bluuebunny/crossref_metadata_2025 huggingface dataset:
Finite Element Vibration and Dynamic Response Analysis of Engineering Structures
Authors: Mackerle Jaroslav
Published: January 2014

This bibliography lists references to papers, conference proceedings, and theses/dissertations dealing with finite element vibration and dynamic response analysis of engineering structures that were published from 1994 to 1998. It contains 539 citations. The following types of structures are included: basic structural systems; ground structures; ocean and coastal structures; mobile structures; and containment structures.
Emergency Gate Vibration of the Pipe‐Turbine Model
Authors: Predin Andrej , Klasinc Roman
Published: January 2014

The vibration behavior of an emergency gate situated on a horizontal‐shaft Kaplan turbine is studied. The analysis and transfer of the dynamic movements of the gate are quite complex. In particular the behavior is examined of the emergency gate for the case when the power unit is disconnected from the system or there is a breakdown of the guide vane system at the moment when the maximal head and capacity are achieved. Experimental‐numerical methods both in the time domain and in the frequency domain are employed. Natural vibrations characterize a first zone, corresponding to relatively small gate openings. As the gate opening increases, the vibration behavior of the gate becomes increasingly dependent on the swirl pulsations in the draft tube of the turbine. Finally, the data transfer from the model to the prototype by use of the dynamic similitude law is discussed.
Hybrid Active and Passive Control of Vibratory Power Flow in Flexible Isolation System
Authors: Xiong Y.P. , Wang X.P. , Xing J.T. , Price W.G.
Published: January 2014

A hybrid active and passive vibration control strategy is developed to reduce the total power flows from machines, subject to multiple excitations, to supporting flexible structures. The dynamic interactions between machines, controllers, and receiving structures are studied. A force feedback control process governed by a proportional control law is adopted to produce active control forces to cancel the transmitted forces in the mounts. Computational simulations of a simple and a multiple dimensional hybrid vibration isolation system are performed to study the force transmissibility and the total power flows from vibration sources through active and passive isolators to the supporting structures. The investigation focuses on the effects of a hybrid control approach to the reduction of power flow transmissions and the influence of the dynamic characteristics of the control on power flow spectra. The hybrid control mechanism is synthesised from the power flow analysis. Conclusions and control strategies, well supported by numerical simulations, are deduced providing very useful guidelines for hybrid vibration isolation design.
Stereotaxic Display of Brain Lesions
Authors: Rorden Chris , Brett Matthew
Published: January 2014

Traditionally lesion location has been reported using standard templates, text based descriptions or representative raw slices from the patient′s CT or MRI scan. Each of these methods has drawbacks for the display of neuroanatomical data. One solution is to display MRI scans in the same stereotaxic space popular with researchers working in functional neuroimaging. Presenting brains in this format is useful as the slices correspond to the standard anatomical atlases used by neuroimagers. In addition, lesion position and volume are directly comparable across patients. This article describes freely available software for presenting stereotaxically aligned patient scans. This article focuses on MRI scans, but many of these tools are also applicable to other modalities (e.g. CT, PET and SPECT). We suggest that this technique of presenting lesions in terms of images normalized to standard stereotaxic space should become the standard for neuropsychological studies.
The Use of Statistical Parametric Mapping (SPM96) as a Decision Aid in the Differential Diagnosis of Dementia Using 99mTc‐HMPAO SPECT
Authors: Barnes A. , Lusman D. , Patterson J. , Brown D. , Wyper D.
Published: January 2014

In this study standard patterns of cerebral perfusion based on classifications described in the literature have been chosen and the ability of experienced imaging specialists to categorise the 99mTc HMPAO SPECT scans of patients referred to the department for investigation of dementia has been compared before and after the calculation of Statistical Parametric Maps (SPM—Wellcome Dept of Cognitive Neurology). The primary aim was to investigate whether SPM is an effective decision aid and whether it impacts on the confidence of image reporting. The secondary aim was to examine the influence of SPM on the agreement between image reporting and clinical diagnosis. The results showed that there was a slight decrease in agreement between the imaging specialists after the introduction of additional information from SPM (K = 0.57 to K = 0.5) and that agreement between imaging reporting (including information from SPM) and clinical diagnosis was moderate (K = 0.28). This study was able to confirm that SPM is capable of producing meaningful significance maps of individual patients in a routine clinical environment. However, there was no overwhelming evidence that SPM was able to resolve many of the dilemmas associated with the use of SPECT for the differential diagnosis of dementia. In particular, interpretation of SPECT perfusion patterns in dementia is a bigger problem than the initial identification of abnormalities.
Subcortical Hypoperfusion following Surgery For Aneurysmal Subarachnoid Haemorrhage: Implications For Cognitive Performance?
Authors: Tooth C. L. , Tindale W. B. , Hadjivassiliou M. , Romanowski C. A. J. , Hunt E. , Pantke R. , Sagar H. J. , Mayes A. R.
Published: January 2014

