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Showing papers by "Congrès International d'Architecture Moderne published in 2015"


Journal ArticleDOI
TL;DR: In this article, a review comprehensively describes the applications of microwave assisted extraction (MAE) in the past six years for the determination of the main families of emerging organic pollutants in the environment.
Abstract: Two of the main topics of growing concern in analytical chemistry are the development of green analytical methods and the determination of emerging pollutants. One of the well-established green extraction techniques is microwave-assisted extraction (MAE). After giving a brief description of MAE principles, the present review comprehensively describes the applications of MAE in the past six years for the determination of the main families of emerging organic pollutants in the environment. Compared to other extraction techniques, MAE offers many advantages, such as great reductions in extraction time and solvent consumption, as well as the possibility of performing multiple extractions, thereby increasing sample throughput. From a technological point of view, most future application areas are likely to focus on improving the flexibility of recently introduced sequential systems with the capacity to control conditions in each extraction vessel.

50 citations


Journal ArticleDOI
TL;DR: Results showed that 65% and 39% of the total FB1 and FB2 contents in silage were due to hidden fumonisins, and the use of inoculant had a significant effect on the stability of hidden and totalFB1 at the two harvest dates.

28 citations


Journal ArticleDOI
TL;DR: In this paper, the authors analyzed convective heat transfer and fluid flow characteristics of nanofluid in a two-dimensional square cavity under different combinations of thermophysical models of nanophotonics.
Abstract: The present study analyzed convective heat transfer and fluid flow characteristics of nanofluid in a two-dimensional square cavity under different combinations of thermophysical models of nanofluids. The right vertical wall temperature is varying linearly with height and the left wall is maintained at low temperature whereas the horizontal walls are adiabatic. Finite volume method is used to solve the governing equations. Two models are considered to calculate the effective thermal conductivity of the nanofluid and four models are considered to calculate the effective viscosity of the nanofluid. Numerical solutions are carried out for different combinations of effective viscosity and effective thermal conductivity models with different volume fractions of nanoparticles and Rayleigh numbers. It is found that the heat transfer rate increases for Models M1 and M3 on increasing the volume fraction of the nanofluid, whereas heat transfer rate decreases for Model M4 on increasing the volume fraction of the nanoparticle. The difference among the effective dynamic viscosity models of nanofluid plays an important role here such that the average Nusselt number demonstrates an increasing or decreasing trend with the concentration of nanoparticle.

14 citations


Journal ArticleDOI
TL;DR: In this paper, the formation of acoustic fluctuations in the half-space over a surface which contains an embedded fluctuating finite-size sink is considered on the basis of the numerical solution of the unsteady Reynolds equations.
Abstract: Free turbulent jets produce disturbances in the ambient medium which at a certain distance from the jet are perceived as sound waves. These disturbances are due to unsteady fluctuating motion of the medium in the jet flow (intermittance). The origin of the acoustic disturbances can be attributed to turbulence intermittance. Due to lowered pressure in the movable dynamic inhomogeneities of the turbulent fluid, they induce air ejection by the jet, which turns out to be fluctuating in nature, since the turbulent fluid flow is unsteady. The proposed mechanism of the generation of acoustic disturbances accompanying turbulent jet propagation is verified in numerical and experimental studies; in particular, the formation of acoustic fluctuations in the half-space over a surface which contains an embedded fluctuating finite-size sink is considered on the basis of the numerical solution of the unsteady Reynolds equations. From the results of the numerical experiment performed using large eddy simulation the fluctuating characteristics of the flow in a swirling jet and the direction of the disturbance energy flux in the ambient medium are determined. An experimental investigation of the disturbances produced by a strongly swirling jet is also carried out.

