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Sample records for controlling aluminum tolerance

  1. Quantitative trait loci controlling aluminum tolerance in soybean: candidate gene and SNP marker discovery

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aluminum (Al) toxicity is an important abiotic stress that affects soybean production in acidic soils. Development of Al-tolerant cultivars is an efficient and environmentally friendly solution to the problem. Effective selection of Al-tolerant genotypes in applied breeding requires an understanding...

  2. Aluminum exclusion and aluminum tolerance in woody plants

    PubMed Central

    Brunner, Ivano; Sperisen, Christoph

    2013-01-01

    The aluminum (Al) cation Al3+ is highly rhizotoxic and is a major stress factor to plants on acid soils, which cover large areas of tropical and boreal regions. Many woody plant species are native to acid soils and are well adapted to high Al3+ conditions. In tropical regions, both woody Al accumulator and non-Al accumulator plants occur, whereas in boreal regions woody plants are non-Al accumulators. The mechanisms of these adaptations can be divided into those that facilitate the exclusion of Al3+ from root cells (exclusion mechanisms) and those that enable plants to tolerate Al3+ once it has entered the root and shoot symplast (internal tolerance mechanisms). The biochemical and molecular basis of these mechanisms have been intensively studied in several crop plants and the model plant Arabidopsis. In this review, we examine the current understanding of Al3+ exclusion and tolerance mechanisms from woody plants. In addition, we discuss the ecology of woody non-Al accumulator and Al accumulator plants, and present examples of Al3+ adaptations in woody plant populations. This paper complements previous reviews focusing on crop plants and provides insights into evolutionary processes operating in plant communities that are widespread on acid soils. PMID:23781222

  3. An ALMT1 gene cluster controlling aluminium (aluminum) tolerance at the Alt4 locus of rye (Secale cereale L.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aluminium toxicity is a major problem in agriculture worldwide. Among the cultivated triticeae, rye (Secale cereale L.) is one of the most Al-tolerant and represents an important potential source of Al-tolerance for improvement of wheat. The Alt4 Al-tolerance locus of rye contains a cluster of genes...

  4. Chromosome-anchored QTL conferring aluminum tolerance in hexaploid oat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Abstract Aluminum (Al) toxicity is a major constraint on crop production in acid soils around the world. Hexaploid oat (Avena sativa L.) possesses signi'cant Al tolerance making it a good candidate for production in these environments. Genetic improvement for Al tolerance in oat has traditionally be...

  5. Development of a novel aluminum tolerance phenotyping platform used for comparisons of cereal aluminum tolerance and investigations into rice aluminum tolerance mechanisms.

    PubMed

    Famoso, Adam N; Clark, Randy T; Shaff, Jon E; Craft, Eric; McCouch, Susan R; Kochian, Leon V

    2010-08-01

    The genetic and physiological mechanisms of aluminum (Al) tolerance have been well studied in certain cereal crops, and Al tolerance genes have been identified in sorghum (Sorghum bicolor) and wheat (Triticum aestivum). Rice (Oryza sativa) has been reported to be highly Al tolerant; however, a direct comparison of rice and other cereals has not been reported, and the mechanisms of rice Al tolerance are poorly understood. To facilitate Al tolerance phenotyping in rice, a high-throughput imaging system and root quantification computer program was developed, permitting quantification of the entire root system, rather than just the longest root. Additionally, a novel hydroponic solution was developed and optimized for Al tolerance screening in rice and compared with the Yoshida's rice solution commonly used for rice Al tolerance studies. To gain a better understanding of Al tolerance in cereals, comparisons of Al tolerance across cereal species were conducted at four Al concentrations using seven to nine genetically diverse genotypes of wheat, maize (Zea mays), sorghum, and rice. Rice was significantly more tolerant than maize, wheat, and sorghum at all Al concentrations, with the mean Al tolerance level for rice found to be 2- to 6-fold greater than that in maize, wheat, and sorghum. Physiological experiments were conducted on a genetically diverse panel of more than 20 rice genotypes spanning the range of rice Al tolerance and compared with two maize genotypes to determine if rice utilizes the well-described Al tolerance mechanism of root tip Al exclusion mediated by organic acid exudation. These results clearly demonstrate that the extremely high levels of rice Al tolerance are mediated by a novel mechanism, which is independent of root tip Al exclusion.

  6. Joint linkage association analysis of aluminum tolerance in maize

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aluminum (Al) toxicity is a profound limitation to crop production worldwide, reducing yields on up to 50% of potentially arable lands. Breeding for Al tolerance and agronomic practices aimed at ameliorating soil acidity have historically been productive avenues for improved crop production. However...

  7. 40 CFR 180.415 - Aluminum tris (O-ethylphosphonate); tolerances for residues.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Aluminum tris (O-ethylphosphonate... Tolerances § 180.415 Aluminum tris (O-ethylphosphonate); tolerances for residues. (a) General. Tolerances are established for residues of the fungicide aluminum tris (O-ethylphosphonate), including its metabolites...

  8. 40 CFR 180.415 - Aluminum tris (O-ethylphosphonate); tolerances for residues.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 25 2013-07-01 2013-07-01 false Aluminum tris (O-ethylphosphonate... Tolerances § 180.415 Aluminum tris (O-ethylphosphonate); tolerances for residues. (a) General. Tolerances are established for residues of the fungicide aluminum tris (O-ethylphosphonate), including its metabolites...

  9. 40 CFR 180.415 - Aluminum tris (O-ethylphosphonate); tolerances for residues.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Aluminum tris (O-ethylphosphonate... Tolerances § 180.415 Aluminum tris (O-ethylphosphonate); tolerances for residues. (a) General. Tolerances are established for residues of the fungicide aluminum tris (O-ethylphosphonate), including its metabolites...

  10. 40 CFR 180.415 - Aluminum tris (O-ethylphosphonate); tolerances for residues.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Aluminum tris (O-ethylphosphonate... Tolerances § 180.415 Aluminum tris (O-ethylphosphonate); tolerances for residues. (a) General. Tolerances are established for residues of the fungicide aluminum tris (O-ethylphosphonate), including its metabolites...

  11. Durability and Damage Tolerance of Aluminum Castings

    DTIC Science & Technology

    1988-09-01

    casting alloys A357 and A201. On completion of the program, revisions to material, process, and DADT specifications will be recommended, if necessary...and the effects of process variables on the properties of A357 -T6 and A201-T7 castings were described. This second interim report covers additional...damage tolerance properties of A357 -T6 and A201-T7 produced using the specifications selected earlier [1] in Task 2 were determined. These alloys were

  12. Fault tolerant control laws

    NASA Technical Reports Server (NTRS)

    Ly, U. L.; Ho, J. K.

    1986-01-01

    A systematic procedure for the synthesis of fault tolerant control laws to actuator failure has been presented. Two design methods were used to synthesize fault tolerant controllers: the conventional LQ design method and a direct feedback controller design method SANDY. The latter method is used primarily to streamline the full-state Q feedback design into a practical implementable output feedback controller structure. To achieve robustness to control actuator failure, the redundant surfaces are properly balanced according to their control effectiveness. A simple gain schedule based on the landing gear up/down logic involving only three gains was developed to handle three design flight conditions: Mach .25 and Mach .60 at 5000 ft and Mach .90 at 20,000 ft. The fault tolerant control law developed in this study provides good stability augmentation and performance for the relaxed static stability aircraft. The augmented aircraft responses are found to be invariant to the presence of a failure. Furthermore, single-loop stability margins of +6 dB in gain and +30 deg in phase were achieved along with -40 dB/decade rolloff at high frequency.

  13. Association and Linkage Analysis of Aluminum Tolerance Genes in Maize

    PubMed Central

    Krill, Allison M.; Kirst, Matias; Kochian, Leon V.; Buckler, Edward S.; Hoekenga, Owen A.

    2010-01-01

    Background Aluminum (Al) toxicity is a major worldwide constraint to crop productivity on acidic soils. Al becomes soluble at low pH, inhibiting root growth and severely reducing yields. Maize is an important staple food and commodity crop in acidic soil regions, especially in South America and Africa where these soils are very common. Al exclusion and intracellular tolerance have been suggested as two important mechanisms for Al tolerance in maize, but little is known about the underlying genetics. Methodology An association panel of 282 diverse maize inbred lines and three F2 linkage populations with approximately 200 individuals each were used to study genetic variation in this complex trait. Al tolerance was measured as net root growth in nutrient solution under Al stress, which exhibited a wide range of variation between lines. Comparative and physiological genomics-based approaches were used to select 21 candidate genes for evaluation by association analysis. Conclusions Six candidate genes had significant results from association analysis, but only four were confirmed by linkage analysis as putatively contributing to Al tolerance: Zea mays AltSB like (ZmASL), Zea mays aluminum-activated malate transporter2 (ALMT2), S-adenosyl-L-homocysteinase (SAHH), and Malic Enzyme (ME). These four candidate genes are high priority subjects for follow-up biochemical and physiological studies on the mechanisms of Al tolerance in maize. Immediately, elite haplotype-specific molecular markers can be developed for these four genes and used for efficient marker-assisted selection of superior alleles in Al tolerance maize breeding programs. PMID:20376361

  14. Aluminum Toxicity-Induced Alterations of Leaf Proteome in Two Citrus Species Differing in Aluminum Tolerance.

    PubMed

    Li, Huan; Yang, Lin-Tong; Qi, Yi-Ping; Guo, Peng; Lu, Yi-Bin; Chen, Li-Song

    2016-07-21

    Seedlings of aluminum-tolerant 'Xuegan' (Citrus sinensis) and Al-intolerant 'sour pummelo' (Citrus grandis) were fertigated for 18 weeks with nutrient solution containing 0 and 1.2 mM AlCl₃·6H₂O. Al toxicity-induced inhibition of photosynthesis and the decrease of total soluble protein only occurred in C. grandis leaves, demonstrating that C. sinensis had higher Al tolerance than C. grandis. Using isobaric tags for relative and absolute quantification (iTRAQ), we obtained more Al toxicity-responsive proteins from C. sinensis than from C. grandis leaves, which might be responsible for the higher Al tolerance of C. sinensis. The following aspects might contribute to the Al tolerance of C. sinensis: (a) better maintenance of photosynthesis and energy balance via inducing photosynthesis and energy-related proteins; (b) less increased requirement for the detoxification of reactive oxygen species and other toxic compounds, such as aldehydes, and great improvement of the total ability of detoxification; and (c) upregulation of low-phosphorus-responsive proteins. Al toxicity-responsive proteins related to RNA regulation, protein metabolism, cellular transport and signal transduction might also play key roles in the higher Al tolerance of C. sinensis. We present the global picture of Al toxicity-induced alterations of protein profiles in citrus leaves, and identify some new Al toxicity-responsive proteins related to various biological processes. Our results provide some novel clues about plant Al tolerance.

