bluuebunny/crossref_metadata_2025 huggingface dataset:
Simultaneous Structural Health Monitoring and Vibration Control of Adaptive Structures Using Smart Materials
Authors: Kim Myung-Hyun
Published: January 2014

The integration of actuators and sensors using smart materials enabled various applications including health monitoring and structural vibration control. In this study, a robust control technique is designed and implemented in order to reduce vibration of an active structure. Special attention is given to eliminating the possibility of interaction between the health monitoring system and the control system. Exploiting the disturbance decoupling characteristic of the sliding mode observer, it is demonstrated that the proposed observer can eliminate the possible high frequency excitation from the health monitoring system. At the same time, a damage identification scheme, which tracks the changes of mechanical impedance due to the presence of damage, has been applied to assess the health condition of structures. The main objective of this paper is to examine the potential of combining the two emerging techniques together. Using the collocated piezoelectric sensors/actuators for vibration suppression as well as for health monitoring, this technique enabled to reduce the number of system components, while enhancing the performance of structures. As an initial study, both simulation and experimental investigations were performed for an active beam structure. The results show that this integrated technique can provide substantial vibration reductions, while detecting damage on the structure at the same time.
Deficits of Motor Intention following Parietal Lesions
Authors: Gore Christopher L. , Rodriguez P. Dennis , Baylis Gordon C.
Published: January 2014

Patients with lesions to the right parietal lobe were tested on their ability to reach to targets, or to respond verbally to targets. The targets occurred at the same two spatial locations ‐‐ to the left and right of the patient—with the task being cued by the color of the target. Patients were able to perform both tasks separately rapidly and without error. However, when the two tasks were interleaved, they had difficulty making a response in the left (contralesional) field when this was different to a response that they had just made. These results suggest that lesions to the parietal cortex may cause a deficit in the coding for motor intention, as well as attention in the contralesional field.
Numerical and Experimental Study of Impulsive Sound Attenuation of an Earmuff
Authors: Vergara Felipe , Gerges Samir N. , Birch Robert S.
Published: January 2014

This work compares the results of laboratory experiments with numerical modelling using the finite element method in order to assess the attenuation of hearing protectors under conditions of high amplitude impulse noise. Comparative data for the finite element simulation was provided from a series of experiments using a shock tube, acoustic test fixture, ear canal simulator and partial head form. The numerical model comprised a finite element mesh of fluid and porous materials in order to model the earmuff hearing protector coupled to the auditory canal. The results show that a simple 2‐D finite element model is capable of making a reasonable prediction of the attenuation of an earmuff provided that headband force is also included in the model.
A New Vibration Measurement Procedure for On‐Line Quality Control of Electronic Devices
Authors: Revel Gian Marco
Published: January 2014

In this paper the problem of experimentally testing the mechanical reliability of electronic components for quality control is approached. In general, many tests are performed on electronic devices (personal computers, power supply units, lamps, etc.), according to the relevant international standards (IEC), in order to verify their resistance to shock and vibrations, but these are mainly “go no‐go” experiments, performed on few samples taken from the production batches.

The idea here proposed is to improve the efficiency of these tests by using electro‐optic techniques for the measurement of the vibration behaviour of the components under known excitation. This would allow the on‐line testing of a high percentage of the production and would be useful to give important feedback to the design process.

Scanning laser Doppler vibrometry seems to be a valuable solution for this problem, thanks to its capabilities of measuring several spatially‐defined points on a vibrating object with reduced testing time for on‐line application, with high sensitivity and accuracy, non‐intrusivity and with any kind of excitation signal. Experimental tests are performed on a power supply: the results show the effectiveness of the proposed approach. The metrological problems connected with the on‐line implementation are also discussed.
Experimental Study on the Vibration of an Overhung Rotor with a Propagating Transverse Crack
Authors: Adewusi S.A. , Al-Bedoor B.O.
Published: January 2014

This paper presents an experimental study on the dynamic response of an overhung rotor with a propagating transverse crack. The effects of a propagating transverse crack and side load on the dynamic response of an overhung rotor are investigated in order to identify vibration signatures of a propagating crack in rotating shafts. Startup and steady state vibration signatures were analyzed and presented in the form of Bode plots, Frequency Spectrum Cascades, Frequency Spectrum Waterfalls and orbits. The startup results showed that crack reduces the critical speed and increases the vibration amplitude of the rotor system. It also excites 2X vibration in the startup vibration signatures. The steady state results showed that the propagating crack produces changes in vibration amplitudes of 1X and 2X vibration harmonics and excites 3X harmonic just before fracture. During crack propagation, 1X amplitude may increase or decrease depending on the location of the crack and the direction of vibration measurement while 2X amplitude always increases. The steady state vibration signal of a propagating crack also produces a two‐loop orbit.
Theoretical Accounts of Gulf War Syndrome: From Environmental Toxins to Psychoneuroimmunology and Neurodegeneration
Authors: Ferguson Eamonn , Cassaday Helen J.
Published: January 2014

