bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonlinear rocking dynamics of pre-tensioned single rigid blocks under harmonic base excitation
Authors: Ahmadi E , Kashani M M 
Published: July 2019

Abstract
The rocking mechanism has been widely recognized as a beneficial technique to reduce structural damage arising from lateral excitations particularly earthquake loading, and hence, segmental pre-tensioned bridge piers have been recently emerged due to their self-centring property accompanied by accelerated construction of such structures. Hence, this study formulates the rocking dynamics of tied pre-tensioned single rigid blocks as an initial study for better understanding of dynamics of segmental pre-tensioned bridge piers. The nonlinear equation of rocking motion is then numerically solved under different range of base harmonic excitations. To achieve this, the rocking initiation condition is considered to determine initial conditions of rocking motion, an implicit solution is adopted to solve the equation of rocking motion and determine rocking response. Finally, a study is performed on a specific composite tied block to investigate effects of geometry and initial pre-tensioning force of the cable on the dynamic behaviour of the block. This study can find use in better understanding of segmental pre-tensioned columns.
Numerical computation of the spatial decaying wave characteristics for the design of locally resonant acoustic metamaterials
Authors: Miksch M , Perez Ramirez J D , Müller G 
Published: July 2019

Abstract
In structural dynamics, periodic resonant inclusions are widely used to improve the vibro-acoustic properties of lightweight structures. Depending on the design of these inclusions, the wave propagation in the structure is modified for specific frequency ranges and stop bands, where in theory no free wave propagation is possible, can be generated. The Wave Finite Element Method (WFEM) investigates the wave propagation in periodic structures based on a Finite Element (FE) model of a single unit cell. Using the direct approach of the WFEM, it is possible to depict the wave characteristics in the frequency range of the resonant frequency of the inclusions. Consequently, a spatial decay for the different wave types can be determined in the frequency range of the potential stop band. The frequency dependent decay characteristics can be used to evaluate the performance of the resonant inclusions and find optimal parameters for the desired application of the metamaterial. The procedure is applied to design beam-like resonators and find an optimal resonator spacing for a beam-like acoustic metamaterial. For a fixed percentage of added mass, the spacing of the resonators can be adjusted to optimize the maximum spatial decay or the stop band size.
Off-road motorcycle tyre force estimation
Authors: Vásquez F , Rustighi E , Lot R 
Published: July 2019

Abstract
To improve the performance of off-road motorcycles, tyre contact forces need to be estimated. Differently to on-road motorcycle contact force estimators where the rider can be considered attached to the chassis, an off-road motorcycles estimator needs to model the rider dynamics, since driving in standing position provides significant isolation from motorcycle motion. In this article, we use a novel simple rider model to approximate the interaction with the motorcycle when no sensing on him is possible. In particular, the novelty is to keep the pitch angle of the rider constant by means of an active torque on the hip. A tyre force estimator is built using this rider model coupled to a five degree-of-freedom motorcycle, which is verified with a virtual experiment performed on Working Model 2D, showing promising results.
Seismic Transient Simulation of an Operating Wind Turbine Considering the Soil-Structure Interaction
Authors: Schauer Marco , Taddei Francesca , Ríos Rodriguez Gustavo Adolfo 
Published: July 2019

Abstract
In this contribution we present a strategy to investigate the vibrations of onshore wind turbines subjected to simultaneous aerodynamic loads and seismic loads. The latter result from the propagation of seismic waves through the underlying soil and are governed by the Lamé’s equations.
The structure and its foundation as well as parts of the soil are modeled by Finite Element Method (FEM). The infinite half-space is discretized by Scaled Boundary Finite Element Method (SBFEM). Both methods are coupled at the common interface. The seismic excitation is expressed as a 3D seismic wave field and transformed into boundary tractions, which are then applied at the interface between the near and far fields. The aerodynamic actions are generated with an additional aerodynamic tool and are applied at the tower head.
The proposed method can be used also to investigate the 3D nonlinear response of the near field, where nonlinear material properties can be assigned to any element of FEM part.
Visco-elastic coupling between a linear two-dof system and a rocking rigid block to improve the dynamic response
Authors: Di Egidio A. , Contento A. , Fabrizio C. , de Leo A.M. 
Published: July 2019

