bluuebunny/crossref_metadata_2025 huggingface dataset:
The Superorganism Account of Human Sociality
Authors: Kesebir Selin
Published: December 2011

Biologists call highly cooperative and socially integrated animal groups like beehives and ant colonies “superorganisms.” In such species, the colony acts like an organism despite each animal’s physical individuality. This article frames human sociality through the superorganisms metaphor by systematically reviewing the superorganismic features of human psychology. These features include (1) mechanisms to integrate individual units, (2) mechanisms to achieve unity of action, (3) low levels of heritable within-group variation, (4) a common fate, and (5) mechanisms to resolve conflicts of interest in the collective’s favor. It is concluded that human beings have a capacity to partly and flexibly display each of these superorganismic properties. Group identification is a key mechanism that activates human superorganismic properties, and threats to the group a key activating condition. This metaphor organizes diverse aspects of human psychology (e.g., normative conformity, social identity processes, religion, and the “rally around the flag” reflex) into a coherent framework.
Bread or Games?
Authors: Nooij Michiel de , Berg Marcel van den , Koopmans Carl
Published: December 2011

Many countries compete fiercely for the right to host mega-events like the World Cup. Proponents of hosting mega-events claim that yields economic gains. Many available studies focus on partial effects of hosting or concern ex post analyses. The authors utilize the existing literature to perform a detailed cost–benefit analysis (CBA) of the Netherlands bidding jointly with Belgium for the 2018 World Cup. The authors show that national pride and pleasure come at a price and financial gains are unlikely. Based on this CBA, the authors predict that the costs of the 2018 World Cup in Russia will also exceed the financial benefits.
Portraits of Leaders
Authors: Schulte Don P. , Hong Barbara S. S.
Published: December 2011

This case study uses real events and hypothetical elements associated with the struggle for school finance equity in Texas. It involves a superintendent faced with difficult choices brought about by a convergence of events and issues, namely, by a national and state economic crisis, the demographic realities of his district, a historically contentious political landscape of his state, a tradition of leadership for social justice established in his school system, and by his own career aspirations. This work is particularly significant because it prompts specific questions related to elements of social justice leadership that are not often specifically addressed in professional preparation programs, namely, the chosen means of advocacy and the resulting consequences to the actor. It also directly addresses a critical domain of social justice action, school finance equity.
COPD association and repeatability of blood biomarkers in the ECLIPSE cohort
Authors: Dickens Jennifer A , Miller Bruce E , Edwards Lisa D , Silverman Edwin K , Lomas David A , Tal-Singer Ruth ,   the Evaluation of COPD Longitudinally to Identify Surrogate Endpoints (ECLIPSE) study investigators
Published: December 2011

Background

There is a need for biomarkers to better characterise individuals with COPD and to aid with the development of therapeutic interventions. A panel of putative blood biomarkers was assessed in a subgroup of the Evaluation of COPD Longitudinally to Identify Surrogate Endpoints (ECLIPSE) cohort.

Methods

Thirty-four blood biomarkers were assessed in 201 subjects with COPD, 37 ex-smoker controls with normal lung function and 37 healthy non-smokers selected from the ECLIPSE cohort. Biomarker repeatability was assessed using baseline and 3-month samples. Intergroup comparisons were made using analysis of variance, repeatability was assessed through Bland-Altman plots, and correlations between biomarkers and clinical characteristics were assessed using Spearman correlation coefficients.

Results

Fifteen biomarkers were significantly different in individuals with COPD when compared to former or non-smoker controls. Some biomarkers, including tumor necrosis factor-α and interferon-γ, were measurable in only a minority of subjects whilst others such as C-reactive protein showed wide variability over the 3-month replication period. Fibrinogen was the most repeatable biomarker and exhibited a weak correlation with 6-minute walk distance, exacerbation rate, BODE index and MRC dyspnoea score in COPD subjects. 33% (66/201) of the COPD subjects reported at least 1 exacerbation over the 3 month study with 18% (36/201) reporting the exacerbation within 30 days of the 3-month visit. CRP, fibrinogen interleukin-6 and surfactant protein-D were significantly elevated in those COPD subjects with exacerbations within 30 days of the 3-month visit compared with those individuals that did not exacerbate or whose exacerbations had resolved.

Conclusions

Only a few of the biomarkers assessed may be useful in diagnosis or management of COPD where the diagnosis is based on airflow obstruction (GOLD). Further analysis of more promising biomarkers may reveal utility in subsets of patients. Fibrinogen in particular has emerged as a potentially useful biomarker from this cohort and requires further investigation.

Trial Registration

SCO104960, clinicaltrials.gov identifier NCT00292552
Microplate-based platform for combined chromatin and DNA methylation immunoprecipitation assays
Authors: Yu Jingjing , Feng Qinghua , Ruan Yusong , Komers Radko , Kiviat Nancy , Bomsztyk Karol
Published: December 2011

Background

The processes that compose expression of a given gene are far more complex than previously thought presenting unprecedented conceptual and mechanistic challenges that require development of new tools. Chromatin structure, which is regulated by DNA methylation and histone modification, is at the center of gene regulation. Immunoprecipitations of chromatin (ChIP) and methylated DNA (MeDIP) represent a major achievement in this area that allow researchers to probe chromatin modifications as well as specific protein-DNA interactions in vivo and to estimate the density of proteins at specific sites genome-wide. Although a critical component of chromatin structure, DNA methylation has often been studied independently of other chromatin events and transcription.

