bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic Response of a Beam Subjected to Moving Load and Moving Mass Supported by Pasternak Foundation
Authors: Uzzal Rajib Ul Alam , Bhat Rama B. , Ahmed Waiz
Published: January 2014

This paper presents the dynamic response of an Euler- Bernoulli beam supported on two-parameter Pasternak foundation subjected to moving load as well as moving mass. Modal analysis along with Fourier transform technique is employed to find the analytical solution of the governing partial differential equation. Shape functions are assumed to convert the partial differential equation into a series of ordinary differential equations. The dynamic responses of the beam in terms of normalized deflection and bending moment have been investigated for different velocity ratios under moving load and moving mass conditions. The effect of moving load velocity on dynamic deflection and bending moment responses of the beam have been investigated. The effect of foundation parameters such as, stiffness and shear modulus on dynamic deflection and bending moment responses have also been investigated for both moving load and moving mass at constant speeds. Numerical results obtained from the study are presented and discussed.
The Nonlinear Dynamic Behaviour of Tapered Laminated Plates Subjected to Blast Loading
Authors: Susler Sedat , Turkmen Halit S. , Kazancı Zafer
Published: January 2014

In this study, the geometrically nonlinear dynamic behaviour of simply supported tapered laminated composite plates subjected to the air blast loading is investigated numerically. In-plane stiffness, inertia and the geometric nonlinearity effects are considered in the formulation of the problem. The equations of motion for the tapered laminated plate are derived by the use of the virtual work principle. Approximate solution functions are assumed for the space domain and substituted into the equations of motion. Then, the Galerkin method is used to obtain the nonlinear algebraic differential equations in the time domain. The resulting equations are solved by using the finite difference approximation over the time. The effects of the taper ratio, the stacking sequence and the fiber orientation angle on the dynamic response are investigated. The displacement-time and strain-time histories are obtained on certain points in the tapered direction. The results obtained by using the present method are compared with the ones obtained by using a commercial finite element software ANSYS. The results are found to be in an agreement. The method presented here is able to determine the nonlinear dynamic response of simply supported tapered laminated plates to the air blast loading accurately.
Transmissibilty-Based Operational Modal Analysis for Flight Flutter Testing Using Exogenous Inputs
Authors: Devriendt Christof , De Troyer Tim , De Sitter Gert , Guillaume Patrick
Published: January 2014

During the recent years several new tools have been introduced by the Vrije Universiteit Brussel in the field of Operational Modal Analysis (OMA) such as the transmissibility based approach and the the frequency-domain OMAX concept. One advantage of the transmissibility based approach is that the ambient forces may be coloured (non-white), if they are fully correlated. The main advantage of the OMAX concept is the fact that it combines the advantages of Operational and Experimental Modal Analysis: ambient (unknown) forces as well as artificial (known) forces are processed simultaneously resulting in improved modal parameters. In this paper, the transmissibility based output-only approach is combined with the input/output OMAX concept. This results in a new methodology in the field of operational modal analysis allowing the estimation of (scaled) modal parameters in the presence of arbitrary ambient (unknown) forces and artificial (known) forces.
Nonlinear Vibration of a Continuum Rotor with Transverse Electromagnetic and Bearing Excitations
Authors: Luo Haiyang , Wang Yuefang
Published: January 2014

The nonlinear vibration of a rotor excited by transverse electromagnetic and oil-film forces is presented in this paper. The rotor-bearing system is modeled as a continuum beam which is loaded by a distributed electromagnetic load and is supported by two oil-film bearings. The governing equation of motion is derived and discretized as a group of ordinary differential equations using the Galerkin's method. The stability of the equilibrium of the rotor is analyzed with the Routh-Hurwitz criterion and the occurrence of the Andronov-Hopf bifurcation is pointed out. The approximate solution of periodic motion is obtained using the averaging method. The stability of steady response is analyzed and the amplitude-frequency curve of primary resonance is illustrated. The Runge-Kutta method is adopted to numerically solve transient response of the rotor-bearing system. Comparisons are made to present influences of electromagnetic load, oil-film force and both of them on the nonlinear vibration response. Bifurcation diagrams of the transverse motion versus rotation speed, electromagnetic parameter and bearing parameters are provided to show periodic motion, quasi-periodic motion and period-doubling bifurcations. Diagrams of time history, shaft orbit, the Poincaré section and fast Fourier transformation of the transverse vibration are presented for further understanding of the rotor response.
Principal Parametric Resonance of Axially Accelerating Viscoelastic Beams: Multi-Scale Analysis and Differential Quadrature Verification
Authors: Chen Li-Qun , Ding Hu , Lim C.W.
Published: January 2014

