bluuebunny/crossref_metadata_2025 huggingface dataset:
Their Views Matter: Frontline Regulators' Perceptions of the Regulated Community in Ohio
Authors: Pautz Michelle C.
Published: April 2012

Frontline regulators are largely responsible for the implementation and ongoing compliance with environmental laws. Yet, as with other frontline worker populations, environmental regulators are routinely overlooked. Existing acknowledgment of these regulators typically only extends to the regulatory enforcement strategy their agency employs. Missing in these conversations is a focused study on regulators themselves and their perceptions of the regulated community that they interact with daily. Understanding these perceptions will provide insights into how regulators approach their interactions and how they ensure regulatory compliance. This research reports on one‐on‐one interviews and a statewide survey of Ohio Environmental Protection Agency frontline regulators and their perceptions of the regulated community. Findings from this survey reveal generally positive perceptions of the regulated community in Ohio and experiences with them. These findings call attention to a neglected population and emphasize the importance of regulators' perceptions in their regulatory approach.
Obesity is the predominant predictor of impaired glucose tolerance and metabolic disturbance in polycystic ovary syndrome
Authors: LIANG SO‐JUNG , LIOU TSAN‐HON , LIN HUI‐WEN , HSU CHUN‐SEN , TZENG CHII‐RUEY , HSU MING‐I
Published: April 2012

Objective. To evaluate the contribution to glucose intolerance and metabolic syndrome of obesity combined with the diagnostic criteria of polycystic ovary syndrome (PCOS). Design. Prospective study. Setting. University teaching hospital from 31 August 2010 to 31 August 2011. Population. Two hundred and twenty women with PCOS and seventy normal control women. Methods. The clinical and biochemical characteristics of women with PCOS and control women were evaluated. Main outcome measures. The impact of obesity, hyperandrogenism, oligo‐anovulation and polycystic ovary morphology on impaired glucose tolerance and metabolic disturbances. Results. Obese women with PCOS had significantly higher insulin resistance than obese normal control women. Logistic regression analysis showed that obesity was the only factor that predicted impaired glucose tolerance and metabolic syndrome. Use of the area under the receiver operating characteristic curve (AUROC) for the body mass index to predict impaired glucose tolerance and metabolic syndrome was more accurate than AUROCs for serum total testosterone level and the average menstrual interval. Conclusions. Body weight status was the major factor determining the risk of impaired glucose tolerance and metabolic syndrome in women with PCOS. Obesity should be treated as the major factor determining long‐term health consequences associated with PCOS.
Oxytocin is expressed in epidermal keratinocytes and released upon stimulation with adenosine 5′‐[γ‐thio]triphosphate in vitro
Authors: Denda Sumiko , Takei Kentaro , Kumamoto Junichi , Goto Makiko , Tsutsumi Moe , Denda Mitsuhiro
Published: April 2012

Oxytocin is a neuropeptide produced primarily in the hypothalamus and is best known for its roles in parturition and lactation. It also influences behaviour, memory and mental state. Recent studies have suggested a variety of roles for oxytocin in peripheral tissues, including skin. Here we show that oxytocin is expressed in human skin. Immunohistochemical studies showed that oxytocin and its carrier protein, neurophysin I, are predominantly localized in epidermis. RT‐PCR confirmed the expression of oxytocin in both skin and cultured epidermal keratinocytes. We also show that oxytocin is released from keratinocytes after application of adenosine 5′‐[γ‐thio]triphosphate (ATPγS, a stable analogue of ATP) in a dose‐dependent manner. The ATPγS‐induced oxytocin release was inhibited by removal of extracellular calcium, or by the P2X receptor antagonist 2′,3′‐O‐(2,4,6‐trinitrophenyl)adenosine 5′‐triphosphate (TNP‐ATP). These results suggest that oxytocin is produced in human epidermal keratinocytes and is released in response to calcium influx via P2X receptors.
Evidence‐based practice standards for the use of topical pressurised oxygen therapy
Authors: Orsted Heather L , Poulson Randy ,   the Advisory Group, Baum Joseph , Christensen Dawn , Despatis Marc , Goettl Kyle , Haligowski David , Ho Chester , Louis Keith , O'Sullivan‐Drombolis Deirdre , Winberg Valerie , Woo Kevin Y
Published: April 2012

Whenever a new therapy enters the wound care arena it is mandatory to deliver the best evidence to clinicians, healthcare administrators and policy makers to support integration of the technology into clinical practice. While this can often be problematic when novel therapies lack a large body of supporting evidence, methods that incorporate the use of expert opinion do exist to evaluate existing evidence and create consensus statements that can help guide decisions. Topical pressurised oxygen therapy is a method of delivering pressurised and humidified oxygen directly to the wound bed to support the healing of chronic and hypoxic wounds. This article will present the process by which the evidence was identified and evaluated as well as present standards based on the evidence related to topical pressurised oxygen therapy. We will show, through the use of the evidence, how this therapy can be a non invasive safe approach for wound management for selected patients in all clinical care settings.
Thermal Shock Testing of Refractory Materials Using an Electron Beam Materials Test Facility
Authors: Thomser Corinna , Skiera Erik , Buerger Andreas , Linke Jochen , Loewenhoff Thorsten , Schmidt Axel , Singheiser Lorenz , Steinbrech Rolf
Published: April 2012