Results

To allow simultaneous measurements of DNA methylation with other genomic processes, we developed and validated a simple and easy-to-use high throughput microplate-based platform for analysis of DNA methylation. Compared to the traditional beads-based MeDIP the microplate MeDIP was more sensitive and had lower non-specific binding. We integrated the MeDIP method with a microplate ChIP assay which allows measurements of both DNA methylation and histone marks at the same time, Matrix ChIP-MeDIP platform. We illustrated several applications of this platform to relate DNA methylation, with chromatin and transcription events at selected genes in cultured cells, human cancer and in a model of diabetic kidney disease.

Conclusion

The high throughput capacity of Matrix ChIP-MeDIP to profile tens and potentially hundreds of different genomic events at the same time as DNA methylation represents a powerful platform to explore complex genomic mechanism at selected genes in cultured cells and in whole tissues. In this regard, Matrix ChIP-MeDIP should be useful to complement genome-wide studies where the rich chromatin and transcription database resources provide fruitful foundation to pursue mechanistic, functional and diagnostic information at genes of interest in health and disease.
Fruit development of the diploid kiwifruit, Actinidia chinensis 'Hort16A'
Authors: Richardson Annette C , Boldingh Helen L , McAtee Peter A , Gunaseelan Kularajathevan , Luo Zhiwei , Atkinson Ross G , David Karine M , Burdon Jeremy N , Schaffer Robert J
Published: December 2011

Background

With the advent of high throughput genomic tools, it is now possible to undertake detailed molecular studies of individual species outside traditional model organisms. Combined with a good understanding of physiological processes, these tools allow researchers to explore natural diversity, giving a better understanding of biological mechanisms. Here a detailed study of fruit development from anthesis through to fruit senescence is presented for a non-model organism, kiwifruit,Actinidia chinensis('Hort16A').

Results

Consistent with previous studies, it was found that many aspects of fruit morphology, growth and development are similar to those of the model fruit tomato, except for a striking difference in fruit ripening progression. The early stages of fruit ripening occur as the fruit is still growing, and many ripening events are not associated with autocatalytic ethylene production (historically associated with respiratory climacteric). Autocatalytic ethylene is produced late in the ripening process as the fruit begins to senesce.

Conclusion

By aligningA. chinensisfruit development to a phenological scale, this study provides a reference framework for subsequent physiological and genomic studies, and will allow cross comparison across fruit species, leading to a greater understanding of the diversity of fruits found across the plant kingdom.
Tyrosine kinase chromosomal translocations mediate distinct and overlapping gene regulation events
Authors: Kim Hani , Gillis Lisa C , Jarvis Jordan D , Yang Stuart , Huang Kai , Der Sandy , Barber Dwayne L
Published: December 2011

Background

Leukemia is a heterogeneous disease commonly associated with recurrent chromosomal translocations that involve tyrosine kinases including BCR-ABL, TEL-PDGFRB and TEL-JAK2. Most studies on the activated tyrosine kinases have focused on proximal signaling events, but little is known about gene transcription regulated by these fusions.

Methods

Oligonucleotide microarray was performed to compare mRNA changes attributable to BCR-ABL, TEL-PDGFRB and TEL-JAK2 after 1 week of activation of each fusion in Ba/F3 cell lines. Imatinib was used to control the activation of BCR-ABL and TEL-PDGFRB, and TEL-JAK2-mediated gene expression was examined 1 week after Ba/F3-TEL-JAK2 cells were switched to factor-independent conditions.

Results

Microarray analysis revealed between 800 to 2000 genes induced or suppressed by two-fold or greater by each tyrosine kinase, with a subset of these genes commonly induced or suppressed among the three fusions. Validation by Quantitative PCR confirmed that eight genes (Dok2, Mrvi1, Isg20, Id1, gp49b, Cxcl10, Scinderin, and collagen Vα1(Col5a1)) displayed an overlapping regulation among the three tested fusion proteins. Stat1 and Gbp1 were induced uniquely by TEL-PDGFRB.

Conclusions

Our results suggest that BCR-ABL, TEL-PDGFRB and TEL-JAK2 regulate distinct and overlapping gene transcription profiles. Many of the genes identified are known to be involved in processes associated with leukemogenesis, including cell migration, proliferation and differentiation. This study offers the basis for further work that could lead to an understanding of the specificity of diseases caused by these three chromosomal translocations.
Comparative one-factor-at-a-time, response surface (statistical) and bench-scale bioreactor level optimization of thermoalkaline protease production from a psychrotrophic Pseudomonas putida SKG-1 isolate
Authors: Singh Santosh K , Singh Sanjay K , Tripathi Vinayak R , Khare Sunil K , Garg Satyendra K
Published: December 2011

Background

Production of alkaline protease from various bacterial strains using statistical methods is customary now-a-days. The present work is first attempt for the production optimization of a solvent stable thermoalkaline protease by a psychrotrophic Pseudomonas putida isolate using conventional, response surface methods, and fermentor level optimization.