The incidence and severity of cognitive deficits after surgery for aneurysmal subarachnoid haemorrhage and their relationship to aneurysm site remains controversial. The aim of this study was to investigate the pattern of regional cerebral blood flow which exists in patients one year post‐surgery and to identify whether different patterns exist which may be related to the type of cognitive deficit or the location of the aneurysm. 62 patients underwent cognitive assessment and HMPAO SPECT imaging at a mean time of 12 months following surgery. Results were compared to those from healthy control subjects (n = 55 for neuropsychological testing; n = 14 for SPECT imaging). In the patient group, significant stable cognitive deficits occurred in all cognitive domains but no cognitive measure differentiated aneurysm site. On SPECT images, statistical parametric mapping identified a large common area of subcortical hypoperfusion in the patient group as a whole. The findings of this study suggest a possible link between reduced subcortical function and the extent and severity of cognitive deficits.
Application of Time‐Frequency Analysis to Transient Data from Centrifuge Earthquake Testing
Authors: Newland David E. , Butler Gary D.
Published: January 2014

Centrifuge model experiments have generated complex transient vibration data. New algorithms for time‐frequency analysis using harmonic wavelets provide a good method of analyzing these data. We describe how the experimental data have been collected and show typical time‐frequency maps obtained by the harmonic wavelet algorithm. Some preliminary comments on the interpretation of these maps are given in terms of the physics of the underlying model. Important features of the motion that are not otherwise apparent emerge from the analysis. Later papers will deal with their more detailed interpretation and their implications for centrifuge modeling.
The Neuroactivation of Cognitive Processes Investigated with SPECT
Authors: Montaldi Daniela , Mayes Andrew R.
Published: January 2014

The last ten years have seen the development and expansion of an exciting new field of neuroscientific research; functional mapping of the human brain. Whilst many of the questions addressed by this area of research could be answered using SPECT, relatively few SPECT activation studies of this kind have been carried out. The present paper combines an evaluation of SPECT procedures used for neuroactivation studies, and their comparison with other imaging modalities (i.e., PET and fMRI), with a review of SPECT neuroactivation studies that yield information concerning normal brain function with a particular emphasis on the brain activations produced by memory processing. The paper aims to describe and counter common misunderstandings regarding potential limitations of the SPECT technique, to explain and illustrate which SPECT procedures best fulfill the requirements of a neuroactivation study, and how best to obtain information about normal brain function (whether using normal healthy subjects or patients) and finally to highlight SPECT’s potential future role in the functional mapping of the human brain.
Modal Testing Using Impact Excitation and a Scanning LDV
Authors: Stanbridge A.B. , Ewins D.J. , Khan A.Z.
Published: January 2014

If a laser Doppler vibrometer is used in a continuously‐scanning mode to measure the response of a vibrating structure, its output spectrum contains side‐bands from which the response mode shape, as defined along the scan line, may be obtained. With impact excitation, the response is the summation of a set of exponentially‐decaying sinusoids which, in the frequency domain, has peaks at the natural frequencies and at `sideband′ pseudo‐natural frequencies, spaced at multiples of the scan frequency. Techniques are described for deriving natural mode shapes from these, using standard modal analysis procedures. Some limitations as to the types of mode which can be analysed are described. The process is simple and speedy, even when compared with a normal point‐by‐point impact test survey. Information may also be derived, using a circular scan, on the direction of vibration, and angular vibration, at individual points.
Neural Network Identification and Control of a Parametrically Excited Structural Dynamic Model of an F‐15 Tail Section
Authors: El-Badawy Ayman A. , Nayfeh Ali H. , Van Landingham Hugh
Published: January 2014

We investigated the design of a neural‐network‐based adaptive control system for a smart structural dynamic model of the twin tails of an F‐15 tail section. A neural network controller was developed and tested in computer simulation for active vibration suppression of the model subjected to parametric excitation. First, an emulator neural network was trained to represent the structure to be controlled and thus used in predicting the future responses of the model. Second, a neurocontroller to determine the necessary control action on the structure was developed. The control was implemented through the application of a smart material actuator. A strain gauge sensor was assumed to be on each tail. Results from computer‐simulation studies have shown great promise for control of the vibration of the twin tails under parametric excitation using artificial neural networks.
Calibration of Accelerometers by Shock Excitation and Laser Interferometry
Authors: Link Alfred , von Martens Hans-Jüurgen
Published: January 2014

A signal processing method for determining the dynamic behavior of accelerometers by shock excitation and laser interferometry is presented. The method allows the shock sensitivity and the magnitude and phase lag of the complex sensitivity of accelerometers to be accurately measured. After digitizing the phase‐modulated signals at the output of a homodyne or heterodyne interferometer, the time‐dependent displacement is reconstructed on the basis of the principle of coherent demodulation. Data processing developed for determining peak value and spectrum of the acceleration efficiently suppresses disturbing quantities. Computer simulations and experiments proved that the shock parameters can be measured with expanded uncertainties of less than 0.2%. method has been adopted by the ISO/TC 108/SC 3 as a primary shock calibration method to be specified in a new international standard ISO 16063‐13 “Primary shock calibration using laser interferometry”.
Fatigue in Patients with Parkinson’s Disease
Authors: Abe Kazuo , Takanashi Mayako , Yanagihara Takehiko
Published: January 2014