Transverse non-linear vibration is investigated in principal parametric resonance of an axially accelerating viscoelastic beam. The axial speed is characterized as a simple harmonic variation about a constant mean speed. The material time derivative is used in the viscoelastic constitutive relation. The transverse motion can be governed by a non-linear partial-differential equation or a non-linear integro-partial-differential equation. The method of multiple scales is applied to the governing equations to determine steady-state responses. It is confirmed that the mode uninvolved in the resonance has no effect on the steady-state response. The differential quadrature schemes are developed to verify results via the method of multiple scales. It is demonstrated that the straight equilibrium configuration becomes unstable and a stable steady-state emerges when the axial speed variation frequency is close to twice any linear natural frequency. The results derived for two governing equations are qualitatively the same, but quantitatively different. Numerical simulations are presented to examine the effects of the mean speed and the variation of the amplitude of the axial speed, the dynamic viscosity, the non-linear coefficients, and the boundary constraint stiffness on the instability interval and the steady-state response amplitude.
A Closed Form Solution for Nonlinear Oscillators Frequencies Using Amplitude-Frequency Formulation
Authors: Barari A. , Kimiaeifar A. , Nejad M.G. , Motevalli M. , Sfahani M.G.
Published: January 2014

Many nonlinear systems in industry including oscillators can be simulated as a mass-spring system. In reality, all kinds of oscillators are nonlinear due to the nonlinear nature of springs. Due to this nonlinearity, most of the studies on oscillation systems are numerically carried out while an analytical approach with a closed form expression for system response would be very useful in different applications. Some analytical techniques have been presented in the literature for the solution of strong nonlinear oscillators as well as approximate and numerical solutions. In this paper, Amplitude-Frequency Formulation (AFF) approach is applied to analyze some periodic problems arising in classical dynamics. Results are compared with another approximate analytical technique called Energy Balance Method developed by the authors (EBM) and also numerical solutions. Close agreement of the obtained results reveal the accuracy of the employed method for several practical problems in engineering.
Free Vibration of Rectangular Plates with Attached Discrete Sprung Masses
Authors: Zhou Ding , Ji Tianjian
Published: January 2014

A direct approach is used to derive the exact solution for the free vibration of thin rectangular plates with discrete sprung masses attached. The plate is simply supported along two opposite edges and elastically supported along the two other edges. The elastic support can represent a range of boundary conditions from free to clamped supports. Considering only the compatibility of the internal forces between the plate and the sprung masses, the equations of the coupled vibration of the plate-spring-mass system are derived. The exact expressions for mode and frequency equations of the coupled vibration of the plate and sprung masses are determined. The solutions converge steadily and monotonically to exact values. The correctness and accuracy of the solutions are demonstrated through comparison with published results. A parametric study is undertaken focusing on the plate with one or two sprung masses. The results can be used as a benchmark for further investigation.

The solution provided in the paper is general and includes several special cases, such as the plate with classical boundary conditions, the plate attached with discrete rigid masses, the plate supported by discrete springs and the plate restricted by rigid vertical point-supports.
Torsional Vibration of a Shafting System under Electrical Disturbances
Authors: Xiang Ling , Yang Shixi , Gan Chunbiao
Published: January 2014

Torsional vibration responses of a nonlinear shafting system are studied by a modified Riccati torsional transfer matrix combining with the Newmark-βmethod. Firstly, the system is modeled as a chain consisting of an elastic spring with concentrated mass points, from which a multi-segment lumped mass model is established. Secondly, accumulated errors are eliminated from the eigenfrequencies and responses of the system's torsional vibration by this newly developed procedure. The incremental transfer matrix method, combining the modified Riccati torsional transfer matrix with Newmark-βmethod, is further applied to solve the dynamical equations for the torsional vibration of the nonlinear shafting system. Lastly, the shafting system of a turbine-generator is employed as an illustrating example, and simulation analysis has been performed on the transient responses of the shaft's torsional vibrations during typical power network disturbances, such as three-phase short circuit, two-phase short circuit and asynchronous juxtaposition. The results validate the present method and are instructive for the design of a turbo-generator shaft.
The Cognitive and Behavioural Profile of Amyotrophic Lateral Sclerosis: Application of the Consensus Criteria
Authors: Consonni Monica , Iannaccone Sandro , Cerami Chiara , Frasson Paola , Lacerenza Marco , Lunetta Christian , Corbo Massimo , Cappa Stefano F.
Published: January 2014

Objective:The study aims to assess the spectrum of cognitive and behavioural disorders in patients affected by Amyotrophic Lateral Sclerosis (ALS) according to the recent consensus criteria [9]. The study also intends to assess the impact of physical disability on cognitive and behavioural abnormalities.

Methods:Detailed neurological, neuropsychological and neurobehavioral evaluations were administered to 23 ALS patients, 11 Lower Motor Neuron Disease (LMND) patients and 39 healthy controls. Strong et al.’s criteria [9] were applied to diagnose the presence of cognitive/behavioural impairment. Clinical and neuropsychological scores were used for group comparisons and correlation analyses.

Results:In comparison with LMND and controls, a subgroup of ALS patients (∼30%) manifested executive dysfunction, which was severe enough to classify them as cognitively impaired. Action naming difficulties and short-term memory deficits were also observed. Aspontaneity, disorganization and mental rigidity reached clinical relevance in 20% of ALS patients. A small percentage of ALS patients (13%) also had comorbid dementia. The cognitive or behavioural status was not related to the clinical features of ALS.

