bluuebunny/crossref_metadata_2025 huggingface dataset:
Accurate Assessment of Computed Order Tracking
Authors: Saavedra P.N. , Rodriguez C.G.
Published: January 2014

Spectral vibration analysis using the Fourier transform is the most common technique for evaluating the mechanical condition of machinery working in stationary regimen. However, machinery operating in transient modes, such as variable speed equipment, generates spectra with distinct frequency content at each time, and the standard approach is not directly applicable for diagnostic. The "order tracking" technique is a suitable tool for analyzing variable speed machines. We have studied the computed order tracking (COT), and a new computed procedure is proposed for solving the indeterminate results generated by the traditional method at constant speed. The effect on the accuracy of the assumptions inherent in the COT was assessed using data from various simulations. The use of these simulations allowed us to determine the effect on the overall true accuracy of the method of different user‐defined factors: the signal and tachometric pulse sampling frequency, the method of amplitude interpolation, and the number of tachometric pulses per revolution. Tests on real data measured on the main transmissions of a mining shovel were carried out, and we concluded that the new method is appropriate for the condition monitoring of this type of machine.
Fundamental and Subharmonic Resonances of Harmonically Oscillation with Time Delay State Feedback
Authors: EL-Bassiouny A.F.
Published: January 2014

Time delays occur in many physical systems. In particular, when automatic control is used with structural or mechanical systems, there exists a delay between measurement of the system state and corrective action. The concept of an equivalent damping related to the delay feedback is proposed and the appropriate choice of the feedback gains and the time delay is discussed from the viewpoint of vibration control. We investigate the fundamental resonance and subharmonic resonance of order one‐half of a harmonically oscillation under state feedback control with a time delay. By using the multiple scale perturbation technique, the first order approximation of the resonances are derived and the effect of time delay on the resonances is investigated. The fixed points correspond to a periodic motion for the starting system and we show the external excitation‐response and frequency‐response curves. We analyze the effect of time delay and the other different parameters on these oscillations.
Reduced Model in H∞ Vibration Control Using Linear Matrix Inequalities
Authors: Júnior Fernando Sarracini , Serpa Alberto Luiz
Published: January 2014

Many practical problems in structural dynamics are modeled with a high number of degrees of freedom in order to properly describe the structure. A formulation to design robust controllers is the H∞ technique where the controller has the same order of the mathematical model and this becomes unpractical and infeasible for most practical problems where the number of degrees of freedom is not small. One way to overcome this difficulty is to employ a model reduction technique, and design a reduced order controller based on this reduced model. In this case, it is required that the reduced controller ensures a good performance also for the nominal model (reduced) and for the real model (non‐reduced) of the structure. Since the reduced controller is designed based on a truncated dynamic model, the non‐modeled vibration modes can be excited causing the spillover phenomena, which is a severe undesirable effect. This work investigates the behavior of a reduced order controller obtained based on a reduced model through the Guyan reduction. The H∞ robust control and Linear Matrix Inequalities (LMI) formulations are employed to the problem of controlling a flexible structure subjected to an external disturbance. Some simulations are performed using a cantilever beam modeled by the finite element method. The results show that the Guyan reduced order model can be used to design a controller to the non‐reduced model with success.
Cognitive and Functional Deterioration in Patients with Severe COPD
Authors: Özge Cengiz , Özge Aynur , Ünal Özgür
Published: January 2014

The objective of this study was to examine the association among the duration of COPD, degree of hypoxemia, and neurological abnormalities including cognitive functioning. Fifty‐four patients with severe COPD and 24 age‐ and sex‐matched controls, were included in the study. All patients and controls were administered pulmonary function tests, standardized Mini‐mental State Examination (MMSE), Blessed Dementia Scale (BDS), Physical Self‐maintenance Scale (PSMS), Modified Activities of Daily Living scale (MADL), Instrumental Activities of Daily Living scale (IADL), Cornell Scale for Depression in Dementia (CSDD), Global Deterioration Scale (GDS) and Clinical Dementia Rating (CDR). In addition, detailed physical and neurological examinations were performed. Sixty‐four percent of patients with COPD showed abnormalities in MMSE, predominantly in recent memory, construction, attention, language, and orientation domains. Functional abnormalities were correlated with cognitive abnormalities. Although COPD patients did not show significant depression compared to controls, 77.7%. of the patients showed subjective and objective cognitive disturbance and 72.2% of the patients were classified as questionable or mild dementia. In conclusion, patients with COPD show significant cognitive and functional impairments that cannot be explained just by coincidence or by depression.
Dynamic Response of Shear‐Flexible Cylindrical Isotropic Shells with Clamped Edges
Authors: Sakka Zafer I. , Abdalla Jamal A. , Kabir H.R.H.
Published: January 2014