Purpose: Fatigue is a complaint frequently encountered among patients with Parkinson’s disease (PD), however, the pathophysiological mechanism remains unclear. Methods: We evaluated fatigue in 26 patients clinically diagnosed to have PD (16 men, 10 women) and age‐ and sex‐ matched 26 controls (16 men, 10 women) without neurological deficits by using a fatigue scale. In addition to neurological and neuropsychological examinations, all patients underwent MRI and SPECT using 99mTc‐HMPAO. Results: Patients with PD had normal cognitive function as judged by the MMSE, but showed significantly high scores with the fatigue and depression scales in comparison to controls (p). There was no significant correlation between the depression scale and the fatigue scale, or between the degree of disability and the fatigue scale in patients with PD, although a significant correlation existed between the depression scale and the fatigue scale in controls. With SPECT, a significant correlation was found between the fatigue scale and the reduction of perfusion in the frontal lobe (p) in patients with PD. Conclusions: The present study suggested that sense of fatigue in patients with PD might be associated with frontal lobe dysfunction.
Mood and Cerebral Perfusion Revisited
Authors: Ebmeier Klaus P.
Published: January 2014

Twenty patients with major depression and observed diurnal variations of mood were examined using clinical and neuropsychological measures and perfusion HMPAO‐SPECT at 8 a.m. and 8 p.m. In thirteen patients depression scores varied more than 15% although 4 patients with reverse diurnal variation caused mean group depression scores to be not different between morning and evening. There was an overall trend for higher depression scores to be associated with higher perfusion in posterior cingulate. This was mainly accounted for by significant positive correlations in the morning scan in posterior, but also anterior cingulate and medial prefrontal cortex compared with evening scans. This means that morning regression slopes were steeper than evening slopes. This result is discussed with regard to possible interpretations, such as adaptive or habituating changes during the day that may occur in depressed patients.
A Study of Emotionalism in Patients Undergoing Rehabilitation following Severe Acquired Brain Injury
Authors: McGrath Joanna
Published: January 2014

The present study describes the phenomenon of emotionalism in a sample of brain injured patients of mixed aetiology, with a view to identifying issues relevant to clinical management, and possible causal factors. 82 subjects with severe acquired brain injury undergoing rehabilitation participated in a structured interview in which they were asked to report the presence/absence of emotionalism and degree of distress associated with it. Their overt crying behaviour was also observed and recorded. Independent variables that predicted crying during the interview were identified using a multiple logistic regression procedure. Prevalence rates of emotionalism‐tearfulness were high in this sample (52% self‐report, 36–41% Emotionalism‐laughter was much less common (13%) Emotionalism‐tearfulness was usually accompanied by negative affect, occurred in response to identifiable precipitants, and was often controllable. It was associated with major personal distress in about half the subjects who reported it. Independent variables which predicted crying behaviour were female gender and focal damage to the right cerebral hemisphere. It is concluded that an increased readiness to cry is common in people with severe acquired brain injury of mixed aetiology. The behaviour is meaningful, though not always distressing. The intensity of the behaviour is variable, and it may be most appropriate to regard emotionalism as a dimension rather than a syndrome. Implications for clinical management are discussed.
Application of Vibrational Power Flow to a Passenger Car for Reduction of Interior Noise
Authors: Lee S.K.
Published: January 2014

Reduction of structure‐borne noise in the compartment of a car is an important task in automotive engineering. Transfer path analysis using the vibroacoustic reciprocity technique or multiple path decomposition method has generally been used for structure‐borne noise path analysis. These methods are useful for solving a particular problem, but they do not quantify the effectiveness of vibration isolation of each isolator of a vehicle. To quantify the effectiveness of vibration isolation, vibrational power flow has been used for a simple isolation system or a laboratory‐based isolation system. It is often difficult to apply the vibrational power flow technique to a complex isolation system like a car. In this paper, a simple equation is derived for calculation of the vibrational power flow of an isolation system with multiple isolators such as a car. It is successfully applied not only to quantifying the relative contributions of eighteen isolators, but also to reducing the structure‐borne noise of a passenger car. According to the results, the main contributor of the eighteen isolators is the rear roll mount of an engine. The reduced structure‐borne noise level is about 5dBA.
Identification of Nonlinear Dynamic Behavior and Failure for Riveted Joint Assemblies
Authors: Langrand B. , Markiewicz E. , Deletombe E. , Drazétic P.
Published: January 2014

