DERIVATION OF THE EQUATION OF UNSTEADY-STATE MOISTURE BEHAVIOUR IN THE ENCLOSING STRUCTURES OF BUILDINGS USING A DISCRETE-CONTINUOUS APPROACH

Two differential equations of moisture transfer based on the theory of moisture potential have been considered. The first equation includes the record of moisture transfer mechanisms of vapor and liquid phases and their relationship. The second equation is a simplified form of the first equation which makes it possible to apply a discrete-continuous approach. The peculiar properties of the boundary conditions setting of the outside air for temperature and humidity fields have been presented. It is proved that the use of the discrete-continuous method provides high accuracy of calculations and can be used in engineering practice to assess the unsteady humidity regime of enclosing structures.

The comparison of a discrete-continuous approach and a method of finite differences in solving the problem of unsteady-state heat and moisture transfer in the building envelope

This article is devoted to the development of methods for calculating heat and humidity regime in the building envelope. The equation of steady-state thermal conductivity with boundary conditions of the third kind and the formula for calculating heat losses of a building based on the heat transfer equation have been considered. The equation of unsteady-state thermal conductivity as well as its solution using the discrete-continual approach has also been studied. The solution of the unsteady-state heat conductivity problem with invariable over time boundary conditions using the discrete-continuous approach was proposed by A.B. Zolotov and P.A. Akimov. The subsequent modernization of the solution was conducted by V.N. Sidorov and S.M. Matskevich. The unsteady-state equation of moisture transfer based on Fick’s second law using the theory of moisture potential is derived. The solution of the unsteady-state moisture transfer equation using the finite difference method according to an explicit difference scheme as well as the solution of the unsteady-state moisture transfer equation using the discrete-continuous approach is demonstrated. To prove the effectiveness of using the discrete-continuous approach in the area of the unsteady-state humidity conditions we compared the calculation results of the distribution of moisture in a single-layer enclosing structure made of aerated concrete using two methods of moisture potential theory. It was found that the difference in the results of calculation by the discrete-continual formula and by the method of finite differences does not exceed 3.2%.

SARS-CoV-2 adsorption on suspended solids along a sewerage network: mathematical model formulation, sensitivity analysis, and parametric study

Accounting for SARS-CoV-2 adsorption on solids suspended in wastewater is a necessary step towards the reliable estimation of virus shedding rate in a sewerage system, based on measurements performed at a terminal collection station, i.e., at the entrance of a wastewater treatment plant. This concept is extended herein to include several measurement stations across a city to enable the estimation of spatial distribution of virus shedding rate. This study presents a pioneer general model describing the most relevant physicochemical phenomena with a special effort to reduce the complicated algebra. This is performed both in the topology regime, introducing a discrete-continuous approach, and in the domain of independent variables, introducing a monodisperse moment method to reduce the dimensionality of the resulting population balance equations. The resulting simplified model consists of a large system of ordinary differential equations. A sensitivity analysis is performed with respect to some key parameters for a single pipe topology. Specific numerical techniques are employed for the integration of the model. Finally, a parametric case study for an indicative—yet realistic—sewerage piping system is performed to show how the model is applied to SARS-CoV-2 adsorption on wastewater solids in the presence of other competing species. This is the first model of this kind appearing in scientific literature and a first step towards setting up an inverse problem to assess the spatial distribution of virus shedding rate based on its concentration in wastewater.

Computational Study on the Interaction and Moving of ssDNA through Nanosheets

The adsorption characteristics and moving through nanopores of a single-stranded deoxyribonucleic acid (ssDNA) molecule on monolayers, such ashexagonal boron nitride and graphene nanosheets, were studied using the continuous approach with the 6–12 Lennard–Jones potential function. The ssDNA molecule is assumed to be at a distance l above the sheet, and the relation between the minimum energy location and the perpendicular distance of the ssDNA molecule from the nanosheet surface is found. In addition, by assuming that there is a hole in the surface of the nanosheet as a pore, the interaction energies for the ssDNA molecule moving through the pore in the surface of the nanosheet (used to calculate the radius p of the hole) are obtained, which provides the minimum energies. Furthermore, a comparative study with graphene was performed in order to compare with hexagonal boron nitride nanosheets. Our results indicate that the binding energies of the ssDNA onto graphene and hexagonal boron nitride nanosheets are approximately 15.488 and 17.582 (kcal/mol), corresponding to perpendicular distances of l=20.271 and l=20.231 Å, respectively. In addition, we observe that the ssDNA molecule passes through graphene and hexagonal boron nitride nanopores when the gap radius p>7.5 Å. Our results provide critical insights to understand and develop the interactions and translocation of DNA molecules with and through nanosheets.

Irregularities and Roughness

The periodically repeated pavement irregularities and their effect on the dynamic behavior of a bridge are the subject of this paper, as well as a new point of view of how the surface roughness operates on vehicles. The authors observed that the models used so far accept that the wheels are always in contact with the roughness curve. But in reality the wheels only come in contact with the peaks of the roughness curve by applying impact forces. The theoretical formulation is based on a continuous approach that has been used in literature to analyze such bridge. The procedure is carried out by the modal superposition method, while the obtained equations are solved by using Duhamel’s integrals. Important conclusions for structural design purposes can be drawn through a variety of numerical examples.

Defining Bilingualism in Infancy and Toddlerhood: A Scoping Review

Controversy surrounds whether bilinguals have advantages in cognitive flexibility, memory, and metalinguistic ability or costs associated with language processing. However, mixed findings are difficult to interpret because of a lack of agreement on the definition of “bilinguals.” The aim of this quantitative descriptive scoping review is to provide an overview of the population and languages studied, and the methods and practices surrounding the definition of bilingualism in children three years and younger. From 530 articles, we identified 127 papers (167 studies) that met our predefined criteria, of which 144 studies provided some kind of definition for their bilingual population. The samples investigated were predominantly western in geographical origin and languages. Percent exposure was the most common method to measure bilingualism among infants and young children, with 20% and 25% the most used cut-off as the minimum requirement for children’s second language. We also analyzed the predictive value of these minimum cutoffs of bilingualism on the likelihood that studies reported a significant difference between monolinguals and bilinguals. The stricter the inclusion requirement for bilinguals was, the higher the odds of a study to report a difference between monolingual and bilingual children. We conclude that a lack of uniformity of definition in the field may be one factor that predicts whether or not significant differences are reported. Implications of these findings are discussed, and the following recommendations are provided. As globalization continues to foster migration and intercultural exchange, it is essential for developmental researchers to diversify their samples and language groups. We highly encourage researchers to carefully document the definitions and rationale for all their language groups and to consider analyzing the impact of bilingualism both from a categorical and continuous approach.

USING DISCRETE-CONTINUOUS APPROACH FOR THE SOLUTION OF UNSTEADY-STATE MOISTURE TRANSFER EQUATION FOR MULTILAYER BUILDING WALLS

Moisture regime of enclosing structures is one of the most complicated and controversial directions in construction industry. Temporary climate impact on enclosing structures and low moisture inertia of building materials lead to the situation in which it is impossible to calculate the steady-state moisture regime. Numerical methods are usually used to assess the moisture behaviour of the enclosing structures. In the current paper, a differential equation of moisture transfer is formulated. The solution of the unsteady-state equation of moisture transfer was obtained using the discrete-continuous approach. Thus, a formula which allows scientists to calculate unsteady-state moisture transfer in multilayer walls of buildings was obtained. A two-layer building enclosing structure with aerated concrete base and mineral wool insulation was calculated.