Inertia Radius Research Articles

Synchrotron small-angle X-ray scattering study of flame retardants based on ammonium sulfate and disubstituted ammonium phosphate

The use of wood in structural and finishing materials can significantly reduce the time of building construction, but the high flammability of wood limits its use in the building industry. To increase fire resistance, wooden structures are impregnated with flame retardants and the penetrating ability depends on their structure. We present the results of a small-angle X-ray scattering study of the structure of flame retardants based on ammonium sulfate and phosphate. The radii of inertia of hydrated complexes formed when flame retardants are dissolved in water, their shape and type of chains along which hydrated ions are located are determined. It is revealed that the presence of diffraction maxima indicates the presence of an ordering in the arrangement of hydrated ions. Aqueous solutions of ammonium sulfate and disubstituted ammonium phosphate contain two types of hydrated complexes of the same shape but different radius of inertia. At the same time, hydrated ions in complexes are located along persistent chains, and ordering revealed in the arrangement of ions, depended on their type. The results obtained can be used in developing flame retardants with a reduced radius of inertia, which will increase the penetrating capacity of the processing solution and increase the fire safety of wooden structures.

OVERVIEW OF CHANGES IN THE STRUCTURE OF ASSORTMENTS AND COSTS OF BUILDING PROFILES IN UKRAINE

Purpose. The main purpose of the publication is a qualitative and quantitative analysis of the changes associated with the implementation of new standards for rolled steel in recent years in the domestic regulatory framework. Also, an additional purpose is to estimate changes in the cost structure of certain types of rolled metal in Ukraine over the past 5 years. Methodology. In order to achieve the main purpose, both the rolled steel standards currently in force in Ukraine and the canceled previous standards were examined in detail. Comparison of standards for sheet profiles was carried out according to the criteria of the number of standard sizes and the profiles themselves in the standard. Comparison of standards for shaped profiles was carried out according to several criteria – the number of available standard sizes of profiles, the number of profiles themselves, the mass indicators of the largest and smallest profiles, as well as the efficiency indicators (nuclear distance and the square of the radius of inertia) of the largest and smallest profiles according to the standard. To assess changes in the cost structure of assortment profiles of various types, a quantitative comparison of their absolute and relative market value was carried out based on data from open electronic resources for the past 5 years. Findings. At present, in the part of standards for the range of steel products in Ukraine, a systematic and full-fledged update of the regulatory framework is taking place, with the full preservation of our own national heritage. The need to develop and implement a standard for flat hot-rolled broad-banded sheet, specialized and improved standards for hot-rolled bars and for cold-bent square and rectangular profiles, as well as the need to provide the official status of the standard for I-bars with parallel edges of the shelves are the main problematic issues in the part of the assortment normative base at the moment. Originality. In this publication, a theoretical estimation of modern changes in the current normative base of Ukraine, which regulates the issue of the range of steel rolled metal, is presented. In particular, 2 types of sheet metal, 5 types of shaped hot-rolled steel and 3 types of shaped cold-bent profiles, which are the most widely used for steel building structures, were analyzed. The main performance indicators of profiles according to old and new standards are calculated. Practical value. In the practical part of the completed review, changes in the cost structure of the main types of rolled steel over the past 5 years in Ukraine were estimated. The main problematic issues of the current assortment base of Ukraine are separately identified and practical recommendations for their elimination are provided.

Separation of the Icelandic Coastal Current from the Reykjanes Peninsula

The Icelandic Coastal Current (ICC) is a buoyant flow fueled by multiple rivers. Satellite observations during the October–November 2019 study period indicate the ICC often separates from the southwest tip of the Reykjanes Peninsula; it subsequently has large offshore excursion during west-southwestward winds. Results from a high-resolution realistic simulation exhibit this ICC behavior and provide detail on the associated currents and salinities. Sensitivity tests with simplified bathymetry, no winds, or no local buoyancy inputs are compared to the standard run to isolate contributions of those factors to flow separation. Analysis indicates that ICC separation occurs because the coast turns more tightly than the inertial radius; this behavior is consistent with inviscid theory. Partial flow deflection over the shelf expression of the Reykjanes Ridge and the widening shelf both increase ICC offshore excursion. The ICC is strongly influenced by the barotropic wind response to west-southwestward winds that includes a downshelf jet (flowing in the direction of Kelvin wave propagation) along the coast upshelf of the peninsula's tip where winds are downwelling-favorable, the downshelf extension of the jet that bends around the peninsula and progresses farther offshore with isobaths, a band of offshore and upshelf currents along the coast downshelf of the peninsula's tip, and surface flow aligned with Ekman transport located offshore beyond the downshelf jet. Similar wind-influence scenarios are discussed for other plumes. There are likely many such hotspots for offshore freshwater transport around the world.