Abstract
A two-degree of freedom linear system is used as a model for a multi-degree of freedom frame structure. Such a structure is coupled with a rocking rigid block to improve its dynamic response. The lowest part of the structure is connected to the block through a linear visco-elastic device. The nonlinear equations of motion of the couple system frame structure-block are obtained by a Lagrangian approach. Such equations are numerically integrated to analyze the behaviour of the coupled system. The coupling is considered effective if it reduces the displacements of the structure. Simulations are performed using a harmonic excitation as forcing term. An extensive parametric analysis is performed, and the results are summarized through behaviour maps. Such maps provide the ratio between the maximum displacements of the structure with and without the coupling with the rigid block for several combinations of system’s parameters. When the ratio of the displacements is less than unity, the coupling is effective. Results show that the presence of the rocking rigid block improves the dynamics of the structure in large ranges of the parameters that characterize the coupled system.
Nonparametric probabilistic approach for uncertainty quantification of geometrically nonlinear mistuned bladed-disks.
Authors: Capiez-Lernout Evangéline , Soize Christian 
Published: July 2019

Abstract
The present research concerns the dynamical analysis of mistuned rotating bladed-disks for which nonlinear geometrical effects exist. The present methodology requires the construction of an adapted reduced-order basis from which a nonlinear reduced-order model is constructed. The mistuning phenomenon is taken into account by considering a nonparametric probabilistic approach based on the information theory. In the present context the uncertainty is introduced by replacing the reduced-order basis with a stochastic reduced-order basis (SROB). This latter one is obtained by using a new nonparametric probabilistic approach of model-form uncertainties so that each realization of the SROB respects some mathematical properties linked to the available information under constraints concerning the specified boundary conditions and the usual orthogonality properties. With such strategy, the computational effort is focused on the stochastic nonlinear reduced internal forces and the related tangential operator which are explicitly constructed using the SROB combined with the finite element method. The numerical application is a rotating mistuned bladed-disk subjected to a load for which geometrical nonlinearities effects occur. The uncertainty propagation in this nonlinear dynamical system is then analyzed.
Effects of modal incompleteness on quantification of mode shapes complexity in vibrating structures
Authors: Iezzi F , Valente C 
Published: July 2019

Abstract
In experimental modal analysis, the mode shapes turn out to be complex due to the non-proportionality of damping in actual structures. For identification purposes, several indices have been proposed to quantify this complexity. Unfortunately, the effectiveness of the above indices is affected by the problem of data incompleteness that arises when a limited set of modal data is available, as in the case of reduced eigenvector components or in the case of band limited eigenvalues range. In contexts such as model updating, this problem makes it difficult to pair experimental versus numerical data and methods to compare the two sets of data are based on the reduction of numerical models or, conversely, on the expansion of the experimental one. However none of them reveals completely satisfactory. The present work aims to analyze the effectiveness of the above modal complexity indices. To this end, the most sensitive index found from previous studies is used in order to detect the mode shapes complexity compared to the damping non-proportionality in vibrating structures for different levels of modal incompleteness.
Wave transmission from asymmetrical changes of cross-sectional area in a beam
Authors: Takiuti B E , Manconi E , Brennan M J , Junior V Lopes 
Published: July 2019