The thermal shock behavior of ceramic refractory materials is of particular interest. These materials are usually tested in downward thermal shocks by cooling hot specimens in water or air. In contrast to this method, the use of electron beam material testing facilities offers an alternative approach to perform thermal shock tests on heating. The method of thermal shock testing by an electron beam is introduced for ceramic refractory materials within this article. Finally, the material degradation of a carbon bonded MgO refractory material due to thermals shocks, applied with the electron beam, is presented.
Are Farm‐to‐School Programs More Common in States With Farm‐to‐School‐Related Laws?
Authors: Schneider Linda , Chriqui Jamie , Nicholson Lisa , Turner Lindsey , Gourdet Camille , Chaloupka Frank
Published: April 2012

BACKGROUND: Farm‐to‐School programs (FTSPs) connect schools with locally grown food. This article examines whether FTSPs are more common in public elementary schools (ESs) in states with a formal, FTSP law or with a related, locally grown procurement law.

METHODS: A pooled, cross‐sectional analysis linked nationally representative samples of 1872 public ESs (across 47 states) for the 2006–2007, 2007–2008, and 2008–2009 school years with state laws effective as of the beginning of September of each year that were collected and analyzed for all states. Multivariate logistic regression models examined the impact of state law on school FTSP participation, controlling for year and school‐level race/ethnicity, region, locale, free‐reduced lunch participation, and school size.

RESULTS: The percentage of schools located in a state with a FTSP‐specific law increased from 7.3% to 20.4% over the 3‐year period, while the percentage of schools located in a state with a locally grown procurement law was approximately 30% across all years. The percentage of schools with FTSPs has more than tripled over the last 3 years (from 4.9% to 17.7%). After adjusting for all covariates except year, FTSPs were significantly more likely in states with a FTSP‐specific law (OR = 2.45, 95% CI = 1.28‐4.67); once adjusting for year, the results were marginally significant (OR = 1.72, 95% CI = .91‐3.25). School‐level FTSPs were not related to state locally grown procurement laws.

CONCLUSION: Although the percentage of schools with FTSPs is relatively small, these programs are becoming more common, particularly in states with FTSP‐specific laws.
Environmental Justice at School: Understanding Research, Policy, and Practice to Improve Our Children's Health
Authors: Sampson Natalie
Published: April 2012

BACKGROUND: No overarching federal agencies or policies are responsible for ensuring environmental health at schools in the United States, potentially allowing many inequities for low‐income and minority communities to persist. This article examines emergent research, policy, and practice‐based efforts that may be used to identify and address environmental justice at school.

METHODS: A brief literature review was conducted to understand (1) major mental, behavioral, and physical outcomes associated with environmental risk for school‐aged children and (2) current research methods for assessing these relationships. Documents prepared by government agencies, school districts, and advocacy groups were also collected and synthesized to improve understanding of the state of planning and policies for maintaining or improving school environments.

RESULTS: Environmental risk can manifest in diverse ways such as mold, poor air quality, poor community design, or contaminated playgrounds. Deeply rooted in national and state structures of school funding and planning, such risks can lead to outcomes including respiratory illness, poor performance in school, and reduced levels of physical activity. With growing attention to these concerns, methods for measuring environmental risks and underlying disparities have advanced tremendously in the last few decades, yet development of innovative research approaches may be necessary to further advance and evaluate appropriate interventions.

CONCLUSIONS: Environmental injustice is generally unacknowledged during decision‐making in US school districts. Continued dialogue reflective of translatable science is necessary to support school districts with limited funding in ensuring safe, healthy environments for learning.
Stroke Management in Northern Lombardy: Organization of An Emergency-Urgency Network and Development of a Connection between Prehospital and In-Hospital Settings
Authors: Vidale Simone , Verrengia Elena , Gerardi Francesca , Arnaboldi Marco , Bezzi Giacomo , Bono Giorgio , Guidotti Mario , Grampa Giampiero , Perrone Patrizia , Zarcone Davide , Zoli Alberto , Beghi Ettore , Agostoni Elio , Porazzi Daniele , Landriscina Mario
Published: April 2012

Stroke is the leading cause of disability in adulthood, and the principal aim of care in cerebrovascular disease is the reduction of this negative outcome and mortality. Several studies demonstrated the efficacy of thrombolytic therapy in ischemic stroke, but up to 80% of cases could not be treated because the diagnostic workup exceeds the time limit. In this article, we described the design of a study conducted in the northern Lombardy, within the district of Sondrio, Lecco, Como, and Varese. The awaited results of this study are reduction of avoidable delay, organization of an operative stroke emergency network, and identification of highly specialized structures. The study schedules education and data registration with implementation and training of acute stroke management algorithms. The use of standardized protocols during prehospital and in-hospital phase can optimize acute stroke pathways. The results of this study could contribute to the assessment of an effective and homogeneous health system to manage acute stroke.
Defining Clinico‐Neuropathological Subtypes of Mesial Temporal Lobe Epilepsy with Hippocampal Sclerosis
Authors: Blümcke Ingmar , Coras Roland , Miyata Hajime , Özkara Cigdem
Published: April 2012

