bluuebunny/crossref_metadata_2025 huggingface dataset:
Additive and Over‐dominant Effects Resulting from Epistatic Loci Are the Primary Genetic Basis of Heterosis in Rice
Authors: Luo Xiaojin , Fu Yongcai , Zhang Peijiang , Wu Shuang , Tian Feng , Liu Jiayong , Zhu Zuofeng , Yang Jinshui , Sun Chuanqing
Published: February 2009

A set of 148 F9 recombinant inbred lines (RILs) was developed from the cross of an indica cultivar 93‐11 and japonica cultivar DT713, showing strong F1 heterosis. Subsequently, two backcross F1 (BCF1) populations were constructed by backcrossing these 148 RILs to two parents, 93‐11 and DT713. These three related populations (281BCF1 lines, 148 RILs) were phenotyped for six yield‐related traits in two locations. Significant inbreeding depression was detected in the population of RILS and a high level of heterosis was observed in the two BCF1 populations. A total of 42 main‐effect quantitative trait loci (M‐QTLs) and 109 epistatic effect QTL pairs (E‐QTLs) were detected in the three related populations using the mixed model approach. By comparing the genetic effects of these QTLs detected in the RILs, BCF1 performance and mid‐parental heterosis (HMP), we found that, in both BCF1 populations, the QTLs detected could be classified into two predominant types: additive and over‐dominant loci, which indicated that the additive and over‐dominant effect were more important than complete or partially dominance for M‐QTLs and E‐QTLs. Further, we found that the E‐QTLs detected collectively explained a larger portion of the total phenotypic variation than the M‐QTLs in both RILs and BCF1 populations. All of these results suggest that additive and over‐dominance resulting from epistatic loci might be the primary genetic basis of heterosis in rice.
Comparison of photospheric current helicity and subsurface kinetic helicity
Authors: Gao Yu , Zhang Hongqi , Zhao Junwei
Published: February 2009

We make a comparison between photospheric current helicity and subsurface kinetic helicity in solar active regions. Four parameters are employed: average value of vertical component of current helicity density 〈Bz· (∇×B)z〉 (〈Hc〉), average force-free field factor and mean subsurface kinetic helicity 〈v· (∇×v)/|v|2〉 (αv), which is denoted as two different parameters, 〈αv1〉 and 〈αv2〉, according to different depths beneath the solar surface. A total of 38 active regions are investigated. The results show that the signs of 〈Hc〉 and αave have a typical hemispheric distribution feature. In contrast, the sign of 〈αv1〉 presents the opposite feature to the above two parameters. For 〈αv2〉, there is no obvious preponderance of the sign in each hemisphere as with the other three parameters. Although there is an opposite hemispheric preponderance between the signs of current helicity and that of kinetic helicity at 0–3 Mm beneath the solar surface, the uncertain correlations between 〈Hc〉 and 〈αv1〉, αave and 〈αv1〉, 〈Hc〉 and 〈αv2〉, and αave and 〈αv2〉 (the correlation coefficients are -0.095, 0.118, -0.102 and -0.179, respectively) do not support that the photospheric current helicity has a cause and effect relation with the kinetic helicity at 0–12 Mm beneath the solar surface.
Human Rights and TRIPS Exclusion and Exception Provisions
Authors: Haugen Hans Morten
Published: February 2009

The Agreement on Trade‐Related Aspects at Intellectual Property Rights contains several provisions that both allow for exclusion from patentability, as well as exceptions from the exercise of the rights of the patent holder. With the exception of the first part of article 30, none of these have until now been clarified by the World Trade Organization's (WTO's) dispute‐settlement system. Based on an in‐depth analysis of a number of these TRIPS provisions, the article identifies whether and how human rights provisions, as well as more overall human rights principles, can be applied in order to strengthen and confer legitimacy to these exclusion and exception provisions. While there is general agreement of the weight of human rights, there is more disagreement on the relevance of human rights, primarily due to the general wording of human rights provisions. Without undertaking a full analysis of the relevant human rights provisions, the article finds that human rights also do provide guidance in negotiations and enforcement of intellectual property rights. An analysis of the prospects for taking into account human rights within the dispute‐settlement system and in the political bodies of the WTO is also conducted.
Neo‐Colonial Aspects of Global Intellectual Property Protection
Authors: Rahmatian Andreas
Published: February 2009

An essential instrument in the process of neo‐colonialism by economic means is the establishment of a legal framework of international trade that confers legally enforceable rights that support and safeguard economic penetration and control. This includes, in a similar way as in colonial times, the guarantee of protection of foreign property rights in dependent regions. Today, intellectual property rights fulfil this colonizing role to a large extent. It will be shown that the implementation of the Agreement on Trade‐Related Aspects of Intellectual Property Rights is one major device that drives such an economic neo‐colonialism forward. This is reflected in the history of the making of this treaty, as well as in the methods of enforcement of intellectual property rights, which will be demonstrated in the example of China. Besides this international expansion of Western‐style intellectual property rights, there is another, seemingly contrasting and alternative non‐proprietarian, legislative project, which nevertheless has neo‐colonial effects: the protection of traditional cultural expressions in the context of “traditional” arts. The article discusses that, despite presumably good intentions, this measure reflects colonial features, such as the concept of indirect rule, and invites segregationist legislation.
Cross‐Border Collective Management and Principle of Territoriality: Problems and Possible Solutions in the EU
Authors: Matulionytė Rita
Published: February 2009