Abstract
In this paper wave scattering from an asymmetrical change of cross-sectional area in a beam is numerically studied. Incident symmetric and antisymmetric Lamb waves are considered and multiple wave mode conversion due to interaction with the discontinuity are investigated up to high frequency (above the cut-off of the second symmetric Lamb wave mode, S
2). Results are presented in terms of transmission power coefficients, kinetic energy, and energy velocity. These are evaluated using the Wave Finite Element method to predict the wave modes from FE cross-sectional nodal displacements and nodal forces. It is shown that the methodology proposed can give an insight into wave scattering and multiple converted Lamb wave modes, which can be useful in Structural Health Monitoring.
Costs to achieve target net emissions reductions in the US electric sector using direct air capture
Authors: Supekar Sarang D , Lim Tae-Hwan , Skerlos Steven J 
Published: July 2019

Abstract
This paper examines the scale and costs of using direct air capture (DAC) with CO2 storage to reduce net CO2 emissions from the US electric sector by 70% in 2050 relative to 2010. Least-cost emission and technology trajectories are generated using an optimization-based stock-and-flow model of electricity generation to meet the 70% target. The analysis finds that the 30%–44% reduction in emissions projected under a least cost business-as-usual (BAU) scenario dominated by natural gas would fall well short of the 70% reduction target at 2050. Delaying reductions in BAU emissions beyond 2030 would require deployment of DAC to achieve the 70% target. Further delays to reduce BAU emissions until 2035 would require up to 1.4 Gt CO2 of DAC capacity to achieve the 70% target. Delaying reductions in BAU emissions beyond 2035 would require so much DAC deployment as to be implausible, placing the 70% target out of reach for most scenarios. Each year of delay in reducing CO2 emissions beyond BAU after 2020 increases costs to achieve the 70% target. A DAC-based emissions reduction future could cost an additional 580–2015 billion USD through 2050 compared to emissions mitigation starting immediately. This translates to approximately 100–345 million USD per day of delay starting in 2020. These costs arise not just from building DAC plants, but from replacing relatively young fossil fuel plants being built today with renewables as well as for the electric power needed for DAC. These results make clear that minimizing the costs of DAC deployment depend on reducing BAU emissions as early as possible, and if done quickly enough, DAC can be avoided altogether—which reduces costs the most. Hence there should be no delay in aggressively reducing emissions from the US electric sector.
Optimal power and resource-intensive process design under uncertainty
Authors: Lapteva T.V. , Nguen K.T. , Laptev S.A. 
Published: July 2019

Abstract
Approach to the solution of a problem of optimal power and resource-intensive process design under uncertainty is proposed. The problem has a form of two-stage optimization problem with separate chance constraints. The approach based on the problem’s functions approximations allows us to avoid calculation of multiple integrals. This allows us to reduce the problem of stochastic nonlinear programming to the usual problem of nonlinear programming.
The emergence of bifurcation phenomena during the flow of rheologically complex media in a tubular reactor
Authors: Livshits S.A. , Yudina N.A. , Dunaeva T.U. , Novikova O.V. , Prudchenko M.S. 
Published: July 2019

Annotation
The mathematical model describing heat-mass transfer in the course of rheologically complex media in a tubular reactor is developed in the article. Using the example of the continuous production scheme for grade B2 polymethacrylate, solutions of the characteristic equations confirming the possibility of emergence of critical flow regimes for certain sets of control parameters were obtained.
Decrease of pressure losses in elbow fittings of ventilation systems of thermal power plant buildings
Authors: Ziganshin A M , Beljaeva E E , Logachev K I , Averkova O A 
Published: July 2019

Abstract
The paper presents the results of a numerical study of the flow in the elbows of the ventilation systems in buildings of thermal power plants. Elbow fittings, as well as other shaped elements of ventilation systems are the main causes of energy losses. A method is proposed for reducing such losses through the use of an insert profiling the sharp edge of the elbow along the outline of the vortex zone. For a wide range of practical dimensions, numerical models of “sharp” elbows at 90° have been studied, a good correspondence between pressure losses in them, numerical and known experimental data has been shown. The outlines of the vortex zones, as well as the lengths of the influence zones of the elbow on the flow parameters upstream and downstream, are determined. Next, numerical models of profiled elbows are constructed and studied; a significant reduction in pressure losses (up to 64%) and lengths of influence zones (up to 45%) as compared with unprofiled ones is shown. Dependence has been found to determine the local resistance coefficient of the profiled elbow, which can be used in the design of ventilation systems.
The analysis on air pollution characteristics at the bus stops in Jinan City
Authors: Weidong Gao , Wei Jiang , Xiaomei Gao , Mimi Zhou 
Published: July 2019