Many different types of rivets need to be modeled to analyze the crashworthiness of aircraft structures. A numerical procedure based on FE modeling and characterization of material failure constitutive models is proposed herein with the aim of limiting the costs of experimental procedures otherwise necessary to obtain these data. Quasi‐static and dynamic experiments were carried out on elementary tension (punched) and shear (riveted) specimens. No strain rate sensitivity was detected in the failure behavior of the riveted joint assemblies. Experimental data were used to identify the Gurson damage parameters of each material (2024‐T351 and 7050 aluminum alloys for the sheet metal plate and the rivet respectively) by an inverse method. Characterization gave rise to satisfactory correlation between FE models and experiments. Optimized parameters were validated for each material by means of a uniaxial tension test for the sheet metal plate and an ARCAN type specimen in pure tension for the rivet.
Orthogonality of Modes of Structures When Using the Exact Transcendental Stiffness Matrix Method
Authors: Chan K.L. , Williams F.W.
Published: January 2014

This paper presents theory, physical insight and results for mode orthogonality of piecewise continuous structures, including both coincident and non‐coincident natural frequencies. The structures are ones for which exact member equations have been obtained by solving the governing differential equations, e.g. as can be done for members of plane frames or prismatic plate assemblies. Such member equations are transcendental functions of the distributed member mass and the frequency. They are used to obtain a transcendental overall stiffness matrix for the structure, from which the natural frequencies are extracted by using the Wittrick‐Williams algorithm, prior to using any existing method to find the modes which are examined from the orthogonality viewpoint in this paper. The natural frequencies and modes found are the exact values for the structure in the sense that the usual finite element method approximations are avoided.
Performance Characteristics of the Magnetic Constrained Layer Damping
Authors: Baz A. , Poh S.
Published: January 2014

A new class of surface damping treatment is proposed to provide effective means for attenuating undesirable structural vibrations. The proposed treatment relies in its operation on the use of smart damping treatments which consist of integrated arrays of constrained visco‐elastic damping layers that are controlled passively by a specially arranged network of permanent magnets. The interaction between the magnets and the visco‐elastic layers aims at enhancing the energy dissipation characteristics of the damping treatments. In this manner, it would be possible to manufacture structures that are light in weight which are also capable of meeting strict constraints on structural vibration when subjected to unavoidable disturbances.

Emphasis is placed here on introducing the concept and the basic performance characteristics of this new class of smart Magnetic Constrained Layer Damping (MCLD) treatments. Comparisons are also presented with conventional Passive Constrained Layer Damping (PCLD) in order to determine the merits and limitation of the MCLD treatments.
Limiting Performance Analysis of Underwater Shock Isolation of a System with Biodynamic Response Using Genetic Algorithm
Authors: Zong Z. , Lam K.Y. , Gan Tessa
Published: January 2014

Biodynamic response of shipboard crew to underwater shock is of a major concern to navies. An underwater shock can produce very high accelerations, resulting in severe human injuries aboard a battleship. Protection of human bodies from underwater shock is implemented by installing onboard isolators. In this paper, the optimal underwater shock isolation to protect human bodies is studied. A simple shock‐structure‐isolator‐human interaction model is first constructed. The model incorporates the effect of fluid‐structure interaction, biodynamic response of human body, isolator influence. Based on this model, the optimum shock isolation is then formulated. The performance index and restriction are defined. Thirdly, GA (genetic algorithm) is employed to solve the formulated optimization problem. GA is a powerful evolutionary optimization scheme suitable for large‐scale and multi‐variable optimization problems that are otherwise hard to be solved by conventional methods. A brief introduction to GA is given in the paper. Finally, the method is applied to an example problem and the limiting performance characteristic is obtained.
Analysis of HMPAO SPECT Scans in Head Injury Using Statistical Parametric Mapping
Authors: Stamatakis E. A. , Wilson J. T. L. , Wyper D. J.
Published: January 2014

The paper examines the ability of Statistical Parametric Mapping (SPM) to contribute towards the quantitative analysis of HMPAO SPECT images containing lesions. A validation study is described in which SPECT images were created that contained synthetic lesions and were analysed with SPM. The study established a set of guidelines concerning the alignment, smoothing, and statistical analysis of images. These were then applied to analysis of SPECT scans from head injured patients. A demonstration is given of the use of SPM to identify localised blood flow abnormalities associated with cognitive deficits after head injury. Correlations between blood flow abnormalities and a test of visual memory are illustrated.
The Processing of Global and Local Visual Information in Alzheimer’s Disease
Authors: Matsumoto Eriko , Ohigashi Yoshitaka , Fujimori Misato , Mori Etsuro
Published: January 2014

We examined the quantitative and qualitative difference of the pattern with visuo‐cognitive processing impairment in patients with early onset AD (EOAD) and late onset AD (LOAD). We use a visual attention task introduced by Navon (1977) to examine the function to integrate local visual stimuli into global image. Although the ability to identify solid digits ether of large and small size presented at the same exposure duration, EOAD performance was poor in the global perception especially at the short duration (20~msec). We provide evidence that this dysfunction is attribute to the AD pathology specific to early onset type.
Familial Multiple Sclerosis with Repetitive Relapses of Manic Psychosis in Two Patients (Mother and Daughter)
Authors: Modrego Pedro J. , Ferrández Jaime
Published: January 2014

