WorldWideScience

Sample records for dual corrosion performance

  1. Corrosion protection performance of single and dual Plasma Electrolytic Oxidation (PEO) coating for aerospace applications

    International Nuclear Information System (INIS)

    Madhan Kumar, A.; Kwon, Sun Hwan; Jung, Hwa Chul; Shin, Kwang Seon

    2015-01-01

    Plasma Electrolytic Oxidation (PEO) coatings are known to be one of the most appropriate method for corrosion protection of magnesium (Mg) alloy. The improvement of PEO coatings and the optimization of their surface aspects are of major importance. In this current work, the influence of dual PEO coating on strip-cast AZ31 Mg alloy substrate has been evaluated with the aim of improving the surface and corrosion protection aspects. For this purpose, AZ31 Mg substrates are subjected to single and dual PEO processing in silicate and phosphate electrolyte under similar condition. Scanning electron microscopy (SEM) analysis confirmed that the number of pores in PEO coating processed in silicate electrolyte is higher than others. X-ray diffraction analysis of PEO coatings showed that the surface coating is mainly comprised of Mg 2 SiO 4 , Mg 3 (PO 4 ) 2 and MgO with different quantity based on PEO processing. Compared with the AZ31 Mg, the corrosion potential (E corr ) of both type PEO coatings was positively shifted about 250–400 mV and the corrosion current density (i corr ) was lowered by 3-4 orders of magnitude as result of adequate corrosion protection to the Mg alloy in 3.5% NaCl solution. All of the observation obviously showed that the dual PEO coating provides better corrosion protection performance than their respective single due to its synergistic beneficial effect. - Highlights: • Influence of dual PEO coating on AZ31 Mg alloy substrate was evaluated. • XRD confirmed formation of thin MgO inner, Mg 3 (PO 4 ) 2 and Mg 2 SiO 4 outer layer. • SEM results showed uniform coating with no cracks and relatively less micro pores. • Micro hardness of dual PEO coatings is higher than single PEO coatings. • Dual coating provides superior corrosion performance due to its synergistic effect

  2. The dual role of microbes in corrosion.

    Science.gov (United States)

    Kip, Nardy; van Veen, Johannes A

    2015-03-01

    Corrosion is the result of a series of chemical, physical and (micro) biological processes leading to the deterioration of materials such as steel and stone. It is a world-wide problem with great societal and economic consequences. Current corrosion control strategies based on chemically produced products are under increasing pressure of stringent environmental regulations. Furthermore, they are rather inefficient. Therefore, there is an urgent need for environmentally friendly and sustainable corrosion control strategies. The mechanisms of microbially influenced corrosion and microbially influenced corrosion inhibition are not completely understood, because they cannot be linked to a single biochemical reaction or specific microbial species or groups. Corrosion is influenced by the complex processes of different microorganisms performing different electrochemical reactions and secreting proteins and metabolites that can have secondary effects. Information on the identity and role of microbial communities that are related to corrosion and corrosion inhibition in different materials and in different environments is scarce. As some microorganisms are able to both cause and inhibit corrosion, we pay particular interest to their potential role as corrosion-controlling agents. We show interesting interfaces in which scientists from different disciplines such as microbiology, engineering and art conservation can collaborate to find solutions to the problems caused by corrosion.

  3. The dual role of microbes in corrosion

    Science.gov (United States)

    Kip, Nardy; van Veen, Johannes A

    2015-01-01

    Corrosion is the result of a series of chemical, physical and (micro) biological processes leading to the deterioration of materials such as steel and stone. It is a world-wide problem with great societal and economic consequences. Current corrosion control strategies based on chemically produced products are under increasing pressure of stringent environmental regulations. Furthermore, they are rather inefficient. Therefore, there is an urgent need for environmentally friendly and sustainable corrosion control strategies. The mechanisms of microbially influenced corrosion and microbially influenced corrosion inhibition are not completely understood, because they cannot be linked to a single biochemical reaction or specific microbial species or groups. Corrosion is influenced by the complex processes of different microorganisms performing different electrochemical reactions and secreting proteins and metabolites that can have secondary effects. Information on the identity and role of microbial communities that are related to corrosion and corrosion inhibition in different materials and in different environments is scarce. As some microorganisms are able to both cause and inhibit corrosion, we pay particular interest to their potential role as corrosion-controlling agents. We show interesting interfaces in which scientists from different disciplines such as microbiology, engineering and art conservation can collaborate to find solutions to the problems caused by corrosion. PMID:25259571

  4. Improved surface corrosion resistance of WE43 magnesium alloy by dual titanium and oxygen ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Ying [Department of Orthopaedics and Traumatology, The University of Hong Kong, Pokfulam, Hong Kong (China); Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Wu, Guosong; Lu, Qiuyuan [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Wu, Jun [Department of Orthopaedics and Traumatology, The University of Hong Kong, Pokfulam, Hong Kong (China); Xu, Ruizhen [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Yeung, Kelvin W.K., E-mail: wkkyeung@hku.hk [Department of Orthopaedics and Traumatology, The University of Hong Kong, Pokfulam, Hong Kong (China); Chu, Paul K., E-mail: paul.chu@cityu.edu.hk [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

    2013-02-01

    Magnesium alloys are potential biodegradable materials and have attracted much attention due to their outstanding biological performance and mechanical properties. However, their rapid degradation inside the human body cannot meet clinical needs. In order to improve the corrosion resistance, dual titanium and oxygen ion implantation is performed to modify the surface of the WE43 magnesium alloy. X-ray photoelectron spectroscopy is used to characterize the microstructures in the near surface layer and electrochemical impedance spectroscopy, potentiodynamic polarization, and immersion tests are employed to investigate the corrosion resistance of the implanted alloys in simulated body fluids. The results indicate that dual titanium and oxygen ion implantation produces a TiO{sub 2}-containing surface film which significantly enhances the corrosion resistance of WE43 magnesium alloy. Our data suggest a simple and practical means to improve the corrosion resistance of degradable magnesium alloys. - Highlights: ► Surface modification of WE43 magnesium alloy using dual ion implantation ► Dual Ti and O ion implantation produces a homogeneous TiO{sub 2}-containing surface film ► Significant improvement of the alloy corrosion resistance after the dual ion implantation.

  5. The dual role of microbes in corrosion

    NARCIS (Netherlands)

    Kip, D.J.; Van Veen, J.A.

    2015-01-01

    Corrosion is the result of a series of chemical, physical and (micro) biological processes leading to the deterioration of materials such as steel and stone. It is a world-wide problem with great societal and economic consequences. Current corrosion control strategies based on chemically produced

  6. Predicting the Performance of Organic Corrosion Inhibitors

    Directory of Open Access Journals (Sweden)

    David A. Winkler

    2017-12-01

    Full Text Available The withdrawal of effective but toxic corrosion inhibitors has provided an impetus for the discovery of new, benign organic compounds to fill that role. Concurrently, developments in the high-throughput synthesis of organic compounds, the establishment of large libraries of available chemicals, accelerated corrosion inhibition testing technologies, and the increased capability of machine learning methods have made discovery of new corrosion inhibitors much faster and cheaper than it used to be. We summarize these technical developments in the corrosion inhibition field and describe how data-driven machine learning methods can generate models linking molecular properties to corrosion inhibition that can be used to predict the performance of materials not yet synthesized or tested. We briefly summarize the literature on quantitative structure–property relationships models of small organic molecule corrosion inhibitors. The success of these models provides a paradigm for rapid discovery of novel, effective corrosion inhibitors for a range of metals and alloys in diverse environments.

  7. High performance polypyrrole coating for corrosion protection and biocidal applications

    Science.gov (United States)

    Nautiyal, Amit; Qiao, Mingyu; Cook, Jonathan Edwin; Zhang, Xinyu; Huang, Tung-Shi

    2018-01-01

    Polypyrrole (PPy) coating was electrochemically synthesized on carbon steel using sulfonic acids as dopants: p-toluene sulfonic acid (p-TSA), sulfuric acid (SA), (±) camphor sulfonic acid (CSA), sodium dodecyl sulfate (SDS), and sodium dodecylbenzene sulfonate (SDBS). The effect of acidic dopants (p-TSA, SA, CSA) on passivation of carbon steel was investigated by linear potentiodynamic and compared with morphology and corrosion protection performance of the coating produced. The types of the dopants used were significantly affecting the protection efficiency of the coating against chloride ion attack on the metal surface. The corrosion performance depends on size and alignment of dopant in the polymer backbone. Both p-TSA and SDBS have extra benzene ring that stack together to form a lamellar sheet like barrier to chloride ions thus making them appropriate dopants for PPy coating in suppressing the corrosion at significant level. Further, adhesion performance was enhanced by adding long chain carboxylic acid (decanoic acid) directly in the monomer solution. In addition, PPy coating doped with SDBS displayed excellent biocidal abilities against Staphylococcus aureus. The polypyrrole coatings on carbon steels with dual function of anti-corrosion and excellent biocidal properties shows great potential application in the industry for anti-corrosion/antimicrobial purposes.

  8. The Effect of Low-Quantity Cr Addition on the Corrosion Behaviour of Dual-Phase High Carbon Steel

    Directory of Open Access Journals (Sweden)

    Wilson Handoko

    2018-03-01

    Full Text Available Industrial application of high carbon low alloy steel with the dual-phase structure of martensite and austenite has increased drastically in recent years. Due to its excellent compression strength and its high abrasion resistance, this grade of steel has used as a high performance cutting tool and in press machinery applications. By increasing the usage of more corrosive media in industrial practice and increasing the demand for reducing the production cost, it is crucial to understand the effect of the small addition of Cr on the corrosion behaviour of this grade of steel. In this study, this effect was investigated using Secondary Electron Microscopy (SEM and in-situ Atomic Force Microscopy (AFM in the sodium chloride solution. Also, the corrosion rate was measured using the Tafel polarisation curve. It has been found that the small addition of Cr increased the stability of retained austenite, thus improving its corrosion resistance and reducing its corrosion rate. This effect has been acquired through in-situ high resolution topography images in which the samples were submerged in a corrosive solution. It has been demonstrated that the corrosion rate was reduced when the stability of austenite enhanced.

  9. Plant corrosion: prediction of materials performance

    International Nuclear Information System (INIS)

    Strutt, J.E.; Nicholls, J.R.

    1987-01-01

    Seventeen papers have been compiled forming a book on computer-based approaches to corrosion prediction in a wide range of industrial sectors, including the chemical, petrochemical and power generation industries. Two papers have been selected and indexed separately. The first describes a system operating within BNFL's Reprocessing Division to predict materials performance in corrosive conditions to aid future plant design. The second describes the truncation of the distribution function of pit depths during high temperature oxidation of a 20Cr austenitic steel in the fuel cladding in AGR systems. (U.K.)

  10. Corrosion performance tests for reinforcing steel in concrete : technical report.

    Science.gov (United States)

    2009-10-01

    The existing test method used to assess the corrosion performance of reinforcing steel embedded in : concrete, mainly ASTM G 109, is labor intensive, time consuming, slow to provide comparative results, : and can be expensive. However, with corrosion...

  11. Corrosion performance tests for reinforcing steel in concrete : test procedures.

    Science.gov (United States)

    2009-09-01

    The existing test method to assess the corrosion performance of reinforcing steel embedded in concrete, mainly : ASTM G109, is labor intensive, time consuming, slow to provide comparative results, and often expensive. : However, corrosion of reinforc...

  12. Corrosion Performance of Inconel 625 in High Sulphate Content

    Science.gov (United States)

    Ismail, Azzura

    2016-05-01

    Inconel 625 (UNS N06625) is a type of nickel-chromium-molybdenum alloy with excellent corrosion resistance in a wide range of corrosive media, being especially resistant to pitting and crevice corrosion. However, in aggressive environment, Inconel 625 will suffer corrosion attack like other metals. This research compared the corrosion performance of Inconel 625 when exposed to higher sulphate content compared to real seawater. The results reveal that Inconel 625 is excellent in resist the corrosion attack in seawater. However, at increasing temperature, the corrosion resistance of this metal decrease. The performance is same in seawater with high sulphate content at increasing temperature. It can be concluded that sulphate promote perforation on Inconel 625 and become aggressive agents that accelerate the corrosion attack.

  13. Improving the tribological and corrosive properties of MoS2-based coatings by dual-doping and multilayer construction

    Science.gov (United States)

    Shang, Kedong; Zheng, Shaoxian; Ren, Siming; Pu, Jibin; He, Dongqing; Liu, Shuan

    2018-04-01

    The pure MoS2 coating always performs high friction coefficient and short service life when used in high humidity or after long-time storage in humid atmospheric environment. In this study, the MoS2/Pb-Ti composite and MoS2/Pb-Ti multilayer coatings are deposited to improve the corrosion resistance in 3.5 wt% NaCl solution and tribological performance in high humidity condition. The electrochemical impedance spectra and salt spray test shown that the MoS2/Pb-Ti composite and multilayer coatings can inhibit the permeation of oxygen and other corrosive elements, thus resulting a high corrosion resistance. Furthermore, compared with pure MoS2 coating, the tribological performance of the MoS2/Pb-Ti composite and multilayer coatings is also improved significantly owing to the high mechanical properties and compact structure. Moreover, the heterogenous interfaces in MoS2/Pb-Ti multilayer coating play an important role to improve the corrosion resistance and tribological performance of coatings. Overall, the dual-doping and multilayer construction are promising approaches to design the MoS2 coatings as the environmentally adaptive lubricants.

  14. Performance Enhancements Under Dual-task Conditions

    Science.gov (United States)

    Kramer, A. F.; Wickens, C. D.; Donchin, E.

    1984-01-01

    Research on dual-task performance has been concerned with delineating the antecedent conditions which lead to dual-task decrements. Capacity models of attention, which propose that a hypothetical resource structure underlies performance, have been employed as predictive devices. These models predict that tasks which require different processing resources can be more successfully time shared than tasks which require common resources. The conditions under which such dual-task integrality can be fostered were assessed in a study in which three factors likely to influence the integrality between tasks were manipulated: inter-task redundancy, the physical proximity of tasks and the task relevant objects. Twelve subjects participated in three experimental sessions in which they performed both single and dual-tasks. The primary task was a pursuit step tracking task. The secondary tasks required the discrimination between different intensities or different spatial positions of a stimulus. The results are discussed in terms of a model of dual-task integrality.

  15. Bacillus sp. Acting as Dual Role for Corrosion Induction and Corrosion Inhibition with Carbon Steel (CS

    Directory of Open Access Journals (Sweden)

    Santosh K. Karn

    2017-10-01

    Full Text Available Present work investigated the role of five different bacteria species as a corrosion inducer as well as corrosion inhibitor with carbon steel (CS. We observed the ability of different bacteria species on the metal surface attachment, biofilm formation, and determined Peroxidase, Catalase enzyme activity in the detached biofilm from the CS surface. We found that each strain has diverse conduct for surface attachment like DS1 3.3, DS2 2.5, DS3 4.3, DS4 4.0, and DS5 4.71 log cfu/cm2 and for biofilm 8.3 log cfu/cm2. The enzyme Peroxidase, Catalase was found in huge concentration inside the biofilm Peroxidase was maximum for DS4 36.0 U/ml and least for DS3 19.54 U/ml. Whereas, Catalase was highest for DS4, DS5 70.14 U/ml and least 57.2 U/ml for DS2. Scanning electron microscopy (SEM was conducted to examine the biofilm and electrochemical impedance spectroscopy (EIS were utilized to observe corrosion in the presence of bacteria. The electrochemical results confirmed that DS1, DS3, DS4, and DS5 strains have statistically significant MIC-factors (Microbially Influenced Corrosion of 5.46, 8.51, 2.36, and 1.04, while DS2 protective effect factor of 0.89. Weight reduction results with carbon steel likewise supports that corrosion was initiated by DS1 and DS3, while DS2 and DS5 have no any impact though with DS4 we watched less weight reduction however assumed no role in the corrosion. We established the relation of Peroxidase enzyme activity of the isolates. DS1, DS3 and having Peroxidase in the range 22.18, 19.54 U/ml which induce the corrosion whereas DS2 and DS5 having 28.57 and 27.0 U/ml has no any effect and DS4 36 U/ml has inhibitory effect, increasing concentration inhibiting the corrosion. For Catalase DS1, DS3 have 67.28, 61.57 U/ml which induce corrosion while DS2 and DS5 57.71 and 59.14 U/ml also has no effect whereas DS4 70.14 U/ml can inhibit corrosion. Results clearly express that in a specific range both enzymes can induce the corrosion

  16. Phase-field modeling of corrosion kinetics under dual-oxidants

    Science.gov (United States)

    Wen, You-Hai; Chen, Long-Qing; Hawk, Jeffrey A.

    2012-04-01

    A phase-field model is proposed to simulate corrosion kinetics under a dual-oxidant atmosphere. It will be demonstrated that the model can be applied to simulate corrosion kinetics under oxidation, sulfidation and simultaneous oxidation/sulfidation processes. Phase-dependent diffusivities are incorporated in a natural manner and allow more realistic modeling as the diffusivities usually differ by many orders of magnitude in different phases. Simple free energy models are then used for testing the model while calibrated free energy models can be implemented for quantitative modeling.

  17. Microstructure, Corrosion and Magnetic Behavior of an Aged Dual-Phase Stainless Steel

    Science.gov (United States)

    Ziouche, A.; Haddad, A.; Badji, R.; Zergoug, M.; Zoubiri, N.; Bedjaoui, W.; Abaidia, S.

    2018-03-01

    In the present work, the effect of the precipitation phenomena on corrosion and magnetic behavior of an aged dual-phase stainless steel was investigated. Aging treatment caused the precipitation of the σ phase, chromium carbides and secondary austenite, which was accompanied by the shifting of the δ/γ interfaces inside the δ ferrite grains. Aging between 700 and 850 °C strongly deteriorated the pitting corrosion resistance of the studied material. Magnetic investigation of the aged material using the vibration sample magnetic technique revealed the sensitivity of the intrinsic magnetic properties to the smallest microstructural change. This was confirmed by the Eddy current technique that led also to the evaluation of the aging-induced localized corrosion.

  18. High-Temperature, Dual-Atmosphere Corrosion of Solid-Oxide Fuel Cell Interconnects

    Science.gov (United States)

    Gannon, Paul; Amendola, Roberta

    2012-12-01

    High-temperature corrosion of ferritic stainless steel (FSS) surfaces can be accelerated and anomalous when it is simultaneously subjected to different gaseous environments, e.g., when separating fuel (hydrogen) and oxidant (air) streams, in comparison with single-atmosphere exposures, e.g., air only. This so-called "dual-atmosphere" exposure is realized in many energy-conversion systems including turbines, boilers, gasifiers, heat exchangers, and particularly in intermediate temperature (600-800°C) planar solid-oxide fuel cell (SOFC) stacks. It is generally accepted that hydrogen transport through the FSS (plate or tube) and its subsequent integration into the growing air-side surface oxide layer can promote accelerated and anomalous corrosion—relative to single-atmosphere exposure—via defect chemistry changes, such as increased cation vacancy concentrations, decreased oxygen activity, and steam formation within the growing surface oxide layers. Establishment of a continuous and dense surface oxide layer on the fuel side of the FSS can inhibit hydrogen transport and the associated effects on the air side. Minor differences in FSS composition, microstructure, and surface conditions can all have dramatic influences on dual-atmosphere corrosion behaviors. This article reviews high-temperature, dual-atmosphere corrosion phenomena and discusses implications for SOFC stacks, related applications, and future research.

  19. Corrosion resistance of high-performance materials titanium, tantalum, zirconium

    CERN Document Server

    2012-01-01

    Corrosion resistance is the property of a material to resist corrosion attack in a particular aggressive environment. Although titanium, tantalum and zirconium are not noble metals, they are the best choice whenever high corrosion resistance is required. The exceptionally good corrosion resistance of these high–performance metals and their alloys results from the formation of a very stable, dense, highly adherent, and self–healing protective oxide film on the metal surface. This naturally occurring oxide layer prevents chemical attack of the underlying metal surface. This behavior also means, however, that high corrosion resistance can be expected only under neutral or oxidizing conditions. Under reducing conditions, a lower resistance must be reckoned with. Only very few inorganic and organic substances are able to attack titanium, tantalum or zirconium at ambient temperature. As the extraordinary corrosion resistance is coupled with an excellent formability and weldability these materials are very valua...

  20. Dynamic Recrystallization Behavior and Corrosion Resistance of a Dual-Phase Mg-Li Alloy

    Directory of Open Access Journals (Sweden)

    Gang Liu

    2018-03-01

    Full Text Available The hot deformation and dynamic recrystallization behavior of the dual-phase Mg-9Li-3Al-2Sr-2Y alloy had been investigated using a compression test. The typical dual-phase structure was observed, and average of grain size of as-homogenized alloy is about 110 µm. It mainly contains β-Li, α-Mg, Al4Sr and Al2Y phases. The dynamic recrystallization (DRX kinetic was established based on an Avrami type equation. The onset of the DRX process occurred before the peak of the stress–strain flow curves. It shows that the DRX volume fraction increases with increasing deformation temperature or decreasing strain rate. The microstructure evolution during the hot compression at various temperatures and strain rates had been investigated. The DRX grain size became larger with the increasing testing temperature or decreasing strain rate because the higher temperature or lower strain rate can improve the migration of DRX grain boundaries. The fully recrystallized microstructure can be achieved in a small strain due to the dispersed island-shape α-Mg phases, continuous the Al4Sr phases and spheroidal Al2Y particles, which can accelerate the nucleation. The continuous Al4Sr phases along the grain boundaries are very helpful for enhancing the corrosion resistance of the duplex structured Mg-Li alloy, which can prevent the pitting corrosion and filiform corrosion.

  1. Dynamic Recrystallization Behavior and Corrosion Resistance of a Dual-Phase Mg-Li Alloy.

    Science.gov (United States)

    Liu, Gang; Xie, Wen; Wei, Guobing; Yang, Yan; Liu, Junwei; Xu, Tiancai; Xie, Weidong; Peng, Xiaodong

    2018-03-09

    The hot deformation and dynamic recrystallization behavior of the dual-phase Mg-9Li-3Al-2Sr-2Y alloy had been investigated using a compression test. The typical dual-phase structure was observed, and average of grain size of as-homogenized alloy is about 110 µm. It mainly contains β-Li, α-Mg, Al₄Sr and Al₂Y phases. The dynamic recrystallization (DRX) kinetic was established based on an Avrami type equation. The onset of the DRX process occurred before the peak of the stress-strain flow curves. It shows that the DRX volume fraction increases with increasing deformation temperature or decreasing strain rate. The microstructure evolution during the hot compression at various temperatures and strain rates had been investigated. The DRX grain size became larger with the increasing testing temperature or decreasing strain rate because the higher temperature or lower strain rate can improve the migration of DRX grain boundaries. The fully recrystallized microstructure can be achieved in a small strain due to the dispersed island-shape α-Mg phases, continuous the Al₄Sr phases and spheroidal Al₂Y particles, which can accelerate the nucleation. The continuous Al₄Sr phases along the grain boundaries are very helpful for enhancing the corrosion resistance of the duplex structured Mg-Li alloy, which can prevent the pitting corrosion and filiform corrosion.

  2. Effect of flow on corrosion in catenary risers and its corrosion inhibitor performance

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Pedro Altoe; Magalhaes, Alvaro Augusto Oliveira; Silva, Jussara de Mello [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil); Kang, Cheolho; More, Parimal P. [Det Norske Veritas (DNV), Oslo (Norway)

    2009-07-01

    In oil and gas production, multiphase flow is often encountered and a range of different flow patterns can be experienced in pipelines. The flow regime transition and flow characteristics can be changed with the change of pipeline topography, which affects the corrosion and the performance of corrosion inhibitor in these multiphase pipelines. This paper outlines on the effect of inclination on the flow characteristics and their subsequent effect on corrosion rates. Also, this paper presents on the performance of three candidate corrosion inhibitors under severe slugging conditions at low water cut. For the simulation of offshore flow lines and risers, the experiments were carried out in a 44 m long, 10 cm diameter, three different pipeline inclinations of 0, 3 and 45 degrees. Light condensate oil with a viscosity of 2.5 cP at room temperature was used and water cut was 20%. The results indicated that the baseline corrosion rate in 45 degrees showed higher than other inclinations. Each corrosion inhibitor showed a different inhibitor performance. (author)

  3. Performance evaluation of corrosion-affected reinforced concrete ...

    Indian Academy of Sciences (India)

    M B Anoop

    Abstract. A methodology for performance evaluation of reinforced concrete bridge girders in corrosive ... concrete (RC) members of infrastructural systems, espe- ... bility will be useful for making engineering decisions for ...... Water-cement ratio.

  4. Corrosion

    Science.gov (United States)

    Slabaugh, W. H.

    1974-01-01

    Presents some materials for use in demonstration and experimentation of corrosion processes, including corrosion stimulation and inhibition. Indicates that basic concepts of electrochemistry, crystal structure, and kinetics can be extended to practical chemistry through corrosion explanation. (CC)

  5. Corrosion performance of inorganic coatings in seawater

    NARCIS (Netherlands)

    Zhang, X.; Buter, S.J.; Ferrari, G.M.; Westing, E. van; Kowalski, L.

    2011-01-01

    Inorganic coatings are widely used to protect carbon steel hydraulic cylinder rods from wear and corrosion in aggressive offshore environment. Different types of lay-ers such as Ni/Cr, Al2O3, Cr2O3, TiO2, and Inconel 625 layers were applied to the carbon steels by plasma, High Velocity Oxygen Fuel

  6. Corrosion performance of new Zircaloy-2-based alloys

    International Nuclear Information System (INIS)

    Rudling, P.; Mikes-Lindbaeck, M.; Lethinen, B.; Andren, H.O.; Stiller, K.

    1994-01-01

    A material development project was initiated to develop a new zirconium alloy, outside the ASTM specifications for Zircaloy-2 and Zircaloy-4, with optimized hydriding and corrosion properties for both boiling water reactors and pressurized water reactors. A number of different alloys were manufactured. These alloys were long-term corrosion tested in autoclaves at 400 C in steam. Also, a 520 C/24 h steam test was carried out. The zirconium metal microstructure and the chemistry of precipitates were characterized by analytical electron microscopy. The metal matrix chemistry was determined by atom probe analysis. The paper describes the correlations between corrosion material performance and zirconium alloy microstructure

  7. Effect of Wall Shear Stress on Corrosion Inhibitor Film Performance

    Science.gov (United States)

    Canto Maya, Christian M.

    In oil and gas production, internal corrosion of pipelines causes the highest incidence of recurring failures. Ensuring the integrity of ageing pipeline infrastructure is an increasingly important requirement. One of the most widely applied methods to reduce internal corrosion rates is the continuous injection of chemicals in very small quantities, called corrosion inhibitors. These chemical substances form thin films at the pipeline internal surface that reduce the magnitude of the cathodic and/or anodic reactions. However, the efficacy of such corrosion inhibitor films can be reduced by different factors such as multiphase flow, due to enhanced shear stress and mass transfer effects, loss of inhibitor due to adsorption on other interfaces such as solid particles, bubbles and droplets entrained by the bulk phase, and due to chemical interaction with other incompatible substances present in the stream. The first part of the present project investigated the electrochemical behavior of two organic corrosion inhibitors (a TOFA/DETA imidazolinium, and an alkylbenzyl dimethyl ammonium chloride), with and without an inorganic salt (sodium thiosulfate), and the resulting enhancement. The second part of the work explored the performance of corrosion inhibitor under multiphase (gas/liquid, solid/liquid) flow. The effect of gas/liquid multiphase flow was investigated using small and large scale apparatus. The small scale tests were conducted using a glass cell and a submersed jet impingement attachment with three different hydrodynamic patterns (water jet, CO 2 bubbles impact, and water vapor cavitation). The large scale experiments were conducted applying different flow loops (hilly terrain and standing slug systems). Measurements of weight loss, linear polarization resistance (LPR), and adsorption mass (using an electrochemical quartz crystal microbalance, EQCM) were used to quantify the effect of wall shear stress on the performance and integrity of corrosion inhibitor

  8. A dual-task design of corrosion-controlling and osteo-compatible hexamethylenediaminetetrakis- (methylene phosphonic acid) (HDTMPA) coating on magnesium for biodegradable bone implants application.

    Science.gov (United States)

    Zhao, Sheng; Chen, Yingqi; Liu, Bo; Chen, Meiyun; Mao, Jinlong; He, Hairuo; Zhao, Yuancong; Huang, Nan; Wan, Guojiang

    2015-05-01

    Magnesium as well as its alloys appears increasingly as a revolutionary bio-metal for biodegradable implants application but the biggest challenges exist in its too fast bio-corrosion/degradation. Both corrosion-controllable and bio-compatible Mg-based bio-metal is highly desirable in clinic. In present work, hexamethylenediaminetetrakis (methylenephosphonic acid) [HDTMPA, (H2 O3 P-CH2 )2 -N-(CH2 )6 -N-(CH2 -PO3 H2 )2 ], as a natural and bioactive organic substance, was covalently immobilized and chelating-deposited onto Mg surface by means of chemical conversion process and dip-coating method, to fullfill dual-task performance of corrosion-protective and osteo-compatible functionalities. The chemical grafting of HDTMPA molecules, by participation of functional groups on pretreated Mg surface, ensured a firmly anchored base layer, and then sub-sequential chelating reactions of HDTMPA molecules guaranteed a homogenous and dense HDTMPA coating deposition on Mg substrate. Electrochemical corrosion and immersion degradation results reveal that the HDTMPA coated Mg provides a significantly better controlled bio-corrosion/degradation behavior in phosphate buffer saline solution as compared with untreated Mg from perspective of clinic requirement. Moreover, the HDTMPA coated Mg exhibits osteo-compatible in that it induces not only bioactivity of bone-like apatite precipitation but also promotes osteoblast cells adhesion and proliferation. Our well-controlled biodegradable and biocompatible HDTMPA modified Mg might bode well for next generation bone implant application. © 2014 Wiley Periodicals, Inc.

  9. Investigation of electrochemical corrosion behavior in a 3.5 wt.% NaCl solution of boronized dual-phase steel

    International Nuclear Information System (INIS)

    Kayali, Yusuf; Anaturk, Bilal

    2013-01-01

    Highlights: ► Corrosion behaviors in a 3.5% NaCl solution of boronized Dual-Phase (DP) steels were examined. ► The martensite ratio increased with an increase in the intercritical annealing temperature. ► The corrosion resistance decreased with increase of the martensite ratio. ► The boride layer increased the corrosion resistance of DP steel 2–3-fold. ► The superior properties of DP steel as well as poor corrosion properties were improved by the boriding process. - Abstract: In this study, corrosion behaviors of boronized and non-boronized dual-phase steel were investigated with Tafel extrapolation and linear polarization methods in a 3.5 wt.% NaCl solution. Microstructure analyses show that the boride layer on the dual-phase steel surface had a flat and saw smooth morphology. It was detected by X-ray diffraction (XRD) analysis that the boride layer contained FeB and Fe 2 B phases. The amount of martensite increases with an increase in the intercritical annealing temperature. Both the amount of martensite and the morphology of the phase constituents have an influence on the corrosion behavior of dual-phase steel. A higher corrosion tendency was observed with an increased amount of martensite. The corrosion resistance of boronized dual-phase steel is higher compared with that of dual-phase steel

  10. Performance of HVOF carbide coatings under erosion/corrosion

    International Nuclear Information System (INIS)

    Simard, S.; Arsenault, B.; Legoux, J.G.; Hawthorne, H.M.

    1999-01-01

    Cermet based materials are known to have an excellent performance under several wear conditions. High velocity oxy-fuel (HVOF) technology allows the deposition of such hard materials in the form of protective coatings onto different surfaces. Under slurry erosion, the performance of the coatings is influenced by the occurrence of corrosion reactions on the metallic matrix. Indeed, wet conditions promote the dissolution of metallic binder resulting in a potential synergic effect between the corrosion and wear mechanisms. The composition of the metallic matrix plays a key role on the stability of the coatings and their degradation rate. In this work, four coatings based on tungsten carbide embedded in different metallic binders were evaluated with regard to corrosion and wear. (author)

  11. Dual-stroke heat pump field performance

    Science.gov (United States)

    Veyo, S. E.

    1984-11-01

    Two nearly identical proprototype systems, each employing a unique dual-stroke compressor, were built and tested. One was installed in an occupied residence in Jeannette, Pa. It has provided the heating and cooling required from that time to the present. The system has functioned without failure of any prototypical advanced components, although early field experience did suffer from deficiencies in the software for the breadboard micro processor control system. Analysis of field performance data indicates a heating performance factor (HSPF) of 8.13 Stu/Wa, and a cooling energy efficiency (SEER) of 8.35 Scu/Wh. Data indicate that the beat pump is oversized for the test house since the observed lower balance point is 3 F whereas 17 F La optimum. Oversizing coupled with the use of resistance heat ot maintain delivered air temperature warmer than 90 F results in the consumption of more resistance heat than expected, more unit cycling, and therefore lower than expected energy efficiency. Our analysis indicates that with optimal mixing the dual stroke heat pump will yield as HSFF 30% better than a single capacity heat pump representative of high efficiency units in the market place today for the observed weather profile.

  12. STEEL CORROSION AT 600°C IN SINGLE AND DUAL CONDITION IN OXYFUEL ATMOSPHERE

    Directory of Open Access Journals (Sweden)

    Daniel Massari de Souza Coelho

    2014-10-01

    Full Text Available Coal-fired power plants using the Oxyfuel process are being developed to produce electricity with zero CO2 emission. Steels used in this and other processes are often exposed to different atmospheres in each side of the material, especially in heat exchangers and solid oxide fuel cells. Some studies have shown that steels exposed to different hydrogen partial pressures in each side have a different corrosion behavior from steels exposed to a single atmosphere condition. In this investigation, two experimental steels were studied at 600°C and 1 atm in dual atmospheres containing water vapor in one side and flue gas in the other and they were compared to steels oxidized in single atmospheres. The gas composition used is similar to the ones found in Oxyfuel coal power plants, where there is a great concentration of CO2, and also H2O and SO2. Analyses were made using SEM and TEM.

  13. Wear and corrosion performance of metallurgical coatings in sodium

    International Nuclear Information System (INIS)

    Johnson, R.N.; Farwick, D.G.

    1980-01-01

    The friction, wear, and corrosion performance of several metallurgical coatings in 200 to 650 0 C sodium are reviewed. Emphasis is placed on those coatings which have successfully passed the qualification tests necessary for acceptance in breeder reactor environments. Tests include friction, wear, corrosion, thermal cycling, self-welding, and irradiation exposure under as-prototypic-as-possible service conditions. Materials tested were coatings of various refractory metal carbides in metallic binders, nickel-base and cobalt-base alloys and intermetallic compounds such as the aluminides and borides. Coating processes evaluated included plasma spray, detonation gun, sputtering, spark-deposition, and solid-state diffusion

  14. Corrosion performance of iron aluminides in fossil energy environments

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K. [Argonne National Lab., IL (United States). Energy Technology Div.

    1997-12-01

    Corrosion of metallic structural materials in complex gas environments of coal gasification and combustion is a potential problem. The corrosion process is dictated by concentrations of two key constituents: sulfur as H{sub 2}S or SO{sub 2} and chlorine as HCl. This paper presents a comprehensive review of the current status of the corrosion performance of alumina scales that are thermally grown on Fe-base alloys, including iron aluminides, in multicomponent gas environments of typical coal-conversion systems. Mechanisms of scale development/breakdown, performance envelopes for long-term usage of these materials, approaches to modifying the surfaces of engineering alloys by cladding or coating them with intermetallics, and in-service experience with these materials are emphasized. The results are compared with the performance of chromia-forming alloys in similar environments. The paper also discusses the available information on corrosion performance of alloys whose surfaces were enriched with Al by the electrospark deposition process or by weld overlay techniques.

  15. Corrosion performance of epoxy-coated reinforcement in aggressive environments

    Science.gov (United States)

    Vaca Cortes, Enrique

    The objective of this research was to investigate the integrity and corrosion performance of epoxy-coated reinforcement in aggressive environments. A series of experimental studies were conducted: (a) hot water immersion and knife adhesion testing for assessment of coating adhesion; (b) materials and procedures for repairing coating damage; (c) degree of mechanical damage caused during concrete placement when using metal head and rubber head vibrators; (d) accelerated corrosion of coated bars embedded in macrocell and beam specimens placed in a corrosive environment for more than four years. The effects of coating condition and amount of damage, repaired vs. unrepaired damage, bar fabrication, and concrete cracking were studied. Regardless of coating condition, the performance of epoxy-coated bars was better than that of uncoated bars. Unlike black bars, coated bars did not exhibit deep pitting or substantial loss of cross section at crack locations. Damage to epoxy coating was the most significant factor affecting corrosion performance. Bars with coating in good condition, without any visible damage, performed best. The greater the size and frequency of damage, the more severe and extensive the amount of corrosion. The performance of bars that were fabricated or bent after coating was worse than that of coated straight bars. Mixing coated and uncoated bars in the same concrete member led to undesirable performance. Patching damaged coating reduced but did not prevent corrosion, particularly at bar ends. The most important factor in coating repair was the type and properties of the patching material. Surface preparation prior to coating had little effect. The absence of cracks in the concrete delayed, but did not prevent the onset of corrosion of coated bars. During consolidation of concrete, rubber head vibrators caused less damage to epoxy-coated reinforcement than did comparable metal heads. Hot water and adhesion tests were useful and practical for evaluating

  16. 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

  17. Corrosion protection performance of palm and mineral oil media

    International Nuclear Information System (INIS)

    Wan Nik Sani, W.B.; Ani, F.N.; Masjuki, H.H.

    2002-01-01

    In European forest, especially Scandinavian, almost all forest machines are filled with biodegradable fluid. The fluid is of synthetic type. The ratio between the lowest cost of mineral oil and the synthetic fluid is about 1:4. The high cost of this biodegradable fluid can be a major obstacle to be used in developing countries. Malaysia and South East Asia are known for its natural beauties. However, a spill of mineral based oils to their land and seas may result in long term water and soil contamination. Thus crop or agricultural based oil product can provide the solution to this problem. However, considering the demand placed on the oil in service, the service performance such as relation to component compatibility with the crop based oil is crucial to be investigated. The ability of crop based oils to protect and reduce corrosion formation is still unexplored. It is important for each oil to preserve its oxidation stability and remain non-corrosive during service. This paper reports the results of copper corrosion tests. The test includes mass change monitoring, oxide scales and microscopic analysis using Scanning Electron Microscope (SEM). Relative Increase of total acid number and weight loss during copper immersion has proved that metal corrosion in contact with oil was caused by oil degradation that produces acidic compounds. Coppers that were immersed in oil temperature of 60 0 C show that increase of temperature in presence of transition metal induces oil degradation. (Author)

  18. Corrosion performance of tube support materials

    International Nuclear Information System (INIS)

    Malagola, P.

    1985-01-01

    The problem of denting in steam generators leads to change in the conception of the tube support plates. A new material is now used for this component, a 13% Cr steel, which composition has been adjusted for weldability and mechanical resistance criteria. The geometry of trefoil support plate (TSP) has also been improved, using a broached TSP (quadrifoiled holes) instead of a drilled TSP. Tests have been performed on 13% Cr and C-steel broached TSP, and drilled TSP, to confirm the better resistance to denting of this new configuration

  19. Musical expertise has minimal impact on dual task performance.

    Science.gov (United States)

    Cocchini, Gianna; Filardi, Maria Serena; Crhonkova, Marcela; Halpern, Andrea R

    2017-05-01

    Studies investigating effect of practice on dual task performance have yielded conflicting findings, thus supporting different theoretical accounts about the organisation of attentional resources when tasks are performed simultaneously. Because practice has been proven to reduce the demand of attention for the trained task, the impact of long-lasting training on one task is an ideal way to better understand the mechanisms underlying dual task decline in performance. Our study compared performance during dual task execution in expert musicians compared to controls with little if any musical experience. Participants performed a music recognition task and a visuo-spatial task separately (single task) or simultaneously (dual task). Both groups showed a significant but similar performance decline during dual tasks. In addition, the two groups showed a similar decline of dual task performance during encoding and retrieval of the musical information, mainly attributed to a decline in sensitivity. Our results suggest that attention during dual tasks is similarly distributed by expert and non-experts. These findings are in line with previous studies showing a lack of sensitivity to difficulty and lack of practice effect during dual tasks, supporting the idea that different tasks may rely on different and not-sharable attentional resources.

  20. 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...

  1. Comparative performance analysis of a dual-solenoid mechanical oscillator

    International Nuclear Information System (INIS)

    Lee, V C C; Lee, H V; Harno, H G; Woo, K C

    2015-01-01

    An innovative dual-solenoid electro-mechanical-vibro-impact system has been constructed and experimentally studied. Comparative studies against a mechanical spring system and a permanent magnet system have been performed, where it is shown that the dual-solenoid system is able to produce oscillations better than the permanent magnet system and more energy efficiently. Comparison with a higher-powered dual solenoid system has also been conducted where a stationary solenoid has shown to be a more dominant parameter. In addition, it is also discovered that a mechanical oscillator in the dual-solenoid system is independent of the angular frequency. (paper)

  2. Performance of epoxy-nanocomposite under corrosive environment

    Directory of Open Access Journals (Sweden)

    2007-06-01

    Full Text Available Nanocomposite materials consisting of polymeric matrix materials and natural or synthetic layered minerals like clay are currently an expanding field of study because these new materials often exhibit a wide range of improved properties over their unmodified starting polymers. Epoxy/organoclay nanocomposites have been prepared by intercalating epoxy into the organoclay via direct mixing process. The clay exfoliation was monitored by X-ray diffraction (XRD and transmission electron microscopy (TEM. Water diffusion and sulfuric acid corrosion resistance of epoxy-based nanocomposites were evaluated. Diffusion was studied through epoxy samples containing up to 6 phr (parts per hundred resin of an organically treated montmorillonite. The diffusion of the environmental solution was measured by noting the increase in weight of the samples as a function of immersion time in these solutions at 80°C. The effect of the degree of exfoliation of the organoclay on water barrier and corrosion resistance was specifically studied. The data have been compared to those obtained from the neat epoxy resin to evaluate the diffusion properties of the nanocomposites. The flexural strength of the epoxy/organoclay nanocomposites samples made was examined to compare their mechanical performance under corrosive conditions as a function of immersion time and temperature. It was found, that the organoclay was mainly intercalated with some exfoliation and that addition of the organoclay yields better flexural strength retention under immersion into sulfuric acid.

  3. Study on the Synthesis and Corrosion Inhibition Performance of Mannich-Modified Imidazoline

    Directory of Open Access Journals (Sweden)

    Xiangjun Kong

    2016-07-01

    Full Text Available A novel Mannich-modified imidazoline (MMI as cationic emulsifier was synthesised for corrosion harm reduction, through three steps — acylation, cyclization, and Mannich reaction. The surface activity was characterized by determination of surface tensions and critical micelle concentration (CMC. The corrosion inhibition performance of five types of steels in the simulated corrosion solution in the presence of the MMI was investigated by static weight loss tests. The results showed that the MMI had good surface activities, with CMC of 19.8 μg g−1 and surface tension of 36.4 mN m−1. The corrosion test results indicated that the corrosion rates of different materials were decreased significantly, and degrees of corrosion inhibition were always higher than 80.0 %. The main inhibition mechanism was most likely due to the adsorption of the corrosion inhibitor on the steel surface, leading to the prevention of corrosion medium from the metal surface.

  4. A high performance dual revised simplex solver

    OpenAIRE

    Hall, Julian; Huangfu, Qi

    2012-01-01

    When solving families of related linear programming (LP) problems and many classes of single LP problems, the simplex method is the preferred computational technique. Hitherto there has been no efficient parallel implementation of the simplex method that gives good speed-up on general, large sparse LP problems. This paper presents a variant of the dual simplex method and a prototype parallelisation scheme. The resulting implementation, ParISS, is efficient when run in serial and offers modest...

  5. The Corrosion of High Performance Steel in Adverse Environments

    International Nuclear Information System (INIS)

    Cook, Desmond C.

    2005-01-01

    The corrosion products that have formed on weathering steel bridges exposed to different weather conditions in the United States have been evaluated. They have been analyzed by spectroscopic techniques to determine the relationship between protective and non-protective rust coatings, and their relationship to the exposure conditions. Bridges constructed recently using High Performance Steel, as well as older bridges built with Type A588B weathering steel, were evaluated for corrosion performance of the rust coatings. In locations where the steel is subjected to regular wet-dry cycling, where the surface is wet for less than about 20% of the time, a protective patina starts to form after a few months exposure, and continues to an adherent, impervious coating after a decade. The protective patina is characterized by the formation of only goethite and lepidocrocite. The goethite makes up about 80% of the rust, and itself consists of a nanophase component, 40%, or infrequent drying cycles (regions close to waterways, fog or having high humidity), the weathering steel forms a rust coating that consists of a large amount of maghemite, and goethite that contains very little of the nanophase component. The rust coating ex-foliates from the steel and is not protective. Under exposure conditions in which chlorides are deposited onto the weathering steel surface (marine or de-icing salt locations), the protective patina also does not form. Instead, the rust coating consists of a large fraction of akaganeite that forms at the expense of the lepidocrocite and nanophase goethite. The bridges exposed to high chloride concentrations, 1.5 wt%, and therefore having no protective patina, have corrosion rates measured to be 6 times larger than expected for weathering steel with the protective patina

  6. Corrosion Protection of Al Alloys for Aircraft by Coatings With Advanced Properties and Enhanced Performance

    National Research Council Canada - National Science Library

    Bierwagen, Gordon; Croll, Stuart; Webster, Dean; Tallman, Dennis; Huo, Qun; Allahar, Brian; Su, Quan; Bonitz, Verena; Fernando, Dilhan; Wang, Duhua

    2007-01-01

    The report presents research that addresses research performed at NDSU for environmentally compliant corrosion protection in coatings systems of greatly extended lifetimes for present and future aircraft...

  7. Corrosion performance of several metals in plutonium nitrate solution

    International Nuclear Information System (INIS)

    Takeda, Seiichiro; Nagai, Takayuki; Yasu, Shozo; Koizumi, Tsutomu

    1995-01-01

    Corrosion behavior of several metals exposed in plutonium nitrate solution was studied. Plutonium nitrate solution with the plutonium concentration ranging from 0.01 to 300 g/l was used as a corrosive medium. Specimens tested were type 304 ULC (304 ULC) stainless steel, type 310 Nb (310 Nb) stainless steel, titanium (Ti), titanium-5% tantalum alloy (Ti-5Ta), and zirconium (Zr). Corrosion behavior of these metals in plutonium nitrate solution was evaluated through examining electrochemical characteristics and corrosion rates obtained by weight loss measurement. From the results of the corrosion tests, it was found that the corrosion rate of stainless steels i.e. 304 ULC and 310 Nb, increases by the presence of plutonium in nitric acid solution. The corrosion potential of the stainless steels shifted linearly towards the noble direction as the concentration of plutonium increases. It is thought that the shifts in corrosion potential of the stainless steels to the noble direction results an increase in anodic current and, hence, corrosion rate. Valve metals, i.e. Ti, Ti-5Ta and Zr, showed good corrosion resistance over the whole range of plutonium concentration examined here. (author)

  8. Cognitive and motor dual task gait training improve dual task gait performance after stroke - A randomized controlled pilot trial.

    Science.gov (United States)

    Liu, Yan-Ci; Yang, Yea-Ru; Tsai, Yun-An; Wang, Ray-Yau

    2017-06-22

    This study investigated effects of cognitive and motor dual task gait training on dual task gait performance in stroke. Participants (n = 28) were randomly assigned to cognitive dual task gait training (CDTT), motor dual task gait training (MDTT), or conventional physical therapy (CPT) group. Participants in CDTT or MDTT group practiced the cognitive or motor tasks respectively during walking. Participants in CPT group received strengthening, balance, and gait training. The intervention was 30 min/session, 3 sessions/week for 4 weeks. Three test conditions to evaluate the training effects were single walking, walking while performing cognitive task (serial subtraction), and walking while performing motor task (tray-carrying). Parameters included gait speed, dual task cost of gait speed (DTC-speed), cadence, stride time, and stride length. After CDTT, cognitive-motor dual task gait performance (stride length and DTC-speed) was improved (p = 0.021; p = 0.015). After MDTT, motor dual task gait performance (gait speed, stride length, and DTC-speed) was improved (p = 0.008; p = 0.008; p = 0.008 respectively). It seems that CDTT improved cognitive dual task gait performance and MDTT improved motor dual task gait performance although such improvements did not reach significant group difference. Therefore, different types of dual task gait training can be adopted to enhance different dual task gait performance in stroke.

  9. Performance of RC columns with partial length corrosion

    International Nuclear Information System (INIS)

    Wang Xiaohui; Liang Fayun

    2008-01-01

    Experimental and analytical studies on the load capacity of reinforced concrete (RC) columns with partial length corrosion are presented, where only a fraction of the column length was corroded. Twelve simply supported columns were eccentrically loaded. The primary variables were partial length corrosion in tensile or compressive zone and the corrosion level within this length. The failure of the corroded column occurs in the partial length, mainly developed from or located nearby or merged with the longitudinal corrosion cracks. For RC column with large eccentricity, load capacity of the column is mainly influenced by the partial length corrosion in tensile zone; while for RC column with small eccentricity, load capacity of the column greatly decreases due to the partial length corrosion in compressive zone. The destruction of the longitudinally mechanical integrality of the column in the partial length leads to this great reduction of the load capacity of the RC column

  10. Corrosion and characterisation of dual phase Mg–Li–Ca alloy in Hank’s solution: The influence of microstructural features

    International Nuclear Information System (INIS)

    Zeng, Rong-Chang; Sun, Lu; Zheng, Yu-Feng; Cui, Hong-Zhi; Han, En-Hou

    2014-01-01

    Highlights: •A schematic four-layered structural model of the natural oxide film has been constructed. •A novel concept for the Pilling–Bedworth ratios of chemical compounds is proposed. •Grain refinement in the microstructure leads to a shift from pitting corrosion to overall corrosion. •A method to characterise the corrosion rate of dual phase Mg–Li–Ca alloys is proposed. -- Abstract: The influence of the microstructure and the oxide film of the Mg–9.29Li–0.88Ca alloy on its corrosion behaviour was investigated using SEM, EPMA, XPS and corrosion measurements. The results demonstrated that the fine-grained microstructure improved the mechanical and corrosion resistance of the alloy and shifted pitting corrosion to overall corrosion. The oxide film contained a multi-layered structure, with the outer layer being enriched in lithium-bearing compounds; the interior layer predominantly consisting of oxides, hydroxides and carbonates of lithium and magnesium; and the bottom layer containing oxides. The Pilling–Bedworth ratio for chemical compounds was proposed, and the corrosion rates were characterised

  11. Adverse local tissue reaction arising from corrosion at the femoral neck-body junction in a dual-taper stem with a cobalt-chromium modular neck.

    Science.gov (United States)

    Cooper, H John; Urban, Robert M; Wixson, Richard L; Meneghini, R Michael; Jacobs, Joshua J

    2013-05-15

    Femoral stems with dual-taper modularity were introduced to allow additional options for hip-center restoration independent of femoral fixation in total hip arthroplasty. Despite the increasing availability and use of these femoral stems, concerns exist about potential complications arising from the modular neck-body junction. This was a multicenter retrospective case series of twelve hips (eleven patients) with adverse local tissue reactions secondary to corrosion at the modular neck-body junction. The cohort included eight women and three men who together had an average age of 60.1 years (range, forty-three to seventy-seven years); all hips were implanted with a titanium-alloy stem and cobalt-chromium-alloy neck. Patients presented with new-onset and increasing pain at a mean of 7.9 months (range, five to thirteen months) following total hip arthroplasty. After serum metal-ion studies and metal artifact reduction sequence (MARS) magnetic resonance imaging (MRI) revealed abnormal results, the patients underwent hip revision at a mean of 15.2 months (range, ten to twenty-three months). Tissue specimens were examined by a single histopathologist, and the retrieved implants were studied with use of light and scanning electron microscopy. Serum metal levels demonstrated greater elevation of cobalt (mean, 6.0 ng/mL) than chromium (mean, 0.6 ng/mL) or titanium (mean, 3.4 ng/mL). MRI with use of MARS demonstrated adverse tissue reactions in eight of nine patients in which it was performed. All hips showed large soft-tissue masses and surrounding tissue damage with visible corrosion at the modular femoral neck-body junction. Available histology demonstrated large areas of tissue necrosis in seven of ten cases, while remaining viable capsular tissue showed a dense lymphocytic infiltrate. Microscopic analysis was consistent with fretting and crevice corrosion at the modular neck-body interface. Corrosion at the modular neck-body junction in dual-tapered stems with a modular

  12. Ultimate strength performance of tankers associated with industry corrosion addition practices

    Directory of Open Access Journals (Sweden)

    Kim Do Kyun

    2014-09-01

    Full Text Available In the ship and offshore structure design, age-related problems such as corrosion damage, local denting, and fatigue damage are important factors to be considered in building a reliable structure as they have a significant influence on the residual structural capacity. In shipping, corrosion addition methods are widely adopted in structural design to prevent structural capacity degradation. The present study focuses on the historical trend of corrosion addition rules for ship structural design and investigates their effects on the ultimate strength performance such as hull girder and stiffened panel of double hull oil tankers. Three types of rules based on corrosion addition models, namely historic corrosion rules (pre-CSR, Common Structural Rules (CSR, and harmonised Common Structural Rules (CSRH are considered and compared with two other corrosion models namely UGS model, suggested by the Union of Greek Shipowners (UGS, and Time-Dependent Corrosion Wastage Model (TDCWM. To identify the general trend in the effects of corrosion damage on the ultimate longitudinal strength performance, the corrosion addition rules are applied to four representative sizes of double hull oil tankers namely Panamax, Aframax, Suezmax, and VLCC. The results are helpful in understanding the trend of corrosion additions for tanker structures

  13. Ultimate strength performance of tankers associated with industry corrosion addition practices

    Directory of Open Access Journals (Sweden)

    Do Kyun Kim

    2014-09-01

    Full Text Available In the ship and offshore structure design, age-related problems such as corrosion damage, local denting, and fatigue damage are important factors to be considered in building a reliable structure as they have a significant influence on the residual structural capacity. In shipping, corrosion addition methods are widely adopted in structural design to prevent structural capacity degradation. The present study focuses on the historical trend of corrosion addition rules for ship structural design and investigates their effects on the ultimate strength performance such as hull girder and stiffened panel of double hull oil tankers. Three types of rules based on corrosion addition models, namely historic corrosion rules (pre-CSR, Common Structural Rules (CSR, and harmonised Common Structural Rules (CSRH are considered and compared with two other corrosion models namely UGS model, suggested by the Union of Greek Shipowners (UGS, and Time-Dependent Corrosion Wastage Model (TDCWM. To identify the general trend in the effects of corrosion damage on the ultimate longitudinal strength performance, the corrosion addition rules are applied to four representative sizes of double hull oil tankers namely Panamax, Aframax, Suezmax, and VLCC. The results are helpful in understanding the trend of corrosion additions for tanker structures.

  14. Performance test of a dual-purpose disc agrochemical applicator ...

    African Journals Online (AJOL)

    The performance test of a dual-purpose disc agrochemical applicator for field crop was conducted with view to assess the distribution patterns/droplet sizes and uniformity of spreading and or spraying for the agrochemical application. The equipment performances for both granular and liquid chemical application were ...

  15. Corrosion performance of some titanium-based hard coatings

    International Nuclear Information System (INIS)

    Matthes, B.; Broszeit, E.; Aromaa, J.; Ronkainen, H.; Hannula, S.P.; Leyland, A.; Matthews, A.

    1991-01-01

    Tools and machine parts which could benefit from wear-resistant titanium-based hard films are often subject to corrosive environments. Physically vapour-deposited coatings frequently exhibit porosity and even small defects, which can cause rapid local corrosion of the substrate material; there is therefore a requirement for dense and chemically inert coatings. This paper presents corrosion data for titanium-based hard coatings such as TiN, (Ti, Al)N, Ti(B, N) and TiB 2 and also for multilayered structures where additional aluminium-based insulating surface layers (AlN and Al 2 O 3 ) were deposited. The corrosion resistance and porosity of the films were analysed by electrochemical techniques. The degree of metallic bonding can play a significant role in influencing the corrosion resistance of refractory transition-metal-based ceramic coatings. Here we demonstrate that, under potentiodynamic corrosion test conditions, resistance to corrosive attack was relatively poor for TiB 2 , better for (Ti, Al)N and Ti(B, N) and best for TiN. It is also shown that applying the additional protective aluminium-based insulating surface layers on the coating can further improve corrosion resistance. (orig.)

  16. Evaluation of the performance of a dual fuel engine

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Toshiharu [The Japan Gas Association, Tokyo (Japan). NGV Project Dept.; Daisho, Yasuhiro; Saito, Takeshi [Waseda Univ., Tokyo (Japan)

    1998-12-31

    Dual fuel operation, in which natural gas is mixed with the diesel engine intake air and ignition is by diesel fuel spray, has the advantage that engine conversion is simple. Under high load it has the same high efficiency as a diesel engine and it can be switched to normal diesel operation for long distance running. Also, NO{sub x} and black smoke emissions can also be reduced. However, the disadvantages are to increase HC and CO emissions, to reduce efficiency under low load, and to emit the large amount of NO{sub x} under high load. Waseda University was commissioned by Tokyo Gas Co., Ltd. to conduct research program involving experimentation ragarding a dual fuel engine. It was then discovered that the most effective means of solving the problems mentioned above is Exhaust Gas Recirculation (EGR) and that the effect can be increased by heating the intake air. An old engine before the current emission standard was converted to dual fuel operation. It was found that these measures enables NO{sub x}, black smoke and CO{sub 2} to be reduced while high thermal efficiency was maintained. They did not reach the point of satisfying latest Japanese emission standard. But it seemed that good results would have been obtained, if a base engine with good emissions had been converted for dual fuel operation. The results of assessing the performance of the dual fuel engine at this time are reported here, centered on the effect of EGR and intake heating. (orig.)

  17. Corrosion and corrosion control

    International Nuclear Information System (INIS)

    Khanna, A.S.; Totlani, M.K.

    1995-01-01

    Corrosion has always been associated with structures, plants, installations and equipment exposed to aggressive environments. It effects economy, safety and product reliability. Monitoring of component corrosion has thus become an essential requirement for the plant health and safety. Protection methods such as appropriate coatings, cathodic protection and use of inhibitors have become essential design parameters. High temperature corrosion, especially hot corrosion, is still a difficult concept to accommodate in corrosion allowance; there is a lack of harmonized system of performance testing of materials at high temperatures. In order to discuss and deliberate on these aspects, National Association for Corrosion Engineers International organised a National Conference on Corrosion and its Control in Bombay during November 28-30, 1995. This volume contains papers presented at the symposium. Paper relevant to INIS is indexed separately. refs., figs., tabs

  18. Corrosion performance of prestressing strands in contact with dissimilar grouts.

    Science.gov (United States)

    2013-01-01

    To improve the corrosion protection provided to prestressing strands, anti-bleed grouts are used to fill voids in post-tensioning : ducts that result from bleeding and shrinkage of older Portland Cement grouts. Environmental differences caused by exp...

  19. Corrosion performance of 7075 alloy under laser heat treatment

    Science.gov (United States)

    Liu, Tong; Su, Ruiming; Qu, Yingdong; Li, Rongde

    2018-05-01

    Microstructure, exfoliation corrosion (EXCO), intergranular corrosion (IGC) and potentidynamic polarization test of the 7075 aluminum alloy after retrogression and re-aging (RRA) treatment, and laser retrogression and re-aging (LRRA), respectively, were studied by using scanning electron microscope, and transmission electron microscope (TEM). The results show that after pre-aging, laser treatment (650 W, 2 mm s‑1) and re-aging a lot of matrix precipitates of alloy were precipitated again. The semi-continuous grain boundary precipitates and the wider precipitate-free zones (PFZ) improve the corrosion resistance of the alloy. The corrosion properties of the alloy after LRRA (650 W, 2 mm s‑1) treatment are better than that after RRA treatment.

  20. Novel copper doped Halloysite Nano Tube/silver-poly(pyrrole-co-3,4-ethylenedioxythiophene dual layer coatings on low nickel stainless steel for anti-corrosion applications

    Directory of Open Access Journals (Sweden)

    Palanisamy Karthikeyan

    2018-03-01

    Full Text Available The increase of the diverse and complicated applications of stainless steel in all fields of industry production and various research activities have induced immense efforts in research and fabrication to increase its efficiency and sophisticated to minimize its corrosion by using among others conducting polymer coatings. The present work discusses the corrosion resistant behavior of stainless steel with copolymer and composite dual layer coatings. The coated samples were analyzed by various analytical studies and the results are discussed. The dual layer composite coating Ag-p(Py-co-EDOT thus obtained was uniform in nature and highly adherent to the stainless steel surface, when compared to the monolayer coatings. An antibacterial effect of coating and the coatings against marine and pathogenic bacteria have also been studied. Keywords: Dual layer coatings, Electrochemical studies, Surface analysis, Antibacterial activity, Ion leachout test

  1. Corrosion Performance of New Generation Aluminum-Lithium Alloys for Aerospace Applications

    Science.gov (United States)

    Moran, James P.; Bovard, Francine S.; Chrzan, James D.; Vandenburgh, Peter

    Over the past several years, a new generation of aluminum-lithium alloys has been developed. These alloys are characterized by excellent strength, low density, and high modulus of elasticity and are therefore of interest for lightweight structural materials applications particularly for construction of current and future aircraft. These new alloys have also demonstrated significant improvements in corrosion resistance when compared with the legacy and incumbent alloys. This paper documents the superior corrosion resistance of the current commercial tempers of these materials and also discusses the corrosion performance as a function of the degree of artificial aging. Results from laboratory corrosion tests are compared with results from exposures in a seacoast atmosphere to assess the predictive capability of the laboratory tests. The correlations that have been developed between the laboratory tests and the seacoast exposures provide confidence that a set of available methods can provide an accurate assessment of the corrosion performance of this new generation of alloys.

  2. Are factors related to dual-task performance in people with Parkinson's disease dependent on the type of dual task?

    Science.gov (United States)

    Strouwen, Carolien; Molenaar, Esther A L M; Keus, Samyra H J; Münks, Liesbeth; Heremans, Elke; Vandenberghe, Wim; Bloem, Bastiaan R; Nieuwboer, Alice

    2016-02-01

    Impaired dual-task performance significantly impacts upon functional mobility in people with Parkinson's disease (PD). The aim of this study was to identify determinants of dual-task performance in people with PD in three different dual tasks to assess their possible task-dependency. We recruited 121 home-dwelling patients with PD (mean age 65.93 years; mean disease duration 8.67 years) whom we subjected to regular walking (control condition) and to three dual-task conditions: walking combined with a backwards Digit Span task, an auditory Stroop task and a Mobile Phone task. We measured dual-task gait velocity using the GAITRite mat and dual-task reaction times and errors on the concurrent tasks as outcomes. Motor, cognitive and descriptive variables which correlated to dual-task performance (p task gait velocity and executive function, tested by the alternating intake test, was significantly associated with gait velocity during the Digit Span (R(2) = 0.65; p task (R(2) = 0.62; p task. Age was a surplus determinant of gait velocity while using a mobile phone. Single-task gait velocity and executive function as measured by a verbal fluency switching task were independent determinants of dual-task gait performance in people with PD. In contrast to expectation, these factors were the same across different tasks, supporting the robustness of the findings. Future study needs to determine whether these factors predict dual-task abnormalities prospectively. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Corrosion performance of SiCsubp/6061 Al metal matrix composites in sodium chloride solution

    International Nuclear Information System (INIS)

    Mohmad Soib bin Selamat

    1995-01-01

    The corrosion performance of silicon carbide particle/aluminium metal matrix composites (SiCsubp/Al) were studied in sodium chloride solution by means of electrochemical, microscopic, gravimetric and analytical techniques. The materials under investigation were compocasting processed 6061 Al reinforced with increasing amounts of SiC particles. Potentiostatic polarization tests were done in 0.1M NaCl solutions that were aerated or deaerated to observe overall corrosion behaviour. It was seen that the corrosion potentials did not vary greatly in relation to the amounts of SiCsubp reinforcement. Corrosion tests showed that the degree of corrosion increased with increasing SiCsubp content. SEM analysis technique was used to study the corroded samples and the pitting morphology. By TEM, no intermetallic layer was found at SiC/Al interface. A model for pitting process was proposed

  4. Steam assisted oxide growth on aluminium alloys using oxidative chemistries: Part II corrosion performance

    DEFF Research Database (Denmark)

    Din, Rameez Ud; Jellesen, Morten Stendahl; Ambat, Rajan

    2015-01-01

    the protection provided by steam treatment with HNO3was a function of the concentration of NO3−ions. The coating generated by inclusion of KMnO4showed highest resistance to filiform corrosion. Overall, the performance of the steam treated surfaces under filiform corrosion and AASS test was a result of the local......Surface treatment of aluminium alloys using steam with oxidative chemistries, namely KMnO4 and HNO3 resulted in accelerated growth of oxide on aluminium alloys. Detailed investigation of the corrosion performance of the treated surfaces was carried out using potentiodynamic polarisation...

  5. Mechanical Performance versus Corrosion Damage Indicators for Corroded Steel Reinforcing Bars

    Directory of Open Access Journals (Sweden)

    Silvia Caprili

    2015-01-01

    Full Text Available The experimental results of a testing campaign including tensile and low-cycle fatigue tests on different reinforcing steel bar types in the as-delivered and corroded condition are presented. Experimental data were statistically analyzed adopting ANOVA technique; Performance Indicators (PIs, describing the mechanical performance characteristics of reinforcements, and Corrosion Damage Indicators (CDIs, describing the detrimental effects of corrosion phenomena, were determined and correlated in order to evaluate the influence of corrosion on the behaviour of reinforcing steels, providing useful information for designers in addition to what is presented in current standards.

  6. Microstructural characterisation and corrosion performance of old railway girder bridge steel and modern weathering structural steel

    International Nuclear Information System (INIS)

    Tewary, N.K.; Kundu, A.; Nandi, R.; Saha, J.K.; Ghosh, S.K.

    2016-01-01

    Highlights: • Microstructure and corrosion performance are compared for two structural steels. • Microstructure evolution shows primarily ferrite-pearlite in both the steels. • Steels show higher corrosion rate in 1% HCl solution than in 3.5% NaCl solution. • The corrosion products show the presence of oxide, hydroxide and oxy-hydroxides. • The corroded surface reveals morphologies like flowery, cotton balls and rosette. - Abstract: A comparison on microstructure and corrosion performance has been made between the two structural steels used in old railway girder bridge (Sample A) and modern grades of weathering structural steel (Sample B). The microstructures, viewed under optical microscope and scanning electron microscope (SEM), show mainly ferrite-pearlite phase constituents in both the steels, A and B. The phase fraction analysis shows higher amount of pearlite in steel A compared to that of steel B. The grain size of steel A is larger than that of steel B under identical processing condition. The immersion corrosion test in 3.5% NaCl shows that the corrosion rate of steel A increases with time, while the same for steel B decreases with time. On the other hand, corrosion test in 1% HCl shows that the corrosion rate of both steel A and B is higher as compared to that of NaCl which always decreases with time. The XRD analysis of corrosion products show the presence of many oxides, hydroxide and oxy-hydroxide like Lepidocrocite (γ-FeOOH), Goethite (α-FeOOH), Akaganeite (β-FeOOH), Magnetite (Fe_3O_4) and Maghemite (γ-Fe_2O_3) in both the steels. The SEM images of corroded surfaces reveal different morphologies like flowery, cotton balls and rosette etc. which indicate that the corrosion products primarily contain Lepidocrocite (γ-FeOOH), Goethite (α-FeOOH) and Akaganeite (β-FeOOH).

  7. Corrosion performance of advanced structural materials in sodium.

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.; Momozaki, Y.; Li, M.; Rink, D.L. (Nuclear Engineering Division)

    2012-05-16

    Test Facility, and Clinch River Breeder Reactor. Among the nonmetallic elements discussed, oxygen is deemed controllable and its concentration in sodium can be maintained in sodium for long reactor life by using cold-trap method. It was concluded that among the cold-trap and getter-trap methods, the use of cold trap is sufficient to achieve oxygen concentration of the order of 1 part per million. Under these oxygen conditions in sodium, the corrosion performance of structural materials such as austenitic stainless steels and ferritic steels will be acceptable at a maximum core outlet sodium temperature of {approx}550 C. In the current sodium compatibility studies, the oxygen concentration in sodium will be controlled and maintained at {approx}1 ppm by controlling the cold trap temperature. The oxygen concentration in sodium in the forced convection sodium loop will be controlled and monitored by maintaining the cold trap temperature in the range of 120-150 C, which would result in oxygen concentration in the range of 1-2 ppm. Uniaxial tensile specimens are being exposed to flowing sodium and will be retrieved and analyzed for corrosion and post-exposure tensile properties. Advanced materials for sodium exposure include austenitic alloy HT-UPS and ferritic-martensitic steels modified 9Cr-1Mo and NF616. Among the nonmetallic elements in sodium, carbon was assessed to have the most influence on structural materials since carbon, as an impurity, is not amenable to control and maintenance by any of the simple purification methods. The dynamic equilibrium value for carbon in sodium systems is dependent on several factors, details of which were discussed in the earlier report. The current sodium compatibility studies will examine the role of carbon concentration in sodium on the carburization-decarburization of advanced structural materials at temperatures up to 650 C. Carbon will be added to the sodium by exposure of carbon-filled iron tubes, which over time will enable

  8. Corrosion performance of advanced structural materials in sodium

    International Nuclear Information System (INIS)

    Natesan, K.; Momozaki, Y.; Li, M.; Rink, D.L.

    2012-01-01

    Clinch River Breeder Reactor. Among the nonmetallic elements discussed, oxygen is deemed controllable and its concentration in sodium can be maintained in sodium for long reactor life by using cold-trap method. It was concluded that among the cold-trap and getter-trap methods, the use of cold trap is sufficient to achieve oxygen concentration of the order of 1 part per million. Under these oxygen conditions in sodium, the corrosion performance of structural materials such as austenitic stainless steels and ferritic steels will be acceptable at a maximum core outlet sodium temperature of ∼550 C. In the current sodium compatibility studies, the oxygen concentration in sodium will be controlled and maintained at ∼1 ppm by controlling the cold trap temperature. The oxygen concentration in sodium in the forced convection sodium loop will be controlled and monitored by maintaining the cold trap temperature in the range of 120-150 C, which would result in oxygen concentration in the range of 1-2 ppm. Uniaxial tensile specimens are being exposed to flowing sodium and will be retrieved and analyzed for corrosion and post-exposure tensile properties. Advanced materials for sodium exposure include austenitic alloy HT-UPS and ferritic-martensitic steels modified 9Cr-1Mo and NF616. Among the nonmetallic elements in sodium, carbon was assessed to have the most influence on structural materials since carbon, as an impurity, is not amenable to control and maintenance by any of the simple purification methods. The dynamic equilibrium value for carbon in sodium systems is dependent on several factors, details of which were discussed in the earlier report. The current sodium compatibility studies will examine the role of carbon concentration in sodium on the carburization-decarburization of advanced structural materials at temperatures up to 650 C. Carbon will be added to the sodium by exposure of carbon-filled iron tubes, which over time will enable carbon to diffuse through iron and

  9. Tropical field performance of dual-pass PV tray dryer

    Science.gov (United States)

    Iskandar, A. Noor; Ya'acob, M. E.; Anuar, M. S.

    2017-09-01

    Solar Photovoltaic technology has become the preferable solution in many countries around the globe to solve the ever increasing energy demand of the consumers. In line with the consumer need, food processing technology has huge potentials of integration with the renewable energy resources especially in drying process which consumes the highest electricity loads. Traditionally, the solar dryer technology was applied in agriculture and food industries utilizing the sun's energy for drying process, but this is highly dependable on the weather condition and surrounding factors. This work shares some field performance of the new design of portable dual-pass PV tray dryer for drying crops in an enclosed system. The dual-pass PV tray dryer encompass a lightweight aluminium box structure with dimensions of 1.1m (L) x 0.6m (W) x 0.2m (H) and can hold a load capacity of 300g - 3kg of crop depending on the types of the crops. Experiments of field performance monitoring were conducted in October -November 2016 which justifies a considerable reduction in time and crops quality improvement when using the dual-pass PV tray dryer as compared to direct-sun drying.

