bluuebunny/crossref_metadata_2025 huggingface dataset:
Unique decomposition of homogeneous languages and application to isothetic regions
Authors: HAUCOURT EMMANUEL , NININ NICOLAS
Published: October 2018

A language is said to be homogeneous when all its words have the same length. Homogeneous languages thus form a monoid under concatenation. It becomes freely commutative under the simultaneous actions of every permutation group on the collection of homogeneous languages of length n ∈ ℕ. One recovers the isothetic regions from (Haucourt 2017, to appear (online since October 2017)) by considering the alphabet of connected subsets of the space |G|, viz the geometric realization of a finite graph G. Factoring the geometric model of a conservative program amounts to parallelize it, and there exists an efficient factoring algorithm for isothetic regions. Yet, from the theoretical point of view, one wishes to go beyond the class of conservative programs, which implies relaxing the finiteness hypothesis on the graph G. Provided that the collections of n-dimensional isothetic regions over G (denoted by |G|) are co-unital distributive lattices, the prime decomposition of isothetic regions is given by an algorithm which is, unfortunately, very inefficient. Nevertheless, if the collections |G| satisfy the stronger property of being Boolean algebras, then the efficient factoring algorithm is available again. We relate the algebraic properties of the collections |G| to the geometric properties of the space |G|. On the way, the algebraic structure |G| is proven to be the universal tensor product, in the category of semilattices with zero, of n copies of the algebraic structure |G|.
Paediatric pulmonary hypertension caused by an ACVRL1 mutation presenting as Ortner syndrome
Authors: Alsheikh Batool , Aljohani Othman , Coufal Nicole G.
Published: October 2018

We report a rare aetiology of vocal cord paralysis secondary to undiagnosed severe pulmonary hypertension from a de novo ACVRL1 variant identified by whole-genome sequencing. The patient had a partial response to intravenous treprostinil in addition to inhaled nitric oxide, bosentan, and sildenafil.
Economic integration and state capacity
Authors: Bruszt Laszlo , Campos Nauro F.
Published: October 2018

We investigate whether and how economic integration increases state capacity. This important relationship has not been studied in detail so far. We put together a conceptual framework that highlights what we call the Montesquieu, Weber and Smith channels to guide our analysis. Each of these corresponds to a series of mechanisms in three distinct institutional arenas: judiciary, bureaucracy and competition policy. To test our framework, we introduce a new panel of institutional reform measures that allow us to investigate how changes in these three arenas interact with each other and what sequence of changes yields increases in state capacity. The yearly data set covers all the 17 candidate countries to join the European Union (EU) after the 1995 enlargement. Deep integration, we find, can induce broad institutional change by providing incentives for simultaneous change in core state institutions. Bureaucratic independence and judicial capacity seem to be the key engine of the process engendered by the prospect of EU membership. Yet early and abrupt removal of external anchors might generate significant backsliding, or reversals, in domestic institutional change.
Spatial trends in United States tornado frequency
Authors: Gensini Vittorio A. , Brooks Harold E.
Published: October 2018

Severe thunderstorms accompanied by tornadoes, hail, and damaging winds cause an average of 5.4 billion dollars of damage each year across the United States, and 10 billion-dollar events are no longer uncommon. This overall economic and casualty risk—with over 600 severe thunderstorm related deaths in 2011—has prompted public and scientific inquiries about the impact of climate change on tornadoes. We show that national annual frequencies of tornado reports have remained relatively constant, but significant spatially-varying temporal trends in tornado frequency have occurred since 1979. Negative tendencies of tornado occurrence have been noted in portions of the central and southern Great Plains, while robust positive trends have been documented in portions of the Midwest and Southeast United States. In addition, the significant tornado parameter is used as an environmental covariate to increase confidence in the tornado report results.
Slow magnetic relaxation in a μ1,1′-azido cobalt(ii) methylquinoline chain complex
Authors: Rajnák Cyril , Dlháň Ľubor , Moncol Ján , Titiš Ján , Boča Roman
Published: October 2018

A [Co(N3)2(mqu)] complex with a 1D chain architecture (mqu – 4-methylquinoline) shows slow magnetic relaxation with three distinct modes. The relaxation time strongly depends upon the applied external field. The low-frequency mode exhibits a relaxation time longer than one second: τLF = 1.6(2) s at BDC = 0.8 T and T = 1.9 K.
A far-red emission (Ca,Sr)14Zn6Ga10O35:Mn4+ phosphor for potential application in plant-growth LEDs
Authors: Wu Yibing , Lv Ying , Ruan Kaibin , Xie Zhi
Published: October 2018