The clinical presentation of multiple sclerosis (MS) with psychiatric symptoms is uncommon but it is believed that MS patients are twice as likely to be afflicted with bipolar disorder as the general population. We report two cases (mother and daughter) of MS presenting with bipolar disorder in the form of recurrent manic psychosis and whose outcome was favourable with neuroleptics and corticosteroids. In both cases we found multiple hypersignal lesions on brain magnetic resonance imaging (MRI), especially in the right frontal lobe where we observed signs of activity. Apart from clinical and radiological concordance, the patients exhibited similar class I HLA alleles and identical class II HLA alleles. We focused discussion on whether there may be a common genetic susceptibility to both illnesses or whether MS caused psychiatric manifestations. The coincidence of psychiatric and neurological symptoms in most relapses supports the second hypothesis.
Underwater Shock Response of Circular HSLA Steel Plates
Authors: Rajendran R. , Narasimhan K.
Published: January 2014

Studies on shock response of circular plates subjected to underwater explosion is of interest to ship designers. Non‐contact underwater explosion experiments were carried out on air backed circular High Strength Low Alloy (HSLA) steel plates of 4 mm thickness and 290 mm diameter. The experiments were carried out in two phases. In the first phase, strain gauges were fixed at intervals of 30 mm from the centre of the plate and strains were recorded for the shock intensity gradually increasing to yielding. Semi‐analytical models were derived for the elastic strain prediction which showed good agreement with the experiments. Dynamic yield stress and the shock factor for yielding were established. In the second phase, individual plates were subjected to increasing shock severity until fracture and the apex bulge depth and the thickness strains were measured. Empirical models were derived to predict the plastic deformation which were validated through a fresh set of experiments. Analysis of the fractured surface by visual examination showed that there was slant fracture indicating ductile mode of failure and the same was corroborated by Scanning Electron Microscopic (SEM) examination.
Stochastic Finite Element Simulation of Uncertain Structures Subjected to Earthquake
Authors: Chakraborty Subrata , Dey Santi Sekhar
Published: January 2014

In present study, the stochastic finite element simulation based on the efficient Neumann expansion technique is extended for the analysis of uncertain structures under seismically induced random ground motion. The basic objective is to investigate the possibility of applying the Neumann expansion technique coupled with the Monte Carlo simulation for dynamic stochastic systems upto that extent of parameter variation after which the method is no longer gives accurate results compared to that of the direct Monte carlo simulation. The stochastic structural parameters are discretized by the local averaging method and then simulated by Cholesky decomposition of the respective covariance matrix. The earthquake induced ground motion is treated as stationary random process defined by respective power spectral density function. Finally, the finite element solution has been obtained in frequency domain utilizing the advantage of Neumann expansion technique.
Topographic Mapping of P300 and Frontal Cognitive Function in Parkinson’s Disease
Authors: Iijima Mutsumi , Osawa Mikio , Iwata Makoto , Miyazaki Akiko , Tei Hideaki
Published: January 2014

The purpose of this study was to evaluate the relationship between P300 that is one of the event‐related potentials and frontal cognitive functions in Parkinson’s disease (PD) without clinically apparent dementia.

Subjects were 20 PD cases 48 to 79 years of age, all of whom were within normal limits on the Mini‐Mental State examination, and 55 age‐matched healthy adults.

P300 was elicited with an auditory oddball paradigm and recorded at 15 sites on the scalp. Cognitive functioning of the frontal lobe was evaluated using the New Modified Wisconsin Card Sorting Test (WCST) and the Letter Pick‐Out Test (LPOT) which reflects selective attention and semantic categorization.

P300 latency was delayed in 30.0% of P300 demonstrated abnormal distribution in 20.0%. the WCST and the LPOT were abnormal in 15.0%, P300 latency significantly correlated with number of subcategories achieved on the WCST. P300 amplitude correlated with scores on the LPOT. These results suggest that cognitive dysfunction which linked partly to the frontal lobe might begin in PD even without clinically apparent dementia.
Dysexecutive Syndrome in Schizophrenia: A Cross‐Cultural Comparison between Japanese and British Patients
Authors: Ihara H. , Berrios G. E. , McKenna P. J.
Published: January 2014