Abstract
The concentration of pollutants is higher near the bus stops because of the frequent start-stop emissions of bus vehicles, which brings great risks to the travel crowd. At the stop of University of Jinan, in Jinan City, PM2.5 concentration and PM10 concentration generally showed an upward trend, and the maximum concentration was mainly concentrated at 20:00-22:00, during the observation period; the concentration of PM2.5 concentration had two peak value, around 11:00 and after 20:00, respectively, during the non-smog weather; the concentration of PM2.5 concentration and PM10 concentration has been rising gradually from 6:00 to 22:00, and the peak value around 11:00 is not very obvious, during the smog weather, but the late peak of PM2.5 concentration and PM10 concentration around 17:00 is especially obvious. The peak of PM2.5 concentration and PM10 concentration of bus stop appeared due to the frequent start and stop of the bus. The content of heavy metals in atmospheric particulates is obviously higher, especially the concentrations of Cd, Cr, Pb and Hg are 59.56, 4.31, 8.68 and 4.19 times of soil background values, respectively, which are obviously enriched. the heavy metal concentrations in falldust are very close to the heavy metal concentrations of atmosphere particulate matter, the result indicated that the heavy metal emitted by automobile exhaust gas has no obvious influence on atmospheric heavy metal content in a short time, the disturbance of ground dustfall has a great influence on the concentrations of heavy metals in the atmosphere. The exposure level of PM2.5 and PM10 during haze weather conditions is far greater than exposure level of PM2.5 and PM10 during non-haze weather conditions.
Enlightenment of Foreign Theories of Sustainable Storm Water Management to Sponge Cities in China
Authors: Jiayu Hu , Manhua Li , Yang Shu 
Published: July 2019

Abstract
With the promotion of sponge cities in China, foreign theories of sustainable rain and flood management similar to sponge cities has also begun to attract attention from all sectors of society. In China, sponge cities are developing continuously. However, people’s doubts about sponge cities are rising because of people’s low understanding of sponge cities, some problems in the construction process of sponge cities, and the results so far are not significant. This paper makes a comparative study on the foreign theories of sustainable rain and flood management and sponge cities.
Study on the Controlling Factors of Coal Seam Distribution in Jurassic Yan’an Formation in Longdong Area in Ordos Basin
Authors: Li Zhenhua , Zhang Suya , Li Xiangyang 
Published: July 2019

Abstract
The distribution characteristics of coal seams and the main controlling factors of coal accumulation of the Middle Jurassic Yan’an Formation in Longdong area are analyzed in this paper based on geophysical logging data, drilling data and sedimentation background. The results show that the central and western parts of Longdong are the main development areas of coal seams, the coal seams are thick in the west and south, while they are thin in the east and north, and thickness of coal seams in this area ranges from 10m to 30m. The characteristics of sedimentary structure indicate that the warm and humid climate, palaeogeographic environment of swamp facies, palaeo-vegetation and late tectonic movement influenced the formation and distribution of coal in Longdong area. The study suggests that the coal resource in Longdong area is rich and preserved well, and its structure is simple, so it is favourable for exploration and has great economic potential.
Research on Optimization of LNG pressure control safety accessories based on fault tree analysis
Authors: Liu Hongkai , Zhu Genmin , Zhang Mingqiang , Shen jiankang , Zhang Xiaohui 
Published: July 2019