Non‐specific illness includes a wide variety of symptoms: behavioural (e.g., reduced food and water intake), cognitive (e.g., memory and concentration problems) and physiological (e.g., fever). This paper reviews evidence suggesting that such symptoms can be explained more parsimoniously as a single symptom cluster than as a set of separate illnesses such as Gulf War Syndrome (GWS) and chronic fatigue syndrome (CFS). This superordinate syndrome could have its biological basis in the activity of pro‐inflammatory cytokines (in particular interleukin‐1: IL‐1), that give rise to what has become known as the ‘sickness response’. It is further argued that the persistence of non‐specific illness in chronic conditions like GWS may be (in part) attributable to a bio‐associative mechanism (Ferguson and Cassaday, 1999). In the case of GWS, physiological challenges could have produced a non‐specific sickness response that became associated with smells (e.g., petrol), coincidentally experienced in the Persian Gulf. On returning to the home environment, these same smells would act as associative triggers for the maintenance of (conditioned) sickness responses. Such associative mechanisms could be mediated through the hypothalamus and limbic system via vagal nerve innervation and would provide an explanation for the persistence of a set of symptoms (e.g., fever) that should normally be short lived and self‐limiting. We also present evidence that the pattern of symptoms produced by the pro‐inflammatory cytokines reflects a shift in immune system functioning towards a (T‐helper‐1) Th1 profile. This position contrasts with other immunological accounts of GWS that suggest that the immune system demonstrates a shift to a Th2 (allergy) profile. Evidence pertaining to these two contrasting positions is reviewed.
Pergolide Mesilate May Improve Fatigue in Patients with Parkinson’s Disease
Authors: Abe Kazuo , Takanashi Mayako , Yanagihara Takehiko , Sakoda Sabro
Published: January 2014

Objectives: Fatigue is a complaint frequently encountered among patients with Parkinson’s disease (PD). Considering the possible relationship between fatigue and dopaminergic dysfuncion, we investigated the effect of pergolide mesilate (a D2 and D1 dopamine receptor agonist) and bromocriptine (a D2 selective dopamine receptor) in patients with PD.

Methods: We evaluated 41 patients with PD and controls. We assessed the degree of fatigue by using a fatigue scale. The severity of PD was evaluated by the Hoehn and Yahr Scale and the unified Parkinson’s disease rating scale (UPDRS).

Results: After five weeks from prescription, patients taking pergolide mesilate showed significant improvement in the fatigue scale (from 5.1 ± 0.7 to 4.4 ± 0.55, p < 0.05, ) but patients taking bromocriptine did not (from 4.8 ± 0.9 to 4.7 ± 0.8).

Conclusions: Our study suggested the possibility of functional correlation between fatigue and D1 receptor in patients with PD.
Is Grasping Impaired in Hemispatial Neglect?
Authors: Harvey Monika , Jackson Stephen R. , Newport Roger , Krämer Tanja , Morris D. Llewlyn , Dow Lindsay
Published: January 2014

Patients with right unilateral cerebral stroke, four of which showed acute hemispatial neglect, and healthy aged‐matched controls were tested for their ability to grasp objects located in either right or left space at near or far distances. Reaches were performed either in free vision or without visual feedback from the hand or target object. It was found that the patient group showed normal grasp kinematics with respect to maximum grip aperture, grip orientation, and the time taken to reach the maximum grip aperture. Analysis of hand path curvature showed that control subjects produced straighter right hand reaches when vision was available compared to when it was not. The right hemisphere lesioned patients, however, showed similar levels of curvature in each of these conditions. No behavioural differences, though, could be found between right hemisphere lesioned patients with or without hemispatial neglect on either grasp parameters, path deviation or temporal kinematics.
Effects of Level of Retrieval Success on Recall‐Related Frontal and Medial Temporal Lobe Activations
Authors: Montaldi Daniela , Mayes Andrew R. , Barnes Anna , Hadley Donald M. , Patterson Jim , Wyper David J.
Published: January 2014

Brain dedicated single photon emission computed tomography (SPECT) was used to compare the neuroactivation produced by the cued recall of response words in a set of studied word pairs with that produced by the cued retrieval of words semantically related to unstudied stimulus words. Six of the 12 subjects scanned were extensively trained so as to have good memory of the studied pairs and the remaining six were minimally trained so as to have poor memory. When comparing episodic with semantic retrieval, the well‐trained subjects showed significant left medial temporal lobe activation, which was also significantly greater than that shown by the poorly trained subjects, who failed to show significant medial temporal lobe activation. In contrast, the poorly trained subjects showed significant bilateral frontal lobe activation, which was significantly greater than that shown by the well‐trained subjects who failed to show significant frontal lobe activation. The frontal activations occurred mainly in the dorsolateral region, but extended into the ventrolateral and, to a lesser extent, the frontal polar regions. It is argued that whereas the medial temporal lobe activation increased as the proportion of response words successfully recalled increased, the bilateral frontal lobe activation increased in proportion to retrieval effort, which was greater when learning had been less good.
In‐Situ Residual Tracking in Reduced Order Modelling
Authors: Slater Joseph C. , Pettit Chris L. , Beran Philip S.
Published: January 2014