This study tested the hypothesis that the dysexecutive syndrome of schizophrenia is impervious to cultural differences. 18 Japanese and 22 British patients and 14 Japanese and 19 British control subjects were compared on the BADS (Behavioural Assessment of Dysexecutive Syndrome), a comprehensive neuropsychological assessment battery, designed for ‘ecological validity’, and other measures of frontal executive functions (EFs). Both cultural groups of schizophrenic patients showed equally severe impairment in most executive tests including the BADS (verbal fluency and intelligence were less impaired). Irrespective of cultural origin, similar neuropsychological deficits were found in patients with minimal intellectual deterioration. Our study suggests that socio‐cultural background does not affect the dysexecutive profile of schizophrenia very much, and that neuropsychological assessment may possibly provide added clinical information relevant to the management and rehabilitation of schizophrenic patients across different cultures.
Development of Soft Tactile Sensor for Prostatic Palpation Diagnosis: Sensor Structure Design and Analysis
Authors: Jiang Zhongwei , Chonan Seiji , Tanahashi Yoshikatu , Kato Takuji , Tanaka Mami
Published: January 2014

This paper is concerned with the development of a palpation probe for assessment of prostatic cancer and hypertrophy. The sensor is constructed by layering two polivinylidene fluoride (PVDF) films into soft material layers such as vulcanized rubber and sponge rubber sheets. Since the contact condition between the sensor and soft objects influences the sensor output significantly, the improvement of its sensitivity is investigated by design of an attachment covered over the sensor surface. In this report, the theoretical model of the sensor and the design of the attachment are presented and the attachment is validated for soft substances due to experimental investigation. Finally, a compact probe developed for clinical testing is presented and the data obtained from the patients are treated by the wavelet transform for de‐noising. Some representative clinical data show that the sensor could be a useful tool for group medical checkup on prostatic cancer and hypertrophy.
Curve Veering: Inherent Behaviour of Some Vibrating Systems
Authors: Bhat B.B.
Published: January 2014

The plots of variation of eigenvalues of vibrating structures with a system parameter often cross each other or abruptly veer away avoiding the crossing. The phenomenon is termed as curve veering and has been observed both in approximate solutions as well as in exact solutions associated with vibration of some vibrating systems. An explanation to such behavior is provided and illustrated by solving a simple example. The curve veering behavior is induced into a membrane by introducing a parameter that can change the mathematical model from an exact form to an approximate one. Approximate deflection functions such as those used in Galerkin′s method or the Rayleigh Ritz method invariably create an approximate or a ficticious system model in lieu of the actual system. The ficticious system may exhibit curve veering while the corresponding real system has no such behaviour. When the ficticious nature of the system is minimized by using large number of terms in the approximate techniques or by discretisation of the domain as in finite difference or by assuming spline type deflection functions, the curve veering behavior subsides and in some cases almost vanishes.
Neural Measures of Conscious and Unconscious Memory
Authors: Paller Ken A.
Published: January 2014

Neuropsychological studies of memory disorders have played a prominent role in the development of theories of memory. To test and refine such theories in future, it will be advantageous to include research that utilizes physiological measures of the neural events responsible for memory. Measures of the electrical activity of the brain in the form of event‐related potentials (ERPs) provide one source of such information. Recent results suggest that these real‐time measures reflect relevant encoding and retrieval operations. In particular, distinct electrical responses have been associated with recollective processing of words and with priming of visual word‐form. This source of evidence can thus enrich our understanding of both the cognitive structure and neural substrates of human memory.
An Experimental Technique for Structural Diagnostic Based on Laser Vibrometry and Neural Networks
Authors: Castellini Paolo , Revel Gian Marco
Published: January 2014

In recent years damage detection techniques based on vibration data have been largely investigated with promising results for many applications. In particular, several attempts have been made to determine which kind of data should be extracted for damage monitoring.

In this work Scanning Laser Doppler Vibrometry (SLDV) has been used to detect, localise and characterise defects in mechanical structures. After dedicated post‐processing, a neural network has been employed to classify LDV data with the aim of automating the detection procedure.

In order to demonstrate the feasibility and applicability of the proposed technique, a simple case study (an aluminium plate) has been approached using both Finite Element simulations and experimental investigations. The proposed methodology was then applied for the detection of damages on real cases, as composite material panels. In addition, the versatility of the approach was demonstrated by analysing a Byzantine icon, which can be considered as a singular kind of composite structure.

The presented methodology has proved to be efficient to automatically recognise defects and also to determine their depth in composite materials. Furthermore, it is worth noting that the diagnostic procedure supplied correct results for the three investigated cases using the same neural network, which was trained with the samples generated by the Finite Element model of the aluminium plate. This represents an important result in order to simplify and shorten the procedure for the training set preparation, which often constitutes the main problem for the application of neural networks on real cases or in industrial environments.
A Highly Accurate and Efficient Analytical Approach to Bridge Deck Free Vibration Analysis
Authors: Gorman D.J. , Garibaldi L.
Published: January 2014

The superposition method is employed to obtain an accurate analytical type solution for the free vibration frequencies and mode shapes of multi‐span bridge decks. Free edge conditions are imposed on the long edges running in the direction of the deck. Inter‐span support is of the simple (knife‐edge) type. The analysis is valid regardless of the number of spans or their individual lengths. Exact agreement is found when computed results are compared with known eigenvalues for bridge decks with all spans of equal length. Mode shapes and eigenvalues are presented for typical bridge decks of three and four span lengths. In each case torsional and non‐torsional modes are studied.
SPECT in Focal Epilepsies
Authors: Duncan Roderick
Published: January 2014

