bluuebunny/crossref_metadata_2025 huggingface dataset:
Solution‐Focused Brief Therapy With People With Mild Intellectual Disabilities: A Case Series
Authors: Roeden John M. , Maaskant Marian A. , Bannink Fredrike P. , Curfs Leopold M. G.
Published: December 2011

Solution‐focused brief therapy (SFBT) is a form of behavior therapy that focuses on evoking desired behavior rather than on the existing problem behavior. To illustrate the use of this form of therapy, the authors undertook a study of 10 case studies of applications of SFBT with people with a mild intellectual disability (MID). For all 10 cases, before SFBT, after SFBT, and during a follow‐up after 6 weeks, the following measurements were taken: assessment of quality of life and assessment of maladaptive behavior as well as goal attainment according to people with MID and according to carers. It was found that SFBT treatments contributed to improvements in psychological functioning and decreases in maladaptive behavior. In addition, achievement of goal attainments were noted according to both people with MID and their carers. The positive changes evident after SFBT proved sustainable during follow‐up. Treatment strategies and therapeutic alliances employed were usually assessed as positive by the participants. Although the study had limitations due to the lack of a control group and the small number of cases, the fact that several case studies showed positive treatments results did indicate the effectiveness of SFBT for people with MID.
Adults With Intellectual Disabilities Living in Hong Kong's Residential Care Facilities: A Descriptive Analysis of Health and Disease Patterns by Sex, Age, and Presence of Down Syndrome
Authors: Wong Chi Wai
Published: December 2011

The aim of this study was to describe the health status profile and identify the healthcare needs of adults with intellectual disability (ID) residing in 18 of Hong Kong's residential care facilities. The author employed a cross‐sectional study using a structured questionnaire survey to collect data on 811 persons with ID (432 males, 53.3%, and 379 females, 46.7%) with an average age of 44. Of the residents, 107 (13.2%) had Down syndrome, 275 (34%) had epilepsy, and 134 (16.6%) had cerebral palsy. Some 25.4% were underweight and 27.3% were overweight. They had the same illnesses as the general population, but the relative frequencies were different. In terms of prevalence, the top five chronic conditions were epilepsy, hypertension, diabetes mellitus, cataract, and gout (compared to Hong Kong's general population, where the top five conditions were hypertension, diabetes mellitus, cataract, heart disease, and respiratory disease). Compared to the general population, the prevalence of epilepsy, dementia, and gout among the adults was higher and there was an earlier onset of dementia. Also noted was an increasing rate of common chronic diseases in the age group 40+. Adults with Down syndrome showed higher prevalence of cataract, gout, heart disease, thyroid disease, hemorrhoids, dementia, hypercholesterolemia, psoriasis, varicose veins, fatty liver, cirrhosis, sleep apnea, as well as prostatic hypertrophy. The author concludes that there is lack of information about healthcare service for people with ID in Hong Kong, and that the study findings should have implications for policy development in the area of healthcare services for people with ID.
Pediatric migraine teaching for families
Authors: Craddock Lindsay , Ray Lynne D.
Published: December 2011

Purpose.  Child and family education regarding management of pediatric migraine is essential to reduce acute pain, prevent chronic daily migraine, and minimize the total number of headache attacks. This paper summarizes current evidence and provides a foundation for family teaching.

Conclusions.  Effective management of pediatric migraine can be achieved with a combination of individually tailored biobehavioral strategies, lifestyle modifications, and optimal scheduling of rescue and preventative pharmacologic treatment.

Practice Implications.  Included are goal setting recommendations, common triggers, key comorbidities, lifestyle modifications, principles of pharmacologic management, commonly used naturopathic compounds, and a link to an online downloadable teaching handout.
Dialogue social et gouvernance de la sécurité sociale: un thème d'actualité pour l'OIT
Authors: Ghellab Youcef , Varela Nancy , Woodall John
Published: December 2011

De tous les sujets intéressant le monde du travail, aucun ne reflète peut‐être mieux les principes du tripartisme et du dialogue social que la sécurité sociale. On est donc naturellement fondéà se demander si ces instruments essentiels de bonne gouvernance ont été, et sont toujours, employés efficacement pour surmonter les sérieux défis auxquels de nombreux régimes de sécurité sociale sont actuellement confrontés. La réforme de la sécurité sociale, notamment en ce qui concerne les prestations de retraite, a figuré en bonne place durant ces dernières décennies parmi les priorités de nombreux pays, reflétant ainsi l'impact de facteurs tels que la mondialisation et le vieillissement démographique. De nouveaux thèmes se sont récemment immiscés dans le débat, suite à la crise financière et économique mondiale. Le Bureau international du Travail (BIT) s'est efforcé d'analyser et de comprendre ces questions; tant avant qu'après la crise économique, les départements du Dialogue social et de la Sécurité sociale ont entrepris conjointement des études, dont les résultats sont mitigés. La valeur et la pertinence du dialogue social ont été confortées dans plusieurs pays où cette tradition est fortement ancrée et donne des résultats positifs. Malheureusement, confrontés à de graves tensions économiques et soumis aux fortes pressions des institutions financières internationales (IFI) et d'autres organismes, d'autres gouvernements ont agi unilatéralement, parfois sans prendre la mesure de leurs responsabilités constitutionnelles. Les auteurs concluent qu'il est à la fois nécessaire et possible de réexaminer cette problématique, et de réactiver l'engagement et la volonté politiques nécessaires à l'instauration d'un dialogue social tripartite, afin de résoudre les questions politiques, souvent complexes et lourdes de conséquences, qui se posent en matière de sécurité sociale.
Attitude des employeurs à l'égard du respect des obligations en matière d'assurance sociale à Shanghai, en Chine
Authors: Nyland Chris , Thomson S. Bruce , Zhu Cherrie J.
Published: December 2011