  15. Aluminum Toxicity-Induced Alterations of Leaf Proteome in Two Citrus Species Differing in Aluminum Tolerance

    PubMed Central

    Li, Huan; Yang, Lin-Tong; Qi, Yi-Ping; Guo, Peng; Lu, Yi-Bin; Chen, Li-Song

    2016-01-01

    Seedlings of aluminum-tolerant ‘Xuegan’ (Citrus sinensis) and Al-intolerant ‘sour pummelo’ (Citrus grandis) were fertigated for 18 weeks with nutrient solution containing 0 and 1.2 mM AlCl3·6H2O. Al toxicity-induced inhibition of photosynthesis and the decrease of total soluble protein only occurred in C. grandis leaves, demonstrating that C. sinensis had higher Al tolerance than C. grandis. Using isobaric tags for relative and absolute quantification (iTRAQ), we obtained more Al toxicity-responsive proteins from C. sinensis than from C. grandis leaves, which might be responsible for the higher Al tolerance of C. sinensis. The following aspects might contribute to the Al tolerance of C. sinensis: (a) better maintenance of photosynthesis and energy balance via inducing photosynthesis and energy-related proteins; (b) less increased requirement for the detoxification of reactive oxygen species and other toxic compounds, such as aldehydes, and great improvement of the total ability of detoxification; and (c) upregulation of low-phosphorus-responsive proteins. Al toxicity-responsive proteins related to RNA regulation, protein metabolism, cellular transport and signal transduction might also play key roles in the higher Al tolerance of C. sinensis. We present the global picture of Al toxicity-induced alterations of protein profiles in citrus leaves, and identify some new Al toxicity-responsive proteins related to various biological processes. Our results provide some novel clues about plant Al tolerance. PMID:27455238

  16. Bacterial citrate synthase expression and soil aluminum tolerance in transgenic alfalfa.

    PubMed

    Barone, Pierluigi; Rosellini, Daniele; Lafayette, Peter; Bouton, Joseph; Veronesi, Fabio; Parrott, Wayne

    2008-05-01

    Alfalfa is very sensitive to soil acidity and its yield and stand duration are compromised due to inhibited root growth and reduced nitrogen fixation caused by Al toxicity. Soil improvement by liming is expensive and only partially effective, and conventional plant breeding for Al tolerance has had limited success. Because tobacco and papaya plants overexpressing Pseudomonas aeruginosa citrate synthase (CS) have been reported to exhibit enhanced tolerance to Al, alfalfa was engineered by introducing the CS gene controlled by the Arabidopsis Act2 constitutive promoter or the tobacco RB7 root-specific promoter. Fifteen transgenic plants were assayed for exclusion of Al from the root tip, for internal citrate content, for growth in in vitro assays, or for shoot and root growth in either hydroponics or in soil assays. Overall, only the soil assays yielded consistent results. Based on the soil assays, two transgenic events were identified that were more aluminum-tolerant than the non-transgenic control, confirming that citrate synthase overexpression can be a useful tool to help achieve aluminum tolerance.

  17. Radiation Tolerance of Aluminum Microwave Kinetic Inductance Detector

    NASA Astrophysics Data System (ADS)

    Karatsu, K.; Dominjon, A.; Fujino, T.; Funaki, T.; Hazumi, M.; Irie, F.; Ishino, H.; Kida, Y.; Matsumura, T.; Mizukami, K.; Naruse, M.; Nitta, T.; Noguchi, T.; Oka, N.; Sekiguchi, S.; Sekimoto, Y.; Sekine, M.; Shu, S.; Yamada, Y.; Yamashita, T.

    2016-08-01

    Microwave kinetic inductance detector (MKID) is one of the candidates of focal plane detector for future satellite missions such as LiteBIRD. For the space use of MKIDs, the radiation tolerance is one of the challenges to be characterized prior to the launch. Aluminum (Al) MKIDs with 50 nm thickness on silicon substrate and on sapphire substrate were irradiated with a proton beam of 160 MeV at the heavy ion medical accelerator in Chiba. The total water-equivalent absorbed dose was ˜ 10 krad which should simulate the worst radiation absorption of 5 years observation at the Lagrange point L2. We measured characteristics of these MKIDs before and after the irradiation. We found no significant changes on resonator quality factor, responsivity, and recombination time of quasi-particles. The change on electrical noise equivalent power was also evaluated, and no significant increase was found at the noise level of O(10^{-18}) W/√{ Hz }.

  18. How do crop plants tolerate acid soils? Mechanisms of aluminum tolerance and phosphorous efficiency.

    PubMed

    Kochian, Leon V; Hoekenga, Owen A; Pineros, Miguel A

    2004-01-01

    Acid soils significantly limit crop production worldwide because approximately 50% of the world's potentially arable soils are acidic. Because acid soils are such an important constraint to agriculture, understanding the mechanisms and genes conferring tolerance to acid soil stress has been a focus of intense research interest over the past decade. The primary limitations on acid soils are toxic levels of aluminum (Al) and manganese (Mn), as well as suboptimal levels of phosphorous (P). This review examines our current understanding of the physiological, genetic, and molecular basis for crop Al tolerance, as well as reviews the emerging area of P efficiency, which involves the genetically based ability of some crop genotypes to tolerate P deficiency stress on acid soils. These are interesting times for this field because researchers are on the verge of identifying some of the genes that confer Al tolerance in crop plants; these discoveries will open up new avenues of molecular/physiological inquiry that should greatly advance our understanding of these tolerance mechanisms. Additionally, these breakthroughs will provide new molecular resources for improving crop Al tolerance via both molecular-assisted breeding and biotechnology.

  19. Radiation tolerance of piezoelectric bulk single-crystal aluminum nitride

    SciTech Connect

    David A. Parks; Bernhard R. Tittmann

    2014-07-01

    For practical use in harsh radiation environments, we pose selection criteria for piezoelectric materials for nondestructive evaluation (NDE) and material characterization. Using these criteria, piezoelectric aluminum nitride is shown to be an excellent candidate. The results of tests on an aluminumnitride-based transducer operating in a nuclear reactor are also presented. We demonstrate the tolerance of single-crystal piezoelectric aluminum nitride after fast and thermal neutron fluences of 1.85 × 1018 neutron/cm2 and 5.8 × 1018 neutron/cm2, respectively, and a gamma dose of 26.8 MGy. The radiation hardness of AlN is most evident from the unaltered piezoelectric coefficient d33, which measured 5.5 pC/N after a fast and thermal neutron exposure in a nuclear reactor core for over 120 MWh, in agreement with the published literature value. The results offer potential for improving reactor safety and furthering the understanding of radiation effects on materials by enabling structural health monitoring and NDE in spite of the high levels of radiation and high temperatures, which are known to destroy typical commercial ultrasonic transducers.

  20. Intelligent failure-tolerant control

    NASA Technical Reports Server (NTRS)

    Stengel, Robert F.

    1991-01-01

    An overview of failure-tolerant control is presented, beginning with robust control, progressing through parallel and analytical redundancy, and ending with rule-based systems and artificial neural networks. By design or implementation, failure-tolerant control systems are 'intelligent' systems. All failure-tolerant systems require some degrees of robustness to protect against catastrophic failure; failure tolerance often can be improved by adaptivity in decision-making and control, as well as by redundancy in measurement and actuation. Reliability, maintainability, and survivability can be enhanced by failure tolerance, although each objective poses different goals for control system design. Artificial intelligence concepts are helpful for integrating and codifying failure-tolerant control systems, not as alternatives but as adjuncts to conventional design methods.

  1. Comparative mapping of a major aluminum tolerance gene in sorghum and other species in the poaceae.

    PubMed Central

    Magalhaes, Jurandir V; Garvin, David F; Wang, Yihong; Sorrells, Mark E; Klein, Patricia E; Schaffert, Robert E; Li, Li; Kochian, Leon V

    2004-01-01

    In several crop species within the Triticeae tribe of the grass family Poaceae, single major aluminum (Al) tolerance genes have been identified that effectively mitigate Al toxicity, a major abiotic constraint to crop production on acidic soils. However, the trait is quantitatively inherited in species within other tribes, and the possible ancestral relationships between major Al tolerance genes and QTL in the grasses remain unresolved. To help establish these relationships, we conducted a molecular genetic analysis of Al tolerance in sorghum and integrated our findings with those from previous studies performed in crop species belonging to different grass tribes. A single locus, AltSB, was found to control Al tolerance in two highly Al tolerant sorghum cultivars. Significant macrosynteny between sorghum and the Triticeae was observed for molecular markers closely linked to putatively orthologous Al tolerance loci present in the group 4 chromosomes of wheat, barley, and rye. However, AltSB was not located within the homeologous region of sorghum but rather mapped near the end of sorghum chromosome 3. Thus, AltSB not only is the first major Al tolerance gene mapped in a grass species that does not belong to the Triticeae, but also appears to be different from the major Al tolerance locus in the Triticeae. Intertribe map comparisons suggest that a major Al tolerance QTL on rice chromosome 1 is likely to be orthologous to AltSB, whereas another rice QTL on chromosome 3 is likely to correspond to the Triticeae group 4 Al tolerance locus. Therefore, this study demonstrates a clear evolutionary link between genes and QTL encoding the same trait in distantly related species within a single plant family. PMID:15342528

  2. Brassica oleracea MATE encodes a citrate transporter and enhances aluminum tolerance in Arabidopsis thaliana.

    PubMed

    Wu, Xinxin; Li, Ren; Shi, Jin; Wang, Jinfang; Sun, Qianqian; Zhang, Haijun; Xing, Yanxia; Qi, Yan; Zhang, Na; Guo, Yang-Dong

    2014-08-01

    The secretion of organic acid anions from roots is an important mechanism for plant aluminum (Al) tolerance. Here we report cloning and characterizing BoMATE (KF031944), a multidrug and toxic compound extrusion (MATE) family gene from cabbage (Brassica oleracea). The expression of BoMATE was more abundant in roots than in shoots, and it was highly induced by Al treatment. The (14)C-citrate efflux experiments in oocytes demonstrated that BoMATE is a citrate transporter. Electrophysiological analysis and SIET analysis of Xenopus oocytes expressing BoMATE indicated BoMATE is activated by Al. Transient expression of BoMATE in onion epidermal cells demonstrated that it localized to the plasma membrane. Compared with the wild-type Arabidopsis, the transgenic lines constitutively overexpressing BoMATE enhanced Al tolerance and increased citrate secretion. In addition, Arabidopsis transgenic lines had a lower K(+) efflux and higher H(+) efflux, in the presence of Al, than control wild type in the distal elongation zone (DEZ). This is the first direct evidence that MATE protein is involved in the K(+) and H(+) flux in response to Al treatment. Taken together, our results show that BoMATE is an Al-induced citrate transporter and enhances aluminum tolerance in Arabidopsis thaliana.

  3. Molecular characterization of Atlas 66 derived wheat near-isogenic lines contrasting in Aluminum (Al) tolerance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aluminum (Al) toxicity is the major limiting factors for wheat growth in acidic soils. Genetic improvement of Al tolerance is one of the most cost-effective solutions to improve wheat productivity. The objective of this study was to identify DNA markers associated with the Al-tolerance in wheat usin...

