Binding of anions in triply interlocked coordination catenanes and dynamic allostery for dehalogenation reactions.

Science.gov (United States)

Yang, Linlin; Jing, Xu; An, Bowen; He, Cheng; Yang, Yang; Duan, Chunying

2018-01-28

By synergistic combination of multicomponent self-assembly and template-directed approaches, triply interlocked metal organic catenanes that consist of two isolated chirally identical tetrahedrons were constructed and stabilized as thermodynamic minima. In the presence of suitable template anions, the structural conversion from the isolated tetrahedral conformers into locked catenanes occurred via the cleavage of an intrinsically reversible coordination bond in each of the tetrahedrons, followed by the reengineering and interlocking of two fragments with the regeneration of the broken coordination bonds. The presence of several kinds of individual pocket that were attributed to the triply interlocked patterns enabled the possibility of encapsulating different anions, allowing the dynamic allostery between the unlocked/locked conformers to promote the dehalogenation reaction of 3-bromo-cyclohexene efficiently, as with the use of dehalogenase enzymes. The interlocked structures could be unlocked into two individual tetrahedrons through removal of the well-matched anion templates. The stability and reversibility of the locked/unlocked structures were further confirmed by the catching/releasing process that accompanied emission switching, providing opportunities for the system to be a dynamic molecular logic system.

Limitations on blanket performance

International Nuclear Information System (INIS)

Malang, S.

1999-01-01

The limitations on the performance of breeding blankets in a fusion power plant are evaluated. The breeding blankets will be key components of a plant and their limitations with regard to power density, thermal efficiency and lifetime could determine to a large degree the attractiveness of a power plant. The performance of two rather well known blanket concepts under development in the frame of the European Blanket Programme is assessed and their limitations are compared with more advanced (and more speculative) concepts. An important issue is the question of which material (structure, breeder, multiplier, coatings) will limit the performance and what improvement would be possible with a 'better' structural material. This evaluation is based on the premise that the performance of the power plant will be limited by the blankets (including first wall) and not by other components, e.g. divertors, or the plasma itself. However, the justness of this premise remains to be seen. It is shown that the different blanket concepts cover a large range of allowable power densities and achievable thermal efficiencies, and it is concluded that there is a high incentive to go for better performance in spite of possibly higher blanket cost. However, such high performance blankets are usually based on materials and technologies not yet developed and there is a rather high risk that the development could fail. Therefore, it is explained that a part of the development effort should be devoted to concepts where the materials and technologies are more or less in hand in order to ensure that blankets for a DEMO reactor can be developed and tested in a given time frame. (orig.)

Allostery Is an Intrinsic Property of the Protease Domain of DegS Implications for Enzyme Function and Evolution

Energy Technology Data Exchange (ETDEWEB)

Sohn, Jungsan; Grant, Robert A.; Sauer, Robert T. (MIT)

2010-12-02

DegS is a periplasmic Escherichia coli protease, which functions as a trimer to catalyze the initial rate-limiting step in a proteolytic cascade that ultimately activates transcription of stress response genes in the cytoplasm. Each DegS subunit consists of a protease domain and a PDZ domain. During protein folding stress, DegS is allosterically activated by peptides exposed in misfolded outer membrane porins, which bind to the PDZ domain and stabilize the active protease. It is not known whether allostery is conferred by the PDZ domains or is an intrinsic feature of the trimeric protease domain. Here, we demonstrate that free DegS{sup {Delta}PDZ} equilibrates between active and inactive trimers with the latter species predominating. Substrate binding stabilizes active DegS{sup {Delta}PDZ} in a positively cooperative fashion. Mutations can also stabilize active DegS{sup {Delta}PDZ} and produce an enzyme that displays hyperbolic kinetics and degrades substrate with a maximal velocity within error of that for fully activated, intact DegS. Crystal structures of multiple DegS{sup {Delta}PDZ} variants, in functional and non-functional conformations, support a two-state model in which allosteric switching is mediated by changes in specific elements of tertiary structure in the context of an invariant trimeric base. Overall, our results indicate that protein substrates must bind sufficiently tightly and specifically to the functional conformation of DegS{sup {Delta}PDZ} to assist their own degradation. Thus, substrate binding alone may have regulated the activities of ancestral DegS trimers with subsequent fusion of the protease domain to a PDZ domain, resulting in ligand-mediated regulation.

Entropy Transfer between Residue Pairs and Allostery in Proteins: Quantifying Allosteric Communication in Ubiquitin.

Directory of Open Access Journals (Sweden)

Aysima Hacisuleyman

2017-01-01

Full Text Available It has recently been proposed by Gunasakaran et al. that allostery may be an intrinsic property of all proteins. Here, we develop a computational method that can determine and quantify allosteric activity in any given protein. Based on Schreiber's transfer entropy formulation, our approach leads to an information transfer landscape for the protein that shows the presence of entropy sinks and sources and explains how pairs of residues communicate with each other using entropy transfer. The model can identify the residues that drive the fluctuations of others. We apply the model to Ubiquitin, whose allosteric activity has not been emphasized until recently, and show that there are indeed systematic pathways of entropy and information transfer between residues that correlate well with the activities of the protein. We use 600 nanosecond molecular dynamics trajectories for Ubiquitin and its complex with human polymerase iota and evaluate entropy transfer between all pairs of residues of Ubiquitin and quantify the binding susceptibility changes upon complex formation. We explain the complex formation propensities of Ubiquitin in terms of entropy transfer. Important residues taking part in allosteric communication in Ubiquitin predicted by our approach are in agreement with results of NMR relaxation dispersion experiments. Finally, we show that time delayed correlation of fluctuations of two interacting residues possesses an intrinsic causality that tells which residue controls the interaction and which one is controlled. Our work shows that time delayed correlations, entropy transfer and causality are the required new concepts for explaining allosteric communication in proteins.

Entropy Transfer between Residue Pairs and Allostery in Proteins: Quantifying Allosteric Communication in Ubiquitin.

Science.gov (United States)

Hacisuleyman, Aysima; Erman, Burak

2017-01-01

It has recently been proposed by Gunasakaran et al. that allostery may be an intrinsic property of all proteins. Here, we develop a computational method that can determine and quantify allosteric activity in any given protein. Based on Schreiber's transfer entropy formulation, our approach leads to an information transfer landscape for the protein that shows the presence of entropy sinks and sources and explains how pairs of residues communicate with each other using entropy transfer. The model can identify the residues that drive the fluctuations of others. We apply the model to Ubiquitin, whose allosteric activity has not been emphasized until recently, and show that there are indeed systematic pathways of entropy and information transfer between residues that correlate well with the activities of the protein. We use 600 nanosecond molecular dynamics trajectories for Ubiquitin and its complex with human polymerase iota and evaluate entropy transfer between all pairs of residues of Ubiquitin and quantify the binding susceptibility changes upon complex formation. We explain the complex formation propensities of Ubiquitin in terms of entropy transfer. Important residues taking part in allosteric communication in Ubiquitin predicted by our approach are in agreement with results of NMR relaxation dispersion experiments. Finally, we show that time delayed correlation of fluctuations of two interacting residues possesses an intrinsic causality that tells which residue controls the interaction and which one is controlled. Our work shows that time delayed correlations, entropy transfer and causality are the required new concepts for explaining allosteric communication in proteins.

Analysis of performance limitations for superconducting cavities

International Nuclear Information System (INIS)

J. R. Delayen; L. R. Doolittle; C. E. Reece

1998-01-01

The performance of superconducting cavities in accelerators can be limited by several factors, such as: field emission, quenches, arcing, rf power; and the maximum gradient at which a cavity can operate will be determined by the lowest of these limitations for that particular cavity. The CEBAF accelerator operates with over 300 cavities and, for each of them, the authors have determined the maximum operating gradient and its limiting factor. They have developed a model that allows them to determine the distribution of gradients that could be achieved for each of these limitations independently of the others. The result of this analysis can guide an R and D program to achieve the best overall performance improvement. The same model can be used to relate the performance of single-cell and multi-cell cavities

Doublet III limiter performance and implications for mechanical design and material selection for future limiters

International Nuclear Information System (INIS)

Sabado, M.M.; Marcus, F.B.; Trester, P.W.; Wesley, J.C.

1979-10-01

The plasma limiter system for Doublet III is described. Initially, high-Z materials, Ta-10W for the primary limiter and Mo for the backup limiters, were selected as the most attractive metallic candidates from the standpoint of thermal and structural properties. For the purpose of evaluating the effect of material Z on plasma performance, the nonmagnetic, Ni-base alloy Inconel X-750 was selected for a medium-Z limiter material. Graphite, a low-Z material, will likely be the next limiter material for evaluation. Design and material selection criteria for the different Z ranges are presented. The performance of the high-Z limiters in Doublet III is reviewed for an operation period that included approximately 5000 plasma shots. Changes in surface appearance and metallurgical changes are characterized. Discussion is presented on how and to what extent the high-Z elements affected the performance of the plasma based on theory and measurements in Doublet III. The fabrication processes for the Inconel X-750 limiters are summarized, and, last, observations on early performance of the Inconel limiters are described

Doublet III limiter performance and implications for mechanical design and material selection for future limiters

Energy Technology Data Exchange (ETDEWEB)

Sabado, M.M.; Marcus, F.B.; Trester, P.W.; Wesley, J.C.

1979-10-01

The plasma limiter system for Doublet III is described. Initially, high-Z materials, Ta-10W for the primary limiter and Mo for the backup limiters, were selected as the most attractive metallic candidates from the standpoint of thermal and structural properties. For the purpose of evaluating the effect of material Z on plasma performance, the nonmagnetic, Ni-base alloy Inconel X-750 was selected for a medium-Z limiter material. Graphite, a low-Z material, will likely be the next limiter material for evaluation. Design and material selection criteria for the different Z ranges are presented. The performance of the high-Z limiters in Doublet III is reviewed for an operation period that included approximately 5000 plasma shots. Changes in surface appearance and metallurgical changes are characterized. Discussion is presented on how and to what extent the high-Z elements affected the performance of the plasma based on theory and measurements in Doublet III. The fabrication processes for the Inconel X-750 limiters are summarized, and, last, observations on early performance of the Inconel limiters are described. (MOW)

Performance limitations of translationally symmetric nonimaging devices

Science.gov (United States)

Bortz, John C.; Shatz, Narkis E.; Winston, Roland

2001-11-01

The component of the optical direction vector along the symmetry axis is conserved for all rays propagated through a translationally symmetric optical device. This quality, referred to herein as the translational skew invariant, is analogous to the conventional skew invariant, which is conserved in rotationally symmetric optical systems. The invariance of both of these quantities is a consequence of Noether's theorem. We show how performance limits for translationally symmetric nonimaging optical devices can be derived from the distributions of the translational skew invariant for the optical source and for the target to which flux is to be transferred. Examples of computed performance limits are provided. In addition, we show that a numerically optimized non-tracking solar concentrator utilizing symmetry-breaking surface microstructure can overcome the performance limits associated with translational symmetry. The optimized design provides a 47.4% increase in efficiency and concentration relative to an ideal translationally symmetric concentrator.

Effect of beta limits on reactor performance in EBT

International Nuclear Information System (INIS)

Uckan, N.A.; Spong, D.A.; Nelson, D.B.

1981-01-01

Because of uncertainties in extrapolating results of simplified models to a reactor plasma, the parameters that influence the beta limits cannot be determined accurately at the present time. Also, the reasonable changes within the models and/or assumptions are seen to affect the core beta limits by almost an order of magnitde. Hence, at the present, these limits cannot be used as a rigid (and reliable) requirement for ELMO Bumpy Torus (EBT) reactor engineering considerations. However, sensitivity studies can be carried out to determine the boundaries of the operating regime and to demonstrate the effects of various modes, assumptions, and models on reactor performance (Q value). First, the modes believed to limit the core β and ring plasma performance are discussed, and the simplifications and/or assumptions involved in deriving these limits are highlighted. Then, the implications of these limits for a reactor are given

Salt bridge interactions within the β2 integrin α7 helix mediate force-induced binding and shear resistance ability.

Science.gov (United States)

Zhang, Xiao; Li, Linda; Li, Ning; Shu, Xinyu; Zhou, Lüwen; Lü, Shouqin; Chen, Shenbao; Mao, Debin; Long, Mian

2018-01-01

The functional performance of the αI domain α 7 helix in β 2 integrin activation depends on the allostery of the α 7 helix, which axially slides down; therefore, it is critical to elucidate what factors regulate the allostery. In this study, we determined that there were two conservative salt bridge interaction pairs that constrain both the upper and bottom ends of the α 7 helix. Molecular dynamics (MD) simulations for three β 2 integrin members, lymphocyte function-associated antigen-1 (LFA-1; α L β 2 ), macrophage-1 antigen (Mac-1; α M β 2 ) and α x β 2 , indicated that the magnitude of the salt bridge interaction is related to the stability of the αI domain and the strength of the corresponding force-induced allostery. The disruption of the salt bridge interaction, especially with double mutations in both salt bridges, significantly reduced the force-induced allostery time for all three members. The effects of salt bridge interactions of the αI domain α 7 helix on β 2 integrin conformational stability and allostery were experimentally validated using Mac-1 constructs. The results demonstrated that salt bridge mutations did not alter the conformational state of Mac-1, but they did increase the force-induced ligand binding and shear resistance ability, which was consistent with MD simulations. This study offers new insight into the importance of salt bridge interaction constraints of the αI domain α 7 helix and external force for β 2 integrin function. © 2017 Federation of European Biochemical Societies.

Performance limits for fusion first-wall structural materials

International Nuclear Information System (INIS)

Smith, D.L.; Majumdar, S.; Billone, M.; Mattas, R.

2000-01-01

Key features of fusion energy relate primarily to potential advantages associated with safety and environmental considerations and the near endless supply of fuel. However, high-performance fusion power systems will be required in order to be an economically competitive energy option. As in most energy systems, the operating limits of structural materials pose a primary constraint to the performance of fusion power systems. In the case of fusion power, the first-wall/blanket system will have a dominant impact on both economic and safety/environmental attractiveness. This paper presents an assessment of the influence of key candidate structural material properties on performance limits for fusion first-wall blanket applications. Key issues associated with interactions of the structural materials with the candidate coolant/breeder materials are discussed

Performance limits for maritime Inverse Synthetic Aperture Radar (ISAR)

Energy Technology Data Exchange (ETDEWEB)

Doerry, Armin Walter [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2013-11-01

The performance of an Inverse Synthetic Aperture Radar (ISAR) system depends on a variety of factors, many which are interdependent in some manner. In this report we specifically examine ISAR as applied to maritime targets (e.g. ships). It is often difficult to get your arms around the problem of ascertaining achievable performance limits, and yet those limits exist and are dictated by physics. This report identifies and explores those limits, and how they depend on hardware system parameters and environmental conditions. Ultimately, this leads to a characterization of parameters that offer optimum performance for the overall ISAR system. While the information herein is not new to the literature, its collection into a single report hopes to offer some value in reducing the seek time.

Fulltext PDF

Indian Academy of Sciences (India)

2017-02-10

Feb 10, 2017 ... gists when speaking of the balance between stability and activity, was not limited to the work of protein engineers, ... What is searched for in a large family of homologous pro- .... Morange M 2012 A new life for allostery.

Targeting Allostery with Avatars to Design Inhibitors Assessed by Cell Activity: Dissecting MRE11 Endo- and Exonuclease Activities.

Science.gov (United States)

Moiani, Davide; Ronato, Daryl A; Brosey, Chris A; Arvai, Andrew S; Syed, Aleem; Masson, Jean-Yves; Petricci, Elena; Tainer, John A

2018-01-01

For inhibitor design, as in most research, the best system is question dependent. We suggest structurally defined allostery to design specific inhibitors that target regions beyond active sites. We choose systems allowing efficient quality structures with conformational changes as optimal for structure-based design to optimize inhibitors. We maintain that evolutionarily related targets logically provide molecular avatars, where this Sanskrit term for descent includes ideas of functional relationships and of being a physical embodiment of the target's essential features without requiring high sequence identity. Appropriate biochemical and cell assays provide quantitative measurements, and for biomedical impacts, any inhibitor's activity should be validated in human cells. Specificity is effectively shown empirically by testing if mutations blocking target activity remove cellular inhibitor impact. We propose this approach to be superior to experiments testing for lack of cross-reactivity among possible related enzymes, which is a challenging negative experiment. As an exemplary avatar system for protein and DNA allosteric conformational controls, we focus here on developing separation-of-function inhibitors for meiotic recombination 11 nuclease activities. This was achieved not by targeting the active site but rather by geometrically impacting loop motifs analogously to ribosome antibiotics. These loops are neighboring the dimer interface and active site act in sculpting dsDNA and ssDNA into catalytically competent complexes. One of our design constraints is to preserve DNA substrate binding to geometrically block competing enzymes and pathways from the damaged site. We validate our allosteric approach to controlling outcomes in human cells by reversing the radiation sensitivity and genomic instability in BRCA mutant cells. © 2018 Elsevier Inc. All rights reserved.

Imaging performance of annular apertures. VI - Limitations by optical surface deviations

Science.gov (United States)

Tschunko, Hubert F. A.

1987-01-01

The performance of optical systems is limited by imperfect optical surfaces that degrade the images below the level set by wave theoretical limits. The central irradiance functions are derived for slit and circular apertures with five distributions of wavefront errors and for a range of maximal wavefront deviations. For practical frequency of occurrence distributions of wavefront deviations, the point spread and the image energy integral functions are determined. Practical performances of optical systems are derived and performance limits discussed.

14 CFR 135.397 - Small transport category airplane performance operating limitations.

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Small transport category airplane... PERSONS ON BOARD SUCH AIRCRAFT Airplane Performance Operating Limitations § 135.397 Small transport category airplane performance operating limitations. (a) No person may operate a reciprocating engine...

14 CFR 135.399 - Small nontransport category airplane performance operating limitations.

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Small nontransport category airplane... PERSONS ON BOARD SUCH AIRCRAFT Airplane Performance Operating Limitations § 135.399 Small nontransport category airplane performance operating limitations. (a) No person may operate a reciprocating engine or...

Performance limits for exo-clutter Ground Moving Target Indicator (GMTI) radar.

Energy Technology Data Exchange (ETDEWEB)

Doerry, Armin Walter

2010-09-01

The performance of a Ground Moving Target Indicator (GMTI) radar system depends on a variety of factors, many which are interdependent in some manner. It is often difficult to 'get your arms around' the problem of ascertaining achievable performance limits, and yet those limits exist and are dictated by physics. This report identifies and explores those limits, and how they depend on hardware system parameters and environmental conditions. Ultimately, this leads to a characterization of parameters that offer optimum performance for the overall GMTI radar system. While the information herein is not new to the literature, its collection into a single report hopes to offer some value in reducing the 'seek time'.

Reactivity limitations on the performance of hybrid reactors

International Nuclear Information System (INIS)

Piera, M.; Martinez-Val, J.M.

1994-01-01

A neutronic theory for characterizing the hybrid blanket physics is used to show that hybrid performances are limited because of reactivity restrictions. The hybrid must always remain subcritical, even in abnormal conditions. For hybrids devoted to energy production by multiplication of the neutron source power, the restriction is particularly strong, and the electricity recirculation fraction to feed the plant can be too large for its economic feasibility. In hybrids used to breed fissile fuel, the power of LWR maintained by power unit of the hybrid is also limited (to a factor of 10, approx.). (author)

Performance limitations at ISABELLE

International Nuclear Information System (INIS)

Keil, E.

1975-01-01

The transverse stability of coasting beams in the planned ISABELLE storage rings was studied. The beam--beam tune shift limitation at 0.005 can be avoided, and a computer simulation seems to show 0.005 is a pessimistic limit. For beams of reasonable smoothness on the edge, the actual limit should be somewhat higher. Some coupling effects due to the beam--beam interaction are also examined

Performance limit of daytime radiative cooling in warm humid environment

Directory of Open Access Journals (Sweden)

Takahiro Suichi

2018-05-01

Full Text Available Daytime radiative cooling potentially offers efficient passive cooling, but the performance is naturally limited by the environment, such as the ambient temperature and humidity. Here, we investigate the performance limit of daytime radiative cooling under warm and humid conditions in Okayama, Japan. A cooling device, consisting of alternating layers of SiO2 and poly(methyl methacrylate on an Al mirror, is fabricated and characterized to demonstrate a high reflectance for sunlight and a selective thermal radiation in the mid-infrared region. In the temperature measurement under the sunlight irradiation, the device shows 3.4 °C cooler than a bare Al mirror, but 2.8 °C warmer than the ambient of 35 °C. The corresponding numerical analyses reveal that the atmospheric window in λ = 16 ∼ 25 μm is closed due to a high humidity, thereby limiting the net emission power of the device. Our study on the humidity influence on the cooling performance provides a general guide line of how one can achieve practical passive cooling in a warm humid environment.

Evaluation on current-limiting performance of the YBCO thin-film wire considering electric coupling condition

International Nuclear Information System (INIS)

Du, H.-I.; Han, B.-S.; Kim, Y.-J.; Lee, D.-H.; Song, S.-S.; Han, T.-H.; Han, S.-C.

2011-01-01

The basic way to improve the performance of a superconducting current limiter is to apply and evaluate a superconducting device that is appropriate to the superconducting current limiter. Among the many types of superconducting devices, the YBCO thin film wire has excellent current-limiting performance that is appropriate for actual system application. For the application of the YBCO thin film wire to superconducting current limiters, its current-limiting performance as a unit device must be accurately evaluated, and measures to improve its current-limiting performance must be sought. Accordingly, to evaluate the current-limiting performance of the YBCO thin film wire, this study was conducted to evaluate its resistance-increasing trend, V max , T r , I max , I qt , and current-limiting rate as a unit device, after which the electric coupling condition that consists of a core and windings was used to evaluate the current-limiting performance of the YBCO thin film wire.

High temperature performance limit of containment system of transport cask

International Nuclear Information System (INIS)

Kato, Osamu; Saegusa, Toshiari

1998-01-01

The containment performance of a containment system using elastomer gaskets for transport casks under a high temperature and high pressure was clarified. Major results are as follows; (1) The deformation characteristics of the gaskets were represented by the compressive permanent strain rate (Dp). The temperature and time dependence was shown by Larson-Miller Parameter (LMP). (2) Generally, the high temperature performance limit is obtained by a value of LMP when the Dp value reaches 80%. However, the gaskets (FKM, VMQ, EPDM) used for real transport casks were not damaged and the containment performance was not deteriorated as a conservative condition. (3) Assuming that the service period of the gaskets for transport casks is 3 months or 1 year, the high temperature performance limit of the gasket made of fluorine rubber (FKM) is 202degC or 182degC, respectively, which includes safety margin. (author)

The Limits of Exercise Physiology: From Performance to Health.

Science.gov (United States)

Gabriel, Brendan M; Zierath, Juleen R

2017-05-02

Many of the established positive health benefits of exercise have been documented by historical discoveries in the field of exercise physiology. These investigations often assess limits: the limits of performance, or the limits of exercise-induced health benefits. Indeed, several key findings have been informed by studying highly trained athletes, in addition to healthy or unhealthy people. Recent progress has been made in regard to skeletal muscle metabolism and personalized exercise regimes. In this perspective, we review some of the historical milestones of exercise physiology, discuss how these inform contemporary knowledge, and speculate on future questions. Copyright © 2017 Elsevier Inc. All rights reserved.

Knock-limited performance of several internal coolants

Science.gov (United States)

Bellman, Donald R; Evvard, John C

1945-01-01

The effect of internal cooling on the knock-limited performance of an-f-28 fuel was investigated in a CFR engine, and the following internal coolants were used: (1) water, (2), methyl alcohol-water mixture, (3) ammonia-methyl alcohol-water mixture, (4) monomethylamine-water mixture, (5) dimethylamine-water mixture, and (6) trimethylamine-water mixture. Tests were run at inlet-air temperatures of 150 degrees and 250 degrees F. to indicate the temperature sensitivity of the internal-coolant solutions.

High Performance Redox Flow Batteries: An Analysis of the Upper Performance Limits of Flow Batteries Using Non-aqueous Solvents

International Nuclear Information System (INIS)

Sun, C.-N.; Mench, M.M.; Zawodzinski, T.A.

2017-01-01

Redox Flow Batteries (RFBs) are a promising technology for grid-scale electrochemical energy storage. In this work, we use a recently achieved high-performance flow battery performance curve as a basis to assess the maximum achievable performance of a RFB employing non-aqueous solutions as active materials. First we show high performance in a vanadium redox flow battery (VRFB), specifically a limiting situation in which the cell losses are ohmic in nature and derive from electrolyte conductance. Based on that case, we analyze the analogous limiting behavior of non-aqueous (NA) systems using a series of calculations assuming similar ohmic losses, scaled by the relative electrolyte resistances, with a higher voltage redox couple assumed for the NA battery. The results indicate that the NA battery performance is limited by the low electrolyte conductivity to a fraction of the performance of the VRFB. Given the narrow window in which the NARFB offers advantages, even for the most generous limiting assumptions related to performance while ignoring the numerous other disadvantageous aspects of these systems, we conclude that this technology is unlikely under present circumstances to provide practical large-scale energy storage solutions.

H/D exchange mass spectrometry and statistical coupling analysis reveal a role for allostery in a ferredoxin-dependent bifurcating transhydrogenase catalytic cycle.

Science.gov (United States)

Berry, Luke; Poudel, Saroj; Tokmina-Lukaszewska, Monika; Colman, Daniel R; Nguyen, Diep M N; Schut, Gerrit J; Adams, Michael W W; Peters, John W; Boyd, Eric S; Bothner, Brian

2018-01-01

Recent investigations into ferredoxin-dependent transhydrogenases, a class of enzymes responsible for electron transport, have highlighted the biological importance of flavin-based electron bifurcation (FBEB). FBEB generates biomolecules with very low reduction potential by coupling the oxidation of an electron donor with intermediate potential to the reduction of high and low potential molecules. Bifurcating systems can generate biomolecules with very low reduction potentials, such as reduced ferredoxin (Fd), from species such as NADPH. Metabolic systems that use bifurcation are more efficient and confer a competitive advantage for the organisms that harbor them. Structural models are now available for two NADH-dependent ferredoxin-NADP + oxidoreductase (Nfn) complexes. These models, together with spectroscopic studies, have provided considerable insight into the catalytic process of FBEB. However, much about the mechanism and regulation of these multi-subunit proteins remains unclear. Using hydrogen/deuterium exchange mass spectrometry (HDX-MS) and statistical coupling analysis (SCA), we identified specific pathways of communication within the model FBEB system, Nfn from Pyrococus furiosus, under conditions at each step of the catalytic cycle. HDX-MS revealed evidence for allosteric coupling across protein subunits upon nucleotide and ferredoxin binding. SCA uncovered a network of co-evolving residues that can provide connectivity across the complex. Together, the HDX-MS and SCA data show that protein allostery occurs across the ensemble of iron‑sulfur cofactors and ligand binding sites using specific pathways that connect domains allowing them to function as dynamically coordinated units. Copyright © 2017 Elsevier B.V. All rights reserved.

The Role of Protein-Ligand Contacts in Allosteric Regulation of the Escherichia coli Catabolite Activator Protein*

Science.gov (United States)

Townsend, Philip D.; Rodgers, Thomas L.; Glover, Laura C.; Korhonen, Heidi J.; Richards, Shane A.; Colwell, Lucy J.; Pohl, Ehmke; Wilson, Mark R.; Hodgson, David R. W.; McLeish, Tom C. B.; Cann, Martin J.

2015-01-01

Allostery is a fundamental process by which ligand binding to a protein alters its activity at a distant site. Both experimental and theoretical evidence demonstrate that allostery can be communicated through altered slow relaxation protein dynamics without conformational change. The catabolite activator protein (CAP) of Escherichia coli is an exemplar for the analysis of such entropically driven allostery. Negative allostery in CAP occurs between identical cAMP binding sites. Changes to the cAMP-binding pocket can therefore impact the allosteric properties of CAP. Here we demonstrate, through a combination of coarse-grained modeling, isothermal calorimetry, and structural analysis, that decreasing the affinity of CAP for cAMP enhances negative cooperativity through an entropic penalty for ligand binding. The use of variant cAMP ligands indicates the data are not explained by structural heterogeneity between protein mutants. We observe computationally that altered interaction strength between CAP and cAMP variously modifies the change in allosteric cooperativity due to second site CAP mutations. As the degree of correlated motion between the cAMP-contacting site and a second site on CAP increases, there is a tendency for computed double mutations at these sites to drive CAP toward noncooperativity. Naturally occurring pairs of covarying residues in CAP do not display this tendency, suggesting a selection pressure to fine tune allostery on changes to the CAP ligand-binding pocket without a drive to a noncooperative state. In general, we hypothesize an evolutionary selection pressure to retain slow relaxation dynamics-induced allostery in proteins in which evolution of the ligand-binding site is occurring. PMID:26187469

The condensed chromatin fiber: an allosteric chemo-mechanical machine for signal transduction and genome processing

International Nuclear Information System (INIS)

Lesne, Annick; Victor, Jean–Marc; Bécavin, Christophe

2012-01-01

Allostery is a key concept of molecular biology which refers to the control of an enzyme activity by an effector molecule binding the enzyme at another site rather than the active site (allos = other in Greek). We revisit here allostery in the context of chromatin and argue that allosteric principles underlie and explain the functional architecture required for spacetime coordination of gene expression at all scales from DNA to the whole chromosome. We further suggest that this functional architecture is provided by the chromatin fiber itself. The structural, mechanical and topological features of the chromatin fiber endow chromosomes with a tunable signal transduction from specific (or nonspecific) effectors to specific (or nonspecific) active sites. Mechanical constraints can travel along the fiber all the better since the fiber is more compact and regular, which speaks in favor of the actual existence of the (so-called 30 nm) chromatin fiber. Chromatin fiber allostery reconciles both the physical and biochemical approaches of chromatin. We illustrate this view with two supporting specific examples. Moreover, from a methodological point of view, we suggest that the notion of chromatin fiber allostery is particularly relevant for systemic approaches. Finally we discuss the evolutionary power of allostery in the context of chromatin and its relation to modularity. (perspective)

The condensed chromatin fiber: an allosteric chemo-mechanical machine for signal transduction and genome processing

Science.gov (United States)

Lesne, Annick; Bécavin, Christophe; Victor, Jean–Marc

2012-02-01

Allostery is a key concept of molecular biology which refers to the control of an enzyme activity by an effector molecule binding the enzyme at another site rather than the active site (allos = other in Greek). We revisit here allostery in the context of chromatin and argue that allosteric principles underlie and explain the functional architecture required for spacetime coordination of gene expression at all scales from DNA to the whole chromosome. We further suggest that this functional architecture is provided by the chromatin fiber itself. The structural, mechanical and topological features of the chromatin fiber endow chromosomes with a tunable signal transduction from specific (or nonspecific) effectors to specific (or nonspecific) active sites. Mechanical constraints can travel along the fiber all the better since the fiber is more compact and regular, which speaks in favor of the actual existence of the (so-called 30 nm) chromatin fiber. Chromatin fiber allostery reconciles both the physical and biochemical approaches of chromatin. We illustrate this view with two supporting specific examples. Moreover, from a methodological point of view, we suggest that the notion of chromatin fiber allostery is particularly relevant for systemic approaches. Finally we discuss the evolutionary power of allostery in the context of chromatin and its relation to modularity.

Treating Chronically Ill Diabetic Patients with Limited Life Expectancy: Implications for Performance Measurement

Science.gov (United States)

Woodard, LeChauncy D.; Landrum, Cassie R.; Urech, Tracy H.; Profit, Jochen; Virani, Salim S.; Petersen, Laura A.

2012-01-01

Background/Objectives To validly assess quality-of-care differences among providers, performance measurement programs must reliably identify and exclude patients for whom the quality indicator may not be desirable, including those with limited life expectancy. We developed an algorithm to identify patients with limited life expectancy and examined the impact of limited life expectancy on glycemic control and treatment intensification among diabetic patients. Design We identified diabetic patients with coexisting congestive heart failure, chronic obstructive pulmonary disease, dementia, end-stage liver disease, and/or primary/metastatic cancers with limited life expectancy. To validate our algorithm, we assessed 5-year mortality among patients identified as having limited life expectancy. We compared rates of meeting performance measures for glycemic control between patients with and without limited life expectancy. Among uncontrolled patients, we examined the impact of limited life expectancy on treatment intensification within 90 days. Setting 110 Veterans Administration facilities; October 2006 – September 2007 Participants 888,628 diabetic patients Measurements Hemoglobin A1c (HbA1c) Quality measurement and performance-based reimbursement systems should acknowledge the different needs of this population. PMID:22260627

Performance limits of direct cryogenically cooled silicon monochromators - experimental results at the APS

International Nuclear Information System (INIS)

Lee, W.-K.; Fernandez, P.; Mills, D.M.

2000-01-01

The successful use of cryogenically cooled silicon monochromators at third-generation synchrotron facilities is well documented. At the Advanced Photon Source (APS) it has been shown that, at 100 mA operation with the standard APS undulator A, the cryogenically cooled silicon monochromator performs very well with minimal (<2 arcsec) or no observable thermal distortions. However, to date there has not been any systematic experimental study on the performance limits of this approach. This paper presents experimental results on the performance limits of these directly cooled crystals. The results show that if the beam is limited to the size of the radiation central cone then, at the APS, the crystal will still perform well at twice the present 100 mA single 2.4 m-long 3.3 cm-period undulator heat load. However, the performance would degrade rapidly if a much larger incident white-beam size is utilized

The Role of Protein-Ligand Contacts in Allosteric Regulation of the Escherichia coli Catabolite Activator Protein.

Science.gov (United States)

Townsend, Philip D; Rodgers, Thomas L; Glover, Laura C; Korhonen, Heidi J; Richards, Shane A; Colwell, Lucy J; Pohl, Ehmke; Wilson, Mark R; Hodgson, David R W; McLeish, Tom C B; Cann, Martin J

2015-09-04

Allostery is a fundamental process by which ligand binding to a protein alters its activity at a distant site. Both experimental and theoretical evidence demonstrate that allostery can be communicated through altered slow relaxation protein dynamics without conformational change. The catabolite activator protein (CAP) of Escherichia coli is an exemplar for the analysis of such entropically driven allostery. Negative allostery in CAP occurs between identical cAMP binding sites. Changes to the cAMP-binding pocket can therefore impact the allosteric properties of CAP. Here we demonstrate, through a combination of coarse-grained modeling, isothermal calorimetry, and structural analysis, that decreasing the affinity of CAP for cAMP enhances negative cooperativity through an entropic penalty for ligand binding. The use of variant cAMP ligands indicates the data are not explained by structural heterogeneity between protein mutants. We observe computationally that altered interaction strength between CAP and cAMP variously modifies the change in allosteric cooperativity due to second site CAP mutations. As the degree of correlated motion between the cAMP-contacting site and a second site on CAP increases, there is a tendency for computed double mutations at these sites to drive CAP toward noncooperativity. Naturally occurring pairs of covarying residues in CAP do not display this tendency, suggesting a selection pressure to fine tune allostery on changes to the CAP ligand-binding pocket without a drive to a noncooperative state. In general, we hypothesize an evolutionary selection pressure to retain slow relaxation dynamics-induced allostery in proteins in which evolution of the ligand-binding site is occurring. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Improving the performance of power-limited transverse stochastic cooling systems

International Nuclear Information System (INIS)

Goldberg, D.A.; Lambertson, G.R.

1989-08-01

We present the formulas relevant to the behavior of (transverse) stochastic cooling systems which operate under the not uncommon condition that performance is limited by available output power, and contrast the operation of such systems with non-power-limited ones. In particular, we show that for power-limited systems, the two most effective improvements are the use of pickups/kickers which operate in both planes simultaneously and/or plunging of the cooling system electrodes, and present an example where increasing bandwidth is counter-productive. We apply our results to the proposed upgrade of the Fermilab bar p source. 4 refs., 1 fig., 2 tabs

Performance limits of plasmon-enhanced organic photovoltaics

Energy Technology Data Exchange (ETDEWEB)

Karatay, Durmus U.; Ginger, David S., E-mail: ginger@chem.washington.edu [Department of Physics, University of Washington, Seattle, Washington 98195 (United States); Department of Chemistry, University of Washington, Seattle, Washington 98195 (United States); Salvador, Michael [Department of Chemistry, University of Washington, Seattle, Washington 98195 (United States); Yao, Kai [Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195 (United States); Jen, Alex K.-Y. [Department of Chemistry, University of Washington, Seattle, Washington 98195 (United States); Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195 (United States)

2014-07-21

We use a combination of experiment and modeling to explore the promise and limitations of using plasmon-resonant metal nanoparticles to enhance the device performance of organic photovoltaics (OPVs). We focus on optical properties typical of the current generation of low-bandgap donor polymers blended with the fullerene (6,6)-phenyl C{sub 71}-butyric acid methyl ester (PC{sub 71}BM) and use the polymer poly(indacenodithiophene-co-phenanthro[9,10-b]quinoxaline) (PIDT-PhanQ) as our test case. We model the optical properties and performance of these devices both in the presence and absence of a variety of colloidal silver nanoparticles. We show that for these materials, device performance is sensitive to the relative z-position and the density of nanoparticles inside the active layer. Using conservative estimates of the internal quantum efficiency for the PIDT-PhanQ/PC{sub 71}BM blend, we calculate that optimally placed silver nanoparticles could yield an enhancement in short-circuit current density of over 31% when used with ∼ 80-nm-thick active layers, resulting in an absolute increase in power conversion efficiency of up to ∼2% for the device based on optical engineering.

Operational limitations of light water reactors relating to fuel performance

International Nuclear Information System (INIS)

Cheng, H.S.

1976-07-01

General aspects of fuel performance for typical Boiling and Pressurized Water Reactors are presented. Emphasis is placed on fuel failures in order to make clear important operational limitations. A discussion of fuel element designs is first given to provide the background information for the subsequent discussion of several fuel failure modes that have been identified. Fuel failure experiences through December 31, 1974, are summarized. The operational limitations that are required to mitigate the effects of fuel failures are discussed

Testing the Limits of Optimizing Dual-Task Performance in Younger and Older Adults

Science.gov (United States)

Strobach, Tilo; Frensch, Peter; Müller, Herrmann Josef; Schubert, Torsten

2012-01-01

Impaired dual-task performance in younger and older adults can be improved with practice. Optimal conditions even allow for a (near) elimination of this impairment in younger adults. However, it is unknown whether such (near) elimination is the limit of performance improvements in older adults. The present study tests this limit in older adults under conditions of (a) a high amount of dual-task training and (b) training with simplified component tasks in dual-task situations. The data showed that a high amount of dual-task training in older adults provided no evidence for an improvement of dual-task performance to the optimal dual-task performance level achieved by younger adults. However, training with simplified component tasks in dual-task situations exclusively in older adults provided a similar level of optimal dual-task performance in both age groups. Therefore through applying a testing the limits approach, we demonstrated that older adults improved dual-task performance to the same level as younger adults at the end of training under very specific conditions. PMID:22408613

Towards integrating control and information theories from information-theoretic measures to control performance limitations

CERN Document Server

Fang, Song; Ishii, Hideaki

2017-01-01

This book investigates the performance limitation issues in networked feedback systems. The fact that networked feedback systems consist of control and communication devices and systems calls for the integration of control theory and information theory. The primary contributions of this book lie in two aspects: the newly-proposed information-theoretic measures and the newly-discovered control performance limitations. We first propose a number of information notions to facilitate the analysis. Using those notions, classes of performance limitations of networked feedback systems, as well as state estimation systems, are then investigated. In general, the book presents a unique, cohesive treatment of performance limitation issues of networked feedback systems via an information-theoretic approach. This book is believed to be the first to treat the aforementioned subjects systematically and in a unified manner, offering a unique perspective differing from existing books.

Modulation of global low-frequency motions underlies allosteric regulation: demonstration in CRP/FNR family transcription factors.

Science.gov (United States)

Rodgers, Thomas L; Townsend, Philip D; Burnell, David; Jones, Matthew L; Richards, Shane A; McLeish, Tom C B; Pohl, Ehmke; Wilson, Mark R; Cann, Martin J

2013-09-01

Allostery is a fundamental process by which ligand binding to a protein alters its activity at a distinct site. There is growing evidence that allosteric cooperativity can be communicated by modulation of protein dynamics without conformational change. The mechanisms, however, for communicating dynamic fluctuations between sites are debated. We provide a foundational theory for how allostery can occur as a function of low-frequency dynamics without a change in structure. We have generated coarse-grained models that describe the protein backbone motions of the CRP/FNR family transcription factors, CAP of Escherichia coli and GlxR of Corynebacterium glutamicum. The latter we demonstrate as a new exemplar for allostery without conformation change. We observe that binding the first molecule of cAMP ligand is correlated with modulation of the global normal modes and negative cooperativity for binding the second cAMP ligand without a change in mean structure. The theory makes key experimental predictions that are tested through an analysis of variant proteins by structural biology and isothermal calorimetry. Quantifying allostery as a free energy landscape revealed a protein "design space" that identified the inter- and intramolecular regulatory parameters that frame CRP/FNR family allostery. Furthermore, through analyzing CAP variants from diverse species, we demonstrate an evolutionary selection pressure to conserve residues crucial for allosteric control. This finding provides a link between the position of CRP/FNR transcription factors within the allosteric free energy landscapes and evolutionary selection pressures. Our study therefore reveals significant features of the mechanistic basis for allostery. Changes in low-frequency dynamics correlate with allosteric effects on ligand binding without the requirement for a defined spatial pathway. In addition to evolving suitable three-dimensional structures, CRP/FNR family transcription factors have been selected to

Volumetric activity of SRS mixed waste and comparison with SRS performance and commercial facility limits

International Nuclear Information System (INIS)

Ades, M.J.; Daugherty, B.A.; Cook, J.R.

1996-01-01

This paper discusses the comparative analysis performed to estimate the after-treatment volumetric activity of the radionuclides included in the Savannah River site (SRS) mixed-waste streams and its comparison with the following: (1) The performance evaluation (PE) limits established for each radionuclide for on-site disposal: These limits correspond to the permissible waste disposal limits that are the lowest limits evaluated for the most restrictive release scenarios that include the groundwater pathway, the atmospheric pathway, and the intruder scenarios. (2) The radiological performance assessment (PA) limits established for each radionuclide for disposal in the SRS disposal vaults that meet the requirements of Chap. III of the U.S. Department of Energy Order 5820.2A: The vaults considered are the low-activity waste (LAW) vaults, the intermediate-level non-tritium (ILNT) vaults. and the intermediate-level tritium (ILT) vaults. (3) The radioactive limits of a commercial mixed waste disposal facility

Effects of intermediate load on performance limitations in excitation control

Directory of Open Access Journals (Sweden)

Pichai Aree

2008-05-01

Full Text Available The stability of excitation control systems is of great concern in power system operations. In this paper, the effects of intermediate load on performance limitation in excitation control are studied. The results reveal that the open-loop characteristic of synchronous machine’s flux linkage can be changed from minimum to non-minimum phase at a high level of intermediate load. This change leads to instability of synchronous machines under manual excitation control. A particular emphasis is also given to investigate the fundamental limitations in excitation control, imposed by non-minimum phases with regard to the open-loop right-half-plane (ORHP pole. The study demonstrates the difficulties of excitation control tuning to achieve the desired performance and robustness under the ORHP pole occurrence. Moreover, this paper shows the conditional stability in excitation control loop, where either an increase or decrease of the exciter gain causes a destabilization of the system’s stability. Frequency response techniques are used for these investigations.

Performance of an irreversible quantum Ericsson cooler at low temperature limit

International Nuclear Information System (INIS)

Wu Feng; Chen Lingen; Wu Shuang; Sun Fengrui

2006-01-01

The purpose of this paper is to investigate the effect of quantum properties of the working medium on the performance of an irreversible quantum Ericsson cooler with spin-1/2. The cooler is studied with the losses of heat resistance, heat leakage and internal irreversibility. The optimal relationship between the dimensionless cooling load R * versus the coefficient of performance ε for the irreversible quantum Ericsson cooler is derived. In particular, the performance characteristics of the cooler at the low temperature limit are discussed

The Effect of Modified Control Limits on the Performance of a Generic Commercial Aircraft Engine

Science.gov (United States)

Csank, Jeffrey T.; May, Ryan D.; Gou, Ten-Huei; Litt, Jonathan S.

2012-01-01

This paper studies the effect of modifying the control limits of an aircraft engine to obtain additional performance. In an emergency situation, the ability to operate an engine above its normal operating limits and thereby gain additional performance may aid in the recovery of a distressed aircraft. However, the modification of an engine s limits is complex due to the risk of an engine failure. This paper focuses on the tradeoff between enhanced performance and risk of either incurring a mechanical engine failure or compromising engine operability. The ultimate goal is to increase the engine performance, without a large increase in risk of an engine failure, in order to increase the probability of recovering the distressed aircraft. The control limit modifications proposed are to extend the rotor speeds, temperatures, and pressures to allow more thrust to be produced by the engine, or to increase the rotor accelerations and allow the engine to follow a fast transient. These modifications do result in increased performance; however this study indicates that these modifications also lead to an increased risk of engine failure.

Performance Limiting Effects in Power Generation from Salinity Gradients by Pressure Retarded Osmosis

KAUST Repository

Yip, Ngai Yin

2011-12-01

Pressure retarded osmosis has the potential to utilize the free energy of mixing when fresh river water flows into the sea for clean and renewable power generation. Here, we present a systematic investigation of the performance limiting phenomena in pressure retarded osmosis-external concentration polarization, internal concentration polarization, and reverse draw salt flux-and offer insights on the design criteria of a high performance pressure retarded osmosis power generation system. Thin-film composite polyamide membranes were chemically modified to produce a range of membrane transport properties, and the water and salt permeabilities were characterized to determine the underlying permeability-selectivity trade-off relationship. We show that power density is constrained by the trade-off between permeability and selectivity of the membrane active layer. This behavior is attributed to the opposing influence of the beneficial effect of membrane water permeability and the detrimental impact of reverse salt flux coupled with internal concentration polarization. Our analysis reveals the intricate influence of active and support layer properties on power density and demonstrates that membrane performance is maximized by tailoring the water and salt permeabilities to the structural parameters. An analytical parameter that quantifies the relative influence of each performance limiting phenomena is employed to identify the dominant effect restricting productivity. External concentration polarization is shown to be the main factor limiting performance at high power densities. Enhancement of the hydrodynamic flow conditions in the membrane feed channel reduces external concentration polarization and thus, yields improved power density. However, doing so will also incur additional operating costs due to the accompanying hydraulic pressure loss. This study demonstrates that by thoughtful selection of the membrane properties and hydrodynamic conditions, the detrimental

Performance and Lifetime Limiting Effects in Li-ion Batteries

DEFF Research Database (Denmark)

Scipioni, Roberto

Lithium-ion batteries (LIBs) find widespread use for electricity storage, from portable devices such as smart phones to electric vehicles (EV), because of their high energy density and design flexibility. However, limited lifetime is still a challenge for several LIB materials. Specifically......, the detailed coupling between degradation mechanisms and battery usage is not fully understood, which impede lifetime improvements. To understand the degradation mechanisms and increase the performance of these materials, the development of improved characterization methods is crucial. This PhD thesis focuses...... on the thorough analysis of degradation mechanism in LIBs, trying to relate morphological and structural changes in Lithium-ion battery electrodes to performance degradation observed during electrode cycling. Degradation mechanisms in laboratory scale LFP cathodes were correlated with the degradation mechanisms...

High performance discharges near the operational limit in HT-7

International Nuclear Information System (INIS)

Li Jiangang; Wan Baonian; Luo Jiarong; Gao Xiang; Zhao Yanping; Kuang Guangli; Zhang Xiaodong; Yang Yu; Yi Bao; Bojiang Ding; Jikang Xie; Yuanxi Wan

2001-01-01

Efforts have been made on the HT-7 tokamak to extend the stable operation boundaries. Extensive RF boronization and siliconization have been used and a wider operational Hugill diagram has been obtained. The transit density reached 1.3 times the Greenwald density limit in ohmic discharges. A stationary high performance discharge with q a =2.1 has been obtained after siliconization. Confinement improvement was obtained as a result of the significant reduction of electron thermal diffusivity χ e in the outer region of the plasma. An improved confinement phase was also observed with LHCD in the density range of 70-120% of the Greenwald density limit. Off-axis LH wave power deposition was attributed to the weak hollow current density profile. Code simulations and measurements showed good agreement with the off-axis LH wave deposition. Supersonic molecular beam injection has been successfully used to achieve stable high density operation in the region of the Greenwald density limit. (author)

Modulation of global low-frequency motions underlies allosteric regulation: demonstration in CRP/FNR family transcription factors.

Directory of Open Access Journals (Sweden)

Thomas L Rodgers

2013-09-01

Full Text Available Allostery is a fundamental process by which ligand binding to a protein alters its activity at a distinct site. There is growing evidence that allosteric cooperativity can be communicated by modulation of protein dynamics without conformational change. The mechanisms, however, for communicating dynamic fluctuations between sites are debated. We provide a foundational theory for how allostery can occur as a function of low-frequency dynamics without a change in structure. We have generated coarse-grained models that describe the protein backbone motions of the CRP/FNR family transcription factors, CAP of Escherichia coli and GlxR of Corynebacterium glutamicum. The latter we demonstrate as a new exemplar for allostery without conformation change. We observe that binding the first molecule of cAMP ligand is correlated with modulation of the global normal modes and negative cooperativity for binding the second cAMP ligand without a change in mean structure. The theory makes key experimental predictions that are tested through an analysis of variant proteins by structural biology and isothermal calorimetry. Quantifying allostery as a free energy landscape revealed a protein "design space" that identified the inter- and intramolecular regulatory parameters that frame CRP/FNR family allostery. Furthermore, through analyzing CAP variants from diverse species, we demonstrate an evolutionary selection pressure to conserve residues crucial for allosteric control. This finding provides a link between the position of CRP/FNR transcription factors within the allosteric free energy landscapes and evolutionary selection pressures. Our study therefore reveals significant features of the mechanistic basis for allostery. Changes in low-frequency dynamics correlate with allosteric effects on ligand binding without the requirement for a defined spatial pathway. In addition to evolving suitable three-dimensional structures, CRP/FNR family transcription factors have

How to Achieve the Best SRF Performance: (Practical) Limitations and Possible Solutions

International Nuclear Information System (INIS)

Antoine, Claire Z

2014-01-01

This chapter presents in the first part the requirement for the surface preparation of RF Niobium cavities and its justification in term s of physical origin of limitation (e.g. cleanliness and field emission, influence of the surface treatments, morphology and surface damage, etc.). In the second part we discuss the different models describing the ultimate limits of SRF cavities, and we present one of the possible ways to overcome Niobium monopoly toward higher performances

How to Achieve the Best SRF Performance: (Practical) Limitations and Possible Solutions

Energy Technology Data Exchange (ETDEWEB)

Antoine, Claire Z [IRFU, Saclay (France)

2014-07-01

This chapter presents in the first part the requirement for the surface preparation of RF Niobium cavities and its justification in term s of physical origin of limitation (e.g. cleanliness and field emission, influence of the surface treatments, morphology and surface damage, etc.). In the second part we discuss the different models describing the ultimate limits of SRF cavities, and we present one of the possible ways to overcome Niobium monopoly toward higher performances.

The 'sensory tolerance limit': A hypothetical construct determining exercise performance?

Science.gov (United States)

Hureau, Thomas J; Romer, Lee M; Amann, Markus

2018-02-01

Neuromuscular fatigue compromises exercise performance and is determined by central and peripheral mechanisms. Interactions between the two components of fatigue can occur via neural pathways, including feedback and feedforward processes. This brief review discusses the influence of feedback and feedforward mechanisms on exercise limitation. In terms of feedback mechanisms, particular attention is given to group III/IV sensory neurons which link limb muscle with the central nervous system. Central corollary discharge, a copy of the neural drive from the brain to the working muscles, provides a signal from the motor system to sensory systems and is considered a feedforward mechanism that might influence fatigue and consequently exercise performance. We highlight findings from studies supporting the existence of a 'critical threshold of peripheral fatigue', a previously proposed hypothesis based on the idea that a negative feedback loop operates to protect the exercising limb muscle from severe threats to homeostasis during whole-body exercise. While the threshold theory remains to be disproven within a given task, it is not generalisable across different exercise modalities. The 'sensory tolerance limit', a more theoretical concept, may address this issue and explain exercise tolerance in more global terms and across exercise modalities. The 'sensory tolerance limit' can be viewed as a negative feedback loop which accounts for the sum of all feedback (locomotor muscles, respiratory muscles, organs, and muscles not directly involved in exercise) and feedforward signals processed within the central nervous system with the purpose of regulating the intensity of exercise to ensure that voluntary activity remains tolerable.

Design of coated standing nanowire array solar cell performing beyond the planar efficiency limits

Energy Technology Data Exchange (ETDEWEB)

Zeng, Yang; Ye, Qinghao; Shen, Wenzhong, E-mail: wzshen@sjtu.edu.cn [Institute of Solar Energy, and Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China)

2016-05-28

The single standing nanowire (SNW) solar cells have been proven to perform beyond the planar efficiency limits in both open-circuit voltage and internal quantum efficiency due to the built-in concentration and the shifting of the absorption front. However, the expandability of these nano-scale units to a macro-scale photovoltaic device remains unsolved. The main difficulty lies in the simultaneous preservation of an effective built-in concentration in each unit cell and a broadband high absorption capability of their array. Here, we have provided a detailed theoretical guideline for realizing a macro-scale solar cell that performs furthest beyond the planar limits. The key lies in a complementary design between the light-trapping of the single SNWs and that of the photonic crystal slab formed by the array. By tuning the hybrid HE modes of the SNWs through the thickness of a coaxial dielectric coating, the optimized coated SNW array can sustain an absorption rate over 97.5% for a period as large as 425 nm, which, together with the inherited carrier extraction advantage, leads to a cell efficiency increment of 30% over the planar limit. This work has demonstrated the viability of a large-size solar cell that performs beyond the planar limits.

What Limits Cardiac Performance during Exercise in Normal Subjects and in Healthy Fontan Patients?

Directory of Open Access Journals (Sweden)

André La Gerche

2010-01-01

Full Text Available Exercise is an important determinant of health but is significantly reduced in the patient with a univentricular circulation. Normal exercise physiology mandates an increase in pulmonary artery pressures which places an increased work demand on the right ventricle (RV. In a biventricular circulation with pathological increases in pulmonary vascular resistance and/or reductions in RV function, exercise-induced augmentation of cardiac output is limited. Left ventricular preload reserve is dependent upon flow through the pulmonary circulation and this requires adequate RV performance. In the Fontan patient, the reasons for exercise intolerance are complex. In those patients with myocardial dysfunction or other pathologies of the circulatory components, it is likely that these abnormalities serve as a limitation to cardiac performance during exercise. However, in the healthy Fontan patient, it may be the absence of a sub-pulmonary pump which limits normal increases in pulmonary pressures, trans-pulmonary flow requirements and cardiac output. If so, performance will be exquisitely dependent on pulmonary vascular resistance. This provides a potential explanation as to why pulmonary vasodilators may improve exercise tolerance. As has recently been demonstrated, these agents may offer an important new treatment strategy which directly addresses the physiological limitations in the Fontan patient.

Assessing control of postural stability in community-living older adults using performance-based limits of stability

DEFF Research Database (Denmark)

Jbabdi, Myriam; Boissy, Patrice; Hamel, Mathieu

2008-01-01

BACKGROUND: Balance disability measurements routinely used to identify fall risks in frail populations have limited value in the early detection of postural stability deficits in community-living older adults. The objectives of the study were to 1) measure performance-based limits of stability (LOS......-session performance variability during multiple trials using the performance-based LOS paradigm. METHODS: Twenty-four healthy community-living older adults (10 men, 14 women) aged between 62 to 85 (mean age +/- sd, 71.5 +/- 6 yrs) participated in the study. Subjects' performance-based LOS were established by asking...

Follow-up skeletal surveys for nonaccidental trauma: can a more limited survey be performed?

Energy Technology Data Exchange (ETDEWEB)

Harlan, Susan R. [University of Utah School of Medicine, Department of Radiology, Salt Lake City, UT (United States); Nixon, G.W.; Prince, Jeffrey S. [Primary Children' s Medical Center, Department of Medical Imaging, Salt Lake City, UT (United States); Campbell, Kristine A.; Hansen, Karen [University of Utah School of Medicine, Department of Pediatrics, Salt Lake City, UT (United States)

2009-09-15

Studies have demonstrated the value of the follow-up skeletal survey in identifying additional fractures, clarifying indeterminate findings, and improving dating of skeletal injuries in victims of physical abuse. To determine whether a more limited follow-up survey could yield the same radiologic data as a full follow-up survey. The study cohort comprised 101 children who had follow-up surveys that met our inclusion criteria. Consensus readings of both original and follow-up surveys were performed by two pediatric radiologists. These results were compared to determine additional findings from the follow-up surveys. Limited skeletal survey protocols were evaluated to determine whether they would detect the same fractures seen with a complete osseous survey. In the 101 children 244 fractures were identified on the initial osseous survey. Follow-up surveys demonstrated new information in 38 children (37.6%). A 15-view limited follow-up survey identified all additional information seen on the complete follow-up survey. Our data demonstrate that a 15-view limited follow-up skeletal survey could be performed without missing clinically significant new fractures and still allow proper identification of confirmed fractures or normal findings. A limited survey would decrease radiation dose in children. (orig.)

Follow-up skeletal surveys for nonaccidental trauma: can a more limited survey be performed?

International Nuclear Information System (INIS)

Harlan, Susan R.; Nixon, G.W.; Prince, Jeffrey S.; Campbell, Kristine A.; Hansen, Karen

2009-01-01

Studies have demonstrated the value of the follow-up skeletal survey in identifying additional fractures, clarifying indeterminate findings, and improving dating of skeletal injuries in victims of physical abuse. To determine whether a more limited follow-up survey could yield the same radiologic data as a full follow-up survey. The study cohort comprised 101 children who had follow-up surveys that met our inclusion criteria. Consensus readings of both original and follow-up surveys were performed by two pediatric radiologists. These results were compared to determine additional findings from the follow-up surveys. Limited skeletal survey protocols were evaluated to determine whether they would detect the same fractures seen with a complete osseous survey. In the 101 children 244 fractures were identified on the initial osseous survey. Follow-up surveys demonstrated new information in 38 children (37.6%). A 15-view limited follow-up survey identified all additional information seen on the complete follow-up survey. Our data demonstrate that a 15-view limited follow-up skeletal survey could be performed without missing clinically significant new fractures and still allow proper identification of confirmed fractures or normal findings. A limited survey would decrease radiation dose in children. (orig.)

