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Journal articles on the topic 'Longitudinal dynamic behaviour'
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1
Dai, L., L. Xu, and B. Setiawan. "A new non-linear approach to analysing the dynamic behaviour of tank vehicles subjected to liquid sloshing." Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics 219, no. 1 (March 1, 2005): 75–86. http://dx.doi.org/10.1243/146441905x9944.
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This research presents a new approach to investigating the non-linear dynamic behaviour of partially filled tank vehicles under large-amplitude liquid sloshing. A non-linear impact model for liquid sloshing in partially filled liquid tank vehicles is established for investigating the longitudinal dynamic characteristics of tank vehicles under typical driving conditions. The dynamic fluid motion within the tank is modelled by utilizing an analogy system together with an impact subsystem for longitudinal oscillations. The forces on the fifth wheel and the axles of the vehicle are determined in considering the effects of the liquid sloshing in the tank. The non-linear dynamic behaviours of the tank vehicle subjected to liquid sloshing and the excitations generated by rough roads are analysed and compared with those of linear models. Numerical simulation of the tank vehicle under typical rough road conditions is performed.
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Pavliuk, A. V. "Dynamics of Three-layer Cylindrical Shells Elliptical Cross-Section With a Longitudinal-Transverse Discrete Ribbed Filler." Фізика і хімія твердого тіла 18, no. 2 (June 15, 2017): 243–48. http://dx.doi.org/10.15330/pcss.18.2.243-248.
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In this paper, we consider the equations of non-axisymmetric oscillations of discretely reinforced multilayer cylindrical shells of elliptical section. When analyzing the elements of the elastic structure, a refinement model of the theory of shells and rods of the Timoshenko type is used. The numerical method of solving the dynamic equations is based on the integro- interpolation method of constructing the finite-difference schemes for equations with discontinuous coefficients. The problem of dynamic behavior of a three-layer longitudinal-transversal reinforced cylindrical shell of an elliptical section under a distributed nonstationary load is investigated. A solution of the problem on dynamic behaviour of the three-layered cylindrical shell with some discrete longitudinal-transverse ribbed filler is considered for distributed non-stationary loading.
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Brzuzy, Aneta, and Grzegorz Bąk. "Stability analysis of steel compression members under shock loads." Bulletin of the Military University of Technology 67, no. 1 (April 3, 2018): 107–25. http://dx.doi.org/10.5604/01.3001.0011.8051.
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This paper presents the results of a numerical analysis of the elastic-plastic behaviour of steel compression members subjected to compression with a permanent pre-deformation in the longitudinal axis by a longitudinal indispensable shock load. A differential load intensity was considered up to the loss of stability. A finite difference method was applied, with an explicit integration schema for the time of the dynamic stability equations. It was assumed that the precursor to the unstable behaviour of a steel compression member was a continuous deformation of the rod axis, which was defined according to current industry-standard design procedures. Cases of flexible and stiff rods, varying in slenderness, were considered. It was demonstrated that a significant load on the performance of the steel compression members and their buckling mechanisms is attributable to longitudinal wave effects. These longitudinal wave effects cause high-frequency changes in the axial forces with a significant stress concentration due to the effect of reflection from a pinned support. This is critical for the dissipation of internal energy by plastic deformation. The applied research method facilitated an estimation of the dynamic critical forces and their relationships with static values. Keywords: steel rods with pre-deformation of axis, elastic-plastic behaviour, dynamic stability of rods, differential approximation, effects of axial wave response
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Taig, Gerard, and Gianluca Ranzi. "Generalised Beam Theory for composite beams with longitudinal and transverse partial interaction." Mathematics and Mechanics of Solids 22, no. 10 (July 8, 2016): 2011–39. http://dx.doi.org/10.1177/1081286516653799.
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This paper presents a Generalised Beam Theory formulation to study the partial interaction behaviour of two-layered prismatic steel–concrete composite beams. The novelty of the proposed approach is in its capacity to handle the deformability of the shear connections at the interface between the slab and steel beam in both the longitudinal and transverse directions in the evaluation of the deformation modes. This method falls within a category of cross-sectional analyses available in the literature for which a suitable set of deformation modes, including conventional, extension and shear, is determined from dynamic analyses of discrete planar frame models representing the cross-section. In this context, the shear connections are modelled using shear deformable spring elements. As a result, the in-plane partial shear interaction behaviour is accounted for in the planar dynamic analysis during the evaluation of the conventional and extension modes, while the longitudinal partial interaction behaviour associated with the shear modes is included in the out-of-plane dynamic analyses. In the case of the conventional modes, the longitudinal slip is accounted for in the post-processing stage where the warping displacements are determined. A numerical example of a composite box girder beam is presented and its structural response investigated for different levels of shear connection stiffness in both the longitudinal and transverse directions. The accuracy of the numerical results is validated against those obtained with a shell finite element model implemented in ABAQUS/Standard software.
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Hambrey, Michael J., and Julian A. Dowdeswell. "Flow regime of the Lambert Glacier-Amery Ice Shelf system, Antarctica: structural evidence from Landsat imagery." Annals of Glaciology 20 (1994): 401–6. http://dx.doi.org/10.3189/1994aog20-1-401-406.
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High-resolution visible and near-infrared satellite imagery provides a means of investigating the structural glaciology, and in turn the dynamics, of large ice masses. The Lambert Glacier-Amery Ice Shelf system is one of the largest ice drainage basins in Antarctica and has previously yielded conflicting evidence concerning its dynamic behaviour: either that the system has a propensity for surging or that it has a constant flow regime. Digital manipulation of Landsat imagery allows analysis of the structure of the glacier system, showing longitudinal foliation, medial moraines and crevasse patterns that provide no evidence of surging behavior during the residence time of ice in the glacier system.
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Hambrey, Michael J., and Julian A. Dowdeswell. "Flow regime of the Lambert Glacier-Amery Ice Shelf system, Antarctica: structural evidence from Landsat imagery." Annals of Glaciology 20 (1994): 401–6. http://dx.doi.org/10.1017/s0260305500016761.
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High-resolution visible and near-infrared satellite imagery provides a means of investigating the structural glaciology, and in turn the dynamics, of large ice masses. The Lambert Glacier-Amery Ice Shelf system is one of the largest ice drainage basins in Antarctica and has previously yielded conflicting evidence concerning its dynamic behaviour: either that the system has a propensity for surging or that it has a constant flow regime. Digital manipulation of Landsat imagery allows analysis of the structure of the glacier system, showing longitudinal foliation, medial moraines and crevasse patterns that provide no evidence of surging behavior during the residence time of ice in the glacier system.
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Bassi, Francesca. "Longitudinal models for dynamic segmentation in financial markets." International Journal of Bank Marketing 35, no. 3 (May 15, 2017): 431–46. http://dx.doi.org/10.1108/ijbm-05-2016-0068.
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Purpose Dynamic market segmentation is a very important topic in many businesses where it is interesting to gain knowledge on the reference market and on its evolution over time. Various papers in the reference literature are devoted to the topic and different statistical models are proposed. The purpose of this paper is to compare two statistical approaches to model categorical longitudinal data to perform dynamic market segmentation. Design/methodology/approach The latent class Markov model identifies a latent variable whose states represent market segments at an initial point in time, customers can switch to one segment to another between consecutive measurement occasions and a regression structure models the effects of covariates, describing customers’ characteristics, on segments belonging and transition probabilities. The latent class growth approach models individual trajectories, describing a behaviour over time. Customers’ characteristics may be inserted in the model to affect trajectories that may vary across latent groups, in the author’s case, market segments. Findings The two approaches revealed both suitable for dynamic market segmentation. The advice to marketer analysts is to explore both solutions to dynamically segment the reference market. The best approach will be then judged in terms of fit, substantial results and assumptions on the reference market. Originality/value The proposed statistical models are new in the field of financial markets.