8 citations


Journal ArticleDOI
30 Jan 2015
TL;DR: An efficient implementation of the lattice Boltzmann method (LBM) for the numerical simulation of the propagation of long ocean waves (e.g. tsunami) based on the nonlinear shallow water (NSW) wave equation is presented in this article.
Abstract: An efficient implementation of the lattice Boltzmann method (LBM) for the numerical simulation of the propagation of long ocean waves (e.g. tsunami), based on the nonlinear shallow water (NSW) wave equation is presented. The LBM is an alternative numerical procedure for the description of incompressible hydrodynamics and has the potential to serve as an efficient solver for incompressible flows in complex geometries. This work proposes the NSW equations for the irrotational surface waves in the case of complex bottom elevation. In recent time, equation involving shallow water is the current norm in modelling tsunami operations which include the propagation zone estimation. Several test-cases are presented to verify our model. Some implications to tsunami wave modelling are also discussed. Numerical results are found to be in excellent agreement with theory.

7 citations


Journal ArticleDOI
TL;DR: In this paper, the effect of synthetic jets on separation flow in an S-shaped diffuser is numerically investigated using a high-resolution RANS/ILES method and the results of a parametric investigation of the regime parameters of the synthetic jets and the Reynolds number and the temperature at the diffuser entry on the synthetic jet efficiency are presented.
Abstract: Synthetic jets are a promising means of the active control of internal flows in units of turbojet (TJ) engines. They reduce or eliminate separation zones which can arise in flows in transition ducts between engine elements and diminish the nonuniformity in the parameter distributions at their exits. This becomes actual for aircraft TJs in view of the tendency to reduce the dimensions of adapting diffusers between engine elements. In this study, the effect of synthetic jets on separation flow in an S-shaped diffuser is numerically investigated using a high-resolution RANS/ILES method. The results of a parametric investigation of the effect of the regime parameters of the synthetic jets and the Reynolds number and the temperature at the diffuser entry on the synthetic jet efficiency are presented.

6 citations


Journal ArticleDOI
TL;DR: Simulated annealing routing method with Dijkstra's shortest path algorithm to provide the best path for each connection if it exists showed that by accepting some uphill movements based on Boltzmann probability function led to better results and yield to lower energy level, suggesting the technique is suitable for adoption into real problem.
Abstract: In an automatic design process for very large scale integration/printed circuit board (VLSI/PCB), routing problem is one of the most important and crucial part after components placement phase. This process is notoriously difficult, and a problem consists of a set of two-pin nets, is known to be NP-complete. In this problem, we considered a rectangular mesh network with all the location for blocks with pins on the boundaries and obstacles is predefined. Given a set of two-pin nets, our goal is to establish connections in the network by avoiding all the obstacles while satisfying the design rules. In this paper, we are using simulated annealing routing method with Dijkstra's shortest path algorithm to provide the best path for each connection if it exists. The simulation results showed that by accepting some uphill movements based on Boltzmann probability function led to better results and yield to lower energy level. This suggests the technique is suitable for adoption into real problem. © 2014 Noraziah Adzhar and Shaharuddin Salleh.

4 citations


Journal ArticleDOI
TL;DR: This paper addresses a directed-weighted cyclic graph and proposes an efficient graph-mapping concept, called DCGSimplify, to reduce the graph onto directed acyclic graph.
Abstract: The scheduling and mapping of task graph to processors is considered to be the most crucial NP-complete in parallel and distributed computing systems. In this paper, the theoretical graph application using matching is presented to assign a number of tasks onto two processors. This paper addresses a directed-weighted cyclic graph. The effort is to reduce the graph onto directed acyclic graph. A co-comparability graph is presented in order to assign the task onto two processors. Combining several innovative techniques lead to an efficient graph-mapping concept, called DCGSimplify. Our simulation model found that the proposed techniques and algorithms are easy to be implemented.

4 citations


Proceedings ArticleDOI
14 Dec 2015
TL;DR: In this article, a fixed point method (FPM) was proposed to solve SVFI-2 and a few theorems and a new algorithm was introduced, supported by numerical examples and simulations using Matlab.
Abstract: In this paper, we consider the system of Volterra-Fredholm integral equations of the second kind (SVFI-2). We propose fixed point method (FPM) to solve SVFI-2. In addition, a few theorems and new algorithm is introduced. They are supported by numerical examples and simulations using Matlab. The results are reasonably good when compared with the exact solutions.

