bluuebunny/crossref_metadata_2025_split huggingface dataset:
Geometrically nonlinear forced vibrations of fully clamped multi-span beams carrying multiple masses and resting on a finite number of simple supports
Authors: Fakhreddine H , Adri A , Chajdi M , Rifai S , Benamar R 
Published: July 2019

Abstract
Geometrically nonlinear forced vibrations of fully clamped multi-span beams resting on multiple simple supports and carrying multiple masses may be encountered in many mechanical and civil engineering applications. The theoretical model developed here is based on the Euler-Bernoulli beam theory and the Von Karman geometrical non-linearity assumptions. Harmonic motion is assumed and the nonlinear beam transverse displacement function is expanded as a series of the linear modes, determined by solving first the linear problem. The discretised expressions for the beam total strain and kinetic energies are then derived, and by applying Hamilton’s principle, the problem is reduced to a nonlinear algebraic system solved using an approximate method (the so-called second formulation). The basic function contribution coefficients to the structure non-linear response function and the corresponding backbone curves giving the non-linear amplitude-frequency dependence is determined. Numerical results are given in the neighbourhood of the predominant nonlinear mode shape, based on the single mode approach, for a wide range of vibration amplitudes, showing the effect of the added masses and their locations, as well as the applied uniformly distributed harmonic force on its non-linear dynamic response.
Geometrically non-linear forced vibrations of fully clamped functionally graded beams with multi-cracks
resting on intermediate simple supports
Authors: Chajdi M , Fakhreddine H , Adri A , bikri K El , Benamar R 
Published: July 2019

Abstract
The objective of this work is to investigate the non-linear forced dynamic response at large vibration amplitudes of fully clamped functionally graded beams containing a multiple open edge cracks and resting on intermediate simple supports. The theoretical model is based on the Euler-Bernoulli beam theory and the crack rotational spring model. The functionally graded beam properties are supposed to vary continuously through the beam thickness. A homogenization procedure based on the neutral surface approach taking into account the presence of the crack is developed to reduce the problem examined to that of an equivalent isotropic homogeneous multi-cracked beam. In the non-linear analysis, harmonic motion is assumed and the discretized expressions for the beam total strain and kinetic energies are derived by applying Hamilton’s Principle, so as to reduce the problem to a non-linear algebraic system solved using an approximate explicit method previously applied to various non-linear structural vibration problems. Considering the forced vibration case, the non-linear frequency response functions are obtained numerically in the neighbourhood of the predominant non-linear mode shape using a single mode approach. The effects of crack, the beam material gradient and the applied harmonic force are presented and discussed.
Using the Finite Product Method for solving eigenvalue problems formulated in cylindrical coordinates
Authors: Ledet L S , Sorokin S V 
Published: July 2019

Abstract
Analysis of free/forced wave propagation in multi-layered structures and structures under heavy fluid loading constitute classical problems of fluid-structure interaction. These waveguides and many similar ones support infinitely many waves and in some cases e.g. at high-frequency excitations or in near-field analysis it is necessary to account for a large number of them. Finding the dispersion curves from these transcendental dispersion relations is not a trivial task due to their ill-conditioned/unstable nature as well as numerical algorithms ability to solve transcendental equations. These issues can, however, be circumvented by using the Finite Product Method (FPM). The FPM is generic and has been used to solve dispersion equations of homogeneous waveguides derived in Cartesian coordinates with sine/cosine functions. However, it is yet to be formulated in cylindrical coordinates when Bessel functions are involved in dispersion equations. We focus in this paper on extending the method to the cylindrical problems and compound waveguides illustrated here by a fluid-filled cylindrical shell. The great advantage of the FPM is that it reduces the transcendental dispersion equation to a polynomial one easily solved by numerical algorithms but more importantly it delivers only authentic roots of the dispersion equation i.e. no spurious roots as often encountered when using Taylor approximations etc.
A hysteretic absorber to mitigate vibrations of rail noise barriers
Authors: Basili M , Casini P , Morelli L , Vestroni F 
Published: July 2019

Abstract
Noise barriers for high-speed train lines are subject to strong vibrations due to fluid pressure generated by moving trains. The barriers, generally made of steel cantilever beams, suffer fatigue. For their safety, it is necessary to adopt more resistant solutions or reduce their vibration, as is applied in this study. Following the fundamental work by Den Hartog on viscoelastic tuned mass dampers, later contributions on vibration mitigation have shown a variety of phenomena exhibited by a primary structure connected to a nonlinear light attachment. Vibration reduction of the structure has been observed for selected characteristics of the attachment. Here, the use of a hysteretic absorber is exploited. The device, made of light mass on rubber elements, has the advantage of directly representing the elastic and damping elements. The Bouc-Wen model describes the absorber behavior and its parameters are determined by the experimental results. Due to the dependence of the nonlinear system response on the oscillation amplitude, an optimal tuning is adjusted. The system is calibrated to behave around the 1:1 internal resonance condition. Numerical and experimental results show that the absorber effectively reduces the amplitude and the number of vibration cycles.
A review on the current trends on computational modelling of masonry-infilled reinforced concrete frames
Authors: Shadlou M , Kashani M M 
Published: July 2019