Results

The pre-screening medium amended with optimized (w/v) 1.0% glucose, 2.0% gelatin and 0.5% yeast extract, produced 278 U protease ml-1 at 72 h incubation. Enzyme production increased to 431 Uml-1 when Mg2+ (0.01%, w/v) was supplemented. Optimization of physical factors further enhanced protease to 514 Uml-1 at pH 9.0, 25°C and 200 rpm within 60 h. The combined effect of conventionally optimized variables (glucose, yeast extract, MgSO4 and pH), thereafter predicted by response surface methodology yielded 617 U protease ml-1 at glucose 1.25% (w/v), yeast extract 0.5% (w/v), MgSO4 0.01% (w/v) and pH 8.8. Bench-scale bioreactor level optimization resulted in enhanced production of 882 U protease ml-1 at 0.8 vvm aeration and 150 rpm agitation during only 48 h incubation.

Conclusions

The optimization of fermentation variables using conventional, statistical approaches and aeration/agitation at fermentor level resulted in ~13.5 folds increase (882 Uml-1) in protease production compared to un-optimized conditions (65 Uml-1). This is the highest level of thermoalkaline protease reported so far by any psychrotrophic bacterium.
Tracheo-brachiocephalic artery fistula after tracheostomy associated with thoracic deformity: a case report
Authors: Ogawa Kie , Nitta Norihisa , Sonoda Akinaga , Takahashi Masashi , Suzuki Tomoaki , Kitamura Shoji , Hanaoka Jun , Tezuka Noriaki , Murata Kiyoshi
Published: December 2011

Introduction

Tracheo-brachiocephalic artery fistulae are critical long-term complications after tracheostomy, reported in 0.6% of patients within three to four weeks after the procedure. In 30% to 50% of cases there is some bleeding prior to onset. Since the onset involves sudden massive bleeding, the prognosis is poor; the reported survival rate is 10% to 30%. The direct cause of bleeding is the formation of a fistula with the trachea subsequent to arterial injury by the tracheostomy tube. Endo-tracheal factors are movement of the tracheostomy tube due to body movement and seizures, pressure exerted by the cuff of the tracheostomy tube, tracheostomy at lower levels, and the fragility of blood vessels and the trachea due to steroid or radiation therapy, and malnutrition. Extra-tracheal factors include prior surgery and deformity and shifting of the trachea and major blood vessels due to congenital kyphoscoliosis or thoracic deformity. There has been no report of the usefulness of contrast-enhanced computed tomography studies to identify the anatomical relationship between the trachea and brachiocephalic artery.

Case presentation

A 27-year-old Mongolian woman with congenital muscular dystrophy who underwent tracheal intubation for airway management due to pneumonia and granulation development developed a tracheo-brachiocephalic artery fistula during the placement of the tracheostomy tube. It was diagnosed by contrast-enhanced chest computed tomography and repaired. About a month later she developed massive airway bleeding during replacement of the tracheostomy tube. Temporary hemostasis was achieved by compression via cuff inflation. A contrast-enhanced chest computed tomography scan demonstrated a narrowed brachiocephalic artery running along and ventral to the tube and a tracheo-brachiocephalic artery fistula was suspected. She underwent brachiocephalic artery resection and aorta, right common carotid artery, and subclavian artery bypass surgery with an innominate vein, tracheoplasty, and partial sternectomy. We noted marked thoracic deformity; the brachiocephalic artery was compressed by the trachea and chest wall resulting in localized wall necrosis and the development of a tracheo-brachiocephalic artery fistula, a fatal complication whose prevention is important.

Conclusions

We suggest that before tracheostomy, the anatomic relationship between the trachea and brachiocephalic artery must be confirmed by contrast-enhanced chest computed tomography scan.
Blood lactate as a predictor for in-hospital mortality in patients admitted acutely to hospital: a systematic review
Authors: Kruse Ole , Grunnet Niels , Barfod Charlotte
Published: December 2011

Background

Using blood lactate monitoring for risk assessment in the critically ill patient remains controversial. Some of the discrepancy is due to uncertainty regarding the appropriate reference interval, and whether to perform a single lactate measurement as a screening method at admission to the hospital, or serial lactate measurements. Furthermore there is no consensus whether the sample should be drawn from arterial, peripheral venous, or capillary blood. The aim of this review was:

1) To examine whether blood lactate levels are predictive for in-hospital mortality in patients in the acute setting, i.e. patients assessed pre-hospitally, in the trauma centre, emergency department, or intensive care unit.

2) To examine the agreement between arterial, peripheral venous, and capillary blood lactate levels in patients in the acute setting.

Methods

We performed a systematic search using PubMed, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and CINAHL up to April 2011. 66 articles were considered potentially relevant and evaluated in full text, of these ultimately 33 articles were selected.