  4. Physiological and molecular analysis of selected Kenyan maize lines for aluminum tolerance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aluminum (Al) toxicity is an important limitation to maize production in many tropical and sub-tropical acid soil areas. The aim of this study was to survey the variation in Al tolerance in a panel of maize lines adapted for Kenya and look for novel sources of Al tolerance. 112 Kenyan maize accessio...

  5. Fault Tolerant Optimal Control.

    DTIC Science & Technology

    1982-08-01

    i k+l since the cost to be minimized in (D.2.3) increases withXk (for fixed xsk). When we have b k _ x~ ji ] Aj M 2a(j) R(j) x bOk +l x]rkt] -b (j...22, pp. 236-239. 69. D.D.Sworder and L.L. Choi (1976): Stationary Cost Densities for Optimally Controlled Stochastic Systems, IEEE Trans. Automatic

  6. Fault tolerant control of spacecraft

    NASA Astrophysics Data System (ADS)

    Godard

    Autonomous multiple spacecraft formation flying space missions demand the development of reliable control systems to ensure rapid, accurate, and effective response to various attitude and formation reconfiguration commands. Keeping in mind the complexities involved in the technology development to enable spacecraft formation flying, this thesis presents the development and validation of a fault tolerant control algorithm that augments the AOCS on-board a spacecraft to ensure that these challenging formation flying missions will fly successfully. Taking inspiration from the existing theory of nonlinear control, a fault-tolerant control system for the RyePicoSat missions is designed to cope with actuator faults whilst maintaining the desirable degree of overall stability and performance. Autonomous fault tolerant adaptive control scheme for spacecraft equipped with redundant actuators and robust control of spacecraft in underactuated configuration, represent the two central themes of this thesis. The developed algorithms are validated using a hardware-in-the-loop simulation. A reaction wheel testbed is used to validate the proposed fault tolerant attitude control scheme. A spacecraft formation flying experimental testbed is used to verify the performance of the proposed robust control scheme for underactuated spacecraft configurations. The proposed underactuated formation flying concept leads to more than 60% savings in fuel consumption when compared to a fully actuated spacecraft formation configuration. We also developed a novel attitude control methodology that requires only a single thruster to stabilize three axis attitude and angular velocity components of a spacecraft. Numerical simulations and hardware-in-the-loop experimental results along with rigorous analytical stability analysis shows that the proposed methodology will greatly enhance the reliability of the spacecraft, while allowing for potentially significant overall mission cost reduction.

  7. Intelligent control of vacuum aluminum brazing

    SciTech Connect

    Zhong, G.; Pai, D.M.; Badgley, S.

    1995-06-01

    Vacuum brazing is a versatile modern day metal joining method. It usually includes vacuum producing, heating and residual gas analyzing systems. When used to join aluminum parts, the quality of the brazed joint is highly dependent on the residual gases in the vacuum, especially the residual oxygen and water vapor in the vacuum chamber which affect the formation of oxides. These vacuum environment brazing contaminants are reduced during the out-gassing processes of degassing and desorption during heating under vacuum. Exceeding the boundary limits of these contaminants causes unacceptable flow of braze filler in the joints during the brazing process. Identification of the quality control boundary for vacuum brazing of aluminum alloy makes computer control of vacuum brazing quality for aluminum alloys possible. The present study utilizes a residual gas analyzer (RGA) to monitor the partial pressures of residual gases during brazing. These data are transported to computer through the RS-232 interface port on the RGA, and used in real time to monitor the brazing quality by an algorithm based on the quality control boundary. If the quality is bad, the computer will send a ``hold`` signal to the heating system via another Rs-232 port until the environment is reestablished within the acceptable boundary.

  8. Progress in Aluminum Electrolysis Control and Future Direction for Smart Aluminum Electrolysis Plant

    NASA Astrophysics Data System (ADS)

    Zhang, Hongliang; Li, Tianshuang; Li, Jie; Yang, Shuai; Zou, Zhong

    2016-10-01

    The industrial aluminum reduction cell is an electrochemistry reactor that operates under high temperatures and highly corrosive conditions. However, these conditions have restricted the measurement of key control parameters, making the control of aluminum reduction cells a difficult problem in the industry. Because aluminum electrolysis control systems have a significant economic influence, substantial research has been conducted on control algorithms, control systems and information systems for aluminum reduction cells. This article first summarizes the development of control systems and then focuses on the progress made since 2000, including alumina concentration control, temperature control and electrolyte molecular ratio control, fault diagnosis, cell condition prediction and control system expansion. Based on these studies, the concept of a smart aluminum electrolysis plant is proposed. The frame construction, key problems and current progress are introduced. Finally, several future directions are discussed.

  9. Progress in Aluminum Electrolysis Control and Future Direction for Smart Aluminum Electrolysis Plant

    NASA Astrophysics Data System (ADS)

    Zhang, Hongliang; Li, Tianshuang; Li, Jie; Yang, Shuai; Zou, Zhong

    2017-02-01

    The industrial aluminum reduction cell is an electrochemistry reactor that operates under high temperatures and highly corrosive conditions. However, these conditions have restricted the measurement of key control parameters, making the control of aluminum reduction cells a difficult problem in the industry. Because aluminum electrolysis control systems have a significant economic influence, substantial research has been conducted on control algorithms, control systems and information systems for aluminum reduction cells. This article first summarizes the development of control systems and then focuses on the progress made since 2000, including alumina concentration control, temperature control and electrolyte molecular ratio control, fault diagnosis, cell condition prediction and control system expansion. Based on these studies, the concept of a smart aluminum electrolysis plant is proposed. The frame construction, key problems and current progress are introduced. Finally, several future directions are discussed.

  10. Aluminum tolerance is associated with higher MATE1 gene copy-number in maize

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Genome structure variation, including copy-number (CNV) and presence/absence variation (PAV), comprise a large extent of maize genetic diversity but their effect on phenotypes remains largely unexplored. Here we describe how copy-number variation in a major aluminum (Al) tolerance locus contributes ...

  11. Polyphenol-aluminum complex formation: Implications for aluminum tolerance in plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural polyphenols may play an important role in aluminum detoxification in some plants. We examined the interaction between Al3+ and the purified high molecular weight polyphenols pentagalloyl glucose (940 Da) and oenothein B (1568 Da), and the related compound methyl gallate (184 Da) at pH 4 and ...

  12. Molecular Characterization of Aluminium (aluminum) Tolerance in Rye

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aluminium (Al) toxicity, affecting around half of the world’s arable land, severely hinders the ability of crop plants to utilize moisture and nutrients by restricting root growth and function. Among the cultivated cereals, rye is the most Al-tolerant and represents an important potential source of ...

  13. Enhancement of aluminum tolerance in wheat by addition of chromosomes from the wild relative Leymus racemosus

    PubMed Central

    Mohammed, Yasir Serag Alnor; Eltayeb, Amin Elsadig; Tsujimoto, Hisashi

    2013-01-01

    Aluminum (Al) toxicity is the key factor limiting wheat production in acid soils. Soil liming has been used widely to increase the soil pH, but due to its high cost, breeding tolerant cultivars is more cost-effective mean to mitigate the problem. Tolerant cultivars could be developed by traditional breeding, genetic transformation or introgression of genes from wild relatives. We used 30 wheat alien chromosome addition lines to identify new genetic resources to improve wheat tolerance to Al and to identify the chromosomes harboring the tolerance genes. We evaluated these lines and their wheat background Chinese Spring for Al tolerance in hydroponic culture at various Al concentrations. We also investigated Al uptake, oxidative stress and cell membrane integrity. The L. racemosus chromosomes A and E significantly enhanced the Al tolerance of the wheat in term of relative root growth. At the highest Al concentration tested (200 μM), line E had the greatest tolerance. The introgressed chromosomes did not affect Al uptake of the tolerant lines. We attribute the improved tolerance conferred by chromosome E to improved cell membrane integrity. Chromosome engineering with these two lines could produce Al-tolerant wheat cultivars. PMID:24399913

  14. Natural variation underlies alterations in Nramp aluminum transporter (NRAT1) expression and function that play a key role in rice aluminum tolerance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aluminum (Al) toxicity is a major constraint for crop production on acid soils that comprise approximately 50% of arable land in the tropics and subtropics. Rice is the most Al tolerant cereal crop, and offers a good model for identifying Al tolerance genes and mechanisms. Here we investigated natur...

  15. Overexpression of Citrus junos mitochondrial citrate synthase gene in Nicotiana benthamiana confers aluminum tolerance.

    PubMed

    Deng, Wei; Luo, Keming; Li, Zhengguo; Yang, Yingwu; Hu, Nan; Wu, Yu

    2009-07-01

    Aluminum (Al) toxicity is one of the major factors that limit plant growth in acid soils. Al-induced release of organic acids into rhizosphere from the root apex has been identified as a major Al-tolerance mechanism in many plant species. In this study, Al tolerance of Yuzu (Citrus Junos Sieb. ex Tanaka) was tested on the basis of root elongation and the results demonstrated that Yuzu was Al tolerant compared with other plant species. Exposure to Al triggered the exudation of citrate from the Yuzu root. Thus, the mechanism of Al tolerance in Yuzu involved an Al-inducible increase in citrate release. Aluminum also elicited an increase of citrate content and increased the expression level of mitochondrial citrate synthase (CjCS) gene and enzyme activity in Yuzu. The CjCS gene was cloned from Yuzu and overexpressed in Nicotiana benthamiana using Agrobacterium tumefaciens-mediated methods. Increased expression level of the CjCS gene and enhanced enzyme activity were observed in transgenic plants compared with the wild-type plants. Root growth experiments showed that transgenic plants have enhanced levels of Al tolerance. The transgenic Nicotiana plants showed increased levels of citrate in roots compared to wild-type plants. The exudation of citrate from roots of the transgenic plants significantly increased when exposed to Al. The results with transgenic plants suggest that overexpression of mitochondrial CS can be a useful tool to achieve Al tolerance.

