bluuebunny/crossref_metadata_2025 huggingface dataset:
Fatigue Properties of Liner Materials Used for 35MPa-Class On-Board Hydrogen Fuel Tanks
Authors: Ohmiya Shinichi , Fujii Hideki
Published: August 2008

To evaluate mechanical properties of the materials used for hydrogen systems such as fuel cell vehicles and hydrogen fuel stations, mechanical testing facilities in gaseous hydrogen at up to 45MPa pressure were newly designed and installed, and fatigue properties, which is one of the key properties for the onboard fuel tanks in the fuel cell vehicles, were actually evaluated for two kinds of liner materials of the on-board CFRP fuel tanks; AA6061-T6 aluminum alloy and 316L type of austenitic stainless steel. Axial S-N fatigue tests (R = −1) were conducted in air and also in gaseous hydrogen at 45MPa pressure at room temperature, and quite similar S-N curves were obtained in both circumstances within the maximum number of cycles to failure of 105 for AA6061-T6. 316L also exhibited excellent fatigue life and was not fractured with maximum applied stress of 90% of 0.2% proof stress at 105 cysles. Clear difference was not observed in fatigue crack growth rate in each material regardless of the circumstances investigated in this study including hydrogen gas at 45MPa pressure. Those results indicate that fatigue properties are not affected by gaseous hydrogen at around room temperature in both AA6061-T6 aluminum alloy and 316L type of stainless steel, and that both materials can fully be employed to the liner of the 35MPa on-board hydrogen fuel tanks from the viewpoints of fatigue properties.
Analysis of the Thermal Fatigue Cracking of 316L Model Pipe Components Under Cyclic Down-Shocks
Authors: Paffumi Elena , Nilsson Karl-Fredrik , Taylor Nigel
Published: August 2008

Cylindrical test pieces of low-carbon austenitic steel 316L are subjected to cyclic thermal loads in a specially designed rig. Intermittent stops allowed measurement of cycles to initiation and of the propagation of the networks of axial and circumferential cracks. These results have been used to validate an analysis procedure, based on a sequentially coupled thermal-stress finite element analysis. It is found that the initiation life can be reliably predicted from the stain range at the inner surface, while a simplified semi-elliptical crack model best described the subsequent crack growth.
Analysis of Gas Freeing of Oil Tankers Using CFD
Authors: Chow Kevin , Holdo̸ Arne E. , Croft Robert J.
Published: August 2008

Current gas-freeing processes on board Very Large Crude Carriers (VLCCs, ships ranging from 160,000 to 320,000 dwt) typically take 2–8 hours depending on the state of the tank. Legislation and practices covering the operations do not account or advise for the varying configurations of the tank leading to potentially inefficient de-gassing of the tank. Through the use of computational fluid dynamics (CFD), it has become possible to examine and analyse the important physical phenomena that governs the de-gassing processes inside the tank. The work presented utilises CFD to visualise the flow interactions of the injected air and the fluid inside the tank in combination with the tank structure. Using these modern techniques, existing gas-freeing methods can be examined with a view to highlighting poor mixing areas. A number if various tank configurations are examined, with respect to size, geometry, vent and fan arrangements. The results are analysed and presented with recommendations.
A New European Commission Initiative on Optimisation of Maintenance in Nuclear Power Plants
Authors: Ahlstrand R. , Bie`th M. , Over H. , Pla P. , Ranguelova V. , Rieg C. , Trampus P.
Published: August 2008

The European Commission has recently launched a new initiative dedicated to Nuclear Safety in Central and Eastern Europe called after “Safety of Eastern European Type Nuclear Facilities” (SENUF). SENUF contributes to bring together all stakeholders of the nuclear safety programs for the Technical Assistance to the Commonwealth of Independent States (TACIS) and the Poland Hungary Aid for Reconstruction of the Economy (PHARE): beneficiaries, end users, Eastern and Western nuclear industries, and thus, to favour fruitful technical exchanges and feedback of experience. At present, the main focus of SENUF is the nuclear power plant maintenance as a substantial element of plant operational safety as well as life management. A dedicated Working Group has been established on plant maintenance. 10 members have joined in the starting period. After a thematic introduction the paper discusses the maintenance optimisation general aspects and current activities in the CIS and CEEC, the paper presents SENUF and reports about the first activities developed within the working group One of its major tasks in 2004 was to prepare a status report on advanced strategies to optimise maintenance. Optimisation projects have an interface with the plant’s overall life management program. Today, almost all plants belonging to SENUF members have an explicit policy to extend their service life. Thus, component ageing management, modernisation and refurbishment actions became much more important. Preliminary results of the extended inquiry are already available which show a rather homogeneous propagation of techniques and methods in general. A web-enabled database has been developed to provide maintenance managers and engineers with adequate information on “Advanced and Special Equipment, Tools, Materials and Processes” in order to help them selecting the most appropriate and cost efficient solution for their maintenance needs. Information about the existence, the main parameters of such equipment and the experience of their usage that can be valuable for others facing similar problems, will be shared through easy access by members. Currently, the activity is starting to develop into the area of Reliability-Centred and Risk-Informed Maintenance, taking benefit from cooperation with the IAEA. Further extension of the memberships is expected in the near future.
Flaw Proximity Rules for Parallel Planar Flaws Under Limit Load Conditions
Authors: Ranganath Sam , Carter Bob , Ku Francis , Herrera Marcos
Published: August 2008