Hippocampal sclerosis (HS) is the most frequent cause of drug‐resistant focal epilepsies (ie, mesial temporal lobe epilepsy with hippocampal sclerosis; mTLE‐HS), and presents a broad spectrum of electroclinical, structural and molecular pathology patterns. Many patients become drug resistant during the course of the disease, and surgical treatment was proven helpful to achieve seizure control. Hence, up to 40% of patients suffer from early or late surgical failures. Different patterns of hippocampal cell loss, involvement of other mesial temporal structures, as well as temporal neocortex including focal cortical dysplasia, may contribute to the extent of the epileptogenic network and will be discussed. An international consensus is mandatory to clarify terminology use and to reliably distinguish mTLE‐HS subtypes. High‐resolution imaging with confirmed histopathologic diagnosis, as well as advanced neurophysiologic and molecular genetic measures, will be a powerful tool in the future to address these issues and help to predict each patient's probability to control their epilepsy in mTLE‐HS conditions.
Green Tea Ingestion by Rats Does Not Affect Iron Absorption but Does Alter the Composition  of the Saliva Proteome
Authors: Beverly Ariel B. , Zhu Le , Fish Tara L. , Thannhauser Theodore , Rutzke Mike A. , Miller Dennis D.
Published: April 2012

Abstract:  We tested the hypothesis that rats adapt to the iron absorption inhibitory effects of tea by modifying the expression of salivary proteins. Thirty‐six weanling rats were allocated into 6 groups. Two control groups were fed a semipurified diet containing 20 mg Fe2+/kg diet. Two groups were fed spray dried green tea infusion mixed into the diet (28.6 g tea/kg diet) and 2 groups were fed the control diet with a twice daily gavage of a tea solution (0.25 g tea/mL). Saliva samples were collected in 3 groups (control, gavage, and oral) on day 8 (acute) and in the remaining groups on day 31 (chronic). Iron absorption was assessed using a 58Fe3+ tracer administered on day 1 (acute) and day 24 (chronic). 2D gel electrophoresis and mass spectrometry were used to assess the composition of the saliva proteome. There was no significant difference in iron absorption between the 3 groups on either day 1 or day 24. Salivary proline‐rich proteins and submandibular gland secretory protein increased to a greater extent in the oral group than in the gavage group, when compared to control, within the same exposure time period. Amylase, chitinase, deoxyribonuclease, cysteine‐rich secretory protein 1, and parotid secretory protein all decreased to a greater extent in the oral tea group, compared to the control, within the same exposure time period. Our results show that green tea did not decrease iron absorption in rats but it did have a marked effect on the saliva proteome when given orally.
Characterization of the bioactive motif of neuregulin‐1, a fibroblast‐derived paracrine factor that regulates the constitutive color and the function of melanocytes in human skin
Authors: Choi Wonseon , Kolbe Ludger , Hearing Vincent J.
Published: April 2012

Interactions between melanocytes and neighboring cells in the skin (keratinocytes and fibroblasts) play important roles in regulating human skin color. We recently reported that neuregulin‐1 (NRG1) is highly expressed in fibroblasts from Fitzpatrick type VI skin (the darkest) and at least in part determines the constitutive color of human skin. We have now characterized the bioactive motif of NRG1 that is involved in modulating melanin production in human melanocytes. We found that 8‐mer motifs (PSRYLCKC and LCKCPNEF) increased melanin production but did not increase the proliferation of melanocytes; the minimum fragment that could elicit that effect was the tetrapeptide LCKC. This smaller bioactive peptide might have an advantage in clinical applications in which it modulates only pigmentation and does not stimulate melanocyte proliferation.
Increased frequency of osteoporosis and BMD below the expected range for age among South Korean women with rheumatoid arthritis
Authors: Lee Seung‐Geun , Park Young‐Eun , Park Sung‐Hoo , Kim Tae‐Kyun , Choi Hyun‐Ju , Lee Seong‐Jun , Kim Sung‐Il , Lee Sun‐Hee , Kim Geun‐Tae , Lee Joung‐Wook , Lee Jun‐Hee , Baek Seung‐Hoon
Published: April 2012

Objective

To compare the frequency of osteoporosis and bone mineral density (BMD) below the expected range for age between female patients with rheumatoid arthritis (RA) and healthy subjects and to determine risk factors for bone loss in female patients with RA.

Method

Two hundred and ninety‐nine patients with RA and 246 age‐matched healthy subjects were included in this study. BMD in the lumbar spine, femoral neck and total hip were measured with dual‐energy X‐ray absorptiometry. A T‐score of −2.5 or lower in postmenopausal women was defined as osteoporosis, and a Z‐score −2.0 or lower in females prior to menopause was defined as below the expected range for age.

Result

The frequency of osteoporosis in the RA patients (22.1%) was significantly higher than in healthy subjects (11.4%) at either the spine or hip (P = 0.014). The occurrence of BMD below the expected range for age in RA patients (7.8%) was also significantly higher than in healthy subjects (1.0%, P = 0.015). In 299 female patients with RA, higher age, lower body mass index and postmenopausal status were significantly associated with the lumbar spine and hip BMD reduction. Of disease‐related variables, glucocorticoid use was independently associated with reduction of hip BMD.

Conclusion

The prevalence of osteoporosis in the RA patients was 1.9 times higher than in healthy subjects. Glucocorticoid use was a risk factor for generalized bone loss in female RA patients.
Enamel roughness and depth profile after phosphoric acid etching of healthy and fluorotic enamel
Authors: Torres‐Gallegos I , Zavala‐Alonso V , Patiño‐Marín N , Martinez‐Castañon GA , Anusavice K , Loyola‐Rodríguez JP
Published: April 2012

Background:  Dental fluorosis requires aesthetic treatment to improve appearance and etching of enamel surfaces with phosphoric acid is a key step for adhesive restorations. The aim of this study was to evaluate surface roughness and a depth profile in healthy and fluorotic enamel before and after phosphoric acid etching at 15, 30 and 60 seconds.