Proper orthogonal decomposition (POD) based reduced‐order modelling is demonstrated to be a weighted residual technique similar to Galerkin′s method. Estimates of weighted residuals of neglected modes are used to determine relative importance of neglected modes to the model. The cumulative effects of neglected modes can be used to estimate error in the reduced order model. Thus, once the snapshots have been obtained under prescribed training conditions, the need to perform full‐order simulations for comparison is eliminates. This has the potential to allow the analyst to initiate further training when the reduced modes are no longer sufficient to accurately represent the predominant phenomenon of interest. The response of a fluid moving at Mach 1.2 above a panel to a forced localized oscillation of the panel at and away from the training operating conditions is used to demonstrate the evaluation method.
Measuring Strain Response Mode Shapes with a Continuous‐Scan LDV
Authors: Stanbridge Anthony B. , Martarelli Milena , Ewins David J.
Published: January 2014

A continuous‐scan LDV is a convenient means for measuring the response mode shape (ODS) of a vibrating surface, particularly in view of the fact that the ODS is automatically derived as a spatial polynomial series. Second spatial derivatives of the deflection equations are therefore easily derived, and these should, in principle, give curvature equations from which, for a beam or plate of known cross‐section, stresses and strains can be obtained directly. Unfortunately, the stress and strain distributions depend critically on higher terms in the original ODS series, which are not accurately measured. This problem can be avoided by a method described here, which enables accurate stress and strain distributions to be derived, from a straight‐line LDV scan along a uniform beam, using only five terms in the mode‐shape polynomial series. A similar technique could be applied to uniform plates but the analysis and the governing equations are rather more complicated.
Analysis of Layered Composite Beam to Underwater Shock Including Structural Damping and Stiffness Effects
Authors: Gong S.W. , Lam K.Y.
Published: January 2014

This paper deals with the transient response of layered composite beams subjected to underwater shock. The Doubly Asymptotic Approximation (DAA) method is employed in this study to treat the fluid‐structure interactions. The effective structural damping and stiffness are formulated and incorporated in the fluid‐structure‐coupled equations, which relate the structure response to fluid impulsive loading and are solved using coupled finite‐element and DAA‐boundary element codes. The present computational method facilitates the study of transient response of the layered composite beams to underwater shock, involving the effects of structural damping and stiffness. In addition, the effect of free surface on the transient response of the layered beam to underwater shock is examined.
Wavelet Based Demodulation of Vibration Signals Generated by Defects in Rolling Element Bearings
Authors: Yiakopoulos C.T. , Antoniadis I.A.
Published: January 2014

Vibration signals resulting from roller bearing defects, present a rich content of physical information, the appropriate analysis of which can lead to the clear identification of the nature of the fault. The envelope detection or demodulation methods have been established as the dominant analysis methods for this purpose, since they can separate the useful part of the signal from its redundant contents. The paper proposes a new effective demodulation method, based on the wavelet transform. The method fully exploits the underlying physical concepts of the modulation mechanism, present in the vibration response of faulty bearings, using the excellent time‐frequency localization properties of the wavelet analysis. The choice of the specific wavelet family is marginal to their overall effect, while the necessary number of wavelet levels is quite limited. Experimental results and industrial measurements for three different types of bearing faults confirm the validity of the overall approach.
Numerical and Experimental Approach for Identifying Elastic Parameters in Sandwich Plates
Authors: Bastos Sergio Ferreira , Borges Lavinia , Rochinha Fernando A.
Published: January 2014

This article deals with the identification of elastic parameters (engineering constants) in sandwich honeycomb orthotropic rectangular plates. A non‐destructive method is introduced to identify the elastic parameters through the experimental measurements of natural frequencies of a plate undergoing free vibrations. Four elastic constant are identified. The estimation of the elastic parameter problem is solved by minimizing the differences between the measured and the calculated natural frequencies. The numerical method to calculate the natural frequencies involves the formulation of Rayleigh‐Ritz using a series of characteristic orthogonal polynomials to properly model the free edge boundary conditions. The analysis of the results indicates the efficiency of the method.
Active Controller Design for Microgravity Isolation Systems
Authors: Tsai Nan-Chyuan
Published: January 2014