This paper describes the evaluation of adjacent cracks (including parallel cracks in different planes) from a limit load perspective. The proposed approach complements the current ASME Code rules that are largely based on linear elastic fracture mechanics considerations. The evaluation considers limit load analysis and is validated by comparison with test data. In particular the paper provides criteria to determine load capability of structures with offset cracks in parallel planes. The objective of the work was to provide criteria for the evaluation of reactor internals, but the results can be applied to evaluate cracking in ductile pressure boundary piping also.
Acoustic Emission Testing of a Process Reactor
Authors: Yuen Simon , Wang David , Benedictus Paul
Published: August 2008

An Acoustic Emission Test (AET) was performed on a hydrocarbon processing reactor to inspect for environmental cracking in 2000. The thick-wall reactor was built in 1965, fabricated from 2.25Cr-1Mo steel with Type 347 stainless steel weld overlay. Past internal inspections of the reactor using liquid penetrant had revealed cracking at internal ring supports. Such inspections were exhaustive and time consuming. The AET was performed to achieve 100% inspection coverage of the reactor and to identify suspect areas for further evaluation. The test included over-pressurization of the reactor to 10% above its operating pressure before the shutdown and the actual cooling of the reactor from 745°F to 300°F. Upon completion of the acoustic emission (AE) monitoring, significant indications were identified, most noticeably at the reactor dump nozzle and the bottom head to shell weld. Both of these were in areas that had not been inspected previously. Follow-up inspections, including external ultrasonic and internal liquid penetrant test, were performed to investigate all the areas of significant AE activities. The results showed internal cracks isolated to the weld overlay at the catalyst dump nozzle and a 12” long weld slag inclusion in the bottom head to shell weld. A methodology was developed also to evaluation criticality of AE signals during different stages of AE test.
ANO-2 Experiences Using Structural Tools During License Renewal Application
Authors: Ahrabli Reza
Published: August 2008

Arkansas Nuclear One, Unit 2 (ANO-2) submitted an application to the Nuclear Regulatory Commission (NRC) to extend its operating license for an additional 20 years on October 15, 2003. NRC regulations governing the license renewal process require the preparation of an Integrated Plant Assessment (IPA) to demonstrate that the effects of aging on systems, structures and components (SSCs) at ANO-2 are adequately managed. ANO participated in the B&W (now AREVA) Owners Group (BWOG) Generic License Renewal Program (GLRP) in developing the BWOG “Aging Effects for Structures and Structural Components”, commonly referred to as “Structural Tools”. The Structural Tools is a generic evaluation based on material and environments that assist the user in performing an evaluation of aging effects. Using the Tools, considerable time was saved in preparing Aging Management Review Reports (AMRR) since the reviewer did not have to independently research potential causes of aging effects for the materials and environments being reviewed. This paper summarizes the ANO-2 experiences in preparing AMRRs utilizing the Structural Tools.
ENPOWER: Investigations by Neutron Diffraction and Finite Element Analyses on Residual Stress Formation in Repair Welds Applied to Ferritic Steel Plates
Authors: Ohms Carsten , Wimpory Robert C. , Neov Dimitar , Lawrjaniec Didier , Youtsos Anastasius G.
Published: August 2008

The European collaborative research project ENPOWER (Management of Nuclear Plant Operation by Optimizing Weld Repairs) has as one of its main objectives the development of guidelines for the application of repair welds to safety critical components in nuclear power plants. In this context letter box repair welds applied to thin ferritic steel plates to simulate repair of postulated shallow cracks have been manufactured for the purpose of experimental and numerical analysis of welding residual stresses. Two specimens have been procured, one of them prepared in accordance with a standard welding procedure, while in the second case a different procedure was followed in order to obtain extended martensite formation in the heat affected zone. Residual stresses have been determined in both specimens by neutron diffraction at the High Flux Reactor of the Joint Research Centre in Petten, The Netherlands. In parallel Institut de Soudure in France has performed a full 3-d analysis of the residual stress field for the standard welding case taking into account the materials and phase transformations. The experimental data obtained for both specimens clearly suggest that the non-conventional welding procedure rendered higher maximum stress values. In the case of the standard welding procedure numerical and experimental data show a reasonable qualitative agreement. The maximum stress value was in both cases found in the same region of the material — in the base metal just underneath the weld pool — and in both cases found to be of similar magnitude (∼800 MPa found in neutron diffraction and ∼700 MPa found in numerical analysis). In this paper the experimental and numerical approaches are outlined and the obtained results are presented. In addition an outlook is given to future work to be performed on this part of the ENPOWER project. A main issue pending is the application of an optimized advanced post weld heat treatment in one of the two cases and the subsequent numerical and experimental determination of its impact on the residual stress field. At the same time further evaluation of the materials transformations due to welding is pursued.
An Overview of Hydrogen Station and Systems Interface
Authors: Gromis Adams
Published: August 2008

