bluuebunny/crossref_metadata_2025 huggingface dataset:
Central nervous system infection withAcanthamoebain a malnourished child
Authors: Khurana Sumeeta , Mewara Abhishek , Verma Sanjay , Totadri Siddharth K
Published: October 2012

A 3-year-old male child presented with moderate-to-high grade fever and non-projectile vomiting, generalised seizures and altered sensorium for 1 month. CT scan revealed a communicating hydrocephalus with no basal exudates. The microbiological tests were negative forStreptococcus pneumoniae,Haemophilus influenzae,Neisseria meningitides, brucellosis, cryptococcosis, HIV andMycobacterium tuberculosis. Intracranial pressure was relieved by ventriculo-peritoneal shunt, and the child was empirically started on ceftriaxone, and antitubercular therapy with isoniazid, rifampicin, ethambutol and streptomycin, along with steroids and supportive treatment for seizures. The symptoms persisted. On further investigation the cerebrospinal fluid showed growth ofAcanthamoebaspp., following which the initial treatment was stopped and a combination antiamoebic regimen of cotrimoxazole, rifampicin and ketoconazole was started, after which he showed clinical improvement. The treatment was continued for 6 months and on follow-up at 1, 3 and 6 months, there was a remarkable clinical improvement with no residual symptoms.
The endurance athletes heart: acute stress and chronic adaptation
Authors: George Keith , Whyte Greg P , Green Danny J , Oxborough David , Shave Rob E , Gaze David , Somauroo John
Published: October 2012

The impact of endurance exercise training on the heart has received significant research and clinical attention for well over a century. Despite this, many issues remain controversial and clinical interpretation can be complex of biomarkers of cardiomyocyte insult. This review assesses the current state of knowledge related to two areas of research where problems with clinical decision making may arise: (1) the impact of chronic endurance exercise training on cardiac structure, function and electrical activity to the point where the athletic heart phenotype may be similar to the expression of some cardiac pathologies (a diagnostic dilemma referred to as the ‘grey-zone’) and (2) the impact of acute bouts of prolonged exercise on cardiac function and the presentation of biomarkers and cardiomyocyte insult in the circulatory system. The combination of acute endurance exercise stress on the heart and prolonged periods of training are considered together in the final section.
Atrial fibrillation and atrial flutter in athletes
Authors: Calvo Naiara , Brugada Josep , Sitges Marta , Mont Lluís
Published: October 2012

Atrial fibrillation (AF) is the most common arrhythmia in clinical practice, with an estimated prevalence of 0.4% to 1% in the general population, increasing with age to 8% in those above 80 years. The recognised risk factors for developing AF include age, structural heart disease, hypertension, diabetes mellitus or hyperthyroidism. However, the mechanisms underlying the initiation of AF in patients below 60 years of age, in whom no cardiovascular disease or any other known causal factor is present, remain to be clarified. This condition, termed as lone AF, may be responsible for as many as 30% of patients with paroxysmal AF seeking medical attention. Recent studies suggest that long-term endurance exercise may increase the incidence of AF and atrial flutter (AFl) in this population. This review article is intended to analyse the prevalence of AF and AFl, the pathophysiological mechanisms responsible for the association between endurance sport practice and AF or AFl and the recommended therapeutic options in endurance athletes.
Performance enhancing drug abuse and cardiovascular risk in athletes: implications for the clinician
Authors: Angell Peter J , Chester Neil , Sculthorpe Nick , Whyte Greg , George Keith , Somauroo John
Published: October 2012

The use of performance-enhancing and social drugs by athletes raises a number of ethical and health concerns. The World Anti-Doping Agency was constituted to address both of these issues as well as publishing a list of, and testing for, banned substances in athletes. Despite continuing methodological developments to detect drug use and associated punishments for positive dope tests, there are still many athletes who choose to use performance and image enhancing drugs. Of primary concern to this review are the health consequences of drug use by athletes. For such a large topic we must put in place delimitations. Specifically, we will address current knowledge, controversies and emerging evidence in relation to cardiovascular (CV) health of athletes taking drugs. Further, we delimit our discussion to the CV consequences of anabolic steroids and stimulant (including amphetamines and cocaine) use. These drugs are reported in the majority of adverse findings in athlete drug screenings and thus are more likely to be relevant to the healthcare professionals responsible for the well-being of athletes. In detailing CV health issues related to anabolic steroid and stimulant abuse by athletes we critique current research evidence, present exemplar case studies and suggest important avenues for on-going research. Specifically we prompt the need for awareness of clinical staff when assessing the potential CV consequences of drug use in athletes.
Advising a cardiac disease gene positive yet phenotype negative or borderline abnormal athlete: Is sporting disqualification really necessary?
Authors: Richard Pascale , Denjoy Isabelle , Fressart Véronique , Wilson Mathew G. , Carré François , Charron Philippe
Published: October 2012