Abstract
A review of methods applicable to the study of masonry-infilled reinforced concrete frames (MIRCF), consisting both traditional and advanced solutions, and located in seismic zones is presented in this research. Firstly, this research presents a brief discussion about the main challenges on modelling the RC frames, masonry infills and interaction between them for structures located in seismic zones. Then, simplified and sophisticated approaches, which are actually used or developed for modelling both RC frames and masonry infills recently, are discussed. The main available strategies including simplified methods, and sophisticated finite element solution are considered with regard to their realism, computer efficiency, data availability and real applicability to large structures.
Dynamic Behavior of Variable Cross-Section Offshore Wind Turbine with Flexible Foundation Using Finite Element Method
Authors: El Absawy Mostafa A. , Elnaggar Zakaria , Ibrahim Hesham H. 
Published: July 2019

Abstract
A Finite Element model for variable cross section offshore wind turbine with flexible foundation is developed to accurately determine the fundamental frequency of the tower-nacelle system. The tower is modeled using two-noded Euler beam element with two degrees of freedom, namely transverse displacement and rotation, and Hermite polynomial shape function. The governing equations are obtained using Euler-Lagrangian energy-based approach, including the effect of variable tower cross section and the nacelle mass. The soil-tower interaction is modeled by rotational and lateral springs at the lower end of the tower. Four offshore wind turbines were selected as case studies in terms of validation and comparison. The results of the current model, compared to those of an experimental, clearly show that it better simulates the dynamic behavior of the tower-nacelle system compared to those of the constant cross-section approximated models.
Semi Analytical Model for the Dynamic Behavior of Offshore Wind Turbine with Flexible Foundation
Authors: El Absawy Mostafa A. , Elnaggar Zakaria , Ibrahim Hesham H. 
Published: July 2019

Abstract
A new semi analytical formulation is developed which models the dynamic behavior of offshore wind turbine with variable cross section and flexible foundation. The wind turbine tower is modeled using Euler-Bernoulli beam model while the soil-tower interaction is modeled by rotational and lateral springs at the lower end of the tower. Recursive differential method is used to calculate natural frequencies which is found to be efficient in terms of accuracy as well as the computational cost. The predicted natural frequencies of the current proposed mathematical technique were validated and compared with those of two other analytical and experimental techniques, for four selected offshore wind turbines, and results were found to be in very good agreement. Furthermore, the results of the current model, which accurately models the variation of the cross section properties, were found to be in a better agreement with the experimental results compared to those of the constant cross-section approximation.
On the interest of a space-time regularization for reconstructing sparse excitation sources
Authors: Aucejo Mathieu , Smet Olivier De , Deü Jean-François 
Published: July 2019

Abstract
In time domain, force reconstruction problems are commonly solved from Tikhonov and LASSO regularizations. Practically, these approaches can lead to inaccurate reconstructions, if the sources to identify don’t share the same space-time characteristics or the corresponding force vector doesn’t exhibit the desired structure. To alleviate this potential drawback, we have recently introduced a multiplicative space-time regularization that allows exploiting one’s prior knowledge of the spatial distribution of the sources as well as their time history. In this contribution, the proposed regularization strategy is compared to the multiplicative Tikhonov and LASSO regularizations through an experimental application to point out the practical interest of exploiting simultaneously both spatial and temporal prior information in terms of quality and robustness of the reconstructed excitation sources.
An analytical model of transducer array arrangement for guided wave excitation and propagation on cylindrical structures
Authors: Niu X , Tee K F , Marques H R 
Published: July 2019

Abstract
Ultrasonic guided wave (GW) inspection is one of the non-destructive testing (NDT) techniques available for the engineering structures. Compared with other NDT techniques, guided waves can propagate a long distance with a relatively high sensitivity to defects in the structure. In order to increase the performance for pipe inspections to meet higher requirements under different conditions, the optimisation of piezoelectric transducer array design is still a need, as the technique is currently subject to a complex analysis due to wide number of guided wave modes generated. This can be done by optimising the transducer array design. In this paper, it is described an analytical mode of a set of piezoelectric transducer arrays upon torsional wave mode T(0,1) excitation in a tubular structure. The proposed analytical model for predicting signal propagation is validated by using finite element analysis in ABAQUS and three-dimensional laser vibrometer experiments for transducer array characterisations. The proposed analytical model works well and very fast for simulating transducer excitation and wave propagation along cylindrical structures. This will significantly reduce the complexity of guided wave analysis, enhancing effectively the structural health of structures and subsequently reducing the industry maintenance cost.
Normalisation of Paris agreement NDCs to enhance transparency and ambition
Authors: King Lewis C , van den Bergh Jeroen C J M 
Published: July 2019