Cross‐border collective management has recently been a highly discussed topic, in particular from the perspective of competition law. This article focuses on the less discussed issue—the problem of the territoriality principle in cross‐border collective management. Territoriality of substantial copyright laws leads to the need for collecting societies to check the initial ownership, scope of rights, etc. under each national copyright law. In addition, territoriality of the collective management laws (as distinguished from substantial copyright laws) requires the societies to adhere to multiple laws differently regulating establishment, functioning, accountability, etc. of the societies. The article analyses the possible solutions to these problems.
Challenges and Standards in Reporting Diagnostic and Prognostic Biomarker Studies
Authors: Azuaje Francisco , Devaux Yvan , Wagner Daniel
Published: February 2009

The discovery of novel biomarkers is a crucial goal in translational biomedical research. A complete and accurate reporting of biomarker studies, including quantitative prediction models, is fundamental to improve research quality and facilitate their potential incorporation into clinical practice. This paper reviews key problems, guidelines, and challenges in reporting biomarker studies, with an emphasis on diagnostic and prognostic applications in cardiovascular research. Recent advances and recommendations for aiding in peer review, research quality assessment, and the reproducibility of findings, such as diagnostic biosignatures, are discussed. An examination of research recently published in the area of cardiovascular biomarkers was implemented. Such a survey, which was based on a sample of papers deposited in PubMed Central, suggests that there is a need to improve the documentation of biomarker studies in terms of information completeness and clarity, as well as the application of more rigorous quantitative evaluation techniques. There is also room for improving practices in reporting data analysis and research limitations. This survey also suggests that, in comparison with other research areas, the cardiovascular biomarker research domain may not be taking advantage of existing standards for reporting diagnostic accuracy. The review concludes with a discussion of the challenges and recommendations.
Oral health conditions in Italian Special Olympics athletes
Authors: Dellavia Claudia , Allievi Cristina , Pallavera Andrea , Rosati Riccardo , Sforza Chiarella
Published: February 2009

During three Italian Special Olympics National Games, 365 athletes were screened. Dental and medical conditions and demographic data were recorded. The athletes were divided into two groups: those with Down syndrome (DS) and those without DS but who had intellectual disabilities (non‐DS).

Most of the subjects were in good systemic health. Total DMFt was 10.3 (SD 5.8; D = 1.3; M = 6.1; F = 2.8). Decayed and filled teeth were significantly more frequent in athletes who did not have DS compared to those with DS. No significant differences were found between the two groups in the number of subjects with filled, sealed, or traumatized teeth.

Athletes with DS and without DS who participated in the Italian Special Olympics had a similar oral status, which was better than Italian persons who were institutionalized and who had an intellectual disability.
Antigen‐presenting cells in human immunosuppressive drug‐induced gingival enlargement
Authors: Cury Patricia R. , Arsati Franco , De Magalhães Marina Helena Cury Gallottini , De Araújo Vera C. , De Araújo Ney S. , Barbuto José Alexandre
Published: February 2009

An immunoperoxidase technique was used to compare the number of CD1a+ and factor XIIIa+ dendritic cells (DCs), and CD68+ Macrophages (M) in 30 gingival samples from subjects with clinically healthy periodontitium (HP) and 10 samples from subjects with drug‐induced gingival enlargement (DIGE). Fewer CD1a+ and factor XIIIa+ DCs were found in areas with inflammatory infiltration (II) of the lamina propria (LP) in the group with immunosuppressed DIGE (IDIGE) compared to the group with HP. In the sulcular and junctional/pocket epithelia, the number of CD1a+ DCs was decreased in the group with IDIGE (p < 0.05). There was a tendency toward a reduced number of CD1a+ DCs and CD68+ M in areas without inflammatory infiltrate of the LP in the group with IDIGE. The alterations in the number of antigen‐presenting cells (APCs) may be the reason for the decreased periodontal inflammation and breakdown clinically observed in subjects who are immunosuppressed.
Toothache pain: Behavioral impact and self‐care strategies
Authors: Cohen Leonard A. , Bonito Arthur J. , Akin Donald R. , Manski Richard J. , Macek Mark D. , Edwards Robert R. , Cornelius Llewellyn J.
Published: February 2009

A computer‐assisted telephone interview in Maryland of adults who had low income and were Hispanic, Black, and White and who had experienced a toothache during the previous 12 months was conducted. Respondents reported a high prevalence of toothaches, with 44.3% having experienced more than five toothaches during the preceding 10 years. Pain intensity associated with the most recent toothache was high with 45.1% of the respondents reporting the highest pain possible. Pain interfered with many aspects of normal functioning. Self‐care strategies generally took precedence over professional health services. Pain sufferers used a combination of self‐care and formal care strategies. Initial strategies most often focused on nonprescription medicines(home remedies and prayer. The majority of respondents ultimately sought pain relief from a dentist. We identified a number of significant differences in the strategies used across racial(ethnic groups.
Characterization of 10 microsatellite loci in an avian louse, Degeeriella regalis (Phthiraptera: Ischnocera: Philopteridae)
Authors: PETERS MAUREEN B. , HAGEN CRIS , WHITEMAN NOAH K. , PARKER PATRICIA G. , GLENN TRAVIS C.
Published: February 2009