Results and Conclusion

The literature reviewed supported blood lactate monitoring as being useful for risk assessment in patients admitted acutely to hospital, and especially the trend, achieved by serial lactate sampling, is valuable in predicting in-hospital mortality. All patients with a lactate at admission above 2.5 mM should be closely monitored for signs of deterioration, but patients with even lower lactate levels should be considered for serial lactate monitoring. The correlation between lactate levels in arterial and venous blood was found to be acceptable, and venous sampling should therefore be encouraged, as the risk and inconvenience for this procedure is minimal for the patient. The relevance of lactate guided therapy has to be supported by more studies.
Uptake of prevention of mother to child transmission interventions in Kenya: health systems are more influential than stigma
Authors: Kinuthia John , Kiarie James N , Farquhar Carey , Richardson Barbra A , Nduati Ruth , Mbori‐Ngacha Dorothy , John‐Stewart Grace
Published: December 2011

Background

We set out to determine the relative roles of stigma versus health systems in non‐uptake of prevention of mother to child transmission (PMTCT) of HIV‐1 interventions: we conducted cross‐sectional assessment of all consenting mothers accompanying infants for six‐week immunizations.

Methods

Between September 2008 and March 2009, mothers at six maternal and child health clinics in Kenya's Nairobi and Nyanza provinces were interviewed regarding PMTCT intervention uptake during recent pregnancy. Stigma was ascertained using a previously published standardized questionnaire and infant HIV‐1 status determined by HIV‐1 polymerase chain reaction.

Results

Among 2663 mothers, 2453 (92.1%) reported antenatal HIV‐1 testing. Untested mothers were more likely to have less than secondary education (85.2% vs. 74.9%, p = 0.001), be from Nyanza (47.1% vs. 32.2%, p < 0.001) and have lower socio‐economic status. Among 318 HIV‐1‐infected mothers, 90% reported use of maternal or infant antiretrovirals. Facility delivery was less common among HIV‐1‐infected mothers (69% vs. 76%, p = 0.009) and was associated with antiretroviral use (p < 0.001). Although internal or external stigma indicators were reported by between 12% and 59% of women, stigma was not associated with lower HIV‐1 testing or infant HIV‐1 infection rates; internal stigma was associated with modestly decreased antiretroviral uptake. Health system factors contributed to about 60% of non‐testing among mothers who attended antenatal clinics and to missed opportunities in offering antiretrovirals and utilization of facility delivery. Eight percent of six‐week‐old HIV‐1‐exposed infants were HIV‐1 infected.

Conclusions

Antenatal HIV‐1 testing and antiretroviral uptake was high (both more than 90%) and infant HIV‐1 infection risk was low, reflecting high PMTCT coverage. Investment in health systems to deliver HIV‐1 testing and antiretrovirals can effectively prevent infant HIV‐1 infection despite substantial HIV‐1 stigma.
Effect of the Accountable Care Act of 2010 on Clinical Trial Insurance Coverage
Authors: Kircher Sheetal M. , Benson Al B. , Farber Matthew , Nimeiri Halla S.
Published: December 2011

Purpose

The Affordable Care Act (ACA) of 2010 implemented dramatic changes in our health care system. The new law requires that insurers and health plans provide coverage for individuals participating in clinical trials. Currently, there are states that already have laws or agreements requiring clinical trial coverage, but there remain deficiencies that will need to be addressed to achieve compliance with the new law.

Methods

State mandates were reviewed to determine current laws and agreements. The ACA was reviewed to outline its provisions, and these were compared with current mandates to identify deficiencies.

Results

Eighteen states meet the requirements set forth by the ACA either through a state law or agreement; 33 states do not meet the requirements. Of these 33 states, 15 do not have any existing laws or agreements in place regarding clinical trials. In states that have deficient policies in place, the most common deficiency is the lack of phase I coverage. The second most common deficiency in policy is coverage of only therapeutic studies.

Conclusion

Most states currently do not meet the requirements of the ACA and will be required to make changes by 2014. The implications of the ACA with regard to insurance coverage of clinical trials remain unclear as implementation of the legislation unfolds. State governments can take steps to ensure insurance coverage by creating and expanding agreements with insurance companies.
Design, Optimization and Analysis of Hydraulic Soft Yaw System for 5 MW Wind Turbine
Authors: Stubkier Søren , Pedersen Henrik C.
Published: December 2011

As wind turbines increase in size and the demands for lifetime also increases, new methods of load reduction needs to be examined. One method is to make the yaw system of the turbine soft/flexible and hence dampen the loads to the system, which is the focus of the current paper. The paper first presents work previous done on this subject with focus on hydraulic yaw systems.

By utilizing the HAWC2 aeroelastic code and an extended model of the NREL 5MW turbine combined with a simplified linear model of the turbine, the parameters of the soft yaw system are optimized. Results show that a significant reduction in fatigue and extreme loads to the yaw system and rotor shaft are possible, when utilizing the soft yaw drive concept compared to the original stiff yaw system. The physical demands of the hydraulic yaw system are furthermore examined for a life time of 20 years. The duty cycles, based on the extrapolated loads, show that it is possible to construct a hydraulic soft yaw system, which is able to reduce the loads on the wind turbine significantly.
Offshore Wind Turbine Blade Coating Deterioration Maintenance Model
Authors: Andrawus Jesse A , Mackay Laurie
Published: December 2011