  10. Corrosion models for predictions of performance of high-level radioactive-waste containers

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, J.C.; McCright, R.D. [Lawrence Livermore National Lab., CA (United States); Gdowski, G.E. [KMI Energy Services, Livermore, CA (United States)

    1991-11-01

    The present plan for disposal of high-level radioactive waste in the US is to seal it in containers before emplacement in a geologic repository. A proposed site at Yucca Mountain, Nevada, is being evaluated for its suitability as a geologic repository. The containers will probably be made of either an austenitic or a copper-based alloy. Models of alloy degradation are being used to predict the long-term performance of the containers under repository conditions. The models are of uniform oxidation and corrosion, localized corrosion, and stress corrosion cracking, and are applicable to worst-case scenarios of container degradation. This paper reviews several of the models.

  11. Localized corrosion of high performance metal alloys in an acid/salt environment

    Science.gov (United States)

    Macdowell, L. G.; Ontiveros, C.

    1991-01-01

    Various vacuum jacketed cryogenic supply lines at the Space Shuttle launch site at Kennedy Space Center use convoluted flexible expansion joints. The atmosphere at the launch site has a very high salt content, and during a launch, fuel combustion products include hydrochloric acid. This extremely corrosive environment has caused pitting corrosion failure in the thin walled 304L stainless steel flex hoses. A search was done to find a more corrosion resistant replacement material. The study focussed on 19 metal alloys. Tests which were performed include electrochemical corrosion testing, accelerated corrosion testing in a salt fog chamber, and long term exposure at a beach corrosion testing site. Based on the results of these tests, several nickel based alloys were found to have very high resistance to this corrosive environment. Also, there was excellent agreement between the electrochemical tests and the actual beach exposure tests. This suggests that electrochemical testing may be useful for narrowing the field of potential candidate alloys before subjecting samples to long term beach exposure.

  12. Research on Performance and Microstructure of Sewage Pipe Mortar Strengthened with Different Anti-Corrosion Technologies

    Science.gov (United States)

    Mu, Song; Zhou, Huaxin; Shi, Liang; Liu, Jianzhong; Cai, Jingshun; Wang, Feng

    2017-10-01

    Mostly urban underground sewage is the acidic corrosion environment with a high concentration of aggressive ions and microbe, which resulted in performance deterioration and service-life decrease of sewage concrete pipe. In order to effectively protect durability of the concrete pipe, the present paper briefly analysed the main degradation mechanism of concrete pipe attacked by urban underground sewage, and proposed that using penetrating and strengthening surface sealer based on inorganic chemistry. In addition, using index of compressive strength, weight loss and appearance level to investigate the influence of the sealer on corrosion resistance of mortar samples after different dry-wet cycles. Besides, comparative research on effect of the sealer, aluminate cement and admixture of corrosion resistance was also addressed. At last, the SEM technology was used to reveal the improvement mechanism of different technologies of corrosion resistance. The results indicated that the sealer and aluminate cement can significantly improve corrosion resistance of mortar. Besides, the improvement effect can be described as the descending order: the penetrating and strengthening surface sealer > aluminate cement > admixture of corrosion resistance. The mortar sample treated with the sealer displayed the condensed and sound microstructure which proved that the sealer can improve the corrosion resistance to urban underground sewage.

  13. Performance investigation of low-toxic organic corrosion inhibitors in amine treating unit

    International Nuclear Information System (INIS)

    Veawab, A.; Tanthapanichakoon, W.

    2003-01-01

    Amine treating unit is constantly subject to severe corrosion problems leading to extra expenditure and operational limitations. Heavy-metal vanadium compounds are extensively used as corrosion inhibitors to suppress the severe corrosion to an acceptable level. In recent years, the fact that these vanadium compounds are inherently toxic and can potentially pose adverse impacts on the human health and the environment has brought about environmental awareness that causes their uses costly due to the difficulty in waste disposal. To respond to the environmental concern and reduce cost of waste disposal as well as prepare for more stringent regulations for chemical uses, the development of low-toxic corrosion inhibitors is necessary. This work therefore focuses on an investigation of inhibition performance of a number of organic and inorganic compounds that have relatively low toxicity in comparison with conventional inhibitors. The performance evaluation was carried out through corrosion experiments using carbon steel specimens. The experiments were done in 3 and 5 kmol/m 3 monoethanolamine (MEA) solution saturated with CO 2 at 80 o C. It was found that several tested compounds have potential to be effective low-toxic corrosion inhibitors. The promising compounds provide reasonable and in some cases comparable protection performance to the conventional inhibitor. (author)

  14. Short-term memory and dual task performance

    Science.gov (United States)

    Regan, J. E.

    1982-01-01

    Two hypotheses concerning the way in which short-term memory interacts with another task in a dual task situation are considered. It is noted that when two tasks are combined, the activity of controlling and organizing performance on both tasks simultaneously may compete with either task for a resource; this resource may be space in a central mechanism or general processing capacity or it may be some task-specific resource. If a special relationship exists between short-term memory and control, especially if there is an identity relationship between short-term and a central controlling mechanism, then short-term memory performance should show a decrement in a dual task situation. Even if short-term memory does not have any particular identity with a controlling mechanism, but both tasks draw on some common resource or resources, then a tradeoff between the two tasks in allocating resources is possible and could be reflected in performance. The persistent concurrence cost in memory performance in these experiments suggests that short-term memory may have a unique status in the information processing system.

  15. Adsorption and performance of the 2-mercaptobenzimidazole as a carbon steel corrosion inhibitor in EDTA solutions

    International Nuclear Information System (INIS)

    Calderón, J.A.; Vásquez, F.A.; Carreño, J.A.

    2017-01-01

    This study presents a thermodynamic analysis of the adsorption and anti-corrosion performance of 2-mercaptobenzimidazole (2-MBI) on carbon steel in EDTA-Na2 solutions. The adsorption of the inhibitor on the metal surface was studied as a function of the concentration of the inhibiting species and the temperature of the system. The corrosion inhibition efficiency was studied by electrochemical impedance spectroscopy and mass loss tests. The results show that the adsorption of the inhibitor onto the metal surface behaves according to the Langmuir model, following an endothermic process. The inhibitor is chemically adsorbed onto the carbon steel surface. The efficiency of corrosion inhibition was above 93%, which was confirmed by both mass loss tests and the electrochemical impedance technique. The good performance of the corrosion inhibitor was maintained up to 24 h after the inhibitor was added to the corrosive EDTA-Na2 solutions. When the ratio of the volume of solution/exposed area was reduced, a decrease in the area covered by the inhibitor was observed. The best cost/benefit ratio for the corrosion protection of carbon steel was obtained when the number of moles of the inhibitor per surface area was maintained at 2.68 mmol cm"−"2. - Highlights: • Adsorption of the inhibitor on the metal surface is confirmed by thermodynamic data. • Adsorption of the inhibitor onto the metal behaves according to the Langmuir model. • Endothermic adsorption process indicates that the inhibitor is chemically adsorbed. • The efficiency of corrosion inhibition was above 93%. • The good performance of the corrosion inhibitor was maintained up to 24 h.

  16. Adsorption and performance of the 2-mercaptobenzimidazole as a carbon steel corrosion inhibitor in EDTA solutions

    Energy Technology Data Exchange (ETDEWEB)

    Calderón, J.A., E-mail: andres.calderon@udea.edu.co [Centro de Investigación, Innovación y Desarrollo de Materiales –CIDEMAT, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Vásquez, F.A. [Centro de Investigación, Innovación y Desarrollo de Materiales –CIDEMAT, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Carreño, J.A. [Laboratório de H2S, CO2 e Corrosividade, Instituto Nacional De Tecnologia (INT), Av. Venezuela, 82 – Térreo, Anexo 01, Sala 101A, Saúde, Rio de Janeiro, RJ (Brazil)

    2017-01-01

    This study presents a thermodynamic analysis of the adsorption and anti-corrosion performance of 2-mercaptobenzimidazole (2-MBI) on carbon steel in EDTA-Na2 solutions. The adsorption of the inhibitor on the metal surface was studied as a function of the concentration of the inhibiting species and the temperature of the system. The corrosion inhibition efficiency was studied by electrochemical impedance spectroscopy and mass loss tests. The results show that the adsorption of the inhibitor onto the metal surface behaves according to the Langmuir model, following an endothermic process. The inhibitor is chemically adsorbed onto the carbon steel surface. The efficiency of corrosion inhibition was above 93%, which was confirmed by both mass loss tests and the electrochemical impedance technique. The good performance of the corrosion inhibitor was maintained up to 24 h after the inhibitor was added to the corrosive EDTA-Na2 solutions. When the ratio of the volume of solution/exposed area was reduced, a decrease in the area covered by the inhibitor was observed. The best cost/benefit ratio for the corrosion protection of carbon steel was obtained when the number of moles of the inhibitor per surface area was maintained at 2.68 mmol cm{sup −2}. - Highlights: • Adsorption of the inhibitor on the metal surface is confirmed by thermodynamic data. • Adsorption of the inhibitor onto the metal behaves according to the Langmuir model. • Endothermic adsorption process indicates that the inhibitor is chemically adsorbed. • The efficiency of corrosion inhibition was above 93%. • The good performance of the corrosion inhibitor was maintained up to 24 h.

  17. Electrochemical techniques for practical evaluation of corrosion inhibitor effectiveness. Performance of cerium nitrate as corrosion inhibitor for AA2024T3 alloy

    International Nuclear Information System (INIS)

    Rosero-Navarro, N.C.; Curioni, M.; Bingham, R.; Duran, A.; Aparicio, M.; Cottis, R.A.; Thompson, G.E.

    2010-01-01

    In this work, a split-cell technique and image-assisted electrochemical noise analysis, which provide minimal perturbation of the freely corroding system and good time resolution, are proposed as a tool for simultaneous investigation of the corrosion inhibition mechanism and assessment of performance. The results obtained are compared with results from traditional electrochemical impedance spectroscopy, disclosing the advantages of these techniques in the evaluation of inhibitor performance. Specific attention is also given to the investigation of corrosion inhibition by cerium nitrate.

  18. Implementation of Localized Corrosion in the Performance Assessment Model for Yucca Mountain

    International Nuclear Information System (INIS)

    Vivek Jain, S.; David Sevougian; Patrick D. Mattie; Kevin G. Mon; Robert J. Mackinnon

    2006-01-01

    A total system performance assessment (TSPA) model has been developed to analyze the ability of the natural and engineered barriers of the Yucca Mountain repository to isolate nuclear waste over the 10,000-year period following repository closure. The principal features of the engineered barrier system (EBS) are emplacement tunnels (or ''drifts'') containing a two-layer waste package (WP) for waste containment and a titanium drip shield to protect the waste package from seeping water and falling rock, The 20-mm-thick outer shell of the WP is composed of Alloy 22, a highly corrosion-resistant nickel-based alloy. The barrier function of the EBS is to isolate the waste from migrating water. The water and its associated chemical conditions eventually lead to degradation of the waste packages and mobilization of the radionuclides within the packages. There are five possible waste package degradation modes of the Alloy 22: general corrosion, microbially influenced corrosion, stress corrosion cracking, early failure due to manufacturing defects, and localized corrosion. This paper specifically examines the incorporation of the Alloy-22 localized corrosion model into the Yucca Mountain TSPA model, particularly the abstraction and modeling methodology, as well as issues dealing with scaling, spatial variability, uncertainty, and coupling to other sub-models that are part of the total system model

  19. Effect of mixed alloy combinations on fretting corrosion performance of spinal screw and rod implants.

    Science.gov (United States)

    Mali, Sachin A; Singh, Vaneet; Gilbert, Jeremy L

    2017-07-01

    Spinal implants are made from a variety of materials to meet the unique mechanical demands of each application. However, the medical device community has raised concern about mixing dissimilar metals in an implant because of fear of inducing corrosion. There is a lack of systematic studies on the effects of mixing metals on performance of spinal implants, especially in fretting corrosion conditions. Hence, the goal was to determine whether mixing stainless steel (SS316L), titanium alloy (Ti6Al4V) and cobalt chromium (CoCrMo) alloy components in a spinal implant leads to any increased risk of corrosion degradation. Spinal constructs consisting of single assembly screw-connector-rod components were tested using a novel short-term cyclic fretting corrosion test method. A total of 17 alloy component combinations (comprised of SS316L, Ti6Al4V-anodized and CoCrMo alloy for rod, screws and connectors) were tested under three anatomic orientations. Spinal constructs having all SS316L were most susceptible to fretting-initiated crevice corrosion attack and showed higher average fretting currents (∼25 - 30 µA), whereas constructs containing all Ti6Al4V components were less susceptible to fretting corrosion with average fretting currents in the range of 1 - 6 µA. Mixed groups showed evidence of fretting corrosion but they were not as severe as all SS316L group. SEM results showed evidence of severe corrosion attack in constructs having SS316L components. There also did not appear to be any galvanic effects of combining alloys together. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1169-1177, 2017. © 2016 Wiley Periodicals, Inc.

  20. Evaluation of corrosion on the fuel performance of stainless steel cladding

    Directory of Open Access Journals (Sweden)

    de Souza Gomes Daniel

    2016-01-01

    Full Text Available In nuclear reactors, the use of stainless steel (SS as the cladding material offers some advantages such as good mechanical and corrosion resistance. However, its main advantage is the reduction in the amount of the hydrogen released during loss-of-coolant accident, as observed in the Fukushima Daiichi accident. Hence, research aimed at developing accident tolerant fuels should consider SS as an important alternative to existing materials. However, the available computational tools used to analyze fuel rod performance under irradiation are not capable of assessing the effectiveness of SS as the cladding material. This paper addresses the SS corrosion behavior in a modified fuel performance code in order to evaluate its effect on the global fuel performance. Then, data from the literature concerning to SS corrosion are implemented in the specific code subroutines, and the results obtained are compared to those for Zircaloy-4 (Zy-4 under the same power history. The results show that the effects of corrosion on SS are considerably different from those on Zy-4. The thickness of the oxide layer formed on the SS surface is considerably lower than that formed on Zy-4. As a consequence of this, the global fuel performance of SS under irradiation should be less affected by the corrosion.

  1. The effect of Sn on autoclave corrosion performance and corrosion mechanisms in Zr–Sn–Nb alloys

    International Nuclear Information System (INIS)

    Wei, J.; Frankel, P.; Polatidis, E.; Blat, M.; Ambard, A.; Comstock, R.J.; Hallstadius, L.; Hudson, D.; Smith, G.D.W.; Grovenor, C.R.M.; Klaus, M.; Cottis, R.A.; Lyon, S.; Preuss, M.

    2013-01-01

    The desire to improve the corrosion resistance of Zr cladding material for high burn-up has resulted in a general trend among fuel manufacturers to develop alloys with reduced levels of Sn. While commonly accepted, the reason for the improved corrosion performance observed for low-tin zirconium alloys in high-temperature aqueous environments remains unclear. High-energy synchrotron X-ray diffraction was used to characterize the oxides formed by autoclave exposure on Zr–Sn–Nb alloys with tin concentration ranging from 0.01 to 0.92 wt.%. The alloys studied included the commercial alloy ZIRLO® (ZIRLO® is a registered trademark of Westinghouse Electric Company LLC in the USA and may be registered in other countries throughout the world. All rights reserved. Unauthorized use is strictly prohibited.) and two variants of ZIRLO with significantly lower tin levels, referred to here as A-0.6Sn and A-0.0Sn. The nature of the oxide grown on tube samples from each alloy was investigated via cross-sectional scanning electron microscopy. Atom probe analysis of ZIRLO demonstrated that the tin present in the alloy passes into the oxide as it forms, with no significant difference in the Sn/Zr ratio between the two. Synchrotron X-ray diffraction measurements on the oxides formed on each alloy revealed that the monoclinic and tetragonal oxide phases display highly compressive in-plane residual stresses with the magnitudes dependent on the phase and alloy. The amount of tetragonal phase present and, more importantly, the level of tetragonal-to-monoclinic phase transformation both decrease with decreasing tin levels, suggesting that tin is a tetragonal oxide phase stabilizing element. It is proposed that in Zr–Nb–Sn alloys with low Sn, the tetragonal phase is mainly stabilized by very small grain size and therefore remains stable throughout the corrosion process. In contrast, alloys with higher tin levels can in addition grow larger, stress stabilized, tetragonal grains that

  2. Corrosion performance of metals and alloys in a tuff geochemical environment

    International Nuclear Information System (INIS)

    Van Konynenburg, R.A.; McCright, R.D.

    1985-01-01

    Reference and alternate alloy systems have been chosen for use in fabricating waste packages for a potential high-level nuclear waste repository in tuff. The main corrosion concerns have been identified. Testing performed to date indicates that austenitic stainless steels woul perform well as package materials under the expected conditions as well as the less likely extreme conditions so far postulated. Carbon steel appears to be adequate as a material for borehole liners. Copper-based alloys and Zircaloys are also undergoing corrosion testing, the former as alternate package materials, and the latter because of their presence as spent fuel cladding. 17 references, 2 tables

  3. Assessment of high performance concrete containing fly ash and calcium nitrite based corrosion inhibitor as a mean to prevent the corrosion of reinforcing steel

    International Nuclear Information System (INIS)

    Montes-García, P; Jiménez-Quero, V; López-Calvo, H

    2015-01-01

    This research analyses the effectiveness of the water-to-cement ratio (w/c), fly ash and a calcium nitrite based corrosion inhibitor to prevent the corrosion of reinforcing steel embedded in high performance concrete. The interactive effect between the inhibitor and fly ash was evaluated because the occurrence of a negative effect when both ingredients are added together in a concrete mixture has been reported. All the concrete mixtures studied in this investigation had 8.2% of silica fume. Twenty seven prismatic concrete specimens were fabricated with dimensions of 55 × 230 × 300 mm each containing two steel rods embedded for the purpose of corrosion monitoring. The specimens were exposed to a simulated marine environment with two daily cycles of wetting and drying for one year. To evaluate the deterioration of the specimens corrosion potentials and linear polarization resistance tests were carried out. The results indicate that the use of a low w/c, the addition of fly ash and the addition of the corrosion inhibitor contributed to the reduction of the corrosion of steel in the concrete specimens. The results further suggest that the combination of fly ash and corrosion inhibitor does not promote the deterioration of the concrete matrix

  4. Corrosion Performance of Nano-ZrO₂ Modified Coatings in Hot Mixed Acid Solutions.

    Science.gov (United States)

    Xu, Wenhua; Wang, Zhenyu; Han, En-Hou; Wang, Shuai; Liu, Qian

    2018-06-01

    A nano-ZrO₂ modified coating system was prepared by incorporation of nano-ZrO₂ concentrates into phenolic-epoxy resin. The corrosion performance of the coatings was evaluated in hot mixed acid solution, using electrochemical methods combined with surface characterization, and the effects of nano-ZrO₂ content were specially focused on. The results showed that 1% and 3% nano-ZrO₂ addition enhanced the corrosion resistance of the coatings, while 5% nano-ZrO₂ addition declined it. The coating with 3% nano-ZrO₂ presented the minimum amount of species diffusion, the lowest average roughness (5.94 nm), and the highest C/O ratio (4.55) and coating resistance, and it demonstrated the best corrosion performance among the coating specimens.

  5. Corrosion Performance of Fe-Cr-Ni Alloys in Artificial Saliva and Mouthwash Solution

    Science.gov (United States)

    Porcayo-Calderon, J.; Casales-Diaz, M.; Salinas-Bravo, V. M.; Martinez-Gomez, L.

    2015-01-01

    Several austenitic stainless steels suitable for high temperature applications because of their high corrosion resistance and excellent mechanical properties were investigated as biomaterials for dental use. The steels were evaluated by electrochemical techniques such as potentiodynamic polarization curves, cyclic polarization curves, measurements of open circuit potential, and linear polarization resistance. The performance of steels was evaluated in two types of environments: artificial saliva and mouthwash solution at 37°C for 48 hours. In order to compare the behavior of steels, titanium a material commonly used in dental applications was also tested in the same conditions. Results show that tested steels have characteristics that may make them attractive as biomaterials for dental applications. Contents of Cr, Ni, and other minor alloying elements (Mo, Ti, and Nb) determine the performance of stainless steels. In artificial saliva steels show a corrosion rate of the same order of magnitude as titanium and in mouthwash have greater corrosion resistance than titanium. PMID:26064083

  6. The corrosion performance of microcrystalline titanium-modified 316 stainless steel

    International Nuclear Information System (INIS)

    Saito, N.; Searson, P.C.; Latanision, R.M.

    1986-01-01

    The corrosion performance of rapidly solidified (RS), consolidated RS and conventionally processed titanium-modified nuclear grade 316 stainless steel was studied. As-solidified RS foils exhibited general corrosion behavior identical to that of the conventionally processed alloy, but inferior pitting resistance, due to the presence of dendritic microsegregation. The consolidated RS alloy exhibited inferior general and pitting corrosion performance due to the detrimental effect of the prior foil boundary formed during the consolidation process. The results of immersion tests in 6% FeC1 3 .6H 2 O solution showed that pit initiation occured primarily at the prior foil boundaries in the consolidated RS alloy. Studies of sensitization were inconclusive due to preferential attack on prior foil boundaries in the consolidated RS specimens which made the determination of the degree of sensitization difficult. (author)

  7. Corrosion inhibition performance of imidazolium ionic liquids and their influence on surface ferrous carbonate layer formation

    Science.gov (United States)

    Yang, Dongrui

    Corrosion inhibitors as effective anti-corrosion applications were widely studied and drawn much attention in both academe and industrial area. In this work, a systematic work, including inhibitors selection, anti-corrosion property and characterization, influence on scale formation, testing system design and so on, were reported. The corrosion inhibition performance of four imidazolium ionic liquids in carbon dioxide saturated NaCl solution was investigated by using electrochemical and surface analysis technologies. The four compounds are 1-ethyl-3-methylimidazolium chloride (a), 1-butyl-3-methylimidazolium chloride (b), 1-hexyl-3-methylimidazolium chloride (c), 1-decyl-3-methylimidazolium chloride (d). Under the testing conditions, compound d showed the highest inhibition efficiency and selected as the main object of further study. As a selected representative formula, 1-decyl-3-methylimidazolium chloride was studied in detail about its corrosion inhibition performance on mild steel in carbon dioxide saturated NaCl brine at pH 3.8 and 6.8. Electrochemical and surface analysis techniques were used to characterize the specimen corrosion process during the immersion in the blank and inhibiting solutions. The precorrosion of specimen surface showed significant and different influences on the anti-corrosion property of DMICL at pH 3.8 and 6.8. The corrosion inhibition efficiency (IE) was calculated based on parameters obtained from electrochemical techniques; the achieved IE was higher than 98% at the 25th hour for the steel with a well-polished surface at pH 3.8. The fitting parameters obtained from electrochemical data helped to account for the interfacial changes. As proved in previous research, 1-decyl-3-methylimidazolium chloride could be used as good corrosion inhibitors under certain conditions. However, under other conditions, such chemicals, as well as other species in oil transporting system, could be a factor influencing the evolution of protective surface

  8. Bridge maintenance to enhance corrosion resistance and performance of steel girder bridges

    Science.gov (United States)

    Moran Yanez, Luis M.

    The integrity and efficiency of any national highway system relies on the condition of the various components. Bridges are fundamental elements of a highway system, representing an important investment and a strategic link that facilitates the transport of persons and goods. The cost to rehabilitate or replace a highway bridge represents an important expenditure to the owner, who needs to evaluate the correct time to assume that cost. Among the several factors that affect the condition of steel highway bridges, corrosion is identified as the main problem. In the USA corrosion is the primary cause of structurally deficient steel bridges. The benefit of regular high-pressure superstructure washing and spot painting were evaluated as effective maintenance activities to reduce the corrosion process. The effectiveness of steel girder washing was assessed by developing models of corrosion deterioration of composite steel girders and analyzing steel coupons at the laboratory under atmospheric corrosion for two alternatives: when high-pressure washing was performed and when washing was not considered. The effectiveness of spot painting was assessed by analyzing the corrosion on steel coupons, with small damages, unprotected and protected by spot painting. A parametric analysis of corroded steel girder bridges was considered. The emphasis was focused on the parametric analyses of corroded steel girder bridges under two alternatives: (a) when steel bridge girder washing is performed according to a particular frequency, and (b) when no bridge washing is performed to the girders. The reduction of structural capacity was observed for both alternatives along the structure service life, estimated at 100 years. An economic analysis, using the Life-Cycle Cost Analysis method, demonstrated that it is more cost-effective to perform steel girder washing as a scheduled maintenance activity in contrast to the no washing alternative.

  9. Nonlinear performances of dual-pump amplifiers in silicon waveguides

    International Nuclear Information System (INIS)

    Meng Fan; Yu Chong-Xiu; Deng Yun-Yi; Yuan Jin-Hui

    2012-01-01

    The performances of a dual-pump parametric and Raman amplification process and the wavelength conversion in silicon waveguides are investigated. By setting the Raman contribution fraction f to be 0.043 in our analytical model, the amplification gain of the probe signal can be obtained to be over 10 dB. The pump transfer noise (PTN), the quantum noise (QN), and the total noise figure (TNF) are discussed, and the TNF has a constant value of about 4 dB in the gain bandwidth. An idler signal generated during the parametric amplification (PA) process can be used to realize the wavelength conversion in wavelength division multiplexing (WDM) systems. In addition, the pump signal parameters, the generated free carrier lifetime and effective mode area (EMA) of the waveguide are analysed for the optimization of signal gain and noise characteristics. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  10. Performance analysis of a composite dual-winding reluctance machine

    International Nuclear Information System (INIS)

    Anih, Linus U.; Obe, Emeka S.

    2009-01-01

    The electromagnetic energy conversion process of a composite dual-winding asynchronous reluctance machine is presented. The mechanism of torque production is explained using the magnetic fields distributions. The dynamic model developed in dq-rotor reference frame from first principles depicts the machine operation and response to sudden load change. The device is self-starting in the absence of rotor conductors and its starting current is lower than that of a conventional induction machine. Although the machine possesses salient pole rotors, it is clearly shown that its performance is that of an induction motor operating at half the synchronous speed. Hence the device produces synchronous torque while operating asynchronously. Simple tests were conducted on a prototype demonstration machine and the results obtained are seen to be in tune with the theory and the steady-state calculations.

  11. Performance Analysis of Retrofitted Tribo-Corrosion Test Rig for Monitoring In Situ Oil Conditions

    Directory of Open Access Journals (Sweden)

    Arpith Siddaiah

    2017-09-01

    Full Text Available Oils and lubricants, once extracted after use from a mechanical system, can hardly be reused, and should be refurbished or replaced in most applications. New methods of in situ oil and lubricant efficiency monitoring systems have been introduced for a wide variety of mechanical systems, such as automobiles, aerospace aircrafts, ships, offshore wind turbines, and deep sea oil drilling rigs. These methods utilize electronic sensors to monitor the “byproduct effects” in a mechanical system that are not indicative of the actual remaining lifecycle and reliability of the oils. A reliable oil monitoring system should be able to monitor the wear rate and the corrosion rate of the tribo-pairs due to the inclusion of contaminants. The current study addresses this technological gap, and presents a novel design of a tribo-corrosion test rig for oils used in a dynamic system. A pin-on-disk tribometer test rig retrofitted with a three electrode-potentiostat corrosion monitoring system was used to analyze the corrosion and wear rate of a steel tribo-pair in industrial grade transmission oil. The effectiveness of the retrofitted test rig was analyzed by introducing various concentrations of contaminants in an oil medium that usually leads to a corrosive working environment. The results indicate that the retrofitted test rig can effectively monitor the in situ tribological performance of the oil in a controlled dynamic corrosive environment. It is a useful method to understand the wear–corrosion synergies for further experimental work, and to develop accurate predictive lifecycle assessment and prognostic models. The application of this system is expected to have economic benefits and help reduce the ecological oil waste footprint.

  12. Performance Analysis of Retrofitted Tribo-Corrosion Test Rig for Monitoring In Situ Oil Conditions.

    Science.gov (United States)

    Siddaiah, Arpith; Khan, Zulfiqar Ahmad; Ramachandran, Rahul; Menezes, Pradeep L

    2017-09-28

    Oils and lubricants, once extracted after use from a mechanical system, can hardly be reused, and should be refurbished or replaced in most applications. New methods of in situ oil and lubricant efficiency monitoring systems have been introduced for a wide variety of mechanical systems, such as automobiles, aerospace aircrafts, ships, offshore wind turbines, and deep sea oil drilling rigs. These methods utilize electronic sensors to monitor the "byproduct effects" in a mechanical system that are not indicative of the actual remaining lifecycle and reliability of the oils. A reliable oil monitoring system should be able to monitor the wear rate and the corrosion rate of the tribo-pairs due to the inclusion of contaminants. The current study addresses this technological gap, and presents a novel design of a tribo-corrosion test rig for oils used in a dynamic system. A pin-on-disk tribometer test rig retrofitted with a three electrode-potentiostat corrosion monitoring system was used to analyze the corrosion and wear rate of a steel tribo-pair in industrial grade transmission oil. The effectiveness of the retrofitted test rig was analyzed by introducing various concentrations of contaminants in an oil medium that usually leads to a corrosive working environment. The results indicate that the retrofitted test rig can effectively monitor the in situ tribological performance of the oil in a controlled dynamic corrosive environment. It is a useful method to understand the wear-corrosion synergies for further experimental work, and to develop accurate predictive lifecycle assessment and prognostic models. The application of this system is expected to have economic benefits and help reduce the ecological oil waste footprint.

  13. Enamel coated steel reinforcement for improved durability and life-cycle performance of concrete structures: microstructure, corrosion, and deterioration

    Science.gov (United States)

    Tang, Fujian

    This study is aimed (a) to statistically characterize the corrosion-induced deterioration process of reinforced concrete structures (concrete cracking, steel mass loss, and rebar-concrete bond degradation), and (b) to develop and apply three types of enamel-coated steel bars for improved corrosion resistance of the structures. Commercially available pure enamel, mixed enamel with 50% calcium silicate, and double enamel with an inner layer of pure enamel and an outer layer of mixed enamel were considered as various steel coatings. Electrochemical tests were respectively conducted on steel plates, smooth bars embedded in concrete, and deformed bars with/without concrete cover in 3.5 wt.% NaCl or saturated Ca(OH)2 solution. The effects of enamel microstructure, coating thickness variation, potential damage, mortar protection, and corrosion environment on corrosion resistance of the steel members were investigated. Extensive test results indicated that corrosion-induced concrete cracking can be divided into four stages that gradually become less correlated with corrosion process over time. The coefficient of variation of crack width increases with the increasing level of corrosion. Corrosion changed the cross section area instead of mechanical properties of steel bars. The bond-slip behavior between the corroded bars and concrete depends on the corrosion level and distribution of corrosion pits. Although it can improve the chemical bond with concrete and steel, the mixed enamel coating is the least corrosion resistant. The double enamel coating provides the most consistent corrosion performance and is thus recommended to coat reinforcing steel bars for concrete structures applied in corrosive environments. Corrosion pits in enamel-coated bars are limited around damage locations.

  14. The influence of current collector corrosion on the performance of electrochemical capacitors

    Science.gov (United States)

    Wojciechowski, Jarosław; Kolanowski, Łukasz; Bund, Andreas; Lota, Grzegorz

    2017-11-01

    This paper discusses the effect of current collector (stainless steel 316L) corrosion on the performance of electrochemical capacitors operated in aqueous electrolytes. This topic seems to be often neglected in scientific research. The studied electrolytes were 1 M H2SO4, 1 M KI, 1 M Na2SO4, 1 M KOH and 6 M KOH. The corrosion process was investigated by means of selected direct and alternating current techniques. The surface of the current collectors as well as the corrosion products were characterised using scanning electron microscopy, energy-dispersive X-ray spectroscopy, Raman spectroscopy and atomic force microscopy. Stainless steel 316L in alkaline solutions is characterised by the lowest values of corrosion potentials whereas the potentials in acidic media become the most noble. Our studies show that corrosion potentials increase with decreasing pH value. This phenomenon can be explained with the formation of passive oxide films on the stainless steel current collectors. The passive oxide films are usually thicker and more porous in alkaline solutions than that in the other electrolytes. The processes occurring at the electrode/electrolyte interfaces strongly influence the working parameters of electrochemical capacitors such as voltage, working potentials of single electrodes, self-discharge as well as the internal resistance and cycling stability.

  15. Corrosion protection performance of waterborne epoxy coatings containing self-doped polyaniline nanofiber

    International Nuclear Information System (INIS)

    Qiu, Shihui; Chen, Cheng; Cui, Mingjun; Li, Wei; Zhao, Haichao; Wang, Liping

    2017-01-01

    Highlights: • Self-dopedpolyaniline (SPANi) with good conductivity and dispersibility in water was copolymerized by aniline and its derivative. • Environmental friendly SPANi/epoxy composite coating with remarkable anti-corrosion performance was prepared. • The corrosion product of pure epoxy or composite coating was characterized by X-ray diffraction pattern and scanning electron microscope (SEM). - Abstract: Self-doped sulfonated polyaniline (SPANi) nanofiber was synthesized by the copolymerization of 2-aminobenzenesulfonic acid (ASA) and aniline via a rapid mixing polymerization approach. The chemical structure of SPANi was investigated by the Fourier-transform infrared (FT-IR), Raman, X-ray photoelectron spectroscopy (XPS), UV–vis spectra and X-ray diffraction (XRD) pattern. The as-prepared SPANi nanofibers had 45 nm average diameter and length up to 750 nm as measured by scanning electron microscope (SEM) and transmission electron microscope (TEM). The self-doped SPANi nanofiber possessed excellent aqueous solubility, good conductivity (0.11 S/cm) and reversible redox activity, making it suitable as a corrosion inhibitor for waterborne coatings. The prepared SPANi/waterborne epoxy composite coatings exhibited remarkably improved corrosion protection compared with pure waterborne epoxy coating as proved by the polarization curves and electrochemical impedance spectroscopy (EIS). The passivation effect of SPANi nanofiber and the corrosion products beneath the epoxy coatings immersed in 3.5% NaCl solution as a function of time were also investigated in this study.

  16. Corrosion protection performance of waterborne epoxy coatings containing self-doped polyaniline nanofiber

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Shihui [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201 (China); Faculty of Materials Science and Chemical Engineering, Ningbo University, Ningbo, 315211 (China); Chen, Cheng; Cui, Mingjun [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201 (China); Li, Wei [Faculty of Materials Science and Chemical Engineering, Ningbo University, Ningbo, 315211 (China); Zhao, Haichao, E-mail: zhaohaichao@nimte.ac.cn [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201 (China); Wang, Liping, E-mail: wangliping@nimte.ac.cn [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201 (China)

    2017-06-15

    Highlights: • Self-dopedpolyaniline (SPANi) with good conductivity and dispersibility in water was copolymerized by aniline and its derivative. • Environmental friendly SPANi/epoxy composite coating with remarkable anti-corrosion performance was prepared. • The corrosion product of pure epoxy or composite coating was characterized by X-ray diffraction pattern and scanning electron microscope (SEM). - Abstract: Self-doped sulfonated polyaniline (SPANi) nanofiber was synthesized by the copolymerization of 2-aminobenzenesulfonic acid (ASA) and aniline via a rapid mixing polymerization approach. The chemical structure of SPANi was investigated by the Fourier-transform infrared (FT-IR), Raman, X-ray photoelectron spectroscopy (XPS), UV–vis spectra and X-ray diffraction (XRD) pattern. The as-prepared SPANi nanofibers had 45 nm average diameter and length up to 750 nm as measured by scanning electron microscope (SEM) and transmission electron microscope (TEM). The self-doped SPANi nanofiber possessed excellent aqueous solubility, good conductivity (0.11 S/cm) and reversible redox activity, making it suitable as a corrosion inhibitor for waterborne coatings. The prepared SPANi/waterborne epoxy composite coatings exhibited remarkably improved corrosion protection compared with pure waterborne epoxy coating as proved by the polarization curves and electrochemical impedance spectroscopy (EIS). The passivation effect of SPANi nanofiber and the corrosion products beneath the epoxy coatings immersed in 3.5% NaCl solution as a function of time were also investigated in this study.

  17. Corrosion resistance of high performance stainless steels in cooling water and other refinery environments

    International Nuclear Information System (INIS)

    Kovach, C.W.; Redmerski, L.S.

    1984-01-01

    The recent successful introduction of high performance stainless steels as tubing for seawater cooled electric utility condensers suggests that these alloys can also provide useful service in refinery heat exchanger applications. Since many of these applications involve higher temperature exposure than steam condensers, a study was conducted to evaluate crevice corrsion resistance over a range of cooling water temperature and chloride concentrations, and also to evaluate general corrosion resistance in some strong chemical and refinery environments. These stainless steels display excellent crevice corrosion resistance as well as good resistance to a variety of chemical environments that may be encountered in refinery, petrochemical and chemical plant service

  18. Corrosion Performance of Composite Galvanic Coatings with Variable Concentration of Polymeric Nanoaggregates and/or Cr(III) Conversion Layers

    NARCIS (Netherlands)

    Koleva, D.A.; Taheri, P.; Tsvetkova, N.; Boshkov, N.; Van Breugel, K.; De Wit, J.H.W.; Mol, J.M.C.

    2011-01-01

    This paper reports on the corrosion performance of composite zinc layers (~ 8µm) on a steel substrate, considering the influence of nano-aggregates and Cr(III) conversion layers, compared to control (only Zn layers) conditions. The main factors, influencing the corrosion performance of Zn in this

  19. 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

  20. Effect of areal power density and relative humidity on corrosion resistant container performance

    International Nuclear Information System (INIS)

    Gansemer, J.D.

    1994-10-01

    The impact of the rewetting process on the performance of waste containers at the Yucca Mountain repository is analyzed. This paper explores the impact of the temperature-humidity relationships on pitting corrosion failure of stainless steel containers for different areal power densities (APDs)in the repository. It compares the likely performance of containers in a repository with a low APD, 55 Kw/acre, and a high APD, 110 kW/acre

  1. FEM Analyses for T-H-M-M Coupling Processes in Dual-Porosity Rock Mass under Stress Corrosion and Pressure Solution

    Directory of Open Access Journals (Sweden)

    Yu-Jun Zhang

    2012-01-01

    Full Text Available The models of stress corrosion and pressure solution established by Yasuhara et al. were introduced into the 2D FEM code of thermo-hydro-mechanical-migratory coupling analysis for dual-porosity medium developed by the authors. Aiming at a hypothetical model for geological disposal of nuclear waste in an unsaturated rock mass from which there is a nuclide leak, two computation conditions were designed. Then the corresponding two-dimensional numerical simulation for the coupled thermo-hydro-mechanical-migratory processes were carried out, and the states of temperatures, rates and magnitudes of aperture closure, pore and fracture pressures, flow velocities, nuclide concentrations and stresses in the rock mass were investigated. The results show: the aperture closure rates caused by stress corrosion are almost six orders higher than those caused by pressure solution, and the two kinds of closure rates climb up and then decline, furthermore tend towards stability; when the effects of stress corrosion and pressure solution are considered, the negative fracture pressures in near field rise very highly; the fracture aperture and porosity are decreases in the case 1, so the relative permeability coefficients reduce, therefore the nuclide concentrations in pore and fracture in this case are higher than those in case 2.

  2. Performance evaluation of corrosion probes in simulated WVNS tank 8D-2 waste: WVNS tank farm process support

    International Nuclear Information System (INIS)

    Elmore, M.R.

    1994-07-01

    Five corrosion probes were received from West Valley Nuclear Services for evaluation in simulated tank 8D-2 3rd-stage sludge wash slurry. The same waste slurry simulated was also used in a series of ongoing corrosion studies assessing the effects of in-tank sludge washing on the integrity of tank 8D-2. Two of the corrosion probes were installed in the coupon corrosion test vessels operating at ∼150 degrees F to compare performance of the probes with that observed by coupon tests conducted in the same vessels. Corrosion rate data calculated from electrical resistance measurements of the corrosion probes were evaluated for this study using two slightly different approaches. One approach uses the total length of exposure of the probe to give a ''time-averaged'' value of the corrosion rate. The other approach uses a shorter period of time (relative to the length of the test) in the calculation of corrosion rate, and is referred to as the ''instantaneous'' rate. The interpretation of the probe data and the implications of corrosion rates calculated with either of these methods are discussed in this report

  3. Corrosion Performance of Friction Stir Linear Lap Welded AM60B Joints

    Science.gov (United States)

    Kish, J. R.; Birbilis, N.; McNally, E. M.; Glover, C. F.; Zhang, X.; McDermid, J. R.; Williams, G.

    2017-11-01

    A corrosion investigation of friction stir linear lap welded AM60B joints used to fabricate an Mg alloy-intensive automotive front end sub-assembly was performed. The stir zone exhibited a slightly refined grain size and significant break-up and re-distribution of the divorced Mg17Al12 (β-phase) relative to the base material. Exposures in NaCl (aq) environments revealed that the stir zone was more susceptible to localized corrosion than the base material. Scanning vibrating electrode technique measurements revealed differential galvanic activity across the joint. Anodic activity was confined to the stir zone surface and involved initiation and lateral propagation of localized filaments. Cathodic activity was initially confined to the base material surface, but was rapidly modified to include the cathodically-activated corrosion products in the filament wake. Site-specific surface analyses revealed that the corrosion observed across the welded joint was likely linked to variations in Al distribution across the surface film/metal interface.

  4. Makeup water system performance and impact on PWR steam generator corrosion

    International Nuclear Information System (INIS)

    Bell, M.J.; Sawocha, S.G.; Smith, L.A.

    1984-01-01

    The object of this EPRI-funded project was to assess the possible relation of pressurized water reactor (PWR) steam generator corrosion at fresh water sites to makeup water impurity ingress. Makeup water system design, operation and performance reviews were based on site visits, plant design documents, performance records and grab sample analyses. Design features were assessed in terms of their effect on makeup system performance. Attempts were made to correlate the makeup plant source water, system design characteristics, and typical makeup water qualities to steam generator corrosion observations, particularly intergranular attack (IGA). Direct correlations were not made since many variables are involved in the corrosion process and in the case of IGA, the variables have not been clearly established. However, the study did demonstrate that makeup systems can be a significant source of contaminants that are suspected to lead to both IGA and denting. Additionally, it was noted that typical makeup system performance with respect to organic removal was not good. The role of organics in steam generator damage has not been quantified and may deserve further study

  5. Working Memory Training Improves Dual-Task Performance on Motor Tasks.

    Science.gov (United States)

    Kimura, Takehide; Kaneko, Fuminari; Nagahata, Keita; Shibata, Eriko; Aoki, Nobuhiro

    2017-01-01

    The authors investigated whether working memory training improves motor-motor dual-task performance consisted of upper and lower limb tasks. The upper limb task was a simple reaction task and the lower limb task was an isometric knee extension task. 45 participants (age = 21.8 ± 1.6 years) were classified into a working memory training group (WM-TRG), dual-task training group, or control group. The training duration was 2 weeks (15 min, 4 times/week). Our results indicated that working memory capacity increased significantly only in the WM-TRG. Dual-task performance improved in the WM-TRG and dual-task training group. Our study provides the novel insight that working memory training improves dual-task performance without specific training on the target motor task.

  6. Investigating Perfect Timesharing: The Relationship between IM-Compatible Tasks and Dual-Task Performance

    Science.gov (United States)

    Halvorson, Kimberly M.; Ebner, Herschel; Hazeltine, Eliot

    2013-01-01

    Why are dual-task costs reduced with ideomotor (IM) compatible tasks (Greenwald & Shulman, 1973; Lien, Proctor & Allen, 2002)? In the present experiments, we first examine three different measures of single-task performance (pure single-task blocks, mixed blocks, and long stimulus onset asynchrony [SOA] trials in dual-task blocks) and two…

  7. A High-Performance Corrosion-Resistant Iron-Based Amorphous Metal - The Effects of Composition, Structure and Environment on Corrosion Resistance

    International Nuclear Information System (INIS)

    Farmer, J.; Haslam, J.; Day, D.; Lian, T.; Saw, C.; Hailey, P.; Choi, J.S.; Rebak, R.; Yang, N.; Bayles, R.; Aprigliano, L.; Payer, J.; Perepezko, J.; Hildal, K.; Lavernia, E.; Ajdelsztajn, L.; Branagan, D.; Beardsley, B.

    2007-01-01

    The passive film stability of several Fe-based amorphous metal formulations have been found to be comparable to that of high-performance Ni-based alloys, and superior to that of stainless steels, based on electrochemical measurements of the passive film breakdown potential and general corrosion rates. Chromium (Cr), molybdenum (Mo) and tungsten (W) provide corrosion resistance; boron (B) enables glass formation; and rare earths such as yttrium (Y) lower critical cooling rate (CCR). The high boron content of this particular amorphous metal also makes it an effective neutron absorber, and suitable for criticality control applications, as discussed in companion publications. Corrosion data for SAM2X5 (Fe 49.7 Cr 17.7 Mn 1.9 Mo 7.4 W 1.6 B 15.2 C 3.8 Si 2.4 ) is discussed here. (authors)

  8. Improving corrosion resistance of post-tensioned substructures emphasizing high performance grouts

    Science.gov (United States)

    Schokker, Andrea Jeanne

    The use of post-tensioning in bridges can provide durability and structural benefits to the system while expediting the construction process. When post-tensioning is combined with precast elements, traffic interference can be greatly reduced through rapid construction. Post-tensioned concrete substructure elements such as bridge piers, hammerhead bents, and straddle bents have become more prevalent in recent years. Chloride induced corrosion of steel in concrete is one of the most costly forms of corrosion each year. Coastal substructure elements are exposed to seawater by immersion or spray, and inland bridges may also be at risk due to the application of deicing salts. Corrosion protection of the post-tensioning system is vital to the integrity of the structure because loss of post-tensioning can result in catastrophic failure. Documentation for durability design of the grout, ducts, and anchorage systems is very limited. The objective of this research is to evaluate the effectiveness of corrosion protection measures for post-tensioned concrete substructures by designing and testing specimens representative of typical substructure elements using state-of-the-art practices in aggressive chloride exposure environments. This was accomplished through exposure testing of twenty-seven large-scale beam specimens and ten large-scale column specimens. High performance grout for post-tensioning tendon injection was also developed through a series of fresh property tests, accelerated exposure tests, and a large-scale pumping test to simulate field conditions. A high performance fly ash grout was developed for applications with small vertical rises, and a high performance anti-bleed grout was developed for applications involving large vertical rises such as tall bridge piers. Long-term exposure testing of the beam and column specimens is ongoing, but preliminary findings indicate increased corrosion protection with increasing levels of post-tensioning, although traditional

  9. The rf-power dependences of the deposition rate, the hardness and the corrosion-resistance of the chromium nitride film deposited by using a dual ion beam sputtering system

    International Nuclear Information System (INIS)

    Lim, Jongmin; Lee, Chongmu

    2006-01-01

    The hexavalent chromium used in chromium plating is so toxic that it is very hazardous to human body and possibly causes cancer in humans. Therefore, it is indispensable to develop an alternative deposition technique. Dependences of the deposition rate, the phases, the hardness, the surface roughness and the corrosion-resistance of CrN x deposited on the high speed steel substrate by using a dual ion beam sputtering system on the rf-power were investigated to see the feasibility of sputtering as an alternative technique for chromium plating. The dual ion beam sputtering system used in this study was designed in such a way as the primary argon ion beam and the secondary nitrogen ion beam are injected toward the target and the substrate, respectively so that the chromium atoms at the chromium target surface may not nearly react with nitrogen atoms. The hardness and the surface roughness were measured by a micro-Vicker's hardness tester and an atomic force microscope (AFM), respectively. X-ray diffraction analyses were performed to identify phases in the films. The deposition rate of CrN x depends more strongly upon the rf-power for argon ion beam than that for nitrogen ion beam. The hardness of the CrN x film is highest when the volume percent of the Cr 2 N phase in the film is highest. Amorphous films are obtained when the rf-power for nitrogen ion beam is much higher than that for argon ion beam. The CrN x film deposited by using the sputtering technique under the optimal condition provides corrosion-resistance comparable to that of the electroplated chromium

  10. Changes in Standing and Walking Performance Under Dual-Task Conditions Across the Lifespan.

    Science.gov (United States)

    Ruffieux, Jan; Keller, Martin; Lauber, Benedikt; Taube, Wolfgang

    2015-12-01

    Simultaneous performance of a postural and a concurrent task is rather unproblematic as long as the postural task is executed in an automatic way. However, in situations where postural control requires more central processing, cognitive resources may be exceeded by the addition of an attentionally demanding task. This may lead to interference between the two tasks, manifested in a decreased performance in one or both tasks (dual-task costs). Owing to changes in attentional demands of postural tasks as well as processing capacities across the lifespan, it might be assumed that dual-task costs are particularly pronounced in children and older adults probably leading to a U-shaped pattern for dual-task costs as a function of age. However, these changes in the ability of dual-tasking posture from childhood to old age have not yet been systematically reviewed. Therefore, Web of Science and PubMed databases were searched for studies comparing dual-task performance with one task being standing or walking in healthy groups of young adults and either children or older adults. Seventy-nine studies met inclusion criteria. For older adults, the expected increase in dual-task costs could be confirmed. In contrast, in children there was only feeble evidence for a trend towards enlarged dual-task costs. More good-quality studies comparing dual-task ability in children, young, and, ideally, also older adults within the same paradigm are needed to draw unambiguous conclusions about lifespan development of dual-task performance in postural tasks. There is evidence that, in older adults, dual-task performance can be improved by training. For the other age groups, these effects have yet to be investigated.

  11. The Many Faces of Graphene as Protection Barrier. Performance under Microbial Corrosion and Ni Allergy Conditions

    Science.gov (United States)

    Gentil, Dana; del Campo, Valeria; Henrique Rodrigues da Cunha, Thiago; Henríquez, Ricardo; Garín, Carolina; Ramírez, Cristian; Flores, Marcos; Seeger, Michael

    2017-01-01

    In this work we present a study on the performance of CVD (chemical vapor deposition) graphene coatings grown and transferred on Ni as protection barriers under two scenarios that lead to unwanted metal ion release, microbial corrosion and allergy test conditions. These phenomena have a strong impact in different fields considering nickel (or its alloys) is one of the most widely used metals in industrial and consumer products. Microbial corrosion costs represent fractions of national gross product in different developed countries, whereas Ni allergy is one of the most prevalent allergic conditions in the western world, affecting around 10% of the population. We found that grown graphene coatings act as a protective membrane in biological environments that decreases microbial corrosion of Ni and reduces release of Ni2+ ions (source of Ni allergic contact hypersensitivity) when in contact with sweat. This performance seems not to be connected to the strong orbital hybridization that Ni and graphene interface present, indicating electron transfer might not be playing a main role in the robust response of this nanostructured system. The observed protection from biological environment can be understood in terms of graphene impermeability to transfer Ni2+ ions, which is enhanced for few layers of graphene grown on Ni. We expect our work will provide a new route for application of graphene as a protection coating for metals in biological environments, where current strategies have shown short-term efficiency and have raised health concerns. PMID:29292763

  12. The Many Faces of Graphene as Protection Barrier. Performance under Microbial Corrosion and Ni Allergy Conditions

    Directory of Open Access Journals (Sweden)

    Carolina Parra

    2017-12-01

    Full Text Available In this work we present a study on the performance of CVD (chemical vapor deposition graphene coatings grown and transferred on Ni as protection barriers under two scenarios that lead to unwanted metal ion release, microbial corrosion and allergy test conditions. These phenomena have a strong impact in different fields considering nickel (or its alloys is one of the most widely used metals in industrial and consumer products. Microbial corrosion costs represent fractions of national gross product in different developed countries, whereas Ni allergy is one of the most prevalent allergic conditions in the western world, affecting around 10% of the population. We found that grown graphene coatings act as a protective membrane in biological environments that decreases microbial corrosion of Ni and reduces release of Ni2+ ions (source of Ni allergic contact hypersensitivity when in contact with sweat. This performance seems not to be connected to the strong orbital hybridization that Ni and graphene interface present, indicating electron transfer might not be playing a main role in the robust response of this nanostructured system. The observed protection from biological environment can be understood in terms of graphene impermeability to transfer Ni2+ ions, which is enhanced for few layers of graphene grown on Ni. We expect our work will provide a new route for application of graphene as a protection coating for metals in biological environments, where current strategies have shown short-term efficiency and have raised health concerns.

  13. Effects of a multicomponent exercise on dual-task performance and executive function among older adults

    Directory of Open Access Journals (Sweden)

    Ray-Yau Wang

    2018-06-01

    Full Text Available Summary: Background: Previous studies showed that multicomponent exercise enhanced physical and cognitive functions. This study aimed to investigate the effects of a multicomponent exercise on dual-task performance and executive function and to demonstrate the relationship between improvement in dual-task performance and enhancement in executive function among the elderly. Methods: A total of 27 people completed the intervention, with 16 in the experimental group and 11 in the control group. The 12-week multicomponent exercise lasted 1 h per day and 3 days per week. Participants' gait performance was assessed in dual-task conditions and executive function was examined at both pre- and post-intervention. Results: Results showed significant interaction effects of time x group on all selected gait parameters in both dual-task conditions and the Executive Interview. Compared with the control group, the experimental group showed greater improvements in most measures following intervention. Improved dual-task performance was correlated with enhanced executive function (r = 0.46–0.75. Conclusion: Our results suggested that a multicomponent exercise positively affects dual-task performance and executive function in the elderly. Keywords: Dual-task, Executive function, Exercise, Gait, Older adults

  14. Self-cleaning performance of superhydrophobic hybrid nanocomposite coatings on Al with excellent corrosion resistance

    International Nuclear Information System (INIS)

    Raj, V.; Mohan Raj, R.

    2016-01-01

    Highlights: • Ceramic-poly(Ani-co-oPD) coatings were formed on Al by anodization and electro-polymerisation techniques. • The superhydrophobic coating was fabricated on copolymer by electrodeposition of zinc stearate. • The superhydrophobicity mechanism relies on morphologies and chemical components on surface is the key factor. • Ceramic-poly(Ani-co-oPD)-zinc stearate coated Al has excellent corrosion resistance and good self-cleaning performance. - Abstract: Protective ceramic-PANI, ceramic-poly(Ani-co-oPD) and ceramic-poly(Ani-co-oPD)-zinc stearate nanocomposite coatings were formed on Al surface by the processes involving anodization, electropolymerisation and electrodeposition under optimum conditions. The prepared nanocomposite coatings were evaluated by ATR-IR and XRD studies. SEM studies performed on nanocomposite coatings reveal that ceramic-poly(Ani-co-oPD)-zinc stearate nanocomposite coating shows a cauliflower-like cluster with crack-free morphology compared to ceramic-PANI and ceramic-poly(Ani-co-oPD) nanocomposite coatings. The mechanical properties of different nanocomposite coatings were measured using Vicker microhardness tester and Taber Abrasion tester. The ceramic-poly(Ani-co-oPD)-zinc stearate nanocomposite has higher mechanical stability. The corrosion resistance of the coatings measured by Tafel polarization and electrochemical impedance spectroscopy, shows that ceramic-poly(Ani-co-oPD)-zinc stearate nanocomposite coated aluminum has higher corrosion resistance than other coatings and bare Al. Wettability studies prove that superhydrophobic nature of ceramic-poly(Ani-co-oPD)-zinc stearate nanocomposite coating with contact angle of 155.8° is responsible for good self-cleaning property and excellent corrosion resistance of aluminum.

  15. Self-cleaning performance of superhydrophobic hybrid nanocomposite coatings on Al with excellent corrosion resistance

    Energy Technology Data Exchange (ETDEWEB)

    Raj, V., E-mail: alaguraj2@rediffmail.com; Mohan Raj, R., E-mail: chem_mohan@rediffmail.com

    2016-12-15

    Highlights: • Ceramic-poly(Ani-co-oPD) coatings were formed on Al by anodization and electro-polymerisation techniques. • The superhydrophobic coating was fabricated on copolymer by electrodeposition of zinc stearate. • The superhydrophobicity mechanism relies on morphologies and chemical components on surface is the key factor. • Ceramic-poly(Ani-co-oPD)-zinc stearate coated Al has excellent corrosion resistance and good self-cleaning performance. - Abstract: Protective ceramic-PANI, ceramic-poly(Ani-co-oPD) and ceramic-poly(Ani-co-oPD)-zinc stearate nanocomposite coatings were formed on Al surface by the processes involving anodization, electropolymerisation and electrodeposition under optimum conditions. The prepared nanocomposite coatings were evaluated by ATR-IR and XRD studies. SEM studies performed on nanocomposite coatings reveal that ceramic-poly(Ani-co-oPD)-zinc stearate nanocomposite coating shows a cauliflower-like cluster with crack-free morphology compared to ceramic-PANI and ceramic-poly(Ani-co-oPD) nanocomposite coatings. The mechanical properties of different nanocomposite coatings were measured using Vicker microhardness tester and Taber Abrasion tester. The ceramic-poly(Ani-co-oPD)-zinc stearate nanocomposite has higher mechanical stability. The corrosion resistance of the coatings measured by Tafel polarization and electrochemical impedance spectroscopy, shows that ceramic-poly(Ani-co-oPD)-zinc stearate nanocomposite coated aluminum has higher corrosion resistance than other coatings and bare Al. Wettability studies prove that superhydrophobic nature of ceramic-poly(Ani-co-oPD)-zinc stearate nanocomposite coating with contact angle of 155.8° is responsible for good self-cleaning property and excellent corrosion resistance of aluminum.

  16. Pressurized water reactor fuel performance problems connected with fuel cladding corrosion processes

    International Nuclear Information System (INIS)

    Dobrevski, I.; Zaharieva, N.

    2008-01-01

    Generally, Pressurized Water Reactor (WWER, PWR) Fuel Element Performance is connected with fuel cladding corrosion and crud deposition processes. By transient to extended fuel cycles in nuclear power reactors, aiming to achieve higher burnup and better fuel utilization, the role of these processes increases significantly. This evolution modifies the chemical and electrochemical conditions in the reactor primary system, including change of fuel claddings' environment. The higher duty cores are always attended with increased boiling (sub-cooled nucleate boiling) mainly on the feed fuel assemblies. This boiling process on fuel cladding surfaces can cause different consequences on fuel element cladding's environment characteristics. In the case of boiling at the cladding surfaces without or with some cover of corrosion product deposition, the behavior of gases dissolved in water phase is strongly influenced by the vapor generation. The increase of vapor partial pressure will reduce the partial pressures of dissolved gases and will cause their stripping out. By these circumstances the concentrations of dissolved gases in cladding wall water layer can dramatically decrease, including also the case by which all dissolved gases to be stripped out. On the other hand it is known that the hydrogen is added to primary coolant in order to avoid the production of oxidants by radiolysis of water. It is clear that if boiling strips out dissolved hydrogen, the creation of oxidizing conditions at the cladding surfaces will be favored. In this case the local production of oxidants will be a result from local processes of water radiolysis, by which not only both oxygen (O 2 ) and hydrogen (H 2 ) but also hydrogen peroxide (H 2 O 2 ) will be produced. While these hydrogen and oxygen will be stripped out preferentially by boiling, the bigger part of hydrogen peroxide will remain in wall water phase and will act as the most important factor for creation of oxidizing conditions in fuel

  17. Development of Electrodeposited Zn/nano-TiO2 Composite Coatings with Enhanced Corrosion Performance

    Science.gov (United States)

    Benea, L.; Dănăilă, E.

    2017-06-01

    Pure zinc coatings have been found ineffective when are used in aggressive environments such as those which contain chlorides or industrial pollutants [1]. In this paper, Zn/nano-TiO2 composite coatings with various contents of TiO2 nanoparticles (diameter size of 10 nm) were prepared on low-carbon steel by electro-codeposition technique. The deposition was carried out at different cathodic potentials ranging from -1600 mV to -2100 mV for different deposition times between 5-15 min. Pure Zn coatings were also produced under the same experimental conditions for comparison. Present work aims to investigate the effects of selected electrodeposition parameters (cathodic potential, TiO2 nanoparticle concentration in the plating bath and electrodeposition time) on the corrosion behavior of electrodeposited Zn/nano-TiO2 composite obtained. The corrosion experiments were performed in natural seawater, using electrochemical methods such as open circuit potential, potentiodynamic polarization and linear polarization resistance. The results showed that the inclusion of TiO2 nanoparticles into zinc matrix lead to an improved corrosion resistance comparatively with pure zinc coatings obtained under similar conditions.

  18. Utilising DualEELS to probe the nanoscale mechanisms of the corrosion of Zircaloy-4 in 350 °C pressurised water

    Energy Technology Data Exchange (ETDEWEB)

    Annand, Kirsty J., E-mail: k.annand.1@research.gla.ac.uk [Materials and Condensed Matter Physics, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom); MacLaren, Ian [Materials and Condensed Matter Physics, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Gass, Mhairi [AMEC Foster Wheeler, Clean Energy, Walton House, Birchwood Park, WA3 6GA (United Kingdom)

    2015-10-15

    Characterisation of materials utilised for fuel cladding in nuclear reactors prior to service is integral in order to understand corrosion mechanisms which would take place in reactor. Zircaloy-4 is one such material of choice for nuclear fuel containment in Pressurised Water Reactors (PWRs). In particular, the metal-oxide interface has been a predominant focus of previous research, however, due to the complex oxidation process of zirconium cladding, there is still no clear understanding of what is present at the interface. Using Scanning Transmission Electron Microscopy (STEM) and Dual Electron Energy Loss Spectroscopy (DualEELS), we have studied the corrosion of this material under conditions similar to those that could be encountered in service. It is shown that under all conditions, whether during faster oxidation in the early stages, slow growth just prior to the transition to a new growth regime, or in the faster growth that happens after this transition, the surface of the metal below the scale is loaded with oxygen up to around 33 at%. Approaching transition, in conditions of slow growth and slow oxygen supply, an additional metastable suboxide is apparent with a thickness of tens of nm. By studying changes in both chemical composition and dielectric function of the material at the oxide scale – metal interface with nanometre resolution, quantitative mapping could be achieved, clearly showing that this is a suboxide composition of ZrO and a Zr oxidation state close to +2. - Highlights: • Metal-oxide interface evolution studied by few-nm resolution EELS mapping. • Low loss EELS is very effective for mapping phase evolution. • ZrO suboxide phase characterised using EELS, which fits theoretical predictions. • ZrO formation found to correlate to local growth rate of oxide scale.

  19. Measuring treatment effects on dual-task performance: a framework for research and clinical practice

    Directory of Open Access Journals (Sweden)

    Prudence ePlummer

    2015-04-01

    Full Text Available The relevance of dual-task walking to everyday ambulation is widely acknowledged, and numerous studies have demonstrated that dual-task interference can significantly impact recovery of functional walking in people with neurological disorders. The magnitude and direction of dual-task interference is influenced by the interaction between the two tasks, including how individuals spontaneously prioritize their attention. Therefore, to accurately interpret and characterize dual-task interference and identify changes over time, it is imperative to evaluate single and dual-task performance in both tasks, as well as the tasks relative to each other. Yet, reciprocal dual-task effects are frequently ignored. The purpose of this perspective paper is to present a framework for measuring treatment effects on dual-task interference, specifically taking into account the interactions between the two tasks and how this can provide information on whether overall dual-task capacity has improved or a different attentional strategy has been adopted. In discussing the clinical implications of using this framework, we provide specific examples of using this method and provide some explicit recommendations for research and clinical practice.

  20. Structural evolution, thermomechanical recrystallization and electrochemical corrosion properties of Ni-Cu-Mg amorphous coating on mild steel fabricated by dual-anode electrolytic processing

    Energy Technology Data Exchange (ETDEWEB)

    Abdulwahab, M., E-mail: mabdulwahab@abu.edu.ng [Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); Department of Metallurgical and Materials Engineering, Ahmadu Bello University, Zaria (Nigeria); Fayomi, O.S.I., E-mail: ojosundayfayomi3@gmail.com [Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); Department of Mechanical Engineering, Covenant University, Ota (Nigeria); Popoola, A.P.I., E-mail: popoolaapi@tut.ac.za [Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa)

    2016-07-01

    Highlights: • The surface of the coat containing Ni-Cu-Mg alloy on mild steel have sufficiently enhanced the properties. • Isothermally treated composites demonstrated 45% increase in the micro-hardness and 79.6% corrosion resistance. • The thermal stability of the developed Ni-Cu-Mg thin films on mild steel was excellent. - Abstract: The electrolytic Ni-Cu based alloy coating with admixed interfacial blend of Mg have been successfully prepared on mild steel substrate by dual anode electroplating processes over a range of applied current density and dwell time. The electrocodeposition of Ni-Cu-Mg coating was investigated in the presence of other bath additives. The influence of deposition current on surface morphology, adhesion behavior, preferred crystal orientation, surface topography and electrochemical activity of Ni-Cu-Mg alloy coating on mild steel were systematically examined. The thermal stability of the developed composite materials was examined via isothermal treatment. Scanning electron microscope equipped with EDS, X-ray diffraction, Atomic force microscope, micro-hardness tester and 3 μmetrohm Potentiostat/galvanostat were used to compare untreated and isothermally treated electrocodeposited composite. The induced activity of the Ni-Cu-Mg alloy changed the surface modification and results to crystal precipitation within the structural interface by the formation of Cu{sub ,} Ni{sub 2}Mg{sub 3} phase. The obtained results showed that the introduction of Mg particles in the plating bath generally modified the surface and brings an increase in the hardness and corrosion resistance of Ni-Cu-Mg layers fabricated. Equally, isothermally treated composites demonstrated an improved properties indicating 45% increase in the micro-hardness and 79.6% corrosion resistance which further showed that the developed composite is thermally stable.

  1. Corrosion/94 conference papers

    International Nuclear Information System (INIS)

    Anon.

    1994-01-01

    The approximately 500 papers from this conference are divided into the following sections: Rail transit systems--stray current corrosion problems and control; Total quality in the coatings industry; Deterioration mechanisms of alloys at high temperatures--prevention and remediation; Research needs and new developments in oxygen scavengers; Computers in corrosion control--knowledge based system; Corrosion and corrosivity sensors; Corrosion and corrosion control of steel reinforced concrete structures; Microbiologically influenced corrosion; Practical applications in mitigating CO 2 corrosion; Mineral scale deposit control in oilfield-related operations; Corrosion of materials in nuclear systems; Testing nonmetallics for life prediction; Refinery industry corrosion; Underground corrosion control; Mechanisms and applications of deposit and scale control additives; Corrosion in power transmission and distribution systems; Corrosion inhibitor testing and field application in oil and gas systems; Decontamination technology; Ozone in cooling water applications, testing, and mechanisms; Corrosion of water and sewage treatment, collection, and distribution systems; Environmental cracking of materials; Metallurgy of oil and gas field equipment; Corrosion measurement technology; Duplex stainless steels in the chemical process industries; Corrosion in the pulp and paper industry; Advances in cooling water treatment; Marine corrosion; Performance of materials in environments applicable to fossil energy systems; Environmental degradation of and methods of protection for military and aerospace materials; Rail equipment corrosion; Cathodic protection in natural waters; Characterization of air pollution control system environments; and Deposit-related problems in industrial boilers. Papers have been processed separately for inclusion on the data base

  2. High-Performance Corrosion-Resistant Materials: Iron-Based Amorphous-Metal Thermal-Spray Coatings

    International Nuclear Information System (INIS)

    Farmer, J C; Haslam, J J; Wong, F; Ji, X; Day, S D; Branagan, D J; Marshall, M C; Meacham, B E; Buffa, E J; Blue, C A; Rivard, J K; Beardsley, M B; Weaver, D T; Aprigliano, L F; Kohler, L; Bayles, R; Lemieux, E J; Wolejsza, T M; Martin, F J; Yang, N; Lucadamo, G; Perepezko, J H; Hildal, K; Kaufman, L; Heuer, A H; Ernst, F; Michal, G M; Kahn, H; Lavernia, E J

    2004-01-01

    The multi-institutional High Performance Corrosion Resistant Materials (HPCRM) Team is cosponsored by the Defense Advanced Projects Agency (DARPA) Defense Science Office (DSO) and the Department of Energy (DOE) Office of Civilian Radioactive Waste Management (OCRWM), and has developed new corrosion-resistant, iron-based amorphous metals that can be applied as coatings with advanced thermal spray technology. Two compositions have corrosion resistance superior to wrought nickel-based Alloy C-22 (UNS No. N06022) in very aggressive environments, including concentrated calcium-chloride brines at elevated temperature. Corrosion costs the Department of Defense billions of dollars every year, with an immense quantity of material in various structures undergoing corrosion. For example, in addition to fluid and seawater piping, ballast tanks, and propulsions systems, approximately 345 million square feet of structure aboard naval ships and crafts require costly corrosion control measures. The use of advanced corrosion-resistant materials to prevent the continuous degradation of this massive surface area would be extremely beneficial. The Fe-based corrosion-resistant, amorphous-metal coatings under development may prove of importance for applications on ships. Such coatings could be used as an ''integral drip shield'' on spent fuel containers, as well as protective coatings that could be applied over welds, thereby preventing exposure to environments that might cause stress corrosion cracking. In the future, such new high-performance iron-based materials could be substituted for more-expensive nickel-based alloys, thereby enabling a reduction in the $58-billion life cycle cost for the long-term storage of the Nation's spent nuclear fuel by tens of percent

  3. Influence of hydroxyapatite coating thickness and powder particle size on corrosion performance of MA8M magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sonmez, S. [Hakkari University, Dept. of Biomedical Eng., 30000 Hakkari (Turkey); Aksakal, B., E-mail: baksakal@yildiz.edu.tr [Yildiz Technical University, Chemical Metallurgy Faculty, Dept. of Metall and Mater Eng., Istanbul (Turkey); Dikici, B. [Yuzuncu Yil University, Dept. of Mechanical Eng., 65080 Van (Turkey)

    2014-05-01

    Graphical abstract: The corrosion resistance of magnesium alloys is the primary concern in biomedical applications. Micron and nano-scale hydroxyapatite (HA) was coated successfully on MA8M magnesium alloy substrates by using a sol–gel deposition. In this study, the effects of coating thicknesses and HA powder particle sizes on the adhesion strength and corrosion behavior were investigated. Potentiodynamic polarization tests were performed in a Ringer solution. The coatings before and after corrosion tests were characterized by adhesion tests, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The micro-scale-HA coated Mg substrates were more corrosion resistant than the nano-scale-HA coatings. The anodic activity of the micro-scale-HA coatings increased with increased coating thickness and the corrosion resistance of Mg substrates decreased. Corrosion susceptibilities of the nano-scale-HA coated samples were affected inversely. The coated film provided good barrier characteristics and achieved good corrosion protection for Mg substrates when compared to substrates without coatings. For micro-scale-HA coatings, anodic and cathodic activities were more intense for thicker films. When HA coatings are compared to nano-scale HA coatings, the micro-scale-HA coatings produced better current density values. Overall, as shown in Fig. 1, the best corrosion behavior of the Mg alloys was achieved using micro-scale HA powders at 30 μm coating thickness. - Highlights: • Nano and micro-scale-HA coatings provided good anti-corrosion performance compared to the uncoated ones. • The micro-scale-HA coated Mg substrates were more corrosion resistant than the nano-scale-HA coatings. • The best corrosion behavior was achieved for the micro-scale HA powders at 30 μm coating thickness. • Anodic activity decrease and cathodic activity increase with increasing film thickness. - Abstract: To improve the corrosion resistance of MA8M magnesium alloy, sol

  4. Corrosion of several components of the in-situ test performed in a deep geological granite disposal site

    International Nuclear Information System (INIS)

    Madina, Virginia; Azkarate, Inaki; Insausti, Mikel

    2004-01-01

    The corrosion damage experienced by different components in a deep geological disposal in a granite formation has been analysed. This in-situ test is part of the Full-scale Engineered Barriers EXperiment project (FEBEX) carried out in Grimsel (Switzerland). Two heaters, simulating the canister and the heat generated, were installed horizontally inside the guide tubes or liners and surrounded by highly compacted bentonite blocks. Coupons of several candidate metals for manufacturing HLW containers were introduced in these bentonite blocks, as well as sensors in order to monitor different physicochemical parameters during the test. The in- situ test began in July 1996 and in June 2002 one of the heaters, a section of the liner, several corrosion coupons and four sensors were extracted. The studied heater is a carbon steel cylinder with welded lids, with a wall thickness of 100 mm and 4.54 m long. The liner consists of a perforated carbon steel tube, 970 mm in diameter and 15 mm thick. Corrosion coupons were made of carbon steel, stainless steel, titanium, copper and cupronickel alloys. Two extensometer type sensors with an outer protection tube made of austenitic stainless steel were also analysed. Visual inspection of the above mentioned components, optical and scanning electron microscope study, together with EDS and XRD analyses of corrosion products, have been performed in order to analyse the corrosion suffered by these components. This has been complemented with the chemical and microbiological characterisation of bentonite samples. Results obtained in the study indicate a slight generalised corrosion for the heater, liner and corrosion coupons. The low humidity content of the bentonite surrounding the liner and the corrosion coupons, is the responsible of this practical absence of corrosion. The sensors studied show, however, an important corrosion damage. The sulphur rich corrosion products, the presence of Sulphate Reducing Bacteria (SRB) in the bentonite

  5. Estimating dual deposit insurance premium rates and forecasting non-performing loans: Two new models

    OpenAIRE

    Yoshino, Naoyuki; Taghizadeh-Hesary, Farhad; Nili, Farhad

    2015-01-01

    Risky banks that endanger the stability of the financial system should pay higher deposit insurance premiums than healthy banks and other financial institutions that have shown good financial performance. It is necessary, therefore, to have at least a dual fair premium rate system. In this paper, we develop a model for calculating dual fair premium rates. Our definition of a fair premium rate in this paper is a rate that could cover the operational expenditures of the deposit insuring organiz...