To facilitate phosphor-converted light-emitting diodes (LEDs) for plant growth, the development of phosphor materials with efficient red or far-red emission is essential.
Copper deficiency-induced anemia is caused by a mitochondrial metabolic reprograming in erythropoietic cells
Authors: Jensen Erik L. , Gonzalez-Ibanez Alvaro M. , Mendoza Pierina , Ruiz Lina M. , Riedel Claudia A. , Simon Felipe , Schuringa Jan J. , Elorza Alvaro A.
Published: October 2018

Copper deficiency reprograms mitochondrial metabolism, which becomes less oxidative, to favor cell expansion over cell differentiation.
Event‐triggered state estimation for stochastic hybrid systems with missing measurements
Authors: Jin Zengwang , Hu Yanyan , Sun Changyin
Published: October 2018

This study is concerned with the event‐triggered state estimation problem for a class of stochastic hybrid systems with missing measurements in a networked environment. Two independent Markov chains are introduced to, respectively, characterise the stochastic measurement missing and the possible modal (or mode) transition of the system. In consideration of the constrained bandwidth and limited power resources of networked systems, a closed‐loop event‐triggered mechanism based on the measurement innovation is designed to trigger data transmission only when trigger conditions are satisfied. To keep the exponentially increasing number of full hypothesis sequences in optimal estimation to bounded computational complexity, the interacting multiple model framework is extended to tackle event‐triggered sampling with the statistical information implicit in event‐triggered conditions sufficiently explored and the possible measurement missing taken into account. A Monte Carlo simulation involving tracking a two‐dimensional manoeuvring target with two operational modes is provided to demonstrate the effectiveness and efficiency of the proposed event‐triggered hybrid state estimation in the presence of missing measurements.
Optimal selection of voltage sag mitigating devices for micro‐level customer in distribution system
Authors: Mitra Rituparna , Goswami Arup Kumar , Tiwari Prashant Kumar
Published: October 2018

Power quality is a vital issue in distribution systems. Power quality issues have become important for the extensive use of sensitive equipment and integration of renewable generation. Several researchers have proposed for voltage sag mitigation devices to minimise financial losses arising from voltage sag. Augmentation of micro‐level units like housing complex, super‐specialty hospitals, rapid urbanisation has opened up demand for electricity. Modernisation in life has led to coextensive requirement for good quality power. Importance of micro‐level consumers is to be considered while looking into the matter of optimal selection of voltage sag mitigation devices. In this study, a new framework is proposed for optimal selection of voltage sag mitigation devices to minimise voltage sag occurrence in a distribution system based on Nested Logit model. Nested Logit model has the essential characteristic for selection of optimal option by allowing equal preference to all the available customers’ choice. This model gives unbiased and equal importance to all the available mitigation devices. The optimal selection of mitigation devices is obtained using aggregate forecasting. Voltage sag severity index is used for placement of optimally selected voltage sag mitigation device. Two case studies are described to validate the proposed approach.
Storage allocation and investment optimisation for transmission‐constrained networks considering losses and high renewable penetration
Authors: Yacar Dean , Tejada‐Arango Diego A. , Wogrin Sonja
Published: October 2018

This study investigates the effects of transmission losses, constraints and increased renewable energy penetration on planning energy storage allocation and investment. By modifying a DC optimal power flow model using a linearised approximation for ohmic losses, the authors were able to understand which network characteristic or inhibitor drives the most change in expanding utility‐scale storage. Four different storage technologies were explored: compressed air energy storage, pumped hydro storage, lithium‐ion battery and fly wheel. Each had different charging, capacity and cost characteristics. The results of the storage allocation trials revealed that network congestion was a more influential network inhibitor than were line losses. Losses only had substantial effects on a free‐flowing network but produced marginal changes in allocation in congested ones. The conclusion of the investment trials revealed two things: (i) storage investment is not significantly affected by transmission constraints so long as renewable generation stays constant and relatively low; (ii) more flexible technologies like flywheels are favoured at lower volumes of renewable penetration for their load balancing capabilities while cheaper technologies are best as the volume of renewable power generated increases.
The analysis of dispersed generation influence on power system automatics settings and function algorithms
Authors: Ilyushin Pavel
Published: October 2018

Dispersed generation (DG) objects are usually connected to distribution grid. This-type of grid supposes to have power system automatics (PSA) that comprise emergency control system (ECS). ECS serves for normal power supply scheme recovery after fault elimination, fault development prevention and system parameters maintenance in acceptable limits within fault and post-fault conditions. Generating power connection to the grid causes significant power flow and current distribution change. This might become a reason of ECS automatics misoperation. This paper presents the results of DG objects influence analysis on PSA settings and function algorithms. Implemented analysis has allowed to define post-fault conditions envelopes that have to be analysed within DG objects grid connection design and provide the recommendations for PSA settings and function algorithms change.
Methods for calculation of the marginal exploitation lifespan of power transformers 35 rV and higher based on the state index
Authors: Nazarychev Alexandr , Andreev Dmitriy , Tadjibaev Alexey , Vysogorets Svetlana , Sulynenkov Ilia
Published: October 2018