Methods:  One hundred and sixty enamel samples from third molars with no fluorosis to severe fluorosis were evaluated by atomic force microscopy.

Results:  Healthy enamel showed a statistically significant difference (p < 0.05) between mean surface roughness at 15 seconds (180.3 nm), 30 seconds (260.9 nm) and 60 seconds (346.5 nm); depth profiles revealed a significant difference for the 60 second treatment (4240.2 nm). For mild fluorosis, there was a statistically significant difference (p < 0.05) between mean surface roughness for 30 second (307.8 nm) and 60 second (346.6 nm) treatments; differences in depth profiles were statistically significant at 15 seconds (2546.7 nm), 30 seconds (3884.2 nm) and 60 seconds (3612.1 nm). For moderate fluorosis, a statistically significant difference (p < 0.05) was observed for surface roughness for 30 second (324.5 nm) and 60 second (396.6 nm) treatments.

Conclusions:  Surface roughness and depth profile analyses revealed that the best etching results were obtained at 15 seconds for the no fluorosis and mild fluorosis groups, and at 30 seconds for the moderate fluorosis group. Increasing the etching time for severe fluorosis decreased surface roughness and the depth profile, which suggests less micromechanical enamel retention for adhesive bonding applications.
Bone regeneration in sinus augmentation procedures with calcium sulphate. Microstructure and microanaytical investigations
Authors: Pettinicchio M , Sammons R , Caputi S , Piattelli A , Traini T
Published: April 2012

Background:  The aim of this study was a histological and ultrastructural evaluation of the bone formed in human sinus augmentation procedures with calcium sulphate (CaS).

Methods:  Scanning electron microscopy (SEM) and energy dispersive X‐ray spectroscopy (EDS) were used to evaluate the relationship between CaS and newly‐formed bone, while birefringence was used to evaluate the bone structure around the CaS particles by polarized light microscopy. Unstained sections were studied with an Axiovert 200 M using the fluorescence in reflected UV light to evaluate the interface between CaS and newly‐formed bone. Twenty specimens retrieved from the sinus after a healing period of six months were studied.

Results:  EDS analysis of six specimens showed that little sulphur remained and residual particles appeared to have transformed to calcium phosphate. Under polarized light a few biomaterial remnants were present in some areas and covered by mature bone. The relationship between residual particles and bone due to the different photon emission under UV light stimulation was observed under fluorescence microscopy.

Conclusions:  The present results confirm the high biocompatibility and rapid resorption rate of CaS. The mechanism of transformation of CaS to calcium phosphate, already demonstrated in animal studies, has been confirmed in the present human study.
Preferential utilization of perilipin 2‐associated intramuscular triglycerides during 1 h of moderate‐intensity endurance‐type exercise
Authors: Shepherd S. O. , Cocks M. , Tipton K. D. , Ranasinghe A. M. , Barker T. A. , Burniston J. G. , Wagenmakers A. J. M. , Shaw C. S.
Published: April 2012

The lipid droplet (LD)‐associated protein perilipin 2 (PLIN2) appears to colocalize with LDs in human skeletal muscle fibres, although the function of PLIN2 in the regulation of intramuscular triglyceride (IMTG) metabolism is currently unknown. Here we investigated the hypothesis that the presence of PLIN2 in skeletal muscle LDs is related to IMTG utilisation during exercise. We therefore measured exercise‐induced changes in IMTG and PLIN2 distribution and changes in their colocalization. Muscle biopsies from the vastus lateralis were obtained from seven lean, untrained men (22 ± 2 years old, body mass index 24.2 ± 0.9 kg m−2 and peak oxygen uptake 3.35 ± 0.13 l min−1) before and after 1 h of moderate‐intensity cycling at ∼65% peak oxygen uptake. Cryosections were stained for perilipin 2, IMTG and myosin heavy chain type I and viewed using wide‐field and confocal fluorescence microscopy. Exercise induced a 50 ± 7% decrease in IMTG content in type I fibres only (P < 0.05), but no change in PLIN2 content. Colocalization analysis showed that the fraction of PLIN2 associated with IMTG was 0.67 ± 0.03 before exercise, which was reduced to 0.51 ± 0.01 postexercise (P < 0.05). Further analysis revealed that the number of PLIN2‐associated LDs was reduced by 31 ± 10% after exercise (P < 0.05), whereas the number of PLIN2‐null LDs was unchanged. No such changes were seen in type II fibres. In conclusion, this study shows that PLIN2 content in skeletal muscle is unchanged in response to a single bout of endurance exercise. Furthermore, the PLIN2 and IMTG association is reduced postexercise, apparently due to preferential utilization of PLIN2‐associated LDs. These results confirm the hypothesis that the PLIN2 association with IMTG is related to the utilization of IMTG as a fuel during exercise.
Pro‐inflammatory cytokines do not affect basal or hypoxia‐stimulated discharge of rat vagal paraganglia
Authors: O'Connor Edward T. , O'Halloran Ken D. , Jones James F. X.
Published: April 2012