Introducing principal components and systems for the Hydrogen Station, comprised of hydrogen generator, auxiliary equipment, hydrogen piping and distribution, hydrogen strorage, compressed hydrogen dispenser and vehicle interface.
Flexible cue use in nonnative phonetic categorization
Authors: Broersma Mirjam
Published: August 2008

Native and nonnative listeners categorized final /v/ versus /f/ in English nonwords. Fricatives followed phonetically long (originally /v/-preceding) or short (originally /f/-preceding) vowels. Vowel duration was constant for each participant and sometimes mismatched other voicing cues. Previous results showed that English but not Dutch listeners (whose L1 has no final voicing contrast) nevertheless used the misleading vowel duration for /v/-/f/ categorization. New analyses showed that Dutch listeners did use vowel duration initially, but quickly reduced its use, whereas the English listeners used it consistently throughout the experiment. Thus, nonnative listeners adapted to the stimuli more flexibly than native listeners did.
The Herschel–Quincke tube: The attenuation conditions and their sensitivity to mean flow
Authors: Karlsson Mikael , Glav Ragnar , Åbom Mats
Published: August 2008

The classic Herschel–Quincke tube is a parallel connection of two ducts yielding multiple noise attenuation maxima via destructive interference. This problem has been discussed to different degrees by a number of authors over the years. This study returns to the basics of the system for the purpose of furthering the understanding of the conditions necessary for noise attenuation and especially their sensitivity to mean flow. First, the transmission loss for an N-duct system with mean flow and arbitrary conditions of state in the different ducts is derived. Next, the two types of conditions yielding the attenuation maxima are studied. In addition to a discussion of the underlying physics, generic expressions for frequencies at which maximum attenuation occur are presented. Experiments without mean flow generally show good agreement with theory based on straight duct elements. However, more detailed models may be required for accurate simulations in the presence of mean flow. A simple model compensating for the losses associated with bends is shown to improve the results significantly for the geometry studied.
The combined effects of reverberation and nonstationary noise on sentence intelligibility
Authors: George Erwin L. J. , Festen Joost M. , Houtgast Tammo
Published: August 2008

Listening conditions in everyday life typically include a combination of reverberation and nonstationary background noise. It is well known that sentence intelligibility is adversely affected by these factors. To assess their combined effects, an approach is introduced which combines two methods of predicting speech intelligibility, the extended speech intelligibility index (ESII) and the speech transmission index. First, the effects of reverberation on nonstationary noise (i.e., reduction of masker modulations) and on speech modulations are evaluated separately. Subsequently, the ESII is applied to predict the speech reception threshold (SRT) in the masker with reduced modulations. To validate this approach, SRTs were measured for ten normal-hearing listeners, in various combinations of nonstationary noise and artificially created reverberation. After taking the characteristics of the speech corpus into account, results show that the approach accurately predicts SRTs in nonstationary noise and reverberation for normal-hearing listeners. Furthermore, it is shown that, when reverberation is present, the benefit from masker fluctuations may be substantially reduced.
Tuning in the spatial dimension: Evidence from a masked speech identification task
Authors: Marrone Nicole , Mason Christine R. , Kidd Gerald
Published: August 2008

Spatial release from masking was studied in a three-talker soundfield listening experiment. The target talker was presented at 0° azimuth and the maskers were either colocated or symmetrically positioned around the target, with a different masker talker on each side. The symmetric placement greatly reduced any “better ear” listening advantage. When the maskers were separated from the target by ±15°, the average spatial release from masking was 8dB. Wider separations increased the release to more than 12dB. This large effect was eliminated when binaural cues and perceived spatial separation were degraded by covering one ear with an earplug and earmuff. Increasing reverberation in the room increased the target-to-masker ratio (T∕M) for the separated, but not colocated, conditions reducing the release from masking, although a significant advantage of spatial separation remained. Time reversing the masker speech improved performance in both the colocated and spatially separated cases but lowered T∕M the most for the colocated condition, also resulting in a reduction in the spatial release from masking. Overall, the spatial tuning observed appears to depend on the presence of interaural differences that improve the perceptual segregation of sources and facilitate the focus of attention at a point in space.
Sound transmission at ground level in a short-grass prairie habitat and its implications for long-range communication in the swift fox Vulpes velox
Authors: Darden Safi K. , Pedersen Simon B. , Larsen Ole N. , Dabelsteen Torben
Published: August 2008