3 citations


Proceedings ArticleDOI
14 Dec 2015
TL;DR: In this article, boundary integral equations for Ahlfors map of bounded multiply connected regions are derived, which have the potential to be useful in computing the zeros of Ahflors map.
Abstract: The Ahlfors map of an n–connected region is a branched n–to–one map from the region onto the unit disk. In this paper we derived new boundary integral equations for Ahlfors map of bounded multiply connected regions. One of them has the potential to be useful in computing the zeros of Ahlfors map. The kernels of these boundary integral equations are the generalized Neumann kernel, adjoint Neumann kernel, Neumann-type kernel and Kerzman-Stein kernel. These integral equations are constructed from a non-homogeneous boundary relationship satisfied by an analytic function on multiply connected regions.

3 citations


Journal ArticleDOI
04 Sep 2015-Age
TL;DR: The results do not confirm the association found in previous studies between longevity and THO1 and CSF1PO loci, but they suggest that the genomic portrait of the human longevity is far complex and probably shaped by a high number of genomic loci.
Abstract: Life span is a complex and multifactorial trait, which is shaped by genetic, epigenetic, environmental, and stochastic factors The possibility that highly hypervariable short tandem repeats (STRs) associated with longevity has been largely explored by comparing the genotypic pools of long lived and younger individuals, but results so far have been contradictory In view of these contradictory findings, the present study aims to investigate whether HUMTHO1 and HUMCSF1PO STRs, previously associated with longevity, exert a role as a modulator of life expectancy, as well as to assess the extent to which other autosomal STR markers are associated with human longevity in population from northern Spain To that end, 21 autosomal microsatellite markers have been studied in 304 nonagenarian individuals (more than 90 years old) and 516 younger controls of European descent Our results do not confirm the association found in previous studies between longevity and THO1 and CSF1PO loci However, significant association between longevity and autosomal STR markers D12S391, D22S1045, and DS441 was observed Even more, when we compared allelic frequency distribution of the 21 STR markers between cases and controls, we found that 6 out of the 21 STRs studied showed different allelic frequencies, thus suggesting that the genomic portrait of the human longevity is far complex and probably shaped by a high number of genomic loci

Proceedings ArticleDOI
10 Mar 2015
TL;DR: In this paper, a linear birth and death with immigration and emigration (BIDE) process to stochastic differential equation (SDE) model was discussed and the exact solution, mean and variance function of BIDE process was found.
Abstract: This paper discusses on linear birth and death with immigration and emigration (BIDE) process to stochastic differential equation (SDE) model. Forward Kolmogorov equation in continuous time Markov chain (CTMC) with a central-difference approximation was used to find Fokker-Planckequation corresponding to a diffusion process having the stochastic differential equation of BIDE process. The exact solution, mean and variance function of BIDE process was found.

Proceedings ArticleDOI
12 Aug 2015
TL;DR: In this article, the effect of rotor clocking on gas-dynamic characteristics of a high-loaded two-stage compressor simulating the first two stages of HPC for an advanced engine was investigated.
Abstract: In recent years, a number of studies in Russia and abroad was completed with the aim of decreasing pressure fluctuations and losses in blade cascades by controlling the unsteady interactions of blade rows (known as “clocking effect”) [1–4]. Tests of individual stages demonstrated that the clocking effect is responsible for 1.5–2.0% in efficiency and 50% in pressure fluctuations [5]. This paper presents the results of experimental and theoretical studies of the clocking effect on gas-dynamic characteristics of a high-loaded two-stage compressor simulating the first two stages of HPC for an advanced engine. The compressor is designed with the help of up-to-date 1D, 2D and 3D direct and inverse problem solutions and distinguished by high aerodynamic loads of stages with πk=3.7 total pressure ratio, 17% stall margin and 88% adiabatic efficiency at Ncor=88% rotational speed that was demonstrated experimentally [6].The compressor was tested at CIAM’s C-3 test facility in the assembly with d=0.5, 0.75, 1.0-mm tip clearance in both rotors (relative clearance in first stage 4.6·10−3; 6.9·10−3; 9.2·10−3 and relative clearance in second stage 9.1·10−3; 13.7·10−3; 18.3·10−3). When tested, clocking effects were checked up for separate and simultaneous changes in clocking positions of stator and rotor blade rows. Indications of a blade tip-timing system and pressure pulsation sensors were used as experimental data. Earlier, it was shown that physics of the rotor clocking is a wake interaction which modifies the behavior of a boundary layer in Rotor 2 blades. This work studies the mechanism of rotor clocking in combination with changes in angular position of Rotor 2 blades due to interactions with Rotor 1 wakes. Tests showed that changes in the clocking position of the rotor with a multiple number of Rotor 1 and Rotor 2 blades affected the static position of Rotor 2 blades causing re-position of the blades depending on the rotor clocking-position. To confirm this result, 3D unsteady aerodynamic calculation was completed with the help of NUMECA software package simulating one of the test points. This work presents the calculated and experimental data showing that vortex wakes from Rotor 1 blades extend downstream, reach Rotor 2 and cause a variable aerodynamic load and a variable blade pitch.Copyright © 2015 by ASME