  6. Promising Hard Carbon Coatings on Cu Substrates: Corrosion and Tribological Performance with Theoretical Aspect

    Science.gov (United States)

    Kumar, A. Madhan; Babu, R. Suresh; Obot, I. B.; Adesina, Akeem Yusuf; Ibrahim, Ahmed; de Barros, A. L. F.

    2018-05-01

    Protecting the surface of metals and alloys against corrosion and wear is of abundant importance owing to their widespread applications. In the present work, we report the improved anticorrosion and tribo-mechanical performance of copper (Cu) by a hard carbon (HC) coating synthesized in different pyrolysis temperature. Structural and surface characterization with roughness measurements was systematically investigated using various techniques. Effect of pyrolysis temperature on the corrosion behavior of coated Cu substrates in 0.6 M NaCl solution was evaluated via electrochemical impedance spectroscopy, potentiodynamic polarization. Pin-on-disk wear test of coated Cu substrate showed the influence of the pyrolysis temperature on the wear resistance performance of the HC coatings. According to the obtained results, it could be concluded that the HC coatings synthesized at 1100 °C revealed an enhanced comprehensive performance, revealing their possible utilization as a protective coating for Cu substrates in chloride environment. Monte Carlo simulations have been utilized to elucidate the interaction between the Cu surface and HC coatings.

  7. Electrosynthesis of Polyaniline-TiO2 Nanocomposite Films on Aluminum Alloy 3004 Surface and its Corrosion Protection Performance

    Directory of Open Access Journals (Sweden)

    M. Shabani-Nooshabadi

    2013-03-01

    Full Text Available The direct synthesis of polyaniline-TiO2 nanocomposite coatings on aluminum alloy 3004 (AA3004 surface has been investigated by using the galvanostatic method. The synthesized coatings were characterized by FT-IR, SEM-EDX, SEM and AFM. Optical absorption spectroscopy reveals the formation of the emeraldine oxidation state form of polyaniline-TiO2 nanocomposite. The corrosion performances of polyaniline-TiO2 nanocomposite coatings were investigated in 3.5% NaCl solution by Tafel polarization and Electrochemical Impedance Spectroscopy (EIS methods. The corrosion rate of polyaniline-TiO2 nanocomposite coating on AA3004 was found ∼260 times lower than bare AA3004 and corrosion potentials of these coatings have shifted to more positive potentials (105 mV. The results of this study clearly ascertain that the polyaniline-TiO2 nanocomposite coating has outstanding potential to protect the AA3004 against corrosion in a chloride environment.

  8. Corrosion and Materials Performance in biomass fired and co-fired power plants

    DEFF Research Database (Denmark)

    Montgomery, Melanie; Larsen, OH; Biede, O

    2003-01-01

    not previously encountered in coal-fired power plants. The type of corrosion attack can be directly ascribed to the composition of the deposit and the metal surface temperature. In woodchip boilers, a similar corrosion rate and corrosion mechanism has on some occasions been observed. Co-firing of straw (10...... and 20% energy basis) with coal has shown corrosion rates lower than those in straw-fired plants. With both 10 and 20% straw, no chlorine corrosion was seen. This paper will describe the results from in situ investigations undertaken in Denmark on high temperature corrosion in biomass fired plants....... Results from 100% straw-firing, woodchip and co-firing of straw with coal will be reported. The corrosion mechanisms observed are summarized and the corrosion rates for 18-8 type stainless steels are compared....

  9. Design of parallel dual-energy X-ray beam and its performance for security radiography

    International Nuclear Information System (INIS)

    Kim, Kwang Hyun; Myoung, Sung Min; Chung, Yong Hyun

    2011-01-01

    A new concept of dual-energy X-ray beam generation and acquisition of dual-energy security radiography is proposed. Erbium (Er) and rhodium (Rh) with a copper filter were positioned in front of X-ray tube to generate low- and high-energy X-ray spectra. Low- and high-energy X-rays were guided to separately enter into two parallel detectors. Monte Carlo code of MCNPX was used to derive an optimum thickness of each filter for improved dual X-ray image quality. It was desired to provide separation ability between organic and inorganic matters for the condition of 140 kVp/0.8 mA as used in the security application. Acquired dual-energy X-ray beams were evaluated by the dual-energy Z-map yielding enhanced performance compared with a commercial dual-energy detector. A collimator for the parallel dual-energy X-ray beam was designed to minimize X-ray beam interference between low- and high-energy parallel beams for 500 mm source-to-detector distance.

  10. Effect of variation in LPG composition on emissions and performance in a dual fuel diesel engine

    Energy Technology Data Exchange (ETDEWEB)

    H.E. Saleh [Mattaria, Helwan University, Cairo (Egypt). Department of Mechanical Power Engineering

    2008-10-15

    This paper investigates the effect of variation in LPG composition on emissions and performance characteristics in a dual fuel engine run on diesel fuel and five gaseous fuel of LPG with different composition. To quantify the best LPG composition for dual fuel operation especially in order to improve the exhaust emissions quality while maintaining high thermal efficiency comparable to a conventional diesel engine, a two-cylinder, naturally aspirated, four-stroke, DI diesel engine converted to run as pilot-injected dual fuel engine. The tests and data collection were performed under various conditions of load at constant engine speed. From the results, it is observed that the exhaust emissions and fuel conversion efficiency of the dual fuel engine are found to be affected when different LPG composition is used as higher butane content lead to lower NOx levels while higher propane content reduces CO levels. Fuel No. 3 (70% propane, 30% butane) with mass fraction 40% substitution of the diesel fuel was the best LPG composition in the dual fuel operation except that at part loads. Also, tests were made for fuel No. 3-diesel blend in the dual fuel operation at part loads to improve the engine performances and exhaust emissions by using the Exhaust Gas Recirculation (EGR) method. 26 refs., 15 figs., 5 tabs.

  11. Associations between physical function, dual-task performance and cognition in patients with mild Alzheimer's disease.

    Science.gov (United States)

    Sobol, Nanna Aue; Hoffmann, Kristine; Vogel, Asmus; Lolk, Annette; Gottrup, Hanne; Høgh, Peter; Hasselbalch, Steen G; Beyer, Nina

    2016-11-01

    Alzheimer's disease (AD) causes a gradual decline in cognition, limitations of dual-tasking and physical function leading to total dependence. Hence, information about the interaction between physical function, dual-task performance and cognition may lead to new treatment strategies with the purpose of preserving function and quality of life. The objective of this study was to investigate the associations between physical function, dual-task performance and cognition in community-dwelling patients with mild AD. Baseline results from 185 participants (50-90 years old) in the single blinded multicenter RCT 'ADEX' (Alzheimer's disease: the effect of physical exercise) were used. Assessments included tests of physical function: 400-m walk test, 10-m walk test, Timed Up and Go test and 30-s chair stand test; dual-task performance, i.e., 10-m walk while counting backwards from 50 or naming the months backwards; and cognition, i.e., Mini Mental State Examination, Symbol Digit Modalities Test, the Stroop Color and Word Test, and Lexical verbal fluency test. Results in the 30-s chair stand test correlated significantly with all tests of cognition (r = .208-.242) while the other physical function tests only randomly correlated with tests of cognition. Results in the dual-task counting backwards correlated significantly with results in all tests of cognition (r = .259-.388), which accounted for 7%-15% of the variation indicating that a faster time to complete dual-task performance was associated with better cognitive performance. The evidence of the associations between physical function, dual-task performance and cognition is important when creating new rehabilitation interventions to patients with mild AD.

  12. The Neurocognitive Basis for Impaired Dual-Task Performance in Senior Fallers.

    Science.gov (United States)

    Nagamatsu, Lindsay S; Hsu, C Liang; Voss, Michelle W; Chan, Alison; Bolandzadeh, Niousha; Handy, Todd C; Graf, Peter; Beattie, B Lynn; Liu-Ambrose, Teresa

    2016-01-01

    Falls are a major health-care concern, and while dual-task performance is widely recognized as being impaired in those at-risk for falls, the underlying neurocognitive mechanisms remain unknown. A better understanding of the underlying mechanisms could lead to the refinement and development of behavioral, cognitive, or neuropharmacological interventions for falls prevention. Therefore, we conducted a cross-sectional study with community-dwelling older adults aged 70-80 years with a history of falls (i.e., two or more falls in the past 12 months) or no history of falls (i.e., zero falls in the past 12 months); n = 28 per group. We compared functional activation during cognitive-based dual-task performance between fallers and non-fallers using functional magnetic resonance imaging (fMRI). Executive cognitive functioning was assessed via Stroop, Trail Making, and Digit Span. Mobility was assessed via the Timed Up and Go test (TUG). We found that non-fallers exhibited significantly greater functional activation compared with fallers during dual-task performance in key regions responsible for resolving dual-task interference, including precentral, postcentral, and lingual gyri. Further, we report slower reaction times during dual-task performance in fallers and significant correlations between level of functional activation and independent measures of executive cognitive functioning and mobility. Our study is the first neuroimaging study to examine dual-task performance in fallers, and supports the notion that fallers have reduced functional brain activation compared with non-fallers. Given that dual-task performance-and the underlying neural concomitants-appears to be malleable with relevant training, our study serves as a launching point for promising strategies to reduce falls in the future.

  13. DUAL MONETARY SYSTEM AND MACROECONOMIC PERFORMANCE IN INDONESIA

    Directory of Open Access Journals (Sweden)

    Sri Herianingrum

    2016-02-01

    Full Text Available This research aims to evaluate the impact of dual monetary policy shock on macroeconomic indicators of Indonesia: growth and inflation. In addition, this study will also examine whether conventional monetary policy has a particular impact upon Islamic banking sector. This research apply VAR (vector auto regressive method on monthly data from Bank Of Indonesia during the period of January 2010 to December 2013. The result of IRF explain that the interest rate channel find the hard way to accomplished the macroeconomic goals while the Islamic monetary instrument indicates the potential growth of output and hold the inflation low. The result of VDC describes that the Islamic instrument still affected by conventional monetary policy because of slow development in Islamic monetary systemDOI: 10.15408/aiq.v8i1.1990

  14. Dual Monetary System and Macroeconomic Performance in Indonesia

    Directory of Open Access Journals (Sweden)

    Sri Herianingrum

    2016-02-01

    Full Text Available This research aims to evaluate the impact of dual monetary policyshock on macroeconomic indicators of Indonesia: growth and inflation. Inaddition, this study will also examine whether conventional monetary policy hasa particular impact upon Islamic banking sector. This research apply VAR (vectorauto regressive method on monthly data from Bank Of Indonesia during theperiod of January 2010 to December 2013. The result of IRF explain that theinterest rate channel find the hard way to accomplished the macroeconomic goalswhile the Islamic monetary instrument indicates the potential growth of outputand hold the inflation low. The result of VDC describes that the Islamic instrumentstill affected by conventional monetary policy because of slow development inIslamic monetary systemDOI: 10.15408/aiq.v8i1.2509

  15. In-Flight performance of MESSENGER's Mercury dual imaging system

    Science.gov (United States)

    Hawkins, S.E.; Murchie, S.L.; Becker, K.J.; Selby, C.M.; Turner, F.S.; Noble, M.W.; Chabot, N.L.; Choo, T.H.; Darlington, E.H.; Denevi, B.W.; Domingue, D.L.; Ernst, C.M.; Holsclaw, G.M.; Laslo, N.R.; Mcclintock, W.E.; Prockter, L.M.; Robinson, M.S.; Solomon, S.C.; Sterner, R.E.

    2009-01-01

    The Mercury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, launched in August 2004 and planned for insertion into orbit around Mercury in 2011, has already completed two flybys of the innermost planet. The Mercury Dual Imaging System (MDIS) acquired nearly 2500 images from the first two flybys and viewed portions of Mercury's surface not viewed by Mariner 10 in 1974-1975. Mercury's proximity to the Sun and its slow rotation present challenges to the thermal design for a camera on an orbital mission around Mercury. In addition, strict limitations on spacecraft pointing and the highly elliptical orbit create challenges in attaining coverage at desired geometries and relatively uniform spatial resolution. The instrument designed to meet these challenges consists of dual imagers, a monochrome narrow-angle camera (NAC) with a 1.5?? field of view (FOV) and a multispectral wide-angle camera (WAC) with a 10.5?? FOV, co-aligned on a pivoting platform. The focal-plane electronics of each camera are identical and use a 1024??1024 charge-coupled device detector. The cameras are passively cooled but use diode heat pipes and phase-change-material thermal reservoirs to maintain the thermal configuration during the hot portions of the orbit. Here we present an overview of the instrument design and how the design meets its technical challenges. We also review results from the first two flybys, discuss the quality of MDIS data from the initial periods of data acquisition and how that compares with requirements, and summarize how in-flight tests are being used to improve the quality of the instrument calibration. ?? 2009 SPIE.

  16. Biodegradable Orthopedic Magnesium-Calcium (MgCa Alloys, Processing, and Corrosion Performance

    Directory of Open Access Journals (Sweden)

    Yuebin Guo

    2012-01-01

    Full Text Available Magnesium-Calcium (Mg-Ca alloy has received considerable attention as an emerging biodegradable implant material in orthopedic fixation applications. The biodegradable Mg-Ca alloys avoid stress shielding and secondary surgery inherent with permanent metallic implant materials. They also provide sufficient mechanical strength in load carrying applications as opposed to biopolymers. However, the key issue facing a biodegradable Mg-Ca implant is the fast corrosion in the human body environment. The ability to adjust degradation rate of Mg-Ca alloys is critical for the successful development of biodegradable orthopedic implants. This paper focuses on the functions and requirements of bone implants and critical issues of current implant biomaterials. Microstructures and mechanical properties of Mg-Ca alloys, and the unique properties of novel magnesium-calcium implant materials have been reviewed. Various manufacturing techniques to process Mg-Ca based alloys have been analyzed regarding their impacts on implant performance. Corrosion performance of Mg-Ca alloys processed by different manufacturing techniques was compared. In addition, the societal and economical impacts of developing biodegradable orthopedic implants have been emphasized.

  17. Dual-fuel natural gas/diesel engines: Technology, performance, and emissions

    Science.gov (United States)

    Turner, S. H.; Weaver, C. S.

    1994-11-01

    An investigation of current dual-fuel natural gas/diesel engine design, performance, and emissions was conducted. The most pressing technological problems associated with dual-fuel engine use were identified along with potential solutions. It was concluded that dual-fuel engines can achieve low NO(sub x) and particulate emissions while retaining fuel-efficiency and BMEP levels comparable to those of diesel engines. The investigation also examined the potential economic impact of dual-fuel engines in diesel-electric locomotives, marine vessels, farm equipment, construction, mining, and industrial equipment, and stand-alone electricity generation systems. Recommendations for further additional funding to support research, development, and demonstration in these applications were then presented.

  18. Age-related differences in dual task performance: A cross-sectional study on women.

    Science.gov (United States)

    Brustio, Paolo R; Magistro, Daniele; Rabaglietti, Emanuela; Liubicich, Monica E

    2017-02-01

    Simultaneous performances of motor and attention-demanding tasks are common in activities of everyday life. The present cross-sectional study examined the changes and age-related differences on mobility performance with an additional cognitive or motor task, and evaluated the relative dual-task cost (DTC) on the motor performance in young, middle-aged and older women. A total of 30 young (mean age 25.12 ± 3.00 years), 30 middle-aged (mean age 47.82 ± 5.06 years) and 30 older women (mean age 72.74 ± 5.95 years) were recruited. Participants carried out: (i) single task: Timed Up & Go Test; (ii) cognitive dual-task: Timed Up & Go Test while counting backwards by three; (iii) manual dual-task: Timed Up & Go Test while carrying a glass of water. A repeated measures anova with between-factor as age groups and within-factor as tasks was carried out to assess the effect of aging on the performance of mobility tasks. DTC was calculated as ([performance in single-task - performance in dual-task] / performance in single task) × 100%. One-way ancova were carried out to compare the DTC among the three age groups. A significant interaction between age groups and task (F 4,172  = 6.716, P performance under dual-task condition compared with young and middle-aged groups. Furthermore, DTC differences in cognitive task were observed in older women compared with younger and middle-aged women (F 2,86  = 7.649, P task. Dual-task conditions might affect mobility performance differently across the lifespan, and could be particularly challenging in older women. Geriatr Gerontol Int 2017; 17: 315-321. © 2015 Japan Geriatrics Society.

  19. Effects of age and auditory and visual dual tasks on closed-road driving performance.

    Science.gov (United States)

    Chaparro, Alex; Wood, Joanne M; Carberry, Trent

    2005-08-01

    This study investigated how driving performance of young and old participants is affected by visual and auditory secondary tasks on a closed driving course. Twenty-eight participants comprising two age groups (younger, mean age = 27.3 years; older, mean age = 69.2 years) drove around a 5.1-km closed-road circuit under both single and dual task conditions. Measures of driving performance included detection and identification of road signs, detection and avoidance of large low-contrast road hazards, gap judgment, lane keeping, and time to complete the course. The dual task required participants to verbally report the sums of pairs of single-digit numbers presented through either a computer speaker (auditorily) or a dashboard-mounted monitor (visually) while driving. Participants also completed a vision and cognitive screening battery, including LogMAR visual acuity, Pelli-Robson letter contrast sensitivity, the Trails test, and the Digit Symbol Substitution (DSS) test. Drivers reported significantly fewer signs, hit more road hazards, misjudged more gaps, and increased their time to complete the course under the dual task (visual and auditory) conditions compared with the single task condition. The older participants also reported significantly fewer road signs and drove significantly more slowly than the younger participants, and this was exacerbated for the visual dual task condition. The results of the regression analysis revealed that cognitive aging (measured by the DSS and Trails test) rather than chronologic age was a better predictor of the declines seen in driving performance under dual task conditions. An overall z score was calculated, which took into account both driving and the secondary task (summing) performance under the two dual task conditions. Performance was significantly worse for the auditory dual task compared with the visual dual task, and the older participants performed significantly worse than the young subjects. These findings demonstrate

  20. Atmospheric corrosion performance of different steels in early exposure in the coastal area region West Java, Indonesia

    Science.gov (United States)

    Nuraini, Lutviasari; Prifiharni, Siska; Priyotomo, Gadang; Sundjono, Gunawan, Hadi; Purawiardi, Ibrahim

    2018-05-01

    The performance of carbon steel, galvanized steel and aluminium after one month exposed in the atmospheric coastal area, which is in Limbangan and Karangsong Beach, West Java, Indonesia was evaluated. The corrosion rate was determined by weight loss method and the morphology of the steel after exposed was observed by Scanning Electron Microscopy(SEM)/Energy Dispersive X-Ray Analysis(EDX). The site was monitored to determine the chloride content in the marine atmosphere. Then, the corrosion products formed at carbon steel were characterized by X-Ray diffraction (XRD). The result showed the aggressively corrosion in Karangsong beach, indicated from the corrosion rate of carbon steel, galvanized steel and aluminium were 38.514 mpy; 4.7860 mpy and 0.5181 mpy, respectively. While in Limbangan Beach the corrosion rate of specimen carbon steel, galvanized steel and aluminium were 3.339; 0.219 and 0.166 mpy, respectively. The chloride content was found to be the main factor that influences in the atmospheric corrosion process in this area. Chloride content accumulated in Karangsong and Limbangan was 497 mg/m2.day and 117 mg/m2.day, respectively. The XRD Analysis on each carbon steel led to the characterization of a complex mixture of iron oxides phases.

  1. Dual throat NaK pump performance evaluation (conceptual design of prototype)

    International Nuclear Information System (INIS)

    Johnson, J.L.

    1972-01-01

    An evaluation of the performance of the dual throat NaK pump for the 5 Kwe Reactor TE System is discussed. Performance at nominal operating conditions and at startup conditions is predicted. The basis for selection of this pump design is presented. (U.S.)

  2. Emotion-Work Performance among Dual-Earner Couples: Testing Four Theoretical Perspectives

    Science.gov (United States)

    Minnotte, Krista Lynn; Stevens, Daphne Pedersen; Minnotte, Michael C.; Kiger, Gary

    2007-01-01

    This study compares four theories of domestic labor in their ability to predict relative emotion-work performance among dual-earner couples. Specifically, the authors investigate the effects of gender ideology, time availability, relative resources, and crossover factors on the dependent variable of relative emotion-work performance using…

  3. Dual Water Systems: Characterization and Performance for Distribution of Reclaimed Water (WaterRF Report 4333)

    Science.gov (United States)

    The research tasks included: an inventory of cases where dual systems have been implemented; formulation of a protocol to identify claimed benefits, costs, and risks; collection of data (quantitative and anecdotal) to assess performance; display of data in the form of performance...

  4. Diagnostic performance of dual-staining cytology for cervical cancer screening: A systematic literature review.

    Science.gov (United States)

    Tjalma, Wiebren A A

    2017-03-01

    Cervical cancer screening saves lives. Secondary prevention in cervical cancer screening relies on the results of primary cytology and/or HPV testing. However, primary screening with cytology has a low sensitivity, and HPV screening has a low specificity. This means that either cancers are missed, or women are over-treated. To improve performance outcomes, the concept of dual-stain cytology (CINtec ® PLUS Cytology test) has been introduced. In this approach, additional staining with p16/Ki-67 is performed in cases where cytology results are abnormal (LSIL or ASCUS) and/or HPV-positive. Another way to describe this approach might be "diagnostic" cytology. In order to assess the value of this "diagnostic cytology", a systematic literature review was conducted of dual-stain cytology performance across multiple studies until May 2016. In a Belgian screening population (women age 25-65 years), dual-stain cytology was significantly more sensitive (66%) and slightly less specific (-1.0%) than cytology. In the population referred to colposcopy or with abnormal cytology (ASCUS, LSIL), dual-staining showed a significantly higher increase in specificity, and a slightly lower sensitivity than HPV testing. Specificity gains resulted in fewer false positives and an increase in the number of correct referrals to colposcopy. Dual-staining with p16/Ki-67 cytology is an attractive biomarker approach for triage in cervical cancer screening. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Development of corrosion models to ensure reliable performance of nuclear power plants

    International Nuclear Information System (INIS)

    Kritzky, V.G.; Stjazhkin, P.S.

    1993-01-01

    The safety and reliability of the coolant circuits in nuclear power plants depend much on corrosion and corrosion products transfer processes. Various empirical models have been developed which are applicable to particular sets of operational conditions. In our laboratory a corrosion model has been worked out, which is based on the thermodynamic properties of the compounds, participating in corrosion process and on the assumption, that the corrosion process is controlled by the solubilities of the corrosion products forming the surface oxide layer. The validity of the model has been verified by use of retrospective experimental data, which have been obtained for a series of structural materials such as e.g., carbon and stainless steels, Cu-, Al-, and Zr alloys. With regard for hydriding the model satisfactorily describes stress corrosion cracking process in water-salt environments. This report describes a model based on the thermodynamic properties of the compounds participating in the corrosion process, and on the assumption that the corrosion process is controlled by the solubilities of the corrosion products forming the surface oxide layer

  6. On the Performance Analysis of Dual-Hop FSO Fixed Gain Transmission Systems

    KAUST Repository

    Zedini, Emna

    2015-12-12

    Novel exact closed-form results for the end-to-end performance analysis of dual-hop free-space optical (FSO) fixed-gain relaying systems under heterodyne detection as well as intensity modulation with direct detection techniques in the presence of atmospheric turbulence as well as pointing errors are presented. By using dual-hop FSO relaying, we demonstrate a better system performance relative to the single FSO link. Numerical and Monte-Carlo simulation results are provided to verify the accuracy of the newly proposed results, and a perfect agreement is observed.

  7. The influence of loading on the corrosion of steel in cracked ordinary Portland cement and high performance concretes

    Science.gov (United States)

    Jaffer, Shahzma Jafferali

    Most studies that have examined chloride-induced corrosion of steel in concrete have focused on sound concrete. However, reinforced concrete is seldom uncracked and very few studies have investigated the influence of cracked concrete on rebar corrosion. Furthermore, the studies that have examined the relationship between cracks and corrosion have focused on unloaded or statically loaded cracks. However, in practice, reinforced concrete structures (e.g. bridges) are often dynamically loaded. Hence, the cracks in such structures open and close which could influence the corrosion of the reinforcing steel. Consequently, the objectives of this project were (i) to examine the effect of different types of loading on the corrosion of reinforcing steel, (ii) the influence of concrete mixture design on the corrosion behaviour and (iii) to provide data that can be used in service-life modelling of cracked reinforced concretes. In this project, cracked reinforced concrete beams made with ordinary Portland cement concrete (OPCC) and high performance concrete (HPC) were subjected to no load, static loading and dynamic loading. They were immersed in salt solution to just above the crack level at their mid-point for two weeks out of every four (wet cycle) and, for the remaining two weeks, were left in ambient laboratory conditions to dry (dry cycle). The wet cycle led to three conditions of exposure for each beam: (i) the non-submerged region, (ii) the sound, submerged region and (iii) the cracked mid-section, which was also immersed in the solution. Linear polarization resistance and galvanostatic pulse techniques were used to monitor the corrosion in the three regions. Potentiodynamic polarization, electrochemical current noise and concrete electrical resistance measurements were also performed. These measurements illustrated that (i) rebar corroded faster at cracks than in sound concrete, (ii) HPC was more protective towards the rebar than OPCC even at cracks and (iii) there

  8. Implicit and Explicit Knowledge Both Improve Dual Task Performance in a Continuous Pursuit Tracking Task.

    Science.gov (United States)

    Ewolds, Harald E; Bröker, Laura; de Oliveira, Rita F; Raab, Markus; Künzell, Stefan

    2017-01-01

    The goal of this study was to investigate the effect of predictability on dual-task performance in a continuous tracking task. Participants practiced either informed (explicit group) or uninformed (implicit group) about a repeated segment in the curves they had to track. In Experiment 1 participants practices the tracking task only, dual-task performance was assessed after by combining the tracking task with an auditory reaction time task. Results showed both groups learned equally well and tracking performance on a predictable segment in the dual-task condition was better than on random segments. However, reaction times did not benefit from a predictable tracking segment. To investigate the effect of learning under dual-task situation participants in Experiment 2 practiced the tracking task while simultaneously performing the auditory reaction time task. No learning of the repeated segment could be demonstrated for either group during the training blocks, in contrast to the test-block and retention test, where participants performed better on the repeated segment in both dual-task and single-task conditions. Only the explicit group improved from test-block to retention test. As in Experiment 1, reaction times while tracking a predictable segment were no better than reaction times while tracking a random segment. We concluded that predictability has a positive effect only on the predictable task itself possibly because of a task-shielding mechanism. For dual-task training there seems to be an initial negative effect of explicit instructions, possibly because of fatigue, but the advantage of explicit instructions was demonstrated in a retention test. This might be due to the explicit memory system informing or aiding the implicit memory system.

  9. Effects of laser remelting on microstructures and immersion corrosion performance of arc sprayed Al coating in 3.5% NaCl solution

    Science.gov (United States)

    Sun, Ze; Zhang, Donghui; Yan, Baoxu; Kong, Dejun

    2018-02-01

    An arc sprayed aluminum (Al) coating on S355 steel was processed using a laser remelting (LR). The microstructures, chemical element composition, and phases of the obtained Al coating were analyzed using a field mission scanning electronic microscope (FESEM), energy dispersive spectrometer (EDS), and X-ray diffractometer (XRD), respectively, and the residual stresses were measured using an X-ray diffraction stress tester. The immersion corrosion tests and potentiodynamic polarization of Al coating in 3.5% NaCl solution were performed to investigate the effects of LR on its immersion corrosion behaviors, and the corrosion mechanism of Al coating was also discussed. The results show that the arc sprayed Al coating is composed of Al phase, while that by LR is composed of Al-Fe and AlO4FeO6 phases, and the porosities and cracks in the arc sprayed Al coating are eliminated by LR, The residual stress of arc sprayed Al coating is -5.6 ± 18 MPa, while that after LR is 137.9 ± 12 MPa, which deduces the immersion corrosion resistance of Al coating. The corrosion mechanism of arc sprayed Al coating is pitting corrosion and crevice corrosion, while that by LR is uniform corrosion and pitting corrosion. The corrosion potential of arc sprayed Al coating by LR shifts positively, which improves its immersion corrosion resistance.

  10. Seismic load resistance of reinforcing steels in the as delivered condition and after corrosion - relevant material characteristics for performance evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Moersch, Ing. Joerg [Max Aicher Engineering GmbH, Freilassing (Germany)

    2016-10-15

    This type of accelerated corrosion test was used to study the high number of test samples in due time. The corrosion phenomena obtained in salt spray testing deviate significantly from corrosion phenomena (pitting factor) obtained in practical conditions. Salt spray testing represents practical conditions for the more uniform corrosion as a result of a severe carbonation of the concrete and/or for higher chloride contents at the surface of the rebar. At low corrosion current densities the effect of pit depth on residual mechanical performance might be underestimated. Reinforced concrete (r.c.) buildings in seismic areas shall be designed to guarantee enough ductile resources as for example a sufficient rotational capacity to allow for load re-distribution. The rotational capacity is directly dependent on the ductility of the reinforcing steel which is generally expressed as elongation at maximum load (A+g{sub t}) and the hardening ratio (R{sub m}/R{sub e}). A direct testing of the seismic load resistance of reinforcing steels is not part of the construction product standards. Therefore it was decided by European Commission to introduce this performance requirement in the mandate for the revision of EN 10080:2005. In parallel to the standardization process a research project was carried out to deliver the scientific background.

  11. Multiple Interference Cancellation Performance for GPS Receivers with Dual-Polarized Antenna Arrays

    Directory of Open Access Journals (Sweden)

    Moeness G. Amin

    2008-11-01

    Full Text Available This paper examines the interference cancellation performance in global positioning system (GPS receivers equipped with dual-polarized antenna arrays. In dense jamming environment, different types of interferers can be mitigated by the dual-polarized antennas, either acting individually or in conjunction with other receiver antennas. We apply minimum variance distorntionless response (MVDR method to a uniform circular dual-polarized antenna array. The MVDR beamformer is constructed for each satellite. Analysis of the eigenstructures of the covariance matrix and the corresponding weight vector polarization characteristics are provided. Depending on the number of jammers and jammer polarizations, the array chooses to expend its degrees of freedom to counter the jammer polarization or/and use phase coherence to form jammer spatial nulls. Results of interference cancellations demonstrate that applying multiple MVDR beamformers, each for one satellite, has a superior cancellation performance compared to using only one MVDR beamformer for all satellites in the field of view.

  12. Friction, adhesion and corrosion performance of metallurgical coatings in HTGR-helium

    International Nuclear Information System (INIS)

    Engel, R.; Kleemann, W.

    1981-01-01

    The friction-, adhesion-, thermal cycling- and corrosion performance of several metallurgical coating systems have been tested in a simulated HTGR-test atmosphere at elevated temperatures. The coatings were applied to a solid solution strengthened Ni-based superalloy. Component design requires coatings for the protection of mating surfaces, since under reactor operating conditions, contacting surfaces of metallic components under high pressures are prone to friction and wear damage. The coatings will have to protect the metal surface for 30 years up to 950 0 C in HTGR-helium. The materials tested were various refractory carbides with or without metallic binders and intermetallic compounds. The coatings evaluated were applied by plasma spraying-, detonation gun- and chemical vapor deposition techniques. These yielded two types of coatings which employ different mechanisms to improve the tribiological properties and maintain coating integrity. (Auth.)

  13. Analysis of Barrier Performance: Modelling of Copper corrosion scenarios with and without buffer erosion

    International Nuclear Information System (INIS)

    Benbow, Steven J.; Robinson, Peter C.; Watson, Sarah P.

    2011-02-01

    SKB have identified buffer erosion as a process that could potentially lead to increased corrosion of the copper canister. Buffer erosion can be caused by: the formation of bentonite (i.e., montmorillonite) colloids and their transport away from deposition holes in intersecting fractures containing dilute groundwaters (such as subglacial meltwaters); steep hydraulic gradients during buffer resaturation; or shearing of solid bentonite particles by rapidly flowing groundwater. Only colloidal removal of bentonite (the first of the processes listed) is considered in this study. The erosion of the bentonite leads to a reduction in density and swelling potential, and hence a lowering of transport resistances in the buffer that can make it easier for corrosive agents to transported to be the canister surface, resulting in increased levels of corrosion of the canister surface compared with those predicted in 'normal evolution' conditions. The reduction in bentonite density that follows as a consequence of erosion also leads to the possibility of breaching other safety functions of the buffer, for example prevention of canister sinking and resistance to shear deformation. These are not considered in this study. This report describes the modelling of copper corrosion processes in the SKB KBS-3 design concept. The modelling includes an initial representation of all relevant physical processes, but with some processes represented in more detail than others. This allows investigation of the impacts of the processes that are modelled on canister corrosion, allowing identification of the processes that impact most on the key performance measures for the EBS, which will help to focus modelling developments in future work. This work could be taken as the starting point in a longer-term modelling study in which the interactions between processes that affect canister corrosion are further investigated. Two high-level scenarios are considered in this work: a base case scenario in

  14. Analysis of Barrier Performance: Modelling of Copper corrosion scenarios with and without buffer erosion

    Energy Technology Data Exchange (ETDEWEB)

    Benbow, Steven J.; Robinson, Peter C.; Watson, Sarah P. (Quintessa Limited, Henley-on-Thames (United Kingdom))

    2011-02-15

    SKB have identified buffer erosion as a process that could potentially lead to increased corrosion of the copper canister. Buffer erosion can be caused by: the formation of bentonite (i.e., montmorillonite) colloids and their transport away from deposition holes in intersecting fractures containing dilute groundwaters (such as subglacial meltwaters); steep hydraulic gradients during buffer resaturation; or shearing of solid bentonite particles by rapidly flowing groundwater. Only colloidal removal of bentonite (the first of the processes listed) is considered in this study. The erosion of the bentonite leads to a reduction in density and swelling potential, and hence a lowering of transport resistances in the buffer that can make it easier for corrosive agents to transported to be the canister surface, resulting in increased levels of corrosion of the canister surface compared with those predicted in 'normal evolution' conditions. The reduction in bentonite density that follows as a consequence of erosion also leads to the possibility of breaching other safety functions of the buffer, for example prevention of canister sinking and resistance to shear deformation. These are not considered in this study. This report describes the modelling of copper corrosion processes in the SKB KBS-3 design concept. The modelling includes an initial representation of all relevant physical processes, but with some processes represented in more detail than others. This allows investigation of the impacts of the processes that are modelled on canister corrosion, allowing identification of the processes that impact most on the key performance measures for the EBS, which will help to focus modelling developments in future work. This work could be taken as the starting point in a longer-term modelling study in which the interactions between processes that affect canister corrosion are further investigated. Two high-level scenarios are considered in this work: a base case

  15. Corrosion/96 conference papers

    International Nuclear Information System (INIS)

    Anon.

    1996-01-01

    Topics covered by this conference include: cathodic protection in natural waters; cleaning and repassivation of building HVAC systems; worldwide opportunities in flue gas desulfurization; advancements in materials technology for use in oil and gas service; fossil fuel combustion and conversion; technology of corrosion inhibitors; computers in corrosion control--modeling and information processing; recent experiences and advances of austenitic alloys; managing corrosion with plastics; corrosion measurement technology; corrosion inhibitors for concrete; refining industry; advances in corrosion control for rail and tank trailer equipment; CO 2 corrosion--mechanisms and control; microbiologically influenced corrosion; corrosion in nuclear systems; role of corrosion in boiler failures; effects of water reuse on monitoring and control technology in cooling water applications; methods and mechanisms of scale and deposit control; corrosion detection in petroleum production lines; underground corrosion control; environmental cracking--relating laboratory results and field behavior; corrosion control in reinforced concrete structures; corrosion and its control in aerospace and military hardware; injection and process addition facilities; progress reports on the results of reinspection of deaerators inspected or repaired per RP0590 criteria; near 100% volume solids coating technology and application methods; materials performance in high temperature environments containing halides; impact of toxicity studies on use of corrosion/scale inhibitors; mineral scale deposit control in oilfield related operations; corrosion in gas treating; marine corrosion; cold climate corrosion; corrosion in the pulp and paper industry; gaseous chlorine alternatives in cooling water systems; practical applications of ozone in recirculating cooling water systems; and water reuse in industry. Over 400 papers from this conference have been processed separately for inclusion on the data base

  16. Ultrahigh PEMFC performance of a thin-film, dual-electrode assembly with tailored electrode morphology.

    Science.gov (United States)

    Jung, Chi-Young; Kim, Tae-Hyun; Yi, Sung-Chul

    2014-02-01

    A dual-electrode membrane electrode assembly (MEA) for proton exchange membrane fuel cells with enhanced polarization under zero relative humidity (RH) is fabricated by introducing a phase-separated morphology in an agglomerated catalyst layer of Pt/C (platinum on carbon black) and Nafion. In the catalyst layer, a sufficient level of phase separation is achieved by dispersing the Pt catalyst and the Nafion dispersion in a mixed-solvent system (propane-1,2,3-triol/1-methyl-2-pyrrolidinone).The high polymer chain mobility results in improved water uptake and regular pore-size distribution with small pore diameters. The electrochemical performance of the dual-film electrode assembly with different levels of phase separation is compared to conventional electrode assemblies. As a result, good performance at 0 % RH is obtained because self-humidification is dramatically improved by attaching this dense and phase-separated catalytic overlayer onto the conventional catalyst layer. A MEA prepared using the thin-film, dual-layered electrode exhibits 39-fold increased RH stability and 28-fold improved start-up recovery time during the on-off operation relative to the conventional device. We demonstrate the successful operation of the dual-layered electrode comprised of discriminatively phase-separated agglomerates with an ultrahigh zero RH fuel-cell performance reaching over 95 % performance of a fully humidified MEA. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Evaluation of the dual digestion system 2: operation and performance of the pure oxygen aerobic reactor

    CSIR Research Space (South Africa)

    Messenger, JR

    1993-07-01

    Full Text Available In a comprehensive study of the performance of a full-scale (45 m3) pure oxygen autothermal thermophilic aerobic reactor of a sewage sludge dual digestion system, it was found that: Biological heat generation rate was directly proportional...

  18. Attention Deficit ِDuring Dual-Task Performance in Alzheimer’s Disease Patients

    Directory of Open Access Journals (Sweden)

    Hamid Salehi

    2014-07-01

    Full Text Available Objectives: The aims of the present investigation was the evaluation of divided attention deficits in Alzheimer's disease (AD patients by using dual-task paradigm in order to ascertain whether this method can be useful in the early diagnosis of AD or not.  Methods & Materials: A total of 23 elderly individuals (11 females and 12 males voluntarily participated in the investigation: 13 patients with Alzheimer's disease (AD and 10 healthy elderly individuals. The experimental setup consisted of (a single -task and (b dual-task trials at two levels of difficulty. In singletask condition, the participants were asked to recite the months of the year continuously with normal order (easy and backward (difficult. They also performed a computerized visuospatial/motor tracking task. The participants then performed the tracking task in conjunction with each of the months reciting tasks as dual-task condition. Results: The results showed a significant interaction (disease×level of difficulty effect. So that, the performance impairment on combine performance in two simultaneous tasks was related to task difficulty, but the elderly control group did not differ in the easy and difficult conditions. Conclusion: These findings not only increase our understanding of the attention deficits in AD patients, but also have implications for the mediating effect of cognitive load in using dual-task paradigm for studying attention mechanisms of cognitively suffered individuals.

  19. Performance Analysis of Mixed Nakagami- m and Gamma–Gamma Dual-Hop FSO Transmission Systems

    KAUST Repository

    Zedini, Emna; Ansari, Imran Shafique; Alouini, Mohamed-Slim

    2015-01-01

    In this paper, we carry out a unified performance analysis of a dual-hop relay system over the asymmetric links composed of both radio-frequency (RF) and unified free-space optical (FSO) links under the effect of pointing errors. Both fixed

  20. Locus of Semantic Interference in Picture Naming: Evidence from Dual-Task Performance

    Science.gov (United States)

    Piai, Vitória; Roelofs, Ardi; Schriefers, Herbert

    2014-01-01

    Disagreement exists regarding the functional locus of semantic interference of distractor words in picture naming. This effect is a cornerstone of modern psycholinguistic models of word production, which assume that it arises in lexical response-selection. However, recent evidence from studies of dual-task performance suggests a locus in…

  1. Impact d'une modulation duale sur les performances d'une liaison ...

    African Journals Online (AJOL)

    Le présent document présente la technique de modulation duale Fréquence - Amplitude dans le cas d'une liaison optique du type IM-DD. Ce travail révèle que la modulation duale Fréquence - Amplitude permet de générer un signal à bande latérale unique. Les performances d'une liaison optique IM-DD basée sur cette ...

  2. Dual-band frequency selective surface with large band separation and stable performance

    Science.gov (United States)

    Zhou, Hang; Qu, Shao-Bo; Peng, Wei-Dong; Lin, Bao-Qin; Wang, Jia-Fu; Ma, Hua; Zhang, Jie-Qiu; Bai, Peng; Wang, Xu-Hua; Xu, Zhuo

    2012-05-01

    A new technique of designing a dual-band frequency selective surface with large band separation is presented. This technique is based on a delicately designed topology of L- and Ku-band microwave filters. The two band-pass responses are generated by a capacitively-loaded square-loop frequency selective surface and an aperture-coupled frequency selective surface, respectively. A Faraday cage is located between the two frequency selective surface structures to eliminate undesired couplings. Based on this technique, a dual-band frequency selective surface with large band separation is designed, which possesses large band separation, high selectivity, and stable performance under various incident angles and different polarizations.

  3. Influence of nanoclay particles modification by polyester-amide hyperbranched polymer on the corrosion protective performance of the epoxy nanocomposite

    International Nuclear Information System (INIS)

    Ganjaee Sari, M.; Ramezanzadeh, B.; Shahbazi, M.; Pakdel, A.S.

    2015-01-01

    Highlights: • Nanoclay particles were modified with polyester-amide hyperbranched polymer. • Epoxy/clay nanocomposites were prepared using modified clay particles. • Surface modification enhanced the clay particles exfoliation properties. • Surface modified clay particles enhanced corrosion resistance of the epoxy coating. - Abstract: Surface modification of nanoclay particles was carried out by various amounts of polyester-amide hyperbranched polymer (HBP). Thermal gravimetric analysis and X-ray diffraction analysis were performed to estimate the efficiency of the HPB grafting on the clay particles. Epoxy/clay nanocomposites were prepared by addition of 1 wt.% unmodified and modified clays. The corrosion protection properties of the nanocomposites were evaluated by electrochemical impedance spectroscopy (EIS). Results revealed that surface modification of the clay particles by HBP caused significant enhancement of the epoxy coating corrosion resistance especially when the ‘polymer/clay’ ratios were 10/1 and 5/1

  4. Composite plasma electrolytic oxidation to improve the thermal radiation performance and corrosion resistance on an Al substrate

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Donghyun [Department of Materials Science and Engineering, Pusan National University, Busan 46241 (Korea, Republic of); Sung, Dahye [Department of Materials Science and Engineering, Pusan National University, Busan 46241 (Korea, Republic of); Korea Institute of Industrial Technology (KITECH), Busan 46742 (Korea, Republic of); Lee, Junghoon [Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, NJ 07030 (United States); Kim, Yonghwan [Korea Institute of Industrial Technology (KITECH), Busan 46742 (Korea, Republic of); Chung, Wonsub, E-mail: wschung1@pusan.ac.kr [Department of Materials Science and Engineering, Pusan National University, Busan 46241 (Korea, Republic of)

    2015-12-01

    Highlights: • Composite plasma electrolytic oxidation was performed using dispersed CuO particles in convectional PEO electrolyte. • Thermal radiation performance and corrosion resistance were examined by FT-IR spectroscopy and electrochemical methods, respectively. • Deposited copper oxide on the surface of the Al substrate was enhanced the corrosion resistance and the emissivity compared with the conventional PEO. - Abstract: A composite plasma electrolytic oxidation (PEO) was performed for enhancing the thermal radiation performance and corrosion resistance on an Al alloy by dispersing cupric oxide (CuO) particles in a conventional PEO electrolyte. Cu-based oxides (CuO and Cu{sub 2}O) formed by composite PEO increased the emissivity of the substrate to 0.892, and made the surface being dark color, similar to a black body, i.e., an ideal radiator. In addition, the corrosion resistance was analyzed using potentio-dynamic polarization and electrochemical impedance spectroscopy tests in 3.5 wt.% NaCl aqueous solution. An optimum condition of 10 ampere per square decimeter (ASD) current density and 30 min processing time produced appropriate surface morphologies and coating thicknesses, as well as dense Cu- and Al-based oxides that constituted the coating layers.

  5. Sensorimotor Adaptability Training Improves Motor and Dual-Task Performance

    Science.gov (United States)

    Bloomberg, J.J.; Peters, B.T.; Mulavara, A.P.; Brady, R.; Batson, C.; Cohen, H.S.

    2009-01-01

    The overall objective of our project is to develop a sensorimotor adaptability (SA) training program designed to facilitate recovery of functional capabilities when astronauts transition to different gravitational environments. The goal of our current study was to determine if SA training using variation in visual flow and support surface motion produces improved performance in a novel sensory environment and demonstrate the retention characteristics of SA training.

  6. Performance of a dual-process PVD/PS tungsten coating structure under deuterium ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyunmyung; Lee, Ho Jung; Kim, Sung Hwan [Department of Nuclear and Quantum Engineering, KAIST, Daejeon (Korea, Republic of); Song, Jae-Min [Department of Nuclear Engineering, Seoul National University, Seoul (Korea, Republic of); Jang, Changheui, E-mail: chjang@kaist.ac.kr [Department of Nuclear and Quantum Engineering, KAIST, Daejeon (Korea, Republic of)

    2016-11-01

    Highlights: • D{sup +} irradiation performance of a dual-process PVD/PS W coating was evaluated. • Low-energy plasmas exposure of 100 eV D{sup +} with 1.17 × 10{sup 21} D/s{sup −1} m{sup 2} flux was applied. • After D ion irradiation, flakes were observed on the surface of the simple PS coating. • While, sub-μm size protrusions were observed for dual-process PVD/PS W coating. • Height of D spike in depth profile was lower for dual-process PVD/PS W coating. - Abstract: A dual-process coating structure was developed on a graphite substrate to improve the performance of the coating structure under anticipated operating condition of fusion devices. A thin multilayer W/Mo coating (6 μm) was deposited by physical vapor deposition (PVD) method with a variation of Mo interlayer thickness on plasma spray (PS) W coating (160 μm) of a graphite substrate panel. The dual-process PVD/PS W coatings then were exposed to 3.08 × 10{sup 24} D m{sup −2} of 100 eV D ions with a flux of 1.71 × 10{sup 21} D m{sup −2} s{sup −1} in an electron cyclotron resonance (ECR) chamber. After irradiation, surface morphology and D depth profiles of the dual-process coating were analyzed and compared to those of the simple PS W coating. Both changes in surface morphology and D retention were strongly dependent on the microstructure of surface coating. Meanwhile, the existence of Mo interlayer seemed to have no significant effect on the retention of deuterium.

  7. Structural performance evaluation on aging underground reinforced concrete structures. Part 6. An estimation method of threshold value in performance verification taking reinforcing steel corrosion

    International Nuclear Information System (INIS)

    Matsuo, Toyofumi; Matsumura, Takuro; Miyagawa, Yoshinori

    2009-01-01

    This paper discusses applicability of material degradation model due to reinforcing steel corrosion for RC box-culverts with corroded reinforcement and an estimation method for threshold value in performance verification reflecting reinforcing steel corrosion. First, in FEM analyses, loss of reinforcement section area and initial tension strain arising from reinforcing steel corrosion, and deteriorated bond characteristics between reinforcement and concrete were considered. The full-scale loading tests using corroded RC box-culverts were numerically analyzed. As a result, the analyzed crack patterns and load-strain relationships were in close agreement with the experimental results within the maximum corrosion ratio 15% of primary reinforcement. Then, we showed that this modeling could estimate the load carrying capacity of corroded RC box-culverts. Second, a parametric study was carried out for corroded RC box culverts with various sizes, reinforcement ratios and levels of steel corrosion, etc. Furthermore, as an application of analytical results and various experimental investigations, we suggested allowable degradation ratios for a modification of the threshold value, which corresponds to the chloride induced deterioration progress that is widely accepted in maintenance practice for civil engineering reinforced concrete structures. Finally, based on these findings, we developed two estimation methods for threshold value in performance verification: 1) a structural analysis method using nonlinear FEM included modeling of material degradation, 2) a practical method using a threshold value, which is determined by structural analyses of RC box-culverts in sound condition, is multiplied by the allowable degradation ratio. (author)

  8. Erosion-corrosion

    International Nuclear Information System (INIS)

    Aghili, B.

    1999-05-01

    A literature study on erosion-corrosion of pipings in the nuclear industry was performed. Occurred incidents are reviewed, and the mechanism driving the erosion-corrosion is described. Factors that influence the effect in negative or positive direction are treated, as well as programs for control and inspection. Finally, examples of failures from databases on erosion-corrosion are given in an attachment

  9. Central as well as peripheral attentional bottlenecks in dual-task performance activate lateral prefrontal cortices

    Directory of Open Access Journals (Sweden)

    Andre J Szameitat

    2016-03-01

    Full Text Available Human information processing suffers from severe limitations in parallel processing. In particular, when required to respond to two stimuli in rapid succession, processing bottlenecks may appear at central and peripheral stages of task processing. Importantly, it has been suggested that executive functions are needed to resolve the interference arising at such bottlenecks. The aims of the present study were to test whether central attentional limitations (i.e., bottleneck at the decisional response selection stage as well as peripheral limitations (i.e., bottleneck at response initiation both demand executive functions located in the lateral prefrontal cortex. For this, we re-analysed two previous studies, in which a total of 33 participants performed a dual-task according to the paradigm of the psychological refractory period (PRP during fMRI. In one study (N=17, the PRP task consisted of two two-choice response tasks known to suffer from a central bottleneck (CB group. In the other study (N=16, the PRP task consisted of two simple-response tasks known to suffer from a peripheral bottleneck (PB group. Both groups showed considerable dual-task costs in form of slowing of the second response in the dual-task (PRP effect. Imaging results are based on the subtraction of both single-tasks from the dual-task within each group. In the CB group, the bilateral middle frontal gyri and inferior frontal gyri were activated. Higher activation in these areas was associated with lower dual-task costs. In the PB group, the right middle frontal and inferior frontal gyrus were activated. Here, higher activation was associated with higher dual-task costs. In conclusion we suggest that central and peripheral bottlenecks both demand executive functions located in lateral prefrontal cortices. Differences between the CB and PB groups with respect to the exact prefrontal areas activated and the correlational patterns suggest that the executive functions resolving

  10. Dictionary corrosion and corrosion control

    International Nuclear Information System (INIS)

    1985-01-01

    This dictionary has 13000 entries in both languages. Keywords and extensive accompanying information simplify the choice of word for the user. The following topics are covered: Theoretical principles of corrosion; Corrosion of the metals and alloys most frequently used in engineering. Types of corrosion - (chemical-, electro-chemical, biological corrosion); forms of corrosion (superficial, pitting, selective, intercrystalline and stress corrosion; vibrational corrosion cracking); erosion and cavitation. Methods of corrosion control (material selection, temporary corrosion protection media, paint and plastics coatings, electro-chemical coatings, corrosion prevention by treatment of the corrosive media); Corrosion testing methods. (orig./HP) [de

  11. Comparison of performance of biodiesels of mahua oil and gingili oil in dual fuel engine

    Directory of Open Access Journals (Sweden)

    Nadar Kapilan N.

    2008-01-01

    Full Text Available In this work, an experimental work was carried out to compare the performance of biodiesels made from non edible mahua oil and edible gingili oil in dual fuel engine. A single cylinder diesel engine was modified to work in dual fuel mode and liquefied petroleum gas was used as primary fuel. Biodiesel was prepared by transesterification process and mahua oil methyl ester (MOME and gingili oil methyl ester (GOME were used as pilot fuels. The viscosity of MOME is slightly higher than GOME. The dual fuel engine runs smoothly with MOME and GOME. The test results show that the performance of the MOME is close to GOME, at the pilot fuel quantity of 0.45 kg/h and at the advanced injection timing of 30 deg bTDC. Also it is observed that the smoke, carbon monoxide and unburnt hydro carbon emissions of GOME lower than the MOME. But the GOME results in slightly higher NOx emissions. From the experimental results it is concluded that the biodiesel made from mahua oil can be used as a substitute for diesel in dual fuel engine.

  12. Corrosion and mechanical performance of AZ91 exposed to simulated inflammatory conditions.

    Science.gov (United States)

    Brooks, Emily K; Der, Stephanie; Ehrensberger, Mark T

    2016-03-01

    Magnesium (Mg) and its alloys, including Mg-9%Al-1%Zn (AZ91), are biodegradable metals with potential use as temporary orthopedic implants. Invasive orthopedic procedures can provoke an inflammatory response that produces hydrogen peroxide (H2O2) and an acidic environment near the implant. This study assessed the influence of inflammation on both the corrosion and mechanical properties of AZ91. The AZ91 samples in the inflammatory protocol were immersed for three days in a complex biologically relevant electrolyte (AMEM culture media) that contained serum proteins (FBS), 150 mM of H2O2, and was titrated to a pH of 5. The control protocol immersed AZ91 samples in the same biologically relevant electrolyte (AMEM & FBS) but without H2O2 and the acid titration. After 3 days all samples were switched into fresh AMEM & FBS for an additional 3-day immersion. During the initial immersion, inflammatory protocol samples showed increased corrosion rate determined by mass loss testing, increased Mg and Al ion released to solution, and a completely corroded surface morphology as compared to the control protocol. Although corrosion in both protocols slowed once the test electrolyte solution was replaced at 3 days, the samples originally exposed to the simulated inflammatory conditions continued to display enhanced corrosion rates as compared to the control protocol. These lingering effects may indicate the initial inflammatory corrosion processes modified components of the surface oxide and corrosion film or initiated aggressive localized processes that subsequently left the interface more vulnerable to continued enhanced corrosion. The electrochemical properties of the interfaces were also evaluated by EIS, which found that the corrosion characteristics of the AZ91 samples were potentially influenced by the role of intermediate adsorption layer processes. The increased corrosion observed for the inflammatory protocol did not affect the flexural mechanical properties of the AZ91

  13. Steam based conversion coating on AA6060 alloy: Effect of sodium silicate chemistry and corrosion performance

    Science.gov (United States)

    Din, Rameez Ud; Bordo, Kirill; Tabrizian, Naja; Jellesen, Morten Stendahl; Ambat, Rajan

    2017-11-01

    Surface treatment of aluminium alloy AA6060 using an industrially applicable pilot steam jet system with and without silicate chemistry has been investigated. Treatment using steam alone and steam with silicate, resulted in an oxide layer formation with thickness ∼425 nm and ∼160 nm, respectively. Moreover, the use of sodium silicate resulted in the formation of distinct microstructure and incorporation of silicate into the oxide film. These oxide films reduced the anodic activity 4 times, while the corrosion protection by silicate containing oxide was the function of its concentration. Further, in acid salt spray and filiform corrosion tests, oxide layer containing silicate exhibited two times higher corrosion resistance.

  14. Corrosion Protection Performance of Polyester-Melamine Coating with Natural Wood Fiber Using EIS Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Shin, PyongHwa; Shon, MinYoung [Pukyong National University, Busan (Korea, Republic of); Jo, DuHwan [POSCO, Gwangyang (Korea, Republic of)

    2016-04-15

    In the present study, polyester-melamine coating systems with natural wood fiber (NWF) were prepared and the effects of NWF on the corrosion protectiveness of the polyester-melamine coating were examined using EIS analysis. From the results, higher average surface roughness was observed with increase of NWF content. Water diffusivity and water uptake into the polyester-melamine coatings with NWF were much higher than that into the pure polyester-melamine coating. The decrease in the impedance modulus |Z| was associated with the localized corrosion on carbon steel, confirming that corrosion protection of the polyester-melamine coatings with NWF well agrees with its water transport behavior.

  15. Cognitive demand of human sensorimotor performance during an extended space mission: a dual-task study.

    Science.gov (United States)

    Bock, Otmar; Weigelt, Cornelia; Bloomberg, Jacob J

    2010-09-01

    Two previous single-case studies found that the dual-task costs of manual tracking plus memory search increased during a space mission, and concluded that sensorimotor deficits during spaceflight may be related to cognitive overload. Since dual-task costs were insensitive to the difficulty of memory search, the authors argued that the overload may reflect stress-related problems of multitasking, rather than a scarcity of specific cognitive resources. Here we expand the available database and compare different types of concurrent task. Three subjects were repeatedly tested before, during, and after an extended mission on the International Space Station (ISS). They performed an unstable tracking task and four reaction-time tasks, both separately and concurrently. Inflight data could only be obtained during later parts of the mission. The tracking error increased from pre- to in flight by a factor of about 2, both under single- and dual-task conditions. The dual-task costs with a reaction-time task requiring rhythm production was 2.4 times higher than with a reaction-time task requiring visuo-spatial transformations, and 8 times higher than with a regular choice reaction-time task. Long-term sensorimotor deficits during spaceflight may reflect not only stress, but also a scarcity of resources related to complex motor programming; possibly those resources are tied up by sensorimotor adaptation to the space environment.

  16. Performance Analysis Of Single-Pumped And Dual-Pumped Parametric Optical Amplifier

    Directory of Open Access Journals (Sweden)

    Sandar Myint

    2015-06-01

    Full Text Available Abstract In this study we present a performance analysis of single-pumped and dual- pumped parametric optical amplifier and present the analysis of gain flatness in dual- pumped Fiber Optical Parametric Amplifier FOPA based on four-wave mixing FWM. Result shows that changing the signal power and pump power give the various gains in FOPA. It is also found out that the parametric gain increase with increase in pump power and decrease in signal power. .Moreover in this paper the phase matching condition in FWM plays a vital role in predicting the gain profile of the FOPAbecause the parametric gain is maximum when the total phase mismatch is zero.In this paper single-pumped parametric amplification over a 50nm gain bandwidth is demonstrated using 500 nm highly nonlinear fiber HNLF and signal achieves about 31dB gain. For dual-pumped parametric amplification signal achieves 26.5dB gains over a 50nm gain bandwidth. Therefore dual-pumped parametric amplifier can provide relatively flat gain over a much wider bandwidth than the single-pumped FOPA.

  17. The inhibition performance of long-chain alkyl-substituted benzimidazole derivatives for corrosion of mild steel in HCl

    International Nuclear Information System (INIS)

    Zhang, Dongqin; Tang, Yongming; Qi, Sijun; Dong, Dawei; Cang, Hui; Lu, Gang

    2016-01-01

    Highlights: • Inhibition performance of long-chain alkyl-substituted benzimidazole. • Benzimidazole segment donating electrons to metal surface. • Non-polar long chain enhancing inhibition by the barrier effect. • Molecular form of DBI more tightly adsorbs on the steel than its protonated form. - Abstract: The corrosion inhibition of a new benzimidazole derivative, 6-(dodecyloxy)-1H-benzo[d]imidazole (DBI), for mild steel in 1 M HCl was investigated in this paper. Computational chemistry was performed to explore the adsorption of DBI on metal surface. Inhibition performance of DBI is attributed to both the direct interaction of benzimidazole segment with iron surface and the barrier effect of the non-polar long chain against aggressive solution. Compared to the protonated form, the molecular form of DBI could more tightly interact with iron surface. These results show that the long-chain alkyl-substituted benzimidazole derivative is of great potential application as corrosion inhibitor.

  18. The applicability of alkaline-resistant glass fiber in cement mortar of road pavement: Corrosion mechanism and performance analysis

    Directory of Open Access Journals (Sweden)

    Qin Xiaochun

    2017-11-01

    Full Text Available The main technical requirements of road pavement concrete are high flexural strength and fatigue durability. Adding glass fiber into concrete could greatly increase flexural strength and wearing resistance of concrete. However, glass fiber has the great potential of corrosion during the cement hydration, which will directly affect the long-term performance and strength stability. In this paper, accelerated corrosion experiments have been done to find out the corrosion mechanism and property of alkali-resistant glass fiber in cement mortar. The applicability and practicability of alkaline-resistant glass fiber in road concrete have been illustrated in the analysis of flexural strength changing trend of cement mortar mixed with different proportions of activated additives to protect the corrosion of glass fiber by cement mortar. The results have shown that a 30% addition of fly ash or 10% addition of silica fume to cement matrix could effectively improve the corrosion resistance of alkali-resistant glass fiber. The optimal mixing amount of alkali-resistant glass fiber should be about 1.0 kg/m3 in consideration of ensuring the compressive strength of reinforced concrete in road pavement. The closest-packing method has been adopted in the mixture ratio design of alkali-resistant glass fiber reinforced concrete, not only to reduce the alkalinity of the cement matrix through large amount addition of activated additives but also to greatly enhance the flexural performance of concrete with the split pressure ratio improvement of 12.5–16.7%. The results suggested a prosperous application prospect for alkaline-resistant glass fiber reinforced concrete in road pavement.

  19. Dual-task performance involving hand dexterity and cognitive tasks and daily functioning in people with schizophrenia: a pilot study.

    Science.gov (United States)

    Lin, Keh-chung; Wu, Yi-fang; Chen, I-chen; Tsai, Pei-luen; Wu, Ching-yi; Chen, Chia-ling

    2015-01-01

    This study investigated separate and concurrent performance on cognitive and hand dexterity tasks and the relationship to daily functioning in 16 people with schizophrenia and 16 healthy control participants. Participants performed the Purdue Pegboard Test and the Serial Seven Subtraction Test under single- and dual-task conditions and completed two daily functioning evaluations. The hand dexterity of all participants declined in the dual-task condition, but the discrepancy between single-task and dual-task hand dexterity was greater in the schizophrenia group than in the control group (p.70, for all). The extent of discrepancy in hand dexterity was negatively correlated with daily functioning in the schizophrenia group (rs=-.3 to -.5, ps=.04-.26). Ability to perform dual tasks may be an indicator of daily functioning in people with schizophrenia. Use of dual-task training may be considered as a therapeutic activity with these clients. Copyright © 2015 by the American Occupational Therapy Association, Inc.

  20. Mood states determine the degree of task shielding in dual-task performance.

    Science.gov (United States)

    Zwosta, Katharina; Hommel, Bernhard; Goschke, Thomas; Fischer, Rico

    2013-01-01

    Current models of multitasking assume that dual-task performance and the degree of multitasking are affected by cognitive control strategies. In particular, cognitive control is assumed to regulate the amount of shielding of the prioritised task from crosstalk from the secondary task. We investigated whether and how task shielding is influenced by mood states. Participants were exposed to two short film clips, one inducing high and one inducing low arousal, of either negative or positive content. Negative mood led to stronger shielding of the prioritised task (i.e., less crosstalk) than positive mood, irrespective of arousal. These findings support the assumption that emotional states determine the parameters of cognitive control and play an important role in regulating dual-task performance.

  1. The effects of glucose dose and dual-task performance on memory for emotional material.

    Science.gov (United States)

    Brandt, Karen R; Sünram-Lea, Sandra I; Jenkinson, Paul M; Jones, Emma

    2010-07-29

    Whilst previous research has shown that glucose administration can boost memory performance, research investigating the effects of glucose on memory for emotional material has produced mixed findings. Whereas some research has shown that glucose impairs memory for emotional material, other research has shown that glucose has no effect on emotional items. The aim of the present research was therefore to provide further investigation of the role of glucose on the recognition of words with emotional valence by exploring effects of dose and dual-task performance, both of which affect glucose facilitation effects. The results replicated past research in showing that glucose administration, regardless of dose or dual-task conditions, did not affect the memorial advantage enjoyed by emotional material. This therefore suggests an independent relationship between blood glucose levels and memory for emotional material. Copyright 2010 Elsevier B.V. All rights reserved.

  2. Design and performance testing of an ultrasonic linear motor with dual piezoelectric actuators.

    Science.gov (United States)

    Smithmaitrie, Pruittikorn; Suybangdum, Panumas; Laoratanakul, Pitak; Muensit, Nantakan

    2012-05-01

    In this work, design and performance testing of an ultrasonic linear motor with dual piezoelectric actuator patches are studied. The motor system consists of a linear stator, a pre-load weight, and two piezoelectric actuator patches. The piezoelectric actuators are bonded with the linear elastic stator at specific locations. The stator generates propagating waves when the piezoelectric actuators are subjected to harmonic excitations. Vibration characteristics of the linear stator are analyzed and compared with finite element and experimental results. The analytical, finite element, and experimental results show agreement. In the experiments, performance of the ultrasonic linear motor is tested. Relationships between velocity and pre-load weight, velocity and applied voltage, driving force and applied voltage, and velocity and driving force are reported. The design of the dual piezoelectric actuators yields a simpler structure with a smaller number of actuators and lower stator stiffness compared with a conventional design of an ultrasonic linear motor with fully laminated piezoelectric actuators.

  3. Tests with Inconel 600 to obtain quantitative stress-corrosion cracking data for evaluating service performance

    International Nuclear Information System (INIS)

    Bandy, R.; van Rooyen, D.

    1982-09-01

    Inconel 600 tubes in pressurized water reactor (PWR) steam generators form a pressure boundary between radioactive primary water and secondary water which is converted to steam and used for generating electricity. Under operating conditions the performance of alloy 600 has been good, but with some occasional small leaks resulting from stress corrosion cracking (SCC), related to the presence of unusually high residual or operating stresses. The suspected high stresses can result from either the deformation of tubes during manufacture, or distortion during abnormal conditions such as denting. The present experimental program addresses two specific conditions, i.e., (1) where deformation occurs but is no longer active, such as when denting is stopped and (2) where plastic deformation of the metal continues, as would occur during denting. Laboratory media consist of pure water as well as solutions to simulate environments that would apply in service; tubing from actual production is used in carrying out these tests. The environments include both normal and off chemistries for primary and secondary water. The results reported here were obtained in several different tests. The main ones are (1) split tube reverse U-bends, (2) constant extension rate tests (CERT), and (3) constant load. The temperature range covered is 290 to 365 0 C

  4. Implementation of Localized Corrosion in the Performance Assessment Model for Yucca Mountain

    International Nuclear Information System (INIS)

    Jain, V.; SEVOUGIAN, D.S.; MATTIE, P.D.; MACKINNON, R.J.

    2005-01-01

    A total system performance assessment (TSPA) model has been developed to analyze the ability of the natural and engineered barriers of the Yucca Mountain repository to isolate nuclear waste for the 10,000-year period following repository closure. The principal features of the engineered barrier system (EBS) are emplacement tunnels (or ''drifts'') containing a two-layer waste package (WP) for waste containment and a titanium drip shield to protect the waste package from seeping water and falling rock. The 20-mm-thick outer shell of the WP is composed of Alloy 22, a highly corrosion-resistant nickel-based alloy, while the 50-mm inner shell is composed of 316 stainless steel (modified with lower carbon and nitrogen compositions), whose primary purpose is to provide structural strength. The barrier function of the EBS is to isolate the waste from the migrating water with its associated chemical conditions that eventually lead to degradation of the waste packages and mobilization of the radionuclides within the packages

  5. Effect of Surface Contaminants Remained on the Blasted Surface on Epoxy Coating Performance and Corrosion Resistance

    International Nuclear Information System (INIS)

    Baek, Kwang Ki; Park, Chung Seo; Kim, Ki Hong; Chung, Mong Kyu; Park, Jin Hwan

    2006-01-01

    One of the critical issues in the coating specification is the allowable limit of surface contaminant(s) - such as soluble salt(s), grit dust, and rust - after grit blasting. Yet, there is no universally accepted data supporting the relationship between the long-term coating performance and the amount of various surface contaminants allowed after grit blasting. In this study, it was attempted to prepare epoxy coatings applied on grit-blasted steel substrate dosed with controlled amount of surface contaminants - such as soluble salt(s), grit dust, and rust. Then, coating samples were subjected to 4,200 hours of cyclic test(NORSOK M-501), which were then evaluated in terms of resistance to rust creepage, blistering, chalking, rusting, cracking and adhesion strength. Additional investigations on the possible damage at the paint/steel interface were carried out using an Electrochemical Impedance Spectroscopy(EIS) and observations of under-film-corrosion. Test results suggested that the current industrial specifications were well matched with the allowable degree of rust, whereas the allowable amount of soluble salt and grit dust after grit blasting showed a certain deviation from the specifications currently employed for fabrication of marine vessels and offshore facilities

  6. Performance of low-resistivity single and dual-gap RPCs for LHCb

    CERN Document Server

    Adinolfi, M; Messi, R; Pacciani, L; Paoluzi, L; Santovetti, E

    2000-01-01

    Resistive plate chambers (RPC) are strong candidates for the outer regions of the LHCb muon detector. We have tested single-gap and dual-gap detectors built with low-resistivity phenolic plates ( rho =9*10/sup 9/ Omega cm) and operated in avalanche mode. Measurements have been performed over a wide range of beam intensities and on the GIF at CERN. The results are presented and discussed, with special emphasis on the detection efficiency. (6 refs).

  7. Performance of low resistivity single and dual-gap RPCs for LHCb

    CERN Document Server

    Adinolfi, M; Messi, R; Pacciani, L; Santovetti, E; Santovetti, Emanuele

    1999-01-01

    99-049 RPCs are strong candidates for the outer regions of the LHCb muon detector. We have tested single-gap and dual-gap detectors built with low-resistivity phenolic plates (ro = 9 x 10^9 microcm) and operated in avalanche mode. Measurements have been performed over a wide range of beam intensities and on the GIF at CERN. The results are presented and discussed, with special emphasis on the detection efficiency.