The sudden cardiac death (SCD) of an athlete is a rare and tragic event, often caused by a number of inherited heart muscle disorders, namely the cardiomyopathies and primary arrhythmia syndromes (also known as cardiac ion channelopathies). Recent advances in the understanding of the molecular genetics of these heritable cardiovascular diseases present new challenges for clinicians who manage athletes with these types of heart muscle conditions. Unfortunately, the clinical heterogeneity of many of these SCD diseases are also matched by the genotypic heterogeneity associated with the pathogenesis of the disease. A particularly challenging situation arises when the sports physician and attending cardiologist are presented with an athlete who demonstrates a familial context of inherited cardiac disease or presents mild cardiac abnormalities suggestive of inherited cardiac disease. Alongside the complete cardiac evaluation, genetic testing may be proposed as an additional diagnostic tool in this clinical conundrum. However, debate still remains on how extensive the screening should be, in particular the use and interpretation of genetic testing in that setting. The aim of this review is to examine the role of genetic testing within the diagnostic algorithm of preparticipation screening of athletes. This will be achieved by providing the sports medicine physician with simple current cardiac genetic knowledge for the main inherited cardiac conditions known to cause SCD. Furthermore, it will examine current knowledge for the role of genetic testing upon the prediction of SCD, concluding with its impact on the sport eligibility and disqualification conundrum using case examples from our genetic testing laboratory.
Assessing the effect of regional deprivation on mortality avoiding compositional bias: a natural experiment
Authors: Reiss Katharina , Berger Ursula , Winkler Volker , Voigtländer Sven , Becher Heiko , Razum Oliver
Published: October 2012

Background and objective

We assessed the effect of regional deprivation on individual mortality by making use of a natural experiment: we followed up ethnic German resettlers from Former Soviet Union countries who were quasi-randomly distributed across the socioeconomically heterogeneous counties of Germany's federal state North Rhine-Westphalia (NRW).

Methods

We used data from the retrospective cohort study ‘AMOR’ on the mortality of resettlers in NRW (n=34 393). Based on the postcode of the last known residence we linked study participants to the 54 counties of NRW, which were aggregated in six deprivation clusters. Mortality rates and standardised mortality ratios (SMRs) were calculated for each cluster. After a mean follow-up of 10 years, 2580 resettlers were deceased.

Results

For male and female cohort members, mortality rates and SMRs were highest in the cluster ‘poverty poles’ (SMR men: 1.21, 95% CI 1.04 to 1.41; SMR women: 1.17, 95% CI 0.99 to 1.37), whereas they were lowest in the cluster ‘prospering regions and suburban counties’ (SMR women: 0.86, 95% CI 0.70 to 1.05) as well as in the cluster ‘heterogeneous counties’ (SMR men: 0.73, 95% CI 0.61 to 0.88).

Conclusions

The population which was quasi-randomly distributed to counties of differing socioeconomic status experienced different levels of mortality. It was highest in regions with the highest level of regional deprivation. Previous studies describing this positive relationship between mortality and regional deprivation could not differentiate between compositional and contextual effects. Thus, our findings indicate that in terms of mortality, regional deprivation does matter.
Comparison of self-obtained penile-meatal swabs to urine for the detection ofC. trachomatis,N. gonorrhoeaeandT. vaginalis
Authors: Dize Laura , Agreda Patricia , Quinn Nicole , Barnes Mathilda R , Hsieh Yu-Hsiang , Gaydos Charlotte A
Published: October 2012

Background

Self-obtained penile-meatal swabs and urine specimens have been used forChlamydia trachomatis(CT),Neisseria gonorrhoeae(NG) andTrichomonas vaginalis(TV) for outreach screening in men.

Objective

To compare the sensitivity of self-collected male penile-meatal swabs and urine for the detection ofCT,NGandTV.

Methods

Matching penile-meatal swabs and urines were collected at home after recruitment to the study; via the internet programme,http://www.iwantthekit.org. The instructions directed the participant to place the tip of a Copan flocked swab at the meatal opening of the urethra to collect the penile-meatal sample. Two ml of urine was collected after the swab onto a Copan sponge-on-a-shaft collection device. Both swab and urine were placed into individual Aptima transport media tubes and mailed to the laboratory for testing. All specimens were tested for CT and NG using the GenProbe Aptima Combo2 Assay and for TV using GenProbe Aptima Analyte Specific Reagents with TV oligonucleotides.

Results

Of 634 men, 86 (13.6%) were positive for CT, 9 (1.4%) were positive for NG and 56 (9.3%) positive for TV. For CT, swab sensitivity was 81/86 (94.2%), and urine sensitivity was 66/86 (76.7%). For NG, swab sensitivity was 9/9 (100%) and urine sensitivity was 8/9 (88.9%). For TV, swab sensitivity was 45/56 (80.4%) and urine sensitivity was 22/56 (39.3%).

Conclusions

Self-obtained penile-meatal swabs provided for the detection of more CT, NG and TV, than urine specimens.
Systemic or intrasynovial medication as singular or as combination treatment in horses with (peri‐)synovial pain
Authors: Brommer H. , Schipper P. , Barneveld A. , van Weeren P. R.
Published: October 2012