Conclusion:The use of consensus criteria for cognitive and behavioural impairment and the comparison with the LMND group proved useful in defining the spectrum of non-motor manifestations of ALS.
Vibrations of a Simply Supported Beam with a Fractional Viscoelastic Material Model – Supports Movement Excitation
Authors: Freundlich Jan
Published: January 2014

The paper presents vibration analysis of a simply supported beam with a fractional order viscoelastic material model. The Bernoulli-Euler beam model is considered. The beam is excited by the supports movement. The Riemann – Liouville fractional derivative of order 0 α ⩽ 1 is applied. In the first stage, the steady-state vibrations of the beam are analyzed and therefore the Riemann – Liouville fractional derivative with lower terminal at −∞ is assumed. This assumption simplifies solution of the fractional differential equations and enables us to directly obtain amplitude-frequency characteristics of the examined system. The characteristics are obtained for various values of fractional derivative of order α and values of the Voigt material model parameters. The studies show that the selection of appropriate damping coefficients and fractional derivative order of damping model enables us to fit more accurately dynamic characteristic of the beam in comparison with using integer order derivative damping model.
Cracks Detection Using Active Modal Damping and Piezoelectric Components
Authors: Chomette B. , Fernandes A. , Sinou J.-J.
Published: January 2014

The dynamics of a system and its safety can be considerably affected by the presence of cracks. Health monitoring strategies attract so a great deal of interest from industry. Cracks detection methods based on modal parameters variation are particularly efficient in the case of large cracks but are difficult to implement in the case of small cracks due to measurement difficulties in the case of small parameters variation. Therefore the present study proposes a new method to detect small cracks based on active modal damping and piezoelectric components. This method uses the active damping variation identificated with the Rational Fraction Polynomial algorithm as an indicator of cracks detection. The efficiency of the proposed method is demonstrated through numerical simulations corresponding to different crack depth and locations in the case of a finite element model of a clamped-clamped beam including four piezoelectric transducers.
Toward an Executive Origin for Acquired Phonological Dyslexia: A Case of Specific Deficit of Context-Sensitive Grapheme-to-Phoneme Conversion Rules
Authors: Auclair-Ouellet Noémie , Fossard Marion , St-Pierre Marie-Catherine , Macoir Joël
Published: January 2014

Phonological dyslexia is a written language disorder characterized by poor reading of nonwords when compared with relatively preserved ability in reading real words. In this study, we report the case of FG, a 74-year-old man with phonological dyslexia. The nature and origin of his reading impairment were assessed using tasks involving activation and explicit manipulation of phonological representations as well as reading of words and nonwords in which the nature and complexity of grapheme-to-phoneme conversion rules (GPC rules) were manipulated. FG also underwent an extensive neuropsychological assessment battery in which he showed impaired performance in tests exploring verbal working memory and executive functions. FG showed no phonological impairment, and his performance was also largely unimpaired for reading words, with no effect of concreteness, grammatical class, morphological complexity, length or nature and complexity of the GPC rules. However, he showed substantial difficulties when asked to read nonwords with contextual GPC rules. The contribution of FG’s executive deficits to his performance in reading is discussed.
Behavioural Treatments for Tourette Syndrome: An Evidence-Based Review
Authors: Frank Madeleine , Cavanna Andrea Eugenio
Published: January 2014

Tourette syndrome (TS) is a disorder characterised by multiple motor and vocal tics and is frequently associated with behavioural problems. Tics are known to be affected by internal factors such as inner tension and external factors such as the surrounding environment. A number of behavioural treatments have been suggested to treat the symptoms of TS, in addition to pharmacotherapy and surgery for the most severe cases. This review compiled all the studies investigating behavioural therapies for TS, briefly describing each technique and assessing the evidence in order to determine which of these appear to be effective. Different behavioural therapies that were used included habit reversal training (HRT), massed negative practice, supportive psychotherapy, exposure with response prevention, self-monitoring, cognitive-behavioural therapy, relaxation therapy, assertiveness training, contingency management, a tension-reduction technique and biofeedback training. Overall, HRT is the best-studied and most widely-used technique and there is sufficient experimental evidence to suggest that it is an effective treatment. Most of the other treatments, however, require further investigation to evaluate their efficacy. Specifically, evidence suggests that exposure with response prevention and self-monitoring are effective, and more research is needed to determine the therapeutic value of the other treatments. As most of the studies investigating behavioural treatments for TS are small-sample or single-case studies, larger randomised controlled trials are advocated.
The Gilles De La Tourette Syndrome-Quality of Life Scale for Children and Adolescents (C&A-GTS-QOL): Development and Validation of the Italian Version
Authors: Cavanna Andrea E. , Luoni Chiara , Selvini Claudia , Blangiardo Rosanna , Eddy Clare M. , Silvestri Paola R. , Calì Paola V. , Seri Stefano , Balottin Umberto , Cardona Francesco , Rizzo Renata , Termine Cristiano
Published: January 2014

Background:Gilles de la Tourette syndrome (GTS) is a chronic childhood-onset neuropsychiatric disorder with a significant impact on patients’ health-related quality of life (HR-QOL). Cavanna et al. (Neurology 2008; 71: 1410–1416) developed and validated the first disease-specific HR-QOL assessment tool for adults with GTS (Gilles de la Tourette Syndrome-Quality of Life Scale, GTS-QOL). This paper presents the translation, adaptation and validation of the GTS-QOL for young Italian patients with GTS.