Limitations in dual-task performance

NARCIS (Netherlands)

Pannebakker, Merel Mathilde

2009-01-01

In this thesis, the effect of information-processing overload on working-memory dependent information processing was examined using dual-task paradigms. The experiments described strengthen the importance of a functional explanation for dual-task limitations. First, it showed evidence for a unified

Rotary engine performance limits predicted by a zero-dimensional model

Science.gov (United States)

Bartrand, Timothy A.; Willis, Edward A.

1992-01-01

A parametric study was performed to determine the performance limits of a rotary combustion engine. This study shows how well increasing the combustion rate, insulating, and turbocharging increase brake power and decrease fuel consumption. Several generalizations can be made from the findings. First, it was shown that the fastest combustion rate is not necessarily the best combustion rate. Second, several engine insulation schemes were employed for a turbocharged engine. Performance improved only for a highly insulated engine. Finally, the variability of turbocompounding and the influence of exhaust port shape were calculated. Rotary engines performance was predicted by an improved zero-dimensional computer model based on a model developed at the Massachusetts Institute of Technology in the 1980's. Independent variables in the study include turbocharging, manifold pressures, wall thermal properties, leakage area, and exhaust port geometry. Additions to the computer programs since its results were last published include turbocharging, manifold modeling, and improved friction power loss calculation. The baseline engine for this study is a single rotor 650 cc direct-injection stratified-charge engine with aluminum housings and a stainless steel rotor. Engine maps are provided for the baseline and turbocharged versions of the engine.

A general method for assessing brain-computer interface performance and its limitations

Science.gov (United States)

Hill, N. Jeremy; Häuser, Ann-Katrin; Schalk, Gerwin

2014-04-01

Objective. When researchers evaluate brain-computer interface (BCI) systems, we want quantitative answers to questions such as: How good is the system’s performance? How good does it need to be? and: Is it capable of reaching the desired level in future? In response to the current lack of objective, quantitative, study-independent approaches, we introduce methods that help to address such questions. We identified three challenges: (I) the need for efficient measurement techniques that adapt rapidly and reliably to capture a wide range of performance levels; (II) the need to express results in a way that allows comparison between similar but non-identical tasks; (III) the need to measure the extent to which certain components of a BCI system (e.g. the signal processing pipeline) not only support BCI performance, but also potentially restrict the maximum level it can reach. Approach. For challenge (I), we developed an automatic staircase method that adjusted task difficulty adaptively along a single abstract axis. For challenge (II), we used the rate of information gain between two Bernoulli distributions: one reflecting the observed success rate, the other reflecting chance performance estimated by a matched random-walk method. This measure includes Wolpaw’s information transfer rate as a special case, but addresses the latter’s limitations including its restriction to item-selection tasks. To validate our approach and address challenge (III), we compared four healthy subjects’ performance using an EEG-based BCI, a ‘Direct Controller’ (a high-performance hardware input device), and a ‘Pseudo-BCI Controller’ (the same input device, but with control signals processed by the BCI signal processing pipeline). Main results. Our results confirm the repeatability and validity of our measures, and indicate that our BCI signal processing pipeline reduced attainable performance by about 33% (21 bits min-1). Significance. Our approach provides a flexible basis

Optimizing the performance and structure of the D0 Collie confidence limit evaluator

Energy Technology Data Exchange (ETDEWEB)

Fishchler, Mark; /Fermilab

2010-07-01

D0 Collie is a program used to perform limit calculations based on ensembles of pseudo-experiments ('PEs'). Since the application of this program to the crucial Higgs mass limit is quite CPU intensive, it has been deemed important to carefully review this program, with an eye toward identifying and implementing potential performance improvements. At the same time, we identify any coding errors or opportunities for potential structural (or algorithm) improvement discovered in the course of gaining sufficient understanding of the workings of Collie to sensibly explore for optimizations. Based on a careful analysis of the program, a series of code changes with potential for improving performance has been identified. The implementation and evaluation of the most important parts of this series has been done, with gratifying speedup results. The bottom line: We have identified and implemented changes leading to a factor of 2.19 speedup in the example program provided, and expected to translate to a factor of roughly 4 speedup in typical realistic usage.

Performance Limiting Effects in Power Generation from Salinity Gradients by Pressure Retarded Osmosis

KAUST Repository

Yip, Ngai Yin; Elimelech, Menachem

2011-01-01

Pressure retarded osmosis has the potential to utilize the free energy of mixing when fresh river water flows into the sea for clean and renewable power generation. Here, we present a systematic investigation of the performance limiting phenomena

Metabolic factors limiting performance in marathon runners.

Science.gov (United States)

Rapoport, Benjamin I

2010-10-21

Each year in the past three decades has seen hundreds of thousands of runners register to run a major marathon. Of those who attempt to race over the marathon distance of 26 miles and 385 yards (42.195 kilometers), more than two-fifths experience severe and performance-limiting depletion of physiologic carbohydrate reserves (a phenomenon known as 'hitting the wall'), and thousands drop out before reaching the finish lines (approximately 1-2% of those who start). Analyses of endurance physiology have often either used coarse approximations to suggest that human glycogen reserves are insufficient to fuel a marathon (making 'hitting the wall' seem inevitable), or implied that maximal glycogen loading is required in order to complete a marathon without 'hitting the wall.' The present computational study demonstrates that the energetic constraints on endurance runners are more subtle, and depend on several physiologic variables including the muscle mass distribution, liver and muscle glycogen densities, and running speed (exercise intensity as a fraction of aerobic capacity) of individual runners, in personalized but nevertheless quantifiable and predictable ways. The analytic approach presented here is used to estimate the distance at which runners will exhaust their glycogen stores as a function of running intensity. In so doing it also provides a basis for guidelines ensuring the safety and optimizing the performance of endurance runners, both by setting personally appropriate paces and by prescribing midrace fueling requirements for avoiding 'the wall.' The present analysis also sheds physiologically principled light on important standards in marathon running that until now have remained empirically defined: The qualifying times for the Boston Marathon.

Metabolic factors limiting performance in marathon runners.

Directory of Open Access Journals (Sweden)

Benjamin I Rapoport

2010-10-01

Full Text Available Each year in the past three decades has seen hundreds of thousands of runners register to run a major marathon. Of those who attempt to race over the marathon distance of 26 miles and 385 yards (42.195 kilometers, more than two-fifths experience severe and performance-limiting depletion of physiologic carbohydrate reserves (a phenomenon known as 'hitting the wall', and thousands drop out before reaching the finish lines (approximately 1-2% of those who start. Analyses of endurance physiology have often either used coarse approximations to suggest that human glycogen reserves are insufficient to fuel a marathon (making 'hitting the wall' seem inevitable, or implied that maximal glycogen loading is required in order to complete a marathon without 'hitting the wall.' The present computational study demonstrates that the energetic constraints on endurance runners are more subtle, and depend on several physiologic variables including the muscle mass distribution, liver and muscle glycogen densities, and running speed (exercise intensity as a fraction of aerobic capacity of individual runners, in personalized but nevertheless quantifiable and predictable ways. The analytic approach presented here is used to estimate the distance at which runners will exhaust their glycogen stores as a function of running intensity. In so doing it also provides a basis for guidelines ensuring the safety and optimizing the performance of endurance runners, both by setting personally appropriate paces and by prescribing midrace fueling requirements for avoiding 'the wall.' The present analysis also sheds physiologically principled light on important standards in marathon running that until now have remained empirically defined: The qualifying times for the Boston Marathon.

Above the nominal limit performance evaluation of multiwavelength optical code-division multiple-access systems

Science.gov (United States)

Inaty, Elie; Raad, Robert; Fortier, Paul; Shalaby, Hossam M. H.

2009-03-01

We provide an analysis for the performance of a multiwavelength optical code-division multiple-access (MW-OCDMA) network when the system is working above the nominal transmission rate limit imposed by passive encoding-decoding operation. We address the problem of overlapping in such a system and how it can directly affect the bit error rate (BER). A unified mathematical framework is presented under the assumption of one-coincidence sequences with nonrepeating wavelengths. A closed form expression of the multiple access interference limited BER is provided as a function of different system parameters. Results show that the performance of the MW-OCDMA system can be critically affected when working above the nominal limit, an event that can happen when the network operates at a high transmission rate. In addition, the impact of the derived error probability on the performance of two newly proposed medium access control (MAC) protocols, the S-ALOHA and the R3T, is also investigated. It is shown that for low transmission rates, the S-ALOHA is better than the R3T, while the R3T is better at very high transmission rates. In general, it is postulated that the R3T protocol suffers a higher delay mainly because of the presence of additional modes.

Performance limiting effects in X-band accelerators

Directory of Open Access Journals (Sweden)

Faya Wang

2011-01-01

Full Text Available Acceleration gradient is a critical parameter for the design of future TeV-scale linear colliders. The major obstacle to higher gradient in room-temperature accelerators is rf breakdown, which is still a very mysterious phenomenon that depends on the geometry and material of the accelerator as well as the input power and operating frequency. Pulsed heating has been associated with breakdown for many years; however, there have been no experiments that clearly separate field and heating effects on the breakdown rate. Recently, such experiments have been performed at SLAC with both standing-wave and traveling-wave structures. These experiments have demonstrated that pulsed heating is limiting the gradient. Nevertheless the X-band structures breakdown studies show damage to the iris surfaces in locations of high electric field rather than of high magnetic field after thousands of breakdowns. It is not yet clear how the relative roles of electric field, magnetic field, and heating factor into the damage caused by rf breakdown. Thus, a dual-moded cavity has been designed to better study the electric field, magnetic field, and pulsed heating effects on breakdown damage.

Driving performance at lateral system limits during partially automated driving.

Science.gov (United States)

Naujoks, Frederik; Purucker, Christian; Wiedemann, Katharina; Neukum, Alexandra; Wolter, Stefan; Steiger, Reid

2017-11-01

This study investigated driver performance during system limits of partially automated driving. Using a motion-based driving simulator, drivers encountered different situations in which a partially automated vehicle could no longer safely keep the lateral guidance. Drivers were distracted by a non-driving related task on a touch display or driving without an additional secondary task. While driving in partially automated mode drivers could either take their hands off the steering wheel for only a short period of time (10s, so-called 'Hands-on' variant) or for an extended period of time (120s, so-called 'Hands-off' variant). When the system limit was reached (e.g., when entering a work zone with temporary lines), the lateral vehicle control by the automation was suddenly discontinued and a take-over request was issued to the drivers. Regardless of the hands-off interval and the availability of a secondary task, all drivers managed the transition to manual driving safely. No lane exceedances were observed and the situations were rated as 'harmless' by the drivers. The lack of difference between the hands-off intervals can be partly attributed to the fact that most of the drivers kept contact to the steering wheel, even in the hands-off condition. Although all drivers were able to control the system limits, most of them could not explain why exactly the take-over request was issued. The average helpfulness of the take-over request was rated on an intermediate level. Consequently, providing drivers with information about the reason for a system limit can be recommended. Copyright © 2017 Elsevier Ltd. All rights reserved.

Performance limitations of piezoelectric and force feedback electrostatic transducers in different applications

International Nuclear Information System (INIS)

Hadjiloucas, S; Walker, G C; Bowen, J W; Karatzas, L S

2009-01-01

Current limitations in piezoelectric and electrostatic transducers are discussed. A force-feedback electrostatic transducer capable of operating at bandwidths up to 20 kHz is described. Advantages of the proposed design are a linearised operation which simplifies the feedback control aspects and robustness of the performance characteristics to environmental perturbations. Applications in nanotechnology, optical sciences and acoustics are discussed.

Performance limitations of piezoelectric and force feedback electrostatic transducers in different applications

Energy Technology Data Exchange (ETDEWEB)

Hadjiloucas, S; Walker, G C; Bowen, J W [Cybernetics, School of Systems Engineering, University of Reading, RG6 6AY (United Kingdom); Karatzas, L S, E-mail: s.hadjiloucas@reading.ac.u [Temasek Polytechnic, School of Engineering, 21 Tampines Avenue 1, Singapore, 529757 (Singapore)

2009-07-01

Current limitations in piezoelectric and electrostatic transducers are discussed. A force-feedback electrostatic transducer capable of operating at bandwidths up to 20 kHz is described. Advantages of the proposed design are a linearised operation which simplifies the feedback control aspects and robustness of the performance characteristics to environmental perturbations. Applications in nanotechnology, optical sciences and acoustics are discussed.

Nogo receptor 1 limits tactile task performance independent of basal anatomical plasticity.

Directory of Open Access Journals (Sweden)

Jennifer I Park

Full Text Available The genes that govern how experience refines neural circuitry and alters synaptic structural plasticity are poorly understood. The nogo-66 receptor 1 gene (ngr1 is one candidate that may restrict the rate of learning as well as basal anatomical plasticity in adult cerebral cortex. To investigate if ngr1 limits the rate of learning we tested adult ngr1 null mice on a tactile learning task. Ngr1 mutants display greater overall performance despite a normal rate of improvement on the gap-cross assay, a whisker-dependent learning paradigm. To determine if ngr1 restricts basal anatomical plasticity in the associated sensory cortex, we repeatedly imaged dendritic spines and axonal varicosities of both constitutive and conditional adult ngr1 mutant mice in somatosensory barrel cortex for two weeks through cranial windows with two-photon chronic in vivo imaging. Neither constant nor acute deletion of ngr1 affected turnover or stability of dendritic spines or axonal boutons. The improved performance on the gap-cross task is not attributable to greater motor coordination, as ngr1 mutant mice possess a mild deficit in overall performance and a normal learning rate on the rotarod, a motor task. Mice lacking ngr1 also exhibit normal induction of tone-associated fear conditioning yet accelerated fear extinction and impaired consolidation. Thus, ngr1 alters tactile and motor task performance but does not appear to limit the rate of tactile or motor learning, nor determine the low set point for synaptic turnover in sensory cortex.

Crush performance of redwood for developing design procedures for impact limiters

International Nuclear Information System (INIS)

Cramer, S.M.; Hermanson, J.C.; McMurtry, W.M.

1995-01-01

Containers for the transportation of hazardous and radioactive materials incorporate redwood in impact limiters. Redwood is an excellent energy absorber, but only the most simplistic information exists on its crush properties. Tbe stress-strain interrelationship for any wood species subject to three-dimensional stresses is largely unknown for any all stress condition and wood behavior at both high strains and high strain-rates is known only in general terms. Both stress-strain and crush failure theories have been developed based only on uniaxial load tests. The anisotropy of wood adds an additional complexity to measuring wood response and developing suitable theories to describe it. A long history of wood utilization in the building industry has led to design procedures and property information related to simple uniaxial loadings that do not inflict damage to the wood. This lack of knowledge may be surprising for a material that has a long history of engineered use, but the result is difficulty in utilizing wood in more sophisticated designs such as impact limiters. This study provides a step toward filling the information gap on wood material response for high performance applications such as impact limiters

Born to run. Studying the limits of human performance

Directory of Open Access Journals (Sweden)

Murray Andrew

2012-07-01

Full Text Available Abstract It is recognised that regular physical activity and a high level of fitness are powerful predictors of positive health outcomes. There is a long and rich history of significant feats of human endurance with some, for example, the death of the first marathon runner, Pheidippides, associated with negative health outcomes. Early studies on endurance running used X-ray and interview techniques to evaluate competitors and comment on performance. Since then, comparatively few studies have looked at runners competing in distances longer than a marathon. Those that have, tend to show significant musculoskeletal injuries and a remarkable level of adaptation to this endurance load. The TransEurope Footrace Project followed ultra-endurance runners aiming to complete 4,500 Km of running in 64 days across Europe. This pioneering study will assess the impact of extreme endurance on human physiology; analysing musculoskeletal and other tissue/organ injuries, and the body's potential ability to adapt to extreme physiological stress. The results will be of interest not only to endurance runners, but to anyone interested in the limits of human performance. Please see related article: http://www.biomedcentral.com/1741-7015/10/78

Limitations in dual-task performance

OpenAIRE

Pannebakker, Merel Mathilde

2009-01-01

In this thesis, the effect of information-processing overload on working-memory dependent information processing was examined using dual-task paradigms. The experiments described strengthen the importance of a functional explanation for dual-task limitations. First, it showed evidence for a unified coding medium (as put forward in the theory of event coding; Hommel, Müsseler, Aschersleben, & Prinz, 2001) in which features, operations and responses are available and can influence each other. A...

Work Functioning Among Firefighters: A Comparison Between Self-Reported Limitations and Functional Task Performance.

Science.gov (United States)

MacDermid, Joy C; Tang, Kenneth; Sinden, Kathryn E; D'Amico, Robert

2018-05-25

Purpose Performance-based and disease indicators have been widely studied in firefighters; self-reported work role limitations have not. The aim of this study was to describe the distributions and correlations of a generic self-reported Work Limitations Questionnaire (WLQ-26) and firefighting-specific task performance-based tests. Methods Active firefighters from the City of Hamilton Fire Services (n = 293) were recruited. Participants completed the WLQ-26 to quantify on-the-job difficulties over five work domains: work scheduling (4 items), output demands (7 items), physical demands (8 items), mental demands (4 items), and social demands (3 items). A subset of participants (n = 149) were also assessed on hose drag and stair climb with a high-rise pack performance-based tests. Descriptive statistics and correlations were used to compare item/subscale performance; and to describe the inter-relationships between tests. Results The mean WLQ-26 item scores (/5) ranged from 4.1 to 4.4 (median = 5 for all items); most firefighters (54.5-80.5%) selected "difficult none of the time" response option on all items. A substantial ceiling effect was observed across all five WLQ-26 subscales as 44.0-55.6% were in the highest category. Subscale means ranged from 61.8 (social demands) to 78.7 (output demands and physical demands). Internal consistency exceeded 0.90 on all subscales. For the hose drag task, the mean time-to-completion was 48.0 s (SD = 14.5; range 20.4-95.0). For the stair climb task, the mean time-to-completion was 76.7 s (SD = 37.2; range 21.0-218.0). There were no significant correlations between self-report work limitations and performance of firefighting tasks. Conclusions The WLQ-26 measured five domains, but had ceiling effects in firefighters. Performance-based testing showed wider score range, lacked ceiling effects and did not correlate to the WLQ-26. A firefighter-specific, self-report role functioning scale may be needed to identify

Impact of optical hard limiter on the performance of an optical overlapped-code division multiple access system

Science.gov (United States)

Inaty, Elie; Raad, Robert; Tablieh, Nicole

2011-08-01

Throughout this paper, a closed form expression of the multiple access interference (MAI) limited bit error rate (BER) is provided for the multiwavelength optical code-division multiple-access system when the system is working above the nominal transmission rate limit imposed by the passive encoding-decoding operation. This system is known in literature as the optical overlapped code division multiple access (OV-CDMA) system. A unified analytical framework is presented emphasizing the impact of optical hard limiter (OHL) on the BER performance of such a system. Results show that the performance of the OV-CDMA system may be highly improved when using OHL preprocessing at the receiver side.

Unmasking Determinants of Specificity in the Human Kinome

DEFF Research Database (Denmark)

Creixell, Pau; Palmeri, Antonio; Miller, Chad J.

2015-01-01

spanning distant regions. Our results reveal a likely role for inter-residue allostery in specificity and an evolutionary decoupling of kinase activity and specificity, which appear loaded on independent groups of residues. Finally, we uncover similar properties driving SH2 domain specificity......Protein kinases control cellular responses to environmental cues by swift and accurate signal processing. Breakdowns in this high-fidelity capability are a driving force in cancer and other diseases. Thus, our limited understanding of which amino acids in the kinase domain encode substrate...

RELATIONSHIP BETWEEN FUNCTIONAL LIMITATIONS OF THE LOCOMOTOR SYSTEM AND PERFORMANCE IN JUDO

Directory of Open Access Journals (Sweden)

Boguszewski Dariusz

2017-09-01

Full Text Available Introduction. The high demands imposed by judo with regard to physical fitness can predispose athletes practising this sport to injury. The aim of the current study was to determine the relationship between the degree of functional limitations and performance outcomes in judo athletes. Material and methods. The study involved 23 judo athletes aged 17-27 years. For the purpose of carrying out comparative analyses, the judokas were divided into two groups according to their level of achievement. The first group consisted of medallists in international tournaments and Polish championships, and the second group was composed of non-medallists. The research tool used was the Functional Movement Screen test battery, which included seven exercise tests whose performance was rated on a scale from 0 to 3. Relationships between variables were assessed using Spearman’s rho correlation coefficients. Inter-group differences were determined by means of the Mann-Whitney U test, and differences between the left and right side of the body in bilateral tests were examined using the Wilcoxon test (statistical significance was set at p ≤ 0.05. Results. The total score for the FMS test was significantly higher (p < 0.05 in judo athletes who had a higher level of achievement. Scores below 14 points, which were indicative of high susceptibility to injury, were received by two athletes from the group of medallists and 8 non-medallists. Major asymmetries were not found in the subjects; significant differences were observed only in the shoulder mobility test in senior judokas (p < 0.05 and non-medallists (p < 0.01. Conclusions. Judo athletes who had better performance outcomes in competitions had higher scores in the FMS test. Functional limitations can have an impact on the outcomes of performance in judo; their degree is indicative of the quality of the movement as well as of susceptibility to injury.

Limits to sustainable muscle performance: interaction between glycolysis and oxidative phosphorylation.

Science.gov (United States)

Conley, K E; Kemper, W F; Crowther, G J

2001-09-01

This paper proposes a mechanism responsible for setting the sustainable level of muscle performance. Our contentions are that the sustainable work rate is determined (i) at the muscle level, (ii) by the ability to maintain ATP supply and (iii) by the products of glycolysis that may inhibit the signal for oxidative phosphorylation. We argue below that no single factor 'limits' sustainable performance, but rather that the flux through and the interaction between glycolysis and oxidative phosphorylation set the level of sustainable ATP supply. This argument is based on magnetic resonance spectroscopy measurements of the sources and sinks for energy in vivo in human muscle and rattlesnake tailshaker muscle during sustained contractions. These measurements show that glycolysis provides between 20% (human muscle) and 40% (tailshaker muscle) of the ATP supply during sustained contractions in these muscles. We cite evidence showing that this high glycolytic flux does not reflect an O(2) limitation or mitochondria operating at their capacity. Instead, this flux reflects a pathway independent of oxidative phosphorylation for ATP supply during aerobic exercise. The consequence of this high glycolytic flux is accumulation of H(+), which we argue inhibits the rise in the signal activating oxidative phosphorylation, thereby restricting oxidative ATP supply to below the oxidative capacity. Thus, both glycolysis and oxidative phosphorylation play important roles in setting the highest steady-state ATP synthesis flux and thereby determine the sustainable level of work by exercising muscle.

Nanocomposites of graphene oxide and upconversion rare-earth nanocrystals with superior optical limiting performance

KAUST Repository

Wei, Wei; He, Tingchao; Teng, Xue; Wu, Shixin; Ma, Lin; Zhang, Hua; Ma, Jan; Yang, Yanhui; Chen, Hongyu; Han, Yu; Sun, Handong; Huang, Ling

2012-01-01

), show excellent performance in optical limiting (OL); however, the wavelengths of currently used lasers for OL studies mainly focus on either 532 or 1064 nm. To design new-generation OL materials working at other optical regions, such as the NIR, a novel

Performance of intact and partially degraded concrete barriers in limiting mass transport

International Nuclear Information System (INIS)

Walton, J.C.

1992-06-01

Mass transport through concrete barriers and release rate from concrete vaults are quantitatively evaluated. The thorny issue of appropriate diffusion coefficients for use in performance assessment calculations is covered, with no ultimate solution found. Release from monolithic concrete vaults composed of concrete waste forms is estimated with a semi-analytical solution. A parametric study illustrates the importance of different parameters on release. A second situation of importance is the role of a concrete shell or vault placed around typical waste forms in limiting mass transport. In both situations, the primary factor controlling concrete performance is cracks. The implications of leaching behavior on likely groundwater concentrations is examined. Frequently, lower groundwater concentrations can be expected in the absence of engineered covers that reduce infiltration

Effects of Heat of Vaporization and Octane Sensitivity on Knock-Limited Spark Ignition Engine Performance

Energy Technology Data Exchange (ETDEWEB)

Ratcliff, Matthew A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Burton, Jonathan L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Sindler, Petr [National Renewable Energy Laboratory (NREL), Golden, CO (United States); McCormick, Robert L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Christensen, Earl D [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Fouts, Lisa A [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2018-04-03

Knock-limited loads for a set of surrogate gasolines all having nominal 100 research octane number (RON), approximately 11 octane sensitivity (S), and a heat of vaporization (HOV) range of 390 to 595 kJ/kg at 25 degrees C were investigated. A single-cylinder spark-ignition engine derived from a General Motors Ecotec direct injection (DI) engine was used to perform load sweeps at a fixed intake air temperature (IAT) of 50 degrees C, as well as knock-limited load measurements across a range of IATs up to 90 degrees C. Both DI and pre-vaporized fuel (supplied by a fuel injector mounted far upstream of the intake valves and heated intake runner walls) experiments were performed to separate the chemical and thermal effects of the fuels' knock resistance. The DI load sweeps at 50 degrees C intake air temperature showed no effect of HOV on the knock-limited performance. The data suggest that HOV acts as a thermal contributor to S under the conditions studied. Measurement of knock-limited loads from the IAT sweeps for DI at late combustion phasing showed that a 40 vol% ethanol (E40) blend provided additional knock resistance at the highest temperatures, compared to a 20 vol% ethanol blend and hydrocarbon fuel with similar RON and S. Using the pre-vaporized fuel system, all the high S fuels produced nearly identical knock-limited loads at each temperature across the range of IATs studied. For these fuels RON ranged from 99.2 to 101.1 and S ranged from 9.4 to 12.2, with E40 having the lowest RON and highest S. The higher knock-limited loads for E40 at the highest IATs examined were consistent with the slightly higher S for this fuel, and the lower engine operating condition K values arising from use of this fuel. The study highlights how fuel HOV can affect the temperature at intake valve closing, and consequently the pressure-temperature history of the end gas leading to more negative values of K, thereby enhancing the effect of S on knock resistance.

Performance limitations of imaging microscopes for soft x-ray applications

International Nuclear Information System (INIS)

Lewotsky, K.L.; Kotha, A.; Harvey, J.E.

1993-01-01

Recent advances in the fabrication of nanometer-scale multilayer structures have yielded high-reflectance mirrors operating at near-normal incidence for soft X-ray wavelengths. These developments have stimulated renewed interest in high-resolution soft X-ray microscopy. The design of a Schwarzschild imaging microscope for soft X-ray applications has been reported by Hoover and Shealy. Based upon a geometrical ray-trace analysis of the residual design errors, diffraction-limited performance at a wavelength of 100 angstrom was predicted over an object size (diameter) of 0.4 mm. In this paper the authors expand upon the previous analysis of the Schwarzschild X-ray microscope design by determining the total image degradation due to diffraction, geometrical aberrations, alignment errors, and realistic assumptions concerning optical fabrication errors. NASA's Optical Surface Analysis Code (OSAC) is used to model the image degradation effects of residual surface irregularities over the entire range of relevant spatial frequencies. This includes small angle scattering effects due to mid spatial frequency surface errors falling between the traditional figure and finish specifications. Performance predictions are presented parametrically to provide some insight into the optical fabrication and alignment tolerances necessary to meet a particular image quality requirement

Prospects and performance limitations for Cu-Zn-Sn-S-Se photovoltaic technology.

Science.gov (United States)

Mitzi, David B; Gunawan, Oki; Todorov, Teodor K; Barkhouse, D Aaron R

2013-08-13

While cadmium telluride and copper-indium-gallium-sulfide-selenide (CIGSSe) solar cells have either already surpassed (for CdTe) or reached (for CIGSSe) the 1 GW yr⁻¹ production level, highlighting the promise of these rapidly growing thin-film technologies, reliance on the heavy metal cadmium and scarce elements indium and tellurium has prompted concern about scalability towards the terawatt level. Despite recent advances in structurally related copper-zinc-tin-sulfide-selenide (CZTSSe) absorbers, in which indium from CIGSSe is replaced with more plentiful and lower cost zinc and tin, there is still a sizeable performance gap between the kesterite CZTSSe and the more mature CdTe and CIGSSe technologies. This review will discuss recent progress in the CZTSSe field, especially focusing on a direct comparison with analogous higher performing CIGSSe to probe the performance bottlenecks in Earth-abundant kesterite devices. Key limitations in the current generation of CZTSSe devices include a shortfall in open circuit voltage relative to the absorber band gap and secondarily a high series resistance, which contributes to a lower device fill factor. Understanding and addressing these performance issues should yield closer performance parity between CZTSSe and CdTe/CIGSSe absorbers and hopefully facilitate a successful launch of commercialization for the kesterite-based technology.

Binding of anions in triply interlocked coordination catenanes and dynamic allostery for dehalogenation reactions† †Electronic supplementary information (ESI) available: Characterization data and additional tables and figures. CCDC 1515722 and 1515723. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7sc04070a

Science.gov (United States)

Yang, Linlin; Jing, Xu; An, Bowen; Yang, Yang

2017-01-01

By synergistic combination of multicomponent self-assembly and template-directed approaches, triply interlocked metal organic catenanes that consist of two isolated chirally identical tetrahedrons were constructed and stabilized as thermodynamic minima. In the presence of suitable template anions, the structural conversion from the isolated tetrahedral conformers into locked catenanes occurred via the cleavage of an intrinsically reversible coordination bond in each of the tetrahedrons, followed by the reengineering and interlocking of two fragments with the regeneration of the broken coordination bonds. The presence of several kinds of individual pocket that were attributed to the triply interlocked patterns enabled the possibility of encapsulating different anions, allowing the dynamic allostery between the unlocked/locked conformers to promote the dehalogenation reaction of 3-bromo-cyclohexene efficiently, as with the use of dehalogenase enzymes. The interlocked structures could be unlocked into two individual tetrahedrons through removal of the well-matched anion templates. The stability and reversibility of the locked/unlocked structures were further confirmed by the catching/releasing process that accompanied emission switching, providing opportunities for the system to be a dynamic molecular logic system. PMID:29675152

Metamaterial polarization converter analysis: limits of performance

DEFF Research Database (Denmark)

Markovich, Dmitry L.; Andryieuski, Andrei; Zalkovskij, Maksim

2013-01-01

and a single layer with a ground plane can have 100 % polarization conversion efficiency. We tested our conclusions numerically reaching the designated limits of efficiency using a simple metamaterial design. Our general analysis provides useful guidelines for the metamaterial polarization converter design......In this paper, we analyze the theoretical limits of a metamaterial-based converter with orthogonal linear eigenpolarizations that allow linear-to-elliptical polarization transformation with any desired ellipticity and ellipse orientation. We employ the transmission line approach providing a needed...... level of the design generalization. Our analysis reveals that the maximal conversion efficiency for transmission through a single metamaterial layer is 50 %, while the realistic reflection configuration can give the conversion efficiency up to 90 %. We show that a double layer transmission converter...

Thriving at the limit: Differential reproductive performance in range-edge populations of a Mediterranean sclerophyll (Olea europaea)

Science.gov (United States)

Granado-Yela, Carlos; Balaguer, Luis; García-Verdugo, Carlos; Carrillo, Katty; Méndez, Marcos

2013-10-01

Peripheral populations are often lumped together on the assumption of thriving in marginal habitats where reproductive performance is compromised. We have tested this hypothesis in peripheral populations of wild olive tree (Olea europaea L.) presumably limited by different factors at the westernmost limit of the species range. Additionally, we hypothesized that differences in reproductive outcome among populations are better explained by site-specific environmental conditions (PAR, soil water, soil nutrients, air humidity and air temperature) than by differences in phenotypic traits (tree size and leaf traits). To test these hypotheses, we assessed the number of flowering trees, the flowering intensity, fruit set and seed viability in eight populations for three consecutive years. Our findings provided sufficient evidence to reject the first hypothesis. Peripheral populations that occur under oceanic conditions, resembling the Tertiary subtropical climate, consistently presented higher values for all components of reproductive performance than those at the thermal and rainfall tolerance limits. In support of our second hypothesis, the variation in reproductive performance among populations was primarily accounted for by local environmental conditions. Leaf traits, however, also explained reproductive variation but to a lesser extent. Finally, we found that small changes in tree size may cause large differences in reproductive performance. This close relationship between tree size and reproductive performance suggests that any impact on population size structure would likely jeopardize persistence and expansion at the range edge. Our results suggest that reproductive performance of wild olive trees was not shaped by the population geographic position within the species range, but by the interaction between local environment, as the main driver, and individual phenotypic traits.

BER Performance Simulation of Generalized MC DS-CDMA System with Time-Limited Blackman Chip Waveform

Directory of Open Access Journals (Sweden)

I. Develi

2010-09-01

Full Text Available Multiple access interference encountered in multicarrier direct sequence-code division multiple access (MC DS-CDMA is the most important difficulty that depends mainly on the correlation properties of the spreading sequences as well as the shape of the chip waveforms employed. In this paper, bit error rate (BER performance of the generalized MC DS-CDMA system that employs time-limited Blackman chip waveform is presented for Nakagami-m fading channels. Simulation results show that the use of Blackman chip waveform can improve the BER performance of the generalized MC DS-CDMA system, as compared to the performances achieved by using timelimited chip waveforms in the literature.

Design Dependent Cutoff Frequency of Nanotransistors Near the Ultimate Performance Limit

Science.gov (United States)

Kordrostami, Zoheir; Sheikhi, M. Hossein; Zarifkar, Abbas

2012-12-01

We have studied the effect of different structural designs of double gate MOSFETs (DG-MOSFETs) and carbon nanotube field effect transistors (CNTFETs) on the cutoff frequency (fT). The effects of metallic contacts with Schottky barriers, gate work function, dual material gate (DMG), halo doped channel and lightly doped drain and source (LDDS) architectures on the fT have been investigated for DG-MOSFETs and CNTFETs and the design dependent fT for both types of transistors has been studied for the first time. The simulations are based on the Schrödinger-Poisson solvers developed for each nanotransistor separately. The ballistic limit has been studied as the ultimate performance limit of the DG-MOSFETs and CNTFETs. The results of this paper, for the first time, show how some designations used for modification of short channel effects or current-voltage characteristics affect the fT. The results revealed that the cutoff frequencies of both types of the transistors exhibit the same behavior with changing design parameters. We have shown that the Schottky barriers, parasitic capacitances and halo doping reduce the fT and have proposed the DMG and LDDS artchitectures as ways to increase the fT for DG-MOSFETs and CNTFETs for the first time.

Preliminary disposal limits, plume interaction factors, and final disposal limits

Energy Technology Data Exchange (ETDEWEB)

Flach, G. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2018-01-11

In the 2008 E-Area Performance Assessment (PA), each final disposal limit was constructed as the product of a preliminary disposal limit and a plume interaction factor. The following mathematical development demonstrates that performance objectives are generally expected to be satisfied with high confidence under practical PA scenarios using this method. However, radionuclides that experience significant decay between a disposal unit and the 100-meter boundary, such as H-3 and Sr-90, can challenge performance objectives, depending on the disposed-of waste composition, facility geometry, and the significance of the plume interaction factor. Pros and cons of analyzing single disposal units or multiple disposal units as a group in the preliminary disposal limits analysis are also identified.

Impact of power limitations on the performance of WLANs for home networking applications

OpenAIRE

Armour, SMD; Lee, BS; Doufexi, A; Nix, AR; Bull, DR

2001-01-01

This paper considers the application of 5 GHz wireless LAN technology to home networking applications. An assessment of physical layer performance is presented in the form of the achievable data rate as a function of received signal to noise ratio. The transmit power limitations imposed by the relevant regulatory bodies are also summarised. Based on this information, a state of the art propagation modelling tool is used to evaluate the coverage achieved by a WLAN system in an example resident...

Price performance following stock's IPO in different price limit systems

Science.gov (United States)

Wu, Ting; Wang, Yue; Li, Ming-Xia

2018-01-01

An IPO burst occurred in China's stock markets in 2015, while price limit trading rules usually help to reduce the short-term trading mania on individual stocks. It is interesting to make clear the function of the price limits after IPOs. We firstly make a statistical analysis based on all the IPO stocks listed from 1990 to 2015. A high dependency exists between the activities in stock's IPO and various market environment. We also focus on the price dynamics in the first 40 trading days after the stock listed. We find that price limit system will delay the price movement, especially for the up-trend movements, which may lead to longer continuous price limit hits. Similar to our previous work, many results such as ;W; shape can be also observed in the future daily return after the price limit open. At last, we find most IPO measures show evident correlations with the following price limit hits. IPO stocks with lower first-day turnover and earning per share will be followed with a longer continuous price limit hits and lower future daily return under the newest trading rules, which give us a good way to estimate the occurrence of price limit hits and the following price dynamics. Our analysis provides a better understanding of the price dynamics after IPO events and offers potential practical values for investors.

Performance limits of ICA-based heart rate identification techniques in imaging photoplethysmography

International Nuclear Information System (INIS)

Mannapperuma, Kavan; Holton, Benjamin D; Lesniewski, Peter J; Thomas, John C

2015-01-01

Imaging photoplethysmography is a relatively new technique for extracting biometric information from video images of faces. This is useful in non-invasive monitoring of patients including neonates or the aged, with respect to sudden infant death syndrome, sleep apnoea, pulmonary disease, physical or mental stress and other cardio-vascular conditions. In this paper, we investigate the limits of detection of the heart rate (HR) while reducing the video quality. We compare the performance of three independent component analysis (ICA) methods (JADE, FastICA, RADICAL), autocorrelation with signal conditioning techniques and identify the most robust approach. We discuss sources of increasing error and other limiting conditions in three situations of reduced signal-to-noise ratio: one where the area of the analyzed face is decreased from 100 to 5%, another where the face area is progressively re-sampled down to a single RGB pixel and one where the HR signal is severely reduced with respect to the boundary noise. In most cases, the cardiac pulse rate can be reliably and accurately detected from videos containing only 5% facial area or from a face occupying just 4 pixels or containing only 5% of the facial HR modulation. (paper)

Physical Performance and Serum 25(OH)vitamin D Status in Community Dwelling Old Mobility Limited Adults: A Cross-Sectional Study.

Science.gov (United States)

von Berens, Å; Cederholm, T; Fielding, R A; Gustafsson, T; Kirn, D; Laussen, J; Nydahl, M; Travison, T G; Reid, K; Koochek, A

2018-01-01

To examine the potential association between serum 25(OH) vitamin D and the performance on the Short Physical Performance Battery (SPPB) including the sub-components; five repeated chair stands test, 4 meters walk test and balance in older mobility-limited community-dwelling men and women. A cross sectional study was performed in American and Swedish subjects who were examined for potential participation in a combined exercise and nutrition intervention trial. Logistic regression analysis and linear regression analyses were performed to evaluate the association for 25(OH)D with the overall score on the SBBP, chair stand, gait speed and balance. Community-dwelling (mean age 77.6 ± 5.3 years) mobility limited American (n=494) and Swedish (n=116) females (59%) and males. The SPPB (0-12 points) includes chair stand (s), gait speed (m/s) and a balance test. Mobility limitation i.e., SPPB score ≤ 9 was an inclusion criterion. A blood sample was obtained to measure serum 25(OH)vitamin D concentrations. No clear association of 25(OH)D with SPPB scores was detected either when 25(OH)D was assessed as a continuous variable or when categorized according to serum concentrations of <50, 50-75 or <75 nmol/L. However, when analyzing the relationship between 25(OH)D and seconds to perform the chair stands, a significant quadratic relationship was observed. Thus, at serum levels of 25(OH)D above 74 nmol/L, higher concentrations appeared to be advantageous for the chair stand test, whereas for serum levels below 74 nmol/L this association was not observed. This cross- sectional study lacked clear association between serum 25(OH)D and physical performance in mobility limited adults. A potentially interesting observation was that at higher serum levels of 25(OH)D a better performance on the chair stand test was indicated.

Performance limitations of polymer electrolytes based on ethylene oxide polymers

International Nuclear Information System (INIS)

Buriez, Olivier; Han, Yong Bong; Hou, Jun; Kerr, John B.; Qiao, Jun; Sloop, Steven E.; Tian, Minmin; Wang, Shanger

1999-01-01

Studies of polymer electrolyte solutions for lithium-polymer batteries are described. Two different salts, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium trifluoromethanesulfonate (LiTf), were dissolved in a variety of polymers. The structures were all based upon the ethylene oxide unit for lithium ion solvation and both linear and comb-branch polymer architectures have been examined. Conductivity, salt diffusion coefficient and transference number measurements demonstrate the superior transport properties of the LiTFSI salt over LiTf. Data obtained on all of these polymers combined with LiTFSI salts suggest that there is a limit to the conductivity achievable at room temperature, at least for hosts containing ethylene oxide units. The apparent conductivity limit is 5 x 10-5 S/cm at 25 C. Providing that the polymer chain segment containing the ethylene oxide units is at least 5-6 units long there appears to be little influence of the polymer framework to which the solvating groups are attached. To provide adequate separator function, the mechanical properties may be disconnected from the transport properties by selection of an appropriate architecture combined with an adequately long ethylene oxide chain. For both bulk and interfacial transport of the lithium ions, conductivity data alone is insufficient to understand the processes that occur. Lithium ion transference numbers and salt diffusion coefficients also play a major role in the observed behavior and the transport properties of these polymer electrolyte solutions appear to be quite inadequate for ambient temperature performance. At present, this restricts the use of such systems to high temperature applications. Several suggestions are given to overcome these obstacles

Elucidating the Performance Limitations of Lithium-ion Batteries due to Species and Charge Transport through Five Characteristic Parameters

Science.gov (United States)

Jiang, Fangming; Peng, Peng

2016-01-01

Underutilization due to performance limitations imposed by species and charge transports is one of the key issues that persist with various lithium-ion batteries. To elucidate the relevant mechanisms, two groups of characteristic parameters were proposed. The first group contains three characteristic time parameters, namely: (1) te, which characterizes the Li-ion transport rate in the electrolyte phase, (2) ts, characterizing the lithium diffusion rate in the solid active materials, and (3) tc, describing the local Li-ion depletion rate in electrolyte phase at the electrolyte/electrode interface due to electrochemical reactions. The second group contains two electric resistance parameters: Re and Rs, which represent respectively, the equivalent ionic transport resistance and the effective electronic transport resistance in the electrode. Electrochemical modeling and simulations to the discharge process of LiCoO2 cells reveal that: (1) if te, ts and tc are on the same order of magnitude, the species transports may not cause any performance limitations to the battery; (2) the underlying mechanisms of performance limitations due to thick electrode, high-rate operation, and large-sized active material particles as well as effects of charge transports are revealed. The findings may be used as quantitative guidelines in the development and design of more advanced Li-ion batteries. PMID:27599870

Missing depth cues in virtual reality limit performance and quality of three dimensional reaching movements.

Science.gov (United States)

Gerig, Nicolas; Mayo, Johnathan; Baur, Kilian; Wittmann, Frieder; Riener, Robert; Wolf, Peter

2018-01-01

Goal-directed reaching for real-world objects by humans is enabled through visual depth cues. In virtual environments, the number and quality of available visual depth cues is limited, which may affect reaching performance and quality of reaching movements. We assessed three-dimensional reaching movements in five experimental groups each with ten healthy volunteers. Three groups used a two-dimensional computer screen and two groups used a head-mounted display. The first screen group received the typically recreated visual depth cues, such as aerial and linear perspective, occlusion, shadows, and texture gradients. The second screen group received an abstract minimal rendering lacking those. The third screen group received the cues of the first screen group and absolute depth cues enabled by retinal image size of a known object, which realized with visual renderings of the handheld device and a ghost handheld at the target location. The two head-mounted display groups received the same virtually recreated visual depth cues as the second or the third screen group respectively. Additionally, they could rely on stereopsis and motion parallax due to head-movements. All groups using the screen performed significantly worse than both groups using the head-mounted display in terms of completion time normalized by the straight-line distance to the target. Both groups using the head-mounted display achieved the optimal minimum in number of speed peaks and in hand path ratio, indicating that our subjects performed natural movements when using a head-mounted display. Virtually recreated visual depth cues had a minor impact on reaching performance. Only the screen group with rendered handhelds could outperform the other screen groups. Thus, if reaching performance in virtual environments is in the main scope of a study, we suggest applying a head-mounted display. Otherwise, when two-dimensional screens are used, achievable performance is likely limited by the reduced depth

Auger generation as an intrinsic limit to tunneling field-effect transistor performance

International Nuclear Information System (INIS)

Teherani, James T.; Agarwal, Sapan; Chern, Winston; Antoniadis, Dimitri A.; Solomon, Paul M.; Yablonovitch, Eli

2016-01-01

Many in the microelectronics field view tunneling field-effect transistors (TFETs) as society's best hope for achieving a >10× power reduction for electronic devices; however, despite a decade of considerable worldwide research, experimental TFET results have significantly underperformed simulations and conventional MOSFETs. To explain the discrepancy between TFET experiments and simulations, we investigate the parasitic leakage current due to Auger generation, an intrinsic mechanism that cannot be mitigated with improved material quality or better device processing. We expose the intrinsic link between the Auger and band-to-band tunneling rates, highlighting the difficulty of increasing one without the other. From this link, we show that Auger generation imposes a fundamental limit on ultimate TFET performance.

Auger generation as an intrinsic limit to tunneling field-effect transistor performance

Energy Technology Data Exchange (ETDEWEB)

Teherani, James T., E-mail: j.teherani@columbia.edu [Department of Electrical Engineering, Columbia University, New York, New York 10027 (United States); Agarwal, Sapan [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States); Chern, Winston; Antoniadis, Dimitri A. [Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Solomon, Paul M. [IBM T.J. Watson Research Center, Yorktown Heights, New York 10598 (United States); Yablonovitch, Eli [Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720 (United States)

2016-08-28

Many in the microelectronics field view tunneling field-effect transistors (TFETs) as society's best hope for achieving a >10× power reduction for electronic devices; however, despite a decade of considerable worldwide research, experimental TFET results have significantly underperformed simulations and conventional MOSFETs. To explain the discrepancy between TFET experiments and simulations, we investigate the parasitic leakage current due to Auger generation, an intrinsic mechanism that cannot be mitigated with improved material quality or better device processing. We expose the intrinsic link between the Auger and band-to-band tunneling rates, highlighting the difficulty of increasing one without the other. From this link, we show that Auger generation imposes a fundamental limit on ultimate TFET performance.

Flight mechanics and control of escape manoeuvres in hummingbirds. II. Aerodynamic force production, flight control and performance limitations.

Science.gov (United States)

Cheng, Bo; Tobalske, Bret W; Powers, Donald R; Hedrick, Tyson L; Wang, Yi; Wethington, Susan M; Chiu, George T-C; Deng, Xinyan

2016-11-15

The superior manoeuvrability of hummingbirds emerges from complex interactions of specialized neural and physiological processes with the unique flight dynamics of flapping wings. Escape manoeuvring is an ecologically relevant, natural behaviour of hummingbirds, from which we can gain understanding into the functional limits of vertebrate locomotor capacity. Here, we extend our kinematic analysis of escape manoeuvres from a companion paper to assess two potential limiting factors of the manoeuvring performance of hummingbirds: (1) muscle mechanical power output and (2) delays in the neural sensing and control system. We focused on the magnificent hummingbird (Eugenes fulgens, 7.8 g) and the black-chinned hummingbird (Archilochus alexandri, 3.1 g), which represent large and small species, respectively. We first estimated the aerodynamic forces, moments and the mechanical power of escape manoeuvres using measured wing kinematics. Comparing active-manoeuvring and passive-damping aerodynamic moments, we found that pitch dynamics were lightly damped and dominated by the effect of inertia, while roll dynamics were highly damped. To achieve observed closed-loop performance, pitch manoeuvres required faster sensorimotor transduction, as hummingbirds can only tolerate half the delay allowed in roll manoeuvres. Accordingly, our results suggested that pitch control may require a more sophisticated control strategy, such as those based on prediction. For the magnificent hummingbird, we estimated that escape manoeuvres required muscle mass-specific power 4.5 times that during hovering. Therefore, in addition to the limitation imposed by sensorimotor delays, muscle power could also limit the performance of escape manoeuvres. © 2016. Published by The Company of Biologists Ltd.

Modeling and Validation of Performance Limitations for the Optimal Design of Interferometric and Intensity-Modulated Fiber Optic Displacement Sensors

Energy Technology Data Exchange (ETDEWEB)

Moro, Erik A. [Los Alamos National Laboratory

2012-06-07

-modulated interferometric sensor depends on an appropriate performance function (e.g., desired displacement range, accuracy, robustness, etc.). In this dissertation, the performance limitations of a bundled differential intensity-modulated displacement sensor are analyzed, where the bundling configuration has been designed to optimize performance. The performance limitations of a white light Fabry-Perot displacement sensor are also analyzed. Both these sensors are non-contacting, but they have access to different regions of the performance-space. Further, both these sensors have different degrees of sensitivity to experimental uncertainty. Made in conjunction with careful analysis, the decision of which sensor to deploy need not be an uninformed one.

High performance operational limits of tokamak and helical systems

International Nuclear Information System (INIS)

Yamazaki, Kozo; Kikuchi, Mitsuru

2003-01-01

The plasma operational boundaries of tokamak and helical systems are surveyed and compared with each other. Global confinement scaling laws are similar and gyro-Bohm like, however, local transport process is different due to sawtooth oscillations in tokamaks and ripple transport loss in helical systems. As for stability limits, achievable tokamak beta is explained by ideal or resistive MHD theories. On the other hand, beta values obtained so far in helical system are beyond ideal Mercier mode limits. Density limits in tokamak are often related to the coupling between radiation collapse and disruptive MHD instabilities, but the slow radiation collapse is dominant in the helical system. The pulse length of both tokamak and helical systems is on the order of hours in small machines, and the longer-pulsed good-confinement plasma operations compatible with radiative divertors are anticipated in both systems in the future. (author)

The impact of power limitations and adjacent residence interference on the performance of WLANs for home networking applications

OpenAIRE

Armour, SMD; Doufexi, A; Lee, BS; Nix, AR; Bull, DR

2001-01-01

This paper considers the application of 5 GHz wireless LAN technology to home networking applications. An assessment of physical layer performance is presented for both the IEEE 802.11a and HIPERLAN/2 standards in the form of achievable data rate as a function of received signal to noise ratio. The transmit power limitations imposed by the relevant regulatory bodies are presented and the implications of transmit power amplifier limitations considered. Based on this information, a state of the...

Performance analysis of 2D asynchronous hard-limiting optical code-division multiple access system through atmospheric scattering channel

Science.gov (United States)

Zhao, Yaqin; Zhong, Xin; Wu, Di; Zhang, Ye; Ren, Guanghui; Wu, Zhilu

2013-09-01

Optical code-division multiple access (OCDMA) systems usually allocate orthogonal or quasi-orthogonal codes to the active users. When transmitting through atmospheric scattering channel, the coding pulses are broadened and the orthogonality of the codes is worsened. In truly asynchronous case, namely both the chips and the bits are asynchronous among each active user, the pulse broadening affects the system performance a lot. In this paper, we evaluate the performance of a 2D asynchronous hard-limiting wireless OCDMA system through atmospheric scattering channel. The probability density function of multiple access interference in truly asynchronous case is given. The bit error rate decreases as the ratio of the chip period to the root mean square delay spread increases and the channel limits the bit rate to different levels when the chip period varies.

Between Action and Act: On the 9-N in Catalonia’s and the Limits of Performativity

Directory of Open Access Journals (Sweden)

Begonya Sáez Tajafuerce

2017-07-01

Full Text Available By referring to Michel Foucault’s and Jacques Lacan’s works, and also taking as reference the popular consultation which took place in Cataluña on november 9th 2014, the purpose of this article is to draw the limits of Judith Butler’s theory of performativity with respect to the subject of the political and its agency. Those limits are made manifest by the distinction between political action and act or between subversion, understood as a transgression of the norm which gives place to the reconfiguration of the socio-symbolic order, and interruption, understood as a transgression of the norm which constitutes an event of a radically different order.

Assessing control of postural stability in community-living older adults using performance-based limits of stability

Directory of Open Access Journals (Sweden)

Boissy Patrick

2008-03-01

Full Text Available Abstract Background Balance disability measurements routinely used to identify fall risks in frail populations have limited value in the early detection of postural stability deficits in community-living older adults. The objectives of the study were to 1 measure performance-based limits of stability (LOS in community-living older adults and compare them to theoretical LOS computed from data proposed by the Balance Master® system, 2 explore the feasibility of a new measurement approach based on the assessment of postural stability during weight-shifting tasks at performance-based LOS, 3 quantify intra-session performance variability during multiple trials using the performance-based LOS paradigm. Methods Twenty-four healthy community-living older adults (10 men, 14 women aged between 62 to 85 (mean age ± sd, 71.5 ± 6 yrs participated in the study. Subjects' performance-based LOS were established by asking them to transfer their body weight as far as possible in three directions (forward, right and left without changing their base of support. LOS were computed as the maximal excursion of the COP in each direction among three trials. Participants then performed two experimental tasks that consisted in controlling, with the assistance of visual feedback, their centre of pressure (COP within two predefined targets set at 100% of their performance-based LOS. For each tasks 8 trials were performed. Ground reaction forces and torques during performance-based LOS evaluation and experimental tasks were recorded with a force plate. Sway area and medio-lateral mean COP displacement speed variables were extracted from force plate recordings. Results Significant differences between theoretical LOS computed from maximum leaning angles derived from anthropometric characteristics and performance-based LOS were observed. Results showed that a motor learning effect was present as the participants optimized their weight-shifting strategy through the first three

The performance and limitations of FPGA-based digital servos for atomic, molecular, and optical physics experiments.

Science.gov (United States)

Yu, Shi Jing; Fajeau, Emma; Liu, Lin Qiao; Jones, David J; Madison, Kirk W

2018-02-01

In this work, we address the advantages, limitations, and technical subtleties of employing field programmable gate array (FPGA)-based digital servos for high-bandwidth feedback control of lasers in atomic, molecular, and optical physics experiments. Specifically, we provide the results of benchmark performance tests in experimental setups including noise, bandwidth, and dynamic range for two digital servos built with low and mid-range priced FPGA development platforms. The digital servo results are compared to results obtained from a commercially available state-of-the-art analog servo using the same plant for control (intensity stabilization). The digital servos have feedback bandwidths of 2.5 MHz, limited by the total signal latency, and we demonstrate improvements beyond the transfer function offered by the analog servo including a three-pole filter and a two-pole filter with phase compensation to suppress resonances. We also discuss limitations of our FPGA-servo implementation and general considerations when designing and using digital servos.

The performance and limitations of FPGA-based digital servos for atomic, molecular, and optical physics experiments

Science.gov (United States)

Yu, Shi Jing; Fajeau, Emma; Liu, Lin Qiao; Jones, David J.; Madison, Kirk W.

2018-02-01

In this work, we address the advantages, limitations, and technical subtleties of employing field programmable gate array (FPGA)-based digital servos for high-bandwidth feedback control of lasers in atomic, molecular, and optical physics experiments. Specifically, we provide the results of benchmark performance tests in experimental setups including noise, bandwidth, and dynamic range for two digital servos built with low and mid-range priced FPGA development platforms. The digital servo results are compared to results obtained from a commercially available state-of-the-art analog servo using the same plant for control (intensity stabilization). The digital servos have feedback bandwidths of 2.5 MHz, limited by the total signal latency, and we demonstrate improvements beyond the transfer function offered by the analog servo including a three-pole filter and a two-pole filter with phase compensation to suppress resonances. We also discuss limitations of our FPGA-servo implementation and general considerations when designing and using digital servos.

Limitation for performance of jobs in power unit control room of nuclear power plant

International Nuclear Information System (INIS)

Janas, D.

1988-01-01

The procedure is described for an analysis of the somatic and mental health condition of operating personnel in the unit control room of a nuclear power plant. It was divided into three stages, viz.: (1) determination of adverse and favorable effects of work; (2) the recording of social, psychological, physiological and biochemical changes in the personnel; (3) determination of possibilities of controlling the limit for performance of a job. The analysis showed that the problem is complex and should permanently remain in the centre of attention. (J.B.). 3 refs

Performance evaluation of five Mediterranean species to optimize ecosystem services of green roofs under water-limited conditions.

Science.gov (United States)

Azeñas, V; Janner, I; Medrano, H; Gulías, J

2018-04-15

Rapid urban growth in Mediterranean cities has become a serious environmental concern. Due to this expansion, which covers adjacent horizontal ground, a critical deficit of green areas has been increasing. Moreover, irrigation is considered an important issue since water is one of the most limiting natural resources all over the world. The main objective of this study was to perform a long-term experiment to assess five Mediterranean species for extensive green roof implementation in Mediterranean-climate conditions. Brachypodium phoenicoides, Crithmum maritimum, Limonium virgatum, Sedum sediforme and Sporobolus pungens were grown in experimental modules under well-watered and water-limited conditions (irrigation at 50% and 25% ET 0 , respectively). Plant growth and cover, relative appearance, color evolution and water use were determined periodically for two years. Shoot and root biomass were quantified at the end of the experimental period. The effects of the irrigation treatments and seasonal changes were assessed to identify the advantages and disadvantages of each species according to their environmental performance. All species survived and showed adequate esthetic performance and plant cover during the experiment. S. sediforme registered the lowest variation of relative appearance along the experiment, the highest biomass production and the lowest water consumption. Nevertheless, B. phoenicoides appeared to be an interesting alternative to S. sediforme, showing high esthetic performance and water consumption throughout the rainy season, suggesting a potential role of this species in stormwater regulation related with runoff reduction. S. pungens performed well in summer but presented poor esthetics during winter. Copyright © 2018 Elsevier Ltd. All rights reserved.

Performance of the MACRO limited streamer tubes for estimates of muon energy

CERN Document Server

Giorgini, M

2002-01-01

The MACRO limited streamer tubes can be operated in drift mode by using the TDCs included in the QTP system. In this way a considerable improvement in the space resolution is obtained, allowing the analysis of muon tracks in terms of multiple scattering effects and the energy estimates of muons crossing the detector. We present the results of two dedicated tests, performed with the CERN PS-T9 and SPS-X7 beams, to provide a full check of the electronics and to exploit the feasibility of the analysis. Using a neural network, we are able to estimate the muon energies up to E/sub mu / approximately = 40 GeV. The test beam data provide then an absolute energy calibration, which allows to apply the method to the MACRO data. (5 refs).