This paper examines the performance of active isolation systems for microgravity space experiments as a function of desired transmissibilities that are chosen to be either much below or close to what can be tolerated. The control system utilizes two feedback signals: absolute acceleration and relative displacement of the controlled mass. The controller transfer function for acceleration feedback is chosen to avoid marginally stable pole‐zero cancellations. The controller transfer function for relative displacement feedback is determined to achieve the desired transmissibility function. The issue of stability and properness of this controller transfer function are discussed. The required input forces and equivalent closed‐loop stiffness are examined for various examples of desired transmissibilities.
Prevalence, and Intellectual Outcome of Unilateral Focal Cortical Brain Damage as a Function of Age, Sex and Aetiology
Authors: Braun C. M. J. , Montour-Proulx I. , Daigneault S. , Rouleau I. , Kuehn S. , Piskopos M. , Desmarais G. , Lussier F. , Rainville C.
Published: January 2014

Neurologists and neuropsychologists are aware that aging men are more at risk than women for brain damage, principally because of the well known male‐predominant risk for cardiovascular disease and related cerebrovascular accidents. However, a disproportion in prevalence of brain damage between the sexes in childhood may be less suspected. Furthermore, sex‐specific risk for other aetiologies of brain damage may be little known, whether in the pediatric or adult populations. Proposals of a sex difference in cognitive recovery from brain damage have also been controversial. Six hundred and thirty five “consecutive” cases with cortical focal lesions including cases of all ages and both sexes were reviewed. Aetiology of the lesion was determined for each case as was postlesion IQ. Risk was highly male prevalent in all age groups, with a predominance of cardiovascular aetiology explaining much of the adult male prevalence. However, several other aetiological categories were significantly male prevalent in juveniles (mitotic, traumatic, dysplasic) and adults (mitotic, traumatic). There was no sex difference in outcome (i.e., postlesion IQ) of these cortical brain lesions for the cohort as a whole, after statistical removal of the influence of lesion extent, aetiology and presence of epilepsy. Mechanisms potentially responsible for sex differences in prevalence, aetiology of brain damage, and recovery, are reviewed and discussed.
Knowing What You Need But Not What You Want: Affordances and Action‐Defined Templates in Neglect
Authors: Humphreys Glyn W. , Riddoch M. Jane
Published: January 2014

We examined search for target objects in a patient, MP, showing symptoms of left unilateral neglect. The conditions varied how the target was defined, the numbers of targets and distractors, and whether search was for multiple or single targets. We found that search was substantially improved when the target was defined by a description of its action rather than its name. This advantage for action‐defined targets increased with larger display sizes. For both action and name‐defined targets, there were also larger effects of the number of distractors when search was for multiple rather than single targets, even when the numbers of distractors were kept constant. However, these effects were increased for name‐defined targets. The differences between action‐ and name‐defined targets decreased when objects were replaced with words. The data suggest that search could be based on action‐defined templates of targets, activated by affordances from objects. The action‐defined templates facilitated detection and reduced MP′s tendency to re‐search displays.
New Technique for Evaluation of Global Vibration Levels in Rolling Bearings
Authors: de Almeida Rui Gomes Teixeira , da Silva Vicente Silmara Alexandra , Padovese Linilson Rodrigues
Published: January 2014

In the last years new technologies and methodologies have been developed for increasing the reliability of fault diagnosis in mechanical equipment, mainly in rotating machinery. Global vibration indexes as RMS, Kurtosis, etc., are widespread known in industry and in addition, are recommended by international norms. Despite that, these parameters do not allow reaching reliable equipment condition diagnosis. They are attractive for their apparent simplicity of interpretation. This work presents a discussion about the diagnosis possibilities based on these traditional parameters. The database used comprises rolling bearings vibration signals taking into account different fault conditions, several shaft speeds and loading. The obtained results show that these global vibration parameters are limited regarding correct fault diagnosis, especially in initial faults condition. As an alternative method a new technique is proposed. This technique seeks to obtain a global parameter that makes better characterization of fault condition. This methodology, named Residual Energy, uses integration of the difference between the power spectrum density of the fault condition and the normal one. The results obtained with this technique are compared with the traditional RMS and Kurtosis.
On the Force Drop Off Phenomenon in Shaker Testing in Experimental Modal Analysis
Authors: Varoto Paulo Sergio , de Oliveira Leopoldo Pisanelli Rodrigues
Published: January 2014

The Electrodynamic Vibration Exciter (shakers) has been one of the most employed excitation sources in modal tests. The shaker is an electromechanical device that provides a mechanical motion due to the input signal sent to its coil. Despite being widely used, it is well known that the shaker interacts with the structure under test. In particular, when the structure passes through a given resonance, the force delivered by the shaker abruptly decreases, causing the so called drop off phenomenon. This paper aims to study this force drop off phenomenon in the single shaker modal testing. Analytical models are developed to help in understanding the physical principles involved in the interaction between the shaker and the structure under test. Experimental analyses are performed using different shakers as well as excitation signals, in order to evaluate the effects of the input signal, as well as the power amplifier operational modes, on the structure dynamics. Preliminary tests revealed that significant distortions might occur during vibration tests using shakers and these distortions significantly affect the determination of the structure response.
Wernicke‐Korsakoff Syndrome following Small Bowel Obstruction
Authors: Deb Shoumitro , Law-Min Richard , Fearnley David
Published: January 2014