La gestion du respect des obligations en matière d'assurance sociale représente un problème de gouvernance particulièrement important dans les pays émergents dont les régimes de réglementation souffrent de lacunes. En s'appuyant sur des données qualitatives issues de huit études de cas menées à Shanghai, en République populaire de Chine, le présent article analyse de façon approfondie la manière dont les employeurs répondent aux tentatives de l'Etat de gérer leurs comportements envers l'assurance sociale. Le sentiment des employeurs et leurs réactions aux politiques en place et aux structures de réglementation traduisent cinq préoccupations principales: l'élaboration d'une politique efficace, une réglementation équitable, le contrôle des coûts, la réputation de leur entreprise et le recrutement et la fidélisation de leur personnel. Ces données indiquent également que trois éléments inhérents aux entreprises peuvent exercer une incidence sur le respect des obligations: les facteurs de risque, les compétences de leur personnel et leur type de propriété. Il avait été supposé que la taille de l'entreprise pouvait également influer sur le respect des obligations en matière d'assurance sociale, mais les données n'ont rien révélé de patent en ce sens.
Vision impairment during cardiac surgery and extracorporeal circulation: current understanding and the need for further investigation
Authors: Nenekidis Ioannis , Pournaras Constantin J. , Tsironi Evangelia , Tsilimingas Nikolaos
Published: December 2011

The aim of this article was to provide a comprehensive review of current knowledge regarding ocular hemodynamic alterations affecting the retinal neuroglial cells and optic nerve head (ONH) function during cardiac surgery. Literature indicates that visual loss after heart surgery is a rare but devastating complication provoked by two main causes of optic ischaemia and infarction during on‐pump cardiac procedures: microembolism and/or hypoperfusion. Retinal ischaemia and ischaemic optic neuropathy are two possible major consequences of extracorporeal circulation in cardiac surgery. The hemodynamic modifications within the vascular beds of retina and ONH during cardiovascular operations have been incompletely studied. Consequently, it is of great interest to investigate the hemodynamic changes during cardiopulmonary bypass within the choroidal, retinal and optic nerve microcirculations as well as other potential causes of vaso‐occlusion. Maintaining stable hemodynamic parameters during cardiovascular surgery seems to be the key to prevent visual impairment.
The Role of Socioeconomic Status and Control Beliefs on Frequency of Exercise During and After Cardiac Rehabilitation
Authors: Murray Terra , Rodgers Wendy
Published: December 2011

Background: Exercise is considered a key component of rehabilitation for heart patients, yet adherence to exercise remains problematic. This study examined the role of socioeconomic status, patients' perception of control over their heart problem and self‐efficacy beliefs on exercise during and after cardiac rehabilitation. Methods: A prospective design was used. Measures were assessed prior to beginning rehabilitation, at the end of rehabilitation, and 1 month post rehabilitation. Results: There were 107 participants (Mean age = 59 years; 85% men) enrolled in the rehabilitation program who completed the study. Regression analysis showed that initial exercise capacity and patients' perception of control over their heart problem prior to starting rehabilitation predicted exercise during the rehabilitation period. Patients scheduling self‐efficacy beliefs at the end of the rehabilitation was the key predictor of exercise 1 month post rehabilitation. Conclusions: Findings support the role of multiple kinds of control beliefs, including conceptualising self‐efficacy in terms of multiple dimensions. Further, there may be different motivational influences on exercise performed during rehabilitation than exercise performed after rehabilitation.
Predictive factors for cholangiocarcinoma associated with hepatolithiasis determined on the basis of Japanese Multicenter study
Authors: Suzuki Yutaka , Mori Toshiyuki , Abe Nobutsugu , Sugiyama Masanori , Atomi Yutaka
Published: December 2011

Aim:  The aim of this study was to delineate predictive factors for cholangiocarcinoma in patients with hepatolithiasis, and to establish optimal management for hepatolithiasis from the viewpoint of carcinogenesis on the basis of a Japanese nationwide survey for hepatolithiasis.

Methods:  The Hepatolithiasis Research Group was organized in 2006 by the Ministry of Health, Labour and Welfare of Japan, and conducted a nationwide survey. The research group collected data on 336 cases of hepatolithiasis in 2006, in a cross‐sectional survey involving 2592 institutions in Japan. Predictive factors for cholangiocarcinoma associated with hepatolithiasis were analyzed by univariate and multivariate analyses of clinicopathological and therapeutic factors.