Vagal paraganglia are structurally similar to the carotid body and are chemosensitive to reduction in the
. We hypothesized that they may also mediate communication between the immune system and the central nervous system via pro‐inflammatory cytokines or endotoxin. In vitro experiments with isolated superior laryngeal nerve (SLN) paraganglia were performed to test this hypothesis. We exposed the cells to increasing concentrations of interleukin‐1β, tumour necrosis factor‐α or interleukin‐6 (0.1, 0.3 and 1 ng ml−1) or bacterial lipopolysaccharide (LPS, 10 and 100 ng ml−1) during both normoxia (
≈ 100 mmHg) and hypoxia (
< 40 mmHg) whilst single‐fibre recordings were made from the main SLN trunk using a glass suction electrode. The results of these experiments confirmed previous findings that these cells respond strongly to changes in
, significantly increasing their discharge rate in response to hypoxia (from 0.71 ± 0.23 to 10.95 ± 1.74 Hz, P < 0.0001). However, neither the cytokines nor LPS had any significant effect on the baseline discharge rate of the SLN units at any concentration. When compared with time‐matched controls, the cytokines and LPS also had no effect on the peak hypoxic discharge rate of the SLN (P= 0.59 and 0.65, respectively). In conclusion, neither the basal nor the hypoxic discharge rate of the SLN paraganglia is modulated by the inflammatory mediators tested above, suggesting that these structures are not the afferent limb of an ‘immune reflex’.
Robust Delay-Dependent H∞ Control for Uncertain Structural Systems With Actuator Delay
Authors: Yazici Hakan , Guclu Rahmi , Kucukdemiral Ibrahim B. , Alpaslan Parlakci M. N.
Published: April 2012

This paper is concerned with the design of a robust, state-feedback, delay-dependent H∞ controller for an active vibration control of seismic-excited structural systems having actuator delay, norm bounded uncertainties, and L2 disturbances. The norm bounded uncertainties are assumed to exist in variations of structural stiffness and damping coefficients. Based on the selection of Lyapunov–Krasovskii functional, first a bounded real lemma (BRL) is obtained in terms of linear matrix inequalities (LMIs) such that the nominal, time-delay system is guaranteed to be globally asymptotically stable with minimum allowable disturbance attenuation level. Extending BRL, sufficient delay-dependent criteria are developed for a stabilizing H∞ controller synthesis involving a matrix inequality for which a nonlinear optimization algorithm with LMIs is proposed to get feasible solution to the problem. Moreover, for the case of existence of norm-bounded uncertainties, both the BRL and H∞ stabilization criteria are easily extended by employing a well-known bounding technique. Then, a cone complementary algorithm is also utilized to solve the nonconvex optimization problem. By use of the proposed method, a suboptimal controller with maximum allowable delay bound, uncertainty bound and minimum allowable disturbance attenuation level can be easily obtained by solving the proposed convex optimization technique. A four-degree-of-freedom uncertain structural system subject to seismic excitations is used to illustrate the effectiveness of the approach through simulations. Simulation results, obtained by using real time-history data of Kobe and Kocaeli earthquakes show that the proposed controller is very effective in reducing vibration amplitudes of storeys and guarantees stability at maximum actuator delay and parametric uncertainty bound.
Application of the Monte Carlo Method for Capacitive Pressure Transmitters Surveillance in Nuclear Power Plants
Authors: Montalvo C. , García-Berrocal A. , Blázquez J. , Balbás M.
Published: April 2012

In nuclear power plants (NPPs), according to current regulations, the response time of capacitive pressure transmitters is used as an index for surveillance. Such measurement can be carried out in situ applying the noise analysis techniques to the sensor output signal. The method is well established, and it is based on the autoregressive (AR) fitting optimized by the Akaike criterion (AIC). The sensor response is influenced by the sensing line, and its length is different in each plant. Recent empirical research has proved that the sensor inner structure can be modeled with a two real poles transfer function. In the present work, it has been proved that the noise analysis applied to the simulated response of a transmitter, modeled with two poles coupled with a sensing line, gives erroneous values for the ramp time delay when the sensing line is long. Specifically, the order of the AR model supplied by the Akaike criterion is not appropriate. Therefore, a Monte Carlo method is proposed to be applied in order to establish a new criterion, based on the statistical analysis of the repeatability of the ramp time delay obtained with the AR model.
Experimental Study on Characteristics of Methane–Coal-Dust Mixture Explosion and Its Mitigation by Ultra-Fine Water Mist
Authors: Xu Hongli , Wang Xishi , Gu Rui , Zhang Heping
Published: April 2012

This paper presents the results of an experimental investigation on the characteristics of methane–coal-dust mixture explosion and its mitigation by ultra-fine water mist. Four E12-1-K-type fast response thermocouples, two printed circuit board (PCB) piezotronic pressure transducers were used to obtain the temperature and pressure history, while a GigaView high-speed camera was used to visualize the processes. Different methane concentrations, coal-dust concentrations, diameters of coal particles, and volumes of ultra-fine water mist were considered to investigate their effects on methane–coal-dust mixture explosion. The temperature of explosion flame, the maximum explosion overpressure, the maximum rate of overpressure rise, and the critical volume flux of ultra-fine water mist were experimentally determined. The results show that the characteristics of the methane–coal-dust mixture explosion and the mitigating effectiveness by ultra-fine water mist are influenced by the methane concentration, the coal-dust concentration, the coal-dust diameter and the applied volume flux of ultra-fine water mist. For example, both the maximum explosion overpressure and rate of overpressure rise increased with increasing of coal-dust concentrations and methane concentrations. All of the test cases indicate that ultra-fine water mist can mitigate the mixture explosion and suppress the flame propagation efficiently from the images recorded by the high-speed video camera.
Optimal Bearing Housing Designing Using Topology Optimization
Authors: Kabus Simon , Pedersen Claus B. W.
Published: April 2012