Records of lame horses (2004–2007) with (peri‐)synovial pain of the metacarpophalangeal joint (MCPJ, n=53), digital flexor tendon sheath (DFTS, n=20), and distal interphalangeal joint (DIPJ, n=31) were evaluated (n=104). Cases were grouped according to the following treatments: (1) systemic administration of NSAIDs (n=40); (2) intrasynovial administration of glucocorticosteroids (n=30); (3) combination treatment (n=34). Outcome was defined as successful when the owner reported that the horse had returned to its previous level of performance within a period of up to six months after treatment. Statistical evaluation was performed using Fisher's Exact tests and multivariable logistic regression analyses at P < 0.05. Successful outcome was significantly higher for horses in treatment group 3 (19/34, 55.9 per cent, P=0.021) than in treatment groups 1 (11/40, 27.5 per cent, OR 0.21, 95 per cent CI 0.06 to 0.71) and 2 (8/30, 26.6 per cent, OR 0.18, 95 per cent CI 0.06 to 0.56). A significant association was only found with regard to the affected synovial structure (P=0.025); relative to the DIPJ, involvement of the MCPJ and DFTS was four to five times more likely to provide a successful outcome (OR 4.18 and 5.59, 95 per cent CI 1.24 to 14.08 and 1.42–22.22, respectively).
LOCATING SUGAR CANE LOADING STATIONS UNDER VARIATIONS IN CANE SUPPLY
Authors: PATHUMNAKUL SUPACHAI , SANMUANG CHATKLAO , EUA-ANANT NAWAPAK , PIEWTHONGNGAM KULLAPAPRUK
Published: October 2012

This study addresses the problem of locating sugar cane loading stations and allocating cane fields to those stations. The problem is different from the general location–allocation problem in so far as this framework takes into account the different maturity periods of each cane field. If the loading station is improperly located, it can result in high transportation costs from cane fields to the station and significant fluctuations in the station utilization rate. A modification of the well-known "fuzzy c-means" (FCM) method, which takes into account both the cane supply and the different cane maturity periods, is proposed to solve this problem. The objective of the model is to minimize the sum of the transportation and station utilization costs. The performance of this method is compared to that of the traditional FCM method. The results show that the proposed approach is practical for solving the problem and that it provides a better solution than the FCM method.
TWO APPROXIMATION SCHEMES FOR SCHEDULING ON PARALLEL MACHINES UNDER A GRADE OF SERVICE PROVISION
Authors: LI WEIDONG , LI JIANPING , ZHANG TONGQUAN
Published: October 2012

We consider the offline scheduling problem to minimize the makespan on m parallel and identical machines with certain features. Each job and machine are labeled with the grade of service (GoS) levels, and each job can only be executed on the machine whose GoS level is no more than that of the job. In this paper, we present an efficient polynomial-time approximation scheme (EPTAS) with running time O(n log n) for the special case where the GoS level is either 1 or 2. This partially solves an open problem posed in (Ou et al., 2008). We also present a simpler full polynomial-time approximation scheme (FPTAS) with running time O(n) for the case where the number of machines is fixed.
MOMENTUM FRACTIONS OF QUARKS AND GLUONS IN A SELF-SIMILARITY BASED MODEL OF PROTON
Authors: JAHAN A. , CHOUDHURY D. K.
Published: October 2012

In this paper, we use momentum sum rule to compute the fractions of momentum carried by quarks and gluons in a self-similarity based model of proton. Comparison of the results with the prediction of QCD asymptotics is also made.
ANALYSIS OF THE RADIATIVE DECAYS AMONG THE BOTTOMONIUM STATES
Authors: WANG ZHI-GANG
Published: October 2012

In this paper, we perform an systematic study of the radiative transitions among the bottomonium states using the heavy quarkonium effective Lagrangians, and make predictions for the ratios among the radiative decay widths of a special multiplet to another multiplet. The predictions can be confronted with the experimental data in the future.
EXACT ABJM PARTITION FUNCTION FROM TBA
Authors: PUTROV PAVEL , YAMAZAKI MASAHITO
Published: October 2012

We report on the exact computation of the S3 partition function of U (N)k × U (N)-k ABJM theory for k = 1, N = 1, …, 19. The result is a polynomial in π-1 with rational coefficients. As an application of our results, we numerically determine the coefficient of the membrane 1-instanton correction to the partition function.
THE HOLOGRAPHIC SCENARIO, THE MODIFIED INERTIA AND THE DYNAMICS OF THE UNIVERSE
Authors: GINÉ JAUME
Published: October 2012

This paper attempts to connect two new gravitational mechanisms: the Verlinde's holographic model of gravity and the modification of inertia resulting from a Hubble-scale Casimir effect (MiHsC) of McCulloch. First we give a short survey about how the holographic scenario can give the correct dynamics of the universe. The introduction of a two-holographic screens one comparable to the Hubble horizon and a second screen that takes into account the contribution of all the matter between the test particle and the observer gives directly the modified Friedmann acceleration equation for the dynamical evolution of the universe. Improvements of this equation using the quantum corrections will realize the inflation at high energy scales and the late-time acceleration (i.e. the accelerated expansion of the universe nowadays) obviating the dark energy. From both models we can derive a version of Modified Newtonian Dynamics (MOND) observed in the dynamics of the astronomical objects obviating the dark matter and explaining other astronomical anomalies. A first connection between both theories is given at the end of the paper.
QUANTUM STATES OF THE SPACETIME, AND FORMATION OF BLACK HOLES IN AdS
Authors: CANTCHEFF MARCELO BOTTA
Published: October 2012

We argue that a nonperturbative description of quantum gravity should involve two (noninteracting) copies of a dual field theory on the boundary, and describe the states of the spacetimes accordingly. So, for instance, a complete description of the asymptotically Anti-de-Sitter (AdS) spacetimes is given by two copies of the conformal field theory (CFT) associated to the global AdS spacetime. We also argue that, in this context, gravitational collapse and formation of a black hole may be described by unitary evolution of the dual nonperturbative degrees of freedom.
GRAVITY'S WEIGHT ON WORLDLINE FUZZINESS
Authors: AMELINO-CAMELIA GIOVANNI , ASTUTI VALERIO , ROSATI GIACOMO
Published: October 2012

