas transport properties. The composite membranes designed hold promise for use in gas–liquid membrane contactors, and hydrophobized membranes with reduced gas permeability can be used for hydrophobic pervaporation.
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