We isolated and characterized 10 polymorphic microsatellite loci in an ischnoceran louse, Degeeriella regalis, which parasitizes the threatened Galápagos hawk (Buteo galapagoensis) and other falconiform birds. The loci were screened across 30 individuals from two island populations in the Galápagos Islands. The number of alleles per locus ranged from two to 28. Polymorphic information content ranged from 0.14 to 0.94 and observed heterozygosity ranged from 0 to 0.67. These markers will be valuable in comparative population genetics studies in this species, which is the focus of a long‐term population and disease ecology research program.
Generation of a Sequence Characterized Amplified Region Probe for Authentication of Mainland Serow (Capricornis sumatraensis)
Authors: MENG KAI , YU JIAN , LUO TAO‐LIN , WU HAI‐LONG , WU XIAO‐BING
Published: February 2009

Mainland serow is an endanged artiodactyl of southern Anhui province, China, that is often subject to poaching. To provide an easy, rapid and reliable marker for identification of bushmeat, skin and other tissues of the species, we developed a sequence characterized amplified region (SCAR) based on a species‐specific random amplified polymorphic DNA (RAPD) marker. Initially, a 1012‐bp species‐specific DNA fragment of mainland serow was detected by a RAPD primer S1193. Then, a serow‐specific primer pair (SCF/SCR) was designed according to the specific RAPD fragment, resulting in a 438‐bp SCAR for the species. Finally, the reliability of the SCAR primers was tested by a common multiplex polymerase chain reaction using the combination of the SCAR and cyt b universal primers. The results that all mainland serow samples presented two target bands but the others failed to produce the SCAR indicated that the designed primers were highly diagnostic. Therefore, the SCAR probe developed in this study will be useful for quick authentication of mainland serow tissue samples for conservation biology and bushmeat regulation.
Temporal changes in retinal thickness after removal of the epiretinal membrane
Authors: Aso Hitoshi , Iijima Hiroyuki , Imai Masahito , Gotoh Teruhiko
Published: February 2009

Purpose:  We aimed to study the temporal aspects of the postoperative reduction of retinal thickness in eyes with epiretinal membrane after vitrectomy with peeling of the epiretinal membrane and internal limiting membrane.

Methods:  In a retrospective study performed as a non‐comparative, interventional case series, 16 eyes from 15 patients with idiopathic epiretinal membrane who underwent vitrectomy and removal of the epiretinal membrane were followed up using optical coherence tomography measurements. Retinal thickness in the macular area was assessed by the foveal thickness and macular volume in a circle 6 mm in diameter.

Results:  Scattergrams of the foveal thickness and macular volume were best fitted with exponential curves. The average time constants of the exponential curve for foveal thickness and macular volume changes were 31 days (range 4–109 days) and 36 days (range 5–100 days), respectively. The average expected final values for foveal thickness and macular volume were 334 μm (range 206–408 μm) and 7.53 mm3 (range 6.57–8.66 mm3), respectively, which were significantly greater than those in normal controls (p < 0.0001, t‐test).

Conclusions:  Retinal thickness decreases rapidly immediately after surgical removal of the epiretinal membrane and the reduction rate gradually slows thereafter. Approximation of the exponential curve provides an estimation of final retinal thickness after surgical removal of the epiretinal membrane; final thickness is expected to be greater than in normal eyes.
Genetic Analysis of Ventricular Arrhythmia in Young German Shepherd Dogs
Authors: Cruickshank J. , Quaas R.L. , Li J. , Hemsley S. , Gunn T.M. , Moïse N.S.
Published: February 2009

Background:Ventricular arrhythmias (VA) and sudden death are inherited in German Shepherd Dogs (GSDs).

Objectives:To estimate the genetic parameters (heritabilities and correlations) of 3 traits of VA (single premature ventricular complexes (PVCs), 2 consecutive PVCs (couplets), and 3 or more consecutive PVCs—ventricular tachycardia [VT]).

Animals:Three hundred and ninety‐eight GSDs.

Methods:Prospective, observational, case control study. Dogs were phenotyped by 24‐hour ambulatory ECG from 6 to 45 weeks of age. Edited ECG records included the number of incidents of (1) single PVCs, (2) couplets, and (3) VT.

Results:A data set of 1,239 Holter records from 398 GSDs was used to estimate genetic variables. Phenotypic correlations for affectedness (binarily coded 0/1) of the 3 traits ranged from 0.55 to 0.74, whereas correlations for severity (continuous values of 24‐hour VA counts) ranged from 0.26 to 0.39. Estimates of genetic correlation among the severity traits were 0.06 to 0.27. Estimated heritabilities were 0.54, 0.54, and 0.46 for affectedness and 0.33, 0.69, and 0.69 for severity of PVCs, couplets, and VT, respectively. Month and year of birth and age at ECG recording had significant effects on all 3 traits. Season of ECG recording had a significant effect on the number of single PVCs, but not couplets or incidents of VT. Age of onset differed, with single PVCs appearing an average of 4 days earlier than couplets and VT.