Results:  Twenty‐three patients had cholangiocarcinoma. Histories of choledocoenterostomy and liver atrophy were found to be significantly predictive factors by multivariate analysis. In 87.5% of cases of cholangiocarcinoma with liver atrophy, cholangiocarcinoma was located in the atrophic lobes. The method of reconstruction did not affect the incidence of cholangiocarcinoma (choledochojejunostomy vs. choledochoduodenostomy; side‐to‐end vs. side‐to‐side anastomosis).

Conclusions:  Choledocoenterostomy and liver atrophy may increase the risk of developing cholangiocarcinoma. Choledocoenterostomy is thus contraindicated in patients with hepatolithiasis. An aggressive resection strategy is recommended for an atrophic segment.
Possible widespread presence of hepatitis A virus subgenotype IIIA in Japan: Recent trend of hepatitis A causing acute liver failure
Authors: Miyamura Tatsuo , Ishii Koji , Kanda Tatsuo , Tawada Akinobu , Sekimoto Tadashi , Wu Shuang , Nakamoto Shingo , Arai Makoto , Fujiwara Keiichi , Imazeki Fumio , Kiyohara Tomoko , Wakita Takaji , Yokosuka Osamu
Published: December 2011

Aim:  Recently, the number of acute hepatitis A cases has decreased in Japan. However, six patients with acute liver failure caused by hepatitis A virus (HAV) have been admitted to Chiba University Hospital, Japan, in the last 18 months, between 2010 and June 2011. The aim of this study is to characterize the recent HAV genotypes from an urban hospital in Japan and to compare the clinical differences.

Methods:  Hepatitis A virus RNA was detected by strand‐specific reverse transcription. Then, HAV VP1/2A regions were amplified by nested polymerase chain reaction (PCR). Sequences were directly determined and phylogenetic trees were constructed for determining HAV subgenotypes.

Results:  Analysis of these HAV genomes revealed that 4 and 2 belonged to subgenotypes IA and IIIA, respectively.

Conclusions:  Fujiwara et al. reported a frequency of HAV subgenotype IIIA of only 2.1% in Japan. We conclude that HAV subgenotype IIIA might be widespread in our country.
Can non‐invasive assessment of liver fibrosis replace liver biopsy?
Authors: Yoshioka Kentaro , Hashimoto Senju
Published: December 2011

Transient elastgraphy, acoustic radiation force impulse and real‐time elastography are the methods with very good or excellent diagnostic accuracy for the assessment of liver fibrosis stage. They do not provide the information on inflammatory activity, steatosis, iron deposition or other findings derived from liver biopsy. Even on account of fibrosis stage, these non‐invasive methods do not give us the estimation completely corresponding to that of liver biopsy. However they provide us useful clinical information that liver biopsy has been providing us, such as appropriate time to start antiviral therapy, prediction of response to antiviral therapy, evaluation of effects of antiviral therapy, assessment of natural course of hepatitis and estimation of prognosis of hepatitis. Recently non‐invasive methods for assessment of inflammatory activity, steatosis and iron deposition in the liver have been developed. Thus in the near future, non‐invasive methods will replace liver biopsy.
Hepatic arterial infusion chemotherapy for advanced hepatocellular carcinoma and future treatments for the poor responders
Authors: Yamasaki Takahiro , Sakaida Isao
Published: December 2011

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide. The most common problem associated with HCC is a high risk of intrahepatic recurrence despite radical treatment, and in many patients, this recurrence has fatal consequences. For patients with advanced‐stage HCC according to the Barcelona Clinic Liver Cancer staging system, the multikinase inhibitor sorafenib is the current standard of care. In contrast, hepatic arterial infusion chemotherapy (HAIC) is the recommended treatment in Japan for patients with intermediate‐stage or advanced‐stage HCC. In this review, we describe the use of HAIC for advanced HCC. Furthermore, we demonstrate an alternative therapy for HCC, the iron chelator deferoxamine, and discuss future therapeutic possibilities.
Prevalence of Patent Foramen Ovale with Right‐to‐Left Shunting in Dogs with Pulmonic Stenosis
Authors: Fujii Y. , Nishimoto Y. , Sunahara H. , Takano H. , Aoki T.
Published: December 2011

Background

Right‐to‐left (R‐L) shunt caused by patent foramen ovale (PFO) concurrent with pulmonic stenosis (PS) is considered common, although there is a lack of published evidence.

Objectives

To investigate the prevalence of R‐L shunt caused by a PFO in dogs with PS.

Animals

Thirty‐one client‐owned dogs with PS, without obvious extracardiac disease detected on the clinical examinations.

Methods

Case control study: R‐L shunt probably caused by PFO was diagnosed when IV injected microbubbles appeared at the left atrial level with an intact atrial septum on echocardiography (bubble‐positive dogs). The severity of PS concurrent tricuspid regurgitation (TR), relative thickness of the right ventricle, and relative right atrial area were compared between bubble‐positive and bubble‐negative dogs.

Results

The prevalence of R‐L shunts caused by PFO was 39% (12 of 31 cases). The instantaneous pressure gradient (PG) across the pulmonic valve and relative thickness of the right ventricle were significantly increased in bubble‐positive compared with those in bubble‐negative dogs. None of the dogs with mild or moderate PS (pressure gradient < 80 mm Hg, n = 2) demonstrated R‐L shunt. The prevalence of TR in bubble‐positive dogs was significantly higher than that in bubble‐negative dogs.