Book ChapterDOI
01 Jan 2015
TL;DR: In this paper, an integrated benchmarking model is developed combining internal and external best practices and continuous improvement tools for oil and gas production companies, based on the vast knowledge and experience available within the performance management systems of one of the world's largest O&G production companies.
Abstract: Contrary to traditional management style, where new managers would introduce immediate drastic changes in an attempt to create short-term impact, more contemporary performance management philosophies rely on embracing and further developing existing internal practices and operating cultures toward world class. Building on the vast knowledge and experience available within the performance management systems of one of the world’s largest oil and gas production companies, an Integrated Benchmarking model is developed combining internal and external best practices and continuous improvement tools.

Proceedings ArticleDOI
01 Jan 2015
TL;DR: A genetic-based scheduling algorithm is proposed to solve the Priority-based Target Coverage (PTC) problem, which has been proven to be an NP-complete problem.
Abstract: Maximizing the network lifetime is one important factor in covering a set of targets in directional sensor networks (DSNs). The targets may take time to be located, and a good tracking management system is necessary to locate them. Target coverage problem arises due to limitation in the sensing angle and battery power of directional sensors. The problem becomes more challenging when the targets have different coverage quality requirements. In the present study, this problem is referred to as Priority-based Target Coverage (PTC) that has been proven to be an NP-complete problem. As sensors are often deployed densely, a promising solution to this problem is the use of scheduling technique through which the sensors are partitioned into several cover sets, then the cover sets are activated successively. In this paper, we propose a genetic-based scheduling algorithm to solve the problem. In order to examine the impact of different factors on the size of the resulting subset, three different experiments were performed to test the effectiveness of our algorithm. The results demonstrated that the proposed algorithm was able to contribute to solving the problem significantly.

Journal ArticleDOI
TL;DR: In this article, the effect of the Mach number and temperature at the nozzle exit on the flow features, turbulent fluctuations of the velocity, the static pressure, and the temperature, together with the overall noise level is analyzed for all the jets considered.
Abstract: The flow, turbulence, and noise parameters of cold and hot jets flowing out of nozzles of different types at subsonic and supersonic velocities are calculated using the high-resolution RANS/ILES method. The effect of the Mach number and the temperature at the nozzle exit on the flow features, the turbulent fluctuations of the velocity, the static pressure, and the temperature, together with the overall noise level is analyzed for all the jets considered. The accuracy of the calculations is confirmed by means of comparing with the available experimental data concerning certain parameters.

Journal Article
TL;DR: In this article, the uncontrolled environmental factors are perturbed into the growth rate deceleration factor of the Gompertzian deterministic model, thus leading to stochastic differential equations of GOMP with time delay.
Abstract: In this paper, the uncontrolled environmental factors are perturbed into the growth rate deceleration factor of the Gompertzian deterministic model. The growth process under Gompertz’s law is considered, thus lead to stochastic differential equations of Gompertzian with time delay. The Gompertzian deterministic model has proven to fit well with the clinical data of cancerous growth, however the performance of stochastic model towards clinical data is yet to be confirmed. The prediction quality of stochastic model is evaluated by comparing the simulated results with the clinical data of cervical cancer growth. The parameter estimation of stochastic models is computed by using simulated maximum likelihood method. 4-stage stochastic Runge-Kutta is applied to simulate the solution of stochastic model. Low values of root mean-square error (RMSE) of Gompertzian model with random effect indicate good fits.