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D’Alessandro, Marco, and Luigi Lombardi. "A Dynamic Framework for Modelling Set-Shifting Performances." Behavioral Sciences 9, no. 7 (July 18, 2019): 79. http://dx.doi.org/10.3390/bs9070079.
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Higher-order cognitive functions can be seen as a class of cognitive processes which are crucial in situations requiring a flexible adjustment of behaviour in response to changing demands of the environment. The cognitive assessment of these functions often relies on tasks which admit a dynamic, or longitudinal, component requiring participants to flexibly adapt their behaviour during the unfolding of the task. An intriguing feature of such experimental protocols is that they allow the performance of an individual to change as the task unfolds. In this work, we propose a Latent Markov Model approach to capture some dynamic aspects of observed response patterns of both healthy and substance dependent individuals in a set-shifting task. In particular, data from a Wisconsin Card Sorting Test were analysed in order to represent performance trends in terms of latent cognitive states dynamics. The results highlighted how a dynamic modelling approach can considerably improve the amount of information a researcher, or a clinician, can obtain from the analysis of a set-shifting task.
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Parnell, William J., and Riccardo De Pascalis. "Soft metamaterials with dynamic viscoelastic functionality tuned by pre-deformation." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 377, no. 2144 (March 18, 2019): 20180072. http://dx.doi.org/10.1098/rsta.2018.0072.
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The small amplitude dynamic response of materials can be tuned by employing inhomogeneous materials capable of large deformation. However, soft materials generally exhibit viscoelastic behaviour, i.e. loss and frequency-dependent effective properties. This is the case for inhomogeneous materials even in the homogenization limit when propagating wavelengths are much longer than phase lengthscales, since soft materials can possess long relaxation times. These media, possessing rich frequency-dependent behaviour over a wide range of low frequencies, can be termed metamaterials in modern terminology. The sub-class that are periodic are frequently termed soft phononic crystals although their strong dynamic behaviour usually depends on wavelengths being of the same order as the microstructure. In this paper we describe how the effective loss and storage moduli associated with longitudinal waves in thin inhomogeneous rods are tuned by pre-stress. Phases are assumed to be quasi-linearly viscoelastic, thus exhibiting time-deformation separability in their constitutive response. We illustrate however that the effective incremental response of the inhomogeneous medium does not exhibit time-deformation separability. For a range of nonlinear materials it is shown that there is strong coupling between the frequency of the small amplitude longitudinal wave and initial large deformation. This article is part of the theme issue ‘Rivlin's legacy in continuum mechanics and applied mathematics’.
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Nasir, Rizal E. M., and Wahyu Kuntjoro. "Longitudinal Flight Stability Augmentation of a Small Blended Wing-Body Aircraft with Canard as Control Surface." Applied Mechanics and Materials 393 (September 2013): 329–37. http://dx.doi.org/10.4028/www.scientific.net/amm.393.329.
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Transient response of an aircraft in longitudinal motion has two modes of oscillatory motion short period mode and phugoid modes and failure to achieve satisfactory level would mean poor flying and handling qualities leading to unnecessary pilot workload. This study proposes a stability augmentation system (SAS) in longitudinal flying modes for steady and level flight at all airspeeds and altitudes within Baseline-II E-2 BWBs operational flight envelope (OFE). The main controlling component of this stability augmentation system is a set of canard, a control surface located in front of the wing. It must be able to compensate Baseline-II E-2 BWB poor transient responses damping ratios so that good flying quality can be achieved. Observation from the transient responses of the unaugmented system signify high-frequency short-period oscillations with almost constant low damping ratio at an altitude, and low-frequency phugoid oscillation with varying damping ratio depending on airspeed. A conclusive behaviour of natural frequencies and damping ratios against dynamic pressure leads to the understanding on how dynamic pressure influences the flying qualities. Derivation of dynamic equations in terms of dynamic pressures enables one to design and device a feedback system to compensate poor flying qualities of the original unaugmented aircraft with conclusive relationship between important parameters and dynamic pressure are put in the overall dynamic equation. Two feedback gain systems, pitch attitude and pitch rate gains are scheduled based on dynamic pressure values and are combined into the aircraft longitudinal SAS. The proposed SAS has proven to be the suitable candidate for Baseline-II E-2 BWB as it is able to ensure Level 1 flying qualities, longitudinally.
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Uyulan, Caglar, and Ersen Arslan. "Simulation and time-frequency analysis of the longitudinal train dynamics coupled with a nonlinear friction draft gear." Nonlinear Engineering 9, no. 1 (February 7, 2020): 124–44. http://dx.doi.org/10.1515/nleng-2020-0003.
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AbstractTrain safety and operational efficiency can be improved by investigating the dynamics of the train under varying conditions. Longitudinal train dynamics (LTD) simulations performed for such purposes, usually by utilising a nonlinear time-domain model. This paper covers two modes of LTD results corresponding to the time domain and frequency domain analysis. Time-domain solutions are essential to evaluate the full response used for parameter optimisation and controller design studies while frequency domain solutions can provide significant but straightforward clues regarding system dynamics. An advanced draft gear model, which works under a four-stage process is constructed considering all structural components, geometric relationships, friction modelling and dynamic characteristics such as hysteresis, stiffening, state transition, locked unloading, softening. Then, this model is parametrically reduced and implemented into an LTD simulation. The simulation in the time domain is conducted assuming a locomotive connected with a nine wagon via “ode3” fixed-step solver. The transfer function among the first wagon acceleration (output) and the locomotive force (input) estimated through system identification methodology. Then, the identification results interpreted by investigating step-response characteristic and best response giving parameter set is selected. Next, the modal and spectral analysis performed to reveal the behaviour of the in-train forces and the effects of vibration. This paper discusses a reliable methodology for the longitudinal dynamic analysis of the multi-bodied train in time and frequency domain and clarifies in-train vibration behaviour under the existence of sophisticated draft gear.
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Běhal, Jiří, and Pavel Zděnek. "Dynamic behaviour of composite panels under acoustic loading." International Journal of Structural Integrity 11, no. 5 (November 19, 2019): 710–22. http://dx.doi.org/10.1108/ijsi-10-2018-0066.
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Purpose There are structural elements on the aircraft that may be exposed to high-intensity sound levels. One of them is an air inlet duct of the jet engine. To prepare data for the air duct damage tolerance analysis, flat panels were tested under acoustic loading. The paper aims to discuss this issue. Design/methodology/approach The acoustic fatigue test equipment for grazing wave’s incidence was designed based on the FE analyses. Flat composite panels were designed and manufactured using the Hexply 8552/AGP193-PW prepreg with the simulation of production imperfections or operational damage. The dynamic behaviour of panels has been tested using three regimes of acoustic loading: white noise spectrum, engine noise spectrum and discrete harmonic frequencies. The panel deflection was monitored along its longitudinal axis, and the ultrasonic NDT instruments were used for the monitoring of relevant delamination increments. The FE model of the panel was created in Abaqus to study panel dynamic characteristics. Findings No delamination progress was observed by NDT testing even if dynamic characteristics, especially modal frequency, of the panel changed during the fatigue test. Rayleigh damping coefficients were evaluated for their use in FE models. Significant differences were found between the measured and computed panel deflection curves near the edge of the panel. Originality/value The research results underscored the signification of the FE model boundary conditions and the element type selections when the panel works like a membrane rather than a plate because of their low bending stiffness.