Prediction of Mobility Limitations after Hospitalization in Older Medical Patients by Simple Measures of Physical Performance Obtained at Admission to the Emergency Department

DEFF Research Database (Denmark)

Bodilsen, Ann Christine; Hedegaard Klausen, Henrik; Petersen, Janne

2016-01-01

Objective: Mobility limitations relate to dependency in older adults. Identification of older patients with mobility limitations after hospital discharge may help stratify treatment and could potentially counteract dependency seen in older adults after hospitalization. We investigated the ability...... of four physical performance measures administered at hospital admission to identify older medical patients who manifest mobility limitations 30 days after discharge. Design: Prospective cohort study of patients (≥65 years) admitted to the emergency department for acute medical illness. During the first...... included. Of those, 128 (40%) patients had mobility limitations at follow-up. Univariate analyzes showed that each of the physical performance measures was strongly associated with mobility limitations at follow-up (handgrip strength(women), OR 0.86 (0.81–0.91), handgrip strength(men), OR 0.90 (0...

Machine learning approaches to evaluate correlation patterns in allosteric signaling: A case study of the PDZ2 domain

Science.gov (United States)

Botlani, Mohsen; Siddiqui, Ahnaf; Varma, Sameer

2018-06-01

Many proteins are regulated by dynamic allostery wherein regulator-induced changes in structure are comparable with thermal fluctuations. Consequently, understanding their mechanisms requires assessment of relationships between and within conformational ensembles of different states. Here we show how machine learning based approaches can be used to simplify this high-dimensional data mining task and also obtain mechanistic insight. In particular, we use these approaches to investigate two fundamental questions in dynamic allostery. First, how do regulators modify inter-site correlations in conformational fluctuations (Cij)? Second, how are regulator-induced shifts in conformational ensembles at two different sites in a protein related to each other? We address these questions in the context of the human protein tyrosine phosphatase 1E's PDZ2 domain, which is a model protein for studying dynamic allostery. We use molecular dynamics to generate conformational ensembles of the PDZ2 domain in both the regulator-bound and regulator-free states. The employed protocol reproduces methyl deuterium order parameters from NMR. Results from unsupervised clustering of Cij combined with flow analyses of weighted graphs of Cij show that regulator binding significantly alters the global signaling network in the protein; however, not by altering the spatial arrangement of strongly interacting amino acid clusters but by modifying the connectivity between clusters. Additionally, we find that regulator-induced shifts in conformational ensembles, which we evaluate by repartitioning ensembles using supervised learning, are, in fact, correlated. This correlation Δij is less extensive compared to Cij, but in contrast to Cij, Δij depends inversely on the distance from the regulator binding site. Assuming that Δij is an indicator of the transduction of the regulatory signal leads to the conclusion that the regulatory signal weakens with distance from the regulatory site. Overall, this

Parameter design and performance simulation of a 10 kV voltage compensation type active superconducting fault current limiter

International Nuclear Information System (INIS)

Chen, L.; Tang, Y.J.; Song, M.; Shi, J.; Ren, L.

2013-01-01

Highlights: •For a practical 10 kV system, the 10 kV active SFCL’s basic parameters are designed. •Under different fault conditions, the 10 kV active SFCL’s performances are simulated. •The designed 10 kV active SFCL’s engineering feasibility is discussed preliminarily. -- Abstract: Since the introduction of superconducting fault current limiter (SFCL) into electrical distribution system may be a good choice with economy and practicability, the parameter design and current-limiting characteristics of a 10 kV voltage compensation type active SFCL are studied in this paper. Firstly, the SFCL’s circuit structure and operation principle are presented. Then, taking a practical 10 kV distribution system as its application object, the SFCL’s basic parameters are designed to meet the system requirements. Further, using MATLAB, the detailed current-limiting performances of the 10 kV active SFCL are simulated under different fault conditions. The simulation results show that the active SFCL can deal well with the faults, and the parameter design’s suitability can be testified. At the end, in view of the engineering feasibility of the 10 kV active SFCL, some preliminary discussions are carried out

Protein Assembly and Building Blocks: Beyond the Limits of the LEGO Brick Metaphor.

Science.gov (United States)

Levy, Yaakov

2017-09-26

Proteins, like other biomolecules, have a modular and hierarchical structure. Various building blocks are used to construct proteins of high structural complexity and diverse functionality. In multidomain proteins, for example, domains are fused to each other in different combinations to achieve different functions. Although the LEGO brick metaphor is justified as a means of simplifying the complexity of three-dimensional protein structures, several fundamental properties (such as allostery or the induced-fit mechanism) make deviation from it necessary to respect the plasticity, softness, and cross-talk that are essential to protein function. In this work, we illustrate recently reported protein behavior in multidomain proteins that deviates from the LEGO brick analogy. While earlier studies showed that a protein domain is often unaffected by being fused to another domain or becomes more stable following the formation of a new interface between the tethered domains, destabilization due to tethering has been reported for several systems. We illustrate that tethering may sometimes result in a multidomain protein behaving as "less than the sum of its parts". We survey these cases for which structure additivity does not guarantee thermodynamic additivity. Protein destabilization due to fusion to other domains may be linked in some cases to biological function and should be taken into account when designing large assemblies.

Limitations in intense exercise performance of athletes - effect of speed endurance training on ion handling and fatigue development

DEFF Research Database (Denmark)

Hostrup, Morten; Bangsbo, Jens

2017-01-01

Mechanisms underlying fatigue development and limitations for performance during intense exercise have been intensively studied during the past couple of decades. Fatigue development may involve several interacting factors and depends on type of exercise undertaken and training level of the indiv...

Peaking for optimal performance: Research limitations and future directions.

Science.gov (United States)

Pyne, David B; Mujika, Iñigo; Reilly, Thomas

2009-02-01

A key element of the physical preparation of athletes is the taper period in the weeks immediately preceding competition. Existing research has defined the taper, identified various forms used in contemporary sport, and examined the prescription of training volume, load, intensity, duration, and type (progressive or step). Current limitations include: the lack of studies on team, combative, racquet, and precision (target) sports; the relatively small number of randomized controlled trials; the narrow focus on a single competition (single peak) compared with multiple peaking for weekly, multi-day or multiple events; and limited understanding of the physiological, neuromuscular, and biomechanical basis of the taper. Future research should address these limitations, together with the influence of prior training on optimal tapering strategies, and the interactions between the taper and long-haul travel, heat, and altitude. Practitioners seek information on how to prescribe tapers from season to season during an athlete's career, or a team's progression through a domestic league season, or multi-year Olympic or World Cup cycle. Practical guidelines for planning effective tapers for the Vancouver 2010 and London 2012 Olympics will evolve from both experimental investigations and modelling of successful tapers currently employed in a wide range of sports.

Nanocomposites of graphene oxide and upconversion rare-earth nanocrystals with superior optical limiting performance

KAUST Repository

Wei, Wei

2012-04-20

Upconversion rare-earth nanomaterials (URENs) possess highly efficient near-infrared (NIR), e.g., 980 nm, laser absorption and unique energy upconversion capabilities. On the other hand, graphene and its derivatives, such as graphene oxide (GO), show excellent performance in optical limiting (OL); however, the wavelengths of currently used lasers for OL studies mainly focus on either 532 or 1064 nm. To design new-generation OL materials working at other optical regions, such as the NIR, a novel nanocomposites, GO-URENs, which combines the advantages of both its components, is synthesized by a one-step chemical reaction. Transmission electron microscopy, X-ray diffraction, infrared spectroscopy, and fluorescence studies prove that the α-phase URENs uniformly attach on the GO surface via covalent chemical bonding, which assures highly efficient energy transfer between URENs and GO, and also accounts for the significantly improved OL performance compared to either GO or URENs. The superior OL effect is also observed in the proof-of-concept thin-film product, suggesting immediate applications in making high-performance laser-protecting products and optoelectronic devices. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Upgrading the Performance of Cholesteric Liquid Crystal Lasers: Improvement Margins and Limitations

Directory of Open Access Journals (Sweden)

Josu Ortega

2017-12-01

Full Text Available The topic of cholesteric-liquid-crystal lasers is a rapidly expanding research area in the field of soft-matter photonics. The increasing interest in this field is due to the high versatility that these lasers may possibly present and the prospects of giving rise to new miniaturized devices. However, further improvements in their operation capabilities are still required for potential applications. In this paper, we critically analyze the main strategies proposed up to now to optimize their performance. We show theoretically and experimentally that possible innovations in the device structure cannot produce lasers with threshold energies below a certain limit. This limit is determined by the light scattering and absorption losses inside the liquid crystal. Even assuming the case of samples free of defects and perfectly non-absorbing, an intrinsic light scattering, typical of mesogens, still remains. Numerical estimates of the thresholds indicate that these lasers could hardly be driven by compact light sources such as current electroluminescent or light-emitting diodes. Since the improvement possibilities regarding cell architecture seem to be exhausted, the advance must come from the use of new dye molecules. These molecules should show enhanced emission cross-sections and be efficiently integrable within the mesogenic solvent. In addition, the fluorescent systems must present very small quantum yields to triplet states if continuous-wave lasing is sought. In this respect, quantum dots are an alternative to explore for further investigations.

Beta-limiting MHD Instabilities in Improved-performance NSTX Spherical Torus Plasmas

International Nuclear Information System (INIS)

J.E. Menard; M.G. Bell; R.E. Bell; E.D. Fredrickson D.A. Gates: S.M. Kaye; B.P. LeBlanc; R. Maingi; D. Mueller; S.A. Sabbagh; D. Stutman; C.E. Bush; D.W. Johnson; R. Kaita; H.W. Kugel; R.J. Maqueda; F. Paoletti; S.F Paul; M. Ono; Y.-K.M. Peng; C.H. Skinner; E.J. Synakowski; the NSTX Research Team

2003-01-01

Global magnetohydrodynamic stability limits in the National Spherical Torus Experiment (NSTX) have increased significantly recently due to a combination of device and operational improvements. First, more routine H-mode operation with broadened pressure profiles allows access to higher normalized beta and lower internal inductance. Second, the correction of a poloidal field coil induced error-field has largely eliminated locked tearing modes during normal operation and increased the maximum achievable beta. As a result of these improvements, peak beta values have reached (not simultaneously) β t = 35%, β N = 6.4, N > = 4.5, β N /l i = 10, and β P = 1.4. High β P operation with reduced tearing activity has allowed a doubling of discharge pulse-length to just over 1 second with sustained periods of β N ∼ 6 above the ideal no-wall limit and near the with-wall limit. Details of the β limit scalings and β-limiting instabilities in various operating regimes are described

Evaluation of impact limiter performance during end-on and slapdown drop tests of a one-third scale model storage/transport cask system

International Nuclear Information System (INIS)

Yoshimura, H.R.; Bronowski, D.R.; Uncapher, W.L.; Attaway, S.W.; Bateman, V.I.; Carne, T.G.; Gregory, D.L.; Huerta, M.

1990-12-01

This report describes drop testing of a one-third scale model shipping cask system. Two casks were designed and fabricated by Transnuclear, Inc., to ship spent fuel from the former Nuclear Fuel Services West Valley reprocessing facility in New York to the Idaho National Engineering Laboratory for a long-term spent fuel dry storage demonstration project. As part of the NRC's regulatory certification process, one-third scale model tests were performed to obtain experimental data on impact limiter performance during impact testing. The objectives of the testing program were to (1) obtain deceleration and displacement information for the cask and impact limiter system, (2) obtain dynamic force-displacement data for the impact limiters, (3) verify the integrity of the impact limiter retention system, and (4) examine the crush behavior of the limiters. Two 30-ft (9-m) drop tests were conducted on a mass model of the cask body and scaled balsa and redwood-filled impact limiters. This report describes the results of both tests in terms of measured decelerations, posttest deformation measurements, and the general structural response of the system. 3 refs., 32 figs

Performance Limitations Analysis of Imperfect Attenuators for Adaptive Self-Interference Cancellation System

Directory of Open Access Journals (Sweden)

J. Liu

2016-09-01

Full Text Available Radio frequency (RF adaptive self-interference cancellation system (RFAICS is extensively used to suppress the self-interference of radios operating in the same platform, such as military command vehicles, airplanes and navy vessels. RFAICS is generally consisted of couplers, attenuators, delay units, amplifiers, and filters and so on. However, RFAICS usually suffers severely from the imperfect attenuators. This paper firstly explores the RFAICS operation process in theory, and then thoroughly investigates and analyzes the negative effects of non-ideal attenuators on performance of RFAICS. The closed-form expressions fully describing the influences of attenuation bias and response-time respectively on the interference cancellation ratio (ICR and system convergence time (SCT are developed with this aim. Simulations are provided for the validity of the limitation analysis and obtained expressions. Results of simulations are in agreement with theoretical analysis, which is significant for component configuration in taking RFAICS into practice.

Adaptive Transmitter Optimization in Multiuser Multiantenna Systems: Theoretical Limits, Effect of Delays, and Performance Enhancements

Directory of Open Access Journals (Sweden)

Samardzija Dragan

2005-01-01

Full Text Available The advances in programmable and reconfigurable radios have rendered feasible transmitter optimization schemes that can greatly improve the performance of multiple-antenna multiuser systems. Reconfigurable radio platforms are particularly suitable for implementation of transmitter optimization at the base station. We consider the downlink of a wireless system with multiple transmit antennas at the base station and a number of mobile terminals (i.e., users each with a single receive antenna. Under an average transmit power constraint, we consider the maximum achievable sum data rates in the case of (1 zero-forcing (ZF spatial prefilter, (2 modified zero-forcing (MZF spatial prefilter, and (3 triangularization spatial prefilter coupled with dirty-paper coding (DPC transmission scheme. We show that the triangularization with DPC approaches the closed-loop MIMO rates (upper bound for higher SNRs. Further, the MZF solution performs very well for lower SNRs, while for higher SNRs, the rates for the ZF solution converge to the MZF rates. An important impediment that degrades the performance of such transmitter optimization schemes is the delay in channel state information (CSI. We characterize the fundamental limits of performance in the presence of delayed CSI and then propose performance enhancements using a linear MMSE predictor of the CSI that can be used in conjunction with transmitter optimization in multiple-antenna multiuser systems.

Fulltext PDF

Indian Academy of Sciences (India)

2012-01-30

Jan 30, 2012 ... the other hand, allostery may explicitly refer to the theory .... the consequence of the binding of small second messengers or, .... Scientific Publishing Company) ... Griffiths P E and Gray R D (eds) 2001 Cycles of contingency:.

Second advanced ICFA beam dynamics workshop on aperture-related limitations of the performance and beam lifetime in storage rings

International Nuclear Information System (INIS)

Hagel, J.; Keil, E.

1988-01-01

These proceedings contain the papers presented at the 'Second advanced beam dynamics workshop on aperture-related limitations of the performance and beam lifetime in storage rings', which was organized in Lugano, Switzerland, from 11 to 16 April 1988, by the Beam Dynamics Panel of the International Committee for Future Accelerators (ICFA). The papers cover experiments on existing accelerators, analytical methods for determining amplitude limitations, criteria for the properties of the circulating beam and for the quality of accelerator components, and compensation schemes for field defects. (orig.)

Performance Limits of Communication with Energy Harvesting

KAUST Repository

Znaidi, Mohamed Ridha

2016-01-01

In energy harvesting communications, the transmitters have to adapt transmission to the availability of energy harvested during communication. The performance of the transmission depends on the channel conditions which vary randomly due to mobility

Protein flexibility in the light of structural alphabets. \

Czech Academy of Sciences Publication Activity Database

Craveur, P.; Joseph, A,P.; Esque, J.; Narwani, T.J.; Noël, F.; Shinada, N.; Goguet, M.; Leonard, S.; Poulain, P.; Bertrand, O.; Faure, G.; Rebehmed, J.; Ghozlane, A.; Swapna, L.S.; Bhaskara, R.M.; Barnoud, J.; Téletchéa, S.; Jallu, V.; Černý, Jiří; Schneider, Bohdan; Etchebest, C.; Srinivasan, N.; Gelly, J.-Ch.; deBrevern, A.G.

2015-01-01

Roč. 2, 27 May 2015 (2015) ISSN 2296-889X R&D Projects: GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:86652036 Keywords : allostery * protein complexes * protein folding Subject RIV: EB - Genetics ; Molecular Biology

Binding-competent states for L-arginine in E. coli arginine repressor apoprotein

Czech Academy of Sciences Publication Activity Database

Pandey, Saurabh Kumar; Řeha, David; Zayats, Vasilina; Melicherčík, Milan; Carey, J.; Ettrich, Rüdiger

2014-01-01

Roč. 20, č. 7 (2014), s. 2330 ISSN 1610-2940 Institutional support: RVO:67179843 Keywords : allostery * ArgRC * conformational dynamics * principal components analysis * salt bridges * temporal evolution of conformers Subject RIV: CE - Biochemistry Impact factor: 1.736, year: 2014

25 CFR 12.55 - Are there any limits on how much force an officer can use when performing law enforcement duties?

Science.gov (United States)

2010-04-01

... 25 Indians 1 2010-04-01 2010-04-01 false Are there any limits on how much force an officer can use when performing law enforcement duties? 12.55 Section 12.55 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR LAW AND ORDER INDIAN COUNTRY LAW ENFORCEMENT Conduct § 12.55 Are there any limits on how much force an officer can use when...

Explore the performance limit of a solar PV – thermochemical power generation system

International Nuclear Information System (INIS)

Li, Wenjia; Hao, Yong

2017-01-01

Highlights: •Theoretical net solar-to-electric efficiency of 51.5% is attainable. •Design of efficient PVT systems is governed by at least 5 key considerations. •Concentration ratio has the most pronounced influence on PVT system efficiency. •Efficient PV, low emissivity and high concentration deliver the best performance. -- Abstract: Performance limit of a solar hybrid power generation system integrating efficient photovoltaic (PV) cells and methanol thermal (T) decomposition is explored from a thermodynamic perspective within the capability of state-of-the-art technologies. This type of PVT system features potentially high “net solar-to-electric efficiency” in general, primarily resulting from a key difference in the design of the thermal part compared with conventional PVT systems, i.e. replacing heat engines by a thermochemical power generation module for thermal energy utilization. Key design parameters of the system, including PV cell type, emissivity, solar concentration ratio and solar concentrator type, are individually studied. A system combining all such optimized aspects is projected to achieve net solar-to-electric efficiencies up to 51.5%, after taking all major (e.g. optical, radiative) losses into consideration. This study reveals important insights and enriches understanding on design principles of efficient PVT systems aimed at comprehensive and effective utilization of solar energy.

Non-Foster Circuits for High Performance Antennas: Advantages and Practical Limitations

Science.gov (United States)

Jacob, Minu Mariam

The demand for miniaturized, broadband communication systems has created a need for electrically small, broadband antennas. However, all passive electrically small antennas have a fundamental gain-bandwidth limitation related to their electrical size, as first described by Wheeler and Chu. This limitation can be overcome using active non-Foster circuits (negative inductors and/or negative capacitors), which can deliver a broadband input match with active matching techniques, or can help reduce phase dispersion using negative delay effects. This thesis will illustrate the advantages of non-Foster circuits in obtaining broadband small antennas, in addition to examining their practical limitations due to noise in receive applications, and nonlinearity in transmit applications.

A systematic review of the sleep, sleepiness, and performance implications of limited wake shift work schedules.

Science.gov (United States)

Short, Michelle A; Agostini, Alexandra; Lushington, Kurt; Dorrian, Jillian

2015-09-01

The aim of this review was to identify which limited wake shift work schedules (LWSW) best promote sleep, alertness, and performance. LWSW are fixed work/rest cycles where the time-at-work does is ≤8 hours and there is >1 rest period per day, on average, for ≥2 consecutive days. These schedules are commonly used in safety-critical industries such as transport and maritime industries. Literature was sourced using PubMed, Embase, PsycInfo, Scopus, and Google Scholar databases. We identified 20 independent studies (plus a further 2 overlapping studies), including 5 laboratory and 17 field-based studies focused on maritime watch keepers, ship bridge officers, and long-haul train drivers. The measurement of outcome measures was varied, incorporating subjective and objective measures of sleep: sleep diaries (N=5), actigraphy (N=4), and polysomnography, (N=3); sleepiness: Karolinska Sleepiness Scale (N=5), visual analog scale (VAS) alertness (N=2) and author-derived measures (N=2); and performance: Psychomotor Vigilance Test (PVT) (N=5), Reaction Time or Vigilance tasks (N=4), Vector and Letter Cancellation Test (N=1), and subjective performance (N=2). Of the three primary rosters examined (6 hours-on/6 hours-off, 8 hours-on/8 hours-off and 4 hours-on/8 hours-off), the 4 hours-on/8 hours-off roster was associated with better sleep and lower levels of sleepiness. Individuals working 4 hours-on/8 hours-off rosters averaged 1 hour more sleep per night than those working 6 hours-on/6 hours-off and 1.3 hours more sleep than those working 8 hours-on/8 hours-off (Pwork, (ii) more frequent rest breaks, (iii) shifts that start and end at the same clock time every 24 hours, and (iv) work shifts commencing in the daytime (as opposed to night). The findings for performance remain incomplete due to the small number of studies containing a performance measure and the heterogeneity of performance measures within those that did. The literature supports the utility of LWSW in

Above- and belowground competition from longleaf pine plantations limits performance of reintroduced herbaceous species.

Energy Technology Data Exchange (ETDEWEB)

T.B. Harrington; C.M. Dagley; M.B. Edwards.

2003-10-01

Although overstory trees limit the abundance and species richness of herbaceous vegetation in longleaf pine (Pinus palustris Mill.) plantations, the responsible mechanisms are poorly understood because of confounding among limiting factors. In fall 1998, research was initiated to determine the separate effects of above- and belowground competition and needlefall from overstory pines on understory plant performance. Three 13- to 15-yr-old plantations near Aiken, SC, were thinned to 0, 25, 50, or 100% of nonthinned basal area (19.5 m2 ha-1). Combinations of trenching (to eliminate root competition) and needlefall were applied to areas within each plot, and containerized seedlings of 14 perennial herbaceous species and longleaf pine were planted within each. Overstory crown closure ranged from 0 to 81%, and soil water and available nitrogen varied consistently with pine stocking, trenching, or their combination. Cover of planted species decreased an average of 16.5 and 14.1% as a result of above- and below-ground competition, respectively. Depending on species, needlefall effects were positive, negative, or negligible. Results indicate that understory restoration will be most successful when herbaceous species are established within canopy openings (0.1-0.2 ha) managed to minimize negative effects from above- and belowground competition and needlefall.

Sensitivity and uncertainty analyses applied to one-dimensional radionuclide transport in a layered fractured rock: Evaluation of the Limit State approach, Iterative Performance Assessment, Phase 2

International Nuclear Information System (INIS)

Wu, Y.T.; Gureghian, A.B.; Sagar, B.; Codell, R.B.

1992-12-01

The Limit State approach is based on partitioning the parameter space into two parts: one in which the performance measure is smaller than a chosen value (called the limit state), and the other in which it is larger. Through a Taylor expansion at a suitable point, the partitioning surface (called the limit state surface) is approximated as either a linear or quadratic function. The success and efficiency of the limit state method depends upon choosing an optimum point for the Taylor expansion. The point in the parameter space that has the highest probability of producing the value chosen as the limit state is optimal for expansion. When the parameter space is transformed into a standard Gaussian space, the optimal expansion point, known as the lost Probable Point (MPP), has the property that its location on the Limit State surface is closest to the origin. Additionally, the projections onto the parameter axes of the vector from the origin to the MPP are the sensitivity coefficients. Once the MPP is determined and the Limit State surface approximated, formulas (see Equations 4-7 and 4-8) are available for determining the probability of the performance measure being less than the limit state. By choosing a succession of limit states, the entire cumulative distribution of the performance measure can be detemined. Methods for determining the MPP and also for improving the estimate of the probability are discussed in this report

SLC kicker magnet limitations

International Nuclear Information System (INIS)

Cassel, R.; Donaldson, A.; Mattison, T.; Bowden, G.; Weaver, J.; Bulos, F.; Fiander, D.

1991-01-01

The SLC Damping Ring kicker magnets requires a fast magnetic field rise time of 58 nsec, a peak field of 800 gauss, a pulse amplitude stability of 0.01%, and a reasonable operational lifetime. The original kicker magnets designed by SLAC and at Fermi were not able to fulfill the SLC kicker requirements. Extensive studies were conducted to determine the limitation in the magnets, response of the ferrite in kicker magnet, and the modifications needed to improve the kicker magnet performance. The paper details the SLAC and Fermi kicker magnets limitation of performance

An evolution-based strategy for engineering allosteric regulation

Science.gov (United States)

Pincus, David; Resnekov, Orna; Reynolds, Kimberly A.

2017-04-01

Allosteric regulation provides a way to control protein activity at the time scale of milliseconds to seconds inside the cell. An ability to engineer synthetic allosteric systems would be of practical utility for the development of novel biosensors, creation of synthetic cell signaling pathways, and design of small molecule pharmaceuticals with regulatory impact. To this end, we outline a general approach—termed rational engineering of allostery at conserved hotspots (REACH)—to introduce novel regulation into a protein of interest by exploiting latent allostery that has been hard-wired by evolution into its structure. REACH entails the use of statistical coupling analysis (SCA) to identify ‘allosteric hotspots’ on protein surfaces, the development and implementation of experimental assays to test hotspots for functionality, and a toolkit of allosteric modulators to impinge on endogenous cellular circuitry. REACH can be broadly applied to rewire cellular processes to respond to novel inputs.

Summary of Dissolved Concentration Limits

International Nuclear Information System (INIS)

Yueting Chen

2001-01-01

According to the Technical Work Plan titled Technical Work Plan for Waste Form Degradation Process Model Report for SR (CRWMS M and O 2000a), the purpose of this study is to perform abstractions on solubility limits of radioactive elements based on the process-level information and thermodynamic databases provided by Natural Environment Program Operations (NEPO) and Waste Package Operations (WPO). The scope of this analysis is to produce solubility limits as functions, distributions, or constants for all transported radioactive elements identified by the Performance Assessment Operations (PAO) radioisotope screening. Results from an expert elicitation for solubility limits of most radioactive elements were used in the previous Total System Performance Assessments (TSPAs). However, the elicitation conducted in 1993 does not meet the criteria set forth by the U.S. Nuclear Regulatory Commission (NRC) due to lack of documentation and traceability (Kotra et al. 1996, Section 3). Therefore, at the Waste Form Abstraction Workshop held on February 2-4, 1999, at Albuquerque, New Mexico, the Yucca Mountain Site Characterization Project (YMP) decided to develop geochemical models to study solubility for the proposed Monitored Geologic Repository. WPO/NEPO is to develop process-level solubility models, including review and compilation of relevant thermodynamic data. PAO's responsibility is to perform abstractions based on the process models and chemical conditions and to produce solubility distributions or response surfaces applicable to the proposed repository. The results of this analysis and conceptual model will feed the performance assessment for Total System Performance Assessment--Site Recommendation (TSPA-SR) and Total System Performance Assessment--License Application (TSPA-LA), and to the Waste Form Degradation Process Model Report section on concentration limits

Summary of Dissolved Concentration Limits

Energy Technology Data Exchange (ETDEWEB)

Yueting Chen

2001-06-11

According to the Technical Work Plan titled Technical Work Plan for Waste Form Degradation Process Model Report for SR (CRWMS M&O 2000a), the purpose of this study is to perform abstractions on solubility limits of radioactive elements based on the process-level information and thermodynamic databases provided by Natural Environment Program Operations (NEPO) and Waste Package Operations (WPO). The scope of this analysis is to produce solubility limits as functions, distributions, or constants for all transported radioactive elements identified by the Performance Assessment Operations (PAO) radioisotope screening. Results from an expert elicitation for solubility limits of most radioactive elements were used in the previous Total System Performance Assessments (TSPAs). However, the elicitation conducted in 1993 does not meet the criteria set forth by the U.S. Nuclear Regulatory Commission (NRC) due to lack of documentation and traceability (Kotra et al. 1996, Section 3). Therefore, at the Waste Form Abstraction Workshop held on February 2-4, 1999, at Albuquerque, New Mexico, the Yucca Mountain Site Characterization Project (YMP) decided to develop geochemical models to study solubility for the proposed Monitored Geologic Repository. WPO/NEPO is to develop process-level solubility models, including review and compilation of relevant thermodynamic data. PAO's responsibility is to perform abstractions based on the process models and chemical conditions and to produce solubility distributions or response surfaces applicable to the proposed repository. The results of this analysis and conceptual model will feed the performance assessment for Total System Performance Assessment--Site Recommendation (TSPA-SR) and Total System Performance Assessment--License Application (TSPA-LA), and to the Waste Form Degradation Process Model Report section on concentration limits.

Benefits and limitations in the use of performance indicators

International Nuclear Information System (INIS)

Nobile, M.; Ceccantini, M.

1990-01-01

In the paper, some Caorso NPP performance indicators for 1982 through 1986 are shown according to the definition of the Institute of Nuclear Power Operations (INPO). The comparison of the Caorso NPP performance indicators with those of similar American plants stresses an analogous behaviour for all the indicators but two: (Industrial Safety Lost-Time Accident Rate and Diesel Generator Unavailability), for which there is a very significant difference. A subsequent analysis enhances, however, that this difference cannot be attributed to component performance or personnel management politics, but essentially to design choices and/or to peculiar social and economical context; if these factors are taken into consideration, the difference between the performance indicators of the Caorso plant and those of American plants is explained quite satisfactorily. This demonstrates, that even if the usefulness of the performance indicators is confirmed, a careful analysis of all the possible implications is necessary before reaching any final conclusion

An improved low-voltage ride-through performance of DFIG based wind plant using stator dynamic composite fault current limiter.

Science.gov (United States)

Gayen, P K; Chatterjee, D; Goswami, S K

2016-05-01

In this paper, an enhanced low-voltage ride-through (LVRT) performance of a grid connected doubly fed induction generator (DFIG) has been presented with the usage of stator dynamic composite fault current limiter (SDCFCL). This protection circuit comprises of a suitable series resistor-inductor combination and parallel bidirectional semiconductor switch. The SDCFCL facilitates double benefits such as reduction of rotor induced open circuit voltage due to increased value of stator total inductance and concurrent increase of rotor impedance. Both effects will limit rotor circuit over current and over voltage situation more secured way in comparison to the conventional scheme like the dynamic rotor current limiter (RCL) during any type of fault situation. The proposed concept is validated through the simulation study of the grid integrated 2.0MW DFIG. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Suggestions on performance of finite element limit analysis for eliminating the necessity of stress classifications in design and defect assessment

Energy Technology Data Exchange (ETDEWEB)

Fujioka, T. [Central Research Institute of Electric Power Industry, Tokyo (Japan)

2001-07-01

In structural design of a nuclear power component, stress classification from elastic stress analysis resultants is often used. Alternatively, to improve accuracy, finite element limit analysis may be performed. This paper examines some issues relating to the use of limit analysis; specifically, the treatment of multiple applied loads and the definition of the limit load from analysis using hardening plasticity laws. These are addressed both by detailed analysis for a simple geometry and by using the reference stress approach to estimate the inelastic displacement. The proposals are also applicable to a defect assessment of a cracked component, and treatment of distributed loads. It is shown that multiple or distributed loads should be treated as if they were applied proportionally irrespective of the actual nature of loads, and that the limit load from analysis with general plasticity laws may be estimated using a newly suggested reduced elastic slope method. (author)

Suggestions on performance of finite element limit analysis for eliminating the necessity of stress classifications in design and defect assessment

International Nuclear Information System (INIS)

Fujioka, T.

2001-01-01

In structural design of a nuclear power component, stress classification from elastic stress analysis resultants is often used. Alternatively, to improve accuracy, finite element limit analysis may be performed. This paper examines some issues relating to the use of limit analysis; specifically, the treatment of multiple applied loads and the definition of the limit load from analysis using hardening plasticity laws. These are addressed both by detailed analysis for a simple geometry and by using the reference stress approach to estimate the inelastic displacement. The proposals are also applicable to a defect assessment of a cracked component, and treatment of distributed loads. It is shown that multiple or distributed loads should be treated as if they were applied proportionally irrespective of the actual nature of loads, and that the limit load from analysis with general plasticity laws may be estimated using a newly suggested reduced elastic slope method. (author)

Interference and memory capacity limitations.

Science.gov (United States)

Endress, Ansgar D; Szabó, Szilárd

2017-10-01

Working memory (WM) is thought to have a fixed and limited capacity. However, the origins of these capacity limitations are debated, and generally attributed to active, attentional processes. Here, we show that the existence of interference among items in memory mathematically guarantees fixed and limited capacity limits under very general conditions, irrespective of any processing assumptions. Assuming that interference (a) increases with the number of interfering items and (b) brings memory performance to chance levels for large numbers of interfering items, capacity limits are a simple function of the relative influence of memorization and interference. In contrast, we show that time-based memory limitations do not lead to fixed memory capacity limitations that are independent of the timing properties of an experiment. We show that interference can mimic both slot-like and continuous resource-like memory limitations, suggesting that these types of memory performance might not be as different as commonly believed. We speculate that slot-like WM limitations might arise from crowding-like phenomena in memory when participants have to retrieve items. Further, based on earlier research on parallel attention and enumeration, we suggest that crowding-like phenomena might be a common reason for the 3 major cognitive capacity limitations. As suggested by Miller (1956) and Cowan (2001), these capacity limitations might arise because of a common reason, even though they likely rely on distinct processes. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Revisiting Pocos de Caldas. Application of the co-precipitation approach to establish realistic solubility limits for performance assessment

International Nuclear Information System (INIS)

Bruno, J.; Duro, L.; Jordana, S.; Cera, E.

1996-02-01

Solubility limits constitute a critical parameter for the determination of the mobility of radionuclides in the near field and the geosphere, and consequently for the performance assessment of nuclear waste repositories. Mounting evidence from natural system studies indicate that trace elements, and consequently radionuclides, are associated to the dynamic cycling of major geochemical components. We have recently developed a thermodynamic approach to take into consideration the co-precipitation and co-dissolution processes that mainly control this linkage. The approach has been tested in various natural system studies with encouraging results. The Pocos de Caldas natural analogue was one of the sites where a full testing of our predictive geochemical modelling capabilities were done during the analogue project. We have revisited the Pocos de Caldas data and expanded the trace element solubility calculations by considering the documented trace metal/major ion interactions. This has been done by using the co-precipitation/co-dissolution approach. The outcome is as follows: A satisfactory modelling of the behaviour of U, Zn and REEs is achieved by assuming co-precipitation with ferrihydrite. Strontium concentrations are apparently controlled by its co-dissolution from Sr-rich fluorites. From the performance assessment point of view, the present work indicates that calculated solubility limits using the co-precipitation approach are in close agreement with the actual trace element concentrations. Furthermore, the calculated radionuclide concentrations are 2-4 orders of magnitude lower than conservative solubility limits calculated by assuming equilibrium with individual trace element phases. 34 refs, 18 figs, 13 tabs

Revisiting Pocos de Caldas. Application of the co-precipitation approach to establish realistic solubility limits for performance assessment

Energy Technology Data Exchange (ETDEWEB)

Bruno, J.; Duro, L.; Jordana, S.; Cera, E. [QuantiSci, Barcelona (Spain)

1996-02-01

Solubility limits constitute a critical parameter for the determination of the mobility of radionuclides in the near field and the geosphere, and consequently for the performance assessment of nuclear waste repositories. Mounting evidence from natural system studies indicate that trace elements, and consequently radionuclides, are associated to the dynamic cycling of major geochemical components. We have recently developed a thermodynamic approach to take into consideration the co-precipitation and co-dissolution processes that mainly control this linkage. The approach has been tested in various natural system studies with encouraging results. The Pocos de Caldas natural analogue was one of the sites where a full testing of our predictive geochemical modelling capabilities were done during the analogue project. We have revisited the Pocos de Caldas data and expanded the trace element solubility calculations by considering the documented trace metal/major ion interactions. This has been done by using the co-precipitation/co-dissolution approach. The outcome is as follows: A satisfactory modelling of the behaviour of U, Zn and REEs is achieved by assuming co-precipitation with ferrihydrite. Strontium concentrations are apparently controlled by its co-dissolution from Sr-rich fluorites. From the performance assessment point of view, the present work indicates that calculated solubility limits using the co-precipitation approach are in close agreement with the actual trace element concentrations. Furthermore, the calculated radionuclide concentrations are 2-4 orders of magnitude lower than conservative solubility limits calculated by assuming equilibrium with individual trace element phases. 34 refs, 18 figs, 13 tabs.

Correlated motions are a fundamental property of β-sheets

Science.gov (United States)

Fenwick, R. Bryn; Orellana, Laura; Esteban-Martín, Santi; Orozco, Modesto; Salvatella, Xavier

2014-06-01

Correlated motions in proteins can mediate fundamental biochemical processes such as signal transduction and allostery. The mechanisms that underlie these processes remain largely unknown due mainly to limitations in their direct detection. Here, based on a detailed analysis of protein structures deposited in the protein data bank, as well as on state-of-the art molecular simulations, we provide general evidence for the transfer of structural information by correlated backbone motions, mediated by hydrogen bonds, across β-sheets. We also show that the observed local and long-range correlated motions are mediated by the collective motions of β-sheets and investigate their role in large-scale conformational changes. Correlated motions represent a fundamental property of β-sheets that contributes to protein function.

Beta-limiting MHD instabilities in improved performance NSTX spherical torus plasmas

International Nuclear Information System (INIS)

Menard, J.E.; Bell, M.G.; Bell, R.E.

2003-01-01

Global magnetohydrodynamic stability limits in the National Spherical Torus Experiment (NSTX) have increased significantly recently due to a combination of device and operational improvements. First, more routine H-mode operation with broadened pressure profiles allows access to higher normalized beta and lower internal inductance. Second, the correction of a poloidal field coil induced error-field has largely eliminated locked tearing modes during nor- mal operation and increased the maximum achievable beta. As a result of these improvements, peak beta values have reached (not simultaneously) β t = 35%, β N 6.5, N > = 4.5, β / l i =10, and β= 1.4. High β P operation with reduced tearing activity has allowed a doubling of discharge pulse-length to just over 1 second with sustained periods of β N ∼ 6. Details of the β limit scalings and β-limiting instabilities in various operating regimes are described. (author)

Discovery of Allostery in PKA Signaling.

Science.gov (United States)

Zhang, Ping; Kornev, Alexandr P; Wu, Jian; Taylor, Susan S

2015-06-01

cAMP-dependent protein kinase (PKA) was the second protein kinase to be discovered and the PKA catalytic (C) subunit serves as a prototype for the large protein kinase superfamily that contains over 500 gene products. The protein kinases regulate much of biology in eukaryotic cells and they are now also a major therapeutic target. Although PKA was discovered nearly 50 years ago and the subsequent discovery of the regulatory subunits that bind cAMP and release the catalytic activity from the holoenzyme followed quickly. Thus in PKA we see the convergence of two major signaling mechanisms - protein phosphorylation and second messenger signaling through cAMP. Crystallography provides a foundation for understanding function, and the structure of the isolated regulatory (R) and C-subunits have been extremely informative. Yet it is the R 2 C 2 holoenzyme that predominates in cells, and one can only appreciate the allosteric features of PKA signaling by seeing the full length protein. The symmetry and the quaternary constraints that one R:C hetero-dimer exerts on the other in the holoenzyme simply are not present in the isolated subunits or even in the R:C hetero-dimer.

Funnel plot control limits to identify poorly performing healthcare providers when there is uncertainty in the value of the benchmark.

Science.gov (United States)

Manktelow, Bradley N; Seaton, Sarah E; Evans, T Alun

2016-12-01

There is an increasing use of statistical methods, such as funnel plots, to identify poorly performing healthcare providers. Funnel plots comprise the construction of control limits around a benchmark and providers with outcomes falling outside the limits are investigated as potential outliers. The benchmark is usually estimated from observed data but uncertainty in this estimate is usually ignored when constructing control limits. In this paper, the use of funnel plots in the presence of uncertainty in the value of the benchmark is reviewed for outcomes from a Binomial distribution. Two methods to derive the control limits are shown: (i) prediction intervals; (ii) tolerance intervals Tolerance intervals formally include the uncertainty in the value of the benchmark while prediction intervals do not. The probability properties of 95% control limits derived using each method were investigated through hypothesised scenarios. Neither prediction intervals nor tolerance intervals produce funnel plot control limits that satisfy the nominal probability characteristics when there is uncertainty in the value of the benchmark. This is not necessarily to say that funnel plots have no role to play in healthcare, but that without the development of intervals satisfying the nominal probability characteristics they must be interpreted with care. © The Author(s) 2014.

Evaluation of limiting factors affecting photovoltaic performance of low-temperature-processed TiO₂ films in dye-sensitized solar cells.

Science.gov (United States)

Lee, Taek-Yong; Kim, Hui-Seon; Park, Nam-Gyu

2014-04-14

Limiting factors affecting photovoltaic performance of dye-sensitized solar cell employing low-temperature-processed TiO2 films were investigated. TiO2 films were prepared at a low temperature of 200 °C using the normal alcohol-containing binder-free TiO2 paste (LT200). Their photovoltaic performance was compared to a high-temperature (550 °C) annealed TiO2 film prepared using a polymer binder containing TiO2 paste (HT550). Compared to the proportional increase in conversion efficiency with TiO2 film thickness upto 14 μm for HT550, the increase in efficiency was terminated at relatively smaller thickness of about 8 μm for LT200 mainly due to unaugmented photocurrent. From the transient photocurrent-voltage studies, the electron transport rate was found to be almost identical, while charge recombination was one order of magnitude faster for LT200. Consequently, the electron diffusion length was more than 2-3 times shorter for LT200 than for HT550. Electron diffusion length and electron life time obtained from electrochemical impedance analysis were well consistent with those observed from transient measurement. Density of states (DOS) was evaluated to be shallow and narrow in LT200, which was responsible for limiting photovoltaic performance in the low-temperature processed TiO2 film. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Centralized motion control of a linear tooth belt drive: Analysis of the performance and limitations

Energy Technology Data Exchange (ETDEWEB)

Jokinen, M.

2010-07-01

A centralized robust position control for an electrical driven tooth belt drive is designed in this doctoral thesis. Both a cascaded control structure and a PID based position controller are discussed. The performance and the limitations of the system are analyzed and design principles for the mechanical structure and the control design are given. These design principles are also suitable for most of the motion control applications, where mechanical resonance frequencies and control loop delays are present. One of the major challenges in the design of a controller for machinery applications is that the values of the parameters in the system model (parameter uncertainty) or the system model it self (non-parametric uncertainty) are seldom known accurately in advance. In this thesis a systematic analysis of the parameter uncertainty of the linear tooth beltdrive model is presented and the effect of the variation of a single parameter on the performance of the total system is shown. The total variation of the model parameters is taken into account in the control design phase using a Quantitative Feedback Theory (QFT). The thesis also introduces a new method to analyze reference feedforward controllers applying the QFT. The performance of the designed controllers is verified by experimental measurements. The measurements confirm the control design principles that are given in this thesis. (orig.)

Non-site-specific allosteric effect of oxygen on human hemoglobin under high oxygen partial pressure.

Science.gov (United States)

Takayanagi, Masayoshi; Kurisaki, Ikuo; Nagaoka, Masataka

2014-04-08

Protein allostery is essential for vital activities. Allosteric regulation of human hemoglobin (HbA) with two quaternary states T and R has been a paradigm of allosteric structural regulation of proteins. It is widely accepted that oxygen molecules (O2) act as a "site-specific" homotropic effector, or the successive O2 binding to the heme brings about the quaternary regulation. However, here we show that the site-specific allosteric effect is not necessarily only a unique mechanism of O2 allostery. Our simulation results revealed that the solution environment of high O2 partial pressure enhances the quaternary change from T to R without binding to the heme, suggesting an additional "non-site-specific" allosteric effect of O2. The latter effect should play a complementary role in the quaternary change by affecting the intersubunit contacts. This analysis must become a milestone in comprehensive understanding of the allosteric regulation of HbA from the molecular point of view.

40 CFR 60.2215 - What else must I report if I have a deviation from the operating limits or the emission limitations?

Science.gov (United States)

2010-07-01

... performance test was conducted that deviated from any emission limitation. (b) The deviation report must be... deviation from the operating limits or the emission limitations? 60.2215 Section 60.2215 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) STANDARDS OF PERFORMANCE FOR...

40 CFR 60.2957 - What else must I report if I have a deviation from the operating limits or the emission limitations?

Science.gov (United States)

2010-07-01

..., or if a performance test was conducted that showed a deviation from any emission limitation. (b) The... deviation from the operating limits or the emission limitations? 60.2957 Section 60.2957 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) STANDARDS OF PERFORMANCE FOR...

Performance assessments of nuclear waste repositories--A dialogue on their value and limitations

Science.gov (United States)

Ewing, Rodney C.; Tierney, Martin S.; Konikow, Leonard F.; Rechard, Rob P.

1999-01-01

Performance Assessment (PA) is the use of mathematical models to simulate the long-term behavior of engineered and geologic barriers in a nuclear waste repository; methods of uncertainty analysis are used to assess effects of parametric and conceptual uncertainties associated with the model system upon the uncertainty in outcomes of the simulation. PA is required by the U.S. Environmental Protection Agency as part of its certification process for geologic repositories for nuclear waste. This paper is a dialogue to explore the value and limitations of PA. Two “skeptics” acknowledge the utility of PA in organizing the scientific investigations that are necessary for confident siting and licensing of a repository; however, they maintain that the PA process, at least as it is currently implemented, is an essentially unscientific process with shortcomings that may provide results of limited use in evaluating actual effects on public health and safety. Conceptual uncertainties in a PA analysis can be so great that results can be confidently applied only over short time ranges, the antithesis of the purpose behind long-term, geologic disposal. Two “proponents” of PA agree that performance assessment is unscientific, but only in the sense that PA is an engineering analysis that uses existing scientific knowledge to support public policy decisions, rather than an investigation intended to increase fundamental knowledge of nature; PA has different goals and constraints than a typical scientific study. The “proponents” describe an ideal, sixstep process for conducting generalized PA, here called probabilistic systems analysis (PSA); they note that virtually all scientific content of a PA is introduced during the model-building steps of a PSA, they contend that a PA based on simple but scientifically acceptable mathematical models can provide useful and objective input to regulatory decision makers. The value of the results of any PA must lie between these two

Limitations of Human Visual Working Memory

OpenAIRE

Wesenick, Maria-Barbara

2004-01-01

The present empirical study investigates limitations of human visual working memory (VWM). The experiments of the present work involve the experimental paradigm of change detection using simple geometrical objects in the form of rectangles of different colour, length, and orientation. It can be shown, that a limited performance in the temporary storage of visual information has multiple sources. Limitations of VWM can be attributed to a limited capacity or a limited duration, but also to limi...

Model for movement of molten limiter material during the ISX-B beryllium limiter experiment

International Nuclear Information System (INIS)

Langley, R.A.; England, A.C.; Edmonds, P.H.; Hogan, J.T.; Neilson, G.H.

1986-01-01

A model is proposed for the movement and erosion of limiter material during the Beryllium Limiter Experiment performed on the ISX-B Tokamak. This model is consistent with observed experimental results and plasma operational characteristics. Conclusions drawn from the model can provide an understanding of erosion mechanisms, thereby contributing to the development of future design criteria. (author)

Properties of magnetic photonic crystals in the visible spectral region and their performance limitations

Science.gov (United States)

Kotov, V. A.; Shavrov, V. G.; Vasiliev, M.; Alameh, K.; Nur-E-Alam, M.; Balabanov, D. E.

2018-02-01

We report on the results of computer modelling and performance analysis of the optical and magneto-optical (MO) characteristics of one-dimensional magnetic photonic crystals (MPC) of several classic design types (having either a single structure defect, or a number of these), designed for applications in the visible spectral region. The calculations are performed accounting for the real levels of optical absorption achievable in existing MO materials which currently demonstrate the best MO quality (bismuth-substituted ferrite garnets). We consider Bi2Dy1Fe4Ga1O12 as the base material for use within quarter-wave thick MO layers of MPC; silica is used for the non-magnetic transparent quarter-wave layers. The achieved results can be used to clarify the nature of the differences that exist between the expected practical potential of MPCs in integrated photonics, and the actual attained experimental results. Our results show that in MPCs optimized for light intensity modulation applications, in the red spectral region (near 650 nm), the achievable levels of optical transmission are limited to about 30%. This coincides spectrally with the peaks of Faraday rotation reaching their maxima at about 25°, with further transmission increases possible in the near-infrared region. Larger Faraday rotation angles are only achievable currently in structures or single film layers with reduced transmission.

Application of a modified flux-coupling type superconducting fault current limiter to transient performance enhancement of micro-grid

Energy Technology Data Exchange (ETDEWEB)

Chen, Lei, E-mail: stclchen1982@163.com [School of Electrical Engineering, Wuhan University, Wuhan 430072 (China); Zheng, Feng; Deng, Changhong; Li, Shichun; Li, Miao; Liu, Hui [School of Electrical Engineering, Wuhan University, Wuhan 430072 (China); Zhu, Lin [Department of Electrical Engineering and Computer Science, University of Tennessee, Knoxville 37996 (United States); Guo, Fang [Department of Substation, Guang Dong Electric Power Design Institute, Guangzhou 510663 (China)

2015-11-15

Highlights: • A modified flux-coupling type SFCL is suggested to enhance the transient performance of a micro-grid. • The SFCL’s main contribution is to improve the micro-grid’s fault ride-through capability. • The SFCL also can make the micro-grid carry out a smooth transition between its grid-connected and islanded modes. • The simulations show that the SFCL can availably strengthen the micro-grid’s voltage and frequency stability. - Abstract: Concerning the application and development of a micro-grid system which is designed to accommodate high penetration of intermittent renewable resources, one of the main issues is related to an increase in the fault-current level. It is crucial to ensure the micro-grid’s operational stability and service reliability when a fault occurs in the main network. In this paper, our research group suggests a modified flux-coupling type superconducting fault current limiter (SFCL) to enhance the transient performance of a typical micro-grid system. The SFCL is installed at the point of common coupling (PCC) between the main network and the micro-grid, and it is expected to actively improve the micro-grid’s fault ride-through capability. And for some specific faults, the micro-grid should disconnect from the main network, and the SFCL’s contribution is to make the micro-grid carry out a smooth transition between its grid-connected and islanded modes. Related theory derivation, technical discussion and simulation analysis are performed. From the demonstrated results, applying the SFCL can effectively limit the fault current, maintain the power balance, and enhance the voltage and frequency stability of the micro-grid.

Application of a modified flux-coupling type superconducting fault current limiter to transient performance enhancement of micro-grid

International Nuclear Information System (INIS)

Chen, Lei; Zheng, Feng; Deng, Changhong; Li, Shichun; Li, Miao; Liu, Hui; Zhu, Lin; Guo, Fang

2015-01-01

Highlights: • A modified flux-coupling type SFCL is suggested to enhance the transient performance of a micro-grid. • The SFCL’s main contribution is to improve the micro-grid’s fault ride-through capability. • The SFCL also can make the micro-grid carry out a smooth transition between its grid-connected and islanded modes. • The simulations show that the SFCL can availably strengthen the micro-grid’s voltage and frequency stability. - Abstract: Concerning the application and development of a micro-grid system which is designed to accommodate high penetration of intermittent renewable resources, one of the main issues is related to an increase in the fault-current level. It is crucial to ensure the micro-grid’s operational stability and service reliability when a fault occurs in the main network. In this paper, our research group suggests a modified flux-coupling type superconducting fault current limiter (SFCL) to enhance the transient performance of a typical micro-grid system. The SFCL is installed at the point of common coupling (PCC) between the main network and the micro-grid, and it is expected to actively improve the micro-grid’s fault ride-through capability. And for some specific faults, the micro-grid should disconnect from the main network, and the SFCL’s contribution is to make the micro-grid carry out a smooth transition between its grid-connected and islanded modes. Related theory derivation, technical discussion and simulation analysis are performed. From the demonstrated results, applying the SFCL can effectively limit the fault current, maintain the power balance, and enhance the voltage and frequency stability of the micro-grid.

Performance limitations of relay neurons.

Directory of Open Access Journals (Sweden)

Rahul Agarwal

Full Text Available Relay cells are prevalent throughout sensory systems and receive two types of inputs: driving and modulating. The driving input contains receptive field properties that must be transmitted while the modulating input alters the specifics of transmission. For example, the visual thalamus contains relay neurons that receive driving inputs from the retina that encode a visual image, and modulating inputs from reticular activating system and layer 6 of visual cortex that control what aspects of the image will be relayed back to visual cortex for perception. What gets relayed depends on several factors such as attentional demands and a subject's goals. In this paper, we analyze a biophysical based model of a relay cell and use systems theoretic tools to construct analytic bounds on how well the cell transmits a driving input as a function of the neuron's electrophysiological properties, the modulating input, and the driving signal parameters. We assume that the modulating input belongs to a class of sinusoidal signals and that the driving input is an irregular train of pulses with inter-pulse intervals obeying an exponential distribution. Our analysis applies to any [Formula: see text] order model as long as the neuron does not spike without a driving input pulse and exhibits a refractory period. Our bounds on relay reliability contain performance obtained through simulation of a second and third order model, and suggest, for instance, that if the frequency of the modulating input increases or the DC offset decreases, then relay increases. Our analysis also shows, for the first time, how the biophysical properties of the neuron (e.g. ion channel dynamics define the oscillatory patterns needed in the modulating input for appropriately timed relay of sensory information. In our discussion, we describe how our bounds predict experimentally observed neural activity in the basal ganglia in (i health, (ii in Parkinson's disease (PD, and (iii in PD during

Chemical shift imprint of intersubunit communication in a symmetric homodimer

Science.gov (United States)

Falk, Bradley T.; Sapienza, Paul J.; Lee, Andrew L.

2016-01-01

Allosteric communication is critical for protein function and cellular homeostasis, and it can be exploited as a strategy for drug design. However, unlike many protein–ligand interactions, the structural basis for the long-range communication that underlies allostery is not well understood. This lack of understanding is most evident in the case of classical allostery, in which a binding event in one protomer is sensed by a second symmetric protomer. A primary reason why study of interdomain signaling is challenging in oligomeric proteins is the difficulty in characterizing intermediate, singly bound species. Here, we use an NMR approach to isolate and characterize a singly ligated state (“lig1”) of a homodimeric enzyme that is otherwise obscured by rapid exchange with apo and saturated forms. Mixed labeled dimers were prepared that simultaneously permit full population of the lig1 state and isotopic labeling of either protomer. Direct visualization of peaks from lig1 yielded site-specific ligand-state multiplets that provide a convenient format for assessing mechanisms of intersubunit communication from a variety of NMR measurements. We demonstrate this approach on thymidylate synthase from Escherichia coli, a homodimeric enzyme known to be half-the-sites reactive. Resolving the dUMP1 state shows that active site communication occurs not upon the first dUMP binding, but upon the second. Surprisingly, for many sites, dUMP1 peaks are found beyond the limits set by apo and dUMP2 peaks, indicating that binding the first dUMP pushes the enzyme ensemble to further conformational extremes than the apo or saturated forms. The approach used here should be generally applicable to homodimers. PMID:27466406

Capacitor performance limitations in high power converter applications

DEFF Research Database (Denmark)

El-Khatib, Walid Ziad; Holbøll, Joachim; Rasmussen, Tonny Wederberg

2013-01-01

High voltage low inductance capacitors are used in converters as HVDC-links, snubber circuits and sub model (MMC) capacitances. They facilitate the possibility of large peak currents under high frequent or transient voltage applications. On the other hand, using capacitors with larger equivalent...... series inductances include the risk of transient overvoltages, with a negative effect on life time and reliability of the capacitors. These allowable limits of such current and voltage peaks are decided by the ability of the converter components, including the capacitors, to withstand them over...... the expected life time. In this paper results are described from investigations on the electrical environment of these capacitors, including all the conditions they would be exposed to, thereby trying to find the tradeoffs needed to find a suitable capacitor. Different types of capacitors with the same voltage...

RESURF power semiconductor devices - Performance and operating limits

NARCIS (Netherlands)

Ferrara, A.

2016-01-01

Power transmission is the transfer of energy from a generating source to a load which uses the energy to perform useful work. Since the end of the 19th century, electrical power transmission has replaced mechanical power transmission in all long distance applications. The alternating current (AC)

RESURF power semiconductor devices: performance and operating limits

NARCIS (Netherlands)

Ferrara, A.

2016-01-01

Power transmission is the transfer of energy from a generating source to a load which uses the energy to perform useful work. Since the end of the 19th century, electrical power transmission has replaced mechanical power transmission in all long distance applications. The alternating current (AC)

Influence of CFC quality on the performance of TS limiter elements under cyclic heat loading

International Nuclear Information System (INIS)

Missirlian, M.; Greuner, H.; Hoeschen, T.; Linsmeier, Ch.; Richou, M.; Lipa, M.; Boeswirth, B.; Boscary, J.

2011-01-01

For the fabrication of 600 actively cooled finger elements for the Tore Supra pump limiter in operation since 2001 it was necessary to rely on two different batches of the CFC N11 grade (Carbon Fibre reinforced Composite) namely so-called SEP N11-92 (fabricated in 1992) and N11-98 (fabricated in 1998). It came out during the incoming inspection of the fingers that the bonding quality was degraded for the 98-batch so that an important number of tiles had to be repaired. Due to the coming upgrade of the Tore Supra heating system, two high heat flux test campaigns were performed on the neutral beam GLADIS facility (IPP Garching, Germany) including micro-structural analyses in order to evaluate, compare and understand the fatigue behaviour of 92- and 98-batch finger elements.

Limiting Performance Analysis of Underwater Shock Isolation of a System with Biodynamic Response Using Genetic Algorithm

Directory of Open Access Journals (Sweden)

Z. Zong

2000-01-01

Full Text Available Biodynamic response of shipboard crew to underwater shock is of a major concern to navies. An underwater shock can produce very high accelerations, resulting in severe human injuries aboard a battleship. Protection of human bodies from underwater shock is implemented by installing onboard isolators. In this paper, the optimal underwater shock isolation to protect human bodies is studied. A simple shock-structure-isolator-human interaction model is first constructed. The model incorporates the effect of fluid-structure interaction, biodynamic response of human body, isolator influence. Based on this model, the optimum shock isolation is then formulated. The performance index and restriction are defined. Thirdly, GA (genetic algorithm is employed to solve the formulated optimization problem. GA is a powerful evolutionary optimization scheme suitable for large-scale and multi-variable optimization problems that are otherwise hard to be solved by conventional methods. A brief introduction to GA is given in the paper. Finally, the method is applied to an example problem and the limiting performance characteristic is obtained.