  16. Association Mapping for Aluminum Tolerance in a Core Collection of Rice Landraces

    PubMed Central

    Zhang, Peng; Zhong, Kaizhen; Tong, Hanhua; Shahid, Muhammad Qasim; Li, Jinquan

    2016-01-01

    Trivalent aluminum (Al3+) has drastic effect on the rice production in acidic soils. Elite genes for aluminum (Al) tolerance might exist in rice landraces. Therefore, the purpose of this research is to mine the elite genes within rice landraces. Association mapping for Al tolerance traits [i.e., relative root elongation (RRE)] was performed by using a core collection of 150 accessions of rice landraces (i.e., Ting’s rice core collection). Our results showed that the Ting’s rice core collection possessed a wide-range of phenotypic variation for Al tolerance, and the index of Al tolerance (RRE) was ranged from 0.22 to 0.89. Moreover, the groups with different origins and compositions of indica and japonica rice showed different degrees of tolerance to varying levels of Al. These rice landraces were further screened with 274 simple sequence repeat markers, and association mapping was performed using a mixed linear model approach. The mapping results showed that a total of 23 significant (P < 0.05) trait–marker associations were detected for Al tolerance. Of these, three associations (13%) were identical to the quantitative trait loci reported previously, and other 20 associations were reported for the first time in this study. The proportion of phenotypic variance (R2) explained by 23 significant associations ranged from 5.03 to 20.03% for Al tolerance. We detected several elite alleles for Al tolerance based on multiple comparisons of allelic effects, which could be used to develop Al tolerant rice cultivars through marker-assisted breeding. PMID:27757115

  17. Damage Tolerance Behavior of Friction Stir Welds in Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    McGill, Preston; Burkholder, Jonathan

    2012-01-01

    Friction stir welding is a solid state welding process used in the fabrication of various aerospace structures. Self-reacting and conventional friction stir welding are variations of the friction stir weld process employed in the fabrication of cryogenic propellant tanks which are classified as pressurized structure in many spaceflight vehicle architectures. In order to address damage tolerance behavior associated with friction stir welds in these safety critical structures, nondestructive inspection and proof testing may be required to screen hardware for mission critical defects. The efficacy of the nondestructive evaluation or the proof test is based on an assessment of the critical flaw size. Test data describing fracture behavior, residual strength capability, and cyclic mission life capability of friction stir welds at ambient and cryogenic temperatures have been generated and will be presented in this paper. Fracture behavior will include fracture toughness and tearing (R-curve) response of the friction stir welds. Residual strength behavior will include an evaluation of the effects of lack of penetration on conventional friction stir welds, the effects of internal defects (wormholes) on self-reacting friction stir welds, and an evaluation of the effects of fatigue cycled surface cracks on both conventional and selfreacting welds. Cyclic mission life capability will demonstrate the effects of surface crack defects on service load cycle capability. The fracture data will be used to evaluate nondestructive inspection and proof test requirements for the welds.

  18. Natural variation underlies alterations in NRAT1 expression and function that play a key role in rice aluminum tolerance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aluminum (Al) toxicity is a major constraint for crop production on acid soils which comprise approximately 40% of arable land in the tropics and subtropics. Rice is the most Al tolerant cereal crop, and offers a good model for identifying Al tolerance genes and mechanisms. Here we investigated natu...

  19. Mechanism of aluminum tolerance in snapbeans. Root exudation of citric acid

    SciTech Connect

    Miyasaka, S.C. ); Buta, J.G.; Howell, R.K.; Foy, C.D. )

    1991-07-01

    One proposed mechanism of aluminum (Al) tolerance in plants is the release of an Al-chelating compound into the rhizosphere. In this experiment, two cultivars of snapbeans (Phaseolus vulgaris L. Romano and Dade) that differ in Al tolerance were grown hydroponically with and without Al under aseptic conditions. After growth in nutrient solutions for 8 days, aliphatic and phenolic organic acids were analyzed in the culture solutions with an ion chromatograph and a high pressure liquid chromatograph. The tolerant snapbean, Dade when exposed to Al, exuded citric acid into the rhizosphere in a concentration that was 70 times as great as that of Dade grown without Al, and 10 times as great as that of Romano grown without Al, and 10 times as great as that of Romano, exuded only slightly more citric acid into the growing medium under Al-stress, compared to nonstressed conditions. Citric acid is known to chelate Al strongly and to reverse its phytotoxic effects. Also, citric acid has been shown previously to enhance the availability of phosphorus (P) from insoluble Al phosphates, Thus, one mechanism of Al-tolerance in snapbeans appears to be the exudation of citric acid into the rhizosphere, induced either by toxic levels of Al or by low P due to the precipitation of insoluble Al phosphates. The experiment was not able to distinguish between these two factors; however, tolerance to both primary and secondary Al-stress injuries are important for plants growing in Al-toxic soils.

  20. Retrotransposon-Mediated Aluminum Tolerance through Enhanced Expression of the Citrate Transporter OsFRDL41[OPEN

    PubMed Central

    Yamaji, Naoki; Fujii-Kashino, Miho

    2016-01-01

    High aluminum (Al) tolerance of rice (Oryza sativa) is controlled by multiple tolerance genes, but the regulatory mechanisms underlying the differential expression of these genes are poorly understood. Here, we investigated the factors regulating the expression of OsFRDL4, a gene encoding a citrate efflux transporter involved in Al-induced citrate secretion from the roots. Analysis with chromosome segment substitution lines derived from cv Nipponbare (high OsFRDL4 expression) and cv Kasalath (low OsFRDL4 expression) revealed that the differential expression of OsFRDL4 is responsible for the quantitative trait locus for Al tolerance detected previously on chromosome 1. Comparison of the OsFRDL4 gene structure in cv Nipponbare and cv Kasalath showed that there was no difference in the position of the transcriptional start site, but a 1.2-kb insertion showing high similarity to the solo long terminal repeat of the retrotransposon was found in the promoter region of OsFRDL4 in cv Nipponbare. This insertion showed higher promoter activity and contained nine cis-acting elements for ALUMINUM RESISTANCE TRANSCRIPTION FACTOR1 (ART1). However, this insertion did not alter the spatial expression or cellular localization of OsFRDL4. Furthermore, this insertion was found in most japonica varieties but was largely absent from indica varieties or wild rice species. These results indicate that the 1.2-kb insertion in the OsFRDL4 promoter region in japonica subspecies is responsible for their higher expression level of OsFRDL4 due to the increased number of cis-acting elements of ART1. Our results also suggest that this insertion event happened at the initial stage of domestication of japonica subspecies. PMID:27744299

  1. Tuning of fault tolerant control design parameters.

    PubMed

    DeLima, Pedro G; Yen, Gary G

    2008-01-01

    This paper presents two major contributions in the field of fault tolerant control. First, it gathers points of concern typical to most fault tolerant control applications and translates the chosen performance metrics into a set of six practical design specifications. Second, it proposes initialization and tuning procedures through which a particular fault tolerant control architecture not only can be set to comply with the required specifications, but also can be tuned online to compensate for a total of twelve properties, such as the noise rejection levels for fault detection and diagnosis signals. The proposed design is realized over a powerful architecture that combines the flexibility of adaptive critic designs with the long term memory and learning capabilities of a supervisor. This paper presents a practical design procedure to facilitate the applications of a fundamentally sound fault tolerant control architecture in real-world problems.

  2. Mechanical behavior of aluminum-bearing ferritic alloys for accident-tolerant fuel cladding applications

    NASA Astrophysics Data System (ADS)

    Guria, Ankan

    Nuclear power currently provides about 13% of electrical power worldwide. Nuclear reactors generating this power traditionally use Zirconium (Zr) based alloys as the fuel cladding material. Exothermic reaction of Zr with steam under accident conditions may lead to production of hydrogen with the possibility of catastrophic consequences. Following the Fukushima-Daiichi incident, the exploration of accident-tolerant fuel cladding materials accelerated. Aluminum-rich (around 5 wt. %) ferritic steels such as Fecralloy, APMT(TM) and APM(TM) are considered as potential materials for accident-tolerant fuel cladding applications. These materials create an aluminum-based oxide scale protecting the alloy at elevated temperatures. Tensile deformation behavior of the above alloys was studied at different temperatures (25-500 °C) at a strain rate of 10-3 s-1 and correlated with microstructural characteristics. Higher strength and decent ductility of APMT(TM) led to further investigation of the alloy at various combination of strain rates and temperatures followed by fractography and detailed microscopic analyses. Serrations appeared in the stress-strain curves of APMT(TM) and Fecralloy steel tested in a limited temperature range (250-400 °C). The appearance of serrations is explained on the basis of dynamic strain aging (DSA) effect due to solute-dislocation interactions. The research in this study is being performed using the funds received from the US DOE Office of Nuclear Energy's Nuclear Energy University Programs (NEUP).

  3. Parametric Modeling and Fault Tolerant Control

    NASA Technical Reports Server (NTRS)

    Wu, N. Eva; Ju, Jianhong

    2000-01-01

    Fault tolerant control is considered for a nonlinear aircraft model expressed as a linear parameter-varying system. By proper parameterization of foreseeable faults, the linear parameter-varying system can include fault effects as additional varying parameters. A recently developed technique in fault effect parameter estimation allows us to assume that estimates of the fault effect parameters are available on-line. Reconfigurability is calculated for this model with respect to the loss of control effectiveness to assess the potentiality of the model to tolerate such losses prior to control design. The control design is carried out by applying a polytopic method to the aircraft model. An error bound on fault effect parameter estimation is provided, within which the Lyapunov stability of the closed-loop system is robust. Our simulation results show that as long as the fault parameter estimates are sufficiently accurate, the polytopic controller can provide satisfactory fault-tolerance.

  4. Quantitative iTRAQ Proteomics Revealed Possible Roles for Antioxidant Proteins in Sorghum Aluminum Tolerance

    PubMed Central

    Zhou, Dangwei; Yang, Yong; Zhang, Jinbiao; Jiang, Fei; Craft, Eric; Thannhauser, Theodore W.; Kochian, Leon V.; Liu, Jiping

    2017-01-01

    Aluminum (Al) toxicity inhibits root growth and limits crop yields on acid soils worldwide. However, quantitative information is scarce on protein expression profiles under Al stress in crops. In this study, we report on the identification of potential Al responsive proteins from root tips of Al sensitive BR007 and Al tolerant SC566 sorghum lines using a strategy employing iTRAQ and 2D-liquid chromatography (LC) coupled to MS/MS (2D-LC-MS/MS). A total of 771 and 329 unique proteins with abundance changes of >1.5 or <0.67-fold were identified in BR007 and SC566, respectively. Protein interaction and pathway analyses indicated that proteins involved in the antioxidant system were more abundant in the tolerant line than in the sensitive one after Al treatment, while opposite trends were observed for proteins involved in lignin biosynthesis. Higher levels of ROS accumulation in root tips of the sensitive line due to decreased activity of antioxidant enzymes could lead to higher lignin production and hyper-accumulation of toxic Al in cell walls. These results indicated that activities of peroxidases and the balance between production and consumption of ROS could be important for Al tolerance and lignin biosynthesis in sorghum. PMID:28119720

  5. Targeting the aluminum tolerance gene Alt3 region in rye, using rice/rye micro-colinearity.

    PubMed

    Miftahudin; Chikmawati, T; Ross, K; Scoles, G J; Gustafson, J P

    2005-03-01

    Characterization and manipulation of aluminum (Al) tolerance genes offers a solution to Al toxicity problems in crop cultivation on acid soil, which composes approximately 40% of all arable land. By exploiting the rice (Oryza sativa L.)/rye (Secale cereale L.) syntenic relationship, the potential for map-based cloning of genes controlling Al tolerance in rye (the most Al-tolerant cereal) was explored. An attempt to clone an Al tolerance gene (Alt3) from rye was initiated by using DNA markers flanking the rye Alt3 gene, from many cereals. Two rice-derived, PCR-based markers flanking the Alt3 gene, B1 and B4, were used to screen 1,123 plants of a rye F2 population segregating for Alt3. Fifteen recombinant plants were identified. Four additional RFLP markers developed from rice genes/putative genes, spanning 10 kb of a 160-kb rice BAC, were mapped to the Alt3 region. Two rice markers flanked the Alt3 locus at a distance of 0.05 cM, while two others co-segregated with it. The rice/rye micro-colinearity worked very well to delineate and map the Alt3 gene region in rye. A rye fragment suspected to be part of the Alt3 candidate gene was identified, but at this level, the rye/rice microsynteny relationship broke down. Because of sequence differences between rice and rye and the complexity of the rye sequence, we have been unable to clone a full-length candidate gene in rye. Further attempts to clone a full-length rye Alt3 candidate gene will necessitate the creation of a rye large-insert library.