Proceedings ArticleDOI
15 May 2015
TL;DR: In this article, a 2-stage stochastic runge-kutta (SRK2) method was proposed to approximate the solution of SDDEs with a constant time lag, r > 0.
Abstract: This paper proposes a newly developed one-step derivative-free method, that is 2-stage stochastic Runge-Kutta (SRK2) to approximate the solution of stochastic delay differential equations (SDDEs) with a constant time lag, r > 0. General formulation of stochastic Runge-Kutta for SDDEs is introduced and Stratonovich Taylor series expansion for numerical solution of SRK2 is presented. Local truncation error of SRK2 is measured by comparing the Stratonovich Taylor expansion of the exact solution with the computed solution. Numerical experiment is performed to assure the validity of the method in simulating the strong solution of SDDEs.

Proceedings ArticleDOI
22 Oct 2015
TL;DR: In this article, the authors considered a two-particle Hamiltonian on the d-dimensional lattice ℤd and studied a family of operators h(k) appearing after the separation of the center of mass of a system of two particles depending on the values of the total quasimomentum k ∈ 𝕋d.
Abstract: We consider a two-particle Hamiltonian on the d-dimensional lattice ℤd. We study a family of operators h(k) appearing after the “separation of the center of mass” of a system of two particles depending on the values of the total quasimomentum k ∈ 𝕋d (where 𝕋d is a d-dimensional torus). The operator h(k) is represented via the operator h(0), 0 ∈ Td, and using this result we obtain estimates for the norm and for the side of the spectrum of the operator h(k), respectively, via the norm and the side of the spectrum of h(0) . We prove the absence of singular spectrum of h(k) for any fixed Td.

Book ChapterDOI
01 Jan 2015
TL;DR: A case study of an oil and gas production company, aiming to drive business performance based on best practice-based learning rather than compliance, shows how benchmarking can be effectively implemented to maintain continuous improvement as mentioned in this paper.
Abstract: Companies are continuously striving for world-class performance by use of various performance management tools and techniques. One such popular technique, proving effective in achieving best-in-class results, is benchmarking. A case study of an oil and gas production company, aiming to drive business performance based on best practice-based learning rather than compliance, shows how benchmarking can be effectively implemented to maintain continuous improvement. Benchmarking practice is assessed across a variety of different departments affecting operations, giving an insight into the diversity and complexities of implementing the practice yet paying attention on learning opportunities, while maintaining focus on the ultimate goal of achieving world-class performance.

Journal ArticleDOI
TL;DR: The results of an experimental investigation of the natural noise of flow past two versions of sound absorbing devices are presented in this article, based on the known theoretical studies and the numerical calculations of the turbulent boundary layer over a rough surface a method for describing the noise of the above-mentioned devices is developed.
Abstract: The results of an experimental investigation of the natural noise of flow past two versions of sound absorbing devices are presented. On the basis of the known theoretical studies and the numerical calculations of the turbulent boundary layer over a rough surface a method for describing the noise of the above-mentioned devices is developed. The tests made using large eddy simulation show good agreement between the calculated and experimental data.