Abstract
The Paris Agreement takes a bottom-up approach to tackling climate change with parties submitting pledges in the form of nationally determined contributions (NDCs). Studies show that the sum of these national pledges falls short of meeting the agreement’s 2 °C target. To explore this discrepancy, we analyse individual pledges and classify them into four categories. By doing so, a lack of consistency and transparency is highlighted, which we correct for by performing a normalisation that makes pledges directly comparable. This involves calculating changes in emissions by 2030, using data for the most recent base year of 2015. We find that pledges framed in terms of absolute emission reductions against historical base years generally produce the greatest ambition, with average emission reductions of 16% by 2030. Pledges defined as GDP intensity targets perform the worst with average emission increases of 61% by 2030. We propose that a normalisation procedure of the type as we develop becomes part of the NDC process. It will allow to not only increase the transparency of pledges for policymakers and wider society, but also promote more effective NDCs upon revision as is foreseen to happen every 5 years under the ‘ratcheting mechanism’ of the agreement.
Evidence, ideology, and the policy of community management in Africa
Authors: Whaley Luke , MacAllister Donald John , Bonsor Helen , Mwathunga Evance , Banda Sembeyawo , Katusiime Felece , Tadesse Yehualaeshet , Cleaver Frances , MacDonald Alan 
Published: July 2019

Abstract
This study examines the performance of the policy of community management for rural groundwater supply in Africa. Across the continent, policies that promote community management have dominated the rural water supply sector for decades. As a result, hundreds of thousands of village-level committees have been formed to manage community boreholes equipped with handpumps. With a significant proportion of these handpumps non-functional at any one time, increasing effort is targeted toward understanding the interacting social and physical determinants of this ‘hidden crisis’. We conducted a survey of community management arrangements across six hundred sites in rural Ethiopia, Malawi, and Uganda, examining the extent to which management capacity is related to borehole functionality whilst accounting for a range of contextual variables. The capacity of water management arrangements (WMAs) was assessed according to four dimensions: finance system; affordable maintenance and repair; decision making, rules, and leadership; and external support. The survey reveals that 73.3% of WMAs have medium or high capacity. However, we found no strong relationship between the capacity of the WMA and the functionality of the borehole. Of the four management dimensions, affordable maintenance and repair was the best predictor of borehole functionality. However, the capacity of this dimension was seen to be the lowest overall, with 61.9% of sites weak or non-existent. Our results provide very limited support for the policy of community management, and we suggest that evidence alone has not accounted for its persistence over decades. After a short historical analysis, we conclude that explanation for the endurance of this model can be found in the nexus between evidence, ideology, and policy. We argue that it is this same nexus that will likely ensure the popularity of community management for some time to come, despite new ideas and evidence to the contrary.
Estimation of extreme daily precipitation thermodynamic scaling using gridded satellite precipitation products over tropical land
Authors: Roca Rémy 
Published: July 2019

Abstract
This study explores the tropical land distribution of precipitation and its extremes focusing on the daily 1° × 1° scale. A common period of 5-year over the tropical belt (30°s–30°n) corresponding to more than 39 million data points, is used to highlight the robust (and non-robust) observed features. A set of 10 observational products is analyzed ranging from satellite only to rain gauges only products and various blended intermediates as well as a sub ensemble of satellite-based products relying upon microwave observations. Overall, the various datasets show a small diversity of response as far as tropical land mean precipitation is concerned. When sorted by surface temperature, the spread in mean rainfall is also well below 10% over a large span of the surface temperature regime. The consistency between the surface temperature and the extreme precipitation is further investigated by computing the thermodynamic scaling of daily precipitation extreme with surface temperature. The wet days’ 99.9th and 99th percentiles are considered and corresponds to ‘extreme’ extremes (∼110 mm d−1) and ‘moderate’ extremes (∼60 mm d−1), respectively. The analysis reveals three regimes over the 287–305 K 2 m temperature range. In the cold regime, 287–293 K, extremes exhibit no dependence to surface temperature while in the warm regime, 299–305 K, the extremes decrease with temperature as identified in previous studies. Over the 293–299 K regime, the scaling of the sub ensemble of satellite products is ∼5.2 K/% for the ‘extremes’ extremes and 5.0% for the ‘moderate’ extremes, and is robust throughout the sub ensemble. This analysis fills the regional gap of previous conventional data based studies and further confirms the Clausius–Clapeyron theoretical expectation for the tropical land regions.
Biofouling on water intakes and fight against them
Authors: Kalinichenko M. Ya. 
Published: July 2019

