bluuebunny/crossref_metadata_2025 huggingface dataset:
Reliability and validity of a Comprehensive Environmental Questionnaire for community‐living elderly with healthcare needs
Authors: YABUWAKI Kenji , YAMADA Takashi , SHIGETA Masahiro
Published: June 2008

Background:  Although environmental factors play an important role in the quality of life of the elderly, no currently available scale is adequate for the comprehensive assessment of the environments of community‐living elderly in Japan. The present study developed a Comprehensive Environmental Questionnaire to assess factors affecting quality of life and examined its reliability, criterion‐related validity, and construct validity among community‐living elderly with healthcare needs.

Methods:  Participants were 178 elderly adults without dementing disorders, aged 60 years and older, who were currently using day care services or home‐visit rehabilitative services. Participants were selected from five regions of Japan. We asked participants to complete the Comprehensive Environmental Questionnaire—provisional version twice (with a 1 month interval in between) and World Health Organization Quality of Life—brief form at baseline.

Results:  Based on exploratory factor analysis, we restructured the Comprehensive Environmental Questionnaire—provisional version to the final version, with 14 items and a three‐factor structure. Cronbach's alpha for internal consistency for all items was 0.82. Spearman's rank correlation coefficients for test–retest reliability were 0.4 or greater for 10 items, and were statistically significant (P < 0.001) for all items. The correlation coefficient of the total score of the Comprehensive Environmental Questionnaire and the environment domain score of the World Health Organization Quality of Life—brief form was 0.63 (P < 0.001). Confirmatory factor analysis indicated that the Comprehensive Environmental Questionnaire as a second‐order factor model was an adequate fit to the data. All standardized path coefficients in the model were statistically significant (P < 0.01).

Conclusion:  The present study established high levels of reliability, criterion‐related validity, and construct validity for the Comprehensive Environmental Questionnaire, with the exception of test–retest reliability for four items among community‐living elderly with healthcare needs.
Possible role of the innate immunity in temporal lobe epilepsy
Authors: Van Gassen Koen L.I. , De Wit Marina , Koerkamp Marian J.A. Groot , Rensen Marije G.A. , Van Rijen Peter C. , Holstege Frank C.P. , Lindhout Dick , De Graan Pierre N.E.
Published: June 2008

Summary

Purpose: Temporal lobe epilepsy (TLE) is a multifactorial disease often involving the hippocampus. So far the etiology of the disease has remained elusive. In some pharmacoresistant TLE patients the hippocampus is surgically resected as treatment. To investigate the involvement of the immune system in human TLE, we performed large‐scale gene expression profiling on this human hippocampal tissue.

Methods: Microarray analysis was performed on hippocampal specimen from TLE patients with and without hippocampal sclerosis and from autopsy controls (n = 4 per group). We used a common reference pool design to perform an unbiased three‐way comparison between the two patient groups and the autopsy controls. Differentially expressed genes were statistically analyzed for significant overrepresentation of gene ontology (GO) classes.

Results: Three‐way analysis identified 618 differentially expressed genes. GO analysis identified immunity and defense genes as most affected in TLE. Particularly, the chemokines CCL3 and CCL4 were highly (>10‐fold) upregulated. Other highly affected gene classes include neuropeptides, chaperonins (protein protection), and the ubiquitin/proteasome system (protein degradation).

Discussion: The strong upregulation of CCL3 and CCL4 implicates these chemokines in the etiology and pathogenesis of TLE. These chemokines, which are mainly expressed by glia, may directly or indirectly affect neuronal excitability. Genes and gene clusters identified here may provide targets for developing new TLE therapies and candidates for genetic research.
THE IMPACT OF ACCULTURATION AMONG HISPANICS ON DRINKING OUTCOMES FOLLOWING BRIEF INTERVENTION IN THE TRAUMA CARE SETTING
Authors: Field C. , Harris T.R. , Caetano R.
Published: June 2008

Background:  In a study of brief intervention in the trauma care setting, a significant interaction between treatment and ethnicity was found among Hispanics. Hispanics receiving brief intervention based on motivational interviewing were significantly more likely to reduce their drinking. This study evaluates the unique role of acculturation among Hispanics on drinking outcomes following brief alcohol intervention in the trauma care setting.

Methods:  A randomized controlled trial of brief intervention based on motivational interviewing and semi‐structured interview was conducted in an urban level I trauma center. Among the patients recruited for this study were 537 Hispanics including 253 Spanish speaking only participants. Six and 12 month follow ups were completed with a 65% and 53% follow up rate, respectively. A lost to follow up analysis was conducted using logistic regression. Hierarchical Linear Modeling was used to evaluate the role of acculturation among Hispanics including place of birth and level of acculturation on drinking outcomes including volume per week, maximum amount consumed in one day, frequency of five or more per occasion, percent days abstinent and percent days heavy drinking. Analyses controlled for age, gender, employment status, marital status, prior alcohol treatment, type of injury and injury severity.