Methods:A three-stage process involving 75 patients with GTS recruited through three Departments of Child and Adolescent Neuropsychiatry in Italy led to the development of a 27-item instrument (Gilles de la Tourette Syndrome-Quality of Life Scale in children and adolescents, C&A-GTS-QOL) for the assessment of HR-QOL through a clinician-rated interview for 6–12 year-olds and a self-report questionnaire for 13–18 year-olds.

Results:The C&A-GTS-QOL demonstrated satisfactory scaling assumptions and acceptability. Internal consistency reliability was high (Cronbach’s alpha > 0.7) and validity was supported by interscale correlations (range 0.4–0.7), principal-component factor analysis and correlations with other rating scales and clinical variables.

Conclusions:The present version of the C&A-GTS-QOL is the first disease-specific HR-QOL tool for Italian young patients with GTS, satisfying criteria for acceptability, reliability and validity.
Optic Neuritis: From Magnocellular to Cognitive Residual Dysfunction
Authors: Viret Anne-Claire , Cavézian Céline , Coubard Olivier , Vasseur Vivien , Raz Noa , Levin Netta , Vignal Catherine , Gout Olivier , Chokron Sylvie
Published: January 2014

Optic Neuritis (ON) has been associated to both parvocellular dysfunction and to an alteration of the magnocellular pathway. After objective visual field and acuity recovery, ON patients may complain about their vision suggesting a residual subclinical deficit. To better characterize visual abnormalities, 8 patients recovering from a first ON episode as well as 16 healthy controls performed a simple detection task and a more complex categorization task of images presented in low spatial frequencies (to target the magnocellular system) or in high spatial frequencies (to target the parvocellular system) or of non-filtered images. When completing the tasks with their (previously) pathologic eye, optic neuritis patients showed lower accuracy compared to controls or to their healthy eye for low spatial frequency images only. Conjointly, the longest reaction times were observed with the previously pathologic eye regardless the type of images and to a greater extent in the categorization task than in the detection task. Such data suggest two distinct, although associated, types of residual dysfunction in ON: a magnocellular pathway alteration and a more general (magno and parvocellular) visual dysfunction that could implicate the cognitive levels of visual processing.
An Energy-Based Limit State Function for Estimation of Structural Reliability in Shock Environments
Authors: Guthrie Michael A.
Published: January 2014

limit state function is developed for the estimation of structural reliability in shock environments. This limit state function uses peak modal strain energies to characterize environmental severity and modal strain energies at failure to characterize the structural capacity. The Hasofer-Lind reliability index is briefly reviewed and its computation for the energy-based limit state function is discussed. Applications to two degree of freedom mass-spring systems and to a simple finite element model are considered. For these examples, computation of the reliability index requires little effort beyond a modal analysis, but still accounts for relevant uncertainties in both the structure and environment. For both examples, the reliability index is observed to agree well with the results of Monte Carlo analysis. In situations where fast, qualitative comparison of several candidate designs is required, the reliability index based on the proposed limit state function provides an attractive metric which can be used to compare and control reliability.
On-Line Impact Load Identification
Authors: Sekuła Krzysztof , Graczykowski Cezary , Holnicki-Szulc Jan
Published: January 2014

The so-called AdaptiveImpact Absorption(AIA) is a research area ofsafety engineeringdevoted to problems of shock absorption in various unpredictable scenarios of collisions. It makes use ofsmart technologies(systems equipped with sensors, controllable dissipaters and specialised tools for signal processing). Examples of engineering applications for AIA systems are protective road barriers, automotive bumpers or adaptive landing gears. One of the most challenging problems for AIA systems is on-line identification of impact loads, which is crucial for introducing the optimum real-time strategy of adaptive impact absorption. This paper presents the concept of animpactometerand develops the methodology able to perform real-time impact load identification. Considered dynamic excitation is generated by a massM1impacting with initial velocityV0. An analytical formulation of the problem, supported with numerical simulations and experimental verifications is presented. Two identification algorithms based on measured response of the impacted structure are proposed and discussed. Finally, a concept of the AIA device utilizing the idea ofimpactometeris briefly presented.
Development and Mechanical Performance of a New Kind of Bridge Seismic Isolator for Low Seismic Regions
Authors: Zhang H. , Li J. , Peng T.
Published: January 2014