Experimental investigation of effect of changing gap size in buckling restrained braces

This experimental study investigates the effect of changing the debonding gap between the core and the mortar filler on the global stability of BRBs using different cross-section restrained members. A total of eight mortar-filled BRBs were produced using a rectangular cross-section steel core and two different restraining members, a circular hollow cross-section (BRB-C series) and a square hollow cross-section (BRB-S series). In choosing the gap sizes, the gap limit formulas in the literature were considered. Not exceeding the limits of the gap, 2.8 mm, 5.6 mm, 8.4 mm, and 11.2 mm gaps were left as the multiples for the radius of inertia of the rectangular cross-section core in the BRBs. All specimens were subjected to displacement-controlled axial cyclic loading. As a result, failure modes, hysteretic performance, energy dissipation, and ductility were summarized and analysed for each specimen. The results showed that the specimens had a better structural performance with a 2.8-mm gap size, which is the radius of inertia of the core. Furthermore, the local buckling modes throughout the core increased in number as the size of the gap decreased, thus raising the members' axial load capacity and energy dissipation. It was concluded that the best structural behaviour of the tested series was provided with the smallest gap of 2.8 mm, better behaviour in energy dissipation may be obtained with smaller gap sizes. However, in this case, it is more likely to increase buckling at the gusset plates and cause local deformations with the end of the restraining members.

Kinematic and dynamic parameters of final stage of javelin throwing

Javelin throwing characterizes by creation of dynamic effort in shoulder-girdle during the process of movement. The emergence of excessive efforts in the joints of the parts of the body performing this sport exercise leads often to injury to the athlete. In this regard, the actual direction of training and competitive activity is the coordination and rationalization of movements in accordance with the principle of bionic adequacy of the system (in this case, “thrower – javelin”), the result of which is the maximum effectiveness of the exercise in the absence of traumatic effects of loads and movements. Biomechanical analysis of the final stage of javelin throwing was performed on the basis of 659 videos of competitive attempts. The results of measuring the angular displacements of the links of the body relative to each other and the common center of mass of the body in various nodal elements of motion are presented. In the work, the method of posture reference points of movements was used, which made it possible to distinguish starting and final movements, as well as a number of animated positions. Prediction of changes in the position of the body links taking into account the moments and radius of inertia of the links relative to the general center of mass of the thrower body allow us to take preventive measures to exclude deviations from the given optimal trajectory of the body parts. The determination of the ranges of angular positions in the joints of the parts of the body also contributes to the achievement of high sports results.

Increase in linear motion steadiness of tractor-trailers using stabilizing towing couplers

Travelling at higher speeds over any type of roads could disturb the stability of motion, which is manifested through lateral oscillations of the trailer in a horizontal plane – trailer wobbling. This research is aimed at building a mathematical model of tractor-trailer motion affected by the external action of lateral forces and estimating how efficient stabilizing couplers could be. A «double pendulum» design diagram is used to build the model. It is shown that the stability of motion is impacted at most by the ratio of the inertia radius (relative to the vertical axis passing through the center of gravity) to the base of the trailer, which depends on the type of cargo, its distribution within the trailer body, the heterogeneity of the cargo material and so on. It is demonstrated that the critical velocity of a trailer would increase when stabilizers are used. Changing the design of the trailer should also positively affect the stability of a tractor-trailer due to faster and more efficient damping of lateral oscillations impacting its movement.

A method to solve discrepancies of scale model in seismic shake table test of quayside container crane

ABSTRACT The quayside container crane (QCC) scale models for seismic simulation test on vibration tables are often high, and the model size and QCC structural size differences introduce discrepancies into the QCC model. In this investigation, discrepancies in the QCC scale model were solved using the similarity method for the sectional radius of inertia. Firstly, a governing equation for the beam section size was established. Secondly, a scale model was constructed for the shake table test, and the results were compared with the simulations. It is demonstrated that the experimental results were close to the simulations. Specifically, the acceleration, strain extreme values, and the time of occurrence were similar at different QCC points. This reveals that the shake table test of the QCC scale model can approximately reflect the prototype seismic response, which verifies the feasibility of the model design method.

Study of Fractal Characteristics of Individual Macromolecular Tangles

The fractal characteristics of individual macromolecular tangles of block and random copolymers are investigated. It was found that the dependence of the mass of macromolecules on the radius of inertia of a statistically significant sample is well described by the de Gennes equation with a fractal dimension of 5/3. It was established that the fine structure of the polymer coil also has a fractal nature. The fractal dimension inside the macromolecular coil changes significantly with distance from the center of mass.