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Wang, Xu Ming, Wen Zhang, and Ying Wang. "The Influence of Longitudinal Magnetic Field on DCEN MAG Welding." Applied Mechanics and Materials 217-219 (November 2012): 1843–46. http://dx.doi.org/10.4028/www.scientific.net/amm.217-219.1843.
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This paper introduces the dynamic process of droplet transfer of DCEN MAG welding applied outside longitudinal magnetic field, and analyses the influence law of magnetic parameters on welding arc, droplet transfer behaviour, wire melting coefficient and weld formation. The feasibility of application of longitudinal magnetic field to DCEN MAG welding is established. We compared DCEN MAG welding with DCEP in order to further perfect rotating MAG welding.
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Girbés, Vicent, Daniel Hernández, Leopoldo Armesto, Juan Dols, and Antonio Sala. "Drive Force and Longitudinal Dynamics Estimation in Heavy-Duty Vehicles." Sensors 19, no. 16 (August 11, 2019): 3515. http://dx.doi.org/10.3390/s19163515.
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Modelling the dynamic behaviour of heavy vehicles, such as buses or trucks, can be very useful for driving simulation and training, autonomous driving, crash analysis, etc. However, dynamic modelling of a vehicle is a difficult task because there are many subsystems and signals that affect its behaviour. In addition, it might be hard to combine data because available signals come at different rates, or even some samples might be missed due to disturbances or communication issues. In this paper, we propose a non-invasive data acquisition hardware/software setup to carry out several experiments with an urban bus, in order to collect data from one of the internal communication networks and other embedded systems. Subsequently, non-conventional sampling data fusion using a Kalman filter has been implemented to fuse data gathered from different sources, connected through a wireless network (the vehicle’s internal CAN bus messages, IMU, GPS, and other sensors placed in pedals). Our results show that the proposed combination of experimental data gathering and multi-rate filtering algorithm allows useful signal estimation for vehicle identification and modelling, even when data samples are missing.
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Fox, S., R. Collins, and J. Boxall. "Dynamic Leakage: Physical Study of the Leak Behaviour of Longitudinal Slits in MDPE Pipe." Procedia Engineering 89 (2014): 286–89. http://dx.doi.org/10.1016/j.proeng.2014.11.189.
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Van Berg, G. J. Den, M. Lindeboom, and G. Ridder. "Attrition in longitudinal panel data and the empirical analysis of dynamic labour market behaviour." Journal of Applied Econometrics 9, no. 4 (October 1994): 421–35. http://dx.doi.org/10.1002/jae.3950090408.
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Krishna, Visakh V., Mats Berg, and Sebastian Stichel. "Tolerable longitudinal forces for freight trains in tight S-curves using three-dimensional multi-body simulations." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 234, no. 5 (April 16, 2019): 454–67. http://dx.doi.org/10.1177/0954409719841794.
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With the need for increasing length of freight trains, the longitudinal train dynamics and its influence on the running safety become a key issue. Longitudinal train dynamics is a complex issue with contributions from both the vehicle and the operating conditions such as infrastructure design, braking regimes, etc. Standards such as the UIC Code 530-2 and EN-15839 detail the procedure for on-track propelling tests that should be conducted to determine the running safety of a single wagon. Also, it only considers a single S-curve and specifies neighbouring wagons and buffers. Hence, the resulting longitudinal train dynamics would not be able to judge the effects of various heterogeneities in the train formation such as the adjacent wagons, buffer types, carbody torsional stiffnesses, curvatures, etc. Here, there is a potential of using three-dimensional multi-body simulations to develop a methodology to judge the running safety of a train with regard to its longitudinal dynamic behaviour, subjected to various heterogeneities. In this study, a tool based on three-dimensional multi-body simulations has been developed to provide longitudinal compressive force limits and tolerable longitudinal compressive force for wagon combinations passing through S-curves of varying curvatures, and the sensitivities of the various heterogeneities present in the train are assessed. The methodology is applied to open wagons of the ‘Falns’ type on tight S-curves by calculating the corresponding tolerable longitudinal compressive force, and the effect of various parameters on the same is discussed.
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Dumitriu, Mădălina. "Influence of the Longitudinal and Lateral Suspension Damping on the Vibration Behaviour in the Railway Vehicles." Archive of Mechanical Engineering 62, no. 1 (March 1, 2015): 115–40. http://dx.doi.org/10.1515/meceng-2015-0008.
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Abstract The paper focuses on the influence of the longitudinal and lateral suspension damping in correlation with the velocity upon the vibration behaviour of the railway vehicles while moving on a tangent track. The numerical simulations are developed based on a linear model of a 17-degree of freedom vehicle that allows the evaluation of the dynamic behaviour of the vehicle in a sub-critical velocity. Based on the response frequency functions of the vehicle in a harmonic and in a random behaviour, a series of basic properties of the stable behaviour of the forced lateral vibrations has been made evident, as well as the opportunities to lower the level of the carbody vibrations by changing the suspension damping.
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Lechner, D., and C. Perrin. "The Actual Use of the Dynamic Performances of Vehicles." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 207, no. 4 (October 1993): 249–56. http://dx.doi.org/10.1243/pime_proc_1993_207_190_02.
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INRETS (France) has carried out research work to determine to what extent drivers make use of the dynamic performances of vehicles in the course of everyday driving. A sample of drivers from varied backgrounds drove over a set distance, including all types of road infrastructures, at the wheel of a specially instrumented vehicle. The data analysis shows that longitudinal and lateral accelerations are low in everyday driving. Significant inter-individual variations in the behaviour of drivers, when at the wheel of the same vehicle, over the same stretch of road, were also revealed.
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Ezenwa, Vanessa O., and Matthew H. Snider. "Reciprocal relationships between behaviour and parasites suggest that negative feedback may drive flexibility in male reproductive behaviour." Proceedings of the Royal Society B: Biological Sciences 283, no. 1831 (May 25, 2016): 20160423. http://dx.doi.org/10.1098/rspb.2016.0423.
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Parasites are ubiquitous components of the environment that contribute to behavioural and life-history variation among hosts. Although it is well known that host behaviour can affect parasite infection risk and that parasites can alter host behaviour, the potential for dynamic feedback between these processes is poorly characterized. Using Grant's gazelle ( Nanger granti ) as a model, we tested for reciprocal effects of behaviour on parasites and parasites on behaviour to understand whether behaviour–parasite feedback could play a role in maintaining variation in male reproductive behaviour. Adult male gazelles either defend territories to attract mates or reside in bachelor groups. Territoriality is highly variable both within- and between-individuals, suggesting that territory maintenance is costly. Using a combination of longitudinal and experimental studies, we found that individual males transition frequently between territorial and bachelor reproductive status, and that elevated parasite burdens are a cost of territoriality. Moreover, among territorial males, parasites suppress aspects of behaviour related to territory maintenance and defence. These results suggest that territorial behaviour promotes the accumulation of parasites in males, and these parasites dampen the very behaviours required for territory maintenance. Our findings suggest that reciprocal feedback between host behaviour and parasitism could be a mechanism maintaining variation in male reproductive behaviour in the system.
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Mokhtari, Fatemeh, Geoffrey M. Spinks, Sepidar Sayyar, and Javad Foroughi. "Dynamic Mechanical and Creep Behaviour of Meltspun PVDF Nanocomposite Fibers." Nanomaterials 11, no. 8 (August 23, 2021): 2153. http://dx.doi.org/10.3390/nano11082153.