The concept of fibre-reinforced plate elastomeric isolator (FRPEI) is introduced firstly in this paper. Three FRPEI specimens have been constructed to evaluate the mechanical performance of the isolators by performing vertical and horizontal tests. The research focuses on the compression stiffness, the shear stiffness, the hysteretic characteristic and the vertical bearing capacity of the isolators. The experimental results show that the mechanical performance of FRPEIs can meet the requirements of bridge rubber bearings and the energy dissipation capacity is better than that of general laminated rubber bearings. Therefore, it is feasible to use FRPEIs in seismic isolation of short span bridges in low seismic regions. Theoretical and finite element methods have also been employed and the deformation assumptions applied in the theoretical method are also verified by FEM. By comparing the differences of the results of different methods, the effectivenesses of the theoretical and finite element methods are evaluated and some considerations on isolator design are proposed.
Dual Task Performance in Parkinson’s Disease
Authors: Foley Jennifer A. , Kaschel Reiner , Sala Sergio Della
Published: January 2014

Several studies have found dual tasking to be impaired in Alzheimer's disease (AD), but unaffected by healthy ageing. It is not known if this deficit is specific to AD, or also present in other neurodegenerative disorders that can occur in later life, such as Parkinson's disease (PD). Therefore, this study investigated dual tasking in 13 people with PD, 26 AD and 42 healthy age-matched controls. The people with AD demonstrated a specific impairment in dual tasking, which worsened with increasing disease severity. The people with PD did not demonstrate any deficits in dual tasking ability, when compared to healthy controls, suggesting that the dual task impairment is specific to AD.
Fractal Dimension-Based Damage Imaging for Composites
Authors: Zhou Li , Sun Hu , He Zhiquan
Published: January 2014

In this paper, a damage imaging algorithm based on fractal dimension is developed for quantitative damage detection of composite structures. Box-counting dimension, a typical fractal dimension, is employed to analyze the difference of Lamb wave signals, extract damage feature and define damage index. An enhanced reconstruction algorithm for probabilistic inspection of damage is developed for damage imaging. Experimental investigation in a composite laminate and a stiffened composite panel shows that the developed algorithm could quantitatively predict the location and size of not only single but also multiple damages. The influence of parameters in the developed algorithm on the imaging quality and accuracy is studied, and reference values for parameters are presented.
Motor Extinction in Distinct Reference Frames: A Double Dissociation
Authors: Heidler-Gary Jennifer , Pawlak Mikolaj , Herskovits Edward H. , Newhart Melissa , Davis Cameron , Trupe Lydia A. , Hillis Argye E.
Published: January 2014

Objective:Test the hypothesis that right hemisphere stroke can cause extinction of left hand movements or movements of either hand held in left space, when both are used simultaneously, possibly depending on lesion site.

Methods:93 non-hemiplegic patients with acute right hemisphere stroke were tested for motor extinction by pressing a counter rapidly for one minute with the right hand, left hand, or both simultaneously with their hands held at their sides, or crossed over midline.

Results:We identified two distinct types of motor extinction in separate patients; 20 patients extinguished left hand movements held in left or right space (left canonical body extinction); the most significantly associated voxel cluster of ischemic tissue was in the right temporal white matter. Seven patients extinguished either hand held in left space (left space extinction), and the most significantly associated voxel cluster of ischemic tissue was in right parietal white matter.

Conclusions:There was a double dissociation between left canonical body extinction and left space motor extinction. Left canonical body extinction seems to be associated with more dorsal (parietal) ischemia, and left canonical body extinction seems to be associated with more ventral (temporal) ischemia.
Parameters Affecting the Transient Response of an Impacting Beam
Authors: Xu Weiping , Ervin Elizabeth K.
Published: January 2014

Impact causes shock waves that may be unexpected and damaging. A computationally efficient impact model with a generic beam which is discrete in time and continuous in space was undertaken; an Euler-Bernoulli beam with adjustable boundary conditions and variable contact location is numerically studied under a pulse loading. Experiments on a cantilever beam were carried out to verify the effects of influential parameters. A half-sine pulse excitation was applied through a mechanical shaker, and the deflection was captured by a high speed camera. Numerous test cases were conducted that varied pulse duration, pulse amplitude, and clearance. Decreasing the pulse duration lowers all deflection amplitudes, but the time in contact is insensitive. No gap causes minimal beam response, and increasing gap generates greater deflection. Representative test cases were selected for validating the theoretical model. When comparing numerical simulation with experimental results, satisfactory agreement for amplitude and duration can be reached even with raw input parameters. The contribution of this study is the incorporation of unique pulse loading, changeable boundary conditions, adjustable contact/impact situations, comprehensive parameter studies, and high speed photography.
Analysis of Stationary Random Vibrating Systems Using Smooth Decomposition
Authors: Bellizzi Sergio , Sampaio Rubens
Published: January 2014