  6. Incomplete transfer of accessory loci influencing SbMATE expression underlies genetic background effects for aluminum tolerance in sorghum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Impaired root development caused by aluminum (Al) toxicity is a major cause for grain yield reduction for crops cultivated on acid soils which are widespread worldwide. In sorghum, the major Al tolerance locus, AltSB, is due to the function of SbMATE, which is an Al-activated root citrate transporte...

  7. Association mapping provides insights into the origin and the fine structure of the sorghum aluminum tolerance locus, AltSB

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Root damage caused by aluminum (Al) toxicity is a major cause of grain yield reduction on acid soils, which are prevalent in tropical and subtropical regions of the world where food security is most tenuous. In sorghum, Al tolerance is conferred by SbMATE, an Al-activated root citrate efflux transpo...

  8. Coaxial Control of Aluminum and Steel Laser Brazing Processes

    NASA Astrophysics Data System (ADS)

    Frank, Sascha; Ungers, Michael; Rolser, Raphael

    Laser brazing has become firmly established as a joining process in the automotive industry. While this process offers many advantages, brazed seams also have to meet particularly high quality requirements. The challenge of creating a suitable online quality control system is magnified by the increasing use of aluminum in automotive engineering. This paper introduces recent works on the development of a system for controlling both aluminum and steel brazing processes. It also discusses some of the challenges connected to this task and discloses some of the results derived from the corresponding process analysis.

  9. A damage tolerance comparison of 7075-T6 aluminum alloy and IM7/977-2 carbon/epoxy

    NASA Technical Reports Server (NTRS)

    Nettles, Alan T.; Lance, David G.; Hodge, Andrew J.

    1991-01-01

    A comparison of low velocity impact damage between one of the strongest aluminum alloys, to a new, damage tolerant resin system as a matrix for high strength carbon fibers was examined in this study. The aluminum and composite materials were used as face sheets on a 0.13 g/cu cm aluminum honeycomb. Four levels of impact energy were used; 2.6 J, 5.3 J, 7.8 J and 9.9 J. The beams were compared for static strength and fatique life by use of the four-point bend flexure test. It was found that in the undamaged state the specific strength of the composite face sheets was about twice that of the aluminum face sheets. A sharp drop in strength was observed for the composite specimens impacted at the lowest (2.6J) energy level, but the overall specific strength was still higher than for the aluminum specimens. At all impact energy levels tested, the static specific strength of the composite face sheets were significantly higher than the aluminum face sheets. The fatigue life of the most severely damaged composite specimen was about 17 times greater than the undamaged aluminum specimens when cycled at 1 Hz between 20 percent and 85 percent of ultimate breaking load.

  10. Femtosecond laser micromachining of aluminum surfaces under controlled gas atmospheres

    NASA Astrophysics Data System (ADS)

    Robinson, G. M.; Jackson, M. J.

    2006-04-01

    The interaction of 180 femtosecond (fs), 775 nm laser pulses with the surface of aluminum under controlled gas atmospheres at ambient pressure has been investigated to study material redeposition, residual surface roughness, and ablation rate. The effect of using various gases to protect the surface of the material appears to interfere with the effects of the plasma and can change the resulting microstructure of the machined surface. By varying the combinations of fluence and laser-scanning speed during ultrafast ablation at high repetition rates, an optimum micromachining condition can be reached, depending on the type of gas used during machining. The debris produced under certain laser-machining conditions tends to produce pure aluminum nanoparticles that are deposited very close to the machined feature by the gas used to protect the surface of the aluminum.

  11. Temperature Controlled Laser Joining of Aluminum to Galvanized Steel

    NASA Astrophysics Data System (ADS)

    Weller, Daniel; Simon, Jörg; Stritt, Peter; Weber, Rudolf; Graf, Thomas; Bezençon, Cyrille; Bassi, Corrado

    Reliable joining of 6000 series aluminum alloy to galvanized steel is a challenge for current manufacturing technologies. To control and limit the formation of brittle intermetallic phases, mixing of both metals in liquid state has to be avoided. It has been shown that laser weld-brazing is a possible process. Thereby the aluminum and zinc layer of the galvanized steel are molten and the steel remains solid during the process. In addition, to avoid zinc degassing, the aluminum melt bath temperature has to be below zinc boiling temperature of 907°C. To meet these requirements a temperature controlled laser process was developed, allowing to join the two materials without flux and filler material. The thickness of the intermetallic layer shows a dependency on the set temperature used to control the process. At optimum set temperature the thickness of intermetallic phases can be limited to about 5 μm. Tensile strengths of the joints of up to 75% of the aluminum base material were achieved.

  12. Performance Analysis on Fault Tolerant Control System

    NASA Technical Reports Server (NTRS)

    Shin, Jong-Yeob; Belcastro, Christine

    2005-01-01

    In a fault tolerant control (FTC) system, a parameter varying FTC law is reconfigured based on fault parameters estimated by fault detection and isolation (FDI) modules. FDI modules require some time to detect fault occurrences in aero-vehicle dynamics. In this paper, an FTC analysis framework is provided to calculate the upper bound of an induced-L(sub 2) norm of an FTC system with existence of false identification and detection time delay. The upper bound is written as a function of a fault detection time and exponential decay rates and has been used to determine which FTC law produces less performance degradation (tracking error) due to false identification. The analysis framework is applied for an FTC system of a HiMAT (Highly Maneuverable Aircraft Technology) vehicle. Index Terms fault tolerant control system, linear parameter varying system, HiMAT vehicle.

  13. Overexpression of a Soybean Ariadne-Like Ubiquitin Ligase Gene GmARI1 Enhances Aluminum Tolerance in Arabidopsis

    PubMed Central

    Zhang, Xiaolian; Wang, Ning; Chen, Pei; Gao, Mengmeng; Liu, Juge; Wang, Yufeng; Zhao, Tuanjie; Li, Yan; Gai, Junyi

    2014-01-01

    Ariadne (ARI) subfamily of RBR (Ring Between Ring fingers) proteins have been found as a group of putative E3 ubiquitin ligases containing RING (Really Interesting New Gene) finger domains in fruitfly, mouse, human and Arabidopsis. Recent studies showed several RING-type E3 ubiquitin ligases play important roles in plant response to abiotic stresses, but the function of ARI in plants is largely unknown. In this study, an ariadne-like E3 ubiquitin ligase gene was isolated from soybean, Glycine max (L.) Merr., and designated as GmARI1. It encodes a predicted protein of 586 amino acids with a RBR supra-domain. Subcellular localization studies using Arabidopsis protoplast cells indicated GmARI protein was located in nucleus. The expression of GmARI1 in soybean roots was induced as early as 2–4 h after simulated stress treatments such as aluminum, which coincided with the fact of aluminum toxicity firstly and mainly acting on plant roots. In vitro ubiquitination assay showed GmARI1 protein has E3 ligase activity. Overexpression of GmARI1 significantly enhanced the aluminum tolerance of transgenic Arabidopsis. These findings suggest that GmARI1 encodes a RBR type E3 ligase, which may play important roles in plant tolerance to aluminum stress. PMID:25364908

  14. Physiological characterization of aluminum tolerance and accumulation in tartary and wild buckwheat.

    PubMed

    Wang, Hua; Chen, Rong Fu; Iwashita, Takashi; Shen, Ren Fang; Ma, Jian Feng

    2015-01-01

    Ionic aluminum (Al) is toxic for plant growth, but some plant species are able to accumulate Al at high concentrations without showing toxicity symptoms. In order to determine whether other species in the genus Fagopyrum are able to accumulate Al like common buckwheat (Fagopyrum esculentum), we investigated the external and internal detoxification mechanisms of Al in two self-compatible species: tartary (Fagopyrum tataricum) and wild buckwheat (Fagopyrum homotropicum). Both tartary and wild buckwheat showed high Al tolerance comparable to common buckwheat. Furthermore, these two species also secreted oxalate rapidly from the roots in response to Al in a time-dependent manner. Both tartary and wild buckwheat accumulated > 1 mg g(-1) Al in the leaves after short-term exposure to Al. Analysis with (27) Al-nuclear magnetic resonance (NMR) revealed that Al was present in the form of Al-oxalate (1 : 3 ratio) in the roots and leaves, but in the form of Al-citrate (1 : 1 ratio) in the xylem sap in both species. These results indicate that similar to common buckwheat, both tartary and wild buckwheat detoxify Al externally and internally, respectively, by secreting oxalate from the roots and by forming the Al-oxalate complex, which is a nonphytotoxic form. These features of Al response and accumulation may be conserved in genus Fagopyrum.

  15. Damage Tolerance Assessment of Friction Pull Plug Welds in an Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    McGill, Preston; Burkholder, Jonathan

    2012-01-01

    Friction stir welding is a solid state welding process used in the fabrication of cryogenic propellant tanks. Self-reacting friction stir welding is one variation of the friction stir weld process being developed for manufacturing tanks. Friction pull plug welding is used to seal the exit hole that remains in a circumferential self-reacting friction stir weld. A friction plug weld placed in a self-reacting friction stir weld results in a non-homogenous weld joint where the initial weld, plug weld, their respective heat affected zones and the base metal all interact. The welded joint is a composite plastically deformed material system with a complex residual stress field. In order to address damage tolerance concerns associated with friction plug welds in safety critical structures, such as propellant tanks, nondestructive inspection and proof testing may be required to screen hardware for mission critical defects. The efficacy of the nondestructive evaluation or the proof test is based on an assessment of the critical flaw size. Test data relating residual strength capability to flaw size in an aluminum alloy friction plug weld will be presented.

  16. Investigations of Aluminum-Doped Self-Healing Zircaloy Surfaces in Context of Accident-Tolerant Fuel Cladding Research

    NASA Astrophysics Data System (ADS)

    Carr, James; Vasudevamurthy, Gokul; Snead, Lance; Hinderliter, Brian; Massey, Caleb

    2016-06-01

    We present here some important results investigating aluminum as an effective surface dopant for increased oxidation resistance of zircaloy nuclear fuel cladding. At first, the transport behavior of aluminum into reactor grade zircaloy was studied using simple diffusion couples at temperatures greater than 770 K. The experiments revealed the formation of tens of microns thick graded Zr-Al layers. The activation energy of aluminum in zircaloy was found to be ~175 kJ/mol (~1.8 eV), indicating the high mobility of aluminum in zircaloy. Subsequently, aluminum sputter-coated zircaloy coupons were heat-treated to achieve surface doping and form compositionally graded layers. These coupons were then tested in steam environments at 1073 and 1273 K. The microstructure of the as-fabricated and steam-corroded specimens was compared to those of pure zircaloy control specimens. Analysis of data revealed that aluminum effectively competed with zircaloy for oxygen up until 1073 K blocking oxygen penetration, with no traces of large scale spalling, indicating mechanically stable interfaces and surfaces. At the highest steam test temperatures, aluminum was observed to segregate from the Zr-Al alloy under layers and migrate to the surface forming discrete clusters. Although this is perceived as an extremely desirable phenomenon, in the current experiments, oxygen was observed to penetrate into the zirconium-rich under layers, which could be attributed to formation of surface defects such as cracks in the surface alumina layers.