The acoustic environment of swift foxes Vulpes velox vocalizing close to the ground and the effect of propagation on individual identity information in vocalizations were quantified in a transmission experiment in prairie habitat. Sounds were propagated (0.45m above the ground) at distances up to 400m. Effects of transmission were measured on three sound types: synthesized sweeps with 1.3kHz bandwidths spanning in the range of 0.3–8.0kHz; single elements of swift fox barking sequences (frequency range of 0.3–4.0kHz) and complete barking sequences. Synthesized sweeps spanning 0.3–1.6 and 1.2–2.5kHz propagated the furthest and the latter sweeps exhibited the best transmission properties for long-range propagation. Swift fox barking sequence elements are centered toward the lower end of this frequency range. Nevertheless, measurable individual spectral characteristics of the barking sequence seem to persist to at least 400m. Individual temporal features were very consistent to at least 400m. The communication range of the barking sequences is likely to be farther than 400m and it should be considered a long-ranging vocalization. However, relative to the large home ranges of swift foxes (up to 16km2 in the experimental area) the barking sequence probably functions at intermediate distances.
Harbor porpoise clicks do not have conditionally minimum time bandwidth product
Authors: Beedholm Kristian
Published: August 2008

The hypothesis that odontocete clicks have minimal time frequency product given their delay and center frequency values is tested by using an in-phase averaged porpoise click compared with a pure tone weighted with the same envelope. These signals have the same delay and the same center frequency values but the time bandwidth product of the artificial click is only 0.76 that of the original. Therefore signals with the same parameters exist that have a lower time bandwidth product. The observation that porpoise clicks are in fact minimum phase is confirmed for porpoise clicks and this property is argued to be incompatible with optimal reception, if auditory filters are also minimum phase.
Ultrasound attenuation estimation using backscattered echoes from multiple sources
Authors: Bigelow Timothy A.
Published: August 2008

The objective of this study was to devise an algorithm that can accurately estimate the attenuation along the propagation path (i.e., the total attenuation) from backscattered echoes. It was shown that the downshift in the center frequency of the backscattered ultrasound echoes compared to echoes obtained in a water bath was calculated to have the form Δf=mfo+b after normalizing with respect to the source bandwidth where m depends on the correlation length, b depends on the total attenuation, and fo is the center frequency of the source as measured from a reference echo. Therefore, the total attenuation can be determined independent of the scatterer correlation length by measuring the downshift in center frequency from multiple sources (i.e., different fo) and fitting a line to the measured shifts versus fo. The intercept of the line gives the total attenuation along the propagation path. The calculations were verified using computer simulations of five spherically focused sources with 50% bandwidths and center frequencies of 6, 8, 10, 12, and 14MHz. The simulated tissue had Gaussian scattering structures with effective radii of 25μm placed at a density of 250∕mm3. The attenuation of the tissue was varied from 0.1to0.9dB∕cm-MHz. The error in the attenuation along the propagation path ranged from −3.5±14.7% for a tissue attenuation of 0.1dB∕cm-MHz to −7.0±3.1% for a tissue attenuation of 0.9dB∕cm-MHz demonstrating that the attenuation along the propagation path could be accurately determined using backscattered echoes from multiple sources using the derived algorithm.
Information theoretic approaches to ultrasonic system design: Beamforming with interative spatial filters.
Authors: Nguyen Nghia , Abbey Craig , Insana Michael
Published: August 2008

First-principles approaches to the design of medical ultrasonic imaging systems for specific visual tasks are being explored. The study focuses on breast cancer diagnosis and is based on the ideal observer concept for visual discrimination tasks, whereby clinical tasks are expressed mathematically as likelihood functions. Realistic approximations to the ideal strategy for each visual task are proposed to maximize the diagnostic information content of the images. Based on previous studies [Abbey et al., IEEE Trans. Med. Imaging 25, 198–209 (2006)], it is known that the Wiener filter approach to beamforming, derived as a stationary approximation of the ideal observer, is limited for low-contrast, large area lesion discrimination. In this study an adaptive iterative Wiener filter coupled to a segmentation algorithm is developed to optimally beamform and process radio-frequency (rf) signals. The segmentation is achieved by applying a Markov random field approach. Performance is measured by comparing proportion correct in human-observer studies with the ideal observer and its approximations as required for an estimate of discrimination efficiency. It is found that by adapting to local statistical properties of the rf signal the iterative Wiener filter increases visual discrimination efficiency where the Wiener filter and conventional beamformers fail. [Work supported by the NCI/NIH.]
Sam’s early work on the sea turtle.
Authors: Fay Richard
Published: August 2008

I first met Sam Ridgway in 1967 or 1968 before he had become “the dolphin doctor.” He was a visiting scientist at the E.G. Wever’s Laboratory at Princeton, NJ and I was a new Ph.D. student. He had already done the classic experiments on the dolphin ear with Wever, McCormick, and Palin (1970, 1971, 1972, and 1974), never to be repeated in the same way. He was there to study hearing in the sea turtle (Chelonia mydas) using cochlear potentials. This was also the last of these kinds of experiments on these charismatic animals. Wever was most interested at the time in the reptile ear and had a swimming pool installed at the laboratory for them. The publication that resulted was that of Ridgway et al. [“Hearing in the giant sea turtle, Chelonia mydas,” Proc. Natl. Acad. Sci. U.S.A. 64, 884–890 (1969)]. It stands as the best information we have on sea turtle hearing, with an indication of sensitivity and a frequency response function. The only better information would be a behavioral audiogram, which is yet to be done. This early chapter in Sam’s career is vitally important today with respect to the setting of sound exposure criteria for fish and turtles.
Tumor Suppressor Foxo3a Is Involved in the Regulation of Lipopolysaccharide-Induced Interleukin-8 in Intestinal HT-29 Cells
Authors: Snoeks Lobke , Weber Christopher R. , Turner Jerrold R. , Bhattacharyya Mitra , Wasland Kaarin , Savkovic Suzana D.
Published: August 2008

