Reliability of Certain Class of Transportation Networks

The reliabilityof a special class of technical objects - tree-like transportation networks is considered. It is argued that the indicators traditionally used to assess reliability in relation to such objects are not very informative and are ambiguously interpreted from a physical point of view. As a quantitative measure, an indicator of operational reliability is proposed and an engineering method for its calculation has been developed. It uses the features of the object, is based on an analogue of the Y-shaped structure-forming fragment of the network and is reduced to a repeating step-by-step computational procedure, when at each step the results of the calculation are obtained at the previous stage and used as initial data. Relationships are derived that allow extending this approach to the case when at the junction point of network elements not two, but, in general, n elements are combined. The advantages of the introduced indicator of the operational reliability of tree-like transportation networks are discussed and the ways of its further generalization and use are outlined

Solubilization Behavior of Homopolymer in Its Blend with the Block Copolymer Displaying the Feature of Lower Critical Ordering Transition

Blending with homopolymer offers a facile approach for tuning the microdomain morphology of block copolymer, provided that the homopolymer chains are uniformly solubilized in the corresponding microdomain to swell the junction point separation. Here we studied the solubilization behavior of poly(4-vinyl pyridine) homopolymer (h-P4VP) in the lamellar microdomain formed by its blends with a poly(ethylene oxide)-block-poly(4-vinyl pyridine) (PEO-b-P4VP) showing the feature of lower critical ordering transition (LCOT) in terms of weaker segregation strength at lower temperature. We revealed that, while the conventional criterion of homopolymer-to-block molecular weight ratio for attaining uniform solubilization was applicable to LCOT blend, there was an excess swelling of junction point separation upon the addition of homopolymer, leading to a decrease of interdomain distance with increasing homopolymer composition. This anomalous phenomenon was attributed to the reduction of interfacial free energy due to the incorporation of P4VP homopolymer into the microdomain interface.

Reconnaissance Stream Sediments Survey in the Sidakan Vicinity, Iraqi Kurdistan Region

A stream survey was conducted in the Sidakan vicinity in the northeastern part of the Iraqi Kurdistan Region, which covered the catchment area of the main stream. The covered area is about 450 km2. The exposed rocks in the study area are mainly igneous with subordinate sedimentary and metamorphic rocks. The catchment area was divided into 14 sub-basins using Global Mapper software. The junction point of the valleys at the end of each sub-basin was sampled. From each junction point, 2 stream sediments were collected. The samples were sieved using the wet method into 2 mm fractions, before the fractions were subjected to x-ray fluorescence (XRF) and x-ray diffraction (XRD) analysis. The results obtained from both tests were used to calculate the concentrations of 9 elements (Cr, Ni, Co, Cu, U, Ag, V, Zn, and Cd). The element concentrations are presented in 9 concentration maps after normalizing the concentration values. Some anomalous results were found. The average concentrations of Ag and Cd were nearly 120 and 266 times higher than the background concentrations (6 mg/kg and 16 mg/ kg, respectively). The acquired data also showed interesting average concentrations for the elements Co, Cr, Ni, and U (280 mg/kg, 999 mg/kg, 375 mg/kg, and 12 mg/kg, respectively). All of these anomalous concentrations are discussed and possible reasons for their existence are given.

Simulation of heat transfer at the junction of the attic floor to the building envelope

Numerous studies and thermal imaging inspection of multi-storey residential buildings indicate characteristic places with increased heat loss. In houses built in accordance with modern domestic regulatory requirements for the thermal resistance of enclosing structures, the actual thermal resistance of walls and windows coincides with the standard. However, nodes of elements of external enclosing structures with increased values of heat loss were found. Insulation of the junction points allows increasing the thermal resistance of the external enclosing structures. In order to increase the energy efficiency of a building, the design of the insulation of the junction of the ceiling in the technical attic has been proposed, which is protected by a patent for a useful model. The linear heat transfer coefficients of the junction point of the ceiling in the attic are analyzed. It was revealed that such information was not indicated in the regulatory documents. Reducing heat loss is achieved by arranging additional layers of insulation in the form of aerogel slabs at the junction of the ceiling to the external enclosing structures. The analysis of the energy efficiency of the proposed design of the junction unit of the attic floor as a "cold bridge" was carried out according to the results of mathematical modeling in the DAMWERK software package. Based on the simulation results, the temperature distribution in the junction of the ceiling in the technical attic was established. The linear heat transfer coefficient of the recommended junction point of the ceiling in the technical attic has been determined, the value of which should be taken into account when developing the Energy Efficiency section. The results obtained confirm the feasibility of introducing the proposed structural design of the floor abutment unit in the technical attic, which will improve the energy efficiency of the building's thermal insulation envelope.

Selection criteria and a mathematical model for the additional source of reactive power in a backbone network

In a backbone network (𝑈􀯡 ≥ 220 𝑘𝑣), when the high-voltage lines are loaded with power less than natural power, we have excess reactive power. Supplying this power into the lower-voltage networks (𝑈􀯡 ≤ 110 𝑘𝑣) would be technically and economically unfeasible and requires compensation on site. In the article, in accordance with the electricity quality criterion, and taking into account the principle of a systemic approach, and using the self- and mutually reactive impedances of the network junction points, a mathematical model for selecting a compensating device in a backbone network is adopted. The quality criterion of electricity involves enforcement of requirements for the operating voltages in the junction points of a backbone network. According to the obtained mathematical model, in the junction points nodes where the operating voltages exceed their permitted values, there will be installed the compensating devices for receiving excess reactive power. However if any junction point has a high reactive load and the voltage, in this context, is below its permitted value, then, according to a model, there is a need for installing the source of reactive power in this junction point. Herewith, according to economic criterion, the model envisages the optimal redistribution of mentioned source of reactive power between the junction points of a distribution network connected to backbone network junction point.