Maintenance of offshore wind turbine blades has significant impact on the overall cost of managing offshore wind farms. Effective maintenance of protective coatings of wind turbine blades is one of the key challenges of offshore wind farms given that the current condition monitoring systems for wind turbines are limited in detecting coating deterioration. The durability and adhesion of coatings are affected by varying complex offshore weather conditions. This impact is further aggravated as access to offshore wind farms are costly and weather dependent. In this paper an effective predictive maintenance strategy for protective coating of wind turbine blades is developed. The strategy is based on risk analysis approach and coating codes for offshore installations. Practical implementation of the developed strategy will significantly reduces the overall maintenance cost of offshore wind farms.
Study on Control Concepts Suitable for Mitigation of Loads from Misaligned Wind and Waves on Offshore Wind Turbines Supported on Monopiles
Authors: Fischer Tim , Rainey Patrick , Bossanyi Ervin , Kühn Martin
Published: December 2011

For current offshore wind farms, monopiles are by far the most popular support structure type. However, for deeper water and/or larger turbines, the fatigue loading is becoming critical and the monopile dimensions are exceeding the current economical feasibility. Especially in cases of misaligned wind and waves, the side-to-side fatigue loading at the support structure can become a design driver. Since the industry aims to use standardized rotor-nacelle-assembly (RNA) designs, the goal of this paper is to show the effectiveness of using the RNA as adjustable controller device for site-specific offshore support structure configurations by using active control devices.
A Passive System for Optimising Battery Charging using a Permanent Magnet, Variable Speed Generator
Authors: Shiota Takashi , Isaka Tsutomu , Seki Kazuichi , Ushiyama Izumi
Published: December 2011

The performance of a permanent magnet, variable speed generator charging a battery via a PWM converter or rectifier is considered. It is found that in neither case can the system be configured to generate electricity at low wind speeds while maintaining optimum efficiency at rated wind speed. Accordingly, an alternative system which permits operation at close to optimum efficiency over the full range of wind speeds below rated is proposed. This uses two separate generator windings, one of which begins to charge the battery at a much lower wind speed than the other. Experimental results are presented which confirm the theoretical analysis.
Correlating a High-Lift Airfoil Performance with Turbulence Strain Rate
Authors: Cao N. , Ting D. S-K. , Carriveau R.
Published: December 2011

The performance of a high-lift airfoil (S1223) has been correlated to the free-stream turbulence strain rate at Reynolds numbers Re = 55,000, 75,000 and 100,000 in a wind tunnel. A comprehensive examination of the lift/drag data, wake velocity deficits, wake turbulence level and power density spectra revealed that the flow patterns above and below the airfoil are significantly altered and the boundary layer separation is delayed to higher angles of attack with increasing turbulence strain rate. That is to say, high straining turbulent wind tends to improve the airfoil performance by suppressing the stall and lowering the drag, at a small cost of a marginally reduced maximum lift coefficient.
Numerical Study of Atmospheric Ice Accretion on Various Geometric Cross-Sections
Authors: Muhammad S. Virk
Published: December 2011

This paper describes the numerical study of atmospheric ice accretion on four different geometric cross sections, circular, parabola, triangle and cube. Most structures are the combination of these four basic geometric cross sections. Understanding of the atmospheric ice accretion physics on these will provide a base for further analyses of ice accretion and its effects on complex structures. CFD based numerical analyses are carried out in this research work to understand the rate and shape of atmospheric ice growth on these cross sections. For constant wind speed and atmospheric temperature, the ice growth is simulated as function of time, where more ice accretion is found on cube as compared to three other cross sections. Parametric study to understand the effect of iced surface roughness showed a significant difference in ice growth, when compared with the case, where no surface roughness was assumed on the cross sections.
Formulation of an Operation Theory for Wind-Generators with Controlled Variable Speed-Ratio
Authors: Siddig Mohammed Hashim
Published: December 2011

The basic variables relevant to wind generation systems were formulated in this study as to relate the operational torque coefficient to the power output and wind velocity. A dimensionless number connecting wind velocity, power output, generator speed, turbine size and air density was identified and shown to be the pivotal independent parameter of the wind-generator operation.

An optimization criterion based on this mathematical formulation was developed. It relates the gearbox's speed-ratio to the newly defined wind generator number. This led, in turn, to the introduction of a variable speed-ratio gearbox that has a constant speed output and a variable turbine shaft-speed to be controlled in such a way as to match continuously and optimally the operation condition.

Making use of a reported experimental study of a variable pitch-angle turbine driving an induction generator, a demonstration of the design procedure was presented. The model was shown to accurately predict the experimentally produced results. The demonstration proceeded to predict the optimum performance for the reported system.
Blasius Boundary Layer Perturbation for Optimal Wind Rotor
Authors: Farthing S.P.
Published: December 2011