Conclusion:These results imply a strong genetic component for this disease but suggest that differences in the 3 traits should be taken into consideration in studies to identify the underlying genes.
Naloxone does not inhibit the attenuation of the response to severe haemorrhage seen after simulated injury in the anaesthetized rat
Authors: Sawdon Marina , Ohnishi Mitsuo , Little Rodney A. , Kirkman Emrys
Published: February 2009

Severe haemorrhage leads to a reflex bradycardia and hypotension. This is thought to be protective, but is attenuated by both concomitant musculoskeletal injury and exogenous morphine. The aim of this study was to determine whether the injury‐induced attenuation of the response to severe haemorrhage could be blocked by naloxone. Male Wistar rats, terminally anaesthetized with alphadolone/alphaxalone (19–20 mg kg−1h−1i.v.), were randomly allocated to one of four groups. In groups I and IV, haemorrhage was simple [40% of estimated total blood volume (BV)], while in groups II and III it was initiated 10 min after the onset of bilateral hindlimb ischaemia (a model of musculoskeletal injury). Groups I and II received 20 μl of 0.9% saline intracerebroventricularly (i.c.v.) immediately before haemorrhage, while groups III and IV received 20 μg of naloxonei.c.v., in the same volume. In group I, the bradycardia reached its peak after the loss of 32.8 ± 0.3% BV (mean ±s.e.m.). Blood pressure did not fall significantly until the loss of 15.0 ± 3.0% BV. The response in group IV was not significantly different from group I. By contrast, the bradycardia was absent after similar blood losses in groups II and III, while hypotension was attenuated. These results indicate that naloxone, at a dose known to be effective in blocking μ‐opioid receptors and preventing other aspects of the response to injury, does not prevent the injury‐induced attenuation of the response to severe haemorrhage. Thus the attenuation of the response to blood loss by injury is unlikely to be mediated via the μ‐opioid receptors.
Microhole Coiled Tubing Drilling: A Low Cost Reservoir Access Technology
Authors: Perry Kent
Published: February 2009

Although the microhole coiled tubing drilling rigs have been used extensively in Canada, their application in the U.S. has been very limited. In an effort to introduce this technology to the U.S. operators, GTI, with the support of DOE∕NETL, has completed a successful field testing of the coiled tubing microhole drilling technology. In this paper we report results of field testing of the system in 25 wells drilled in the Niobrara unconventional gas play of Kansas and Colorado. The objective of the field test was to measure and document the rig performance under actual drilling conditions. In these tests, a coiled tubing drilling rig (designed and built by T Gipson with Advanced Drilling Technologies Inc.) was utilized. The rig operations have continued to improve to the point where it now drills a 3100ft well in a single day. Well cost savings of approximately 30% over conventional rotary well drilling have been documented. A description of the rig and a summary of its performance in the Niobrara unconventional gas play are included. In addition, an estimate of economic advantages of widespread application of microhole drilling technology in the lower 48 states is presented.
Added Mass
Effects of Compressible and Incompressible Flows in Fluid-Structure
Interaction
Authors: van Brummelen E.
H.
Published: February 2009

The subiteration method, which forms the basic iterative procedure for solving fluid-structure-interaction problems, is based on a partitioning of the fluid-structure system into a fluidic part and a structural part. In fluid-structure interaction, on short time scales the fluid appears as an added mass to the structural operator, and the stability and convergence properties of the subiteration process depend significantly on the ratio of this apparent added mass to the actual structural mass. In the present paper, we establish that the added-mass effects corresponding to compressible and incompressible flows are fundamentally different. For a model problem, we show that on increasingly small time intervals, the added mass of a compressible flow is proportional to the length of the time interval, whereas the added mass of an incompressible flow approaches a constant. We then consider the implications of this difference in proportionality for the stability and convergence properties of the subiteration process, and for the stability and accuracy of loosely coupled staggered time-integration methods.
Synthesis of a Novel Ester-Based Drilling Fluid Applicable to High Temperature Conditions
Authors: Nasiri M. , Ashrafizadeh S. N. , Ghalambor A.
Published: February 2009

Ester-based drilling fluids based on aliphatic esters were introduced in 1990. Esters can be synthesized from fatty acids and alcohols. Previous studies indicated that ester hydrolysis in drilling fluids happens only under certain conditions. In order for ester hydrolysis to occur, two primary conditions must be present: high temperature and excessive hydroxyl. When the temperature exceeds 300°F, ester hydrolysis can occur under the presence of excessive hydroxyl. Hydrolysis breaks down the ester component into its parent carboxylic acid and alcohol. The current study shows that the stability of ester-based drilling fluids at high temperature conditions depends on the composition so that the selection of proper components and additives such as emulsifiers, stabilizers, copolymers, viscosifiers, and rheological modifiers can increase the temperature stability of the fluid. Hereby, the application of an ester-based drilling fluid is improved up to 350°F. The composition of the provided fluid is unique in the view point of its higher thermal stability against the previous formulations provided in literature. Furthermore, the experimental results of this study show the favorable effect of hot-rolling pressure on barite sag and electrical stability of the mud, i.e., increasing the pressure at three particular temperatures of 300°F, 325°F, and 350°F reduced the barite sag and at some instances increased the electrical stability.
MEMS-Based Active Sliders With Multi-Layered Composite PZT Thin Films in Hard Disk Drives
Authors: Tagawa Norio , Mori Atsunobu
Published: February 2009