Abstract
This paper classifies more than 20 accidents according to the main factors and types of accidents from 1994 to now. Through analysis, it is found that the safety attachment of LNG pressure control is a weak link in LNG storage system. The safety attachment of LNG pressure control is analyzed from four aspects of people machine Environmental management, and the fault tree model is established. After calculation, the minimum cut set and structural importance of the safety attachment of LNG pressure control are obtained. Based on the fault tree analysis results of LNG pressure control safety accessories and the statistical results of 20 accidents, control measures and suggestions are put forward from the peripheral layout, electrical, equipment, installation, production operation, daily maintenance of LNG pressure control safety accessories, in order to prevent and reduce accidents caused by LNG pressure control safety accessories.
Design of half-rotating impeller tidal turbine and its energy-capturing characteristics
Authors: Wang Xiaoyi , Gao Xu , Xue Kang , Zhang Yuhua , Zhang Liangan , Qiu Zhizhen 
Published: July 2019

Abstract
Based on characteristics of the half-rotating mechanism, a new type of vertical axis turbine with characteristic of lift-drag combination was proposed, which named the half-rotating impeller tidal turbine(HRITT). The turbine was composed of rotary mechanism, alignment mechanism and support mechanism. The mechanism design and manufacture of the HRITT were completed and underwater operation experiments were carried out to verify the rationality of mechanism design and its good self-starting performance. Through the hydrodynamic simulation of the impeller by Xflow, the changes of pressure and velocity around the blades in the flow field were analyzed, which proved the feasibility of the operation and energy-capturing characteristics of lift-drag combination of the HRITT.
Preparation and characteristics of magnetic water hyacinth
Authors: Zeng Huiting , Wu Xiaoqing , Zeng Honghu , Zhang Hua , Shahab Asfandyar 
Published: July 2019

Abstract
The preparation process and method of magnetic water hyacinth(MBC) were conducted, and the morphological structure and surface characteristics of biochar were characterized. The optimal MBC preparation method was obtained under different carbonation temperatures, impregnation times, and mass ratio of potassium carbonate to water Gourd: carbonization temperature is 450 °C, iron nitrate concentration is 0.2 M, and the mass ratio of potassium carbonate to water hyacinth is 0.5:5.
Seismic damage pattern analysis of high piers of RC bridges based on the fiber model
Authors: Li Zheng , Ren Qingying 
Published: July 2019

Abstract
The practical method of the seismic damage analysis of high piers of RC bridges is established using the uniaxial modified Faria-Oliver damage model for concrete and modified Menegotto-Pinto model for rebars, based on the fiber beam-column element, in the FEA software ABAQUS. Furthermore, the seismic damage analysis of short pier and high piers of different section sizes are conducted, respectively. The results indicate that for the short piers the damage zone is located at the bottom of piers. However, the high piers tend to have multi-location damage zones, and the tendency is more obvious for the high piers with a more slender shape.
Development of a Practical Uniaxial Cyclic Constitutive Model for Concrete
Authors: Li Zheng , Ren Qingying 
Published: July 2019

Abstract
The uniaxial stress-strain curves of concrete suggested in Chinese Concrete Standard (GB50010-2010) are combined with the modified Yassin hysteretic rule. The integrated cyclic constitutive model for concrete is aimed at the nonlinear analysis of the reinforced concrete (RC) structures under strong earthquake. The model is implemented into general-purpose FEA software ABAQUS through the user material subroutine VUMAT. Then, some typical performances of the proposed model are verified. Furthermore, a seismic damage analysis of a multi-story RC frame structure is conducted using the cyclic model. The results show that the constitutive model is applicable to the nonlinear seismic analysis of RC structures.
Research on Investment Management System and Supervision System Construction of Power Grid Enterprise Group
Authors: Ma Yungao , Xia Liyu , Lu Qiang 
Published: July 2019

Abstract
This paper analyzes the internal and external situations faced by the power grid enterprise group investment management system and supervision, and puts forward the ideas and key points of the group company’s investment management system and supervision system optimization and improvement. It will play a positive role in implementing the state’s legal management of enterprises, standardizing investment activities, preventing and controlling investment risks, and achieving high-quality development.