It is fundamental to obtain the natural frequencies and the corresponding mode shapes for cylindrical shells in order to determine their response to different dynamic loading. In this paper an analytical investigation to the free vibration response of moderately‐thick shear flexible isotropic cylindrical shells with all edges clamped is presented. The Sander’s kinematic relations for moderately thick cylindrical shell panels are utilized to develop the governing partial differential equations in conjunction with the boundary conditions. A recently developed generalized Navier’s approach, based on a boundary continuous double Fourier series expansion, is used as a solution methodology. A parametric study is presented with respect to various thicknesses, length and radius of curvature of the shell panel. The convergence of the solution method is established numerically for various parametric properties. The present results are compared with the results obtained from finite element method using a four‐node isoparametric shell element. The results thus presented should serve as bench‐mark solutions for future comparisons with numerical and approximate methods for calculation of free vibration parameters of moderately‐thick isotropic cylindrical shells.
Neuropharmacological Aspects of Cognitive Neurorehabilitation in Epilepsy
Authors: Mula Marco , Trimble Michael R.
Published: January 2014

The role of CNS neuromodulators in cognitive neurorehabilitation can be related to two main issues: (1) the negative impact on cognition of drug categories prescribed for different neurologic symptoms, such as spasticity, extrapyramidal symptoms, or epileptic seizures; (2) their possible role in neuroprotection and amelioration of the cognitive status of the patient, especially attention and memory. This paper reviews different pharmacological aspects of cognitive neurorehabilitation in epilepsy.
Comparison of Estimation Techniques for Vibro‐Acoustic Transfer Path Analysis
Authors: Padilha Paulo Eduardo França , de França Arruda José Roberto
Published: January 2014

Vibro‐acoustic Transfer Path Analysis (TPA) is a tool to evaluate the contribution of different energy propagation paths between a source and a receiver, linked to each other by a number of connections. TPA is typically used to quantify and rank the relative importance of these paths in a given frequency band, determining the most significant one to the receiver. Basically, two quantities have to be determined for TPA: the operational forces at each transfer path and the Frequency Response Functions (FRF) of these paths. The FRF are obtained either experimentally or analytically, and the influence of the mechanical impedance of the source can be taken into account or not. The operational forces can be directly obtained from measurements using force transducers or indirectly estimated from auxiliary response measurements. Two methods to obtain the operational forces indirectly – the Complex Stiffness Method (CSM) and the Matrix Inversion Method (MIM) – associated with two possible configurations to determine the FRF – including and excluding the source impedance – are presented and discussed in this paper. The effect of weak and strong coupling among the paths is also commented considering the techniques previously presented. The main conclusion is that, with the source removed, CSM gives more accurate results. On the other hand, with the source present, MIM is preferable. In the latter case, CSM should be used only if there is a high impedance mismatch between the source and the receiver. Both methods are not affected by a higher or lower degree of coupling among the transfer paths.
Art Produced By a Patient with Parkinson’s Disease
Authors: Chatterjee Anjan , Hamilton Roy H. , Amorapanth Prin X.
Published: January 2014

Artists with neurological diseases sometimes produce remarkably appealing art. Here we present the art of a patient with Parkinson’s disease, who demonstrated remarkable creativity and productivity well into the course of his disease. Despite his manifest motor impairments, he produced paintings and drawings with fluid sinuous movements. He also became preoccupied with his art in an unprecedented way, raising the possibility that his disease and medications were contributing to his creative drive.
Sensitivity Analysis of Viscoelastic Structures
Authors: de Lima A.M.G. , Stoppa M.H. , Rade D.A. , Steffen V.
Published: January 2014

In the context of control of sound and vibration of mechanical systems, the use of viscoelastic materials has been regarded as a convenient strategy in many types of industrial applications. Numerical models based on finite element discretization have been frequently used in the analysis and design of complex structural systems incorporating viscoelastic materials. Such models must account for the typical dependence of the viscoelastic characteristics on operational and environmental parameters, such as frequency and temperature. In many applications, including optimal design and model updating, sensitivity analysis based on numerical models is a very usefull tool. In this paper, the formulation of first‐order sensitivity analysis of complex frequency response functions is developed for plates treated with passive constraining damping layers, considering geometrical characteristics, such as the thicknesses of the multi‐layer components, as design variables. Also, the sensitivity of the frequency response functions with respect to temperature is introduced. As an example, response derivatives are calculated for a three‐layer sandwich plate and the results obtained are compared with first‐order finite‐difference approximations.
Non‐Linear Signal Analysis Applied to Surface Wear Condition Monitoring in Reciprocating Sliding Testing Machines
Authors: Neto Francisco Paulo Lépore , de Mello José Daniel Biasoli , dos Santos Marcelo Braga
Published: January 2014