Discussion and Clinical Relevance

Patent foramen ovale PFO with R‐L shunt was more common in dogs with very severe PS and absent in dogs with mild PS.
Flow‐Mediated Vasodilation Measurements inCavalierKingCharlesSpaniels with Increasing Severity of Myxomatous Mitral Valve Disease
Authors: Moesgaard S.G. , Klostergaard C. , Zois N.E. , Teerlink T. , Molin M. , Falk T. , Rasmussen C.E. , Luis Fuentes V. , Jones I.D. , Olsen L.H.
Published: December 2011

Background

Cardiovascular disease is associated with endothelial dysfunction in humans and studies of plasma biomarkers suggest that dogs with myxomatous mitral valve disease (MMVD) might also have endothelial dysfunction.

Hypothesis

That progression of mitral regurgitation (MR) is associated with development of endothelial dysfunction.

Animals

Forty‐threeCavalierKingCharlesSpaniels (CKCS) withMRof varying severity.

Methods

Privately ownedCKCSwere prospectively recruited and divided in 4 groups: (1) 12CKCSwith minimalMR; (2) 9CKCSwith mildMR; (3) 11CKCSwith moderate‐severeMR; and (4) 11CKCSwith moderate‐severeMRand clinical signs compatible with heart failure. Dogs underwent blood sampling, echocardiography, blood pressure (BP) recordings, and flow‐mediated vasodilation (FMD) measurements. The effect of progressiveMRonFMDwas determined by multivariate analyses.

Results

Flow‐mediated vasodilation decreased with progression ofMR. Group 4 (4.79 ± 3.22%) had significantly lowerFMDthan groups 1 (10.40 ± 4.58%) and 2 (10.14 ± 3.67%) (P < .005) and group 3 (6.79 ± 3.98%) had a significantly lowerFMDthan group 1 (P = .03). Increasing left ventricular end‐diastolic diameter (P = .0004, R2 = 0.27) and the combination of age (P = .01) and body weight (P = .002) (R2 = 0.31) were significantly associated with reducedFMD.FMDdid not correlate with sex,BP, or plasma markers.

Conclusions and Clinical Importance

ReducedFMDindicates that increased disease severity inCKCSwithMMVDis associated with development of endothelial dysfunction which might be a future therapeutic and/or diagnostic target.
Coronary patients who returned to work had stronger internal locus of control beliefs than those who did not return to work
Authors: Bergvik Svein , Sørlie Tore , Wynn Rolf
Published: December 2011

Objectives. Return To Work (RTW) is an important indicator of recovery from coronary artery disease (CAD), associated with social and economical benefits, and improved quality of life. Percutaneous coronary intervention (PCI) and coronary artery bypass graft (CABG) surgery are effective procedures relieving symptoms and reducing the risk for new events, but psychosocial problems are frequent among these patients. The aim was to determine psychosocial and treatment‐related factors associated with RTW among PCI and CABG patients in Northern Norway.

Design. Cross‐sectional design based on questionnaire data from CABG and PCI patients 3–15 months following discharge, and from hospital records.

Methods. Of the 348 responding patients, 168 were younger than 67 years and working prior to hospitalization. Factors associated with RTW were examined in a logistic regression analysis.

Results. A total of 108 (64%) had RTW within 3–15 months. Four factors made unique significant contributions to the model, including higher education, time since hospital discharge and Internal Locus of Control (LoC) of the Multidimensional Health Locus of Control Scale (MHLC) as positively associated factors, and Powerful Others LoC as a negatively associated factor. Analyses controlled for data on demographics, emergency status, type of treatment, number of days at the hospital, physical exercise, attending a rehabilitation program, mental distress, Type D personality, and for the CABG patients additional data on coronary health.

Conclusions. Patients’ control beliefs and educational level are significant psychosocial factors associated with RTW following PCI and CABG treatment. Implications for hospital treatment and rehabilitation programs are discussed.
Efficacy of US paediatric obesity primary care guidelines: two randomized trials
Authors: Raynor H. A. , Osterholt K. M. , Hart C. N. , Jelalian E. , Vivier P. , Wing R. R.
Published: December 2011

Objective

The objective of this study was to examine the efficacy of US primary care paediatric obesity treatment recommendations, within two randomized trials.

Methods

Between November 2005 to September 2007, 182 families (children aged 4–9 years, body mass index [BMI] ≥85th percentile) were recruited for two separate trials and randomized within trial to a 6‐month intervention. Each trial had one intervention that increased child growth‐monitoring frequency and feedback to families (GROWTH MONITORING). Each trial also had two interventions, combining GROWTH MONITORING with an eight‐session, behavioural, parent‐only intervention targeting two energy‐balance behaviours (Trial 1: reducing snack foods and sugar‐sweetened beverages [DECREASE], and increasing fruits, vegetables and low‐fat dairy [INCREASE]; Trial 2: decreasing sugar‐sweetened beverages and increasing physical activity [TRADITIONAL] and increasing low‐fat milk consumption and reducing television watching [SUBSTITUTES]). Child standardized BMI (ZBMI) and energy intake were assessed at 0, 6 and 12 months.