  17. Genetic architecture of aluminum tolerance in rice (Oryza sativa) determined through genome-wide association analysis and QTL mapping.

    PubMed

    Famoso, Adam N; Zhao, Keyan; Clark, Randy T; Tung, Chih-Wei; Wright, Mark H; Bustamante, Carlos; Kochian, Leon V; McCouch, Susan R

    2011-08-01

    Aluminum (Al) toxicity is a primary limitation to crop productivity on acid soils, and rice has been demonstrated to be significantly more Al tolerant than other cereal crops. However, the mechanisms of rice Al tolerance are largely unknown, and no genes underlying natural variation have been reported. We screened 383 diverse rice accessions, conducted a genome-wide association (GWA) study, and conducted QTL mapping in two bi-parental populations using three estimates of Al tolerance based on root growth. Subpopulation structure explained 57% of the phenotypic variation, and the mean Al tolerance in Japonica was twice that of Indica. Forty-eight regions associated with Al tolerance were identified by GWA analysis, most of which were subpopulation-specific. Four of these regions co-localized with a priori candidate genes, and two highly significant regions co-localized with previously identified QTLs. Three regions corresponding to induced Al-sensitive rice mutants (ART1, STAR2, Nrat1) were identified through bi-parental QTL mapping or GWA to be involved in natural variation for Al tolerance. Haplotype analysis around the Nrat1 gene identified susceptible and tolerant haplotypes explaining 40% of the Al tolerance variation within the aus subpopulation, and sequence analysis of Nrat1 identified a trio of non-synonymous mutations predictive of Al sensitivity in our diversity panel. GWA analysis discovered more phenotype-genotype associations and provided higher resolution, but QTL mapping identified critical rare and/or subpopulation-specific alleles not detected by GWA analysis. Mapping using Indica/Japonica populations identified QTLs associated with transgressive variation where alleles from a susceptible aus or indica parent enhanced Al tolerance in a tolerant Japonica background. This work supports the hypothesis that selectively introgressing alleles across subpopulations is an efficient approach for trait enhancement in plant breeding programs and demonstrates

  18. Fabrication of sub-15 nm aluminum wires by controlled etching

    NASA Astrophysics Data System (ADS)

    Morgan-Wall, T.; Hughes, H. J.; Hartman, N.; McQueen, T. M.; Marković, N.

    2014-04-01

    We describe a method for the fabrication of uniform aluminum nanowires with diameters below 15 nm. Electron beam lithography is used to define narrow wires, which are then etched using a sodium bicarbonate solution, while their resistance is simultaneously measured in-situ. The etching process can be stopped when the desired resistance is reached, and can be restarted at a later time. The resulting nanowires show a superconducting transition as a function of temperature and magnetic field that is consistent with their smaller diameter. The width of the transition is similar to that of the lithographically defined wires, indicating that the etching process is uniform and that the wires are undamaged. This technique allows for precise control over the normal state resistance and can be used to create a variety of aluminum nanodevices.

  19. Evaluating the Effects of Aluminum-Containing and Non-Aluminum Containing Deodorants on Axillary Skin Toxicity During Radiation Therapy for Breast Cancer: A 3-Armed Randomized Controlled Trial

    SciTech Connect

    Lewis, Lucy; Carson, Sharron; Bydder, Sean; Athifa, Mariyam; Williams, Anne M.; Bremner, Alexandra

    2014-11-15

    Purpose: Deodorant use during radiation therapy for breast cancer has been controversial as there are concerns deodorant use may exacerbate axillary skin toxicity. The present study prospectively determined the use of both aluminum-containing and non aluminum containing deodorants on axillary skin toxicity during conventionally fractionated postoperative radiation therapy for breast cancer. Methods and Materials: This 3-arm randomized controlled study was conducted at a single center, tertiary cancer hospital between March 2011 and April 2013. Participants were randomized to 1 of 2 experimental groups (aluminum-containing deodorant and soap or non–aluminum containing deodorant and soap) or a control group (soap). A total of 333 participants were randomized. Generalized estimating equations were used to estimate and compare the odds of experiencing high levels of sweating and skin toxicity in each of the deodorant groups to the odds in the control group. The study evaluated a range of endpoints including objective measurements of axilla sweating, skin toxicity, pain, itch and burning. Quality of life was assessed with a validated questionnaire. Results: Radiation characteristics were similar across all groups. Patients in the deodorant groups did not report significantly different ratings for axillary pain, itch, or burning compared with the control group. Patients in the aluminum-containing deodorant group experienced significantly less sweating than the control; the odds of their sweating being barely tolerable and frequently or always interfering with their daily activities was decreased by 85% (odds ratio, 0.15; 95% confidence interval, 0.03-0.91). Conclusions: We found no evidence that the use of either aluminum-containing or non–aluminum containing deodorant adversely effects axillary skin reaction during conventionally fractionated radiation therapy for breast cancer. Our analysis also suggests patients in the aluminum-containing deodorant arm had

  20. VOC emissions controls for aluminum cold rolling mills

    SciTech Connect

    Genoble, A.L.; Lagoe, D.J.; Wasyluk, W.J.R.

    1997-12-31

    This paper is a case history of retrofitting VOC emissions controls to two (2) aluminum cold rolling mills at an aluminum sheet complex in central New York. The plant site was located in the northeast ozone transport region, and it was necessary to achieve compliance with VOC emissions limitations. Emissions control equipment included high efficiency filters for VOC mists and a wash oil process for scrubbing VOC vapors. All rolling oil was recovered for reuse on site. A vacuum distillation process was used to separate wash oil from rolling oil. The equipment began operating in mid-1995, and long term results have proven the validity of the recovery concept. Total project costs were $7.2 million for two (2) 60,000 ACFM systems. Project duration from the date of the initial request for equipment price quotations to the first round of stack testing was twenty (20) months. The modular construction of the vacuum distillation equipment simplified field erection and shortened the duration of field work. Stack testing indicated overall VOC collection efficiencies that exceeded regulatory requirements. Initially, problems were experienced with Method 25 stack testing methodology. Final results were confirmed by two (2) independent methods.

  1. Eigenstructure Assignment for Fault Tolerant Flight Control Design

    NASA Technical Reports Server (NTRS)

    Sobel, Kenneth; Joshi, Suresh (Technical Monitor)

    2002-01-01

    In recent years, fault tolerant flight control systems have gained an increased interest for high performance military aircraft as well as civil aircraft. Fault tolerant control systems can be described as either active or passive. An active fault tolerant control system has to either reconfigure or adapt the controller in response to a failure. One approach is to reconfigure the controller based upon detection and identification of the failure. Another approach is to use direct adaptive control to adjust the controller without explicitly identifying the failure. In contrast, a passive fault tolerant control system uses a fixed controller which achieves acceptable performance for a presumed set of failures. We have obtained a passive fault tolerant flight control law for the F/A-18 aircraft which achieves acceptable handling qualities for a class of control surface failures. The class of failures includes the symmetric failure of any one control surface being stuck at its trim value. A comparison was made of an eigenstructure assignment gain designed for the unfailed aircraft with a fault tolerant multiobjective optimization gain. We have shown that time responses for the unfailed aircraft using the eigenstructure assignment gain and the fault tolerant gain are identical. Furthermore, the fault tolerant gain achieves MIL-F-8785C specifications for all failure conditions.

  2. Impurity control and corrosion resistance of magnesium-aluminum alloy

    SciTech Connect

    Liu, M.; Song, GuangLing

    2013-01-01

    The corrosion resistance of magnesium alloys is very sensitive to the contents of impurity elements such as iron. In this study, a series of diecast AXJ530 magnesium alloy samples were prepared with additions of Mn and Fe. Through a comprehensive phase diagram calculation and corrosion evaluation, the mechanisms for the tolerance limit of Fe in magnesium alloy are discussed. This adds a new dimension to control the alloying impurity in terms of alloying composition design and casting conditions.

  3. Complete mitochondrial genome of the aluminum-tolerant fungus Rhodotorula taiwanensis RS1 and comparative analysis of Basidiomycota mitochondrial genomes

    PubMed Central

    Zhao, Xue Qiang; Aizawa, Tomoko; Schneider, Jessica; Wang, Chao; Shen, Ren Fang; Sunairi, Michio

    2013-01-01

    The complete mitochondrial genome of Rhodotorula taiwanensis RS1, an aluminum-tolerant Basidiomycota fungus, was determined and compared with the known mitochondrial genomes of 12 Basidiomycota species. The mitochondrial genome of R. taiwanensis RS1 is a circular DNA molecule of 40,392 bp and encodes the typical 15 mitochondrial proteins, 23 tRNAs, and small and large rRNAs as well as 10 intronic open reading frames. These genes are apparently transcribed in two directions and do not show syntenies in gene order with other investigated Basidiomycota species. The average G+C content (41%) of the mitochondrial genome of R. taiwanensis RS1 is the highest among the Basidiomycota species. Two introns were detected in the sequence of the atp9 gene of R. taiwanensis RS1, but not in that of other Basidiomycota species. Rhodotorula taiwanensis is the first species of the genus Rhodotorula whose full mitochondrial genome has been sequenced; and the data presented here supply valuable information for understanding the evolution of fungal mitochondrial genomes and researching the mechanism of aluminum tolerance in microorganisms. PMID:23427135

  4. New Insights into Aluminum Tolerance in Rice: The ASR5 Protein Binds the STAR1 Promoter and Other Aluminum-Responsive Genes

    PubMed Central

    Margis-Pinheiro, Marcia

    2014-01-01

    Aluminum (Al) toxicity in plants is one of the primary constraints in crop production. Al3+, the most toxic form of Al, is released into soil under acidic conditions and causes extensive damage to plants, especially in the roots. In rice, Al tolerance requires the ASR5 gene, but the molecular function of ASR5 has remained unknown. Here, we perform genome-wide analyses to identify ASR5-dependent Al-responsive genes in rice. Based on ASR5_RNAi silencing in plants, a global transcriptome analysis identified a total of 961 genes that were responsive to Al treatment in wild-type rice roots. Of these genes, 909 did not respond to Al in the ASR5_RNAi plants, indicating a central role for ASR5 in Al-responsive gene expression. Under normal conditions, without Al treatment, the ASR5_RNAi plants expressed 1.756 genes differentially compared to the wild-type plants, and 446 of these genes responded to Al treatment in the wild-type plants. Chromatin immunoprecipitation followed by deep sequencing identified 104 putative target genes that were directly regulated by ASR5 binding to their promoters, including the STAR1 gene, which encodes an ABC transporter required for Al tolerance. Motif analysis of the binding peak sequences revealed the binding motif for ASR5, which was confirmed via in vitro DNA-binding assays using the STAR1 promoter. These results demonstrate that ASR5 acts as a key transcription factor that is essential for Al-responsive gene expression and Al tolerance in rice. PMID:24253199

  5. Model-Based Fault Tolerant Control

    NASA Technical Reports Server (NTRS)

    Kumar, Aditya; Viassolo, Daniel

    2008-01-01

    The Model Based Fault Tolerant Control (MBFTC) task was conducted under the NASA Aviation Safety and Security Program. The goal of MBFTC is to develop and demonstrate real-time strategies to diagnose and accommodate anomalous aircraft engine events such as sensor faults, actuator faults, or turbine gas-path component damage that can lead to in-flight shutdowns, aborted take offs, asymmetric thrust/loss of thrust control, or engine surge/stall events. A suite of model-based fault detection algorithms were developed and evaluated. Based on the performance and maturity of the developed algorithms two approaches were selected for further analysis: (i) multiple-hypothesis testing, and (ii) neural networks; both used residuals from an Extended Kalman Filter to detect the occurrence of the selected faults. A simple fusion algorithm was implemented to combine the results from each algorithm to obtain an overall estimate of the identified fault type and magnitude. The identification of the fault type and magnitude enabled the use of an online fault accommodation strategy to correct for the adverse impact of these faults on engine operability thereby enabling continued engine operation in the presence of these faults. The performance of the fault detection and accommodation algorithm was extensively tested in a simulation environment.