Results:  Ethnicity was a significant predictor of loss to follow up at 6 months (p<.01) but not 12 months. Hispanics born in the US were less likely to be lost to follow up at 6 and 12 months (OR=.4, 95% CI=.3‐.7). Acculturation was not significantly associated with loss to follow up at 6 or 12 months. Hispanics born in the US had higher volume per week (β=.7, se=.3, p<.01) and maximum amount consumed in one day (β=.6, se=.2, p<.01). Hispanics with low acculturation, had lower average volume per week (β=‐.9, se=.3, p<.01), maximum amount consumed in one day (β=‐.5,se=.2, p<.05) and frequency of five or more per occasion (β=‐.7, se=.3, o<.05). No significant interactions between treatment and acculturation or place of birth was observed (p>.50)

Conclusions:  While brief intervention based on motivational interviewing is effective among Hispanics in the trauma care setting, place of birth and acculturation influence treatment outcome.
OVARIECTOMY SENSITIZES A DELETERIOUS INTERACTION BETWEEN ETHANOL WITHDRAWAL AND AGING TO A GREATER DEGREE AFTER ABRUPT TERMINATION THAN GRADUAL TERMINATION OF ETHANOL
Authors: Jung Marianna E. , Wilson Andrew M. , Metzger Daniel , Brown Nastassia D. , Simpkins James W.
Published: June 2008

We have demonstrated that abrupt termination of chronic ethanol diet creates lipid peroxidation in young adult rats in a manner protected by endogenous estrogen [(17(‐estradiol (E2)]. In this study, we tested whether ovariectomy exacerbates a deleterious interaction between ethanol withdrawal (EW) and age at the levels of oxidative stress using a 3 month ethanol diet paradigm. 5‐, 12‐, and 16‐month‐old ovariectomized rats with oil pellet or E2 replacement received a liquid ethanol (6.5%) or control dextrin diet for 3 months. One group was terminated from the ethanol diet by step‐down concentrations of ethanol. Another group was terminated from the ethanol diet abruptly. Cerebellum, cortex, hippocampus were collected to assess the levels of carbonyls as a marker of oxidative damage to protein. Compared to groups with control dextrin diet and gradual termination of ethanol diet, EW groups showed a greater increase in protein carbonyls. Such phenomenon was more profound in older rats vs younger rats and more profound in ovariectomized rats vs in ovary intact rats. This increase in carbonyl contents was partially prevented by E2 implantation. These findings suggest that ovariectomy sensitizes brain to a deleterious interaction of EW with age in a manner that is more prominent after abrupt termination than a gradual termination of ethanol of long term ethanol diet (supported by NIAAA AA013864 and AA015982).
NEUROPROTECTION AGAINST ETHANOL MEDIATED OXIDATIVE STRESS AND APOPTOSIS VIA NRF2/ARE.
Authors: Stewart J.L. , Henderson G.I.
Published: June 2008

This study characterizes a neuroprotective pathway responsible for coordinated enhancement of astrocyte glutathione (GSH)‐homeostatic machinery. Injuries in fetal rat cortical neurons associated with Fetal Alcohol Syndrome are correlated to ethanol (E) exposure leading to increased oxidative stress, GSH depletion, and ultimately neuroapoptosis. Our lab has previously published that astrocytes protect neurons from E mediated apoptosis, via maintenance of GSH homeostasis. We hypothesize that neuroprotection is regulated by the activation of the anti‐oxidant response elements (ARE) contained in the 5’ regions of cytoprotective genes, via the master transcription factor Nrf2. To identify the role of E in astrocyte anti‐oxidant defense induction, we first employed an E time course to investigate Nrf2 protein expression. Primary cultured rat neonatal astrocytes were treated with 4mg/ml E at various time points. There was increased nuclear Nrf2 expression within 15 minutes after E treatment, and lasted up to 4 hours. Immunohistochemical studies corroborate cytoplasmic to nuclear translocation. Enhanced nuclear Nrf2 expression was further augmented by BSO pre‐treatment. In addition, the transcription factor Maf, which obligatorily dimerizes with Nrf2 to activate gene transcription, was increased by E or BSO. Known ARE inducers and oxidative stress mimicked the cytoplasmic to nuclear translocation seen in E treatment. To determine whether E increased GSH‐homeostatic machinery at the transcriptional level, cells were pre‐incubated with Actinomycin D, and subsequently treated with E. Nrf2 expression induced by E was abolished in the presence of AD suggesting that E increases Nrf2 by stimulating gene transcription. Transfection of Nrf2 siRNA completely ablated Nrf2 expression, and furthermore blocks the tert‐butyl hydroquinone induced Nrf2, GGT, and Mrp1 expression. Finally, we examined E's effect on Nrf2 ubiquitination. E decreased Nrf2 ubiquitination at 4 and 24 hours while not effecting overall ubiquitin levels in the cell suggesting another possible mechanism for Nrf2 protein level increase and subsequent nuclear translocation to activate ARE. Taken together, this suggests that Nrf2 is required for activation of ARE. The role of E in Nrf2‐ARE control of astrocyte neuroprotection needs to be further investigated. These points of regulation may allow for pharmacological augmentation of this crucial neuroprotective mechanism.
BINGE ALCOHOL CONSUMPTION IN ADOLESCENT AND ADULT MICE DIFFERENTIALLY REMODELS THE BRAIN TRANSCRIPTOME
Authors: Owen Julie A. , Velasquez Oscar , Levin Patricia S. , Wang Yan , Krishnan Harish , Atkinson Nigel S. , Bergeson Susan E.
Published: June 2008