Breaking the speed limit--comparative sprinting performance of brook trout (Salvelinus fontinalis) and brown trout (Salmo trutta)

Science.gov (United States)

Castro-Santos, Theodore; Sanz-Ronda, Francisco Javier; Ruiz-Legazpi, Jorge

2013-01-01

Sprinting behavior of free-ranging fish has long been thought to exceed that of captive fish. Here we present data from wild-caught brook trout (Salvelinus fontinalis) and brown trout (Salmo trutta), volitionally entering and sprinting against high-velocity flows in an open-channel flume. Performance of the two species was nearly identical, with the species attaining absolute speeds > 25 body lengths·s−1. These speeds far exceed previously published observations for any salmonid species and contribute to the mounting evidence that commonly accepted estimates of swimming performance are low. Brook trout demonstrated two distinct modes in the relationship between swim speed and fatigue time, similar to the shift from prolonged to sprint mode described by other authors, but in this case occurring at speeds > 19 body lengths·s−1. This is the first demonstration of multiple modes of sprint swimming at such high swim speeds. Neither species optimized for distance maximization, however, indicating that physiological limits alone are poor predictors of swimming performance. By combining distributions of volitional swim speeds with endurance, we were able to account for >80% of the variation in distance traversed by both species.

Knock-Limited Performance of Triptane and 28-R Fuel Blends as Affected by Changes in Compression Ratio and in Engine Operating Variables

Science.gov (United States)

Brun, Rinaldo J.; Feder, Melvin S.; Fisher, William F.

1947-01-01

A knock-limited performance investigation was conducted on blends of triptane and 28-P fuel with a 12-cylinder, V-type, liquid-cooled aircraft engine of 1710-cubic-inch displacement at three compression ratios: 6.65, 7.93, and 9.68. At each compression ratio, the effect of changes in temperature of the inlet air to the auxiliary-stage supercharger and in fuel-air ratio were investigated at engine speeds of 2280 and. 3000 rpm. The results show that knock-limited engine performance, as improved by the use of triptane, allowed operation at both take-off and cruising power at a compression ratio of 9.68. At an inlet-air temperature of 60 deg F, an engine speed of 3000 rpm ; and a fuel-air ratio of 0,095 (approximately take-off conditions), a knock-limited engine output of 1500 brake horsepower was possible with 100-percent 28-R fuel at a compression ratio of 6.65; 20-percent triptane was required for the same power output at a compression ratio of 7.93, and 75 percent at a compression ratio of 9.68 allowed an output of 1480 brake horsepower. Knock-limited power output was more sensitive to changes in fuel-air ratio as the engine speed was increased from 2280 to 3000 rpm, as the compression ratio is raised from 6.65 to 9.68, or as the inlet-air temperature is raised from 0 deg to 120 deg F.

Limiting characteristics of the superconducting fault current limiter applied to the neutral line of conventional transformer

International Nuclear Information System (INIS)

Im, I.G.; Choi, H.S.; Jung, B.I.

2013-01-01

Highlights: •Fault current limiter was used a high-speed interrupter. •High-speed interrupter was operated to bypass to the current limiter line. •The size of the fault current was limited to about 80% after the fault occurred. •The fault current was limited quickly within a half-cycle after the fault occurred. -- Abstract: The increased electricity demands influenced by the recent industrial development make the electric power distribution system more comprehensive, and the risks are high to cause failures to steady state electric line due to the extended range of fault at the time of fault occurrence. Also, the high performance and the high precision electric appliances that sensitive to switching surge and fault current expose vulnerability of reduced life span and increased fault occurrence ratio. Therefore, this thesis analyzed the fault limiting characteristics by the fault types by applying the superconducting fault current limiter to the neutral line of the transformer in order to reduce the fault currents that flow such high performance appliances. A current transformer (CT) that detects the fault current in the simulated power distribution system, a switching control system that is self-developed and a transformer are used in constructing a circuit. When a fault occurs, the initial fault current is restricted by the superconducting fault current limiter and simultaneously detours the fault current by operating the SCR contact of the switching control system through the detection by CT. This thesis analyzed the limiting characteristics of the superconducting fault current limiter that are applied to the neutral line of the transformer by the fault types

Limiting characteristics of the superconducting fault current limiter applied to the neutral line of conventional transformer

Energy Technology Data Exchange (ETDEWEB)

Im, I.G., E-mail: asiligo@gmail.com; Choi, H.S., E-mail: hyosang@chosun.ac.kr; Jung, B.I.

2013-11-15

Highlights: •Fault current limiter was used a high-speed interrupter. •High-speed interrupter was operated to bypass to the current limiter line. •The size of the fault current was limited to about 80% after the fault occurred. •The fault current was limited quickly within a half-cycle after the fault occurred. -- Abstract: The increased electricity demands influenced by the recent industrial development make the electric power distribution system more comprehensive, and the risks are high to cause failures to steady state electric line due to the extended range of fault at the time of fault occurrence. Also, the high performance and the high precision electric appliances that sensitive to switching surge and fault current expose vulnerability of reduced life span and increased fault occurrence ratio. Therefore, this thesis analyzed the fault limiting characteristics by the fault types by applying the superconducting fault current limiter to the neutral line of the transformer in order to reduce the fault currents that flow such high performance appliances. A current transformer (CT) that detects the fault current in the simulated power distribution system, a switching control system that is self-developed and a transformer are used in constructing a circuit. When a fault occurs, the initial fault current is restricted by the superconducting fault current limiter and simultaneously detours the fault current by operating the SCR contact of the switching control system through the detection by CT. This thesis analyzed the limiting characteristics of the superconducting fault current limiter that are applied to the neutral line of the transformer by the fault types.

The Limits of Exercise Physiology

DEFF Research Database (Denmark)

Gabriel, Brendan M; Zierath, Juleen R

2017-01-01

Many of the established positive health benefits of exercise have been documented by historical discoveries in the field of exercise physiology. These investigations often assess limits: the limits of performance, or the limits of exercise-induced health benefits. Indeed, several key findings have...... been informed by studying highly trained athletes, in addition to healthy or unhealthy people. Recent progress has been made in regard to skeletal muscle metabolism and personalized exercise regimes. In this perspective, we review some of the historical milestones of exercise physiology, discuss how...

40 CFR 60.3052 - What else must I report if I have a deviation from the operating limits or the emission limitations?

Science.gov (United States)

2010-07-01

... control device was bypassed, or if a performance test was conducted that showed a deviation from any... deviation from the operating limits or the emission limitations? 60.3052 Section 60.3052 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) STANDARDS OF PERFORMANCE FOR...

ALPS - advanced limiter-divertor plasma-facing systems

International Nuclear Information System (INIS)

Allain, J. P.; Bastasz, R.; Brooks, J. N.; Evans, T.; Hassanein, A.; Luckhardt, S.; Maingi, R.; Mattas, R. F.; McCarthy, K.; Mioduszewski, P.; Mogahed, E.; Moir, R.; Molokov, S.; Morely, N.; Nygren, R.; Reed, C.; Rognlien, T.; Ruzic, D.; Sviatoslavsky, I.; Sze, D.; Tillack, M.; Ulrickson, M.; Wade, P. M.; Wong, C.; Wooley, R.

1999-01-01

The Advanced Limiter-divertor Plasma-facing Systems (ALPS) program was initiated in order to evaluate the potential for improved performance and lifetime for plasma-facing systems. The main goal of the program is to demonstrate the advantages of advanced limiter/divertor systems over conventional systems in terms of power density capability, component lifetime, and power conversion efficiency, while providing for safe operation and minimizing impurity concerns for the plasma. Most of the work to date has been applied to free surface liquids. A multi-disciplinary team from several institutions has been organized to address the key issues associated with these systems. The main performance goals for advanced limiters and diverters are a peak heat flux of >50 MW/m 2 ,elimination of a lifetime limit for erosion, and the ability to extract useful heat at high power conversion efficiency (approximately40%). The evaluation of various options is being conducted through a combination of laboratory experiments, modeling of key processes, and conceptual design studies. The current emphasis for the work is on the effects of free surface liquids on plasma edge performance

Journal of Biosciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Biosciences; Volume 42; Issue 1. What history tells us XLII. A 'new' view of proteins. MICHEL MORANGE. Series Volume 42 Issue 1 March 2017 pp 11-14. Fulltext. Click here to view fulltext PDF. Permanent link: https://www.ias.ac.in/article/fulltext/jbsc/042/01/0011-0014. Keywords. Allostery ...

Tokamak pump limiters

International Nuclear Information System (INIS)

Conn, R.W.; California Univ., Los Angeles

1984-01-01

Recent experiments with a scoop limiter without active internal pumping have been carried out in the PDX tokamak with up to 6 MW of auxiliary neutral beam heating. Experiments have also been performed with a rotating head pump limiter in the PLT tokamak in conjunction with RF plasma heating. Extensive experiments have been done in the ISX-B tokamak and first experiments have been completed with the ALT-I limiter in TEXTOR. The pump limiter modules in these latter two machines have internal getter pumping. Experiments in ISX-B are with ohmic and auxiliary neutral beam heating. The results in ISX-B and TEXTOR show that active density control and particle removal is achieved with pump limiters. In ISX-B, the boundary layer (or scrape-off layer) plasma partially screens the core plasma from gas injection. In both ISX-B and TEXTOR, the pressure internal to the module scales linearly with plasma density but in ISX-B, with neutral beam injection, a nonlinear increase is observed at the highest densities studied. Plasma plugging is the suspected cause. Results from PDX suggest that a regime may exist in which core plasma energy confinement improves using a pump limiter during neutral beam injection. Asymmetric radial profiles and an increased edge electron temperature are observed in discharges with improved confinement. The injection of small amounts of neon into ISX-B has more clearly shown an improved electron core energy confinement during neutral beam injection. While carried out with a regular limiter, this 'Z-mode' of operation is ideal for use with pump limiters and should be a way to achieve energy confinement times similar to values for H-mode tokamak plasmas. The implication of all these results for the design of a reactor pump limiter is described. (orig.)

Limited Investigation of the Effects of Elevator Rate Limiting and Stick Dynamics on Longitudinal Pilot Induced Oscillations (HAVE GRIP)

National Research Council Canada - National Science Library

Peters, Patrick

1996-01-01

This report presents the results of the HAVE GRIP flight test program. This program performed a limited investigation of the effects of stick dynamics and elevator rate limiting on longitudinal pilot induced oscillations (PIOs...

Development of stair-climbing mechanism with passive crawlers. Analysis of limitation for crawler rotation angle and test vehicle performance

International Nuclear Information System (INIS)

Hirasawa, Junji; Kimura, Tetsuya

2016-01-01

This paper describes a novel mechanism with passive crawlers that will realize a stair-climbing rescue robot with simple system. The proposed mechanism is called 'SMART-III', it is named after 'Simple Mechanism Adaptive for Rough Terrain'. Some quasi-static dynamic analysis were implemented and effectiveness of limitation for crawler rotation angle were verified. A prototype robot with the SMART-III mechanism had been improved. Experimental results show the effectiveness and performance of the proposed mechanism against a step and continuous stairs. (author)

To what extent might N2 limit dive performance in king penguins?

Science.gov (United States)

Fahlman, A; Schmidt, A; Jones, D R; Bostrom, B L; Handrich, Y

2007-10-01

A mathematical model was used to explore if elevated levels of N2, and risk of decompression sickness (DCS), could limit dive performance (duration and depth) in king penguins (Aptenodytes patagonicus). The model allowed prediction of blood and tissue (central circulation, muscle, brain and fat) N2 tensions (P(N2)) based on different cardiac outputs and blood flow distributions. Estimated mixed venous P(N2) agreed with values observed during forced dives in a compression chamber used to validate the assumptions of the model. During bouts of foraging dives, estimated mixed venous and tissue P(N2) increased as the bout progressed. Estimated mean maximum mixed venous P(N2) upon return to the surface after a dive was 4.56+/-0.18 atmospheres absolute (ATA; range: 4.37-4.78 ATA). This is equivalent to N2 levels causing a 50% DCS incidence in terrestrial animals of similar mass. Bout termination events were not associated with extreme mixed venous N2 levels. Fat P(N2) was positively correlated with bout duration and the highest estimated fat P(N2) occurred at the end of a dive bout. The model suggested that short and shallow dives occurring between dive bouts help to reduce supersaturation and thereby DCS risk. Furthermore, adipose tissue could also help reduce DCS risk during the first few dives in a bout by functioning as a sink to buffer extreme levels of N2.

Bipolar-power-transistor-based limiter for high frequency ultrasound imaging systems.

Science.gov (United States)

Choi, Hojong; Yang, Hao-Chung; Shung, K Kirk

2014-03-01

High performance limiters are described in this paper for applications in high frequency ultrasound imaging systems. Limiters protect the ultrasound receiver from the high voltage (HV) spikes produced by the transmitter. We present a new bipolar power transistor (BPT) configuration and compare its design and performance to a diode limiter used in traditional ultrasound research and one commercially available limiter. Limiter performance depends greatly on the insertion loss (IL), total harmonic distortion (THD) and response time (RT), each of which will be evaluated in all the limiters. The results indicated that, compared with commercial limiter, BPT-based limiter had less IL (-7.7 dB), THD (-74.6 dB) and lower RT (43 ns) at 100 MHz. To evaluate the capability of these limiters, they were connected to a 100 MHz single element transducer and a two-way pulse-echo test was performed. It was found that the -6 dB bandwidth and sensitivity of the transducer using BPT-based limiter were better than those of the commercial limiter by 22% and 140%, respectively. Compared to the commercial limiter, BPT-based limiter is shown to be capable of minimizing signal attenuation, RT and THD at high frequencies and is thus suited for high frequency ultrasound applications. Copyright © 2013 Elsevier B.V. All rights reserved.

TFCX pumped limiter and vacuum pumping system design and analysis

International Nuclear Information System (INIS)

Haines, J.R.

1985-04-01

Impurity control system design and performance studies were performed in support of the Tokamak Fusion Core Experiment (TFCX) pre-conceptual design. Efforts concentrated on pumped limiter and vacuum pumping system design configuration, thermal/mechanical and erosion lifetime performance of the limiter protective surface, and helium ash removal performance. The reference limiter design forms a continuous toroidal belt at the bottom of the device and features a flat surface with a single leading edge. The vacuum pumping system features large vacuum ducts (diameter approximately 1 m) and high-speed, compound cryopumps. Analysis results indicate that the limiter/vacuum pumping system design provides adequate helium ash removal. Erosion, primarily by disruption-induced vaporization and/or melting, limits the protective surface lifetime to about one calendar year or only about 60 full-power hours of operation. In addition to evaluating impurity control system performance for nominal TFCX conditions, these studies attempt to focus on the key plasma physics and engineering design issues that should be addressed in future research and development programs

Determination and Interpretation of Characteristic Limits for Radioactivity Measurements: Decision Threshhold, Detection Limit and Limits of the Confidence Interval

International Nuclear Information System (INIS)

2017-01-01

Since 2004, the environment programme of the IAEA has included activities aimed at developing a set of procedures for analytical measurements of radionuclides in food and the environment. Reliable, comparable and fit for purpose results are essential for any analytical measurement. Guidelines and national and international standards for laboratory practices to fulfil quality assurance requirements are extremely important when performing such measurements. The guidelines and standards should be comprehensive, clearly formulated and readily available to both the analyst and the customer. ISO 11929:2010 is the international standard on the determination of the characteristic limits (decision threshold, detection limit and limits of the confidence interval) for measuring ionizing radiation. For nuclear analytical laboratories involved in the measurement of radioactivity in food and the environment, robust determination of the characteristic limits of radioanalytical techniques is essential with regard to national and international regulations on permitted levels of radioactivity. However, characteristic limits defined in ISO 11929:2010 are complex, and the correct application of the standard in laboratories requires a full understanding of various concepts. This publication provides additional information to Member States in the understanding of the terminology, definitions and concepts in ISO 11929:2010, thus facilitating its implementation in Member State laboratories.

14 CFR 183.55 - Limitations.

Science.gov (United States)

2010-01-01

... REGULATIONS REPRESENTATIVES OF THE ADMINISTRATOR Organization Designation Authorization § 183.55 Limitations... structure), no Unit member may perform that function until the Administrator is notified of the change, and...

Biased limiter experiments on text

International Nuclear Information System (INIS)

Phillips, P.E.; Wootton, A.J.; Rowan, W.L.; Ritz, C.P.; Rhodes, T.L.; Bengtson, R.D.; Hodge, W.L.; Durst, R.D.; McCool, S.C.; Richards, B.; Gentle, K.W.; Schoch, P.; Forster, J.C.; Hickok, R.L.; Evans, T.E.

1987-01-01

Experiments using an electrically biased limiter have been performed on the Texas Experimental Tokamak (TEXT). A small movable limiter is inserted past the main poloidal ring limiter (which is electrically connected to the vacuum vessel) and biased at V Lim with respect to it. The floating potential, plasma potential and shear layer position can be controlled. With vertical strokeV Lim vertical stroke ≥ 50 V the plasma density increases. For V Lim Lim > 0 the results obtained are inconclusive. Variation of V Lim changes the electrostatic turbulence which may explain the observed total flux changes. (orig.)

Latent Factors Limiting the Performance of sEMG-Interfaces

Directory of Open Access Journals (Sweden)

Sergey Lobov

2018-04-01

Full Text Available Recent advances in recording and real-time analysis of surface electromyographic signals (sEMG have fostered the use of sEMG human–machine interfaces for controlling personal computers, prostheses of upper limbs, and exoskeletons among others. Despite a relatively high mean performance, sEMG-interfaces still exhibit strong variance in the fidelity of gesture recognition among different users. Here, we systematically study the latent factors determining the performance of sEMG-interfaces in synthetic tests and in an arcade game. We show that the degree of muscle cooperation and the amount of the body fatty tissue are the decisive factors in synthetic tests. Our data suggest that these factors can only be adjusted by long-term training, which promotes fine-tuning of low-level neural circuits driving the muscles. Short-term training has no effect on synthetic tests, but significantly increases the game scoring. This implies that it works at a higher decision-making level, not relevant for synthetic gestures. We propose a procedure that enables quantification of the gestures’ fidelity in a dynamic gaming environment. For each individual subject, the approach allows identifying “problematic” gestures that decrease gaming performance. This information can be used for optimizing the training strategy and for adapting the signal processing algorithms to individual users, which could be a way for a qualitative leap in the development of future sEMG-interfaces.

Summary of the half-day internal review of LHC performance limitations (linked to transverse collective effects) during run II (CERN, 29/11/2016)

CERN Document Server

Metral, Elias; Biancacci, Nicolo; Buffat, Xavier; Carver, Lee Robert; Iadarola, Giovanni; Li, Kevin Shing Bruce; Persson, Tobias Hakan Bjorn; Romano, Annalisa; Schenk, Michael; Tambasco, Claudia; CERN. Geneva. ATS Department

2017-01-01

In this note the half-day internal review of LHC performance limitations (linked to transverse collective effects) during run II (2015-2016), which took place at CERN on 29/11/2016 (https://indico.cern.ch/event/589625/), is summarised and the next steps are discussed.

Cell Signalling Through Covalent Modification and Allostery

Science.gov (United States)

Johnson, Louise N.

Phosphorylation plays essential roles in nearly every aspect of cell life. Protein kinases catalyze the transfer of the γ-phosphate of ATP to a serine, threonine or tyrosine residue in protein substrates. This covalent modification allows activation or inhibition of enzyme activity, creates recognition sites for other proteins and promotes order/disorder or disorder/order transitions. These properties regulate ­signalling pathways and cellular processes that mediate metabolism, transcription, cell cycle progression, differentiation, cytoskeleton arrangement and cell movement, apoptosis, intercellular communication, and neuronal and immunological functions. In this lecture I shall review the structural consequences of protein phosphorylation using our work on glycogen phosphorylase and the cell cycle cyclin dependent protein kinases as illustrations. Regulation of protein phosphorylation may be disrupted in the diseased state and protein kinases have become high profile targets for drug development. To date there are 11 compounds that have been approved for clinical use in the treatment of cancer.

Income trusts and limited partnerships

International Nuclear Information System (INIS)

Toews, E.L.

1999-01-01

This author provided a conceptual overview of income trusts and limited partnerships that are designed to pass operating cash flow directly to investors without the imposition of corporate taxes, discussed the evolution of the market, the mechanism used to price income funds, past and present performance of the sector, and made some predictions concerning the sector's future performance. 13 figs

A simplified technique for shakedown limit load determination

International Nuclear Information System (INIS)

Abdalla, Hany F.; Megahed, Mohammad M.; Younan, Maher Y.A.

2007-01-01

In this paper, a simplified technique is presented to determine the shakedown limit load of a structure using the finite element method. The simplified technique determines the shakedown limit load without performing lengthy time consuming full elastic-plastic cyclic loading simulations or conventional iterative elastic techniques. Instead, the shakedown limit load is determined by performing two analyses namely: an elastic analysis and an elastic-plastic analysis. By extracting the results of the two analyses, the shakedown limit load is determined through the calculation of the residual stresses developed within the structure. The simplified technique is applied and verified using two bench mark shakedown problems namely: the two-bar structure subjected to constant axial force and cyclic thermal loading, and the Bree cylinder subjected to constant internal pressure and cyclic high temperature variation across its wall. The results of the simplified technique showed very good correlation with the, analytically determined, Bree diagrams of both structures. In order to gain confidence in the simplified technique, the shakedown limit loads output by the simplified technique are used to perform full elastic-plastic cyclic loading simulations to check for shakedown behavior of both structures

Characterizing Mobility Limitations Among Older African American Men.

Science.gov (United States)

Mitchell, Jamie A; Johnson-Lawrence, Vicki; Williams, Ed-Dee G; Thorpe, Roland

2018-04-01

This study represents an effort to contribute to the limited body of research on biopsychosocial contextual factors that influence or contribute to mobility limitations for older African American men. Specifically, we were interested in examining associations between socio-demographic, physical and emotional health experiences with mobility limitations. A secondary analysis of 1666 older African American men was performed to investigate socio-demographic, mental and physical health correlates to a specific measures of mobility limitation. In the final model, difficulty with self-care, severe pain interference, and problems with usual activities were most strongly associated with mobility limitations. Men who were married were significantly less likely to experience mobility limitations. Findings highlighted the relationship between mobility limitations and difficulty performing activities of daily living. Additional research should examine the impact of poor emotional health and the buffering effects of marriage on mobility for older African American men, a population at high risk of experiencing disparate health outcomes. Copyright © 2018 National Medical Association. Published by Elsevier Inc. All rights reserved.

Influence of limit-feeding and time of day of feed availability to growing calves on growth performance and feeding behavior in cold weather.

Science.gov (United States)

Prezotto, L D; Gilbery, T C; Bauer, M L; Islas, A; Swanson, K C

2017-11-01

Objective swere to determine the effects of limit-feeding and time of feed access in cold weather on growth performance and feeding behavior of growing calves fed a corn silage-based diet. Sixty-six steers (BW = 317 ± 5.3 kg) and 30 heifers (BW = 239 ± 7.6 kg) were assigned randomly to dietary treatment: 1) ad libitum feed intake (AL), 2) limit-fed to 80% of the average DMI of the AL group on a BW basis in the daytime (0601-1759 h; LF-D), 3) limit-fed to 80% of the average DMI of the AL group on a BW basis in the nighttime (1800-0559 h; LF-N), and 4) limit-fed to 80% of the average DMI of the AL group on a BW basis, split 1/2 in the daytime and 1/2 in the nighttime (LF-S). Feed intake and feeding behavior were monitored over 84 d using the Insentec feeding system. Average daily gain, DMI, and G:F were greater ( ≤ 0.002) in the AL group compared with others. Dry matter intake was not different ( = 0.17) when comparing the LF-D with the LF-N groups. Average daily gain and G:F were greater ( ≤ 0.05) when comparing the LF-N group to the LF-D group, and were not different ( ≥ 0.51) when comparing the LF-S group with the mean of the LF-D and LF-N groups. Number of visits and meals per d was greater ( ≤ 0.001) in the LF-N than the LF-D group. Feed intake per visit was not different ( = 0.55) when comparing the AL group and others, and tended to be greater ( = 0.06) in the LF-D than the LF-N group. Feed intake per meal was greater ( Feed intake per minute (eating rate) was not influenced by treatment. In conclusion, limit-feeding at 80% of ad libitum intake decreased ADG and G:F. Limit-feeding in the nighttime as compared to limit-feeding in the daytime improves growth performance and increases feeding activity (number of visits and meals per d) which could be because of increased heat production to help maintain body temperature and thus reduce maintenance energy requirements.

Performance evaluation of multilevel modulation formats using partial response for capacity upgrade in access network with limited electronic bandwidth

DEFF Research Database (Denmark)

Madsen, Peter; Suhr, Lau Frejstrup; Rodríguez Páez, Juan Sebastián

2016-01-01

We present a successful experimental evaluation of 4 level Pulse Amplitude Modulation (4-PAM) and Duobinary modulation. An experimental performance evaluation is presented for Duobinary 4 PAM and other modulation formats. All modulation formants used, may be considered to be implemented in future...... Passive Optical Network (PON) class access networks with limited electrical bandwidth. We compared NRZ, Duobinary, 4-PAM and Duobinary 4-PAM operating at 9 Gbaud over 20 km single mode fiber. The results provides an insight and guidelines on the utilization of these advanced modulation formats....

Predicting Classifier Performance with Limited Training Data: Applications to Computer-Aided Diagnosis in Breast and Prostate Cancer

Science.gov (United States)

Basavanhally, Ajay; Viswanath, Satish; Madabhushi, Anant

2015-01-01

Clinical trials increasingly employ medical imaging data in conjunction with supervised classifiers, where the latter require large amounts of training data to accurately model the system. Yet, a classifier selected at the start of the trial based on smaller and more accessible datasets may yield inaccurate and unstable classification performance. In this paper, we aim to address two common concerns in classifier selection for clinical trials: (1) predicting expected classifier performance for large datasets based on error rates calculated from smaller datasets and (2) the selection of appropriate classifiers based on expected performance for larger datasets. We present a framework for comparative evaluation of classifiers using only limited amounts of training data by using random repeated sampling (RRS) in conjunction with a cross-validation sampling strategy. Extrapolated error rates are subsequently validated via comparison with leave-one-out cross-validation performed on a larger dataset. The ability to predict error rates as dataset size increases is demonstrated on both synthetic data as well as three different computational imaging tasks: detecting cancerous image regions in prostate histopathology, differentiating high and low grade cancer in breast histopathology, and detecting cancerous metavoxels in prostate magnetic resonance spectroscopy. For each task, the relationships between 3 distinct classifiers (k-nearest neighbor, naive Bayes, Support Vector Machine) are explored. Further quantitative evaluation in terms of interquartile range (IQR) suggests that our approach consistently yields error rates with lower variability (mean IQRs of 0.0070, 0.0127, and 0.0140) than a traditional RRS approach (mean IQRs of 0.0297, 0.0779, and 0.305) that does not employ cross-validation sampling for all three datasets. PMID:25993029

Growth Performance and Carcass Characteristics of Korean Native Ducks Fed Diets with Varying Levels of Limiting Amino Acids

Directory of Open Access Journals (Sweden)

Y. K. Choo

2014-04-01

Full Text Available There are multiple experiments conducted with male Korean native ducks (KND to evaluate the optimal levels of limiting amino acids (AA. In Exp. 1, a total of 450 one-d-old male KNDs were divided into five groups with six replicates and fed experimental diets with varying levels of lysine, total sulfur amino acids (TSAA and threonine (T1, 0.90/0.74/0.70%; T2, 1.00/0.82/0.77%; T3, 1.10/0.90/0.85%; T4, 1.20/0.98/0.93%; T5, 1.30/1.07/1.01% to 21 d of age. In Exp. 2, one-d-old male KND were received and fed commercial starter diet from hatching to 21 d of age, and then divided into five groups with six replicates and fed one of five diets varying levels of lysine, TSAA, and threonine (T1, 0.73/0.62/0.54%; T2, 0.80/0.68/0.60%; T3, 0.87/0.74/0.65%; T4, 0.94/0.80/0.70%; T5, 1.01/0.86/0.75% during 22 to 56 d of age, respectively. The BW gain was linearly increased as dietary limiting AA levels increased to 1.20% lysine, 0.98% TSAA and 0.93% threonine. There were no significant differences in feed intake, gain:feed and uniformity among groups. In Exp. 2, the BW gain and gain:feed were not affected by dietary limiting AA levels. There were no significant differences in carcass characteristics and meat quality among groups. The growth performance and carcass characteristics did not show the significant response to increasing dietary limiting AA levels in KND during 22 to 56 d of age. In conclusion, the levels of lysine, TSAA and threonine necessary to maximize growth for starter phase were at least 1.20%, 0.98%, and 0.93%, respectively. On the other hands, KND require relatively low levels of limiting AA for late growth and carcass yield. The dietary levels of 0.73% lysine, 0.62% TSAA and 0.54% threonine appear to be adequate during growing phase.

US ITER limiter module design

International Nuclear Information System (INIS)

Mattas, R.F.; Billone, M.; Hassanein, A.

1996-08-01

The recent U.S. effort on the ITER (International Thermonuclear Experimental Reactor) shield has been focused on the limiter module design. This is a multi-disciplinary effort that covers design layout, fabrication, thermal hydraulics, materials evaluation, thermo- mechanical response, and predicted response during off-normal events. The results of design analyses are presented. Conclusions and recommendations are also presented concerning, the capability of the limiter modules to meet performance goals and to be fabricated within design specifications using existing technology

Proposed limiting values for performance criteria in acceptance testing of diagnostic X-ray equipment in the Federal Republic of Germany

International Nuclear Information System (INIS)

Baeuml, A.

1989-01-01

In the Federal Republic of Germany a new X-ray ordinance came into force in 1988 containing a specific paragraph on quality assurance for all medical X-ray units stipulating acceptance tests, regular checks and supervision by medical bodies and the competent authorities. Acceptance testing is to be performed by engineers from equipment suppliers of manufacturers in new and existing installations. It is expected that the service engineers will adjust the equipment in such a way as to obtain optimal performance before measurements are made, the results of which are to be stated in a certificate describing quality status of the equipment. A working group has developed guidelines for these acceptance tests. Items to be measured are reported and proposed limiting values and their tolerances are discussed. (author)

Proposed limiting values for performance criteria in acceptance testing of diagnostic X-ray equipment in the Federal Republic of Germany

International Nuclear Information System (INIS)

Baeuml, A.

1989-01-01

In the Federal Republic of Germany a new X-ray ordinance came into force in 1988 containing a specific paragraph on quality assurance for all medical X-ray units stipulating acceptance tests, regular checks and supervision by medical bodies and the competent authorities. Acceptance testing is to be performed by engineers from the equipment suppliers or manufacturers in new and also existing installations. It is expected that the service engineers will adjust the equipment in such a way as to obtain optimal performance before measurements are made, the results of which are to be stated in a certificate describing the quality status of the equipment. A working group has developed guidelines for these acceptance tests. The items to be measured are reported and the proposed limiting values and their tolerances are discussed. (author)

At the limit of polychromatic microdiffraction

Energy Technology Data Exchange (ETDEWEB)

Ice, Gene E., E-mail: IceGE@ornl.gov [MST Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6118 (United States); Pang, Judy W.L.; Larson, Bennett C.; Budai, John D.; Tischler, Jonathan Z. [MST Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6118 (United States); Choi, Jae-Young [Pohang Accelerator Laboratory, Pohang (Korea, Republic of); Liu Wenjun; Liu Chian; Assoufid, Lahsen; Shu Deming; Khounsary, Ali [Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States)

2009-10-25

With a high-energy 3rd generation source like the Advanced Photon Source (APS), it is possible to push the performance of polychromatic microdiffraction far beyond current levels and to approach the intrinsic limit of the technique based on sample damage and the diffraction limit of X-rays. We describe ongoing efforts to improve the spatial, temporal and momentum transfer resolution of polychromatic microdiffraction on beamline 34-ID-E at the APS. The goal of this effort is to provide high-resolution images of 3D crystal structures over sufficient volumes and with sufficient detail to clarify the underlying physics of inhomogeneous structure and evolution on mesoscopic length scales. The performance of a high-speed amorphous Si area detector system and the ongoing development of advanced focusing optics will be described and discussed in light of the ultimate limits set by the physics of X-rays and materials, and in light of opportunities to field specialized insertion devices and optics for polychromatic microdiffraction.

Performance Limits of Communication with Energy Harvesting

KAUST Repository

Znaidi, Mohamed Ridha

2016-04-01

In energy harvesting communications, the transmitters have to adapt transmission to the availability of energy harvested during communication. The performance of the transmission depends on the channel conditions which vary randomly due to mobility and environmental changes. During this work, we consider the problem of power allocation taking into account the energy arrivals over time and the quality of channel state information (CSI) available at the transmitter, in order to maximize the throughput. Differently from previous work, the CSI at the transmitter is not perfect and may include estimation errors. We solve this problem with respect to the energy harvesting constraints. Assuming a perfect knowledge of the CSI at the receiver, we determine the optimal power policy for different models of the energy arrival process (offline and online model). Indeed, we obtain the power allocation scheme when the transmitter has either perfect CSI or no CSI. We also investigate of utmost interest the case of fading channels with imperfect CSI. Moreover, a study of the asymptotic behavior of the communication system is proposed. Specifically, we analyze of the average throughput in a system where the average recharge rate goes asymptotically to zero and when it is very high.

Performance limitations in thieno[3,4-c]pyrrole-4,6-dione-based polymer:ITIC solar cells

KAUST Repository

Yang, Fan

2017-08-15

We report a systematic study of the efficiency limitations of non-fullerene organic solar cells that exhibit a small energy loss (Eloss) between the polymer donor and the non-fullerene acceptor. To clarify the impact of Eloss on the performance of the solar cells, three thieno[3,4-c]pyrrole-4,6-dione-based conjugated polymers (PTPD3T, PTPD2T, and PTPDBDT) are employed as the electron donor, which all have complementary absorption spectra compared with the ITIC acceptor. The corresponding photovoltaic devices show that low Eloss (0.54 eV) in PTPDBDT:ITIC leads to a high open-circuit voltage (Voc) of 1.05 V, but also to a small quantum efficiency, and in turn photocurrent. The high Voc or small energy loss in the PTPDBDT-based solar cells is a consequence of less non-radiative recombination, whereas the low quantum efficiency is attributed to the unfavorable micro-phase separation, as confirmed by the steady-state and time-resolved photoluminescence experiments, grazing-incidence wide-angle X-ray scattering, and resonant soft X-ray scattering (R-SoXS) measurements. We conclude that to achieve high performance non-fullerene solar cells, it is essential to realize a large Voc with small Eloss while simultaneously maintaining a high quantum efficiency by manipulating the molecular interaction in the bulk-heterojunction.

Performance limitations in thieno[3,4-c]pyrrole-4,6-dione-based polymer:ITIC solar cells

KAUST Repository

Yang, Fan; Qian, Deping; Balawi, Ahmed Hesham; Wu, Yang; Ma, Wei; Laquai, Fré dé ric; Tang, Zheng; Zhang, Fengling; Li, Weiwei

2017-01-01

We report a systematic study of the efficiency limitations of non-fullerene organic solar cells that exhibit a small energy loss (Eloss) between the polymer donor and the non-fullerene acceptor. To clarify the impact of Eloss on the performance of the solar cells, three thieno[3,4-c]pyrrole-4,6-dione-based conjugated polymers (PTPD3T, PTPD2T, and PTPDBDT) are employed as the electron donor, which all have complementary absorption spectra compared with the ITIC acceptor. The corresponding photovoltaic devices show that low Eloss (0.54 eV) in PTPDBDT:ITIC leads to a high open-circuit voltage (Voc) of 1.05 V, but also to a small quantum efficiency, and in turn photocurrent. The high Voc or small energy loss in the PTPDBDT-based solar cells is a consequence of less non-radiative recombination, whereas the low quantum efficiency is attributed to the unfavorable micro-phase separation, as confirmed by the steady-state and time-resolved photoluminescence experiments, grazing-incidence wide-angle X-ray scattering, and resonant soft X-ray scattering (R-SoXS) measurements. We conclude that to achieve high performance non-fullerene solar cells, it is essential to realize a large Voc with small Eloss while simultaneously maintaining a high quantum efficiency by manipulating the molecular interaction in the bulk-heterojunction.

FTU pump limiter

International Nuclear Information System (INIS)

Alessandrini, C.; Ciotti, M.; Mattei, A. De; Maddaluno, G.; Mazzitelli, G.

1989-01-01

The control of the refuelling and recycling of the plasma is crucial in providing enhanced performances in tokamaks and steady-state operation in future reactors. In this paper, we report details of the design and analysis for the pump limiter to be incorporated into the FTU tokamak. The FTU, presently under commissioning, is a compact high field (B=8T), medium high density, circular cross section machine with small accesses. The dimensions of the equatorial port (width 8 cm) would reduce the length of the entrance throat to a few centimeters, which is unacceptable for efficient particle trapping. We have, therefore, designed a rotating blade of the pump limiter head that, in the working position, extends in the toroidal direction inside the vacuum chamber. (author) 8 refs., 4 figs

Hadron collider luminosity limitations

CERN Document Server

Evans, Lyndon R

1992-01-01

The three colliders operated to date have taught us a great deal about the behaviour of both bunched and debunched beams in storage rings. The main luminosity limitations are now well enough understood that most of them can be stronglu attenuated or eliminated by approriate design precautions. Experience with the beam-beam interaction in both the SPS and the Tevatron allow us to predict the performance of the new generation of colliders with some degree of confidence. One of the main challenges that the accelerator physicist faces is the problem of the dynamic aperture limitations due to the lower field quality expected, imposed by economic and other constraints.

Are altitudinal limits of equatorial stream insects reflected in their respiratory performance?

DEFF Research Database (Denmark)

Jacobsen, Dean; Brodersen, Klaus Peter

2008-01-01

.6 between genera at 17 °C, and from 1.3 to 2.5 at 5 °C. Q10 values for this temperature interval ranged 1.5-2.9 (mean 2.3). The two "high-altitude" genera had higher respiration rates at low temperature and oxygen saturation, and their respiration rate saturated at lower temperatures, than three of the four......-term physiological tolerance of low temperature and oxygen concentration. 5. Multiple regressions (based on respiration experiments and previously obtained relationships between water temperature, oxygen saturation and altitude) were used to predict how respiration rates should vary with altitude. At the upper limit...... saturation. Further quantitative and long-term studies on survival and recruitment in populations and communities are needed to determine the importance of temperature and oxygen for altitudinal limits of aquatic insects....

The Augmented Performer and the Performative Augmentation

DEFF Research Database (Denmark)

Kallionpaa, Maria; Gasselseder, Hans-Peter

2016-01-01

Composers, performers, and listeners usually regard musical compositions as unchangeable entities, which limits the composition techniques and decreases the originality of performers ́ interpretations, thus leading to a stagnation of classical music culture. The significance and possibilities of ...

Modular pump limiter systems for large tokamaks

International Nuclear Information System (INIS)

Uckan, T.; Klepper, C.C.; Mioduszewski, P.K.; McGrath, R.T.

1987-09-01

Long-pulse (>10-s) operation of large tokamaks with high-power (>10-MW) heating and extensive external fueling will require correspondingly efficient particle exhaust for density control. A pump limiter can provide the needed exhaust capability by removing a small percentage of the particles, which would otherwise be recycled. Single pump limiter modules have been operated successfully on ISX-B, PDX, TEXTOR, and PLT. An axisymmetric pump limiter is now being installed and will be studied in TEXTOR. A third type of pump limiter is a system that consists of several modules and exhibits performance different from that of a single module. To take advantage of the flexibility of a modular pump limiter system in a high-power, long-pulse device, the power load must be distributed among a number of modules. Because each added module changes the performance of all the others, a set of design criteria must be defined for the overall limiter system. The design parameters for the modules are then determined from the system requirements for particle and power removal. Design criteria and parameters are presented, and the impact on module design of the state of the art in engineering technology is discussed. The relationship between modules are considered from the standpoint of flux coverage and shadowing effects. The results are applied to the Tore Supra tokamak. A preliminary conceptual design for the Tore Supra pump limiter system is discussed, and the design parameters of the limiter modules are presented. 21 refs., 12 figs

Analytical performance, reference values and decision limits. A need to differentiate between reference intervals and decision limits and to define analytical quality specifications

DEFF Research Database (Denmark)

Petersen, Per Hyltoft; Jensen, Esther A; Brandslund, Ivan

2012-01-01

of the values of analytical components measured on reference samples from reference individuals. Decision limits are based on guidelines from national and international expert groups defining specific concentrations of certain components as limits for decision about diagnosis or well-defined specific actions....... Analytical quality specifications for reference intervals have been defined for bias since the 1990s, but in the recommendations specified in the clinical guidelines analytical quality specifications are only scarcely defined. The demands for negligible biases are, however, even more essential for decision...... limits, as the choice is no longer left to the clinician, but emerge directly from the concentration. Even a small bias will change the number of diseased individuals, so the demands for negligible biases are obvious. A view over the analytical quality as published gives a variable picture of bias...

Nitrate limitation and ocean acidification interact with UV-B to reduce photosynthetic performance in the diatom Phaeodactylum tricornutum

Science.gov (United States)

Li, W.; Gao, K.; Beardall, J.

2015-04-01

It has been proposed that ocean acidification (OA) will interact with other environmental factors to influence the overall impact of global change on biological systems. Accordingly we investigated the influence of nitrogen limitation and OA on the physiology of diatoms by growing the diatom Phaeodactylum tricornutum Bohlin under elevated (1000 μatm; high CO2 - HC) or ambient (390 μatm; low CO2 - LC) levels of CO2 with replete (110 μmol L-1; high nitrate - HN) or reduced (10 μmol L-1; low nitrate - LN) levels of NO3- and subjecting the cells to solar radiation with or without UV irradiance to determine their susceptibility to UV radiation (UVR, 280-400 nm). Our results indicate that OA and UVB induced significantly higher inhibition of both the photosynthetic rate and quantum yield under LN than under HN conditions. UVA or/and UVB increased the cells' non-photochemical quenching (NPQ) regardless of the CO2 levels. Under LN and OA conditions, activity of superoxide dismutase and catalase activities were enhanced, along with the highest sensitivity to UVB and the lowest ratio of repair to damage of PSII. HC-grown cells showed a faster recovery rate of yield under HN but not under LN conditions. We conclude therefore that nutrient limitation makes cells more prone to the deleterious effects of UV radiation and that HC conditions (ocean acidification) exacerbate this effect. The finding that nitrate limitation and ocean acidification interact with UV-B to reduce photosynthetic performance of the diatom P. tricornutum implies that ocean primary production and the marine biological C pump will be affected by OA under multiple stressors.

On the density limit of Tokamaks

International Nuclear Information System (INIS)

Lehnert, B.

1982-12-01

Under the conditions of so far performed quasi-steady tokamak experiments near the density limit, the plasma pressure gradient in the outer layers of the plasma body becomes mainly determined by the plasma-neutral gas balance. An earlier analysis of ballooning instabilities driven by this gradient in regions of bad curvature has been extended to deduce an explicit stability criterion which determines the density limit. This criterion is closely related to the empirical Murakami limit. At relevant tokamak data, the deduced limit becomes proportional to J(sub)zR(sup)1/2 where J(sub)z is the average current density and R the major plasma radius. It is further found to be independent of the toroidal magnetic field strength and anomalous transport, as well as to be a slow function of the outer layer temperature and the mass number. The deduced stability criterion is consistent with so far performed experiments. Provided that the present analysis can be extrapolated to a wider range of parameter data and be combined with Alcator scaling, conditions near ignition appear to become realizable in small tokamaks by ohmic heating alone. These conditions can be satisfied at relevant magnetic field strengths and plasma currents, by imposing a high plasma current density. (author)

Analysis of forming limit in tube hydroforming

International Nuclear Information System (INIS)

Kim, Chan Il; Yang, Seung Hang; Kim, Young Suk

2013-01-01

The automotive industry has shown increasing interest in tube hydroforming. Despite many automobile structural parts being produced from cylindrical tubes, failures frequently occur during tube hydroforming under improper forming conditions. These problems include wrinkling, buckling, folding back, and bursting. We perform analytical studies to determine forming limits in tube hydroforming and demonstrate how these forming limits are influenced by the loading path. Theoretical results for the forming limits of wrinkling and bursting are compared with experimental results for an aluminum tube.

7 CFR 1400.204 - Limited partnerships, limited liability partnerships, limited liability companies, corporations...

Science.gov (United States)

2010-01-01

... 7 Agriculture 10 2010-01-01 2010-01-01 false Limited partnerships, limited liability partnerships..., limited liability partnerships, limited liability companies, corporations, and other similar legal entities. (a) A limited partnership, limited liability partnership, limited liability company, corporation...

Designs for a TFTR full-power pumped limiter

International Nuclear Information System (INIS)

Budny, R.

1986-10-01

A pumped-limiter system which would provide increased particle control and enhance the performance of full-power discharges is being considered for TFTR. The system consists of two toroidal belts located near the Zirconium-Aluminium (ZrAl) getter panels. The limiter blades would be made of carbon/carbon composite in order to have a very thin profile, allowing a large fraction of the scrape-off flux to be pumped. Simulations of the plasma scrape-off and neutral transport indicate that the limiter pumping should reduce the recycling coefficient by 10 to 25%. Simulations of central plasma processes indicate that the lowered recycling could increase Q/sub fusion/ by more than 100%. This paper discusses the designs and the performance predictions for the system

Derivation of the Crick-Wyman equation for allosteric proteins defining the difference between the number of binding sites and the Hill coefficient.

Science.gov (United States)

Poitevin, Frédéric; Edelstein, Stuart J

2013-05-13

In response to a 100-word footnote in the 1965 article by Monod, Wyman, and Changeux, a detailed manuscript signed by Francis Crick and Jeffries Wyman with 6000 words and 30 equations entitled "A Footnote on Allostery" circulated in 1965 among a limited group of scientists interested in allosteric interactions. This interesting and provocative document is published in this special issue for the first time. An intriguing equation in their text relates the difference between n (the number of ligand binding sites) and n' (the Hill coefficient) to the ratio of the saturation functions Y¯, for oligomers with n-1 and n binding sites. A compact derivation of this equation was not provided by Crick and Wyman, but one is presented here based on a definition of Y¯ involving the binding polynomial and its first derivative. Copyright © 2013 Elsevier Ltd. All rights reserved.

THE CHALLENGES OF CORPORATE GOVERNANCE AND AUDIT IN RELATION TO FINANCIAL PERFORMANCE – TRENDS, LIMITATIONS AND DIRECTIONS TO FOLLOW

Directory of Open Access Journals (Sweden)

Alexandra Narcisa CIOBAN (LUCAN

2016-12-01

Full Text Available Through this paper we propose to identify and present the latest trends in valuing the corporate governance and audit features in relation to the company performance, measured in financial terms. Our research is qualitative, as it covers a wide range of approache from the perspective of academics and practitioners in the field. In this regard, we consulted the most important resources in the world scientific electronic documentation, such as: Thomson Reuters Web of Science, SpringerLink platform, PROQUEST Central, Oxford Journals, Emerald Journals and other research platforms. The contribution of this research it is valuable both for researchers in the area of financial accounting and practitioners, and aims to identify the recent challenges of the corporate governance and audit in influencing the financial performance of major companies around the world. We analyzed a variety of scientific publications on this subject, more than 70 empirical studies conducted in the US, China, Russia, Japan, India, Malaysia, the Arab countries, UK, Germany, Spain, Romania, etc. After having conducted the research, we carried out a platform with representative variables for corporate governance, audit and financial performance which will serve for future studies in the field. This will facilitate the researchers’ choice for building econometric analysis models since we also surprised existing limitations.

Controlling proteins through molecular springs.

Science.gov (United States)

Zocchi, Giovanni

2009-01-01

We argue that the mechanical control of proteins-the notion of controlling chemical reactions and processes by mechanics-is conceptually interesting. We give a brief review of the main accomplishments so far, leading to our present approach of using DNA molecular springs to exert controlled stresses on proteins. Our focus is on the physical principles that underlie both artificial mechanochemical devices and natural mechanisms of allostery.

Correlation of shoulder range of motion limitations at discharge with limitations in activities and participation one year later in persons with spinal cord injury.

Science.gov (United States)

Eriks-Hoogland, Inge E; de Groot, Sonja; Post, Marcel W M; van der Woude, Lucas H V

2011-02-01

To study the correlation between limited shoulder range of motion in persons with spinal cord injury at discharge and the performance of activities, wheeling performance, transfers and participation one year later. Multicentre prospective cohort study. A total of 146 newly injured subjects with spinal cord injury. Shoulder range of motion was measured at discharge. One year later, Functional Independence Measure (FIM), transfer ability, wheelchair circuit and Physical Activity Scale for Individuals with Physical Disabilities (PASIPD) were assessed. Corrections were made for possible confounding factors (age, gender, level and completeness of injury, time since injury and shoulder pain). All subjects with limited shoulder range of motion at discharge had a lower FIM motor score and were less likely (total group 5 times, and subjects with tetraplegia 10 times less likely) to be able to perform an independent transfer one year later. Subjects with limited shoulder range of motion in the total group needed more time to complete the wheelchair circuit. No significant associations with the PASIPD were found in either group. Persons with spinal cord injury and limited shoulder range of motion at discharge are more limited in their activities one year later than those without limited shoulder range of motion.

Efficiencies and coefficients of performance of heat engines, refrigerators, and heat pumps with friction: a universal limiting behavior.

Science.gov (United States)

Bizarro, João P S; Rodrigues, Paulo

2012-11-01

For work-producing heat engines, or work-consuming refrigerators and heat pumps, the percentage decrease caused by friction in their efficiencies, or coefficients of performance (COP's), is approximately given by the ratio W(fric)/W between the work spent against friction forces and the work performed by, or delivered to, the working fluid. This universal scaling, which applies in the limit of small friction (W(fric)/W heat-engine efficiencies), allows a simple and quick estimate of the impact that friction losses can have on the FOM's of thermal engines and plants, or of the level of those losses from the observed and predicted FOM's. In the case of refrigerators and heat pumps, if W(fric)/W heat engines), the COP percentage decrease due to friction approaches asymptotically (W(fric)/W)/(1+W(fric)/W) instead of W(fric)/W. Estimates for the level of frictional losses using the Carnot (or, for heat engines and power plants only, the Curzon-Ahlborn) predictions and observed FOM's of real power plants, heat engines, refrigerators, and heat pumps show that they usually operate in domains where these behaviors are valid.

ZEPLIN-II limits on WIMP-nucelon interactions

International Nuclear Information System (INIS)

Alner, G. J.; Bungau, C.; Camanzi, B.; Durkin, T.; Edwards, B.; Lewin, J. D.; Luescher, R.; Preece, R. M.; Smith, N. J. T.; Smith, P. F.; Sumner, T. J.; Thorne, C.; Araujo, H. M.; Bewick, A.; Davidge, D.; Dawson, J.; Howard, A. S.; Jones, W. G.; Joshi, M.; Lebedenko, V. N.

2009-01-01

ZEPLIN II is a two-phase xenon detector designed to detect dark matter in the form of Weakly Interacting Massive Particles (WIMPs). Following the first 31-day underground run in Boulby Mine, UK, the collaboration published dark matter limits in January 2007; the first such limits using two-phase xenon technology. We outline the key detector design, performance and results here.

Performance and stability limits at near-unity aspect ratio in the Pegasus Toroidal Experiment

International Nuclear Information System (INIS)

Fonck, R.J.

2002-01-01

The Pegasus Toroidal Experiment is a mid-sized extremely-low aspect ratio (A) spherical torus (ST). It has the dual roles of exploring limits of ST behavior as A approaches 1 and studying the physics of ST plasmas in the tokamak-spheromak overlap regime. Major parameters are R 0.25 - 0.45 m, A 1.1 - 1.4, I p ≤ 0.15MA, and B t p =aB t is similar to that observed for NBI-heated START discharges. Achievable plasma current apparently is subject to a 'soft' limit of I p =I t f ≤ 1. Access to higher-current plasmas appears to be restricted by the appearance of large internal MHD activity, including m/n=2/1 and 3/2 modes. Recent experiments have begun to access ideal stability limits, with disruptions observed as q 95 approaches 5, in agreement with numerical predictions. (author)

12 CFR 228.25 - Community development test for wholesale or limited purpose banks.

Science.gov (United States)

2010-01-01

... Performance § 228.25 Community development test for wholesale or limited purpose banks. (a) Scope of test. The... performance of a wholesale or limited purpose bank pursuant to the following criteria: (1) The number and... performance rating. The Board rates a bank's community development performance as provided in appendix A of...

Particle removal with pump limiters in ISX-B

International Nuclear Information System (INIS)

Mioduszewski, P.; Emerson, L.C.; Simpkins, J.E.

1983-01-01

First pump limiter experiments were performed on ISX-B. Two pump limiter modules were installed in the top and bottom of one toroidal sector of the tokamak. The modules consist of inertia cooled, TiC coated graphite heads and Zr-Al getter pumps each with a pumping speed of 1000 to 2000 l/s. The objective of the initial experiments was the demonstration of plasma particle control with pump limiters. The first set of experiments were performed in ohmic discharges (OH) in which the effect of the pump limiters on the plasma density was clearly demonstrated. In discharges characterized by: I/sub p/ = 110 kA, B/sub T/ = 15 kG, anti n/sub e/ = 1 - 5 x 10 13 cm -3 and t = 0.3 s the pressure rise in the pump limiters was typically 2 mTorr with the pumps off and 0.7 mTorr after activating the pumps. When the pumps were activated, the line-average plasma density decreased by up to a factor 2 at identical gas flow rates. The second set of measurements were performed in neutral beam heated discharges (NBI) with injected powers between 0.6 MW and 1.0 MW. Due to a cooling problem on one of the Zr-Al pumps the NBI experiments were carried out with one limiter only. The maximum pressure observed in NBI-discharges was 5 mTorr without activating the pumps, i.e., approximately twice as high as in OH-discharges. The exhaust efficiency, which is defined as the removed particle flux over the total particle flux in the scrape-off layer is estimated to be 5%

Materials Genome in Action: Identifying the Performance Limits of Physical Hydrogen Storage

Science.gov (United States)

2017-01-01

The Materials Genome is in action: the molecular codes for millions of materials have been sequenced, predictive models have been developed, and now the challenge of hydrogen storage is targeted. Renewably generated hydrogen is an attractive transportation fuel with zero carbon emissions, but its storage remains a significant challenge. Nanoporous adsorbents have shown promising physical adsorption of hydrogen approaching targeted capacities, but the scope of studies has remained limited. Here the Nanoporous Materials Genome, containing over 850 000 materials, is analyzed with a variety of computational tools to explore the limits of hydrogen storage. Optimal features that maximize net capacity at room temperature include pore sizes of around 6 Å and void fractions of 0.1, while at cryogenic temperatures pore sizes of 10 Å and void fractions of 0.5 are optimal. Our top candidates are found to be commercially attractive as “cryo-adsorbents”, with promising storage capacities at 77 K and 100 bar with 30% enhancement to 40 g/L, a promising alternative to liquefaction at 20 K and compression at 700 bar. PMID:28413259

Performance and stability limits at near-unity aspect ratio in the pegasus toroidal experiment

International Nuclear Information System (INIS)

Fonck, R.; Diem, S.; Garstka, G.; Kissick, M.; Lewicki, B.; Ostrander, C.; Probert, P.; Reinke, M.; Sontag, A.; Tritz, K.; Unterberg, E.

2003-01-01

The Pegasus Toroidal Experiment is a mid-sized extremely-low aspect ratio (A) spherical torus (ST). It has the dual roles of exploring limits of ST behavior as A approaches 1 and studying the physics of ST plasmas in the tokamak-spheromak overlap regime. Major parameters are R 0.25 - 0.45 m, A 1.1 - 1.4, I p T 20% have been obtained, and the operational space of beta vs I p /aB T is similar to that observed for NBI-heated START discharges. Achievable plasma current is subject to an apparent limit of I p /I tf ∼ 1. Access to higher-current plasmas appears to be restricted by the appearance of large internal MHD activity, including m/n=2/1 and 3/2 modes. Recent experiments have begun to access ideal stability limits, with disruptions observed as q 95 approaches 5, in agreement with numerical predictions for external kink mode onset. (author)

The quasi-abelian limit

International Nuclear Information System (INIS)

Fried, H.M.; Avan, J.

2000-01-01

A new, non-perturbative, eikonal method called the ''quasi abelian limit'' (QAL) is suggested for high energy quark (nucleon) scattering involving the exchange of all possible, non-interacting, non-abelian gluons (mesons). With this method, those functional integrals defining, e.g., the exchange of color coordinates in quark-quark scattering, are replaced by a finite number of quadratures over a subset of their coordinates. Mathematically, this procedure is not rigourous, because an unjustified interchange of limits has been performed; physically, it corresponds to the observation that the non-perturbative sum over all color-moment fluctuations can vanish at arbitrarily high energies. The QAL generates a result in agreement with a corrected, ''contiguity'' calculation, when the latter is summed over all perturbative orders. (orig.)

Halden fuel and material experiments beyond operational and safety limits

International Nuclear Information System (INIS)

Volkov, Boris; Wiesenack, Wolfgang; McGrath, M.; Tverberg, T.

2014-01-01

One of the main tasks of any research reactor is to investigate the behavior of nuclear fuel and materials prior to their introduction into the market. For commercial NPPs, it is important both to test nuclear fuels at a fuel burn-up exceeding current limits and to investigate reactor materials for higher irradiation dose. For fuel vendors such tests enable verification of fuel reliability or for the safety limits to be found under different operational conditions and accident situations. For the latter, in-pile experiments have to be performed beyond some normal limits. The program of fuel tests performed in the Halden reactor is aimed mainly at determining: The thermal FGR threshold, which may limit fuel operational power with burn-up increase, the “lift-off effect” when rod internal pressure exceeds coolant pressure, the effects of high burn-up on fuel behavior under power ramps, fuel relocation under LOCA simulation at higher burn-up, the effect of dry-out on high burn-up fuel rod integrity. This paper reviews some of the experiments performed in the Halden reactor for understanding some of the limits for standard fuel utilization with the aim of contributing to the development of innovative fuels and cladding materials that could be used beyond these limits. (author)

Pumped-limiter study for Alcator DCT

International Nuclear Information System (INIS)

Brooks, J.N.; Mattas, R.F.; Cha, Y.S.; Hassanein, A.M.; Majumdar, S.