The internal load distribution in rolling bearings has a high impact on the bearing fatigue life. This study presents a method to optimize roller bearing housing design in order to maximize the bearing fatigue life by ensuring an optimal internal load distribution. An FE-model of a cylindrical roller bearing utilizing nonlinear springs in the roller modeling is presented, which is capable of simulating the bearing load distribution efficiently. The optimal load distribution is achieved by specifying the desired internal load distribution as design constraints in a topology optimization of the bearing housing design. The superiority of the method is clearly demonstrated through case studies involving a cylindrical roller bearing, where it is shown that the fatigue life is increased and the bearing housing mass and roller contact misalignment is reduced.
The Effect of the Location of Nucleation Sites on the Thermal-Hydraulic Stability of a Short-Tube Natural Circulation Loop
Authors: Kapitz Marek , Wiesche Stefan aus der
Published: April 2012

The use of small two-phase natural circulation loops is an attractive option for efficient cooling applications and innovative steam generators. An experimental study was conducted to examine how the thermal-hydraulic stability and operating conditions of these devices are affected by nucleation sites. A very smooth glass tube with artificial nucleation sites was used as a boiling channel. The mass flow rate was obtained as a function of heat flux and nucleation site location. Nucleation sites have a strong impact on stability behavior, particularly for low heat flux levels. The observed flow instabilities were analyzed with regard to nonlinear effects and chaotic behavior.
The Port Width and Position Determination for Pressure-Exchange Ejector
Authors: Zhao Wenjing , Hu Dapeng , Liu Peiqi , Dai Yuqiang , Zou Jiupeng , Zhu Che , Zhao Jiaquan
Published: April 2012

A pressure-exchange ejector transferring energy by compression and expansion waves has the potential for higher efficiency. The width and position of each port are essential in pressure-exchange ejector design. A dimensionless time τ expressing both port widths and the positions of port ends was introduced. A prototype was designed and the experimental system was set up. Many sets of experiment with different geometrical arrangements were conducted. The results suggest that the efficiency greatly changes with the geometrical arrangements. The efficiency is about 60% at proper port widths and positions, while at improper geometrical arrangements, the efficiency is much lower and the maximum deviation may reach about 20%. The proper dimensionless port widths and positions at different operating conditions are obtained. For a fixed overall pressure ratio, the widths of the high pressure flow inlet and middle pressure flow outlet increase as the outlet pressure increases and the low pressure flow inlet width is reduced with a larger outlet pressure. The middle pressure flow outlet (MO) opening end remains constant at different outlet pressures. The positions of the high pressure flow inlet (HI) closed end and the low pressure flow inlet (LI) open end increase with the elevation of outlet pressure, however, the distance between the HI closing end and the LI opening end is constant. The port widths and positions have a significant influence on the performance of the pressure-exchange ejector. The dimensionless data obtained are very valuable for pressure-exchange ejector design and performance optimization.
Open-Loop Control of Combustion Instabilities and the Role of the Flame Response to Two-Frequency Forcing
Authors: Ćosić Bernhard , Bobusch Bernhard C. , Moeck Jonas P. , Paschereit Christian Oliver
Published: April 2012

Controlling combustion instabilities by means of open-loop forcing at non-resonant frequencies is attractive because neither a dynamic sensor signal nor a signal processor is required. On the other hand, since the mechanism by which this type of control suppresses an unstable thermoacoustic mode is inherently nonlinear, a comprehensive explanation for success (or failure) of open-loop control has not been found. The present work contributes to the understanding of this process in that it interprets open-loop forcing at non-resonant frequencies in terms of the flame’s nonlinear response to a superposition of two approximately sinusoidal input signals. For a saturation-type nonlinearity, the fundamental gain at one frequency may be decreased by increasing the amplitude of a secondary frequency component in the input signal. This effect is first illustrated on the basis of an elementary model problem. In addition, an experimental investigation is conducted at an atmospheric combustor test-rig to corroborate the proposed explanation. Open-loop acoustic and fuel-flow forcing at various frequencies and amplitudes is applied at unstable operating conditions that exhibit high-amplitude limit-cycle oscillations. The effectiveness of specific forcing parameters in suppressing self-excited oscillations is correlated with flame response measurements that include a secondary forcing frequency. The results demonstrate that a reduction in the fundamental harmonic gain at the instability frequency through the additional forcing at a non-resonant frequency is one possible indicator of successful open-loop control. Since this mechanism is independent of the system acoustics, an assessment of favorable forcing parameters, which stabilize thermoacoustic oscillations, may be based solely on an investigation of burner and flame.
Measurement of Volatile Particulate Matter Emissions From Aircraft Engines Using a Simulated Plume Aging System
Authors: Peck Jay , Timko Michael T. , Yu Zhenhong , Wong Hsi-Wu , Herndon Scott C. , Yelvington Paul E. , Miake-Lye Richard C. , Wey Changlie , Winstead Edward L. , Ziemba Luke D. , Anderson Bruce E.
Published: April 2012