Alcohol abuse in pre‐teens and teenagers continues to be a considerable problem in the United States. Not only can brain injury result, but also several studies have now cemented the role of underage drinking in an approximate 5‐fold increased risk for development of alcoholism. The mechanism by which the change in susceptibility occurs is not understood. Therefore, a mouse model of high alcohol consumption was utilized to further include the ability to test the consequences of differential drinking between adolescent and adult animals. Using genetically defined C57BL/6J x FVB/NJ F1 hybrid mice and a “Drinking in the Dark” (DID) protocol, we determined that young mice will drink more than their adult counterparts. Gene expression analysis by cDNA microarray hybridization of brain revealed significant differences in pathway regulation and an age‐apparent left shift of overall transcription by alcohol. Over‐represented transcription factor binding site usage following alcohol exposure was readily apparent in adult, but not adolescent brain. Epigenetic consequences were also uncovered. Chromatin immunoprecipitation (ChIP) analysis showed that alcohol changed the gene expression of Scn4b, a sodium channel beta subunit that modulates the kinetics of firing, through a mechanism involving the acetylation of histone H4. These findings indicate a clear age‐related difference in brain transcriptome plasticity following binge alcohol drinking.
Blood safety in Sub‐Saharan Africa: a multi‐factorial problem
Authors: Tagny Claude Tayou , Mbanya Dora , Tapko Jean‐Baptiste , Lefrère Jean‐Jacques
Published: June 2008

Although the World Health Organization (WHO) has set targets for safe blood by 2012, Sub‐Saharan Africa remains confronted with multi‐factorial issues that compromise blood safety in most countries of the region. Some of these include the development and implementation of national policies for transfusion, the recruitment of voluntary and unpaid donors, proper screening of collected blood as well as a strategy for its rational use in a setting already plagued by a high prevalence of blood‐borne agents, poverty, and sometimes organizational deficits. Furthermore, the organization of hemovigilance, as well as quality systems that could monitor transfusion practices is lacking in these settings. There is no funding and global improvement of blood safety has to be cheap to be feasible. Specific solutions for the African continent need to be developed and implemented. This paper examines the current status and difficulties of blood safety in Africa and reviews available data on transfusion medicine in the region.
Psychiatric morbidity in patients with Parkinson’s disease following bilateral subthalamic deep brain stimulation: literature review
Authors: Meagher Linton J. , Ilchef Ralf , Silberstein Paul , Cook Raymond J. , Wasson Daniel , Malhi Gin S.
Published: June 2008

Objective:

To provide a comprehensive review and evaluation of the literature pertaining to the psychiatric sequelae of deep brain stimulation (DBS) of the subthalamic nucleus (STN) in patients with Parkinson’s disease (PD).

Methods:

A structured search of the EMBASE, PsychINFO and MEDLINE databases was performed on articles published since the first use of STN DBS in 1993 for PD until March 2007. Non-human studies were excluded, along with studies reporting on unilateral DBS and studies reporting on the use of STN DBS for indications other than idiopathic PD. Ninety-seven articles were selected for inclusion in the review.

Results:

Patients with advanced PD have a high rate of psychiatric morbidity. STN DBS has been shown to be an effective treatment for the control of motor symptoms in advanced PD. Neurobehavioural side-effects are, however, relatively common following STN DBS. Side-effects include impaired executive function and verbal fluency, depression, hypomania, apathy, postoperative delirium, anxiety disorders and psychotic symptoms, especially hallucinations. The alteration in dopaminergic medication following surgery as well as the direct effect of STN stimulation both appear to contribute to the short-term and long-term postoperative psychiatric complications. Methodological issues that limit the applicability of the current literature in this field are highlighted.

Conclusions:

STN DBS is an effective treatment for the motor symptoms of advanced PD. However, further research is needed to assess the extent to which STN DBS contributes to or exacerbates psychiatric morbidity over and above that associated with advanced PD. Careful neuropsychiatric evaluation and monitoring are required in this patient group.
The Effects of Variable Speed Cutting on Vibration Control in Face Milling
Authors: Lin S. C. , DeVor R. E. , Kapoor S. G.
Published: June 2008

This paper discusses the use of variable speed cutting for vibration control in the face milling process. Both simulation and experimental results show that the self-excited vibrations that can occur during constant speed cutting, and hence put limitation on the possible size of cut, can be suppressed by continuously varying the spindle speed. Through both analytical and experimental studies, the shape of variable speed trajectory has been examined, in terms of both the trackability by the spindle servo system and performance in terms of vibration suppression. It was found that a sinusoidal wave because of its acceleration and jerk characteristics can be tracked more precisely than some other periodic waves. The dynamic face milling force model was used to study the effects of speed trajectory parameters, namely, the frequency and amplitude. The results, in general, show the method to be fairly robust to the specific nature of the machining situation in terms of both processing conditions and system dynamics. Speed trajectory design was, however, shown to be somewhat dependent upon the nominal cutting speed and dominant frequencies of the system.
The Maximum Drawing Ratio in Hydroforming Processes
Authors: Yossifon S. , Tirosh J.
Published: June 2008