  8. The Assessment of Military Multitasking Performance: Validation of a Dual-Task and Multitask Protocol

    Science.gov (United States)

    2015-11-01

    preliminary validity of the Walking and Remembering Test. Journal of geriatric physical therapy . 2009;32(1):2-9. 23. Mancini M, Salarian A, Carlson-Kuhta P...MacMillan), American Physical Therapy Association (APTA) 2014 Annual conference, Charlotte, NC 88 August 18-21, 2014 (paper) A novel dual...Multitasking Performance for Mild TBI. Federal Section, American Physical Therapy Association’s Combined Section Meeting, (Weightman, Scherer, McCulloch

  9. On the importance of Task 1 and error performance measures in PRP dual-task studies

    Science.gov (United States)

    Strobach, Tilo; Schütz, Anja; Schubert, Torsten

    2015-01-01

    The psychological refractory period (PRP) paradigm is a dominant research tool in the literature on dual-task performance. In this paradigm a first and second component task (i.e., Task 1 and Task 2) are presented with variable stimulus onset asynchronies (SOAs) and priority to perform Task 1. The main indicator of dual-task impairment in PRP situations is an increasing Task 2-RT with decreasing SOAs. This impairment is typically explained with some task components being processed strictly sequentially in the context of the prominent central bottleneck theory. This assumption could implicitly suggest that processes of Task 1 are unaffected by Task 2 and bottleneck processing, i.e., decreasing SOAs do not increase reaction times (RTs) and error rates of the first task. The aim of the present review is to assess whether PRP dual-task studies included both RT and error data presentations and statistical analyses and whether studies including both data types (i.e., RTs and error rates) show data consistent with this assumption (i.e., decreasing SOAs and unaffected RTs and/or error rates in Task 1). This review demonstrates that, in contrast to RT presentations and analyses, error data is underrepresented in a substantial number of studies. Furthermore, a substantial number of studies with RT and error data showed a statistically significant impairment of Task 1 performance with decreasing SOA. Thus, these studies produced data that is not primarily consistent with the strong assumption that processes of Task 1 are unaffected by Task 2 and bottleneck processing in the context of PRP dual-task situations; this calls for a more careful report and analysis of Task 1 performance in PRP studies and for a more careful consideration of theories proposing additions to the bottleneck assumption, which are sufficiently general to explain Task 1 and Task 2 effects. PMID:25904890

  10. On the importance of Task 1 and error performance measures in PRP dual-task studies.

    Science.gov (United States)

    Strobach, Tilo; Schütz, Anja; Schubert, Torsten

    2015-01-01

    The psychological refractory period (PRP) paradigm is a dominant research tool in the literature on dual-task performance. In this paradigm a first and second component task (i.e., Task 1 and Task 2) are presented with variable stimulus onset asynchronies (SOAs) and priority to perform Task 1. The main indicator of dual-task impairment in PRP situations is an increasing Task 2-RT with decreasing SOAs. This impairment is typically explained with some task components being processed strictly sequentially in the context of the prominent central bottleneck theory. This assumption could implicitly suggest that processes of Task 1 are unaffected by Task 2 and bottleneck processing, i.e., decreasing SOAs do not increase reaction times (RTs) and error rates of the first task. The aim of the present review is to assess whether PRP dual-task studies included both RT and error data presentations and statistical analyses and whether studies including both data types (i.e., RTs and error rates) show data consistent with this assumption (i.e., decreasing SOAs and unaffected RTs and/or error rates in Task 1). This review demonstrates that, in contrast to RT presentations and analyses, error data is underrepresented in a substantial number of studies. Furthermore, a substantial number of studies with RT and error data showed a statistically significant impairment of Task 1 performance with decreasing SOA. Thus, these studies produced data that is not primarily consistent with the strong assumption that processes of Task 1 are unaffected by Task 2 and bottleneck processing in the context of PRP dual-task situations; this calls for a more careful report and analysis of Task 1 performance in PRP studies and for a more careful consideration of theories proposing additions to the bottleneck assumption, which are sufficiently general to explain Task 1 and Task 2 effects.

  11. On the importance of Task 1 and error performance measures in PRP dual-task studies

    Directory of Open Access Journals (Sweden)

    Tilo eStrobach

    2015-04-01

    Full Text Available The Psychological Refractory Period (PRP paradigm is a dominant research tool in the literature on dual-task performance. In this paradigm a first and second component task (i.e., Task 1 and 2 are presented with variable stimulus onset asynchronies (SOAs and priority to perform Task 1. The main indicator of dual-task impairment in PRP situations is an increasing Task 2-RT with decreasing SOAs. This impairment is typically explained with some task components being processed strictly sequentially in the context of the prominent central bottleneck theory. This assumption could implicitly suggest that processes of Task 1 are unaffected by Task 2 and bottleneck processing, i.e. decreasing SOAs do not increase RTs and error rates of the first task. The aim of the present review is to assess whether PRP dual-task studies included both RT and error data presentations and statistical analyses and whether studies including both data types (i.e., RTs and error rates show data consistent with this assumption (i.e., decreasing SOAs and unaffected RTs and/ or error rates in Task 1. This review demonstrates that, in contrast to RT presentations and analyses, error data is underrepresented in a substantial number of studies. Furthermore, a substantial number of studies with RT and error data showed a statistically significant impairment of Task 1 performance with decreasing SOA. Thus, these studies produced data that is not primarily consistent with the strong assumption that processes of Task 1 are unaffected by Task 2 and bottleneck processing in the context of PRP dual-task situations; this calls for a more careful report and analysis of Task 1 performance in PRP studies and for a more careful consideration of theories proposing additions to the bottleneck assumption, which are sufficiently general to explain Task 1 and Task 2 effects.

  12. Dual-Task Performance: Influence of Frailty, Level of Physical Activity, and Cognition.

    Science.gov (United States)

    Giusti Rossi, Paulo; Pires de Andrade, Larissa; Hotta Ansai, Juliana; Silva Farche, Ana Claudia; Carnaz, Leticia; Dalpubel, Daniela; Ferriolli, Eduardo; Assis Carvalho Vale, Francisco; de Medeiros Takahashi, Anielle Cristhine

    2018-03-08

    Cognition and level of physical activity have been associated with frailty syndrome. The development of tools that assess deficits related to physical and cognitive frailties simultaneously are of common interest. However, little is known about how much these aspects influence the performance of dual-task tests. Our aims were (a) to verify the influence of frailty syndrome and objectively measured physical activity and cognition on the Timed Up and Go (TUG) test and Timed Up and Go associated with dual-task (TUG-DT) performances; and (b) to compare TUG and TUG-DT performances between older adults who develop frailty syndrome. Sixty-four community-dwelling older adults were divided into frail, prefrail, and nonfrail groups, according to frailty phenotype. Assessments included anamnesis, screening of frailty syndrome, cognitive assessment (Addenbrooke's cognitive examination), placement of a triaxial accelerometer to assess level of physical activity, and TUG and TUG-DT (TUG associated with a motor-cognitive task of calling a phone number) performances. After 7 days, the accelerometer was removed. A multiple linear regression was applied to identify which independent variables could explain performances in the TUG and TUG-DT. Subsequently, the analysis of covariance test, adjusted for age, cognition, and level of physical activity covariates, was used to compare test performances. There were no differences in cognition between groups. Significant differences in the level of physical activity were found in the frail group. Compared with the frail group, the nonfrail group required less time and fewer steps to complete the TUG. Regarding the TUG-DT, cognition and age influenced the time spent and number of steps, respectively; however, no differences were found between groups. Frail older adults presented worse performance in the TUG when compared with nonfrail older adults. The dual-task test does not differentiate older adults with frailty syndrome, regardless of

  13. The Use of AC-DC-AC Methods in Assessing Corrosion Resistance Performance of Coating Systems for Magnesium Alloys

    Science.gov (United States)

    McCune, Robert C.; Upadhyay, Vinod; Wang, Yar-Ming; Battocchi, Dante

    The potential utility of AC-DC-AC electrochemical methods in comparative measures of corrosion-resisting coating system performance for magnesium alloys under consideration for the USAMP "Magnesium Front End Research and Development" project was previously shown in this forum [1]. Additional studies of this approach using statistically-designed experiments have been conducted with focus on alloy types, pretreatment, topcoat material and topcoat thickness as the variables. Additionally, sample coupons made for these designed experiments were also subjected to a typical automotive cyclic corrosion test cycle (SAE J2334) as well as ASTM B117 for comparison of relative performance. Results of these studies are presented along with advantages and limitations of the proposed methodology.

  14. Active corrosion protection performance of an epoxy coating applied on the mild steel modified with an eco-friendly sol-gel film impregnated with green corrosion inhibitor loaded nanocontainers

    Science.gov (United States)

    Izadi, M.; Shahrabi, T.; Ramezanzadeh, B.

    2018-05-01

    In this study the corrosion resistance, active protection, and cathodic disbonding performance of an epoxy coating were improved through surface modification of steel by a hybrid sol-gel system filled with green corrosion inhibitors loaded nanocontainer as intermediate layer on mild steel substrate. The green inhibitor loaded nanocontainers (GIN) were used to induce active inhibition performance in the protective coating system. The corrosion protection performance of the coated panels was investigated by electrochemical impedance spectroscopy (EIS), salt spray, and cathodic disbonding tests. It was observed that the corrosion inhibition performance of the coated mild steel panels was significantly improved by utilization of active multilayer coating system. The inhibitor release from nanocontainers at the epoxy-silane film/steel interface resulted in the anodic and cathodic reactions restriction, leading to the lower coating delamination from the substrate and corrosion products progress. Also, the active inhibition performance of the coating system was approved by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and energy dispersive X-ray (EDS) analysis on the panels with artificial defects. The inhibitive agents were released to the scratch region and blocked the active sites on the metal surface.

  15. Corrosion performance of Al-Si-Cu hypereutectic alloys in a synthetic condensed automotive solution

    Directory of Open Access Journals (Sweden)

    Hamilta de Oliveira Santos

    2005-06-01

    Full Text Available In this investigation the corrosion resistance of four Al-Si hypereutectic alloys in a solution typical of condensate from automotive fuel combustion products, and referred to here as synthetic condensed automotive solution, has been studied. Three commercial alloys that are used for cylinder liners, and a laboratory made alloy, were studied by electrochemical impedance spectroscopy and measurements were taken after increasing times of immersion in this solution. Comparison of the electrochemical response of the four alloys in the corrosive solution was carried out. Although the mechanisms by which the four alloys corroded were similar, the results indicated differences in corrosion resistances of these alloys, and these differences could be related to their microstructures. The laboratory prepared alloy showed increased susceptibility to pitting corrosion compared to the commercial alloys. The surfaces of the alloys were examined, before and after the corrosion test, by scanning electron microscopy and analyzed by energy dispersive spectroscopy. The results indicated preferential attack of the aluminium matrix phase in all the alloys. The alloy with higher copper content and prepared by spray forming was more susceptible to pitting compared to the other alloys. The EIS response at low frequencies indicated a diffusion-controlled process, probably that of oxygen to the alloy interface.

  16. Performance Evaluation of Dual-axis Tracking System of Parabolic Trough Solar Collector

    Science.gov (United States)

    Ullah, Fahim; Min, Kang

    2018-01-01

    A parabolic trough solar collector with the concentration ratio of 24 was developed in the College of Engineering; Nanjing Agricultural University, China with the using of the TracePro software an optical model built. Effects of single-axis and dual-axis tracking modes, azimuth and elevating angle tracking errors on the optical performance were investigated and the thermal performance of the solar collector was experimentally measured. The results showed that the optical efficiency of the dual-axis tracking was 0.813% and its year average value was 14.3% and 40.9% higher than that of the eat-west tracking mode and north-south tracking mode respectively. Further, form the results of the experiment, it was concluded that the optical efficiency was affected significantly by the elevation angle tracking errors which should be kept below 0.6o. High optical efficiency could be attained by using dual-tracking mode even though the tracking precision of one axis was degraded. The real-time instantaneous thermal efficiency of the collector reached to 0.775%. In addition, the linearity of the normalized efficiency was favorable. The curve of the calculated thermal efficiency agreed well with the normalized instantaneous efficiency curve derived from the experimental data and the maximum difference between them was 10.3%. This type of solar collector should be applied in middle-scale thermal collection systems.

  17. Effects of Dual-Channel Functional Electrical Stimulation on Gait Performance in Patients with Hemiparesis

    Directory of Open Access Journals (Sweden)

    Shmuel Springer

    2012-01-01

    Full Text Available The study objective was to assess the effect of functional electrical stimulation (FES applied to the peroneal nerve and thigh muscles on gait performance in subjects with hemiparesis. Participants were 45 subjects (age 57.8 ± 14.8 years with hemiparesis (5.37 ± 5.43 years since diagnosis demonstrating a foot-drop and impaired knee control. Thigh stimulation was applied either to the quadriceps or hamstrings muscles, depending on the dysfunction most affecting gait. Gait was assessed during a two-minute walk test with/without stimulation and with peroneal stimulation alone. A second assessment was conducted after six weeks of daily use. The addition of thigh muscles stimulation to peroneal stimulation significantly enhanced gait velocity measures at the initial and second evaluation. Gait symmetry was enhanced by the dual-channel stimulation only at the initial evaluation, and single-limb stance percentage only at the second assessment. For example, after six weeks, the two-minute gait speed with peroneal stimulation and with the dual channel was 0.66 ± 0.30 m/sec and 0.70 ± 0.31 m/sec, respectively (. In conclusion, dual-channel FES may enhance gait performance in subjects with hemiparesis more than peroneal FES alone.

  18. Dual-band frequency selective surface with large band separation and stable performance

    International Nuclear Information System (INIS)

    Zhou Hang; Qu Shao-Bo; Lin Bao-Qin; Wang Jia-Fu; Ma Hua; Zhang Jie-Qiu; Peng Wei-Dong; Bai Peng; Wang Xu-Hua; Xu Zhuo

    2012-01-01

    A new technique of designing a dual-band frequency selective surface with large band separation is presented. This technique is based on a delicately designed topology of L- and Ku-band microwave filters. The two band-pass responses are generated by a capacitively-loaded square-loop frequency selective surface and an aperture-coupled frequency selective surface, respectively. A Faraday cage is located between the two frequency selective surface structures to eliminate undesired couplings. Based on this technique, a dual-band frequency selective surface with large band separation is designed, which possesses large band separation, high selectivity, and stable performance under various incident angles and different polarizations. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  19. A high-performance dual-scale porous electrode for vanadium redox flow batteries

    Science.gov (United States)

    Zhou, X. L.; Zeng, Y. K.; Zhu, X. B.; Wei, L.; Zhao, T. S.

    2016-09-01

    In this work, we present a simple and cost-effective method to form a dual-scale porous electrode by KOH activation of the fibers of carbon papers. The large pores (∼10 μm), formed between carbon fibers, serve as the macroscopic pathways for high electrolyte flow rates, while the small pores (∼5 nm), formed on carbon fiber surfaces, act as active sites for rapid electrochemical reactions. It is shown that the Brunauer-Emmett-Teller specific surface area of the carbon paper is increased by a factor of 16 while maintaining the same hydraulic permeability as that of the original carbon paper electrode. We then apply the dual-scale electrode to a vanadium redox flow battery (VRFB) and demonstrate an energy efficiency ranging from 82% to 88% at current densities of 200-400 mA cm-2, which is record breaking as the highest performance of VRFB in the open literature.

  20. Steam based conversion coating on AA6060 alloy: Effect of sodium silicate chemistry and corrosion performance

    DEFF Research Database (Denmark)

    Din, Rameez Ud; Bordo, Kirill; Tabrizian, Naja

    2017-01-01

    . Moreover, the use of sodium silicate resulted in the formation of distinct microstructure and incorporation of silicate into the oxide film. These oxide films reduced the anodic activity 4 times, while the corrosion protection by silicate containing oxide was the function of its concentration. Further......Surface treatment of aluminium alloy AA6060 using an industrially applicable pilot steam jet system with and without silicate chemistry has been investigated. Treatment using steam alone and steam with silicate, resulted in an oxide layer formation with thickness ∼425 nm and ∼160 nm, respectively......, in acid salt spray and filiform corrosion tests, oxide layer containing silicate exhibited two times higher corrosion resistance....

  1. Single-task and dual-task tandem gait test performance after concussion.

    Science.gov (United States)

    Howell, David R; Osternig, Louis R; Chou, Li-Shan

    2017-07-01

    To compare single-task and dual-task tandem gait test performance between athletes after concussion with controls on observer-timed, spatio-temporal, and center-of-mass (COM) balance control measurements. Ten participants (19.0±5.5years) were prospectively identified and completed a tandem gait test protocol within 72h of concussion and again 1 week, 2 weeks, 1 month, and 2 months post-injury. Seven uninjured controls (20.0±4.5years) completed the same protocol in similar time increments. Tandem gait test trials were performed with (dual-task) and without (single-task) concurrently performing a cognitive test as whole-body motion analysis was performed. Outcome variables included test completion time, average tandem gait velocity, cadence, and whole-body COM frontal plane displacement. Concussion participants took significantly longer to complete the dual-task tandem gait test than controls throughout the first 2 weeks post-injury (mean time=16.4 [95% CI: 13.4-19.4] vs. 10.1 [95% CI: 6.4-13.7] seconds; p=0.03). Single-task tandem gait times were significantly lower 72h post-injury (p=0.04). Dual-task cadence was significantly lower for concussion participants than controls (89.5 [95% CI: 68.6-110.4] vs. 127.0 [95% CI: 97.4-156.6] steps/minute; p=0.04). Moderately-high to high correlations between tandem gait test time and whole-body COM medial-lateral displacement were detected at each time point during dual-task gait (r s =0.70-0.93; p=0.03-0.001). Adding a cognitive task during the tandem gait test resulted in longer detectable deficits post-concussion compared to the traditional single-task tandem gait test. As a clinical tool to assess dynamic motor function, tandem gait may assist with return to sport decisions after concussion. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  2. Factors affecting the silver corrosion performance of jet fuel from the Merox process

    Energy Technology Data Exchange (ETDEWEB)

    Viljoen, C.L. [Sasol Oil R& D (South Africa); Hietkamp, S. [CSIR, Pretoria (South Africa); Marais, B.; Venter, J.J. [National Petroleum Refineries of South Africa, Sasolburg (South Africa)

    1995-05-01

    The Natref refinery at Sasolburg, South Africa, which is 63,6% owned by Sasol and 36,5% by Total, is producing Jet A-1 fuel at a rate of 80 m{sup 3}/h by means of a UOP Merox process. A substantial part of the crude oil slate is made up from crudes which have been stored for considerable times in underground mines. Since the 1970`s, Natref has experienced sporadic non-conformance of its treated jet fuel to the silver corrosion (IP 227) test. Various causes and explanations for the sporadic silver corrosion occurrence have been put forward but a direct causal link has remained obscure. The paper addresses these possible causes for silver corrosion and some of the process changes which have been made to alleviate the problem. Emphasis is placed on the most recent approaches which were taken to identify the origin of the sporadic silver corrosion. An inventory of all the potential causes was made, such a bacterial action, elemental sulphur formation in storage, etc. and experiments designed to test the validity of these causes, are discussed. A statistical evaluation which was done of the historical process data over a 2 year period, failed to link the use of mine crudes directly to Ag-corrosion occurrence. However, a correlation between elemental sulphur and H{sub 2}S levels in the feed to the Merox reactor and Ag-corrosion was observed. Finally, the outcome of the experiments are discussed, as well as the conclusions which were reached from the observed results.

  3. Performance analysis of dual-hop relaying systems in the presence of Co-channel interference

    KAUST Repository

    Ikki, Salama Said

    2010-12-01

    In this paper, we investigate the effect of co-channel interference on the performance of dual-hop communications with amplify-and-forward relaying. Based on the derivation of the effective signal-to-interference-plus-noise ratio (SINR) at the destination node of the system, taking into account co-channel interference, we obtain expressions for the error and outage probabilities. Moreover, we study the performance of the system in the high SINR regime. Monte-Carlo simulations are further provided and confirm the accuracy of the analytical results. ©2010 IEEE.

  4. Performance of a dual readout calorimeter with a BGO electromagnetic section

    International Nuclear Information System (INIS)

    Gaudio, Gabriella

    2011-01-01

    The dual readout technique has been tested on a hybrid calorimeter. The electromagnetic section of this instrument consists of 100 BGO crystals and the hadronic section is made out scintillating and Cherenkov fibers embedded in a copper matrix (DREAM). The electromagnetic fraction of hadronic showers is evaluated on an event-by-event basis from the relative amounts of Cherenkov and scintillation lights produced in the shower development. The performance of such a calorimeter in terms of energy resolution is presented. Effects of side leakage on detector performance are also studied.

  5. The effects of voice and manual control mode on dual task performance

    Science.gov (United States)

    Wickens, C. D.; Zenyuh, J.; Culp, V.; Marshak, W.

    1986-01-01

    Two fundamental principles of human performance, compatibility and resource competition, are combined with two structural dichotomies in the human information processing system, manual versus voice output, and left versus right cerebral hemisphere, in order to predict the optimum combination of voice and manual control with either hand, for time-sharing performance of a dicrete and continuous task. Eight right handed male subjected performed a discrete first-order tracking task, time-shared with an auditorily presented Sternberg Memory Search Task. Each task could be controlled by voice, or by the left or right hand, in all possible combinations except for a dual voice mode. When performance was analyzed in terms of a dual-task decrement from single task control conditions, the following variables influenced time-sharing efficiency in diminishing order of magnitude, (1) the modality of control, (discrete manual control of tracking was superior to discrete voice control of tracking and the converse was true with the memory search task), (2) response competition, (performance was degraded when both tasks were responded manually), (3) hemispheric competition, (performance degraded whenever two tasks were controlled by the left hemisphere) (i.e., voice or right handed control). The results confirm the value of predictive models invoice control implementation.

  6. Effects of the Addition of a Dual Task to a Supervised Physical Exercise Program on Older Adults' Cognitive Performance.

    Science.gov (United States)

    Ansai, Juliana Hotta; de Andrade, Larissa Pires; de Souza Buto, Marcele Stephanie; de Vassimon Barroso, Verena; Farche, Ana Claudia Silva; Rossi, Paulo Giusti; de Medeiros Takahashi, Anielle Cristhine

    2017-04-01

    The purpose of this study was to investigate the effects of the addition of a dual task to multicomponent training on cognition of active older adults. Eighty physically active older adults were divided into an intervention group (IG) and a control group (CG). Both groups performed multicomponent training over 12 weeks. The IG simultaneously performed exercises and cognitive tasks. The Mini-Mental State Examination, the Montreal Cognitive Assessment, and the Clock Drawing Test were used for cognitive assessments. The Timed Up and Go Test associated with a cognitive task was used for dual-task assessment. Significant interactions were not observed between groups in terms of the cognitive variables or the dual-task performance. An interaction was observed only for Timed Up and Go Test performance, which was better in the CG than in the IG. Active older adults showed no improvement in cognition following the addition of the dual task to the multicomponent training.

  7. DOE-DARPA High-Performance Corrosion-Resistant Materials (HPCRM), Annual HPCRM Team Meeting & Technical Review

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, J; Brown, B; Bayles, B; Lemieux, T; Choi, J; Ajdelsztajn, L; Dannenberg, J; Lavernia, E; Schoenung, J; Branagan, D; Blue, C; Peter, B; Beardsley, B; Graeve, O; Aprigliano, L; Yang, N; Perepezko, J; Hildal, K; Kaufman, L; Lewandowski, J; Perepezko, J; Hildal, K; Kaufman, L; Lewandowski, J; Boudreau, J

    2007-09-21

    The overall goal is to develop high-performance corrosion-resistant iron-based amorphous-metal coatings for prolonged trouble-free use in very aggressive environments: seawater & hot geothermal brines. The specific technical objectives are: (1) Synthesize Fe-based amorphous-metal coating with corrosion resistance comparable/superior to Ni-based Alloy C-22; (2) Establish processing parameter windows for applying and controlling coating attributes (porosity, density, bonding); (3) Assess possible cost savings through substitution of Fe-based material for more expensive Ni-based Alloy C-22; (4) Demonstrate practical fabrication processes; (5) Produce quality materials and data with complete traceability for nuclear applications; and (6) Develop, validate and calibrate computational models to enable life prediction and process design.

  8. Anti-Corrosion Performance of 1,3-BENZOTHIAZOLE on 410 Martensitic Stainless Steel in H2SO4

    Science.gov (United States)

    Loto, Roland Tolulope

    The corrosion inhibition effect of synthesized 1,3-benzothiazole at very low concentrations on 410 martensitic stainless steel in 3MH2SO4 solution was studied through potentiodynamic polarization and weight loss measurements. The observation showed that the organic compound performed effectively with average inhibition efficiencies of 94% and 98% at the concentrations studied from both electrochemical methods due to the inhibition action of protonated inhibitor molecules in the acid solution. The amine and aromatics functional groups of the molecules active in the corrosion inhibition reaction were exposed from Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) spectroscopic analysis. Thermodynamic calculations showed cationic adsorption to be chemisorption adsorption, obeying the Langmuir adsorption isotherm. Images from optical microscopy showed an improved morphology in comparison to images from corroded stainless steel. Severe surface deterioration and macro-pits were observed in the uninhibited samples.

  9. Properties and performance of spin-on-glass coatings for the corrosion protection of stainless steels in chloride media

    DEFF Research Database (Denmark)

    Lampert, Felix; Jensen, Annemette H.; Din, Rameez U.

    2018-01-01

    Spin-on-glass deposition was investigated as viable alternative to increase the durability and performance of 316L steel in chloride environment. The buildup of a detrimental interface oxide was prevented by non-oxidative thermal curing of the coatings, which leads to a transformation...... silica. Electrochemical analysis by cyclic polarization indicated that the coatings behave as imperfect barrier coatings, which may enhance the passive properties of the substrates; however, there is still some statistical scatter in the quality of the coatings. While there is a tendency for an increase...... of the upper limit of the breakdown potential, there is also a decrease of the lower limit. It was found that such lower quality coatings showed, in association with substrate defects, unevenly distributed coating flaws, which may act as initiation points of pitting corrosion and decrease the corrosion...

  10. Do Dual-Route Models Accurately Predict Reading and Spelling Performance in Individuals with Acquired Alexia and Agraphia?

    OpenAIRE

    Rapcsak, Steven Z.; Henry, Maya L.; Teague, Sommer L.; Carnahan, Susan D.; Beeson, Pélagie M.

    2007-01-01

    Coltheart and colleagues (Coltheart, Rastle, Perry, Langdon, & Ziegler, 2001; Castles, Bates, & Coltheart, 2006) have demonstrated that an equation derived from dual-route theory accurately predicts reading performance in young normal readers and in children with reading impairment due to developmental dyslexia or stroke. In this paper we present evidence that the dual-route equation and a related multiple regression model also accurately predict both reading and spelling performance in adult...

  11. Semantic interference in picture naming during dual-task performance does not vary with reading ability.

    Science.gov (United States)

    Piai, Vitória; Roelofs, Ardi; Roete, Ingeborg

    2015-01-01

    Previous dual-task studies examining the locus of semantic interference of distractor words in picture naming have obtained diverging results. In these studies, participants manually responded to tones and named pictures while ignoring distractor words (picture-word interference, PWI) with varying stimulus onset asynchrony (SOA) between tone and PWI stimulus. Whereas some studies observed no semantic interference at short SOAs, other studies observed effects of similar magnitude at short and long SOAs. The absence of semantic interference in some studies may perhaps be due to better reading skill of participants in these than in the other studies. According to such a reading-ability account, participants' reading skill should be predictive of the magnitude of their interference effect at short SOAs. To test this account, we conducted a dual-task study with tone discrimination and PWI tasks and measured participants' reading ability. The semantic interference effect was of similar magnitude at both short and long SOAs. Participants' reading ability was predictive of their naming speed but not of their semantic interference effect, contrary to the reading ability account. We conclude that the magnitude of semantic interference in picture naming during dual-task performance does not depend on reading skill.

  12. Performance evaluation of a 'dual-side read' dedicated mammography computed radiography system

    International Nuclear Information System (INIS)

    Fetterly, Kenneth A.; Schueler, Beth A.

    2003-01-01

    The image quality of a dedicated mammography computed radiography (CR) system was characterized. A unique feature of this system is that it collects image signals from both sides of the storage phosphor. Measurements of the modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE) were made. This work included improvements in our measurement methods to specifically account for the detrimental effects of system glare on the MTF and to accurately characterize the low-frequency NPS components. Image quality measurements were performed using a 25 kVp beam filtered with 2 mm Al and an exposure range of 1 to 100 mR (87 to 870 μGy). The DQE was found to decrease with increasing exposure due to an increased contribution of storage phosphor structure noise. The DQE of this system was compared to similar measurements made using a standard CR system. The dual-side read system demonstrated superior DQE compared to the standard system. The decrease in DQE with increasing exposure was more severe for the standard system than the dual-side read system. This finding suggests that the CR system noise was reduced for the dual-side read system compared to the standard system

  13. IMPROVEMENT OF PERFORMANCE OF DUAL FUEL ENGINE OPERATED AT PART LOAD

    Directory of Open Access Journals (Sweden)

    N. Kapilan

    2010-12-01

    Full Text Available Rising petroleum prices, an increasing threat to the environment from exhaust emissions, global warming and the threat of supply instabilities has led to the choice of inedible Mahua oil (MO as one of the main alternative fuels to diesel oil in India. In the present work, MO was converted into biodiesel by transesterification using methanol and sodium hydroxide. The cost of Mahua oil biodiesel (MOB is higher than diesel. Hence liquefied petroleum gas (LPG, which is one of the cheapest gaseous fuels available in India, was fumigated along with the air to reduce the operating cost and to reduce emissions. The dual fuel engine resulted in lower efficiency and higher emissions at part load. Hence in the present work, the injection time was varied and the performance of the dual fuel engine was studied. From the engine tests, it is observed that an advanced injection time results in higher efficiency and lower emissions. Hence, advancing the injection timing is one of the ways of increasing the efficiency of LPG+MOB dual fuel engine operated at part load.

  14. Characterization of dual layer phoswich detector performance for small animal PET using Monte Carlo simulation

    International Nuclear Information System (INIS)

    Chung, Yong Hyun; Choi, Yong; Cho, Gyuseong; Choe, Yearn Seong; Lee, Kyung-Han; Kim, Byung-Tae

    2004-01-01

    A positron emission tomograph dedicated to small animal imaging should have high spatial resolution and sensitivity, and dual layer scintillators have been developed for this purpose. In this study, simulations were performed to optimize the order and the length of each crystal of a dual layer phoswich detector, and to evaluate the possibility of measuring signals from each layer of the phoswich detector. A simulation tool GATE was used to estimate the sensitivity and resolution of a small PET scanner. The proposed scanner is based on dual layer phoswich detector modules arranged in a ring of 10 cm diameter. Each module is composed of 8 x 8 arrays of phoswich detectors consisting of LSO and LuYAP with a 2 mm x 2 mm sensitive area coupled to a Hamamatsu R7600-00-M64 PSPMT. The length of the front layer of the phoswich detector varied from 0 to 10 mm at 1 mm intervals, and the total length (LSO + LuYAP) was fixed at 20 mm. The order of the crystal layers of the phoswich detector was also changed. Radial resolutions were kept below 3.4 mm and 3.7 mm over 8 cm FOV, and sensitivities were 7.4% and 8.0% for LSO 5 mm-LuYAP 15 mm, and LuYAP 6 mm-LSO 14 mm phoswich detectors, respectively. Whereas, high and uniform resolutions were achieved by using the LSO front layer, higher sensitivities were obtained by changing the crystal order. The feasibilities for applying crystal identification methods to phoswich detectors consisting of LSO and LuYAP were investigated using simulation and experimentally derived measurements of the light outputs from each layer of the phoswich detector. In this study, the optimal order and lengths of the dual layer phoswich detector were derived in order to achieve high sensitivity and high and uniform radial resolution

  15. Toward an understanding of the neural mechanisms underlying dual-task performance: Contribution of comparative approaches using animal models.

    Science.gov (United States)

    Watanabe, Kei; Funahashi, Shintaro

    2018-01-01

    The study of dual-task performance in human subjects has received considerable interest in cognitive neuroscience because it can provide detailed insights into the neural mechanisms underlying higher-order cognitive control. Despite many decades of research, our understanding of the neurobiological basis of dual-task performance is still limited, and some critical questions are still under debate. Recently, behavioral and neurophysiological studies of dual-task performance in animals have begun to provide intriguing evidence regarding how dual-task information is processed in the brain. In this review, we first summarize key evidence in neuroimaging and neuropsychological studies in humans and discuss possible reasons for discrepancies across studies. We then provide a comprehensive review of the literature on dual-task studies in animals and provide a novel working hypothesis that may reconcile the divergent results in human studies toward a unified view of the mechanisms underlying dual-task processing. Finally, we propose possible directions for future dual-task experiments in the framework of comparative cognitive neuroscience. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  16. Age-related decrements in dual-task performance: Comparison of different mobility and cognitive tasks. A cross sectional study.

    Science.gov (United States)

    Brustio, Paolo Riccardo; Magistro, Daniele; Zecca, Massimiliano; Rabaglietti, Emanuela; Liubicich, Monica Emma

    2017-01-01

    This cross-sectional study investigated the age-related differences in dual-task performance both in mobility and cognitive tasks and the additive dual-task costs in a sample of older, middle-aged and young adults. 74 older adults (M = 72.63±5.57 years), 58 middle-aged adults (M = 46.69±4.68 years) and 63 young adults (M = 25.34±3.00 years) participated in the study. Participants performed different mobility and subtraction tasks under both single- and dual-task conditions. Linear regressions, repeated-measures and one-way analyses of covariance were used, The results showed: significant effects of the age on the dual and mobility tasks (ptask costs (pperformance under dual-task conditions in all groups (pperformance in the older group (ptask activity affected mobility and cognitive performance, especially in older adults who showed a higher dual-task cost, suggesting that dual-tasks activities are affected by the age and consequently also mobility and cognitive tasks are negatively influenced.

  17. Motor-cognitive dual-task performance: effects of a concurrent motor task on distinct components of visual processing capacity.

    Science.gov (United States)

    Künstler, E C S; Finke, K; Günther, A; Klingner, C; Witte, O; Bublak, P

    2018-01-01

    Dual tasking, or the simultaneous execution of two continuous tasks, is frequently associated with a performance decline that can be explained within a capacity sharing framework. In this study, we assessed the effects of a concurrent motor task on the efficiency of visual information uptake based on the 'theory of visual attention' (TVA). TVA provides parameter estimates reflecting distinct components of visual processing capacity: perceptual threshold, visual processing speed, and visual short-term memory (VSTM) storage capacity. Moreover, goodness-of-fit values and bootstrapping estimates were derived to test whether the TVA-model is validly applicable also under dual task conditions, and whether the robustness of parameter estimates is comparable in single- and dual-task conditions. 24 subjects of middle to higher age performed a continuous tapping task, and a visual processing task (whole report of briefly presented letter arrays) under both single- and dual-task conditions. Results suggest a decline of both visual processing capacity and VSTM storage capacity under dual-task conditions, while the perceptual threshold remained unaffected by a concurrent motor task. In addition, goodness-of-fit values and bootstrapping estimates support the notion that participants processed the visual task in a qualitatively comparable, although quantitatively less efficient way under dual-task conditions. The results support a capacity sharing account of motor-cognitive dual tasking and suggest that even performing a relatively simple motor task relies on central attentional capacity that is necessary for efficient visual information uptake.

  18. Evaluation of the performance of combined cooling, heating, and power systems with dual power generation units

    International Nuclear Information System (INIS)

    Knizley, Alta A.; Mago, Pedro J.; Smith, Amanda D.

    2014-01-01

    The benefits of using a combined cooling, heating, and power system with dual power generation units (D-CCHP) is examined in nine different U.S. locations. One power generation unit (PGU) is operated at base load while the other is operated following the electric load. The waste heat from both PGUs is used for heating and for cooling via an absorption chiller. The D-CCHP configuration is studied for a restaurant benchmark building, and its performance is quantified in terms of operational cost, primary energy consumption (PEC), and carbon dioxide emissions (CDE). Cost spark spread, PEC spark spread, and CDE spark spread are examined as performance indicators for the D-CCHP system. D-CCHP system performance correlates well with spark spreads, with higher spark spreads signifying greater savings through implementation of a D-CCHP system. A new parameter, thermal difference, is introduced to investigate the relative performance of a D-CCHP system compared to a dual PGU combined heat and power system (D-CHP). Thermal difference, together with spark spread, can explain the variation in savings of a D-CCHP system over a D-CHP system for each location. The effect of carbon credits on operational cost savings with respect to the reference case is shown for selected locations. - Highlights: • We investigate benefits from using combined cooling, heating, and power systems. • A dual power generation unit configuration is considered for CCHP and CHP. • Spark spreads for cost, energy, and emissions correlate with potential savings. • Thermal difference parameter helps to explain variations in potential savings. • Carbon credits may increase cost savings where emissions savings are possible

  19. Effect of sulfur on the SCC and corrosion fatigue performance of stainless steel

    International Nuclear Information System (INIS)

    West, E.; Nolan, T.; Lucente, A.; Morton, D.; Lewis, N.; Morris, R.; Mullen, J.; Newsome, G.

    2015-01-01

    Stress corrosion cracking and corrosion fatigue experiments were conducted on model heats of 304/304L stainless steel with systematically controlled sulfur content to isolate the influence of sulfur on crack growth behavior. The results of the SCC experiments conducted in 338 C. degrees deaerated water on 20% cold worked model heats with 0.006 and 0.012 wt% sulfur showed an order of magnitude or more reduction in the crack growth rate relative to a model heat with <0.001 wt% sulfur. Corrosion fatigue crack growth rates revealed a reduction in the crack growth rates of the elevated sulfur heats relative to model predicted steady state crack growth rates with increasing rise time for nominal loading conditions of a stress ratio of 0.7 and a stress intensity factor range of 6.6 MPa√m. At the longest rise time of 5.330 sec, the corrosion fatigue crack growth rate of the 0.006 wt% sulfur model heat was only 13% of model predictions and the crack growth of the 0.012 wt% sulfur heat completely stalled. Experiments conducted in anion faulted aerated water on stainless steel heats with moderate to high sulfur and variable carbon and boron contents showed that any detrimental effect of sulfur in this environment was secondary to the effect of sensitization in promoting SCC growth. (authors)

  20. Anti-corrosion performance of oxidized and oxygen plasma-implanted NiTi alloys

    International Nuclear Information System (INIS)

    Poon, Ray W.Y.; Ho, Joan P.Y.; Liu, Xuanyong; Chung, C.Y.; Chu, Paul K.; Yeung, Kelvin W.K.; Lu, William W.; Cheung, Kenneth M.C.

    2005-01-01

    Nickel-titanium shape memory alloys are useful orthopedic biomaterials on account of its super-elastic and shape memory properties. However, the problem associated with out-diffusion of harmful nickel ions in prolonged use inside the human body raises a critical safety concern. Titanium oxide films are deemed to be chemically inert and biocompatible and hence suitable to be the barrier layers to impede the leaching of Ni from the NiTi substrate to biological tissues and fluids. In the work reported in this paper, we compare the anti-corrosion efficacy of oxide films produced by atmospheric-pressure oxidation and oxygen plasma ion implantation. Our results show that the oxidized samples do not possess improved corrosion resistance and may even fare worse than the untreated samples. On the other hand, the plasma-implanted surfaces exhibit much improved corrosion resistance. Our work also shows that post-implantation annealing can further promote the anti-corrosion capability of the samples

  1. Corrosion Performance of Carbon Steel in Simulated Pore Solution in the Presence of Micelles

    NARCIS (Netherlands)

    Hu, J.; Koleva, D.A.; De Wit, J.H.W.; Kolev, H.; Van Breugel, K.

    2011-01-01

    This study presents the results on the investigation of the corrosion behavior of carbon steel in model alkaline medium in the presence of very low concentration of polymeric nanoaggregates [0.0024 wt % polyethylene oxide (PEO)113-b-PS70 micelles]. The steel electrodes were investigated in chloride

  2. A new corrosion resistant, martensitic stainless steel for improved performance in miniature bearings

    Energy Technology Data Exchange (ETDEWEB)

    Tomasello, C.M.; Maloney, J.L.; Materkowski, J.P. [Latrobe Steel Co., Latrobe, PA (United States); Ward, P.C. [MPB Corp., Keene, NH (United States)

    1998-12-31

    A new alloy, 440 N-DUR{trademark} has been developed which will provide the corrosion resistance of 440C with improved carbide size and distribution for noiseless miniature precision bearing operation. The alloy may be through hardened to achieve a minimum hardness of 60 HRC. Its nominal composition is 0.65 wt.% C, 14.5 wt.% Cr, 0.30 wt.% Si, 0.45 wt.% Mn and 0.10 wt.% N{sub 2}. The development of the alloy is a result of a factorial experimental design including 17 alloy variants. The optimum alloy provides a combination of the best carbide structure, corrosion resistance and heat treat response. The addition of nitrogen combined with this carbon and chromium content improves the alloy`s hardenability and corrosion resistance. The alloy successfully withstands copper sulfate exposure and is currently being tested in several bearing applications. It also has great potential to outperform 440C and other corrosion resistant alloys for other ambient and low temperature applications because of its improved microstructure and heat treat response.

  3. Tempering effect on corrosion performance of magnesium alloys for biomedical applications

    NARCIS (Netherlands)

    Zhang, X.; Ferrari, G.M.; Erinc, M.; Sillekens, W.H.

    2010-01-01

    The corrosion resistances for magnesium alloys AZ80, AE82 and ZM21 treated at 200 and 330°C for 2 hours, and for AZ80 and AE82 at 415°C for 8 hours were investigated using potentiodynamic polarization measurements in simulated body fluid (SBF) solution at 37°C. The morphology and the Volta potential

  4. Properties of corrosion resistance in C + Mo multi implanted steel

    International Nuclear Information System (INIS)

    Zhang Tonghe; Wu Yuguang; Wang Xiaoyan

    2001-01-01

    The influence of multi-implantation on the corrosion resistance of H13 steel was studied using multi-sweep cyclic voltammetry. The formation conditions of phases and its effects on corrosion resistance were studied. The mechanism of improvement in corrosion resistance was discussed. The experimental results show that the increase of Mo dose can improve corrosion resistance, however the increase of C dose can enhance pitting corrosion potential. Both effects were obtained using dual-and multi-implantation. The passivation layer consists of the phases of Fe 2 Mo, FeMo, MoC, Fe 5 C 3 and Fe 7 C 3 in dual implantation surface of steel. It can improve corrosion resistance and increase pitting corrosion potential. Multi-implantation can further improve corrosion and pitting corrosion resistance compared with dual implantation

  5. Evaluation of the mechanical and corrosion protection performance of electrodeposited hydroxyapatite on the high energy electron beam treated titanium alloy

    International Nuclear Information System (INIS)

    Gopi, D.; Sherif, El-Sayed M.; Rajeswari, D.; Kavitha, L.; Pramod, R.; Dwivedi, Jishnu; Polaki, S.R.

    2014-01-01

    Graphical abstract: - Highlights: • Ti–6Al–4V alloy was surface treated by high energy low current DC electron beam. • Successful electrodeposition of HAP was achieved on surface treated Ti–6Al–4V. • The as-formed coating possessed improved surface wettability and adhesion strength. • Maximum corrosion protection performance was exhibited by the as-formed coating. - Abstract: In our present study, the Ti–6Al–4V alloy surface was modified by irradiating with the high energy low current DC electron beam (HELCDEB) using 700 keV DC accelerator. Following this, the HELCDEB treated surface was coated with hydroxyapatite by adopting electrodeposition method. The microstructure and hardness of HELCDEB treated Ti–6A1–4V alloy with and without electrodeposited hydroxyapatite were investigated. Also, the electrochemical corrosion characteristics of the samples in simulated body fluid (SBF) was studied by potentiodynamic polarisation and electrochemical impedence techniques (EIS) which showed an enhanced corrosion resistance and revealed an improved life time for the hydroxyapatite coating developed on the HELCDEB treated Ti–6A1–4V alloy than the untreated sample

  6. Performance evaluation of a dual-flow recharge filter for improving groundwater quality.

    Science.gov (United States)

    Samuel, Manoj P; Senthilvel, S; Mathew, Abraham C

    2014-07-01

    A dual-flow multimedia stormwater filter integrated with a groundwater recharge system was developed and tested for hydraulic efficiency and pollutant removal efficiency. The influent stormwater first flows horizontally through the circular layers of planted grass and biofibers. Subsequently, the flow direction changes to a vertical direction so that water moves through layers of pebbles and sand and finally gets recharged to the deep aquifers. The media in the sequence of vegetative medium:biofiber to pebble:sand were filled in nine proportions and tested for the best performing combination. Three grass species, viz., Typha (Typha angustifolia), Vetiver (Chrysopogon zizanioides), and St. Augustine grass (Stenotaphrum secundatum), were tested as the best performing vegetative medium. The adsorption behavior of Coconut (Cocos nucifera) fiber, which was filled in the middle layer, was determined by a series of column and batch studies.The dual-flow filter showed an increasing trend in hydraulic efficiency with an increase in flowrate. The chemical removal efficiency of the recharge dual-flow filter was found to be very high in case of K+ (81.6%) and Na+ (77.55%). The pH normalizing efficiency and electrical conductivity reduction efficiency were also recorded as high. The average removal percentage of Ca2+ was moderate, while that of Mg2+ was very low. The filter proportions of 1:1 to 1:2 (plant:fiber to pebble:sand) showed a superior performance compared to all other proportions. Based on the estimated annual costs and returns, all the financial viability criteria (internal rate of return, net present value, and benefit-cost ratio) were found to be favorable and affordable to farmers in terms of investing in the developed filtration system.

  7. Effects of Backpack Carriage on Dual-Task Performance in Children During Standing and Walking.

    Science.gov (United States)

    Beurskens, Rainer; Muehlbauer, Thomas; Grabow, Lena; Kliegl, Reinhold; Granacher, Urs

    2016-01-01

    Primary school children perform parts of their everyday activities while carrying school supplies and being involved in attention-demanding situations. Twenty-eight children (8-10 years old) performed a 1-legged stance and a 10 m walking test under single- and dual-task situations in unloaded (i.e., no backpack) and loaded conditions (i.e., backpack with 20% of body mass). Results showed that load carriage did not significantly influence children's standing and walking performance (all p > .05), while divided attention affected all proxies of walking (all p attention interactions was detected. The single application of attentional but not load demand negatively affects children's walking performance. A combined application of both did not further deteriorate their gait behavior.

  8. Associations between physical function, dual-task performance and cognition in patients with mild Alzheimer's disease

    DEFF Research Database (Denmark)

    Sobol, Nanna Aue; Hoffmann, Kristine; Vogel, Asmus Mejling

    2016-01-01

    blinded multicenter RCT 'ADEX' (Alzheimer's disease: the effect of physical exercise) were used. Assessments included tests of physical function: 400-m walk test, 10-m walk test, Timed Up and Go test and 30-s chair stand test; dual-task performance, i.e., 10-m walk while counting backwards from 50...... or naming the months backwards; and cognition, i.e., Mini Mental State Examination, Symbol Digit Modalities Test, the Stroop Color and Word Test, and Lexical verbal fluency test. RESULTS: Results in the 30-s chair stand test correlated significantly with all tests of cognition (r = .208-.242) while...

  9. Researching the Performance of Dual-Chamber Fire-Tube Boiler Furnace

    Directory of Open Access Journals (Sweden)

    Khaustov Sergei

    2015-01-01

    Full Text Available Autonomous heating systems equipped with fire-tube or shell boilers show high effectiveness, consistent performance and great technical parameters. But there is a significant limitation of its thermal productivity due to the complexity of durable large diameter fire-tube bottoms implementation. Optimization of combustion aerodynamics can be the way to expand the fire-tube boilers performance limit. In this case lots of problems connected with reducing emissions of toxic substances, providing of burning stability, local heat stresses and aerodynamic resistances should be solved. To resolve the indicated problems, a modified model of dual-chamber fire-tube boiler furnace is proposed. The performance of suggested flame-tube was simulated using the proven computer-aided engineering software ANSYS Multiphysics. Results display proposed flame tube completely filled with moving medium without stagnant zones. Turbulent vortical combustion is observed even with the straight-through fuel supply. Active flue gas recirculation in suggested dual-chamber furnace reduces emissions of pollutants. Diminution of wall heat fluxes allows boiler operation at lower water treatment costs.

  10. Neurofeedback training improves the dual-task performance ability in stroke patients.

    Science.gov (United States)

    Lee, Young-Shin; Bae, Sea-Hyun; Lee, Sung-Hee; Kim, Kyung-Yoon

    2015-05-01

    Owing to the reduced capacity for information processing following a stroke, patients commonly present with difficulties in performing activities of daily living that combine two or more tasks. To address this problem, in the present study, we investigated the effects of neurofeedback training on the abilities of stroke patients to perform dual motor tasks. We randomly assigned 20 patients who had sustained a stroke within the preceding 6 months to either a pseudo-neurofeedback (n = 10) or neurofeedback (n = 10) group. Both groups participated in a general exercise intervention for 8 weeks, three times a week for 30 min per session, under the same conditions. An electrode was secured to the scalp over the region of the central lobe (Cz), in compliance with the International 10-20 System. The electrode was inactive for the pseudo-training group. Participants in the neurofeedback training group received the 30-min neurofeedback training per session for reinforcing the sensorimotor rhythm. Electroencephalographic activity of the two groups was compared. In addition, selected parameters of gait (velocity, cadence [step/min], stance phase [%], and foot pressure) were analyzed using a 10-m walk test, attention-demanding task, walk task and quantified by the SmartStep system. The neurofeedback group showed significantly improved the regulation of the sensorimotor rhythm (p neurofeedback training is effective to improve the dual-task performance in stroke patients.

  11. Effect of sewage sludge ash (SSA on the mechanical performance and corrosion levels of reinforced Portland cement mortars

    Directory of Open Access Journals (Sweden)

    Andión, L. G.ª

    2006-06-01

    Full Text Available The article describes a study conducted to determinecorrosion in reinforcement embedded in Portland cement(PC mortars with different percentages of sewage sludgeash (SSA admixtures. The polarization resistancetechnique was used to determine the steel corrosion rate(Icorr in the test specimens. The samples were subjectedto different environmental conditions and aggressiveagents: 100% relative humidity (RH, accelerated carbonationat 70% RH and seawater immersion. Portlandcement was partially substituted for SSA in the mixes atrates of 0, 10, 20, 30 and 60% (by mass to make thedifferent mortars. The results show that where cementwas replaced by SSA at rates of up to 10% by mass,mortar corrosion performance was comparable to thebehaviour observed in SSA-free mortars (control mortar:0% SSA. Data for higher rates are also shown. From themechanical standpoint, SSA exhibited moderate pozzolanicactivity and the best performance when SSA wasadded at a rate of 10% to mixes with a water/(binder:PC + SSA (w/b ratio of 0.5.Se ha estudiado el nivel de corrosion que presentan lasarmaduras embebidas en morteros fabricados con cementoPortland (CP con diferentes porcentajes de sustitucion deceniza de lodo de depuradora (CLD. Se ha utilizado la tecnicade la Resistencia a la Polarizacion para determinar lavelocidad de corrosion del acero embebido en las muestrasestudiadas. Las muestras se han sometido a diferentes condicionesambientales y agentes agresivos: 100% de humedadrelativa (HR, carbonatacion acelerada al 70% HR einmersion en agua de mar. Para la fabricacion de los distintosmorteros, el cemento Portland ha sido parcialmente sustituidopor CLD en los siguientes porcentajes en masa: 0,10, 20, 30 y 60%. Los resultados muestran que sustitucionesde cemento por CLD de hasta el 10% en masa no alteranel comportamiento frente a la corrosion de los morterosal compararlos con los morteros libres de CLD (morteroscontrol: 0% de sustitucion de cemento por CLD. Se

  12. Effect of Tai Chi Training on Dual-Tasking Performance That Involves Stepping Down among Stroke Survivors: A Pilot Study.

    Science.gov (United States)

    Chan, Wing-Nga; Tsang, William Wai-Nam

    2017-01-01

    Descending stairs demands attention and neuromuscular control, especially with dual-tasking. Studies have demonstrated that stroke often degrades a survivor's ability to descend stairs. Tai Chi has been shown to improve dual-tasking performance of healthy older adults, but no such study has been conducted in stroke survivors. This study investigated the effect of Tai Chi training on dual-tasking performance that involved stepping down and compared it with that of conventional exercise among stroke survivors. Subjects were randomized into Tai Chi ( n = 9), conventional exercise ( n = 8), and control ( n = 9) groups. Those in the former two groups received 12-week training. Assessments included auditory Stroop test, stepping down test, and dual-tasking test involving both simultaneously. They were evaluated before training (time-1), after training (time-2), and one month after training (time-3). Tai Chi group showed significant improvement in the auditory Stroop test from time-1 to time-3 and the performance was significantly better than that of the conventional exercise group in time-3. No significant effect was found in the stepping down task or dual-tasking in the control group. These results suggest a beneficial effect of Tai Chi training on cognition among stroke survivors without compromising physical task performance in dual-tasking. The effect was better than the conventional exercise group. Nevertheless, further research with a larger sample is warranted.

  13. Effect of Tai Chi Training on Dual-Tasking Performance That Involves Stepping Down among Stroke Survivors: A Pilot Study

    Directory of Open Access Journals (Sweden)

    Wing-Nga Chan

    2017-01-01

    Full Text Available Descending stairs demands attention and neuromuscular control, especially with dual-tasking. Studies have demonstrated that stroke often degrades a survivor’s ability to descend stairs. Tai Chi has been shown to improve dual-tasking performance of healthy older adults, but no such study has been conducted in stroke survivors. This study investigated the effect of Tai Chi training on dual-tasking performance that involved stepping down and compared it with that of conventional exercise among stroke survivors. Subjects were randomized into Tai Chi (n=9, conventional exercise (n=8, and control (n=9 groups. Those in the former two groups received 12-week training. Assessments included auditory Stroop test, stepping down test, and dual-tasking test involving both simultaneously. They were evaluated before training (time-1, after training (time-2, and one month after training (time-3. Tai Chi group showed significant improvement in the auditory Stroop test from time-1 to time-3 and the performance was significantly better than that of the conventional exercise group in time-3. No significant effect was found in the stepping down task or dual-tasking in the control group. These results suggest a beneficial effect of Tai Chi training on cognition among stroke survivors without compromising physical task performance in dual-tasking. The effect was better than the conventional exercise group. Nevertheless, further research with a larger sample is warranted.

  14. Do dual-route models accurately predict reading and spelling performance in individuals with acquired alexia and agraphia?

    Science.gov (United States)

    Rapcsak, Steven Z; Henry, Maya L; Teague, Sommer L; Carnahan, Susan D; Beeson, Pélagie M

    2007-06-18

    Coltheart and co-workers [Castles, A., Bates, T. C., & Coltheart, M. (2006). John Marshall and the developmental dyslexias. Aphasiology, 20, 871-892; Coltheart, M., Rastle, K., Perry, C., Langdon, R., & Ziegler, J. (2001). DRC: A dual route cascaded model of visual word recognition and reading aloud. Psychological Review, 108, 204-256] have demonstrated that an equation derived from dual-route theory accurately predicts reading performance in young normal readers and in children with reading impairment due to developmental dyslexia or stroke. In this paper, we present evidence that the dual-route equation and a related multiple regression model also accurately predict both reading and spelling performance in adult neurological patients with acquired alexia and agraphia. These findings provide empirical support for dual-route theories of written language processing.

  15. Multiphase Venturi Dual Energy Gamma Ray combination performance in NUEX flow loop; Desempenho no flowloop do NUEX da medicao multifasica Venturi Dual Energy Gamma Ray

    Energy Technology Data Exchange (ETDEWEB)

    Barreiros, Claudio; Taranto, Cleber; Costa, Alcemir [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil); Pinguet, Bruno; Heluey, Vitor; Bessa, Fabiano; Loicq, Olivier [Schlumberger Servicos de Petroleo Ltda., Rio de Janeiro, RJ (Brazil)

    2008-07-01

    The Multiphase Venturi Dual Energy Gamma Ray Combination, Vx* technology, arrived in Brazil in 2000. PETROBRAS, Brazilian Oil Company, has been putting big efforts in its production business and also has demonstrated a large interest in having a multiphase meter approved by ANP for back allocation purposes. The oil industry was looking for ways to improve the back allocation process using an approved on line multiphase flow measurement device, thus replacing punctual test done today by a permanent monitoring device. Considering this scenario, a partnership project between PETROBRAS and Schlumberger was created in Brazil. The main objective of this project, which was held in NUEX flow loop, was to demonstrate to INMETRO (Brazilian Metrology Institute) that the Multiphase Venturi Dual Energy Gamma Ray Combination meter is able to be used for back allocation purpose. PETROBRAS and Schlumberger elaborated a complete methodology in the NUEX flow loop to demonstrate the results and benefits of the Multiphase Venturi Dual Energy Gamma Ray Combination meter. The test was witnessed by INMETRO and had a very good performance at the end. The results were within what was expected by Schlumberger, PETROBRAS and INMETRO. These results has been very useful to PETROBRAS in order to start using the Venturi Dual Energy Gamma Ray technology for well allocation purposes. (author)

  16. Corrosion performance of optimised and advanced fuel rod cladding in PWRs at high burnups

    International Nuclear Information System (INIS)

    Jourdain, P.; Hallstadius, L.; Pati, S.R.; Smith, G.P.; Garde, A.M.

    1997-01-01

    The corrosion behaviour both in-pile and out-of-pile for a number of cladding alloys developed by ABB to meet the current and future needs for fuel rod cladding with improved corrosion resistance is presented. The cladding materials include: 1) Zircaloy-4 (OPTIN) with optimised composition and processing and Zircaloy-2 optimised for Pressurised Water Reactors (PWR), (Zircaloy-2P), and 2) several alternative zirconium-based alloys with compositions outside the composition range for Zircaloys. The data presented originate from fuel rods irradiated in six PWRs to burnups up to about 66 MWd/kgU and from tests conducted in 360 o water autoclave. Also included are in-pile fuel rod growth measurements on some of the alloys. (UK)

  17. Lessons from Monte Carlo simulations of the performance of a dual-readout fiber calorimeter

    CERN Document Server

    Akchurin, N; Cardini, A; Cascella, M; De Pedis, D; Ferrari, R; Fracchia, S; Franchino, S; Fraternali, M; Gaudio, G; Genova, P; Hauptman, J; La Rotonda, L; Lee, S; Livan, M; Meoni, E; Pinci, D; Policicchio, A; Saraiva, J G; Scuri, F; Sill, A; Venturelli, T; Wigmans, R

    2014-01-01

    The RD52 calorimeter uses the dual-readout principle to detect both electromagnetic and hadronic showers, as well as muons. Scintillation and Cherenkov light provide the two signals which, in combination, allow for superior hadronic performance. In this paper, we report on detailed, GEANT4 based Monte Carlo simulations of the performance of this instrument. The results of these simulations are compared in great detail to measurements that have been carried out and published by the DREAM Collaboration. This comparison makes it possible to understand subtle details of the shower development in this unusual particle detector. It also allows for predictions of the improvement in the performance that may be expected for larger detectors of this type. These studies also revealed some inadequacies in the GEANT4 simulation packages, especially for hadronic showers, but also for the Cherenkov signals from electromagnetic showers.

  18. Dual Arm Work Package performance estimates and telerobot task network simulation

    International Nuclear Information System (INIS)

    Draper, J.V.

    1997-01-01

    This paper describes the methodology and results of a network simulation study of the Dual Arm Work Package (DAWP), to be employed for dismantling the Argonne National Laboratory CP-5 reactor. The development of the simulation model was based upon the results of a task analysis for the same system. This study was performed by the Oak Ridge National Laboratory (ORNL), in the Robotics and Process Systems Division. Funding was provided the US Department of Energy's Office of Technology Development, Robotics Technology Development Program (RTDP). The RTDP is developing methods of computer simulation to estimate telerobotic system performance. Data were collected to provide point estimates to be used in a task network simulation model. Three skilled operators performed six repetitions of a pipe cutting task representative of typical teleoperation cutting operations

  19. Evaluation of corrosive behavior of SAE 5155 by corrosion environment

    International Nuclear Information System (INIS)

    An, Jae Pil; Park, Keyung Dong

    2005-01-01

    In this study, the influence of shot peening and corrosive condition for corrosion property was investigated on immersed in 3.5% NaCl, 10% HNO 3 + 3% HF, 6% FeCl 3 . The immersion test was performed on two kinds of specimen. The immersion periods was performed 30days. Corrosion potential, weight loss were investigated from experimental results. From test results, the effect of shot peening on the corrosion was evaluated

  20. A mixed-pH dual-electrolyte microfluidic aluminum–air cell with high performance

    International Nuclear Information System (INIS)

    Chen, Binbin; Leung, Dennis Y.C.; Xuan, Jin; Wang, Huizhi

    2017-01-01

    Highlights: • A mix-pH dual-electrolyte Al–air cell is proposed. • Cells with dual-electrolyte exhibit higher performance. • Cell performance increases with increasing electrolyte concentration and flow rate. • Optimized channel thickness is 0.3 mm. • A restriction of reaction activation on the Al side is observed. - Abstract: Energy storage capacity has been a major limiting factor in pursuit of increasing functionality and mobility for portable devices. To increase capacity limits, novel battery designs with multi-electron redox couples and increased voltages have been listed as a priority research direction by the US Department of Energy. This study leverages the benefits of microfluidics technology to develop a novel mixed-pH media aluminum–air cell which incorporates the advantages of the trivalence of aluminum and mixed-pH thermodynamics. Experimentally, the new cell exhibited an open circuit potential of 2.2 V and a maximum power density of 176 mW cm −2 , which are respectively 37.5% and 104.6% higher than conventional single alkaline aluminum–air cell under similar conditions. With further optimization of channel thickness, a power density of 216 mW cm −2 was achieved in the present study.

  1. On the performance of hybrid RF and RF/FSO dual-hop transmission systems

    KAUST Repository

    Ansari, Imran Shafique

    2013-10-01

    In this work, we present the performance analysis of a dual-branch transmission system composed of a direct radio frequency (RF) link and a dual-hop relay composed of asymmetric RF and free-space optical (FSO) links. The FSO link accounts for pointing errors and both types of detection techniques (i.e. intensity modulation/direct detection (IM/DD) as well as heterodyne detection). The performance is evaluated under the assumption of selection combining (SC) diversity scheme. RF links are modeled by Rayleigh fading distribution whereas the FSO link is modeled by a unified Gamma-Gamma fading distribution. Specifically, we derive new exact closed-form expressions for the cumulative distribution function, probability density function, moment generating function, and moments of the end-to-end signal-to-noise ratio of such systems in terms of the Meijer\\'s G function. We then capitalize on these results to offer new exact closed-form expressions for the outage probability, higher-order amount of fading, average error rate for binary and M-ary modulation schemes, and ergodic capacity, all in terms of Meijer\\'s G functions. © 2013 IEEE.

  2. Characterization of cognitive and motor performance during dual-tasking in healthy older adults and patients with Parkinson's disease.

    Science.gov (United States)

    Wild, Lucia Bartmann; de Lima, Daiane Borba; Balardin, Joana Bisol; Rizzi, Luana; Giacobbo, Bruno Lima; Oliveira, Henrique Bianchi; de Lima Argimon, Irani Iracema; Peyré-Tartaruga, Leonardo Alexandre; Rieder, Carlos R M; Bromberg, Elke

    2013-02-01

    The primary purpose of this study was to investigate the effect of dual-tasking on cognitive performance and gait parameters in patients with idiopathic Parkinson's disease (PD) without dementia. The impact of cognitive task complexity on cognition and walking was also examined. Eighteen patients with PD (ages 53-88, 10 women; Hoehn and Yahr stage I-II) and 18 older adults (ages 61-84; 10 women) completed two neuropsychological measures of executive function/attention (the Stroop Test and Wisconsin Card Sorting Test). Cognitive performance and gait parameters related to functional mobility of stride were measured under single (cognitive task only) and dual-task (cognitive task during walking) conditions with different levels of difficulty and different types of stimuli. In addition, dual-task cognitive costs were calculated. Although cognitive performance showed no significant difference between controls and PD patients during single or dual-tasking conditions, only the patients had a decrease in cognitive performance during walking. Gait parameters of patients differed significantly from controls at single and dual-task conditions, indicating that patients gave priority to gait while cognitive performance suffered. Dual-task cognitive costs of patients increased with task complexity, reaching significantly higher values then controls in the arithmetic task, which was correlated with scores on executive function/attention (Stroop Color-Word Page). Baseline motor functioning and task executive/attentional load affect the performance of cognitive tasks of PD patients while walking. These findings provide insight into the functional strategies used by PD patients in the initial phases of the disease to manage dual-task interference.

  3. Comparison of corrosion performance of grade 316 and grade 347H stainless steels in molten nitrate salt

    Science.gov (United States)

    Trent, M. C.; Goods, S. H.; Bradshaw, R. W.

    2016-05-01

    Stainless steel samples machined from SA-312 TP316 and SA-213 TP347H pipe were exposed to a molten nitrate salt environment at 600°C (1112°F) for up to 3000 hours in order to generate corrosion rates for use in concentrated solar power (CSP) facilities. Descaled weight loss measurements were made at 1000, 2000, and 3000 hours, with optical and scanning electron microscopy being performed on samples at the longest exposure time. The 316 and 347H alloys exhibited metal losses of 4.4 and 4.8 um respectively at 3000 hours. A linear fit to the data sets yielded annualized metal loss rates of 8.4 and 8.8 um/yr. The oxides were relatively uniform in thickness and multilayered. The inner layer consisted of a (Fe, Cr)-spinel with appreciable amounts of Mn while the outer layer was an oxide composed of only Fe. No pitting, intergranular attack, or other localized attack was found, despite the presence of a sensitized microstructure in both alloys and chloride impurity in the salt mixture. The observations presented here indicate that the two alloys perform quite comparably with respect to molten salt-induced corrosion and in that regard; either would be expected to perform satisfactorily in the intended application.

  4. Effect of steel reinforcement with different degree of corrosion on degeneration of mechanical performance of reinforced concrete frame joints

    Directory of Open Access Journals (Sweden)

    Wu Xu

    2016-02-01

    Full Text Available Beam-column joints which shoulders high-level and vertical shearing effect that maintains balance of beam and column end is the major component influencing the performance of the whole framework. Post earthquake investigation suggests that collapse of frame structure is induced by failure of joints in most cases. Thus, beam-column joints must have strong bearing capacity and good ductility, and reinforced concrete structure just meets the above requirement. But corrosion caused by long time use of reinforced concrete framework will lead to degeneration of mechanical performance of joints. To find out the rule of effect of steel reinforcement with different corrosion rate on degeneration of bearing capacity of reinforced concrete framework joints, this study made a nonlinear numerical analysis on fifteen models without stirrup in the core area of reinforced concrete frame joints using displacement method considering axial load ratio of column end and constraint condition. This work aims to find out the key factor that influences mechanical performance of joints, thus to provide a basis for repair and reinforcement of degenerated framework joints.

  5. Accelerated growth of oxide film on aluminium alloys under steam: Part II: Effects of alloy chemistry and steam vapour pressure on corrosion and adhesion performance

    DEFF Research Database (Denmark)

    Din, Rameez Ud; Bordo, Kirill; Jellesen, Morten Stendahl

    2015-01-01

    The steam treatment of aluminium alloys with varying vapour pressure of steamresulted in the growth of aluminium oxyhydroxide films of thickness range between 450 - 825nm. The surface composition, corrosion resistance, and adhesion of the produced films was characterised by XPS, potentiodynamic p...... of the vapour pressure of the steam. The accelerated corrosion and adhesion tests on steam generated oxide films with commercial powder coating verified that the performance of the oxide coating is highly dependent on the vapour pressure of the steam....... polarization, acetic acid salt spray, filiform corrosion test, and tape test. The oxide films formed by steam treatment showed good corrosion resistance in NaCl solution by significantly reducing anodic and cathodic activities. The pitting potential of the surface treated with steam was a function...

  6. The Effect of Impingement Velocity and Angle Variation on the Erosion Corrosion Performance of API 5L-X65 Carbon Steel in a Flow Loop

    Directory of Open Access Journals (Sweden)

    Ihsan UlHaq Toor

    2018-05-01

    Full Text Available Erosion corrosion performance of API 5L-X65 carbon steel was investigated at three different impingement velocities (3, 6 & 12 m/s, five different angles (15, 30, 45, 60, & 90°, and with/without solid particles (average particle size of 314 µm. The experiments were conducted in 0.2 M NaCl solution at room temperature for a duration of 24 h and the results showed that the maximum erosion corrosion rate was observed at 45° irrespective of the velocity. The highest erosion corrosion rate at 45° was due to the balance between the shear and normal impact stress at this angle. Ploughing, deep craters, and micro-forging/plastic deformation were found to be the main erosion corrosion mechanisms. The maximum wear scar depth measured using optical profilometery was found to be 51 µm (average at an impingement angle of 45°.

  7. On the performance of dual-hop FSO/RF systems

    KAUST Repository

    Zedini, Emna

    2016-04-21

    Exact closed-form performance metrics for mixed free-space optical/radio frequency (FSO/RF) communication systems are not available in the literature. This paper presents novel results for the performance analysis of a dual-hop FSO/RF transmission system where the FSO link is modeled by the Gamma-Gamma distribution with pointing error impairments and under heterodyne detection, and the RF link experiences the Nakagami-m fading. Using amplify-and-forward fixed gain relaying, new closed form expressions for the outage probability, the moments, the average bit-error-rate, and the ergodic capacity are obtained in terms of the extended generalized bivariate Meijer\\'s G function. Monte Carlo simulations are provided to confirm the accuracy of the newly proposed results.

  8. Performance and emission characteristics of a turpentine-diesel dual fuel engine

    Energy Technology Data Exchange (ETDEWEB)

    Karthikeyan, R. [Adhiparasakthi Engineering College, Melmaruvathur, Tamil Nadu (India); Mahalakshmi, N.V. [I.C. Engines Division, Department of Mechanical Engineering, College of Engineering Guindy, Chennai, Tamil Nadu (India)

    2007-07-15

    This paper describes an experimental study concerning the feasibility of using bio-oil namely turpentine obtained from the resin of pine tree. The emission and performance characteristics of a D.I. diesel engine were studied through dual fuel (DF) mode. Turpentine was inducted as a primary fuel through induction manifold and diesel was admitted into the engine through conventional fueling device as an igniter. The result showed that except volumetric efficiency, all other performance and emission parameters are better than those of diesel fuel with in 75% load. The toxic gases like CO, UBHC are slightly higher than that of the diesel baseline (DBL). Around 40-45% smoke reduction is obtained with DF mode. The pollutant No{sub x} is found to be equal to that of DBL except at full load. This study has proved that approximately 75% diesel replacement with turpentine is possible by DF mode with little engine modification. (author)

  9. Effects of dual task difficulty in motor and cognitive performance: Differences between adults and adolescents.

    Science.gov (United States)

    Bustillo-Casero, Pilar; Villarrasa-Sapiña, Israel; García-Massó, Xavier

    2017-10-01

    In the present study our aim was to compare dual-task performance in thirteen adolescents and fifteen young adults while concurrently performing a cognitive and a motor task. The postural control variables were obtained under three different conditions: i) bipedal stance, ii) tandem stance and iii) unipedal stance. The cognitive task consisted of a backward digit span test in which the participants were asked to memorize a sequence of numbers and then repeat the number in reverse order at three different difficulty levels (i.e. with 3, 4 and 5 digits). The difficulty of the cognitive task was seen to have different effects on adolescents and young adults. Adolescents seem to prioritize postural control during high difficulty postural conditions while a cross-domain competition model appeared in easy postural conditions. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Dose performance and image quality: Dual source CT versus single source CT in cardiac CT angiography

    International Nuclear Information System (INIS)

    Wang Min; Qi Hengtao; Wang Ximing; Wang Tao; Chen, Jiu-Hong; Liu Cheng

    2009-01-01

    Objective: To evaluate dose performance and image quality of 64-slice dual source CT (DSCT) in comparison to 64-slice single source CT (SSCT) in cardiac CT angiography (CTA). Methods: 100 patients examined by DSCT and 60 patients scanned by SSCT were included in this study. Objective indices such as image noise, contrast-to-noise ratio and signal-to-noise ratio were analyzed. Subjective image quality was assessed by two cardiovascular radiologists in consensus using a four-point scale (1 = excellent to 4 = not acceptable). Estimation of effective dose was performed on the basis of dose length product (DLP). Results: At low heart rates ( 0.05), but, at high heart rates (>70 bpm), DSCT provided robust image quality (P 70 bpm), DSCT is able to provide robust diagnostic image quality at doses far below that of SSCT.