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Piezoelectric fibers have an important role in wearable technology as energy generators and sensors. A series of hybrid nanocomposite piezoelectric fibers of polyinylidene fluoride (PVDF) loaded with barium–titanium oxide (BT) and reduced graphene oxide (rGO) were prepared via the melt spinning method. Our previous studies show that high-performance fibers with 84% of the electroactive β-phase in the PVDF generated a peak output voltage up to 1.3 V and a power density of 3 W kg−1. Herein, the dynamic mechanical and creep behavior of these fibers were investigated to evaluate their durability and piezoelectric performance. Dynamic mechanical analysis (DMA) was used to provide phenomenological information regarding the viscoelastic properties of the fibers in the longitudinal direction. DSC and SEM were employed to characterize the crystalline structure of the samples. The storage modulus and the loss tangent increased by increasing the frequency over the temperature range (−50 to 150 °C) for all of the fibers. The storage modulus of the PVDF/rGO nanocomposite fibers had a higher value (7.5 GPa) in comparison with other fibers. The creep and creep recovery behavior of the PVDF/nanofillers in the nanocomposite fibers have been explored in the linear viscoelastic region at three different temperatures (10–130 °C). In the PVDF/rGO nanocomposite fibers, strong sheet/matrix interfacial interaction restricted the mobility of the polymer chains, which led to a higher modulus at temperatures 60 and 130 °C.
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Widmann, Andreas, and Regina H. Mulder. "Team learning behaviours and innovative work behaviour in work teams." European Journal of Innovation Management 21, no. 3 (August 13, 2018): 501–20. http://dx.doi.org/10.1108/ejim-12-2017-0194.
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Purpose The purpose of this paper is to get deeper insight into the complex nature of the relationship between team learning conditions, team learning behaviours (TLBs) and innovative work behaviour (IWB) by considering and combining different neglected aspects in research. Design/methodology/approach A questionnaire was filled out by 593 vocational educators of 117 interdisciplinary work teams in vocational colleges in Germany. Correlations were calculated and structural equation modelling at two levels was conducted. Findings The results indicate that TLBs, especially team reflexivity and boundary spanning, relate positively to IWB. Furthermore, team structure, task interdependence and group potency relate positively to TLBs. It means that TLBs can be fostered by establishing these team learning conditions and, thus, IWB can be fostered. Research limitations/implications The main limitation of the study is that the data collection was cross-sectional. Longitudinal studies are required to capture the dynamic character of team learning and to identify causal relationships. Practical implications It is important to make all employees in vocational education aware of the importance of TLBs especially of team reflexivity and boundary spanning. Originality/value This study provides practical implications for organisations to foster IWB and indications for a better understanding of the relationship between team learning conditions, TLBs and IWB considering and combining different neglected aspects such as examining TLBs separated in one study.
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Krebs, G., M. A. Waszczuk, H. M. S. Zavos, D. Bolton, and T. C. Eley. "Genetic and environmental influences on obsessive–compulsive behaviour across development: a longitudinal twin study." Psychological Medicine 45, no. 7 (December 12, 2014): 1539–49. http://dx.doi.org/10.1017/s0033291714002761.
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BackgroundLittle is known about the factors influencing the stability of obsessive–compulsive behaviour (OCB) from childhood to adolescence. The current study aimed to investigate: (1) the stability of paediatric OCB over a 12-year period; (2) the extent to which genetic and environmental factors influence stability; and (3) the extent to which these influences are stable or dynamic across development.MethodThe sample included 14 743 twins from a population-based study. Parental ratings of severity of OCB were collected at ages 4, 7, 9 and 16 years.ResultsOCB was found to be moderately stable over time. The genetic influence on OCB at each age was moderate, with significant effects also of non-shared environment. Genetic factors exerted a substantial influence on OCB persistence, explaining 59–80% of the stability over time. The results indicated genetic continuity, whereby genetic influences at each age continue to affect the expression of OCB at subsequent ages. However, we also found evidence for genetic attenuation in that genetic influences at one age decline in their influence over time, and genetic innovation whereby new genes ‘come on line’ at each age. Non-shared environment influenced stability of OCB to a lesser extent and effects were largely unique to each age and displayed negligible influences on OCB at later time points.ConclusionsOCB appears to be moderately stable across development, and stability is largely driven by genetic factors. However, the genetic effects are not entirely constant, but rather the genetic influence on OCB appears to be a developmentally dynamic process.
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Vincent, C., M. Vallon, L. Reynaud, and E. Le Meur. "Dynamic behaviour analysis of glacier de Saint Sorlin, France, from 40 years of observations, 1957–97." Journal of Glaciology 46, no. 154 (2000): 499–506. http://dx.doi.org/10.3189/172756500781833052.
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AbstractMass-balance and dynamic measurements carried out on glacier de Saint Sorlin since 1957 provide a good opportunity to study the dynamics of this glacier. Ice-flow analysis shows that dynamic changes have been important over the last 40 years and that these changes are not consistent with the concepts usually used in glacier modelling. Present velocities are larger than the 1960 velocities, although the thickness decreased everywhere (10–30 m in the ablation zone). A simple numerical ice-flow model which does not include longitudinal stress gradients has been used to investigate these phenomena. This model allows us to infer the sliding velocity from observed surface and calculated deformation velocities. We conclude that: (1) the sliding velocity cannot be described by Weertman analysis or empirical relations which link the sliding to the thickness and surface slope; (2) the inferred sliding velocity is uniform over at least half of the glacier; and (3) there is no clear link between the sliding process and the quantity of water coming from surface ablation. Furthermore, it may not be reasonable to calibrate model flow parameters from geometry changes because the surface geometry is relatively insensitive to velocity changes over some decades.
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Kaczmarczyk, Stefan, and Seyed Mirhadizadeh. "Modelling, Simulation and Experimental Validation of Nonlinear Dynamic Interactions in an Aramid Rope System." Applied Mechanics and Materials 706 (December 2014): 117–27. http://dx.doi.org/10.4028/www.scientific.net/amm.706.117.
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Vibration phenomena taking place in lifting and hoist installations may influence the dynamic performance of their components. For example, in an elevator system they may affect ride quality of a lift car. Lateral and longitudinal vibrations of suspension ropes and compensating cables may result in an adverse dynamic behaviour of the entire installation. Thus, there is a need to develop reliable mathematical and computer simulation models to predict the dynamic behaviour of suspension rope and compensating cable systems. The aim of this paper is to develop a model of an aramid suspension rope system in order to predict nonlinear modal interactions taking place in the installation. A laboratory model comprising an aramid suspension rope, a sheave/ pulley assembly and a rigid suspended mass has been studied. Experimental tests have been conducted to identify modal nonlinear couplings in the system. The dynamic behaviour of the model has been described by a set of nonlinear partial differential equations. The equations have been solved numerically. The numerical results have been validated by experimental tests. It has been shown that the nonlinear couplings may lead to adverse modal interactions in the system.
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Hadytama, Muhammad Rafi, and Rianto A. Sasongko. "Dynamics Simulation and Analysis of Transition Stage of Tilt-Rotor Aircraft." Applied Mechanics and Materials 842 (June 2016): 251–58. http://dx.doi.org/10.4028/www.scientific.net/amm.842.251.
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This paper presents the flight dynamics simulation and analysis of a tilt-rotor vertical takeoff and landing (VTOL) aircraft on transition phase, that is conversion from vertical or hover to horizontal or level flight and vice versa. The model of the aircraft is derived from simplified equations of motion comprising the forces and moments working on the aircraft in the airplane's longitudinal plane of motion. This study focuses on the problem of the airplane's dynamic response during conversion phase, which gives an understanding about the flight characteristics of the vehicle. The understanding about the flight dynamics characteristics is important for the control system design phase. Some simulation results are given to provide better visualization about the behaviour of the tilt-rotor. The simulation results show that both transition phases are quite stable, although an improved stability can give better manoeuver and attitude handling. Improvement on the simulation model is also required to provide more accurate and realistic dynamic response of the vehicle.