The concept of Maximum Drawing Ratio (MDR), supplementary to the well-known Limit Drawing Ratio (LDR), is defined, examined, and illustrated by experiments. In essence the MDR is reached when the two basic failure modes, namely: rupture (due to tensile instability) and wrinkling (due to buckling instability) are delayed till they occur simultaneously. Thus the process is beneficially utilized for higher drawing ratio by postponing earlier interception of either one of the above failures alone. The ability to suppress (up to a certain extent) the appearance of these failure modes depends heavily on the fluid-pressure path which controls the hydroforming process. The effect of the material properties, like the strain hardening exponent, the normal anisotropy of the blank, etc., as well as the geometrical properties (i.e., the thickness of the blank, the radius of curvature at the lip, etc.) on the MDR, are considered here in some detail. The nature of the solutions by which MDR is reached is discussed.
An Enhanced Quality Evaluation System for Continuous Manufacturing Processes, Part 2: Application
Authors: Dooley K. J. , Kapoor S. G.
Published: June 2008

Following Part 1 of this work, which discussed the theory behind the design of an Enhanced Quality Evaluation System (EQES), Part 2 addresses the construction of the rule base which classifies how the transfer function of the process has changed and also details the least squares algorithms used to estimate the magnitude and time of occurrence of the change. An example showing how EQES could be used to improve the quality of a turning process is given. Also shown are results of a physical experiment which used EQES to monitor changes in force signals from an end milling process.
Acoustic Emission During Athermal Martensitic Transformation in Steels
Authors: Liu Xiangying , Kannatey-Asibu Elijah
Published: June 2008

A relationship developed earlier between acoustic emission signals and the process of athermal martensitic transformation based on the free energy associated with the process is extended and verified experimentally. The relationship is found to model the process characteristics very well. The intensity of AE signal generated during transformation was found to be proportional to the temperature derivative of the fraction of martensite, the cooling rate, and volume of specimen. The AE signal was also found to be related to the carbon content of the steel. During transformation, the signal intensity was found to increase to a peak, and then tail off near the end of the transformation. Values of the martensite start temperature obtained from plots of the total RMS squared AE signals were also found to correlate well with values from the literature.
Tolerances: Their Analysis and Synthesis
Authors: Lee Woo-Jong , Woo T. C.
Published: June 2008

Tolerance, representing a permissible variation of a dimension in an engineering drawing, is synthesized by considering assembly stack-up conditions based on manufacturing cost minimization. A random variable and its standard deviation are associated with a dimension and its tolerance. This probabilistic approach makes it possible to perform trade-off between performance and tolerance rather than the worst case analysis as it is commonly practiced. Tolerance (stack-up) analysis, as an inner loop in the overall algorithm for tolerance synthesis, is performed by approximating the volume under the multivariate probability density function constrained by nonlinear stack-up conditions with a convex polytope. This approximation makes use of the notion of reliability index [10] in structural safety. Consequently, the probabilistic optimization problem for tolerance synthesis is simplified into a deterministic nonlinear programming problem. An algorithm is then developed and is proven to converge to the global optimum through an investigation of the monotonic relations among tolerance, the reliability index, and cost. Examples from the implementation of the algorithm are given.
Experimental Investigations into Electrochemical Spark Machining of Composites
Authors: Jain V. K. , Tandon S. , Kumar P.
Published: June 2008

Reports have indicated the poor performance of the conventional type of cutting tools during machining of composites. In this paper electrochemical spark machining (ECSM) for the cutting and drilling of holes in the composites is being proposed. The feasibility of using ECSM for composites was first ascertained. Then, kevlar-fiber-epoxy and glass-fiber-epoxy composites as work material, copper as tool material, and an aqueous solution of NaCl as electrolyte were used. It has been concluded that the ECSM is a viable solution for cutting of Fiber Reinforced Plastics (FRP). For achieving desired accuracy, surface finish, and economics of the process, the machining parameters should be optimized.
A Study on Acoustic Emission from the Orthogonal Cutting Process
Authors: Blum T. , Inasaki I.
Published: June 2008

Comprehensive experiments have been conducted to determine the influence of cutting conditions on the generation of Acoustic Emission (AE) signals while machining S45C steel. The simultaneous observation of AE-sensor signals and tool dynamometer signals provides extensive data on the orthogonal cutting process. Theoretical relationships drawn between the energy content of the AE-signal and the plastic work of deformation in the primary and secondary cutting zone will be discussed with these data. In addition, shortcomings of the established theory will be highlighted. A relationship between the AE-signals generated and the strain rate will be estimated. The influence of flank wear on the generation of AE signals will be emphasized. Finally, the feasibility of utilizing AE in tool wear sensing will be pointed out while comparing AE-signal generation and machining force measurements for the orthogonal cutting process.
A Replacement Model for Multi-Tool Transfer Lines
Authors: Billatos S. B. , Kendall L. A.
Published: June 2008