When the surfaces of two elastic bodies present relative motions under certain amount of contact pressure the mechanical system can be unstable. Experiments conducted on elastic bodies in contact shown that the dynamic system is self‐excited by the non‐linear behavior of the friction forces. The main objective of this paper is to estimate the friction force using the vibrations signals, measured on a reciprocating wear testing machine, by the proposed non‐linear signal analysis formulation. In the proposed formulation the system global output is the sum of two outputs produced by a linear path associated in parallel with a non‐linear path. This last path is a non‐linear model that represents the friction force. Since the linear path can be identified by traditional signal analysis, the non‐linear function can be evaluated by the global input/output relationships. Validation tests are conducted in a tribological system composed by a sphere in contact with and a prismatic body, which has an imposed harmonic motion. The global output force is simultaneously measured by a piezoelectric and by a piezoresistive load cells. The sphere and prismatic body vibrations are measured by a laser Doppler vibrometer and by an accelerometer respectively. All signals are digitalized at the same time base and the data is transferred to a microcomputer. The non‐linear signal analysis technique uses this data to identify the friction force.
Vision Influence on Whole‐Body Human Vibration Comfort Levels
Authors: Duarte Maria Lúcia Machado , de Brito Pereira Matheus
Published: January 2014

The well being of people needs to be a priority in the modern world. In that respect, vibration cannot be one more cause of stress. Besides that, vibration comfort is very important, since high levels may cause health or even tasks′ accomplishment problems. Several parameters may influence the levels of vibration a human being supports. Among them, one can mention the influence of gender, age, corporeal mass index (CMI), temperature, humor, anxiety, hearing, posture, vision, etc. The first three parameters mentioned were already investigated in previous studies undertaken by GRAVI (Group of Acoustics and Vibration) researchers. In this paper, the influence of vision is evaluated. The main objective with this series of tests performed is to try to quantify in a future the influence of each parameter in a global vibration comfort level. Conclusions are presented for the parameter investigated.
Flight Path Reconstruction and Parameter Estimation Using Output‐Error Method
Authors: de Oliveira Maciel Benedito Carlos , Sandoval Góes Luiz Carlos , Hemerly Elder Moreira , Brasil Neto Nei Salis
Published: January 2014

This work describes the application of the output‐error method using the Levenberg‐Marquardt optimization algorithm to the Flight Path Reconstruction (FPR) problem, which constitutes an important preliminary step towards the aircraft parameter identification. This method is also applied to obtain the aerodynamic and control derivatives of a regional jet aircraft from flight test data with measurement noise and bias. Experimental results are reported, employing a real jet aircraft, with flight test data acquired by smart probes, inertial sensors (gyrometers and accelerometers) and Global Positioning Systems (GPS) receivers.
Dynamic Model of a Rotating Flexible Arm‐Flexible Root Mechanism Driven by a Shaft Flexible in Torsion
Authors: Ismail S.Z. , Al-Qaisia A.A. , Al-Bedoor B.O.
Published: January 2014

This paper presents a dynamic model of a rotating flexible beam carrying a payload at its tip. The model accounts for the driving shaft and the arm root flexibilities. The finite element method and the Lagrangian dynamics are used in deriving the equations of motion with the small deformation theory assumptions and the Euler‐Bernoulli beam theory. The obtained model is a nonlinear‐coupled system of differential equations. The model is simulated for different combinations of shaft and root flexibilities and arm properties. The simulation results showed that the root flexibility is an important factor that should be considered in association with the arm and shaft flexibilities, as its dynamics influence the motor motion. Moreover, the effect of system non‐linearity on the dynamic behavior is investigated by simulating the equivalent linearized system and it was found to be an important factor that should be considered, particularly when designing a control strategy for practical implementation.
Radiation Efficiencies for Steel Plates in Water
Authors: Rumerman M.L.
Published: January 2014

Statistical Energy (or similar) Analysis may use radiation efficiencies as a means of estimating acoustic power radiated by plates in bending vibration. It is common to calculate them using uncoupled sinusoidal mode shapes of simply supported plates to account for the plate boundaries and rib stiffeners. This paper shows that, when applied to steel plates bounded by water on one side, this procedure can significantly overestimate the acoustic power radiated for frequencies below about one‐eighth of the coincidence frequency. With water on both sides of the plate, the cutoff is increased to about one‐fourth of coincidence.
Estimation of Dynamic Characteristics of a Spring‐Mass‐Beam System
Authors: Zhou Ding , Ji Tianjian
Published: January 2014

This paper presents an approximate solution for the analysis of the dynamic characteristics of a spring‐mass‐beam system. The spring‐mass can be distributed or concentrated on a beam, which can represent a crowd or an individual on a beam. The analysis is based on the fact that a spring‐mass‐beam system can be modeled approximately as a series of two degree‐of‐freedom (TDOF) systems and the frequency coupling occurs mainly at the first TDOF system. The Galerkin method is used to derive the frequency equation of the TDOF system. Static beam functions of a beam with distributed and concentrated spring‐masses are developed for the solutions, in which the effect of the magnitude and position of the mass of the spring‐mass on the beam is considered. Using a set of simple formulae, the first pair of coupled frequencies and the corresponding mode can be obtained. The mass and stiffness factors in the TDOF system are tabled for engineering applications. For verification and use of the proposed method, a case of human‐structure interaction is analysed using the proposed method and FE method. Parametric studies show that using the proposed functions, not only the first pair of natural frequencies but also the mode and internal forces of the coupled system can be obtained with high accuracy.
Higher‐Order Nonlinear Vibration Analysis of Timoshenko Beams by the Spline‐Based Differential Quadrature Method
Authors: Zhong Hongzhi , Liao Minmao
Published: January 2014