A methods for determining the marginal exploitation lifespan of a transformer based on a complex diagnostic survey was developed. The integral evaluation of the technical state of the transformers is performed according to the value of the condition index. An example of the marginal exploitation lifespan calculation of the transformer according to the real initial data is given. The application of the methods will allow to proceed to the planning of technical re-equipment and reconstruction of energy facilities taking into account the technical condition of the equipment.
Resilience Assessment of the State Estimation Software under Cyber Attacks
Authors: Voropai Nikolai , Kolosok Irina , Korkina Elena
Published: October 2018

Taking into account Smart Grid creation, cyber security appears as critical problem. In spite of wide set of technical tools and organisational decisions, which use for protection of electrical objects against cyber attacks, it is impossible to prevent them completely. Therefore, the ability of Smart Grid to resist cyber attacks is important and necessary property. Thus, the cyber resilience is ability of complicate technical-information system to keep operable state under contingencies including cyber attacks. This paper deals with general problem of electric power system resilience and its cyber resilience, determination methods to calculate quantitative measure of Smart Grid resilience. The state estimation software resilience under cyber attacks is discussed.
Configuration management of electricity distribution grids 6-35 kV according to the criteria of reliability
Authors: Vukolov Vladimir , Papkov Boris , Pnev Evgeny , Kolesnikov Anton
Published: October 2018

Questions of a choice of criteria for definition of places of opening of electric networks 6-35 kV are considered in this paper. Recommendations are given on the configuration management of distribution electrical networks based on the hierarchy analysis method.
Calculations of the complex network’s steady-state modes by brining it to equivalent open
Authors: Akhmetbayev Dauren , Zhantlessova Assemgul , Akhmetbayev Arman
Published: October 2018

The paper considers the development of the idea of diakoptics as applied to the calculation of the steady-state modes of energy system’s complex electrical networks. The well-known goal of diakoptics is to obtain the equations of state for the dedicated part of the system, the study of which is much simpler than the study of the initial system and can be achieved by improving its steady state equations. Technique for dividing a complex-closed system into a set of uncomplicated subsystems was developed based on the inverse form of nodal equations. Analytic expressions for the intersection circuits obtained based on identical equality of voltage at the nodes of the system division into subsystems are proposed. Using the example of 110kV network calculation, the technique for determining the matrixes of generalized parameters of the dedicated subsystems, the sizes of which depend on the number of their broken link is shown. Analytical determination of the equality condition of the voltage of subsystems intersections nodes, allowed analyzing a complex closed network by bringing it to an equivalent open.
Semi-Markov and hidden semi-Markov models of energy systems
Authors: Obzherin Yuriy E.
Published: October 2018

The problem of information control systems creation for energy systems and transition to intelligent control and engineering is one of the important problems of reliability and efficiency theory for energy systems. The solution of this problem is possible based on construction of mathematical models concerning different aspects of these systems structure and operation. The possibilities of application of semi-Markov processes with common phase space of states, hidden Markov and semi-Markov models for energy system modeling are considered in the paper.
Prospects of using new technologies in Russia’s electric power industry to comply with international commitments to reduce CO2 emissions
Authors: Tchemezov Alexey , Chemezova Elena , Syromyatnikov Anton
Published: October 2018

This study addresses the methodology of projecting the electric power industry developments, taking into account environmental constraints. I obtained quantitative assessments of long-term electric power industry development in a Russian region, determined the emission of greenhouse gases from fuel combustion at thermal power plants (TPPs), and the efficiency of technologies to reduce greenhouse gas emissions in the electric power industry.
Determination of Critically Objects of Electric Power Systems from the Position of Energy Security
Authors: Krupenev Dmitry
Published: October 2018

The paper deal the problem of definition and ranking of critical objects (CO) in electric power systems (EPS). The identification of the CO is necessary for the timely adoption of measures to organize the provision of the required level of energy security of the region where the object is location. The adequacy model is used for determine the critical objects of EPS, within the framework of which the simulation of the functioning of EPS during the given time interval is carried out, taking into account the main random factors affecting its operation. Approbation of the proposed approach is presented on the interconnected power system.
Comparative analysis of strategies for a semi-active suspension of a ¼ vehicle
Authors: Melo Matheus , Avila Suzana
Published: October 2018

The vehicle suspension isolates the chassis from road irregularities, reacting to forces produced by the tires and the braking torques, always keeping the road tire contact, providing stability and safety. Stability and safety are two antagonistic characteristics in suspension design, when improving one the other is impaired and vice versa. The semi-active suspension is a type of vehicle suspension that can change its stiffness and/or damping in real time depending on the vehicle response to the actual road profile. The On-Off semi-active suspension changes its damping coefficient between two fixed limit values. This work proposes an On-Off semi-active suspension model, in which the damping coefficient changes its values considering the road profile function frequency. A control strategy is proposed in a way to improve performance keeping the same simplicity, without any structural change of the semi-active suspension. On the proposed control strategy one of the damping coefficients is obtained through the linear quadratic regulator (LQR) algorithm, with the aim to set the coefficient from the gain matrix associated to the velocity of the suspended mass. This model is compared to anothers found in literature.
Experimental study of a passive inverted pendulum control system
Authors: Resende Diogo V. , de Morais Marcus V. G. , Avila Suzana M.
Published: October 2018