A modified Karhunen-Loève Decomposition/Proper Orthogonal Decomposition method, named Smooth Decomposition (SD) (also named smooth Karhunen-Loève decomposition), was recently introduced to analyze stationary random signal. It is based on a generalized eigenproblem defined from the covariance matrix of the random process and the covariance matrix of the associated time-derivative random process. The SD appears to be an interesting tool in terms of modal analysis. In this paper, the SD will be described in case of stationary random processes and extended also to stationary random fields. The main properties will be discussed and illustrated on a randomly excited clamped-free beam.
Progressive Micrographia Shown in Horizontal, but not Vertical, Writing in Parkinson’s Disease
Authors: Ma Hui-Ing , Hwang Wen-Juh , Chang Shao-Hsia , Wang Tsui-Ying
Published: January 2014

All published studies on micrographia, a diminution of letter size, examine handwriting in the horizontal direction. Writing horizontally typically requires increased wrist extension as handwriting progresses from left to right. Chinese characters, however, can be written not only horizontally from left to right, but also vertically from top to bottom. We examined the effect of handwriting direction on character size and stroke length. Fifteen participants with Parkinson’s disease (PD) and 15 age-matched controls wrote the same Chinese characters both horizontally and vertically. Handwriting performance was recorded with a digitizing tablet, and a custom-written computer program was used to provide objective data about character size and stroke length. The PD group had a linear decrease in overall character size and horizontal strokes along the writing sequence in the horizontal direction, but not in the vertical direction. The controls had shorter horizontal strokes in the horizontal than the vertical direction, but there was no progressive shortening of stroke length along the writing sequence. The results suggest that traditionally reported progressive micrographia in horizontal writing may not be generalizable to vertical writing. The observed decrease of handwriting size in the horizontal direction suggests that micrographia in PD may be associated with wrist extension. For clinical implications, patients may mitigate their micrographia by changing handwriting direction.
Dynamic Modelling of Axle Tramp in a Sport Type Car
Authors: Zargartalebi Ali , Shirazi Kourosh Heidari
Published: January 2014

One of the most significant dynamic aspects of coupled vibration of transmission system and dependent type suspension systems is axle tramp. The tramp is defined as undesirable oscillation of rigid live axle around roll axis. In spite of utilizing powerful engines in some type of sport cars, tramp occurrence causes loss of longitudinal performance. The aim of this paper is to derive a mathematical model for predicting and classifying of the tramp. A parameter study reveals that, some parameters such as engine torque, moving parts moment of inertia, car and wheels weight and the material used in suspension system play important role in controlling the tramp. It is shown that large difference between sprung and unsprung mass moment of inertia around the roll-axis, low vehicle mass, short rear track and medium damping values have significant effects on the severity of tramp.
Independent Modal Variable Structure Fuzzy Active Vibration Control of Cylindrical Thin Shells Laminated with Photostrictive Actuators
Authors: He R.B. , Zheng S.J. , Wang H.T.
Published: January 2014

Photostrictive actuator, which can produce photodeformation strains under the activation of ultraviolet lights, is a new promising non-contact photoactuation technique for active vibration control of flexible structures. Generally, the membrane control action plays a major role in vibration control of flexible thin shell structures. However, it is unfortunate that the existing photostrictive actuator configuration can not induce negative membrane control forces. In this paper, a novel multi-layer actuator configuration is first presented to remedy this deficiency, followed by presenting the photostrictive/shell coupling equations of thin cylindrical shells laminated with the proposed multi-layer actuator configuration. Moreover, considering the time-variant and nonlinear dynamic characteristics of photostrictive actuator, variable structure self-adjusting parameter fuzzy active controller is explored to overcome disadvantages of conventional control schemes, in which off-line fuzzy control table is adopted. The optimal switching surface is derived to increase the range of sliding mode to facilitate vibration suppression. A continuous function is used to replace the sign function for reducing the variable structure control chattering. Finally, two case studies are carried out to evaluate the effectiveness of the proposed actuator configuration and the control scheme. Numerical simulation results demonstrate that the proposed actuator configuration is effective in shell actuation and control. It is also suggested that the proposed control strategy could give better control responses than the proportional velocity feedback.
Effects of Eccentricity on the Dynamic Behavior for Electromechanical Integrated Toroidal Drive
Authors: Xu Lizhong , Li Haifeng
Published: January 2014

In electromechanical integrated toroidal drive, eccentric center errors occur which has important influences on the dynamic behavior of the drive system. Here, the dynamic equations of the drive system with eccentric center are presented. Changes of the natural frequencies and vibrating modes along with eccentric center distance are analyzed. The forced responses of the drive system to eccentric center excitation are investigated. Results show that the eccentric center causes some natural frequencies to increase, and the other natural frequencies to drop. It also causes some vibrations to become weak, and the other vibrations to become strong. The eccentric center has more obvious effects on the dynamic behavior of the planets. The results are useful in design and manufacture of the drive systems.
A Novel Damage Detection Algorithm using Time-Series Analysis-Based Blind Source Separation
Authors: Sadhu A. , Hazra B.
Published: January 2014