Higher‐order nonlinear vibrations of Timoshenko beams with immovable ends are studied. The nonlinear effects of axial deformation, bending curvature and transverse shear strains are considered. The nonlinear governing differential equations are solved using a spline‐based differential quadrature method (SDQM), which is constructed based on quartic B‐splines. Ratios of the nonlinear to the linear frequencies are extracted and their variations with the ratio of amplitude to radius of gyration are examined. In contrast to the well‐recognized finding for the nonlinear fundamental frequency of beams, some higher‐order nonlinear frequencies decrease with the increase of ratio of amplitude to radius of gyration.
Ground Shock Attenuation on a Buried Cylindrical Structure by a Barrier
Authors: Kobielak Sylwester , Krauthammer Theodor , Walczak Adam
Published: January 2014

This paper presents results from studies on the influence of an attenuation barrier on soil stresses and pressures acting on a buried silo, caused by underground explosions at different distances from the structure. The attenuation barrier was made of PVC tubes that were placed between the explosive charges and the RC silo structure. Soil stress gages and pressure transducers were used to measure these data in the soil and on the structure, respectively. The influences of several parameters were analyzed for tests with and without an attenuation barrier between the silo and the explosive sources.
Optimal Impact Isolation for Injury Prevention Evaluated by the Head Injury Criterion
Authors: Balandin D.V. , Bolotnik N.N. , Crandall J.R. , Pilkey W.D. , Purtsezov S.V.
Published: January 2014

The optimal control of the deceleration of a particle moving along a straight line after an impact against an isolated surface is considered. The force applied to the particle by the surface is treated as the control variable. The deceleration distance is minimized subject to a constraint on the Head Injury Criterion functional. This functional is an integral criterion that is utilized in engineering biomechanics to evaluate the expected severity of impact‐induced head injury of a human being. The solution obtained provides characteristics of the limiting capabilities for the prevention of head injuries by means of an impact isolator, such as a coating of the surface against which the impacts occur. The head injuries can be due to impact occurrences, including traffic crashes, falling, and contacts with ballistic objects.
Psychogenic and Organic Amnesia. A Multidimensional Assessment of Clinical, Neuroradiological, Neuropsychological and Psychopathological Features
Authors: Serra Laura , Fadda Lucia , Buccione Ivana , Caltagirone Carlo , Carlesimo Giovanni A.
Published: January 2014

Psychogenic amnesia is a complex disorder characterised by a wide variety of symptoms. Consequently, in a number of cases it is difficult distinguish it from organic memory impairment. The present study reports a new case of global psychogenic amnesia compared with two patients with amnesia underlain by organic brain damage. Our aim was to identify features useful for distinguishing between psychogenic and organic forms of memory impairment. The findings show the usefulness of a multidimensional evaluation of clinical, neuroradiological, neuropsychological and psychopathological aspects, to provide convergent findings useful for differentiating the two forms of memory disorder.
Clinical Assessment of Motor Function: A Processes Oriented Instrument Based on a Speed‐Accuracy Trade‐Off Paradigm
Authors: Christe Blaise , Burkhard Pierre R. , Pegna Alan J. , Mayer Eugene , Hauert Claude-Alain
Published: January 2014

In this study, we developed a digitizing tablet‐based instrument for the clinical assessment of human voluntary movements targeting motor processes of planning, programming and execution. The tool was used to investigate an adaptation of Fitts′ reciprocal tapping task [10], comprising four conditions, each of them modulated by three indices of difficulty related to the amplitude of movement required. Temporal, spatial and sequential constraints underlying the various conditions allowed the intricate motor processes to be dissociated. Data obtained from a group of elderly healthy subjects (N = 50) were in agreement with the literature on motor control, in the temporal and spatial domains. Speed constraints generated gains in the temporal domain and costs in the spatial one, while spatial constraints generated gain in the spatial domain and costs in the temporal one; finally, sequential constraints revealed the integrative nature of the cognitive operations involved in motor production. This versatile instrument proved capable of providing quantitative, accurate and sensitive measures of the various processes sustaining voluntary movement in healthy subjects. Altogether, analyses performed in this study generated a theoretical framework and reference data which could be used in the future for the clinical assessment of patients with various movement disorders, in particular Parkinson’s disease.
The Clinical Overlap between the Corticobasal Degeneration Syndrome and Other Diseases of the Frontotemporal Spectrum: Three Case Reports
Authors: Raggi Alberto , Marcone Alessandra , Iannaccone Sandro , Ginex Valeria , Perani Daniela , Cappa Stefano F.
Published: January 2014