Transfer lines have long been used for machining a single product at high production rates. This study deals with the transfer line, in particular, estimating the production time per part and the effect of using probability models in describing tool and machine lives. The production time is estimated using three major causes of line stoppage. An aspiration level criterion is used to establish a scheduled tool replacement interval. The aspiration decision parameter is system reliability. It is shown how a scheduled tool replacement interval could be established to obtain this reliability level. A methodology for selecting the replacement interval for a group of tools is developed and the impact of changing this interval on tool changing costs and tool failure costs is discussed. In this study, only a single premature tool failure is assumed to occur; however, the results are compared with multiple tool failures using the renewal function. It is shown that this single premature failure analysis is equivalent to the renewal function approach for machining systems having a reliability greater than 50 percent and tool failure variabilities having a coefficient of variation less than 1.0. Using the model developed in this paper, an example problem is presented. For this problem, electromechanical equipment failure and tool wear failures are modeled using the exponential and the Weibull probability distributions, respectively. Scheduled tool replacement intervals are developed for a range of target reliabilities. The part cycle time and operating cost for the transfer line based on these reliabilities are computed. These results are compared to the minimum cost reliability level. The minimum cost operating condition is dependent on the ratio of the scheduled replacement costs over the failure replacement costs. For the example presented, the reliability level at minimum cost is much lower than the desired target value of .9. This result illustrates the importance of conducting a careful analysis and using the results to help guide operating practices toward more efficient tool change practices and maintenance policies.
An Approximate Model to Calculate Foldover and Strains During Cold Upsetting of Cylinders Part II: Use of the Foldover Model to Estimate Friction
Authors: Ettouney O. M. , Stelson K. A.
Published: June 2008

This paper addresses an approach to calculate the friction coefficient during nonuniform compression of cylinders. The approach combines new friction-calibration curves (prepared using the finite-element analysis) that relate friction to workpiece shape and the foldover model from Part I. Foldover in upsetting is used in the same way that the change in internal diameter is used in the ring test to determine friction. However, the new approach has the advantage that measurements are taken directly from the workpiece. Comparisons of friction values calculated from the ring test and the new approach showed good agreement.
Effect of Thickness on the Pure Stretchability of Aluminum Sheets
Authors: Kobayashi M. , Kurosaki Y. , Kawai N.
Published: June 2008

The effects of the thickness, lubricant, and temper of metals on pure stretchability of aluminum sheets have been studied. The pure stretchability of the sheet metals was markedly deteriorated by decreasing both the thickness in every lubricant and the temper of metal used in this experiment. The optimum frictional coefficient, which gives a maximum of the critical forming depth, was found in this experiment, and it was confirmed to change with the thickness and temper of metal. The thickness dependence of the critical forming depth was analytically calculated by means of Hill’s diffuse neck criterion, Yamaguchi’s method based on M-K theory and the criterion proposed by Gotoh. The result calculated by Yamaguchi’s method was comparatively in good agreement with the experiment in soft aluminum sheet and the result by Gotoh’s method did so in the half-hard one.
Producing Three-Dimensional Shapes by Laser Milling
Authors: Hsu R. K. C. , Copley S. M.
Published: June 2008

A laser milling process employing a pulsed, carbon dioxide laser has been investigated using graphite as a model material. Material is removed by scanning the focused beam across the surface of the workpiece leaving behind a series of narrow, parallel, overlapping grooves. These grooves, together, constitute the removal of a thin layer of uniform thickness lying parallel to a layer plane. In order to remove layers bounded at the edge by upright walls perpendicular to the layer plane, the laser beam must be tilted with respect to the layer plane. Using this approach, it is possible to produce perpendicular steps and cylindrical surfaces.
Root Sum Squares Tolerance Analysis with Nonlinear Problems
Authors: Greenwood W. H. , Chase K. W.
Published: June 2008

Elementary tolerance analysis with nonlinear assembly equations or functions can lead to significant errors when either Worst Limits or Root Sum Squares are applied. A previous paper [1] presented the errors and a corrective design method for Worst Limit elementary tolerance analysis. In this paper, Root Sum Squares tolerance analysis is applied to a nonlinear assembly equation, which gives significant errors in the assembly acceptance fraction. Advanced statistical analysis can be used in an iterative design procedure to specify the independent variables which meet the specified assembly in spite of the nonlinearities.
The Prediction of Two-Phase Turbulence and Phase Distribution Phenomena Using a Reynolds Stress Model
Authors: Lopez de Bertodano M. , Lee S.-J. , Lahey R. T. , Drew D. A.
Published: June 2008

The void fraction distribution for turbulent bubbly air/water upflows and downflows in a pipe was analyzed using a three-dimensional two-fluid model. A τ − ε (i.e., Reynolds stress) turbulence model was used for the continuous (liquid) phase. The τ − ε transport equations yield all components of the Reynolds stress tensor for the liquid phase momentum equations. The effect of these stresses is to create a lateral pressure gradient that acts on the bubbles and effects their distribution. The lateral lift force on the bubbles has also been modelled. This lift force arises due to the relative motion of the bubble with respect to a nonuniform liquid velocity field. It has been observed experimentally that for upflows the bubbles concentrate near the wall while for downflows they move toward the center of the conduit. The model presented herein predicts these trends.
Analysis of Dispersion of Small Spherical Particles in a Random Velocity Field
Authors: Ounis H. , Ahmadi G.
Published: June 2008