This work presents the results obtained by an experimental study of vibration control for a system with a single degree of freedom, composed by a sliding base on an air track. An inverted pendulum-type tuned mass damper (TMD-IP) is installed on the sliding base to reduce its displacements. First, a reduced model is built using a 3D printer. The experimental model consists of two parts: the mains system, which is the sliding base; and the inverted pendulum (TMD-IP). The model can be tested as a one-degree-of-freedom system using only the base or as a two-degree system of freedom system after connecting the TMD-IP to the sliding base. The CIDEPE air rail is used to provide the sliding base displacement, which will receive the TMD-IP. The acquisition of the response data in the time domain is done through the software CvMob, which performs image acquisition and was produced by the Nucleus of Technological Innovation in Rehabilitation - NITRE, Federal University of Bahia.
Stability of the dynamic shifting process in the vehicle transmission with the input shaper
Authors: Taratorkin Alexander , Derzhanskii Victor , Taratorkin Igor
Published: October 2018

This paper investigates stability of the dynamic process of gear shift in the vehicle transmission with the input shapers (IS) taking in consideration uncertainty of the natural frequency of the mechanical system. The proposed control algorithm increases the stability of the researched system with variation of its elastic and inertial parameters. The control law with guaranteed asymptotic stability is obtained for full load of the vehicle when the all-wheel drive is turned on. The monitoring of the state and performance of the required parameters for the regulation of input shapers are tested by means of numerical simulation. Analyzing the results it is established that the best stability is reached by the adaptive setting of the input shapers in accordance with controlled value of the natural frequency of the lowest single-node mode.
Identifying route to stall flutter through stochastic bifurcation analysis
Authors: Bethi Rajagopal V , Reddy Gali Sai Vishal , Venkatramani J
Published: October 2018

The interaction of an elastic structure such as an airfoil and fluid flow can give rise to nonlinear phenomenon such as limit cycle oscillations, period doubling or chaos. These phenomena are indicated by a change in the stability behaviour of the dynamical known as bifurcations. Presence of viscous effects in the fluid flow can give rise to flow separation which causes a stability change in the system that is identified to happen via a Hopf bifurcation. In such cases, the airfoil exhibits limit cycle oscillations which are torsionally dominant, known as stall flutter. Despite identifying the route to stall flutter under uniform flow conditions, investigating a stall problem under stochastic wind has received minimal attention. The ability of fluctuating flows to change the stability boundaries and disrupt the route to flutter, compels the need to carry out a stochastic analysis of stalling airfoils. Study of stall flutter in such systems under the influence of a time varying sinusoidal gust is undertaken and the route to flutter is identified by carrying out a stochastic bifurcation analysis.
Analysis of AE characteristics of tool wear in drilling CFRP/Ti stacked material
Authors: Wang Zhan , Leng Sheng , Min Tao , Chen Gang
Published: October 2018

Based on the signal data acquired in drilling process of carbon fiber reinforced polymer/titanium alloy (CFRP/Ti) stacked materials, the acoustic emission (AE) characteristic values were carefully studied, by using the method of statistical analysis, spectrum analysis and wavelet packet. The results show that the root mean square(RMS) value of the AE signals and the energy of the wavelet packet are closely related to the tool wear. Meanwhile, experiments indicate that different materials, chips and tool tipping will cause instantaneous signal mutation, which has different forms in time domain and in time-frequency domain. These mutations may increase the difficulty of identifying the tool wear. Fortunately, with repeated experiments and comparison, some identifiable mutations were recognized. When a tool is processed from CFRP to Ti, the signal intensity decreases generally, the high-frequency component of signal increases gradually, and the signal has a tendency to show in high frequencies.
Visualization research on the influence of an ultrasonic degassing system on the operation of a hydraulic gear pump
Authors: Antoniak Piotr , Stryczek Jarosław , Banaś Michał , Lyhovskyi Oleksandr , Gryshko Ihor , Zilinskyi Andrii , Kovalov Vasyl
Published: October 2018

Gear pumps make a group of the most popular hydraulic energy generators. Research and development works concerning those units have been going on for decades, and thanks to them gear pumps feature very good operating parameters. However, even well-designed gear pumps will not work properly if the physical properties of the working fluid are incorrect. One of such properties is compressibility of the fluid, which largely depends on the amount of gas dissolved in the medium. For this reason, the aim is to reduce the amount of gas dissolved in the working medium. It can be done using both chemical and physical methods. Because chemical methods can affect the chemical composition of the working fluid, it is the physical methods that are usually used in hydraulic systems.