Results

In both trials, main effects of time were found for ZBMI, which decreased at 6 and 12 months (P < 0.01). In Trial 1, ZBMI reduced from 0 to 6 months, which was maintained from 6 to 12 months (ΔZBMI 0 to 12 months = −0.12 ± 0.22). In Trial 2, ZBMI reduced from 0 to 6 and from 6 to 12 months (ΔZBMI 0–12 months = −0.16 ± 0.31). For energy intake, main effects of time were found in both trials and intake reduced from 0 to 6 months (P < 0.05), with Trial 1 reducing intake from 0 to 12 months (P < 0.05).

Conclusions

All interventions improved weight status. Future research should examine effectiveness and translatability of these approaches into primary care settings.
Characteristics of Fluidelastic Instability of Tube Rows in Crossflow
Authors: Chen S. S. , Jendrzejczyk J. A.
Published: December 2011

An experimental study is reported that investigated the jump phenomenon in critical flow velocities for tube rows with different pitch-to-diameter ratios, and the excited and intrinsic instabilities for a tube row with a pitch-to-diameter ratio of 1.75. The experimental data provide additional insights into the instability phenomena of tube arrays in crossflow.
A Total Strain Energy Density Theory for Cumulative Fatigue Damage
Authors: Golos K. , Ellyin F.
Published: December 2011

A unified theory based on the cyclic strain energy density criterion is presented first. It is shown that the fatigue failure in both low and high-cycle regimes, and cumulative damage and loading sequence, can all be expressed in terms of a single damage parameter. The damage criterion is based on the total strain energy density per cycle (sum of the plastic and tensile elastic strain energy). Both the crack initiation and propagation phases of the fatigue life are embodied in this approach. A systematic investigation into the cyclic, fatigue and cumulative damage behavior of the pressure vessel steel, A-516 Gr. 70, is subsequently presented. The comparison between the predicted and experimental results is found to be good.
Overview of Numerical Methods for Predicting Flow-Induced Vibration
Authors: Axisa F. , Antunes J. , Villard B.
Published: December 2011

A predictive analysis of an heat-exchanger design against severe vibration and wear has to cope with experimental data on flow-induced vibration and fretting wear, together with the use of analytical and numerical methods for predicting linear and nonlinear tube response. This paper describes a general approach of the problem currently under development at C.E.A. Attention is especially paid to some key aspects of the numerical techniques, namely, the modelization of flow-induced forcing functions and the modelization of impact and sliding at tube-support gaps. These topics are exemplified by numerical results related to some typical situations including the case of random vibration induced by flow turbulence and fluidelastic vibration.
Statistical Forecasting of Trends in Tubular Pressure Part Forced Outage Rates for Fossil Boilers
Authors: Gallucci R. H. V. , Moelling D. S. , Talbot K. P.
Published: December 2011

Statistical models for calculating age-dependent component failure rates and system unavailabilities have been combined into a flexible procedure to forecast trends in tubular pressure part forced outage rates for fossil boilers as a function of their ages. These models have been computerized, and the forecasting procedure has been applied to predicting trends at six fossil units of a specific utility. The analytic procedure is described, and its application to the example study is discussed.
Numerical Evaluation of Two Creep-Fatigue Damage Models Under Complex Loading Histories and Multiaxial States of Stress
Authors: Bertini L. , Vitale E.
Published: December 2011

The work is focused on the modeling of creep-fatigue behavior in austenitic stainless steels in the presence of complex loading histories and multiaxial states of stress. Two interaction models, namely “Continuous Damage Model” and “Damage Rate Approach,” have been applied to predict experimental results of time-variable loading and multiaxial tests. Related application difficulties and prediction accuracy are discussed. Life predictions were obtained from computer programs written to perform numerical calculations. Material parameters were derived from over 1500 uniaxial tests conducted on AISI 304 and 316 austenitic stainless steel specimens.
Computer-Aided Analysis and Experimental Verification of a Motorcycle Suspension
Authors: van Vliet M. , Sankar S.
Published: December 2011

A computer-aided analysis and experimental verification of a motorcycle suspension are presented. A mathematical model describing the flow characteristics in a front fork and a rear shock absorber was independently developed for both compression and extension strokes. The model includes both laminar and turbulent flow conditions and the spring effect due to entrapped air in front fork and gas charged chamber in the case of rear shock absorber. A sinusoidal displacement was considered as the input excitation for the model. A digital simulation in the case of front fork and an analog simulation for rear shock absorber were used to obtain force-displacement (F-D) Lissajous diagrams for each input amplitude-frequency combination. An experimental setup consisting of an electro-hydraulic shaker was used to test the performance characteristics of the front fork and rear shock absorber. The comparison between simulated and experimentally obtained results is presented and discussed.
Response of Two Nuclear Power Plant Valves to Dynamic Excitation
Authors: Masri S. F. , Stott S. J. , Reiff D. D.
Published: December 2011