  11. Performance Analysis of Dual-Polarized Massive MIMO System with Human-Care IoT Devices for Cellular Networks

    Directory of Open Access Journals (Sweden)

    Jun-Ki Hong

    2018-01-01

    Full Text Available The performance analysis of the dual-polarized massive multiple-input multiple-output (MIMO system with Internet of things (IoT devices is studied when outdoor human-care IoT devices are connected to a cellular network via a dual-polarized massive MIMO system. The research background of the performance analysis of dual-polarized massive MIMO system with IoT devices is that recently the data usage of outdoor human-care IoT devices has increased. Therefore, the outdoor human-care IoT devices are necessary to connect with 5G cellular networks which can expect 1000 times higher performance compared with 4G cellular networks. Moreover, in order to guarantee the safety of the patient for emergency cases, a human-care Iot device must be connected to cellular networks which offer more stable communication for outdoors compared to short-range communication technologies such as Wi-Fi, Zigbee, and Bluetooth. To analyze the performance of the dual-polarized massive MIMO system for human-care IoT devices, a dual-polarized MIMO spatial channel model (SCM is proposed which considers depolarization effect between the dual-polarized transmit-antennas and the receive-antennas. The simulation results show that the performance of the dual-polarized massive MIMO system is improved about 16% to 92% for 20 to 150 IoT devices compared to conventional single-polarized massive MIMO system for identical size of the transmit array.

  12. Corrosion performance of atmospheric plasma sprayed alumina coatings on AZ31B magnesium alloy under immersion environment

    OpenAIRE

    D. Thirumalaikumarasamy; K. Shanmugam; V. Balasubramanian

    2014-01-01

    Plasma sprayed ceramic coatings are successfully used in many industrial applications, where high wear and corrosion resistance with thermal insulation are required. The alumina powders were plasma sprayed on AZ31B magnesium alloy with three different plasma spraying parameters. In the present work, the influence of plasma spray parameters on the corrosion behavior of the coatings was investigated. The corrosion behavior of the coated samples was evaluated by immersion corrosion test in 3.5 w...

  13. Effects of Dual-Channel Functional Electrical Stimulation on Gait Performance in Patients with Hemiparesis

    Science.gov (United States)

    Springer, Shmuel; Vatine, Jean-Jacques; Lipson, Ronit; Wolf, Alon; Laufer, Yocheved

    2012-01-01

    The study objective was to assess the effect of functional electrical stimulation (FES) applied to the peroneal nerve and thigh muscles on gait performance in subjects with hemiparesis. Participants were 45 subjects (age 57.8 ± 14.8 years) with hemiparesis (5.37 ± 5.43 years since diagnosis) demonstrating a foot-drop and impaired knee control. Thigh stimulation was applied either to the quadriceps or hamstrings muscles, depending on the dysfunction most affecting gait. Gait was assessed during a two-minute walk test with/without stimulation and with peroneal stimulation alone. A second assessment was conducted after six weeks of daily use. The addition of thigh muscles stimulation to peroneal stimulation significantly enhanced gait velocity measures at the initial and second evaluation. Gait symmetry was enhanced by the dual-channel stimulation only at the initial evaluation, and single-limb stance percentage only at the second assessment. For example, after six weeks, the two-minute gait speed with peroneal stimulation and with the dual channel was 0.66 ± 0.30 m/sec and 0.70 ± 0.31 m/sec, respectively (P hemiparesis more than peroneal FES alone. PMID:23097635

  14. Rational hybrid modulation of P, N dual-doped holey graphene for high-performance supercapacitors

    Science.gov (United States)

    Nazarian-Samani, Masoud; Haghighat-Shishavan, Safa; Nazarian-Samani, Mahboobeh; Kim, Myeong-Seong; Cho, Byung-Won; Oh, Si-Hyoung; Kashani-Bozorg, Seyed Farshid; Kim, Kwang-Bum

    2017-12-01

    A P, N dual-doped holey graphene (PNHG) material is prepared by a scalable, facile synthetic approach, using a mixture of glucose, dicyandiamide (DCDA), and phosphoric acid (H3PO4). H3PO4 successfully functions as an "acid catalyst" to encourage the uniform breakage of C=C bonds to create large, localized perforations over the graphene monolith. Further acid treatment and annealing introduce in-plane holes. The correlation between the capacitance of the PNHG and its structural parameters during the fabrication process is comprehensively evaluated. A thermally induced sp2→sp3 transformation occurs at high temperatures because of the substantial loss of graphitic sp2-type carbons, together with a dramatic reduction in capacitance. The target PNHG-400 electrode material delivers exceptionally high gravimetric capacitance (235.5 F g-1 at 0.5 A g-1), remarkable rate capability (84.8% at 70 A g-1), superior capacitance retention (93.2 and 92.7% at 10 and 50 A g-1 over 25000 cycles, respectively), and acceptable volumetric capacitance due to moderate density, when it is used with organic electrolytes in the voltage range between 0 and 3 V. These results suggest a pioneering defect-engineered strategy to fabricate dual-doped holey graphene with valuable structural properties for high-performance electric double layer supercapacitors, which could be used in next-generation energy storage applications.

  15. Dual-Functional Ultrafiltration Membrane for Simultaneous Removal of Multiple Pollutants with High Performance.

    Science.gov (United States)

    Pan, Shunlong; Li, Jiansheng; Noonan, Owen; Fang, Xiaofeng; Wan, Gaojie; Yu, Chengzhong; Wang, Lianjun

    2017-05-02

    Simultaneous removal of multiple pollutants from aqueous solution with less energy consumption is crucial in water purification. Here, a novel concept of dual-functional ultrafiltration (DFUF) membrane is demonstrated by entrapment of nanostructured adsorbents into the finger-like pores of ultrafiltration (UF) membrane rather than in the membrane matrix in previous reports of blend membranes, resulting in an exceptionally high active content and simultaneous removal of multiple pollutants from water due to the dual functions of rejection and adsorption. As a demonstration, hollow porous Zr(OH) x nanospheres (HPZNs) were immobilized in poly(ether sulfone) (PES) UF membranes through polydopamine coating with a high content of 68.9 wt %. The decontamination capacity of DFUF membranes toward multiple model pollutants (colloidal gold, polyethylene glycol (PEG), Pb(II)) was evaluated against a blend membrane. Compared to the blend membrane, the DFUF membranes showed 2.1-fold increase in the effective treatment volume for the treatment of Pb(II) contaminated water from 100 ppb to below 10 ppb (WHO drinking water standard). Simultaneously, the DFUF membranes effectively removed the colloidal gold and PEG below instrument detection limit, however the blend membrane only achieved 97.6% and 96.8% rejection for colloidal gold and PEG, respectively. Moreover, the DFUF membranes showed negligible leakage of nanoadsorbents during testing; and the membrane can be easily regenerated and reused. This study sheds new light on the design of high performance multifunction membranes for drinking water purification.

  16. Exploring R&D Influences on Financial Performance for Business Sustainability Considering Dual Profitability Objectives

    Directory of Open Access Journals (Sweden)

    Kao-Yi Shen

    2017-10-01

    Full Text Available The importance of research and development (R&D for business sustainability have gained increasing interests, especially in the high-tech sector. However, the efforts of R&D might cause complex and mixed impacts on the financial results considering the associated expenses. Thus, this study aims to examine how R&D efforts may influence business to improve its financial performance considering the dual objectives: the gross and the net profitability. This research integrates a rough-set-based soft computing technique and multiple criteria decision-making (MCDM methods to explore this complex and yet valuable issue. A group of public listed companies from Taiwan, all in the semiconductor sector, is analyzed as a case study. More than 30 variables are considered, and the adopted soft computing technique retrieves 14 core attributes—for the dual profitability objectives—to form the evaluation model. The importance of R&D for pursuing superior financial prospects is confirmed, and the empirical case demonstrates how to guide an individual company to plan for improvements to achieve its long-term sustainability by this hybrid approach.

  17. Corrosion performance of MAO coatings on AZ31 Mg alloy in simulated body fluid vs. Earle's Balance Salt Solution

    Energy Technology Data Exchange (ETDEWEB)

    Wilke, Benjamin M. [Department of Mechanical Engineering, PO Box 755905, University of Alaska Fairbanks, Fairbanks, AK 99775 (United States); Zhang, Lei, E-mail: lzhang14@alaska.edu [Department of Mechanical Engineering, PO Box 755905, University of Alaska Fairbanks, Fairbanks, AK 99775 (United States); Li, Weiping; Ning, Chengyun [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510641 (China); Chen, Cheng-fu [Department of Mechanical Engineering, PO Box 755905, University of Alaska Fairbanks, Fairbanks, AK 99775 (United States); Gu, Yanhong [College of Mechanical Engineering, Beijing Institute of Petrochemical Technology, Beijing 102617 (China)

    2016-02-15

    Graphical abstract: - Highlights: • MAO coating is deposited on AZ31 Mg alloy by microarc oxidation. • Corrosion performance of MAO-coated AZ31 in EBSS vs. c-SBF is studied. • MAO-coated AZ31 exhibits enhanced corrosion resistance compared to bare AZ31. • Samples in EBSS show slower corrosion progression than the samples in c-SBF. • CO{sub 2} buffer and less chloride in EBSS cause corrosion rate gap in c-SBF and EBSS. - Abstract: Earle's Balance Salt Solution (EBSS) provides an alternative to the conventional simulated body fluids (c-SBF) and has been shown to better simulate the corrosion conditions in vivo. In this work, a series of tests were conducted to explore the corrosion performance of MAO-coated AZ31 samples in EBSS vs. c-SBF. Samples were produced by varying MAO process parameters and then immersed up to 21 days in both EBSS and c-SBF. The corrosion rates were evaluated by the electrochemical impedance spectroscopy and potentiodynamic scanning. Scanning electron microscope (SEM) was used to compare the progression of microcracks across the surface of the coatings. The evaluation of cross-sectional thickness showed an increase in MAO coating thickness with the process voltage. MAO samples with a thicker coating generally have higher impedance and lower current density at the initial immersion time point of 0.5 h. Samples in EBSS showed higher initial impedance and lower current density values as compared to c-SBF counterparts for all process groups. Samples in EBSS demonstrated a much slower corrosion rate than c-SBF samples because of the decreased chloride content and CO{sub 2} buffering mechanism of the EBSS.

  18. Corrosion performance of MAO coatings on AZ31 Mg alloy in simulated body fluid vs. Earle's Balance Salt Solution

    International Nuclear Information System (INIS)

    Wilke, Benjamin M.; Zhang, Lei; Li, Weiping; Ning, Chengyun; Chen, Cheng-fu; Gu, Yanhong

    2016-01-01

    Graphical abstract: - Highlights: • MAO coating is deposited on AZ31 Mg alloy by microarc oxidation. • Corrosion performance of MAO-coated AZ31 in EBSS vs. c-SBF is studied. • MAO-coated AZ31 exhibits enhanced corrosion resistance compared to bare AZ31. • Samples in EBSS show slower corrosion progression than the samples in c-SBF. • CO 2 buffer and less chloride in EBSS cause corrosion rate gap in c-SBF and EBSS. - Abstract: Earle's Balance Salt Solution (EBSS) provides an alternative to the conventional simulated body fluids (c-SBF) and has been shown to better simulate the corrosion conditions in vivo. In this work, a series of tests were conducted to explore the corrosion performance of MAO-coated AZ31 samples in EBSS vs. c-SBF. Samples were produced by varying MAO process parameters and then immersed up to 21 days in both EBSS and c-SBF. The corrosion rates were evaluated by the electrochemical impedance spectroscopy and potentiodynamic scanning. Scanning electron microscope (SEM) was used to compare the progression of microcracks across the surface of the coatings. The evaluation of cross-sectional thickness showed an increase in MAO coating thickness with the process voltage. MAO samples with a thicker coating generally have higher impedance and lower current density at the initial immersion time point of 0.5 h. Samples in EBSS showed higher initial impedance and lower current density values as compared to c-SBF counterparts for all process groups. Samples in EBSS demonstrated a much slower corrosion rate than c-SBF samples because of the decreased chloride content and CO 2 buffering mechanism of the EBSS.

  19. Corrosion cracking

    International Nuclear Information System (INIS)

    Goel, V.S.

    1985-01-01

    This book presents the papers given at a conference on alloy corrosion cracking. Topics considered at the conference included the effect of niobium addition on intergranular stress corrosion cracking, corrosion-fatigue cracking in fossil-fueled-boilers, fracture toughness, fracture modes, hydrogen-induced thresholds, electrochemical and hydrogen permeation studies, the effect of seawater on fatigue crack propagation of wells for offshore structures, the corrosion fatigue of carbon steels in seawater, and stress corrosion cracking and the mechanical strength of alloy 600

  20. Thermal Performance of a Dual-Channel, Helium-Cooled, Tungsten Heat Exchanger

    International Nuclear Information System (INIS)

    Youchison, Dennis L.; North, Mart T.

    2000-01-01

    Helium-cooled, refractory heat exchangers are now under consideration for first wall and divertor applications. These refractory devices take advantage of high temperature operation with large delta-Ts to effectively handle high heat fluxes. The high temperature helium can then be used in a gas turbine for high-efficiency power conversion. Over the last five years, heat removal with helium was shown to increase dramatically by using porous metal to provide a very large effective surface area for heat transfer in a small volume. Last year, the thermal performance of a bare-copper, dual-channel, helium-cooled, porous metal divertor mock-up was evaluated on the 30 kW Electron Beam Test System at Sandia National Laboratories. The module survived a maximum absorbed heat flux of 34.6 MW/m 2 and reached a maximum surface temperature of 593 C for uniform power loading of 3 kW absorbed on a 2-cm 2 area. An impressive 10 kW of power was absorbed on an area of 24 cm 2 . Recently, a similar dual-module, helium-cooled heat exchanger made almost entirely of tungsten was designed and fabricated by Thermacore, Inc. and tested at Sandia. A complete flow test of each channel was performed to determine the actual pressure drop characteristics. Each channel was equipped with delta-P transducers and platinum RTDs for independent calorimetry. One mass flow meter monitored the total flow to the heat exchanger, while a second monitored flow in only one of the channels. The thermal response of each tungsten module was obtained for heat fluxes in excess of 5 MW/m 2 using 50 C helium at 4 MPa. Fatigue cycles were also performed to assess the fracture toughness of the tungsten modules. A description of the module design and new results on flow instabilities are also presented

  1. Research Opportunities in Corrosion Science for Long-Term Prediction of Materials Performance: A Report of the DOE Workshop on ''Corrosion Issues of Relevance to the Yucca Mountain Waste Repository''

    International Nuclear Information System (INIS)

    Payer, Joe H.; Scully, John R.

    2003-01-01

    The report summarizes the findings of a U.S. Department of Energy workshop on ''Corrosion Issues of Relevance to the Yucca Mountain Waste Repository''. The workshop was held on July 29-30, 2003 in Bethesda, MD, and was co-sponsored by the Office of Basic Energy Sciences and Office of Civilian Radioactive Waste Management. The workshop focus was corrosion science relevant to long-term prediction of materials performance in hostile environments, with special focus on relevance to the permanent disposal of nuclear waste at the Yucca Mountain Repository. The culmination of the workshop is this report that identifies both generic and Yucca Mountain Project-specific research opportunities in basic and applied topic areas. The research opportunities would be realized well after the U.S. Nuclear Regulatory Commission's initial construction-authorization licensing process. At the workshop, twenty-three invited scientists deliberated on basic and applied science opportunities in corrosion science relevant to long-term prediction of damage accumulation by corrosive processes that affect materials performance.

  2. Research Opportunities in Corrosion Science for Long-Term Prediction of Materials Performance: A Report of the DOE Workshop on “Corrosion Issues of Relevance to the Yucca Mountain Waste Repository”.

    Energy Technology Data Exchange (ETDEWEB)

    Payer, Joe H. [Case Western Reserve Univ., Cleveland, OH (United States); Scully, John R. [Univ. of Virginia, Charlottesville, VA (United States)

    2003-07-29

    The report summarizes the findings of a U.S. Department of Energy workshop on “Corrosion Issues of Relevance to the Yucca Mountain Waste Repository”. The workshop was held on July 29-30, 2003 in Bethesda, MD, and was co-sponsored by the Office of Basic Energy Sciences and Office of Civilian Radioactive Waste Management. The workshop focus was corrosion science relevant to long-term prediction of materials performance in hostile environments, with special focus on relevance to the permanent disposal of nuclear waste at the Yucca Mountain Repository. The culmination of the workshop is this report that identifies both generic and Yucca Mountain Project-specific research opportunities in basic and applied topic areas. The research opportunities would be realized well after the U.S. Nuclear Regulatory Commission’s initial construction-authorization licensing process. At the workshop, twenty-three invited scientists deliberated on basic and applied science opportunities in corrosion science relevant to long-term prediction of damage accumulation by corrosive processes that affect materials performance.

  3. Reduced Dual-Task Performance in MS Patients Is Further Decreased by Muscle Fatigue.

    Science.gov (United States)

    Wolkorte, Ria; Heersema, Dorothea J; Zijdewind, Inge

    2015-06-01

    Multiple sclerosis (MS) can be accompanied by motor, cognitive, and sensory impairments. Additionally, MS patients often report fatigue as one of their most debilitating symptoms. It is, therefore, expected that MS patients will have difficulties in performing cognitive-motor dual tasks (DTs), especially in a fatiguing condition. To determine whether MS patients are more challenged by a DT than controls in a fatiguing and less-fatiguing condition and whether DT performance is associated with perceived fatigue. A group of 19 MS patients and 19 age-, sex-, and education-matched controls performed a cognitive task (2-choice reaction time task) separately or concurrent with a low-force or a high-force motor task (index finger abduction at 10% or 30% maximal voluntary contraction). MS patients performed less well on a cognitive task than controls. Cognitive task performance under DT conditions decreased more for MS patients. Moreover, under high-force DT conditions, cognitive performance declined in both groups but to a larger degree for MS patients. Besides a decline in cognitive task performance, MS patients also showed a stronger decrease in motor performance under high-force DT conditions. DT costs were positively related to perceived fatigue as measured by questionnaires. Compared with controls, MS patients performed less well on DTs as demonstrated by a reduction in both cognitive and motor performances. This performance decrease was stronger under fatiguing conditions and was related to the sense of fatigue of MS patients. These data illustrate problems that MS patients may encounter in daily life because of their fatigue. © The Author(s) 2014.

  4. Age-Related Changes in Brain Activation Underlying Single- and Dual-Task Performance: Visuomanual Drawing and Mental Arithmetic

    Science.gov (United States)

    Van Impe, A.; Coxon, J. P.; Goble, D. J.; Wenderoth, N.; Swinnen, S. P.

    2011-01-01

    Depending on task combination, dual-tasking can either be performed successfully or can lead to performance decrements in one or both tasks. Interference is believed to be caused by limitations in central processing, i.e. structural interference between the neural activation patterns associated with each task. In the present study, single- and…

  5. Attention and gaze shifting in dual-task and go/no-go performance with vocal responding

    NARCIS (Netherlands)

    Lamers, M.J.M.; Roelofs, A.P.A.

    2011-01-01

    Evidence from go/no-go performance on the Eriksen flanker task with manual responding suggests that individuals gaze at stimuli just as long as needed to identify them (e.g.. Sanders, 1998). In contrast, evidence from dual-task performance with vocal responding suggests that gaze shifts occur after

  6. Influence of performance characteristic of a gaseous fuel supply system on hydrocarbon emissions of a dual-fuel engine

    Energy Technology Data Exchange (ETDEWEB)

    Ren, J.; Wang, Z.Y.; Zhong, H.; Hao, S.H. [Xi' an Jiaotong Univ., Dept. of Automobile Engineering, Xi' an (China)

    2000-11-01

    The performance of the gaseous fuel supply and its influence on hydrocarbon (HC) emissions of dual-fuel engines have been investigated. A new design of manifold respirators with mixers is also presented in the paper. The design of the gaseous fuel supply system has a great influence on HC emissions in the dual-fuel engine at light load. The problem of scavenging is discussed and solved by using the manifold respirators in the dual-fuel engine. It performs the function of retarding the gaseous fuel entry timing from the moment of intake valve opening, and its delaying effects have been measured and tested. Experimental results show that the manifold respirator gives the best performance in reducing HC emissions compared with a common pipe mixer and a respirator with bo miser. In addition, the mixing effects are sensitive to the mixer configuration. (Author)

  7. Effects of combined organic and inorganic corrosion inhibitors on the nanostructure cerium based conversion coating performance on AZ31 magnesium alloy: Morphological and corrosion studies

    International Nuclear Information System (INIS)

    Saei, E.; Ramezanzadeh, B.; Amini, R.; Kalajahi, M. Salami

    2017-01-01

    Highlights: •Cn-Mn-polyvinyl alcohol conversion coating led to more uniform and crack free film deposition. •The corrosion resistance of Ce film was noticeably improved by using combination of polyvinyl alchol and Mn2+ cations. •A synergistic effect between polyvinyl alchol-Mn2+ resulted in Ce film with enhanced morphology and corrosion resistance. -- Abstract: Magnesium (Mg) AZ31 samples were chemically treated by a series of room temperature nanostructure cerium based conversion coatings containing Mn(NO 3 ) 2 ·4H 2 O, Co(NO 3 ) 2 ·6H 2 O, and polyvinyl alcohol (PVA). The microstructure and corrosion protection properties of different samples were studied by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS) and polarization test in 3.5 wt.% NaCl solution. Results demonstrated that the AZ31 Mg alloy sample treated by Ce-Mn-PVA showed the highest corrosion resistance. A denser Ce film with lower crack was precipitated on the sample treated by Ce-Mn-PVA conversion coating.

  8. Investigation of structure, adhesion strength, wear performance and corrosion behavior of platinum/ruthenium/nitrogen doped diamond-like carbon thin films with respect to film thickness

    International Nuclear Information System (INIS)

    Khun, N.W.; Liu, E.

    2011-01-01

    Research highlights: → Sputtered PtRuN-DLC thin films were fabricated with different film thicknesses. → The graphitization of the films increased with increased film thickness. → The wear resistance of the films increased though their adhesion strength decreased. → The corrosion potentials of the films shifted to more negative values. → However, the corrosion currents of the films decreased. - Abstract: In this study, the corrosion performance of platinum/ruthenium/nitrogen doped diamond-like carbon (PtRuN-DLC) thin films deposited on p-Si substrates using a DC magnetron sputtering deposition system in a 0.1 M NaCl solution was investigated using potentiodynamic polarization test in terms of film thickness. The effect of the film thickness on the chemical composition, bonding structure, surface morphology, adhesion strength and wear resistance of the PtRuN-DLC films was studied using X-ray photoelectron spectroscopy (XPS), micro-Raman spectroscopy, atomic force microscopy (AFM), micro-scratch test and ball-on-disc tribotest, respectively. It was found that the wear resistance of the PtRuN-DLC films apparently increased with increased film thickness though the adhesion strength of the films decreased. The corrosion results revealed that the increased concentration of sp 2 bonds in the PtRuN-DLC films with increased film thickness shifted the corrosion potentials of the films to more negative values but the decreased porosity density in the films significantly decreased the corrosion currents of the films.

  9. Performance study of a dual power source residential CCHP system based on PEMFC and PTSC

    International Nuclear Information System (INIS)

    Chen, Xi; Gong, Guangcai; Wan, Zhongmin; Zhang, Caizhi; Tu, Zhengkai

    2016-01-01

    Highlights: • A novel dual power source residential CCHP system model is proposed. • Low temperature and high current density guarantee the high efficiency of PTSC. • High system efficiency can be obtained at a relatively low solar radiation. • Government subsidy is a crucial factor to improve system economic performance. • System environmental performance is discussed by parametric study. - Abstract: This paper presents an innovative, hybrid residential CCHP system based on fuel cell and solar technologies that can provide electric power, heating and cooling. The CCHP system consists of a proton exchange membrane fuel cell (PEMFC) stack, parabolic trough solar collector (PTSC), double-effect absorption chiller and their relevant accessories. The effects of key operating parameters for PEMFC and PTSC systems (e.g.: current density, operating temperature and solar radiation) on the system thermodynamic performance are analyzed and discussed. The results show that the PEMFC operation temperature has a significant influence on the PTSC output performance in a hybrid CCHP system and that the PTSC also plays an important role as a bridge between the PEMFC stack and absorption chiller. The maximum efficiency of a hybrid system can reach 80.5%, which is higher than conventional CCHP systems, due to the high efficiency of PEMFC, PTSC and double-effect absorption chiller. The economic and environmental analysis of CCHP system are also performed, the results indicate the project is practicable, meanwhile, high current density and solar radiation and low operating temperature can improve pollutant emissions reduction of the system.

  10. Determination of Performance Measuring Parameters of an Improved Dual Paraboloid Solar Cooker

    Directory of Open Access Journals (Sweden)

    Suhail Zaki Farooqui

    2017-01-01

    Full Text Available An experimental investigation into the performance evaluation of an improved dual reflector foldable paraboloid solar cooker has been reported, along with its energy and exergy analysis. The best attribute of this lightweight and low-cost solar cooker is its high performance coupled with the ease of handling. The cooker utilizes two paraboloid reflectors made out of Mylar-coated fiberglass dishes, each having a diameter of 90 cm and focal length of 105 cm. The total intercepted radiation energy is 1.08 kW under standard test conditions. Stagnation temperatures of up to 330°C and cooking temperatures of up to 290°C have been attained with load. Altogether, 9 experiments have been performed with and without load. Loaded tests have been conducted with water and vegetable oil. Results indicate an average cooking power of 485 W, peak exergy gain of 60.53 W, quality factor of 0.077, and a high product of temperature difference gap at half peak power to peak power of 4364.33 W·K. The maximum exergy output power attained was 70 W, while maximum exergy efficiency was 8–10%. All performance measuring parameters indicate that it is a high performance solar cooker for rural and urban communities and is suitable for all types of oil- and water-based cooking.

  11. Performance Evaluation of a Dual Coverage System for Internet of Things Environments

    Directory of Open Access Journals (Sweden)

    Omar Said

    2016-01-01

    Full Text Available A dual coverage system for Internet of Things (IoT environments is introduced. This system is used to connect IoT nodes regardless of their locations. The proposed system has three different architectures, which are based on satellites and High Altitude Platforms (HAPs. In case of Internet coverage problems, the Internet coverage will be replaced with the Satellite/HAP network coverage under specific restrictions such as loss and delay. According to IoT requirements, the proposed architectures should include multiple levels of satellites or HAPs, or a combination of both, to cover the global Internet things. It was shown that the Satellite/HAP/HAP/Things architecture provides the largest coverage area. A network simulation package, NS2, was used to test the performance of the proposed multilevel architectures. The results indicated that the HAP/HAP/Things architecture has the best end-to-end delay, packet loss, throughput, energy consumption, and handover.

  12. Effect of pilot fuel quantity on the performance of a dual fuel engine

    Energy Technology Data Exchange (ETDEWEB)

    Abd Alla, G.H.; Soliman, H.A.; Badr, O.A.; Abd Rabbo, M.F. [Zagazig University, Cairo (Egypt). Shoubra Faculty of Engineering

    2000-04-01

    It is well known that the operation of dual fuel engines at lower loads suffers from lower thermal efficiency and higher unburned percentages of fuel. To rectify this problem, tests have been conducted on a special single cylinder compression ignition research engine (Ricardo E6) to investigate the effect of pilot fuel quantity on the performance of an indirect injection diesel engine fuelled with gaseous fuel. Diesel fuel was used as the pilot fuel and methane or propane was used as the main fuel which was inducted into the intake manifold to mix with the intake air. Through experimental investigations, it is shown that, the low efficiency and excess emissions at light loads can be improved significantly by increasing the amount of pilot fuel, while increasing the amount of pilot fuel at high loads led to early knocking. (author)

  13. Performance and Exhaust Emissions in a Natural-Gas Fueled Dual-Fuel Engine

    Science.gov (United States)

    Shioji, Masahiro; Ishiyama, Takuji; Ikegami, Makoto; Mitani, Shinichi; Shibata, Hiroaki

    In order to establish the optimum fueling in a natural gas fueled dual fuel engine, experiments were done for some operational parameters on the engine performances and the exhaust emissions. The results show that the pilot fuel quantity should be increased and its injection timing should be advanced to suppress unburned hydrocarbon emission in the middle and low output range, while the quantity should be reduced and the timing retarded to avoid onset of knock at high loads. Unburned hydrocarbon emission and thermal efficiency are improved by avoiding too lean natural gas mixture by restricting intake charge air. However, the improvement is limited because the ignition of pilot fuel deteriorates with excessive throttling. It is concluded that an adequate combination of throttle control and equivalence ratio ensures low hydrocarbon emission and the thermal efficiency comparable to diesel operation.

  14. Experimental Flow Performance Evaluation of novel miniaturized Advanced Piezoelectric Dual Cooling Jet

    International Nuclear Information System (INIS)

    De Bock, H P J; Whalen, B P; Chamarthy, P; Jackson, J L

    2012-01-01

    In recent years, electronics systems have significantly reduced in size at maintained or increased functionality. This trend has led to an increased demand for smaller and more capable thermal management. However, miniaturization of conventional fan and heat sink cooling systems introduce significant size, weight and efficiency challenges. In this study the flow performance of a novel alternative thin form-factor cooling solution, the advanced piezoelectric dual cooling jet(DCJ), is evaluated. A DCJ is a system where two piezoelectric actuators are excited to produce air flow. The total height of the device is about 1mm. The design of the experimental method for evaluating the equivalent fan-curve of the DCJ device is described in detail. Experimental results in comparison to conventional fan solutions are provided. The DCJ is expected to be a good candidate for thermal management in next generation thin profile consumer electronics.

  15. Performance analysis of decode-and-forward dual-hop optical spatial modulation with diversity combiner over atmospheric turbulence

    Science.gov (United States)

    Odeyemi, Kehinde O.; Owolawi, Pius A.; Srivastava, Viranjay M.

    2017-11-01

    Dual-hops transmission is a growing interest technique that can be used to mitigate against atmospheric turbulence along the Free Space Optical (FSO) communication links. This paper analyzes the performance of Decode-and-Forward (DF) dual-hops FSO systems in-conjunction with spatial modulation and diversity combiners over a Gamma-Gamma atmospheric turbulence channel using heterodyne detection. Maximum Ratio Combiner (MRC), Equal Gain Combiner (EGC) and Selection Combiner (SC) are considered at the relay and destination as mitigation tools to improve the system error performance. Power series expansion of modified Bessel function is used to derive the closed form expression for the end-to-end Average Pairwise Error Probability (APEP) expressions for each of the combiners under study and a tight upper bound on the Average Bit Error Rate (ABER) per hop is given. Thus, the overall end-to-end ABER for the dual-hops FSO system is then evaluated. The numerical results depicted that dual-hops transmission systems outperformed the direct link systems. Moreover, the impact of having the same and different combiners at the relay and destination are also presented. The results also confirm that the combination of dual hops transmission with spatial modulation and diversity combiner significantly improves the systems error rate with the MRC combiner offering an optimal performance with respect to variation in atmospheric turbulence, change in links average received SNR and link range of the system.

  16. Quantitation of bone mineral by dual photon absorptiometry (DPA): Evaluation of instrument performance

    International Nuclear Information System (INIS)

    Dunn, W.L.; O'Duffy, A.; Wahner, H.W.

    1984-01-01

    Quantitation of bone mineral is used with increasing frequency for clinical studies. This paper details the principle of DPA and present an evaluation of the technique. DPA measurements were performed with a scanning dual photon system constructed at this institution and modeled after the device developed at the University of Wisconsin. The components are a rectilinear scanner frame, 1.5 Ci Gd-153 source, NaI(TL) detector and a PDP 11/03 computer. Dual discriminator windows are set on the 44 and 100 keV photon energies of Gd-153. Instrument linearity, accuracy and reproducibility were evaluated with ashed bone standards and simulated tissue covering. In these experiments computed and actual bone mineral have a correlation coefficient of 1.0 and a SEE of approximately 1.0% (Linear regression analysis). Precision and accuracy of a standard were studied over a period of two years. Mean error between actual and measured bone mineral was 0.28%. In vivo precision in six subjects averaged 2.3% (CV) for lumbar spine measurements. The effect of soft tissue compositional change was studied with ashed bone standards and human cadaver spine specimens. Intraosseous fat changes of 50% produced an average bone mineral measurement error of 1.4%. A 20% change in fat thickness produced a 2.5% error. In situ and in vitro scans of 9 cadaver spines were performed to study the effect of extraosseous fat. The mean percent difference between the two measurements was 0.7% (SEE=3.2%)

  17. Corrosion engineering

    Energy Technology Data Exchange (ETDEWEB)

    Fontana, M.G.

    1986-01-01

    This book emphasizes the engineering approach to handling corrosion. It presents corrosion data by corrosives or environments rather than by materials. It discusses the corrosion engineering of noble metals, ''exotic'' metals, non-metallics, coatings, mechanical properties, and corrosion testing, as well as modern concepts. New sections have been added on fracture mechanics, laser alloying, nuclear waste isolation, solar energy, geothermal energy, and the Statue of Liberty. Special isocorrosion charts, developed by the author, are introduced as a quick way to look at candidates for a particular corrosive.

  18. Corrosion properties of the Mg alloy coated with polypyrrole films

    International Nuclear Information System (INIS)

    Grubač, Zoran; Rončević, Ivana Škugor; Metikoš-Huković, Mirjana

    2016-01-01

    Highlights: • Electropolymerization of pyrrole on Mg-alloy surface in presence of salicylate. • Salicylate dual role in PPy deposition: passivation and electron transfer mediation. • Redox potential of salicylate corresponds to potential of PPy nucleation. • EIS and polarization corrosion studies of PPy coated Mg-alloy in Hanks’ solution. • Polypyrrole significantly slowdown Mg alloy corrosion in Hanks’ solution. - Abstract: In the present study the reactive surface of Mg alloy was coated with the nontoxic biocompatible polypyrrole (PPy) film synthesized by electrochemical oxidation from an aqueous salicylate solution. Salicylate ions prevent Mg dissolution and act as an electron transfer mediator during the PPy film nucleation, formation and growth on the alloy surface. Kinetics of the pyrrole polymerization as well as corrosion resistance of the PPy coated Mg alloy in the Hanks’ solution were investigated using dc electrochemical methods and electrochemical impedance spectroscopy (EIS). Characterization of the surface film was performed by optical and Fourier transform infrared spectroscopy (FTIR).

  19. [Features of dual--postural and calculation--task performance in patients with consequences of traumatic brain injury].

    Science.gov (United States)

    Zharikova, A V; Zhavoronkova, L A; Maksakova, O A; Kuptsova, S V

    2012-01-01

    Dual tasks with voluntary postural control and calculation have been done by 14 patients (25.7 +/- 4.7 yo.) after traumatic brain injury and 40 healthy volunteers (29.8 +/- 2.5 y.o.). Complex clinical (MMSE, FIM, MPAI-3 and Berg scales) and stabilographic evaluation has been performed. According to clinical evaluation 8 patients were included into group 1 with less severe functional deficit and 6 patients formed group 2 with more severe deficit. Parameters of motor and especially cognitive sub-tasks in patients were lower than in healthy subjects in both separate and dual tasks. In group 2 these parameters were lower than in group 1. Certain types of dual task where the quality of sub-tasks, especially of the motor-one increased in healthy subjects and patients of the first group were revealed. The complex of stabilographic parameters which could be used for estimation of quality of sub-tasks performance has been revealed. Dual tasks could be an additional method of evaluation of patients' adaptive possibilities and certain type of dual task could become a promising approach to recovery at late period of rehabilitation.

  20. Effects of alcohol on attention orienting and dual-task performance during simulated driving: an event-related potential study.

    Science.gov (United States)

    Wester, Anne E; Verster, Joris C; Volkerts, Edmund R; Böcker, Koen B E; Kenemans, J Leon

    2010-09-01

    Driving is a complex task and is susceptible to inattention and distraction. Moreover, alcohol has a detrimental effect on driving performance, possibly due to alcohol-induced attention deficits. The aim of the present study was to assess the effects of alcohol on simulated driving performance and attention orienting and allocation, as assessed by event-related potentials (ERPs). Thirty-two participants completed two test runs in the Divided Attention Steering Simulator (DASS) with blood alcohol concentrations (BACs) of 0.00%, 0.02%, 0.05%, 0.08% and 0.10%. Sixteen participants performed the second DASS test run with a passive auditory oddball to assess alcohol effects on involuntary attention shifting. Sixteen other participants performed the second DASS test run with an active auditory oddball to assess alcohol effects on dual-task performance and active attention allocation. Dose-dependent impairments were found for reaction times, the number of misses and steering error, even more so in dual-task conditions, especially in the active oddball group. ERP amplitudes to novel irrelevant events were also attenuated in a dose-dependent manner. The P3b amplitude to deviant target stimuli decreased with blood alcohol concentration only in the dual-task condition. It is concluded that alcohol increases distractibility and interference from secondary task stimuli, as well as reduces attentional capacity and dual-task integrality.

  1. Adsorption of alginate and albumin on aluminum coatings inhibits adhesion of Escherichia coli and enhances the anti-corrosion performances of the coatings

    Energy Technology Data Exchange (ETDEWEB)

    He, Xiaoyan; Liu, Yi; Huang, Jing; Chen, Xiuyong; Ren, Kun; Li, Hua, E-mail: lihua@nimte.ac.cn

    2015-03-30

    Graphical abstract: - Highlights: • Adsorption behaviors of alginate and albumin on Al coatings were investigated at molecular level. • The adsorption inhibits effectively the colonization of Escherichia coli bacteria. • The adsorption alters the wettability of the Al coatings. • The conditioning layer enhances anti-corrosion performances of the Al coatings. - Abstract: Thermal-sprayed aluminum coatings have been extensively used as protective layers against corrosion for steel structures in the marine environment. The corrosion usually deteriorates from marine biofouling, yet the mechanism of accelerated corrosion of the coatings remains elusive. As the first stage participating in biofouling process, adsorption of molecules plays critical roles in mediating formation of biofilm. Here, we report at molecular level the adsorption behaviors of albumin and marine polysaccharide on arc-sprayed aluminum coatings and their influence on adhesion of Escherichia coli. The adsorption of alginate and albumin was characterized by infrared spectra analyses and atomic force microscopic observation. The adsorption inhibits effectively adhesion of the bacteria. Further investigation indicates that alginate/albumin altered the hydrophilicity/hydrophobicity of the coatings instead of impacting the survival of the bacteria to decline their adhesion. The conditioning layer composed of the molecules enhances anti-corrosion performances of the coatings.

  2. Adsorption of alginate and albumin on aluminum coatings inhibits adhesion of Escherichia coli and enhances the anti-corrosion performances of the coatings

    International Nuclear Information System (INIS)

    He, Xiaoyan; Liu, Yi; Huang, Jing; Chen, Xiuyong; Ren, Kun; Li, Hua

    2015-01-01

    Graphical abstract: - Highlights: • Adsorption behaviors of alginate and albumin on Al coatings were investigated at molecular level. • The adsorption inhibits effectively the colonization of Escherichia coli bacteria. • The adsorption alters the wettability of the Al coatings. • The conditioning layer enhances anti-corrosion performances of the Al coatings. - Abstract: Thermal-sprayed aluminum coatings have been extensively used as protective layers against corrosion for steel structures in the marine environment. The corrosion usually deteriorates from marine biofouling, yet the mechanism of accelerated corrosion of the coatings remains elusive. As the first stage participating in biofouling process, adsorption of molecules plays critical roles in mediating formation of biofilm. Here, we report at molecular level the adsorption behaviors of albumin and marine polysaccharide on arc-sprayed aluminum coatings and their influence on adhesion of Escherichia coli. The adsorption of alginate and albumin was characterized by infrared spectra analyses and atomic force microscopic observation. The adsorption inhibits effectively adhesion of the bacteria. Further investigation indicates that alginate/albumin altered the hydrophilicity/hydrophobicity of the coatings instead of impacting the survival of the bacteria to decline their adhesion. The conditioning layer composed of the molecules enhances anti-corrosion performances of the coatings

  3. The SKB spent fuel corrosion programme. An evaluation of results from the experimental programme performed in the Studsvik Hot Cell Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Forsyth, R. [Forsyth Consulting, Nykoeping (Sweden)

    1997-12-01

    During the last few years, many of the specimens in the SKB programme on the corrosion of spent fuel have been analysed by the ICP-MS technique, shortly after conclusion of the corrosion tests, or by the analysis of archive samples. Together with the previous results, this has made available a much more extended analytical data base than that available before, and this has been used in a new evaluation which complements those published earlier. Some of the new analytical data is for tests performed on fuel specimens (from two reference fuel rods, one BWR and one PWR) which have been corrosion tested for over ten years. Most of the data refers to 16 fuel/clad specimens from a short BWR fuel rod, which had burnups over a range of 27.0 to 48.8 MWd/kg U. Detailed examination and characterisation of three other fuel specimens from the rod had shown that the specimens with the higher burnups in this series would have a fuel microstructure and alpha activity content and distribution which, theoretically, may promote enhanced corrosion. These specimens had been exposed to over 5 years of corrosion during nine water contact periods. The corrodants used were a simulated bicarbonate groundwater and de-ionised water, and both oxic and nominally anoxic conditions were included in the test matrix. Most of the emphasis in the evaluation has, therefore, been on the possible effects on corrosion behaviour of the linear heat rating and burnup of the fuels. However, examination of the variation with water contact time of the fractional release rates of selected fission products and their total release over the five years of corrosion, have shown that the corrosion rates during the first few weeks of corrosion of the specimens with the higher burnups were lower than those for specimens with slightly lower burnup. Later, the corrosion rates converged for all specimens. This has been interpreted to be due to burnup-related differences in the fuel microstructure, particularly in the

  4. Comparative study on Ti/Zr/V and chromate conversion treated aluminum alloys: Anti-corrosion performance and epoxy coating adhesion properties

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Wen; Li, Wenfang, E-mail: mewfli@163.com; Mu, Songlin; Fu, Nianqing; Liao, Zhongmiao

    2017-05-31

    Highlights: • The surface roughness and surface free energy of the AA6063 are significantly increased after TZVCC treatment. • The anti-corrosion performance of the AA6063 is effectively enhanced after TZVCC treatment. • Both the corrosion resistance and wet adhesion properties of the epoxy coating on the AA6063 are noticeably improved after TZVCC treatment. - Abstract: In this study, a Ti/Zr/V conversion coating (TZVCC) was deposited on the surface of aluminum alloy 6063 (AA6063) as an alternative of the chromate conversion coating (CCC). Both the TZVCC treated AA6063 (TZVCC/AA6063) and CCC treated AA6063 (CCC/AA6063) were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM) and contact angle measuring device. The anti-corrosion performance of the TZVCC/AA6063 and CCC/AA6063 was evaluated by electrochemical measurements and neutral salt spray tests. It showed that both the surface roughness and surface free energy of the AA6063 were significantly increased after TZVCC treatment. The anti-corrosion performance of TZVCC/AA6063 was superior to that of CCC/AA6063. In addition, the effects of the TZVCC and CCC on the adhesion properties and anti-corrosion performance of epoxy coating applied on samples were examined by pull-off tests and electrochemical impedance spectroscopy (EIS). The dry, wet and recovery adhesive strengths of the epoxy coating on TZVCC treated samples (epoxy coated TZVCC/AA6063) were very close to those of epoxy coating on CCC treated ones (epoxy coated CCC/AA6063). The epoxy coated TZVCC/AA6063 showed better corrosion resistance than the epoxy coated CCC/AA6063 and epoxy coated AA6063.

  5. Performance evaluation of a three-phase dual active bridge DC-DC converter with different transformer winding configurations

    NARCIS (Netherlands)

    Baars, N.; Everts, J.; Wijnands, K.; Lomonova, E.

    2016-01-01

    This paper investigates the impact of three transformer winding configurations, i.e. the Y-Y, the Y-Delta, and the Delta-Delta configuration, on the performance of a three-phase dual active bridge (DAB) dc–dc converter. For each configuration, equations for the phase currents, power flow, and zero

  6. Musical Training, Bilingualism, and Executive Function: A Closer Look at Task Switching and Dual-Task Performance

    Science.gov (United States)

    Moradzadeh, Linda; Blumenthal, Galit; Wiseheart, Melody

    2015-01-01

    This study investigated whether musical training and bilingualism are associated with enhancements in specific components of executive function, namely, task switching and dual-task performance. Participants (n = 153) belonging to one of four groups (monolingual musician, bilingual musician, bilingual non-musician, or monolingual non-musician)…

  7. Experimental study of dual fuel engine performance using variable LPG composition and engine parameters

    International Nuclear Information System (INIS)

    Elnajjar, Emad; Selim, Mohamed Y.E.; Hamdan, Mohammad O.

    2013-01-01

    Highlights: • The effect of using variable LPG is studied. • Five fuels with propane to butane % volume ratio are: 100-70-55-25-0. • 100% Propane composition shows the highest noise levels with similar performance. • At 45° BTDC injection timing 55% Propane LPG the only fuel experience knocking. • LPG fuels gave similar engine performance, with differences in levels of noise. - Abstract: The present work investigates experimentally the effect of LPG fuel with different composition and engine parameters on the performance of a dual compression engine. Five different blends of LPG fuels are used with Propane to Butane volume ratio of 100:0, 70:30, 55:45, 25:75, and 0:100. A single cylinder, naturally aspirated, four strokes, indirectly injected, water cooled modified Ricardo E6 engine, is used in this study. The study is carried out by measuring the cylinder pressure, engine load, engine speed, crank angle, and the fuel’s flow rate. The engine performance under variable LPG fuel composition, engine load, pilot fuel injection timing, compression ratio, pilot fuel mass and engine speed, are estimated by comparing the following engine parameters: the cylinder maximum pressure, the indicated mean effective pressure, the maximum rate of pressure rise, and the thermal efficiency. The experimental data indicates that the engine parameters are playing a major role on the engine’s performance. Different LPG fuel composition did not show a major effect on the engine efficiency but directly impacted the levels of generated combustion noise

  8. Numerical Investigation of Aerodynamic Performance and Loads of a Novel Dual Rotor Wind Turbine

    Directory of Open Access Journals (Sweden)

    Behnam Moghadassian

    2016-07-01

    Full Text Available The objective of this paper is to numerically investigate the effects of the atmospheric boundary layer on the aerodynamic performance and loads of a novel dual-rotor wind turbine (DRWT. Large eddy simulations are carried out with the turbines operating in the atmospheric boundary layer (ABL and in a uniform inflow. Two stability conditions corresponding to neutral and slightly stable atmospheres are investigated. The turbines are modeled using the actuator line method where the rotor blades are modeled as body forces. Comparisons are drawn between the DRWT and a comparable conventional single-rotor wind turbine (SRWT to assess changes in aerodynamic efficiency and loads, as well as wake mixing and momentum and kinetic energy entrainment into the turbine wake layer. The results show that the DRWT improves isolated turbine aerodynamic performance by about 5%–6%. The DRWT also enhances turbulent axial momentum entrainment by about 3.3 %. The highest entrainment is observed in the neutral stability case when the turbulence in the ABL is moderately high. Aerodynamic loads for the DRWT, measured as out-of-plane blade root bending moment, are marginally reduced. Spectral analyses of ABL cases show peaks in unsteady loads at the rotor passing frequency and its harmonics for both rotors of the DRWT.

  9. Silicene Flowers: A Dual Stabilized Silicon Building Block for High-Performance Lithium Battery Anodes.

    Science.gov (United States)

    Zhang, Xinghao; Qiu, Xiongying; Kong, Debin; Zhou, Lu; Li, Zihao; Li, Xianglong; Zhi, Linjie

    2017-07-25

    Nanostructuring is a transformative way to improve the structure stability of high capacity silicon for lithium batteries. Yet, the interface instability issue remains and even propagates in the existing nanostructured silicon building blocks. Here we demonstrate an intrinsically dual stabilized silicon building block, namely silicene flowers, to simultaneously address the structure and interface stability issues. These original Si building blocks as lithium battery anodes exhibit extraordinary combined performance including high gravimetric capacity (2000 mAh g -1 at 800 mA g -1 ), high volumetric capacity (1799 mAh cm -3 ), remarkable rate capability (950 mAh g -1 at 8 A g -1 ), and excellent cycling stability (1100 mA h g -1 at 2000 mA g -1 over 600 cycles). Paired with a conventional cathode, the fabricated full cells deliver extraordinarily high specific energy and energy density (543 Wh kg ca -1 and 1257 Wh L ca -1 , respectively) based on the cathode and anode, which are 152% and 239% of their commercial counterparts using graphite anodes. Coupled with a simple, cost-effective, scalable synthesis approach, this silicon building block offers a horizon for the development of high-performance batteries.

  10. Can dual processing theory explain physics students’ performance on the Force Concept Inventory?

    Directory of Open Access Journals (Sweden)

    Anna K. Wood

    2016-07-01

    Full Text Available According to dual processing theory there are two types, or modes, of thinking: system 1, which involves intuitive and nonreflective thinking, and system 2, which is more deliberate and requires conscious effort and thought. The Cognitive Reflection Test (CRT is a widely used and robust three item instrument that measures the tendency to override system 1 thinking and to engage in reflective, system 2 thinking. Each item on the CRT has an intuitive (but wrong answer that must be rejected in order to answer the item correctly. We therefore hypothesized that performance on the CRT may give useful insights into the cognitive processes involved in learning physics, where success involves rejecting the common, intuitive ideas about the world (often called misconceptions and instead carefully applying physical concepts. This paper presents initial results from an ongoing study examining the relationship between students’ CRT scores and their performance on the Force Concept Inventory (FCI, which tests students’ understanding of Newtonian mechanics. We find that a higher CRT score predicts a higher FCI score for both precourse and postcourse tests. However, we also find that the FCI normalized gain is independent of CRT score. The implications of these results are discussed.

  11. High-performance dual-speed CCD camera system for scientific imaging

    Science.gov (United States)

    Simpson, Raymond W.

    1996-03-01

    Traditionally, scientific camera systems were partitioned with a `camera head' containing the CCD and its support circuitry and a camera controller, which provided analog to digital conversion, timing, control, computer interfacing, and power. A new, unitized high performance scientific CCD camera with dual speed readout at 1 X 106 or 5 X 106 pixels per second, 12 bit digital gray scale, high performance thermoelectric cooling, and built in composite video output is described. This camera provides all digital, analog, and cooling functions in a single compact unit. The new system incorporates the A/C converter, timing, control and computer interfacing in the camera, with the power supply remaining a separate remote unit. A 100 Mbyte/second serial link transfers data over copper or fiber media to a variety of host computers, including Sun, SGI, SCSI, PCI, EISA, and Apple Macintosh. Having all the digital and analog functions in the camera made it possible to modify this system for the Woods Hole Oceanographic Institution for use on a remote controlled submersible vehicle. The oceanographic version achieves 16 bit dynamic range at 1.5 X 105 pixels/second, can be operated at depths of 3 kilometers, and transfers data to the surface via a real time fiber optic link.

  12. Heat transfer effects on the performance of an air standard Dual cycle

    International Nuclear Information System (INIS)

    Hou, S.-S.

    2004-01-01

    There are heat losses during the cycle of a real engine that are neglected in ideal air standard analysis. In this paper, the effects of heat transfer on the net work output and the indicated thermal efficiency of an air standard Dual cycle are analyzed. Heat transfer from the unburned mixture to the cylinder walls has a negligible effect on the performance for the compression process. Additionally, the heat transfer rates to the cylinder walls during combustion are the highest and extremely important. Therefore, we assume that the compression and power processes proceed instantaneously so that they are reversible adiabatics, and the heat losses during the heat rejection process can be neglected. The heat loss through the cylinder wall is assumed to occur only during combustion and is further assumed to be proportional to the average temperature of both the working fluid and the cylinder wall. The results show that the net work output versus efficiency characteristics and the maximum net work output and the corresponding efficiency bounds are strongly influenced by the magnitude of the heat transfer. Higher heat transfer to the combustion chamber walls lowers the peak temperature and pressure and reduces the work per cycle and the efficiency. The effects of other parameters, in conjunction with the heat transfer, including combustion constants, cut-off ratio and intake air temperature, are also reported. The results are of importance to provide good guidance for the performance evaluation and improvement of practical Diesel engines

  13. Performance of surrogate high-level waste glass in the presence of iron corrosion products

    International Nuclear Information System (INIS)

    Jain, V.; Pan, Y.M.

    2004-01-01

    Radionuclide release from a waste package (WP) is a series of processes that depend upon the composition and flux of groundwater contacting the waste-forms (WF); the corrosion rate of WP containers and internal components made of Alloy 22, 316L SS, 304L SS and carbon steel; the dissolution rate of high-level radioactive waste (HLW) glass and spent nuclear fuel (SNF); the solubility of radionuclides; and the retention of radionuclides in secondary mineral phases. In this study, forward reaction rate measurements were made on a surrogate HLW glass in the presence of FeCl 3 species. Results indicate that the forward reaction rate increases with an increase in the FeCl 3 concentration. The addition of FeCl 3 causes the drop in the pH due to hydrolysis of Fe 3+ ions in the solution. Results based on the radionuclide concentrations and dissolution rates for HLW glass and SNF indicate that the contribution from glass is similar to SNF at 75 deg C. (authors)

  14. Performance demonstration testing at the EPRI NDE center for intergranular stress corrosion cracking in BWR piping

    International Nuclear Information System (INIS)

    Pherigo, G.

    1986-01-01

    Intergranular stress corrosion cracking (IGSCC) has become a significant concern for the commercial electric utility industry during the past four years. As the IGSCC problem manifested itself, the Nuclear Regulatory Commission (NRC) responded by issuing Inspection and Enforcement (I and E) Bulletin 82-03 which required that ultrasonic inspection procedures be demonstrated on service- removed samples. The ability to reliably detect and discriminate IGSCC was recognized by the industry as a very difficult task, at best. Concurrent with the NRC bulletin, state-of-the-art yet practical techniques for the detection and discrimination of IGSCC had to be developed, demonstrated, and transferred to the field in a relatively short time. With the release of I and E Bulletin 83-02, procedures as well as personnel had to be qualified on service-removed samples. This paper reports how the EPRI Nondestructive Evaluation (NDE) Center developed the necessary technology and a formal training and qualification program to meet these needs on behalf of the industry

  15. Musical training, bilingualism, and executive function: a closer look at task switching and dual-task performance.

    Science.gov (United States)

    Moradzadeh, Linda; Blumenthal, Galit; Wiseheart, Melody

    2015-07-01

    This study investigated whether musical training and bilingualism are associated with enhancements in specific components of executive function, namely, task switching and dual-task performance. Participants (n = 153) belonging to one of four groups (monolingual musician, bilingual musician, bilingual non-musician, or monolingual non-musician) were matched on age and socioeconomic status and administered task switching and dual-task paradigms. Results demonstrated reduced global and local switch costs in musicians compared with non-musicians, suggesting that musical training can contribute to increased efficiency in the ability to shift flexibly between mental sets. On dual-task performance, musicians also outperformed non-musicians. There was neither a cognitive advantage for bilinguals relative to monolinguals, nor an interaction between music and language to suggest additive effects of both types of experience. These findings demonstrate that long-term musical training is associated with improvements in task switching and dual-task performance. Copyright © 2014 Cognitive Science Society, Inc.

  16. Student satisfaction and academic performance in a dual PharmD/MBA degree program.

    Science.gov (United States)

    Chumney, Elinor C G; Ragucci, Kelly R

    2006-04-15

    Evaluate the academic experience and satisfaction of students enrolled in the dual PharmD/MBA degree program between the South Carolina College of Pharmacy and The Citadel's School of Business Administration. Compare grade point averages of students enrolled in the dual degree program with those of traditional student colleagues. A standardized satisfaction survey instrument was administered to 32 students currently enrolled in the dual PharmD/MBA degree program. Grade point averages (GPAs) in both pharmacy and business coursework were also collected for analysis. There were slightly higher percentages of both female and minority students in the dual degree program compared to the pharmacy class as a whole. Eighteen (56%) of students completed the survey, and responses were generally positive. The mean GPA of students in the dual degree program was higher than that of both pharmacy (3.37 vs 3.08, p vs 3.64, not statistically significant) students not enrolled in the dual degree program. Students enrolled in the dual degree program did better academically than their counterparts and indicated an overall high level of satisfaction with the program.

  17. High temperature solution-nitriding and low-temperature nitriding of AISI 316: Effect on pitting potential and crevice corrosion performance

    DEFF Research Database (Denmark)

    Bottoli, Federico; Jellesen, Morten Stendahl; Christiansen, Thomas Lundin

    2018-01-01

    in a 0.1M NaCl solution and crevice corrosion immersion tests in 3wt% FeCl3 solution were studied before and after the bulk and surface treatments.Nitrogen addition in the bulk proved to have a beneficial effect on the pitting resistance of the alloy. The formation of a zone of expanded austenite...... at the material surface through low-temperature nitriding resulted in a considerable improvement of the pitting potential and the crevice corrosion performance of the steels....

  18. Design and Performance of LPG Fuel Mixer for Dual Fuel Diesel Engine

    Science.gov (United States)

    Desrial; Saputro, W.; Garcia, P. P.

    2018-05-01

    Small horizontal diesel engines are commonly used for agricultural machinery, however, availability of diesel fuel become one of big problems especially in remote area. Conversely, in line with government policy for conversion of kerosene into LPG for cooking, then LPG become more popular and available even in remote area. Therefore, LPG is potential fuel to replace the shortage of diesel fuel for operating diesel engine in remote area. The purpose of this study was to design mixing device for using dual fuel i.e. LPG and diesel fuel and evaluate its performance accordingly. Simulation by using CFD was done in order to analyze mixture characteristics of LPG in air intake manifold. The performance test was done by varying the amount of LPG injected in intake air at 20%, 25%, 30%, 35%, until 40%, respectively. Result of CFD contour simulation showed the best combination when mixing 30% LPG into the intake air. Performance test of this research revealed that mixing LPG in air intake can reduce the diesel fuel consumption about 0.7 l/hour (without load) and 1.14 l/hour (with load). Diesel engine revolution increases almost 300 rpm faster than when using diesel fuel only. Based on economic analysis, using the fuel combination (diesel fuel – LPG) is not recommended in the area near SPBU where the price of diesel fuel is standard. However, using the fuel combination LPG-diesel fuel is highly recommended in the remote areas in Indonesia where price of diesel fuel is comparatively expensive which will provide cheaper total fuel cost for diesel engine operation.

  19. Diagnostic performance of dual-energy CT stress myocardial perfusion imaging: direct comparison with cardiovascular MRI.

    Science.gov (United States)

    Ko, Sung Min; Song, Meong Gun; Chee, Hyun Kun; Hwang, Hweung Kon; Feuchtner, Gudrun Maria; Min, James K

    2014-12-01

    The purpose of this study was to assess the diagnostic performance of stress perfusion dual-energy CT (DECT) and its incremental value when used with coronary CT angiography (CTA) for identifying hemodynamically significant coronary artery disease. One hundred patients with suspected or known coronary artery disease without chronic myocardial infarction detected with coronary CTA underwent stress perfusion DECT, stress cardiovascular perfusion MRI, and invasive coronary angiography (ICA). Stress perfusion DECT and cardiovascular stress perfusion MR images were used for detecting perfusion defects. Coronary CTA and ICA were evaluated in the detection of ≥50% coronary stenosis. The diagnostic performance of coronary CTA for detecting hemo-dynamically significant stenosis was assessed before and after stress perfusion DECT on a per-vessel basis with ICA and cardiovascular stress perfusion MRI as the reference standard. The performance of stress perfusion DECT compared with cardiovascular stress perfusion MRI on a per-vessel basis in the detection of perfusion defects was sensitivity, 89%; specificity, 74%; positive predictive value, 73%; negative predictive value, 90%. Per segment, these values were sensitivity, 76%; specificity, 80%; positive predictive value, 63%; and negative predictive value, 88%. Compared with ICA and cardiovascular stress perfusion MRI per vessel territory the sensitivity, specificity, positive predictive value, and negative predictive value of coronary CTA were 95%, 61%, 61%, and 95%. The values for stress perfusion DECT were 92%, 72%, 68%, and 94%. The values for coronary CTA and stress perfusion DECT were 88%, 79%, 73%, and 91%. The ROC AUC increased from 0.78 to 0.84 (p=0.02) with the use of coronary CTA and stress perfusion DECT compared with coronary CTA alone. Stress perfusion DECT plays a complementary role in enhancing the accuracy of coronary CTA for identifying hemodynamically significant coronary stenosis.

  20. Simulation of storage performance on hydropneumatic driveline in dual hybrid hydraulic passenger car

    Directory of Open Access Journals (Sweden)

    Wasbari Faizil

    2017-01-01

    Full Text Available The charging process is one of the critical processes in the hydro-pneumatic driveline storage system. It converts the kinetic energy of the vehicle braking and coasting to the compression energy. This energy is stored in the storage device called the accumulator. The system is planned to be used on the dual hydro-pneumatic hybrid driveline and applied to a hydraulic hybrid passenger car. The aim of this paper is to find the effect of charging parameters on the storage performance through simulation. Through the storage behaviour, the desirable and optimal sizing of the accumulator can be selected. The paper emphasized on the effect of pressure elevation, pre-charge pressure, effective volume, thermal reaction and required time of the accumulator’s charging process. The circuit of charging process has been designed and simulated by using the hydraulic tool in the Automation Studio software. The simulation results were corroborated through the component specification for data rationality. Through the simulation, it was found that pre-charge pressure had a significant effect on the charging process. It determined the efficiency of the effective volume. The higher the pressure elevation, the higher the effective volume. Nevertheless, the more energy required to compress the nitrogen gas in the bladder. Besides, in term of volume displacement, higher volume displacement reduced charging time and lower the fluid temperature. The simulation had been positively highlighted the critical point in charging process which later on, benefited the sizing process in the component selection specification.

  1. Numerical Study of the Performance and Emission of a Diesel-Syngas Dual Fuel Engine

    Directory of Open Access Journals (Sweden)

    Shiquan Feng

    2017-01-01

    Full Text Available Based on the theory of direct relation graph (DRG and the sensitivity analysis, a reduced mechanism for the diesel-syngas dual fuel was constructed. Three small thresholds were applied in the process of the detailed mechanism simplification by DRG, and a skeletal mechanism with 185 elements and the 832 elementary reactions was obtained. According to the framework of the skeletal mechanism, the time-consuming approach of sensitivity analysis was employed for further simplification, and the skeletal mechanism was further reduced to the size of 158 elements and 705 reactions. The Chemkin software with the detailed mechanism was utilized to calculate the effect of syngas addition on the combustion characteristics of diesel combustion. The findings showed that the addition of syngas could reduce the ignition delay time and increase the laminar flame speed. Based on the reduced mechanism and engine parameters, a 3D model of the engine was constructed with the Forte code. The 3D model was adopted to study the effect of syngas addition on the performance and exhaust emissions of the engine and the relevant data of the experiment was used in the calibration of the 3D model.

  2. Performance Analysis and Optimization of Millimeter Wave Networks with Dual-Hop Relaying

    KAUST Repository

    Chelli, Ali

    2017-11-16

    In this paper, we use dual-hop relaying to overcome the signal blockage problem that occurs for millimeter waves (mmWaves) due to obstacles located in the propagation environment. Using device-to-device communication, a device in the neighborhood of the transmitter and the receiver can play the role of a relay by amplifying the signal from the source device and forwarding it to the destination device. We consider that both the relay and the destination devices are subject to interference. We study the performance of this mmWave network and derive an exact and asymptotic expressions for the bit error probability (BEP). The exact BEP expression is validated by Monte Carlo simulations. The asymptotic BEP allows determining the diversity order and the coding gain of the communication system. Additionally, we investigate the power allocation optimization subject to a power constraint and derive an analytical expression for the optimal power. Numerical results illustrate the gain achieved in terms of BEP thanks to optimal power allocation.

  3. Performance Investigation and Structure Optimization of a Flat Dual-Function Solar Collector

    Directory of Open Access Journals (Sweden)

    Jinwei Ma

    2015-01-01

    Full Text Available The performance of a dual-function solar collector (DFSC that can work as either water heater or air heater depending on seasonal requirement is investigated via both experimental and numerical approaches in this paper. The numerical results are well consistent with the experimental results. Daily efficiency of the thermosiphon system with DFSC is more than 55% in water heating mode and the instantaneous air heating efficiency of the collector reaches 60%. The effects of inner parameters on the thermal efficiency of the collector are analyzed by numerical simulations of the operation of DFSC in two working modes. It is found that the depths of the two air channels in DFSC have an optimal range suitable for both working modes. The thickness of back insulation should be no less than 0.06 m to prevent heat loss via backboard, and the diameter and number of copper tubes show notable effect on the efficiency of DFSC in water heating mode but slight effect in air heating mode.

  4. On the Performance Analysis of Dual-Hop Mixed FSO/RF Systems

    KAUST Repository

    Zedini, Emna

    2016-02-03

    This paper presents novel results for the performance analysis of dual-hop free-space optical/radio frequency (FSO/RF) transmission systems where the FSO link is modeled by the Gamma-Gamma distribution with pointing error impairments and under both heterodyne detection and intensity modulation with direct detection (IM/DD), and the RF link experiences the Generalized Nakagami-m fading. Using amplify-and-forward fixed-gain relaying as well as channel-state-information(CSI)- assisted relaying, we derive closed-form expressions for the outage probability, the average bit-error rate (BER), and the ergodic capacity in terms of the bivariate H-Fox function. For a special case, we obtain simplified results for Nakagami-m fading channels in the RF link. Further, new asymptotic results for the outage probability and the average BER at high signal-to-noise ratio (SNR) regime are presented in terms of simple functions. Numerical and Monte-Carlo simulation results are provided to verify the accuracy of the newly proposed results, and a perfect agreement is observed.

  5. Performance Analysis of Mixed Nakagami- m and Gamma–Gamma Dual-Hop FSO Transmission Systems

    KAUST Repository

    Zedini, Emna

    2015-02-01

    In this paper, we carry out a unified performance analysis of a dual-hop relay system over the asymmetric links composed of both radio-frequency (RF) and unified free-space optical (FSO) links under the effect of pointing errors. Both fixed and variable gain relay systems are studied. The RF link is modeled by the Nakagami-m fading channel and the FSO link by the Gamma-Gamma fading channel subject to both types of detection techniques (i.e., heterodyne detection and intensity modulation with direct detection). In particular, we derive new unified closed-form expressions for the cumulative distribution function, the probability density function, the moment generating function (MGF), and the moments of the end-to-end signal-to-noise ratio (SNR) of these systems in terms of the Meijer\\'s G function. Based on these formulas, we offer exact closed-form expressions for the outage probability (OP), the higher order amount of fading, and the average bit error rate (BER) of a variety of binary modulations in terms of the Meijer\\'s G function. Furthermore, an exact closed-form expression of the end-to-end ergodic capacity is derived in terms of the bivariate G function. Additionally, by using the asymptotic expansion of the Meijer\\'s G function at the high-SNR regime, we derive new asymptotic results for the OP, the MGF, and the average BER in terms of simple elementary functions.

  6. Simulating tokamak PFC performance using simultaneous dual beam particle loading with pulsed heat loading

    Science.gov (United States)

    Sinclair, Gregory; Gonderman, Sean; Tripathi, Jitendra; Ray, Tyler; Hassanein, Ahmed

    2017-10-01

    The performance of plasma facing components (PFCs) in a fusion device are expected to change due to high flux particle loading during operation. Tungsten (W) is a promising PFC candidate material, due to its high melting point, high thermal conductivity, and low tritium retention. However, ion irradiation of D and He have each shown to diminish the thermal strength of W. This work investigates the synergistic effect between ion species, using dual beam irradiation, on the thermal response of W during ELM-like pulsed heat loading. Experiments studied three different loading conditions: laser, laser + He+, and laser + He+ + D+. 100 eV He+ and D+ exposures used a flux of 3.0-3.5 x 1020 m-2 s-1. ELM-like loading was applied using a pulsed Nd:YAG laser at an energy density of 0.38-1.51 MJ m-2 (3600 1 ms pulses at 1 Hz). SEM imaging revealed that laser + He+ loading at 0.76 MJ m-2 caused surface melting, inhibiting fuzz formation. Increasing the laser fluence decreased grain size and increased surface pore density. Thermally-enhanced migration of trapped gases appear to reflect resultant molten morphology. This work was supported by the National Science Foundation PIRE project.

  7. The effect of single-task and dual-task balance exercise programs on balance performance in adults with osteoporosis: a randomized controlled preliminary trial.

    Science.gov (United States)

    Konak, H E; Kibar, S; Ergin, E S

    2016-11-01

    Osteoporosis is a serious disease characterized by muscle weakness in the lower extremities, shortened length of trunk, and increased dorsal kyphosis leading to poor balance performance. Although balance impairment increases in adults with osteoporosis, falls and fall-related injuries have been shown to occur mainly during the dual-task performance. Several studies have shown that dual-task performance was improved with specific repetitive dual-task exercises. The aims of this study were to compare the effect of single- and dual-task balance exercise programs on static balance, dynamic balance, and activity-specific balance confidence in adults with osteoporosis and to assess the effectiveness of dual-task balance training on gait speed under dual-task conditions. Older adults (N = 42) (age range, 45-88 years) with osteoporosis were randomly assigned into two groups. Single-task balance training group was given single-task balance exercises for 4 weeks, whereas dual-task balance training group received dual-task balance exercises. Participants received 45-min individualized training session, three times a week. Static balance was evaluated by one-leg stance (OLS) and a kinesthetic ability trainer (KAT) device. Dynamic balance was measured by the Berg Balance Scale (BBS), Time Up and Go (TUG) test, and gait speed. Self-confidence was assessed with the Activities-specific Balance Confidence (ABC-6) scale. Assessments were performed at baseline and after the 4-week program. At the end of the treatment periods, KAT score, BBS score, time in OLS and TUG, gait speeds under single- and dual-task conditions, and ABC-6 scale scores improved significantly in all patients (p gait speeds under single- and dual-task conditions showed significantly greater improvement in the dual-task balance training group than in the single-task balance training group (p gait speeds showed greater improvement following the application of a specific type of dual-task exercise programs

  8. Electrochemical and micro-gravimetric corrosion studies on spent fuel provide relevant source term data for a repository performance assessment

    International Nuclear Information System (INIS)

    Wegen, Detlef H.; Bottomley, Paul D. W.; Glatz, Jean-Paul

    2004-01-01

    Various electrochemical methods (corrosion potential monitoring, AC impedance analysis and electrochemical noise monitoring) were used in the investigation of UO 2 samples: natural and doped with two different levels of 238 Pu (0.1 and 10 wt%) simulating the increasing α-intensities seen with time in the repository. The results were compared and were able to show the intense, but also the very local nature of the radiolysis and to demonstrate that corrosion rates were proportional to α-radiolysis and hence the 238 Pu content; the corrosion rates were in accordance with earlier work at ITU. By contrast it was seen that the redox potentials only gave information as to the bulk solution that did not reflect the true conditions at the electrode interface that were driving the corrosion processes of UO 2 dissolution in groundwaters. The study shows how electrochemical techniques can provide vital information on the corrosion mechanism at the UO 2 /solution interface

  9. Effects of Gait Self-Efficacy and Lower-Extremity Physical Function on Dual-Task Performance in Older Adults

    Science.gov (United States)

    Banducci, Sarah E.; Daugherty, Ana M.; Fanning, Jason; Awick, Elizabeth A.; Porter, Gwenndolyn C.; Burzynska, Agnieszka; Shen, Sa; Kramer, Arthur F.; McAuley, Edward

    2017-01-01

    Objectives. Despite evidence of self-efficacy and physical function's influences on functional limitations in older adults, few studies have examined relationships in the context of complex, real-world tasks. The present study tested the roles of self-efficacy and physical function in predicting older adults' street-crossing performance in single- and dual-task simulations. Methods. Lower-extremity physical function, gait self-efficacy, and street-crossing success ratio were assessed in 195 older adults (60–79 years old) at baseline of a randomized exercise trial. During the street-crossing task, participants walked on a self-propelled treadmill in a virtual reality environment. Participants crossed the street without distraction (single-task trials) and conversed on a cell phone (dual-task trials). Structural equation modeling was used to test hypothesized associations independent of demographic and clinical covariates. Results. Street-crossing performance was better on single-task trials when compared with dual-task trials. Direct effects of self-efficacy and physical function on success ratio were observed in dual-task trials only. The total effect of self-efficacy was significant in both conditions. The indirect path through physical function was evident in the dual-task condition only. Conclusion. Physical function can predict older adults' performance on high fidelity simulations of complex, real-world tasks. Perceptions of function (i.e., self-efficacy) may play an even greater role. The trial is registered with United States National Institutes of Health ClinicalTrials.gov (ID: NCT01472744; Fit & Active Seniors Trial). PMID:28255557

  10. Study of the Effect of Sol pH and Nanoclay Incorporation on the Corrosion Protection Performance of a Silane Sol-Gel Coating

    Directory of Open Access Journals (Sweden)

    Najmeh Asadi

    2014-06-01

    Full Text Available This work is aimed to evaluate the role of nanoclay in the protective performance of an eco-friendly silane sol-gel layer applied on mild steel substrate in 0.1M sodium chloride solution. At the first step, the effect of pH of the silane solution, consisting of a mixture of γ-glycidoxypropiltrimethoxysilane and methyltriethoxysilane and tetraethoxysilane, on the coating performance was evaluated through electrochemical noise measurements. The values of characteristic charge as a parameter extracted from shot noise theory revealed that the sol pH determining the rate of hydrolysis can play an important role in the corrosion protection behavior of silane coatings. Then, the influence of clay nanoparticles on the corrosion protective performance of the hybrid silane film was studied through taking advantage of electrochemical techniques, including electrochemical impedance spectroscopy and polarization curves, as well as surface analysis methods. The obtained electrochemical data including the values of charge transfer resistance, coating resistance, low frequency impedance and corrosion current density showed that the silane sol gel film in the presence of clay nanoparticles can present an improved corrosion protection. The behavior was connected to an enhancement in the coating barrier properties. Moreover, FESEM and water contact angle confirmed the higher reticulation in case of the coating incorporating nanoclay.