The corticobasal degeneration syndrome has been suggested to be part of a complex of conditions (including the different subtypes of frontotemporal dementia and progressive supranuclear palsy), which reflect a spectrum of pathological substrates. This concept is supported by the frequent clinical overlap that can be observed among patients diagnosed with these conditions. We report three clinical cases, characterized by the overlap of the clinical features of corticobasal degeneration syndrome with, respectively, nonfluent progressive aphasia, progressive supranuclear palsy and semantic dementia. Current diagnostic criteria emphasize differences in clinical presentation, which probably reflect the preferential location of pathology in the early stages of disease. However, with disease progression, a considerable clinical overlap can be expected among the different syndromes. This concept should be extended not only to the cognitive and behavioural features of the frontotemporal dementia subtypes, but also to the movement disorders of corticobasal degeneration and supranuclear palsy.
Cubic Velocity Feedback Control of High‐Amplitude Vibration of a Nonlinear Plant to a Primary Resonance Excitation
Authors: Jun Li , Rongying Shen , Hongxing Hua
Published: January 2014

High‐amplitude response suppression of the primary resonance of a nonlinear plant under cubic velocity feedback control is investigated. By means of the multiple scales method, two equations on the amplitude and phase of the response of the nonlinear system are obtained and the force‐response and frequency‐response curves are shown. The stability analyses for the open‐ and closed‐loop responses of the system are carried out and the performance of the control strategy is investigated. The instantaneous power requirement of the control law is also examined. It can be demonstrated that appropriate choice for the feedback gain can greatly reduce the response amplitude of the primary resonance and completely eliminate the multiple responses. Finally the perturbation solutions are verified with numerical simulations.
Relationship between Object‐Related Gestures and the Fractionated Object Knowledge System
Authors: Bartolo Angela , Daumüller Meike , Della Sala Sergio , Goldenberg Georg
Published: January 2014

The praxic semantic system comprises a conceptual knowledge system, which stores functional information about objects, and an action knowledge system, which stores information about the correct manipulation of objects. Moreover, mechanical problem solving abilities permit to take advantages from objects structure to use unfamiliar tools or discover alternative ways of using familiar tools. This study aims at investigating whether conceptual knowledge, action knowledge and mechanical problem solving abilities intervene in the production of gestures with objects (i.e. pantomimes and object use) by testing a group of brain damaged patients. Results showed that the mechanical problem solving abilities are not sufficient to produce pantomimes and that only severe deficits in the praxic semantic system would affect the production of these gestures. Furthermore, a double dissociation was observed between mechanical problem solving abilities and the capacity to use multiple objects. Overall, the results indicate that the praxic semantic system can be disrupted at different levels, suggesting that the semantic system for object has to be conceived as fractionated in different entities.
The Evaluation of the Damping Characteristics of a Hard Coating on Titanium
Authors: Blackwell Christopher , Palazotto Anthony , George Tommy J. , Cross Charles J.
Published: January 2014

Engine failures due to fatigue have cost the Air Force an estimated $400 million dollars per year over the past two decades. Damping treatments capable of reducing the internal stresses of fan and turbine blades to levels where fatigue is less likely to occur have the potential for reducing cost while enhancing reliability. This research evaluates the damping characteristics of magnesium aluminate spinel, MgO+Al2O3, (mag spinel) on titanium plates from an experimental point of view. The material and aspect ratio were chosen to approximate the low aspect ratio blades found in military gas turbine fans. In the past, work has generally been performed on cantilever supported beams, and thus the two‐dimensional features of damping were lost. In this study plates were tested with a cantilevered boundary condition, using electrodynamic shaker excitation. The effective test area of each specimen was 4.5 in × 4.5 in. The nominal plate thickness was 0.125 in. Mag spinel was applied to both sides of the plate, at a thickness of 0.01 in, and damping tests were run at room temperature. The effect of the coating was evaluated at the 2nd bending mode (mode 3) and the chord wise bending mode (mode 4). A scanning laser vibrometer revealed the frequency and shape of each mode for the plates. Sine sweeps were used to characterize the damping of the coated and uncoated specimens for the modes tested. The coating increased damping nonlinearly for both modes tested in which the general outcome was similar to that found in beams.
Development of Mortar Simulator with Shell‐In‐Shell System – Problem of External Ballistics
Authors: Fedaravicius A. , Jonevicius V. , Ragulskis M.
Published: January 2014

The shell‐in‐shell system used in the mortar simulator raises a number of non‐standard technical and computational problems starting from the requirement to distribute the propelling blast energy between the warhead and the ballistic barrel, finishing with the requirement that the length of warhead′s flight path must be scaled to combat shell firing tables. The design problem of the simulator is split into two parts – the problem of external ballistics where the initial velocities of the warhead must be determined, and the problem of internal ballistics – where the design of the cartridge and the ballistic barrel must be performed.
Development of Non‐Conservative Joints in Beam Networks for Vibration Energy Flow Analysis
Authors: Song Jee-Hun , Hong Suk-Yoon
Published: January 2014