1983-06-01

A study was performed for a pumped-limiter design for the proposed Alcator DCT device. The study focused on reactor-relevant issues. The main issues examined were configuration, surface erosion, thermal hydraulics, and the choice of structural and surface materials. A bottom, flat limiter, with a copper-alloy substrate, seems to be a reasonable design and should provide an opportunity to test high power and particle loadings. Carbon is recommended as a surface material if acceptable redeposition properties can be demonstrated

Pumped-limiter study for Alcator DCT

Energy Technology Data Exchange (ETDEWEB)

Brooks, J.N.; Mattas, R.F.; Cha, Y.S.; Hassanein, A.M.; Majumdar, S.

1983-06-01

A study was performed for a pumped-limiter design for the proposed Alcator DCT device. The study focused on reactor-relevant issues. The main issues examined were configuration, surface erosion, thermal hydraulics, and the choice of structural and surface materials. A bottom, flat limiter, with a copper-alloy substrate, seems to be a reasonable design and should provide an opportunity to test high power and particle loadings. Carbon is recommended as a surface material if acceptable redeposition properties can be demonstrated.

Tokamak plasma interaction with limiters

International Nuclear Information System (INIS)

Pitcher, C.S.

1987-11-01

The importance of plasma purity is first discussed in terms of the general requirements of controlled thermonuclear fusion. The tokamak approach to fusion and its inherent problem of plasma contamination are introduced. A main source of impurities is due to the bombardment of the limiter by energetic particles and thus the three main aspects of the plasma-limiter interaction are reviewed, boundary plasma conditions, fuelling/recycling and impurity production. The experiments, carried out on the DITE tokamak at Culham Laboratory, UK, investigated these three topics and the results are compared with predicted behaviour; new physical phenomena are presented in all three areas. Simple one-dimensional fluid equations are found to adequately describe the SOL plasma, except in regard to the pre-sheath electric field and ambipolarity; that is, the electric field adjacent to the limiter surface appears to be weak and the associated plasma flow can be non-ambipolar. Recycling of fuel particles from the limiter is observed to be near unity at all times. The break-up behaviour of recycled and gas puffed D 2 molecules is dependent on the electron temperature, as expected. Impurity production at the limiter is chemical erosion of graphite being negligible. Deposition of limiter and wall-produced impurities is found on the limiter. The spatial distributions of impurities released from the limiter are observed and are in good agreement with a sputtered atom transport code. Finally, preliminary experiments on the transport of impurity ions along field lines away from the limiter have been performed and compared with simple analytic theory. The results suggest that the pre-sheath electric field in the SOL is much weaker than the simple fluid model would predict

Limits of detection and decision. Part 4

International Nuclear Information System (INIS)

Voigtman, E.

2008-01-01

Probability density functions (PDFs) have been derived for a number of commonly used limit of detection definitions, including several variants of the Relative Standard Deviation of the Background-Background Equivalent Concentration (RSDB-BEC) method, for a simple linear chemical measurement system (CMS) having homoscedastic, Gaussian measurement noise and using ordinary least squares (OLS) processing. All of these detection limit definitions serve as both decision and detection limits, thereby implicitly resulting in 50% rates of Type 2 errors. It has been demonstrated that these are closely related to Currie decision limits, if the coverage factor, k, is properly defined, and that all of the PDFs are scaled reciprocals of noncentral t variates. All of the detection limits have well-defined upper and lower limits, thereby resulting in finite moments and confidence limits, and the problem of estimating the noncentrality parameter has been addressed. As in Parts 1-3, extensive Monte Carlo simulations were performed and all the simulation results were found to be in excellent agreement with the derived theoretical expressions. Specific recommendations for harmonization of detection limit methodology have also been made

Performance Analysis of a Power Limited Spectrum Sharing System with TAS/MRC

KAUST Repository

Khan, Fahd Ahmed; Tourki, Kamel; Alouini, Mohamed-Slim; Qaraqe, Khalid A.

2014-01-01

multiple antennas on the secondary network terminals and performing antenna selection. In this paper, the performance of a multiple-input multiple-output (MIMO) secondary link with transmit antenna selection (TAS) at the transmitter and maximum ratio

Optimization of an impact limiter for radioactive waste packaging

International Nuclear Information System (INIS)

Mourao, Rogerio Pimenta; Mattar Neto, Miguel

1999-01-01

A certain class of packages for the transportation of radioactive wastes - type B packages in the transport jargon - is supposed to resist to a series of postulated tests, the most severe for the majority of the packages being the 9 m height drop test. To improve the performance of the packages under this test, impact limiters are added to them, normally as a removable overpack, with the primary goal of reducing the deceleration loads transmitted to the packages and their contents. The first impact limiter concept, developed during the '70s, used a shell-type impact limiter attached to both ends of the package. Later on, wood was tested as impact limiter filling, which improved the package's mechanical performance, but not its thermal resistance. The popularization of the polymeric materials and their growing use in engineer applications have led to the use of these materials in impact limiters, with the extra advantage of the polymers good thermal properties. This paper proposes a methodology for the optimization of an impact limiter for a package for the conditioning of spent sealed sources. Two simplified methods for the design of impact limiters are presented. Finally, a brief discussion is presented on the methodology usually employed in the design of accident-resisting packages. (author)

Chemical exchange in biomacromolecules: Past, present, and future

Science.gov (United States)

Palmer, Arthur G.

2014-01-01

The perspective reviews quantitative investigations of chemical exchange phenomena in proteins and other biological macromolecules using NMR spectroscopy, particularly relaxation dispersion methods. The emphasis is on techniques and applications that quantify the populations, interconversion kinetics, and structural features of sparsely populated conformational states in equilibrium with a highly populated ground state. Applications to folding, mol ecular recognition, catalysis, and allostery by proteins and nucleic acids are highlighted. PMID:24656076

Short Communication: Comparison of Maxim and Sedia Limiting Antigen Assay Performance for Measuring HIV Incidence.

Science.gov (United States)

Schlusser, Katherine E; Konikoff, Jacob; Kirkpatrick, Allison R; Morrison, Charles; Chipato, Tsungai; Chen, Pai-Lien; Munjoma, Marshall; Eshleman, Susan H; Laeyendecker, Oliver

2017-06-01

Accurate methods for cross-sectional incidence estimation are needed for HIV prevention research. The Limiting Antigen Avidity (LAg-Avidity) assay has been marketed by two vendors, Maxim Biomedical and Sedia BioSciences Corporation. Performance differences between the two versions of the assay are unknown. We tested a total 1,410 treatment-naive samples with both versions of the assay. The samples came from 176 seroconverters from the Zimbabwe Hormonal Contraception and HIV Study. The correlation between the two versions of the assay was 0.93 for the optical density (OD) and 0.86 for the normalized OD. As the difference was more pronounced for the normalized OD, the difference in assays can be attributed to the calibrators. The mean duration of recent infection (MDRI), the average time individuals infected 1,000 copies/ml. The MDRI was 137 days for Sedia and 157 days for Maxim, with a difference of 20 days (95% CI 11-30). The MDRIs decreased to 102 and 120 days with the inclusion of a viral load cutoff of >1,000 copies/ml. These results imply that use of the Sedia LAg-Avidity will result in estimates of incidence ∼13% lower than those using the Maxim LAg-Avidity.

Physical limits of silicon transistors and circuits

International Nuclear Information System (INIS)

Keyes, Robert W

2005-01-01

A discussion on transistors and electronic computing including some history introduces semiconductor devices and the motivation for miniaturization of transistors. The changing physics of field-effect transistors and ways to mitigate the deterioration in performance caused by the changes follows. The limits of transistors are tied to the requirements of the chips that carry them and the difficulties of fabricating very small structures. Some concluding remarks about transistors and limits are presented

High performance H-mode plasmas at densities above the Greenwald limit

International Nuclear Information System (INIS)

Mahdavi, M.A.; Osborne, T.H.; Leonard, A.W.

2001-01-01

Densities up to 40 percent above the Greenwald limit are reproducibly achieved in high confinement (H ITER89p =2) ELMing H-mode discharges. Simultaneous gas fueling and divertor pumping were used to obtain these results. Confinement of these discharges, similar to moderate density H-mode, is characterized by a stiff temperature profile, and therefore sensitive to the density profile. A particle transport model is presented that explains the roles of divertor pumping and geometry for access to high densities. Energy loss per ELM at high density is a factor of five lower than predictions of an earlier scaling, based on data from lower density discharges. (author)

40 CFR 434.63 - Effluent limitations for precipitation events.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Effluent limitations for precipitation... SOURCE PERFORMANCE STANDARDS Miscellaneous Provisions § 434.63 Effluent limitations for precipitation... discharge or increase in the volume of a discharge caused by precipitation within any 24 hour period less...

Alkali Metal-O2 Batteries. Performance and Lifetime Limiting Effects

DEFF Research Database (Denmark)

Knudsen, Kristian Bastholm

The rechargeable Na-O2 and Li-O2 batteries are attractive battery technologies as they potentially are very cheap and as they theoretically possess about 3 and 10 times higher energy density than the current Li-ion technologies. This PhD thesis is dedicated to studying the effects that limit cell...... product, Li2O2, was investigated. This was done by using of a conventional three electrode cell in which the heterogeneous electron transfer rate of three different redox couples were studied on Li2O2 coated glassy carbon electrodes to provide a measure of the conductivity of the Li2O2 layers. Charge....... The capacitance of the cathode was shown to be sensitive to the thickness of the deposited Li2O2 layer. These investigations also explored the influence of the composition of the electrolyte and conditions, which favors a solution mediated Li2O2 deposition mechanism. On charge, an electrochemical “safe” operating...

40 CFR 35.718 - Award limitation.

Science.gov (United States)

2010-07-01

... included in the Performance Partnership Grant work plan. Hazardous Waste Management Program Grants (Pub.L... ASSISTANCE Environmental Program Grants for Tribes Toxic Substances Compliance Monitoring (section 28) § 35.718 Award limitation. If the Toxic Substances Compliance Monitoring grant funds are included in a...

Scaling limits and reliability of SOI CMOS technology

International Nuclear Information System (INIS)

Ioannou, D E

2005-01-01

As bulk and PD-SOI CMOS approach their scaling limit (at gate length of around 50 nm), there is a renewed interest on FD-SOI because of its potential for continued scalability beyond this limit. In this review the performance and reliability of extremely scaled FD transistors are discussed and an attempt is made to identify critical areas for further research. (invited paper)

Allosteric regulation of rhomboid intramembrane proteolysis.

Science.gov (United States)

Arutyunova, Elena; Panwar, Pankaj; Skiba, Pauline M; Gale, Nicola; Mak, Michelle W; Lemieux, M Joanne

2014-09-01

Proteolysis within the lipid bilayer is poorly understood, in particular the regulation of substrate cleavage. Rhomboids are a family of ubiquitous intramembrane serine proteases that harbour a buried active site and are known to cleave transmembrane substrates with broad specificity. In vitro gel and Förster resonance energy transfer (FRET)-based kinetic assays were developed to analyse cleavage of the transmembrane substrate psTatA (TatA from Providencia stuartii). We demonstrate significant differences in catalytic efficiency (kcat/K0.5) values for transmembrane substrate psTatA (TatA from Providencia stuartii) cleavage for three rhomboids: AarA from P. stuartii, ecGlpG from Escherichia coli and hiGlpG from Haemophilus influenzae demonstrating that rhomboids specifically recognize this substrate. Furthermore, binding of psTatA occurs with positive cooperativity. Competitive binding studies reveal an exosite-mediated mode of substrate binding, indicating allostery plays a role in substrate catalysis. We reveal that exosite formation is dependent on the oligomeric state of rhomboids, and when dimers are dissociated, allosteric substrate activation is not observed. We present a novel mechanism for specific substrate cleavage involving several dynamic processes including positive cooperativity and homotropic allostery for this interesting class of intramembrane proteases. © 2014 The Authors.

75 FR 10438 - Effluent Limitations Guidelines and Standards for the Construction and Development Point Source...

Science.gov (United States)

2010-03-08

... Effluent Limitations Guidelines and Standards for the Construction and Development Point Source Category... technology-based Effluent Limitations Guidelines and New Source Performance Standards for the Construction... technology-based Effluent Limitations Guidelines and New Source Performance Standards for the Construction...

Power MOSFET-diode-based limiter for high-frequency ultrasound systems.

Science.gov (United States)

Choi, Hojong; Kim, Min Gon; Cummins, Thomas M; Hwang, Jae Youn; Shung, K Kirk

2014-10-01

The purpose of the limiter circuits used in the ultrasound imaging systems is to pass low-voltage echo signals generated by ultrasonic transducers while preventing high-voltage short pulses transmitted by pulsers from damaging front-end circuits. Resistor-diode-based limiters (a 50 Ω resistor with a single cross-coupled diode pair) have been widely used in pulse-echo measurement and imaging system applications due to their low cost and simple architecture. However, resistor-diode-based limiters may not be suited for high-frequency ultrasound transducer applications since they produce large signal conduction losses at higher frequencies. Therefore, we propose a new limiter architecture utilizing power MOSFETs, which we call a power MOSFET-diode-based limiter. The performance of a power MOSFET-diode-based limiter was evaluated with respect to insertion loss (IL), total harmonic distortion (THD), and response time (RT). We compared these results with those of three other conventional limiter designs and showed that the power MOSFET-diode-based limiter offers the lowest IL (-1.33 dB) and fastest RT (0.10 µs) with the lowest suppressed output voltage (3.47 Vp-p) among all the limiters at 70 MHz. A pulse-echo test was performed to determine how the new limiter affected the sensitivity and bandwidth of the transducer. We found that the sensitivity and bandwidth of the transducer were 130% and 129% greater, respectively, when combined with the new power MOSFET-diode-based limiter versus the resistor-diode-based limiter. Therefore, these results demonstrate that the power MOSFET-diode-based limiter is capable of producing lower signal attenuation than the three conventional limiter designs at higher frequency operation. © The Author(s) 2014.

Performance and limitations of steatosis biomarkers in patients with nonalcoholic fatty liver disease.

Science.gov (United States)

Fedchuk, L; Nascimbeni, F; Pais, R; Charlotte, F; Housset, C; Ratziu, V

2014-11-01

Several steatosis biomarkers are available with limited independent validation. To determine diagnostic value and limitations of several steatosis biomarkers using liver biopsy as reference standard in a large cohort of patients with suspected NAFLD. Three hundred and twenty-four consecutive liver biopsies were included. Histological steatosis was categorised as none (66%). Five steatosis biomarkers were measured: fatty liver index (FLI), NAFLD liver fat score (NAFLD-LFS), hepatic steatosis index (HSI), visceral adiposity index (VAI) and triglyceride × glucose (TyG) index. Steatosis grades prevalence was: none 5%, mild 39%, moderate 30% and severe 27%. Except for VAI, the steatosis biomarkers showed a linear trend across the steatosis grades. However, their correlation with the histological amount of steatosis was only weak-moderate. All steatosis biomarkers had an adequate diagnostic accuracy for the presence of steatosis: AUROCs for FLI, LFS, HSI, VAI and TyG were 0.83, 0.80, 0.81, 0.92 and 0.90. However, their ability to quantify steatosis was poor: none of them distinguished between moderate and severe steatosis and the AUROCs for predicting steatosis >33% were 0.65, 0.72, 0.65, 0.59 and 0.59 for FLI, LFS, HSI, VAI and TyG. Both fibrosis and inflammation significantly confounded the association between steatosis biomarkers and steatosis. The steatosis biomarkers were all correlated with HOMA-IR, independent from histological steatosis. All five steatosis biomarkers can diagnose steatosis and are correlated with insulin resistance. They are confounded by fibrosis and inflammation, and do not accurately quantify steatosis; this may limit their clinical utility. More research is needed to identify truly independent and quantitative markers of steatosis. © 2014 John Wiley & Sons Ltd.

The ODELIA Study on Noise Limits for Outdoor Machinery

NARCIS (Netherlands)

Dittrich, M.G.; Carletti, E.; Spellerberg, G.

2016-01-01

In the ODELIA study for the European Commission an assessment of the outdoor equipment noise directive 2000/14/EC and its amendment 2005/88/EC has been performed. The directive requires noise marking for 57 types of equipment used outdoors, and sets noise limits for 22 of these. Since the limits

UV DRIVEN EVAPORATION OF CLOSE-IN PLANETS: ENERGY-LIMITED, RECOMBINATION-LIMITED, AND PHOTON-LIMITED FLOWS

International Nuclear Information System (INIS)

Owen, James E.; Alvarez, Marcelo A.

2016-01-01

We have investigated the evaporation of close-in exoplanets irradiated by ionizing photons. We find that the properties of the flow are controlled by the ratio of the recombination time to the flow timescale. When the recombination timescale is short compared to the flow timescale, the flow is in approximate local ionization equilibrium with a thin ionization front where the photon mean free path is short compared to the flow scale. In this “recombination-limited” flow the mass-loss scales roughly with the square root of the incident flux. When the recombination time is long compared to the flow timescale the ionization front becomes thick and encompasses the entire flow with the mass-loss rate scaling linearly with flux. If the planet's potential is deep, then the flow is approximately “energy-limited”; however, if the planet's potential is shallow, then we identify a new limiting mass-loss regime, which we term “photon-limited.” In this scenario, the mass-loss rate is purely limited by the incoming flux of ionizing photons. We have developed a new numerical approach that takes into account the frequency dependence of the incoming ionizing spectrum and performed a large suite of 1D simulations to characterize UV driven mass-loss around low-mass planets. We find that the flow is “recombination-limited” at high fluxes but becomes “energy-limited” at low fluxes; however, the transition is broad occurring over several orders of magnitude in flux. Finally, we point out that the transitions between the different flow types do not occur at a single flux value but depend on the planet's properties, with higher-mass planets becoming “energy-limited” at lower fluxes

Molecular basis of the 14-3-3 protein-dependent activation of yeast neutral trehalase Nth1

Czech Academy of Sciences Publication Activity Database

Alblová, Miroslava; Šmídová, Aneta; Dočekal, V.; Veselý, J.; Herman, P.; Obšilová, Veronika; Obšil, Tomáš

2017-01-01

Roč. 114, č. 46 (2017), E9811-E9820 ISSN 0027-8424 R&D Projects: GA ČR(CZ) GA16-02739S; GA MŠk(CZ) ED1.1.00/02.0109; GA ČR(CZ) GA17-00726S Institutional support: RVO:67985823 Keywords : 14-3-3 protein * trehalase * crystal structure * enzyme * allostery Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Biochemical research methods Impact factor: 9.661, year: 2016

The effect of laser ablation parameters on optical limiting properties of silver nanoparticles

Science.gov (United States)

Gursoy, Irmak; Yaglioglu, Halime Gul

2017-09-01

This paper presents the effect of laser ablation parameters on optical limiting properties of silver nanoparticles. The current applications of lasers such as range finding, guidance, detection, illumination and designation have increased the potential of damaging optical imaging systems or eyes temporary or permanently. The applications of lasers introduce risks for sensors or eyes, when laser power is higher than damage threshold of the detection system. There are some ways to protect these systems such as neutral density (nd) filters, shutters, etc. However, these limiters reduce the total amount of light that gets into the system. Also, response time of these limiters may not be fast enough to prevent damage and cause precipitation in performance due to deprivation of transmission or contrast. Therefore, optical limiting filters are needed that is transparent for low laser intensities and limit or block the high laser intensities. Metal nanoparticles are good candidates for such optical limiting filters for ns pulsed lasers or CW lasers due to their high damage thresholds. In this study we investigated the optical limiting performances of silver nanoparticles produced by laser ablation technique. A high purity silver target immersed in pure water was ablated with a Nd:YAG nanosecond laser at 532 nm. The effect of altering laser power and ablation time on laser ablation efficiency of nanoparticles was investigated experimentally and optimum values were specified. Open aperture Zscan experiment was used to investigate the effect of laser ablation parameters on the optical limiting performances of silver nanoparticles in pure water. It was found that longer ablation time decreases the optical limiting threshold. These results are useful for silver nanoparticles solutions to obtain high performance optical limiters.

Thermal Performance and Operation Limit of Heat Pipe Containing Neutron Absorber

Energy Technology Data Exchange (ETDEWEB)

Kim, Kyung Mo; Jeong, Yeong Shin; Kim, In Guk; Bang, In Choel [UNIST, Ulsan (Korea, Republic of)

2015-05-15

Recently, passive safety systems are under development to ensure the core cooling in accidents involving impossible depressurization such as station blackout (SBO). Hydraulic control rod drive mechanisms, passive auxiliary feedwater system (PAFS), Passive autocatalystic recombiner (PAR), and so on are types of passive safety systems to enhance the safety of nuclear power plants. Heat pipe is used in various engineering fields due to its advantages in terms of easy fabrication, high heat transfer rate, and passive heat transfer. Also, the various concepts associated with safety system and heat transfer using the heat pipe were developed in nuclear engineering field.. Thus, our group suggested the hybrid control rod which combines the functions of existing control rod and heat pipe. If there is significant temperature difference between active core and condenser, the hybrid control rod can shutdown the nuclear fission reaction and remove the decay heat from the core to ultimate heat sink. The unique characteristic of the hybrid control rod is the presence of neutron absorber inside the heat pipe. Many previous researchers studied the effect of parameters on the thermal performance of heat pipe. However, the effect of neutron absorber on the thermal performance of heat pipe has not been investigated. Thus, the annular heat pipe which contains B{sub 4}C pellet in the normal heat pipe was prepared and the thermal performance of the annular heat pipe was studied in this study. Hybrid control rod concept was developed as a passive safety system of nuclear power plant to ensure the safety of the reactor at accident condition. The hybrid control rod must contain the neutron absorber for the function as a control rod. So, the effect of neutron absorber on the thermal performance of heat pipe was experimentally investigated in this study. Temperature distributions at evaporator section of annular heat pipe were lower than normal heat pipe due to the larger volume occupied by

Strong Relation between Muscle Mass Determined by D3-creatine Dilution, Physical Performance and Incidence of Falls and Mobility Limitations in a Prospective Cohort of Older Men.

Science.gov (United States)

Cawthon, Peggy M; Orwoll, Eric S; Peters, Katherine E; Ensrud, Kristine E; Cauley, Jane A; Kado, Deborah M; Stefanick, Marcia L; Shikany, James M; Strotmeyer, Elsa S; Glynn, Nancy W; Caserotti, Paolo; Shankaran, Mahalakshmi; Hellerstein, Marc; Cummings, Steven R; Evans, William J

2018-06-12

Direct assessment of skeletal muscle mass in older adults is clinically challenging. Relationships between lean mass and late-life outcomes have been inconsistent. The D3-creatine dilution method provides a direct assessment of muscle mass. Muscle mass was assessed by D3-creatine (D3Cr) dilution in 1,382 men (mean age, 84.2 yrs). Participants completed the Short Physical Performance Battery (SPPB); usual walking speed (6 meters); and DXA lean mass. Men self-reported mobility limitations (difficulty walking 2-3 blocks or climbing 10 steps); recurrent falls (2+); and serious injurious falls in the subsequent year. Across quartiles of D3Cr muscle mass/body mass, multivariate linear models calculated means for SPPB and gait speed; multivariate logistic models calculated odds ratios for incident mobility limitations or falls. Compared to men in the highest quartile, those in the lowest quartile of D3Cr muscle mass/body mass had slower gait speed (Q1: 1.04 vs Q4: 1.17 m/s); lower SPPB (Q1: 8.4 vs Q4: 10.4 points); greater likelihood of incident serious injurious falls (OR Q1 vs Q4: 2.49, 95% CI: 1.37, 4.54); prevalent mobility limitation (OR Q1 vs Q4,: 6.1, 95%CI: 3.7, 10.3) and incident mobility limitation (OR Q1 vs Q4: 2.15 95% CI: 1.42, 3.26); p for trend strongly related to physical performance, mobility and incident injurious falls in older me.

Force Limited Vibration Test of HESSI Imager

Science.gov (United States)

Amato, Deborah; Pankow, David; Thomsen, Knud

2000-01-01

The High Energy Solar Spectroscopic Imager (HESSI) is a solar x-ray and gamma-ray observatory scheduled for launch in November 2000. Vibration testing of the HESSI imager flight unit was performed in August 1999. The HESSI imager consists of a composite metering tube, two aluminum trays mounted to the tube on titanium flexure mounts, and nine modulation grids mounted on each tray. The vibration tests were acceleration controlled and force limited, in order to prevent overtesting. The force limited strategy reduced the shaker force and notched the acceleration at resonances. The test set-up, test levels, and results are presented. The development of the force limits is also discussed. The imager successfully survived the vibration testing.

INAA - application and limitation

International Nuclear Information System (INIS)

Heydorn, K.

1990-01-01

The uncertainties associated with performing Instrumental Neutron Activation Analysis (INAA) are discussed in relation to their category. The Comite International de Poids et Mesure (CIPM) distinguishes between uncertainties according to how their contribution to the overall uncertainty is evaluated. INAA is a potentially definitive method, if all sources of uncertainty can be accounted for. The limitation of the method is reached when uncertainties, which cannot be accounted for, assume significance, and the method cannot be brought in statistical control. (orig.)

External and internal limitations in amplitude-modulation processing

DEFF Research Database (Denmark)

Ewert, Stephan; Dau, Torsten

2004-01-01

Three experiments are presented to explore the relative role of "external" signal variability and "internal" resolution limitations of the auditory system in the detection and discrimination of amplitude modulations (AM). In the first experiment, AM-depth discrimination performance was determined......-filterbank models. The predictions revealed that AM-depth discrimination and AM detection are limited by a combination of the external signal variability and an internal "Weber-fraction" noise process....

Flux-limited diffusion coefficients in reactor physics applications

International Nuclear Information System (INIS)

Pounders, J.; Rahnema, F.; Szilard, R.

2007-01-01

Flux-limited diffusion theory has been successfully applied to problems in radiative transfer and radiation hydrodynamics, but its relevance to reactor physics has not yet been explored. The current investigation compares the performance of a flux-limited diffusion coefficient against the traditionally defined transport cross section. A one-dimensional BWR benchmark problem is examined at both the assembly and full-core level with varying degrees of heterogeneity. (authors)

The limits on trypanosomatid morphological diversity.

Directory of Open Access Journals (Sweden)

Richard John Wheeler

Full Text Available Cell shape is one, often overlooked, way in which protozoan parasites have adapted to a variety of host and vector environments and directional transmissions between these environments. Consequently, different parasite life cycle stages have characteristic morphologies. Trypanosomatid parasites are an excellent example of this in which large morphological variations between species and life cycle stage occur, despite sharing well-conserved cytoskeletal and membranous structures. Here, using previously published reports in the literature of the morphology of 248 isolates of trypanosomatid species from different hosts, we perform a meta-analysis of the occurrence and limits on morphological diversity of different classes of trypanosomatid morphology (trypomastigote, promastigote, etc. in the vertebrate bloodstream and invertebrate gut environments. We identified several limits on cell body length, cell body width and flagellum length diversity which can be interpreted as biomechanical limits on the capacity of the cell to attain particular dimensions. These limits differed for morphologies with and without a laterally attached flagellum which we suggest represent two morphological superclasses, the 'juxtaform' and 'liberform' superclasses. Further limits were identified consistent with a selective pressure from the mechanical properties of the vertebrate bloodstream environment; trypanosomatid size showed limits relative to host erythrocyte dimensions. This is the first comprehensive analysis of the limits of morphological diversity in any protozoan parasite, revealing the morphogenetic constraints and extrinsic selection pressures associated with the full diversity of trypanosomatid morphology.

Pushing the Performance Limit of Sub-100 nm Molybdenum Disulfide Transistors.

Science.gov (United States)

Liu, Yuan; Guo, Jian; Wu, Yecun; Zhu, Enbo; Weiss, Nathan O; He, Qiyuan; Wu, Hao; Cheng, Hung-Chieh; Xu, Yang; Shakir, Imran; Huang, Yu; Duan, Xiangfeng

2016-10-12

Two-dimensional semiconductors (2DSCs) such as molybdenum disulfide (MoS 2 ) have attracted intense interest as an alternative electronic material in the postsilicon era. However, the ON-current density achieved in 2DSC transistors to date is considerably lower than that of silicon devices, and it remains an open question whether 2DSC transistors can offer competitive performance. A high current device requires simultaneous minimization of the contact resistance and channel length, which is a nontrivial challenge for atomically thin 2DSCs, since the typical low contact resistance approaches for 2DSCs either degrade the electronic properties of the channel or are incompatible with the fabrication process for short channel devices. Here, we report a new approach toward high-performance MoS 2 transistors by using a physically assembled nanowire as a lift-off mask to create ultrashort channel devices with pristine MoS 2 channel and self-aligned low resistance metal/graphene hybrid contact. With the optimized contact in short channel devices, we demonstrate sub-100 nm MoS 2 transistor delivering a record high ON-current of 0.83 mA/μm at 300 K and 1.48 mA/μm at 20 K, which compares well with that of silicon devices. Our study, for the first time, demonstrates that the 2DSC transistors can offer comparable performance to the 2017 target for silicon transistors in International Technology Roadmap for Semiconductors (ITRS), marking an important milestone in 2DSC electronics.

Limitations imposed by wearing armour on Medieval soldiers' locomotor performance.

Science.gov (United States)

Askew, Graham N; Formenti, Federico; Minetti, Alberto E

2012-02-22

In Medieval Europe, soldiers wore steel plate armour for protection during warfare. Armour design reflected a trade-off between protection and mobility it offered the wearer. By the fifteenth century, a typical suit of field armour weighed between 30 and 50 kg and was distributed over the entire body. How much wearing armour affected Medieval soldiers' locomotor energetics and biomechanics is unknown. We investigated the mechanics and the energetic cost of locomotion in armour, and determined the effects on physical performance. We found that the net cost of locomotion (C(met)) during armoured walking and running is much more energetically expensive than unloaded locomotion. C(met) for locomotion in armour was 2.1-2.3 times higher for walking, and 1.9 times higher for running when compared with C(met) for unloaded locomotion at the same speed. An important component of the increased energy use results from the extra force that must be generated to support the additional mass. However, the energetic cost of locomotion in armour was also much higher than equivalent trunk loading. This additional cost is mostly explained by the increased energy required to swing the limbs and impaired breathing. Our findings can predict age-associated decline in Medieval soldiers' physical performance, and have potential implications in understanding the outcomes of past European military battles.

Fundamental limits of positron emission mammography

International Nuclear Information System (INIS)

Moses, William W.; Qi, Jinyi

2001-01-01

We explore the causes of performance limitation in positron emission mammography cameras. We compare two basic camera geometries containing the same volume of 511 keV photon detectors, one with a parallel plane geometry and another with a rectangular geometry. We find that both geometries have similar performance for the phantom imaged (in Monte Carlo simulation), even though the solid angle coverage of the rectangular camera is about 50 percent higher than the parallel plane camera. The reconstruction algorithm used significantly affects the resulting image; iterative methods significantly outperform the commonly used focal plane tomography. Finally, the characteristics of the tumor itself, specifically the absolute amount of radiotracer taken up by the tumor, will significantly affect the imaging performance

Limits on fundamental limits to computation.

Science.gov (United States)

Markov, Igor L

2014-08-14

An indispensable part of our personal and working lives, computing has also become essential to industries and governments. Steady improvements in computer hardware have been supported by periodic doubling of transistor densities in integrated circuits over the past fifty years. Such Moore scaling now requires ever-increasing efforts, stimulating research in alternative hardware and stirring controversy. To help evaluate emerging technologies and increase our understanding of integrated-circuit scaling, here I review fundamental limits to computation in the areas of manufacturing, energy, physical space, design and verification effort, and algorithms. To outline what is achievable in principle and in practice, I recapitulate how some limits were circumvented, and compare loose and tight limits. Engineering difficulties encountered by emerging technologies may indicate yet unknown limits.

Correlation and image compression for limited-bandwidth CCD.

Energy Technology Data Exchange (ETDEWEB)

Thompson, Douglas G.

2005-07-01

As radars move to Unmanned Aerial Vehicles with limited-bandwidth data downlinks, the amount of data stored and transmitted with each image becomes more significant. This document gives the results of a study to determine the effect of lossy compression in the image magnitude and phase on Coherent Change Detection (CCD). We examine 44 lossy compression types, plus lossless zlib compression, and test each compression method with over 600 CCD image pairs. We also derive theoretical predictions for the correlation for most of these compression schemes, which compare favorably with the experimental results. We recommend image transmission formats for limited-bandwidth programs having various requirements for CCD, including programs which cannot allow performance degradation and those which have stricter bandwidth requirements at the expense of CCD performance.

First pump limiter experiments in Tore Supra

International Nuclear Information System (INIS)

Chatelier, M.; Bruneau, J.L.; Chappuis, P.; Gil, C.; Guilhem, D.; Lipa, M.; Rodriguez, L.; Vallet, J.C.; Van Houtte, D.; Watkins, J.G.

1989-01-01

The thermal load and the particle pumping effects on the outboard pump limiters (OPL), in Tore Supra are analyzed. The investigations are performed for the plasma either in contact with the OPL/ONPL (outboard non pumped limiters) alone or with the OPL and the vertical limiters together. Calorimetric measurements provide estimates of the time-integrated balance of the energy flow at the plasma edge. Radiated and charge exchange energy losses are deduced from the inner vessel calorimetry (R=242cm, a=94cm). Conductive/convective losses on the OPL and vertical (top and bottom) limiters are independently measured, as well as the integrated energy flow on the ergodic divertors. The calorimetric results, the bolometric measurements of the radiated power and the Ohmic power estimates, are indicated. The central line density from interferometric measurement for the two successive shots, with the ONPL and with the OPL, are given

Beam-intensity limitations in linear accelerators

International Nuclear Information System (INIS)

Jameson, R.A.

1981-01-01

Recent demand for high-intensity beams of various particles has renewed interest in the investigation of beam current and beam quality limits in linear RF and induction accelerators and beam-transport channels. Previous theoretical work is reviewed, and new work on beam matching and stability is outlined. There is a real need for extending the theory to handle the time evolution of beam emittance; some present work toward this goal is described. The role of physical constraints in channel intensity limitation is emphasized. Work on optimizing channel performance, particularly at low particle velocities, has resulted in major technological advances. The opportunities for combining such channels into arrays are discussed. 50 references

Partnerships – Limited partnerships and limited liability limited partnerships

OpenAIRE

Henning, Johan J.

2000-01-01

Consideration of the Limited Liability Partnership Act 2000 which introduced a new corporate entity, carrying the designations “partnership” and “limited” which allow members to limit their liability whilst organising themselves internally as a partnership. Article by Professor Johan Henning (Director of the Centre for Corporate Law and Practice, IALS and Dean of the Faculty of Law, University of the Free State, South Africa). Published in Amicus Curiae - Journal of the Institute of Advanced ...

The limitation and modification of flux-limited diffusion theory

International Nuclear Information System (INIS)

Liu Chengan; Huang Wenkai

1986-01-01

The limitation of various typical flux-limited diffusion theory and advantages of asymptotic diffusion theory with time absorption constant are analyzed and compared. The conclusions are as following: Though the flux-limited problem in neutron diffusion theory are theoretically solved by derived flux-limited diffusion equation, it's going too far to limit flux due to the inappropriate assumption in deriving flux-limited diffusion equation. The asymptotic diffusion theory with time absorption constant has eliminated the above-mentioned limitation, and it is more accurate than flux-limited diffusion theory in describing neutron transport problem

An estimation of tritium inventory limits for the E-Area vaults

International Nuclear Information System (INIS)

Yu, A.D.; Cook, J.R.

1991-01-01

At the request of Waste Management, Interim Waste Technology has conducted a modeling study to estimate the tritium inventory limits for the E-Area vaults. These inventory limits are based on the groundwater impact of the planned waste disposal. The tritium inventory limit for an Intermediate Level Tritium Vault (ILTV) is estimated to be 400,000 Curies with a 100 year storage period. During this period, it is assumed that the ILTV will be vented, any leachate will be extracted, and its performance will be carefully monitored. The tritium inventory limits for a Low Activity Waste Vault (LAWV) and an Intermediate Level Non-Tritium Vault (ILNTV) are estimated to be 15,000 and 11,000 Curies, respectively. Venting and leachate extraction were not assumed necessary. These operational alternatives would further enhance the performance of these vaults. These limits are significantly higher than the forecasted maximum tritium inventories for the vaults. Details of the modeling study are described in the attached report

Effects of line dancing on physical function and perceived limitation in older adults with self-reported mobility limitations.

Science.gov (United States)

Bennett, Crystal G; Hackney, Madeleine E

2018-06-01

Older adults with mobility limitations are at greater risk for aging-related declines in physical function. Line dancing is a popular form of exercise that can be modified, and is thus feasible for older adults with mobility limitations. The purpose of this study was to assess the effects of 8 weeks of line dancing on balance, muscle strength, lower extremity function, endurance, gait speed, and perceived mobility limitations. An experimental design randomly assigned older adults to either an 8-week line dancing or usual care group. The convenience sample consisted of 23 participants with mobility limitations (age range: 65-93 years). The intervention used simple routines from novice line dance classes. At baseline and at 8 weeks, balance, knee muscle strength, lower extremity function, endurance, gait speed, and mobility limitations were measured. ANCOVA tests were conducted on each dependent variable to assess the effects of the intervention over time. Results found significant positive differences for the intervention group in lower extremity function (p dancing significantly improved physical function and reduced self-reported mobility limitations in these individuals. Line dancing could be recommended by clinicians as a potential adjunct therapy that addresses mobility limitations. Implications for Rehabilitation Line dancing may be an alternative exercise for older adults who need modifications due to mobility limitations. Line dancing incorporates cognitive and motor control. Line dancing can be performed alone or in a group setting. Dancing improves balance which can reduce risk of falls.

Core Power Limits For A Lead-Bismuth Natural Circulation Actinide Burner Reactor

Energy Technology Data Exchange (ETDEWEB)

Davis, Cliff Bybee; Kim, D.; Todreas, N. E.; Mujid S. Kazimi

2002-04-01

The Idaho National Engineering and Environmental Laboratory and Massachusetts Institute of Technology are investigating the suitability of lead-bismuth cooled fast reactors for producing low-cost electricity as well as for actinide burning. The design being considered here is a pool type reactor that burns actinides and utilizes natural circulation of the primary coolant, a conventional steam power conversion cycle, and a passive decay heat removal system. Thermal-hydraulic evaluations of the actinide burner reactor were performed to determine allowable core power ratings that maintain cladding temperatures below corrosion-established temperature limits during normal operation and following a loss-of-feedwater transient. An economic evaluation was performed to optimize various design parameters by minimizing capital cost. The transient power limit was initially much more restrictive than the steady-state limit. However, enhancements to the reactor vessel auxiliary cooling system for transient decay heat removal resulted in an increased power limit of 1040 MWt, which was close to the steady-state limit. An economic evaluation was performed to estimate the capital cost of the reactor and its sensitivity to the transient power limit. For the 1040 MWt power level, the capital cost estimate was 49 mills per kWhe based on 1999 dollars.

Performance Analysis of a Power Limited Spectrum Sharing System with TAS/MRC

KAUST Repository

Khan, Fahd Ahmed

2014-02-01

Capacity of the cognitive radio network degrades due to the interference constraint from the primary network. The secondary network capacity can be enhanced in a cost effective way by means of spatial diversity, that can be achieved by adding multiple antennas on the secondary network terminals and performing antenna selection. In this paper, the performance of a multiple-input multiple-output (MIMO) secondary link with transmit antenna selection (TAS) at the transmitter and maximum ratio combining (MRC) at the receiver is analyzed. A peak transmit power constraint at the secondary transmitter is considered in addition to the interference power constraint and two scenarios are considered; 1) the MIMO cognitive system with TAS/MRC (MCS-TM) does not experience interference from the primary network (denote by MCS-TM-NI), and 2) MCS-TM does experience interference from the primary network (denote by MCS-TM-WI). The performance of both MCS-TM-NI and MCS-TM-WI is analyzed and, for a Rayleigh faded channel, closed-form expression for the outage probability is derived. In addition, closed-form expressions of the moment generating function, the symbol error rate and the ergodic capacity are obtained for the MCS-TM-NI. Asymptotic performance analysis of the MCS-TM-NI reveals that TAS/MRC in a MIMO cognitive system achieves a generalized diversity gain equal to the product of the number of transmit and receive antennas. Numerical results are also presented to corroborate the derived analytical results. © 1991-2012 IEEE.

Formation of carbon containing layers on tungsten test limiters

International Nuclear Information System (INIS)

Rubel, M.; Philipps, V.; Huber, A.; Tanabe, T.

1999-01-01

Tungsten test limiters of mushroom shape and a plasma facing area of approximately 100 cm 2 were exposed at the TEXTOR-94 tokamak to a number of deuterium fuelled discharges performed under various operation conditions. Two types of limiters were tested: a sole tungsten limiter and a twin limiter consisting of two halves, one made of tungsten and another of graphite. The exposed surfaces were examined with ion beam analysis methods and laser profilometry. The formation of some deposition zones was observed near the edges of the limiters. The deuterium-to-carbon concentration ratio was in the range from 0.04 to 0.11 and around 0.2 for the sole tungsten and the twin limiter, respectively. Significant amounts of the co-deposited tungsten and silicon atoms were found on the graphite part of the twin limiter indicating the formation of mixed W-C-Si compounds. (orig.)

Correlation of shoulder range of motion limitations at discharge with limitations in activities and participation one year later in persons with spinal cord injury

NARCIS (Netherlands)

Eriks-Hoogland, Inge E.; de Groot, Sonja; Post, Marcel W. M.; van der Woude, Lucas H. V.

Objective: To study the correlation between limited shoulder range of motion in persons with spinal cord injury at discharge and the performance of activities, wheeling performance, transfers and participation one year later. Design: Multicentre prospective cohort study. Subjects: A total of 146

On performance limitations and property correlations of Al-doped ZnO deposited by radio-frequency sputtering

DEFF Research Database (Denmark)

Crovetto, Andrea; Ottsen, Tobias Sand; Stamate, Eugen

2016-01-01

-pressure regime, we find a generalized dependence of the electrical properties, grain size, texture, and Al content on compressive stress, regardless of sputtering pressure or position on the substrate. In a high-pressure regime, a porous microstructure limits the achievable resistivity and causes it to increase......The electrical properties of RF-sputtered Al-doped ZnO are often spatially inhomogeneous and strongly dependent on deposition parameters. In this work, we study the mechanisms that limit the minimum resistivity achievable under different deposition regimes. In a low- and intermediate...... over time as well. The primary cause of inhomogeneity in the electrical properties is identified as energetic particle bombardment. Inhomogeneity in oxygen content is also observed, but its effect on the electrical properties is small and limited to the carrier mobility....

Current limiters

Energy Technology Data Exchange (ETDEWEB)

Loescher, D.H. [Sandia National Labs., Albuquerque, NM (United States). Systems Surety Assessment Dept.; Noren, K. [Univ. of Idaho, Moscow, ID (United States). Dept. of Electrical Engineering

1996-09-01

The current that flows between the electrical test equipment and the nuclear explosive must be limited to safe levels during electrical tests conducted on nuclear explosives at the DOE Pantex facility. The safest way to limit the current is to use batteries that can provide only acceptably low current into a short circuit; unfortunately this is not always possible. When it is not possible, current limiters, along with other design features, are used to limit the current. Three types of current limiters, the fuse blower, the resistor limiter, and the MOSFET-pass-transistor limiters, are used extensively in Pantex test equipment. Detailed failure mode and effects analyses were conducted on these limiters. Two other types of limiters were also analyzed. It was found that there is no best type of limiter that should be used in all applications. The fuse blower has advantages when many circuits must be monitored, a low insertion voltage drop is important, and size and weight must be kept low. However, this limiter has many failure modes that can lead to the loss of over current protection. The resistor limiter is simple and inexpensive, but is normally usable only on circuits for which the nominal current is less than a few tens of milliamperes. The MOSFET limiter can be used on high current circuits, but it has a number of single point failure modes that can lead to a loss of protective action. Because bad component placement or poor wire routing can defeat any limiter, placement and routing must be designed carefully and documented thoroughly.

Skeletal muscle performance and ageing.

Science.gov (United States)

Tieland, Michael; Trouwborst, Inez; Clark, Brian C

2018-02-01

The world population is ageing rapidly. As society ages, the incidence of physical limitations is dramatically increasing, which reduces the quality of life and increases healthcare expenditures. In western society, ~30% of the population over 55 years is confronted with moderate or severe physical limitations. These physical limitations increase the risk of falls, institutionalization, co-morbidity, and premature death. An important cause of physical limitations is the age-related loss of skeletal muscle mass, also referred to as sarcopenia. Emerging evidence, however, clearly shows that the decline in skeletal muscle mass is not the sole contributor to the decline in physical performance. For instance, the loss of muscle strength is also a strong contributor to reduced physical performance in the elderly. In addition, there is ample data to suggest that motor coordination, excitation-contraction coupling, skeletal integrity, and other factors related to the nervous, muscular, and skeletal systems are critically important for physical performance in the elderly. To better understand the loss of skeletal muscle performance with ageing, we aim to provide a broad overview on the underlying mechanisms associated with elderly skeletal muscle performance. We start with a system level discussion and continue with a discussion on the influence of lifestyle, biological, and psychosocial factors on elderly skeletal muscle performance. Developing a broad understanding of the many factors affecting elderly skeletal muscle performance has major implications for scientists, clinicians, and health professionals who are developing therapeutic interventions aiming to enhance muscle function and/or prevent mobility and physical limitations and, as such, support healthy ageing. © 2017 The Authors. Journal of Cachexia, Sarcopenia and Muscle published by John Wiley & Sons Ltd on behalf of the Society on Sarcopenia, Cachexia and Wasting Disorders.

Limited Area Forecasting and Statistical Modelling for Wind Energy Scheduling

DEFF Research Database (Denmark)

Rosgaard, Martin Haubjerg

forecast accuracy for operational wind power scheduling. Numerical weather prediction history and scales of atmospheric motion are summarised, followed by a literature review of limited area wind speed forecasting. Hereafter, the original contribution to research on the topic is outlined. The quality...... control of wind farm data used as forecast reference is described in detail, and a preliminary limited area forecasting study illustrates the aggravation of issues related to numerical orography representation and accurate reference coordinates at ne weather model resolutions. For the o shore and coastal...... sites studied limited area forecasting is found to deteriorate wind speed prediction accuracy, while inland results exhibit a steady forecast performance increase with weather model resolution. Temporal smoothing of wind speed forecasts is shown to improve wind power forecast performance by up to almost...

English Value-Added Measures: Examining the Limitations of School Performance Measurement

Science.gov (United States)

Perry, Thomas

2016-01-01

Value-added "Progress" measures are to be introduced for all English schools in 2016 as "headline" measures of school performance. This move comes despite research highlighting high levels of instability in value-added measures and concerns about the omission of contextual variables in the planned measure. This article studies…

Atterberg Limits Prediction Comparing SVM with ANFIS Model

Directory of Open Access Journals (Sweden)

Mohammad Murtaza Sherzoy

2017-03-01

Full Text Available Support Vector Machine (SVM and Adaptive Neuro-Fuzzy inference Systems (ANFIS both analytical methods are used to predict the values of Atterberg limits, such as the liquid limit, plastic limit and plasticity index. The main objective of this study is to make a comparison between both forecasts (SVM & ANFIS methods. All data of 54 soil samples are used and taken from the area of Peninsular Malaysian and tested for different parameters containing liquid limit, plastic limit, plasticity index and grain size distribution and were. The input parameter used in for this case are the fraction of grain size distribution which are the percentage of silt, clay and sand. The actual and predicted values of Atterberg limit which obtained from the SVM and ANFIS models are compared by using the correlation coefficient R2 and root mean squared error (RMSE value.  The outcome of the study show that the ANFIS model shows higher accuracy than SVM model for the liquid limit (R2 = 0.987, plastic limit (R2 = 0.949 and plastic index (R2 = 0966. RMSE value that obtained for both methods have shown that the ANFIS model has represent the best performance than SVM model to predict the Atterberg Limits as a whole.

Beam-limiting and radiation-limiting interlocks

International Nuclear Information System (INIS)

Macek, R.J.

1996-01-01

This paper reviews several aspects of beam-limiting and radiation- limiting interlocks used for personnel protection at high-intensity accelerators. It is based heavily on the experience at the Los Alamos Neutron Science Center (LANSCE) where instrumentation-based protection is used extensively. Topics include the need for ''active'' protection systems, system requirements, design criteria, and means of achieving and assessing acceptable reliability. The experience with several specific devices (ion chamber-based beam loss interlock, beam current limiter interlock, and neutron radiation interlock) designed and/or deployed to these requirements and criteria is evaluated

5 CFR 551.702 - Time limits.

Science.gov (United States)

2010-01-01

... at any time file a complaint under the child labor provisions of the Act or an FLSA claim challenging... claim concerning his or her entitlement to minimum wage or overtime pay for work performed under the Act... limitations is 3 years. In deciding a claim, a determination must be made as to whether the cause or basis of...

Mass limit for the lightest neutralino

CERN Document Server

Buskulic, D.; Decamp, D.; Ghez, Philippe; Goy, C.; Lees, J.P.; Lucotte, A.; Minard, M.N.; Nief, J.Y.; Odier, P.; Pietrzyk, B.; Casado, M.P.; Chmeissani, M.; Crespo, J.M.; Delfino, M.; Efthymiopoulos, I.; Fernandez, E.; Fernandez-Bosman, M.; Garrido, L.; Juste, A.; Martinez, M.; Orteu, S.; Padilla, C.; Park, I.C.; Pascual, A.; Perlas, J.A.; Riu, I.; Sanchez, F.; Teubert, F.; Colaleo, A.; Creanza, D.; de Palma, M.; Gelao, G.; Girone, M.; Iaselli, G.; Maggi, G.; Maggi, M.; Marinelli, N.; Nuzzo, S.; Ranieri, A.; Raso, G.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Zito, G.; Huang, X.; Lin, J.; Ouyang, Q.; Wang, T.; Xie, Y.; Xu, R.; Xue, S.; Zhang, J.; Zhang, L.; Zhao, W.; Alemany, R.; Bazarko, A.O.; Bright-Thomas, P.; Cattaneo, M.; Comas, P.; Coyle, P.; Drevermann, H.; Forty, R.W.; Frank, M.; Hagelberg, R.; Harvey, John; Janot, P.; Jost, B.; Kneringer, E.; Knobloch, J.; Lehraus, I.; Lutters, G.; Martin, E.B.; Mato, P.; Minten, A.; Miquel, R.; Mir, L.M.; Moneta, L.; Oest, T.; Pacheco, A.; Pusztaszeri, J.F.; Ranjard, F.; Rensing, P.; Rolandi, Gigi; Schlatter, D.; Schmelling, M.; Schmitt, M.; Schneider, O.; Tejessy, W.; Tomalin, I.R.; Venturi, A.; Wachsmuth, H.; Wagner, A.; Ajaltouni, Z.; Barres, A.; Boyer, C.; Falvard, A.; Gay, P.; Guicheney, C.; Henrard, P.; Jousset, J.; Michel, B.; Monteil, S.; Montret, J.C.; Pallin, D.; Perret, P.; Podlyski, F.; Proriol, J.; Rosnet, P.; Rossignol, J.M.; Fearnley, T.; Hansen, J.B.; Hansen, J.D.; Hansen, J.R.; Hansen, P.H.; Nilsson, B.S.; Rensch, B.; Waananen, A.; Kyriakis, A.; Markou, C.; Simopoulou, E.; Vayaki, A.; Zachariadou, K.; Blondel, A.; Brient, J.C.; Rouge, A.; Rumpf, M.; Valassi, A.; Videau, H.; Focardi, E.; Parrini, G.; Corden, M.; Georgiopoulos, C.; Jaffe, D.E.; Antonelli, A.; Bencivenni, G.; Bologna, G.; Bossi, F.; Campana, P.; Capon, G.; Casper, D.; Chiarella, V.; Felici, G.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, G.P.; Passalacqua, L.; Pepe-Altarelli, M.; Curtis, L.; Dorris, S.J.; Halley, A.W.; Knowles, I.G.; Lynch, J.G.; O'Shea, V.; Raine, C.; Reeves, P.; Scarr, J.M.; Smith, K.; Teixeira-Dias, P.; Thompson, A.S.; Thomson, F.; Thorn, S.; Turnbull, R.M.; Becker, U.; Geweniger, C.; Graefe, G.; Hanke, P.; Hansper, G.; Hepp, V.; Kluge, E.E.; Putzer, A.; Schmidt, M.; Sommer, J.; Stenzel, H.; Tittel, K.; Werner, S.; Wunsch, M.; Abbaneo, D.; Beuselinck, R.; Binnie, D.M.; Cameron, W.; Dornan, P.J.; Morawitz, P.; Moutoussi, A.; Nash, J.; Sedgbeer, J.K.; Stacey, A.M.; Williams, M.D.; Dissertori, G.; Girtler, P.; Kuhn, D.; Rudolph, G.; Betteridge, A.P.; Bowdery, C.K.; Colrain, P.; Crawford, G.; Finch, A.J.; Foster, F.; Hughes, G.; Sloan, T.; Whelan, E.P.; Williams, M.I.; Galla, A.; Greene, A.M.; Hoffmann, C.; Jacobs, K.; Kleinknecht, K.; Quast, G.; Renk, B.; Rohne, E.; Sander, H.G.; van Gemmeren, P.; Zeitnitz, C.; Aubert, J.J.; Bencheikh, A.M.; Benchouk, C.; Bonissent, A.; Bujosa, G.; Calvet, D.; Carr, J.; Diaconu, C.; Konstantinidis, N.; Payre, P.; Rousseau, D.; Talby, M.; Sadouki, A.; Thulasidas, M.; Tilquin, A.; Trabelsi, K.; Aleppo, M.; Ragusa, F.; Bauer, C.; Berlich, R.; Blum, W.; Buescher, Volker; Dietl, H.; Dydak, F.; Ganis, G.; Gotzhein, C.; Kroha, H.; Lutjens, G.; Lutz, G.; Manner, W.; Moser, H.G.; Richter, Robert; Rosado-Schlosser, A.; Schael, S.; Settles, R.; Seywerd, H.; St. Denis, Richard Dante; Stenzel, H.; Wiedenmann, W.; Wolf, G.; Boucrot, J.; Callot, O.; Cordier, A.; Davier, M.; Duflot, L.; Grivaz, J.F.; Heusse, P.; Hocker, Andreas; Jacholkowska, A.; Jacquet, M.; Kim, D.W.; Le Diberder, F.; Lefrancois, J.; Lutz, A.M.; Nikolic, Irina; Park, H.J.; Schune, M.H.; Simion, S.; Veillet, J.J.; Videau, I.; Zerwas, D.; Azzurri, P.; Bagliesi, Giuseppe; Batignani, G.; Bettarini, S.; Bozzi, C.; Calderini, G.; Carpinelli, M.; Ciocci, M.A.; Ciulli, V.; Dell'Orso, R.; Fantechi, R.; Ferrante, I.; Giassi, A.; Gregorio, A.; Ligabue, F.; Lusiani, A.; Marrocchesi, P.S.; Messineo, A.; Palla, F.; Rizzo, G.; Sanguinetti, G.; Sciaba, A.; Spagnolo, P.; Steinberger, J.; Tenchini, R.; Tonelli, G.; Vannini, C.; Verdini, P.G.; Walsh, J.; Blair, G.A.; Bryant, L.M.; Cerutti, F.; Chambers, J.T.; Gao, Y.; Green, M.G.; Medcalf, T.; Perrodo, P.; Strong, J.A.; von Wimmersperg-Toeller, J.H.; Botterill, D.R.; Clifft, R.W.; Edgecock, T.R.; Haywood, S.; Maley, P.; Norton, P.R.; Thompson, J.C.; Wright, A.E.; Bloch-Devaux, Brigitte; Colas, P.; Emery, S.; Kozanecki, W.; Lancon, E.; Lemaire, M.C.; Locci, E.; Marx, B.; Perez, P.; Rander, J.; Renardy, J.F.; Roussarie, A.; Schuller, J.P.; Schwindling, J.; Trabelsi, A.; Vallage, B.; Black, S.N.; Dann, J.H.; Johnson, R.P.; Kim, H.Y.; Litke, A.M.; McNeil, M.A.; Taylor, G.; Booth, C.N.; Boswell, R.; Brew, C.A.J.; Cartwright, S.; Combley, F.; Koksal, A.; Letho, M.; Newton, W.M.; Reeve, J.; Thompson, L.F.; Boehrer, Armin; Brandt, S.; Cowan, G.; Grupen, C.; Saraiva, P.; Smolik, L.; Stephan, F.; Apollonio, N.; Bosisio, L.; Della Marina, R.; Giannini, G.; Gobbo, B.; Musolino, G.; Putz, J.; Rothberg, J.; Wasserbaech, S.; Armstrong, S.R.; Elmer, P.; Feng, Z.; Ferguson, D.P.S.; Gao, Y.S.; Gonzales, S.; Grahl, J.; Greening, T.C.; Hayes, O.J.; Hu, H.; McNamara, P.A., III; Nachtman, J.M.; Orejudos, W.; Pan, Y.B.; Saadi, Y.; Scott, I.J.; Walsh, A.M.; Wu, Sau Lan; Wu, X.; Yamartino, J.M.; Zheng, M.; Zobernig, G.

1996-01-01

Indirect limits on the mass of the lightest neutralino are derived from the results of searches for charginos, neutralinos, and sleptons performed with data taken by the ALEPH Collaboration at centre-of-mass energies near the Z peak and at 130 and 136 GeV. Within the context of the Minimal Supersymmetric Standard Model and when $M_{\\tilde\

Chemical reactions as $\\Gamma$-limit of diffusion

NARCIS (Netherlands)

Peletier, M.A.; Savaré, G.; Veneroni, M.

2012-01-01

We study the limit of high activation energy of a special Fokker–Planck equation known as the Kramers–Smoluchowski equation (KS). This equation governs the time evolution of the probability density of a particle performing a Brownian motion under the influence of a chemical potential

Two-fluid limits on stellarator performance: Explanation of three stellarator puzzles and comparison to axisymmetric plasmas

International Nuclear Information System (INIS)

Sugiyama, L.E.; Strauss, H.R.; Park, W.; Fu, G.Y.; Breslau, J.A.; Chen, J.