Brain perfusion changes during seizures were first observed in the 1930s. Single Photon Emission Computed Tomography (SPECT) was developed in the 1970s, and tracers suitable for the imaging of regional cerebral perfusion (rCP) became available in the 1980s. The method was first used to study rCP in the interictal phase, and this showed areas of low perfusion in a proportion of cases, mainly in patients with temporal lobe epilepsies. However, the trapping paradigm of tracers such as hexamethyl propyleneamine oxime (HMPAO) provided a practicable method of studying changes in rCP during seizures, and a literature was established in the late 1980s and early 1990s showing a typical sequence of changes during and after seizures of mesial temporal lobe origin; the ictal phase was associated with large increases in perfusion throughout the temporal lobe, with first the lateral, then the mesial temporal lobe becoming hypoperfused in the postictal phase. Activation and inhibition of other structures, such as the basal ganglia and frontal cortex, were also seen. Studies of seizures originating elsewhere in the brain have shown a variety of patterns of change, according to the structures involved. These changes have been used practically to aid the process of localisation of the epileptogenic zone so that epilepsy surgery can be planned.

Some neuroreceptors (e.g. benzodiazepine receptors) can be studied using SPECT, and have shown localised abnormalities. SPECT has also been used to study brain function during the intracarotid amytal test. SPECT images of all kinds can be analysed using numerical techniques such as statistical parametric mapping, and such techniques promise to improve the yield of information from ictal studies.
Cingulate Abnormalities Associated with PANSS Negative Scores in First Episode Schizophrenia
Authors: Ashton Liz , Barnes Anna , Livingston Martin , Wyper David , The Scottish Schizophrenia Research Group
Published: January 2014

There is evidence for the involvement of the cingulate gyrus in schizophrenia. We present details of a Statistical Parametric Mapping (SPM) analysis of SPECT data from the largest study (N = 39) of drug naive schizophrenic patients. The main findings are that there is decreased perfusion in the anterior cingulate during verbal fluency when patients are compared to controls (matched individually by age, gender and father’s social class as determined by occupation) and also that PANSS negative scores correlate negatively with regional cerebral blood flow in the cingulate gyrus (Pearson’s Correlation coefficient of r = − 0.49 and significance p < 0.005). This suggests that measurement of change of perfusion in this region could be a useful biological marker in assessing the effect of neuroleptics on negative symptoms.
Single Photon Emission Tomography Imaging in Parkinsonian Disorders: A Review
Authors: Acton Paul D. , Mozley P. David
Published: January 2014

Parkinsonian symptoms are associated with a number of neurodegenerative disorders, such as Parkinson’s disease, multiple system atrophy and progressive supranuclear palsy. Pathological evidence has shown clearly that these disorders are associated with a loss of neurons, particularly in the nigrostriatal dopaminergic pathway. Positron emission tomography (PET) and single photon emission tomography (SPECT) now are able to visualise and quantify changes in cerebral blood flow, glucose metabolism, and dopaminergic function produced by parkinsonian disorders. Both PET and SPECT have become important tools in the differential diagnosis of these diseases, and may have sufficient sensitivity to detect neuronal changes before the onset of clinical symptoms. Imaging is now being utilised to elucidate the genetic contribution to Parkinson’s disease, and in longitudinal studies to assess the efficacy and mode of action of neuroprotective drug and surgical treatments. This review summarises recent applications of SPECT imaging in the study of parkinsonian disorders, with particular reference to the increasing role it is playing in the understanding, diagnosis and management of these diseases.
Applications of DSP to Explicit Dynamic FEA Simulations of Elastically‐Dominated Impact Problems
Authors: Diehl Ted , Carroll Doug , Nagaraj Ben
Published: January 2014

Explicit Dynamic Finite Element techniques are increasingly used for simulating impact events of personal electronic devices such as portable phones and laptop computers. Unfortunately, the elastically‐dominated impact behavior of these devices greatly increases the tendency of Explicit Dynamic methods to calculate noisy solutions containing high‐frequency ringing, especially for acceleration and contact‐force data. For numerous reasons, transient FEA results are often improperly recorded by the analyst, causing corruption by aliasing. If aliasing is avoided, other sources of distortion can still occur. For example, filtering or decimating Explicit Dynamic data typically requires extremely small normalized cutoff frequencies that can cause significant numerical problems for common DSP programs such as MATLAB. This paper presents techniques to combat the unique DSP‐related challenges of Explicit Dynamic data and then demonstrates them on a very challenging transient problem of a steel ball impacting a plastic LCD display in a portable phone, correlating simulation and experimental results.
On the Steady State Response of a Cantilever Beam Partially Immersed in a Fluid and Carrying an Intermediate Mass
Authors: Al-Qaisia A.A. , Hamdan M.N. , Al-Bedoor B.O.
Published: January 2014