Flow on the lee side of wind turbines has been assumed to be helical, with swirl constrained by a pressure increase with radius. This would imply secondary flow into the axis in the blade boundary layer with the heavy swirl optimal at low speed ratios. But in the DTU wind tunnel, tufts on the BEM optimal torque wind stator did not show secondary flow. In fact the straight smoke trails observed behind the stator imply uniform pressure. For BEM optimal and practicable rotors, the interference increases with local speed ratio so the pressure on the lee side actually decreases with radius. In the limit of high speed ratio the pressure gradient again vanishes and the difference between Coriolis and curvilinear secondary forcing terms is a simple function of the apparent wind. Using this function for all speed ratios avoids any pressure gradient and secondary flow towards the axis. The universal profile of such approximated secondary flow and its effect on the chordwise boundary layer are studied as perturbations of the Blasius flat plate layer for Glauert's BEM optimal rotor.
A Multi-Wave-Packets Decomposition Algorithm of Vibration Signal
Authors: Ye Qingwei , Zhou Yu , Wang Xiaodong
Published: December 2011

From the perspective of mechanic wave propagation, a new approach to decompose a vibration signal is proposed in this paper. Define a series wave-packet mode functions, think a vibration signal of the sensor correcting is many resonance wave-packets linear super-position after propagation, reflection, diffraction and dispersion. The multi-wave-packets mode decomposition algorithm of vibration signal mainly includes two parts, that is, wave-packet center detection and extraction of wave-packet parameters. Assume the resonance wave-packet center signal value is maximum in the local time-frame, each possible wave-packet center mode fitting is done with an additional-window sliding manner, at the same time, corresponding to parameters are extracted. These parameters represent every mechanical fluctuation of the sensor collecting. Meanwhile, they can recover the signal better and provide many characteristics for signal detection and fault diagnosis. By applying the algorithm to the In-line vibration inspection of anchor screws in light rail, it has been proven that the wave-packet mode parameters obtained from the algorithm is very useful for connection looseness testing and fault diagnosis.
The Noise Analysis for Draft Tube of Turbine
Authors: Wei Dehua , Zhao Weiguo
Published: December 2011

We take the field test data from the entrance to the draft tube of the turbine of a hydropower station as an example, the signals acquired are depicted in time domain and frequency spectrum, and the relation between the noise and the load is analyzed, then we find out the reasons which cause noise and put forward the measures for noise elimination. After analyzing the noise signals of the draft tube under different loads, the experimental results show that when the unit operates in load 19MW - 80MW and 138MW - 179MW, the noise is much larger than usual, the abnormal noise is mainly caused by the hydraulic pressure fluctuation of draft tube, the best way to eliminate the noise is the reasonable air compensation for the draft tube.
Experimental Study on the Performance of Constrained Damped Rail Vibration Reduction
Authors: Liu L.Y. , Li J.Y. , Yin X.J.
Published: December 2011

To study the vibration reduction performance of damped rail, we take the standard rail and labyrinth constrained damped rail as the study target. By testing the vibration performance of both standard rail and labyrinth constrained damped rail in an anechoic room, we use the time-domain analysis to study the vibration changes with time passing. The results showed that: the labyrinth constrained damped rail vibration can effectively reduce the vibration amplitude and duration. Under the radial impact load, compared to the standard rail, vibration acceleration attenuation of the labyrinth constrained damped rail is 5% −19%, time of vibration and attenuation greater than 94%; under the axial impact load, compared to the standard rail, vibration acceleration attenuation of the labyrinth constrained damped rail is 9% −21%, time of vibration and attenuation greater than 92%. The results have provided an experimental basis for the design of new constrained damped rail.
Torsional Vibration Dynamic Analysis of the Test Rig for Intersecting Axes Gears of Helicopters
Authors: Jin Xiangyang , Xian Li Gui , Qiang Zhao Yong
Published: December 2011

In this paper, the transfer matrix method has been employed to analyze the torsional vibration dynamics of the test rig for closed intersecting axes beveloid gears of helicopter. The torsional vibration dynamic model has been established through adopting the transfer matrix method. At the same time, the mathematical model of the branch nodes and the dynamic analysis of test rig closed system have been also derived. The dynamic simulation principle of the test rig is studied and the corresponding dynamic load coefficients are also solved. Finally, the simulation curve of the vibration load coefficients of the test gears under different speed is drawn. The results shows that both the dynamic character of test rig and the loading precision can meet the test requirement.
Modeling and Simulation Study on Crosswind Stability of the High-Speed Bus
Authors: Dong-chen Qin , Yi-cun Xu , Qiang Zhu , Li Yu
Published: December 2011

Based on multi-body system dynamics, the model of Yutong high-speed bus was built by ADAMS/Car software to analyse the influence of crosswind on the high-speed bus' handing stability. Seven discrete wind pressure centers effects on the chasis were taken into account, so the crosswind model with a shifting pressure center was achieved. After improving the standard of the crosswind sensitivity test that is prescribed by American ESV (Experimental safety vehicle), the crosswind simulation tests with pressure center's shift and the immobile pressure center were carried out. The high-speed straight-line simulation test without the crosswind was also completed. By comparing the results of the three tests, the test data in consideration of wind pressure center's shift was more reasonable and provided the reference data for improving the crosswind stability of the bus.
A Study on Surge and Stall under the Interaction of Parallel Axial flow fan in Tunnel
Authors: Chun Guo , Mingnian Wang , Zhaozhi Tang
Published: December 2011