2005-01-01

The basic two-fluid processes, those related to the nonlinearly self-consistent diamagnetic drifts of the electrons and ions, are shown to have fundamentally different effects on the steady state and beta limits of stellarator configurations, compared to MHD predictions. Nonlinear numerical simulation shows that the ideal MHD ballooning modes and the resistive MHD ballooning and interchange modes at relatively high mode numbers, that set the most severe theoretical limits on beta in stellarators with fixed boundary, are easily stabilized by two-fluid effects at realistic parameters, including finite Larmor radius effects related to the ion diamagnetic drift. Magnetic reconnection at low-order rational magnetic surfaces, on the other hand, is enhanced through the parallel component of the two-fluid electron pressure gradient in Ohm's law. The accelerated reconnection rates may impose the true intrinsic limit on beta in stellarators, as a 'soft' or confinement mediated limit in β e , due to steady confinement degradation in the presence of large magnetic islands. Study of the corresponding axisymmetric configurations shows that the helical component of the stellarator configuration provides an important amplifying factor for these effects. The two-fluid results may explain several previously puzzling experimental observations on stellarator behavior. (author)

Comparison among tomographic reconstruction with limited data

International Nuclear Information System (INIS)

Oliveira, Eric F.; Dantas, Carlos C.; Vasconcelos, Daniel A.A.; Cadiz, Luis F.; Melo, Silvio B.

2011-01-01

Nowadays there is a continuing interest in applying computed tomography (CT) techniques in non-destructive testing and inspection of many industrial products. These applications of CT usually require a differentiated analysis when there are strong limitations in acquiring a sufficiently large amount of projection data. The use of a low number of tomographic data normally degrades the quality of the reconstructed image, highlighting the formation of artifacts and noise. This work investigates the reconstruction methods most commonly used (FBP, ART, SIRT, MART, SMART) and shows the performance of each one in this limited scenario. For this purpose, all methods were implemented and tested with a phantom of uniform density with well-known distribution, with measures of transmission of gamma radiation in a first generation CT scanner. The phantom is a concentric stainless steel tube coupled with a half - cylinder of aluminum. The measurements were made with an highest root mean square error, with the formation of visible artifacts. The artifacts are diminished but still visible in the ART and SIRT techniques, and the best performance was observed with the techniques MART and SMART. The technical superiority of these multiplicative methods is clearly seen in the reconstructed image quality, endorsing their application to situations of limited input data. (author)

Material limitations on the detection limit in refractometry.

Science.gov (United States)

Skafte-Pedersen, Peder; Nunes, Pedro S; Xiao, Sanshui; Mortensen, Niels Asger

2009-01-01

We discuss the detection limit for refractometric sensors relying on high-Q optical cavities and show that the ultimate classical detection limit is given by min {Δn} ≳ η, with n + iη being the complex refractive index of the material under refractometric investigation. Taking finite Q factors and filling fractions into account, the detection limit declines. As an example we discuss the fundamental limits of silicon-based high-Q resonators, such as photonic crystal resonators, for sensing in a bio-liquid environment, such as a water buffer. In the transparency window (λ ≳ 1100 nm) of silicon the detection limit becomes almost independent on the filling fraction, while in the visible, the detection limit depends strongly on the filling fraction because the silicon absorbs strongly.

Tightening Quantum Speed Limits for Almost All States.

Science.gov (United States)

Campaioli, Francesco; Pollock, Felix A; Binder, Felix C; Modi, Kavan

2018-02-09

Conventional quantum speed limits perform poorly for mixed quantum states: They are generally not tight and often significantly underestimate the fastest possible evolution speed. To remedy this, for unitary driving, we derive two quantum speed limits that outperform the traditional bounds for almost all quantum states. Moreover, our bounds are significantly simpler to compute as well as experimentally more accessible. Our bounds have a clear geometric interpretation; they arise from the evaluation of the angle between generalized Bloch vectors.

The effects of limited adventitiectomy on vascular anastomosis: An experimental study in rats.

Science.gov (United States)

Ugurlu, Alper Mete; Basat, Salih Onur; Ceran, Fatih; Ozalp, Burhan; Berkoz, Omer

2017-04-01

Blockages in anastomotic vessels cause complete loss of free tissue transfer and replanted limb. Many studies have been conducted in the last 30 years to solve this problem. There are insufficient studies dealing with the effects of the limited adventitiectomy done before surgery for sympathetic overactivity leading situations. The aim of this experimental study is to reveal the effects of limited adventitiectomy. In this study, limited adventitiectomy was performed in a wide area before surgery, and the effect of this practice on the vessel diameter and anastomosis was investigated. Rapidly growing dilatation and increase in vessel diameter was observed, and dilatation continued in the limited adventitiectomy group. The preoperative performed limited adventitiectomy is a useful preparation for super microsurgery. Especially in clinical practice before the free flap surgery, limited adventitiectomy can be applied if the recipient site is expected to have vascular problems.

‘The engine just started coughing!’ — Limits of physical performance, aging and career continuity in elite endurance sports

DEFF Research Database (Denmark)

Ronkainen, Noora; Ryba, Tatiana; Nesti, Mark

2013-01-01

This research examines male endurance athletes' experience of aging and/or reaching the perceived limits of physical performance. More specifically, the current study aimed to explore how existential meanings attached to these experiences are connected with athletes' decision-making concerning...... career continuity and retirement. Life story interviews were conducted with 10 Finnish runners and/or orienteers aged between 25 and 62 and the data was analyzed with an existential-narrative framework. Four major storylines related to aging were identified: The end of an era, putting things...... the normativity of retirement when unable to improve their results anymore, other athletes demonstrated career continuity and positive aspects in the late career years, such as lack of competitive anxiety, finding perspective and increased enjoyment in running. We suggest that through awareness of alternative...

Bioenergy Sorghum Crop Model Predicts VPD-Limited Transpiration Traits Enhance Biomass Yield in Water-Limited Environments.

Science.gov (United States)

Truong, Sandra K; McCormick, Ryan F; Mullet, John E

2017-01-01

of genotypes with optimized VPD-limited transpiration traits and deployment of these crops in water limited growing environments. The energy sorghum model and VPD-limited transpiration trait implementation are made available to simulate performance in other target environments.

The impact of multi-criteria performance measurement on business performance improvement

Directory of Open Access Journals (Sweden)

Fentahun Moges Kasie

2013-06-01

Full Text Available Purpose: The purpose of this paper is to investigate the relationship between multi-criteria performance measurement (MCPM practice and business performance improvement using the raw data collected from 33 selected manufacturing companies. In addition, it proposes modified MCPM model as an effective approach to improve business performance of manufacturing companies. Design/methodology/approach:Research paper. Primary and secondary data were collected using questionnaire survey, interview and observation of records. The methodology is to evaluate business performances of sampled manufacturing companies and the extent of utilization of crucial non-financial (lagging and non-financial (leading performance measures. The positive correlation between financial business performance and practice of MCPM is clearly shown using Pearson’s correlation coefficient analysis. Findings –This research paper indicates that companies which measure their performance using important financial and non-financial measures achieve better business performance. Even though certain companies are currently using non-financial measures, the researchers have learned that these financial measures were not integrated with each other, financial measures and strategic objectives. Research limitations/implications: The limitation of this paper is that the number of surveyed companies is small to make generalization and they are found in a single country. Further researches which incorporate a large number of companies from various developing nations are suggested to minimize the limitation of this research.Practical Implication: The paper shows that multi-dimensional performance measures with the inclusion of key leading indicator are essential to predict the future environment. But cost-accounting based financial measures are inadequate to do so. These are shown practically using Pearson’s correlation coefficient analysis. Originality/value: The significance of multi

Material Limitations on the Detection Limit in Refractometry

Directory of Open Access Journals (Sweden)

Niels Asger Mortensen

2009-10-01

Full Text Available We discuss the detection limit for refractometric sensors relying on high-Q optical cavities and show that the ultimate classical detection limit is given by min {Δn} ≳ η with n + iη being the complex refractive index of the material under refractometric investigation. Taking finite Q factors and filling fractions into account, the detection limit declines. As an example we discuss the fundamental limits of silicon-based high-Q resonators, such as photonic crystal resonators, for sensing in a bio-liquid environment, such as a water buffer. In the transparency window (λ ≳ 1100 nm of silicon the detection limit becomes almost independent on the filling fraction, while in the visible, the detection limit depends strongly on the filling fraction because the silicon absorbs strongly.

β limit disruptions in the TFTR tokamak

International Nuclear Information System (INIS)

Fredrickson, E.D.; McGuire, K.; Janos, A.; Bell, M.; Budny, R.V.; Bush, C.E.; Manickam, J.; Mynick, H.; Nazikian, R.; Taylor, G.

1994-11-01

A disruptive β limit (β = plasma pressure/magnetic pressure) is observed in high performance plasmas in TFTR. The MHD character of these disruptions differs substantially from the disruptions in high density plasmas (density limit disruptions) on TFTR. The high β disruptions can occur with less than a milliseconds warning in the form of a fast growing precursor. The precursor appears to be an external kink or internal (m,n)=(1,1) kink strongly coupled through finite β effects and toroidal terms to higher m components. It does not have the open-quote cold bubble close-quote structure found in density limit disruptions. There is also no evidence for a change in the internal inductance, i.e., a major reconnection of the flux, at the time of the thermal quench

Quantum Limits of Space-to-Ground Optical Communications

Science.gov (United States)

Hemmati, H.; Dolinar, S.

2012-01-01

For a pure loss channel, the ultimate capacity can be achieved with classical coherent states (i.e., ideal laser light): (1) Capacity-achieving receiver (measurement) is yet to be determined. (2) Heterodyne detection approaches the ultimate capacity at high mean photon numbers. (3) Photon-counting approaches the ultimate capacity at low mean photon numbers. A number of current technology limits drive the achievable performance of free-space communication links. Approaching fundamental limits in the bandwidth-limited regime: (1) Heterodyne detection with high-order coherent-state modulation approaches ultimate limits. SOA improvements to laser phase noise, adaptive optics systems for atmospheric transmission would help. (2) High-order intensity modulation and photon-counting can approach heterodyne detection within approximately a factor of 2. This may have advantages over coherent detection in the presence of turbulence. Approaching fundamental limits in the photon-limited regime (1) Low-duty cycle binary coherent-state modulation (OOK, PPM) approaches ultimate limits. SOA improvements to laser extinction ratio, receiver dark noise, jitter, and blocking would help. (2) In some link geometries (near field links) number-state transmission could improve over coherent-state transmission

Intrinsic Energy Dissipation Limits in Nano and Micromechanical Resonators

Science.gov (United States)

Iyer, Srikanth Subramanian

Resonant microelectromechanical Systems (MEMS) have enabled miniaturization of high-performance inertial sensors, radio-frequency filters, timing references and mass-based chemical sensors. Despite the increasing prevalence of MEMS resonators for these applications, the energy dissipation in these structures is not well-understood. Accurate prediction of the energy loss and the resulting quality factor (Q) has significant design implications because it is directly related to device performance metrics including sensitivity for resonant sensors, bandwidth for radio-frequency filters and phase-noise for timing references. In order to assess the future potential for MEMS resonators it is critically important to evaluate the energy dissipation limits, which will dictate the ultimate performance resonant MEMS devices can achieve. This work focuses on the derivation and evaluation of the intrinsic mechanical energy dissipation limit for single-crystal nano and micromechanical resonators due to anharmonic phonon-phonon scattering in the Akhiezer regime. The energy loss is derived using perturbation theory and the linearized Boltzmann transport equation for phonons, and includes the direction and polarization dependent mode-Gruneisen parameters in order to capture the strain-induced anharmonicity among phonon branches. Evaluation of the quality factor limit reveals that Akhiezer damping, previously thought to depend only on material properties, has a strong dependence on crystal orientation and resonant mode shape. The robust model provides a dissipation limit for all resonant modes including shear-mode vibrations, which have significantly reduced energy loss because dissipative phonon-phonon scattering is restricted to volume-preserving phonon branches, indicating that Lame or wine-glass mode resonators will have the highest upper limit on mechanical efficiency. Finally, the analytical dissipation model is integrated with commercial finite element software in order to

Testing of Liquid Lithium Limiters in CDX-U

International Nuclear Information System (INIS)

Majeski, R.; Kaita, R.; Boaz, M.; Efthimion, P.; Gray, T.; Jones, B.; Hoffman, D.; Kugel, H.; Menard, J.; Munsat, T.; Post-Zwicker, A.; Soukhanovskii, V.; Spaleta, J.; Taylor, G.; Timberlake, J.; Woolley, R.; Zakharov, L.; Finkenthal, M.; Stutman, D.; Antar, G.; Doerner, R.; Luckhardt, S.; Seraydarian, R.; Maingi, R.; Maiorano, M.; Smith, S.; Rodgers, D.

2004-01-01

Part of the development of liquid metals as a first wall or divertor for reactor applications must involve the investigation of plasma-liquid metal interactions in a functioning tokamak. Most of the interest in liquid-metal walls has focused on lithium. Experiments with lithium limiters have now been conducted in the Current Drive Experiment-Upgrade (CDX-U) device at the Princeton Plasma Physics Laboratory. Initial experiments used a liquid-lithium rail limiter (L3) built by the University of California at San Diego. Spectroscopic measurements showed some reduction of impurities in CDX-U plasmas with the L3, compared to discharges with a boron carbide limiter. While no reduction in recycling was observed with the L3, which had a plasma-wet area of approximately 40 cm2, subsequent experiments with a larger area fully toroidal lithium limiter demonstrated significant reductions in both recycling and in impurity levels. Two series of experiments with the toroidal limiter have now be en performed. In each series, the area of exposed, clean lithium was increased, until in the latest experiments the liquid-lithium plasma-facing area was increased to 2000 cm2. Under these conditions, the reduction in recycling required a factor of eight increase in gas fueling in order to maintain the plasma density. The loop voltage required to sustain the plasma current was reduced from 2 V to 0.5 V. This paper summarizes the technical preparations for lithium experiments and the conditioning required to prepare the lithium surface for plasma operations. The mechanical response of the liquid metal to induced currents, especially through contact with the plasma, is discussed. The effect of the lithium-filled toroidal limiter on plasma performance is also briefly described

Testing of Liquid Lithium Limiters in CDX-U

Energy Technology Data Exchange (ETDEWEB)

R. Majeski; R. Kaita; M. Boaz; P. Efthimion; T. Gray; B. Jones; D. Hoffman; H. Kugel; J. Menard; T. Munsat; A. Post-Zwicker; V. Soukhanovskii; J. Spaleta; G. Taylor; J. Timberlake; R. Woolley; L. Zakharov; M. Finkenthal; D. Stutman; G. Antar; R. Doerner; S. Luckhardt; R. Seraydarian; R. Maingi; M. Maiorano; S. Smith; D. Rodgers

2004-07-30

Part of the development of liquid metals as a first wall or divertor for reactor applications must involve the investigation of plasma-liquid metal interactions in a functioning tokamak. Most of the interest in liquid-metal walls has focused on lithium. Experiments with lithium limiters have now been conducted in the Current Drive Experiment-Upgrade (CDX-U) device at the Princeton Plasma Physics Laboratory. Initial experiments used a liquid-lithium rail limiter (L3) built by the University of California at San Diego. Spectroscopic measurements showed some reduction of impurities in CDX-U plasmas with the L3, compared to discharges with a boron carbide limiter. While no reduction in recycling was observed with the L3, which had a plasma-wet area of approximately 40 cm2, subsequent experiments with a larger area fully toroidal lithium limiter demonstrated significant reductions in both recycling and in impurity levels. Two series of experiments with the toroidal limiter have now be en performed. In each series, the area of exposed, clean lithium was increased, until in the latest experiments the liquid-lithium plasma-facing area was increased to 2000 cm2. Under these conditions, the reduction in recycling required a factor of eight increase in gas fueling in order to maintain the plasma density. The loop voltage required to sustain the plasma current was reduced from 2 V to 0.5 V. This paper summarizes the technical preparations for lithium experiments and the conditioning required to prepare the lithium surface for plasma operations. The mechanical response of the liquid metal to induced currents, especially through contact with the plasma, is discussed. The effect of the lithium-filled toroidal limiter on plasma performance is also briefly described.

Testing of liquid lithium limiters in CDX-U

International Nuclear Information System (INIS)

Majeski, R.; Kaita, R.; Boaz, M.; Efthimion, P.; Gray, T.; Jones, B.; Hoffman, D.; Kugel, H.; Menard, J.; Munsat, T.; Post-Zwicker, A.; Spaleta, J.; Taylor, G.; Timberlake, J.; Woolley, R.; Zakharov, L.; Finkenthal, M.; Stutman, D.; Antar, G.; Doerner, R.; Luckhardt, S.; Seraydarian, R.; Maingi, R.; Maiorano, M.; Smith, S.; Rodgers, D.; Soukhanovskii, V.

2004-01-01

Part of the development of liquid metals as a first wall or divertor for reactor applications must involve the investigation of plasma-liquid metal interactions in a functioning tokamak. Most of the interest in liquid metal walls has focused on lithium. Experiments with lithium limiters have now been conducted in the Current Drive Experiment-Upgrade (CDX-U) device at the Princeton Plasma Physics Laboratory. Initial experiments used a liquid lithium rail limiter (L3) built by the University of California at San Diego. Spectroscopic measurements showed some reduction of impurities in CDX-U plasmas with the L3, compared to discharges with a boron carbide limiter. While no reduction in recycling was observed with the L3, which had a plasma-wet area of approximately 40 cm 2 , subsequent experiments with a larger area fully toroidal lithium limiter demonstrated significant reductions in both recycling and in impurity levels. Two series of experiments with the toroidal limiter have now been performed. In each series, the area of exposed, clean lithium was increased, until in the latest experiments, the liquid lithium plasma-facing area was increased to 2000 cm 2 . Under these conditions, the reduction in recycling required a factor of eight increase in gas fueling in order to maintain the plasma density. The loop voltage required to sustain the plasma current was reduced from 2 V to 0.5 V. This paper summarizes the technical preparations for lithium experiments and the conditioning required to prepare the lithium surface for plasma operations. The mechanical response of the liquid metal to induced currents, especially through contact with the plasma, is discussed. The effect of the lithium-filled toroidal limiter on plasma performance is also briefly described

Embracing the quantum limit in silicon computing.

Science.gov (United States)

Morton, John J L; McCamey, Dane R; Eriksson, Mark A; Lyon, Stephen A

2011-11-16

Quantum computers hold the promise of massive performance enhancements across a range of applications, from cryptography and databases to revolutionary scientific simulation tools. Such computers would make use of the same quantum mechanical phenomena that pose limitations on the continued shrinking of conventional information processing devices. Many of the key requirements for quantum computing differ markedly from those of conventional computers. However, silicon, which plays a central part in conventional information processing, has many properties that make it a superb platform around which to build a quantum computer. © 2011 Macmillan Publishers Limited. All rights reserved

Providers with Limited Experience Perform Better in Advanced Life Support with Assistance Using an Interactive Device with an Automated External Defibrillator Linked to a Ventilator.

Science.gov (United States)

Busch, Christian Werner; Qalanawi, Mohammed; Kersten, Jan Felix; Kalwa, Tobias Johannes; Scotti, Norman Alexander; Reip, Wikhart; Doehn, Christoph; Maisch, Stefan; Nitzschke, Rainer

2015-10-01

Medical teams with limited experience in performing advanced life support (ALS) or with a low frequency of cardiopulmonary resuscitation (CPR) while on duty, often have difficulty complying with CPR guidelines. This study evaluated whether the quality of CPR of trained medical students, who served as an example of teams with limited experience in ALS, could be improved with device assistance. The primary outcome was the hands-off time (i.e., the percentage of the entire CPR time without chest compressions). The secondary outcome was seven time intervals, which should be as short as possible, and the quality of ventilations and chest compressions on the mannequin. We compared standard CPR equipment to an interactive device with visual and acoustic instructions for ALS workflow measures to guide briefly trained medical students through the ALS algorithm in a full-scale mannequin simulation study with a randomized crossover study design. The study equipment consisted of an automatic external defibrillator and ventilator that were electronically linked and communicating as a single system. Included were regular medical students in the third to sixth years of medical school of one class who provided written informed consent for voluntary participation and for the analysis of their CPR performance data. No exclusion criteria were applied. For statistical measures of evaluation we used an analysis of variance for crossover trials accounting for treatment effect, sequence effect, and carry-over effect, with adjustment for prior practical experience of the participants. Forty-two medical students participated in 21 CPR sessions, each using the standard and study equipment. Regarding the primary end point, the study equipment reduced the hands-off time from 40.1% (95% confidence interval [CI] 36.9-43.4%) to 35.6% (95% CI 32.4-38.9%, p = 0.031) compared with the standard equipment. Within the prespecified secondary end points, study equipment reduced the time interval until

Technical aspects of the joint JET-ISX-B beryllium limiter experiment

International Nuclear Information System (INIS)

Edmonds, P.H.; Dietz, K.J.; Mioduszewski, P.K.; Watson, R.D.; Emerson, L.C.; Gabbard, W.A.; Goodall, D.; Simpkins, J.E.; Yarber, J.L.

1984-01-01

An experiment has been performed on the Impurity Study Experiment (ISX-B) tokamak to test beryllium as a limiter material. Beryllium is an attractive candidate for a limiter and has been proposed for use in the Joint European Torus (JET) experiment. A temperature-controlled, segmented, beryllium top-rail limiter was located inside the plasma radius described by the existing titanium limiters. An extended set of diagnostics was added for measurement of scrapeoff and limiter parameters. These included visible and infrared monitoring systems, probes, and surface analysis experiments. Tokamak experiments included parameter surveys of both ohmically heated and neutral-beam-heated plasmas and an extended fluence test of the limiter

Limits on the thermal energy release from radioactive wastes in a mined geologic repository

International Nuclear Information System (INIS)

Scott, J.A.

1983-03-01

The theraml energy release of nuclear wastes is a major factor in the design of geologic repositories. Thermal limits need to be placed on various aspets of the geologic waste disposal system to avoid or retard the degradation of repository performance because of increased temperatures. The thermal limits in current use today are summarized in this report. These limits are placed in a hierarchial structure of thermal criteria consistent with the failure mechanism they are trying to prevent. The thermal criteria hierarchy is used to evaluate the thermal performance of a sample repository design. The design consists of disassembled BWR spent fuel, aged 10 years, close packed in a carbon steel canister with 15 cm of crushed salt backfill. The medium is bedded salt. The most-restrictive temperature for this design is the spent-fuel centerline temperature limit of 300 0 C. A sensitivity study on the effects of additional cooling prior to disposal on repository thermal limits and design is performed

40 CFR 401.12 - Law authorizing establishment of effluent limitations guidelines for existing sources, standards...

Science.gov (United States)

2010-07-01

... effluent limitations guidelines for existing sources, standards of performance for new sources and... ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS GENERAL PROVISIONS § 401.12 Law authorizing establishment of effluent limitations guidelines for existing sources, standards of performance...

Effect of High Phytase Inclusion Rates on Performance of Broilers Fed Diets Not Severely Limited in Available Phosphorus

Directory of Open Access Journals (Sweden)

T. T. dos Santos

2013-02-01

Full Text Available Phytate is not only an unavailable source of phosphorus (P for broilers but it also acts as an anti-nutrient, reducing protein and mineral absorption, increasing endogenous losses and reducing broiler performance. The objective of this study was to investigate the anti-nutritional effects of phytate by including high levels of phytase in diets not severely limited in available P. A total of 768 male Arbor Acres broilers were distributed in six treatments of eight replicate pens of 16 birds each consisting of a positive control diet (PC, positive control with 500 FTU/kg phytase, negative control (NC diet with lower available P and calcium (Ca levels and the same NC diet with 500, 1,000 or 1,500 FTU/kg phytase. Body weight gain (BWG, feed intake (FI, feed conversion ratio (FCR and mortality were determined at 21 and 35 d of age while foot ash was determined in four birds per pen at 21 d of age. FI, FCR and foot ash where not affected by the lower mineral diets at 21 d of age nor by the enzyme inclusion but broilers fed lower Ca and available P diets had lower BWG. At 35 d of age no difference was observed between broilers fed the positive or NC diets but broilers fed 500, 1,000 and 1,500 FTU/kg on top of the NC diet had better FCR than broilers fed the positive control diet. When compared to birds fed a diet adequate in P, birds fed the same diet included with 500, 1,000 and 1,500 FTU/kg of phytase in marginally deficient available P and Ca diets had an improvement of performance. These results support the concept that hydrolysing phytate and reducing the anti-nutritional effects of phytate improves bird performance on marginally deficient diets that were not covering the P requirement of birds.

Corrida em piscina funda: limites e possibilidades para o alto desempenho Velocidad en piscina de profundidad: límites y posibilidades para un alto desempeño Deep water running: limits and possibilities for high performance

Directory of Open Access Journals (Sweden)

Leonardo Alexandre Peyré-Tartaruga

2006-10-01

Full Text Available O objetivo deste estudo foi analisar os limites e possibilidades da utilização da corrida em piscina funda no treinamento de corredores de rendimento. Além disso, são discutidas as respostas agudas submáximas, máximas e crônicas, do ponto de vista fisiológico e biomecânico entre a corrida em terra e em piscina funda. As respostas máximas de freqüência cardíaca e consumo de oxigênio são menores no exercício aquático do que na corrida terrestre. Dados experimentais sugerem o uso do treinamento de corrida em piscina funda para corredores de rendimento; contudo, essas evidências são limitadas para treinamentos de até 10 semanas.El objetivo de este estudio ha sido el de analizar los límites y posibilidades de la utilización de carreras de velocidad en piscina de profundidad durante el entrenamiento de velocista de rendimiento. Además de esto, son discutidas las respuestas agudas submáximas, máximas y crónicas, bajo el punto de vista fisiológico y biomecánico entre la carrera en tierra y en piscina profunda. Las respuestas máximas de frecuencia cardíaca y consumo de oxígeno son menores en el ejercicio acuático que en la de tierra. Datos experimentales sugieren el uso de entrenamiento de carrera en piscina profunda para velocistas de rendimiento, sin embargo estas evidencias son limitadas a entrenamientos de hasta 10 semanas.The purpose of this study was to analyze the limits and possibilities of deep water running on training of performance runners. Besides, it has been discussed the submaximal acute, maximal acute and chronical responses, following physiological and biomechanical aspects between running on land and deep water running. Heart rate and oxygen uptake's maximal responses are lower in aquatic exercise than in running on land. Experimental evidences suggest the deep water running training for performance athletes, but these studies are limited in training program until ten weeks.

Density limit experiments on FTU

International Nuclear Information System (INIS)

Pucella, G.; Tudisco, O.; Apicella, M.L.; Apruzzese, G.; Artaserse, G.; Belli, F.; Boncagni, L.; Botrugno, A.; Buratti, P.; Calabrò, G.; Castaldo, C.; Cianfarani, C.; Cocilovo, V.; Dimatteo, L.; Esposito, B.; Frigione, D.; Gabellieri, L.; Giovannozzi, E.; Bin, W.; Granucci, G.

2013-01-01

One of the main problems in tokamak fusion devices concerns the capability to operate at a high plasma density, which is observed to be limited by the appearance of catastrophic events causing loss of plasma confinement. The commonly used empirical scaling law for the density limit is the Greenwald limit, predicting that the maximum achievable line-averaged density along a central chord depends only on the average plasma current density. However, the Greenwald density limit has been exceeded in tokamak experiments in the case of peaked density profiles, indicating that the edge density is the real parameter responsible for the density limit. Recently, it has been shown on the Frascati Tokamak Upgrade (FTU) that the Greenwald density limit is exceeded in gas-fuelled discharges with a high value of the edge safety factor. In order to understand this behaviour, dedicated density limit experiments were performed on FTU, in which the high density domain was explored in a wide range of values of plasma current (I p = 500–900 kA) and toroidal magnetic field (B T = 4–8 T). These experiments confirm the edge nature of the density limit, as a Greenwald-like scaling holds for the maximum achievable line-averaged density along a peripheral chord passing at r/a ≃ 4/5. On the other hand, the maximum achievable line-averaged density along a central chord does not depend on the average plasma current density and essentially depends on the toroidal magnetic field only. This behaviour is explained in terms of density profile peaking in the high density domain, with a peaking factor at the disruption depending on the edge safety factor. The possibility that the MARFE (multifaced asymmetric radiation from the edge) phenomenon is the cause of the peaking has been considered, with the MARFE believed to form a channel for the penetration of the neutral particles into deeper layers of the plasma. Finally, the magnetohydrodynamic (MHD) analysis has shown that also the central line

Limiter discriminator detection of M-ary FSK signals

Science.gov (United States)

Fonseka, John P.

1990-10-01

The performance of limiter discriminator detection of M-ary FSK signals is analyzed at arbitrary modulation indices. It is shown that the error rate performance of limiter discriminator detection can be significantly improved by increasing the modulation index above 1/M. The optimum modulation index that minimizes the overall error probability is determined for the cases M = 2, 4 and 8. The analysis is carried out for wideband and bandlimited channels with Gaussian and second-order Butterworth filters. It is shown that the optimum modulation index depends on the signal/noise ratio (SNR), in a wideband channel, and on both SNR and time-bandwidth product in a bandlimited channel. Finally, it is shown that the optimum sampling instance in presence of a nonzero phase IF filter can be approximately determined by using only the worst case symbol pattern.

Material Limitations on the Detection Limit in Refractometry

OpenAIRE

Skafte-Pedersen, Peder; Nunes, Pedro S.; Xiao, Sanshui; Mortensen, Niels Asger

2009-01-01

We discuss the detection limit for refractometric sensors relying on high-Q optical cavities and show that the ultimate classical detection limit is given by min {Δn} ≳ η with n + iη being the complex refractive index of the material under refractometric investigation. Taking finite Q factors and filling fractions into account, the detection limit declines. As an example we discuss the fundamental limits of silicon-based high-Q resonators, such as photonic crystal resonators, for sensing in a...

Influence of gas mixture and primary ionization on the performance of limit streamer mode tubes

International Nuclear Information System (INIS)

An Jigang; Anderson, K.J.; Merritt, F.S.; Oreglia, M.; Pilcher, J.E.; Possoz, A.; Schappert, W.; Chicago Univ., IL

1988-01-01

We report a study of the dependence of limited streamer mode operation on gas composition. Results are given for the plateau onset voltage, plateau length, charge versus voltage, charge spectra and pulse width for various fractions of (Ar, CO 2 , pentane) and (Ar, isobutane). In addition, a series of argon-free strong quenching gas mixtures has been studied which have very attractive characteristics. Chamber lifetime tests for these are also reported. As part of a study of the nature of the limited streamer mode mechanism, the response to X-rays and minimum ionizing particles are compared and differences noted. The character of the primary ionization is found to have a clear effect on the chamber response even in the streamer region. (orig.)

The biotin repressor: modulation of allostery by corepressor analogs.

Science.gov (United States)

Brown, Patrick H; Cronan, John E; Grøtli, Morten; Beckett, Dorothy

2004-04-02

The Escherichia coli biotin repressor functions in biotin retention and regulation of biotin biosynthesis. Biotin retention is accomplished via the two-step biotinylation of the biotin-dependent enzyme, acetyl-CoA carboxylase. In the first step of this reaction the substrates biotin and ATP are utilized in synthesis of the activated biotin, biotinyl-5'-AMP, while in the second step this activated biotin is transferred to a unique lysine residue of the biotin carboxyl carrier protein subunit of the carboxylase. Regulation of biotin biosynthesis is accomplished through binding of the repressor to the transcription control region of the biotin biosynthetic operon. The adenylated or activated biotin functions as the corepressor in this DNA binding process. The activated biotin is a mixed anhydride and thus labile. In efforts to develop tools for structural and thermodynamic studies of the biotin regulatory interactions, two analogs of the adenylate, a sulfamoyl derivative and an ester derivative, have been synthesized and functionally characterized. Results of fluorescence measurements indicate that both analogs bind with high affinity to the repressor and that both are inactive in biotin transfer to the acceptor protein. Functional studies of their corepressor properties indicate that while the sulfamoyl is a weak allosteric activator, the ester closely mimics the physiological corepressor in activation of assembly of the transcription repression complex. Results of these studies also provide further insight into the allosteric mechanism of the biotin repressor.

CYP2E1 Metabolism of Styrene Involves Allostery

Science.gov (United States)

Hartman, Jessica H.; Boysen, Gunnar

2012-01-01

We are the first to report allosterism during styrene oxidation by recombinant CYP2E1 and human liver microsomes. At low styrene concentrations, oxidation is inefficient because of weak binding to CYP2E1 (Ks = 830 μM). A second styrene molecule then binds CYP2E1 with higher affinity (Kss = 110 μM) and significantly improves oxidation to achieve a kcat of 6.3 nmol · min−1 · nmol CYP2E1−1. The transition between these metabolic cycles coincides with reported styrene concentrations in blood from exposed workers; thus, this CYP2E1 mechanism may be relevant in vivo. Scaled modeling of the in vitro-positive allosteric mechanism for styrene metabolism to its in vivo clearance led to significant deviations from the traditional model based on Michaelis-Menten kinetics. Low styrene levels were notably much less toxic than generally assumed. We interrogated the allosteric mechanism using the CYP2E1-specific inhibitor and drug 4-methylpyrazole, which we have shown binds two CYP2E1 sites. From the current studies, styrene was a positive allosteric effector on 4-methylpyrazole binding, based on a 10-fold increase in 4-methylpyrazole binding affinity from Ki 0.51 to Ksi 0.043 μM. The inhibitor was a negative allosteric effector on styrene oxidation, because kcat decreased 6-fold to 0.98 nmol · min−1 · nmol CYP2E1−1. Consequently, mixtures of styrene and other molecules can induce allosteric effects on binding and metabolism by CYP2E1 and thus mitigate the efficiency of their metabolism and corresponding effects on human health. Taken together, our elucidation of mechanisms for these allosteric reactions provides a powerful tool for further investigating the complexities of CYP2E1 metabolism of drugs and pollutants. PMID:22807108

A "Smart" Force-Limiting Instrument for Microsurgery: Laboratory and In Vivo Validation.

Directory of Open Access Journals (Sweden)

Hani J Marcus

Full Text Available Residents are required to learn a multitude of skills during their microsurgical training. One such skill is the judicious application of force when handling delicate tissue. An instrument has been developed that indicates to the surgeon when a force threshold has been exceeded by providing vibrotactile feedback. The objective of this study was to validate the use of this "smart" force-limiting instrument for microsurgery. A laboratory and an in vivo experiment were performed to evaluate the force-limiting instrument. In the laboratory experiment, twelve novice surgeons were randomly allocated to use either the force-limiting instrument or a standard instrument. Surgeons were then asked to perform microsurgical dissection in a model. In the in vivo experiment, an intermediate surgeon performed microsurgical dissection in a stepwise fashion, alternating every 30 seconds between use of the force-limiting instrument and a standard instrument. The primary outcomes were the forces exerted and the OSATS scores. In the laboratory experiment, the maximal forces exerted by novices using the force-limiting instrument were significantly less than using a standard instrument, and were comparable to intermediate and expert surgeons (0.637N versus 4.576N; p = 0.007. In the in vivo experiment, the maximal forces exerted with the force-limiting instrument were also significantly less than with a standard instrument (0.441N versus 0.742N; p 0.1. In conclusion, the development and use of this force-limiting instrument in a clinical setting may improve patient safety.

Optical limiting study of C60 doped (dimethylandicarboxylate) /poly (ethylacetylenecarboxy)polymer

International Nuclear Information System (INIS)

Zidan, M.D.; Allaf, A.W.

2011-10-01

The optical limiting action of poly(dimethylacetylendicarboxylate) polymer and poly(ethylacetylendicarboxylate) polymer doped with fullerene C 6 0 has been investigated under irradiation with 10 ns laser pulse at 532 nm. The optical limiting measurements were performed at different doping concentrations. The threshold limiting fluence decreased at high doping concentrations, at the same time the optical limiting efficiency has been increased. An explanation based on the combination of two-photon absorption and reverse saturable absorption was proposed for its nonlinear optical absorption behavior. (author)

Rhythmic Interlimb Coordination Impairments and the Risk for Developing Mobility Limitations.

Science.gov (United States)

James, Eric G; Leveille, Suzanne G; Hausdorff, Jeffrey M; Travison, Thomas; Kennedy, David N; Tucker, Katherine L; Al Snih, Soham; Markides, Kyriakos S; Bean, Jonathan F

2017-08-01

The identification of novel rehabilitative impairments that are risk factors for mobility limitations may improve their prevention and treatment among older adults. We tested the hypothesis that impaired rhythmic interlimb ankle and shoulder coordination are risk factors for subsequent mobility limitations among older adults. We conducted a 1-year prospective cohort study of community-dwelling older adults (N = 99) aged 67 years and older who did not have mobility limitations (Short Physical Performance Battery score > 9) at baseline. Participants performed antiphase coordination of the right and left ankles or shoulders while paced by an auditory metronome. Using multivariable logistic regression, we determined odds ratios (ORs) for mobility limitations at 1-year follow-up as a function of coordination variability and asymmetry. After adjusting for age, sex, body mass index, Mini-Mental State Examination score, number of chronic conditions, and baseline Short Physical Performance Battery score, ORs were significant for developing mobility limitations based on a 1 SD difference in the variability of ankle (OR = 1.88; 95% confidence interval [CI]: 1.16-3.05) and shoulder (OR = 1.96; 95% CI: 1.17-3.29) coordination. ORs were significant for asymmetry of shoulder (OR = 2.11; 95% CI: 1.25-3.57), but not ankle (OR = 0.95; 95% CI: 0.59-1.55) coordination. Similar results were found in unadjusted analyses. The results support our hypothesis that impaired interlimb ankle and shoulder coordination are risk factors for the development of mobility limitations. Future work is needed to further examine the peripheral and central mechanisms underlying this relationship and to test whether enhancing coordination alters mobility limitations. © The Author 2016. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Numerical Limit Analysis of Reinforced Concrete Structures

DEFF Research Database (Denmark)

Larsen, Kasper Paaske

For more than half a century, limit state analysis based on the extremum principles have been used to assess the load bearing capacity of reinforced concrete structures. Extensi- ve research within the field has lead to several techniques for performing such analysis manually. While these manual...... methods provide engineers with valuable tools for limit sta- te analysis, their application becomes difficult with increased structural complexity. The main challenge is to solve the optimization problem posed by the extremum principles. This thesis is a study of how numerical methods can be used to solve...... limit state analysis problems. The work focuses on determination of the load bearing capacity of reinforced concrete structures by employing the lower bound theorem and a finite element method using equilibrium elements is developed. The recent year’s development within the field of convex optimization...

Primary system temperature limits and transient mitigation

Energy Technology Data Exchange (ETDEWEB)

Drucker, G.S.; Bost, D.S.

1978-10-03

Results of a study to determine the limiting temperature conditions in a large reactor system are presented. The study considers a sodium-cooled breeder reactor system having a loop-type primary system configuration. A temperature range of 930 to 1050/sup 0/F in reactor outlet temperature is covered. Significant findings were that the use of the materials for the 930/sup 0/F reference design, i.e., a core material of 20% cold-worked 316 stainless steel, a primary piping material of 316SS, and a steam generator material of unstabilized 2-1/4 Cr - 1 Mo resulted in limiting conditions in component performance at the higher temperatures. Means to circumvent these limits through the use of alternate materials, mitigation of thermal transients, and/or design changes are presented. The economic incentive to make some materials changes is also presented.

Neutral iron densities in front of a reference limiter in TEXTOR

International Nuclear Information System (INIS)

Schweer, B.; Bay, H.L.

1983-09-01

Preliminary measurements of the time and space resolved densities of neutral iron in front of a reference limiter in Textor have been performed using laser induced fluorescence. The limiter was made of stainless steel (SS 316) and formed as a half sphere, 10 cm in diameter. Neutral iron densities up to 5 x 10 9 atoms/cm 3 were found. The detection limit was below 10 7 atoms/cm 3 . (orig.)

Shell Canada Limited 1996 annual report

International Nuclear Information System (INIS)

1996-01-01

Shell Canada Resources Limited is one of Canada's largest producers of crude oil, natural gas, natural gas liquids, sulphur and bitumen. This annual report for 1996 presented a summary review of operations and a summary of the Company's audited consolidated financial statements. Overall, the resources business delivered exceptional results in 1996. The oil products and chemicals businesses did not perform as well as expected. This less than satisfactory performance of the oil products and chemicals divisions of the the Company is reflected in the financial returns which, after excluding revenues from asset sales, left operating earnings $ 59 million below those of 1996. tabs., figs

Beta limits in EBT and their implications for a reactor

International Nuclear Information System (INIS)

Uckan, N.A.; Spong, D.A.; Nelson, D.B.

1982-01-01

Theoretical models indicate limits on core beta ranging from a few percent to 10-20% depending on the models and/or assumptions. Some of the parameters that enter into these beta limits are: the ratio of the ring radial scale length to the average radius of curvature, epsilon=Δ/Rsub(c); the ratio of the cold to the hot plasma density, fsub(R)=nsub(cold)/nsub(hot); the ratios of the hot electron drift frequency to the ion cyclotron frequency, ωsub(dh)/ωsub(ci), and to the drift Alfven frequency ωsub(dh)/kVsub(A); the ratio of the ring electron temperature to the core ion temperature, Tsub(R)/Tsub(i); the ring beta βsub(R); etc. Because of uncertainties in extrapolating results of simplifield models to a reactor plasma, the above parameters that influence the beta limits cannot be determined accurately at the present time. Also, reasonable changes within the models and/or assumptions are seen to affect the core beta limits by almost an order of magnitude. Hence, at the present, these limits cannot be used as a rigid (and reliable) requirement for ELMO Bumpy Torus (EBT) reactor engineering considerations. However, sensitivity studies can be carried out to determine the boundaries of the operating regime and to demonstrate the effects of various modes, assumptions, and models on reactor performance (Q value). First the modes believed to limit the core β and ring plasma performance are discussed, and the simplifications and/or assumptions involved in deriving these limits are highlighted. Then, the implications of these limits for a reactor are given. (author)

Removing the current-limit of vertical organic field effect transistors

Science.gov (United States)

Sheleg, Gil; Greenman, Michael; Lussem, Bjorn; Tessler, Nir

2017-11-01

The reported Vertical Organic Field Effect Transistors (VOFETs) show either superior current and switching speeds or well-behaved transistor performance, especially saturation in the output characteristics. Through the study of the relationship between the device architecture or dimensions and the device performance, we find that achieving a saturation regime in the output characteristics requires that the device operates in the injection limited regime. In current structures, the existence of the injection limited regime depends on the source's injection barrier as well as on the buried semiconductor layer thickness. To overcome the injection limit imposed by the necessity of injection barrier, we suggest a new architecture to realize VOFETs. This architecture shows better gate control and is independent of the injection barrier at the source, thus allowing for several A cm-2 for a semiconductor having a mobility value of 0.1 cm2 V-1 s-1.

Dissolved Concentration Limits of Radioactive Elements

Energy Technology Data Exchange (ETDEWEB)

Y. Chen; E.R. Thomas; F.J. Pearson; P.L. Cloke; T.L. Steinborn; P.V. Brady

2003-06-20

The purpose of this study is to evaluate dissolved concentration limits (also referred to as solubility limits) of radioactive elements under possible repository conditions, based on geochemical modeling calculations using geochemical modeling tools, thermodynamic databases, and measurements made in laboratory experiments and field work. The scope of this modeling activity is to predict dissolved concentrations or solubility limits for 14 radioactive elements (actinium, americium, carbon, cesium, iodine, lead, neptunium, plutonium, protactinium, radium, strontium, technetium, thorium, and uranium), which are important to calculated dose. Model outputs are mainly in the form of look-up tables plus one or more uncertainty terms. The rest are either in the form of distributions or single values. The results of this analysis are fundamental inputs for total system performance assessment to constrain the release of these elements from waste packages and the engineered barrier system. Solubilities of plutonium, neptunium, uranium, americium, actinium, thorium, protactinium, lead, and radium have been re-evaluated using the newly updated thermodynamic database (Data0.ymp.R2). For all of the actinides, identical modeling approaches and consistent environmental conditions were used to develop solubility models in this revision. These models cover broad ranges of environmental conditions so that they are applicable to both waste packages and the invert. Uncertainties from thermodynamic data, water chemistry, temperature variation, activity coefficients, and selection of solubility controlling phase have been quantified or otherwise addressed. Moreover, a new blended plutonium solubility model has been developed in this revision, which gives a mean solubility that is three orders of magnitude lower than the plutonium solubility model used for the Total System Performance Assessment for the Site Recommendation. Two alternative neptunium solubility models have also been

Dissolved Concentration Limits of Radioactive Elements

International Nuclear Information System (INIS)

Y. Chen; E.R. Thomas; F.J. Pearson; P.L. Cloke; T.L. Steinborn; P.V. Brady

2003-01-01

The purpose of this study is to evaluate dissolved concentration limits (also referred to as solubility limits) of radioactive elements under possible repository conditions, based on geochemical modeling calculations using geochemical modeling tools, thermodynamic databases, and measurements made in laboratory experiments and field work. The scope of this modeling activity is to predict dissolved concentrations or solubility limits for 14 radioactive elements (actinium, americium, carbon, cesium, iodine, lead, neptunium, plutonium, protactinium, radium, strontium, technetium, thorium, and uranium), which are important to calculated dose. Model outputs are mainly in the form of look-up tables plus one or more uncertainty terms. The rest are either in the form of distributions or single values. The results of this analysis are fundamental inputs for total system performance assessment to constrain the release of these elements from waste packages and the engineered barrier system. Solubilities of plutonium, neptunium, uranium, americium, actinium, thorium, protactinium, lead, and radium have been re-evaluated using the newly updated thermodynamic database (Data0.ymp.R2). For all of the actinides, identical modeling approaches and consistent environmental conditions were used to develop solubility models in this revision. These models cover broad ranges of environmental conditions so that they are applicable to both waste packages and the invert. Uncertainties from thermodynamic data, water chemistry, temperature variation, activity coefficients, and selection of solubility controlling phase have been quantified or otherwise addressed. Moreover, a new blended plutonium solubility model has been developed in this revision, which gives a mean solubility that is three orders of magnitude lower than the plutonium solubility model used for the Total System Performance Assessment for the Site Recommendation. Two alternative neptunium solubility models have also been

'The engine just started coughing!' - Limits of physical performance, aging and career continuity in elite endurance sports.

Science.gov (United States)

Ronkainen, Noora J; Ryba, Tatiana V; Nesti, Mark S

2013-12-01

This research examines male endurance athletes' experience of aging and/or reaching the perceived limits of physical performance. More specifically, the current study aimed to explore how existential meanings attached to these experiences are connected with athletes' decision-making concerning career continuity and retirement. Life story interviews were conducted with 10 Finnish runners and/or orienteers aged between 25 and 62 and the data was analyzed with an existential-narrative framework. Four major storylines related to aging were identified: The end of an era, putting things in perspective, the attitude has to change and winning was never the only motive. Our results suggest that endurance athletes possess diverse ways of bringing meaning to the experience of aging, both confirming and resisting the dominant cultural narrative of decline. While three athletes' stories confirmed the normativity of retirement when unable to improve their results anymore, other athletes demonstrated career continuity and positive aspects in the late career years, such as lack of competitive anxiety, finding perspective and increased enjoyment in running. We suggest that through awareness of alternative narratives, sport psychology consultants may be able to help their clients to explore new meanings in the potentially challenging and beneficial experiences of aging and athletic retirement. © 2013.

Master athletes are extending the limits of human endurance

Directory of Open Access Journals (Sweden)

Romuald Lepers

2016-12-01

Full Text Available The increased participation of master athletes (i.e. > 40 years old in endurance and ultra-endurance events (> 6h duration over the past few decades has been accompanied by an improvement in their performances at a much faster rate than their younger counterparts. Ageing does however result in a decrease in overall endurance performance. Such age-related declines in performance depend upon the modes of locomotion, event duration and gender of the participant. For example, smaller age-related declines in cycling performance than in running and swimming have been documented. The relative stability of gender differences observed across the ages suggests that the age-related declines in physiological function did not differ between males and females. Among the main physiological determinants of endurance performance, the maximal oxygen consumption (VO2max appears to be the parameter that is most altered by age. Exercise economy and the exercise intensity at which a high fraction of VO2max can be sustained (i.e. lactate threshold, seem to decline to a lesser extent with advancing age. The ability to maintain a high exercise-training stimulus with advancing age is emerging as the single most important means of limiting the rate of decline in endurance performance. By constantly extending the limits of (ultra-endurance, master athletes therefore represent an important insight into the ability of humans to maintain physical performance and physiological function with advancing age.

Performance limits of ion extraction systems with non-circular apertures

Energy Technology Data Exchange (ETDEWEB)

Shagayda, A., E-mail: shagayda@gmail.com; Madeev, S. [Keldysh Research Centre, Onezhskaya, 8, 125438 Moscow (Russian Federation)

2016-04-15

A three-dimensional computer simulation is used to determine the perveance limitations of ion extraction systems with non-circular apertures. The objective of the study is to analyze the possibilities to improve mechanical strength of the ion optics made of carbon-carbon composite materials. Non-circular grid apertures are better suited to the physical structure of carbon-carbon composite materials, than conventionally used circular holes in a hexagonal pattern, because they allow a fewer number of cut fibers. However, the slit-type accelerating systems, usually regarded as the main alternative to the conventional ion optics, have an intolerably narrow range of operating perveance values at which there is no direct ion impingement on the acceleration grid. This paper presents results of comparative analysis of a number of different ion optical systems with non-circular apertures and conventional ion optical systems with circular apertures. It has been revealed that a relatively wide perveance range without direct ion impingement may be obtained with apertures shaped as a square with rounded corners. Numerical simulations show that this geometry may have equivalent perveance range as the traditional geometry with circular apertures while being more mechanically robust. In addition, such important characteristics, as the effective transparency for both the ions and the neutral atoms, the height of the potential barrier reflecting the downstream plasma electrons and the angular divergence of the beamlet also can be very close to these parameters for the optics with circular apertures.

Performance limits of ion extraction systems with non-circular apertures.

Science.gov (United States)

Shagayda, A; Madeev, S

2016-04-01

A three-dimensional computer simulation is used to determine the perveance limitations of ion extraction systems with non-circular apertures. The objective of the study is to analyze the possibilities to improve mechanical strength of the ion optics made of carbon-carbon composite materials. Non-circular grid apertures are better suited to the physical structure of carbon-carbon composite materials, than conventionally used circular holes in a hexagonal pattern, because they allow a fewer number of cut fibers. However, the slit-type accelerating systems, usually regarded as the main alternative to the conventional ion optics, have an intolerably narrow range of operating perveance values at which there is no direct ion impingement on the acceleration grid. This paper presents results of comparative analysis of a number of different ion optical systems with non-circular apertures and conventional ion optical systems with circular apertures. It has been revealed that a relatively wide perveance range without direct ion impingement may be obtained with apertures shaped as a square with rounded corners. Numerical simulations show that this geometry may have equivalent perveance range as the traditional geometry with circular apertures while being more mechanically robust. In addition, such important characteristics, as the effective transparency for both the ions and the neutral atoms, the height of the potential barrier reflecting the downstream plasma electrons and the angular divergence of the beamlet also can be very close to these parameters for the optics with circular apertures.

Performance limits of ion extraction systems with non-circular apertures

Science.gov (United States)

Shagayda, A.; Madeev, S.

2016-04-01

A three-dimensional computer simulation is used to determine the perveance limitations of ion extraction systems with non-circular apertures. The objective of the study is to analyze the possibilities to improve mechanical strength of the ion optics made of carbon-carbon composite materials. Non-circular grid apertures are better suited to the physical structure of carbon-carbon composite materials, than conventionally used circular holes in a hexagonal pattern, because they allow a fewer number of cut fibers. However, the slit-type accelerating systems, usually regarded as the main alternative to the conventional ion optics, have an intolerably narrow range of operating perveance values at which there is no direct ion impingement on the acceleration grid. This paper presents results of comparative analysis of a number of different ion optical systems with non-circular apertures and conventional ion optical systems with circular apertures. It has been revealed that a relatively wide perveance range without direct ion impingement may be obtained with apertures shaped as a square with rounded corners. Numerical simulations show that this geometry may have equivalent perveance range as the traditional geometry with circular apertures while being more mechanically robust. In addition, such important characteristics, as the effective transparency for both the ions and the neutral atoms, the height of the potential barrier reflecting the downstream plasma electrons and the angular divergence of the beamlet also can be very close to these parameters for the optics with circular apertures.

Performance limits of ion extraction systems with non-circular apertures

International Nuclear Information System (INIS)

Shagayda, A.; Madeev, S.

2016-01-01

A three-dimensional computer simulation is used to determine the perveance limitations of ion extraction systems with non-circular apertures. The objective of the study is to analyze the possibilities to improve mechanical strength of the ion optics made of carbon-carbon composite materials. Non-circular grid apertures are better suited to the physical structure of carbon-carbon composite materials, than conventionally used circular holes in a hexagonal pattern, because they allow a fewer number of cut fibers. However, the slit-type accelerating systems, usually regarded as the main alternative to the conventional ion optics, have an intolerably narrow range of operating perveance values at which there is no direct ion impingement on the acceleration grid. This paper presents results of comparative analysis of a number of different ion optical systems with non-circular apertures and conventional ion optical systems with circular apertures. It has been revealed that a relatively wide perveance range without direct ion impingement may be obtained with apertures shaped as a square with rounded corners. Numerical simulations show that this geometry may have equivalent perveance range as the traditional geometry with circular apertures while being more mechanically robust. In addition, such important characteristics, as the effective transparency for both the ions and the neutral atoms, the height of the potential barrier reflecting the downstream plasma electrons and the angular divergence of the beamlet also can be very close to these parameters for the optics with circular apertures.

Optical limiting properties of optically active phthalocyanine derivatives

Science.gov (United States)

Wang, Peng; Zhang, Shuang; Wu, Peiji; Ye, Cheng; Liu, Hongwei; Xi, Fu

2001-06-01

The optical limiting properties of four optically active phthalocyanine derivatives in chloroform solutions and epoxy resin thin plates were measured at 532 nm with 10 ns pulses. The excited state absorption cross-section σex and refractive-index cross-section σr were determined with the Z-scan technique. These chromophores possess larger σex than the ground state absorption cross-section σ0, indicating that they are the potential materials for reverse saturable absorption (RSA). The negative σr values of these chromophores add to the thermal contribution, producing a larger defocusing effect, which may be helpful in further enhancing their optical limiting performance. The optical limiting responses of the thin plate samples are stronger than those of the chloroform solutions.

A vented pump limiter for the reversed field pinch RFX

International Nuclear Information System (INIS)

Sonato, P.

1998-01-01

The reversed field pinch (RFP) plasma performance, as in the Tokamak, is strongly correlated with the edge neutral particle control. The drawbacks of the conventional magnetic divertors and throat limiters on the RFP plasma have slackened the application of an active particle control system in existing devices. An advanced solution, based on the idea of the 'vented pump limiter' experimented on Tore Supra, has been conceived for RFX. This type of pump limiter is very attractive for a RFP. In this paper, the design of a 'vented limiter' prototype for RFX is presented. Up to six modules of this limiter can be installed at the equatorial plane of RFX, allowing a particle exhaust efficiency comparable with a divertor or a throat limiter working in a Tokamak. Finally, the optimization of this concept for the next step RFP device is presented. (orig.)

Topological properties of the limited penetrable horizontal visibility graph family

Science.gov (United States)

Wang, Minggang; Vilela, André L. M.; Du, Ruijin; Zhao, Longfeng; Dong, Gaogao; Tian, Lixin; Stanley, H. Eugene

2018-05-01

The limited penetrable horizontal visibility graph algorithm was recently introduced to map time series in complex networks. In this work, we extend this algorithm to create a directed-limited penetrable horizontal visibility graph and an image-limited penetrable horizontal visibility graph. We define two algorithms and provide theoretical results on the topological properties of these graphs associated with different types of real-value series. We perform several numerical simulations to check the accuracy of our theoretical results. Finally, we present an application of the directed-limited penetrable horizontal visibility graph to measure real-value time series irreversibility and an application of the image-limited penetrable horizontal visibility graph that discriminates noise from chaos. We also propose a method to measure the systematic risk using the image-limited penetrable horizontal visibility graph, and the empirical results show the effectiveness of our proposed algorithms.

Audit calculation of the limiting CESSAR feedwater-line-break transient with RELAP5/MOD1

International Nuclear Information System (INIS)

Chung, K.S.; Kennedy, M.F.; Guttmann, J.

1983-01-01

Argonne National Laboratory (ANL) performed a series of audit calculations of the limiting FLB transient presented in Appendix 15B to the CESSAR FSAR, supported by a limited number of additional calculations to investigate the sensitivity of the results (in terms of peak primary reactor system pressure) to break area and reactor trip time. The latter calculations were performed to quantify potential benefits in crediting reactor tip on low steam generator downcomer water level, which occurs earlier than the trip shown in the limiting FSAR transient, which tripped on high pressurizer pressure. These calculations were performed to verify the break spectrum results presented by C-E and to insure that C-E did indeed analyze the limiting transient. All of the ANL calculations were performed with RELAP5/MOD1 (cycle 18) using an input deck developed at ANL from CESSAR plant data provided by C-E. In this paper we compare the results and provide insight into the generic behavior of a Feedwater Line Break transient

Planar concentrators at the étendue limit

Science.gov (United States)

Winston, Roland; Gordon, Jeffrey M.

2005-08-01

Recently proposed aplanatic imaging designs are integrally combined with nonimaging flux boosters to produce an ultra-compact planar dielectric-filled concentrator that performs near the étendue limit. Such optical devices are attractive for high-efficiency multi-junction photovoltaics at high flux, with realistic power generation of 1 W from a 1 mm2 cell.

Proton-proton bremsstrahlung towards the elastic limit

Science.gov (United States)

Mahjour-Shafiei, M.; Amir-Ahmadi, H. R.; Bacelar, J. C. S.; Castelijns, R.; Ermisch, K.; van Garderen, E.; Gašparić, I.; Harakeh, M. N.; Kalantar-Nayestanaki, N.; Kiš, M.; Löhner, H.

2005-05-01

In oder to study proton-proton bremsstrahlung moving towards the elastic limit, a detection system, consisting of Plastic-ball and SALAD, was set up and an experiment at 190 MeV incident beam energy was performed. Here, the experimental setup and the data analysis procedure along with some results obtained in the measurement are discussed.