To formulate more suitable testing criteria for safety-related equipment in nuclear power plants, new investigations of equipment behavior under dynamic loading are required. Currently used guidelines and their applicability are summarized and several major problems to be solved by new investigations are described. Experimental and analytical studies conducted on two typical valves exemplify the type of investigation required. A 4-in. and 6-in. globe valve were investigated to determine characteristic structural dynamic-response relationships among various magnitudes of swept-sine, sine-dwell, random, and shock excitation. Different directions of acceleration were applied to each type of excitation. Finite element models of the valves were used to determine the dominant eigenvalues and eigenvectors. The experimental measurements were analyzed by the introduction of suitable dimensionless response parameters and appropriate excitation intensity measures that clearly indicate the presence of nonlinear response phenomena. Some guidelines are given for the qualifications testing of similar equipment and some areas of concern are pointed out.
Fluidelastic Instability of an Infinite Double Row of Circular Cylinders Subject to a Uniform Cross-Flow
Authors: Price S. J. , Paidoussis M. P.
Published: December 2011

This paper represents the first stage of a fundamental investigation of the vibration phenomena induced in heat exchanger bundles subject to a cross-flow. Using aerodynamic force coefficient data, obtained experimentally from a static wind tunnel model, a linearized quasi-static analysis is employed to analyze the stability of an infinite double row of circular cylinders in uniform cross-flow. From the analysis it is shown that the instability is a result of the negative fluid damping forces, resulting from the complex flow pattern in the row. A new expression is obtained relating the critical velocity for the onset of instability to the damping parameter, the mass parameter and the pitch ratio of the cylinders. The expression is compared with experimental data available in the literature, from dynamic laboratory results, and a good correlation is obtained. Using this stability analysis the effect of mechanical coupling and frequency detuning, both between modes in one cylinder and modes in adjacent cylinders, is examined. In general it is shown that mechanical coupling is destabilizing and frequency detuning stabilizing.
Experimental Studies of Damping and Hydrodynamic Mass of a Cylinder in Confined Two-Phase Flow
Authors: Carlucci L. N. , Brown J. D.
Published: December 2011

This paper presents the results of experiments done to determine the effects of cylinder mass and flow regime on the damping and hydrodynamic mass characteristics of a cylinder vibrating in simulated two-phase air-water flows. It was found that two-phase damping varied in inverse proportion to the combined cylinder and two-phase hydrodynamic masses. This is in agreement with a postulated detuning process for damping in two-phase flow. As in earlier studies, the two-phase hydrodynamic mass was found to be less than that calculated from the mixture density, for all flow conditions.
Strategies for Improved Nuclear Plant Reliability
Authors: Thomas J. M. , Bosinoff P. R.
Published: December 2011

This paper presents a methodology for identifying cost-effective failure prevention strategies for components or systems in nuclear power plants. Two strategies identified are the improvement of component reliability and the addition of redundant components. These two strategies are evaluated within the context of both repairable and nonrepairable systems. Capacity/demand and continuous time models are used to analyze the two strategies and systems. An example problem is developed for a continuous time, repairable system. It is clearly shown that large expenditures are justified to improve the reliability of some major systems in nuclear power plants and that these expenditures, exceeding the original capital cost of the system, could save tens of millions of dollars.
Inertia Stresses in a Rotating Multisided Box or Tube
Authors: Holland M.
Published: December 2011

General formulas are developed for the prediction of the components of inertia loading acting on a solid, thin, rectangular section rotating with constant angular velocity about a center which is remote from the boundaries of the rectangle. The components of loading so determined are then used to determine the stress in a multisided member which rotates about a longitudinal axis passing through the center of the cross section. The range of application, minimum number of sides for closure (equilateral triangle) to infinite number of sides (circle), is covered by the analysis and when the number of sides approaches infinity the general equations are seen to produce solutions consistent with the standard forms for circumferential stress and radial displacement in a rotating thin circular member.
Fail-Safe Vibration Control Using Active Force Generators
Authors: Guntur R. R. , Sankar S.
Published: December 2011

Using the concept of force generators, various active vibration configurations have been examined for their performance potential. It is shown that an active vibration control system offers a great deal of flexibility in that by a proper choice of active components its transmissibility characteristics can be altered to suit the requirements. It is also shown how the full potential of active systems can be achieved even when there are passive components. An active system is designed in such a way that it gives the desired performance even in the event of the failure of the active components through the reliability offered by a passive system.
Protection of Continuous Structures Against Vibrations by Active Damping
Authors: Luzzato E. , Jean M.
Published: December 2011

In this paper, we deal with the problem of active damping of vibrations of a continuous viscoelastic structure, and a general method of computation of the control system is developed. We define a mechanical model for this structure, the sources of perturbing vibrations, the control system, and different absorption criteria. The problem is set in an infinite dimension space, and an approximation problem is derived in n dimension spaces. Two methods of resolution are proposed for this approximation problem, and the solutions are compared. An example is given for the case of flexural vibrations in beams. Numerical results simulating the behavior of flexural vibrations in a rectangular plate, which is simply supported along the whole boundary, are presented for three different absorption criteria, thus permitting a quick evaluation of the comparative effectiveness of the chosen criteria.
Comparison of Equivalent Viscous Damping and Nonlinear Damping in Discrete and Continuous Vibrating Systems
Authors: Bandstra J. P.
Published: December 2011

The study of nonlinear damping in vibrations is motivated by the desire to represent and predict real responses more accurately than allowed by the limitations of linear analysis, since observed phenomena are, in general, actually nonlinear in nature. The scope of this paper is to compare the normal engineering methods of including the effects of nonlinear damping to more exact methods of solution so that the range of applicability of the normal methods may be known and the limitations of linear analysis more fully understood.
Wave Transmission and Energy Dissipation at Structural and Machine Joints
Authors: Gaul L.
Published: December 2011