In this paper, a novel damage detection algorithm is developed based on blind source separation in conjunction with time-series analysis. Blind source separation (BSS), is a powerful signal processing tool that is used to identify the modal responses and mode shapes of a vibrating structure using only the knowledge of responses. In the proposed method, BSS is first employed to estimate the modal response using the vibration measurements. Time-series analysis is then performed to characterize the mono-component modal responses and successively the resulting time-series models are utilized for one-step ahead prediction of the modal response. With the occurrence of newer measurements containing the signature of damaged system, a variance-based damage index is used to identify the damage instant. Once the damage instant is identified, the damaged and undamaged modal parameters of the system are estimated in an adaptive fashion. The proposed method solves classical damage detection issues including the identification of damage instant, location as well as the severity of damage. The proposed damage detection algorithm is verified using extensive numerical simulations followed by the full scale study of UCLA Factor building using the measured responses under Parkfield earthquake.
Rolling Element Bearing Fault Recognition Approach Based on Fuzzy Clustering Bispectrum Estimation
Authors: Liu W.Y. , Han J.G.
Published: January 2014

A rolling element bearing fault recognition approach is proposed in this paper. This method combines the basic Higher-order spectrum (HOS) theory and fuzzy clustering method in data mining area. In the first step, all the bispectrum estimation results of the training samples and test samples are turned into binary feature images. Secondly, the binary feature images of the training samples are used to construct object templates including kernel images and domain images. Every fault category has one object templates. At last, by calculating the distances between test samples' binary feature images and the different object templates, the object classification and pattern recognition can be effectively accomplished. Bearing is the most important and much easier to be damaged component in rotating machinery. Furthermore, there exist large amounts of noise jamming and nonlinear coupling components in bearing vibration signals. The Higher Order Cumulants (HOC), which can quantitatively describe the nonlinear characteristic signals with close relationship between the mechanical faults, is introduced in this paper to de-noise the raw bearing vibration signals and obtain the bispectrum estimation pictures. In the experimental part, the rolling bearing fault diagnosis experiment results proved that the classification was completely correct.
The Future of Research in Tourette Syndrome
Authors: Cavanna Andrea E. , Kavanagh Conor , Robertson Mary M.
Published: January 2014

Tourette syndrome (TS) is a neurological condition first described by Georges Gilles de la Tourette in 1885. TS was largely thought of as a rare and bizarre condition until the 1960s, when the beneficial effects of neuroleptics on tic symptoms led to an exponential increase in neuroscientific research. Today TS is known to be a relatively common condition that is frequently misdiagnosed due to a combination of its variable manifestation and the waxing and waning of tic frequency and severity. Although there has been a paucity of research on TS compared to other movement disorders, in recent years TS has garnered increasing interest and has shown a number of novel and complex sides, about which much is yet to be learnt. The present article discusses where research has taken us thus far and where it is heading in all the major facets of this fascinating condition.
Verbal and Nonverbal Memory in Primary Progressive Aphasia: The Three Words-Three Shapes Test
Authors: Weintraub Sandra , Rogalski Emily , Shaw Emily , Sawlani Sabrina , Rademaker Alfred , Wieneke Christina , Mesulam M.-Marsel
Published: January 2014

Objectives:To investigate cognitive components and mechanisms of learning and memory in primary progressive aphasia (PPA) using a simple clinical measure, the Three Words Three Shapes Test (3W3S).

Background:PPA patients can complain of memory loss and may perform poorly in standard tests of memory. The extent to which these signs and symptoms reflect dysfunction of the left hemisphere language versus limbic memory network remains unknown.

Methods:3W3S data from 26 patients with a clinical diagnosis of PPA were compared with previously published data from patients with typical dementia of the Alzheimer type (DAT) and cognitively healthy elders.

Results:PPA patients showed two bottlenecks in new learning. First, they were impaired in the effortless (but not effortful) on-line encoding of verbal (but not non-verbal) items. Second, they were impaired in the retrieval (but not retention) of verbal (but not non-verbal) items. In contrast, DAT patients had impairments also in effortful on-line encoding and retention of verbal and nonverbal items.

Conclusions:PPA selectively interferes with spontaneous on-line encoding and subsequent retrieval of verbal information. This combination may underlie poor memory test performance and is likely to reflect the dysfunction of the left hemisphere language rather than medial temporal memory network.
Component Mode Synthesis Using Undeformed Interface Coupling Modes to Connect Soft and Stiff Substructures
Authors: Lindberg Eskil , Hörlin Nils-Erik , Göransson Peter
Published: January 2014