Aircraft exhaust contains nonvolatile (soot) particulate matter (PM), trace gas pollutants, and volatile PM precursor material. Nonvolatile soot particles are predominantly present at the engine exit plane, but volatile PM precursors form new particles or add mass to the existing ones as the exhaust is diluted and cooled. Accurately characterizing the volatile PM mass, number, and size distribution is challenging due to this evolving nature and the impact of local ambient conditions on the gas-to-particle conversion processes. To accurately and consistently measure the aircraft PM emissions, a dilution and aging sampling system that can condense volatile precursors to particle phase to simulate the atmospheric evolution of aircraft engine exhaust has been developed. In this paper, a field demonstration of its operation is described. The dilution/aging probe system was tested using both a combustor rig and on-wing CFM56-7 engines. During the combustor rig testing at NASA Glenn Research Center, the dilution/aging probe supported formation of both nucleation/growth mode particles and soot coatings. The results showed that by increasing residence time, the nucleation particles become larger in size, increase in total mass, and decrease in number. During the on-wing CFM56-7 engine testing at Chicago Midway Airport, the dilution/aging probe was able to form soot coatings along with nucleation mode particles, unlike conventional 1-m probe engine measurements. The number concentration of nucleation particles depended on the sample fraction and relative humidity of the dilution air. The performance of the instrument is analyzed and explained using computational microphysics simulations.
Quick Response Fuel Injector for Direct-Injection Gasoline Engines
Authors: Abe Motoyuki , Maekawa Noriyuki , Yasukawa Yoshihito , Ishikawa Tohru , Namaizawa Yasuo , Ehara Hideharu
Published: April 2012

We developed a new injector for direct injection gasoline engines that reduce the exhaust emissions and help to reduce fuel consumption. The newly developed actuator in this injector has two features. One is a bounceless valve closing mechanism, and the second is quick response moving parts. The first feature, the bounceless valve closing mechanism, can prevent ejecting a coarse droplet, which causes unburned gas emission. The new actuation mechanism realizes the bounceless valve closing. We analyzed the valve motion and injection behavior. The second feature, the quick-response actuator, achieves a smaller minimum injection quantity. This feature assists in reducing the fuel consumption under low load engine conditions. The closing delay time of the needle valve is the dominant factor of the minimum injection quantity because the injection quantity is controlled by the duration time of the valve opening. The new actuator movements can be operated with a shorter closing delay time. The closing delay time is caused by a magnetic delay and kinematic delay. A compact magnetic circuit of the actuator reduces the closing delay time by 26%. In addition, the kinematic delay was improved when the hydraulic resistance was reduced by 9%. As a result, the new injector realizes reduction of the minimum injection quantity by 25% compared to a conventional injector.
Thermohydrodynamic Analysis of Spiral Groove Mechanical Face Seal for Liquid Applications
Authors: Qiu Yifan , Khonsari M. M.
Published: April 2012

In this study, a three-dimensional thermohydrodynamic (THD) CFD model is developed to study the characteristics of an inward pumping spiral groove mechanical seal pair using a commercial CFD software CFD-ACE + . The model is capable of predicting the temperature distribution and pressure distribution of the seal pair. Based on the CFD model, a parametric study is conducted to evaluate the performance of the seal. It is found that thermal behavior plays an important role in the overall performance of a seal. The spiral groove parameter can be optimized to achieve desired performance. The optimization is dependent on the application requirement of the seal.
Discharge Imbalance Mitigation in Francis Turbine Draft-Tube Bays
Authors: Tridon S. , Barre S. , Ciocan G. , Ségoufin C. , Leroy P.
Published: April 2012

Rehabilitation of ageing power plant is a growing market with specific needs: we have to deal with non up-to-date elements in terms of hydraulic behavior. Refurbishment projects are often focused on the guide vane and runner modification. But for low-head refurbishment projects, the draft-tube is a non negligible part of the overall performance. In some cases, pathological draft-tubes have been encountered with a significant efficiency drop near the best efficiency point. Modification of the draft-tube in order to attenuate, and even eliminate, this effect can thus have a real impact on improving the performance of the power plant, and therefore become economically justified (that heavily depends on the addition or removal of material from the draft-tube walls). Laser Doppler Velocimetry (LDV) measurements near draft-tube outlet have been achieved for both original and modified draft-tube. It offers 2D velocity profiles and permits to calculate discharge repartition in each bay. Pressure recovery factor measured separately for each bay is used to quantify losses.
Effects of Load Distribution on Life of Radial Roller Bearings
Authors: Nagatomo Takafumi , Takahashi Ken , Okamura Yoshiaki , Kigawa Takehiko , Noguchi Shoji
Published: April 2012