Book ChapterDOI
01 Jan 2015
TL;DR: In this article, the experimental and theoretical foundations of computational methods for estimating both isothermal and non-isothermal cyclic durability of engineering structures have been discussed, and the possibility for summation of cyclic damage is demonstrated for evaluating durability of variable cycles associated with unsteady loading and heating or unstable material parameters.
Abstract: Cyclic durability of machine parts is related to material resistance against low cycle fatigue (LCF) under periodic (cyclic) loads and temperatures within the range from 10 to 104 cycles and above. This chapter deals with experimental and theoretical foundations of computational methods for estimating both isothermal and non-isothermal cyclic durability of engineering structures. Typical examples of material cyclic tests under varying loads and peculiarities of cyclic non-isothermal deformation diagrams are considered. In the last case, the heating and cooling half-cycles are not identical due to a difference in the occurrence of elastic and plastic zones. The role of material the so-called cyclic adaptability is emphasized. This phenomenon leads to cycle stabilization that ensures to a great extend of the long-term working capacity of machines. Stabilized cycles can be both simple and consisting of a set of half-cycles of different stress and temperature. It is shown that the number of cycles before LCF failure under arbitrary programs of periodic loading and heating can be calculated from Coffin–Manson’s curves by averaging plastic strain intensity magnitude over whole deformation process. Analysis of the factors influencing the thermal fatigue of machine parts coming from thermocyclic tests is presented along with efficient methods for calculating stresses and strains corresponding to synchronous non-isothermal cycles. The possibility for summation of cyclic damage is demonstrated for evaluating durability of variable cycles associated with unsteady loading and heating or unstable material parameters. It is shown that LCF can be evaluated using the normalized accumulated plastic strain related to its magnitude at failure. The absolute accumulated plastic strain (Odqvist’s parameter) at cyclic loading varies over a wide range and cannot be a criterion for cyclic damage accumulation and failure.

Book ChapterDOI
01 Jan 2015
TL;DR: In this article, an approach for evaluating critical parameters (stress, strain, temperature, and operation duration) for lateral buckling of rod elements with a straight and curvilinear axis under elastoplastic deformation and creep is presented.
Abstract: Non-isothermal loss of stability of machine and structure elements under uniform or varying external loads and temperatures is considered. Stability at elevated temperatures may depend on a certain critical temperature value along with critical values of stress and strain. Peculiarities of structure buckling under temperature stresses in case of constrained deformation are demonstrated. Approaches for evaluating critical parameters (stress, strain, temperature, and operation duration) are presented for lateral buckling of rod elements with a straight and curvilinear axis under elastoplastic deformation and creep. The loss of a cylindrical equilibrium form of a stretched rod due to increase of creep rate evolution is discussed. Loss of stability, caused by non-uniform heating of the bodies of various shapes, is analyzed. Nonlinear calculation of transition to a new equilibrium state caused by a temperature variation is studied in detail using von Mises modified truss.

Book ChapterDOI
01 Jan 2015
TL;DR: In this article, a general approach to computation analysis of unsteady elastoplastic deformations in machine parts and mechanical systems under non-isothermal loading, based on modern experimental data and theoretical developments is presented.
Abstract: A topic of this chapter is the general approach to computation analysis of unsteady elastoplastic deformations in machine parts and mechanical systems under non-isothermal loading, based on modern experimental data and theoretical developments. It is shown that widespread variants of theories of plasticity, including strain hardening model, enable satisfactory evaluation of the plastic strain rate, associated with transient processes, only provided that strains increase along an invariable direction. The theory of stabilized anisotropic hardening (SAH theory) developed over the last few decades is outlined. This theory takes into consideration loading history and material adaptability along with separation of stresses into so-called active and residual micro-stress parts. A comparison with numerous experimental results demonstrates efficiency of the SAH theory for calculating the plastic strain rate under sign-varying multi-axial proportional loading. An experimentally justified extension of the SAH theory proposed by the author for analyzing more elaborate case of non-proportional (out-of-phase) non-isothermal loading and conditionally named “the model of stabilized anisotropic-ray hardening” (the SARH theory) is described in detail. The theory starts from the concept of the evolvement of anisotropy deformation along a “hardening axis,” which is collinear to a varying vector of the aforementioned active stresses, and also relies on separation of residual micro-stresses into steady (isotropic) and unsteady (anisotropic) parts; in doing so, unsteady micro-stresses vary under rotation of the hardening axis. The constitutive relations written in the form of the projections of micro-stresses, plastic strains, and their increments onto this axis govern arbitrary non-isothermal deformations. A step-by-step procedure of numerical solution of a thermal plasticity problem using the SARH model is also described. Numerical examples illustrate the applicability of the proposed fairly simple model for restoring the plastic strain rate and direction of plastic strain observed for specimens loaded over a wide range of magnitudes and orientations of the stress vector. The possibility of estimating damage accumulation and failure conditions is addressed for general elastoplastic non-isothermal process. A brief survey of the publications (both in Russian and English) on the SAH theory of elastic plastic deformations of solids subject to sign-varying loading is presented.