Enteric bacteria and their products play an important role in intestinal inflammation; however, the complete mechanisms are not elucidated yet. Tumor suppressor Foxo3a regulates gene expression in the nucleus, and its translocation to the cytosol leads to inactivation. Proximally, Foxo3a is regulated by different pathways including the phosphoinositide 3-kinase (PI3K) pathway. The aim of this study was to determine the effect of bacterial infection on Foxo3a in intestinal epithelial cells and to examine the contribution of Foxo3a in intestinal inflammation. Bacterial lipopolysaccharide (LPS) and infection with mouse pathogenCitrobacter rodentiuminduce translocation of the nuclear Foxo3a into the cytosol, where it degrades in human HT-29 and mouse CMT-93 cells. In colonic epithelia of healthy mice, Foxo3a is localized in the epithelia at the bottom of the crypts in both the nucleus and the cytosol, while inC. rodentium-infected colon Foxo3a is expressed along the crypts and located mainly in the cytosol, suggesting its inactivation. LPS utilized the PI3K pathway to inhibit Foxo3a. Additionally, inhibition of PI3K attenuated LPS-induced proinflammatory interleukin-8 (IL-8). LPS-induced IL-8 is increased in HT-29 cells with silenced Foxo3a. Moreover, in HT-29 cells with silenced Foxo3a, the amount of IκBα, an NF-κB inhibitor, is decreased. In conclusion, LPS and bacterial infection inactivate Foxo3a in intestinal epithelia via the PI3K pathway and inactivated Foxo3a leads to the upregulation of IL-8 by suppressing inhibitory IκBα.
Binding of theStreptococcus gordoniiDL1 Surface Protein Hsa to the Host Cell Membrane Glycoproteins CD11b, CD43, and CD50
Authors: Urano-Tashiro Yumiko , Yajima Ayako , Takashima Eizo , Takahashi Yukihiro , Konishi Kiyoshi
Published: August 2008

Infective endocarditis is frequently attributed to oral streptococci. The mechanisms of pathogenesis, however, are not well understood, although interaction between streptococci and phagocytes are thought to be very important. A highly expressed surface component ofStreptococcus gordonii, Hsa, which has sialic acid-binding activity, contributes to infective endocarditis in vivo. In the present study, we found thatS. gordoniiDL1 binds to HL-60 cells differentiated into monocytes, granulocytes, and macrophages. Using a glutathioneS-transferase (GST) fusion to the NR2 domain, which is the sialic acid-binding region of Hsa, we confirmed that the Hsa NR2 domain also binds to differentiated HL-60 cells. To identify which sialoglycoproteins on the surface of differentiated HL-60 cells are receptors for Hsa, intrinsic membrane proteins were assessed by bacterial overlay and far-Western blotting.S. gordoniiDL1 adhered to 100- to 150-kDa proteins, a reaction that was abolished by neuraminidase treatment. These sialoglycoproteins were identified as CD11b, CD43, and CD50 by GST pull-down assay and immunoprecipitation with each specific monoclonal antibody. These data suggest thatS. gordoniiDL1 Hsa specifically binds to three glycoproteins as receptors and that this interaction may be the initial bacterial binding step in infective endocarditis by oral streptococci.
Haemophilus ducreyi
LspA Proteins Are Tyrosine Phosphorylated by Macrophage-Encoded Protein Tyrosine Kinases
Authors: Deng Kaiping , Mock Jason R. , Greenberg Steven , van Oers Nicolai S. C. , Hansen Eric J.
Published: August 2008

The LspA proteins (LspA1 and LspA2) of
Haemophilus ducreyi
are necessary for this pathogen to inhibit the phagocytic activity of macrophage cell lines, an event that can be correlated with a reduction in the level of active Src family protein tyrosine kinases (PTKs) in these eukaryotic cells. During studies investigating this inhibitory mechanism, it was discovered that the LspA proteins themselves were tyrosine phosphorylated after wild-type
H. ducreyi
cells were incubated with macrophages. LspA proteins in cell-free concentrated
H. ducreyi
culture supernatant fluid could also be tyrosine phosphorylated by macrophages. This ability to tyrosine phosphorylate the LspA proteins was not limited to immune cell lineages but could be accomplished by both HeLa and COS-7 cells. Kinase inhibitor studies with macrophages demonstrated that the Src family PTKs were required for this tyrosine phosphorylation activity. In silico methods and site-directed mutagenesis were used to identify EPIYG and EPVYA motifs in LspA1 that contained tyrosines that were targets for phosphorylation. A total of four tyrosines could be phosphorylated in LspA1, with LspA2 containing eight predicted tyrosine phosphorylation motifs. Purified LspA1 fusion proteins containing either the EPIYG or EPVYA motifs were shown to be phosphorylated by purified Src PTK in vitro. Macrophage lysates could also tyrosine phosphorylate the LspA proteins and an LspA1 fusion protein via a mechanism that was dependent on the presence of both divalent cations and ATP. Several motifs known to interact with or otherwise affect eukaryotic kinases were identified in the LspA proteins.
Application of Statistical Power Analysis to the Oregon Coho Salmon (Oncorhynchus kisutch) Problem
Authors: Peterman Randall M.
Published: August 2008