An external load applied to a radial rolling bearing is distributed among the rolling elements. In many applications, the bearing internal load distribution may be altered by the elastic deformations of the bearing rings. This alteration can have an effect on bearing life. The objective of this study is to investigate the effect of load distribution on bearing life, both theoretically and experimentally, using several housing models which provide different contact conditions between the housing bore and the outer ring. This paper first presents a newly developed method of determining dynamic load distributions with an optical fiber strain sensor. The measurements of the load distribution for the housing models by using this method have shown that the contact condition between the housing bore and the outer ring affects the load distribution, and the effect of the load distribution on the bearing life has been confirmed by the theoretical calculation of the bearing life. Furthermore, endurance tests using dented bearings were performed to validate the effect of load distribution on bearing life. The results of the tests have substantiated that the bearing life is substantially affected by the load distribution; moreover, it has been shown that there is a linear relationship between the calculated lives and the experimental ones.
Topology Optimization of Compliant Mechanisms Using the Improved Quadrilateral Discretization Model
Authors: Zhou Hong , Mandala Avinash R.
Published: April 2012

The improved quadrilateral discretization model for the topology optimization of compliant mechanisms is introduced in this paper. The design domain is discretized into quadrilateral design cells and each quadrilateral design cell is further subdivided into triangular analysis cells. All kinds of dangling quadrilateral design cells and sharp-corner triangular analysis cells are removed in the improved quadrilateral discretization model to promote the material utilization. Every quadrilateral design cell or triangular analysis cell is either solid or void to implement the discrete topology optimization and eradicate the topology uncertainty caused by intermediate material states. The local stress constraint is directly imposed on each triangular analysis cell to make the synthesized compliant mechanism safe. The binary bit-array genetic algorithm is used to search for the optimal topology to circumvent the geometrical bias against the vertical design cells. Two topology optimization examples of compliant mechanisms are solved based on the proposed improved quadrilateral discretization model to verify its effectiveness.
Fast Convergence of Iterative Computation for Incompressible-Fluid Reynolds Equation
Authors: Wang Nenzi , Cha Kuo-Chiang , Huang Hua-Chih
Published: April 2012

When a discretized Reynolds equation is to be solved iteratively at least three subjects have to be determined first. These are the iterative solution method, the size of gridwork for the numerical model, and the stopping criterion for the iterative computing. The truncation error analysis of the Reynolds equation is used to provide the stopping criterion, as well as to estimate an adequate grid size based on a required relative precision or grid convergence index. In the simulated lubrication analyses, the convergent rate of the solution is further improved by combining a simple multilevel computing, the modified Chebyshev acceleration, and multithreaded computing. The best case is obtained by using the parallel three-level red-black successive-over-relaxation (SOR) with Chebyshev acceleration. The speedups of the best case relative to the case using sequential SOR with optimal relaxation factor are around 210 and 135, respectively, for the slider and journal bearing simulations.
Modeling and Design of Air Vane Motors for Minimal Torque Ripples
Authors: Cheng Cheng-Wei , Lan Chao-Chieh , Tseng Chun-Yi
Published: April 2012

This paper presents the analysis and design of a novel air vane motor. Air motors have a very high specific power. They require compressed air rather than electricity to produce motion; thus, they avoid sparks and can be used in demanding environments. Similar to other types of rotary machines, air vane motors exhibit torque fluctuations. The varying torque curve is a result of unmatched torques generated by the vanes in one revolution. Accompanying the torque fluctuations are dynamic speed ripples that produce undesirable vibration on the load side. Rather than using auxiliary flywheels or dampers to smoothen the fluctuation, we propose a new motor with noncircular stator profile so as to increase the flexibility of balancing vane torques. Through numerical optimization of the parametric noncircular profile, a nearly constant torque curve can be achieved. Experiments validate that the speed ripples are greatly suppressed without compromising performance, when compared with traditional air vane motors that employ circular stator profiles. We expect that the noncircular stator profile design can be applied to air vane motors of various sizes to minimize torque and speed ripples.
Fizz-ball Fizzics
Authors: Moinester Murray , Gerland Lars , Liger-Belair Gérard , Ocherashvili Aharon
Published: April 2012

We describe the fluid dynamics principles governing the up-down oscillatory cycling of a bubble- covered, low-density, low-mass ball of material (referred to henceforth as a “fizz-ball”) immersed inside a glass of bubbling (super-saturated) carbonated liquid. The bubbles serve to desaturate the liquid of excess CO2. The fizz-ball acts as a catalyst to speed up this process.
Minds-On Audio-Guided Activities (MAGA): More Than Hearing and Better Than Seeing
Authors: Hancock James Brian , Fornari Marco
Published: April 2012

Minds-On Audio-Guided Activities (MAGA) are podcast-delivered instruction designed to facilitate learning through all-body experiments. Instruction by MAGA has undergone preliminary testing in an introductory physics course at Central Michigan University. Topics are currently focused on mechanics and range from discovering the differences between distance and displacement to momentum to the Coriolis effect (see Table I). MAGA instruction emphasizes physical activity, encouraging learners to engage their bodies and minds simultaneously. It targets a combination of learning styles, stimulating group discussion by using technology familiar to the learners. MAGA should be used as either an introductory activity or as a supplemental experience for students, compared with creating an entire class around MAGA-style instruction. Average learning gain1 for the trial semesters shows certain MAGA-covered topics are more effective than others. Oral interviews designed to probe the effectiveness of MAGA as well as student attitudes indicate that MAGA may foster longer-term retention of concepts.
Moment of Inertia of a Ping-Pong Ball
Authors: Cao Xian-Sheng
Published: April 2012

This note describes how to theoretically calculate and experimentally measure the moment of inertia of a Ping-Pong® ball. The theoretical calculation results are in good agreement with the experimental measurements that can be reproduced in an introductory physics laboratory.