This paper presents preliminary visualization research into the influence of an ultrasonic degassing system on the operation of a hydraulic gear pump. Apart from that, operation of such a system and its theoretical impact on the work of the gear pump is discussed Experimental study, using a high-speed camera, was carried out in order to verify the theoretical description.
Acoustic devices for breathing investigations
Authors: Shkundin Semyon , Rumyantseva Valentina
Published: October 2018

The problem of spirometry control in medicine and medical engineering still remains urgent. The necessity of getting more and more information from spirometry investigations imposes more and more stringent requirements for spirometers, volumeters and bodypletizmographs, first of all, to the primary spiroflow transdusers. Practice shows that these requirements cannot be met by improving devices which use conventional spirometric principles. The new acoustic means for pulsating air-gas flow rate measurement has been created in Russia and is described in the paper. The main feature is special air-metric channel, supplied with ceramics electroacoustic transducers. The principle of its operation is based on the dependence of the acoustic vibrations arriving at the receiver velocity upon the air-gas flow rate. The device does not disturb the air dynamic structure of the flow, has no inertia or moving elements and unsurpassed sensitivity and precision.
Calculation of acoustic flow-rate measurements error with the help of Fermat’s principle
Authors: Petrov Alexander , Shkundin Semyon
Published: October 2018

The establishment of dispatching and automatic control systems for mine ventilation is impossible without the availability of perfect air flow rate sensors. Existing anemometers (tachometer, heat) do not meet these requirements. The error of average in cross section velocity measurements with such sensors reaches 15-20, sometimes 30%. The reason - the speed measured at one point is interpreted as the average over the cross section. The reliability of the sensors is small, because they are exposed to the damaging effect of a dusty atmosphere. Stationary installed anemometers clutter cross section, which is not always allowed. Fermat’s variational principle is used for derivation of the formula for the time of propagation of a sonic signal between two set points A and B in a steady three-dimensional flow of a fluid or gas. It is shown that the fluid flow changes the time of signal reception by a value proportional to the flow rate independently of the velocity profile. The time difference in the reception of the signals from point B to point A and vice versa is proportional with a high accuracy to the flow rate. It is shown that the relative error of the formula does not exceed the square of the largest Mach number. This makes it possible to measure the flow rate of a fluid or gas with an arbitrary steady subsonic velocity field
A Bayesian updating procedure for the electromechanical properties of piezoelectric energy harvesters
Authors: Peralta Patricio , Ruiz Rafael O. , Meruane Viviana
Published: October 2018

In the last decade, several numerical and analytic procedures have been proposed to predict the dynamic behavior of piezoelectric energy har- vesters (PEHs). Nevertheless, PEHs present characteristics that are di ﬃ cult to control in their manufacturing process, for example the electromechanical properties of the materials present variations up to 20% of their nominal val- ues. In that sense, the use of deterministic models to obtain accurate predictions implies to have full information about the geometry and the electromechanical properties. This work introduces a procedure to update the electromechani- cal properties of PEHs based on Bayesian updating techniques. The procedure requires the use of: (i) a predictive model, (ii) a prior multivariate probabilis- tic density function for the electromechanical properties, and (iii) experimen- tal measurements of the harvester response. The mode of the updated elec- tromechanical properties is identiﬁed adopting a Maximum a Posteriori esti- mate while the probability density function associated is obtained by applying a Laplace’s asymptotic approximation. The procedure is exempliﬁed using the experimental characterization of 20 nominally identical PEHs. Results show the capability of the procedure to update not only the electromechanical proper- ties of each PEH but also the characteristics of the whole sample of harvesters (mandatory information for design purposes).
Verified nonlinear model of piezoelectric energy harvester
Authors: Rubes Ondrej , Brablc Martin , Hadas Zdenek
Published: October 2018

Energy harvesting is an important topic today. Complex monitoring systems with many nodes need energy sources and vibration energy harvesters (VEHs) could be one type of them. Mathematical model of the VEH is necessary instrument to estimate possible harvested power. This paper deals with piezoelectric VEH in setting as cantilever beam with tip mass. Traditional linear model of this type of VEH is simple, however, it represents the VEH only in one operating point and in another one (another amplitude of excitation vibrations) it could return wrong results. The nonlinear model of VEH is introduced in this paper with its parameters estimation. The nonlinear model is compared with linear model and experiment to demonstrate difference between them in amplitude frequency characteristics. Finally, the average harvested power from harmonic vibrations is measured experimentally and compared with prediction from linear and nonlinear model.
Analytical evaluation of the lifetime of a three-axle bogie frame using the analytical model validated through experimental modal analysis
Authors: Ion Manea , Ioan Sebesan , Mihai Matache , Gabriel Prenta , Catalin Firicel
Published: October 2018