We investigate a connection between recent results in three-dimensional (3D) quantum gravity, providing an effective noncommutative-spacetime description, and some earlier heuristic descriptions of a quantum-gravity contribution to the fuzziness of the worldlines of particles. We show that 3D-gravity-inspired spacetime noncommutativity reflects some of the features suggested by previous heuristic arguments. Most notably, gravity-induced worldline fuzziness, while irrelevantly small on terrestrial scales, could be observably large for propagation of particles over cosmological distances.
INTERACTION OF VECTOR MESONS WITH BARYONS AND NUCLEI
Authors: OSET E. , RAMOS A. , GARZON E. J. , MOLINA R. , TOLOS L. , XIAO C. W. , WU J. J. , ZOU B. S.
Published: October 2012

After some short introductory remarks on particular issues on the vector mesons in nuclei, in this paper, we present a short review of recent developments concerning the interaction of vector mesons with baryons and with nuclei from a modern perspective using the local hidden gauge formalism for the interaction of vector mesons. We present results for the vector–baryon interaction and in particular for the resonances which appear as composite states, dynamically generated from the interaction of vector mesons with baryons, taking also the mixing of these states with pseudoscalars and baryons into account. We then venture into the charm sector, reporting on hidden charm baryon states around 4400 MeV, generated from the interaction of vector mesons and baryons with charm, which have a strong repercussion on the properties of the J/ΨN interaction. We also address the interaction of K* with nuclei and make suggestions to measure the predicted huge width in the medium by means of transparency ratio. The formalism is extended to study the phenomenon of J/ψ suppression in nuclei via J/ψ photo-production reactions.
PROJECTED SHELL MODEL DESCRIPTION OF E2 TRANSITION PROBABILITIES AND g-FACTORS OF EVEN–EVEN NEUTRON-RICH NUCLEI FROMXeTONd
Authors: KRISHAN GOPAL , DEVI RANI , KHOSA S. K.
Published: October 2012

The systematics of E2 transition probabilities and g-factors of even–even N ≥ 86 Xe , Ba , Ce and Nd have been studied by using the projected shell model approach. The E2 transition probabilities and g-factors have been calculated by using the many-body wave functions that reproduce the low-lying ground state energy levels. The calculated B(E2) values show an increasing trend with spin and neutron number. The calculated g-factors reproduce the observed decreasing trend of [Formula: see text] with neutron number except Nd nuclei.
DYNAMIC PARTNERSHIP FORMATION FOR MULTI-ROVER COORDINATION
Authors: KNUDSON MATT , TUMER KAGAN
Published: October 2012

Coordinating multiagent systems to maximize global information collection is a key challenge in many real world applications such as planetary exploration, and search and rescue. In particular, in many domains where communication is expensive (e.g., in terms of energy), the coordination must be achieved in a passive manner, without agents explicitly informing other agents of their states and/or intended actions. In this work, we extend results on such multiagent coordination algorithms to domains where the agents cannot achieve the required tasks without forming teams. We investigate team formation in three types of domains, one where n agents need to perform a task for the team to receive credit, one where there is an optimal number of agents (n) required for the task, but where the agents receive a decaying reward if they form a team with membership other than n, and finally we investigate heterogeneous teams where individuals vary in construction. Our results show that encouraging agents to coordinate is more successful than strictly requiring coordination. We also show that devising agent objective functions that are aligned with the global objective and locally computable significantly outperform systems where agents directly use the global objective, and that the improvement increases with the complexity of the task.
SIMULATIONS OF FLOW CIRCULATIONS AND ATRAZINE CONCENTRATIONS IN A MIDWEST U.S. RESERVOIR
Authors: ZHAO XIANGGUI , GU ROY R. , GUO CHULING , WANG KUI , LI SHIJIE
Published: October 2012

Atrazine is the most commonly used herbicide in the spring for pre-emergent weed control in the corn cropping area in the Midwestern United States. A frequent high level of herbicide concentrations in reservoirs is a great concern for public health and aquatic ecosystems. In this study, a two-dimensional hydrodynamics and toxic contaminant transport model was applied to Saylorville Reservoir, Iowa, USA. The model simulates physical, chemical, and biological processes and predicts unsteady vertical and longitudinal distributions of a toxic chemical. Model results were validated by measured temperatures and atrazine concentrations. Simulated flow velocities, water temperatures, and chemical concentrations demonstrated that the spatial variation of atrazine concentrations was largely affected by seasonal flow circulation patterns in the reservoir. In particular, the simulated fate and transport of atrazine showed the effect of flow circulation on spatial distribution of atrazine during summer months as the river flow formed an underflow within the reservoir and resulted in greater concentrations near the surface of the reservoir. Atrazine concentrations in the reservoir peaked around the end of May and early June. A thorough understanding of the fate and transport of atrazine in the reservoir can assist in developing operation and pollution prevention strategies with respect to timing, amount, and depth of withdrawal. The responses of atrazine transport to various boundary conditions provide useful information in assessing environmental impact of alternative upstream watershed management practices on the quality of reservoir water.
A NUMERICAL STUDY OF FLUID INJECTION AND MIXING UNDER NEAR-CRITICAL CONDITIONS
Authors: LI HUA-GUANG , LU XI-YUN , YANG VIGOR
Published: October 2012