The dynamics of composed structures is influenced by the transfer behavior of interfaces of bolted, riveted, and compression joints. The measured nonlinear behavior of such joints is represented by equivalent linearized models and coupled with models of the members. Excitations by incident flexural waves, as well as longitudinal waves, are discussed. Characteristics of wave transmission, wave reflection, and energy dissipation of jointed beams are calculated. The influence of different models of joints is compared. A test setup for experimental vertification is proposed.
Modal Analysis and Error Estimates for Linearized Finite Journal Bearings
Authors: Hashish E. , Sankar T. S.
Published: December 2011

The linearized model of a rigid symmetric rotor with finite bearings is solved using modal analysis. Important parameters of the finite bearing system are evaluated and these include the logarithmic decrement, damped natural frequencies, complex frequency response functions, and inclination angles of the orbits with the load direction. A chart of error measures giving the deviation of the linearized bearing stiffness and damping from those of the actual nonlinear system is provided. This chart can assist in obtaining a knowledge of the quality of a rotor response as calculated using linearized stiffness and damping and can be used to set acceptance boundaries for the linear model in different industrial applications because of the mathematical difficulties involved in a complete solution of the actual nonlinear representation of the rotor bearing system.
Identification of Modal Parameters of an Elastic Rotor With Oil Film Bearings
Authors: Nordmann Rainer
Published: December 2011

Investigations of the dynamic behavior of structures have become increasingly important in the design process of mechanical systems. To have a better understanding of the dynamic behavior of a structure, the knowledge of the modal parameters is very important. The powerful method of experimental modal analysis has been used to measure modal parameters in many mechanical engineering problems. But the method was mainly applied to nonrotating structures. This presentation shows improvements of the classical modal analysis for a successful application in rotating machinery with nonconservative effects. An example is given, investigating the modal parameters of an elastic rotor with oil film bearings.
Theory and Guidelines to Proper Coupling Design for Rotor Dynamics Considerations
Authors: Kirk R. G. , Mondy R. E. , Murphy R. C.
Published: December 2011

The use of couplings for high-speed turbocompressors or pumps is essential to transmit power from the driver. Typical couplings are either of the lubricated gear or dry diaphragm type design. Gear couplings have been the standard design for many years and recent advances in power and speed requirements have pushed the standard design criteria to the limit. Recent test stand and field data on continuous lube gear type couplings have forced a closer examination of design tolerances and concepts to avoid operational instabilities. Two types of mechanical instabilities are reviewed in this paper: (1) entrapped fluid, and (2) gear mesh instability resulting in spacer throw-out onset. Test and results of these types of instabilities and other directly related problems are presented together with criteria for proper coupling design to avoid these conditions. An additional test case discussed shows the importance of proper material selection and processing and what can happen to an otherwise good design.
The Reduction of Bias Error in Transfer Function Estimates Using FFT-Based Analyzers
Authors: Cawley P.
Published: December 2011

The susceptibility to bias error of two methods for computing transfer (frequency response) functions from spectra produced by FFT-based analyzers using random excitation has been investigated. Results from tests with an FFT analyzer on a single degree-of-freedom system set up on an analogue computer show good agreement with the theoretical predictions. It has been shown that, around resonance, the bias error in the transfer function estimate H2 (Syy/Sxy*) is considerably less than that in the more commonly used estimate, H1 (Sxy/Sxx). The record length, and hence the testing time, required for a given accuracy is reduced by over 50 percent if the H2 calculation procedure is used. The analysis has also shown that if shaker excitation is used on lightly damped structures with low modal mass, it is important to minimize the mass of the force gage and the moving element of the shaker.
Probabilistic Design and Analysis of Foundation Forces for a Class of Unbalanced Rotating Machines
Authors: Boyce L. , Kozik T. J. , Parzen E.
Published: December 2011

Rotors of rotating machinery inherently have mass eccentricities that transfer forces to the bearings, housing, and foundation of the machine. This paper considers, from a probabilistic viewpoint, ways to determine the foundation forces and their probabilities. A rotor-housing system is modeled with three degrees-of-freedom, a translation in the direction of the machine supports, a roll, and a pitch. Equations are presented for the motion of the model and the expression for maximum foundation force is developed. All parameters are constant except for rotor mass eccentricity, which is introduced into the problem as a random variable. The probabilistic analysis includes the calculation of the mean value of the foundation force and some measure for its error or variance. An approximate calculation for variance yields values too large for meaningful interpretation. However, a simulation method using a sufficient number of individual rotors leads to a quantile function that displays the variability of the foundation force data in useful form, and allows determination of foundation force probabilities. A numerical example illustrates how the equations can be applied to a sample taken from a population of mass-produced rotors.
Vibrations of Twisted Rotating Blades
Authors: Leissa A. W. , Lee J. K. , Wang A. J.
Published: December 2011