Classical component mode synthesis methods for reduction are usually limited by the size and compatibility of the coupling interfaces. A component mode synthesis approach with constrained coupling interfaces is presented for vibro-acoustic modelling. The coupling interfaces are constrained to six displacement degrees of freedom. These degrees of freedom represent rigid interface translations and rotations respectively, retaining an undeformed interface shape. This formulation is proposed for structures with coupling between softer and stiffer substructures in which the displacement is chiefly governed by the stiffer substructure. Such may be the case for the rubber-bushing/linking arm assembly in a vehicle suspension system. The presented approach has the potential to significantly reduce the modelling size of such structures, compared with classical component mode synthesis which would be limited by the modelling size of the interfaces. The approach also eliminates problems of nonconforming meshes in the interfaces since only translation directions, rotation axes and the rotation point need to be common for the coupled substructures. Simulation results show that the approach can be used for modelling of systems that resemble a vehicle suspension. It is shown for a test case that adequate engineering accuracy can be achieved when the stiffness properties of the connecting parts are within the expected range of rubber connected to steel.
Change of Accent as an Atypical Onset of non Fluent Primary Progressive Aphasia
Authors: Paolini Susy , Paciaroni Lucia , Manca Antonio , Rossi Roberto , Fornarelli Daniela , Cappa Stefano F. , Abbatecola Angela M. , Scarpino Osvaldo
Published: January 2014

Language disorders can be the first symptom of many neurodegenerative diseases, including Alzheimer's disease (AD) and primary progressive aphasia (PPA). The main variants of PPA are: the non-fluent/agrammatic variant, the semantic variant and the logopenic variant.

Several additional variants of PPA, however, have been described and are considered as atypical presentations.

We describe the case of a woman presenting a progressive isolated language disturbance, characterized by an early dysprosodia, phonological and semantic paraphasias, agrammatism, impairment in repetition, writing of non-words and sentence comprehension. This clinical picture pointed to an atypical presentation of the non-fluent variety. The frequent symptom overlap between the different variants of PPA, most likely reflecting differences in the topography of the pathological changes, needs to be considered in the definition of diagnostic criteria.
Thermo-Mechanical Vibration of Short Carbon Nanotubes Embedded in Pasternak Foundation Based on Nonlocal Elasticity Theory
Authors: Amirian B. , Hosseini-Ara R. , Moosavi H.
Published: January 2014

This study is concerned with the thermal vibration analysis of a short single-walled carbon nanotube embedded in an elastic medium based on nonlocal Timoshenko beam model. A Winkler- and Pasternak-type elastic foundation is employed to model the interaction of short carbon nanotubes and the surrounding elastic medium. Influence of all parameters such as nonlocal small-scale effects, high temperature change, Winkler modulus parameter, Pasternak shear parameter, vibration mode and aspect ratio of short carbon nanotubes on the vibration frequency are analyzed and discussed. The present study shows that for high temperature changes, the effect of Winkler constant in different nonlocal parameters on nonlocal frequency is negligible. Furthermore, for all temperatures, the nonlocal frequencies are always smaller than the local frequencies in short carbon nanotubes. In addition, for high Pasternak modulus, by increasing the aspect ratio, the nonlocal frequency decreases. It is concluded that short carbon nanotubes have the higher frequencies as compared with long carbon nanotubes.
Vibration and Acoustic Response of Rectangular Sandwich Plate under Thermal Environment
Authors: Liu Yuan , Li Yueming
Published: January 2014

In this paper, we focus on the vibration and acoustic response of a rectangular sandwich plate which is subjected to a concentrated harmonic force under thermal environment. The critical buckling temperature is obtained to decide the thermal load. The natural frequencies and modes as well as dynamic responses are acquired by using the analytical formulations based on equivalent non-classical theory, in which the effects of shear deformation and rotational inertia are taken into account. The rise of thermal load decreases the natural frequencies and moves response peaks to the low-frequency range. The specific features of sandwich plates with different formations are discussed subsequently. As the thickness ratio of facing to core increases, the natural frequencies are enlarged, and the response peaks float to the high-frequency region. Raising the Young's modulus of the core can cause the similar trends. The accuracy of the theoretical method is verified by comparing its results with those computed by the FEM/BEM.
Multi-Fault Feature Extraction and Diagnosis of Gear Transmission System Using Time-Frequency Analysis and Wavelet Threshold De-Noising Based on EMD
Authors: Shao Renping , Hu Wentao , Li Jing
Published: January 2014

gear transmission system is a complex non-stationary and nonlinear time-varying coupling system. When faults occur on gear system, it is difficult to extract the fault feature. This paper researches the threshold principle in the process of using the wavelet transform to de-noise the system, and combines EMD (empirical mode decomposition) with wavelet threshold de-noising to solve the problem. The wavelet threshold de-noising is acts on the high-frequency IMF (Intrinsic Mode Function) component of the signal, and does overcome the defect by simply highlighting the fault feature. On this basis, the pre-processed signal is analyzed by the method of time-frequency analysis to extract the feature of the signal. The result shows that the SNR (signal-noise ratio) of the signal was largely improved, and the fault feature of the signal can therefore be effectively extracted. Combined with time-frequency analyses in the different running conditions (300 rpm, 900 rpm), various faults such as tooth root crack, tooth wear and multi-fault can be identified effectively. Based on this theory and combining the merits of MATLAB and VC++, a multi-functional gear fault diagnosis software system is successfully exploited.