Nitrogen injection under conditions in close vicinity of liquid-gas critical point is studied through numerical simulation. The thermodynamic and transport properties of fluid exhibit anomalies in the near-critical fluid regime. These anomalies can cause distinctive effects on heat transfer and hydrodynamics. To focus on the influence of the highly variable properties and avoid the difficulties encountered in modeling high Reynolds number flows, a relatively low injection Reynolds number is adopted. A reference case with the same configuration and Reynolds number is also simulated in the ideal gas regime. Full conservation laws, real-fluid thermodynamic and transport phenomena are accommodated in the model. The obtained results reveal that the flow features of the near-critical fluid jet are significantly different from the ideal gas case. The near-critical fluid jet spreads faster and mixes better with the ambient fluid compared to the ideal gas jet. It is also identified that vortex pairing process develops faster in the near-critical case than in the ideal gas case. Detailed analysis of data at different streamwise positions including both flat shear layer region and fully developed vortex region reveals the effect of volume dilatation and baroclinic torque plays an important role in the near-critical fluid case. The volume dilatation effect disturbs the shear layer and makes it more unstable. The volume dilatation and baroclinic effects strengthen the vorticity and stimulate the vortex rolling up and pairing process.
COMPUTATIONAL STUDY OF DEFLAGRATION TO DETONATION TRANSITION IN A STRAIGHT DUCT: EFFECT OF ENERGY RELEASE
Authors: DOU HUA-SHU , HU ZONGMIN , KHOO BOO CHEONG
Published: October 2012

Numerical simulation based on the Euler equation and one-step reaction model is carried out to investigate the process of deflagration to detonation transition (DDT) occurring in a straight duct. The numerical method used includes a high resolution fifth-order weighted essentially nonoscillatory scheme for spatial discretization, coupled with a third order total variation diminishing Runge-Kutta time stepping method. In particular, effect of energy release on the DDT process is studied. The model parameters used are the heat release at q =50, 30, 25, 20, 15, 10 and 5, the specific heat ratio at 1.2, and the activation temperature at Ti =15, respectively. For all the cases, the initial energy in the spark is about the same compared to the detonation energy at the Chapman-Jouguet (CJ) state. It is found from the simulation that the DDT occurrence strongly depends on the magnitude of the energy release. The run-up distance of DDT occurrence decreases with the increase of the energy release for q =50~20, and increases with the increase of the energy release for q =50~20. It is concluded from the simulations that the interaction of the shock wave and the flame front is the main reason for leading to DDT.
LARGE EDDY SIMULATION OF AN ELLIPTIC JET INJECTED INTO A SUPERSONIC CROSSFLOW
Authors: WANG GUO-LEI , LU XI-YUN
Published: October 2012

A transverse jet issuing from an elliptic injector into a supersonic crossflow has been investigated using large eddy simulation. The complex flow structures and the relevant flow features are analyzed to exhibit the evolution of shock structures, vertical structures and jet shear layer. A horseshoe vortex is formed in the upstream of the jet and the shock structures exhibit small fluctuations due to the flow interaction. The kidney-shaped counter-rotating vortex pair dominates the flow field in the downstream of the jet. The elliptic jet spreads rapidly in the spanwise direction and then the axis-switching phenomenon occurs. Intense turbulent fluctuations are identified behind the Mach disk because of the large velocity gradients.
SIMULATION OF FLOW THROUGH POROUS ANODE IN MFC AT HIGHER POWER DENSITY
Authors: SU W. W. , XU Y. S. , YAN W. W. , LIU Y.
Published: October 2012

Microbial fuel cell (MFC) is a new environmental friendly energy device which has received greatly attention due to its technology for producing electricity directly from organic or inorganic matter using bacteria as catalyst. To date, many studies have been carried out on advective flow through porous anode in a continuous flow MFC. However, the precise mechanical mechanism of flow through porous anode and the quantified relationship between porous media and MFC performance are not yet clearly understood. It has been found experimentally the power density can be increased apparently at certain spacing configuration. Based on these available experimental data, we studied the effect of spacing between electrodes and the Darcy number of porous anode on the power generation performance of MFC using lattice Boltzmann method. The simulation results indicated that the spacing between electrodes significantly influence the flow velocity profile and residence time in the MFC. Moreover, it was found that the Darcy number of porous anode could regulate the output efficiency of MFC. Our results would be helpful to optimize MFC design.
AIRFRAME NOISE PREDICTION USING THE SNGR METHOD
Authors: CHEN RONGQIAN , WU YIZHAO , XIA JIAN
Published: October 2012

In this paper, the Stochastic Noise Generation and Radiation method (SNGR) is used to predict airframe noise. The SNGR method combines a stochastic model with Computational Fluid Dynamics (CFD), and it can give acceptable noise results while the computation cost is relatively low. In the method, the time-averaged mean flow field is firstly obtained by solving Reynolds Averaged Navier-Stokes equations (RANS), and a stochastic velocity is generated based on the obtained information. Then the turbulent field is used to generate the source for the Acoustic Perturbation Equations (APEs) that simulate the noise propagation. For numerical methods, timeaveraged RANS equations are solved by finite volume method, and the turbulent model is K – ε model; APEs are solved by finite difference method, and the numerical scheme is the Dispersion-Relation-Preserving (DRP) scheme, with explicit optimized 5-stage Rung-Kutta scheme time step. In order to test the APE solver, propagation of a Gaussian pulse in a uniform mean flow is firstly simulated and compared with the analytical solution. Then, using the method, the trailing edge noise of NACA0012 airfoil is calculated. The results are compared with reference data, and good agreements are demonstrated.
RE-EVALUATING MIXING LENGTH IN TURBULENT MIXING LAYER BY MEANS OF HIGH-ORDER STATISTICS OF VELOCITY FIELD
Authors: CHANG KEH-CHIN , LI KUAN-HUANG , CHANG TING-CHENG
Published: October 2012