Proton-proton bremsstrahlung towards the elastic limit

International Nuclear Information System (INIS)

Mahjour-Shafiei, M.; Amir-Ahmadi, H.R.; Bacelar, J.C.S.; Castelijns, R.; Ermisch, K.; Garderen, E. van; Harakeh, M.N.; Kalantar-Nayestanaki, N.; Kis, M.; Loehner, H.; Gasparic, I.

2005-01-01

In oder to study proton-proton bremsstrahlung moving towards the elastic limit, a detection system, consisting of Plastic-ball and SALAD, was set up and an experiment at 190 MeV incident beam energy was performed. Here, the experimental setup and the data analysis procedure along with some results obtained in the measurement are discussed

Automatic Margin Computation for Risk-Limiting Audits

DEFF Research Database (Denmark)

Beckert, Bernhard; Kirsten, Michael; Klebanov, Vladimir

2017-01-01

A risk-limiting audit is a statistical method to create confidence in the correctness of an election result by checking samples of paper ballots. In order to perform an audit, one usually needs to know what the election margin is, i.e., the number of votes that would need to be changed in order...

Limited aperture effects on ultrasonic image reconstruction

International Nuclear Information System (INIS)

Kogan, V.G.; Rose, J.H.

1985-01-01

In the inverse Born approximation the shape of a weak scatterer can be determined from a knowledge of the backscattered ultrasonic amplitude for all directions of incidence and all frequencies. Two questions are considered. First, what information on the scatterer shape is preserved and what is degraded if the scattering data are available only within a limited set of incident directions (limited aperture). This problem is addressed for a spherical weakly scattering uniform flaw. It is shown that the problem of a general uniform ellipsoidal flaw can be reduced to the spherical case by a scale transformation; however, the apertures in these two cases must be related by the same transformation. Second, limited aperture and finite bandwidth Born inversions were performed for strongly scattering flaws (voids and cracks) using numerically generated scattering amplitudes. These inversions were then compared with the weak scattering analytic results, which show many common features

Special Analysis: Revision of Saltstone Vault 4 Disposal Limits (U)

Energy Technology Data Exchange (ETDEWEB)

Cook, J

2005-05-26

New disposal limits have been computed for Vault 4 of the Saltstone Disposal Facility based on several revisions to the models in the existing Performance Assessment and the Special Analysis issued in 2002. The most important changes are the use of a more rigorous groundwater flow and transport model, and consideration of radon emanation. Other revisions include refinement of the aquifer mesh to more accurately model the footprint of the vault, a new plutonium chemistry model accounting for the different transport properties of oxidation states III/IV and V/VI, use of variable infiltration rates to simulate degradation of the closure system, explicit calculation of gaseous releases and consideration of the effects of settlement and seismic activity on the vault structure. The disposal limits have been compared with the projected total inventory expected to be disposed in Vault 4. The resulting sum-of-fractions of the 1000-year disposal limits is 0.2, which indicates that the performance objectives and requirements of DOE 435.1 will not be exceeded. This SA has not altered the conceptual model (i.e., migration of radionuclides from the Saltstone waste form and Vault 4 to the environment via the processes of diffusion and advection) of the Saltstone PA (MMES 1992) nor has it altered the conclusions of the PA (i.e., disposal of the proposed waste in the SDF will meet DOE performance measures). Thus a PA revision is not required and this SA serves to update the disposal limits for Vault 4. In addition, projected doses have been calculated for comparison with the performance objectives laid out in 10 CFR 61. These doses are 0.05 mrem/year to a member of the public and 21.5 mrem/year to an inadvertent intruder in the resident scenario over a 10,000-year time-frame, which demonstrates that the 10 CFR 61 performance objectives will not be exceeded. This SA supplements the Saltstone PA and supersedes the two previous SAs (Cook et al. 2002; Cook and Kaplan 2003).

Determining the Limiting Current Density of Vanadium Redox Flow Batteries

Directory of Open Access Journals (Sweden)

Jen-Yu Chen

2014-09-01

Full Text Available All-vanadium redox flow batteries (VRFBs are used as energy storage systems for intermittent renewable power sources. The performance of VRFBs depends on materials of key components and operating conditions, such as current density, electrolyte flow rate and electrolyte composition. Mass transfer overpotential is affected by the electrolyte flow rate and electrolyte composition, which is related to the limiting current density. In order to investigate the effect of operating conditions on mass transport overpotential, this study established a relationship between the limiting current density and operating conditions. First, electrolyte solutions with different states of charge were prepared and used for a single cell to obtain discharging polarization curves under various operating conditions. The experimental results were then analyzed and are discussed in this paper. Finally, this paper proposes a limiting current density as a function of operating conditions. The result helps predict the effect of operating condition on the cell performance in a mathematical model.

Thermodynamic limit for coherence-limited solar power conversion

Science.gov (United States)

Mashaal, Heylal; Gordon, Jeffrey M.

2014-09-01

The spatial coherence of solar beam radiation is a key constraint in solar rectenna conversion. Here, we present a derivation of the thermodynamic limit for coherence-limited solar power conversion - an expansion of Landsberg's elegant basic bound, originally limited to incoherent converters at maximum flux concentration. First, we generalize Landsberg's work to arbitrary concentration and angular confinement. Then we derive how the values are further lowered for coherence-limited converters. The results do not depend on a particular conversion strategy. As such, they pertain to systems that span geometric to physical optics, as well as classical to quantum physics. Our findings indicate promising potential for solar rectenna conversion.

Aerodynamic Limits on Large Civil Tiltrotor Sizing and Efficiency

Science.gov (United States)

Acree, C W.

2014-01-01

The NASA Large Civil Tiltrotor (2nd generation, or LCTR2) is a useful reference design for technology impact studies. The present paper takes a broad view of technology assessment by examining the extremes of what aerodynamic improvements might hope to accomplish. Performance was analyzed with aerodynamically idealized rotor, wing, and airframe, representing the physical limits of a large tiltrotor. The analysis was repeated with more realistic assumptions, which revealed that increased maximum rotor lift capability is potentially more effective in improving overall vehicle efficiency than higher rotor or wing efficiency. To balance these purely theoretical studies, some practical limitations on airframe layout are also discussed, along with their implications for wing design. Performance of a less efficient but more practical aircraft with non-tilting nacelles is presented.

Limitations of systemic accident analysis methods

Directory of Open Access Journals (Sweden)

Casandra Venera BALAN

2016-12-01

Full Text Available In terms of system theory, the description of complex accidents is not limited to the analysis of the sequence of events / individual conditions, but highlights nonlinear functional characteristics and frames human or technical performance in relation to normal functioning of the system, in safety conditions. Thus, the research of the system entities as a whole is no longer an abstraction of a concrete situation, but an exceeding of the theoretical limits set by analysis based on linear methods. Despite the issues outlined above, the hypothesis that there isn’t a complete method for accident analysis is supported by the nonlinearity of the considered function or restrictions, imposing a broad vision of the elements introduced in the analysis, so it can identify elements corresponding to nominal parameters or trigger factors.

Performance objectives for the Hanford immobilized low-activity waste (ILAW) performance assessment

International Nuclear Information System (INIS)

MANN, F.M.

1999-01-01

Before low-level waste may be disposed of, a performance assessment must be written and then approved by the DOE (DOE 1988a, DOE 1999a). The performance assessment is to determine whether ''reasonable assurance'' exists that the performance objectives of the disposal facility will be met. The DOE requirements for waste disposal (DOE 1988a, DOE 1999a) require (see Appendix B): The protection of public health and safety; and The protection of the environment. Although quantitative limits are sometimes stated (for example, the all-pathways exposure limit is 25 mredyear), usually the requirements are stated in a general nature. Quantitative limits were established by: investigating all potentially applicable regulations as well as interpretations of the review panels which DOE has established to review performance assessments; interacting with program management to establish the additional requirements of the program; and interacting with the public (i.e., the Hanford Advisory Board members; as well as affected Tribal Governments) to understand the values of residents in the Pacific Northwest. Because of space considerations, not all radionuclides and dangerous chemicals are listed in this document. The radionuclides listed here are those which were explicitly treated in the ILAW PA (Mann 1998). The dangerous chemicals listed here are those most often detected in Hanford tank waste as documented in the Regulatory Data Quality Objectives Supporting Tank Waste Remediation System Privatization Project (Wiemers 1998)

Using Mason number to predict MR damper performance from limited test data

Science.gov (United States)

Becnel, Andrew C.; Wereley, Norman M.

2017-05-01

The Mason number can be used to produce a single master curve which relates MR fluid stress versus strain rate behavior across a wide range of shear rates, temperatures, and applied magnetic fields. As applications of MR fluid energy absorbers expand to a variety of industries and operating environments, Mason number analysis offers a path to designing devices with desired performance from a minimal set of preliminary test data. Temperature strongly affects the off-state viscosity of the fluid, as the passive viscous force drops considerably at higher temperatures. Yield stress is not similarly affected, and stays relatively constant with changing temperature. In this study, a small model-scale MR fluid rotary energy absorber is used to measure the temperature correction factor of a commercially-available MR fluid from LORD Corporation. This temperature correction factor is identified from shear stress vs. shear rate data collected at four different temperatures. Measurements of the MR fluid yield stress are also obtained and related to a standard empirical formula. From these two MR fluid properties - temperature-dependent viscosity and yield stress - the temperature-corrected Mason number is shown to predict the force vs. velocity performance of a full-scale rotary MR fluid energy absorber. This analysis technique expands the design space of MR devices to high shear rates and allows for comprehensive predictions of overall performance across a wide range of operating conditions from knowledge only of the yield stress vs. applied magnetic field and a temperature-dependent viscosity correction factor.

Determining passive cooling limits in CPV using an analytical thermal model

Science.gov (United States)

Gualdi, Federico; Arenas, Osvaldo; Vossier, Alexis; Dollet, Alain; Aimez, Vincent; Arès, Richard

2013-09-01

We propose an original thermal analytical model aiming to predict the practical limits of passive cooling systems for high concentration photovoltaic modules. The analytical model is described and validated by comparison with a commercial 3D finite element model. The limiting performances of flat plate cooling systems in natural convection are then derived and discussed.

Extending the Performance of Hybrid NoCs beyond the Limitations of Network Heterogeneity

Directory of Open Access Journals (Sweden)

Michael Opoku Agyeman

2017-04-01

Full Text Available To meet the performance and scalability demands of the fast-paced technological growth towards exascale and big data processing with the performance bottleneck of conventional metal-based interconnects (wireline, alternative interconnect fabrics, such as inhomogeneous three-dimensional integrated network-on-chip (3D NoC and hybrid wired-wireless network-on-chip (WiNoC, have emanated as a cost-effective solution for emerging system-on-chip (SoC design. However, these interconnects trade off optimized performance for cost by restricting the number of area and power hungry 3D routers and wireless nodes. Moreover, the non-uniform distributed traffic in a chip multiprocessor (CMP demands an on-chip communication infrastructure that can avoid congestion under high traffic conditions while possessing minimal pipeline delay at low-load conditions. To this end, in this paper, we propose a low-latency adaptive router with a low-complexity single-cycle bypassing mechanism to alleviate the performance degradation due to the slow 2D routers in such emerging hybrid NoCs. The proposed router transmits a flit using dimension-ordered routing (DoR in the bypass datapath at low-loads. When the output port required for intra-dimension bypassing is not available, the packet is routed adaptively to avoid congestion. The router also has a simplified virtual channel allocation (VA scheme that yields a non-speculative low-latency pipeline. By combining the low-complexity bypassing technique with adaptive routing, the proposed router is able to balance the traffic in hybrid NoCs to achieve low-latency communication under various traffic loads. Simulation shows that the proposed router can reduce applications’ execution time by an average of 16.9% compared to low-latency routers, such as SWIFT. By reducing the latency between 2D routers (or wired nodes and 3D routers (or wireless nodes, the proposed router can improve the performance efficiency in terms of average

Gold nanorods-silicone hybrid material films and their optical limiting property

Science.gov (United States)

Li, Chunfang; Qi, Yanhai; Hao, Xiongwen; Peng, Xue; Li, Dongxiang

2015-10-01

As a kind of new optical limiting materials, gold nanoparticles have optical limiting property owing to their optical nonlinearities induced by surface plasmon resonance (SPR). Gold nanorods (GNRs) possess transversal SPR absorption and tunable longitudinal SPR absorption in the visible and near-infrared region, so they can be used as potential optical limiting materials against tunable laser pulses. In this letter, GNRs were prepared using seed-mediated growth method and surface-modified by silica coating to obtain good dispersion in polydimethylsiloxane prepolymers. Then the silicone rubber films doped with GNRs were prepared after vulcanization, whose optical limiting property and optical nonlinearity were investigated. The silicone rubber samples doped with more GNRs were found to exhibit better optical limiting performance.

Ensenanzas en un gimnasio: an investigation of modeling and verbal rehearsal on the motor performance of Hispanic limited English proficient children.

Science.gov (United States)

Meaney, K S; Edwards, R

1996-03-01

This study investigated the effects of modeling and verbal rehearsal on the motor performance of English-speaking and limited English proficient (LEP) children. Children (N = 64) in 4th-grade classes were randomly assigned to conditions in a 2 x 2 x 2 x 2 (Gender x Primary Language x Model Type x Rehearsal) factorial design. Boys and girls whose primary language was English or Spanish were assigned to either a verbal model or no-model condition as well as to a verbal rehearsal or no-rehearsal condition of the motor skills required to be performed. Analysis of variance revealed a significant Model Type x Primary Language interaction as well as a significant Rehearsal x Primary Language interaction. Follow-up analyses revealed that English-speaking children provided with a verbal rehearsal strategy recalled significantly more skills than English-speaking children in the no-rehearsal condition; for LEP children, there were no differences due to rehearsal. Moreover, LEP children presented with a verbal model recalled significantly more skills than LEP children in the no-model condition; for English-speaking children, there were no differences attributed to model type. These results indicate that effective modeling conditions that are provided with verbal cues in English are related to children's primary language.

Determination of detection limits for a VPD ICPMS method of analysis; Determination des limites de detection d'une methode d'analyse VPD ICPMS

Energy Technology Data Exchange (ETDEWEB)

Badard, M.; Veillerot, M

2007-07-01

This training course report presents the different methods of detection and quantifying of metallic impurities in semiconductors. One of the most precise technique is the collection of metal impurities by vapor phase decomposition (VPD) followed by their analysis by ICPMS (inductively coupled plasma mass spectrometry). The study shows the importance of detection limits in the domain of chemical analysis and the way to determine them for the ICPMS analysis. The results found on detection limits are excellent. Even if the detection limits reached with ICPMS performed after manual or automatic VPD are much higher than detection limits of ICPMS alone, this method remains one of the most sensible for ultra-traces analysis. (J.S.)

Are We Reaching the Limits of Homo sapiens?

Science.gov (United States)

Marck, Adrien; Antero, Juliana; Berthelot, Geoffroy; Saulière, Guillaume; Jancovici, Jean-Marc; Masson-Delmotte, Valérie; Boeuf, Gilles; Spedding, Michael; Le Bourg, Éric; Toussaint, Jean-François

2017-01-01

Echoing scientific and industrial progress, the Twentieth century was an unprecedented period of improvement for human capabilities and performances, with a significant increase in lifespan, adult height, and maximal physiological performance. Analyses of historical data show a major slow down occurring in the most recent years. This triggered large and passionate debates in the academic scene within multiple disciplines; as such an observation could be interpreted as our upper biological limits. Such a new phase of human history may be related to structural and functional limits determined by long term evolutionary constraints, and the interaction between complex systems and their environment. In this interdisciplinary approach, we call into question the validity of subsequent forecasts and projections through innovative and related biomarkers such as sport, lifespan, and height indicators. We set a theoretical framework based on biological and environmental relevance rather than using a typical single-variable forecasting approach. As demonstrated within the article, these new views will have major social, economical, and political implications.

Practical roadmap and limits to nanostructured photovoltaics

Energy Technology Data Exchange (ETDEWEB)

Lunt, Richard R. [Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI 48824 (United States); Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Osedach, Timothy P. [School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138 (United States); Brown, Patrick R. [Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Rowehl, Jill A. [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Bulovic, Vladimir [Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

2011-12-22

The significant research interest in the engineering of photovoltaic (PV) structures at the nanoscale is directed toward enabling reductions in PV module fabrication and installation costs as well as improving cell power conversion efficiency (PCE). With the emergence of a multitude of nanostructured photovoltaic (nano-PV) device architectures, the question has arisen of where both the practical and the fundamental limits of performance reside in these new systems. Here, the former is addressed a posteriori. The specific challenges associated with improving the electrical power conversion efficiency of various nano-PV technologies are discussed and several approaches to reduce their thermal losses beyond the single bandgap limit are reviewed. Critical considerations related to the module lifetime and cost that are unique to nano-PV architectures are also addressed. The analysis suggests that a practical single-junction laboratory power conversion efficiency limit of 17% and a two-cell tandem power conversion efficiency limit of 24% are possible for nano-PVs, which, when combined with operating lifetimes of 10 to 15 years, could position them as a transformational technology for solar energy markets. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

DISSOLVED CONCENTRATION LIMITS OF RADIOACTIVE ELEMENTS

Energy Technology Data Exchange (ETDEWEB)

NA

2004-11-22

The purpose of this study is to evaluate dissolved concentration limits (also referred to as solubility limits) of elements with radioactive isotopes under probable repository conditions, based on geochemical modeling calculations using geochemical modeling tools, thermodynamic databases, field measurements, and laboratory experiments. The scope of this modeling activity is to predict dissolved concentrations or solubility limits for 14 elements with radioactive isotopes (actinium, americium, carbon, cesium, iodine, lead, neptunium, plutonium, protactinium, radium, strontium, technetium, thorium, and uranium) important to calculated dose. Model outputs for uranium, plutonium, neptunium, thorium, americium, and protactinium are in the form of tabulated functions with pH and log (line integral) CO{sub 2} as independent variables, plus one or more uncertainty terms. The solubility limits for the remaining elements are either in the form of distributions or single values. The output data from this report are fundamental inputs for Total System Performance Assessment for the License Application (TSPA-LA) to determine the estimated release of these elements from waste packages and the engineered barrier system. Consistent modeling approaches and environmental conditions were used to develop solubility models for all of the actinides. These models cover broad ranges of environmental conditions so that they are applicable to both waste packages and the invert. Uncertainties from thermodynamic data, water chemistry, temperature variation, and activity coefficients have been quantified or otherwise addressed.

Limits on the transverse phase space density in the Fermilab Booster

International Nuclear Information System (INIS)

Ankenbrandt, C.; Holmes, S.D.

1987-09-01

Recent results on intensity and transverse density limitations in the Fermilab 8-GeV Booster are presented. The evidence suggests that the limits are set by incoherent space-charge effects at low energy. Data are interpreted in terms of the space-charge tune shift and possible means of improving performance further are discussed. 8 refs., 3 figs

Fuel and Core Design Options to Overcome the Heavy Metal Loading Limit and Improve Performance and Safety of Liquid Salt Cooled Reactors

Energy Technology Data Exchange (ETDEWEB)

Petrovic, Bojan [Georgia Inst. of Technology, Atlanta, GA (United States); Maldonado, Ivan [Univ. of Tennessee, Knoxville, TN (United States)

2016-04-14

The research performed in this project addressed the issue of low heavy metal loading and the resulting reduced cycle length with increased refueling frequency, inherent to all FHR designs with solid, non-movable fuel based on TRISO particles. Studies performed here focused on AHTR type of reactor design with plate (“plank”) fuel. Proposal to FY12 NEUP entitled “Fuel and Core Design Options to Overcome the Heavy Metal Loading Limit and Improve Performance and Safety of Liquid Salt Cooled Reactors” was selected for award, and the 3-year project started in August 2012. A 4-month NCE was granted and the project completed on December 31, 2015. The project was performed by Georgia Tech (Prof. Bojan Petrovic, PI) and University of Tennessee (Prof. Ivan Maldonado, Co-PI), with a total funding of $758,000 over 3 years. In addition to two Co-PIs, the project directly engaged 6 graduate students (at doctoral or MS level) and 2 postdoctoral researchers. Additionally, through senior design projects and graduate advanced design projects, another 23 undergraduate and 12 graduate students were exposed to and trained in the salt reactor technology. We see this as one of the important indicators of the project’s success and effectiveness. In the process, 1 journal article was published (with 3 journal articles in preparation), together with 8 peer-reviewed full conference papers, 8 peer-reviewed extended abstracts, as well as 1 doctoral dissertation and 2 master theses. The work included both development of models and methodologies needed to adequately analyze this type of reactor, fuel, and its fuel cycle, as well as extensive analyses and optimization of the fuel and core design.

Fuel and Core Design Options to Overcome the Heavy Metal Loading Limit and Improve Performance and Safety of Liquid Salt Cooled Reactors

International Nuclear Information System (INIS)

Petrovic, Bojan; Maldonado, Ivan

2016-01-01

The research performed in this project addressed the issue of low heavy metal loading and the resulting reduced cycle length with increased refueling frequency, inherent to all FHR designs with solid, non-movable fuel based on TRISO particles. Studies performed here focused on AHTR type of reactor design with plate ('plank') fuel. Proposal to FY12 NEUP entitled 'Fuel and Core Design Options to Overcome the Heavy Metal Loading Limit and Improve Performance and Safety of Liquid Salt Cooled Reactors' was selected for award, and the 3-year project started in August 2012. A 4-month NCE was granted and the project completed on December 31, 2015. The project was performed by Georgia Tech (Prof. Bojan Petrovic, PI) and University of Tennessee (Prof. Ivan Maldonado, Co-PI), with a total funding of $758,000 over 3 years. In addition to two Co-PIs, the project directly engaged 6 graduate students (at doctoral or MS level) and 2 postdoctoral researchers. Additionally, through senior design projects and graduate advanced design projects, another 23 undergraduate and 12 graduate students were exposed to and trained in the salt reactor technology. We see this as one of the important indicators of the project's success and effectiveness. In the process, 1 journal article was published (with 3 journal articles in preparation), together with 8 peer-reviewed full conference papers, 8 peer-reviewed extended abstracts, as well as 1 doctoral dissertation and 2 master theses. The work included both development of models and methodologies needed to adequately analyze this type of reactor, fuel, and its fuel cycle, as well as extensive analyses and optimization of the fuel and core design.

Penser aux/les limites de nos limites

Directory of Open Access Journals (Sweden)

Jacques Lévy

2010-12-01

Full Text Available Le mot « frontière » a beaucoup de succès, dans son sens propre mais plus encore comme métaphore d’une multitude de réalités qui ont à voir avec les limites, c’est-à-dire avec notre propension à découper le monde en objets séparables. Mais on constate une grande indétermination entre concept et métaphore et un usage trop facile de mélanges entre ceux-ci. Il faut donc d’abord admettre que la matérialité n’est qu’une des composantes de notre monde, mais que l’immatériel n’est pas l’irréel, le simulé ou le métaphorique. Après un détour par une théorie des limites et ses limites et une distinction entre le topographique (continu et le topologique (discontinu appliquée à l’intérieur et aux limites d’une aire, deux exemples sont développés qui visent à montrer que, si l’on trouve des frontières, ce n’est pas forcément là où on les attend et que l’appréciation juste de la place des frontières suppose la prise en compte de bien d’autres considérations que la seule limitation volontaire et brutale du franchissement d’une ligne imaginaire tracée au sol.Think about limits and the limits of our limitsThe word “boundary” has been very successful in its literal sense but even more so as a metaphor of a multitude of realities involving limits, that is, with regards to our tendency to divide the world into separable objects. However, one can observe a considerable uncertainty between the concept and the metaphor and an utilisation too easy of various mixtures of them. It becomes necessary therefore to first admit that materiality is only one of the components of our world whilst the immaterial is not unreal, simulated or metaphoric. After a detour consisting of examining a theory of limits and its limits and making the distinction between the topographic (continuous and the topologic (discontinuous applied to the interior and the limits of an area, two examples are developed which aim to

Low power optical limiting studies on nanocrystalline benzimidazole ...

Indian Academy of Sciences (India)

Optical limiting studies were performed using the same laser source and the ... activities.7 However, for the last two decades much attention ... the substrate, to control the number of molecules striking the ..... ESA which is a common behaviour in CW regime. ... urable absorption whereas nonlinear refraction leads to self-.

ICRF power limitation relation to density limit in ASDEX

International Nuclear Information System (INIS)

Ryter, F.

1992-01-01

Launching high ICRF power into ASDEX plasmas required good antenna-plasma coupling. This could be achieved by sufficient electron density in front of the antennas i.e. small antenna-plasma distance (1-2 cm) and moderate to high line-averaged electron density compared to the density window in ASDEX. These are conditions eventually close to the density limit. ICRF heated discharges terminated by plasma disruptions caused by the RF pulse limited the maximum RF power which can be injected into the plasma. The disruptions occurring in these cases have clear phenomenological similarities with those observed in density limit discharges. We show in this paper that the ICRF-power limitation by plasma disruptions in ASDEX was due to reaching the density limit. (orig.)

ICRF power limitation relation to density limit in ASDEX

International Nuclear Information System (INIS)

Ryter, F.

1992-01-01

Launching high ICRF power into ASDEX plasmas required good antenna-plasma coupling. This could be achieved by sufficient electron density in front of the antennas i.e. small antenna-plasma distance (1-2 cm) and moderate to high line-averaged electron density compared to the density window in ASDEX. These are conditions eventually close to the density limit. ICRF heated discharges terminated by plasma disruptions caused by the RF pulse limited the maximum RF power which can be injected into the plasma. The disruptions occurring in these cases have clear phenomenological similarities with those observed in density limit discharges. We show in this paper that the ICRF-power limitation by plasma disruptions in ASDEX was due to reaching the density limit. (author) 3 refs., 3 figs

Time-resolved analysis of nonlinear optical limiting for laser synthesized carbon nanoparticles

Science.gov (United States)

Chen, G. X.; Hong, M. H.

2010-11-01

Nonlinear optical limiting materials have attracted much research interest in recent years. Carbon nanoparticles suspended in liquids show a strong nonlinear optical limiting function. It is important to investigate the nonlinear optical limiting process of carbon nanoparticles for further improving their nonlinear optical limiting performance. In this study, carbon nanoparticles were prepared by laser ablation of a carbon target in tetrahydrofuran (THF). Optical limiting properties of the samples were studied with 532-nm laser light, which is in the most sensitive wavelength band for human eyes. The shape of the laser pulse plays an important role for initializing the nonlinear optical limiting effect. Time-resolved analysis of laser pulses discovered 3 fluence stages of optical limiting. Theoretical simulation indicates that the optical limiting is initialized by a near-field optical enhancement effect.

Impact of steam generator start-up limitations on the performance of a parabolic trough solar power plant

DEFF Research Database (Denmark)

Ferruzza, Davide; Topel, Monika; Laumert, Björn

2018-01-01

typically start-up and shut down every day, so in order to maximize their profitability, it is necessary to increase their flexibility in transient operation and to initiate power generation as rapidly as possible. Two of the key components are the steam generator and steam turbine and the rates at which...... they can reach operational speed are limited by thermo-mechanical constraints. This paper presents an analysis of the effects of the thermal stress limitations of the steam generator and steam turbine on the power plant start-up, and quantifies their impact on the economy of the system. A dynamic model......-driven and peak-load. The results indicate that for steam generator hot start-ups, a 1.5% increase in peak-load electricity production would be achieved by doubling the maximum allowable heating rate of the evaporator. No useful increase would be achieved by increasing the rates beyond a limit of 7–8 K...

Evaluation of a bi-directional aluminum honeycomb impact limiter design

International Nuclear Information System (INIS)

Doman, M.J.

1995-01-01

A 120 Ton shipping cask is being developed for the on-site shipment of dry spent fuel at the Idaho National Engineering Laboratory. Impact limiters were incorporated in the cask design to limit the inertial load of the package and its contents during the hypothetical 9-meter (30-foot) drop accident required by 10CFR71. The design process included: (1) a series of static and dynamic tests to determine the crush characteristics of the bi-directional aluminum honeycomb impact limiter material, (2) the development of an analytical model to predict the cask deceleration force as a function of impact limiter crush, and (3) a series of quarter scale model drop tests to qualify the analytical model. The scale model testing, performed at Sandia National Laboratory in Albuquerque, New Mexico, revealed several design aspects which should be considered in developing bi-directional aluminum honeycomb impact limiters and several other design aspects which should be considered for impact limiter designs in general

Rotor aerodynamic power limits at low tip speed ratio using CFD

International Nuclear Information System (INIS)

Mikkelsen, Robert F; Sarmast, Sasan; Henningson, Dan; Sørensen, Jens N

2014-01-01

When investigating limits of rotor aerodynamic models, the Betz limit serves as a solid marker of an upper limit which no model should be able to exceed. A century ago Joukowsky (1912) proposed a rotor aerodynamic model utilizing a rotating actuator disc with a constant circulation. This model has since then been the subject of much controversy as it predicts a power performance that for all tip speed ratios exceeds the Betz limit and which goes to infinity when the tip speed ratio goes to zero. Recently, it was demonstrated that the Joukowsky model is fully consistent with the inviscid Euler equations and that the apparent inconsistency partly can be explained by the lack of viscous effects (Sprensen and van Kuik [4]). However, even including a term to account for the effect of viscosity at small tip speed ratios, the model still predicts a power yield that exceeds the Betz limit. In the present work we study in detail, using a CFD actuator line model, the flow behavior for rotors at small tip speed ratios. It is shown that the excessive swirl appearing towards the rotor center at small tip speed ratios generates vortex breakdown, causing a recirculating zone in the wake that limits the power yield of the rotor. The appearance of vortex breakdown has a similar effect on the flow behavior as the vortex ring state that usually appears at higher tip speed ratios. Limits to where vortex breakdown might occur with tip speed ratio and rotor loading as parameter are investigated and presented in the paper. The limits found correspond to well-known criterion for vortex breakdown onset for swirling flows in general. By applying a criterion for vortex breakdown in combination with the general momentum theory, the power performance always stays below the Betz limit

System Capacity Limits Introduced by Data Fusion on Cooperative Spectrum Sensing under Correlated Environments

DEFF Research Database (Denmark)

Pratas, Nuno; Marchetti, Nicola; Prasad, Neeli R.

2010-01-01

on cooperative sensing schemes. The analysis is supported by evaluation metrics which accounts for the perceived capacity limits. The analysis is performed along the data fusion chain, comparing several scenarios encompassing different degrees of environment correlation between the cluster nodes, number......Spectrum sensing, the cornerstone of the Cognitive Radio paradigm, has been the focus of intensive research, from which the main conclusion was that its performance can be greatly enhanced through the use of cooperative sensing schemes. Nevertheless, if a proper design of the cooperative scheme...... is not followed, then the use of cooperative schemes will introduce some limitations in the network perceived capacity. In this paper, we analyze the performance of a cooperative spectrum sensing scheme based on Data Fusion, by measuring the perceived capacity limits introduced by the use of Data Fusion...

Modelling, development and optimization of integrated power LDMOS transistor. Performance limits in terms of energy; Modelisation, conception et optimisation de composant de puissance lateral DMOS integre. Etude des limites de performance en energie

Energy Technology Data Exchange (ETDEWEB)

Farenc, D.

1997-12-16

Technologies for Smart Power Integrated Circuits combine into a single chip Bipolar and CMOS transistors, plus power with lateral or vertical DMOS transistors. Complexity which has been increasing dramatically since the mid-80`s has allowed to integrate, into a single monolithic solution, entire systems. This thesis deals with the modelling, conception and test of the power integrated LDMOS transistor. The power LDMOS transistor is used as a switching device. It is characterized by two parameters which are the Specific On-resistance R{sub sp} and the breakdown voltage BV{sub DSS}. The LDMOS transistor developed for the new Smart Power technology exhibits a Specific On-resistance of 200 m{Omega}{sup *}mm{sup 2} and a breakdown voltage of 60 V. This device is dedicated to automotive applications. A reduction of the power device which is achieved with a low Specific On-resistance puts forward new issues such as the maximum Energy capability. When the power device is switched-off on an inductive load, a certain amount of energy is dissipated; if it is beyond a certain limit, the device is destroyed. Our goal is to determine the energy limits which are associated with our new Power integrated LDMOS transistor. (author) 28 refs.

Waste tank characterization sampling limits

International Nuclear Information System (INIS)

Tusler, L.A.

1994-01-01

This document is a result of the Plant Implementation Team Investigation into delayed reporting of the exotherm in Tank 241-T-111 waste samples. The corrective actions identified are to have immediate notification of appropriate Tank Farm Operations Shift Management if analyses with potential safety impact exceed established levels. A procedure, WHC-IP-0842 Section 12.18, ''TWRS Approved Sampling and Data Analysis by Designated Laboratories'' (WHC 1994), has been established to require all tank waste sampling (including core, auger and supernate) and tank vapor samples be performed using this document. This document establishes levels for specified analysis that require notification of the appropriate shift manager. The following categories provide numerical values for analysis that may indicate that a tank is either outside the operating specification or should be evaluated for inclusion on a Watch List. The information given is intended to translate an operating limit such as heat load, expressed in Btu/hour, to an analysis related limit, in this case cesium-137 and strontium-90 concentrations. By using the values provided as safety flags, the analytical laboratory personnel can notify a shift manager that a tank is in potential violation of an operating limit or that a tank should be considered for inclusion on a Watch List. The shift manager can then take appropriate interim measures until a final determination is made by engineering personnel

Comparison between a pumped-limiter and a divertor for the next step machines

International Nuclear Information System (INIS)

Harrison, F.F.A.

1985-01-01

The paper presents a simple description of the physics issues which influence the conceptual design of a pumped-limiter and single-null poloidal divertor in a next step, long burn tokamak of NET/INTOR scale. Predicted performance of the limiter and divertor are compared in regard to localised recycling, sputtering of the plasma collection surfaces, penetration of sputtered impurities into the fusion plasma, surface power loading and exhaust of helium ash. It is concluded that the performance of the divertor is superior and that it can be predicted with a reasonable degree of confidence. The viability of the limiter remains in doubt but the concept cannot be rejected at the present time

Microscopic Investigation of Materials Limitations of Superconducting RF Cavities

Energy Technology Data Exchange (ETDEWEB)

Anlage, Steven [Univ. of Maryland, College Park, MD (United States)

2017-08-04

Our overall goal is to contribute to the understanding of defects that limit the high accelerating gradient performance of Nb SRF cavities. Our approach is to develop a microscopic connection between materials defects and SRF performance. We developed a near-field microwave microscope to establish this connection. The microscope is based on magnetic hard drive write heads, which are designed to create very strong rf magnetic fields in very small volumes on a surface.

Preparation of conjugated poly(ethyl acetylene carboxylate) as optical limiter of laser radiation

International Nuclear Information System (INIS)

Allaf, A. W.; Al-Zier, A.; Al-Naima, D.

2009-03-01

The optical limiting action of poly (ethylacetylene carboxylate) dissolved in dichloroethane were investigated under irradiation with 8 ns laser pulses at 532 nm. The optical limiting measurements were performed at a series of concentrations. The threshold limiting fluence was observed for high concentrations at 5 J/cm 2 with a transmission of about 20 %. No optical limiting action was observed at very low concentration of the prepared polymer in the dichloroethane solvent. The observed data show that poly (ethylacetylene carboxylate) has the potential for the use as optical limiting material for future applications. (author)

Quench limits

International Nuclear Information System (INIS)

Sapinski, M.

2012-01-01

With thirteen beam induced quenches and numerous Machine Development tests, the current knowledge of LHC magnets quench limits still contains a lot of unknowns. Various approaches to determine the quench limits are reviewed and results of the tests are presented. Attempt to reconstruct a coherent picture emerging from these results is taken. The available methods of computation of the quench levels are presented together with dedicated particle shower simulations which are necessary to understand the tests. The future experiments, needed to reach better understanding of quench limits as well as limits for the machine operation are investigated. The possible strategies to set BLM (Beam Loss Monitor) thresholds are discussed. (author)

Generative Models of Conformational Dynamics

Science.gov (United States)

Langmead, Christopher James

2014-01-01

Atomistic simulations of the conformational dynamics of proteins can be performed using either Molecular Dynamics or Monte Carlo procedures. The ensembles of three-dimensional structures produced during simulation can be analyzed in a number of ways to elucidate the thermodynamic and kinetic properties of the system. The goal of this chapter is to review both traditional and emerging methods for learning generative models from atomistic simulation data. Here, the term ‘generative’ refers to a model of the joint probability distribution over the behaviors of the constituent atoms. In the context of molecular modeling, generative models reveal the correlation structure between the atoms, and may be used to predict how the system will respond to structural perturbations. We begin by discussing traditional methods, which produce multivariate Gaussian models. We then discuss GAMELAN (GrAphical Models of Energy LANdscapes), which produces generative models of complex, non-Gaussian conformational dynamics (e.g., allostery, binding, folding, etc) from long timescale simulation data. PMID:24446358

Performance Evaluation Model for Application Layer Firewalls.

Science.gov (United States)

Xuan, Shichang; Yang, Wu; Dong, Hui; Zhang, Jiangchuan

2016-01-01

Application layer firewalls protect the trusted area network against information security risks. However, firewall performance may affect user experience. Therefore, performance analysis plays a significant role in the evaluation of application layer firewalls. This paper presents an analytic model of the application layer firewall, based on a system analysis to evaluate the capability of the firewall. In order to enable users to improve the performance of the application layer firewall with limited resources, resource allocation was evaluated to obtain the optimal resource allocation scheme in terms of throughput, delay, and packet loss rate. The proposed model employs the Erlangian queuing model to analyze the performance parameters of the system with regard to the three layers (network, transport, and application layers). Then, the analysis results of all the layers are combined to obtain the overall system performance indicators. A discrete event simulation method was used to evaluate the proposed model. Finally, limited service desk resources were allocated to obtain the values of the performance indicators under different resource allocation scenarios in order to determine the optimal allocation scheme. Under limited resource allocation, this scheme enables users to maximize the performance of the application layer firewall.

Performance Evaluation Model for Application Layer Firewalls.

Directory of Open Access Journals (Sweden)

Shichang Xuan

Full Text Available Application layer firewalls protect the trusted area network against information security risks. However, firewall performance may affect user experience. Therefore, performance analysis plays a significant role in the evaluation of application layer firewalls. This paper presents an analytic model of the application layer firewall, based on a system analysis to evaluate the capability of the firewall. In order to enable users to improve the performance of the application layer firewall with limited resources, resource allocation was evaluated to obtain the optimal resource allocation scheme in terms of throughput, delay, and packet loss rate. The proposed model employs the Erlangian queuing model to analyze the performance parameters of the system with regard to the three layers (network, transport, and application layers. Then, the analysis results of all the layers are combined to obtain the overall system performance indicators. A discrete event simulation method was used to evaluate the proposed model. Finally, limited service desk resources were allocated to obtain the values of the performance indicators under different resource allocation scenarios in order to determine the optimal allocation scheme. Under limited resource allocation, this scheme enables users to maximize the performance of the application layer firewall.

The limiting current in a one-dimensional situation: Transition from a space charge limited to magnetically limited flow

International Nuclear Information System (INIS)

Kumar, Raghwendra; Biswas, Debabrata

2008-01-01

For a nonrelativistic electron beam propagating in a cylindrical drift tube, it is shown that the limiting current density does not saturate to the electrostatic one-dimensional (1D) estimate with increasing beam radius. Fully electromagnetic particle-in-cell (PIC) simulation studies show that beyond a critical aspect ratio, the limiting current density is lower than the 1D electrostatic prediction. The lowering in the limiting current density is found to be due to the transition from the space charge limited to magnetically limited flow. An adaptation of Alfven's single particle trajectory method is used to estimate the magnetically limited current as well as the critical radius beyond which the flow is magnetically limited in a drift tube. The predictions are found to be in close agreement with PIC simulations

Application of tungsten for plasma limiters in TEXTOR

International Nuclear Information System (INIS)

Tanabe, T.; Wada, M.; Ohgo, T.; Philipps, V.; Rubel, M.; Huber, A.; Seggern, J. von; Ohya, K.; Pospieszczyk, A.; Schweer, B.

2000-01-01

Three different types of W limiters were exposed in the TEXTOR plasma and the response of the plasma and materials performance of the limiters were investigated. - A W bulk limiter operated with preheating above 800 K withstood a plasma heat load of about ∼20 MW/m 2 for a few seconds with some slight surface melting during the highest heat load shot. However, it was severely damaged when operated at around 500 K. - A C/W twin test limiter, half made of bulk W and the other half of graphite (EK-98) gave very useful information on how low- and high-Z materials behave under conditions of simultaneous utilization as PFM such as cross-contamination and the influence of a large mass difference on hydrogen reflection and deposition. - Two sets of main poloidal W limiters made of vacuum vapor sprayed (VPS)-W deposited on graphite (IG-430U) with a Re interlayer could absorb about 60% of the total convection heat and the ohmic plasma with a density as high as 5 x 10 13 cm -3 was sustained. Most of the VPS-W coated limiters tolerated a heat load of ∼20 MW/m 2 . This series of W limiters experiments in TEXTOR has shown that W is applicable as a PFM, if its central accumulation is avoided by NBI and/or ICRH heating. Nevertheless, some concerns still remain, including difficulty of plasma start-up, W behavior in higher temperature plasmas, and materials' selection

Performance Estimation for Lowpass Ternary Filters

Directory of Open Access Journals (Sweden)

Brenton Steele

2003-11-01

Full Text Available Ternary filters have tap values limited to −1, 0, or +1. This restriction in tap values greatly simplifies the multipliers required by the filter, making ternary filters very well suited to hardware implementations. Because they incorporate coarse quantisation, their performance is typically limited by tap quantisation error. This paper derives formulae for estimating the achievable performance of lowpass ternary filters, thereby allowing the number of computationally intensive design iterations to be reduced. Motivated by practical communications systems requirements, the performance measure which is used is the worst-case stopband attenuation.

Dynamic probability control limits for risk-adjusted CUSUM charts based on multiresponses.

Science.gov (United States)

Zhang, Xiang; Loda, Justin B; Woodall, William H

2017-07-20

For a patient who has survived a surgery, there could be several levels of recovery. Thus, it is reasonable to consider more than two outcomes when monitoring surgical outcome quality. The risk-adjusted cumulative sum (CUSUM) chart based on multiresponses has been developed for monitoring a surgical process with three or more outcomes. However, there is a significant effect of varying risk distributions on the in-control performance of the chart when constant control limits are applied. To overcome this disadvantage, we apply the dynamic probability control limits to the risk-adjusted CUSUM charts for multiresponses. The simulation results demonstrate that the in-control performance of the charts with dynamic probability control limits can be controlled for different patient populations because these limits are determined for each specific sequence of patients. Thus, the use of dynamic probability control limits for risk-adjusted CUSUM charts based on multiresponses allows each chart to be designed for the corresponding patient sequence of a surgeon or a hospital and therefore does not require estimating or monitoring the patients' risk distribution. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

Nonlinear dynamics of autonomous vehicles with limits on acceleration

Science.gov (United States)

Davis, L. C.

2014-07-01

The stability of autonomous vehicle platoons with limits on acceleration and deceleration is determined. If the leading-vehicle acceleration remains within the limits, all vehicles in the platoon remain within the limits when the relative-velocity feedback coefficient is equal to the headway time constant [k=1/h]. Furthermore, if the sensitivity α>1/h, no collisions occur. String stability for small perturbations is assumed and the initial condition is taken as the equilibrium state. Other values of k and α that give stability with no collisions are found from simulations. For vehicles with non-negligible mechanical response, simulations indicate that the acceleration-feedback-control gain might have to be dynamically adjusted to obtain optimal performance as the response time changes with engine speed. Stability is demonstrated for some perturbations that cause initial acceleration or deceleration greater than the limits, yet do not cause collisions.

Limit analysis on FRP-strengthened RC members

Directory of Open Access Journals (Sweden)

D. De Domenico

2014-07-01

Full Text Available Reinforced concrete (RC members strengthened with externally bonded fiber-reinforced-polymer (FRP plates are numerically investigated by a plasticity-based limit analysis approach. The key-concept of the present approach is to adopt proper constitutive models for concrete, steel reinforcement bars (re-bars and FRP strengthening plates according to a multi-yield-criteria formulation. This allows the prediction of concrete crushing, steel bars yielding and FRP rupture that may occur at the ultimate limit state. To simulate such limitstate of the analysed elements, two iterative methods performing linear elastic analyses with adaptive elastic parameters and finite elements (FEs description are employed. The peak loads and collapse mechanisms predicted for FRP-plated RC beams are validated by comparison with the corresponding experimental findings.

Has Athletic Performance Reached its Peak?

Science.gov (United States)

Berthelot, Geoffroy; Sedeaud, Adrien; Marck, Adrien; Antero-Jacquemin, Juliana; Schipman, Julien; Saulière, Guillaume; Marc, Andy; Desgorces, François-Denis; Toussaint, Jean-François

2015-09-01

Limits to athletic performance have long been a topic of myth and debate. However, sport performance appears to have reached a state of stagnation in recent years, suggesting that the physical capabilities of humans and other athletic species, such as greyhounds and thoroughbreds, cannot progress indefinitely. Although the ultimate capabilities may be predictable, the exact path for the absolute maximal performance values remains difficult to assess and relies on technical innovations, sport regulation, and other parameters that depend on current societal and economic conditions. The aim of this literature review was to assess the possible plateau of top physical capabilities in various events and detail the historical backgrounds and sociocultural, anthropometrical, and physiological factors influencing the progress and regression of athletic performance. Time series of performances in Olympic disciplines, such as track and field and swimming events, from 1896 to 2012 reveal a major decrease in performance development. Such a saturation effect is simultaneous in greyhound, thoroughbred, and frog performances. The genetic condition, exhaustion of phenotypic pools, economic context, and the depletion of optimal morphological traits contribute to the observed limitation of physical capabilities. Present conditions prevailing, we approach absolute physical limits and endure a continued period of world record scarcity. Optional scenarios for further improvements will mostly depend on sport technology and modification competition rules.

An examination of the flame spread limits in a dual fuel engine

Energy Technology Data Exchange (ETDEWEB)

Badr, O.; Karim, G.A.; Liu, B. [Calgary Univ., Dept. of Mechanical Engineering, Calgary, AB (Canada)

1999-10-01

The performance of a gas-fuelled diesel engine (dual fuel) is examined at light load and an effective threshold limit to the combustion of the gaseous fuel through bulk flame spread is identified. The relationship of such a limit to some of the key operating parameters is then discussed. A comparison between the measured values of the limit with those corresponding to the lower flammability limits of the gaseous fuel when evaluated under the prevailing cylinder conditions during pilot diesel fuel ignition showed similar trends. It is suggested that such a similarity may form a basis for estimating the lean operation limits for duel a fuel combustion in engines. A simple approach for estimating the limiting equivalence ratio for the apparent bulk flame spread limit is described for a methane-fuelled dual fuel engine. (Author)

Electron transport limitation in P3HT:CdSe nanorods hybrid solar cells.

Science.gov (United States)

Lek, Jun Yan; Xing, Guichuan; Sum, Tze Chien; Lam, Yeng Ming

2014-01-22

Hybrid solar cells have the potential to be efficient solar-energy-harvesting devices that can combine the benefits of solution-processable organic materials and the extended absorption offered by inorganic materials. In this work, an understanding of the factors limiting the performance of hybrid solar cells is explored. Through photovoltaic-device characterization correlated with transient absorption spectroscopy measurements, it was found that the interfacial charge transfer between the organic (P3HT) and inorganic (CdSe nanorods) components is not the factor limiting the performance of these solar cells. The insulating original ligands retard the charge recombination between the charge-transfer states across the CdSe-P3HT interface, and this is actually beneficial for charge collection. These cells are, in fact, limited by the subsequent electron collection via CdSe nanoparticles to the electrodes. Hence, the design of a more continuous electron-transport pathway should greatly improve the performance of hybrid solar cells in the future.

High-efficiency free-form condenser overcoming rotational symmetry limitations.

Science.gov (United States)

Miñano, Juan C; Benítez, Pablo; Blen, José; Santamaría, Asunción

2008-12-08

Conventional condensers using rotational symmetric devices perform far from their theoretical limits when transferring optical power from sources such as arc lamps or halogen bulbs to the rectangular entrance of homogenizing prisms (target). We present a free-form condenser design (calculated with the SMS method) that overcomes the limitations inherent to rotational devices and can send to the target 1.8 times the power sent by an equivalent elliptical condenser for a 4:1 target aspect ratio and 1.5 times for 16:9 target and for practical values of target etendue.

Technical aspects of the joint JET-ISX-B beryllium limiter experiment

International Nuclear Information System (INIS)

Edmonds, P.H.; Dietz, K.J.; Mioduszewski, P.K.; Watson, R.D.; Emerson, L.C.; Gabbard, W.A.; Goodall, D.; Simpkins, J.E.; Yarber, J.L.

1985-01-01

An experiment has been performed on the Impurity Study Experiment (ISX-B) tokamak to test beryllium as a limiter material. Beryllium is an attractive candidate for a limiter and has been proposed for use in the Joint European Torus (JET) experiment. A temperature-controlled, segmented, beryllium top-rail limiter was located inside the plasma radius described by the existing titanium limiters. An extended set of diagnostics was added for measurement of scrapeoff and limiter parameters. These included visible and infrared monitoring systems, probes, and surface analysis experiments. Tokamak experiments included parameter surveys of both Ohmically heated and neutral-beam-heated plasmas and an extended fluence test of the limiter. The most significant effect of operation with a beryllium limiter was the reduction in low-Z impurities caused by gettering action of beryllium deposited on the liner walls. The experiment required the design and implementation of contamination control apparatus and work procedures to prevent the accidental dispersion of beryllium dust

Operational limits and conditions and operating procedures for research reactors. Safety guide

International Nuclear Information System (INIS)

2008-01-01

This publication provides practical guidance on all important aspects of developing, formulating and presenting the operational limits and conditions as well as the operating procedures for research reactors. It covers the concept of operational limits and conditions, their content, and the responsibilities of the operating organization with respect to their establishment, modification, documentation and compliance. The guidance also covers the training of operating personnel on performing periodic testing, established by the operational limits and conditions, and operating procedures

Quantum-limited heat conduction over macroscopic distances

Science.gov (United States)

Partanen, Matti; Tan, Kuan Yen; Govenius, Joonas; Lake, Russell E.; Mäkelä, Miika K.; Tanttu, Tuomo; Möttönen, Mikko

2016-05-01

The emerging quantum technological apparatuses, such as the quantum computer, call for extreme performance in thermal engineering. Cold distant heat sinks are needed for the quantized electric degrees of freedom owing to the increasing packaging density and heat dissipation. Importantly, quantum mechanics sets a fundamental upper limit for the flow of information and heat, which is quantified by the quantum of thermal conductance. However, the short distance between the heat-exchanging bodies in the previous experiments hinders their applicability in quantum technology. Here, we present experimental observations of quantum-limited heat conduction over macroscopic distances extending to a metre. We achieved this improvement of four orders of magnitude in the distance by utilizing microwave photons travelling in superconducting transmission lines. Thus, it seems that quantum-limited heat conduction has no fundamental distance cutoff. This work establishes the integration of normal-metal components into the framework of circuit quantum electrodynamics, which provides a basis for the superconducting quantum computer. Especially, our results facilitate remote cooling of nanoelectronic devices using faraway in situ-tunable heat sinks. Furthermore, quantum-limited heat conduction is important in contemporary thermodynamics. Here, the long distance may lead to ultimately efficient mesoscopic heat engines with promising practical applications.

Limitations of shallow nets approximation.

Science.gov (United States)

Lin, Shao-Bo

2017-10-01

In this paper, we aim at analyzing the approximation abilities of shallow networks in reproducing kernel Hilbert spaces (RKHSs). We prove that there is a probability measure such that the achievable lower bound for approximating by shallow nets can be realized for all functions in balls of reproducing kernel Hilbert space with high probability, which is different with the classical minimax approximation error estimates. This result together with the existing approximation results for deep nets shows the limitations for shallow nets and provides a theoretical explanation on why deep nets perform better than shallow nets. Copyright © 2017 Elsevier Ltd. All rights reserved.

Establishing legal limits for driving under the influence of marijuana

OpenAIRE

Wong, Kristin; Brady, Joanne E; Li, Guohua

2014-01-01

Marijuana has become the most commonly detected non-alcohol substance among drivers in the United States and Europe. Use of marijuana has been shown to impair driving performance and increase crash risk. Due to the lack of standardization in assessing marijuana-induced impairment and limitations of zero tolerance legislation, more jurisdictions are adopting per se laws by specifying a legal limit of ?9-tetrahydrocannabinol (THC) at or above which drivers are prosecuted for driving under the i...

Optimising Mycobacterium tuberculosis detection in resource limited settings.

Science.gov (United States)

Alfred, Nwofor; Lovette, Lawson; Aliyu, Gambo; Olusegun, Obasanya; Meshak, Panwal; Jilang, Tunkat; Iwakun, Mosunmola; Nnamdi, Emenyonu; Olubunmi, Onuoha; Dakum, Patrick; Abimiku, Alash'le

2014-03-03

The light-emitting diode (LED) fluorescence microscopy has made acid-fast bacilli (AFB) detection faster and efficient although its optimal performance in resource-limited settings is still being studied. We assessed the optimal performances of light and fluorescence microscopy in routine conditions of a resource-limited setting and evaluated the digestion time for sputum samples for maximum yield of positive cultures. Cross-sectional study. Facility-based involving samples of routine patients receiving tuberculosis treatment and care from the main tuberculosis case referral centre in northern Nigeria. The study included 450 sputum samples from 150 new patients with clinical diagnosis of pulmonary tuberculosis. The 450 samples were pooled into 150 specimens, examined independently with mercury vapour lamp (FM), LED CysCope (CY) and Primo Star iLED (PiLED) fluorescence microscopies, and with the Ziehl-Neelsen (ZN) microscopy to assess the performance of each technique compared with liquid culture. The cultured specimens were decontaminated with BD Mycoprep (4% NaOH-1% NLAC and 2.9% sodium citrate) for 10, 15 and 20 min before incubation in Mycobacterium growth incubator tube (MGIT) system and growth examined for acid-fast bacilli (AFB). Of the 150 specimens examined by direct microscopy: 44 (29%), 60 (40%), 49 (33%) and 64 (43%) were AFB positive by ZN, FM, CY and iLED microscopy, respectively. Digestion of sputum samples for 10, 15 and 20 min yielded mycobacterial growth in 72 (48%), 81 (54%) and 68 (45%) of the digested samples, respectively, after incubation in the MGIT system. In routine laboratory conditions of a resource-limited setting, our study has demonstrated the superiority of fluorescence microscopy over the conventional ZN technique. Digestion of sputum samples for 15 min yielded more positive cultures.

Legal weight truck cask model impact limiter response

International Nuclear Information System (INIS)

Meinert, N.M.; Shappert, L.B.

1989-01-01

Dynamic and quasi-static quarter-scale model testing was performed to supplement the analytical case presented in the Nuclear Assurance Corporation Legal Weight Truck (NAC LWT) cask transport licensing application. Four successive drop tests from 9.0 meters (30 feet) onto an unyielding surface and one 1.0-meter (40-inch) drop onto a scale mild steel pin 3.8 centimeters (1.5 inches) in diameter, corroborated the impact limiter design and structural analyses presented in the licensing application. Quantitative measurements, made during drop testing, support the impact limiter analyses. High-speed photography of the tests confirm that only a small amount of energy is elastically stored in the aluminum honeycomb and that oblique drop slapdown is not significant. The qualitative conclusion is that the limiter protected LWT cask will not sustain permanent structural damage and containment will be maintained, subsequent to a hypothetical accident, as shown by structural analyses

Equilibrium helium film in the thick film limit

International Nuclear Information System (INIS)

Klier, J.; Schletterer, F.; Leiderer, P.; Shikin, V.

2003-01-01

For the thickness of a liquid or solid quantum film, like liquid helium or solid hydrogen, there exist still open questions about how the film thickness develops in certain limits. One of these is the thick film limit, i.e., the crossover from the thick film to bulk. We have performed measurements in this range using the surface plasmon resonance technique and an evaporated Ag film deposited on glass as substrate. The thickness of the adsorbed helium film is varied by changing the distance h of the bulk reservoir to the surface of the substrate. In the limiting case, when h > 0, the film thickness approaches about 100 nm following the van der Waals law in the retarded regime. The film thickness and its dependence on h is precisely determined and theoretically modeled. The equilibrium film thickness behaviour is discussed in detail. The agreement between theory and experiment is very good

Energy saving in WWTP: Daily benchmarking under uncertainty and data availability limitations.

Science.gov (United States)

Torregrossa, D; Schutz, G; Cornelissen, A; Hernández-Sancho, F; Hansen, J

2016-07-01

Efficient management of Waste Water Treatment Plants (WWTPs) can produce significant environmental and economic benefits. Energy benchmarking can be used to compare WWTPs, identify targets and use these to improve their performance. Different authors have performed benchmark analysis on monthly or yearly basis but their approaches suffer from a time lag between an event, its detection, interpretation and potential actions. The availability of on-line measurement data on many WWTPs should theoretically enable the decrease of the management response time by daily benchmarking. Unfortunately this approach is often impossible because of limited data availability. This paper proposes a methodology to perform a daily benchmark analysis under database limitations. The methodology has been applied to the Energy Online System (EOS) developed in the framework of the project "INNERS" (INNovative Energy Recovery Strategies in the urban water cycle). EOS calculates a set of Key Performance Indicators (KPIs) for the evaluation of energy and process performances. In EOS, the energy KPIs take in consideration the pollutant load in order to enable the comparison between different plants. For example, EOS does not analyse the energy consumption but the energy consumption on pollutant load. This approach enables the comparison of performances for plants with different loads or for a single plant under different load conditions. The energy consumption is measured by on-line sensors, while the pollutant load is measured in the laboratory approximately every 14 days. Consequently, the unavailability of the water quality parameters is the limiting factor in calculating energy KPIs. In this paper, in order to overcome this limitation, the authors have developed a methodology to estimate the required parameters and manage the uncertainty in the estimation. By coupling the parameter estimation with an interval based benchmark approach, the authors propose an effective, fast and reproducible

Determination of detection limits for a VPD ICPMS method of analysis

International Nuclear Information System (INIS)

Badard, M.; Veillerot, M.