We report a case of a 64‐year‐old lady who developed clinical features of Wernicke‐Korsakoff syndrome following a laparotomy for small bowel obstruction. Following the operation she developed paralytic ileus and required total parenteral nutrition for one month. A suspected history of average 40 units of weekly alcohol consumption prior to the operation could not be confirmed and the patient did not show any sign of alcohol dependence. Within a few months of treatment with a daily oral dose of thiamine 200 mgs supplemented by multivitamins the patient showed subjective evidence of improvement in confusion, confabulation, and anterograde amnesia, although objective tests showed residual deficits in many areas of cognitive functioning, including immediate and delayed recall of verbal and non‐verbal materials, planning and switching of attention.
Thermally Induced Principal Parametric Resonance in Circular Plates
Authors: Nayfeh Ali H. , Faris Waleed
Published: January 2014

We consider the problem of large‐amplitude vibrations of a simply supported circular flat plate subjected to harmonically varying temperature fields arising from an external heat flux (aeroheating for example). The plate is modeled using the von Karman equations. We used the method of multiple scales to determine an approximate solution for the case in which the frequency of the thermal variations is approximately twice the fundamental natural frequency of the plate; that is, the case of principal parametric resonance. The results show that such thermal loads produce large‐amplitude vibrations, with associated multi‐valued responses and subcritical instabilities.
Linear and Nonlinear Damage Detection Using a Scanning Laser Vibrometer
Authors: Vanlanduit Steve , Guillaume Patrick , Schoukens Johan , Parloo Eli
Published: January 2014

Because a Scanning Laser Vibrometer (SLV) can perform vibration measurements with a high spatial resolution, it is an ideal instrument to accurately locate damage in a structure. Unfortunately, the use of linear damage detection features, as for instance FRFs or modal parameters, does not always lead to a successful identification of the damage location. Measurement noise and nonlinear distortions can make the damage detection procedure difficult. In this article, a combined linear‐nonlinear strategy to detect and locate damage in a structure with the aid of a SLV, will be proposed. To minimize the effect of noise, the modal parameters will be estimated using a Maximum Likelihood Estimator (MLE). Both noise and nonlinear distortion levels are extracted using the residuals of a two‐dimensional spline fit. The validation of the technique will be performed on SLV measurements of a delaminated composite plate.
Dynamic Research of a Nonlinear Stochastic Vibratory Machine
Authors: Zhang Yimin , Liu Qiaoling , Wen Bangchun
Published: January 2014

This paper presents the dynamics problems of stochastic vibratory machine systems. The random responses of the vibratory machine systems with stochastic parameters subjected to random excitation are researched using a stochastic perturbation method. The numerical results are obtained. The dynamic characteristics of nonlinear stochastic vibratory machine are analyzed.
Multiple Fault Identification Method in the Frequency Domain for Rotor Systems
Authors: Bachschmid Nicolò , Pennacchi Paolo
Published: January 2014

Fault identification in rotor systems has been studied by many authors, but the considered malfunction is one single fault only, generally an unbalance. Real machines can be affected by several different types of faults; moreover sometimes also two different faults may develop simultaneously. A model based method for identifying multiple faults acting simultaneously on a rotor system in the frequency domain is briefly described and its robustness with regards to measuring and modelling errors is evaluated, by means of numerical simulations performed on the models of two typical power plant machines: a steam turbogenerator and a gas turbogenerator.
Lexical Processes and Eye Movements in Neglect Dyslexia
Authors: di Pellegrino Giuseppe , Làdavas Elisabetta , Galletti Claudio
Published: January 2014

Neglect dyslexia is a disturbance in the allocation of spatial attention over a letter string following unilateral brain damage. Patients with this condition may fail to read letters on the contralesional side of an orthographic string. In some of these cases, reading is better with words than with non‐words. This word superiority effect has received a variety of explanations that differ, among other things, with regard to the spatial distribution of attention across the letter string during reading. The primary goal of the present study was to explore the interaction between attention and lexical processes by recording eye movements in a patient (F.C.) with severe left neglect dyslexia who was required to read isolated word and non‐word stimuli of various length.

F.C.’s ocular exploration of orthographic stimuli was highly sensitive to the lexical status of the letter string. We found that: (1) the location to which F.C. directed his initial saccade (obtained approximately 230 ms post‐stimulus onset) differed between word and non‐word stimuli; (2) the patient spent a greater amount of time fixating the contralesional side of word than non‐word strings. Moreover, we also found that F.C. failed to identify the left letters of a string despite having fixated them, thus showing a clear dissociation between eye movement responses and conscious access to orthographic stimuli.