Our work aims to find a general solution for the vibrational energy flow through a plane network of beams on the basis of an energy flow analysis. A joint between two semi‐infinite beams are modeled by three sets of springs and dashpots. Thus, the results can incorporate the case of complaint and non‐conservative in all the three degrees of freedom. In the cases of finite coupled structures connected at a certain angle, the derived non‐conservative joints and developed wave energy equation were applied. The joint properties, the frequency, the coupling angle, and the internal loss factor were changed to evaluate the proposed methods for predicting medium‐to‐high frequency vibrational energy and intensity distributions.
Persistent Visual Aura following Catheter Ablation in a Patient with WPW Syndrome
Authors: Koyama Shinichi , Kawamura Mitsuru
Published: January 2014

We report a patient who has had persistent visual disturbances since she underwent catheter ablation to treat her Wolff‐Parkinson‐White (WPW) syndrome. We examined her visual symptoms carefully and quantitatively by means of our newly developed method combining image‐processing and psychophysics. We first simulated the patient’s visual symptoms using image‐processing techniques. Since the simulation indicated that she would be very sensitive to the edges of the visual stimuli, we evaluated her sensitivity to the edges using psychophysics. The results indicated that she was hypersensitive to the clear‐cut edges of the visual stimuli. Her visual symptoms were very similar to those of visual aura of migraine, rather than those of photosensitive epilepsy. Magnetic resonance imaging (MRI) and single photon emission computed tomography (SPECT), electroenchepalogram (EEG), and visual‐evoked potentials (VEP) in the patient were normal. No abnormalities in her fundus, visual field, or electroretinogram were found, either. Transesophageal echocardiography with bubble study indicated that she had a preexisting right‐to‐left shunt. We hypothesize that visual aura of migraine was triggered and made persistent by the catheter ablation in this patient. Although the relationship between migraine, catheter ablation, and right‐to‐left shunts is unknown, previous studies on the transcatheter closure of patent foramen ovale suggest a possible link between them. Catheter ablation in patients with migraine and preexisting shunts may lead to exacerbations in migraine symptoms.
Vibration of the Duffing Oscillator: Effect of Fractional Damping
Authors: Borowiec Marek , Litak Grzegorz , Syta Arkadiusz
Published: January 2014

We have applied the Melnikov criterion to examine a global homoclinic bifurcation and transition to chaos in a case of the Duffing system with nonlinear fractional damping and external excitation. Using perturbation methods we have found a critical forcing amplitude above which the system may behave chaotically. The results have been verified by numerical simulations using standard nonlinear tools as Poincare maps and a Lyapunov exponent. Above the critical Melnikov amplitude μ_c, which a sufficient condition of a global homoclinic bifurcation, we have observed the region with a transient chaotic motion.
Anton’s Syndrome following Callosal Disconnection
Authors: Abutalebi J. , Arcari C. , Rocca M. A. , Rossi P. , Comola M. , Comi G. C. , Rovaris M. , Filippi M.
Published: January 2014

Anosognosia for cortical blindness, also called Anton’s syndrome, is a rare neurological disorder usually following bilateral lesions to occipital cortices. Neuropsychological, morphological and functional neuroimaging (SPECT and fMRI) findings are reported in a patient who incurred Anton’s syndrome after an ischaemic lesion confined to the left occipital lobe involving the corpus callosum. The present case study suggests that Anton′s syndrome may also follow from lesions disconnecting the occipital cortices.
Free Vibration Analysis of a Rectangular Plate with Kelvin Type Boundary Conditions
Authors: Kırışık R. , Yüksel Ş.
Published: January 2014

The transverse vibrations of a rectangular plate with the Kelvin type boundary conditions at four corners are investigated. The plate is modeled as being attached to four lumped spring‐damper systems at the corners. An analytical procedure is proposed based on the modal analysis. The completely free case of the plate is first studied. The expressions for the eigenfrequencies and eigenfunctions of the plate are obtained by utilizing the separation of variables. Then, the case in which the stiffness and the viscous damping as external forces acting at the corners of the plate is studied. Following the modal analysis procedure, the general solution for the equation of motion of the rectangular plate is derived. Some numerical results are presented.
The Potential of Dyslexic Individuals in Communication Design Education
Authors: Çorlu Muzaffer , Özcan O&gcaron;uzhan , Korkmazlar Ümran
Published: January 2014

If dyslexic individuals have the ability to express themselves in different ways, particularly in the field of modern graphic design, would they be a favoured group in creating the extraordinary and outstanding ideas that are required in communication design? The study group consisted of 20 primary school dyslexics between ages of 7–12 and 20 non‐dyslexics serving as a control group. A jury with four specialists evaluated the drawings gathered from the 40 participants. Even though we might not say surely that the dyslexics are the best possible candidates for communication design education, based on the statistical results we have concluded that they should be among the potential candidates for both general communication design education and for more specific minor study areas such as icon design.
The Time Delay Filtering Method for Cancelling Vibration on Overhead Transportation Systems Modelled as a Physical Pendulum
Authors: Peláez G. , Doval-Gandoy J. , Caparrini N. , García-Prada J.C.
Published: January 2014