Energy Method on Dynamic Buckling of Elastic Bar with Clamped-Free boundary Condition subjected to Impact of Rigid Mass

Considering the effect of stress wave, the dynamic buckling problem of elastic bar with clamped-free boundary condition subjected to impact of rigid mass is studied using the energy method. The Lagrange function is built. Both of the trial function that satisfy the boundary conditions and the Lagrange function are substituted into the second Lagrange equation. After that an analytical expression of critical impact velocity can be deduced. By the analytical expression, it is obtained that the critical impact velocity is related to the impact mass of rigid block, the critical length and the inertia radius of the bar. The result show that the critical velocity decreases by increasing the impact mass and critical length, while increases by the increasing of inertia radius.

Determination of geometric parameters for rational load-bearing unit of bridge cylindrical column pier

This paper deals with a bridge pier energywise uniform strength cylindrical steel-concrete load-bearing unit having a mesh case, which is made of an expanded metal mesh, as the most rational and the least resource-demanding one, using the nonwaste technology. The rational parameter selection method, which guarantees cross section uniform strength for the suggested load-bearing unit, is provided. The concrete core of the given element is a hollow cylindrical element that varies in height and whose centre of gravity coincides with an external loading point for any horizontal cross section. In addition to uniform strength, the hollow enables you to control the centre of gravity of the given complicated compound cross section of a cylindrical steel-concrete load-bearing unit. The calculation method to determine the main geometric parameters of the uniform strength load-bearing unit of a bridge cylindrical column pier having the lateral cross section area that varies in height is provided. The geometric parameters are the centre of gravity and its coordinates, central inertia moments and the radius of inertia. To exclude an impact of random eccentricity on a complicated compound cross section of a pier uniform strength steel-concrete load-bearing unit, the method to design a cross section core is provided.

ИССЛЕДОВАНИЕ ОБЛАСТИ ЭФФЕКТИВНОГО ПРИМЕНЕНИЯ СТАЛЬНЫХ КОЛОНН

The article sets the task of determining the area of effective application of solid and through columns. The parametric optimization method is used as a research method. The accepted optimality criterion includes the cost of steel, the cost of column manufacturing and the cost of applying corrosion protection. The main parameters affecting the intensity of metal and cost of the column are the load, the calculated length and the radius of inertia of the section. In the study, the type of cross-section of the column is adopted unchanged, in the form of an I-beam (is a limitation); the load and length of the column are taken as variable parameters. The design scheme of the structure is a centrally compressed column with hinged fastening of the base and the head. According to the regulatory conditions of stability and ultimate flexibility, the required cross-sectional area for each value of the variable parameter is determined. Charts with selected areas of optimal application are compiled; it helps the design engineer to choose between a solid or through section of the column, depending on its actual load and length.

Galerkin Analysis of Effect of Dead Load on Natural Frequencies of Box Beam

Based on Hamilton’s principle, a nonlinear differential equation considering the effect of dead loads is formulated for box beams. By using Galerkin method, the effect of dead load on the natural frequencies of box beams with various restraint conditions being simply supported, fixed at both ends, cantilevered and fixed at one end and simply supported at the other end is studied. The effects of major physical parameters, including the magnitude of dead load, sectional inertia moment and inertia radius, span length, and restraint conditions are discussed, and the natural frequencies are presented for these box beams, with the nonlinear effect of dead load taken into account. The results show that the deterrent effect of dead loads has significant effect on the increase of the natural frequencies of box beams. It is further observed that this behavior is more apparent at lower-order natural frequencies; the varying deterrent effect of dead loads relates to the stiffness of structures and is more significant for more flexible structures.

Analysis for wave power capture capacity of two interconnected floats in regular waves

The most representative of raft-type wave energy converters (WECs) is one composed of two interconnected floats, which uses the relative rotation between the floats to drive a Power Take-Off (PTO) system, achieving power capture from ocean waves. This paper presents a fundamental investigation into the wave power capture capacity of two interconnected floats with arbitrary float length. Linear hydrodynamics of the interconnected floats and a linear PTO system are employed, which enables us to carry out a frequency-domain analysis. Analytical formulas are derived of an optimized PTO damping and PTO stiffness/inertia for maximizing wave energy conversion in regular waves with/without consideration of relative rotary motion constraints due to the restraints of pump stroke or/and collision problem between the floats. The analytical model is then employed to examine the influence of fore-and-aft float length ratio, PTO system and float rotary inertia radius on the power capture capability of the two interconnected floats. It is concluded that for general wave conditions and specified total float length, two interconnected floats with the fore one properly shorter than the aft one possess high capacity in power absorption.