Our data suggest the existence of multiple interactions between lexical, attentional and eye movement systems that occur from very initial stages of visual word recognition.
Wavenumber Processing Techniques to Determine Structural Intensity and Its Divergence from Optical Measurements without Leakage Effects
Authors: Pascal Jean-Claude , Li Jing-Fang , Carniel Xavier
Published: January 2014

The technique of processing data in the wavenumber domain based on the Spatial Fourier Transform (SFT), is a powerful tool to compute higher‐order partial derivatives occurred in the expressions of the structural intensity and its divergence. However, performing directly the SFT usually results in great distortions if a discontinuity occurs in spatial periodicity (leakage effect). The worst thing is that the divergence of a free plate cannot correctly be estimated by existing wavenumber processing such as the STF and zero padding method. In this paper, a new algorithm ‐‐ mirror processing, is developed. By the use of vibrating velocity measured from the technique of laser scanning vibrometry, the structural intensity, its divergence and the force distribution are evaluated by different techniques of wavenumber processing. It is shown that the distortions caused by leakage effects can be removed by using advanced algorithms.
Frequency‐Dependent Viscoelastic Models for Passive Vibration Isolation Systems
Authors: Coronado Alberto , Trindade Marcelo A. , Sampaio Rubens
Published: January 2014

Even though there is a growing interest in active vibration isolation systems, passive approaches are still the best choice in many cases because they are inherently the simplest and of lowest cost. Moreover, better comprehension of the dynamics and specially of the damping behavior in passive systems is required for successful implementation of active schemes. In the vast literature of passive isolation systems, there are not many works that consider damping models more elaborated than the widely used complex modulus. In this work a passive isolation system composed of a base and two isolators, modelled as Timoshenko beams, and a vibration source, modelled as a rigid body, is considered. For the isolators, two different viscoelastic models are considered: the Anelastic Displacement Fields (ADF) and Fractional Calculus (FC), which will be compared with the complex modulus model. The results show that both ADF and FC models lead to better approximation of dissipated energy, since they account for frequency‐dependence of the viscoelastic isolators. Analysis of the curve‐fitting of material parameters, using ADF and FC models has shown that generally less parameters are needed by FC model, for the same fitting quality, although optimization results depends strongly on the initial guess for the solution.
Safe Zones for Shock‐Protection of Fragile Components during Impact‐Induced Clatter
Authors: Goyal Suresh , Papadopoulos James M.
Published: January 2014

Clattering motion that occurs when flat objects strike the ground at an oblique angle is studied through a simple, tractable, model of a rigid bar with arbitrary, but symmetric, mass distribution and coefficient of restitution. The maximum velocity changes, or velocity shocks, that occur at various locations of the bar as it clatters to rest, are presented. It is shown that different parts of the bar can be subjected to sequences of velocity changes that are both higher, and lower, than those encountered in a single clatter‐free impact. The implication that the drop‐tolerance of an electronic product can be increased by configuring it to have ‘safe zones’ – where the velocity shocks are lower – for the placement of fragile components, is analysed. It is shown, through example, that a significant safe zone can be created in the center of the product by configuring it to have a low moment of inertia and by minimizing coefficient of restitution.
The Effects of Unilateral Pulvinar Damage in Humans on Reflexive Orienting and Filtering of Irrelevant Information
Authors: Danziger Shai , Ward Robert , Owen Vanessa , Rafal Robert
Published: January 2014

The effects of damage to the pulvinar nucleus of the thalamus in humans on reflexive orienting and selective attention were investigated. In a spatial orienting task three patients with unilateral pulvinar damage determined the location of a visual target that followed a cue that was not informative as to the targets location. Contralesional targets were responded to more slowly than ipsilesional targets. Also, at long cue target intervals patients responses to contralesional targets that appeared at previously cued locations were slower than to non‐cued locations indicating that pulvinar damage does not affect inhibition of return. In the selective attention task two of the patients identified a target that appeared at one level of a global‐local hierarchical stimulus while ignoring a distractor present at the other level. The distractor indicated either the same response as the target or a different response. Response times to targets in both visual fields were similar as were interference effects from the ignored distractors. These data indicate that engaging attention contralesionally is not impaired in discrimination tasks and that filtering of irrelevant information was not impaired contralesionally.
Integration of Pulsed‐Laser ESPI with Spatial Domain Modal Analysis
Authors: Auweraer H. Van der , Steinbichler H. , Haberstok C. , Freymann R. , Storer D.
Published: January 2014

The present paper discusses the various critical elements of a modal testing system based on pulsed‐laser holographic ESPI measurements. Such system allows making very high spatial resolution measurements on panel‐like structures at frequencies that are of relevance for the vibro‐acoustic behavior.