  6. Global Transcriptome Analysis Reveals Distinct Aluminum-Tolerance Pathways in the Al-Accumulating Species Hydrangea macrophylla and Marker Identification

    PubMed Central

    Chen, Haixia; Lu, Changping; Jiang, Hui; Peng, Jinhui

    2015-01-01

    Hydrangea (Hydrangea macrophylla) is a well known Al-accumulating plant, showing a high level of aluminum (Al) tolerance and accumulation. Although the physiological mechanisms for detoxification of Al and the roles of Al in blue hydrangea sepals have been reported, the molecular mechanisms of Al tolerance and accumulation are poorly understood in hydrangea. In this study, we conducted a genome-wide transcriptome analysis of Al-response genes in the roots and leaves of hydrangea by RNA sequencing (RNA-seq). The assembly of hydrangea transcriptome provides a rich source for gene identification and mining molecular markers, including single nucleotide polymorphism (SNP) and simple sequence repeat (SSR). A total of 401,215 transcripts with an average length of 810.77bp were assembled, generating 256,127 unigenes. After annotation, 4,287 genes in the roots and 730 genes in the leaves were up-regulated by Al exposure, while 236 genes in the roots and 719 genes in the leaves were down-regulated, respectively. Many transporters, including MATE and ABC families, were involved in the process of Al-citrate complex transporting from the roots in hydrangea. A plasma membrane Al uptake transporter, Nramp aluminum transporter was up-regulated in roots and leaves under Al stress, indicating it may play an important role in Al tolerance by reducing the level of toxic Al. Although the exact roles of these candidate genes remain to be examined, these results provide a platform for further functional analysis of the process of detoxification of Al in hydrangea. PMID:26660093

  7. The Basis of Aluminum Tolerance Encoded by the Alt3 Locus of Rye

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aluminium (Al) toxicity, affecting around half of the world’s arable land, severely hinders the ability of crop plants to cope with drought and nutrient stresses by restricting root growth and function. Among the cultivated cereals, rye is the most Al tolerant. At the Alt3 Al tolerance locus on rye ...

  8. Endosymbiont Tolerance and Control within Insect Hosts

    PubMed Central

    Ratzka, Carolin; Gross, Roy; Feldhaar, Heike

    2012-01-01

    Bacterial endosymbioses are very common in insects and can range from obligate to facultative as well as from mutualistic to pathogenic associations. Several recent studies provide new insight into how endosymbionts manage to establish chronic infections of their hosts without being eliminated by the host immune system. Endosymbiont tolerance may be achieved either by specific bacterial adaptations or by host measurements shielding bacteria from innate defense mechanisms. Nevertheless, insect hosts also need to sustain control mechanisms to prevent endosymbionts from unregulated proliferation. Emerging evidence indicates that in some cases the mutual adaptations of the two organisms may have led to the integration of the endosymbionts as a part of the host immune system. In fact, endosymbionts may provide protective traits against pathogens and predators and may even be required for the proper development of the host immune system during host ontogeny. This review gives an overview of current knowledge of molecular mechanisms ensuring maintenance of chronic infections with mutualistic endosymbionts and the impact of endosymbionts on host immune competence. PMID:26466544

  9. Root Adaptive Responses to Aluminum-Treatment Revealed by RNA-Seq in Two Citrus Species With Different Aluminum-Tolerance

    PubMed Central

    Guo, Peng; Qi, Yi-Ping; Yang, Lin-Tong; Lai, Ning-Wei; Ye, Xin; Yang, Yi; Chen, Li-Song

    2017-01-01

    Seedlings of aluminum (Al)-tolerant Citrus sinensis and Al-intolerant Citrus grandis were fertigated daily with nutrient solution containing 0 and 1.0 mM AlCl3●6H2O for 18 weeks. The Al-induced decreases of biomass and root total soluble proteins only occurred in C. grandis, demonstrating that C. sinensis had higher Al-tolerance than C. grandis. Under Al-treatment, C. sinensis roots secreted more citrate and malate than C. grandis ones; less Al was accumulated in C. sinenis than in C. grandis leaves. The Al-induced reduction of phosphorus was lesser in C. sinensis roots and leaves than in C. grandis ones, whereas the Al-induced increase of sulfur was greater in C. sinensis roots and leaves. Using RNA-seq, we isolated 1905 and 2670 differentially expressed genes (DEGs) from Al-treated C. sinensis than C. grandis roots, respectively. Among these DEGs, only 649 DEGs were shared by the two species. Further analysis suggested that the following several aspects conferred C. sinensis higher Al-tolerance: (a) Al-treated C. sinensis seedlings had a higher external Al detoxification capacity via enhanced Al-induced secretion of organic acid anions, a higher antioxidant capacity and a more efficient chelation system in roots; (b) Al-treated C. sinensis seedlings displayed a higher level of sulfur in roots and leaves possibly due to increased uptake and decreased export of sulfur and a higher capacity to maintain the cellular phosphorus homeostasis by enhancing phosphorus acquisition and utilization; (c) Cell wall and cytoskeleton metabolism, energy and carbohydrate metabolism and signal transduction displayed higher adaptative responses to Al in C. sinensis than in C. grandis roots; (d) More upregulated than downregulated genes related to fatty acid and amino acid metabolisms were isolated from Al-treated C. sinensis roots, but the reverse was the case for Al-treated C. grandis roots. These results provide a platform for further investigating the roles of genes possibly

  10. Root Adaptive Responses to Aluminum-Treatment Revealed by RNA-Seq in Two Citrus Species With Different Aluminum-Tolerance.

    PubMed

    Guo, Peng; Qi, Yi-Ping; Yang, Lin-Tong; Lai, Ning-Wei; Ye, Xin; Yang, Yi; Chen, Li-Song

    2017-01-01

    Seedlings of aluminum (Al)-tolerant Citrus sinensis and Al-intolerant Citrus grandis were fertigated daily with nutrient solution containing 0 and 1.0 mM AlCl3●6H2O for 18 weeks. The Al-induced decreases of biomass and root total soluble proteins only occurred in C. grandis, demonstrating that C. sinensis had higher Al-tolerance than C. grandis. Under Al-treatment, C. sinensis roots secreted more citrate and malate than C. grandis ones; less Al was accumulated in C. sinenis than in C. grandis leaves. The Al-induced reduction of phosphorus was lesser in C. sinensis roots and leaves than in C. grandis ones, whereas the Al-induced increase of sulfur was greater in C. sinensis roots and leaves. Using RNA-seq, we isolated 1905 and 2670 differentially expressed genes (DEGs) from Al-treated C. sinensis than C. grandis roots, respectively. Among these DEGs, only 649 DEGs were shared by the two species. Further analysis suggested that the following several aspects conferred C. sinensis higher Al-tolerance: (a) Al-treated C. sinensis seedlings had a higher external Al detoxification capacity via enhanced Al-induced secretion of organic acid anions, a higher antioxidant capacity and a more efficient chelation system in roots; (b) Al-treated C. sinensis seedlings displayed a higher level of sulfur in roots and leaves possibly due to increased uptake and decreased export of sulfur and a higher capacity to maintain the cellular phosphorus homeostasis by enhancing phosphorus acquisition and utilization; (c) Cell wall and cytoskeleton metabolism, energy and carbohydrate metabolism and signal transduction displayed higher adaptative responses to Al in C. sinensis than in C. grandis roots; (d) More upregulated than downregulated genes related to fatty acid and amino acid metabolisms were isolated from Al-treated C. sinensis roots, but the reverse was the case for Al-treated C. grandis roots. These results provide a platform for further investigating the roles of genes possibly

  11. The relationship between population structure and aluminum tolerance in cultivated sorghum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Acid soils comprise up to 50% of the world’s arable lands and in these areas aluminum (Al) toxicity impairs root growth, strongly limiting crop yield. Food security is thereby compromised in many developing countries that are located in tropical and subtropical regions worldwide. In sorghum, SbMATE,...

  12. Effects of short-term acid and aluminum exposure on the parr-smolt transformation in Atlantic salmon (Salmo salar): Disruption of seawater tolerance and endocrine status

    USGS Publications Warehouse

    Monette, M.Y.; Bjornsson, Bjorn Thrandur; McCormick, S.D.

    2008-01-01

    Episodic acidification resulting in increased acidity and inorganic aluminum (Ali) is known to interfere with the parr-smolt transformation of Atlantic salmon (Salmo salar), and has been implicated as a possible cause of population decline. To determine the extent and mechanism(s) by which short-term acid/Al exposure compromises smolt development, Atlantic salmon smolts were exposed to either control (pH 6.7-6.9) or acid/Al (pH 5.4-6.3, 28-64 ??g l-1 Ali) conditions for 2 and 5 days, and impacts on freshwater (FW) ion regulation, seawater (SW) tolerance, plasma hormone levels and stress response were examined. Gill Al concentrations were elevated in all smolts exposed to acid/Al relative to controls confirming exposure to increased Ali. There was no effect of acid/Al on plasma ion concentrations in FW however, smolts exposed to acid/Al followed by a 24 h SW challenge exhibited greater plasma Cl- levels than controls, indicating reduced SW tolerance. Loss of SW tolerance was accompanied by reductions in gill Na+,K+-ATPase (NKA) activity and Na+,K+,2Cl- (NKCC) cotransporter protein abundance. Acid/Al exposure resulted in decreased plasma insulin-like growth factor (IGF-I) and 3,3???,5???-triiodo-l-thyronine (T3) levels, whereas no effect of treatment was seen on plasma cortisol, growth hormone (GH), or thyroxine (T4) levels. Acid/Al exposure resulted in increased hematocrit and plasma glucose levels in FW, but both returned to control levels after 24 h in SW. The results indicate that smolt development and SW tolerance are compromised by short-term exposure to acid/Al in the absence of detectable impacts on FW ion regulation. Loss of SW tolerance during short-term acid/Al exposure likely results from reductions in gill NKA and NKCC, possibly mediated by decreases in plasma IGF-I and T3. ?? 2008 Elsevier Inc.