A turbulent planar mixing layer is composed of two different flow types in its flow field, namely a shear layer in the central region and two free streams in each outer high- and low-speed side. Shear layer is formed after the trailing edge of the splitting plate and develops stream-wisely through successively distinct regions, namely the near field region and the self-preserving region. Two alternative definitions of the mixing lengths (lS and lF) are proposed in terms of the skewness and flatness factors, respectively, which are of third- and fourth-order of turbulence statistics. It is shown that the linear growth rate of the mixing length (either lS or lF) can be, then, used as one of the necessary and sufficient conditions to identify the achievement of the self-preserving state in turbulent mixing layer. Moreover, lF can be taken as the real length scale of the shear layer, which is of shear turbulence, bounded by the two outer high- and low-speed free streams in a given stream-wise station.
WIND TURBINE AERODYNAMICS PREDICTION USING FREE-WAKE METHOD IN AXIAL FLOW
Authors: JEONG MIN-SOO , YOO SEUNG-JAE , LEE IN
Published: October 2012

Wind turbine aerodynamics remains a particularly challenging and crucial research for wind energy industry. The blade element momentum theory is the most widely used in predicting the performance of wind turbine, since the method is simple and fast numerical algorithm. The flow field generated by rotary wing is considerably important and complicated, however, the BEM method has some limitations to model the unsteady effects. To overcome these limitations, the aerodynamic analysis using a time-marching free-vortex wake method was performed in this paper. Moreover, the inboard region of the blade experience a delay in stall and enhanced values of the normal force coefficient because of rotational boundary layer augmentation and three-dimensional effects. For this reason, Raj-Selig stall delay model was applied in this research. The numerical results were compared with experimental data, and the present results show excellent agreement with experiment.
PERFORMANCE OF NEEDLE-FREE INJECTION OF ORGANIC FIBER SOLUTIONS FOR TISSUE ELEVATION
Authors: WANG MUH-RONG , CHEN MIN , HU CHIH-YUAN
Published: October 2012

This paper investigates the characteristics of endoscopic needle-free injection and the performance of tissue elevation by an endoscopic needle-free injection system. We choose the stomach of six-months-old pig as the test material, with HPMC and MC as the working fluid. The parameters include the mass flow rate, average power of injection, and the height of tissue elevation, and the evolution of tissue elevation. According to the experiment data, the performance of HPMC is much better than MC, because of the difference of their molecular structure. Longer duration of tissue elevation of the submucosal layer is maintained under the pressure of 90bar and the concentration of HPMC at 0.5%. The tissue elevation is 10.6mm suitable for medical surgery with the higher injection pressure under the same concentration of the working fluid because of the increased injection power. Analysis on the evolution of tissue elevation found that duration time is more than 60 minute under higher concentration of HPMC. The duration of tissue elevation is longer for higher concentration of the working fluid because the higher viscosity under high concentration would result in the elongation of the elevation time. A clear separation of the mucosal layer from the muscle layer is achieved by injecting HPMC in the samples with formalin-fixed and paraffin-embedded sections stained with H&E. Results of the experiments would provide the data base for endoscopic surgery in order to assure a successful operation.
INTERACTION OF TWO DIFFERENTLY SIZED BUBBLES IN A FREE FIELD
Authors: CHEW LUP WAI , KHOO BOO CHEONG , KLASEBOER EVERT , OHL SIEW-WAN
Published: October 2012

The interaction between two different sized (spark created, non-equilibrium) bubbles is studied by using high speed photography. The bubble size ranges from 2 to 7 mm. The experimental results are compared to that of the similar sized bubbles reported in the literature. Interestingly, all the four major behaviors of bubble-bubble interactions (i.e. 'bubble-collapsed' induced liquid jets directed away from each other, liquid jets directed towards each other, bubble coalescence and the 'catapult' effect) are observed which bear much similarity to that found for similar sized bubbles' interaction. The main parameters studied/varied are the size of the bubbles, the dimensionless separation distance and the phase difference between the two bubbles. The results obtained are consistent with the cases of similar sized bubbles reported in the literature, with each type of behavior occupying a distinct region in the graphical plot. This indicates that the results for the (special) similar sized bubbles can be generalized to cases with different sized bubbles. Many of the real life applications such as cavitations corrosions often involve bubbles with significant size difference, thus the present findings are useful in predicting the behavior of multiple bubbles in many situations.
ULTRASONIC CONCENTRATION AND TRAPPING OF MICROSIZED PARTICLES IN A FLUID SUSPENSION
Authors: HTIKE THEIN MIN , LIM KIAN-MENG
Published: October 2012