In the ventilation design for tunnels above 10km, an axial flow fan of great power needs to be set in ventilation shafts. There are few provisions on the setting modes and less discussion of parallel axial flow fan mode in the Specifications for Design of Ventilation and Lighting of Highway Tunnels. All of these bring a lot of difficulties about the axial fan selection, layout and control design. There is no specialized research on axial flow fan for tunnels and no studies on surge and stall under the interaction of parallel axial flow fan in tunnel in spite of the more and more application of parallel axial flow fan. So, this paper conducts a study on surge and stall under the interaction of parallel axial flow fan in tunnels. Through the study on the operating principle and analysis of parallel axial flow fan, we can know that the noise will increase suddenly, which will in turn result in fan vibration and running instability once the stall occurs. When a fan surges, the air volume and pressure, the motor current will fluctuate sharply, which brings significantly increased vibration and noise. At the same time, the rotary blade and the shell are subject to considerable stress effects and the fan will possibly suffer from great damage. The surge will occur in the unstable zone of axial fan performance curve. The strong pulsation and periodic oscillation of the air flow will increase the noise, which is a serious damage to the fan. So an axial fan should avoid this zone in running. With two axial flow fans of the same power parallel, the mutual influence is not very great. Therefore this research will focus on the efficiency in the case of two fans with a high and a low power parallel. Stall will occur if the outside pressure is greater than the outlet pressure. Once the stall happens, the noise will increase suddenly, which will in turn result in fan vibration and running instability. When two fans parallel, i.e. when the power ratio of the parallel fans is over 5.3, the possibility of the small fan's stall is high, otherwise it is small. With regard to the running efficiency of parallel axial flow fans and the starting safety, it is better to parallel two fans, and the fans with adjustable movable vanes or frequency control or the ordinary nonadjustable fans can be used.
Temperature Estimates from Models and Observations
Authors: Symmons Philip
Published: December 2011

Seventy estimates of annual global mean near-surface temperature from models have been compared with an estimate from observations, for the period 1959–1999. Correlations coefficients ranged from 0.35 to 0.85. Only 3 were better than the correlation with the level of atmospheric carbon dioxide. That suggests that the fluctuations of model values do not mirror “natural variation”, a conclusion reinforced by the lack of association between one year's estimate and that for the previous year from observation, with that from models. Regression slopes of observation on model ranged from 0.26 to 1.16; that does not constitute strong support for the “green-house gas” explanation of global warming. Model outputs can be modified to predict global temperatures but then the model output is logically no different from the empirical relationship with atmospheric carbon dioxide, which is as good as the best of the models and is transparent.
Atmospheric Ice Accretion on Non-Rotating Circular Cylinder
Authors: Virk Muhammad S.
Published: December 2011

Numerical study of atmospheric ice accretion on a non-rotating circular cylinder was carried out at dry rime ice conditions. To validate the numerical model, results were compared with the experimental data obtained from CIGELE atmospheric icing research wind tunnel (CAIRWT). A good agreement was found between experimental and numerical results. Numerical study showed that selection of appropriate numerical model of ice density and droplet size distribution is important, as these can significantly varies the simulated ice growth. Parametric study at different air flow velocities and angles showed a significant change in ice accretion on circular cylinder. This research work provides a useful base for further numerical investigation of atmospheric ice accretion on circular power network cables installed in the cold regions like arctic and alpine.
Large-Scale Fire Test of Unprotected Cellular Beam Acting in Membrane Action
Authors: Vassart Olivier , Bailey C. , Hawes M. , Nadjai A. , Simms W. , Zhao B. , Gernay T. , Franssen J.-M.
Published: December 2011

This paper describes a full scale fire test performed the 27th of February 2010 on a composite floor for analysing the possibility of tensile membrane action to develop when the unprotected steel beams in the central part of the floor are made of cellular beams. The natural fire was created by a wood crib fire load of 700 MJ/m2 and the 9 × 15 m floor survived the fire that peaked at 1000°C and lasted for 90 minutes. Blind predictions of the air temperature development by the software OZone and of the structural behaviour by the software SAFIR which proved quite satisfactory are also described.
Mechanical Behavior of Polycarbonate Circular Honeycombs under in-Plane Biaxial Compression
Authors: Yu T.X. , Gao Z.Y. , Hu L.L.
Published: December 2011

In-plane equi-biaxial compression tests were conducted quasistatically on polycarbonate circular honeycombs in a conventional universal testing machine with a specially designed test rig. In view of the complex characteristics of the deformation in a honeycomb block under biaxial compression, the focus was put on the initiation and evolution of deformation inhomogeneity. An inhomogeneity index, Iinh, is defined as a function of the overall compression of a sample to quantify the severity of the deformation inhomogeneity of the honeycomb block; and it facilitates quantitative comparisons among the results under various loading conditions. To examine the role of the friction between the honeycomb sample and the test rig, and to explore the effect of dynamic loading, finite element analysis is carried out to simulate the collapse process of a circular honeycomb block under equi-biaxial compression. The numerical simulation also reveals the transition from a global collapse mode (although inhomogeneous) to a progressive collapse mode at a critical loading velocity, which is further studied by the wave trapping theory.
Dynamic Responses of Sandwich Beams with Gradient-Density Aluminum Foam Cores
Authors: Zhang J. , Zhao G. P. , Lu T. J.
Published: December 2011