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Kushvaha, Vinod, S. Anand Kumar, Priyanka Madhushri, and Aanchna Sharma. "Artificial neural network technique to predict dynamic fracture of particulate composite." Journal of Composite Materials 54, no. 22 (March 8, 2020): 3099–108. http://dx.doi.org/10.1177/0021998320911418.
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In this paper, the artificial neural network technique using a multi-layer perceptron feed forward scheme was used to model and predict the mode-I fracture behaviour of particulate polymer composites when subjected to impact loading. A neural network consisting of three-layers was employed to develop the network. Artificial neural network was constructed using six input parameters such as shear wave speed ( CS), density ( D), elastic modulus ( Ed), longitudinal wave speed ( CL), volume fraction ( Vf) and time ( t). The influence of input parameters on the output stress intensity factor and crack-initiation fracture toughness were found to be in the order of t > CS > D > Ed > CL > Vf. The degree of accuracy of prediction was 92.7% for stress intensity factor. In this regard, artificial neural network can be used in the modelling and prediction of fracture behaviour of particulate polymer composites under impact loading.
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Haberzettl, Sebastian, Alexander K. Zschocke, and Frank Gauterin. "A new method for studying the longitudinal dynamic behaviour of a suspension on a test rig." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 230, no. 8 (September 9, 2015): 1027–39. http://dx.doi.org/10.1177/0954407015601265.
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Beeh, Elmar, Horst E. Friedrich, Michael Kriescher, Philipp Straßburger, Gundolf Kopp, Ping Zhou, Harald Kraft, and Hussam Abu El-Hija. "Peeling of Aluminium Tubes as an Efficient Method for Energy Absorption in Vehicle Front Structures." Materials Science Forum 765 (July 2013): 798–802. http://dx.doi.org/10.4028/www.scientific.net/msf.765.798.
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Current crash structures in cars are still using the buckling of metallic structures to absorb the kinetic energy in case of an impact. The disadvantage of this technology is that changes within the static structural behaviour, like e.g. the stiffness or eigenfrequencies, will cause changes in the crash behaviour, even if this is not desired. This correlation between static and dynamic behaviour causes many development loops to adjust the crash behaviour, e.g. through optimizing trigger geometries which lower the initial crash forces. The German Aerospace Center (DLR) - Institute of Vehicle Concepts has developed a novel method to offer an efficient way of absorbing energy by peeling the outer skin of load bearing structures, like the crash boxes and the longitudinal rails. This technology provides an adjustable force level without changing the static behaviour of the front structure itself. This property offers the opportunity to create adaptable crash behaviour with only smallest changes within the peeling depth. Furthermore, it is possible to generate close to ideal force-deflection curves, which offers the potential to achieve high specific energy absorption. The DLR will show results of static and dynamic testing of crash tubes and of a vehicle front structure equipped with this mechanism. In addition the implementation of the methodology into the dynamic simulation with LS-Dyna will be shown. Benefits and limitations of this novel energy absorption method will be discussed.
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Foti, Dora. "On the Optimum Placement of Dissipators in a Steel Model Building Subjected to Shaking-Table Tests." Open Construction and Building Technology Journal 8, no. 1 (October 1, 2014): 142–52. http://dx.doi.org/10.2174/1874836801408010142.
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The following research presents the numerical and experimental results obtained on a reduced scale steel model of a medium-rise building structure dynamically protected with energy dissipaters. The steel-steel friction dissipates energy as the structure undergoes interstory drifts. A preliminary numerical analysis is performed to determine the best position of the friction dampers in the longitudinal frames. All the nodes of the numerical model have been assumed with the same bending stiffness. Shaking table tests have been performed, both in random vibration tests (to determine the natural periods and the dynamic characteristics of the model) and in earthquake simulation tests (to study the dynamic behaviour of the model with and without dampers). The results have been compared to those achieved during a previous experimental study based on the same model protected with only one friction damper for each longitudinal frame.
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Zeng, Fei, Cheng Yan, Qing Wu, and Tao Wang. "Dynamic Behaviour of a Conveyor Belt Considering Non-Uniform Bulk Material Distribution for Speed Control." Applied Sciences 10, no. 13 (June 27, 2020): 4436. http://dx.doi.org/10.3390/app10134436.
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For the conveyor belt, variable material flow influences the energy efficiency of the speed control technology significantly. The fluctuation of material flow on the conveyor belt will lead to the detrimental vibrations on both the belt and the conveyor while the conveyor works at certain speeds. In order to improve the model inaccuracy caused by the uniform bulk material flow assumption in the current conveyor belt model, the paper establishes a high-precision dynamic model that can consider speed control of a conveyor belt under non-uniform bulk material transportation. In this dynamic model, a non-uniform bulk material distribution model is firstly proposed based on laser scanning technology. Then, a high-precision longitudinal dynamic model is proposed to investigate the dynamic behavior of a belt conveyor. Considering the micro-units of actual load on a conveyor belt, it can well describe the transient state of the conveyor belt. These models can be used to determine the optimal speed for safety and energy conservation in operation. Experimental results are used to validate the proposed dynamic model for analyzing belt mechanical behavior under non-uniform bulk material distribution on the belt. The results show that the proposed models can be used for optimizing the operating procedures of belt conveyor systems.
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Ametorwo, Aaron Makafui, Daniel Ofori, Francis Annor, and Kwasi Dartey-Baah. "Work-family conflict as antecedent to workplace deviance: a study among bankers." African Journal of Management Research 28, no. 1 (August 18, 2022): 90–104. http://dx.doi.org/10.4314/ajmr.v28i1.7.
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Hinged on the Job Demand-Resource model and Source Attribution Theory, this study assessed the relationship between work-family conflict (family-towork and work-to-family conflicts) and workplace deviant behaviours (organizational and interpersonal deviance) among bank employees in Ghana. The quantitative two-wave longitudinal design was used, and data collected from 301 respondents. Unique self-generated codes were used to match the responses from each respondent in both times. Work-to-family conflict predicted interpersonal deviant behaviour in both Time 1 and Time 2, and organizational deviant behaviour in Time 2 but not in Time 1. Also, family-to-work conflict predicted interpersonal deviant behaviour in both Time 1 and Time 2 and also predicted organizational deviant behaviour in Time 1 only. This is one of the few empirical studies assessing the relationship between work-family conflict and workplace deviance, and in particular, among bankers. Assessing such relationships in this study over time has shown that variations in nature of the hypothesized relationships could be a result of extraneous variables (dynamic employee behaviour or environmental changes) not anticipated. Banks must pay particular attention to the job demands imposed on employees and again take interest in the out-of-job experiences of staff that could affect their job performance and involvement in deviant behaviours.
Keywords: Work-family conflict; workplace deviance; bankers; Ghana; antecedents
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Zhang, Yangkun, Tien-Fu Lu, and Wei Gao. "Equivalent homogeneous model of D31-mode longitudinal piezoelectric transducers." Journal of Intelligent Material Systems and Structures 28, no. 19 (February 20, 2017): 2651–58. http://dx.doi.org/10.1177/1045389x17692054.
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This article focuses on modelling of D31-mode longitudinal piezoelectric transducers. A simple equivalent one-dimensional homogeneous model of D31-mode longitudinal piezoelectric transducers is proposed in this article. Homogeneous properties of the model are derived by a simple analytical mixing method based on the operation principle of D31-mode longitudinal piezoelectric transducers. Compared with other models in the literature, the proposed homogeneous model can consider passive layers in D31-mode longitudinal piezoelectric transducers for more accurate predictions in either static or dynamic behaviour. The proposed model is validated by a three-dimensional finite element model. Besides, based on the homogeneous model and borrowing the network theory, an exact equivalent circuit is formulated. A more straightforward form of the equivalent circuit can further facilitate analysis and modelling of D31-mode longitudinal piezoelectric transducers. Also, the proposed homogeneous model is wrapped into a transfer matrix form. The formulated transfer matrix of D31-mode longitudinal piezoelectric transducers can be used with the transfer matrix method to facilitate the calculations, when D31-mode longitudinal piezoelectric transducers are connected with numerous mediums in the operation direction. The effectiveness of the equivalent circuit and the transfer matrix is also verified.