An investigation of the response of a physical pendulum to time delay filtered inputs was conducted. It was shown that the physical pendulum model is more accurate than the simple pendulum for modelling the dynamic response of overhead cranes with loads hanging from hooks. Based on the physical pendulum model a Specified Time Delay filter for an experimental mini overhead crane was synthesized. While somewhat limited in the scope by the hardware conditions placed in the system, the results provide basic insights into the successful application of the Time Delay Filtering method to overhead cranes.
Field Tests and Simulation of Lion‐Head River Bridge
Authors: Fang Yao-Min , Pu Jun-Ping
Published: January 2014

Lion‐Head River Bridge is a twin bridge in parallel position. The east‐bounded was designed and constructed as a traditional prestress concrete box girder bridge with pot bearings; and the west‐bounded was installed with seismic isolation devices of lead rubber bearings. The behavior of the isolated bridge is compared with that of the traditional bridge through several field tests including the ambient vibration test, the force vibration test induced by shakers, the free vibration test induced by a push and fast release system, and the truck test. The bridges suffered from various extents of damage due to the Chi‐Chi and the Chi‐I earthquakes of great strength during the construction and had been retrofitted. The damage was reflected by the change of the bridges′ natural frequencies obtained from the ambient vibration tests. The models of the two bridges are simulated by the finite element method based on the original design drawings. Soil‐structure interaction was also scrutinized in this study. The simulation was then modified based on the results from the field tests. Dynamic parameters of bridges are identified and compared with those from theoretical simulation. The efficiency is also verified to be better for an isolated bridge.
Tunable Mechanical Filter for Longitudinal Vibrations
Authors: Asiri S.
Published: January 2014

This paper presents both theoretically and experimentally a new kind of vibration isolator called tunable mechanical filter which consists of four parallel hybrid periodic rods connected between two plates. The rods consist of an assembly of periodic cells, each cell being composed of a short rod and piezoelectric inserts. By actively controlling the piezoelectric elements, it is shown that the periodic rods can efficiently attenuate the propagation of vibration from the upper plate to the lower one within critical frequency bands and consequently minimize the effects of transmission of undesirable vibration and sound radiation. In such a filter, longitudinal waves can propagate from the vibration source in the upper plate to the lower one along the rods only within specific frequency bands called the “Pass Bands” and wave propagation is efficiently attenuated within other frequency bands called the “Stop Bands”. The spectral width of these bands can be tuned according to the nature of the external excitation. The theory governing the operation of this class of vibration isolator is presented and their tunable filtering characteristics are demonstrated experimentally as functions of their design parameters. The concept of this mechanical filter as presented can be employed in many applications to control the wave propagation and the force transmission of longitudinal vibrations both in the spectral and spatial domains in an attempt to stop/attenuate the propagation of undesirable disturbances.
Experimental Measurement of Picometer Scale Spontaneous Vibrations in a Precision Deployable Boom under Thermal Loading
Authors: Silver Mark J. , Peterson Lee D. , Hardaway Lisa M.R.
Published: January 2014

This paper reports observations and analysis of picometer scale spontaneous vibrations in a precision deployable boom under thermal loading. The structural test article is a deployable boom previously flown in space. It exhibited spontaneous vibrations during the temperature rise following a night to day transition on orbit. In an attempt to reproduce the spontaneous vibrations on the ground, the test article was thermally loaded within a mechanically stabilized test environment. Spontaneous vibrations were induced in these ground experiments. The vibrations were at a scale of motion for which current theories would not expect such a release. The amplitudes of these vibrations were on the order of a few dozen picometers, and the frequency was near 1500 Hz. Evidence of wave dispersion was detected in the vibrations.
Testing Conclusions From Functional Imaging of Working Memory with Data From Acute Stroke
Authors: Philipose Lisa E. , Alphs Hannah , Prabhakaran Vivek , Hillis Argye E.
Published: January 2014

Functional imaging studies indicate that the left hemisphere mediates verbal working memory, while the right hemisphere mediates both verbal and spatial working memory. We evaluated acute stroke patients with working memory tests and imaging to identify whether unilateral dysfunction causes deficits in spatial and/or verbal working memory deficits. While left cortical stroke patients had verbal working memory impairments (p < 0.003), right cortical stroke patients had both verbal (p < 0.007) and spatial working memory (p < 0.03) impairments, confirming functional imaging results. Patients with transient ischemic stroke and patients with non‐cortical stroke did not have significant deficits in working memory in either modality.
Right Hemisphere Involvement in Non‐Fluent Primary Progressive Aphasia
Authors: Repetto Claudia , Manenti Rosa , Cotelli Maria , Calabria Marco , Zanetti Orazio , Borroni Barbara , Padovani Alessandro , Miniussi Carlo
Published: January 2014

We described a 56‐years‐old man with a diagnosis of “non‐fluent primary progressive aphasia” (NfPPA). An accurate neuropsychological, neurological and neuroimaging evaluation was performed in order to assess clinical and behavioural features of the patient.