2007-01-01

This training course report presents the different methods of detection and quantifying of metallic impurities in semiconductors. One of the most precise technique is the collection of metal impurities by vapor phase decomposition (VPD) followed by their analysis by ICPMS (inductively coupled plasma mass spectrometry). The study shows the importance of detection limits in the domain of chemical analysis and the way to determine them for the ICPMS analysis. The results found on detection limits are excellent. Even if the detection limits reached with ICPMS performed after manual or automatic VPD are much higher than detection limits of ICPMS alone, this method remains one of the most sensible for ultra-traces analysis. (J.S.)

Effects of Supply Chain Risk Management on Organization Performance: Case of Andy Forwarders Services Limited

OpenAIRE

Caroline Wanjiru Munyuko

2015-01-01

The purpose of the research was to determine the effects of Supply chain risk management on organization performance. Previous studies have focused on risk management within the general context of an organization but little attention has been focused on how supply chain risk affect organization performance in terms of its bottom line profits and overall organization objectives. Particular attention was paid to the effects of supply chain risk management variables to the performance of the org...

MHD stability limits in the TCV Tokamak

International Nuclear Information System (INIS)

Reimerdes, H.

2001-07-01

Magnetohydrodynamic (MHD) instabilities can limit the performance and degrade the confinement of tokamak plasmas. The Tokamak a Configuration Variable (TCV), unique for its capability to produce a variety of poloidal plasma shapes, has been used to analyse various instabilities and compare their behaviour with theoretical predictions. These instabilities are perturbations of the magnetic field, which usually extend to the plasma edge where they can be detected with magnetic pick-up coils as magnetic fluctuations. A spatially dense set of magnetic probes, installed inside the TCV vacuum vessel, allows for a fast observation of these fluctuations. The structure and temporal evolution of coherent modes is extracted using several numerical methods. In addition to the setup of the magnetic diagnostic and the implementation of analysis methods, the subject matter of this thesis focuses on four instabilities, which impose local and global stability limits. All of these instabilities are relevant for the operation of a fusion reactor and a profound understanding of their behaviour is required in order to optimise the performance of such a reactor. Sawteeth, which are central relaxation oscillations common to most standard tokamak scenarios, have a significant effect on central plasma parameters. In TCV, systematic scans of the plasma shape have revealed a strong dependence of their behaviour on elongation κ and triangularity δ, with high κ, and low δ leading to shorter sawteeth with smaller crashes. This shape dependence is increased by applying central electron cyclotron heating. The response to additional heating power is determined by the role of ideal or resistive MHD in triggering the sawtooth crash. For plasma shapes where additional heating and consequently, a faster increase of the central pressure shortens the sawteeth, the low experimental limit of the pressure gradient within the q = 1 surface is consistent with ideal MHD predictions. The observed decrease

MHD stability limits in the TCV Tokamak

Energy Technology Data Exchange (ETDEWEB)

Reimerdes, H. [Ecole Polytechnique Federale de Lausanne, Centre de Recherches en Physique des Plasmas (CRPP), CH-1015 Lausanne (Switzerland)

2001-07-01

Magnetohydrodynamic (MHD) instabilities can limit the performance and degrade the confinement of tokamak plasmas. The Tokamak a Configuration Variable (TCV), unique for its capability to produce a variety of poloidal plasma shapes, has been used to analyse various instabilities and compare their behaviour with theoretical predictions. These instabilities are perturbations of the magnetic field, which usually extend to the plasma edge where they can be detected with magnetic pick-up coils as magnetic fluctuations. A spatially dense set of magnetic probes, installed inside the TCV vacuum vessel, allows for a fast observation of these fluctuations. The structure and temporal evolution of coherent modes is extracted using several numerical methods. In addition to the setup of the magnetic diagnostic and the implementation of analysis methods, the subject matter of this thesis focuses on four instabilities, which impose local and global stability limits. All of these instabilities are relevant for the operation of a fusion reactor and a profound understanding of their behaviour is required in order to optimise the performance of such a reactor. Sawteeth, which are central relaxation oscillations common to most standard tokamak scenarios, have a significant effect on central plasma parameters. In TCV, systematic scans of the plasma shape have revealed a strong dependence of their behaviour on elongation {kappa} and triangularity {delta}, with high {kappa}, and low {delta} leading to shorter sawteeth with smaller crashes. This shape dependence is increased by applying central electron cyclotron heating. The response to additional heating power is determined by the role of ideal or resistive MHD in triggering the sawtooth crash. For plasma shapes where additional heating and consequently, a faster increase of the central pressure shortens the sawteeth, the low experimental limit of the pressure gradient within the q = 1 surface is consistent with ideal MHD predictions. The

Limitations and improvements for harmonic generation measurements

International Nuclear Information System (INIS)

Best, Steven; Croxford, Anthony; Neild, Simon

2014-01-01

A typical acoustic harmonic generation measurement comes with certain limitations. Firstly, the use of the plane wave-based analysis used to extract the nonlinear parameter, β, ignores the effects of diffraction, attenuation and receiver averaging which are common to most experiments, and may therefore limit the accuracy of a measurement. Secondly, the method usually requires data obtained from a through-transmission type setup, which may not be practical in a field measurement scenario where access to the component is limited. Thirdly, the technique lacks a means of pinpointing areas of damage in a component, as the measured nonlinearity represents an average over the length of signal propagation. Here we describe a three-dimensional model of harmonic generation in a sound beam, which is intended to provide a more realistic representation of a typical experiment. The presence of a reflecting boundary is then incorporated into the model to assess the feasibility of performing single-sided measurements. Experimental validation is provided where possible. Finally, a focusing acoustic source is modelled to provide a theoretical indication of the afforded advantages when the nonlinearity is localized

Limit on the electric charge of antihydrogen

Energy Technology Data Exchange (ETDEWEB)

Capra, A., E-mail: acapra@triumf.ca; Amole, C. [York University, Department of Physics and Astronomy (Canada); Ashkezari, M. D. [Simon Fraser University, Department of Physics (Canada); Baquero-Ruiz, M. [University of California at Berkeley, Department of Physics (United States); Bertsche, W. [University of Manchester, School of Physics and Astronomy (United Kingdom); Butler, E. [Imperial College, Centre for Cold Matter (United Kingdom); Cesar, C. L. [Universidade Federal do Rio de Janeiro, Instituto de Física (Brazil); Charlton, M.; Eriksson, S. [Swansea University, Department of Physics, College of Science (United Kingdom); Fajans, J. [University of California at Berkeley, Department of Physics (United States); Friesen, T. [University of Calgary, Department of Physics and Astronomy (Canada); Fujiwara, M. C.; Gill, D. R. [TRIUMF (Canada); Gutierrez, A. [University of British Columbia, Department of Physics and Astronomy (Canada); Hangst, J. S. [CERN, Physics Department (Switzerland); Hardy, W. N. [University of British Columbia, Department of Physics and Astronomy (Canada); Hayden, M. E. [Simon Fraser University, Department of Physics (Canada); Isaac, C. A. [Swansea University, Department of Physics, College of Science (United Kingdom); Jonsell, S. [Stockholm University, Department of Physics (Sweden); Kurchaninov, L. [TRIUMF (Canada); and others

2017-11-15

The ALPHA collaboration has successfully demonstrated the production and the confinement of cold antihydrogen, H̅. An analysis of trapping data allowed a stringent limit to be placed on the electric charge of the simplest antiatom. Charge neutrality of matter is known to a very high precision, hence a neutrality limit of H̅ provides a test of CPT invariance. The experimental technique is based on the measurement of the deflection of putatively charged H̅ in an electric field. The tendency for trapped H̅ atoms to be displaced by electrostatic fields is measured and compared to the results of a detailed simulation of H̅ dynamics in the trap. An extensive survey of the systematic errors was performed, and this work focuses on those due to the silicon vertex detector, which is the device used to determine the H̅ annihilation position. The limit obtained on the charge of the H̅ atom is Q = (−1.3 ± 1.8 ± 0.4) × 10{sup −8}, representing the first precision measurement with H̅ [1].

Lower bounds on scintillation detector timing performance

International Nuclear Information System (INIS)

Clinthorne, N.H.; Rogers, W.L.; Hero, A.O. III.; Petrick, N.A.

1990-01-01

Fundamental method-independent limits on the timing performance of scintillation detectors are useful for identifying regimes in which either present timing methods are nearly optimal or where a considerable performance gain might be realized using better pulse processing techniques. Several types of lower bounds on mean-squared timing error (MSE) performance have been developed and applied to scintillation detectors. The simple Cramer-Rao (CR) bound can be useful in determining the limiting MSE for scintillators having a relatively high rate of photon problction such as BaF 2 and NaI(Tl); however, it tends to overestimate the achievalbe performance for scintillators with lower rates such as BGO. For this reason, alternative bounds have been developed using rate-distortion theory or by assuming that the conversion of energy to scintillation light must pass through excited states which have exponential lifetime densities. The bounds are functions of the mean scintillation pulse shape, the scintillation intensity, and photodetector characteristics; they are simple to evaluate and can be used to conveniently assess the limiting timing performance of scintillation detectors. (orig.)

12 CFR 25.25 - Community development test for wholesale or limited purpose banks.

Science.gov (United States)

2010-01-01

... the community development performance of a wholesale or limited purpose bank pursuant to the following... performance rating. The OCC rates a bank's community development performance as provided in appendix A of this... 12 Banks and Banking 1 2010-01-01 2010-01-01 false Community development test for wholesale or...

Planar concentrators near the étendue limit

Science.gov (United States)

Winston, Roland; Gordon, Jeffrey M.

2005-10-01

Recently proposed aplanatic imaging designs are integrally combined with nonimaging flux boosters to produce an ultracompact planar glass-filled concentrator that performs near the étendue limit. Such optical devices are attractive for high-efficiency multijunction photovoltaics at high flux, with realistic power generation of 1 W from a 1 mm² cell. When deployed in reverse, our designs provide collimation even for high-numerical-aperture light sources.

Planar concentrators near the étendue limit.

Science.gov (United States)

Winston, Roland; Gordon, Jeffrey M

2005-10-01

Recently proposed aplanatic imaging designs are integrally combined with nonimaging flux boosters to produce an ultracompact planar glass-filled concentrator that performs near the étendue limit. Such optical devices are attractive for high-efficiency multijunction photovoltaics at high flux, with realistic power generation of 1 W from a 1 mm2 cell. When deployed in reverse, our designs provide collimation even for high-numerical-aperture light sources.

Quantification of human performance using performance shaping factors

International Nuclear Information System (INIS)

Embrey, D.E.; Hall, R.E.

1982-01-01

This paper considers the human reliability data needs for Probabilistic Risk Assessment, and concludes that some form of extrapolation will be needed to supplement the limited data resources currently available. A technique for quantifying expert subjective judgement is described, which can be used to systematically perform extrapolations. Some preliminary results from recent research in this area are presented

Material limitations on the detection limit in refractometry

DEFF Research Database (Denmark)

Skafte-Pedersen, Peder; Nunes, Pedro; Xiao, Sanshui

2009-01-01

We discuss the detection limit for refractometric sensors relying on high-Q optical cavities and show that the ultimate classical detection limit is given by min {Δn} ≳ η with n + iη being the complex refractive index of the material under refractometric investigation. Taking finite Q factors and...

Update in the understanding of altitude-induced limitations to performance in team-sport athletes.

Science.gov (United States)

Billaut, François; Aughey, Robert J

2013-12-01

The internationalism of field-based team sports (TS) such as football and rugby requires teams to compete in tournaments held at low to moderate altitude (∼1200-2500 m). In TS, acceleration, speed and aerobic endurance are physical characteristics associated with ball possession and, ultimately, scoring. While these qualities are affected by the development of neuromuscular fatigue at sea level, arterial hypoxaemia induced by exposure to altitude may further hinder the capacity to perform consecutive accelerations (CAC) or sprint endurance and thereby change the outcome of a match. The higher the altitude, the more severe the hypoxaemia, and thus, the larger the expected decline in aerobic endurance, CAC and match running performance. Therefore, it is critical for athletes and coaches to understand how arterial hypoxaemia affects aerobic endurance and CAC and the magnitude of decline they may face at altitude for optimal preparation and increased chances of success. This mini review summarises the effects of acute altitude/hypoxia exposure on aerobic endurance, CAC and activity profiles of TS athletes performing in the laboratory and during matches at natural altitude, and analyses the latest findings about the consequences of arterial hypoxaemia on the relationship between peripheral perturbations, neural adjustments and performance during repeated sprints or CAC. Finally, we briefly discuss how altitude training can potentially help athletes prepare for competition at altitude.

Atomic Energy of Canada Limited annual report 1985-86

International Nuclear Information System (INIS)

1986-01-01

The annual report of Atomic Energy of Canada Limited for the fiscal year ended March 31, 1986 covers the following subjects: report from the chairman and the president; research company; CANDU operations; radiochemical company; employee performance; nuclear Canada; Financial section; and board of directors and officers

Possibilities and limitations for sustainable bioenergy production systems

International Nuclear Information System (INIS)

Smeets, Edward Martinus Wilhelmus Utrecht University

2008-05-01

The main objective of this thesis is to investigate the possibilities and limitations of sustainable bioenergy production. To this end, the following research questions have been formulated: (1). What is the potential of different world regions to produce biomass for energy generation in the year 2050, taking account of biological and climatological limitations, the use of biomass to produce food, materials and traditional bioenergy, as well as the need to maintain existing forests and thus protect biodiversity?; (2) What are the main bottlenecks to formulating and implementing sustainability criteria for bioenergy production?; (3) To what extent does complying with sustainability criteria have impacts on the costs and potential of bioenergy production?; (4) To what extent do fertilizer- and manure-induced nitrous oxide (N2O) emissions due to energy crop production have an impact on the reduction of greenhouse gas (GHG) emissions when conventional transportation fuels are replaced by first-generation biofuels?; (5) In terms of economic and environmental performance, how does Europe's production, storage and transport of miscanthus and switchgrass in 2004 compare to that in 2030? Throughout this thesis, specific attention is paid to knowledge gaps and their potential impact on results, the aim being to identify priorities for future research and development. Another key element of our research is that we evaluate the possibilities and limitations of strategies that are designed to improve the performance of bioenergy production systems and that may be incorporated in bioenergy certification schemes and bioenergy promoting policies

Piezoelectric PVDF materials performance and operation limits in space environments

International Nuclear Information System (INIS)

Dargaville, Tim Richard; Assink, Roger Alan; Clough, Roger Lee; Celina, Mathias Christopher

2004-01-01

Piezoelectric polymers based on polyvinylidene fluoride (PVDF) are of interest for large aperture space-based telescopes. Dimensional adjustments of adaptive polymer films are achieved via charge deposition and require a detailed understanding of the piezoelectric material responses which are expected to suffer due to strong vacuum UV, gamma, X-ray, energetic particles and atomic oxygen under low earth orbit exposure conditions. The degradation of PVDF and its copolymers under various stress environments has been investigated. Initial radiation aging studies using gamma- and e-beam irradiation have shown complex material changes with significant crosslinking, lowered melting and Curie points (where observable), effects on crystallinity, but little influence on overall piezoelectric properties. Surprisingly, complex aging processes have also been observed in elevated temperature environments with annealing phenomena and cyclic stresses resulting in thermal depoling of domains. Overall materials performance appears to be governed by a combination of chemical and physical degradation processes. Molecular changes are primarily induced via radiative damage, and physical damage from temperature and AO exposure is evident as depoling and surface erosion. Major differences between individual copolymers have been observed providing feedback on material selection strategies

Work limitations among working persons with rheumatoid arthritis: results, reliability, and validity of the work limitations questionnaire in 836 patients.

Science.gov (United States)

Walker, Nancy; Michaud, Kaleb; Wolfe, Frederick

2005-06-01

To describe workplace limitations and the validity and reliability of the Work Limitations Questionnaire (WLQ) in persons with rheumatoid arthritis (RA). A total of 836 employed persons with RA reported clinical and work related measures and completed the WLQ, a 25 item questionnaire that assesses the impact of chronic health conditions on job performance and productivity. Limitations are categorized into 4 domains: physical demands (PDS), mental demands (MDS), time management demands (TMS), and output demands (ODS), which are then used to calculate the WLQ index. Of the 836 completed WLQ, about 10% (85) could not be scored, as more than half the items in each domain were not applicable to the patient's job. Demographic and clinical variables were associated with missing WLQ scores including older age (OR 1.7, 95% CI 1.3-2.1), male sex (OR 1.9, 95% CI 1.2-3.0), and Health Assessment Questionnaire (HAQ) scores (OR 1.4, 95% CI 1.0-2.0). Work limitations were present in all work domains: PDS (27.5%), MDS (15.7%), ODS (19.4%), and TMS (28.6%), resulting in a mean WLQ index of 5.9 (SD 5.6), which corresponds to a 4.9% decrease in productivity and a 5.1% increase in work hours to compensate for productivity loss. The WLQ index was inversely associated with Medical Outcomes Study Short Form 36 (SF-36) Mental Component Score (MCS; r = -0.60) and Physical Component Score (PCS; r = -0.49). Fatigue (0.5), pain (0.46), and HAQ (0.56) were also significantly associated with the WLQ index. Weaker associations were seen with days unable to perform (0.29), days activities cut down (0.38), and annual income (-0.10). The WLQ is a reliable tool for assessing work productivity. However, persons with RA tend to select jobs that they can do with their RA limitations, with the result that the WLQ does not detect functional limitations as well as the HAQ and SF-36. The WLQ provides special information that is not available using conventional measures of assessment, and can provide helpful

The limits to solar thermal electricity

International Nuclear Information System (INIS)

Trainer, Ted

2014-01-01

The potential and limits of solar thermal power systems depend primarily on their capacity to meet electricity demand in mid-winter, and the associated cost, storage and other implications. Evidence on output and costs is analysed. Most attention is given to central receivers. Problems of low radiation levels, embodied energy costs, variability and storage are discussed and are found to set significant difficulties for large scale solar thermal supply in less than ideal latitudes and seasons. It is concluded that for solar thermal systems to meet a large fraction of anticipated global electricity demand in winter would involve prohibitive capital costs. - Highlights: • Output and capital cost data for various solar thermal technologies is examined. • Special attention is given to performance in winter. • Attention is also given to the effect of solar intermittency. • Implications for storage are considered. • It is concluded that there are significant limits to solar thermal power

Charismatic leadership, environmental dynamism, and performance

NARCIS (Netherlands)

de Hoogh, Annebel H.B.; den Hartog, Deanne N.; Koopman, Paul L.; Thierry, Henk; van den Berg, Peter T.; van der Weide, J.G.; Wilderom, Celeste P.M.

2004-01-01

Most studies relating charismatic leadership to performance have limitations concerning selection of criterion measures and investigation of moderators. Therefore, this study examines relationships between charismatic leadership and multiple performance outcomes under different levels of

Air quality indicators from the Environmental Performance Index: potential use and limitations in South Africa

Directory of Open Access Journals (Sweden)

Rebecca M. Garland

2017-06-01

Full Text Available In responding to deteriorating air quality, many countries, including South Africa, have implemented national programmes that aim to manage and regulate ambient air quality, and the emissions of air pollutants. One aspect within these management strategies is effective communication to stakeholders, including the general public, with regard to the state and trend of ambient air quality in South Africa. Currently, information on ambient air quality is communicated through ambient mass concentration values, as well as number of exceedances of South African National Ambient Standards. However, these do not directly communicate the potential impact on human health and the ecosystem. To this end, the use of air quality indicators is seen as a potential way to achieve communication to stakeholders in a simplified, yet scientifically defensible manner. Air quality indicators and their source data from the Environmental Performance Index (EPI were interrogated to understand their potential use in South Africa. An assessment of four air quality indicators, together with their source data, showed improvements in air quality over the time period studied, though the input data do have uncertainties. The source data for the PM indicators, which came from a global dataset, underestimated the annual PM2.5 concentrations in the Highveld Priority Area and Vaal Triangle Airshed Priority Area over the time period studied (2009-2014 by ~3.7 times. This highlights a key limitation of national-scale indicators and input data, that while the data used by the EPI are a well-thought out estimate of a country’s air quality profile, they remain a generalised estimate. The assumptions and uncertainty inherent in such an ambitious global-wide attempt make the estimates inaccurate for countries without proper emissions tracking and accounting and few monitoring stations, such as South Africa. Thus, the inputs and resultant indicators should be used with caution until such

Three-dimensional live microscopy beyond the diffraction limit

International Nuclear Information System (INIS)

Fiolka, Reto

2013-01-01

In fluorescence microscopy it has become possible to fundamentally overcome the diffraction limited resolution in all three spatial dimensions. However, to have the most impact in biological sciences, new optical microscopy techniques need to be compatible with live cell imaging: image acquisition has to be fast enough to capture cellular dynamics at the new resolution limit while light exposure needs to be minimized to prevent photo-toxic effects. With increasing spatial resolution, these requirements become more difficult to meet, even more so when volumetric imaging is performed. In this review, techniques that have been successfully applied to three-dimensional, super-resolution live microscopy are presented and their relative strengths and weaknesses are discussed. (special issue article)

Low plasma edge temperatures for the self-pumped limiter

International Nuclear Information System (INIS)

Terry, W.K.; Brooks, J.N.

1985-03-01

Transport code calculations have been performed to study the operation of an INTOR-like tokamak plasma from which helium is removed by a self-pumped limiter, which traps helium, but not hydrogen, in its surface layers. To prevent saturation by helium, the surface is renewed by continuous injection of the surface material (vanadium in this study) into the scrape-off layer. The presence of the injected vanadium leads to plasma temperatures well below 50 eV in the scrape-off layer, with supplementary rf heating. Operation in this edge temperature regime is essential for the use of medium- and high-Z limiter coatings

Hanford Waste Vitrification Project Building limited scope risk assessment

International Nuclear Information System (INIS)

Braun, D.J.; Lindberg, S.E.; Reardon, M.F.; Wilson, G.P.

1992-10-01

A limited scope risk assessment was performed on the preliminary design of a high-level waste interim storage facility. The Canister Storage Building (CSB) facility will be built to support remediation at the US Department of Energy Hanford Site in Washington State. The CSB will be part of the support facilities for a high level Hanford Waste Vitrification Plant (HWVP). The limited scope risk assessment is based on a preliminary design which uses forced air circulation systems to move air through the building vault. The current building design calls for natural circulation to move air through the building vault

Thermal Limits and Thresholds of Red Sea Biota

KAUST Repository

Chaidez, Veronica

2018-05-01

As ocean temperatures continue to rise, the effect of temperature on marine organisms becomes highly relevant. The Red Sea is the warmest sea and is rapidly warming with current surface temperatures (28 – 34 °C) already exceeding those of most tropical systems. This has major consequences for organisms that may already find themselves at their thermal limits. The aim of this project was to define the thermal limits and thresholds of certain Red Sea species. Firstly, to better understand the thermal regimes of the Red Sea, we looked at decadal trends in maximum sea surface temperature across the basin. Then, we tested the thermal capacities of Red Sea mangroves and zooplankton, two key ecological groups, by performing thermal stress experiments in the laboratory. We found that the Red Sea basin is warming faster than the global average (0.17 °C decade-1), the thermal limit of mangrove propagules is between 33 and 35 °C, and the limits among the most common zooplankton groups range from 30 to 36 °C. This project gives us a better understanding of how organisms respond to extreme temperatures and how they may be affected in a future, warmer, ocean.

HOME Income Limits

Data.gov (United States)

Department of Housing and Urban Development — HOME Income Limits are calculated using the same methodology that HUD uses for calculating the income limits for the Section 8 program. These limits are based on HUD...

Superconducting magnet radiation limit considerations for fusion reactors

International Nuclear Information System (INIS)

Sawan, M.E.; Walstrom, P.L.

1986-01-01

The radiation limits for fusion reactor magnets have a direct impact on the cost of electricity. For example, reducing the inboard shield by 1 cm saves up to $3 million in the Tokamak Fusion Core Experiment cost. The magnet components most sensitive to radiation damage are the superconductor, stabilizer, and insulators. Nuclear heating in the magnet affects the design and also impacts the economic performance of the reactor through increased refrigeration costs. The radiation effects in the different components of the magnet are related, as all of them are determined by the flux level in the magnet. Hence, in efforts to push radiation limits, these effects should be considered simultaneously. Furthermore, the levels of radiation effects that correspond to the optimum nuclear heating determined from economic trade-off analysis will be useful in specifying the fluence, dose, and stabilization limit goals for the magnet development program. In this paper, we review the available irradiation data and assess the need for achieving higher irradiation levels

40 CFR 63.3967 - How do I establish the emission capture system and add-on control device operating limits during...

Science.gov (United States)

2010-07-01

... system and add-on control device operating limits during the performance test? 63.3967 Section 63.3967... capture system and add-on control device operating limits during the performance test? During the... the operating limits required by § 63.3892 according to this section, unless you have received...

Flutter and limit cycle oscillation suppression using linear and nonlinear tuned vibration absorbers

OpenAIRE

Verstraelen, Edouard; Kerschen, Gaëtan; Dimitriadis, Grigorios

2017-01-01

Aircraft are more than ever pushed to their limits for performance reasons. Consequently, they become increasingly nonlinear and they are more prone to undergo aeroelastic limit cycle oscillations. Structural nonlinearities affect aircraft such as the F-16, which can undergo store-induced limit cycle oscillations (LCOs). Furthermore, transonic buzz can lead to LCOs because of moving shock waves in transonic flight conditions on many aircraft. This study presents a numerical investigation o...

Test of a beryllium limiter in the tokamak UNITOR

International Nuclear Information System (INIS)

Hackmann, J.; Uhlenbusch, J.

1984-01-01

Beryllium rail limiters are inserted into the tokamak UNITOR to study the compatibility of this material with the plasma. The power load onto the limiter surface is 1-2 kW/cm 2 during the plasma pulse length of 50 ms duration. The concentration of heavy (Cr) and light (O) impurities is monitored by means of spectroscopy. In comparison with other materials tested likewise (graphite, Ni, Al 2 O 3 , TiC, SiC, SS) the Be-experiments have shown the following improvements: (a) the concentration of heavy impurities is considerably reduced, (b) this reduction is preserved if the poloidal Be-limiters are retracted from the plasma, (c) the plasma resistivity is diminished, (d) the occurrence of disruptions decreases. A total amount of 6 mg beryllium was found distributed on the inner torus wall after 1500 shots. The decontamination of the apparatus was performed without major problems. Only very little volatile Be-dust was detected, and peripheric parts (pumps, mass spectrometer etc.) were not contaminated. The beryllium released from the limiters was found to be entirely deposited on the torus wall mainly in the vicinity of the limiters. (orig.)

Shift scheduling limits for the nuclear industry NRC policy and recommendations

International Nuclear Information System (INIS)

Koontz, J.; Morisseau, D.; Lewis, P.

1985-01-01

A study on shift scheduling and use of overtime and their effects on human performance in nuclear and non-nuclear industries was conducted. An analysis of the literature, current practices, and federal policy on shift scheduling resulted in human factors recommendations for limiting hours of work in the nuclear industry for nuclear power plant personnel conducting safety related functions. Recommended limits on total hours of work were developed by a panel of experts for both 8-hour and 12-hour daily shift schedules for weekly, biweekly, monthly, and annual work periods. The study results are particularly applicable to control room operators but should also be considered for other personnel where performance degradation due to fatigue could directly affect safe plant operations

Chip-integrated optical power limiter based on an all-passive micro-ring resonator

Science.gov (United States)

Yan, Siqi; Dong, Jianji; Zheng, Aoling; Zhang, Xinliang

2014-10-01

Recent progress in silicon nanophotonics has dramatically advanced the possible realization of large-scale on-chip optical interconnects integration. Adopting photons as information carriers can break the performance bottleneck of electronic integrated circuit such as serious thermal losses and poor process rates. However, in integrated photonics circuits, few reported work can impose an upper limit of optical power therefore prevent the optical device from harm caused by high power. In this study, we experimentally demonstrate a feasible integrated scheme based on a single all-passive micro-ring resonator to realize the optical power limitation which has a similar function of current limiting circuit in electronics. Besides, we analyze the performance of optical power limiter at various signal bit rates. The results show that the proposed device can limit the signal power effectively at a bit rate up to 20 Gbit/s without deteriorating the signal. Meanwhile, this ultra-compact silicon device can be completely compatible with the electronic technology (typically complementary metal-oxide semiconductor technology), which may pave the way of very large scale integrated photonic circuits for all-optical information processors and artificial intelligence systems.

The capacity limitations of orientation summary statistics

Science.gov (United States)

Attarha, Mouna; Moore, Cathleen M.

2015-01-01

The simultaneous–sequential method was used to test the processing capacity of establishing mean orientation summaries. Four clusters of oriented Gabor patches were presented in the peripheral visual field. One of the clusters had a mean orientation that was tilted either left or right while the mean orientations of the other three clusters were roughly vertical. All four clusters were presented at the same time in the simultaneous condition whereas the clusters appeared in temporal subsets of two in the sequential condition. Performance was lower when the means of all four clusters had to be processed concurrently than when only two had to be processed in the same amount of time. The advantage for establishing fewer summaries at a given time indicates that the processing of mean orientation engages limited-capacity processes (Experiment 1). This limitation cannot be attributed to crowding, low target-distractor discriminability, or a limited-capacity comparison process (Experiments 2 and 3). In contrast to the limitations of establishing multiple summary representations, establishing a single summary representation unfolds without interference (Experiment 4). When interpreted in the context of recent work on the capacity of summary statistics, these findings encourage reevaluation of the view that early visual perception consists of summary statistic representations that unfold independently across multiple areas of the visual field. PMID:25810160

The effects of Tai Ji Quan training on limits of stability in older adults

Directory of Open Access Journals (Sweden)

Li F

2014-08-01

Full Text Available Fuzhong Li1,2 1Oregon Research Institute, Eugene, OR, USA; 2Shanghai University of Sport, Shanghai, People’s Republic of ChinaBackground: Limits of stability, defined as the ability to maintain the center of gravity within the boundary of the base of support, is critically important for older adults in performing their activities of daily living. However, few exercise programs specifically tailored to enhance limits of stability exist. The primary purpose of this study was to determine whether a therapeutically designed intervention, Tai Ji Quan: Moving for Better Balance (TJQMBB, could improve limits of stability in older adults. A secondary purpose was to examine concomitant change in limits of stability and physical performance as a result of the intervention.Methods: A single-group design was used in which 145 community-dwelling older adults (average age: 75 years were enrolled in TJQMBB classes, participating twice weekly for 48 weeks. Primary outcome measures were three indicators of limits of stability (LOS (endpoint excursion, movement velocity, and directional control, with secondary measures of physical performance being Timed Up and Go and 50-foot speed walk (in seconds, which were assessed at baseline, 24 weeks, and 48 weeks. Changes in the repeated measures of outcome variables were analyzed via latent curve analysis.Results: At 48 weeks, a significant rate of change (improvement over time was observed in the three limits of stability indicators (endpoint execution: 8.30% LOS, P<0.001; movement velocity: 0.86 degrees/second, P<0.001; directional control: 6.79% of 100, P<0.001; all reached a threshold of real change as judged by the minimal detectable change values. Improvements in the three limits of stability measures were concomitantly correlated with improved (reduced times performance scores in the Timed Up and Go (-0.30, -0.45, and -0.55, ­respectively and 50-foot walk (-0.33, -0.49, and -0.41, respectively

Exploiting protein flexibility to predict the location of allosteric sites

Directory of Open Access Journals (Sweden)

Panjkovich Alejandro

2012-10-01

Full Text Available Abstract Background Allostery is one of the most powerful and common ways of regulation of protein activity. However, for most allosteric proteins identified to date the mechanistic details of allosteric modulation are not yet well understood. Uncovering common mechanistic patterns underlying allostery would allow not only a better academic understanding of the phenomena, but it would also streamline the design of novel therapeutic solutions. This relatively unexplored therapeutic potential and the putative advantages of allosteric drugs over classical active-site inhibitors fuel the attention allosteric-drug research is receiving at present. A first step to harness the regulatory potential and versatility of allosteric sites, in the context of drug-discovery and design, would be to detect or predict their presence and location. In this article, we describe a simple computational approach, based on the effect allosteric ligands exert on protein flexibility upon binding, to predict the existence and position of allosteric sites on a given protein structure. Results By querying the literature and a recently available database of allosteric sites, we gathered 213 allosteric proteins with structural information that we further filtered into a non-redundant set of 91 proteins. We performed normal-mode analysis and observed significant changes in protein flexibility upon allosteric-ligand binding in 70% of the cases. These results agree with the current view that allosteric mechanisms are in many cases governed by changes in protein dynamics caused by ligand binding. Furthermore, we implemented an approach that achieves 65% positive predictive value in identifying allosteric sites within the set of predicted cavities of a protein (stricter parameters set, 0.22 sensitivity, by combining the current analysis on dynamics with previous results on structural conservation of allosteric sites. We also analyzed four biological examples in detail, revealing

Error rate performance of narrowband multilevel CPFSK signals

Science.gov (United States)

Ekanayake, N.; Fonseka, K. J. P.

1987-04-01

The paper presents a relatively simple method for analyzing the effect of IF filtering on the performance of multilevel FM signals. Using this method, the error rate performance of narrowband FM signals is analyzed for three different detection techniques, namely limiter-discriminator detection, differential detection and coherent detection followed by differential decoding. The symbol error probabilities are computed for a Gaussian IF filter and a second-order Butterworth IF filter. It is shown that coherent detection and differential decoding yields better performance than limiter-discriminator detection and differential detection, whereas two noncoherent detectors yield approximately identical performance.

The effect of performance-volume limit on the DRG based acute care hospital financing in Hungary.

Science.gov (United States)

Endrei, Dóra; Zemplényi, Antal; Molics, Bálint; Agoston, István; Boncz, Imre

2014-04-01

The aim of our paper is to analyse the effect of the so-called performance volume limit (PVL) financing method on acute hospital care. The data were derived from the nationwide administrative dataset of the National Health Insurance Fund Administration (OEP) covering the period 2003-2008. We analysed the trends in the DRG cost-weights, number of cases, case-mix, and average length of stay. We calculated the average annual reimbursement rate per DRG cost-weight with and without the application of PVL degression according to the hospital type and medical professions. Our results showed that although the national case mix (i.e., the sum of all of the DRG cost-weights produced in one year) did not change between 2003-2006, the trend of the annual number of cases increased, and the average length of stay decreased. During 2007-2008, a significant decline was found in each indicator. The introduction of the PVL resulted in a health insurance budget saving of 1.9% in 2004, 2.6% in 2005, 3.4% in 2006, 5.6% in 2007, and 3.2% in 2008. We found the lowest reimbursement rate per DRG cost-weight at the university medical schools (HUF 138,200 or € 550) and children's hospitals (HUF 132,547 or € 528), whereas the highest was at the county hospitals (HUF 143,451 or € 571) and city hospitals (HUF 142, 082 or € 565). The implementation of the PVL reduced the acute care hospital activity and reimbursement. The effect of the PVL was different on the different types of hospitals, and it had a serious disadvantageous effect on the university medical schools and children's hospitals. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Finite element-based limit load of piping branch junctions under combined loadings

International Nuclear Information System (INIS)

Xuan Fuzhen; Li Peining

2004-01-01

The limit load is an important input parameter in engineering defect-assessment procedures and strength design. In the present work, a total of 100 different piping branch junction models for the limit load calculation were performed under combined internal pressure and moments in use of non-linear finite element (FE) method. Three different existing accumulation rules for limit load, i.e., linear equation, parabolic equation and quadratic equation were discussed on the basis of FE results. A novel limit load solution was developed based on detailed three-dimensional FE limit analyses which accommodated the geometrical parameter influence, together with analytical solutions based on equilibrium stress fields. Finally, six experimental results were provided to justify the presented equation. According to the FE limit analysis, limit load interaction of the piping tees under combined pressure and moments has a relationship with the geometrical parameters, especially with the diameter ratio d/D. The predicted limit loads from the presented formula are very close to the experimental data. The resulting limit load solution is given in a closed form, and thus can be easily used in practice

Inverse Limits

CERN Document Server

Ingram, WT

2012-01-01

Inverse limits provide a powerful tool for constructing complicated spaces from simple ones. They also turn the study of a dynamical system consisting of a space and a self-map into a study of a (likely more complicated) space and a self-homeomorphism. In four chapters along with an appendix containing background material the authors develop the theory of inverse limits. The book begins with an introduction through inverse limits on [0,1] before moving to a general treatment of the subject. Special topics in continuum theory complete the book. Although it is not a book on dynamics, the influen

Probabilistic inference of fatigue damage propagation with limited and partial information

Directory of Open Access Journals (Sweden)

Huang Min

2015-08-01

Full Text Available A general method of probabilistic fatigue damage prognostics using limited and partial information is developed. Limited and partial information refers to measurable data that are not enough or cannot directly be used to statistically identify model parameter using traditional regression analysis. In the proposed method, the prior probability distribution of model parameters is derived based on the principle of maximum entropy (MaxEnt using the limited and partial information as constraints. The posterior distribution is formulated using the principle of maximum relative entropy (MRE to perform probability updating when new information is available and reduces uncertainty in prognosis results. It is shown that the posterior distribution is equivalent to a Bayesian posterior when the new information used for updating is point measurements. A numerical quadrature interpolating method is used to calculate the asymptotic approximation for the prior distribution. Once the prior is obtained, subsequent measurement data are used to perform updating using Markov chain Monte Carlo (MCMC simulations. Fatigue crack prognosis problems with experimental data are presented for demonstration and validation.

High-Speed Imaging of Explosive Droplet Boiling at the Superheat Limit

Science.gov (United States)

Ferris, F. Robert; Hermanson, Jim; Asadollahi, Arash; Esmaeeli, Asghar

2017-11-01

The explosive boiling processes of droplets of diethyl ether (1-2 mm in diameter) at the superheat limit were examined both experimentally and computationally. Experimentally, droplet explosion was studied using a heated bubble column to bring the test droplet to the superheat limit. The droplet fluid was diethyl ether (superheat limit 147 C at 1 bar) with immiscible glycerol employed as the heated host fluid. Tests were carried out at pressures between 0.5 and 4 bar absolute. The pressure rise associated with the explosive boiling event was captured using a piezoelectric quartz pressure transducer with a 1 MHz DAQ system. High-speed imaging of the interfacial behavior during explosive boiling was performed using a Phantom v12.1 camera at a frame rate of up to one million frames per second with the droplets illuminated by diffuse back-lighting. The imaging reveals features of the Rayleigh-Taylor instability at the vapor-liquid interface resulting from the unstable boiling process. Computationally, Direct Numerical Simulations are performed at Southern Illinois University Carbondale to compliment the experimental tests. NSF Award Number 1511152.

Robust test limits

NARCIS (Netherlands)

Albers, Willem/Wim; Kallenberg, W.C.M.; Otten, G.D.

1997-01-01

Because of inaccuracies of the measurement process inspection of manufactured parts requires test limits which are more strict than the given specification limits. Test limits derived under the assumption of normality for product characteristics turn out to violate the prescribed bound on the

JET pump limiter

International Nuclear Information System (INIS)

Sonnenberg, K.; Deksnis, E.; Shaw, R.; Reiter, D.

1988-01-01

JET plans to install two pump limiter modules which can be used for belt-limiter, inner-wall and X-point discharges and, also, for 1-2s as the main limiter. A design is presented which is compatible with two diagnostic systems, and which allows partial removal of the pump limiter to provide access for remote-handling operations. The high heat-flux components are initially cooled during a pulse. Heat is removed between discharges by radiation and pressure contacts to a water-cooled support structure. The pumping edge will be made of annealed pyrolytic graphite. Exhaust efficiency has been estimated, for a 1-d edge model, using a Monte-Carlo calculation of neutral gas transport. When the pump limiter is operated together with other wall components we expect an efficiency of ≅ 5% (2.5 x 10 21 part/s). As a main limiter the efficiency increases to about 10%. (author)

Growth performance, rumen fermentation, nutrient utilization, and metabolic profile of dairy heifers limit-fed distillers dried grains with ad libitum forage.

Science.gov (United States)

Manthey, A K; Anderson, J L

2018-01-01

The objective of this study was to determine the effects of feeding a corn- and soybean-product-based concentrate mix or distillers dried grains with solubles concentrate mix with ad libitum grass hay to dairy heifers. A 16-wk randomized complete block design study was conducted using 24 heifers [18 Holstein and 6 Brown Swiss; 219 ± 2 d of age (±standard deviation); 230 ± 4 kg of body weight] to evaluate the effect of diet on dry matter intake (DMI), growth performance, rumen fermentation, metabolic profile, and nutrient digestibility. Treatments were (1) corn and soybean product concentrate mix, and (2) distillers-dried-grains-with-solubles-based concentrate mix (DDG). Both concentrate mixes were limit-fed at 0.8% of body weight and grass hay was offered ad libitum. Heifers were individually fed using Calan gates and orts were recorded daily at feeding. Heifers were weighed every 2 wk and ration concentrate mix offered was adjusted accordingly. Frame measurements and body condition score were recorded every 2 wk. Rumen fluid was collected via esophageal tubing during wk 12 and 16 for pH, ammonia N, and volatile fatty acid analysis. Jugular blood samples were collected every 4 wk for metabolite and metabolic hormone analysis. Total-tract digestibility of nutrients was evaluated during wk 16 by fecal grab sampling. No treatment by week interactions were observed for any of the growth measurements and growth measurements and DMI did not differ between treatments. A treatment by time interaction was observed for rumen butyrate percentage with heifers fed DDG having a greater percentage. Total volatile fatty acid concentration, acetate molar percentage, and acetate:propionate decreased with the DDG treatment, whereas propionate molar percentage increased. No treatment by week interactions were observed for any of the metabolites or metabolic hormones measured. A tendency was observed for glucose and plasma urea nitrogen concentration to decrease with DDG. Plasma

ALT-I pump limiter results on TEXTOR

International Nuclear Information System (INIS)

Dippel, K.H.; Finken, K.H.; Guthrie, S.E.; Malinowski, M.E.; Pontau, A.E.; Campbell, G.A.; Goebel, D.M.; Conn, R.W.

1985-01-01

The ALT-I pump limiter is used to control hydrogen fluxes from the TEXTOR tokamak. The performance of two different modules, the open fixed geometry (FG) and the closed variable geometry (VG) is discussed. In unpumped scoop limiter operation, the pressure in the ALT-I chamber increases to 3x10 -4 torr(FG) and 2x10 -3 torr(VG). With pumping, the fraction of particles incident on the neutralizer plate that is removed is 25-50%(FG) and 50-80%(VG). These removed particles are estimated to be 2-4(8)%(FG) and 6-13%(VG) of the total plasma outflux (Nsub(e)/tausub(p)). The collection of helium from the plasma using the FG module is approximately half as effective as hydrogen collection. The higher particle removal efficiency for the VG module is attributed to lower neutral backstreaming. (author)

Twist limits for late twisting double somersaults on trampoline.

Science.gov (United States)

Yeadon, M R; Hiley, M J

2017-06-14

An angle-driven computer simulation model of aerial movement was used to determine the maximum amount of twist that could be produced in the second somersault of a double somersault on trampoline using asymmetrical movements of the arms and hips. Lower bounds were placed on the durations of arm and hip angle changes based on performances of a world trampoline champion whose inertia parameters were used in the simulations. The limiting movements were identified as the largest possible odd number of half twists for forward somersaulting takeoffs and even number of half twists for backward takeoffs. Simulations of these two limiting movements were found using simulated annealing optimisation to produce the required amounts of somersault, tilt and twist at landing after a flight time of 2.0s. Additional optimisations were then run to seek solutions with the arms less adducted during the twisting phase. It was found that 3½ twists could be produced in the second somersault of a forward piked double somersault with arms abducted 8° from full adduction during the twisting phase and that three twists could be produced in the second somersault of a backward straight double somersault with arms fully adducted to the body. These two movements are at the limits of performance for elite trampolinists. Copyright © 2017 Elsevier Ltd. All rights reserved.

Bronchoscopic guidance of endovascular stenting limits airway compression.

Science.gov (United States)

Ebrahim, Mohammad; Hagood, James; Moore, John; El-Said, Howaida

2015-04-01

Bronchial compression as a result of pulmonary artery and aortic arch stenting may cause significant respiratory distress. We set out to limit airway narrowing by endovascular stenting, by using simultaneous flexible bronchoscopy and graduated balloon stent dilatation, or balloon angioplasty to determine maximum safe stent diameter. Between August 2010 and August 2013, patients with suspected airway compression by adjacent vascular structures, underwent CT or a 3D rotational angiogram to evaluate the relationship between the airway and the blood vessels. If these studies showed close proximity of the stenosed vessel and the airway, simultaneous bronchoscopy and graduated stent re-dilation or graduated balloon angioplasty were performed. Five simultaneous bronchoscopy and interventional catheterization procedures were performed in four patients. Median age/weight was 33 (range 9-49) months and 14 (range 7.6-24) kg, respectively. Three had hypoplastic left heart syndrome, and one had coarctation of the aorta (CoA). All had confirmed or suspected left main stem bronchial compression. In three procedures, serial balloon dilatation of a previously placed stent in the CoA was performed and bronchoscopy was used to determine the safest largest diameter. In the other two procedures, balloon testing with simultaneous bronchoscopy was performed to determine the stent size that would limit compression of the adjacent airway. In all cases, simultaneous bronchoscopy allowed selection of an ideal caliber of the stent that optimized vessel diameter while minimizing compression of the adjacent airway. In cases at risk for airway compromise, flexible bronchoscopy is a useful tool to guide endovascular stenting. Maximum safe stent diameter can be determined without risking catastrophic airway compression. © 2014 Wiley Periodicals, Inc.

A study on DC hybrid three-phase fault current limiting interrupter for a power distribution system

International Nuclear Information System (INIS)

Shao, Hongtian; Satoh, Tomoyuki; Yamaguchi, Mitsugi; Fukui, Satoshi; Ogawa, Jun; Satoh, Takao; Ishikawa, Hiroyuki

2005-01-01

For the purpose of protecting electric power system, many researches and developments of fault current limiters are being performed. The authors studied a dc hybrid three-phase fault current limiting interrupter (FCLI) composed of a superconducting reactor and an S/N transition element, connected in series each other. The dc hybrid type fault current limiting interrupter can limit a fault current by means of the inductance of high temperature superconducting (HTS) coil together with the normal transition of HTS bulk material (HTSB). In the case of an accident, the normal transition of the bulk material can be accelerated by the magnetic field of the HTS coil. In this paper, the dc hybrid type fault current limiting interrupter for 5.5 km long 6.6 kV-600 A power distribution system is analyzed, and performances of fault current limitation and interruption are confirmed. Moreover, a reclosing operation is discussed for this power distribution system

The importance of human performance and procedures in limiting severe accident risks

International Nuclear Information System (INIS)

Higgins, J.C.

1990-01-01

Due to the defense in depth concept and redundancy in safety systems utilized, complex industrial plants, such as nuclear power plants (NPPs) can be operated safely. This capability has been demonstrated by many years of safe operation by numerous NPPs in the US and abroad. However, the occurrence of severe accidents has also demonstrated that constant vigilance in a number of areas is necessary to ensure continued safe operation. The areas noted as particularly important are Design, Organization and Management, Maintenance, and Operations (Human Performance). 18 refs

Real-time reactor coolant system pressure/temperature limit system

International Nuclear Information System (INIS)

Newton, D.G.; Schemmel, R.R.; Van Scooter, W.E. Jr.

1991-01-01

This patent describes an system, used in controlling the operating of a nuclear reactor coolant system, which automatically calculates and displays allowable reactor coolant system pressure/temperature limits within the nuclear reactor coolant system based upon real-time inputs. It comprises: means for producing signals representative of real-time operating parameters of the nuclear reactor cooling system; means for developing pressure and temperature limits relating the real-time operating parameters of the nuclear reactor coolant system, for normal and emergency operation thereof; means for processing the signals representative of real-time operating parameters of the nuclear reactor coolant system to perform calculations of a best estimate of signals, check manual inputs against permissible valves and test data acquisition hardware for validity and over/under range; and means for comparing the representative signals with limits for the real-time operating parameters to produce a signal for a real-time display of the pressure and temperature limits and of the real-time operating parameters use an operator in controlling the operation of the nuclear reactor coolant system

No evidence for an item limit in change detection.

Directory of Open Access Journals (Sweden)

Shaiyan Keshvari

Full Text Available Change detection is a classic paradigm that has been used for decades to argue that working memory can hold no more than a fixed number of items ("item-limit models". Recent findings force us to consider the alternative view that working memory is limited by the precision in stimulus encoding, with mean precision decreasing with increasing set size ("continuous-resource models". Most previous studies that used the change detection paradigm have ignored effects of limited encoding precision by using highly discriminable stimuli and only large changes. We conducted two change detection experiments (orientation and color in which change magnitudes were drawn from a wide range, including small changes. In a rigorous comparison of five models, we found no evidence of an item limit. Instead, human change detection performance was best explained by a continuous-resource model in which encoding precision is variable across items and trials even at a given set size. This model accounts for comparison errors in a principled, probabilistic manner. Our findings sharply challenge the theoretical basis for most neural studies of working memory capacity.

40 CFR 197.36 - Are there limits on what DOE must consider in the performance assessments?

Science.gov (United States)

2010-07-01

... effects of climate change. The climate change analysis may be limited to the effects of increased water flow through the repository as a result of climate change, and the resulting transport and release of radionuclides to the accessible environment. The nature and degree of climate change may be represented by...

Temperature limit values for touching cold surfaces with the fingertip

NARCIS (Netherlands)

Geng, Q.; Holme, I.; Hartog, E.A. den; Havenith, G.; Jay, O.; Malchaires, J.; Piette, A.; Rintama, H.; Rissanen, S.

2006-01-01

Objectives: At the request of the European Commission and in the framework of the European Machinery Directive, research was performed in five different laboratories to develop specifications for surface temperature limit values for the short-term accidental touching of the fingertip with cold

Emissive limiter bias experiment for improved confinement of tokamaks

International Nuclear Information System (INIS)

Choe, W.; Ono, M.; Darrow, D.S.; Pribyl, P.A.; Liberati, J.R.; Taylor, R.J.

1992-01-01

Experiments have been performed in Ohmic discharges of the UCLA CCT tokamak with a LaB 6 biased limiter, capable of emitting energetic electrons as a technique to improve confinement in tokamaks. To study the effects of emitted electrons, the limiter position, bias voltage, and plasma position were varied. The results have shown that the plasma positioning with respect to the emissive limiter plays an important role in obtaining H-mode plasmas. The emissive cathode must be located close to the last closed flux surface in order to charge up the plasma. As the cathode is moved closer to the wall, the positioning of the plasma becomes more critical since the plasma can easily detach from the cathode and reattach to the wall, resulting in the termination of H-mode. The emissive capability appears to be important for operating at lower bias voltage and reducing impurity levels in the plasma. With a heated cathode, transition to H-mode was observed for V bias ≤ 50 V and I inj ≥ 30 A. At a lower cathode heater current, a higher bias voltage is required for the transition. Moreover, with a lower cathode heater current, the time delay for inducing H-mode becomes longer, which can be attributed to the required time for the self-heating of the cathode to reach the emissive temperature. From this result, we conclude that the capacity for emission can significantly improve the performance of limiter biasing for inducing H-mode transition. With L-mode plasmas, the injection current flowing out of the cathode was generally higher than 100 A

The Development of Early Numeracy Ability in Kindergartners with Limited Working Memory Skills

Science.gov (United States)

Toll, Sylke W. M.; Van Luit, Johannes E. H.

2013-01-01

Research has proven limited working memory skills to be a high risk factor for educational underachievement in mathematics across the primary school years. Less is known, however, about the performance of children with limited working memory skills in early numeracy tasks. The main purpose of the two studies reported in this article is to explore…

Limited versus full sternotomy for aortic valve replacement.

Science.gov (United States)

Kirmani, Bilal H; Jones, Sion G; Malaisrie, S C; Chung, Darryl A; Williams, Richard Jnn

2017-04-10

Aortic valve disease is a common condition that is easily treatable with cardiac surgery. This is conventionally performed by opening the sternum longitudinally down the centre ("median sternotomy") and replacing the valve under cardiopulmonary bypass. Median sternotomy is generally well tolerated, but as less invasive options have become available, the efficacy of limited incisions has been called into question. In particular, the effects of reducing the visibility and surgical access has raised safety concerns with regards to the placement of cannulae, venting of the heart, epicardial wire placement, and de-airing of the heart at the end of the procedure. These difficulties may increase operating times, affecting outcome. The benefits of smaller incisions are thought to include decreased pain; improved respiratory mechanics; reductions in wound infections, bleeding, and need for transfusion; shorter intensive care stay; better cosmesis; and a quicker return to normal activity. To assess the effects of minimally invasive aortic valve replacement via a limited sternotomy versus conventional aortic valve replacement via median sternotomy in people with aortic valve disease requiring surgical replacement. We performed searches of CENTRAL, MEDLINE, Embase, clinical trials registries, and manufacturers' websites from inception to July 2016, with no language limitations. We reviewed references of identified papers to identify any further studies of relevance. Randomised controlled trials comparing aortic valve replacement via a median sternotomy versus aortic valve replacement via a limited sternotomy. We excluded trials that performed other minimally invasive incisions such as mini-thoracotomies, port access, trans-apical, trans-femoral or robotic procedures. Although some well-conducted prospective and retrospective case-control and cohort studies exist, these were not included in this review. Two review authors independently assessed trial papers to extract data

Delay-Limited Capacity in the Low Power Regime

KAUST Repository

Rezki, Zouheir

2016-02-11

Outage performance of the M-block fading with additive white Gaussian noise (BF-AWGN) is investigated in the low-power regime. We consider delay-constrained constant-rate communications with perfect channel state information (CSI) at both the transmitter and the receiver (CSI-TR), under a shortterm power constraint (STPC) and a long-term power constraint (LTPC). Subject to STPC, we show that selection diversity that allocates all the power to the strongest block is asymptotically optimal. Then, we provide a simple characterization of the outage probability in the regime of interest. We quantify the reward due to CSI-TR over the constant-rate constant-power scheme and show that this reward increases with the delay constraint. For instance, for Rayleigh fading, we find that a power gain up to 4.3 dB is achievable. Subject to LTPC, we show that the above guidelines still holds and that the outage performance improves due to the flexibility of the LTPC over the STPC. More interestingly, we prove that LTPC allows zero-outage communication even at low SNR and characterize the delaylimited capacity at low SNR in a simple form. More precisely, we establish that the delay-limited capacity scales linearly with the power constraint, for a given M < 1. Our framework highlights the benefit of fading at low SNR as the delay-limited capacity may outperform the AWGN capacity. For instance, for Rayleigh fading and with M = 3, the delay-limited capacity is 16% higher than the capacity of an AWGN channel.

Status and limitations of multilayer X-ray interference structures

International Nuclear Information System (INIS)

Kortright, J.B.

1996-01-01

Trends in the performance of x-ray multilayer interference structures with periods ranging from 9 to 130 (angstrom) are reviewed. Analysis of near-normal incidence reflectance data vs photon energy reveals that the effective interface with σ in a static Debye-Waller model, describing interdiffusion and roughness, decreases as the multilayer period decreases, and reaches a lower limit of roughly 2 (angstrom). Specular reflectance and diffuse scattering from uncoated and multilayer-coated substrates having different roughness suggest that this lower limit results largely from substrate roughness. The increase in interface width with period thus results from increasing roughness of interdiffusion as the layer thickness increases

40 CFR 63.4567 - How do I establish the emission capture system and add-on control device operating limits during...

Science.gov (United States)

2010-07-01

... system and add-on control device operating limits during the performance test? 63.4567 Section 63.4567... Emission Rate with Add-on Controls Option § 63.4567 How do I establish the emission capture system and add-on control device operating limits during the performance test? During the performance test required...

Assessment of the influence of design limits to the economics of WWER fuel cycle

International Nuclear Information System (INIS)

Dementiev, V.G.; Shishkov, L.K.

2010-01-01

The paper discusses the influence of the reactor parameters limits for normal operation on the economical performance of WWER fuel cycles. It is shown for the typical WWER fuel cycles that decreasing the limits for the main power distribution parameters to 10% leads to decreasing the fuel components of the electricity cost price up to 4-5%. As the nowadays limitations are reached the dependence becomes weaker. (Authors)

Forecasting oilfield economic performance

International Nuclear Information System (INIS)

Bradley, M.E.; Wood, A.R.O.

1994-01-01

This paper presents a general method for forecasting oilfield economic performance that integrates cost data with operational, reservoir, and financial information. Practices are developed for determining economic limits for an oil field and its components. The economic limits of marginal wells and the role of underground competition receive special attention. Also examined is the influence of oil prices on operating costs. Examples illustrate application of these concepts. Categorization of costs for historical tracking and projections is recommended

Simple frequency-dependent tools for analysis of inherent control limitations

Directory of Open Access Journals (Sweden)

Sigurd Skogestad

1991-10-01

Full Text Available By a plant's inherent control limitations we mean the characteristics of the plant which will cause poor control performance irrespective of what controller is used. Another frequently used term is 'dynamic resilience' which is the best closed-loop performance achievable using any controller. Since a plant's dynamic resilience cannot be altered by change of the control algorithm, but only by design modifications, it follows that the term controllability provides a link between process design and process control. In this paper we focus on two aspects of controllability. The plants' sensitivity to disturbances and the limitations imposed by interactions when using decentralized control. We use simple tools such as the RGA, the PRGA (Performance RGA and the closely related Closed Loop Disturbance Gain (CLDG. For example, if kth column of the CLDG is large, then this indicates that disturbance k will be difficult to reject. This may pinpoint the need for modifying the process. The PRGA provides a measure of interaction which also includes one-way coupling. In the paper we apply these measures to distillation column control and fluid catalytic cracker (FCC control.

Moving toroidal limiter

International Nuclear Information System (INIS)

Ikuta, Kazunari; Miyahara, Akira.

1983-06-01

The concept of the limiter-divertor proposed by Mirnov is extended to a toroidal limiter-divertor (which we call moving toroidal limiter) using the stream of ferromagnetic balls coated with a low Z materials such as plastics, graphite and ceramics. An important advantage of the use of the ferromagnetic materials would be possible soft landing of the balls on a catcher, provided that the temperature of the balls is below Curie point. Moreover, moving toroidal limiter would work as a protector of the first wall not only against the vertical movement of plasma ring but also against the violent inward motion driven by major disruption because the orbit of the ball in the case of moving toroidal limiter distributes over the small major radius side of the toroidal plasma. (author)