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Mazhar, Farrukh, Mohammad A. Choudhry, and Muhammad Shehryar. "Nonlinear auto-regressive neural network for mathematical modelling of an airship using experimental data." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, no. 7 (June 18, 2018): 2549–69. http://dx.doi.org/10.1177/0954410018783131.
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Autonomous flight of an aerial vehicle requires a sufficiently accurate mathematical model, which can capture system dynamics in the presence of external disturbances. Artificial neural network is known for ideal in capturing systems behaviour, where little knowledge about vehicle dynamics is available. In this paper, we explored this potential of artificial neural network for characterizing nonlinear dynamics of an unmanned airship. The flight experimentation data for an outdoor experimental airship are acquired through a series of pre-determined flight tests. The experimental data are subjected to a class of dynamic recurrent neural network model dubbed as nonlinear auto-regressive model with exogenous inputs for training. Sufficiently trained neural network model captured and demonstrated the longitudinal dynamics of the airship satisfactorily. We also demonstrated the usefulness of proposed technique for Lotte airship, wherein the performance of proposed model is validated and analysed for the Lotte airship flight test data.
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Chen, P.-C., S.-L. Wu, and K.-Y. Chang. "Output feedback control with H∞ performance for saturated linear systems with magnitude and rate constraints." Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 225, no. 7 (August 29, 2011): 1005–17. http://dx.doi.org/10.1177/2041304110394537.
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The dynamic behaviour of controlled systems depend significantly on the allowable magnitude and change rate of the control efforts, which need to be considered during controller design. The controller design algorithm investigated in this paper can independently address both the magnitude and rate constraints and their effect on actuator dynamics. The integral dynamics are augmented to the systems actuator. The original control effort is formulated as new states in the augmented dynamics formulation, and the inputs of the integrator represent the rate of the control effort. The feedback gain is then designed to obtain suitable actuator dynamics such that the desired H∞ performance can be optimized and the magnitude of the rate constraints can be satisfied. Using satellite attitude control and aircraft longitudinal control as case studies, the effectiveness of the proposed algorithm is verified through achievable H∞ performance and time response simulations with various chosen constraints on the magnitude and rate of the control.
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Wu, Yuexing, Jianting Zhou, Jinquan Zhang, Qiang Wen, and Xuan Li. "Train-Bridge Dynamic Behaviour of Long-Span Asymmetrical-Stiffness Cable-Stayed Bridge." Shock and Vibration 2021 (November 18, 2021): 1–15. http://dx.doi.org/10.1155/2021/8512197.
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Long-span cable-stayed bridge (LCB) with unequal-height towers is being designed and constructed in metro lines due to its better adaptability to environment and terrain conditions compared to traditional cable-stayed bridge with equal-height towers. However, the asymmetrical arrangement of towers leads to obvious nonuniformity of the structural stiffness along the longitudinal direction, which intensifies the wheel-rail coupled vibration behaviour, and affects the running safety of operating trains and ride comfort. Therefore, train-bridge dynamic behaviour of long-span asymmetrical-stiffness cable-stayed bridge is deeply investigated in this work. Primarily, considering the comprehensive index of frequency difference and modal assurance criterion (MAC), a nonlinear model updating technique (NMUT) based on penalty function theory is proposed, which can be used to optimize the bridge numerical model. Secondly, on the basis of the train-track-bridge dynamic interaction theory (TDIT), a train-track-bridge coupled dynamic model (TCDM) is established. Finally, a LCB with unequal-height towers is applied as a case to illustrate the influence of asymmetrical stiffness on the train-track-bridge dynamic characteristics. Results show that the proposed NMUT is efficacious and practical. For the LCB with unequal-height towers, a significant difference between the bridge vibration at low tower location and that at high tower location appears. The vertical displacement difference of the main beam on both sides of the bridge increases with the distance from the observation point to the bridge tower increasing. The variation of acceleration difference on both sides of the bridge is influenced by the speed of the train and the position of the observation point simultaneously. In general, vibrations of the main beam at low tower location are larger than those at high tower location.
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Hogan, L. S., L. M. Wotherspoon, S. Beskhyroun, and J. M. Ingham. "Modal identification of a bridge-abutment system using forced vibration testing." Bulletin of the New Zealand Society for Earthquake Engineering 45, no. 4 (December 31, 2012): 161–70. http://dx.doi.org/10.5459/bnzsee.45.4.161-170.
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During the 2010 Mw7.1 Darfield earthquake, the single span Davis Road Bridge located 5 km southeast of Lincoln, New Zealand, sustained significant lateral spreading damage to the western approach. While lateral spreading resulted in up to 450 mm of approach settlement and evidence of damage to the pile foundations, the bridge superstructure sustained no significant damage. Prior to reinstating traffic, the bridge was used for full scale dynamic testing to characterise the influence of different substructure components on the lateral dynamic behaviour of the bridge superstructure.
The bridge was characterised using an eccentric mass shaker and an array of accelerometers to perform lateral forced vibration testing in both the transverse and longitudinal directions. Modal properties were extracted from these tests using multiple system identification algorithms. The experimental testing and system identification methodology are described here. Forced vibration testing was able to detect one mode in each principal direction of the bridge, with the fundamental modes for the transverse and longitudinal direction occurring at a period of 0.118 s and 0.092 s respectively. The torsional response found during the transverse direction shaking was most likely due to the effect of gap opening around the piles on the western abutment, while the longitudinal response was dominated by the approach soil.
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Lionetto, Francesca, Francesco Montagna, and Alfonso Maffezzoli. "Ultrasonic Dynamic Mechanical Analysis of Polymers." Applied Rheology 15, no. 5 (October 1, 2005): 326–35. http://dx.doi.org/10.1515/arh-2005-0016.
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Abstract The propagation of ultrasonic waves in polymers depends on their viscoelastic behaviour and density, resulting significantly affected by phase transitions occurring with changing temperature and pressure or during chemical reactions. Therefore, the application of low intensity ultrasound, acting as a high frequency dynamic mechanical deformation applied to a polymer, can monitor the changes of viscoelastic properties associated with the glass transition, the crystallization, the physical or chemical gelation, the crosslinking. Thanks to the non-destructive character (due to the very small deformation amplitude), low intensity ultrasound can be successfully used for polymer characterization. Moreover, this technique has a big potential as a sensor for on-line and in-situ monitoring of production processes for polymers or polymer matrix composites. Recently, in the laboratory of Polymeric Materials of Lecce University a custom made ultrasonic set-up for the characterization of polymeric material, even at high temperatures, has been developed. The ultrasonic equipment is coupled with a rotational rheometer. Ultrasonic waves and shear oscillations at low frequency can be applied simultaneously on the sample, getting information on its viscoelastic behaviour over a wide frequency range. The aim of this paper is to present the potential and reliability of the ultrasonic equipment for the ultrasonic dynamic mechanical analysis (UDMA) of both thermosetting and thermoplastic polymers. Three applications of UDMA to different polymeric systems will be reviewed, concerning the cross-linking of a thermosetting resin, the crystallisation from melt of a semicrystalline polymer and the water sorption in a dry hydrogel film. From the ultrasonic velocity and attenuation measurements, the viscoelastic properties of the tested polymers are evaluated in terms of complex longitudinal modulus and compared with the results of conventional dynamic mechanical analysis, carried out at low frequency.