  11. Predicting the Oxidation/Corrosion Performance of Structural Alloys in Supercritical CO2

    Energy Technology Data Exchange (ETDEWEB)

    Wright, Ian [Wright HT Inc., Denver, CO (United States); Kung, Steven [Electric Power Research Inst. (EPRI), Charlotte, NC (United States); Shingledecker, John [Electric Power Research Inst. (EPRI), Charlotte, NC (United States)

    2017-12-22

    This project was the first research to address oxidation of alloys under supercritical CO2 conditions relevant to a semi-open Allam Cycle system. The levels of impurities expected in the CO2 for typical operation were determined by thermodynamic and mass balance calculations, and a test rig was assembled and used to run corrosion tests at temperatures from 650 to 750°C in CO2 at 200 bar for up to 5,000h, with and without impurities. Oxidation rates were measured for seven alloys representing high-strength ferritic steels, standard austenitic steels, and Ni-based alloys with higher-temperature capabilities. The very thin, protective scales formed on the high-temperature alloys provided significant challenges in characterization and thickness measurement. The rates of mass gain and scale thickening were possibly slower when oxidizing impurities were present in the sCO2, and the scale morphologies formed on the ferritic and austenitic steels were consistent with expectations, and similar to those formed in high-pressure steam, with some potential influences of C. Some surface hardening (possibly due to carbon uptake) was identified in ferritic steels Grade 91 and VM12, and appeared more severe in commercially-pure CO2. Hardening was also observed in austenitic steel TP304H, but that in HR3C appeared anomalous, probably the result of work-hardening from specimen preparation. No hardening was found in Ni-base alloys IN617 and IN740H. An existing EPRI Oxide Exfoliation Model was modified for this application and used to evaluate the potential impact of the scales grown in sCO2 on service lifetimes in compact heat exchanger designs. Results suggested that reduction in flow area by simple oxide growth as well as by accumulation of exfoliated scale may have a major effect on the design of small-channel heat exchangers. In addition, the specific oxidation behavior of each alloy strongly influences the

  12. Clinical performance of dual-source computerized tomography (DSCT) in primary diagnostics of coronary heart diseases

    International Nuclear Information System (INIS)

    Brunner, H.; Froehner, S.; Wagner, M.; Schmitt, R.; Brunn, J.; Gietzen, F.H.; Kerber, S.

    2008-01-01

    Dual-source-CT-technology (DSCT) improves temporal resolution of cardiac computed tomography to 83 ms per heart-phase. In this study, the clinical performance of this new method is evaluated. Materials and Methods: In fifty patients (33 male, 17 female; age 50±13 years) with suspected coronary heart disease, CT angiography (slice thickness 0,75 mm, contrast-agent 60-80 ml iomeprol) was performed with a Somatom Definition scanner. Based on the coronary 15-segment-model of the AHA, scores for image quality and lumen reduction were established to enable the observer, to give recommendations for further therapy. Results: Out of 750 possible AHA-segments, 655 were depicted (87,3%). 591 segments (90,2%) were assessed without any limitation of quality, 49 (7,5%) segments showed moderate, and 15 (2,3%) segments severe limitation in image quality. 508 (77,6%) segments were without pathological findings, 92 (14,0%) segments had minimal atherosclerotic lesions, 42 (6,4%) segments suffered from stenoses with lumen reduction less than 70%, and 13 (2,0%) showed significant stenoses of more than 70%. In 31 patients (62%), coronary heart disease was ruled out by CT angiography without any need for further non-invasive or invasive diagnostics. 8 patients (16%) underwent stress-testing for ischemia. In 11 (22%) patients coronary angiography was recommended, and DSCT findings were confirmed in 10 cases. Only one LCx stenosis was overestimated in DSCT. Conclusion: Contrast-enhanced DSCT is a powerful tool in diagnosis of coronary heart disease. 98% of coronary segments could be assessed in diagnostic quality, and at least 90% of haemodynamically significant coronary stenoses were detected. (orig.)

  13. Improving the performance and fuel consumption of dual chamber stratified charge spark ignition engines

    Energy Technology Data Exchange (ETDEWEB)

    Sorenson, S.C.; Pan, S.S.; Bruckbauer, J.J.; Gehrke, G.R.

    1979-09-01

    A combined experimental and theoretical investigation of the nature of the combustion processes in a dual chamber stratified charge spark ignition engine is described. This work concentrated on understanding the mixing process in the main chamber gases. A specially constructed single cylinder engine was used to both conduct experiments to study mixing effects and to obtain experimental data for the validation of the computer model which was constructed in the theoretical portion of the study. The test procedures are described. Studies were conducted on the effect of fuel injection timing on performance and emissions using the combination of orifice size and prechamber to main chamber flow rate ratio which gave the best overall compromise between emissions and performance. In general, fuel injection gave slightly higher oxides of nitrogen, but considerably lower hydrocarbon and carbon monoxide emissions than the carbureted form of the engine. Experiments with engine intake port redesign to promote swirl mixing indicated a substantial increase in the power output from the engine and, that an equivalent power levels, the nitric oxide emissions are approximately 30% lower with swirl in the main chamber than without swirl. The development of a computer simulation of the combustion process showed that a one-dimensional combustion model can be used to accurately predict trends in engine operation conditions and nitric oxide emissions even though the actual flame in the engine is not completely one-dimensional, and that a simple model for mixing of the main chamber and prechamber intake gases at the start of compression proved adequate to explain the effects of swirl, ignition timing, overall fuel air ratio, volumetric efficiency, and variations in prechamber air fuel ratio and fuel rate percentage on engine power and nitric oxide emissions. (LCL)

  14. Effect of biodiesel blends on engine performance and exhaust emission for diesel dual fuel engine

    International Nuclear Information System (INIS)

    Mohsin, R.; Majid, Z.A.; Shihnan, A.H.; Nasri, N.S.; Sharer, Z.

    2014-01-01

    Highlights: • Engine and emission characteristics of biodiesel DDF engine system were measured. • Biodiesel DDF fuelled system produced high engine performance. • Lower hydrocarbons and carbon dioxide was emitted by biodiesel DDF system. • Biodiesel DDF produced slightly higher carbon monoxide and nitric oxides emission. - Abstract: Biodiesel derived from biomass is a renewable source of fuel. It is renovated to be the possible fuel to replace fossil derived diesel due to its properties and combustion characteristics. The integration of compressed natural gas (CNG) in diesel engine known as diesel dual fuel (DDF) system offered better exhaust emission thus become an attractive option for reducing the pollutants emitted from transportation fleets. In the present study, the engine performance and exhaust emission of HINO H07C DDF engine; fuelled by diesel, biodiesel, diesel–CNG, and biodiesel–CNG, were experimentally studied. Biodiesel and diesel fuelled engine system respectively generated 455 N m and 287 N m of torque. The horse power of biodiesel was found to be 10–20% higher compared to diesel. Biodiesel–CNG at 20% (B20-DDF) produced the highest engine torque compared to other fuel blends Biodiesel significantly increase the carbon monoxide (15–32%) and nitric oxides (6.67–7.03%) but in contrast reduce the unburned hydrocarbons (5.76–6.25%) and carbon dioxide (0.47–0.58%) emissions level. These results indicated that biodiesel could be used without any engine modifications as an alternative and environmentally friendly fuel especially the heavy transportation fleets

  15. Brain activation during dual-task processing is associated with cardiorespiratory fitness and performance in older adults

    Directory of Open Access Journals (Sweden)

    Chelsea N Wong

    2015-08-01

    Full Text Available Higher cardiorespiratory fitness is associated with better cognitive performance and enhanced brain activation. Yet, the extent to which cardiorespiratory fitness-related brain activation is associated with better cognitive performance is not well understood. In this cross-sectional study, we examined whether the association between cardiorespiratory fitness and executive function was mediated by greater prefrontal cortex activation in healthy older adults. Brain activation was measured during dual-task performance with functional magnetic resonance imaging in a sample of 128 healthy older adults (59-80 years. Higher cardiorespiratory fitness was associated with greater activation during dual-task processing in several brain areas including the anterior cingulate and supplementary motor cortex (ACC/SMA, thalamus and basal ganglia, right motor/somatosensory cortex and middle frontal gyrus, and left somatosensory cortex, controlling for age, sex, education, and gray matter volume. Of these regions, greater ACC/SMA activation mediated the association between cardiorespiratory fitness and dual-task performance. We provide novel evidence that cardiorespiratory fitness may support cognitive performance by facilitating brain activation in a core region critical for executive function.

  16. Efficiency maximization and performance evaluation of hybrid dual channel semitransparent photovoltaic thermal module using fuzzyfied genetic algorithm

    International Nuclear Information System (INIS)

    Singh, Sonveer; Agrawal, Sanjay

    2016-01-01

    Highlights: • Thermal modeling of novel dual channel semitransparent photovoltaic thermal hybrid module. • Efficiency maximization and performance evaluation of dual channel photovoltaic thermal module. • Annual performance has been evaluated for Srinagar, Jodhpur, Bangalore and New Delhi (India). • There are improvements in results for optimized system as compared to un-optimized system. - Abstract: The work has been carried out in two steps; firstly the parameters of hybrid dual channel semitransparent photovoltaic thermal module has been optimized using a fuzzyfied genetic algorithm. During the course of optimization, overall exergy efficiency is considered as an objective function and different design parameters of the proposed module have been optimized. Fuzzy controller is used to improve the performance of genetic algorithms and the approach is called as a fuzzyfied genetic algorithm. In the second step, the performance of the module has been analyzed for four cities of India such as Srinagar, Bangalore, Jodhpur and New Delhi. The performance of the module has been evaluated for daytime 08:00 AM to 05:00 PM and annually from January to December. It is to be noted that, an average improvement occurs in electrical efficiency of the optimized module, simultaneously there is also a reduction in solar cell temperature as compared to un-optimized module.

  17. Investigation of structure, adhesion strength, wear performance and corrosion behavior of platinum/ruthenium/nitrogen doped diamond-like carbon thin films with respect to film thickness

    Energy Technology Data Exchange (ETDEWEB)

    Khun, N.W. [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Liu, E., E-mail: MEJLiu@ntu.edu.sg [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

    2011-03-15

    Research highlights: {yields} Sputtered PtRuN-DLC thin films were fabricated with different film thicknesses. {yields} The graphitization of the films increased with increased film thickness. {yields} The wear resistance of the films increased though their adhesion strength decreased. {yields} The corrosion potentials of the films shifted to more negative values. {yields} However, the corrosion currents of the films decreased. - Abstract: In this study, the corrosion performance of platinum/ruthenium/nitrogen doped diamond-like carbon (PtRuN-DLC) thin films deposited on p-Si substrates using a DC magnetron sputtering deposition system in a 0.1 M NaCl solution was investigated using potentiodynamic polarization test in terms of film thickness. The effect of the film thickness on the chemical composition, bonding structure, surface morphology, adhesion strength and wear resistance of the PtRuN-DLC films was studied using X-ray photoelectron spectroscopy (XPS), micro-Raman spectroscopy, atomic force microscopy (AFM), micro-scratch test and ball-on-disc tribotest, respectively. It was found that the wear resistance of the PtRuN-DLC films apparently increased with increased film thickness though the adhesion strength of the films decreased. The corrosion results revealed that the increased concentration of sp{sup 2} bonds in the PtRuN-DLC films with increased film thickness shifted the corrosion potentials of the films to more negative values but the decreased porosity density in the films significantly decreased the corrosion currents of the films.

  18. Corrosion performance of atmospheric plasma sprayed alumina coatings on AZ31B magnesium alloy under immersion environment

    Directory of Open Access Journals (Sweden)

    D. Thirumalaikumarasamy

    2014-12-01

    Full Text Available Plasma sprayed ceramic coatings are successfully used in many industrial applications, where high wear and corrosion resistance with thermal insulation are required. The alumina powders were plasma sprayed on AZ31B magnesium alloy with three different plasma spraying parameters. In the present work, the influence of plasma spray parameters on the corrosion behavior of the coatings was investigated. The corrosion behavior of the coated samples was evaluated by immersion corrosion test in 3.5 wt% NaCl solution. Empirical relationship was established to predict the corrosion rate of plasma sprayed alumina coatings by incorporating process parameters. The experiments were conducted based on a three factor, five-level, central composite rotatable design matrix. The developed relationship can be effectively used to predict the corrosion rate of alumina coatings at 95% confidence level. The results indicate that the input power has the greatest influence on corrosion rate, followed by stand-off distance and powder feed rate.

  19. BWR steel containment corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Tan, C.P.; Bagchi, G.

    1996-04-01

    The report describes regulatory actions taken after corrosion was discovered in the drywell at the Oyster Creek Plant and in the torus at the Nine Mile Point 1 Plant. The report describes the causes of corrosion, requirements for monitoring corrosion, and measures to mitigate the corrosive environment for the two plants. The report describes the issuances of generic letters and information notices either to collect information to determine whether the problem is generic or to alert the licensees of similar plants about the existence of such a problem. Implementation of measures to enhance the containment performance under severe accident conditions is discussed. A study by Brookhaven National Laboratory (BNL) of the performance of a degraded containment under severe accident conditions is summarized. The details of the BNL study are in the appendix to the report.

  20. The comparison of Selective Attention Deficit in Dual Task Performance in Elderly Alzheimer Patients and Healthy Elderly Individuals

    Directory of Open Access Journals (Sweden)

    A. m. Azadian

    2014-06-01

    Full Text Available The purpose of this study was to compare selective attention deficit in elderly Alzheimer patients and healthy elderly individuals using the dual task. Therefore, 23 subjects (11 females and 12 males age 62 to 81 years; 13 patients with Alzheimer's disease (AD and 10 healthy elderly subjects (EHI with normal cognitive function participated in this study. people with Alzheimer's disease. healthy people was selected through some neurologist identified Short Portable Mental Status Questionnaire (SPMSQ. After obtaining the average number of correct counting of months of the year in both simple and difficult cognitive task the overall error (E or Root Mean Squared Error (RMSE, and variable error (VE were calculated for the tracking task. Then each person performed 10 tasks simultaneously (under Dual-task in both simple and difficult mode. Analysis of variance in cognitive tasks showed that there was a significant interaction between task difficulty and risk of AD (p0.05. In other words, at dual conditions of tracking task, accuracy and consistency of both groups was equally reduced, which was most prominent in difficult conditions. This decrease indicates increased interference at response level due to defects in the mechanisms of selective attention in dual cognitive and tracking tasks and both groups.

  1. PERFORMANCE ANALYSIS OF ARQ AND HYBRID ARQ OVER SINGLE-HOP, DUAL-HOP, AND MULTIBRANCH DUAL-HOP NETWORKS

    KAUST Repository

    Hadjtaieb, Amir

    2014-05-01

    During the last decade, relay networks have attracted a lot of interest due to their numerous benefits. The relaying technique allows extending the coverage zone of wireless networks and offers a higher reliability for communication systems. The performance of relay networks can be improved further by the use of automatic repeat request (ARQ) and hybrid automatic repeat request (HARQ) techniques. ARQ and HARQ are retransmission mechanisms that ensure a good quality of service even in absence of channel state information at the transmitter. We, firstly, study the spectral and energy efficiency of ARQ in Nakagami-m block-fading channels. We maximize both spectral efficiency and energy efficiency with respect to the transmitted power. We derive exact expressions as well as compact and tight approximation for the solutions of these problems. Our analysis shows that the two problems of maximizing spectral efficiency and energy efficiency with respect to the transmitted power are completely different and give different solutions. Additionally, operating with a power that maximizes energy efficiency can lead to a significant drop in the spectral efficiency, and vice versa. Next, we consider a three node relay network comprising a source, a relay, and a destination. The source transmits the message to the destination using HARQ with incremental redundancy (IR). The relay overhears the transmitted message, amplifies it using a variable gain amplifier, and then forwards the message to the destination. This latter combines both the source and the relay message and tries to decode the information. In case of decoding failure, the destination sends a negative acknowledgement. A new replica of the message containing new parity bits is then transmitted in the subsequent HARQ round. This process continues until successful decoding occurs at the destination or a maximum number M of rounds is reached. We study the performance of HARQ-IR over the considered relay channel from an

  2. Dual-source dual-energy CT angiography with virtual non-enhanced images and iodine map for active gastrointestinal bleeding: Image quality, radiation dose and diagnostic performance

    International Nuclear Information System (INIS)

    Sun, Hao; Hou, Xin-Yi; Xue, Hua-Dan; Li, Xiao-Guang; Jin, Zheng-Yu; Qian, Jia-Ming; Yu, Jian-Chun; Zhu, Hua-Dong

    2015-01-01

    in 84 patients, 83 (83/84, 98.8%) of which were confirmed by one or more reference standard. The AUC was 0.935 ± 0.027 and 0.947 ± 0.026 for protocols 1 and 2, respectively. There was no significant difference between protocols 1 and 2 for diagnostic performance (Z = 1.672, P > 0.05). The radiation dose reduction achieved by omitting the TNE acquisition was (30.11 ± 6.32)%. Conclusion: DSDECTA with arterial phase with single-source mode, portal-venous phase with dual-energy mode and post-processing VNE image sets and iodine map could act as an accurate screening method for detection and localization of active GIB with lower radiation dose

  3. Dual-source dual-energy CT angiography with virtual non-enhanced images and iodine map for active gastrointestinal bleeding: Image quality, radiation dose and diagnostic performance

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Hao, E-mail: sunhao_robert@126.com [Department of Radiology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing Street, Dongcheng District, Beijing 100730 (China); Hou, Xin-Yi, E-mail: hxy_pumc@126.com [Department of Radiology, Beijing Tiantan Hospital, Capital Medical University, Beijing (China); Xue, Hua-Dan, E-mail: bjdanna95@hotmail.com [Department of Radiology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing Street, Dongcheng District, Beijing 100730 (China); Li, Xiao-Guang, E-mail: xglee88@126.com [Department of Radiology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing Street, Dongcheng District, Beijing 100730 (China); Jin, Zheng-Yu, E-mail: zhengyu_jin@126.com [Department of Radiology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing Street, Dongcheng District, Beijing 100730 (China); Qian, Jia-Ming, E-mail: qjiaming57@gmail.com [Department of Gastroenterology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing (China); Yu, Jian-Chun, E-mail: yu-jch@163.com [Department of General Surgery, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing (China); Zhu, Hua-Dong, E-mail: huadongzhu@hotmail.com [Department of Emergency, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing (China)

    2015-05-15

    in 84 patients, 83 (83/84, 98.8%) of which were confirmed by one or more reference standard. The AUC was 0.935 ± 0.027 and 0.947 ± 0.026 for protocols 1 and 2, respectively. There was no significant difference between protocols 1 and 2 for diagnostic performance (Z = 1.672, P > 0.05). The radiation dose reduction achieved by omitting the TNE acquisition was (30.11 ± 6.32)%. Conclusion: DSDECTA with arterial phase with single-source mode, portal-venous phase with dual-energy mode and post-processing VNE image sets and iodine map could act as an accurate screening method for detection and localization of active GIB with lower radiation dose.

  4. Alkali-corrosion synthesis and excellent DSSC performance of novel jujube-like hierarchical TiO2 microspheres

    Science.gov (United States)

    Xiao, Jiajia; Li, Po; Wen, Xiaogang

    2018-04-01

    Novel jujube-like hierarchical TiO2 microspheres (HTMs) were synthesized by an alkali-corrosion process of titanium phosphate (Ti2O3(H2PO4)2 · 2H2O) microspheres. The hierarchical titanium phosphate microsphere (HTPM) intermediates consisting of nanoflakes with a thickness of 20 nm were firstly prepared by a facile hydrothermal method. After reacting with diluted NaOH at low temperature and atmospheric pressure, followed by subsequent acid washing and a calcination process, the HTPM intermediates were transformed to TiO2 with the microsphere morphology well retained, while the nanoflakes became porous, and some new nanowires were formed between the nanoflakes. Finally, HTMs consisting of porous nanoflakes and nanowires were obtained. The possible growth mechanisms of HTPMs and HTMs are discussed. The HTMs demonstrate high specific surface area and excellent light-scattering ability. The performance of the dye sensitized solar cells (DSSCs) of the HTMs synthesized under different conditions is studied, and a total conversion efficiency of up to 8.93% was obtained. The improved DSSC performance was attributed to the enhanced dye loading, light-scattering, and charge transporting ability of the HTMs with a unique hierarchical nanostructure.

  5. EFFECT OF INJECTOR OPENING PRESSURE ON PERFORMANCE AND EMISSION OF LPG - METHYL ESTER OF MAHUA OIL DUAL FUEL ENGINE

    Directory of Open Access Journals (Sweden)

    N. Kapilan

    2017-11-01

    Full Text Available One of variables, which affect the performance and emission of dual fuel engine is injection pressure. Hence in the present work, effect of Injector opening pressure on the performance of the engine was studied.  A four stroke single cylinder engine was modified to work in dual fuel mode. Three injector opening pressures (180 bar, 200 bar and 220 bar were considered for the present work. Methyl ester of mahua oil was used as pilot fuel and LPG was used as primary fuel.    From the test results, it was observed that the injector opening pressure of 200 bar results in higher brake thermal efficiency. The higher injector opening pressure results in better atomization and peneatration of methyl ester of mahua oil. The exhaust emissions such as Smoke, unburnt hydro carbon and carbon monoxide of 200 bar is lower than other pressures.

  6. Motor-cognitive dual-task performance: effects of a concurrent motor task on distinct components of visual processing capacity

    OpenAIRE

    Künstler, E. C. S.; Finke, K.; Günther, A.; Klingner, C.; Witte, O.; Bublak, P.

    2017-01-01

    Dual tasking, or the simultaneous execution of two continuous tasks, is frequently associated with a performance decline that can be explained within a capacity sharing framework. In this study, we assessed the effects of a concurrent motor task on the efficiency of visual information uptake based on the ‘theory of visual attention’ (TVA). TVA provides parameter estimates reflecting distinct components of visual processing capacity: perceptual threshold, visual processing speed, and visual sh...

  7. Electrochemical characterisation speeds up prediction of corrosion behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Schuring, E.W.; Hooijmans, J.W. [ECN Environment and Energy Engineering, Petten (Netherlands)

    2013-04-15

    The contents of this presentation show the following elements: Introduction; Corrosion in real life; Why Electrochemical characterisation of corrosion; Applications (corrosion resistance coatings, corrosion behaviour (brazed) joints); Available electrochemical corrosion techniques; Standards; Conclusions. In the Conclusions the corrosion screening method is summarized: ECN method fast; within 1h -1 week results depending on test method; Fast pre-selection of promising materials/combinations (cost savings); Determining of corrosion initiation; Determination of corrosion mechanisms and propagation; Life time predictions possible; Strong combination with metallographic post-investigation; Ranking materials / constructions for corrosion performance.

  8. Multi-physics corrosion modeling for sustainability assessment of steel reinforced high performance fiber reinforced cementitious composites

    DEFF Research Database (Denmark)

    Lepech, M.; Michel, Alexander; Geiker, Mette

    2016-01-01

    and widespread depassivation, are the mechanism behind experimental results of HPFRCC steel corrosion studies found in the literature. Such results provide an indication of the fundamental mechanisms by which steel reinforced HPFRCC materials may be more durable than traditional reinforced concrete and other......Using a newly developed multi-physics transport, corrosion, and cracking model, which models these phenomena as a coupled physiochemical processes, the role of HPFRCC crack control and formation in regulating steel reinforcement corrosion is investigated. This model describes transport of water...... and chemical species, the electric potential distribution in the HPFRCC, the electrochemical propagation of steel corrosion, and the role of microcracks in the HPFRCC material. Numerical results show that the reduction in anode and cathode size on the reinforcing steel surface, due to multiple crack formation...

  9. Improving balance, mobility, and dual-task performance in an adolescent with cerebral palsy: A case report.

    Science.gov (United States)

    Fisher-Pipher, Sarah; Kenyon, Lisa K; Westman, Marci

    2017-07-01

    Improving functional mobility is often a desired outcome for adolescents with cerebral palsy (CP). Traditional neurorehabilitation approaches are frequently directed at impairments; however, improvements may not be carried over into functional mobility. The purpose of this case report was to describe the examination, intervention, and outcomes of a task-oriented physical therapy intervention program to improve dynamic balance, functional mobility, and dual-task performance in an adolescent with CP. The participant was a 15-year-old girl with spastic triplegic CP (Gross Motor Classification System Level II). Examination procedures included the Canadian Occupational Performance Measure, 6-minute walk test, Muscle Power Sprint Test, 10 x 5-meter sprint test, Timed Up and Down Stairs Test, Gross Motor Function Measure, Gillette Functional Assessment Questionnaire, and functional lower extremity strength tests. Intervention focused on task-oriented dynamic balance and mobility tasks that incorporated coordination and speed demands as well as task-specific lower extremity and trunk strengthening activities. Dual task demands were integrated into all intervention activities. Post-intervention testing revealed improvements in cardiovascular endurance, anaerobic power, agility, stair climbing, gross motor skills, and mobility. The participant appeared to benefit from a task-oriented program to improve dynamic balance, functional mobility, and dual-task performance.

  10. Investigation of field corrosion performance and bond/development length of galvanized reinforcing steel.

    Science.gov (United States)

    2014-12-01

    In reinforced concrete systems, ensuring that a good bond between the concrete and the embedded reinforcing steel is critical to : long-term structural performance. Without good bond between the two, the system simply cannot behave as intended. The b...

  11. Mobile evaporator corrosion test results

    International Nuclear Information System (INIS)

    Rozeveld, A.; Chamberlain, D.B.

    1997-05-01

    Laboratory corrosion tests were conducted on eight candidates to select a durable and cost-effective alloy for use in mobile evaporators to process radioactive waste solutions. Based on an extensive literature survey of corrosion data, three stainless steel alloys (304L, 316L, AL-6XN), four nickel-based alloys (825, 625, 690, G-30), and titanium were selected for testing. The corrosion tests included vapor phase, liquid junction (interface), liquid immersion, and crevice corrosion tests on plain and welded samples of candidate materials. Tests were conducted at 80 degrees C for 45 days in two different test solutions: a nitric acid solution. to simulate evaporator conditions during the processing of the cesium ion-exchange eluant and a highly alkaline sodium hydroxide solution to simulate the composition of Tank 241-AW-101 during evaporation. All of the alloys exhibited excellent corrosion resistance in the alkaline test solution. Corrosion rates were very low and localized corrosion was not observed. Results from the nitric acid tests showed that only 316L stainless steel did not meet our performance criteria. The 316L welded interface and crevice specimens had rates of 22.2 mpy and 21.8 mpy, respectively, which exceeds the maximum corrosion rate of 20 mpy. The other welded samples had about the same corrosion resistance as the plain samples. None of the welded samples showed preferential weld or heat-affected zone (HAZ) attack. Vapor corrosion was negligible for all alloys. All of the alloys except 316L exhibited either open-quotes satisfactoryclose quotes (2-20 mpy) or open-quotes excellentclose quotes (<2 mpy) corrosion resistance as defined by National Association of Corrosion Engineers. However, many of the alloys experienced intergranular corrosion in the nitric acid test solution, which could indicate a susceptibility to stress corrosion cracking (SCC) in this environment

  12. Corrosion Performance of AISI-309 Exposed to Molten Salts V2O5-Na2SO4 at 700°C Applying EIS and Rp Electrochemical Techniques

    Directory of Open Access Journals (Sweden)

    E. F. Diaz

    2015-01-01

    Full Text Available The corrosion performance of AISI-309 exposed 5 days to molten salts 50 mol% V2O5-50 mol% Na2SO4 at 700°C is reported in this paper. Such evaluation was made using three electrochemical techniques: potentiodynamic polarization curve (PC, electrochemical impedance spectroscopy (EIS, and linear polarization resistance (Rp. From PC, the Tafel slopes, Icorr, and Ecorr were obtained. From Nyquist and Bode plots, it was possible to determine two different stages; the first one showed just one loop, which indicated the initial formation of Cr2O3 layer over the metallic surface; after that, the dissolution of Cr2O3 formed a porous layer, which became part of the corrosion products; at the same time a NiO layer combined with sulfur was forming, which was suggested as the second stage, represented by two capacitive loops. EIS plots were in agreement with the physical characterization made from SEM and EDS analyses. Fitting of EIS experimental data allowed us to propose two electrical circuits, being in concordance with the corrosion stages. Parameters obtained from the simulation of EIS data are also reported. From the results, it was stated that AISI-309 suffered intergranular corrosion due to the presence of sulfur, which diffused to the metallic surface through a porous Cr2O3 layer.

  13. SYNTHESIS AND STUDY OF CORROSION PERFORMANCE OF EPOXY COATING CONTAINING MULTI-WALLED CARBON NANOTUBE/ POLY ORTHO AMINOPHENOL NANOCOMPOSITE

    Directory of Open Access Journals (Sweden)

    N. Bahrami Panah

    2016-03-01

    Full Text Available The epoxy coatings containing multi-walled carbon nanotube/ poly ortho aminophenol nanocomposite were prepared and used as anticorrosive coatings. The nanocomposites with different contents of carbon nanotube were synthesized in a solution of sodium dodecyl sulfate and ammonium peroxy disulfate as a surfactant and an oxidant, respectively. The morphology and structural properties were confirmed by Fourier transform infrared spectroscopy and scanning electron microscopy methods. The mean size of nanocomposite particles was 20-35 nm determined by scanning electron microscopy. The epoxy coatings containing the nanocomposites were applied over mild steel panels and their corrosion performance was investigated using electrochemical impedance spectroscopy and potentiodynamic polarization measurements in a 3.5 % sodium chloride solution. The results showed that epoxy coatings consisting of nanocomposite with 1 wt.% multi-walled carbon nanotube exhibited higher anticorrosive properties than other prepared coatings of different carbon nanotube contents, which could be due to the strong interaction between the mild steel surface and the conjugated nanocomposite.

  14. Semantic interference in picture naming during dual-task performance does not vary with reading ability

    NARCIS (Netherlands)

    Piai, V.; Roelofs, A.P.A.; Roete, I.E.C.

    2015-01-01

    Previous dual-task studies examining the locus of semantic interference of distractor words in picture naming have obtained diverging results. In these studies, participants manually responded to tones and named pictures while ignoring distractor words (picture-word interference, PWI) with varying

  15. Transverse tripolar spinal cord stimulation: theoretical performance of a dual channel system

    NARCIS (Netherlands)

    Struijk, J.J.; Struijk, J.J.; Holsheimer, J.

    1996-01-01

    A new approach to spinal cord stimulation is presented, by which several serious problems of conventional methods can be solved. A transverse tripolar electrode with a dual-channel voltage stimulator is evaluated theoretically by means of a volume conductor model, combined with nerve fibre models.

  16. Performance Enhancement in L-Band Edfa Through Dual Stage Technique

    Directory of Open Access Journals (Sweden)

    S. W. Harun and H. Ahmad

    2012-10-01

    Full Text Available An experiment on gain enhancement in the long wavelength band erbium doped fiber amplifier (L-band EDFA is demonstrated. It uses a dual stage technique with dual forward pumping scheme. Compared to a conventional single stage amplifier, the small signal gain for 1580nm signal can be improved by 5.5dB without paying much noise figure penalty. The corresponding noise figure penalty was 0.3dB due to the insertion loss of the optical isolator. The optimum pump power ratio for the first pump is experimentally determined to be 33%. The maximum gain improvement of 8.3dB was obtained at a signal wavelength of 1568nm while signal and total pump powers were fixed at -30dBm and 92mW, respectively. The employment of dual stage amplifier system seems to play an important role in the development of practical L-band EDFA from the perspective of economical usage of pump power.Key Words:  erbium doped fibre; optical amplifier; L-band EDFA; dual stage EDFA; amplified spontaneous emission

  17. Emission and operating performance of a biomethane tractor with dual fuel engine

    International Nuclear Information System (INIS)

    Mautner, Sebastian; Emberger, Peter; Thuneke, Klaus; Remmele, Edgar

    2016-01-01

    The use of biomethane as fuel for agricultural machinery with dual fuel technology is contributing to climate protection and ensures safe fuel supply. So far, hardly any documented operational experiences are known. The aim of the project, funded by the Bavarian Ministry of Economic Affairs and Media, Energy and Technology, was to investigate practicability for daily use and the emission behaviour of a Valtra N101 prototype tractor (exhaust stage IIIA). The retrofitted dual-fuel technology of the former conventional diesel tractor simultaneously uses biomethane or natural gas and diesel as ignition fuel. During the field test over 590 working hours, the tractor showed overall high reliability. On average the operating range in dual-fuel mode with one complete filling of the gas tanks was about 11.5 hours. On the tractor test bench a significant improvement of the exhaust emissions could be observed, since the gas ECU had been optimized and changed by the manufacturer. For dual-fuel operation, nitrogen oxides (NO x ) are lower, whereas carbon monoxide (CO), hydrocarbons (HC) and particulate matter emissions (PM) are higher compared to solely diesel operation. In particular, HC emissions exceed the proposed limiting value, submitted by the European Commission. This is due to incomplete gas combustion and insufficient conversion by the exhaust after-treatment-system (methane slip). A big potential for optimization is expected by adjusting the operating point-specific gasdiesel ratio and improving the exhaust gas aftertreatment system.

  18. Structural Support of High-Performance Athletes' Education: Supporting Dual Careers in Greece

    Science.gov (United States)

    Pavlidis, George; Gargalianos, Dimitris

    2014-01-01

    This article describes how the current Greek sport-education context seems to offer relatively poor dual-career support in comparison to other available structures in the world. This results in additional obstacles for Greek athletes who wish to educate themselves and an ambiguous prospect for their future. Consequently, the Greek…

  19. Can Dual Processing Theory Explain Physics Students' Performance on the Force Concept Inventory?

    Science.gov (United States)

    Wood, Anna K.; Galloway, Ross K.; Hardy, Judy

    2016-01-01

    According to dual processing theory there are two types, or modes, of thinking: system 1, which involves intuitive and nonreflective thinking, and system 2, which is more deliberate and requires conscious effort and thought. The Cognitive Reflection Test (CRT) is a widely used and robust three item instrument that measures the tendency to override…

  20. Corrosion Engineering.

    Science.gov (United States)

    White, Charles V.

    A description is provided for a Corrosion and Corrosion Control course offered in the Continuing Engineering Education Program at the General Motors Institute (GMI). GMI is a small cooperative engineering school of approximately 2,000 students who alternate between six-week periods of academic study and six weeks of related work experience in…

  1. Adhesive Bonding and Corrosion Performance Investigated as a Function of Aluminum Oxide Chemistry and Adhesives

    NARCIS (Netherlands)

    Abrahami, S.T.; Hauffman, T.; de Kok, John M.M.; Terryn, H.A.; Mol, J.M.C.

    2017-01-01

    The long-term strength and durability of an adhesive bond is dependent on the stability of the oxide-adhesive interface. As such, changes in the chemistry of the oxide and/or the adhesive are expected to modify the interfacial properties and affect the joint performance in practice. The upcoming

  2. Dual material gate doping-less tunnel FET with hetero gate dielectric for enhancement of analog/RF performance

    Science.gov (United States)

    Anand, Sunny; Sarin, R. K.

    2017-02-01

    In this paper, charge-plasma-based tunnel FET is proposed by employing dual material gate with hetero gate dielectric technique and it is named hetero-dielectric dual material gate doping-less TFET (HD_DMG_DLTFET). It is compared with conventional doping-less TFET (DLTFET) and dual material gate doping-less TFET (DMG_DLTFET) on the basis of analog and RF performance. The HD_DMG_DLTFET provides better ON state current ({I}\\text{ON}=94 μ \\text{A}/μ \\text{m}), {I}\\text{ON}/{I}\\text{OFF}(≈ 1.36× {10}13), \\text{point} (≈ 3\\text{mV}/\\text{dec}) and average subthreshold slope (\\text{AV}-\\text{SS}=40.40 \\text{mV}/\\text{dec}). The proposed device offers low total gate capacitance (C gg) along with higher drive current. However, with a better transconductance (g m) and cut-off frequency (f T), the HD_DMG_DLTFET can be a good candidate for RF circuitry. The early voltage (V EA) and output conductance (g d) are also moderate for the proposed device with comparison to other devices and therefore can be a candidate for analog devices. From all these simulation results and their study, it is observed that HD_DMG_DLTFET has improved analog/RF performance compared to DLTFET and DMG_DLTFET.

  3. Corrosion of fuel assembly materials

    International Nuclear Information System (INIS)

    Noe, M.; Frejaville, G.; Beslu, P.

    1985-08-01

    Corrosion of zircaloy-4 is reviewed in relation with previsions of improvement in PWRs performance: higher fuel burnup; increase coolant temperature, implying nucleate boiling on the hot clad surfaces; increase duration of the cycle due to load-follow operation. Actual knowledge on corrosion rates, based partly on laboratory tests, is insufficient to insure that external clad corrosion will not constitute a limitation to these improvements. Therefore, additional testing within representative conditions is felt necessary [fr

  4. Accelerated Test Method for Corrosion Protective Coatings

    Data.gov (United States)

    National Aeronautics and Space Administration — This project seeks to develop a new accelerated corrosion test method that predicts the long-term corrosion protection performance of spaceport structure coatings as...

  5. An experimental assessment on the influence of high octane fuels on biofuel based dual fuel engine performance, emission, and combustion

    Directory of Open Access Journals (Sweden)

    Masimalai Senthilkumar

    2017-01-01

    Full Text Available This paper presents an experimental study on the effect of different high octane fuels (such as eucalyptus oil, ethanol, and methanol on engine’s performance behaviour of a biofuel based dual fuel engine. A single cylinder Diesel engine was modified and tested under dual fuel mode of operation. Initially the engine was run using neat diesel, neat mahua oil as fuels. In the second phase, the engine was operated in dual fuel mode by using a specially designed variable jet carburettor to supply the high octane fuels. Engine trials were made at 100% and 40% loads (power outputs with varying amounts of high octane fuels up-to the maximum possible limit. The performance and emission characteristics of the engine were obtained and analysed. Results indicated significant improvement in brake thermal efficiency simultaneous reduction in smoke and NO emissions in dual fuel operation with all the inducted fuels. At 100% load the brake thermal efficiency increased from 25.6% to a maximum of 32.3, 30.5, and 28.4%, respectively, with eucalyptus oil, ethanol, and methanol as primary fuels. Smoke was reduced drastically from 78% with neat mahua oil a minimum of 41, 48, and 53%, respectively, with eucalyptus oil, ethanol, and methanol at the maximum efficiency point. The optimal energy share for the best engine behaviour was found to be 44.6, 27.3, and 23.2%, respectively, for eucalyptus oil, ethanol, and methanol at 100% load. Among the primary fuels tested, eucalyptus oil showed the maximum brake thermal efficiency, minimum smoke and NO emissions and maximum energy replacement for the optimal operation of the engine.

  6. Performance and emissions of a dual-fuel pilot diesel ignition engine operating on various premixed fuels

    International Nuclear Information System (INIS)

    Yousefi, Amin; Birouk, Madjid; Lawler, Benjamin; Gharehghani, Ayatallah

    2015-01-01

    Highlights: • Natural gas/diesel, methanol/diesel, and hydrogen/diesel cases were investigated. • For leaner mixtures, the hydrogen/diesel case has the highest IMEP and ITE. • The methanol/diesel case has the maximum IMEP and ITE for richer mixtures. • Hydrogen/diesel case experiences soot and CO free combustion at rich regions. - Abstract: A multi-dimensional computational fluid dynamics (CFD) model coupled with chemical kinetics mechanisms was applied to investigate the effect of various premixed fuels and equivalence ratios on the combustion, performance, and emissions characteristics of a dual-fuel indirect injection (IDI) pilot diesel ignition engine. The diesel fuel is supplied via indirect injection into the cylinder prior to the end of the compression stroke. Various premixed fuels were inducted into the engine through the intake manifold. The results showed that the dual-fuel case using hydrogen/diesel has a steeper pressure rise rate, higher peak heat release rate (PHRR), more advanced ignition timing, and shorter ignition delay compared to the natural gas/diesel and methanol/diesel dual-fuel cases. For leaner mixtures (Φ_P 0.32). For instance, with an equivalence ratio of 0.35, the ITE is 56.24% and 60.85% for hydrogen/diesel and methanol/diesel dual-fuel cases, respectively. For an equivalence ratio of 0.15, the natural gas/diesel simulation exhibits partial burn combustion and thus results in a negative IMEP. At equivalence ratios of 0.15, 0.2, and 0.25, the methanol/diesel case experiences misfiring phenomenon which consequently deteriorates the engine performance considerably. As for the engine-out emissions, the hydrogen/diesel results display carbon monoxide (CO) free combustion relative to natural gas/diesel and methanol/diesel engines; however, considerable amount of nitrogen oxides (NO_x) emissions are produced at an equivalence ratio of 0.35 which exceeds the Euro 6 NO_x limit. Due to the larger area exposed to high temperature regions

  7. The photoelectrocatalytic activity, long term stability and corrosion performance of NiMo deposited titanium oxide nano-tubes for hydrogen production in alkaline medium

    Science.gov (United States)

    Mert, Mehmet Erman; Mert, Başak Doğru; Kardaş, Gülfeza; Yazıcı, Birgül

    2017-11-01

    In this study, titanium oxide nano-tubes are doped with Ni and Mo particles with various chemical compositions, in order to put forth the efficiency of single and binary coatings on hydrogen evolution reaction (HER) in 1 M KOH. The characterization was achieved by cyclic voltammetry, scanning electron microscopy and energy dispersive X-ray analysis. The water wettability characteristics of electrode surfaces were investigated using contact angle. The long-term catalyst stability and corrosion performance were determined by current-potential curves and electrochemical impedance spectroscopy. Furthermore, photoelectrochemical behavior was determined via linear sweep voltammetry. Results showed that, nano-structured Ni and Mo deposited titanium oxide nano-tubes decrease the hydrogen over potential and increase HER efficiency, it is stable over 168 h electrolysis and it exhibits higher corrosion performance.

  8. Zircaloy-4 corrosion in PWR's

    International Nuclear Information System (INIS)

    Fyfitch, S.; Smalley, W.R.; Roberts, E.

    1985-01-01

    Zircaloy-4 waterside corrosion has been studied extensively in the nuclear industry for a number of years. Following the early crud-related corrosion failures in the Saxton test reactor, Westinghouse undertook numerous programs to minimize crud deposition on fuel rods in power reactors through primary coolant chemistry control. Modern plants today are operating with improved coolant chemistry guidelines, and crud deposition levels are very low in proportion to earlier experience. Zircaloy-4 corrosion under a variety of coolant chemistry, heat flux and exposure conditions has been studied extensively. Experience to date, even in relatively high coolant temperature plants, has indicated that -for both fuel cladding and structural components- Zircaloy-4 waterside corrosion performance has been excellent. Recognizing future industry trends, however, which will result in Zircaloy-4 being subjected to ever increasing corrosion duties, Westinghouse will continue accumulating Zircaloy-4 corrosion experience in large power plants. 13 refs.

  9. Performance of turbo high-pitch dual-source CT for coronary CT angiography: first ex vivo and patient experience

    Energy Technology Data Exchange (ETDEWEB)

    Morsbach, Fabian; Gordic, Sonja; Husarik, Daniela; Frauenfelder, Thomas; Alkadhi, Hatem [University Hospital Zurich, Institute of Diagnostic and Interventional Radiology, Zurich (Switzerland); Desbiolles, Lotus; Leschka, Sebastian [University Hospital Zurich, Institute of Diagnostic and Interventional Radiology, Zurich (Switzerland); Kantonsspital St. Gallen, Divison of Radiology and Nuclear Medicine, St. Gallen (Switzerland); Schmidt, Bernhard; Allmendinger, Thomas [Siemens AG, Healthcare Sector, Forchheim (Germany); Wildermuth, Simon [Kantonsspital St. Gallen, Divison of Radiology and Nuclear Medicine, St. Gallen (Switzerland)

    2014-08-15

    To evaluate image quality, maximal heart rate allowing for diagnostic imaging, and radiation dose of turbo high-pitch dual-source coronary computed tomographic angiography (CCTA). First, a cardiac motion phantom simulating heart rates (HRs) from 60-90 bpm in 5-bpm steps was examined on a third-generation dual-source 192-slice CT (prospective ECG-triggering, pitch 3.2; rotation time, 250 ms). Subjective image quality regarding the presence of motion artefacts was interpreted by two readers on a four-point scale (1, excellent; 4, non-diagnostic). Objective image quality was assessed by calculating distortion vectors. Thereafter, 20 consecutive patients (median, 50 years) undergoing clinically indicated CCTA were included. In the phantom study, image quality was rated diagnostic up to the HR75 bpm, with object distortion being 1 mm or less. Distortion increased above 1 mm at HR of 80-90 bpm. Patients had a mean HR of 66 bpm (47-78 bpm). Coronary segments were of diagnostic image quality for all patients with HR up to 73 bpm. Average effective radiation dose in patients was 0.6 ± 0.3 mSv. Our combined phantom and patient study indicates that CCTA with turbo high-pitch third-generation dual-source 192-slice CT can be performed at HR up to 75 bpm while maintaining diagnostic image quality, being associated with an average radiation dose of 0.6 mSv. (orig.)

  10. PERFORMANCE, EMISSION, AND COMBUSTION CHARACTERISTICS OF A CI ENGINE USING LIQUID PETROLEUM GAS AND NEEM OIL IN DUAL FUEL MODE

    Directory of Open Access Journals (Sweden)

    Palanimuthu Vijayabalan

    2010-01-01

    Full Text Available Increased environmental awareness and depletion of resources are driving the industries to develop viable alternative fuels like vegetable oils, compresed natural gas, liquid petroleum gas, producer gas, and biogas in order to provide suitable substitute to diesel for compression ignition engine. In this investigation, a single cylinder, vertical, air-cooled diesel engine was modified to use liquid petroleum gas in dual fuel mode. The liquefied petroleum gas, was mixed with air and supplied through intake manifold. The liquid fuel neem oil or diesel was injected into the combustion chamber. The performance, emission, and combustion characteristics were studied and compared for neat fuel and dual fuel mode. The experimental results on dual fuel engine show a reduction in oxides of nitrogen up to 70% of the rated power and smoke in the entire power range. However the brake thermal efficiency was found decreased in low power range due to lower calorific value of liquid petroleum gas, and increase in higher power range due to the complete burning of liquid petroleum gas. Hydrocarbon and carbon monoxide emissions were increased significantly at lower power range and marginal variation in higher power range.

  11. Performance of turbo high-pitch dual-source CT for coronary CT angiography: first ex vivo and patient experience

    International Nuclear Information System (INIS)

    Morsbach, Fabian; Gordic, Sonja; Husarik, Daniela; Frauenfelder, Thomas; Alkadhi, Hatem; Desbiolles, Lotus; Leschka, Sebastian; Schmidt, Bernhard; Allmendinger, Thomas; Wildermuth, Simon

    2014-01-01

    To evaluate image quality, maximal heart rate allowing for diagnostic imaging, and radiation dose of turbo high-pitch dual-source coronary computed tomographic angiography (CCTA). First, a cardiac motion phantom simulating heart rates (HRs) from 60-90 bpm in 5-bpm steps was examined on a third-generation dual-source 192-slice CT (prospective ECG-triggering, pitch 3.2; rotation time, 250 ms). Subjective image quality regarding the presence of motion artefacts was interpreted by two readers on a four-point scale (1, excellent; 4, non-diagnostic). Objective image quality was assessed by calculating distortion vectors. Thereafter, 20 consecutive patients (median, 50 years) undergoing clinically indicated CCTA were included. In the phantom study, image quality was rated diagnostic up to the HR75 bpm, with object distortion being 1 mm or less. Distortion increased above 1 mm at HR of 80-90 bpm. Patients had a mean HR of 66 bpm (47-78 bpm). Coronary segments were of diagnostic image quality for all patients with HR up to 73 bpm. Average effective radiation dose in patients was 0.6 ± 0.3 mSv. Our combined phantom and patient study indicates that CCTA with turbo high-pitch third-generation dual-source 192-slice CT can be performed at HR up to 75 bpm while maintaining diagnostic image quality, being associated with an average radiation dose of 0.6 mSv. (orig.)

  12. Design, modeling and performance analysis of dual channel semitransparent photovoltaic thermal hybrid module in the cold environment

    International Nuclear Information System (INIS)

    Singh, Sonveer; Agrawal, Sanjay; Avasthi, D.V.

    2016-01-01

    Highlights: • Thermal modeling of novel dual channel semitransparent PVT hybrid module. • Exergy and carbon credit analysis has been performed. • Annual performance has been evaluated for Srinagar (India). • There are improvements in results for case-I as compared to case-II. - Abstract: In this work, thermal modeling and performance analysis of the dual channel semitransparent photovoltaic thermal (DCSPVT) module has been carried out. For extracting heat associated with the lower and upper surface of the solar cell, two channels have been proposed; (i) one is above the solar cell called upper channel and (ii) second is below the solar cell called lower channel. Firstly, thermal modeling of DCSPVT module has been developed. After that, performance analysis of the above system has been carried out for Srinagar, Indian climatic condition. Performance in terms of electrical gain (EG), thermal gain (TG), overall exergy gain (OEG), overall thermal gain (OTG), electrical efficiency (EE) and overall exergy efficiency (OEE) of the DCSPVT module (case-I) have been compared with single channel semitransparent photovoltaic thermal (SCSPVT) hybrid module (case-II). The average improvement in EG, TG, OEG, OTG of the case-I have been observed by 71.51%, 34.57%, 5.78% and 35.41% respectively as compared to case-II.

  13. Performance Study of Dual Fuel Engine Using Producer Gas as Secondary Fuel

    Directory of Open Access Journals (Sweden)

    Deepika Shaw

    2016-06-01

    Full Text Available In the present paper, development of producer gas fuelled 4 stroke diesel engine has been investigated. Producer gas from biomass has been examined and successfully operated with 4 stroke diesel engine. The effects of higher and lower loads were investigated on the dual fuel mode. The experimental investigations revealed that at lower loads dual fuel operation with producer gas shows lower efficiency due to lower combustion rate cause by low calorific value of the producer gas. Beyond 40% load the brake thermal efficiency of dual fuel operation improved due to faster combustion rate of producer gas and higher level of premixing. It can be observed that at lower load and 20% opening of producer gas the gaseous fuel substitution found to be 56% whereas at 100% opening of producer gas it reaches 78% substitution. The CO2 emission increased at high producer gas opening and high load because at 100% producer gas maximum atoms of carbons were there and at high load condition the diesel use increased. At 80% load and producer gas varying from 20% to 100. Power output was almost comparable to diesel power with marginal higher efficiency. Producer gas is one such technology which is environmentally benign and holds large promise for future.

  14. Impact of Cyclic Loading on Chloride Diffusivity and Mechanical Performance of RC Beams under Seawater Corrosion

    Directory of Open Access Journals (Sweden)

    Sen Pang

    2017-01-01

    Full Text Available An experimental study was conducted to investigate the impact of cyclic loading on the mechanical performance and chloride diffusivity of RC beams exposed to seawater wet-dry cycles. To induce initial damage to RC beam specimen, cyclic loading controlled by max load and cycles was applied. Then beam specimens underwent 240 wet-dry cycles of seawater. Results show that the chloride content increased as max load and cycle increased. The chloride content at steel surface increased approximatively linearly as average crack width increased. Moreover, the max load had more influence on chloride content at steel surface than cycle. The difference of average chloride diffusion coefficient between tension and compression concrete was little at uncracked position. Average chloride diffusion coefficient increased as crack width increased when crack width was less than 0.11 mm whereas the increasing tendency was weak when crack width exceeded 0.11 mm. The residual yield load and ultimate load of RC beams decreased as max load and cycle increased. Based on univariate analysis of variance, the max load had more adverse effect on yield load and ultimate load than cycle.

  15. A review of ionic liquid surface film formation on Mg and its alloys for improved corrosion performance

    International Nuclear Information System (INIS)

    Huang, Peipei; Latham, Julie-Anne; MacFarlane, Douglas R.; Howlett, Patrick C.; Forsyth, Maria

    2013-01-01

    Magnesium and its alloys are prone to corrosion upon exposure to atmosphere thus are usually protected by using a pretreatment before being employed. The use of ionic liquids (ILs) has emerged as a novel chemical in corrosion protection of reactive metals such as lithium and magnesium. This paper reviews the use of ILs in the corrosion protection of magnesium and aluminium with respect to a range of IL chemistries. Emphasis has also been placed on characterisation of the passivating films using various techniques, as well as proposed mechanisms for film formation. This review highlights that there is still much research needed to understand how to generate robust passivating films on reactive metal surfaces in the presence of ILs

  16. Age and education influence the performance of elderly women on the dual-task Timed Up and Go test

    Directory of Open Access Journals (Sweden)

    Gisele de Cássia Gomes

    2015-03-01

    Full Text Available Gait variability is related to functional decline in the elderly. The dual-task Timed Up and Go Test (TUG-DT reflects the performance in daily activities. Objective To evaluate the differences in time to perform the TUG with and without DT in elderly women with different ages and levels of education and physical activity. Method Ninety-two elderly women perfomed the TUG at usual and fast speeds, with and without motor and cognitive DT. Results Increases in the time to perform the TUG-DT were observed at older ages and lower educational levels, but not at different levels of physical activity. More educated women performed the test faster with and without DT at both speeds. When age was considered, significant differences were found only for the TUG-DT at both speeds. Conclusion Younger women with higher education levels demonstrated better performances on the TUG-DT.

  17. Performance and exhaust emissions in a natural-gas fueled dual-fuel engine; Tennen gas dual fuel kikan no seino oyobi haiki tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Shioji, M.; Ishiyama, T.; Shibata, H. [Kyoto Univ., Kyoto (Japan). Inst. of Atomic Energy; Ikegami, M. [Fukui Institute of Technology, Fukui (Japan). Faculty of Engineering

    2000-07-25

    In order to establish the optimum fueling in a natural gas fueled dual fuel engine, tests were made for some operational parameters and their combination on the engine performances and the exhaust emissions. The results show that the gas oil quantity should be increased and gas oil injection timing should be advanced to suppress unburned hydrocarbon emission at middle and low output range, while the quantity should be reduced and the timing should be retarded to avoid onset of knock at high loads. The unburned hydrocarbon emission and the thermal efficiency are improved at the same load avoiding too lean natural gas premixture by restriction of intake charge air. However the improvement is limited because the ignition and initial combustion of pilot diesel fuel is deteriorated when the cylinder pressure is excessively lowered by throttling. The increase in pilot gas oil amount is effective for low-load operation and the adequate combination of throttle control and equivalence ratio ensures low hydrocarbon emission and the thermal efficiency comparable to diesel operation. (author)

  18. Dual Youla parameterization

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik

    2003-01-01

    A different aspect of using the parameterisation of all systems stabilised by a given controller, i.e. the dual Youla parameterisation, is considered. The relation between system change and the dual Youla parameter is derived in explicit form. A number of standard uncertain model descriptions...... are considered and the relation with the dual Youla parameter given. Some applications of the dual Youla parameterisation are considered in connection with the design of controllers and model/performance validation....

  19. Effect of compression ratio on performance, combustion and emission characteristics of a dual fuel diesel engine run on raw biogas

    International Nuclear Information System (INIS)

    Bora, Bhaskor J.; Saha, Ujjwal K.; Chatterjee, Soumya; Veer, Vijay

    2014-01-01

    Highlights: • Maximum brake thermal efficiency of 20.04% was obtained in dual fuel mode. • Compression ratio of 18 produced the maximum brake thermal efficiency. • Maximum replacement of diesel was found to be 79.46% at a compression ratio of 18. • CO gets reduced by 26.22% with the increase of compression ratio from 16 to18. • HC gets reduced by 41.97% with the increase of compression ratio from 16 to18. - Abstract: The energy consumption of the world is increasing at a staggering rate due to population explosion. The extensive use of energy has led to fossil fuel depletion and the rise in pollution. Renewable energy holds the key solution to these aforementioned problems. Biogas, one such renewable fuel, can be used in a diesel engine under dual fuel mode for the generation of power. This work attempts to unfold the effect of compression ratio on the performance, combustion and emission characteristics of a dual fuel diesel engine run on raw biogas. For this investigation, a 3.5 kW single cylinder, direct injection, water cooled, variable compression ratio diesel engine is converted into a biogas run dual fuel diesel engine by connecting a venturi gas mixer at the inlet manifold. Experiments have been conducted at various compression ratios (18, 17.5, 17 and 16) and under different loading conditions fixing the standard injection timing at 23° before top dead centre. At 100% load, the brake thermal efficiencies of the dual fuel mode are found to be 20.04%, 18.25%, 17.07% and 16.42% at compression ratios of 18, 17.5, 17 and 16, respectively, whereas at the same load, the diesel mode shows an efficiency of 27.76% at a compression ratio of 17.5. The maximum replacement of the precious fossil fuel is found to be 79.46%, 76.1%, 74% and 72% at compression ratios of 18, 17.5, 17 and 16, respectively at 100% load. For the dual fuel mode, on an average, there is a reduction in carbon monoxide as well as hydrocarbon emission by 26.22% and 41.97% when compression

  20. Corrosion '98: 53. annual conference and exposition, proceedings

    International Nuclear Information System (INIS)

    Anon.

    1998-01-01

    This conference was divided into the following sections: Corrosion in Gas Treating; Problems and Solutions in Commercial Building Water Systems; Green Corrosion/Scale Inhibitors; Atmospheric Corrosion; AIRPOL Update/98; Rubber Lining--Answers to Many Problems; Interference Problems; Environmental Assisted Cracking: Fundamental Research and Industrial Applications; Corrosion in Nuclear Systems; New Developments in Scale and Deposit Control; Corrosion and Corrosion Protection in the Transportation Industries; What's All the Noise About--Electrochemical That Is; Refining Industry Corrosion; Corrosion Problems in Military Hardware: Case Histories, Fixes and Lessons Learned; Cathodic Protection Test Methods and Instrumentation for Underground and On-grade Pipelines and Tanks; Recent Developments in Volatile Corrosion Inhibitors; Corrosion in Supercritical Fluids; Microbiologically Influenced Corrosion; Advances in Understanding and Controlling CO 2 Corrosion; Managing Corrosion with Plastics; Material Developments for Use in Exploration and Production Environments; Corrosion in Cold Regions; The Effect of Downsizing and Outsourcing on Cooling System Monitoring and Control Practices; New Developments in Mechanical and Chemical Industrial Cleaning; Mineral Scale Deposit Control in Oilfield Related Operations; Biocides in Cooling Water; Corrosion and Corrosion Control of Reinforced Concrete Structures; Materials Performance for Fossil Energy Conversion Systems; Marine corrosion; Thermal Spray--Coating and Corrosion Control; Flow Effects on Corrosion in Oil and Gas Production; Corrosion Measurement Technologies; Internal Pipeline Monitoring--Corrosion Monitoring, Intelligent Pigging and Leak Detection; Cathodic Protection in Natural Waters; Corrosion in Radioactive Liquid Waste Systems; On-line Hydrogen Permeation Monitoring Equipment and Techniques, State of the Art; Water Reuse and Recovery; Performance of Materials in High Temperature Environments; Advances in Motor

  1. Stress corrosion cracking of austenitic stainless steels in PWR primary water: an update of metallurgical investigations performed on French withdrawn components

    International Nuclear Information System (INIS)

    Boursier, J.M.; Gallet, S.; Rouillon, Y.; Bordes, P.

    2002-01-01

    Austenitic stainless steels (AISI 304, 304L, 316 and 316L) are largely used in Nuclear Power Plants because of their good resistance to corrosion and their satisfactory mechanical properties. Nevertheless, on various French PWR Nuclear Power Plants, several cases of corrosion have been encountered in auxiliary circuit portions where deleterious species and oxygen can be present. This paper focuses on the metallurgical investigations performed on pulled out components such as Canopy welds or 'dead legs' (auxiliary circuit portions connected to the main primary loops) in terms of cracking locations and degradation parameters. In addition, some comparisons between Nuclear Power Plant feedback and fundamental research and development studies are discussed, particularly in the scope of temperature, microstructure, stresses (applied and residual) and medium responsible for the degradation. (authors)

  2. The effect of cerium-based conversion treatment on the cathodic delamination and corrosion protection performance of carbon steel-fusion-bonded epoxy coating systems

    Energy Technology Data Exchange (ETDEWEB)

    Ramezanzadeh, B., E-mail: ramezanzadeh@aut.ac.ir [Department of Surface Coatings and Corrosion, Institute for Color Science and Technology (ICST), 16765-654, Tehran (Iran, Islamic Republic of); Rostami, M. [Department of Nanomaterials and Nanocoatings, Institute for Color Science and Technology (ICST), 16765-654, Tehran (Iran, Islamic Republic of)

    2017-01-15

    Highlights: • Steel surface was treated by Ce and acid phosphoric solutions. • Ce treatment considerably enhanced the surface energy and produce nanoscale roughness. • Ce treated samples showed enhanced adhesion to FBE coating. • Ce treatment of steel significantly reduced the FBE cathodic delamination rate. • Ce treated sample showed enhanced corrosion resistance. - Abstract: The effect of surface pre-treatment of pipe surface by green cerium compound and phosphoric acid solution on the fusion-bonded epoxy (FBE) coating performance was studied. The composition and surface morphology of the steel samples treated by acid and Ce solutions were characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), equipped with energy dispersive spectroscopy (EDS). Also, the surface free energy was evaluated on these samples through contact angle measurements. In addition, the effect of Ce and acid washing procedures on the adhesion properties and corrosion protection performance of the FBE was examined by pull-off, salt spray and electrochemical impedance spectroscopy (EIS) tests. Results showed that compared to acid washing, the chemical treatment by Ce solution noticeably increased the surface free energy of steel, improved the adhesion properties of FBE, decreased the cathodic delamination rate of FBE, and enhanced the coating corrosion resistance compared to the acid washed samples.

  3. General Corrosion and Localized Corrosion of Waste Package Outer Barrier

    Energy Technology Data Exchange (ETDEWEB)

    K.G. Mon

    2004-10-01

    The waste package design for the License Application is a double-wall waste package underneath a protective drip shield (BSC 2004 [DIRS 168489]; BSC 2004 [DIRS 169480]). The purpose and scope of this model report is to document models for general and localized corrosion of the waste package outer barrier (WPOB) to be used in evaluating waste package performance. The WPOB is constructed of Alloy 22 (UNS N06022), a highly corrosion-resistant nickel-based alloy. The inner vessel of the waste package is constructed of Stainless Steel Type 316 (UNS S31600). Before it fails, the Alloy 22 WPOB protects the Stainless Steel Type 316 inner vessel from exposure to the external environment and any significant degradation. The Stainless Steel Type 316 inner vessel provides structural stability to the thinner Alloy 22 WPOB. Although the waste package inner vessel would also provide some performance for waste containment and potentially decrease the rate of radionuclide transport after WPOB breach before it fails, the potential performance of the inner vessel is far less than that of the more corrosion-resistant Alloy 22 WPOB. For this reason, the corrosion performance of the waste package inner vessel is conservatively ignored in this report and the total system performance assessment for the license application (TSPA-LA). Treatment of seismic and igneous events and their consequences on waste package outer barrier performance are not specifically discussed in this report, although the general and localized corrosion models developed in this report are suitable for use in these scenarios. The localized corrosion processes considered in this report are pitting corrosion and crevice corrosion. Stress corrosion cracking is discussed in ''Stress Corrosion Cracking of the Drip Shield, the Waste Package Outer Barrier, and the Stainless Steel Structural Material'' (BSC 2004 [DIRS 169985]).

  4. Performance analysis of waste heat recovery with a dual loop organic Rankine cycle (ORC) system for diesel engine under various operating conditions

    International Nuclear Information System (INIS)

    Yang, Fubin; Dong, Xiaorui; Zhang, Hongguang; Wang, Zhen; Yang, Kai; Zhang, Jian; Wang, Enhua; Liu, Hao; Zhao, Guangyao

    2014-01-01

    Highlights: • Dual loop ORC system is designed to recover waste heat from a diesel engine. • R245fa is used as working fluid for the dual loop ORC system. • Waste heat characteristic under engine various operating conditions is analyzed. • Performance of the combined system under various operating conditions is studied. • The waste heat from coolant and intake air has considerable potential for recovery. - Abstract: To take full advantage of the waste heat from a diesel engine, a set of dual loop organic Rankine cycle (ORC) system is designed to recover exhaust energy, waste heat from the coolant system, and released heat from turbocharged air in the intercooler of a six-cylinder diesel engine. The dual loop ORC system consists of a high temperature loop ORC system and a low temperature loop ORC system. R245fa is selected as the working fluid for both loops. Through the engine test, based on the first and second laws of thermodynamics, the performance of the dual loop ORC system for waste heat recovery is discussed based on the analysis of its waste heat characteristics under engine various operating conditions. Subsequently, the diesel engine-dual loop ORC combined system is presented, and the effective thermal efficiency and the brake specific fuel consumption (BSFC) are chosen to evaluate the operating performances of the diesel engine-dual loop ORC combined system. The results show that, the maximum waste heat recovery efficiency (WHRE) of the dual loop ORC system can reach 5.4% under engine various operating conditions. At the engine rated condition, the dual loop ORC system achieves the largest net power output at 27.85 kW. Compared with the diesel engine, the thermal efficiency of the combined system can be increased by 13%. When the diesel engine is operating at the high load region, the BSFC can be reduced by a maximum 4%

  5. Performance enhancement of polymer electrolyte membrane fuel cells by dual-layered membrane electrode assembly structures with carbon nanotubes.

    Science.gov (United States)

    Jung, Dong-Won; Kim, Jun-Ho; Kim, Se-Hoon; Kim, Jun-Bom; Oh, Eun-Suok

    2013-05-01

    The effect of dual-layered membrane electrode assemblies (d-MEAs) on the performance of a polymer electrolyte membrane fuel cell (PEMFC) was investigated using the following characterization techniques: single cell performance test, electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). It has been shown that the PEMFC with d-MEAs has better cell performance than that with typical mono-layered MEAs (m-MEAs). In particular, the d-MEA whose inner layer is composed of multi-walled carbon nanotubes (MWCNTs) showed the best fuel cell performance. This is due to the fact that the d-MEAs with MWCNTs have the highest electrochemical surface area and the lowest activation polarization, as observed from the CV and EIS test.

  6. Fatigue does not conjointly alter postural and cognitive performance when standing in a shooting position under dual-task conditions.

    Science.gov (United States)

    Bermejo, José Luis; García-Massó, Xavier; Paillard, Thierry; Noé, Frédéric

    2018-02-01

    This study investigated the effects of fatigue on balance control and cognitive performance in a standing shooting position. Nineteen soldiers were asked to stand while holding a rifle (single task - ST). They also had to perform this postural task while simultaneously completing a cognitive task (dual task - DT). Both the ST and DT were performed in pre- and post-fatigue conditions. In pre-fatigue, participants achieved better balance control in the DT than in the ST, thus suggesting that the increased cognitive activity associated with the DT improves balance control by shifting the attentional focus away from a highly automatised activity. In post-fatigue, balance control was degraded in both the ST and DT, while reaction time was enhanced in the first minutes following the fatiguing exercise without affecting the accuracy of response in the cognitive task, which highlights the relative independent effects of fatigue on balance control and cognitive performance.

  7. Effects of Cavity on the Performance of Dual Throat Nozzle During the Thrust-Vectoring Starting Transient Process.

    Science.gov (United States)

    Gu, Rui; Xu, Jinglei

    2014-01-01

    The dual throat nozzle (DTN) technique is capable to achieve higher thrust-vectoring efficiencies than other fluidic techniques, without compromising thrust efficiency significantly during vectoring operation. The excellent performance of the DTN is mainly due to the concaved cavity. In this paper, two DTNs of different scales have been investigated by unsteady numerical simulations to compare the parameter variations and study the effects of cavity during the vector starting process. The results remind us that during the vector starting process, dynamic loads may be generated, which is a potentially challenging problem for the aircraft trim and control.

  8. Numerical Comparison of NASA's Dual Brayton Power Generation System Performance Using CO2 or N2 as the Working Fluid

    Science.gov (United States)

    Ownens, Albert K.; Lavelle, Thomas M.; Hervol, David S.

    2010-01-01

    A Dual Brayton Power Conversion System (DBPCS) has been tested at the NASA Glenn Research Center using Nitrogen (N2) as the working fluid. This system uses two closed Brayton cycle systems that share a common heat source and working fluid but are otherwise independent. This system has been modeled using the Numerical Propulsion System Simulation (NPSS) environment. This paper presents the results of a numerical study that investigated system performance changes resulting when the working fluid is changed from gaseous (N2) to gaseous carbon dioxide (CO2).

  9. Evaluating UV-C LED disinfection performance and investigating potential dual-wavelength synergy.

    Science.gov (United States)

    Beck, Sara E; Ryu, Hodon; Boczek, Laura A; Cashdollar, Jennifer L; Jeanis, Kaitlyn M; Rosenblum, James S; Lawal, Oliver R; Linden, Karl G

    2017-02-01

    A dual-wavelength UV-C LED unit, emitting at peaks of 260 nm, 280 nm, and the combination of 260|280 nm together was evaluated for its inactivation efficacy and energy efficiency at disinfecting Escherichia coli, MS2 coliphage, human adenovirus type 2 (HAdV2), and Bacillus pumilus spores, compared to conventional low-pressure and medium-pressure UV mercury vapor lamps. The dual-wavelength unit was also used to measure potential synergistic effects of multiple wavelengths on bacterial and viral inactivation and DNA and RNA damage. All five UV sources demonstrated similar inactivation of E. coli. For MS2, the 260 nm LED was most effective. For HAdV2 and B. pumilus, the MP UV lamp was most effective. When measuring electrical energy per order of reduction, the LP UV lamp was most efficient for inactivating E. coli and MS2; the LP UV and MP UV mercury lamps were equally efficient for HAdV2 and B. pumilus spores. Among the UV-C LEDs, there was no statistical difference in electrical efficiency for inactivating MS2, HAdV2, and B. pumilus spores. The 260 nm and 260|280 nm LEDs had a statistical energy advantage for E. coli inactivation. For UV-C LEDs to match the electrical efficiency per order of log reduction of conventional LP UV sources, they must reach efficiencies of 25-39% or be improved on by smart reactor design. No dual wavelength synergies were detected for bacterial and viral inactivation nor for DNA and RNA damage. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Influence of anti-corrosion additive on the performance, emission and engine component wear characteristics of an IDI diesel engine fueled with palm biodiesel

    International Nuclear Information System (INIS)

    Ashraful, A.M.; Masjuki, H.H.; Kalam, M.A.; Rashedul, H.K.; Sajjad, H.; Abedin, M.J.