Book ChapterDOI
01 Jan 2015
TL;DR: Rational methods for generation of probabilistic-statistical strength and durability margins of machine parts, using results of the limited scope of sampling tests, are proposed.
Abstract: Working capacity of machine parts in various possible operation conditions must be maintained by introduction of strength and durability margins (safety factors). These margins are necessary in view of possible random industrial deviations, unforeseen adverse combinations of loads, temperatures, and operating time at some regimes, and many other reasons. General principles for safety factor formation require analyzing the most probable ways for deviation of stresses, temperatures, and work duration or any other specific parameter, over its design value—on separateness or in aggregate with other ones. The possibility of creating a design of “equal strength” at non-isothermal loading is illustrated by the optimization of a turbomachine blade model non-uniformly heated along its length. The benefits of introducing a “weak link” that reaches destruction under overload before the entire system are discussed. It is shown that “equivalent” trials replicating the lifetime of the system can significantly accelerate the verification of the most stressed machine parts. The trials ensure a machine functioning with the same safety factors as under the work conditions, but during smaller duration. The cyclic durability margins for non-isothermal cyclic fatigue, taking into account influence of exposure at the maximum cycle temperature and asymmetric loading, are considered. Along with the evaluation of local strength and durability margins for the most stressed elements of a structure, computation methods, on a bearing ability of the structure “in whole,” are stated. Use of the determined safety factors is shown to be principally necessary for the reliable probabilistic estimation of details’ low-cycle fatigue (LCF). For this purpose, rational methods for generation of probabilistic-statistical strength and durability margins of machine parts, using results of the limited scope of sampling tests, are proposed.

Book ChapterDOI
01 Jan 2015
TL;DR: A vector theory of stabilized anisotropic-ray hardening (the SARH theory) of a material considering non-isothermal creep under arbitrary loadings, including non-proportional ones, is formulated in this paper.
Abstract: In this chapter, the most validated experimental data for creep and durability of structural materials subjected to unsteady loading and heating are presented. The effect of heredity and adaptability on the material deformation hardening under uni- and multi-axial stress states is demonstrated. A vector theory of stabilized anisotropic-ray hardening (the SARH theory) of a material considering non-isothermal creep under arbitrary loadings, including non-proportional ones, is formulated. The theory is based on the experimentally justified concept of directed and stabilized nature of creep deformation hardening. It develops the results of previous publications on the subject. The design model reveals prominent features of non-steady creep, such as increase in rate of strain development after repeated loadings, spatial variation of the strain rate evolution at rotation of the stress tensor with or without unloading, subsequent stabilizing of the creep rate along a new direction, complete or partial creep inhibition under unloading, and aftereffect. A quasi-steady version of the theory takes into consideration the overall effect of rapid variation of operating regimes on creep evolution.

01 Dec 2015
TL;DR: In this article, el presente trabajo is senalar y demostrar que la produccion arquitectonica de la vivienda unifamiliar de la primera mitad del siglo XX in la ciudad de Corrientes is el de observar arquaturías modernas in una ciuda no moderna.
Abstract: El objetivo del presente trabajo es senalar y demostrar que la produccion arquitectonica de la vivienda unifamiliar de la primera mitad del siglo XX en la ciudad de Corrientes es el de observar arquitecturas modernas en una ciudad no moderna. Asi, la modernidad arquitectonica de la vivienda unifamiliar correntina entendida como manifestacion cultural materializada, se manifiesta de manera poco autonoma y ligada a las fuerzas de la tradicion historico-urbana de la ciudad. Por otro lado, y en cuanto a los sistemas de produccion, se manifiestan a partir de cualidades diferenciadas de los ejemplos historicos a partir de la adopcion de la novedosa tecnologia del hormigon armado y de las formalizaciones emergentes de las esteticas de las vanguardias.