The equation of motion of a small spherical rigid particle in a turbulent flow field, including the Stokes drag, the Basset force, and the virtual mass effects, is considered. For an isotropic field, the lift force and the velocity gradient effects are neglected. Using the spectral method, responses of the resulting constant coefficient stochastic integrao-differential equation are studied. Analytical expressions relating the Lagrangian energy spectra of particle velocity to that of the fluid are developed and the results are used to evaluate various response statistics. Variations of the mean-square particle velocity and particle diffusivity with size, density ratio and response time are studied. The theoretical predictions are compared with the digital simulation results and the available data and good agreement is observed.
Analysis of Venturi Performance for Gas-Particle Flows
Authors: Shaffer F. D. , Bajura R. A.
Published: June 2008

In recent years, use of the venturi for measurement of gas-particle flows has received considerable attention. The technology for the venturi as a single-phase flowmeter has matured to the point that application is routine. Much more research, however, is required to establish the venturi as an acceptable gas-particle flowmeter. The first part of this paper consists of a discussion of the basic principles of venturi pressure-flow performance for gas-particle flows. This is followed by a description of the experimental calibration of a venturi for measurement of gas-particle flows with particle-to-gas mass-loading ratios up to 35. Next, a modified Stokes number is presented and shown to improve correlation of venturi pressure-flow data. Finally, the predictions of a model presented by Doss are compared with the pressure-flow data of the venturi calibration performed in this work. The Doss model provides good predictions of venturi differential pressures for particle-to-gas mass-loading ratios less than ten but tends to overpredict the differential pressure, by as much as 45 percent, for particle-to-gas mass-loading ratios above 10.
The Outflow of Buoyant Releases Including Fire Gases From a Long Corridor Closed at One End
Authors: Delichatsios M. A.
Published: June 2008

A new simple model is presented for the outflow of buoyant releases, including fire gases, from a long corridor closed at one end. A physical description of the model and application to well-documented data justify and validate the present model. The analysis incorporates the interaction of gravity (buoyancy) forces, turbulence, and entrainment rates into the plume rising from the fire. The model provides equations for predicting the temperature rise and the velocity in the ceiling layer if one knows the heat release rate from the fire and the air entrainment into the fire plume before the plume is submerged in the ceiling layer. Limited data and analysis indicate that the present flow situation allows a maximum entrainment rate into the fire beyond which the rate of the flow entering the corridor at the open end cannot further increase, i.e., the flow is choked. Although the data analyzed in this paper could not include buoyant outflows produced by fires at the end of a long corridor, the present model can be extended to apply for such flows as it is suggested by a recent Japanese paper [6] and other similar flows [3]. Of course, more experiments using fires in corridors are desirable to validate the present model.
Horizontal Slug Flow: A Comparison of Existing Theories
Authors: Kordyban E.
Published: June 2008

Over the last twenty years a number of papers have appeared in literature concerning the transition to slug flow in horizontal two-phase flow. The theories proposed in these papers are described, and compared to each other and to results of experiments. It is found that most writers accept that the transition is due to Kelvin-Helmholtz instability of the waves, but if this is studied on the basis of wave motion equations, the transition is found to be dependent on wavelength which contradicts experimental data. A number of authors look at this instability by studying the Bernoulli equation, but this does not predict the wave height. Various approaches are taken by the authors to determine this quantity.
Errors Due to Turbidity in Particle Sizing Using Laser-Doppler Anemometry
Authors: Kliafas Y. , Taylor A. M. K. P. , Whitelaw J. H.
Published: June 2008

Flow turbidity, when introduced between the transmitting and receiving optics and the measuring volume of a laser-Doppler anemometer, changes the pedestal amplitude and visibility of the signal. The purpose of this work is to assess the effect on the accuracy of particle sizing, based on measurements of these two quantities, for depths of field of 5 and 10 cm, interrupting particle diameters between 14 to 212 μm in three discrete ranges and void fractions up to 0.1 percent. The turbidity introduces random fluctuations in visibility which increase with void fraction and the resulting rms errors in particle diameter for turbidity introduced on the receiving side of the optics are smaller than 10 percent at void fractions below 0.1 percent. For particles larger than about one third of the beam diameter, the influence of turbidity is largely due to the interruption of the incident beams over the 5 cm nearest to the measuring volume.
Corrosion of Pure Copper in Flowing Seawater Under Cavitating and Noncavitating Flow Conditions
Authors: Wood R. J. K. , Fry S. A.
Published: June 2008