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Dulinska, Joanna M., and Anna Galuszka. "3D Vs. 2D Modeling of Concrete Gravity Dam Subjected to Mining Tremor." Applied Mechanics and Materials 405-408 (September 2013): 2015–19. http://dx.doi.org/10.4028/www.scientific.net/amm.405-408.2015.
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The paper indicates the role of 3D modeling of concrete gravity dams in evaluation of dynamic response of dams to mining tremors which occur in mining activity regions. 2D and 3D models of a concrete gravity dam were prepared in order to compare two-and three-dimensional analysis of the dynamic response of dam to mining shock. Firstly, values of natural frequencies obtained for 2D and 3D models occurred to be very similar, but only the 3D model allowed to predict the dam behaviour under longitudinal kinematic excitation. Secondly, the comparison of the maximal principal stresses obtained for 2D and 3D models indicates that the simplified 2D analysis underestimates the values of dynamic response on about 20 %. Three-dimensional dynamic analysis allows to assess internal stresses resulting from mining shock more precisely, since the amplitudes of ground vibrations during mining tremors are comparable in three directions.
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Dulinska, Joanna. "3D vs. 2D Modeling of Concrete Gravity Dam Subjected to Mining Tremor." Applied Mechanics and Materials 325-326 (June 2013): 1324–28. http://dx.doi.org/10.4028/www.scientific.net/amm.325-326.1324.
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The paper indicates the role of 3D modeling of concrete gravity dams in evaluation of dynamic response of dams to mining tremors which occur in mining activity regions. 2D and 3D models of a concrete gravity dam were prepared in order to compare two-and three-dimensional analysis of the dynamic response of dam to mining shock. Firstly, values of natural frequencies obtained for 2D and 3D models occurred to be very similar, but only the 3D model allowed to predict the dam behaviour under longitudinal kinematic excitation. Secondly, the comparison of the maximal principal stresses obtained for 2D and 3D models indicates that the simplified 2D analysis underestimates the values of dynamic response on about 20 %. Three-dimensional dynamic analysis allows to assess internal stresses resulting from mining shock more precisely, since the amplitudes of ground vibrations during mining tremors are comparable in three directions.
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Messmann, Gerhard, and Regina H. Mulder. "A short measure of innovative work behaviour as a dynamic, context-bound construct." International Journal of Manpower 41, no. 8 (April 6, 2020): 1251–67. http://dx.doi.org/10.1108/ijm-01-2019-0029.
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PurposeThis contribution aims at providing a measure of the overall construct of innovative work behaviour (IWB). As a consequence of the construct's dynamic, context-bound nature, the measure of IWB is based on concrete work activities, captures social and reflective activities, and is context-bound. By employing a short, one-dimensional measurement scale, the instrument enables valuable scientific and practical insights in an economical way.Design/methodology/approachThe measure of IWB was evaluated with two samples of employees in different work contexts by conducting psychometric analyses, reliability analyses, exploratory and confirmatory factor analyses and correlation analyses with criterion variables.FindingsThe study provides evidence for the psychometric quality, reliability and validity of the measure of IWB.Research limitations/implicationsThe measure can be used to efficiently measure overall IWB. It thus enables the investigation of complex research models involving intervening mechanisms, interactions, or longitudinal effects. Further validation in other work domains and the inclusion of other criterion variables, such as innovative outcomes, is advised.Practical implicationsThe measure is useful for organizational practitioners to efficiently assess employees' IWB, to determine needs for supporting IWB at organizational level, and as a conceptual guideline for designing training or giving performance feedback during innovation projects.Originality/valueThe measure enables insights into the question how IWB can be fostered in practice. In addition, the contribution highlights that a measure of IWB needs to account for the construct's dynamic, context-bound nature and pay attention to usability as an important but often neglected quality criterion.
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Saramago, Gabriel, Pedro Aires Montenegro, Diogo Ribeiro, Artur Silva, Sergio Santos, and Rui Calçada. "Experimental Validation of a Double-Deck Track-Bridge System under Railway Traffic." Sustainability 14, no. 10 (May 10, 2022): 5794. http://dx.doi.org/10.3390/su14105794.
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This article describes the experimental and numerical evaluation of the dynamic behaviour of the Cascalheira bridge, located on the Northern Line of the Portuguese railway network. The bridge has a short span formed by two filler-beam half-decks, each one accommodating a railway track. The study includes the development of a finite element numerical model in ANSYS® software, as well as in situ dynamic characterization tests of the structure, namely ambient vibration tests, for the estimation of natural frequencies, modes shapes and damping coefficients, and a dynamic test under railway traffic, particularly for the passage of the Alfa Pendular train. The damping coefficients’ estimation was performed based on the Prony method, which proved effective in situations where the classical methods (e.g., decrement logarithm) tend to fail, particularly in the case of mode shapes with closed natural frequencies, as typically happens with the first vertical bending and torsion modes. The updating of the numerical model of the bridge was carried out using an iterative methodology based on a genetic algorithm, allowing an upgrade of the agreement between the numerical and experimental modal parameters. Particular attention was given to the characterization of the ballast degradation over the longitudinal joint between the two half-decks, given its influence in the global dynamic behavior of this type of double-deck bridges. Finally, the validation of the numerical model was performed by comparing the acceleration response of the structure under traffic actions, by means of numerical dynamic analyses considering vehicle-bridge interaction and including track irregularities, with the ones obtained by the dynamic test under traffic actions. The results of the calibrated numerical model showed a better agreement with the experimental results based on the accelerations evaluated in several measurement points located in both half-decks. In the validation process the vertical stiffness of the supports, as well as the degradation of the ballast located over the longitudinal joint between half-decks, was demonstrated to be relevant for the accuracy and effectiveness of the numerical models.
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Danvers, Alexander F., David A. Sbarra, and Matthias R. Mehl. "Understanding Personality through Patterns of Daily Socializing: Applying Recurrence Quantification Analysis to Naturalistically Observed Intensive Longitudinal Social Interaction Data." European Journal of Personality 34, no. 5 (September 2020): 777–93. http://dx.doi.org/10.1002/per.2282.
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Ambulatory assessment methods provide a rich approach for studying daily behaviour. Too often, however, these data are analysed in terms of averages, neglecting patterning of this behaviour over time. This paper describes recurrence quantification analysis (RQA), a non–linear time series technique for analysing dynamic systems, as a method for analysing patterns of categorical, intensive longitudinal ambulatory assessment data. We apply RQA to objectively assessed social behaviour (e.g. talking to another person) coded from the Electronically Activated Recorder. Conceptual interpretations of RQA parameters, and an analysis of Electronically Activated Recorder data in adults going through a marital separation, are provided. Using machine learning techniques to avoid model overfitting, we find that adding RQA parameters to models that include just average amount of time spent talking (a static measure) improves prediction of four Big Five personality traits: extraversion, neuroticism, conscientiousness, and openness. Our strongest results suggest that a combination of average amount of time spent talking and four RQA parameters yield an R2 = .09 for neuroticism. Neuroticism is shown to be associated with shorter periods of extended conversation (periods of at least 12 minutes), demonstrating the utility of RQA to identify new relationships between personality and patterns of daily behaviour. Materials: https://osf.io/5nkr9/ . © 2020 European Association of Personality Psychology
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Lagnese, J. E. "Boundary controllability of nonlinear beams to bounded states." Proceedings of the Royal Society of Edinburgh: Section A Mathematics 119, no. 1-2 (1991): 63–72. http://dx.doi.org/10.1017/s0308210500028316.