    2014-01-01

    Highlights: • Maximum engine performance was obtained at 2000 rpm for all fuel blends. • IRGALUBE 349 additive is enhances diesel engine performance. • Reduction of CO and NOx considerably using anti-corrosion additive except HC. • Engine wear decreases with using blended fuels with anti-corrosion additive. - Abstract: This study evaluates the effect of anti-corrosion additives such as 8% and 16% (vol.%) palm olein oil (PO) with ordinary diesel (OD) fuel on engine operation, emission behavior, engine part wear, and lubrication characteristics. This experiment was conducted on 4-cylinder and 4-stroke IDI diesel engine at different engine speed ranging from 1200 to 2800 RPM with 30% throttle setting under full load condition. The properties of the palm olein oil blends meet the ASTM D6751 and EN 14214 standards. At 2000 rpm, the experimental results revealed that the POD8A (0.2% Additive + 8% PO + 92% OD) and POD16A (0.2% Additive + 16% PO + 84% OD) blended fuels produced 0.5% and 0.51% higher brake power as well as 1.45% and 1.25% higher torque than same blends without additive, respectively. In comparison with ODF, the brake specific fuel consumption (BSFC) was found 1.8% and 3.1% higher for POD8A and POD16A blends, respectively. Anti-corrosion additive is found more effectual in enhancing the engine performance as such additive helps in timely ignition for complete burn in the combustion chamber. The results from engine emission indicated that POD8A and POD16A blended fuel reduced CO emissions by 11% and 6.6% and NOx emission by 2.5% and 1.09%, respectively in compared with OD fuel. Although HC emissions for all blended fuel and OD fuel increased at higher engine speed, the average HC emissions of all blended fuel were not higher than OD fuel. The application of anti-corrosion additives in POD blends reduced ferrous (Fe) wear debris concentration (WBC) by 17.3%. The reductions in WBC were about 16.1%, 10.8%, and 19.3%, 17.6% for copper (Cu) and aluminum

  11. FY05 HPCRM Annual Report: High-Performance Corrosion-Resistant Iron-Based Amorphous Metal Coatings

    International Nuclear Information System (INIS)

    Farmer, J; Choi, J; Haslam, J; Day, S; Yang, N; Headley, T; Lucadamo, G; Yio, J; Chames, J; Gardea, A; Clift, M; Blue, G; Peters, W; Rivard, J; Harper, D; Swank, D; Bayles, R; Lemieux, E; Brown, R; Wolejsza, T; Aprigliano, L; Branagan, D; Marshall, M; Meacham, B; Aprigliano, L; Branagan, D; Marshall, M; Meacham, B; Lavernia, E; Schoenung, J; Ajdelsztajn, L; Dannenberg, J; Graeve, O; Lewandowski, J; Perepezko, J; Hildal, K; Kaufman, L; Boudreau, J

    2007-01-01

    New corrosion-resistant, iron-based amorphous metals have been identified from published data or developed through combinatorial synthesis, and tested to determine their relative corrosion resistance. Many of these materials can be applied as coatings with advanced thermal spray technology. Two compositions have corrosion resistance superior to wrought nickel-based Alloy C-22 (UNS No. N06022) in some very aggressive environments, including concentrated calcium-chloride brines at elevated temperature. Two Fe-based amorphous metal formulations have been found that appear to have corrosion resistance comparable to, or better than that of Ni-based Alloy C-22, based on breakdown potential and corrosion rate. Both Cr and Mo provide corrosion resistance, B enables glass formation, and Y lowers critical cooling rate (CCR). SAM1651 has yttrium added, and has a nominal critical cooling rate of only 80 Kelvin per second, while SAM2X7 (similar to SAM2X5) has no yttrium, and a relatively high critical cooling rate of 610 Kelvin per second. Both amorphous metal formulations have strengths and weaknesses. SAM1651 (yttrium added) has a low critical cooling rate (CCR), which enables it to be rendered as a completely amorphous thermal spray coating. Unfortunately, it is relatively difficult to atomize, with powders being irregular in shape. This causes the powder to be difficult to pneumatically convey during thermal spray deposition. Gas atomized SAM1651 powder has required cryogenic milling to eliminate irregularities that make flow difficult. SAM2X5 (no yttrium) has a high critical cooling rate, which has caused problems associated with devitrification. SAM2X5 can be gas atomized to produce spherical powders of SAM2X5, which enable more facile thermal spray deposition. The reference material, nickel-based Alloy C-22, is an outstanding corrosion-resistant engineering material. Even so, crevice corrosion has been observed with C-22 in hot sodium chloride environments without buffer

  12. Electrochemical synthesis of bilayer coatings of poly(N-methylaniline) and polypyrrole on mild steel and their corrosion protection performances

    Energy Technology Data Exchange (ETDEWEB)

    Zeybek, Buelent [Ankara University, Faculty of Science, Department of Chemistry, Ankara (Turkey); Dumlupinar University, Faculty of Arts and Sciences, Department of Chemistry, Kuetahya (Turkey); Ozcicek Pekmez, Nuran, E-mail: npekmez@hacettepe.edu.t [Hacettepe University, Faculty of Science, Department of Chemistry, Ankara (Turkey); Kilic, Esma [Ankara University, Faculty of Science, Department of Chemistry, Ankara (Turkey)

    2011-10-30

    Highlights: > The bilayers of poly(N-methylaniline) and polypyrrole-dodecylsulfate were synthesized. > These films on mild steel were characterized by cyclic voltammetry, FTIR and FESEM. > DS dopant allows permeation to cations and decreases the ingress of chloride ions. > The PNMA/PPy-DS bilayer coating exhibited the best corrosion resistance in 0.5 M HCl. > The protective properties of polymers was developed by preparing their bilayer coatings. - Abstract: Homopolymer and bilayer coatings of poly(N-methylaniline) (PNMA) and polypyrrole-dodecylsulfate (PPy-DS) have been electropolymerized on a mild steel (MS) surface by the potentiodynamic method in aqueous oxalic acid solutions. In order to include dodecylsulfate ion as dopant in the polypyrrole, sodium dodecylsulfate was also added to the polymerization solution of pyrrole. Characterization of coatings was carried out by the cyclic voltammetry, Fourier transform infrared (FTIR) spectroscopy and field emission scanning electron microscopy (FESEM). Corrosion behavior of the polymer coated MS electrodes was investigated in highly aggressive 0.5 M HCl solution by the Tafel test and electrochemical impedance spectroscopy (EIS) techniques. Corrosion test revealed that among the protective coatings obtained, the PNMA/PPy-DS bilayer exhibited the best corrosion resistance at all immersion times.

  13. FY05 HPCRM Annual Report: High-Performance Corrosion-Resistant Iron-Based Amorphous Metal Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, J; Choi, J; Haslam, J; Day, S; Yang, N; Headley, T; Lucadamo, G; Yio, J; Chames, J; Gardea, A; Clift, M; Blue, G; Peters, W; Rivard, J; Harper, D; Swank, D; Bayles, R; Lemieux, E; Brown, R; Wolejsza, T; Aprigliano, L; Branagan, D; Marshall, M; Meacham, B; Aprigliano, L; Branagan, D; Marshall, M; Meacham, B; Lavernia, E; Schoenung, J; Ajdelsztajn, L; Dannenberg, J; Graeve, O; Lewandowski, J; Perepezko, J; Hildal, K; Kaufman, L; Boudreau, J

    2007-09-20

    New corrosion-resistant, iron-based amorphous metals have been identified from published data or developed through combinatorial synthesis, and tested to determine their relative corrosion resistance. Many of these materials can be applied as coatings with advanced thermal spray technology. Two compositions have corrosion resistance superior to wrought nickel-based Alloy C-22 (UNS No. N06022) in some very aggressive environments, including concentrated calcium-chloride brines at elevated temperature. Two Fe-based amorphous metal formulations have been found that appear to have corrosion resistance comparable to, or better than that of Ni-based Alloy C-22, based on breakdown potential and corrosion rate. Both Cr and Mo provide corrosion resistance, B enables glass formation, and Y lowers critical cooling rate (CCR). SAM1651 has yttrium added, and has a nominal critical cooling rate of only 80 Kelvin per second, while SAM2X7 (similar to SAM2X5) has no yttrium, and a relatively high critical cooling rate of 610 Kelvin per second. Both amorphous metal formulations have strengths and weaknesses. SAM1651 (yttrium added) has a low critical cooling rate (CCR), which enables it to be rendered as a completely amorphous thermal spray coating. Unfortunately, it is relatively difficult to atomize, with powders being irregular in shape. This causes the powder to be difficult to pneumatically convey during thermal spray deposition. Gas atomized SAM1651 powder has required cryogenic milling to eliminate irregularities that make flow difficult. SAM2X5 (no yttrium) has a high critical cooling rate, which has caused problems associated with devitrification. SAM2X5 can be gas atomized to produce spherical powders of SAM2X5, which enable more facile thermal spray deposition. The reference material, nickel-based Alloy C-22, is an outstanding corrosion-resistant engineering material. Even so, crevice corrosion has been observed with C-22 in hot sodium chloride environments without buffer

  14. ECG signal performance de-noising assessment based on threshold tuning of dual-tree wavelet transform.

    Science.gov (United States)

    El B'charri, Oussama; Latif, Rachid; Elmansouri, Khalifa; Abenaou, Abdenbi; Jenkal, Wissam

    2017-02-07

    Since the electrocardiogram (ECG) signal has a low frequency and a weak amplitude, it is sensitive to miscellaneous mixed noises, which may reduce the diagnostic accuracy and hinder the physician's correct decision on patients. The dual tree wavelet transform (DT-WT) is one of the most recent enhanced versions of discrete wavelet transform. However, threshold tuning on this method for noise removal from ECG signal has not been investigated yet. In this work, we shall provide a comprehensive study on the impact of the choice of threshold algorithm, threshold value, and the appropriate wavelet decomposition level to evaluate the ECG signal de-noising performance. A set of simulations is performed on both synthetic and real ECG signals to achieve the promised results. First, the synthetic ECG signal is used to observe the algorithm response. The evaluation results of synthetic ECG signal corrupted by various types of noise has showed that the modified unified threshold and wavelet hyperbolic threshold de-noising method is better in realistic and colored noises. The tuned threshold is then used on real ECG signals from the MIT-BIH database. The results has shown that the proposed method achieves higher performance than the ordinary dual tree wavelet transform into all kinds of noise removal from ECG signal. The simulation results indicate that the algorithm is robust for all kinds of noises with varying degrees of input noise, providing a high quality clean signal. Moreover, the algorithm is quite simple and can be used in real time ECG monitoring.

  15. The effects of stimulus modality and task integrality: Predicting dual-task performance and workload from single-task levels

    Science.gov (United States)

    Hart, S. G.; Shively, R. J.; Vidulich, M. A.; Miller, R. C.

    1986-01-01

    The influence of stimulus modality and task difficulty on workload and performance was investigated. The goal was to quantify the cost (in terms of response time and experienced workload) incurred when essentially serial task components shared common elements (e.g., the response to one initiated the other) which could be accomplished in parallel. The experimental tasks were based on the Fittsberg paradigm; the solution to a SternBERG-type memory task determines which of two identical FITTS targets are acquired. Previous research suggested that such functionally integrated dual tasks are performed with substantially less workload and faster response times than would be predicted by suming single-task components when both are presented in the same stimulus modality (visual). The physical integration of task elements was varied (although their functional relationship remained the same) to determine whether dual-task facilitation would persist if task components were presented in different sensory modalities. Again, it was found that the cost of performing the two-stage task was considerably less than the sum of component single-task levels when both were presented visually. Less facilitation was found when task elements were presented in different sensory modalities. These results suggest the importance of distinguishing between concurrent tasks that complete for limited resources from those that beneficially share common resources when selecting the stimulus modalities for information displays.

  16. Effect of Heat Treatment on Corrosion Behaviors of Mg-5Y-1.5Nd Alloys

    Directory of Open Access Journals (Sweden)

    Xiumin Ma

    2016-01-01

    Full Text Available Corrosion behavior of Mg-5Y-1.5Nd alloy was investigated after heat treatment. The microstructure and precipitation were studied by scanning electron microscope (SEM and energy dispersive spectrometer (EDS. The weight loss rates of different samples were arranged as T6-24 h>T6-6 h>T6-14 h>as-cast>T4. The open circuit potential (OCP showed that T4 sample had a more positive potential than that of other samples. The potentiodynamic polarization curves showed that the T6-24 h sample had the highest corrosion current density of 245.362 μA·cm−2, whereas the T4 sample had the lowest at 52.164 μA·cm−2. The EIS results confirmed that the heat treatment reduced the corrosion resistance for Mg-5Y-1.5Nd alloy, because the precipitations acted as the cathode of electrochemical reactions to accelerate the corrosion process. The corrosion rates of different samples were mainly determined by the amount and distribution of the precipitations. The precipitations played dual roles that depended on the amount and distribution. The presence of the phase in the alloys could deteriorate the corrosion performance as it could act as an effective galvanic cathode. Otherwise, a fine and homogeneous phase appeared to be a better anticorrosion barrier.

  17. Dual process theory and intermediate effect: are faculty and residents' performance on multiple-choice, licensing exam questions different?

    Science.gov (United States)

    Dong, Ting; Durning, Steven J; Artino, Anthony R; van der Vleuten, Cees; Holmboe, Eric; Lipner, Rebecca; Schuwirth, Lambert

    2015-04-01

    Clinical reasoning is essential for the practice of medicine. Dual process theory conceptualizes reasoning as falling into two general categories: nonanalytic reasoning (pattern recognition) and analytic reasoning (active comparing and contrasting of alternatives). The debate continues regarding how expert performance develops and how individuals make the best use of analytic and nonanalytic processes. Several investigators have identified the unexpected finding that intermediates tend to perform better on licensing examination items than experts, which has been termed the "intermediate effect." We explored differences between faculty and residents on multiple-choice questions (MCQs) using dual process measures (both reading and answering times) to inform this ongoing debate. Faculty (board-certified internists; experts) and residents (internal medicine interns; intermediates) answered live licensing examination MCQs (U.S. Medical Licensing Examination Step 2 Clinical Knowledge and American Board of Internal Medicine Certifying Examination) while being timed. We conducted repeated analysis of variance to compare the 2 groups on average reading time, answering time, and accuracy on various types of items. Faculty and residents did not differ significantly in reading time [F (1,35) = 0.01, p = 0.93], answering time [F (1,35) = 0.60, p = 0.44], or accuracy [F (1,35) = 0.24, p = 0.63] regardless of easy or hard items. Dual process theory was not evidenced in this study. However, this lack of difference between faculty and residents may have been affected by the small sample size of participants and MCQs may not reflect how physicians made decisions in actual practice setting. Reprint & Copyright © 2015 Association of Military Surgeons of the U.S.

  18. Detection of parathyroid adenomas using a monophasic dual-energy computed tomography acquisition: diagnostic performance and potential radiation dose reduction

    International Nuclear Information System (INIS)

    Leiva-Salinas, Carlos; Flors, Lucia; Durst, Christopher R.; Hou, Qinghua; Mukherjee, Sugoto; Patrie, James T.; Wintermark, Max

    2016-01-01

    The aims of the study were to compare the diagnostic performance of a combination of virtual non-contrast (VNC) images and arterial images obtained from a single-phase dual-energy CT (DECT) acquisition and standard non-contrast and arterial images from a biphasic protocol and to study the potential radiation dose reduction of the former approach. All DECT examinations performed for evaluation of parathyroid adenomas during a 13-month period were retrospectively reviewed. An initial single-energy unenhanced acquisition was followed by a dual-energy arterial phase acquisition. ''Virtual non-contrast images'' were generated from the dual-energy acquisition. Two independent and blinded radiologists evaluated three different sets of images during three reading sessions: single arterial phase, single-phase DECT (virtual non-contrast and arterial phase), and standard biphasic protocol (true non-contrast and arterial phase). The accuracy of interpretation in lateralizing an adenoma to the side of the neck and localizing it to a quadrant in the neck was evaluated. Sixty patients (mean age, 65.5 years; age range, 38-87 years) were included in the study. The lateralization and localization accuracy, sensitivity, and positive predicted value (PPV) and negative predicted value (NPV) of the different image datasets were comparable. The combination of VNC and arterial images was more specific than arterial images alone to lateralize a parathyroid lesion (OR = 1.93, p = 0.043). The use of the single-phase protocol resulted in a calculated radiation exposure reduction of 52.8 %. Virtual non-contrast and arterial images from a single DECT acquisition showed similar diagnostic accuracy than a biphasic protocol, providing a significant dose reduction. (orig.)

  19. Detection of parathyroid adenomas using a monophasic dual-energy computed tomography acquisition: diagnostic performance and potential radiation dose reduction

    Energy Technology Data Exchange (ETDEWEB)

    Leiva-Salinas, Carlos; Flors, Lucia; Durst, Christopher R.; Hou, Qinghua; Mukherjee, Sugoto [University of Virginia, Department of Radiology, Division of Neuroradiology, Charlottesville, VA (United States); Patrie, James T. [University of Virginia, Department of Public Health Sciences, Charlottesville, VA (United States); Wintermark, Max [Stanford University, Department of Radiology, Palo Alto, CA (United States)

    2016-11-15

    The aims of the study were to compare the diagnostic performance of a combination of virtual non-contrast (VNC) images and arterial images obtained from a single-phase dual-energy CT (DECT) acquisition and standard non-contrast and arterial images from a biphasic protocol and to study the potential radiation dose reduction of the former approach. All DECT examinations performed for evaluation of parathyroid adenomas during a 13-month period were retrospectively reviewed. An initial single-energy unenhanced acquisition was followed by a dual-energy arterial phase acquisition. ''Virtual non-contrast images'' were generated from the dual-energy acquisition. Two independent and blinded radiologists evaluated three different sets of images during three reading sessions: single arterial phase, single-phase DECT (virtual non-contrast and arterial phase), and standard biphasic protocol (true non-contrast and arterial phase). The accuracy of interpretation in lateralizing an adenoma to the side of the neck and localizing it to a quadrant in the neck was evaluated. Sixty patients (mean age, 65.5 years; age range, 38-87 years) were included in the study. The lateralization and localization accuracy, sensitivity, and positive predicted value (PPV) and negative predicted value (NPV) of the different image datasets were comparable. The combination of VNC and arterial images was more specific than arterial images alone to lateralize a parathyroid lesion (OR = 1.93, p = 0.043). The use of the single-phase protocol resulted in a calculated radiation exposure reduction of 52.8 %. Virtual non-contrast and arterial images from a single DECT acquisition showed similar diagnostic accuracy than a biphasic protocol, providing a significant dose reduction. (orig.)

  20. Simulation analysis on dynamic performance of a combined solar/air dual source heat pump water heater

    International Nuclear Information System (INIS)

    Deng, Weishi; Yu, Jianlin

    2016-01-01

    Highlights: • A modified direct expansion solar-assisted heat pump water heater is investigated. • An additional air source evaporator is used in parallel way in the M-DX-SHPWH system. • The M-DX-SHPWH system displays a higher performance at the low solar radiation. • Effects of solar radiation and air temperature on the performance are discussed. - Abstract: This paper investigated a combined solar/air dual source heat pump water heater system for domestic water heating application. In the dual source system, an additional air source evaporator is introduced in parallel way based on a conventional direct expansion solar-assisted heat pump water heaters (DX-SHPWH) system, which can improve the performance of the DX-SHPWH system at a low solar radiation. In the present study, a dynamic mathematical model based on zoned lump parameter approach is developed to simulate the performance of the system (i.e. a modified DX-SHPWH (M-DX-SHPWH) system). Using the model, the performance of M-DX-SHPWH system is evaluated and then compared with that of the conventional DX-SHPWH system. The simulation results show the M-DX-SHPWH system has a better performance than that of the conventional DX-SHPWH system. At a low solar radiation of 100 W/m"2, the heating time of the M-DX-SHPWH decreases by 19.8% compared to the DX-SHPWH when water temperature reaches 55 °C. Meanwhile, the COP on average increases by 14.1%. In addition, the refrigerant mass flow rate distribution in the air source evaporator and the solar collector of the system, the allocation between the air source evaporator and the solar collector areas and effects of solar radiation and ambient air temperature on the system performance are discussed.

  1. Synthesis of dual porous structured germanium anodes with exceptional lithium-ion storage performance

    Science.gov (United States)

    Kwon, Dohyoung; Ryu, Jaegeon; Shin, Myungsoo; Song, Gyujin; Hong, Dongki; Kim, Kwang S.; Park, Soojin

    2018-01-01

    Dual-porous Ge nanostructures are synthesized via two straightforward steps. Compared with conventional approaches related to porous Ge materials, different types of pores can be readily generated by adjusting the relative ratio of the precursor amounts for GeO2 and SiO2. Unlike using hard templates with different sizes for introducing secondary pores, this system makes a uniformly blended structure of porogen and active sites in the nanoscale range. When GeO2 is subjected to zincothermic reduction, it is selectively converted to pure Ge still connected to unreacted SiO2. During the reduction process, primary pores (larger than 50 nm) are formed by eliminating zinc oxide by-products, while inactive SiO2 with respect to zinc metal could contribute to retaining the overall structure. Finally, the HF treatment completely leaches remaining SiO2 and formed secondary pores (micro/mesopores) to complete the dual-porous Ge structure. The resulting Ge structure is tested as an anode material for lithium-ion batteries. The Ge electrode exhibits an outstanding reversibility and an exceptional cycling stability corresponding to a capacity retention of 100% after 100 cycles at C/5 and of 94.4% after 300 cycles at C/2. Furthermore, multi-scale pores facilitate a facile Li-ion accessibility, resulting in an excellent rate capability delivering ∼740 mAh g-1 at 5C.

  2. Effects of heat transfer, friction and variable specific heats of working fluid on performance of an irreversible dual cycle

    International Nuclear Information System (INIS)

    Chen Lingen; Ge Yanlin; Sun Fengrui; Wu Chih

    2006-01-01

    The thermodynamic performance of an air standard dual cycle with heat transfer loss, friction like term loss and variable specific heats of working fluid is analyzed. The relations between the power output and the compression ratio, between the thermal efficiency and the compression ratio, as well as the optimal relation between power output and the efficiency of the cycle, are derived by detailed numerical examples. Moreover, the effects of variable specific heats of the working fluid and the friction like term loss on the irreversible cycle performance are analyzed. The results show that the effects of variable specific heats of working fluid and friction like term loss on the cycle performance are obvious, and they should be considered in practical cycle analysis. The results obtained in this paper may provide guidance for the design of practical internal combustion engines

  3. Effect of pole number and slot number on performance of dual rotor permanent magnet wind power generator using ferrite magnets

    Directory of Open Access Journals (Sweden)

    Peifeng Xu

    2017-05-01

    Full Text Available Dual rotor permanent magnet (DRPM wind power generator using ferrite magnets has the advantages of low cost, high efficiency, and high torque density. How to further improve the performance and reduce the cost of the machine by proper choice of pole number and slot number is an important problem to be solved when performing preliminarily design a DRPM wind generator. This paper presents a comprehensive performance comparison of a DRPM wind generator using ferrite magnets with different slot and pole number combinations. The main winding factors are calculated by means of the star of slots. Under the same machine volume and ferrite consumption, the flux linkage, back-electromotive force (EMF, cogging torque, output torque, torque pulsation, and losses are investigated and compared using finite element analysis (FEA. The results show that the slot and pole number combinations have an important impact on the generator properties.

  4. Experimental study on combustion modes and thrust performance of a staged-combustor of the scramjet with dual-strut

    Science.gov (United States)

    Yang, Qingchun; Chetehouna, Khaled; Gascoin, Nicolas; Bao, Wen

    2016-05-01

    To enable the scramjet operate in a wider flight Mach number, a staged-combustor with dual-strut is introduced to hold more heat release at low flight Mach conditions. The behavior of mode transition was examined using a direct-connect model scramjet experiment along with pressure measurements. The typical operating modes of the staged-combustor are analyzed. Fuel injection scheme has a significant effect on the combustor operating modes, particularly for the supersonic combustion mode. Thrust performances of the combustor with different combustion modes and fuel distributions are reported in this paper. The first-staged strut injection has a better engine performance in the operation of subsonic combustion mode. On the contrast, the second-staged strut injection has a better engine performance in the operation of supersonic combustion mode.

  5. Enhanced antimicrobial properties, cytocompatibility, and corrosion resistance of plasma-modified biodegradable magnesium alloys.

    Science.gov (United States)

    Zhao, Ying; Jamesh, Mohammed Ibrahim; Li, Wing Kan; Wu, Guosong; Wang, Chenxi; Zheng, Yufeng; Yeung, Kelvin W K; Chu, Paul K

    2014-01-01

    Magnesium alloys are potential biodegradable materials and have received increasing attention due to their outstanding biological performance and mechanical properties. However, rapid degradation in the physiological environment and potential toxicity limit clinical applications. Recently, special magnesium-calcium (Mg-Ca) and magnesium-strontium (Mg-Sr) alloys with biocompatible chemical compositions have been reported, but the rapid degradation still does not meet clinical requirements. In order to improve the corrosion resistance, a rough, hydrophobic and ZrO(2)-containing surface film is fabricated on Mg-Ca and Mg-Sr alloys by dual zirconium and oxygen ion implantation. Weight loss measurements and electrochemical corrosion tests show that the corrosion rate of the Mg-Ca and Mg-Sr alloys is reduced appreciably after surface treatment. A systematic investigation of the in vitro cellular response and antibacterial capability of the modified binary magnesium alloys is performed. The amounts of adherent bacteria on the Zr-O-implanted and Zr-implanted samples diminish remarkably compared to the unimplanted control. In addition, significantly enhanced cell adhesion and proliferation are observed from the Zr-O-implanted sample. The results suggest that dual zirconium and oxygen ion implantation, which effectively enhances the corrosion resistance, in vitro biocompatibility and antimicrobial properties of Mg-Ca and Mg-Sr alloys, provides a simple and practical means to expedite clinical acceptance of biodegradable magnesium alloys. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  6. Desempeño y emisiones de un motor de combustión interna con combustible dual Diesel – Gas natural ;Performance and emissions study of an internal combustion engine with dual fuel diesel - natural gas

    Directory of Open Access Journals (Sweden)

    Juan Miguel Mantilla González

    2015-04-01

    Full Text Available Muchos de los problemas reportados para los sistemas duales diesel- gas natural ocurren por mala dosificación del gas. Por esta razón se adaptó un sistema de alimentación dual con inyección electrónica de gas natural a un motor de combustión interna encendido por compresión. Se plantea un diseño experimental controlando el dosado de gas natural.Como resultado se obtiene un análisis comparativo entre los valoresde desempeño y emisiones desde la operación Diesel y Diesel-Gas natural. A partir de este análisis es posible observar que el desempeño del motor no se ve afectado por la operación del motor bajo el esquema Dual Diesel-GN, es decir que el motor funcionando bajo modo dual puede sostener las cargas solicitadas al motor. También se observa que la eficiencia volumétrica mejora bajo todas las condiciones de operación dual y las emisiones son mejores sólo cuando el motor trabaja a altas cargas. Many of the problems reported for dual diesel-natural gas systems occur due to poor gas dosage. For this reason a natural gas electronic injection feeding system was adapted to a compression ignitios internal combustion engine. An experimental design controlling the natural gas dosage is considered. As a result a comparative analysis between performance and emissions from the Diesel-and diesel-Natural Gas operation is obtained. From this analysis it is possible to see that engine performance is not affected by operation of the engine under the dual mode, i.e. the motor running under dual mode can support the loads applied to the engine. It is also observed that the volumetric efficiency improves under all conditions of operation and emissions from the dual mode of operation are better only when working at high engine loads.

  7. Properties and Corrosion Performance of Self-reinforced Composite PEEK for Proposed Use as a Modular Taper Gasket.

    Science.gov (United States)

    Ouellette, Eric S; Gilbert, Jeremy L

    2016-11-01

    Fretting corrosion in medical alloys is a persistent problem, and the need for biomaterials that can effectively suppress mechanically assisted crevice corrosion in modular taper junctions or otherwise insulate metal-on-metal interfaces in mechanically demanding environments is as yet unmet. The purpose of this study is to characterize a novel material, self-reinforced composite polyetheretherketone (SRC-PEEK) and to evaluate its ability to inhibit fretting corrosion in a pin-on-disk metal-on-metal interface test. SRC-PEEK was fabricated by hot compaction of in-house-made PEEK fibers by compacting uniaxial layups at 344°C under a load of 18,000 N for 10 minutes. SRC-PEEK, bulk isotropic PEEK, and the in-house-made PEEK fibers were analyzed for thermal transitions (T g , T m ) through differential scanning calorimetry, crystallinity, crystal size, crystalline orientation (Hermanns orientation parameter) through wide-angle x-ray scattering, and modulus, tensile strength, yield stress, and strain to failure through monotonic tensile testing. SRC-insulated pin-on-disk samples were compared with metal-on-metal control samples in pin-on-disk fretting corrosion experiments using fretting current and fretting mechanics measurements. Fifty-micron cyclic motion at 2.5 Hz was applied to the interface, first over a range of loads (0.5-35 N) while held at -0.05 V versus Ag/AgCl and then over a range of voltages (-0.5 to 0.5 V) at a constant contact stress of 73 ± 19 MPa for SRC-PEEK and 209 ± 41 MPa for metal-on-metal, which were different for each group as a result of changes in true contact area due to variations in modulus between sample groups. Pins, disks, and SRC samples were imaged for damage (on alloy and SRC surfaces) and evidence of corrosion (on alloy pin and disk surfaces). SRC specimens were analyzed for traces of alloy transferred to the surface using energy dispersive spectroscopy after pin-on-disk testing. SRC-PEEK showed improved mechanical properties to

  8. On the performance of hybrid RF and RF/FSO fixed gain dual-hop transmission systems

    KAUST Repository

    Ansari, Imran Shafique

    2013-04-01

    In this work, we present the performance analysis of a dual-branch transmission system composed of a direct radio frequency (RF) link and a dual-hop relay composed of asymmetric RF and free-space optical (FSO) links and compare it without having a direct RF path to see the effects of diversity on our system. The FSO link accounts for pointing errors and both types of detection techniques (i.e. indirect modulation/direct detection (IM/DD) as well as heterodyne detection). The performance is evaluated under the assumption of selection combining diversity scheme. RF links are modeled by Rayleigh fading distribution whereas the FSO link is modeled by a unified Gamma-Gamma fading distribution. Specifically, we derive new exact closed-form expressions for the cumulative distribution function, probability density function, moment generating function, and moments of the end-to-end signal-to-noise ratio of these systems in terms of the Meijer\\'s G function. We then capitalize on these results to offer new exact closed-form expressions for the outage probability, higher-order amount of fading, average error rate for binary and M-ary modulation schemes, and ergodic capacity, all in terms of Meijer\\'s G functions. All our new analytical results are also verified via computer-based Monte-Carlo simulations. © 2013 IEEE.

  9. Corrosion in airframes

    OpenAIRE

    PETROVIC ZORAN C.

    2016-01-01

    The introductory chapter provides a brief reference to the issue of corrosion and corrosion damage to aircraft structures. Depending on the nature and dimensions of this non uniformity, three different categories of corrosion are defined: uniform, selective and localized corrosion. The following chapters present the forms of corrosion that can occur in three defined categories of corrosion. Conditions that cause certain types of corrosion in various corrosive environments are discussed. Examp...

  10. High-Performance Corrosion-Resistant Materials: Iron-Based Amorphous-Metal Thermal-Spray Coatings: SAM HPCRM Program ? FY04 Annual Report ? Rev. 0 - DARPA DSO and DOE OCRWM Co-Sponsored Advanced Materials Program

    International Nuclear Information System (INIS)

    Farmer, J; Haslam, J; Wong, F; Ji, S; Day, S; Branagan, D; Marshall, M; Meacham, B; Buffa, E; Blue, C; Rivard, J; Beardsley, M; Buffa, E; Blue, C; Rivard, J; Beardsley, M; Weaver, D; Aprigliano, L; Kohler, L; Bayles, R; Lemieux, E; Wolejsza, T; Martin, F; Yang, N; Lucadamo, G; Perepezko, J; Hildal, K; Kaufman, L; Heuer, A; Ernst, F; Michal, G; Kahn, H; Lavernia, E

    2007-01-01

    The multi-institutional High Performance Corrosion Resistant Materials (HPCRM) Team is cosponsored by the Defense Advanced Projects Agency (DARPA) Defense Science Office (DSO) and the Department of Energy (DOE) Office of Civilian Radioactive Waste Management (OCRWM), and has developed new corrosion-resistant, iron-based amorphous metals that can be applied as coatings with advanced thermal spray technology. Two compositions have corrosion resistance superior to wrought nickel-based Alloy C-22 (UNS No. N06022) in very aggressive environments, including concentrated calcium-chloride brines at elevated temperature. Corrosion costs the Department of Defense billions of dollars every year, with an immense quantity of material in various structures undergoing corrosion. For example, in addition to fluid and seawater piping, ballast tanks, and propulsions systems, approximately 345 million square feet of structure aboard naval ships and crafts require costly corrosion control measures. The use of advanced corrosion-resistant materials to prevent the continuous degradation of this massive surface area would be extremely beneficial. The Fe-based corrosion-resistant, amorphous-metal coatings under development may prove of importance for applications on ships. Such coatings could be used as an 'integral drip shield' on spent fuel containers, as well as protective coatings that could be applied over welds, thereby preventing exposure to environments that might cause stress corrosion cracking. In the future, such new high-performance iron-based materials could be substituted for more-expensive nickel-based alloys, thereby enabling a reduction in the $58-billion life cycle cost for the long-term storage of the Nation's spent nuclear fuel by tens of percent

  11. High-Performance Corrosion-Resistant Materials: Iron-Based Amorphous-Metal Thermal-Spray Coatings: SAM HPCRM Program ? FY04 Annual Report ? Rev. 0 - DARPA DSO & DOE OCRWM Co-Sponsored Advanced Materials Program

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, J; Haslam, J; Wong, F; Ji, S; Day, S; Branagan, D; Marshall, M; Meacham, B; Buffa, E; Blue, C; Rivard, J; Beardsley, M; Buffa, E; Blue, C; Rivard, J; Beardsley, M; Weaver, D; Aprigliano, L; Kohler, L; Bayles, R; Lemieux, E; Wolejsza, T; Martin, F; Yang, N; Lucadamo, G; Perepezko, J; Hildal, K; Kaufman, L; Heuer, A; Ernst, F; Michal, G; Kahn, H; Lavernia, E

    2007-09-19

    The multi-institutional High Performance Corrosion Resistant Materials (HPCRM) Team is cosponsored by the Defense Advanced Projects Agency (DARPA) Defense Science Office (DSO) and the Department of Energy (DOE) Office of Civilian Radioactive Waste Management (OCRWM), and has developed new corrosion-resistant, iron-based amorphous metals that can be applied as coatings with advanced thermal spray technology. Two compositions have corrosion resistance superior to wrought nickel-based Alloy C-22 (UNS No. N06022) in very aggressive environments, including concentrated calcium-chloride brines at elevated temperature. Corrosion costs the Department of Defense billions of dollars every year, with an immense quantity of material in various structures undergoing corrosion. For example, in addition to fluid and seawater piping, ballast tanks, and propulsions systems, approximately 345 million square feet of structure aboard naval ships and crafts require costly corrosion control measures. The use of advanced corrosion-resistant materials to prevent the continuous degradation of this massive surface area would be extremely beneficial. The Fe-based corrosion-resistant, amorphous-metal coatings under development may prove of importance for applications on ships. Such coatings could be used as an 'integral drip shield' on spent fuel containers, as well as protective coatings that could be applied over welds, thereby preventing exposure to environments that might cause stress corrosion cracking. In the future, such new high-performance iron-based materials could be substituted for more-expensive nickel-based alloys, thereby enabling a reduction in the $58-billion life cycle cost for the long-term storage of the Nation's spent nuclear fuel by tens of percent.

  12. Effects of Hearing Loss on Dual-Task Performance in an Audiovisual Virtual Reality Simulation of Listening While Walking.

    Science.gov (United States)

    Lau, Sin Tung; Pichora-Fuller, M Kathleen; Li, Karen Z H; Singh, Gurjit; Campos, Jennifer L

    2016-07-01

    -subject factors. In analyses of the 60% listening condition, spatial expectation (likely versus unlikely) was a within-subject factor. Differences between groups in age and baseline measures of hearing, mobility, and cognition were tested using t tests. The NH group had significantly better word recognition accuracy than the HL group. Both groups performed better when the probability was higher and the target location more likely. For word recognition, dual-task costs for the HL group did not depend on condition, whereas the NH group demonstrated a surprising dual-task benefit in conditions with lower probability or spatial expectation. For the kinematic parameters, both groups demonstrated a more upright and less variable head position and more variable trunk position during dual-task conditions compared to the walking-only condition, suggesting that safe walking was prioritized. The HL group demonstrated more overall stride time variability than the NH group. This study provides new knowledge about the effects of ARHL, HA use, and aging on word recognition when individuals also perform a mobility-related task that is typically experienced in everyday life. This research may help inform the development of more effective function-based approaches to assessment and intervention for people who are hard-of-hearing. American Academy of Audiology.

  13. Improvement performance and emissions in a diesel engine dual-fueled with natural gas; Tennen gas dual fuel diesel kikan no seino haishutsu gas tokusei no kaizen

    Energy Technology Data Exchange (ETDEWEB)

    Nakayama, S; Okamoto, T; Kusaka, J; Daisho, Y; Kihara, R; Saito, T [Waseda University, Tokyo (Japan)

    1997-10-01

    This paper deals with a study on combustion and emission characteristics of a direct injection diesel engine dual-fueled with natural gas. Dual fueling systems tend to emit high unburned fuel especially at low load, resulting in a decreased thermal efficiency. This is because natural gas-air mixtures are too lean for flame to propagate under low load conditions. Intake charge heating and uncooled EGR are very useful to improve emissions and thermal efficiency at low load. Such favorable effects are supported by NO kinetic simulations. 2 refs., 13 figs.

  14. Long-term corrosion studies

    International Nuclear Information System (INIS)

    Gdowski, G.

    1998-01-01

    The scope of this activity is to assess the long-term corrosion properties of metallic materials under consideration for fabricating waste package containers. Three classes of metals are to be assessed: corrosion resistant, intermediate corrosion resistant, and corrosion allowance. Corrosion properties to be evaluated are general, pitting and crevice corrosion, stress-corrosion cracking, and galvanic corrosion. The performance of these materials will be investigated under conditions that are considered relevant to the potential emplacement site. Testing in four aqueous solutions, and vapor phases above them, and at two temperatures are planned for this activity. (The environmental conditions, test metals, and matrix are described in detail in Section 3.0.) The purpose and objective of this activity is to obtain the kinetic and mechanistic information on degradation of metallic alloys currently being considered for waste package containers. This information will be used to provide assistance to (1) waste package design (metal barrier selection) (E-20-90 to E-20-92), (2) waste package performance assessment activities (SIP-PA-2), (3) model development (E-20-75 to E-20-89). and (4) repository license application

  15. Older Adults Pay an Additional Cost When Texting and Walking: Effects of Age, Environment, and Use of Mixed Reality on Dual-Task Performance.

    Science.gov (United States)

    Krasovsky, Tal; Weiss, Patrice L; Kizony, Rachel

    2018-04-06

    Texting while walking (TeWW) has become common among people of all ages, and mobile phone use during gait is increasingly associated with pedestrian injury. Although dual-task walking performance is known to decline with age, data regarding the effect of age on dual-task performance in ecological settings are limited. The objective of this study was to evaluate the effect of age, environment (indoors/outdoors), and mixed reality (merging of real and virtual environments) on TeWW performance. A cross-sectional design was used. Young (N = 30; 27.8 ± 4.4 years) and older (N = 20; 68.9 ± 3.9 years) adults performed single and dual-task texting and walking indoors and outdoors, with and without a mixed reality display. Participants also completed evaluations of visual scanning and cognitive flexibility (Trail Making Test) and functional mobility (Timed Up and Go). Indoors, similar interference to walking and texting occurred for both groups, but only older adults' gait variability increased under dual task conditions. Outdoors, TeWW was associated with larger age-related differences in gait variability, texting accuracy, and gait dual-task costs. Young adults with better visual scanning and cognitive flexibility performed TeWW with lower gait costs (r = 0.52 to r = 0.65). The mixed reality display was unhelpful and did not modify walking or texting. Older adults tested in this study were relatively high-functioning. Gaze of participants was not directly monitored. Although young and older adults possess the resources necessary for TeWW, older adults pay an additional "price" when dual-tasking, especially outdoors. TeWW may have potential as an ecologically-valid assessment and/or an intervention paradigm for dual task performance among older adults as well as for clinical populations.

  16. Effects of dual-task balance training on postural performance in patients with Multiple Sclerosis: a double-blind, randomized controlled pilot trial.

    Science.gov (United States)

    Monjezi, Saeideh; Negahban, Hossein; Tajali, Shirin; Yadollahpour, Nava; Majdinasab, Nastaran

    2017-02-01

    To investigate the effects of dual-task balance training on postural performance in patients with multiple sclerosis as compared with single-task balance training. Double-blind, pretest-posttest, randomized controlled pilot trial. Local Multiple Sclerosis Society. A total of 47 patients were randomly assigned to two equal groups labeled as single-task training and dual-task training groups. All patients received supervised balance training sessions, 3 times per week for 4 weeks. The patients in the single-task group performed balance activities, alone. However, patients in dual-task group practiced balance activities while simultaneously performing cognitive tasks. The 10-Meter Walk Test and Timed Up-and-Go under single-task and dual-task conditions, in addition to Activities-specific Balance Confidence, Berg Balance Scale, and Functional Gait Assessment were assessed pre-, and post intervention and also 6-weeks after the end of intervention. Only 38 patients completed the treatment plan. There was no difference in the amount of improvement seen between the two study groups. In both groups there was a significant effect of time for dual-10 Meter Walk Test (F 1, 36 =11.33, p=0.002) and dual-Timed Up-and-Go (F 1, 36 =14.27, p=0.001) but not for their single-tasks. Moreover, there was a significant effect of time for Activities-specific Balance Confidence, Berg Balance Scale, and Functional Gait Assessment ( Ppilot study did not show more benefits from undertaking dual-task training than single-task training. A power analysis showed 71 patients per group would be needed to determine whether there was a clinically relevant difference for dual-task gait speed between the groups.

  17. Transverse tripolar spinal cord stimulation: theoretical performance of a dual channel system.

    Science.gov (United States)

    Struijk, J J; Holsheimer, J

    1996-07-01

    A new approach to spinal cord stimulation is presented, by which several serious problems of conventional methods can be solved. A transverse tripolar electrode with a dual-channel voltage stimulator is evaluated theoretically by means of a volume conductor model, combined with nerve fibre models. The simulations predict that a high degree of freedom in the control of activation of dorsal spinal pathways may be obtained with the described system. This implies an easier control of paraesthesia coverage of skin areas and the possibility to correct undesired paraesthesia patterns, caused by lead migration, tissue growth, or anatomical asymmetries, for example, without surgical intervention. It will also be possible to preferentially activate either dorsal column or dorsal root fibres, which has some important clinical advantages. Compared to conventional stimulation systems, the new system has a relatively high current drain.

  18. Modeling indirect detectors for performance optimization of a digital mammographic detector for dual energy applications

    International Nuclear Information System (INIS)

    Martini, N; Koukou, V; Sotiropoulou, P; Nikiforidis, G; Kalyvas, N; Michail, C; Valais, I; Kandarakis, I; Fountos, G; Bakas, A

    2015-01-01

    Dual Energy imaging is a promising method for visualizing masses and microcalcifications in digital mammography. The advent of two X-ray energies (low and high) requires a suitable detector. The scope of this work is to determine optimum detector parameters for dual energy applications. The detector was modeled through the linear cascaded (LCS) theory. It was assumed that a phosphor material was coupled to a CMOS photodetector (indirect detection). The pixel size was 22.5 μm. The phosphor thickness was allowed to vary between 20mg/cm 2 and 160mg/cm 2 The phosphor materials examined where Gd 2 O 2 S:Tb and Gd 2 O 2 S:Eu. Two Tungsten (W) anode X-ray spectra at 35 kV (filtered with 100 μm Palladium (Pd)) and 70 kV (filtered with 800 pm Ytterbium (Yb)), corresponding to low and high energy respectively, were considered to be incident on the detector. For each combination the contrast- to-noise ratio (CNR) and the detector optical gain (DOG), showing the sensitivity of the detector, were calculated. The 40 mg/cm 2 and 70 mg/cm 2 Gd 2 O 2 S:Tb exhibited the higher DOG values for the low and high energy correspondingly. Higher CNR between microcalcification and mammary gland exhibited the 70mg/cm 2 and the 100mg/cm 2 Gd 2 O 2 S:Tb for the low and the high energy correspondingly

  19. Performance Improvement of Polymer Solar Cells by Surface-Energy-Induced Dual Plasmon Resonance.

    Science.gov (United States)

    Yao, Mengnan; Shen, Ping; Liu, Yan; Chen, Boyuan; Guo, Wenbin; Ruan, Shengping; Shen, Liang

    2016-03-09

    The surface plasmon resonance (SPR) effect of metal nanoparticles (MNPs) is effectively applied on polymer solar cells (PSCs) to improve power conversion efficiency (PCE). However, universality of the reported results mainly focused on utilizing single type of MNPs to enhance light absorption only in specific narrow wavelength range. Herein, a surface-energy-induced dual MNP plasmon resonance by thermally evaporating method was presented to achieve the absorption enhancement in wider range. The differences of surface energy between silver (Ag), gold (Au), and tungsten trioxide (WO3) compared by contact angle images enable Ag and Au prefer to respectively aggregate into isolated islands rather than films at the initial stage of the evaporation process, which was clearly demonstrated in the atomic force microscopy (AFM) measurement. The sum of plasmon-enhanced wavelength range induced by both Ag NPs (350-450 nm) and Au NPs (450-600 nm) almost cover the whole absorption spectra of active layers, which compatibly contribute a significant efficiency improvement from 4.57 ± 0.16 to 6.55 ± 0.12% compared to the one without MNPs. Besides, steady state photoluminescence (PL) measurements provide strong evidence that the SPR induced by the Ag-Au NPs increase the intensity of light absorption. Finally, ultraviolet photoelectron spectroscopy (UPS) reveals that doping Au and Ag causes upper shift of both the work function and valence band of WO3, which is directly related to hole collection ability. We believe the surface-energy-induced dual plasmon resonance enhancement by simple thermally evaporating technique might pave the way toward higher-efficiency PSCs.

  20. Microbiologically induced corrosion

    International Nuclear Information System (INIS)

    Stein, A.A.

    1988-01-01

    Biological attack is a problem that can affect all metallic materials in a variety of environments and systems. In the power industry, corrosion studies have focused on condensers and service water systems where slime, barnacles, clams, and other macro-organisms are easily detected. Efforts have been made to eliminate the effect of these organisms through the use of chlorination, backflushing, organic coating, or thermal shock. The objective is to maintain component performance by eliminating biofouling and reducing metallic corrosion. Recently, corrosion of power plant components by micro-organisms (bacteria) has been identified even in very clean systems. A system's first exposure to microbiologically induced corrosion (MIC) occurs during its first exposure to an aqueous environment, such as during hydrotest or wet layup. Corrosion of buried pipelines by sulfate-reducing bacteria has been studied by the petrochemical industry for years. This paper discusses various methods of diagnosing, monitoring, and controlling MIC in a variety of systems, as well as indicates areas where further study is needed

  1. Effect of substrate temperature on corrosion performance of nitrogen doped amorphous carbon thin films in NaCl solution

    Energy Technology Data Exchange (ETDEWEB)

    Khun, N.W. [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Liu, E., E-mail: MEJLiu@ntu.edu.s [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

    2009-07-01

    Nitrogen doped amorphous carbon (a-C:N) thin films were deposited on p-Si substrates by DC magnetron sputtering at varying substrate temperature from room temperature (RT) to 300 {sup o}C. The bonding structure, surface morphology and adhesion strength of the a-C:N films were investigated by using X-ray photoelectron spectroscopy (XPS), micro-Raman spectroscopy, atomic force microscopy (AFM) and micro-scratch testing. The corrosion behavior of the a-C:N films was evaluated by potentiodynamic polarization test in a 0.6 M NaCl solution. The results indicated that the corrosion resistance of the films depended on the sp{sup 3}-bonded cross-link structure that was significantly affected by the substrate temperature.

  2. Effect of substrate temperature on corrosion performance of nitrogen doped amorphous carbon thin films in NaCl solution

    International Nuclear Information System (INIS)

    Khun, N.W.; Liu, E.

    2009-01-01

    Nitrogen doped amorphous carbon (a-C:N) thin films were deposited on p-Si substrates by DC magnetron sputtering at varying substrate temperature from room temperature (RT) to 300 o C. The bonding structure, surface morphology and adhesion strength of the a-C:N films were investigated by using X-ray photoelectron spectroscopy (XPS), micro-Raman spectroscopy, atomic force microscopy (AFM) and micro-scratch testing. The corrosion behavior of the a-C:N films was evaluated by potentiodynamic polarization test in a 0.6 M NaCl solution. The results indicated that the corrosion resistance of the films depended on the sp 3 -bonded cross-link structure that was significantly affected by the substrate temperature.

  3. Effects of Dual-Task Management and Resistance Training on Gait Performance in Older Individuals: A Randomized Controlled Trial

    Science.gov (United States)

    Wollesen, Bettina; Mattes, Klaus; Schulz, Sören; Bischoff, Laura L.; Seydell, L.; Bell, Jeffrey W.; von Duvillard, Serge P.

    2017-01-01

    Background: Dual-task (DT) training is a well-accepted modality for fall prevention in older adults. DT training should include task-managing strategies such as task switching or task prioritization to improve gait performance under DT conditions. Methods: We conducted a randomized controlled trial to evaluate a balance and task managing training (BDT group) in gait performance compared to a single task (ST) strength and resistance training and a control group, which received no training. A total of 78 older individuals (72.0 ± 4.9 years) participated in this study. The DT group performed task managing training incorporating balance and coordination tasks while the ST group performed resistance training only. Training consisted of 12 weekly sessions, 60 min each, for 12 weeks. We assessed the effects of ST and BDT training on walking performance under ST and DT conditions in independent living elderly adults. ST and DT walking (visual verbal Stroop task) were measured utilizing a treadmill at self-selected walking speed (mean for all groups: 4.4 ± 1 km h-1). Specific gait variables, cognitive performance, and fear of falling were compared between all groups. >Results: Training improved gait performance for step length (p changes in cognitive performance. Both interventions reduced fear of falling (p management strategies into balance and strength training in our population revealed a promising modality to prevent falls in older individuals. Trial registration: German register of clinical trials DRKS00012382. PMID:29326581

  4. Accelerated cyclic corrosion tests

    Directory of Open Access Journals (Sweden)

    Prošek T.

    2016-06-01

    Full Text Available Accelerated corrosion testing is indispensable for material selection, quality control and both initial and residual life time prediction for bare and painted metallic, polymeric, adhesive and other materials in atmospheric exposure conditions. The best known Neutral Salt Spray (NSS test provides unrealistic conditions and poor correlation to exposures in atmosphere. Modern cyclic accelerated corrosion tests include intermittent salt spray, wet and dry phases and eventually other technical phases. They are able to predict the material performance in service more correctly as documented on several examples. The use of NSS should thus be restricted for quality control.

  5. Improved mechanical performance and delayed corrosion phenomena in biodegradable Mg-Zn-Ca alloys through Pd-alloying.

    Science.gov (United States)

    González, S; Pellicer, E; Fornell, J; Blanquer, A; Barrios, L; Ibáñez, E; Solsona, P; Suriñach, S; Baró, M D; Nogués, C; Sort, J

    2012-02-01

    The influence of partial substitution of Mg by Pd on the microstructure, mechanical properties and corrosion behaviour of Mg(72-x)Zn(23)Ca(5)Pd(x) (x=0, 2 and 6 at.%) alloys, synthesized by copper mould casting, is investigated. While the Mg(72)Zn(23)Ca(5) alloy is mainly amorphous, the addition of Pd decreases the glass-forming ability, thus favouring the formation of crystalline phases. From a mechanical viewpoint, the hardness increases with the addition of Pd, from 2.71 GPa for x=0 to 3.9 GPa for x=6, mainly due to the formation of high-strength phases. In turn, the wear resistance is maximized for an intermediate Pd content (i.e., Mg(70)Zn(23)Ca(5)Pd(2)). Corrosion tests in a simulated body fluid (Hank's solution) indicate that Pd causes a shift in the corrosion potential towards more positive values, thus delaying the biodegradability of this alloy. Moreover, since the cytotoxic studies with mouse preosteoblasts do not show dead cells after culturing for 27 h, these alloys are potential candidates to be used as biomaterials. Copyright © 2011 Elsevier Ltd. All rights reserved.

  6. Effect of hydrogen-diesel combustion on the performance and combustion parameters of a dual fuelled diesel engine

    Energy Technology Data Exchange (ETDEWEB)

    Bose, P.K.; Banerjee, Rahul; Deb, Madhujit [Mechanical Engineering Department, National Institute of Technology, Agartala, Tripura-799055 (India)

    2013-07-01

    Petroleum crude is expected to remain main source of transport fuels at least for the next 20 to 30 years. The petroleum crude reserves however, are declining and consumption of transport fuels particularly in the developing countries is increasing at high rates. Severe shortage of liquid fuels derived from petroleum may be faced in the second half of this century. In this paper, experiments are performed in a fur stroke, single cylinder, compression ignition diesel engine with dual fuel mode. Diesel and hydrogen are used as pilot liquid and primary gaseous fuel, respectively. The objective of this study is to find out the effects on combustion and performance parameters observed at diesel hydrogen fuel mixture for all the different loadings (2kg,4kg,6kg,8kg,10kg and 12kg) in the engine.

  7. Corrosion and stress corrosion cracking in supercritical water

    Science.gov (United States)

    Was, G. S.; Ampornrat, P.; Gupta, G.; Teysseyre, S.; West, E. A.; Allen, T. R.; Sridharan, K.; Tan, L.; Chen, Y.; Ren, X.; Pister, C.

    2007-09-01

    Supercritical water (SCW) has attracted increasing attention since SCW boiler power plants were implemented to increase the efficiency of fossil-based power plants. The SCW reactor (SCWR) design has been selected as one of the Generation IV reactor concepts because of its higher thermal efficiency and plant simplification as compared to current light water reactors (LWRs). Reactor operating conditions call for a core coolant temperature between 280 °C and 620 °C at a pressure of 25 MPa and maximum expected neutron damage levels to any replaceable or permanent core component of 15 dpa (thermal reactor design) and 100 dpa (fast reactor design). Irradiation-induced changes in microstructure (swelling, radiation-induced segregation (RIS), hardening, phase stability) and mechanical properties (strength, thermal and irradiation-induced creep, fatigue) are also major concerns. Throughout the core, corrosion, stress corrosion cracking, and the effect of irradiation on these degradation modes are critical issues. This paper reviews the current understanding of the response of candidate materials for SCWR systems, focusing on the corrosion and stress corrosion cracking response, and highlights the design trade-offs associated with certain alloy systems. Ferritic-martensitic steels generally have the best resistance to stress corrosion cracking, but suffer from the worst oxidation. Austenitic stainless steels and Ni-base alloys have better oxidation resistance but are more susceptible to stress corrosion cracking. The promise of grain boundary engineering and surface modification in addressing corrosion and stress corrosion cracking performance is discussed.

  8. System for corrosion monitoring in pipeline applying fuzzy logic mathematics

    Science.gov (United States)

    Kuzyakov, O. N.; Kolosova, A. L.; Andreeva, M. A.

    2018-05-01

    A list of factors influencing corrosion rate on the external side of underground pipeline is determined. Principles of constructing a corrosion monitoring system are described; the system performance algorithm and program are elaborated. A comparative analysis of methods for calculating corrosion rate is undertaken. Fuzzy logic mathematics is applied to reduce calculations while considering a wider range of corrosion factors.

  9. Corrosion inhibition

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, A O

    1965-12-29

    An acid corrosion-inhibiting composition consists essentially of a sugar, and an alkali metal salt selected from the group consisting of iodides and bromides. The weight ratio of the sugar to the alkali metal salt is between 2:1 and about 20,000:1. Also, a corrosion- inhibited phosphoric acid composition comprising at least about 20 wt% of phosphoric acid and between about 0.1 wt% and about 10 wt% of molasses, and between about 0.0005 wt% and about 1 wt% of potassium iodide. The weight ratio of molasses to iodide is greater than about 2:1. (11 claims)

  10. Corrosion and bioactivity performance of graphene oxide coating on Ti−Nb shape memory alloys in simulated body fluid

    International Nuclear Information System (INIS)

    Saud, Safaa N.; Hosseinian, Raheleh S.; Bakhsheshi-Rad, H.R.; Yaghoubidoust, F.; Iqbal, N.; Hamzah, E.; Ooi, C.H. Raymond

    2016-01-01

    In the present work, the microstructure, corrosion, and bioactivity of graphene oxide (GO) coating on the laser-modified and -unmodified surfaces of Ti−Nb shape memory alloys (SMAs) were investigated. The surface morphology and chemical composition was examined using field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). The surface modification was carried out via a femtosecond laser with the aim to increase the surface roughness, and thus increase the adhesion property. FE-SEM analysis of the laser-treated Ti-30 at.% Nb revealed the increase in surface roughness and oxygen/nitrogen containing groups on the Ti-30 at.% Nb surface after being surface modified via a femtosecond laser. Furthermore, the thickness of GO was increased from 35 μm to 45 μm after the surface was modified. Potentiodynamic polarisation and electrochemical impedance spectroscopy studies revealed that both the GO and laser/GO-coated samples exhibited higher corrosion resistance than that of the uncoated Ti−Nb SMA sample. However, the laser/GO-coated sample presented the highest corrosion resistance in SBF at 37 °C. In addition, during soaking in the simulated body fluid (SBF), both the GO and laser/GO coating improved the formation of apatite layer. Based on the bioactivity results, the GO coating exhibited a remarkable antibacterial activity against gram-negative bacteria compared with the uncoated. In conclusion, the present results indicate that Ti-30 at.% Nb SMAs may be promising alternatives to NiTi for certain biomedical applications. - Highlights: • Ti-30 at.% Nb SMA were successfully produced by PM and microwave sintering. • GO were successfully coated on the surface of TiNb. • The corrosion resistance of TiNb have enhanced after surface modification and coating of GO. • The corrosion resistance increased from 620.7 to 1,760.7 Ω cm 2 with coating of GO. • The GO and laser/GO coating induce apatite formation and enhance the bioactivity

  11. Corrosion and bioactivity performance of graphene oxide coating on Ti−Nb shape memory alloys in simulated body fluid

    Energy Technology Data Exchange (ETDEWEB)

    Saud, Safaa N., E-mail: safaaengineer@gmail.com [Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor (Malaysia); Faculty of Information Science and Engineering, Management and Science University, 40100 Shah Alam (Malaysia); Hosseinian, Raheleh S. [Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia); Bakhsheshi-Rad, H.R. [Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor (Malaysia); Advanced Materials Research Center, Faculty of Materials Engineering, NajafAbad Branch, Islamic Azad University, NajafAbad (Iran, Islamic Republic of); Yaghoubidoust, F. [Ibnu Sina Institute for Fundamental Science Studies, Universiti Teknologi Malaysia, 81310, UTM, Skudai, Johor (Malaysia); Iqbal, N. [Medical Devices & Technology Group (MEDITEG), Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor (Malaysia); Hamzah, E. [Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor (Malaysia); Ooi, C.H. Raymond [Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2016-11-01

    In the present work, the microstructure, corrosion, and bioactivity of graphene oxide (GO) coating on the laser-modified and -unmodified surfaces of Ti−Nb shape memory alloys (SMAs) were investigated. The surface morphology and chemical composition was examined using field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). The surface modification was carried out via a femtosecond laser with the aim to increase the surface roughness, and thus increase the adhesion property. FE-SEM analysis of the laser-treated Ti-30 at.% Nb revealed the increase in surface roughness and oxygen/nitrogen containing groups on the Ti-30 at.% Nb surface after being surface modified via a femtosecond laser. Furthermore, the thickness of GO was increased from 35 μm to 45 μm after the surface was modified. Potentiodynamic polarisation and electrochemical impedance spectroscopy studies revealed that both the GO and laser/GO-coated samples exhibited higher corrosion resistance than that of the uncoated Ti−Nb SMA sample. However, the laser/GO-coated sample presented the highest corrosion resistance in SBF at 37 °C. In addition, during soaking in the simulated body fluid (SBF), both the GO and laser/GO coating improved the formation of apatite layer. Based on the bioactivity results, the GO coating exhibited a remarkable antibacterial activity against gram-negative bacteria compared with the uncoated. In conclusion, the present results indicate that Ti-30 at.% Nb SMAs may be promising alternatives to NiTi for certain biomedical applications. - Highlights: • Ti-30 at.% Nb SMA were successfully produced by PM and microwave sintering. • GO were successfully coated on the surface of TiNb. • The corrosion resistance of TiNb have enhanced after surface modification and coating of GO. • The corrosion resistance increased from 620.7 to 1,760.7 Ω cm{sup 2} with coating of GO. • The GO and laser/GO coating induce apatite formation and enhance the bioactivity.

  12. Pomelo peels-derived porous activated carbon microsheets dual-doped with nitrogen and phosphorus for high performance electrochemical capacitors

    Science.gov (United States)

    Wang, Zhen; Tan, Yongtao; Yang, Yunlong; Zhao, Xiaoning; Liu, Ying; Niu, Lengyuan; Tichnell, Brandon; Kong, Lingbin; Kang, Long; Liu, Zhen; Ran, Fen

    2018-02-01

    In this work, biomass pomelo peel is used to fabricate the porous activated carbon microsheets, and diammonium hydrogen phosphate (DHP) is employed to dual-dope carbon with nitrogen and phosphorus elements. With the benefit of DHP inducement and dual-doping of nitrogen and phosphorus, the prepared carbon material has a higher carbon yield, and exhibits higher specific surface area (about 807.7 m2/g), and larger pore volume (about 0.4378 cm3/g) with hierarchically structure of interconnected thin microsheets compared to the pristine carbon. The material exhibits not only high specific capacitance (240 F/g at 0.5 A/g), but also superior cycling performance (approximately 100% of capacitance retention after 10,000 cycles at 2 A/g) in 2 M KOH aqueous electrolyte. Furthermore, the assembled symmetric electrochemical capacitor in 1 M Na2SO4 aqueous electrolyte exhibits a high energy density of 11.7 Wh/kg at a power density of 160 W/kg.

  13. High performances of dual network PVA hydrogel modified by PVP using borax as the structure-forming accelerator.

    Science.gov (United States)

    Huang, Min; Hou, Yi; Li, Yubao; Wang, Danqing; Zhang, Li

    2017-01-01

    A dual network hydrogel made up of polyvinylalcohol (PVA) crosslinked by borax and polyvinylpyrrolidone (PVP) was prepared by means of freezing-thawing circles. Here PVP was incorporated by linking with PVA to form a network structure, while the introduction of borax played the role of crosslinking PVA chains to accelerate the formation of a dual network structure in PVA/PVP composite hydrogel, thus endowing the hydrogel with high mechanical properties. The effects of both PVP and borax on the hydrogels were evaluated by comparing the two systems of PVA/PVP/borax and PVA/borax hydrogels. In the former system, adding 4.0% PVP not only increased the water content and the storage modulus but also enhanced the mechanical strength of the final hydrogel. But an overdose of PVP just as more than 4.0% tended to undermine the structure of hydrogels, and thus deteriorated hydrogels' properties because of the weakened secondary interaction between PVP and PVA. Likewise, increasing borax could promote the gel crosslinking degree, thus making gels show a decrease in water content and swelling ratio, meanwhile shrinking the pores inside the hydrogels and finally enhancing the mechanical strength of hydrogels prominently. The developed hydrogel with high performances holds great potential for applications in biomedical and industrial fields.

  14. Monitoring supports performance in a dual-task paradigm involving a risky decision-making task and a working memory task

    Directory of Open Access Journals (Sweden)

    Bettina eGathmann

    2015-02-01

    Full Text Available Performing two cognitively demanding tasks at the same time is known to decrease performance. The current study investigates the underlying executive functions of a dual-tasking situation involving the simultaneous performance of decision making under explicit risk and a working memory task. It is suggested that making a decision and performing a working memory task at the same time should particularly require monitoring - an executive control process supervising behavior and the state of processing on two tasks. To test the role of a supervisory/monitoring function in such a dual-tasking situation we investigated 122 participants with the Game of Dice Task plus 2-back task (GDT plus 2-back task. This dual task requires participants to make decisions under risk and to perform a 2-back working memory task at the same time. Furthermore, a task measuring a set of several executive functions gathered in the term concept formation (Modified Card Sorting Test, MCST and the newly developed Balanced Switching Task (BST, measuring monitoring in particular, were used. The results demonstrate that concept formation and monitoring are involved in the simultaneous performance of decision making under risk and a working memory task. In particular, the mediation analysis revealed that BST performance partially mediates the influence of MCST performance on the GDT plus 2-back task. These findings suggest that monitoring is one important subfunction for superior performance in a dual-tasking situation including decision making under risk and a working memory task.

  15. Monitoring supports performance in a dual-task paradigm involving a risky decision-making task and a working memory task

    Science.gov (United States)

    Gathmann, Bettina; Schiebener, Johannes; Wolf, Oliver T.; Brand, Matthias

    2015-01-01

    Performing two cognitively demanding tasks at the same time is known to decrease performance. The current study investigates the underlying executive functions of a dual-tasking situation involving the simultaneous performance of decision making under explicit risk and a working memory task. It is suggested that making a decision and performing a working memory task at the same time should particularly require monitoring—an executive control process supervising behavior and the state of processing on two tasks. To test the role of a supervisory/monitoring function in such a dual-tasking situation we investigated 122 participants with the Game of Dice Task plus 2-back task (GDT plus 2-back task). This dual task requires participants to make decisions under risk and to perform a 2-back working memory task at the same time. Furthermore, a task measuring a set of several executive functions gathered in the term concept formation (Modified Card Sorting Test, MCST) and the newly developed Balanced Switching Task (BST), measuring monitoring in particular, were used. The results demonstrate that concept formation and monitoring are involved in the simultaneous performance of decision making under risk and a working memory task. In particular, the mediation analysis revealed that BST performance partially mediates the influence of MCST performance on the GDT plus 2-back task. These findings suggest that monitoring is one important subfunction for superior performance in a dual-tasking situation including decision making under risk and a working memory task. PMID:25741308

  16. DPC materials and corrosion environments.

    Energy Technology Data Exchange (ETDEWEB)

    Ilgen, Anastasia Gennadyevna; Bryan, Charles R.; Teich-McGoldrick, Stephanie; Hardin, Ernest

    2014-10-01

    After an exposition of the materials used in DPCs and the factors controlling material corrosion in disposal environments, a survey is given of the corrosion rates, mechanisms, and products for commonly used stainless steels. Research needs are then identified for predicting stability of DPC materials in disposal environments. Stainless steel corrosion rates may be low enough to sustain DPC basket structural integrity for performance periods of as long as 10,000 years, especially in reducing conditions. Uncertainties include basket component design, disposal environment conditions, and the in-package chemical environment including any localized effects from radiolysis. Prospective disposal overpack materials exist for most disposal environments, including both corrosion allowance and corrosion resistant materials. Whereas the behavior of corrosion allowance materials is understood for a wide range of corrosion environments, demonstrating corrosion resistance could be more technically challenging and require environment-specific testing. A preliminary screening of the existing inventory of DPCs and other types of canisters is described, according to the type of closure, whether they can be readily transported, and what types of materials are used in basket construction.

  17. On the performance of hybrid line of sight RF and RF-FSO fixed gain dual-hop transmission systems

    KAUST Repository

    Zedini, Emna

    2014-12-01

    In this work, we carry out a unified performance analysis of a dual-branch transmission system composed of a direct radio-frequency (RF) link and a dual-hop fixed gain relay over the asymmetric links composed of both RF and unified free-space optics (FSO) under the effect of pointing errors. RF links are modeled by the Nakagami-m fading channel and the FSO link by the Gamma-Gamma fading channel subject to both types of detection techniques (i.e. heterodyne detection and intensity modulation with direct detection (IM/DD)). Selection combining (SC) and maximum ratio combining (MRC) diversity schemes are investigated. More specifically, for the SC method, we derive new unified closed-form expressions for the cumulative distribution function (CDF), the probability density function (PDF), the moment generating function (MGF), the moments, the outage probability (OP), the average bit-error rate (BER) of a variety of binary modulations, and the ergodic capacity for end-to-end signal-to-noise ratio (SNR). Additionally, using the MGF-based approach, the evaluation of the OP, the average BER, and the ergodic capacity for the MRC diversity technique can be performed based entirely on the knowledge of the MGF of the output SNR without ever having to compute its statistics (i.e. PDF and CDF). By implementing SC or MRC diversity techniques, we demonstrate a better performance of our system relative to the traditional RF path only. Also, our analysis illustrates MRC as the optimum combing method. All the analytical results are verified via computer-based Monte-Carlo simulations.

  18. Cortical Thickness Changes and Their Relationship to Dual-Task Performance following Mild Traumatic Brain Injury in Youth.

    Science.gov (United States)

    Urban, Karolina J; Riggs, Lily; Wells, Greg D; Keightley, Michelle; Chen, Jen-Kai; Ptito, Alain; Fait, Philippe; Taha, Tim; Sinopoli, Katia J

    2017-02-15

    Mild traumatic brain injury (mTBI) is common in youth, especially in those who participate in sport. Recent investigations from our group have shown that asymptomatic children and adolescents with mTBI continue to exhibit alterations in neural activity and cognitive performance compared with those without a history of mTBI. This is an intriguing finding, given that current return-to-learn and return-to-play protocols rely predominately on subjective symptom reports, which may not be sensitive enough to detect subtle injury-related changes. As a result, youth may be at greater risk for re-injury and long-term consequences if they are cleared for activity while their brains continue to be compromised. It is currently unknown whether mTBI also affects brain microstructure in the developing brain, particularly cortical thickness, and whether such changes are also related to cognitive performance. The present study examined cortical thickness in 13 asymptomatic youth (10-14 years old) who had sustained an mTBI 3-8 months prior to testing compared with 14 age-matched typically developing controls. Cortical thickness was also examined in relation to working memory performance during single and dual task paradigms. The results show that youth who had sustained an mTBI had thinner cortices in the left dorsolateral prefrontal region and right anterior and posterior inferior parietal lobes. Additionally, cortical thinning was associated with slower reaction time during the dual-task condition in the injured youth only. The results also point to a possible relationship between functional and structural alterations as a result of mTBI in youth, and lend evidence for neural changes beyond symptom resolution.

  19. A novel PV/T-air dual source heat pump water heater system: Dynamic simulation and performance characterization

    International Nuclear Information System (INIS)

    Cai, Jingyong; Ji, Jie; Wang, Yunyun; Zhou, Fan; Yu, Bendong

    2017-01-01

    Highlights: • The PV/T evaporator and air source evaporator connect in parallel and operate simultaneously. • A dynamic model is developed to simulate the behavior of the system. • The thermal and electrical characteristics of the PV/T evaporator are evaluated. • The contribution of the air source evaporator and PV/T evaporator has been discussed. - Abstract: To enable the heat pump water heater maintain efficient operation under diverse circumstances, a novel PV/T-air dual source heat pump water heater (PV/T-AHPWH) has been proposed in this study. In the PV/T-AHPWH system, a PV/T evaporator and an air source evaporator connect in parallel and operate simultaneously to recover energy from both solar energy and environment. A dynamic model is presented to simulate the behavior of the PV/T-AHPWH system. On this basis, the influences of solar irradiation, ambient temperature and packing factor have been discussed, and the contributions of air source evaporator and PV/T evaporator are evaluated. The results reveal that the system can obtain efficient operation with the average COP above 2.0 under the ambient temperature of 10 °C and solar irradiation of 100 W/m 2 . The PV/T evaporator can compensate for the performance degradation of the air source evaporator caused by the increasing condensing temperature. As the evaporating capacity in PV/T evaporator remains at relatively low level under low irradiation, the air source evaporator can play the main role of recovering heat. Comparing the performance of dual source heat pump system employing PV/T collector with that utilizing normal solar thermal collector, the system utilizing PV/T evaporator is more efficient in energy saving and performance improvement.