This paper investigates the corrosion of pure copper in flowing seawater under cavitating and non-cavitating flow conditions. Experiments were conducted in a 10 mm × 20 mm working section with a 60 deg symmetrical wedge cavitation source. A copper sidewall specimen was held under potentiostatic control and its average corrosion current was measured under different flow conditions. To facilitate a detailed investigation of the flow field upon the current distribution over the specimen surface, further tests were carried out using a sidewall incorporating 24 mini-electrodes. Apart from some indication of cavity shielding, corrosion currents were little affected by the presence of cavitation during the incubation period (when no material was being removed). However, under similar cavitation conditions (but with material removal under steady-state erosion conditions) the corrosion currents approximately doubled.
A Near-Wall Eddy Viscosity Formula for Turbulent Boundary Layers in Pressure Gradients Suitable for Momentum, Heat, or Mass Transfer
Authors: Granville P. S.
Published: June 2008

An eddy viscosity formula is proposed for turbulent boundary layers in pressure gradients which is compatible with the slope and intercept of the log law. By having a “y3” variation at the wall the formula is suitable for momentum, heat and mass transfer.
Rivulet Formation on an Inclined Cylinder and Its Effects on the Near-Wake
Authors: Xu Y. L. , Zhou Y. , Wang Z. J. , Wang L. Y.
Published: June 2008

Wind rain tunnel experiments were performed in this paper to investigate the formation of water rivulet on the surface of an inclined stationary cylinder immerged in a uniform wind field and the effects of the rivulet on the near-wake of the cylinder. A digital video camera was used to record the formation of water rivulet for a series of cylinder inclination α, cylinder yaw angle β, incident free-stream wind velocity U∞, and water flow rate m. The pictures were then analyzed to find the flow pattern and position of rivulet on the surface of the cylinder. A hot wire anemometer was used to measure wind speed near the cylinder, and a spectral analysis was then performed on the recorded data to investigate the effects of water rivulet on the near-wake of the cylinder. It was found that the formation of water rivulet depends on the parameters m, U∞, α, and β significantly. Water rivulets can be formed on the cylinder surface only in the range of 0° ≤ β ≤ 90° for U∞ = 8 − 15 m/s. Water rivulets seem to locate near flow separation points and move circumferentially. It was also found that fluid dynamics associated with wind-water-structure interaction could be quite different from that without the involvement of water rivulet.
On the Modeling of Rain-Wind Induced Vibrations of a Simple Oscillator
Authors: van der Burgh A. H. P. , Abramian A. K.
Published: June 2008

In this paper two model equations are presented for the study of rain-wind induced vibrations of a simple oscillator. As will be shown the presence of raindrops in a windfield may have an essential influence on the dynamic stability of the oscillator. In the first model equation the influence of the variation of the vibrating mass due to an incoming flow of raindrops hitting the oscillator and a mass flow which is blown and shaken off, is investigated. The time-varying vibrating mass is modeled by a piecewise constant and periodic function. In the second model equation the time-varying vibrating mass is modeled by a time harmonic function whereas simultaneously also time-varying lift and drag forces are considered.
Validation of a Two-Dimensional Numerical Model for Vortex/Blade Interaction
Authors: Lau Y. L. , So R. M. C. , Liu Y. , Leung R. C. K.
Published: June 2008

The numerical method developed previously to analyze two-dimensional vortex-blade interaction problems is validated using recently measured vortex-induced blade vibration data. It assumed a vortex lattice method to calculate the flow field assuming a distribution of sources and discrete vortices on the blade surfaces and a free wake model for the wake flow. A discrete vortex tracking technique in Lagrangian frame is used to track the path of the vortices. The blade is modeled as elastic structures with two-degree-of-freedom in plunging and pitching direction. The fully coupled fluid-structure interaction problem is resolved by means of a time-marching technique. The flow-field is assumed to be inviscid, incompressible and two-dimensional, with no flow separation occurring on the surfaces of the blade. Two cases were examined and they included a blade-vortex interaction and a blade vortex street interaction problem. In the blade-vortex interaction case, the blade is modeled as rigid; therefore, the response of the structure is purely aerodynamics. The calculated variation of the lift coefficient of the blade with the horizontal missed distance of the convected vortex compares well with known experimental results. In the blade vortex street interaction case, the blade is modeled as elastic and is under the unsteady excitation from a Karman vortex street. The calculated blade responses due to vortex-induced vibration are compared with some recently measured vibration characteristics of a flat plate placed behind a cylinder at different separation distance. Good agreement between calculations and measured vibration amplitudes of the plate at its mid-span is obtained, thus indicating that the numerical method gives a viable model for the analysis of the aerodynamics and structural response in vortex/blade interaction problems.
Vibrations of Plates With Clamped and Free Edges Excited by Highly Subsonic Turbulent Boundary Layer Flow
Authors: Hambric Stephen A. , Hwang Yun Fan , Bonness William K.
Published: June 2008