The literature dealing with vibrations of turbomachinery blades is voluminous, but the vast majority of it treats the blades as beams. In a previous paper a two-dimensional analytical procedure was developed and demonstrated on simple models of blades having camber. The procedure utilizes shallow shell theory along with the classical Ritz method for solving the vibration problem. Displacement functions are taken as algebraic polynomials. In the present paper the method is demonstrated on blade models having camber. Comparisons are first made with results in the literature for nonrotating twisted plates and various disagreements between results are pointed out. A method for depicting mode shape information is demonstrated, permitting one to examine all three components of displacement. Finally, the analytical procedure is demonstrated on rotating twisted blade modes, both without and with camber.
Control of Rapid Transit Propulsion System Noise
Authors: Remington P. J. , Dixon N. R.
Published: December 2011

An extensive series of diagnostic measurements was carried out on an urban rail propulsion system of the type that was found to have the greatest community noise impact. At high speed, 3000 to 4000 rpm, the fan dominates all other sources by 10–15 dBA. At low speed, 1000 to 1500 rpm, fan, gears, and drive motors make comparable noise. A series of tests on a laboratory model of the fan/end housing of a Westinghouse 1447 propulsion motor showed that by modifying the geometry of the end housing posts and reducing the diameter of the cooling fan, the tone at the blade passage frequency was virtually eliminated. In addition, the overall noise was reduced by over 10 dBA while the same airflow was maintained through the fan. When these treatments were applied to the motor itself, it was possible to maintain the same airflow as in the unmodified motor by redesigning the grill over the inlet at the commutator end of the motor. Noise reductions, however, were not as significant as in the laboratory model. Although the blade passage tone was virtually eliminated, overall noise reduction was in the 3 to 6 dBA range, depending on the combination of treatments used.
Elastic System Moving on an Elastically Supported Beam
Authors: Huang T. C. , Shah V. N.
Published: December 2011

The problem of a two-dimensional elastic system moving on a beam is considered. The moving elastic system or vehicle is represented by the structural members with distributed stiffness, damping, and inertia properties, and it is supported by the suspension units. Each suspension unit consists of a linear spring, a viscous damper, and an unsprung mass. The beam is supported at discrete points along its length, and/or by an elastic foundation. The deformations of the moving system and the beam are represented by their corresponding eigenfunction series. The resulting governing equations are represented by the coupled, ordinary differential equations with variable coefficients. The equations of motion for an elastic platform moving with constant velocity on a beam are derived and solved by the Hamming’s predictor-corrector method. Numerical examples are presented.
Long-Range Acoustic Scattering by Surface Inhomogeneities Beneath a Turbulent Boundary Layer
Authors: Crighton D. G.
Published: December 2011

Low-frequency turbulent boundary layer eddies inject a power Ps into the elastic structure over which the boundary layer is formed which generally greatly exceeds the acoustic power Pa directly radiated by the eddies (acoustically equivalent to quadrupoles). The power Ps remains trapped in the surface and an adjacent fluid layer and propagates in subsonic surface wave modes until it encounters a rib, or edge, or other surface inhomogeneity, from which a power Pe is scattered to the far field. While Pe is again small compared with Ps, it may nonetheless greatly exceed Pa, and in that case the dominant acoustic mechanism is associated with the long-range coupling between the quadrupole eddy and the remote inhomogeneity via subsonic surface waves. That interaction, and the acoustic fields produced by it, are examined in detail in this paper for the inhomogeneities represented by a simple line support rib, a simple point support rib, and an edge to a plane elastic plate, either with or without an adjacent rigid baffle, and with a range of edge conditions. Under conditions of “light” fluid loading, the long-range coupling mechanism seems unlikely to be of importance, but at low frequencies and under “heavy” fluid loading it appears that, even for large separations between an eddy and an inhomogeneity, the long-range coupling generates an acoustic field far in excess of that radiated by the same boundary layer turbulence over a homogeneous surface.
Active Impedance Control for One-Dimensional Sound
Authors: Guicking D. , Karcher K.
Published: December 2011

Generalizing the concept of active sound absorption, a system for active impedance control has been developed, so far for plane waves at normal incidence. The active reflector is a loudspeaker driven by the incident sound wave. Its feeding signal is derived from a “wave separator” with two microphones splitting up the standing wave field into incident and reflected wave. This system permits easy control of the reflection coefficient and eliminates feedback instability. Arbitrary reflection coefficients between almost 0 and about 1.5 have been realized in the frequency range from below 100 Hz to more than 800 Hz.
Modified Shielding Jet Model for Twin-Jet Shielding Analysis
Authors: Gerhold C. H. , Gilbride J.
Published: December 2011

An analytical model to estimate the shielding of noise emitted from a point noise source has been developed assuming the shielding jet to be a cylinder of constant radius with uniform flow across the cross section. Comparison to experiment indicated that the model overestimates diffraction of sound around the jet in the far downstream region. The shielding jet model is modified to include widening downstream of the nozzle exit. This not only represents a more realistic model of the jet, but is also expected to improve the shielding estimate downstream. The modified jet model incorporates a Mach number dependent widening rate, a corresponding decrease in flow velocity downstream and an equivalent slug flow evaluation to retain the locally parallel flow approximation of the model development. The shielding analysis with modified jet model is compared to measured data for a subsonic isothermal air jet and a simulated hot subsonic jet. Improvement of the shielding estimate is discussed.