This paper describes MEMS-based active sliders with micro-actuators. The proposal active slider uses PZT thin films as a micro-actuator and control the slider flying height of less than 10 nm. The design procedure for the active slider is discussed. In addition, novel multi-layered composite PZT thin film micro-actuators, which are very important functional micro-devices, are studied, and it is shown that the recently developed PZT thin films have better piezoelectric characteristics than not only conventional sol-gel derived PZT thin films but also sputtered PZT thin films. The micro-machining process for the active slider is also developed and the pico-size active slider is fabricated. The technical issues related to the fabrication of MEMS-based active sliders are discussed.
Textured Sliders as Means to Reduce Adhesion in Ultra Low Flying Head Disk Interfaces
Authors: Suh Allison Y. , Lee Sung-Chang , Polycarpou Andreas A.
Published: February 2009

A means of avoiding the negative consequences of ultra low flying super smooth Head/Disk Interfaces (HDIs) is to use textured sliders while still maintaining super smooth magnetic media. In this paper, the effect of preferential texturing (roughening) of slider air-bearing surfaces (ABS) on the intermolecular/adhesion forces at HDIs is investigated using a quasi-dynamic adhesion model. Super smooth (untextured), preferentially textured and rough sliders were investigated in this study. First, they were measured using an Atomic Force Microscope (AFM) and subsequently roughness parameters were extracted and used in the modeling. Preferential texturing provides a unique roughening of the ABS, where parts of the original surface are not affected, thus maintaining the initial roughness, with other parts of the surface being removed. This texturing has the net effect of reducing the effective or nominal area of contact between the slider and media surfaces, which plays an important role in the adhesion forces at the HDI. The simulation results indicate that preferential texturing can alleviate the problem of high adhesion forces in ultra-low flying HDI’s.
Reduction of Head Wear on Thin-Film Magnetic Disks
Authors: Kawakubo Youich , Miyazawa Shunichi , Nagata Kenjirou , Kobatake Shinichi
Published: February 2009

It is necessary to reduce head wear to develop future hard disk drives. For this purpose, we have been studying transparent pin-on-disk wear tests on thin-film magnetic disks. We reported that pin wear on thin-film magnetic disk showed running-in effects. The reason of the running-in was considered to be a result of disk surface flattening. This means that if we could introduce an efficient burnishing technique, we could reduce head wear in operation. We then introduced a burnishing technique using a hemispherical diamond slider and compared pin wear on disk surfaces with and without burnishing. The results showed that the pin wear was reduced by the introduction of the burnishing technique. We consider that burnishing with hard round slider is another way of reducing head wear on future disk surfaces.
Observations of Chain-Reaction Behavior at Bubble Collapse Using Ultra High Speed Video Camera
Authors: Sato Keiichi , Shimojo Shigemasa , Watanabe Jun
Published: February 2009

Collapsing behavior of cavitation bubbles is a very short phenomenon. In this study a new ultra-high-speed video camera with the maximum frame speed of 106 fps is used to observe the detailed aspects of three cavitation patterns such as separated vortex cavitation in a convergent-divergent channel, Karman-vortex-like cavitation in the wake flow of a circular cylinder and vibratory cavitation in an ultrasonic vibratory apparatus. For a convergent-divergent channel, the re-entrant motion within the separation zone was observed together with bubble collapse in the divergent part. It was found that minute bubbles collapsed in a chain-reaction manner inside the separated zone with the re-entrant motion after the shedding of cavitation cloud. For the wake flow of a circular cylinder, a collapsing motion of cavitation was observed as an axial-collapse type. The successive bubble collapses after the collapse of main bubble were caused due to pressure wave near the flow field. For cavitation in a vibratory apparatus, cavitation bubbles on the vibratory disk surface were examined in detail, especially from the viewpoint of a non-cavitation ring. The disappearance of bubbles spread radially toward the outer region through the motion of vibratory horn.
Computations of Unsteady Cavitation With a Pressure-Based Method
Authors: Senocak Inanc , Shyy Wei
Published: February 2009

A computational approach based on the conservative form of the Favre-averaged Navier-Stokes equations, transport equation-based turbulent cavitation models and a pressure-based operator-splitting algorithm is applied to study turbulent cavitating flows through convergent-divergent nozzles. The implications of the compressibility effect, reflected via the speed of sound definition in the two-phase mixture, are assessed with two modeling approaches. Depending on the geometric confinement of the nozzle, compressibility model, and cavitation numbers, auto-oscillations and quasi-steady behaviors are observed. Detailed flow structures and cavitation dynamics are highlighted, and implications of the cavitation model discussed.
Hydrodynamic Characteristics of Water-Entry Blades
Authors: Kamikubo Hisashi , Ikegami Dasisuke , Sato Kotaro , Mizuno Shinichi , Furuya Okitsugu , Tujimoto Yoshinobu
Published: February 2009

The partially submerged ventilated propeller (PSVP) is of interest to many researchers and ship builders due to its high propulsive efficiency and thrusting capability at the high sea states. As a matter of fact, it is now used for those ships of high speed up to 50 knots. However, its full capability is not totally utilized to date due to the complex nature of both hydrodynamic and material problems. It is a well known fact that PSVP fails materially after a certain period of time. The cause of the failure is not fully understood to date. Although PSVP is tested in the form of propeller for many years, the detailed ventilation phenomena, i.e., blade entry problems are not fully investigated. The paper presented herein will discuss about the results of blade entry experiments with two-dimensional blades of triangular shape used.
Determination of Condensation Coefficient and Boundary Condition for Kinetic Theory of Gases by Molecular Dynamics Simulations of Evaporation of Argon Into Vacuum
Authors: Ishiyama Tatsuya , Yano Takeru , Fujikawa Shigeo
Published: February 2009