This paper presents a study on the nonlinear steady state response of a slender beam partially immersed in a fluid and carrying an intermediate mass. The model is developed based on the large deformation theory with the constraint of inextensible beam, which is valid for most engineering structures. The Lagrangian dynamics in conjunction with the assumed mode method is utilized in deriving the non‐linear unimodal temporal equation of motion. The distributed and concentrated sinusoidal loads are accounted for in a consistent manner using the assumed mode method. The non‐linear equation of motion is, analytically, solved using the single term harmonic balance (SHB) and the two terms harmonic balance (2HB) methods. The stability of the system, under various loading conditions, is investigated. The results are presented, discussed and some conclusions on the partially immersed beam nonlinear dynamics are extracted.
Review: Modeling Damping in Mechanical Engineering Structures
Authors: Lalanne Michel
Published: January 2014

This paper is concerned with the introduction of damping effects in the analysis of mechanical engineering structures. Damping can be considered as being generated by concentrated elements, by distributed elements, or by several effects existing simultaneously. Modeling damping for different engineering situations is described and some applications are presented briefly.

Erratum to “Review: Modeling Damping in Mechanical Engineering Structures”dx.doi.org/10.1155/2000/481496
Analyzing the Total Structural Intensity in Beams Using a Homodyne Laser Doppler Vibrometer
Authors: Freschi Agnaldo A. , Pereira Allan K.A. , Ahmida Khaled M. , Frejlich Jaime , Arruda José Roberto F.
Published: January 2014

The total structural intensity in beams can be considered as composed of three types of waves: bending, longitudinal, and torsional. In passive and active control applications, it is useful to separate each of these components in order to evaluate their contribution to the total structural power flowing through the beam. In this paper, a twisted z‐shaped beam is used in order to allow the three types of waves to propagate. The contributions of the structural intensity, due to these waves, are computed from measurements taken over the surface of the beam with a simple homodyne interferometric laser vibrometer. The optical sensor incorporates some polarizing optics, additional to a Michelson type interferometer, to generate two optical signals in quadrature, which are processed to display velocities and/or displacements. This optical processing scheme is used to remove the directional ambiguity from the velocity measurement and allows nearly all back‐scattered light collected from the object to be detect. This paper investigates the performance of the laser vibrometer in the estimation of the different wave components. The results are validated by comparing the total structural intensity computed from the laser measurements, with the measured input power. Results computed from measurements using PVDF sensors are also shown, and compared with the non‐intrusive laser measurements.
Vibration Control of Linear Split Stirling Cryogenic Cooler for Airborne Infrared Application
Authors: Veprik A.M. , Babitsky V.I. , Pundak N. , Riabzev S.V.
Published: January 2014

Modern infrared imagers often rely on the split Stirling cryogenic coolers the linear compressors of which are the well‐known sources of harmonic disturbance. The traditional method of their passive isolation fails to meet the restraints on the static and dynamic deflections which are originated by the combined action of the airborne g‐loading and harsh random vibration.

The vibration protection system, which combines a stiff and heavily damped vibration isolator with tuned dynamic absorber, is studied and optimised for use in the design of an airborne infrared device.

Such a design is aimed, primarily, at essential dynamic suppression of the harmonic force which is produced by the linear compressor and, secondarily, at minimisation of environmental vibration loads transmitted through the infrared device to the linear compressor. Experimental testing backed up the theoretical results.
Structural Modal Reanalysis of Topological Modifications
Authors: Chen Su Huan , Huang Cheng , Cao Zongjie
Published: January 2014

This paper presents a procedure for modal reanalysis of structures with topological modifications. The procedure is based on the results of initial modal analysis of the original structure. It is necessary for topological modifications with the increase of joints and the number of degrees of freedom. The research results show that the proposed method is effective and easy to implement on a computer.
Variable Modal Parameter Identification for Non‐Linear Mdof Systems. Part I: Formulation and Numerical Validation
Authors: Chong Y.H. , Imregun M.
Published: January 2014

This paper deals with the formulation of a frequency domain modal analysis technique that is applicable to weakly non‐linear multi‐degree of freedom (MDOF) systems with well‐separated modes. The concept of linear modal superposition is combined with the normal non‐linear mode technique, an approach that allows the formulation of a system identification procedure in terms of variable modal parameters. The numerical study was focused on a 4‐DOF system with cubic stiffness non‐linearity, and the modal parameters were obtained as functions of the modal amplitude. It was shown that the methodology was well suited to the study of practical cases for which the underlying linear model may be approximate. Similarly, the technique was found to be robust in the presence of measurement noise, though some adverse effects were observed for high noise levels. Once the variable modal parameters were extracted at some given force level, the non‐linear responses were predicted at other force levels via synthesis of normal non‐linear modes. The same responses were also obtained using a harmonic balance approach and very good agreement was obtained between the two sets of results. The procedure is well suited to the study of industrial cases because of its compatibility with existing finite element methods and linear modal analysis techniques.