The fatigue strength validation by tests of the railway bogie frames requires existence of an expensive laboratory and a long time for testing, of about 6 to 10 months. Considering these aspects, the european norms admit that fatigue tests can be replaced by finite elementes analysis, with condition that analytical model to be correctly realized and validated by tests. Experimental modal analysis provides a powerful tool for validation of the FEA model through experimental data. The article presents an application for analytical assessment of the fatigue strength for a three-axle locomotive bogie frame, before sending it to the laboratory fatigue tests. Using Ansys, it was carried out the structural analysis of the bogie frame, rezulting the modal model characterized by the modal parameters: eigenfrequencies and eigenshapes. The analytical model was validated through an EMA application carried out on the bogie frame and correlation analysis of the EMA and FEA models. The analytical model and data files containing the simulated vertical, transverse and twist loads, applied to the bogie frame according to EN13749/2011, constitutes the input data for nCode program, that evaluates the bogie frame lifetime using appropriate stress curves and a recognized hypothesis of damage accumulation.
Wear depth calculation and influence factor analysis for groove ball bearing
Authors: Lu Fengxia , Zhu Rupeng , Fu Qiuju
Published: October 2018

Based on Hertz contact theory and load distribution, the formulas for contact stress cycle times, slip distance and wear depth measurements are derived, and the influences of load, curvature coefficient, roll body diameter and friction coefficient on the contact region wear depth and distributions are thoroughly analyzed. The results show that the wear depth is zero at the pure rolling point and the long half-axle terminals of contact ellipse, and reaches maximum value near by the long half-axle terminals of the contact ellipse, and further shows that the wear depth increases with increase of the load and friction coefficient, however decreases with increase of the curvature coefficient and roll body diameter.
A new approximate model of tyre accounting for both deformed state and dry friction forces in the contact spot on the background of the coupled model
Authors: Kireenkov Alexey A. , Nushtaev Dmitry V. , Zhavoronok Sergey I.
Published: October 2018

A new approximate model of the tire rolling accounting for coupled longitudinal and lateral sliding as well as the spinning and the deformed state resulting in elastic forces is proposed. The main goal of this investigation consists in the construction of simple models with a few of degrees of freedom allowing one to implement them analytically in the engineering practice, primarily for the estimation of the rolling stability and for the prognosis of the instable rolling so-called ”shimmy phenomenon” and to numerical simulation of the transient dynamics of rolling wheels with sliding effects. Such a model could become useful at the earlier stages of the engineering design instead of complex numerical models that are usually resource consuming.

The known models of the shimmy phenomenon are usually based on the nonholonomic condition of the steady rolling and consider as the main cause of instability only the tire deformation while the sliding and spinning are assumed to vanish, i. e. the dry friction effects are neglected. Another type of models consists in the ”rigid wheel” assumption, in other words only the dry friction effects are accounted on the background of the coupled dry friction theory whereas the deformed state effects are neglected. Such a theory is based on the complete accounting of the combined kinematics due to simultaneous sliding and spin and shows its efficiency for slightly deformed wheels and the unsteady rolling regimes. Our goal consists in the formulation of the combined model that takes into account as well as the deformed state as the dry friction effects. This model is based on the solution of some model problems for the tire using solid finite element simulation or various shell theories, the computing of a set of specific generalized rigidity factors for the tire model, and on the accounting for the shape of the contact spot and the contact pressure distribution after the numerical simulation of the tire-road contact interaction in quasi-statics. As a result, we obtain a model with only a few degrees of freedom but more general that the Keldysh’s or Klimov’s ones.
Dynamic assessment of a cable-stayed footbridge under earthquake sequence using a concrete damage plasticity model (CDP)
Authors: Ciura Rafał , Drygała Izabela , Dulinska Joanna M.
Published: October 2018

In this paper, the investigation of the dynamic response of a cable-stayed footbridge with steel reinforced concrete deck to foreshocks, a mainshock and an aftershock seismic sequence is delivered. For the aim of the study the finite element (FE) model was prepared with the ABAQUS/Standard software program. The representative seismic events with three components were taken into account in the numerical simulation. For the evaluation of seismic-induced damages in reinforced concrete deck of the footbridge, the concrete damage plasticity (CDP) model was applied.
Dynamic forces with random amplitudes from rhythmic jumps and squats
Authors: Pańtak Marek
Published: October 2018

In the paper the load models of the dynamic forces generated during jumps and squats taking into account random changes in the amplitudes of the forces are presented. The models were elaborated on the basis of series of laboratory measurements of continuously and rhythmically performed jumps and squats in frequency range 1.40-3.80 Hz.
Controlling construction-induced vibrations in healthcare facilities
Authors: Wong Melissa W.Y. , Wesolowsky Michael J.
Published: October 2018