Molecular dynamics simulations at liquid-vapor equilibrium condition and evaporation condition into vacuum were carried out to investigate the boundary condition for the kinetic theory of gases. The determination method for condensation coefficient α consistent with the kinetic theory is also proposed. It was found that α for argon at an equilibrium state is close to unity near the triple point temperature of the bulk liquid, and decreases gradually as the temperature rises. The velocity distribution of molecules evaporating into vacuum becomes nearly half-Maxwellian near the triple point temperature, and is deformed as the temperature rises.
Wavelet Multi-Resolution Image Analysis on a Jet Issuing From Rotating Inclined Section
Authors: Nakashima Masahiro , Tabata Takahide , Li Hui , Nozaki Tsutomu
Published: February 2009

The water jet flow issuing from the rotating circular pipe with the inclined section has been studied by the method of the flow visualization and the wavelet multi-resolution method. Three-dimensional views of large-scale structure in the jet cross-section were constructed by applying a volume rendering method to the images of the sum of wavelet levels 1 and 2 in layers in the wavelet multi-resolution analysis. In order to clarify the change with the time of the jet diffusion, the large-scale structure has been investigated in the cases of various inclined angles of the section and rotating speeds of the pipe. As a result, it has been found that the jet diffusion is affected by the inclined angle and the rotating speed of the pipe.
Analysis of PIV Image Using Modal Wavelet Transform: Proposal of a Modal Wavelet Transform and Application to PIV Image Analysis
Authors: Yamazaki Teruyoshi , Takei Masahiro , Hassan Yassin A. , Villafuerte Javier Ortiz , Saito Yoshifuru , Horii Kiyoshi
Published: February 2009

Particle image velocimetry (PIV) vector image data of a uniform flow and of arbitrary length is decomposed using a new modal wavelet transform with both Dirichlet and Neumann boundary conditions. The Neumann boundary condition is found to be most suitable for PIV vector image data of a uniform flow. It is also found that when the summation of multi-resolution data is performed for more than 10 levels, the number and severity of error vector increases.
Visualization Study on the Mechanism of Clusters Formation of ER Fluid in a Cylindrical ER Clutch
Authors: Kim Dae-Young , Park Myeong-Kwan , Yamane Ryuichiro , Oshima Shuzo
Published: February 2009

Since interest in ER fluids has increased, recently numerous and quite diverse application fields has been proposed. In the studies concerning devices using ER fluids, the behavior of the fluids has been assumed to be almost that of bingham plastics. Also, many differences have been observed between experimental and theoretical result of application devices. But the behavior of ER fluid differs from bingham plastics in the region of low shear rate. Almost all the research concerning application devices using ER fluids is based on the assumption similarity with bingham plastics. And studies have not been performed in this area because of the nonlinear behavior in the region of low shear rates. In spite of the use of improved control methods, research concerning the application of devices using ER fluids has encountered many problems due to modeling error of the basic governing equations. In this study, the motion of particles of an ER fluid in a cylindrical ER clutch is visualized by video camera in order to examine the mechanism of ER effects under the shear mode. The particle type ER fluid is used in this study. The particle size of ER fluids used in the devices is very small, and the response times are in the range of milliseconds. Hence, ER fluids that have a slow response time, fluids with extremely large particles and low concentration were selected. A cylindrical ER clutch is consists of input and output rotational cylinders and ER fluid between them. The cylinders also serve as electrodes. The torque of a cylindrical ER Clutch/Break is measured by torque meter. And then discuss the behavior of cylindrical ER clutch/Break influenced of the nonlinear behavior of ER fluid through results of visualization. As result, the shear stress of a cylindrical ER Clutch/Break is nonlinear at low shear rate because ER fluid in a cylindrical ER clutch is different to form the cluster according to the strength of electric field.
Three-Dimensional Numerical Analysis for Convection of Air in a Bore Space of a Superconducting Magnet
Authors: Tomita G. , Kaneda M. , Tagawa T. , Ozoe H.
Published: February 2009

Three-dimensional numerical computations were carried out for the natural convection of air in a horizontal cylindrical enclosure in a magnetic field, which is modeled for a bore space of a horizontal superconducting magnet. The enclosure was cooled from the circumferential sidewall at the constant heat flux and vertical end walls were thermally insulated. A strong magnetic field was considered by a one-turn electric coil with the concentric and twice diameter of the cylinder. Without a magnetic field, natural convection occurs along the circumferential sidewall. When a magnetic field was applied, magnetizing force induced the additional convection, that is, the cooled air at the circumferential wall was attracted to the location of a coil. Consequently, the temperature around the coil decreased extensively.
Simulation of Laboratory Jets and Full Scale Exhaust Plumes (Keynote Paper)
Authors: Dash Sanford M.
Published: February 2009