Next to the optical parts, the integration with the modal analysis procedure, including the integration of geometry and response information, is reviewed. The ESPI based Image‐domain frequency response functions are accumulated frequency by frequency. Special attention is paid to the modal parameter extraction of the large DOF number data, for which a special data reduction scheme was developed. The approach has been applied to several case studies related to car panels. The research was conducted in the context of the Brite/Euram project SALOME and the EUREKA project HOLOMODAL.
Identification of Rotary Machines Excitation Forces Using Wavelet Transform and Neural Networks
Authors: Lepore Francisco Paulo , Santos Marcelo Braga , Barreto Rafael Gonçalves
Published: January 2014

Unbalance and asynchronous forces acting on a flexible rotor are characterized by their positions, amplitudes, frequencies and phases, using its measured vibration responses. The rotary machine dynamic model is a neural network trained with measured vibration signals previously decomposed by wavelets. A typical compaction ratio of 2048:4 is achieved in this application, considering the stationary nature of the measured vibrations signals and the shape of the chosen wavelet function. The Matching Pursuit procedure, coupled to a modified Simulated Annealing optimization algorithm is used to decompose the vibration signals. The performance of several neural network with different input database sets is analyzed to define the best network architecture in the sense to achieve successful training, minimum identification error, with maximum probability to give the correct answers. The experiments are conducted on a vertical rotor with three rigid discs mounted on a flexible shaft supported by two flexible bearings. The vibration responses are measured at the bearings and at the discs. A methodology to balance flexible rotors based on the proposed identification methodology is also presented.
Comparison between Accelerometer and Laser Vibrometer to Measure Traffic Excited Vibrations on Bridges
Authors: Rossi G. , Marsili R. , Gusella V. , Gioffrè M.
Published: January 2014

The use of accelerometer based measurement techniques for evaluating bridge forced vibrations or to perform bridge modal analysis is well established. It is well known to all researchers who have experience in vibration measurements that values of acceleration amplitude can be very low at low frequencies and that a limitation to the use of accelerometer can be due to the threshold parameter of this kind of transducer. Under this conditions the measurement of displacement seems more appropriate. On the other hand laser vibrometer systems detect relative displacements as opposed to the absolute measures of accelerometers. Vibrations have been measured simultaneously by a typical accelerometer for civil structures and by a laser vibrometer equipped with a fringe counter board in terms of velocity and displacements. The accelerations calculated from the laser vibrometer signals and the one directly measured by the accelerometer has been compared.
An Analytical Study of Fire Out of Battery Using Magneto Rheological Dampers
Authors: Ahmadian Mehdi , Appleton Randall , Norris James A.
Published: January 2014

The application of magneto rheological dampers for controlling the dynamics of a fire out‐of‐battery recoil system is examined, using a dynamic simulation of a 105mm cannon. Upon providing a brief background on MR dampers and fire out‐of‐battery dynamics, we will describe the simulation model, along with some of the results obtained from the model. The simulation results show that although conventional hydraulic recoil dampers can be designed and tuned to control fire out‐of‐battery dynamics as effectively as MR dampers, they are not able to perform well when firing faults are encountered. The results show that MR dampers are able to adapt to the firing faults such as pre‐fire, hang‐fire, and misfire and provide "soft recoil" under all firing conditions. The inability of conventional hydraulic dampers to adapt to the firing faults can yield recoil dynamics that seriously jeopardize the performance of the gun. Therefore, the results presented here show that MR dampers may provide an enabling technology in achieving fire out‐of‐battery under all firing conditions.
Opposed Left and Right Brain Hemisphere Contributions to Sexual Drive: A Multiple Lesion Case Analysis
Authors: Braun Claude M. J. , Dumont Mathieu , Duval Julie , Hamel Isabelle , Godbout Lucie
Published: January 2014

Brain topographical studies of normal men have have shown that sexual excitation is asymmetric in the brain hemispheres. Group studies of patients with unilateral epileptic foci and other studies of patients with unilateral brain lesions have come to the same conclusion. The present study reviewed previously published single case reports of patients with frank hypo or hypersexuality subsequent to a unilateral brain lesion. Hyposexual patients tended to have left hemisphere lesions (primarily of the temporal lobe), and hypersexual patients tended to have right hemisphere lesions (primarily of the temporal lobe) (p < 0.05). We interpret this double dissociation as part of a more general phenomenon of psychic tone similarly dissociated with regard to hemispheric control, including mood, psychomotor baseline, speech rate, and even immunity. The behavioral significance of this psychic tone is to modulate approach versus avoidance behavior.
A Combination of Modal Synthesis and Subspace Iteration for an Efficient Algorithm for Modal Analysis within a FE‐Code
Authors: Zehn M.W.
Published: January 2014

Various well‐known modal synthesis methods exist in the literature, which are all based upon certain assumptions for the relation of generalised modal co‐ordinates with internal modal co‐ordinates. If employed in a dynamical FE substructure/superelement technique the generalised modal co‐ordinates are represented by the master degrees of freedom (DOF) of the master nodes of the substructure. To conduct FE modal analysis the modal synthesis method can be integrated to reduce the number of necessary master nodes or to ease the process of defining additional master points within the structure. The paper presents such a combined method, which can be integrated very efficiently and seamless into a special subspace eigenvalue problem solver with no need to alter the FE system matrices within the FE code. Accordingly, the merits of using the new algorithm are the easy implementation into a FE code, the less effort to carry out modal synthesis, and the versatility in dealing with superelements. The paper presents examples to illustrate the proper work of the algorithm proposed.
Dynamic Stability of Rotating Blades with Transverse Cracks
Authors: Ng T.Y. , Lam K.Y. , Li Hua
Published: January 2014