Nickelson (1986; Can. J. Fish. Aquat. Sci. 43: 527–535) was unable to reject the null hypothesis (Ho) of density-independent marine survival rate for Oregon coho salmon (Oncorhynchus kisutch) when wild, private hatchery, and public hatchery stocks were analyzed separately. Thus, even though there appears to have been no consistent increase in adult abundance in recent years in spite of large increases in smolt abundance, Nickelson's analysis does not support the alternative hypothesis (HA) of density-dependent marine survival. Some fishery managers are using Nickelson's results to support proposals to increase smolt production further. I calculated statistical power for these cases, i.e. the probability that the null hypothesis of density-independence could have been rejected, even if marine survival were truly density-dependent. Power was below 0.19 for all cases, which meant that Nickelson (1986) had at least an 81% chance of making a Type II error (incorrectly accepting Ho), if Ho was actually false. Therefore, Oregon fishery managers should be cautious about making decisions on increased smolt production based on current data; they run a high risk of mistakenly assuming density-independent marine survival. More generally, managers should not take action based on a failure to reject a null hypothesis unless power is high.
ASTROD AND ASTROD I — OVERVIEW AND PROGRESS
Authors: NI WEI-TOU
Published: August 2008

In this paper, we present an overview of ASTROD (Astrodynamical Space Test of Relativity using Optical Devices) and ASTROD I mission concepts and studies. The missions employ deep-space laser ranging using drag-free spacecraft to map the gravitational field in the solar-system. The solar-system gravitational field is determined by three factors: the dynamic distribution of matter in the solar system; the dynamic distribution of matter outside the solar system (galactic, cosmological, etc.) and gravitational waves propagating through the solar system. Different relativistic theories of gravity make different predictions of the solar-system gravitational field. Hence, precise measurements of the solar-system gravitational field test these relativistic theories, in addition to gravitational wave observations, determination of the matter distribution in the solar-system and determination of the observable (testable) influence of our galaxy and cosmos. The tests and observations include: (i) a precise determination of the relativistic parameters β and γ with 3–5 orders of magnitude improvement over previous measurements; (ii) a 1–2 order of magnitude improvement in the measurement of G; (iii) a precise determination of any anomalous, constant acceleration Aadirected towards the Sun; (iv) a measurement of solar angular momentum via the Lense-Thirring effect; (v) the detection of solar g-mode oscillations via their changing gravity field, thus, providing a new eye to see inside the Sun; (vi) precise determination of the planetary orbit elements and masses; (vii) better determination of the orbits and masses of major asteroids; (viii) detection and observation of gravitational waves from massive black holes and galactic binary stars in the frequency range 50 μHz to 5 mHz; and (ix) exploring background gravitational waves. The baseline scheme of ASTROD is to have two spacecraft in separate solar orbits and one spacecraft near the Earth–Sun L1/L2 point carrying a payload of a proof mass, two telescopes, two 1–2 W lasers with spares, a clock and a drag-free system ranging coherently among one another using lasers. ASTROD I is a first step towards ASTROD. Its scheme is to have one spacecraft in a Venus-gravity-assisted solar orbit, ranging optically with ground stations with less ambitious, but still significant scientific goals.
SUPERMASSIVE BLACK HOLE MASSES FOR BLAZARS
Authors: FAN JUN-HUI , YUAN YU-HAI , ZHANG JIANG-SHUI , YANG JIANG-HE
Published: August 2008

In this work, we determine the central black hole mass for a sample of blazars including 30 γ-ray loud blazars with available variability timescales. The γ-ray energy, the emission size and the property of a two-temperature accretion disk are used to determine the absorption depth. If we take the intrinsic γ-ray luminosity to be λ times the Eddington luminosity, i.e. [Formula: see text], then we have following results: the masses of the black hole are in the range of 0.59 ~ 67.99 × 107M⊙(λ = 1.0) or 0.90 ~ 104.13 × 107M⊙(λ = 0.1). Blazars are also discussed.
DO LANGUAGE CHANGE RATES DEPEND ON POPULATION SIZE?
Authors: WICHMANN SØREN , STAUFFER DIETRICH , SCHULZE CHRISTIAN , HOLMAN ERIC W.
Published: August 2008

An earlier study [24] concluded, based on computer simulations and some inferences from empirical data, that languages will change the more slowly the larger the population gets. We replicate this study using a more complete language model for simulations (the Schulze model combined with a Barabási–Albert network) and a richer empirical dataset [12]. Our simulations show either a negligible or a strong dependence of language change on population sizes, depending on the parameter settings; while empirical data, like some of the simulations, show a negligible dependence.
LINEAR ORDER AS A PREDICTOR OF WORD ORDER REGULARITIES
Authors: CYSOUW MICHAEL
Published: August 2008