Recent activities at CRAFT Tech related to the simulation of high speed laboratory jets, their control via passive actuation, and the scale-up and revisions required for real engines and operation at flight are discussed. We focus on aircraft applications related to jet noise reduction with activities pertinent to varied missile jet/plume applications the subject of other review papers. Laboratory jet experiments have served to validate the RANS turbulence models utilized and are supplemented by LES studies to provide data sets not readily obtainable in the laboratory such as temperature fluctuation data needed for thermal transport modeling. Applications for a military fighter aircraft indicate that laboratory experiments cannot replicate the real exhaust environment and thus can only suggest actuation concepts that are promising. CFD is required to revise and scale-up these concepts for the real engine and to provide estimates of their performance in flight. Studies presented show the differences between laboratory plumes and real plumes, as well as the effects of plume/plume and plume/aerodynamic interactions which are quite appreciable and show a markedly different structure than that of the isolated jet under the same operating conditions.
Numerical Study on Thermal and Fluid Flow Around the New Type of Micro Flow Sensor
Authors: Yoshida Munehiro , Toda Kazuyuki , Yamamoto Makoto , Kamiunten Shoji , Honami Shinji
Published: February 2009

We design a new type of the micro flow sensor which can detect the wall shear stress and the flow direction. In the new type of the micro flow sensor configuration, the two sensing elements are arrayed on the silicon chip and also used as heater due to a self-heating of the elements for higher frequency response and miniaturization. The flow sensing elements are thermal sensitive thin film resistors fabricated on the silicon chip. The principle of the micro flow sensor is based on the convective heat transfer from the heated resistance to the surrounding fluid. The optimum spacing of the heaters is discussed by the numerical simulation of a two-dimensional low Reynolds number flow including the heat conduction within the chip. In the feasibility study the proposed micro flow sensor with 30% reduction in size is found to have higher sensitivity.
Experiments of Compressible Homogeneous and Isotropic Turbulence Interacting With Expansion Waves
Authors: Xanthos Savvas S. , Andreopoulos Yiannis
Published: February 2009

The interaction of traveling expansion waves with grid-generated turbulence was investigated in a large-scale shock tube research facility. The incident shock and the induced flow behind it passed through a rectangular grid, which generated a nearly homogeneous and nearly isotropic turbulent flow. As the shock wave exited the open end of the shock tube, a system of expansion waves was generated which traveled upstream and interacted with the grid-generated turbulence; a type of interaction free from streamline curvature effects, which cause additional effects on turbulence. In this experiment, wall pressure, total pressure and velocity were measured indicating a clear reduction in fluctuations. The incoming flow at Mach number 0.46 was expanded to a flow with Mach number 0.77 by an applied mean shear of 100 s−1. Although the strength of the generated expansion waves was mild, the effect on damping fluctuations on turbulence was clear. A reduction of in the level of total pressure fluctuations by 20 per cent was detected in the present experiments.
Compressibility Effects in Turbulent Subsonic Jets
Authors: Wang Zhexuan , Andreopoulos Yiannis
Published: February 2009

The behavior of compressible turbulent jets issuing in still air in the absence of shock waves has been investigated at three different subsonic Mach numbers, 0.3, 0.6 and 0.9. Helium, nitrogen and krypton gases were used to generate the jet flows and investigate the density effects on the structure of turbulence. Particle Image Velocimetry and high-frequency response pressure transducers were used to obtain velocity, Mach number inside the flow field. The decay of the Mach number at the centerline of the axisymmetric jets increases with increasing the initial Mach number at the exit of the flow for all jets. The decay of mean velocity at the centerline of the jets is also higher at higher exit Mach numbers. However, the velocity non-dimensionalized by the exit velocity seems to decrease faster at low exit Mach numbers suggesting a reduced mixing with increasing the exit flow Mach numbers. Helium jets were found to have the largest spreading rate among the three different gas jets used in the present investigation, while krypton had the lowest spreading rate. Total pressure fluctuations appear to decrease with increasing exit flow Mach numbers. Unusually high turbulence intensities were measured in helium jets issuing in still air.
Effects of Dimple Size and Depth on Golf Ball Aerodynamic Performance
Authors: Ting L. L.
Published: February 2009

Based on the three-dimensional CFD modeling method reported previously, systematic computational sensitivity studies of how the changes of dimple size, depth, number, coverage area, and distribution pattern will affect the golf ball aerodynamic performance have been made by considering those variables individually and then collectively. By using a new golf ball surface design with 344 identical single-sized circular dimples, but keeping the dimple distribution pattern and the dimple diameter unchanged, the dimple depth effect was first investigated by varying the dimple depressions from shallow to deep, and an optimum value corresponding to minimum drag loss has been found. Using the balls with same optimum dimple depth, drag results show the tendency of decreasing as the dimple diameter increases from small to large until a limit is reached. Beyond this limit, drag coefficient will remain to be a constant even with the further increases of the dimple diameter. Ball drag and lift results obtained and presented are not only for the whole ball, but also separately for the dimple occupied area and the dimple-free cage area. Influence of ball backspin motion to the magnitude of the dimple’s optimum depth value was found to be insignificant. Flow field solutions of velocity vectors, trace lines, pressure, and turbulence intensity have also been obtained, and some are used to show how the changes of dimple depth, dimple diameter, as well as the ball backspin motion, will affect the wake formation behind the ball both in size and shape.
Instability of the Flow in a Mixed-Flow-Type Vaneless Diffuser System
Authors: Tsurusaki Hiromu
Published: February 2009