Controlling excessive floor vibrations is critical in modern healthcare facilities where high-resolution imaging and diagnostic equipment are often used. These types of equipment have stringent floor vibration criteria to ensure the accuracy of their results. Controlling floor vibrations is further complicated as existing healthcare facilities are being renovated and upgraded to meet current healthcare demands, while remaining in operation. This paper presents a case study of an existing hospital which is undergoing extensive renovations. This hospital houses a variety of diagnostic imaging equipment including Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) equipment, as well as mass spectrometers. To determine the extent of the vibration mitigation required such that the equipment can remain operational during construction, vibration tests simulating the future construction activities were conducted. The vibration tests consisted of striking the ground with an excavator, while accelerometers were placed at strategic locations throughout the hospital to capture the excitation.
On the sloshing effect in half-filled freight trains during braking
Authors: Dai Jian , Han Mengmeng , Ang Kok Keng , Tran Minh Thi
Published: October 2018

This paper is concerned with a computationally efficient numerical study on the dynamic responses of a half-filled freight train during braking phase using the moving element method. The motion of liquid inside the freight tank is modelled based on potential flow theory. The vehicle components are represented by interconnected rigid multi-bodies and the track is modelled by an Euler beam resting on a Pasternak-type foundation. The accuracy of the proposed computational model is examined by comparison with available results in the literature. This paper also investigates the effect of the initial train speed and the braking torque on the dynamic response of the train-track system.
Railway infrastructures sustainable interventions: Proposal for a Cost-Benefit Analysis application
Authors: Couto Paula , Salvado Filipa , Silva Maria João falcão
Published: October 2018

The decision to intervene in Railway Infrastructures (RI) in a sustainable way is complex, because the involved costs require different assessment levels, given their relevance to all stakeholders in decision-making, and are not always easily quantifiable. Following recent decisions of the EU, it is urgent to carry studies to support RI sustainable interventions. In this context, the use of methodologies based on Cost-Benefit Analysis (CBA) contributes positively to base decisions on RI investment projects. CBA is a methodology to assess the net economic impact of a public investment project and can be used for a variety of interventions. CBA is based on the conversion to monetary values of all costs and benefits, even when they are intangible. The purpose of a CBA is to evaluate if a project is feasible from the point of view of social welfare through the algebraic sum of their costs and benefits discounted over time. This paper presents a framework for the assessment of RI sustainable projects based on CBA, which integrates the development of community policies and financial instruments. It aims to provide technical support and contribute to the reflection about co-financing rates modulation.
Transport infrastructures assessment using multiple GPR configurations and FWD
Authors: Marecos Vânia , Fontul Simona , Solla Mercedes , Antunes Maria de Lurdes
Published: October 2018

This article presents a case study where FWD and GPR, two NDT methods, were combined to assess the bearing capacity of a flexible pavement. The thickness of the bituminous layer was estimated using a coreless GPR approach: the Common Mid-Point method with Air-Coupled antennas, by combining multiple GPR offset configurations.
Multi-criteria analysis applied to railway rehabilitation
Authors: Caetano Vasco , Couto Paula , Fontul Simona , João Falcão Silva Maria
Published: October 2018

The railway infrastructure has very specific constraints that lead to the need of maximizing of the availability of infrastructure, with high levels of safety and quality, associated with an optimized cost. Having said this, it is essential to understand the methods behind the inspection and monitoring of existing railway infrastructures, the way of processing their data, as well as existing rehabilitation solutions. The present work begins with a brief description of the components of the ballast track and its operation, the different types of actions to which it is subjected to and the degradation mechanisms at the level of the ballast layer, substructure and transition zones, with particular attention being given to the latter since it is a section of the road with singularities that lead to a more pronounced degradation. The rehabilitation solutions addressed in this work start from a slight attack of the road (which can be considered as a small intervention) until a complete renovation of the road with reinforcement of the foundation. Based on the previously mentioned concepts, it is possible to define which variables, criteria and respective weights are more important and influence the investment decision (on the rehabilitation of the railway infrastructure), thus enabling the methodologies of multi-criteria analysis applied to these variables. Currently, the economic factor is one of the variables that influence the most in decision making due to the lack of investment capacity. Mainly because of this factor and sometimes even without performing an analysis, one of the common practices is the restriction of circulation velocity rather than maintenance or rehabilitation measures. The case study used is an excerpt from a railroad in Portugal, where the entire described process will be applied and consequently analysed. Therefore, this work intends to contribute to a more efficient planning of the railway maintenance and rehabilitation measures, based on a better use of the data resulting from the track inspection, through a multi-criteria analysis.
Fundamental study on countermeasures against subharmonic vibration of order 1/2 in automatic transmissions for cars
Authors: Takino Fumiya , Ryu Takahiro , Nakae Takashi , Matsuzaki Kenichiro , Ueno Risa
Published: October 2018