From a neuropsychological point of view, the patient showed a typical cognitive profile of subjects affected by NfPPA: a prominent language deficit, associated with impairments in several cognitive domains after three years from the onset of the symptomatology.

The most intriguing feature is that SPECT revealed hypoperfusion in the right frontal cortex, albeit the patient is right‐handed.

This unexpected finding shows that NfPPA may arise not only from cortical abnormalities in the language‐dominant left hemisphere, but also from right hemisphere involvement in a right hander (crossed aphasia).
Naming of Grammatical Classes in Frontotemporal Dementias: Linguistic and Non Linguistic Factors Contribute to Noun‐Verb Dissociation
Authors: Silveri Maria Caterina , Ciccarelli Nicoletta
Published: January 2014

We studied noun and verb naming in three main variants of frontotemporal dementia: the frontal variant(Fv‐FTD), primary progressive aphasia (PPA) and semantic dementia (SD). We further distinguished PPA in nonfluent and fluent forms and restricted diagnosis of SD to subjects with progressive semantic breakdown leading to agnosia for words and objects. Fv‐FTD and nonfluent‐PPA named objects better than actions, SD showed an inverse dissociation and no specific pattern emerged in fluent‐PPA. In this last group, in spite of the broad definition of fluent aphasia, quite heterogeneous patterns of language disorders and word class dissociation emerged when single‐subject analyses were performed. In fv‐FTD correlations between executive tasks and action naming were stronger than between executive tasks and object naming. We conclude that both linguistic and non linguistic factors, in particular an executive deficit, contribute to grammatical class dissociation. We also suggest that the fluent vs. nonfluent distinction does not reflect the complexity of primary aphasia.
Neural Substrates of Word Generation during Stroke Recovery: The Influence of Cortical Hypoperfusion
Authors: Prabhakaran V. , Raman S. P. , Grunwald M. R. , Mahadevia A. , Hussain N. , Lu H. , Van zijl P. C. M. , Hillis A. E.
Published: January 2014

Several studies have demonstrated reorganization of cognitive and motor function caused by stroke. This study examined the influence of hypoperfused brain regions, in addition to the area of the infarct itself, on reorganization of the cognitive processes underlying word generation in stroke patients. In addition, we also sought to determine the influence of hypoperfusion on the blood oxygen level dependent/(BOLD) effect. Subjects with left and right subacute or chronic subcortical strokes, along with normal controls, were imaged while performing a verbal fluency task (word generation). The study population included six normal subject and six stroke patients with subcortical infarcts and cortical hypoperfusion in the middle cerebral artery territory who had recovered or improved markedly in word fluency. While normal subjects displayed a left‐lateralized fronto‐temporo‐parietal and bilateral cingulo‐striatal‐thalamic‐cerebellar network, the activation pattern of stroke patients was determined both by the hypoperfused regions and infarcted areas of the brain. Specifically, patients showed diminished BOLD effect in the cortical regions that were hypoperfused, even though their infarcts were subcortical, and showed increased BOLD effect in the homologous regions of the normal hemisphere. This finding raises the possibility that cortical hypoperfusion in the absence of infarct can cause shift of language functions to the opposite, intact hemisphere. However, reduced BOLD effect in the task relative to rest was found in hypoperfused regions in two patients, raising the possibility that regional function persisted, even though vascular reactivity was impaired. Results illustrate the complexities of functional imaging studies of recovery in patients with vascular lesions.
The Diagnostic Role of Serum Inflammatory and Soluble Proteins on Dementia Subtypes: Correlation with Cognitive and Functional Decline
Authors: Öztürk Candan , Özge Aynur , Yalın Osman Özgür , Yılmaz İ. Arda , Delialioglu Nuran , Yıldız Çilem , Tesdelen Bahar , Kudiaki Cigdem
Published: January 2014

In the past years, the possible involvement of inflammation in the pathogenesis of dementia has been the subject of several investigations. However there are restricted data about the profile of the inflammatory and soluble proteins in well evaluated Alzheimer’s disease (AD), vascular dementia (VD), mild cognitive impairment (MCI) and healthy controls. There are also no reliable data regarding the relationship between the overlapping protein levels and cognitive or functional decline. We measured levels of IL‐1β, IL‐2, IL‐6, IL‐18, TNF‐α, β‐Amlyloid 1–40 and α1‐antichymotrypsin levels in plasma in groups of total 82 subjects with AD, MCI, VD and controls using enzyme‐linked immunosorbent assay (ELISA) method. Our study samples showed high levels of proinflammatory cytokine levels (especially IL‐18) in all patient groups but only high levels of α1‐antichymotrypsine in VD patients compared to controls. There is no significant correlation between the laboratory and clinical variables except for a link between IL‐1β and NPI scores of AD. In conclusion, this study yielded evidence of some shared mechanisms underlying AD and VD and thus motivates further studies of inflammatory markers in various types of dementia and MCI.