The dynamic responses of end-clamped sandwich beams comprised of aluminum face sheets and close-celled aluminum foam cores are numerically simulated by loading the beams at mid-span. Three types of aluminum foam core having identical areal density are considered: homogeneous core, low-high gradient-density core, and high-low gradient-density core. Two-dimensional (2D) finite element (FE) models are created from tomographic images of the foam, which represent the cell shape and geometric distribution of real foams fabricated using the powder metallurgy foaming technique with blowing agents. To determine the mechanical properties of cell wall material, the numerically predicted uniaxial stress versus strain curve for homogeneous aluminum foam is fitted to that measured experimentally. The shock impulse is simulated using a uniformly distributed pressure versus time history. Depending upon the initial impulse applied, it is demonstrated that the deformation and deflection of the sandwich beam can be either bend or stretch dominated. Within the bend dominated domain, the foam-cored sandwich beams outperform monolithic solid beams of equal mass. However, the benefits diminish as the response of the sandwich becomes stretch dominated. Whilst the sandwich beam with homogeneous foam core shows the smallest mid-span deflection of its back facesheet, that with low-high gradient-density core achieves the largest average compressive strain and absorbs the most internal energy.
The Response of Sandwich Panels Made of Thin-Walled Tubes Subjected to Axial Load
Authors: Yuen S. Chung Kim , Nurick G. N. , Witbeen H. L.
Published: December 2011

This paper presents the results of experimental and numerical work on the response of sandwich panels made of thin-walled tubes and mild steel plates to axial loading. The core of the sandwich panels consists of mild-steel square tubes, 20×20×0.9 mm in cross-section, in three different layouts comprising of four or five or nine tubes, (panels A, B and C respectively). Three tube configurations are investigated, as–received tubes, tubes with circular cut-out on opposite sides, and tubes with dents on opposite sides. The imperfections are located at the mid-section of the tube. The outer skin of the sandwich panel is 150×150×10 mm in cross-section and non-deformable. Quasi-static tests carried out on two and three tubes laid out in parallel between the skin indicate that the axial forces is a multiple of the axial force of a single tube, as expected. Consequently, the sandwich panel with the nine tubes deforms less than the sandwich panels with five and four tubes when subjected to similar impact energy. Triggers in the tubes improve the collapse mode of the sandwich panels. The Finite Element package ABAQUS/Explicit v6.7 is used to construct a ¼ symmetry model using shell elements to simulate the response of the sandwich panels to dynamic axial load. The Finite element simulations, validated using high speed photography footage, show good correlations with experiments.
Numerical Analysis of Metallic Foam Using Microstructure Model
Authors: Wu Chengqing , Yu Ling , Zhou Yun
Published: December 2011

It has become a critical issue that the human life and civil facility have been threatened by the increasing terroristic explosive attack. The application of cellular materials is an effective and feasible measure to mitigate blast and impact loading on buildings due to their energy absorption capacity. The Finite Element code such as LSDYNA has been used to simulate the mechanical behaviours of cellular materials. However, most of numerical models regarded the cellular materials as homogeneous materials on the macro level which may affect the accuracy of simulation, because none of them can reflect the pore structure of cellular materials, especially for the irregular metallic foam structures. Therefore, in this study, two main microstructure models (2D/3D metallic foam) were developed for numerical simulation of closed-cell metal. In the microstructure model of metallic foam, the cell walls were represented by thin shell elements and the solid wall material of the cells is modelled as bi-linear stress-strain relationship based on the material properties of the cell wall material of metallic foam. The numerical models were validated through comparing simulated results with analytical values of plateau phase stress-strain response under static condition. With the validated microstructure models, a series of parametric studies were conducted, in order to have a better understanding about the mechanical properties of closed-cell metallic foam. The emphases of this study were on the differences between static and dynamic performances of closed-cell metallic foam specimens in both 2D and 3D cases, the relationship between dynamic increase factor and nominal strain rate.
Dynamic Test and Constitutive Model of 225 MPa Low Yield Point Steel Material and its Energy Absorption Ability
Authors: Zhang Chunwei
Published: December 2011

Based on Low Yield Point (LYP) steel's attractive features, e.g. relative lower yielding strength, better plasticity performance than traditional structural steel material, the feasibility of utilizing LYP steel material for absorbing blast and impact/shock energy through its plastic deformation is discussed in this paper. Selected 225 MPa class LYP steels made by Chinese An Gang Corp., abbreviated as AQ225, are tested via quasi-static and split Hopkinson pressure bar (SHPB) experiments, respectively. Then, Johnson-Cook dynamic constitutive model is developed through a comprehensive thorough processing of raw test data. Moreover, the reliability of achieved model and its corresponding parameters are discussed. Finally, the dynamic response of a square plate structure made of LYP steel as well as other different types of steel materials, e.g. high-strength HQ600 and normal high-strength low alloy steel Q345, subject to explosive loading is studied through numerical simulations. As a result, the advantages of LYP steel for absorbing blast and impact energy through the accumulated plastic deformation are demonstrated, which provides the basis of utilizing such material for protective structures.