We present a millimeter scale fluidic channel for concentrating and filtering microsized particles suspended in the fluid medium. The device takes on an h-shape with a narrow inlet and a wide outlet. By setting up an ultrasonic standing wave across the channel width, microparticles with positive acoustic contrast factor are constrained to move along pressure nodal lines within the fluid. The acoustic radiation force acts on the particles in the transverse direction, keeping the particles to the lower part of the outlet. As a result, a suspension with higher particle concentration is formed at the lower part of the outlet, while clean fluid can be extracted at the upper part of the outlet. A series of experimental results were obtained to study the performance of this concentration process for various volume flowrates and ultrasonic power used. For high ultrasonic power, the microparticles were found to be trapped in the fluid channel. A numerical model was also developed to study the strength of the acoustic energy density in the channel and its influence on the performance of the concentrator. This ultrasonic concentrator has potential in biomedical and environmental applications where cells and micro-organisms need to be filtered out from a fluid suspension.
EFFECTS OF BOUNDARY-LAYER THICKNESS ON UNSTEADY FLOW CHARACTERISTICS INSIDE OPEN CAVITIES AT SUBSONIC AND TRANSONIC SPEEDS
Authors: YANG DANG-GUO , LI JIAN-QIANG , FAN ZHAO-LIN , LUO XIN-FU
Published: October 2012

An experimental study was conducted in a 0.6m by 0.6m wind-tunnel to analyze effects of boundary-layer thickness on unsteady flow characteristics inside a rectangular open cavity at subsonic and transonic speeds. The sound pressure level (SPL) distributions at the centerline of the cavity floor and Sound pressure frequency spectrum (SPFS) characteristics on some measurement positions presented herein was obtained with cavity length-to-depth ratio (L/D) of 8 over Mach numbers (Ma) of 0.6 and 1.2 at a Reynolds numbers (Re) of 1.23 × 107 and 2.02 × 107 per meter under different boundary-layer thickness to cavity-depth ratios (δ/D). The experimental angle of attack, yawing and rolling angles were 0°. The results indicate that decrease in δ/D leads to severe flow separation and unsteady pressure fluctuation, which induces increase in SPL at same measurement points inside the cavity at Ma of 0.6. At Ma of 1.2, decrease in δ/D results in enhancing compressible waves. Generally, decrease in δ/D induces more flow self-sustained oscillation frequencies. It also makes severer aerodynamic noise inside the open cavity.
A NEW APPROACH FOR COMPLETE MIXING BY TRANSVERSE AND STREAMWISE FLOW MOTIONS IN MICRO-CHANNELS
Authors: WANG MUH-RONG , DAI CHIAU-YI , HUANG YANG-SHENG
Published: October 2012

Mixing control is an important issue in micro-fluid chip applications, such as μTAS (Micro-Total Analysis System) or LOC (Lab-on-Chip) because the flow at micro-scale is highly laminar. Several flow control schemes had been developed for complete mixing in the micro-channels in the past decades. However, most of the mixing control schemes are performed by utilizing specific excitation devices, such as electrokinetic, magnetic or pressure drivers. This paper investigates a new control scheme which is composed of a series of flow manipulation by changing the pressure at the two inlets of the micromixer as the external excitation. The fluids from two inlets are introduced to a square mixing chamber, which provides a space where the streamwise and transverse flow motions take place. The results show that the micromixer can be used to produce a large recirculation zone with series of small transverse fringes under external excitations. It is found that this new flow pattern enhances mixing processes at the micro-scale. A complete mixing can be achieved under appropriate flow control with the corresponding design.
EXPERIMENTAL AND NUMERICAL INVESTIGATION OF ICE ACCRETION ON AIRFOIL
Authors: MENG FANXIN , CHEN WEIJIAN , ZHANG DALIN , MA HUI
Published: October 2012

Open Circuit Icing Research Tunnel was developed to test the ice shape under simulated icing conditions. Standard icing blade technique was used to measure liquid water content (LWC) in the icing tunnel test section. The uniformity of liquid water content was assessed by accreting ices on aluminum cylinder bars. Mean volumetric diameter (MVD) of the spray cloud was determined by soot-coated slide and verified through the limits of impingement. Ice accretion tests were performed on a NACA0012 wing model in typical rime and glaze conditions. Results were compared to ice shapes numerically predicted by Messinger method in the same conditions. It is indicated that good overall agreement is achieved in both icing shape and impingement limit.
MECHANISM AND PERFORMANCE OF CO2 SNOW JET IN CO-AXIAL TYPE INJECTION SYSTEMS
Authors: SHEN YI-JUN , WANG MUH-RONG
Published: October 2012

This paper describes the characteristics of CO 2 snow formation with co-axial type injection systems. The injection of CO 2 snow flow is controlled by a co-axial type nitrogen auxiliary nozzle. Five cases of co-axial nitrogen nozzle with different diameters and injection types of auxiliary nitrogen are presented. Flow field visualization and spray characteristics are performed by the particle image velocimetry (PIV). Result shows that the CO 2 snow particles would collide with each other and generate lager particles in the recirculation zone of the formation chamber. Results also show that the particle size distribution is influenced by the geometry of the injection device. The length of the formation chamber influence the region and strength of recirculation flow. In the region after reattach zone of recirculation flow, the fine particles deposit on the chamber wall and form a deposition layer. The particles in the main stream further impinge onto the deposition layer and result in the snowballs. It turns out that the mean particle size becomes larger as the length of chamber is increased. Results also show that CO 2 snow jet has higher velocity and the flow-focusing takes place with nitrogen auxiliary gas. Furthermore, the mist layer of the jet flow caused by lower temperature of CO 2 snow is eliminated when co-axial nitrogen flow is injected. The velocity of CO 2 snow jet is increased under higher injection pressure of co-axial nitrogen flow. Furthermore, smaller diameter of nitrogen auxiliary nozzle results in higher injection velocity of CO 2 snow jet. Hence the injection power of the CO 2 snow jet can be controlled by the design of the nitrogen auxiliary nozzle. It will be useful in the medical applications of cryotherapy treatment and the dry cleaning of the semiconductor and solar cell manufacturing processes.
EXPERIMENTAL RESEARCH ON AEROELASTICITY OF A LARGE LENGTH TO DIAMETER RATIO PROJECTILE
Authors: YI WENJUN , SUN DONGYANG , TAN JUNJIE , YUAN DANDAN
Published: October 2012