Book ChapterDOI
01 Jan 2015
TL;DR: In this article, the problems of the theory of thermal plasticity in which, under proportional change of stress tensor components, the plastic deformation increases at a loading and heating, and does not vary at unloading and cooling is considered.
Abstract: This chapter deals with the problems of the theory of thermal plasticity in which, under proportional change of stress tensor components, the plastic deformation increases at a loading and heating, and does not vary at unloading and cooling. The temperature range in which creep can be neglected is considered. Analysis of results of material tests under uni- and multi-axis stress at various temperatures shows that, with reference to the specified brand of the problems, non-isothermal variants of the theory of plastic flow and the deformation theory correctly enough present evolution of plastic deformations. The beginning of the plastic flow or its renewal after the intermediate unloading happens when the stress intensity reaches a generalized non-isothermal surface of yielding. Unlike an isothermal loading, the conditions and rate of plastic strain evolution depend on a relationship of rates of the temperature and stress intensity; in particular, plastic strains can increase under reduce of stresses, but increase of temperature. Rational methods of step-by-step calculation of elastoplastic deformations are stated in application to the non-isothermal loading. As the initial approach, the elastic solution is used at small plastic strains, and the solution for ideally plastic body—at major strains. Instances of such solutions are demonstrated. It is shown that the growth of temperatures at combined stress leads to diminish of a short-term carrying capacity of a structure because of the change of a material strength characteristics, while a role of temperature stresses induced by a non-uniform heating distinctly weakens when plastic strains considerably exceed the thermal expansion.

Book ChapterDOI
01 Jan 2015
TL;DR: In this paper, the authors discuss the effects of temperature variations on the properties of materials and constructions at elevated temperatures, including the effect of the material thermal extension on detail natural oscillation frequencies.
Abstract: The chapter contains information on the special problems of thermal integrity, which can be of interest for the readers aimed to gain deepened understanding about some peculiarities of materials’ and constructions’ behavior at elevated temperatures. For problems of non-isothermal dynamics (Sect. 12.1), it is shown that influence of the material thermal extension on detail natural oscillation frequencies with temperature increase can be different. Alteration of contact conditions between machine parts (for example, change negative clearances on tightness or on the contrary) and occurrence of the temperature stresses, especially in thin-walled structures, can change their rigidity and the frequency spectrum. A possibility of directional change of a body shape by serial variable heating of its separate body sections having various elastoplastic temperature-dependent mechanical properties is demonstrated in Sect. 12.2. This effect, used in a number of technological processes, is illustrated on simple examples. Though in the majority of practical thermal strength problems, the temperature state of a body is supposed known and not dependent on its stress–strain state, and for an explanation of some effects, it is necessary to address to the “coupled” theory of the thermoelasticity considering thermodynamic link of mechanical and thermal processes. The bases of this theory in rather simple treatment are stated in Sect. 12.3. The coupling effect is illustrated by calculations of energy dispersion during elastic vibrations and influence of convective heat exchange on material deformation at tensile trials. In Sect. 12.4, the fundamentals of the wave theory of thermal conductivity considering (unlike the classical theory) a finite speed of thermal stream and temperature propagation over a solid are briefly stated, and the influence of this factor on unsteady temperatures and stresses propagation at a heat shock on a semi-infinite body is shown.

Journal ArticleDOI
TL;DR: In this paper, the bifurcation of limit cycles at infinity for a class of homogeneous polynomial systems of degree four is examined and the conditions from the origin to be a centre and the highest degree fine focus results from the calculation of singular point values.
Abstract: In this paper the bifurcation of limit cycles at infinity for a class of homogeneous polynomial system of degree four is examined. This requires a problem for bifurcation of limit cycles at infinity be converted from the original system to the class of complex autonomous differential system. The evaluation of the conditions from the origin to be a centre and the highest degree fine focus results from the calculation of singular point values. A quartic system is constructed for which it can bifurcate with only one limit cycle at infinity when the normal parameters are constant.