This is a reply to Ramon Ferrer-I-Cancho's paper in this issue "Some Word Order Biases from Limited Brain Resources: A Mathematical Approach." In this reply, I challenge the Euclidean distance model proposed in that paper by proposing a simple alternative model based on linear ordering.
A POPULATION MODEL OF THE STABILITY–FLEXIBILITY TRADEOFF
Authors: VOORHEES BURTON , SENEZ JOSEPH , KEELER TODD , CONNORS MARTIN
Published: August 2008

We present a population model illustrating the concept of virtual stability, i.e. the idea that complex adaptive systems with the capacity for self-monitoring and adaptive control are able to maintain themselves in states that would otherwise be unstable. The advantage gained from this is increased behavioral flexibility in the face of random environmental perturbations. In the model presented, transition probabilities between three population types are used to emulate stability: stable types have low probabilities of making transitions to other types, and unstable types have high transition probabilities. The model itself consists of two stable types and one unstable type, and conditions are explored that lead to dominance by the unstable type. Under certain conditions the unstable type can defeat a stable type, even in an environment that always favors the stable type.
Finding paths through the world's photos
Authors: Snavely Noah , Garg Rahul , Seitz Steven M. , Szeliski Richard
Published: August 2008

When a scene is photographed many times by different people, the viewpoints often cluster along certain paths. These paths are largely specific to the scene being photographed, and follow interesting regions and viewpoints. We seek to discover a range of such paths and turn them into controls for image-based rendering. Our approach takes as input a large set of community or personal photos, reconstructs camera viewpoints, and automatically computes orbits, panoramas, canonical views, and optimal paths between views. The scene can then be interactively browsed in 3D using these controls or with six degree-of-freedom free-viewpoint control. As the user browses the scene, nearby views are continuously selected and transformed, using control-adaptive reprojection techniques.
BSGP
Authors: Hou Qiming , Zhou Kun , Guo Baining
Published: August 2008

We present BSGP, a new programming language for general purpose computation on the GPU. A BSGP program looks much the same as a sequential C program. Programmers only need to supply a bare minimum of extra information to describe parallel processing on GPUs. As a result, BSGP programs are easy to read, write, and maintain. Moreover, the ease of programming does not come at the cost of performance. A well-designed BSGP compiler converts BSGP programs to kernels and combines them using optimally allocated temporary streams. In our benchmark, BSGP programs achieve similar or better performance than well-optimized CUDA programs, while the source code complexity and programming time are significantly reduced. To test BSGP's code efficiency and ease of programming, we implemented a variety of GPU applications, including a highly sophisticated X3D parser that would be extremely difficult to develop with existing GPU programming languages.
Clone attack! Perception of crowd variety
Authors: McDonnell Rachel , Larkin Michéal , Dobbyn Simon , Collins Steven , O'Sullivan Carol
Published: August 2008

When simulating large crowds, it is inevitable that the models and motions of many virtual characters will be cloned. However, the perceptual impact of this trade-off has never been studied. In this paper, we consider the ways in which an impression of variety can be created and the perceptual consequences of certain design choices. In a series of experiments designed to test people's perception of variety in crowds, we found that clones of appearance are far easier to detect than motion clones. Furthermore, we established that cloned models can be masked by color variation, random orientation, and motion. Conversely, the perception of cloned motions remains unaffected by the model on which they are displayed. Other factors that influence the ability to detect clones were examined, such as proximity, model type and characteristic motion. Our results provide novel insights and useful thresholds that will assist in creating more realistic, heterogeneous crowds.
Hair photobooth
Authors: Paris Sylvain , Chang Will , Kozhushnyan Oleg I. , Jarosz Wojciech , Matusik Wojciech , Zwicker Matthias , Durand Frédo
Published: August 2008

We accurately capture the shape and appearance of a person's hairstyle. We use triangulation and a sweep with planes of light for the geometry. Multiple projectors and cameras address the challenges raised by the reflectance and intricate geometry of hair. We introduce the use of structure tensors to infer the hidden geometry between the hair surface and the scalp. Our triangulation approach affords substantial accuracy improvement and we are able to measure elaborate hair geometry including complex curls and concavities. To reproduce the hair appearance, we capture a six-dimensional reflectance field. We introduce a new reflectance interpolation technique that leverages an analytical reflectance model to alleviate cross-fading artifacts caused by linear methods. Our results closely match the real hairstyles and can be used for animation.
Interactive relighting of dynamic refractive objects
Authors: Sun Xin , Zhou Kun , Stollnitz Eric , Shi Jiaoying , Guo Baining
Published: August 2008

We present a new technique for interactive relighting of dynamic refractive objects with complex material properties. We describe our technique in terms of a rendering pipeline in which each stage runs entirely on the GPU. The rendering pipeline converts surfaces to volumetric data, traces the curved paths of photons as they refract through the volume, and renders arbitrary views of the resulting radiance distribution. Our rendering pipeline is fast enough to permit interactive updates to lighting, materials, geometry, and viewing parameters without any precomputation. Applications of our technique include the visualization of caustics, absorption, and scattering while running physical simulations or while manipulating surfaces in real time.
Data-driven enhancement of facial attractiveness
Authors: Leyvand Tommer , Cohen-Or Daniel , Dror Gideon , Lischinski Dani
Published: August 2008

When human raters are presented with a collection of shapes and asked to rank them according to their aesthetic appeal, the results often indicate that there is a statistical consensus among the raters. Yet it might be difficult to define a succinct set of rules that capture the aesthetic preferences of the raters. In this work, we explore a data-driven approach to aesthetic enhancement of such shapes. Specifically, we focus on the challenging problem of enhancing the aesthetic appeal (or the
attractiveness
) of human faces in frontal photographs (portraits), while maintaining close similarity with the original.