In order to investigate the aeroelastic influences on the aerodynamic performance and flight stability of a large length to diameter ratio projectile, free-flight experiments on both the flexible and rigid projectile model are performed in our ballistic range. Many groups of shadowgraphs for these two kinds of projectiles during flight tests were taken and one of those typical results is shown. The projectile flight velocity, angle of attack and precession are obtained after the data procession. Moreover, the aerodynamic force and moment coefficients of two kinds of projectiles are presented, their aerodynamic performances and flight stability are compared and analyzed. Our results show that the flexible projectile has larger drag coefficient than the rigid. After the deformation, its lift to drag ratio decreases and its rotation moment increases obviously. The elastic deformation of the flexible projectile has remarkable influence on its flight stability which can induce the flight instability.
ENERGY SPECTRUM OF DISTURBANCE AT TURBULENT TRANSITION VIA ENERGY GRADIENT METHOD
Authors: DOU HUA-SHU , KHOO BOO CHEONG
Published: October 2012

The energy gradient theory for flow instability and turbulent transition was proposed in our previous work. The theoretical result obtained accords well with some experimental data for pipe and channel flows in the literature. In the present study, the energy gradient theory is extended to examine the effect of disturbance frequency on turbulent transition. Then, the energy spectrum of disturbance at the turbulent transition is obtained, which scales with the wave number by an exponent of –2. This scaling is near to the K41 law of –5/3 for the full developed isentropic homogenous turbulence. The difference for the two energy spectra may be due to the intermittency of turbulence at the transition state. The intermittence causes the distribution of the energy spectrum to take on a steeper gradient (tending to –2 from –5/3). Finally, the flow instability leading to turbulent transition can be classified as two-dimensional (2D) or three-dimensional (3D) in terms of the wave number and the Re. It is found that there is an optimum wave number which separates the 2D and 3D transitions and at which the disturbance energy at transition is minimum.
INVESTIGATION OF HEAD-DISK INTERFACE AND UNLOADING PROCESS IN HDD WITH AN EFFICIENT SCHEME
Authors: DU HEJUN , LIU YAN
Published: October 2012

An efficient scheme was developed to analyze head-disk interfaces (HDIs) in hard disk drives. HDIs were studied by decoupling the nanometer scale variations of the air bearings and the micrometer scale changes of the suspensions. The nonlinear variations of the air bearing forces and moments were described with analytical expressions obtained from a surface fitting scheme. Combined with a 3 degree of freedom (DOF) suspension model whose parameters were estimated from a comprehensive finite element model, the historical behaviors of a subambient slider during an unloading process can be obtained in a very short computation period, thus providing a way of exploring a large number of parameter values of the suspension stiffness matrix.
HEAT BALANCE RESEARCH OF 3MW MARINE WIND TURBINE'S ENGINE ROOM
Authors: KANG NA , JIANG YANLONG , ZHOU NIANYONG , SHI HONG , LIU ZHILI , WANG YU
Published: October 2012

The increment of heat load in Wind Turbine's engine room could cause the system shut down. In this paper the heat balance of Wind Turbine's engine room is investigated according to the structure of the engine room, environmental operating requirements as well as heat-dissipating of different components of a 3MW Wind Turbine System. The heat load of the engine room is analyzed and the physical model is developed based on finite volume method. After that, the temperature distribution of the cabin is obtained under different conditions with/without the jet unit. The temperature distribution in engine compartments with different number and the arrangement of jet units is compared in this paper. Based on the analysis, the cabin cooling design is carried out to achieve the purpose of stopping heat gathering and keeping heat balance of the cabin. This work puts forward the heat balance maintenance and completes the corresponding research, which could be helpful for the optimization of large-capacity Wind Turbine cooling system.
A NEW EFFICIENT CONTROL METHOD FOR BLENDED WING BODY
Authors: WU WENHUA , CHEN DEHUA , QIN NING , PENG XIN , TANG XINWU
Published: October 2012

The blended wing body (BWB) is the hottest one of the aerodynamic shapes of next generation airliner because of its' high lift-drag ratio, but there are still some flaws that cut down its aerodynamical performance. One of the most harmful flaws is the low efficiency of elevator and direction rudder, this makes the BWB hard to be controlled. In this paper, we proposed a new control method to solve this problem by morphing wing—that is, to control the BWB only by changing its wing shape but without any rudder. The pitching moments, rolling moments and yawing moments are plotted versus the parameters section and the wing shape in figures and are discussed in the paper. The result shows that the morphing wing can control the moments of BWB more precisely and in wider range. The pitching moments, rolling moments and yawing moments increases or decreases linearly or almost linearly, with the value of the selected parameters. These results show that using morphing wing is an excellent aerodynamic control way for a BWB craft.