Abstract
Relevance of the research is caused by high costs of maintenance for Dreissena removal from water inlets of a water intake system.
In this regard, the article is directed to the development of the technology and the technological scheme of biofouling prevention on water intakes.
The main approach to this problem research is the development of the technology and the technological scheme of biofouling prevention on water intakes.
Waste gas treatment technology against dust in vortex apparatuses with closed water circulation
Authors: Mahotkin A. F. , Mahotkin I. A. , Starkova A. V. 
Published: July 2019

Abstract
This article covers the development results and manufacturing application of high technology of water scrubbing for waste gases against dust for environmental management of finely broken stone of limestone wastes burning in rotary kilns. The followings are obtained under production conditions firstly: current sanitary standards for gas cleaning, comprehensive utilization of trapped slurry and closed water circulation.
Purification of water sources from oil contamination by hydrophobic carbonate sludge
Authors: Nikolaeva L.A. , Khamzina D.A. 
Published: July 2019

Abstract
The paper presents laboratory and experimental studies on the purification of surface water sources from oil contamination by sorption material on the basis of production waste. Energy waste is a slurry of chemical water treatment, which is formed during liming and coagulation at the stage of preliminary purification of natural water. Based on the sludge, the hydrophobic sorption material “MGSM” was developed. The following requirements are imposed on the sorption materials that allow, at low costs, the most effective cleaning of the water surface from petroleum products: hydrophobicity, oil capacity, buoyancy, ease of utilization from the water surface, efficient work in a different temperature range, resistance to water disruption, non-toxicity, optimal price. The material obtained has these requirements. The technical characteristics of the developed sorption material were determined: oil capacity, wetting contact angle, an express analysis of the quality of the aqueous extract of the hydrophobic sorbent developed for the acute lethal toxicity of fish of the Poecilliareticulata Pet. and crustaceans Daphniamagna Str. A technological scheme for utilization of oil-contaminated hydrophobic sorption material as a secondary energy resource in industrial enterprises is proposed, a calculation of the volume of air and combustion products during its combustion, calculation of harmful emissions, thermal calculation, and prevented environmental damage.
Technology of utilization of liquid wastes generated during the preparation of main oil pipelines to transport diesel fuel with produce cheap steam or warm heat carrier
Authors: Pavlov G.I. , Sitnikov O.R. , Khakimzyanova Y.I. , Otradnova V.A. 
Published: July 2019

Abstract
The existing technology of cleaning internal surfaces of oil pipelines from oil residues and solid sediments leads to the formation of a large volume of liquid hydrocarbons contaminated with mechanical particles and various resins. Currently, in the oil industry, mobile steam generator plants of PPU 1600/100 are used to steal sections of oil pipelines. The standard nozzle burner used in the PPU 1600/100 does not allow to burn effectively liquid waste similar to contaminated liquid hydrocarbons formed during the cleaning of the inner walls of the main oil pipelines. The article presents the results of operation of steam generator sets of PPU 1600/100 with a nozzle-free burner device VGU-1.
Influence of wheat husk modification on sorption properties of heavy metal ions
Authors: Politaeva N. , Smyatskaya Y. , Safonova E. , Barsukova N. 
Published: July 2019

Abstract
This article focuses on sorption properties of sorbents based on modified wheat husk. It presents kinetic characteristics and isotherms of sorbents sorption. We studied the influence of pH environment on the efficiency of wastewater treatment from heavy metal ions.
On-line express-analyzer and method of water monitoring on the base of proton magnetic resonance
Authors: Kashaev R.S. , Kozelkov O.V. 
Published: July 2019

Annotation
Described flow analyzer of water on the presence of impurities, based on proton magnetic resonance - PMRA. Presented common appearance and construction, mode of operation PMR-analyzer. Presented equations of received dependences for determination of salts and oil impurities in water. Proposed structure and technologic schemes for removal of impurities from water in the installation with rotating magnetic and nonuniform electric field with continual online control of water purity bu flow PMR-analyzer.
Using Redox potential in water quality assessment of energy facilities
Authors: Gordeeva M E , Kalayda M L 
Published: July 2019

Abstract
The question of natural water quality for a long time has wondered researchers and ordinary citizens. Cities expanded, population increases, it leads to a deterioration in natural waters by sanitary-chemical and microbiological indicators. In this regard, this article concerns the question of the monitoring of physicochemical indicators and introduction the new indicator – Redox potential (Eh). Dynamics of Eh changes in the rivers of the Republic of Tatarstan and surrounding areas as well as natural and artificial water reservoirs, including basin-coolers of energy facilities are researched in this article. Conducted full-size data and experiments made it possible to establish the Eh sensitivity in relation to the pH. In the article has showed the possibility of introducing Eh indicator into the assessment of water quality on the assumption of further consideration and detail.