  20. Diagnostic performance of calcification-suppressed coronary CT angiography using rapid kilovolt-switching dual-energy CT.

    Science.gov (United States)

    Yunaga, Hiroto; Ohta, Yasutoshi; Kaetsu, Yasuhiro; Kitao, Shinichiro; Watanabe, Tomomi; Furuse, Yoshiyuki; Yamamoto, Kazuhiro; Ogawa, Toshihide

    2017-07-01

    Multi-detector-row computed tomography angiography (MDCTA) plays an important role in the assessment of patients with suspected coronary artery disease. However, MDCTA tends to overestimate stenosis in calcified coronary artery lesions. The aim of our study was to evaluate the diagnostic performance of calcification-suppressed material density (MD) images produced by using a single-detector single-source dual-energy computed tomography (ssDECT). We enrolled 67 patients with suspected or known coronary artery disease who underwent ssDECT with rapid kilovolt-switching (80 and 140 kVp). Coronary artery stenosis was evaluated on the basis of MD images and virtual monochromatic (VM) images. The diagnostic performance of the two methods for detecting coronary artery disease was compared with that of invasive coronary angiography as a reference standard. We evaluated 239 calcified segments. In all the segments, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy for detecting significant stenosis were respectively 88%, 88%, 75%, 95% and 88% for the MD images, 91%, 71%, 56%, 95% and 77% for the VM images. PPV was significantly higher on the MD images than on the VM images (P < 0.0001). Calcification-suppressed MD images improved PPV and diagnostic performance for calcified coronary artery lesions. • Computed tomography angiography tends to overestimate stenosis in calcified coronary artery. • Dual-energy CT enables us to suppress calcification of coronary artery lesions. • Calcification-suppressed material density imaging reduces false-positive diagnosis of calcified lesion.

  1. Performance and emissions of a heavy-duty diesel/LPG dual fuel engine

    Energy Technology Data Exchange (ETDEWEB)

    Schaberg, Paul [Sasol Technology, Cape Town (South Africa)

    2013-06-01

    This paper describes an investigation into the combustion characteristics and exhaust emissions of a heavy-duty truck engine which has been equipped with an aftermarket conversion kit to enable operation as a diesel/LPG (Liquefied Petroleum Gas) dual fuel engine. During operation diesel fuel is displaced by LPG which is vaporised and metered into the inlet manifold by means of solenoid injectors. It was found that, as the LPG fuelling rate is increased, the cylinder pressure rise rates and peak cylinder pressures increase, as do the carbon monoxide and unburned hydrocarbon emissions. At higher loads it was found that the LPG autoignites independently of the diesel fuel, resulting in very high rates of cylinder pressure rise. Particulate and nitrogen oxide emissions remain largely unchanged, and carbon dioxide emissions are reduced due to the lower carbon content of the LPG fuel. Different LPG compositions were also investigated and it was found that the LPG properties that have the most significant effect on combustion and emissions were the autoignition and volatility characteristics. (orig.)

  2. Mechanical Performance Evaluation of a Top End Piece for Dual Cooled Fuels

    International Nuclear Information System (INIS)

    Kim, Jae Yong; Yoon, Kyung Ho; Kim, Hyung Kyu; Choi, Woo Seok

    2011-01-01

    A fuel assembly consists of five major components, i.e., a top end piece (TEP), a bottom end piece (BEP), spacer grids (SGs), guide tubes (GTs) and an instrumentation tube (IT): in addition, it also includes fuel rods (FRs). The TEP/BEP should satisfy stress intensity limits according to the conditions A and B of ASME, Section III, Division 1.Subsection NB. In a dual-cooled fuel assembly, the array and position of fuel rods are different from those in a conventional PWR fuel assembly; these changes are necessary for achieving power uprating. The flow plates of the TEP and BEP have to be modified accordingly. The pattern and shape of the flow holes were newly designed. To verify the strength compatibility, the Tresca stress limit according to the ASME code was investigated in the case of an axial load of 22.241 kN. In this paper, the stress linearization procedure for strength evaluation of a newly designed TEP is presented

  3. Corrosion inhibitors

    International Nuclear Information System (INIS)

    El Ashry, El Sayed H.; El Nemr, Ahmed; Esawy, Sami A.; Ragab, Safaa

    2006-01-01

    The corrosion inhibition efficiencies of some triazole, oxadiazole and thiadiazole derivatives for steel in presence of acidic medium have been studied by using AM1, PM3, MINDO/3 and MNDO semi-empirical SCF molecular orbital methods. Geometric structures, total negative charge on the molecule (TNC), highest occupied molecular energy level (E HOMO ), lowest unoccupied molecular energy level (E LUMO ), core-core repulsion (CCR), dipole moment (μ) and linear solvation energy terms, molecular volume (V i ) and dipolar-polarization (π *), were correlated to corrosion inhibition efficiency. Four equations were proposed to calculate corrosion inhibition efficiency. The agreement with the experimental data was found to be satisfactory; the standard deviations between the calculated and experimental results ranged between ±0.03 and ±4.18. The inhibition efficiency was closely related to orbital energies (E HOMO and E LUMO ) and μ. The correlation between quantum parameters and experimental inhibition efficiency has been validated by single point calculations for the semi-empirical AM1 structures using B3LYP/6-31G** as a higher level of theory. The proposed equations were applied to predict the corrosion inhibition efficiency of some related structures to select molecules of possible activity from a presumable library of compounds

  4. A fast dual wavelength laser beam fluid-less optical CT scanner for radiotherapy 3D gel dosimetry II: dosimetric performance

    Science.gov (United States)

    Ramm, Daniel

    2018-02-01

    New clinical radiotherapy dosimetry systems need comprehensive demonstration of measurement quality. Practicality and reliability are other important aspects for clinical dosimeters. In this work the performance of an optical CT scanner for true 3D dosimetry is assessed using a radiochromic gel dosimeter. The fluid-less scanner utilised dual lasers to avoid the necessity for pre-irradiation scans and give greater robustness of image quality, enhancing practicality. Calibration methods using both cuvettes and reconstructed volumes were developed. Dosimetric accuracy was similar for dual and single wavelength measurements, except that cuvette calibration reliability was reduced for dual wavelength without pre-irradiation scanning. Detailed performance parameters were specified for the dosimetry system indicating the suitability for clinical use. The most significant limitations of the system were due to the gel dosimeter rather than the optical CT scanner. Quality assurance guidelines were developed to maintain dosimetry system performance in routine use.

  5. Underground pipeline corrosion

    CERN Document Server

    Orazem, Mark

    2014-01-01

    Underground pipelines transporting liquid petroleum products and natural gas are critical components of civil infrastructure, making corrosion prevention an essential part of asset-protection strategy. Underground Pipeline Corrosion provides a basic understanding of the problems associated with corrosion detection and mitigation, and of the state of the art in corrosion prevention. The topics covered in part one include: basic principles for corrosion in underground pipelines, AC-induced corrosion of underground pipelines, significance of corrosion in onshore oil and gas pipelines, n

  6. Exact Performance Analysis of Dual-Hop Semi-Blind AF Relaying over Arbitrary Nakagami-m Fading Channels

    KAUST Repository

    Xia, Minghua; Xing, Chengwen; Wu, Yik-Chung; Aissa, Sonia

    2011-01-01

    Relay transmission is promising for future wireless systems due to its significant cooperative diversity gain. The performance of dual-hop semi-blind amplify-and-forward (AF) relaying systems was extensively investigated, for transmissions over Rayleigh fading channels or Nakagami-𝑚 fading channels with integer fading parameter. For the general Nakagami-𝑚 fading with arbitrary 𝑚 values, the exact closed-form system performance analysis is more challenging. In this paper, we explicitly derive the moment generation function (MGF), probability density function (PDF) and moments of the end-to-end signal-to-noise ratio (SNR) over arbitrary Nakagami-𝑚 fading channels with semi-blind AF relay. With these results, the system performance evaluation in terms of outage probability, average symbol error probability, ergodic capacity and diversity order, is conducted. The analysis developed in this paper applies to any semi-blind AF relaying systems with fixed relay gain, and two major strategies for computing the relay gain are compared in terms of system performance. All analytical results are corroborated by simulation results and they are shown to be efficient tools to evaluate system performance.

  7. How do leader-member exchange quality and differentiation affect performance in teams? An integrated multilevel dual process model.

    Science.gov (United States)

    Li, Alex Ning; Liao, Hui

    2014-09-01

    Integrating leader-member exchange (LMX) research with role engagement theory (Kahn, 1990) and role system theory (Katz & Kahn, 1978), we propose a multilevel, dual process model to understand the mechanisms through which LMX quality at the individual level and LMX differentiation at the team level simultaneously affect individual and team performance. With regard to LMX differentiation, we introduce a new configural approach focusing on the pattern of LMX differentiation to complement the traditional approach focusing on the degree of LMX differentiation. Results based on multiphase, multisource data from 375 employees of 82 teams revealed that, at the individual level, LMX quality positively contributed to customer-rated employee performance through enhancing employee role engagement. At the team level, LMX differentiation exerted negative influence on teams' financial performance through disrupting team coordination. In particular, teams with the bimodal form of LMX configuration (i.e., teams that split into 2 LMX-based subgroups with comparable size) suffered most in team performance because they experienced greatest difficulty in coordinating members' activities. Furthermore, LMX differentiation strengthened the relationship between LMX quality and role engagement, and team coordination strengthened the relationship between role engagement and employee performance. Theoretical and practical implications of the findings are discussed. PsycINFO Database Record (c) 2014 APA, all rights reserved.

  8. Exact Performance Analysis of Dual-Hop Semi-Blind AF Relaying over Arbitrary Nakagami-m Fading Channels

    KAUST Repository

    Xia, Minghua

    2011-10-01

    Relay transmission is promising for future wireless systems due to its significant cooperative diversity gain. The performance of dual-hop semi-blind amplify-and-forward (AF) relaying systems was extensively investigated, for transmissions over Rayleigh fading channels or Nakagami- fading channels with integer fading parameter. For the general Nakagami- fading with arbitrary values, the exact closed-form system performance analysis is more challenging. In this paper, we explicitly derive the moment generation function (MGF), probability density function (PDF) and moments of the end-to-end signal-to-noise ratio (SNR) over arbitrary Nakagami- fading channels with semi-blind AF relay. With these results, the system performance evaluation in terms of outage probability, average symbol error probability, ergodic capacity and diversity order, is conducted. The analysis developed in this paper applies to any semi-blind AF relaying systems with fixed relay gain, and two major strategies for computing the relay gain are compared in terms of system performance. All analytical results are corroborated by simulation results and they are shown to be efficient tools to evaluate system performance.

  9. Intraoperative tumor detection: Relative performance of single-element, dual-element, and imaging probes with various collimators

    International Nuclear Information System (INIS)

    Hartsough, N.E.; Barrett, H.H.; Barber, H.B.; Woolfenden, J.M.

    1995-01-01

    Accurate tumor staging depends on finding all tumor sites, and curative surgery requires the removal of all cancerous tissue from those sites. One technique for locating tumors is to inject patients before surgery with a radiotracer that is preferentially taken up by cancerous tissue. Then, an intraoperative gamma-sensitive probe is used to locate the tumors. Small (< 1-cm diameter) tumors, often undetectable by external imaging and by the standard surgical inspection with sight and touch, can be found with probes. Simple calculations and measurements with radioactive tumor models show that small tumors should be detected by single-element probes, but often such probes fail to detect these small tumors in practice. This discrepancy is often caused by the use of a uniform background to predict probe performance. Real backgrounds are nonuniform and can decrease probe performance dramatically. Dual-element, coincidence, or imaging probes may solve the background problem. The authors devised a method to predict probe performance in a realistic background which includes variations in normal organ uptakes. They predict the relative performance of both existing probes and those in the design stage so that optimal detector and collimator configurations can be determined. The procedure includes a Monte-Carlo-calculated point-response function, a numerical torso phantom, and measured biodistribution of a monoclonal antibody. The Hotelling Trace Value, a measure of tumor-detection performance, is computed from the probe responses in simulated studies

  10. Oxidative degradation stability and hydrogen sulfide removal performance of dual-ligand iron chelate of Fe-EDTA/CA.

    Science.gov (United States)

    Miao, Xinmei; Ma, Yiwen; Chen, Zezhi; Gong, Huijuan

    2017-09-05

    Catalytic oxidation desulfurization using chelated iron catalyst is an effective method to remove H 2 S from various gas streams including biogas. However, the ligand of ethylenediaminetetraacetic acid (EDTA), which is usually adopted to prepare chelated iron catalyst, is liable to be oxidative degraded, and leads to the loss of desulfurization performance. In order to improve the degradation stability of the iron chelate, a series of iron chelates composed of two ligands including citric acid (CA) and EDTA were prepared and the oxidative degradation stability as well as desulfurization performance of these chelated iron catalysts were studied. Results show that the iron chelate of Fe-CA is more stable than Fe-EDTA, while for the desulfurization performance, the situation is converse. For the dual-ligand iron chelates of Fe-EDTA/CA, with the increase of mol ratio of CA to EDTA in the iron chelate solution, the oxidative degradation stability increased while the desulfurization performance decreased. The results of this work showed that Fe-EDTA/CA with a mol ratio of CA:EDTA = 1:1 presents a relative high oxidative degradation stability and an acceptable desulfurization performance with over 90% of H 2 S removal efficiency.

  11. Corrosion and bioactivity performance of graphene oxide coating on TiNb shape memory alloys in simulated body fluid.

    Science.gov (United States)

    Saud, Safaa N; Hosseinian S, Raheleh; Bakhsheshi-Rad, H R; Yaghoubidoust, F; Iqbal, N; Hamzah, E; Ooi, C H Raymond

    2016-11-01

    In the present work, the microstructure, corrosion, and bioactivity of graphene oxide (GO) coating on the laser-modified and -unmodified surfaces of TiNb shape memory alloys (SMAs) were investigated. The surface morphology and chemical composition was examined using field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). The surface modification was carried out via a femtosecond laser with the aim to increase the surface roughness, and thus increase the adhesion property. FE-SEM analysis of the laser-treated Ti-30at.% Nb revealed the increase in surface roughness and oxygen/nitrogen containing groups on the Ti-30at.% Nb surface after being surface modified via a femtosecond laser. Furthermore, the thickness of GO was increased from 35μm to 45μm after the surface was modified. Potentiodynamic polarisation and electrochemical impedance spectroscopy studies revealed that both the GO and laser/GO-coated samples exhibited higher corrosion resistance than that of the uncoated TiNb SMA sample. However, the laser/GO-coated sample presented the highest corrosion resistance in SBF at 37°C. In addition, during soaking in the simulated body fluid (SBF), both the GO and laser/GO coating improved the formation of apatite layer. Based on the bioactivity results, the GO coating exhibited a remarkable antibacterial activity against gram-negative bacteria compared with the uncoated. In conclusion, the present results indicate that Ti-30at.% Nb SMAs may be promising alternatives to NiTi for certain biomedical applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Nanostructure and Properties of Corrosion Resistance in C+Ti Multi-Ion-Implanted Steel

    Institute of Scientific and Technical Information of China (English)

    张通和; 吴瑜光; 刘安东; 张旭; 王晓妍

    2003-01-01

    The corrosion and pitting corrosion resistance of C+ Ti dual and C+Ti+C ternary implanted H13 steel were studied by using a multi-sweep cyclic voltammetry and a scanning electron microscope. The effects of phase formation on corrosion and pitting corrosion resistance were explored. The x-ray diffraction analysis shows that the nanometer-sized precipitate phases consist of compounds of Fe2 Ti, TiC, Fe2C and Fe3 C in dual implanted layer and even in ternary implanted layer. The passivation layer consists of these nanometer phases. It has been found that the corrosion and pitting corrosion resistance of dual and ternary implanted H13 steel are improved extremely. The corrosion resistance of ternary implanted layer is better than that of dual implantations and is enhanced with the increasing ion dose. When the ion dose of Ti is 6 × 1017/cm2 in the ternary implantation sample, the anodic peak current density is 95 times less than that of the H13 steel. The pitting corrosion potential of dual and ternary implantation samples is in the range from 55mV to 160mV which is much higher than that of the H13 steel. The phases against the corrosion and pitting corrosion are nanometer silkiness phases.

  13. Impact of Pointing Errors on the Performance of Mixed RF/FSO Dual-Hop Transmission Systems

    KAUST Repository

    Ansari, Imran Shafique; Alouini, Mohamed-Slim; Yilmaz, Ferkan

    2013-01-01

    In this work, the performance analysis of a dual-hop relay transmission system composed of asymmetric radio-frequency (RF)/free-space optical (FSO) links with pointing errors is presented. More specifically, we build on the system model presented in [1] to derive new exact closed-form expressions for the cumulative distribution function, probability density function, moment generating function, and moments of the end-to-end signal-to-noise ratio in terms of the Meijer's G function. We then capitalize on these results to offer new exact closed-form expressions for the higher-order amount of fading, average error rate for binary and M-ary modulation schemes, and the ergodic capacity, all in terms of Meijer's G functions. Our new analytical results were also verified via computer-based Monte-Carlo simulation results.

  14. Theoretical and experimental investigations on the performance of dual fuel diesel engine with hydrogen and LPG as secondary fuels

    Energy Technology Data Exchange (ETDEWEB)

    Lata, D.B.; Misra, Ashok [Department of Mechanical Engineering, Birla Institute of Technology, Mesra, Ranchi 835215 (India)

    2010-11-15

    The mathematical models to predict pressure, net heat release rate, mean gas temperature, and brake thermal efficiency for dual fuel diesel engine operated on hydrogen, LPG and mixture of LPG and hydrogen as secondary fuels are developed. In these models emphasis have been given on spray mixing characteristics, flame propagation, equilibrium combustion products and in-cylinder processes, which were computed using empirical equations and compared with experimental results. This combustion model predicts results which are in close agreement with the results of experiments conducted on a multi cylinder turbocharged, intercooled gen-set diesel engine. The predictions are also in close agreement with the results on single cylinder diesel engine obtained by other researchers. A reasonable agreement between the predicted and experimental results reveals that the presented model gives quantitatively and qualitatively realistic prediction of in-cylinder processes and engine performances during combustion. (author)

  15. Impact of Pointing Errors on the Performance of Mixed RF/FSO Dual-Hop Transmission Systems

    KAUST Repository

    Ansari, Imran Shafique

    2013-02-20

    In this work, the performance analysis of a dual-hop relay transmission system composed of asymmetric radio-frequency (RF)/free-space optical (FSO) links with pointing errors is presented. More specifically, we build on the system model presented in [1] to derive new exact closed-form expressions for the cumulative distribution function, probability density function, moment generating function, and moments of the end-to-end signal-to-noise ratio in terms of the Meijer\\'s G function. We then capitalize on these results to offer new exact closed-form expressions for the higher-order amount of fading, average error rate for binary and M-ary modulation schemes, and the ergodic capacity, all in terms of Meijer\\'s G functions. Our new analytical results were also verified via computer-based Monte-Carlo simulation results.

  16. Dividing attention between tasks : Testing whether explicit payoff functions elicit optimal dual-task performance

    NARCIS (Netherlands)

    Farmer, George D.; Janssen, C.P.|info:eu-repo/dai/nl/412781654; Nguyen, Anh T; Brumby, Duncan P.

    2018-01-01

    We test people's ability to optimize performance across two concurrent tasks. Participants performed a number entry task while controlling a randomly moving cursor with a joystick. Participants received explicit feedback on their performance on these tasks in the form of a single combined score.

  17. Deployment and Performance of an X-Band Dual-Polarization Radar during the Southern China Monsoon Rainfall Experiment

    Directory of Open Access Journals (Sweden)

    Zhao Shi

    2017-12-01

    Full Text Available An X-band dual-polarization radar (XPRAD was deployed in Guangdong province as part of the Southern China Monsoon Rainfall Experiment (SCMREX during the storm season in 2016. This paper presents a comprehensive assessment of XPRAD observations during SCMREX with emphasis on data processing and rainfall products. The differential phase-based attenuation correction and radar calibration using self-consistency of dual-polarization observables are presented. It is found that the standard deviation of the Z d r bias is less than 0.2 dB based on ‘light rain at low angle’ and ‘dry aggregate snow’ observations. Cross-comparison with two standard S-band China New Generation Weather Radars (CINRAD shows that the bias of Z h has a mean value less than 1.5 dBZ and a standard deviation less than 0.5 dBZ. In addition, fifteen rainfall events that occurred during the intensive observing period (IOP are analyzed to demonstrate the rainfall estimation performance of XPRAD. In particular, rainfall accumulations at 1-, 2- and 3-h scales derived using R( K d p and R( Z h , Z d r relations are evaluated using national level rain gauge data and CINRAD-based rainfall estimation. The results show that both R( K d p - and R( Z h , Z d r -based products agree well with the rain gauge observations and CINRAD estimation. The difference between R ( K d p and R ( Z h , Z d r is not significant, although R ( K d p shows slightly better performance than R ( Z h , Z d r .

  18. Comparison of model and human observer performance for detection and discrimination tasks using dual-energy x-ray images

    International Nuclear Information System (INIS)

    Richard, Samuel; Siewerdsen, Jeffrey H.

    2008-01-01

    Model observer performance, computed theoretically using cascaded systems analysis (CSA), was compared to the performance of human observers in detection and discrimination tasks. Dual-energy (DE) imaging provided a wide range of acquisition and decomposition parameters for which observer performance could be predicted and measured. This work combined previously derived observer models (e.g., Fisher-Hotelling and non-prewhitening) with CSA modeling of the DE image noise-equivalent quanta (NEQ) and imaging task (e.g., sphere detection, shape discrimination, and texture discrimination) to yield theoretical predictions of detectability index (d ' ) and area under the receiver operating characteristic (A Z ). Theoretical predictions were compared to human observer performance assessed using 9-alternative forced-choice tests to yield measurement of A Z as a function of DE image acquisition parameters (viz., allocation of dose between the low- and high-energy images) and decomposition technique [viz., three DE image decomposition algorithms: standard log subtraction (SLS), simple-smoothing of the high-energy image (SSH), and anti-correlated noise reduction (ACNR)]. Results showed good agreement between theory and measurements over a broad range of imaging conditions. The incorporation of an eye filter and internal noise in the observer models demonstrated improved correspondence with human observer performance. Optimal acquisition and decomposition parameters were shown to depend on the imaging task; for example, ACNR and SSH yielded the greatest performance in the detection of soft-tissue and bony lesions, respectively. This study provides encouraging evidence that Fourier-based modeling of NEQ computed via CSA and imaging task provides a good approximation to human observer performance for simple imaging tasks, helping to bridge the gap between Fourier metrics of detector performance (e.g., NEQ) and human observer performance.

  19. Corrosion/95 conference papers

    International Nuclear Information System (INIS)

    Anon.

    1995-01-01

    The papers in this conference represent the latest technological advances in corrosion control and prevention. The following subject areas are covered: cathodic protection in natural waters; materials for fossil fuel combustion and conversion systems; modern problems in atmospheric corrosion; innovative ideas for controlling the decaying infrastructure; deposits and their effects on corrosion in industry; volatile high temperature and non aqueous corrosion inhibitors; corrosion of light-weight and precoated metals for automotive application; refining industry corrosion; corrosion in pulp and paper industry; arctic/cold weather corrosion; materials selection for waste incinerators and associated equipment; corrosion measurement technology; environmental cracking of materials; advancing technology in the coating industry; corrosion in gas treating; green inhibition; recent advances in corrosion control of rail equipment; velocity effects and erosion corrosion in oil and gas production; marine corrosion; corrosion of materials in nuclear systems; underground corrosion control; corrosion in potable and industrial water systems in buildings and its impact on environmental compliance; deposit related boiler tube failures; boiler systems monitoring and control; recent developments and experiences in reactive metals; microbiologically influenced corrosion; corrosion and corrosion control for steel reinforced concrete; international symposium on the use of 12 and 13 Cr stainless steels in oil and gas production environments; subsea corrosion /erosion monitoring in production facilities; fiberglass reinforced pipe and tubulars in oilfield service; corrosion control technology in power transmission and distribution; mechanisms and methods of scale and deposit control; closing the loop -- results oriented cooling system monitoring and control; and minimization of aqueous discharge

  20. [Dual pathology].

    Science.gov (United States)

    Rougier, A

    2008-05-01

    Dual pathology is defined as the association of two potentially epileptogenic lesions, hippocampal (sclerosis, neuronal loss) and extrahippocampal (temporal or extratemporal). Epileptic activity may be generated by either lesion and the relative importance of every lesion's epileptogenicity conditions the surgical strategy adopted. Most frequently associated with hippocampal sclerosis are cortical dysplasias. The common physiopathology of the two lesions is not clearly established. Extrahippocampal lesions may be undetectable on MRI (microdysgenesis, for example) and ictal discharge patterns may vary among dual pathology patients. The surgical strategy depends on the location of the extrahippocampal lesion and its relative role in seizure generation; however, reported surgical results suggest that simultaneous resection of mesial temporal structures along with the extrahippocampal lesion should be performed.

  1. Plasma thermal performance of a dual-process PVD/PS tungsten coating on carbon-based panels for nuclear fusion application

    International Nuclear Information System (INIS)

    Kim, Hyunmyung; Lee, Ho Jung; Kim, Sung Hwan; Jang, Changheui

    2016-01-01

    Highlights: • Plasma thermal performance of a dual-process PVD/PS W coating was evaluated. • Steady-state heat fluxes of 1–3 MW/m 2 were applied to the W coated specimens. • Less micro-pores and grain growth were observed for the dual-process coating. • Loss of coating thickness was observed for the simple PS W coating. • Dual-process PVD/PS W coating was resistant to erosion due to the surface PVD layer. - Abstract: Various tungsten (W) coating techniques have been used for the application of plasma facing material in nuclear fusion devices, which resulted in limited success. In this study, a dual-process W coating structure was developed on a graphite substrate to improve the thermal performance of the coating structure. The dual-process coating structure consisted of a thin (∼7 μm) multilayer W/Mo physical vapor deposition (PVD) coating layer deposited on top of the relatively thick (∼160 μm) plasma spray (PS) W coating on a graphite substrate panel. Then the coated sample was exposed to plasma heat flux of 1–3 MW/m 2 for 300 s. With addition of a thin surface PVD coating layer, the microstructure change in underlying PS W coating was substantially reduced compared to the simple PS W coating structure. The thickness of overall coating structure was maintained for the dual-process PVD/PS coated samples after the thermal loading tests, while a significant reduction in thickness due to surface erosion was observed for the simple PS W coated samples. The improvement in surface erosion resistance in the dual-process coating structure was discussed in view of the characteristics of PVD and PS coating layers.

  2. Plasma thermal performance of a dual-process PVD/PS tungsten coating on carbon-based panels for nuclear fusion application

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyunmyung; Lee, Ho Jung; Kim, Sung Hwan; Jang, Changheui, E-mail: chjang@kaist.ac.kr

    2016-11-01

    Highlights: • Plasma thermal performance of a dual-process PVD/PS W coating was evaluated. • Steady-state heat fluxes of 1–3 MW/m{sup 2} were applied to the W coated specimens. • Less micro-pores and grain growth were observed for the dual-process coating. • Loss of coating thickness was observed for the simple PS W coating. • Dual-process PVD/PS W coating was resistant to erosion due to the surface PVD layer. - Abstract: Various tungsten (W) coating techniques have been used for the application of plasma facing material in nuclear fusion devices, which resulted in limited success. In this study, a dual-process W coating structure was developed on a graphite substrate to improve the thermal performance of the coating structure. The dual-process coating structure consisted of a thin (∼7 μm) multilayer W/Mo physical vapor deposition (PVD) coating layer deposited on top of the relatively thick (∼160 μm) plasma spray (PS) W coating on a graphite substrate panel. Then the coated sample was exposed to plasma heat flux of 1–3 MW/m{sup 2} for 300 s. With addition of a thin surface PVD coating layer, the microstructure change in underlying PS W coating was substantially reduced compared to the simple PS W coating structure. The thickness of overall coating structure was maintained for the dual-process PVD/PS coated samples after the thermal loading tests, while a significant reduction in thickness due to surface erosion was observed for the simple PS W coated samples. The improvement in surface erosion resistance in the dual-process coating structure was discussed in view of the characteristics of PVD and PS coating layers.

  3. A Combined Cognitive Stimulation and Physical Exercise Programme (MINDVital) in Early Dementia: Differential Effects on Single- and Dual-Task Gait Performance.

    Science.gov (United States)

    Tay, Laura; Lim, Wee Shiong; Chan, Mark; Ali, Noorhazlina; Chong, Mei Sian

    2016-01-01

    Gait disorders are common in early dementia, with particularly pronounced dual-task deficits, contributing to the increased fall risk and mobility decline associated with cognitive impairment. This study examines the effects of a combined cognitive stimulation and physical exercise programme (MINDVital) on gait performance under single- and dual-task conditions in older adults with mild dementia. Thirty-nine patients with early dementia participated in a multi-disciplinary rehabilitation programme comprising both physical exercise and cognitive stimulation. The programme was conducted in 8-week cycles with participants attending once weekly, and all participants completed 2 successive cycles. Cognitive, functional performance and behavioural symptoms were assessed at baseline and at the end of each 8-week cycle. Gait speed was examined under both single- (Timed Up and Go and 6-metre walk tests) and dual-task (animal category and serial counting) conditions. A random effects model was performed for the independent effect of MINDVital on the primary outcome variable of gait speed under dual-task conditions. The mean age of patients enroled in the rehabilitation programme was 79 ± 6.2 years; 25 (64.1%) had a diagnosis of Alzheimer's dementia, and 26 (66.7%) were receiving a cognitive enhancer therapy. There was a significant improvement in cognitive performance [random effects coefficient (standard error) = 0.90 (0.31), p = 0.003] and gait speed under both dual-task situations [animal category: random effects coefficient = 0.04 (0.02), p = 0.039; serial counting: random effects coefficient = 0.05 (0.02), p = 0.013], with reduced dual-task cost for gait speed [serial counting: random effects coefficient = -4.05 (2.35), p = 0.086] following successive MINDVital cycles. No significant improvement in single-task gait speed was observed. Improved cognitive performance over time was a significant determinant of changes in dual-task gait speed [random effects coefficients

  4. Effects of Dual-Task Management and Resistance Training on Gait Performance in Older Individuals: A Randomized Controlled Trial

    Directory of Open Access Journals (Sweden)

    Bettina Wollesen

    2017-12-01

    Full Text Available Background: Dual-task (DT training is a well-accepted modality for fall prevention in older adults. DT training should include task-managing strategies such as task switching or task prioritization to improve gait performance under DT conditions.Methods: We conducted a randomized controlled trial to evaluate a balance and task managing training (BDT group in gait performance compared to a single task (ST strength and resistance training and a control group, which received no training. A total of 78 older individuals (72.0 ± 4.9 years participated in this study. The DT group performed task managing training incorporating balance and coordination tasks while the ST group performed resistance training only. Training consisted of 12 weekly sessions, 60 min each, for 12 weeks. We assessed the effects of ST and BDT training on walking performance under ST and DT conditions in independent living elderly adults. ST and DT walking (visual verbal Stroop task were measured utilizing a treadmill at self-selected walking speed (mean for all groups: 4.4 ± 1 km h-1. Specific gait variables, cognitive performance, and fear of falling were compared between all groups.>Results: Training improved gait performance for step length (p < 0.001 and gait-line (ST: p < 0.01; DT p < 0.05 in both training groups. The BDT training group showed greater improvements in step length (p < 0.001 and gait-line (p < 0.01 during DT walking but did not have changes in cognitive performance. Both interventions reduced fear of falling (p < 0.05.Conclusion: Implementation of task management strategies into balance and strength training in our population revealed a promising modality to prevent falls in older individuals.Trial registration: German register of clinical trials DRKS00012382.

  5. Changes in dual-task performance after 5 months of karate and fitness training for older adults to enhance fall prevention.

    Science.gov (United States)

    Pliske, Gerald; Emmermacher, Peter; Weinbeer, Veronika; Witte, Kerstin

    2016-12-01

    Demographic changes resulting in an aging population are major factors for an increase of fall-related injuries. Especially in situations where dual tasks such as walking whilst talking have to be performed simultaneously the risk of a fall-related injury increases. It is well known that some types of martial art (e.g. Tai Chi) can reduce the risk of a fall. It is unknown if the same is true for karate. In this randomized, controlled study 68 people with a mean age of 69 years underwent 5-month karate training, 5-month fitness training or were part of a control group. Before and after the time of intervention a gait analysis with normal walk, a cognitive dual task and a motor dual task were performed. The gait parameter step frequency, walking speed, single-step time and single-step length were investigated. It could be seen that all groups improved their gait parameters after a 5-month period, even the control group. A sporty intervention seems to affect mainly the temporal gait parameters positively. This effect was especially demonstrated for normal walk and cognitive dual task. An improvement of the human walk seems to be possible through karate and fitness training, even under dual-task conditions. A prolonged intervention time with multiple repetitions of gait analysis could give better evidence if karate is a useful tool to increase fall prevention.

  6. Planning and task management in Parkinson's disease: differential emphasis in dual-task performance.

    Science.gov (United States)

    Bialystok, Ellen; Craik, Fergus I M; Stefurak, Taresa

    2008-03-01

    Seventeen patients diagnosed with Parkinson's disease completed a complex computer-based task that involved planning and management while also performing an attention-demanding secondary task. The tasks were performed concurrently, but it was necessary to switch from one to the other. Performance was compared to a group of healthy age-matched control participants and a group of young participants. Parkinson's patients performed better than the age-matched controls on almost all measures and as well as the young controls in many cases. However, the Parkinson's patients achieved this by paying relatively less attention to the secondary task and focusing attention more on the primary task. Thus, Parkinson's patients can apparently improve their performance on some aspects of a multidimensional task by simplifying task demands. This benefit may occur as a consequence of their inflexible exaggerated attention to some aspects of a complex task to the relative neglect of other aspects.

  7. Corrosion engineering in nuclear power industry

    International Nuclear Information System (INIS)

    Prazak, M.; Tlamsa, J.; Jirousova, D.; Silber, K.

    1990-01-01

    Corrosion problems in nuclear power industry are discussed from the point of view of anticorrosion measures, whose aim is not only increasing the lifetime of the equipment but, first of all, securing ecological safety. A brief description is given of causes of corrosion damage that occurred at Czechoslovak nuclear power plants and which could have been prevented. These involve the corrosion of large-volume radioactive waste tanks made of the CSN 17247 steel and of waste piping of an ion exchange station made of the same material, a crack in a steam generator collector, contamination of primary circuit water with iron, and corrosion of CrNi corrosion-resistant steel in a spent fuel store. It is concluded that if a sufficient insight into the corrosion relationships exists and a reasonable volume of data is available concerning the corrosion state during the nuclear facility performance, the required safety can be achieved without adopting extremely costly anticorrosion measures. (Z.M.)

  8. O desempenho da dupla tarefa na Doença de Parkinson The dual task performance in Parkinson's disease

    Directory of Open Access Journals (Sweden)

    NB Teixeira

    2007-04-01

    Full Text Available INTRODUÇÃO: A capacidade de o indivíduo realizar duas tarefas ao mesmo tempo é um pré-requisito para uma vida normal. Em circunstâncias normais, a realização concomitante de tarefas motoras e cognitivas é comum. OBJETIVO: O objetivo deste estudo foi analisar o desempenho de pacientes com Doença de Parkinson na realização de dupla tarefa motora-cognitiva. MÉTODO: Dois grupos foram estudados. Um grupo foi composto por 10 indivíduos saudáveis e o outro por 10 pacientes com diagnóstico de Doença de Parkinson, ambos com idades entre 47 e 75 anos, pareados em relação ao gênero e idade. Foi solicitado que vestissem uma camisa de botões o mais rapidamente possível de forma isolada (tarefa simples e enquanto verbalizavam nomes próprios femininos (dupla tarefa, em ordem aleatória. Cada tarefa foi repetida três vezes. O tempo de movimento e os erros cometidos foram analisados. RESULTADOS: Os pacientes levaram mais tempo para completar ambas as tarefas (p= 0,006 quando comparados aos indivíduos saudáveis. Ambos os grupos cometeram mais erros na dupla tarefa (p= 0,03. Houve uma redução no tempo de movimento com a repetição da tarefa (p= 0,039. CONCLUSÕES: Estes resultados sugerem que indivíduos com Doença de Parkinson apresentam um prejuízo no desempenho motor em relação ao grupo controle, no entanto, o custo para o desempenho desta tarefa independe da interferência motora-cogntiva e a possibilidade de melhora do desempenho com a prática é real.INTRODUCTION: A capacity to perform two tasks at the same time is a prerequisite for an individual to have a normal life. Under normal circumstances, performing motor and cognitive tasks concomitantly is common. OBJECTIVE: The aim of this study was investigate the motor-cognitive dual task performance in Parkinson's disease patients. METHOD: Two groups were studied. One group was composed by 10 healthy individuals and the other by 10 patients with a diagnosis of Parkinson

  9. A dual fired downdraft gasifier system to produce cleaner gas for power generation: Design, development and performance analysis

    International Nuclear Information System (INIS)

    Raman, P.; Ram, N.K.; Gupta, Ruchi

    2013-01-01

    The existing biomass gasifier systems have several technical challenges, which need to be addressed. They are reduction of impurities in the gas, increasing the reliability of the system, easy in operation and maintenance. It is also essential to have a simple design of gasifier system for power generation, which can work even in remote locations. A dual fired downdraft gasifier system was designed to produce clean gas from biomass fuel, used for electricity generation. This system is proposed to overcome a number of technical challenges. The system is equipped with dry gas cleaning and indirect gas cooling equipment. The dry gas cleaning system completely eliminates wet scrubbers that require large quantities of water. It also helps to do away with the disposal issues with the polluted water. With the improved gasifier system, the tar level in the raw gas is less than 100 mg Nm −3 .Cold gas efficiency has improved to 89% by complete gasification of biomass and recycling of waste heat into the reactor. Several parameters, which are considered in the design and development of the reactors, are presented in detail with their performance indicators. - Highlights: • Hot air injection in dual fired reactor reduces the tar content to less than 100 mg Nm −3 . • In clean gas the tar content is 35 mg Nm −3 and the dust content is nil. • The specific gasification rate is 2.8 Nm 3 kg −1 of fuel wood and cold gas efficiency is 89.7%. • CV of the gas: 5.3 MJ Nm −3 , SFC: 1.1 kg kWh −1 and wood to power efficiency: 21%. • Cold gas efficiency is improved by optimizing the reactor's design and recycling the waste heat from hot gas

  10. Aircraft Corrosion

    Science.gov (United States)

    1981-08-01

    attribud au choix de traitements et de rev~tements spproprids. Au contrairo, dens d’sutros structures des corrosions iirportsntea se sont msnifestdes...au traitement . micaniqus qui provoque une compression de surface - h1l’spplication i1’une double protection comportant oxydation snodique et...chlore mais dans une proportion semblable b cells d’une eau de vil)e ; - lea solides, d’aprbs lea analyses chimique et criatallographique, paraissaiont

  11. Assessment of radiation exposure on a dual-source computed tomography-scanner performing coronary computed tomography-angiography

    International Nuclear Information System (INIS)

    Kirchhoff, S.; Herzog, P.; Johnson, T.; Boehm, H.; Nikolaou, K.; Reiser, M.F.; Becker, C.H.

    2010-01-01

    Objective: The radiation exposure of a dual-source-64-channel multi-detector-computed-tomography-scanner (Somatom-Defintion, Siemens, Germany) was assessed in a phantom-study performing coronary-CT-angiography (CTCA) in comparison to patients' data randomly selected from routine scanning. Methods: 240 CT-acquisitions of a computed tomography dose index (CTDI)-phantom (PTW, Freiburg, Germany) were performed using a synthetically generated Electrocardiography (ECG)-signal with variable heart rates (30-180 beats per minute (bpm)). 120 measurements were acquired using continuous tube-output; 120 measurements were performed using ECG-synchronized tube-modulation. The pulsing window was set at minimum duration at 65% of the cardiac cycle between 30 and 75 bpm. From 90-180 bpm the pulsing window was set at 30-70% of the cardiac cycle. Automated pitch adaptation was always used. A comparison between phantom CTDI and two patient groups' CTDI corresponding to the two pulsing groups was performed. Results: Without ECG-tube-modulation CDTI-values were affected by heart-rate-changes resulting in 85.7 mGray (mGy) at 30 and 45 bpm, 65.5 mGy/60 bpm, 54.7 mGy/75 bpm, 46.5 mGy/90 bpm, 34.2 mGy/120 bpm, 27.0 mGy/150 bpm and 22.1 mGy/180 bpm equal to effective doses between 14.5 mSievert (mSv) at 30/45 bpm and 3.6 mSv at 180 bpm. Using ECG-tube-modulation these CTDI-values resulted: 32.6 mGy/30 bpm, 36.6 mGy/45 bpm, 31.4 mGy/60 bpm, 26.8 mGy/75 bpm, 23.7 mGy/90 bpm, 19.4 mGy/120 bpm, 17.2 mGy/150 bpm and 15.6 mGy/180 bpm equal to effective doses between 5.5 mSv at 30 bpm and 2.6 mSv at 180 bpm. Significant CTDI-differences were found between patients with lower/moderate and higher heart rates in comparison to the phantom CTDI-results. Conclusions: Dual source CTCA is particularly dose efficient at high heart rates when automated pitch adaptation, especially in combination with ECG-based tube-modulation is used. However in clinical routine scanning for patients with higher heart rates

  12. Diagnostic performance of calcification-suppressed coronary CT angiography using rapid kilovolt-switching dual-energy CT

    Energy Technology Data Exchange (ETDEWEB)

    Yunaga, Hiroto; Ohta, Yasutoshi; Kitao, Shinichiro; Ogawa, Toshihide [Tottori University, Division of Radiology, Department of Pathophysiological Therapeutic Science, Faculty of Medicine, Yonago City, Tottori (Japan); Kaetsu, Yasuhiro [Kakogawa Higashi Hospital, Department of Cardiology, Kakogawa (Japan); Watanabe, Tomomi; Furuse, Yoshiyuki; Yamamoto, Kazuhiro [Tottori University, Division of Cardiology, Department of Molecular Medicine and Therapeutics, Faculty of Medicine, Yonago (Japan)

    2017-07-15

    Multi-detector-row computed tomography angiography (MDCTA) plays an important role in the assessment of patients with suspected coronary artery disease. However, MDCTA tends to overestimate stenosis in calcified coronary artery lesions. The aim of our study was to evaluate the diagnostic performance of calcification-suppressed material density (MD) images produced by using a single-detector single-source dual-energy computed tomography (ssDECT). We enrolled 67 patients with suspected or known coronary artery disease who underwent ssDECT with rapid kilovolt-switching (80 and 140 kVp). Coronary artery stenosis was evaluated on the basis of MD images and virtual monochromatic (VM) images. The diagnostic performance of the two methods for detecting coronary artery disease was compared with that of invasive coronary angiography as a reference standard. We evaluated 239 calcified segments. In all the segments, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy for detecting significant stenosis were respectively 88%, 88%, 75%, 95% and 88% for the MD images, 91%, 71%, 56%, 95% and 77% for the VM images. PPV was significantly higher on the MD images than on the VM images (P < 0.0001). Calcification-suppressed MD images improved PPV and diagnostic performance for calcified coronary artery lesions. (orig.)

  13. Dual paths to individuals’ network based performance in intra-organizational networks

    DEFF Research Database (Denmark)

    Waldstrøm, Christian; Shah, Neha P.; Parker, Andrew

    Scholars have long been aware of the advantages to performance when colleagues share work information. We know less about the implications of multiplex ties such as when the sharing of work information is combined with that of nonwork information. We contrast social embeddedness theory with that ......Scholars have long been aware of the advantages to performance when colleagues share work information. We know less about the implications of multiplex ties such as when the sharing of work information is combined with that of nonwork information. We contrast social embeddedness theory...... a negative effect on performance. In addition, we find that the path to higher performance differs by the amount of time people have been in an organization. Those with low tenure outperformed colleagues with a moderate number of multiplex ties. Whereas, for their high tenure colleagues, multiplex ties had...... little effect....

  14. The Perceived Leadership Style and Employee Performance in Hotel Industry – a Dual Approach

    OpenAIRE

    Andreia ISPAS

    2012-01-01

    Hotel industry is an industry based on specific services and a high degree of employees (especially front line employees) client direct contact. A good relationship with the manager helps the subordinate to work beyond his daily effort, to be oriented to improve continuously his work performance and to give maximum of satisfaction to clients. This research paper is aiming to discuss the perceived leadership style and employees’ individual performance related to job satisfaction and organizati...

  15. Corrosion protective performance of amino trimethylene phosphonic acid-metal complex layers fabricated on the cold-rolled steel substrate via one-step assembly

    Science.gov (United States)

    Yan, Ru; He, Wei; Zhai, Tianhua; Ma, Houyi

    2018-06-01

    Seeing that amino trimethylene phosphonic acid (ATMP) possesses very strong complexation ability to metal ions and the phosphonic acid group has good affinity for the oxidized iron surface, herein a simple and rapid film-forming method (one-step assembly method) was developed to construct the ATMP-Zn complex conversion layers (ATMP-Zn layers for short) on the cold-rolled steel (CRS) substrate. Zinc ions were found to participate in the formation process of ATMP-based composite film, which made the Zn-containing ATMP film significantly different in appearance, thickness, microstructure and film-forming mechanisms from the Zn-free ATMP film. There was mainly iron (ш) phosphonate in the Zn-free ATMP film, whereas there were Zn2+-ATMP complex and a certain amount of ZnO in the ATMP-Zn composite film. In addition, electrochemical test results clearly indicate that corrosion resistance of ATMP-Zn composite film was greatly enhanced due to the presence of Zn component. Moreover, the corrosion resistance performance could be controlled by adjusting film-forming time, pH and ATMP concentration in the film-forming solutions. The present study provides a new method for the design and fabrication of high-quality environmentally-friendly conversion layers.

  16. High performance corrosion and wear resistant composite titanium nitride layers produced on the AZ91D magnesium alloy by a hybrid method

    Directory of Open Access Journals (Sweden)

    Michał Tacikowski

    2014-09-01

    Full Text Available Composite, diffusive titanium nitride layers formed on a titanium and aluminum sub-layer were produced on the AZ91D magnesium alloy. The layers were obtained using a hybrid method which combined the PVD processes with the final sealing by a hydrothermal treatment. The microstructure, resistance to corrosion, mechanical damage, and frictional wear of the layers were examined. The properties of the AZ91D alloy covered with these layers were compared with those of the untreated alloy and of some engineering materials such as 316L stainless steel, 100Cr6 bearing steel, and the AZ91D alloy subjected to commercial anodizing. It has been found that the composite diffusive nitride layer produced on the AZ91D alloy and then sealed by the hydrothermal treatment ensures the corrosion resistance comparable with that of 316L stainless steel. The layers are characterized by higher electrochemical durability which is due to the surface being overbuilt with the titanium oxides formed, as shown by the XPS examinations, from titanium nitride during the hydrothermal treatment. The composite titanium nitride layers exhibit high resistance to mechanical damage and wear, including frictional wear which is comparable with that of 100Cr6 bearing steel. The performance properties of the AZ91D magnesium alloy covered with the composite titanium nitride coating are substantially superior to those of the alloy subjected to commercial anodizing which is the dominant technique employed in industrial practice.

  17. Explaining the Evolution of Performance Measures - A Dual Case-Study Approach

    Directory of Open Access Journals (Sweden)

    Mohammed Salloum

    2013-07-01

    Full Text Available Few empirical studies have examined how performance measures change in practice and the driving forces behind this change. The existing body of literature has taken a prescriptive approach to how managers and organisations ought to manage change in performance measures without any concern for studying the phenomenon itself and thus a theoretical gap exists. With this gap in mind, the purpose of this paper is to outline how and why the performance measures have changed at two case companies over the time period 2008-2011. In order to fulfil the purpose of this paper two case studies at two different case companies have been conducted. The choice of data collection method is justified by the ambition to attain an in-depth and holistic understanding of the phenomenon. For each case, the data collection was based on four components: an interview study, analysis of archived data, documentation and direct observations. In total, 28 interviews were conducted, 14 at each case company. The empirical findings exhibit that the performance measures are exposed to continuous and considerable change from several perspectives. The measurement scopes at both case companies are steadily expanding, the individual performance measures are constantly replaced and their characteristics are continuously altered. An array of change triggers has been identified in the empirical findings. In contrast to what is advocated in literature, the findings illustrate that the most frequent reason for change is the will to improve the performance measures, the measurement process and the overall performance rather than changing internal and external environments. There are several challenges that need to be addressed in the future research agenda.

  18. Selection system orientations as an explanation for the differences between dual leaders of the same organization in their perception of organizational performance

    NARCIS (Netherlands)

    Bhansing, P.V.; Leenders, M.A.A.M.; Wijnberg, N.M.

    2016-01-01

    We investigate to what extent individual managers operating in a dual leadership structure have different perceptions of how well his/her organization is performing. Using selection system theory we develop hypotheses on the relationships between a leader’s selection system orientation and his/her

  19. Selection system orientations as an explanation for the differences between dual leaders of the same organization in their perception of organizational performance

    NARCIS (Netherlands)

    P.V. Bhansing (Pawan); M.A.A.M. Leenders (Mark); N.M. Wijnberg (Nachoem)

    2016-01-01

    textabstractWe investigate to what extent individual managers operating in a dual leadership structure have different perceptions of how well his/her organization is performing. Using selection system theory we develop hypotheses on the relationships between a leader’s selection system orientation

  20. Corrosion Testing Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Corrosion Testing Facility is part of the Army Corrosion Office (ACO). It is a fully functional atmospheric exposure site, called the Corrosion Instrumented Test...

  1. Vehicle accelerated corrosion test procedures for automotive in Malaysia

    Directory of Open Access Journals (Sweden)

    Anuar Liza

    2017-01-01

    Full Text Available An accelerated corrosion test, known as proving ground accelerated test, is commonly performed by automotive manufacturers to evaluate the corrosion performance of a vehicle. The test combines corrosion and durability inputs to detect potential failures that may occur during in-service conditions. Currently, the test is conducted at an external test center overseas. Such test is aimed to simulate the effects of one year accelerated corrosion in severe corrosive environment of the north-east and south east of America. However, the test results obtained do not correlate with the actual corrosion conditions observed in the Malaysian market, which is likely attributed to the different test environment of the tropical climate of vehicles in service. Therefore, a vehicle accelerated corrosion test procedure that suits the Malaysian market is proposed and benchmarked with other global car manufacturers that have their own dedicated corrosion test procedure. In the present work, a test track is used as the corrosion test ground and consists of various types of roads for structural durability exposures. Corrosion related facilities like salt trough, mud trough and gravel road are constructed as addition to the existing facilities. The establishment of accelerated corrosion test facilities has contributed to the development of initial accelerated corrosion test procedure for the national car manufacturer. The corrosion exposure is monitored by fitting test coupons at the underbody of test vehicle using mass loss technique so that the desired corrosion rate capable of simulating the real time corrosion effects for its target market.

  2. Over-focused? The relation between patients' inclination for conscious control and single- and dual-task motor performance after stroke.

    Science.gov (United States)

    Denneman, R P M; Kal, E C; Houdijk, H; Kamp, J van der

    2018-05-01

    Many stroke patients are inclined to consciously control their movements. This is thought to negatively affect patients' motor performance, as it disrupts movement automaticity. However, it has also been argued that conscious control may sometimes benefit motor performance, depending on the task or patientś motor or cognitive capacity. To assess whether stroke patients' inclination for conscious control is associated with motor performance, and explore whether the putative association differs as a function of task (single- vs dual) or patientś motor and cognitive capacity. Univariate and multivariate linear regression analysis were used to assess associations between patients' disposition to conscious control (i.e., Conscious Motor Processing subscale of Movement-Specific Reinvestment Scale; MSRS-CMP) and single-task (Timed-up-and-go test; TuG) and motor dual-task costs (TuG while tone counting; motor DTC%). We determined whether these associations were influenced by patients' walking speed (i.e., 10-m-walk test) and cognitive capacity (i.e., working memory, attention, executive function). Seventy-eight clinical stroke patients (task TuG performance. However, patients with a strong inclination for conscious control showed higher motor DTC%. These associations were irrespective of patients' motor and cognitive abilities. Patients' disposition for conscious control was not associated with single task motor performance, but was associated with higher motor dual task costs, regardless of patients' motor or cognitive abilities. Therapists should be aware that patients' conscious control inclination can influence their dual-task performance while moving. Longitudinal studies are required to test whether reducing patients' disposition for conscious control would improve dual-tasking post-stroke. Copyright © 2018 Elsevier B.V. All rights reserved.

  3. An experimental investigation of performance-emission trade off characteristics of a CI engine using hydrogen as dual fuel

    International Nuclear Information System (INIS)

    Deb, Madhujit; Paul, Abhishek; Debroy, Durbadal; Sastry, G.R.K.; Panua, Raj Sekhar; Bose, P.K.

    2015-01-01

    The investigation carried out in this research work concerns the effect of the addition of H 2 on performance and emission characteristics of a single cylinder, 4-stroke diesel engine. The tests were performed using diesel as a pilot fuel, with hydrogen addition at varying load condition using a Timed Manifold Injection (TMI) system has been developed using ECU (electronic control unit) with varying injection strategy to deliver hydrogen on to the intake manifold. The results showed a significant increase in BTE with appreciable decrease in BSEC of the engine when compared to conventional diesel-fueled operation. The emission of CO 2 and NOx was found to increase with enhancement of H 2 addition. The emission of UHC was found to be very high at low load conditions, but it enhanced as the load increased for all hydrogen injection while Soot emissions decreased. Thus, this paper provided a potential to investigate the effect of the addition of H 2 on the performance and emission characteristics of a diesel engine and how to get a best ratio of H 2 addition. The tradeoff study also consolidated the verity that Diesel–H 2 dual fuel operation was instrumental in resolving the high performance – low emission paradox. - Highlights: • Pure diesel and diesel–H 2 blends are tested. • Diesel–H 2 blends produced higher brake thermal efficiency than pure diesel in all part loads. • Diesel–H 2 blends reduced the energy consumption of the engine. • Diesel–H 2 blends simultaneously reduced Soot to some extent but increases N Ox and hydrocarbon emissions. • The performance-emission trade-off paradox has been studied using pure diesel and diesel–H 2 blends

  4. Isolating the Neural Mechanisms of Interference During Continuous Multisensory Dual-task Performance

    Science.gov (United States)

    2014-01-01

    of multitasking impairments have focused on the performance of two tasks presented in close temporal proximity on discrete trials; however, such...simultaneously and continuously monitor both auditory communications from pilots and visual radar displays. Drivers may choose to hold a cell phone

  5. Strategic adaptation to performance objectives in a dual-task setting.

    Science.gov (United States)

    Janssen, Christian P; Brumby, Duncan P

    2010-11-01

    How do people interleave attention when multitasking? One dominant account is that the completion of a subtask serves as a cue to switch tasks. But what happens if switching solely at subtask boundaries led to poor performance? We report a study in which participants manually dialed a UK-style telephone number while driving a simulated vehicle. If the driver were to exclusively return his or her attention to driving after completing a subtask (i.e., using the single break in the xxxxx-xxxxxx representational structure of the number), then we would expect to see a relatively poor driving performance. In contrast, our results show that drivers choose to return attention to steering control before the natural subtask boundary. A computational modeling analysis shows that drivers had to adopt this strategy to meet the required performance objective of maintaining an acceptable lateral position in the road while dialing. Taken together these results support the idea that people can strategically control the allocation of attention in multitask settings to meet specific performance criteria. Copyright © 2010 Cognitive Science Society, Inc.

  6. Context-Sensitive Adjustment of Cognitive Control in Dual-Task Performance

    Science.gov (United States)

    Fischer, Rico; Gottschalk, Caroline; Dreisbach, Gesine

    2014-01-01

    Performing 2 highly similar tasks at the same time requires an adaptive regulation of cognitive control to shield prioritized primary task processing from between-task (cross-talk) interference caused by secondary task processing. In the present study, the authors investigated how implicitly and explicitly delivered information promotes the…

  7. Corrosion and corrosion fatigue of airframe aluminum alloys

    Science.gov (United States)

    Chen, G. S.; Gao, M.; Harlow, D. G.; Wei, R. P.

    1994-01-01

    Localized corrosion and corrosion fatigue crack nucleation and growth are recognized as degradation mechanisms that effect the durability and integrity of commercial transport aircraft. Mechanically based understanding is needed to aid the development of effective methodologies for assessing durability and integrity of airframe components. As a part of the methodology development, experiments on pitting corrosion, and on corrosion fatigue crack nucleation and early growth from these pits were conducted. Pitting was found to be associated with constituent particles in the alloys and pit growth often involved coalescence of individual particle-nucleated pits, both laterally and in depth. Fatigue cracks typically nucleated from one of the larger pits that formed by a cluster of particles. The size of pit at which fatigue crack nucleates is a function of stress level and fatigue loading frequency. The experimental results are summarized, and their implications on service performance and life prediction are discussed.

  8. Graphene oxide as a dual-function conductive binder for PEEK-derived microporous carbons in high performance supercapacitors

    Science.gov (United States)

    Kim, Christine H. J.; Zhang, Hongbo; Liu, Jie

    2015-06-01

    Microporous carbons (MPCs) are promising electrode materials for supercapacitors because of their high surface area and accessible pores. However, their low electrical conductivity and mechanical instability result in limited power density and poor cycle life. This work proposes a unique two-layered film made of polyetheretherketone-derived MPCs and reduced graphene oxide (rGO) as an electrode for supercapacitors. Electrochemical characterizations of films show that such a layered structure is more effective in increasing the accessibility of ions to the hydrophilic MPCs and establishing conductive paths through the rGO network than a simple mixed composite film. The two-layered structure increases the capacitance by ˜124% (237 F g-1) with excellent cycling stability (˜93% after 6000 cycles). More importantly, we demonstrate that such performance improvements result from an optimal balance between electrical conductivity and ion accessibility, which maximizes the synergistic effects of MPC and rGO. The MPCs, which are exposed to the surface, provide a highly accessible surface area for ion adsorption. The rGO serves a dual function as a conductive filler to increase the electrical conductivity and as a binder to interconnect individual MPC particles into a robust and flexible film. These findings provide a rational basis for the design of MPC-based electrodes in high performance supercapacitors.

  9. Graphene oxide as a dual-function conductive binder for PEEK-derived microporous carbons in high performance supercapacitors

    International Nuclear Information System (INIS)

    Kim, Christine H J; Zhang, Hongbo; Liu, Jie

    2015-01-01

    Microporous carbons (MPCs) are promising electrode materials for supercapacitors because of their high surface area and accessible pores. However, their low electrical conductivity and mechanical instability result in limited power density and poor cycle life. This work proposes a unique two-layered film made of polyetheretherketone-derived MPCs and reduced graphene oxide (rGO) as an electrode for supercapacitors. Electrochemical characterizations of films show that such a layered structure is more effective in increasing the accessibility of ions to the hydrophilic MPCs and establishing conductive paths through the rGO network than a simple mixed composite film. The two-layered structure increases the capacitance by ∼124% (237 F g −1 ) with excellent cycling stability (∼93% after 6000 cycles). More importantly, we demonstrate that such performance improvements result from an optimal balance between electrical conductivity and ion accessibility, which maximizes the synergistic effects of MPC and rGO. The MPCs, which are exposed to the surface, provide a highly accessible surface area for ion adsorption. The rGO serves a dual function as a conductive filler to increase the electrical conductivity and as a binder to interconnect individual MPC particles into a robust and flexible film. These findings provide a rational basis for the design of MPC-based electrodes in high performance supercapacitors. (paper)

  10. Performance and emission comparison of a supercharged dual-fuel engine fueled by producer gases with varying hydrogen content

    Energy Technology Data Exchange (ETDEWEB)

    Mohon Roy, Murari [Rajshahi University of Engineering and Technology (JSPS Research Fellow, Okayama University), Tsushima-Naka 3, Okayama 700-8530 (Japan); Department of Mechanical Engineering, Okayama University, Tsushima-Naka 3, Okayama 700-8530 (Japan); Tomita, Eiji; Kawahara, Nobuyuki; Harada, Yuji [Department of Mechanical Engineering, Okayama University, Tsushima-Naka 3, Okayama 700-8530 (Japan); Sakane, Atsushi (Mitsui Engineering and Shipbuilding Co. Ltd., 6-4 Tsukiji 5-chome, Chuo-ku, Tokyo)

    2009-09-15

    This study investigated the effect of hydrogen content in producer gas on the performance and exhaust emissions of a supercharged producer gas-diesel dual-fuel engine. Two types of producer gases were used in this study, one with low hydrogen content (H{sub 2} = 13.7%) and the other with high hydrogen content (H{sub 2} = 20%). The engine was tested for use as a co-generation engine, so power output while maintaining a reasonable thermal efficiency was important. Experiments were carried out at a constant injection pressure and injection quantity for different fuel-air equivalence ratios and at various injection timings. The experimental strategy was to optimize the injection timing to maximize engine power at different fuel-air equivalence ratios without knocking and within the limit of the maximum cylinder pressure. Two-stage combustion was obtained; this is an indicator of maximum power output conditions and a precursor of knocking combustion. Better combustion, engine performance, and exhaust emissions (except NO{sub x}) were obtained with the high H{sub 2}-content producer gas than with the low H{sub 2}-content producer gas, especially under leaner conditions. Moreover, a broader window of fuel-air equivalence ratio was found with highest thermal efficiencies for the high H{sub 2}-content producer gas. (author)

  11. Performance and emissions of a supercharged dual-fuel engine fueled by hydrogen-rich coke oven gas

    Energy Technology Data Exchange (ETDEWEB)

    Roy, M.M.; Tomita, E.; Kawahara, N.; Harada, Y.; Sakane, A. [Okayama University, Okayama (Japan). Dept. of Mechanical Engineering

    2009-12-15

    This study investigated the engine performance and emissions of a supercharged dual-fuel engine fueled by hydrogen-rich coke oven gas and ignited by a pilot amount of diesel fuel. The engine was tested for use as a cogeneration engine, so power output while maintaining a reasonable thermal efficiency was important. Experiments were carried out at a constant pilot injection pressure and pilot quantity for different fuel-air equivalence ratios and at various injection timings without and with exhaust gas recirculation (EGR). The experimental strategy was to optimize the injection timing to maximize engine power at different fuel-air equivalence ratios without knocking and within the limit of the maximum cylinder pressure. The engine was tested first without EGR condition up to the maximum possible fuel-air equivalence ratio of 0.65. A maximum indicated mean effective pressure (IMEP) of 1425 kPa and a thermal efficiency of 39% were obtained. However, the nitrogen oxides (NOx) emissions were high. A simulated EGR up to 50% was then performed to obtain lower NOx emissions. The maximum reduction of NOx was 60% or more maintaining the similar levels of IMEP and thermal efficiency. Two-stage combustion was obtained; this is an indicator of maximum power output conditions and a precursor of knocking combustion.

  12. An experimental investigation on engine performance and emissions of a supercharged H{sub 2}-diesel dual-fuel engine

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Murari Mohon [Rajshahi University of Engineering and Technology (JSPS Research Fellow, Okayama University), Tsushima-Naka 3, Okayama 700-8530 (Japan); Department of Mechanical Engineering, Okayama University, Tsushima-Naka 3, Okayama 700-8530 (Japan); Tomita, Eiji; Kawahara, Nobuyuki; Harada, Yuji [Department of Mechanical Engineering, Okayama University, Tsushima-Naka 3, Okayama 700-8530 (Japan); Sakane, Atsushi [Mitsui Engineering and Shipbuilding Co. Ltd., 6-4 Tsukiji 5-chome, Chuo-ku, Tokyo (Japan)

    2010-01-15

    This study investigated the engine performance and emissions of a supercharged engine fueled by hydrogen and ignited by a pilot amount of diesel fuel in dual-fuel mode. The engine was tested for use as a cogeneration engine, so power output while maintaining a reasonable thermal efficiency was important. Experiments were carried out at a constant pilot injection pressure and pilot quantity for different fuel-air equivalence ratios and at various injection timings without and with charge dilution. The experimental strategy was to optimize the injection timing to maximize engine power at different fuel-air equivalence ratios without knocking and within the limit of the maximum cylinder pressure. The engine was tested first with hydrogen-operation condition up to the maximum possible fuel-air equivalence ratio of 0.3. A maximum IMEP of 908 kPa and a thermal efficiency of about 42% were obtained. Equivalence ratio could not be further increased due to knocking of the engine. The emission of CO was only about 5 ppm, and that of HC was about 15 ppm. However, the NOx emissions were high, 100-200 ppm or more. The charge dilution by N{sub 2} was then performed to obtain lower NOx emissions. The 100% reduction of NOx was achieved. Due to the dilution by N{sub 2} gas, higher amount of energy could be supplied from hydrogen without knocking, and about 13% higher IMEP was produced than without charge dilution. (author)

  13. Who is talking in backward crosstalk? Disentangling response- from goal-conflict in dual-task performance.

    Science.gov (United States)

    Janczyk, Markus; Pfister, Roland; Hommel, Bernhard; Kunde, Wilfried

    2014-07-01

    Responses in the second of two subsequently performed tasks can speed up compatible responses in the temporally preceding first task. Such backward crosstalk effects (BCEs) represent a challenge to the assumption of serial processing in stage models of human information processing, because they indicate that certain features of the second response have to be represented before the first response is emitted. Which of these features are actually relevant for BCEs is an open question, even though identifying these features is important for understanding the nature of parallel and serial response selection processes in dual-task performance. Motivated by effect-based models of action control, we show in three experiments that the BCE to a considerable degree reflects features of intended action effects, although features of the response proper (or response-associated kinesthetic feedback) also seem to play a role. These findings suggest that the codes of action effects (or action goals) can become activated simultaneously rather than serially, thereby creating BCEs. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Corrosion potential analysis system

    Science.gov (United States)

    Kiefer, Karl F.

    1998-03-01

    Many cities in the northeastern U.S. transport electrical power from place to place via underground cables, which utilize voltages from 68 kv to 348 kv. These cables are placed in seamless steel pipe to protect the conductors. These buried pipe-type-cables (PTCs) are carefully designed and constantly pressurized with transformer oil to prevent any possible contamination. A protective coating placed on the outside diameter of the pipe during manufacture protects the steel pipe from the soil environment. Notwithstanding the protection mechanisms available, the pipes remain vulnerable to electrochemical corrosion processes. If undetected, corrosion can cause the pipes to leak transformer oil into the environment. These leaks can assume serious proportions due to the constant pressure on the inside of the pipe. A need exists for a detection system that can dynamically monitor the corrosive potential on the length of the pipe and dynamically adjust cathodic protection to counter local and global changes in the cathodic environment surrounding the pipes. The northeastern United States contains approximately 1000 miles of this pipe. This milage is critical to the transportation and distribution of power. So critical, that each of the pipe runs has a redundant double running parallel to it. Invocon, Inc. proposed and tested a technically unique and cost effective solution to detect critical corrosion potential and to communicate that information to a central data collection and analysis location. Invocon's solution utilizes the steel of the casing pipe as a communication medium. Each data gathering station on the pipe can act as a relay for information gathered elsewhere on the pipe. These stations must have 'smart' network configuration algorithms that constantly test various communication paths and determine the best and most power efficient route through which information should flow. Each network station also performs data acquisition and analysis tasks that ultimately

  15. Single- versus dual-process models of lexical decision performance: insights from response time distributional analysis.

    Science.gov (United States)

    Yap, Melvin J; Balota, David A; Cortese, Michael J; Watson, Jason M

    2006-12-01

    This article evaluates 2 competing models that address the decision-making processes mediating word recognition and lexical decision performance: a hybrid 2-stage model of lexical decision performance and a random-walk model. In 2 experiments, nonword type and word frequency were manipulated across 2 contrasts (pseudohomophone-legal nonword and legal-illegal nonword). When nonwords became more wordlike (i.e., BRNTA vs. BRANT vs. BRANE), response latencies to nonwords were slowed and the word frequency effect increased. More important, distributional analyses revealed that the Nonword Type = Word Frequency interaction was modulated by different components of the response time distribution, depending on the specific nonword contrast. A single-process random-walk model was able to account for this particular set of findings more successfully than the hybrid 2-stage model. (c) 2006 APA, all rights reserved.

  16. The effects of glucose dose and dual-task performance on memory for emotional material

    OpenAIRE

    Brandt, Karen; Sünram-Lea, Sandra; Jenkinson, Paul; Jones, Emma

    2010-01-01

    Whilst previous research has shown that glucose administration can boost memory performance, research investigating the effects of glucose on memory for emotional material has produced mixed findings. Whereas some research has shown that glucose impairs memory for emotional material, other research has shown that glucose has no effect on emotional items. The aim of the present research was therefore to provide further investigation of the role of glucose on the recognition of words with emoti...

  17. Capturing the Dual Pillars of Grit: The Synergistic Benefits of Perseverance and Passion for Performance

    OpenAIRE

    Wihler, Andreas; Jachimowicz, Jon; Galinsky, Adam

    2018-01-01

    Previous research has found mixed evidence regarding the relationship between grit-defined as perseverance and passion for long-term goals-and performance. We propose that this inconsistency has occurred because prior research has emphasized perseverance, both theoretically and empirically, while insufficiently incorporating passion. We suggest that a combination of the original grit measure-which emphasizes perseverance-with a measure that assesses whether individuals attain desired levels o...

  18. The Assessment of Military Multitasking Performance: Validation of a Dual-Task and Multitask Protocol

    Science.gov (United States)

    2014-08-01

    multitasks using healthy control and SM with diagnosed mTBI. Approach: Inter-rater reliability and assessment of training requirements for expert...developers piloted the revised multitask assessment in a healthy population to assess IRR. Given the an- ticipated variability in task performance between...1 AD_________________ Award Number: Contract W81XWH-12-2-0070 TITLE: Annual Report: The Assessment of Military Multitasking

  19. Dual-Functional Graphene Carbon as Polysulfide Trapper for High-Performance Lithium Sulfur Batteries.

    Science.gov (United States)

    Zhang, Linlin; Wan, Fang; Wang, Xinyu; Cao, Hongmei; Dai, Xi; Niu, Zhiqiang; Wang, Yijing; Chen, Jun

    2018-02-14

    The lithium sulfur (Li-S) battery has attracted much attention due to its high theoretical capacity and energy density. However, its cycling stability and rate performance urgently need to improve because of its shuttle effect. Herein, oxygen-doped carbon on the surface of reduced graphene oxide (labeled as ODC/rGO) was fabricated to modify the separators of Li-S batteries to limit the dissolution of the lithium polysulfides. The mesoporous structure in ODC/rGO can not only serve as the physical trapper, but also provide abundant channels for fast ion transfer, which is beneficial for effective confinement of the dissoluble intermediates and superior rate performance. Moreover, the oxygen-containing groups in ODC/rGO are able to act as chemical adsorption sites to immobilize the lithium polysulfides, suppressing their dissolution in electrolyte to enhance the utilization of sulfur cathode in Li-S batteries. As a result, because of the synergetic effects of physical adsorption and chemical interaction to immobilize the soluble polysulfides, the Li-S batteries with the ODC/rGO-coated separator exhibit excellent rate performance and good long-term cycling stability with 0.057% capacity decay per cycle at 1.0 C after 600 cycles.

  20. Corrosion technology. V. 1

    International Nuclear Information System (INIS)

    Khan, I.H.

    1989-01-01

    This book has been produced for dissemination of information on corrosion technology, corrosion hazards and its control. Chapter one of this book presents an overall view of the subject and chapter 2-5 deals with electrochemical basics, types of corrosion, pourbaix diagrams and form of corrosion. The author explains polarization/kinetics of corrosion, passivity, aqueous corrosion and corrosion testing and monitoring in 6-11 chapters. The author hopes it