Development of the method for estimating the inertia radius relative to the vertical axis of the car

Development of the method for estimating the inertia radius relative to the vertical axis of the car

Suppression of Baroclinic Instabilities in Buoyancy-Driven Flow over Sloping Bathymetry

AbstractBaroclinic instabilities are ubiquitous in many types of geostrophic flow; however, they are seldom observed in river plumes despite strong lateral density gradients within the plume front. Supported by results from a realistic numerical simulation of the Mississippi–Atchafalaya River plume, idealized numerical simulations of buoyancy-driven flow are used to investigate baroclinic instabilities in buoyancy-driven flow over a sloping bottom. The parameter space is defined by the slope Burger number S = Nf−1α, where N is the buoyancy frequency, f is the Coriolis parameter, and α is the bottom slope, and the Richardson number Ri = N2f2M−4, where M2 = |∇Hb| is the magnitude of the lateral buoyancy gradients. Instabilities only form in a subset of the simulations, with the criterion that SH ≡ SRi−1/2 = Uf−1W−1 = M2f−2α 0.2, where U is a horizontal velocity scale and SH is a new parameter named the horizontal slope Burger number. Suppression of instability formation for certain flow conditions contrasts linear stability theory, which predicts that all flow configurations will be subject to instabilities. The instability growth rate estimated in the nonlinear 3D model is proportional to ωImaxS−1/2, where ωImax is the dimensional growth rate predicted by linear instability theory, indicating that bottom slope inhibits instability growth beyond that predicted by linear theory. The constraint SH 0.2 implies a relationship between the inertial radius Li = Uf−1 and the plume width W. Instabilities may not form when 5Li > W; that is, the plume is too narrow for the eddies to fit.

Maximum Wave Energy Conversion by Two Interconnected Floaters

Interconnected floaters could use relative rotations around connection joints to drive a power take-off (PTO) system, such that the ocean wave energy can be converted into a useful energy. In this paper, our attention is on the PTO optimization for the interconnected floaters. A fully linear dynamic system, including the linear hydrodynamics of the interconnected floaters and a linear PTO system, is considered. Under assumptions of linear theory, we present a mathematical model for evaluating the maximum wave energy conversion of two interconnected floaters based on the three-dimensional wave radiation–diffraction theory. The model is validated by comparison of the present results with the published data, and there is a good agreement. The model can be employed to calculate the maximum power absorbed by the interconnected floaters under motion constraints due to the restraints of pump stroke or/and collision problem between the floaters. The influence of wave frequency, PTO system, floater rotary inertia radius, and motion constraints on the power capture capability of the two interconnected floaters is also examined. It can be concluded that enlarging the rotary inertia of each floater by using mass nonuniform distribution can be seen as an alternative way of adding PTO inertia. The maximum relative power capture width of the two interconnected floaters with optimized PTO system under constraints is much smaller than that without any motion constraints for long waves.

Dynamics of a body sliding on a rough plane and supported at three points

This paper is concerned with the problem of a rigid body (tripod) moving with three points in contact with a horizontal plane under the action of dry friction forces. It is shown that the regime of asymptotic motion (final dynamics) of the tripod can be pure rotation, pure sliding, or sliding and rotation can cease simultaneously, which is determined by the position of the tripod?s supports relative to the radius of inertia. In addition, the dependence of the trajectory of the center of mass on the system parameters is investigated. A comparison is made with the well-known theoretical and experimental studies on the motion of bodies with a flat base.

Моделирование взаимодействия оксида кремния с дифенольными производными. Радиус инерции системы

Моделирование взаимодействия оксида кремния с дифенольными производными. Радиус инерции системы

Flexural vibrations of a rod of variable stiffness and distributed mass

A general approach to constructing mathematical models of the transverse vibrations of structures for different dynamic forces is considered. The variable flexural stiffness and the distributed mass are taken into account for the case when their ratio is expressed by a quadratic dependence on the dimensionless radius of inertia of the cross section. The free flexural vibrations and dynamic loads in an elastic rod, modelled by the structure of a lattice tower, are considered as an example. The effect of the model parameters on the value of the first natural frequency is investigated taking into account the presence of an inertial load. Expressions are obtained for the dynamic coefficients when the load is suddenly applied.

Monte Carlo properties of the hydrocarbon chains of phospholipid molecules

Properties of 65 chain hydrocarbon molecules in the unperturbed state are investigated using the Monte Carlo method at temperatures of 293, 303, and 313 K. Chains with the general structure CH3-(CH2)a-(CH=CH-CH2)d-(CH2)b-CH3 are considered. The number of carbon atoms in a skeleton N = 16, 18, 20, and 22; the number of cis-double bonds d = 0, 1, ..., 6. Conformations are generated with continuous varying of the angles of internal rotation around simple C-C bonds in the range of 0°–360°, the interdependence of each three angles along the chain is allowed for, and essential sampling is performed. Different properties of molecules are considered: the average maximum projections of hydrocarbon chains on their main axes of inertia, average squares of the radii of inertia, and relative fluctuations in the squares of the radii of inertia. The dependence of the calculated characteristics on the structural parameters of the chains is investigated.