This study was carried out in order to investigate the unstable flow through a mixed-flow-type vaneless diffuser system. The testing equipment consists of a vaneless diffuser, an inlet pipe, and a swirl flow generator. Pressure fluctuations of the flow through the diffuser were measured. In the experiment, the velocity ratio (axial velocity/peripheral velocity) at the diffuser inlet, diffuser width, inlet pipe length, hub diameter, and mixed flow angle of the diffuser were varied. The internal flow condition existing when the unstable flow occurred is discussed in terms of turbulent flow analysis. The main findings of this study are as follows. The unstable flow is excited when the aforementioned velocity ratio is lowered under a critical value. The source of the unstable flow is the mixed flow vaneless diffuser. The rotational speed of the cell and the intensity of pressure fluctuation are influenced remarkably by diffuser width. The inlet pipe acts as an attenuator for the unstable flow of the diffuser. A prediction equation for rotational speed of the cell is proposed. Prediction of back flow in the diffuser is useful for prediction of the onset of unstable flow. Unstable flow with a fast-speed mode was measured when the diffuser had a small hub and a small mixed flow angle. The fast-speed mode is believed to arise from instability in the inlet pipe system.
Experimental Study on Unstable Characteristics of Mixed-Flow Pump at Low Flow-Rates
Authors: Funakoshi Hiroshi , Tsukamoto Hiroshi , Miyazaki Koji , Miyagawa Kazuyoshi
Published: February 2009

Static and dynamic characteristics of a mixed flow pump were measured at low flow rate, where the steady characteristic curves show a positive slope. Unsteady flow was measured at upstream and downstream of impeller, as well as on the casing wall of diffuser passage by using a fast response five-hole pitot tube and semi-conductor type pressure transducers. Dynamic response of the pump to the sinusoidal change in flow rate was measured under constant rotational speed. As a result of the unsteady flow measurements, the positive slope of steady characteristic was found to be caused by the impeller tip separation, inlet backflow, and pre-rotation. Moreover, the dynamic characteristics of the pump were found to become unstable with the increased frequency of flow rate.
Commercial CFD Code Validation for Simulation of Heavy-Vehicle External Aerodynamics
Authors: Pointer W. David , Sofu Tanju , Weber David
Published: February 2009

The issue of energy economy in transportation has grown beyond traditional concerns over environment, safety and health to include new concerns over national and international security. In collaboration with the U.S. Department of Energy Office of FreedomCAR and Vehicle Technologies’ Working Group on Aerodynamic Drag of Heavy Vehicles, Argonne National Laboratory is investigating the accuracy of aerodynamic drag predictions from commercial Computational Fluid Dynamics (CFD) Software. In this validation study, computational predictions from two commercial CFD codes, Star-CD [1] and PowerFLOW [2], will be compared with detailed velocity, pressure and force balance data from experiments completed in the 7 ft. by 10 ft. wind tunnel at NASA Ames [3, 4] using a Generic Conventional Model (GCM) that is representative of typical current-generation tractor-trailer geometries.
Direct Numerical Simulation of Air Bubbles in Water/Glycerol Mixtures: Shapes and Velocity Fields
Authors: Koebe Mario , Bothe Dieter , Warnecke Hans-Joachim
Published: February 2009

In this paper results of direct numerical simulation (DNS) of bubbles rising in viscous Newtonian liquids with high-density ratio are presented. The simulations are carried out with the highly parallelized code FS3D, which employs the Volume-of-Fluid (VOF) method. The high degree of parallization of the code allows high resolution of the computational domain, such that the Kolmogorov length scale inside the liquid phase is resolved for the simulations. For validation of the numerical results the terminal rise velocities, bubble shapes and flow fields are compared to experimental data as well as to approximate analytical solutions. For high Morton numbers terminal rise velocities and aspect ratios agree very well with experimental values. For lower Morton numbers there is an increasing difference between experimental and numerical rise velocities. The aspect ratios of ellipsoidal bubbles match both with experimental measurements and with theoretical values of Taylor and Acrivos. At very low Reynolds numbers (ReB < 1) the velocity fields in and outside of the bubble show good semi-quantitative agreement with the analytical creeping flow solution of Hadamard and Rybczynski.
Numerical Simulation of Flow Around Melting Object by Lattice Gas Automata Method
Authors: Matsukuma Yosuke , Minemoto Masaki , Abe Yutaka
Published: February 2009

From the view point of effective use of energy resources and reduction of greenhouse gases, methane hydrate has received considerable attention as a promising alternative energy resource. It is important to study effective recovery system of the methane hydrate, since it exists on the seabed at a depth of more than 1000m. The hot water injection method has been proposed as a promising methane hydrate recovery system. In this method, hot water is injected into methane hydrate layer through a pipe, and then molten methane is recovered. In this study, as the first step of the numerical analysis of the multiphase flow through complex boundary changing geometry, a new technique to generate a deformable solid boundary is proposed based on the lattice gas automata method. By using this technique, fundamental numerical simulations are demonstrated for the immiscible two-component flow in two-dimensional systems. Comparisons between simulation and experimental results clarified that the present technique is applicable to the flow of hot water and liquid methane and the disassociation of methane hydrate wall.