The key component in our approach is an automatic facial attractiveness engine trained on datasets of faces with accompanying facial attractiveness ratings collected from groups of human raters. Given a new face, we extract a set of distances between a variety of facial feature locations, which define a point in a high-dimensional "face space". We then search the face space for a nearby point with a higher predicted attractiveness rating. Once such a point is found, the corresponding facial distances are embedded in the plane and serve as a target to define a 2D warp field which maps the original facial features to their adjusted locations. The effectiveness of our technique was experimentally validated by independent rating experiments, which indicate that it is indeed capable of increasing the facial attractiveness of most portraits that we have experimented with.
Skeleton extraction by mesh contraction
Authors: Au Oscar Kin-Chung , Tai Chiew-Lan , Chu Hung-Kuo , Cohen-Or Daniel , Lee Tong-Yee
Published: August 2008

Extraction of curve-skeletons is a fundamental problem with many applications in computer graphics and visualization. In this paper, we present a simple and robust skeleton extraction method based on mesh contraction. The method works directly on the mesh domain, without pre-sampling the mesh model into a volumetric representation. The method first contracts the mesh geometry into zero-volume skeletal shape by applying implicit Laplacian smoothing with global positional constraints. The contraction does not alter the mesh connectivity and retains the key features of the original mesh. The contracted mesh is then converted into a 1D curve-skeleton through a connectivity surgery process to remove all the collapsed faces while preserving the shape of the contracted mesh and the original topology. The centeredness of the skeleton is refined by exploiting the induced skeleton-mesh mapping. In addition to producing a curve skeleton, the method generates other valuable information about the object's geometry, in particular, the skeleton-vertex correspondence and the local thickness, which are useful for various applications. We demonstrate its effectiveness in mesh segmentation and skinning animation.
Two-way coupling of fluids to rigid and deformable solids and shells
Authors: Robinson-Mosher Avi , Shinar Tamar , Gretarsson Jon , Su Jonathan , Fedkiw Ronald
Published: August 2008

We propose a novel solid/fluid coupling method that treats the coupled system in a fully implicit manner making it stable for arbitrary time steps, large density ratios, etc. In contrast to previous work in computer graphics, we derive our method using a simple back-of-the-envelope approach which lumps the solid and fluid momenta together, and which we show exactly conserves the momentum of the coupled system. Notably, our method uses the standard Cartesian fluid discretization and does not require (moving) conforming tetrahedral meshes or ALE frameworks. Furthermore, we use a standard Lagrangian framework for the solid, thus supporting arbitrary solid constitutive models, both implicit and explicit time integration, etc. The method is quite general, working for smoke, water, and multiphase fluids as well as both rigid and deformable solids, and both volumes and thin shells. Rigid shells and cloth are handled automatically without special treatment, and we support fully one-sided discretizations without leaking. Our equations are fully symmetric, allowing for the use of fast solvers, which is a natural result of properly conserving momentum. Finally, for simple explicit time integration of rigid bodies, we show that our equations reduce to form similar to previous work via a single block Gaussian elimination operation, but that this approach scales poorly, i.e. as though four spatial dimensions rather than three.
Inverse texture synthesis
Authors: Wei Li-Yi , Han Jianwei , Zhou Kun , Bao Hujun , Guo Baining , Shum Heung-Yeung
Published: August 2008

The quality and speed of most texture synthesis algorithms depend on a 2D input sample that is small and contains enough texture variations. However, little research exists on how to acquire such sample. For homogeneous patterns this can be achieved via manual cropping, but no adequate solution exists for inhomogeneous or
globally varying
textures, i.e. patterns that are local but not stationary, such as rusting over an iron statue with appearance conditioned on varying moisture levels.

We present
inverse texture synthesis
to address this issue. Our inverse synthesis runs in the opposite direction with respect to traditional forward synthesis: given a large globally varying texture, our algorithm automatically produces a small texture compaction that best summarizes the original. This small compaction can be used to reconstruct the original texture or to re-synthesize new textures under user-supplied controls. More important, our technique allows real-time synthesis of globally varying textures on a GPU, where the texture memory is usually too small for large textures. We propose an optimization framework for inverse texture synthesis, ensuring that each input region is properly encoded in the output compaction. Our optimization process also automatically computes orientation fields for anisotropic textures containing both low- and high-frequency regions, a situation difficult to handle via existing techniques.