In this paper, the main objective is to examine the effects of transverse cracks on the dynamic instability regions of an axially loaded rotating blade. The blade is modeled as an Euler‐Bernoulli beam. To reduce the governing equations to a set of ordinary differential equations in matrix form, Hamilton′s principle is used in conjunction with the assumed‐mode method. The crack is accounted for by considering the energy release rate and the parametric instability regions are obtained using Bolotin′s first approximation. Benchmark results are presented for cracked rotating blades at different rotating speeds, crack lengths and crack positions.
Ruggedizing Printed Circuit Boards Using a Wideband Dynamic Absorber
Authors: Ho V.C. , Veprik A.M. , Babitsky V.I.
Published: January 2014

The existing approaches to ruggedizing inherently fragile and sensitive critical components of electronic equipment such as printed circuit boards (PCB) for use in hostile industrial and military environment are either insufficient or expensive. This paper addresses a novel approach towards ruggedizing commercial‐off‐the‐shelf PCBs using a miniature wideband dynamic absorber. The optimisation technique used relies on the experimentally measured vibration spectra and complex receptance of the original PCB.

The analytical study and full‐scale experiment show that an optimised wideband dynamic absorber with the mass of only 15% relative to the total mass of the PCB is quite capable of the essential suppression of all relevant resonant responses of the PCB under shock, wideband random and sinusoidal vibration with variable frequency.
On Antiresonance in the Forced Response of Mistuned Bladed Disks
Authors: Jones Keith , Cross Charles
Published: January 2014

Mistuning in bladed disks usually increases the forced response of the maximum responding blade leading to shortened component life in turbine engines. This paper investigates mistuning using a transfer function approach where the frequency response functions (FRFs) are described by natural frequencies and antiresonant frequencies. Using this approach, antiresonant frequencies are shown to be a critical factor in determining the maximum blade response. Two insights are gained by formulating antiresonant frequencies as the eigenvalues of reduced system matrices: 1) Mistuning a particular blade has no effect on that blade′s antiresonant frequencies. 2) Engine orders N and N/2, where N is the number of blades on the disk, tend to produce the highest maximum local response. Numerical examples are given using a spring‐mass‐oscillator model of a bladed disk. Pole‐zero loci of mistuned bladed disks show that increased maximum blade response is often due to the damping of antiresonant frequencies. An important conclusion is that antiresonant frequencies can be arranged such that a mistuned bladed disk has a lower maximum blade response than a tuned bladed disk.
The Variance of Energy Estimates for the Product Model
Authors: Smallwood David
Published: January 2014

A product model, in which {x(t)}
, is the product of a slowly varying random window, {w(t)}, and a stationary random process, {g(t)}, is defined. A single realization of the process will be defined as x(t). This is slightly different from the usual definition of the product model where the window is typically defined as deterministic. An estimate of the energy (the zero order temporal moment, only in special cases is this physical energy) of the random process, {x(t)}, is defined as Relationships for the mean and variance of the energy estimates, m0, are then developed. It is shown that for many cases the uncertainty (4π times the product of rms duration, Dt, and rms bandwidth, Df) is approximately the inverse of the normalized variance of the energy. The uncertainty is a quantitative measure of the expected error in the energy estimate. If a transient has a significant random component, a small uncertainty parameter implies large error in the energy estimate. Attempts to resolve a time/frequency spectrum near the uncertainty limits of a transient with a significant random component will result in large errors in the spectral estimates.
The Association between Negative and Dysexecutive Syndromes in Schizophrenia: A Cross‐Cultural Study
Authors: Ihara H. , Berrios G. E. , McKenna P. J.
Published: January 2014

This paper examined the relationship between the ‘negative syndrome’ (NS) and the neuropsychological ‘dysexecutive syndrome’ (DES) in schizophrenia. The study also examined whether any relationship that exists between the NS and the DES holds equally for British and Japanese subjects. We compared 26 Japanese with 17 British schizophrenic patients, divided into ‘mild’ and ‘severe’ NS groups, on the basis of performance on neuropsychological tests, including the ‘Behavioural Assessment of Dysexecutive Syndrome’ (BADS). We found that patients with severe NS showed more everyday executive deficits than those with mild NS. The severity of NS was correlated with executive competence. The association between NS and the BADS performance was closer than that between NS and other conventional executive measures. These findings were not influenced by cultural differences between Japanese and British subjects, and, hence, suggested the existence of culture‐neutral neurobehavioural processes.