Plate vibrations due to turbulent boundary layer (TBL) excitation can depend strongly on the plate boundary conditions, especially when the flow convects over the plate at speeds much slower than those of the bending waves in the plate. The vibration response of a TBL excited flat rectangular plate is analyzed with two sets of boundary conditions: (A) all four edges clamped, and (B) three edges clamped and one edge free, with the flow direction perpendicular to the free edge. A finite element model with discretization sufficient to resolve the convective wavenumbers in the flow excitation field is used for the study. Three TBL wall pressure excitation models are applied to the plates to represent the cross-spectra of the wall pressures: (1) a modified Corcos model, which includes all wavenumber components of excitation; (2) a low-wavenumber excitation model previously derived by one of the authors, which only models the wavenumber-white region of the modified Corcos model; and (3) an equivalent edge force model which only models the convective component in the modified Corcos model. The TBL wall pressure autospectrum is approximated using the model derived by Smolyakov and Tkachenko. The results obtained from applying models (2) and (3) to the clamped and free edge plates are compared to those generated using model (1). For the completely clamped boundary conditions, the low-wavenumber and Modified Corcos models yield nearly identical vibration spectra, indicating that surface interactions dominate the response of fully clamped plates excited by TBL pressures. For the free edge boundary condition, the vibrations predicted using the equivalent edge force and modified Corcos models match very well, showing that edge interactions between TBL pressures and structural modes dominate the vibrations of plates with free edges excited by TBL flow.
Influence of Electric Fields on Pressure Drop of Liquid Crystal Mixture
Authors: Tsukiji Tetsuhiro , Mitani Tsuyoshi
Published: June 2008

Liquid crystal is one of homogeneous ER (Electrorheological) fluids in some range of temperature. In the present experiment a liquid crystal mixture is used. The responses of the pressure drop are examined when the liquid crystal mixture flows between two parallel-plate electrodes for the constant flow rates. When the voltages are applied on the liquid crystal mixture and removed, the pressure responses of the inlet electrodes are measured with the pressure transducer. At same time, the liquid crystal mixture between the transparent electrodes made of glass is visualized with the video camera investigate the time history of the director of the liquid crystal mixture. The AC voltages are also used to investigate dependence of the liquid crystal mixture on the frequency the voltages. Outlet of the flow channel with two parallel-plate electrodes is atmosphere. Relation between the flow visualization results and the changes of pressure drop investigated especially for transient period. On the other hand, the pulse-wave voltages are added to the electrodes to control the pressure drop using the pulse width modulation or the pulse frequency modulation. In the present study the flow rates change from 0.001cc/sec (velocity is lmm/sec) to 0.003cc/sec and the electric field intensity is from 0.2kV/mm to lkV/mm. The gap of the electrodes is 0.2mm.The isotropic-nematic transition is 90.0°C and smectic-nematic transition is −44.0°C for the liquid crystal mixture. The open-loop test facility the liquid crystal is set in a pyrostat to keep the temperature constant.
Controller Design of Left Ventricle Assist Device
Authors: Wu Yi , Allaire Paul , Adams Milton , Wood Houston , Patel Sonna , Throckmorton Amy
Published: June 2008

A left ventricle assist device (LVAD) is a device composed mainly of a pump and a controller. It is used not only to save lives of patients who suffer from left ventricle failure, but also to help them live like healthy people. Due to the continuing increasing number of left ventricle heart failure cases and limited number of heart donations for heart transplant, the need for LVADs become more and more demanding.
Development of an ECHO-PIV® Technique and Validation in Pipe Flow
Authors: Kim Hyoung-Bum , Hertzberg Jean , Shandas Robin
Published: June 2008

Non invasive echocardiographic techniques have been widely used to provide structural information via imaging of cardiovascular anatomy and functional hemodynamics via measurement of local blood flow velocity. Although the non-invasive nature of the technique is highly attractive, Doppler measurement of blood velocity is still limited due to the inherent angle dependence which requires the ultrasound beam be parallel to the flow direction. This limitation precludes measurement of velocity vectors within the flow field. Such multi-dimensional information would be useful for quantitation of velocity profiles, shear stress, vorticity and flow rate in vivo.
A Study of Arterial Vasodilation as a Means of Modulating Wall Shear Stress
Authors: Kypuros Javier A. , Marrufo Edmundo
Published: June 2008

Diseases of the heart continue to be the number 1 killer of Americans. In 2001, cardiovascular disease and stroke cost the United States an estimated $298.2 billion [American Heart Association]. Heart disease and related vascular disorders remain focus areas during this decade for the National Institutes of Health (NIH) as reported in Healthy People 2010.
Flow and Compression in Asymmetric Stenosis Models: Influence of Compliance on Flow and Compression
Authors: Kobayashi Shunichi , Tsunoda Daisuke , Morikawa Hirohisa , Tang Dalin , Ku David N.
Published: June 2008

Blood flow through the constricted area of a severe stenosis is similar to that through a venturi or flow nozzle. In the contraction section, the blood can accelerate to high speed. In this situation, the external pressure may be greater than the internal fluid pressure, and the artery could collapse. This collapse may be important in the development of atherosclerotic plaque fracture and subsequent thrombosis or distal embolization [1]. We have developed an asymmetric experimental model that closely approximates the arterial disease situation and performed steady and pulsatile flow experiments. The characteristics of flow and compression concerned with the geometry of the model were discussed [2, 3]. This paper was to examine the influence of compliance on flow and compression under steady and pulsatile flow.