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SynopsisConsidered is a nonlinear model which describes the dynamic behaviour of the not necessarily small longitudinal and transverse displacements of a thin, cantilevered beam. The motion of the beam is driven by a bending moment, an axial force and a vertical shear force that act at the free end of the beam. The main goal is to describe the reachable set of the system, that is, the set of all states that can be reached by varying the end forces within a certain set of admissible controls.
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Kang, Jaeyoung. "Forced vibration analysis for dynamic coupling of finite-element spring-reduced suspension system." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 222, no. 3 (March 1, 2008): 349–56. http://dx.doi.org/10.1243/09544062jmes906.
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The current paper studies the dynamic behaviour of a coil spring in a vehicle suspension system. A portion of the coil spring is contacted with the top and bottom spring pads. The contact interface is modelled as a set of linear spring elements on the contact nodes of the coil spring. The eigensensitivity analysis is conducted to investigate the frequency variation of the stiffness-coupled system with respect to the contact stiffness variation. In the forced vibration analysis, the transfer function through the coil spring is obtained. The contribution of the coil spring modes to the load transfer is calculated by the modal contribution factor. It is shown that some of the longitudinal and bending vibration modes participate on the load transfer.
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Rongong, J. A., J. R. Wright, R. J. Wynne, and G. R. Tomlinson. "Modelling of a Hybrid Constrained Layer/Piezoceramic Approach to Active Damping." Journal of Vibration and Acoustics 119, no. 1 (January 1, 1997): 120–30. http://dx.doi.org/10.1115/1.2889679.
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It has been shown that significant reductions in structural vibration levels can be achieved using a hybrid system involving constrained layer damping and active control with piezoceramics. In this paper, mathematical models based on the Rayleigh Ritz approach, are developed to describe the longitudinal and flexural vibration behaviour of a cantilevered beam when excited using piezoceramic patches bonded to a constrained layer damping treatment. Predictions of static and steady state dynamic behaviour, obtained using the models are validated by comparison with results from finite element analysis and laboratory experiments. The models are then used in open loop and closed loop velocity feedback control simulations to demonstrate the improvements in stability and performance achieved using this method over that achieved using conventional active control.
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Boshoff, C., and S. M. Van Eeden. "South African consumer sentiment towards marketing: A longitudinal analysis." South African Journal of Business Management 32, no. 2 (June 30, 2001): 23–33. http://dx.doi.org/10.4102/sajbm.v32i2.718.
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A constant interaction occurs between the firm, its markets and the variables in the business environment. This dynamic interaction ensures that changes in the environment continuously exert an influence on consumer attitudes and sentiment and how consumers react to and perceive the marketing of products and services.The primary objective of this longitudinal study is to measure South African consumer sentiment towards marketing and to compare the results with previous studies done in 1990 and 1994. Secondary objectives include an investigation to establish to what extent this sentiment towards marketing is influenced by demographic variables.Although the marketing index decreased during the period 1990 to 1994, it improved dramatically during the period 1994 to 1999. In contrast to the previous studies it was established that demographic factors had no significant influence on the sentiment towards marketing in this study.As it is generally acknowledged that attitudes influence actual buying behaviour, marketers need to be aware that attitudes and sentiment toward marketing and marketing activities can change over time and proactive steps need to be taken to ensure that sentiment remains positive regardless of the changes in the external environment.
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Tian, Fu Qiang, Xiao Yan Li, and Yao Wu Shi. "Effect of Geometry Factors on Dynamic Fracture Behavior for Mechanical Heterogeneous Welded Joint." Key Engineering Materials 324-325 (November 2006): 543–46. http://dx.doi.org/10.4028/www.scientific.net/kem.324-325.543.
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Welded joint is a mechanical heterogeneous body, which is composed of base metal, weld metal and heat affected zone (HAZ). Many welded structures endure dynamic load in service. Mechanical heterogeneity has important influence on dynamic fracture behaviour of welded joint. In the present investigation, dynamic fracture parameter of J-integral of undermatched three-point-bending (TPB) welded joint specimens containing longitudinal crack with different geometry were computed. The strain rate near crack tip reaches 103 under the impact velocity of 5m/s, so dynamic properties under corresponding strain rate should be used in dynamic analysis. The results of instrumented impact experiment were used as the input parameters in the computation. Dynamic J-integral was evaluated using virtual crack extension (VCE) method of MARC finite element code in 3-D condition. Dynamic J-integral evaluated by VCE method is path independent. The value of dynamic J-integral curve increases with loading time smoothly, so inertia force has little influence on dynamic J-integral. The values of dynamic J-integral decrease with increase of weld width. When the weld width is bigger than 5mm the influence of base material on weld metal is not evident. The influence of initial crack length on dynamic J-integral is complicate. The value of dynamic J-integral of the computation model with initial crack length of a/W=1/4 is the highest, and that of the computation model with initial crack length of a/W=1/8 is the lowest. The results are helpful for dynamic fracture evaluation of macro-heterogeneous welded joints.
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Bassi, Francesca. "Forecasting Financial Products Acquisition via Dynamic Segmentation: An Application to the Italian Market." International Journal of Market Research 57, no. 6 (November 2015): 909–30. http://dx.doi.org/10.2501/ijmr-2015-071.
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The topic of market segmentation is still one of the most pervasive in marketing. Among clustering techniques, finite mixture models have gained recognition as a method of segmentation with several advantages over traditional methods; one variant of finite mixture models – the latent class (LC) model – is probably the most popular. The LC approach is innovative and flexible, and can provide suitable solutions to several problems regarding the definition and development of marketing strategies, because it takes into account specific features of the collected data, such as their scale of measure (often ordinal or categorical, rather than continuous), their hierarchical structure and their longitudinal component. Dynamic segmentation is of key importance in many markets where it is unrealistic to assume stationary segments due to the dynamics in consumers' needs and product choices. In this paper, a mixture latent class Markov model is proposed to dynamically segment Italian households with reference to financial products ownership. The mixture approach is compared with the standard one in terms of its ability to forecast customers' behaviour in the reference market.
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Banerjee, Saayan, Varadarajan Balamurugan, and R. Krishna Kumar. "Effect of integrated ride and cornering dynamics of a military vehicle on the weapon responses." Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics 232, no. 4 (February 6, 2018): 536–54. http://dx.doi.org/10.1177/1464419318754647.
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The present study brings out the influence of a non-linear dynamics model of military vehicle with trailing arm suspension, on the weapon dynamics responses. A 20 degrees of freedom integrated ride and cornering dynamics model has sequentially been coupled with the 7 degrees of freedom weapon dynamics model. The 20 degrees of freedom integrated model includes the bounce, pitch, roll, longitudinal, lateral and yaw motions of the sprung mass and rotational dynamics of the 14 unsprung masses. The 7 degrees of freedom weapon model comprises the coupled elevation and azimuth dynamics. The coupled weapon model includes angular rotation of the elevation drive, breech and muzzle in elevation direction, as well as, angular rotation of the azimuth drive, turret, breech and muzzle in azimuth direction. The actual physical behaviour of each of the hydro-gas trailing arm suspension units is implemented in the governing differential equations. The non-linear governing equations also incorporate the dynamic coupling between each of the axle arms and sprung mass, which is an inherent behaviour of the trailing arm suspension, unlike their equivalent vertical representation. The integrated model has been simulated for different cornering manoeuvres at specified speeds. It is observed that the sprung mass dynamics, emanating from different manoeuvres, significantly affects the coupled elevation and azimuth dynamics responses of the weapon. The weapon dynamics model coupled with the integrated ride and cornering dynamics model of the military vehicle, would be useful for implementation of a suitable robust gun control system in military vehicles.