In automatic transmissions for cars, a damper is installed in the lock-up clutch to absorb torsional vibrations caused by combustion in the engine. Although a damper with low stiffness reduces the torsional vibration, low-stiffness springs are difficult to use because of space limitations. To address this problem, dampers have been designed using a piecewise-linear spring having three different stages of stiffness. However, a nonlinear subharmonic vibration of order 1/2 occurs because of the nonlinearity of the piecewise-linear spring in the damper. In this study, we experimentally and analytically examined a countermeasure against the subharmonic vibration by increasing the stages of the piecewise-linear spring using the one-degree-of-freedom system model. We found that the gap between the switching points of the piecewise-linear spring was the key to vibration reduction. The experimental results agreed with results of the numerical analyses.
Numerical analysis of the shielding effect provided by periodic elastic scatterers
Authors: Amado-Mendes Paulo , Godinho Luís , Alves-Costa Pedro , Castanheira-Pinto Alexandre , Albino Carlos
Published: October 2018

The search for innovative mitigation solutions that can be adopted in urban areas to efficiently reduce the effects of induced vibrations by increasing numbers of vehicles has motivated a significant number of researchers from different fields. An interesting concept seems to be the use of buried elastic inclusions, periodically arranged parallel to the ground surface, applying sonic crystal inspired technologies and bandgap filtering on adequate frequency ranges. In previous works, preliminary numerical results have shown the influence of the presence of multiple elastic heterogeneities on the attenuation of the vibration fields in receivers located on the opposite side from the traffic vibration source. Following this concept, a 2.5D numerical model has been implemented, based on the Finite Element Method (FEM) and on the use of a numerical absorbing layer. The effects on the vibration levels provided by a set of periodic elastic inclusions inserted in the host propagation medium are parametrically analysed. In fact, frequency domain results, obtained when modelling different configurations of the periodic structure and host soil, are used to assess the efficiency of these arrays as a mitigation measure.
Damage estimation on concrete gravity dams through artificial accelerograms
Authors: Zacchei Enrico , Molina José Luis
Published: October 2018

The aim of this paper is to analyse the damage on gravity dams through artificial earthquakes from two methods. The first procedure defines the performance and the response curve of concrete gravity dams using a harmonic function which establishes linear displacements. The other procedure to obtain the artificial earthquake defines the power spectral density function consistent with the response spectrum. This artificial accelerogram is necessary to quantify the response curve of concrete gravity dams in the time domain. The seismic activity in Spain is not frequent, therefore it is often difficult to select real accelerograms to perform a complete seismic analysis, which makes artificial accelerograms extremely useful. Finally, combining these two procedures, a damage index is determined for assessing the crack’s magnitude. These both efficient and practical procedures are useful to develop further complicated analysis.
Seismic vibration control using a novel inerto-elastic damper
Authors: Abdeddaim Mahdi , Kasar Arnav A. , Djedoui Nassim
Published: October 2018

The use of advanced structural control devices is an effective engineering solution to reduce earthquake induced damages to structures. Owing to rapid advancement in technology and persistent research efforts, a variety of control devices have been developed and successfully implemented. Quite recently, a new passive damper, called inerter has been introduced, which is capable of developing a fictive mass. This study presents a novel inerto-elastic damper, which combines the inerter devices with classical elastic springs, and demonstrates the effectiveness of these devices in achieving seismic response reduction. The inerto-elastic device employs the inerter and elastic spring in parallel to control the seismic structural response. The effectiveness of the inerto-elastic dampers has been demonstrated through the response of a multi-degree of freedom system subjected to seismic excitations. The results of the analysis show a significant reduction in the response of the structure with novel inerto-elastic damper, as compared to those of structures with normal elastic spring as well as no dampers. The response quantities of interest, considered for this study are top floor displacement, inter-storey drift and base shear. The study also underlines optimal parameters for the inerter fictive mass and the elastic spring stiffness on the basis of the results obtained.
A parametric study of a tower controlled by a pendulum tuned mass damper: beam modelling
Authors: Colherinhas Gino B. , Shzu Maura A. M. , Avila Suzana M. , de Morais Marcus V. G.
Published: October 2018

This paper models a tower with a passive Pendulum Tuned Mass Damper (PTMD) with Finite Elements (FE) using the resources and capabilities of commercial software ANSYS. Although structural control of high and slender towers using PTMDs are widely studied in literature, it was not found yet studies modelling the PTMD with ANSYS. This FE model is called by a routine coded in MATLAB to find the relation between the mass, length, stiffness, and damping coefficient of the pendulum in function of the high vibration amplitudes at the top of the tower (defined as a beam element type). This parametric study of the dynamic behaviour of the PTMD + FE beam structural model is analysed and its results are compared to a genetic optimization developed in other researches to find the best pendulum parameters.