  13. Interaction between Aluminum Toxicity and Calcium Uptake at the Root Apex in Near-Isogenic Lines of Wheat (Triticum aestivum L.) Differing in Aluminum Tolerance.

    PubMed Central

    Ryan, P. R.; Kochian, L. V.

    1993-01-01

    Aluminum (Al) is toxic to plants at pH < 5.0 and can begin to inhibit root growth within 3 h in solution experiments. The mechanism by which this occurs is unclear. Disruption of calcium (Ca) uptake by Al has long been considered a possible cause of toxicity, and recent work with wheat (Triticum aestivum L. Thell) has demonstrated that Ca uptake at the root apex in an Al-sensitive cultivar (Scout 66) was inhibited more than in a tolerant cultivar (Atlas 66) (J.W. Huang, J.E. Shaff, D.L. Grunes, L.V. Kochian [1992] Plant Physiol 98: 230-237). We investigated this interaction further in wheat by measuring root growth and Ca uptake in three separate pairs of near-isogenic lines within which plants exhibit differential sensitivity to Al. The vibrating calcium-selective microelectrode technique was used to estimate net Ca uptake at the root apex of 6-d-old seedlings. Following the addition of 20 or 50 [mu]M AlCl3, exchange of Ca for Al in the root apoplasm caused a net Ca efflux from the root for up to 10 min. After 40 min of exposure to 50 [mu]M Al, cell wall exchange had ceased, and Ca uptake in the Al-sensitive plants of the near-isogenic lines was inhibited, whereas in the tolerant plants it was either unaffected or stimulated. This provides a general correlation between the inhibition of growth by Al and the reduction in Ca influx and adds some support to the hypothesis that a Ca/Al interaction may be involved in the primary mechanism of Al toxicity in roots. In some treatments, however, Al was able to inhibit root growth significantly without affecting net Ca influx. This suggests that the correlation between inhibition of Ca uptake and the reduction in root growth may not be a mechanistic association. The inhibition of Ca uptake by Al is discussed, and we speculate about possible mechanisms of tolerance. PMID:12231883

  14. Evaluation and control of environmental corrosion for aluminum and steel alloys

    NASA Technical Reports Server (NTRS)

    Franklin, D. B.

    1977-01-01

    Corrosion protection systems for aerospace application and the effects of surface treatments and methods of controlling stress corrosion are evaluated. Chromate pigmented systems were found to be most effective for aluminum alloys; zinc-rich coatings gave the greatest protection to steel alloys. Various steel and aluminum alloys are rated for stress corrosion resistance.

  15. Reliability of Fault Tolerant Control Systems. Part 1

    NASA Technical Reports Server (NTRS)

    Wu, N. Eva

    2001-01-01

    This paper reports Part I of a two part effort, that is intended to delineate the relationship between reliability and fault tolerant control in a quantitative manner. Reliability analysis of fault-tolerant control systems is performed using Markov models. Reliability properties, peculiar to fault-tolerant control systems are emphasized. As a consequence, coverage of failures through redundancy management can be severely limited. It is shown that in the early life of a syi1ein composed of highly reliable subsystems, the reliability of the overall system is affine with respect to coverage, and inadequate coverage induces dominant single point failures. The utility of some existing software tools for assessing the reliability of fault tolerant control systems is also discussed. Coverage modeling is attempted in Part II in a way that captures its dependence on the control performance and on the diagnostic resolution.

  16. A Multi-Environment Thermal Control System With Freeze-Tolerant Radiator

    NASA Technical Reports Server (NTRS)

    Chen, Weibo; Fogg, David; Mancini, Nick; Steele, John; Quinn, Gregory; Bue, Grant; Littibridge, Sean

    2013-01-01

    Future space exploration missions require advanced thermal control systems (TCS) to dissipate heat from spacecraft, rovers, or habitats operating in environments that can vary from extremely hot to extremely cold. A lightweight, reliable TCS is being developed to effectively control cabin and equipment temperatures under widely varying heat loads and ambient temperatures. The system uses freeze-tolerant radiators, which eliminate the need for a secondary circulation loop or heat pipe systems. Each radiator has a self-regulating variable thermal conductance to its ambient environment. The TCS uses a nontoxic, water-based working fluid that is compatible with existing lightweight aluminum heat exchangers. The TCS is lightweight, compact, and requires very little pumping power. The critical characteristics of the core enabling technologies were demonstrated. Functional testing with condenser tubes demonstrated the key operating characteristics required for a reliable, freeze-tolerant TCS, namely (1) self-regulating thermal conductance with short transient responses to varying thermal loads, (2) repeatable performance through freeze-thaw cycles, and (3) fast start-up from a fully frozen state. Preliminary coolant tests demonstrated that the corrosion inhibitor in the water-based coolant can reduce the corrosion rate on aluminum by an order of magnitude. Performance comparison with state-of-the-art designs shows significant mass and power saving benefits of this technology.

  17. Optimal Management of Redundant Control Authority for Fault Tolerance

    NASA Technical Reports Server (NTRS)

    Wu, N. Eva; Ju, Jianhong

    2000-01-01

    This paper is intended to demonstrate the feasibility of a solution to a fault tolerant control problem. It explains, through a numerical example, the design and the operation of a novel scheme for fault tolerant control. The fundamental principle of the scheme was formalized in [5] based on the notion of normalized nonspecificity. The novelty lies with the use of a reliability criterion for redundancy management, and therefore leads to a high overall system reliability.

  18. A fault-tolerant intelligent robotic control system

    NASA Technical Reports Server (NTRS)

    Marzwell, Neville I.; Tso, Kam Sing

    1993-01-01

    This paper describes the concept, design, and features of a fault-tolerant intelligent robotic control system being developed for space and commercial applications that require high dependability. The comprehensive strategy integrates system level hardware/software fault tolerance with task level handling of uncertainties and unexpected events for robotic control. The underlying architecture for system level fault tolerance is the distributed recovery block which protects against application software, system software, hardware, and network failures. Task level fault tolerance provisions are implemented in a knowledge-based system which utilizes advanced automation techniques such as rule-based and model-based reasoning to monitor, diagnose, and recover from unexpected events. The two level design provides tolerance of two or more faults occurring serially at any level of command, control, sensing, or actuation. The potential benefits of such a fault tolerant robotic control system include: (1) a minimized potential for damage to humans, the work site, and the robot itself; (2) continuous operation with a minimum of uncommanded motion in the presence of failures; and (3) more reliable autonomous operation providing increased efficiency in the execution of robotic tasks and decreased demand on human operators for controlling and monitoring the robotic servicing routines.

  19. An Oxalyl-CoA Synthetase Is Involved in Oxalate Degradation and Aluminum Tolerance1[OPEN

    PubMed Central

    Fan, Wei; Xu, Jia Meng; Gong, Yu Long; Jin, Jian Feng; Chen, Wei Wei; Liu, Ling Yu; Hai, Mei Rong

    2016-01-01

    Acyl Activating Enzyme3 (AAE3) was identified to be involved in the catabolism of oxalate, which is critical for seed development and defense against fungal pathogens. However, the role of AAE3 protein in abiotic stress responses is unknown. Here, we investigated the role of rice bean (Vigna umbellata) VuAAE3 in Al tolerance. Recombinant VuAAE3 protein has specific activity against oxalate, with Km = 121 ± 8.2 µm and Vmax of 7.7 ± 0.88 µmol min−1 mg−1 protein, indicating it functions as an oxalyl-CoA synthetase. VuAAE3-GFP localization suggested that this enzyme is a soluble protein with no specific subcellular localization. Quantitative reverse transcription-PCR and VuAAE3 promoter-GUS reporter analysis showed that the expression induction of VuAAE3 is mainly confined to rice bean root tips. Accumulation of oxalate was induced rapidly by Al stress in rice bean root tips, and exogenous application of oxalate resulted in the inhibition of root elongation and VuAAE3 expression induction, suggesting that oxalate accumulation is involved in Al-induced root growth inhibition. Furthermore, overexpression of VuAAE3 in tobacco (Nicotiana tabacum) resulted in the increase of Al tolerance, which was associated with the decrease of oxalate accumulation. In addition, NtMATE and NtALS3 expression showed no difference between transgenic lines and wild-type plants. Taken together, our results suggest that VuAAE3-dependent turnover of oxalate plays a critical role in Al tolerance mechanisms. PMID:27650448

  20. An Oxalyl-CoA Synthetase Is Involved in Oxalate Degradation and Aluminum Tolerance.

    PubMed

    Lou, He Qiang; Fan, Wei; Xu, Jia Meng; Gong, Yu Long; Jin, Jian Feng; Chen, Wei Wei; Liu, Ling Yu; Hai, Mei Rong; Yang, Jian Li; Zheng, Shao Jian

    2016-11-01

    Acyl Activating Enzyme3 (AAE3) was identified to be involved in the catabolism of oxalate, which is critical for seed development and defense against fungal pathogens. However, the role of AAE3 protein in abiotic stress responses is unknown. Here, we investigated the role of rice bean (Vigna umbellata) VuAAE3 in Al tolerance. Recombinant VuAAE3 protein has specific activity against oxalate, with Km = 121 ± 8.2 µm and Vmax of 7.7 ± 0.88 µmol min(-1) mg(-1) protein, indicating it functions as an oxalyl-CoA synthetase. VuAAE3-GFP localization suggested that this enzyme is a soluble protein with no specific subcellular localization. Quantitative reverse transcription-PCR and VuAAE3 promoter-GUS reporter analysis showed that the expression induction of VuAAE3 is mainly confined to rice bean root tips. Accumulation of oxalate was induced rapidly by Al stress in rice bean root tips, and exogenous application of oxalate resulted in the inhibition of root elongation and VuAAE3 expression induction, suggesting that oxalate accumulation is involved in Al-induced root growth inhibition. Furthermore, overexpression of VuAAE3 in tobacco (Nicotiana tabacum) resulted in the increase of Al tolerance, which was associated with the decrease of oxalate accumulation. In addition, NtMATE and NtALS3 expression showed no difference between transgenic lines and wild-type plants. Taken together, our results suggest that VuAAE3-dependent turnover of oxalate plays a critical role in Al tolerance mechanisms.

  1. Fault tolerant programmable digital attitude control electronics study

    NASA Technical Reports Server (NTRS)

    Sorensen, A. A.

    1974-01-01

    The attitude control electronics mechanization study to develop a fault tolerant autonomous concept for a three axis system is reported. Programmable digital electronics are compared to general purpose digital computers. The requirements, constraints, and tradeoffs are discussed. It is concluded that: (1) general fault tolerance can be achieved relatively economically, (2) recovery times of less than one second can be obtained, (3) the number of faulty behavior patterns must be limited, and (4) adjoined processes are the best indicators of faulty operation.

  2. Bacterial and fungal communities in bulk soil and rhizospheres of aluminum-tolerant and aluminum-sensitive maize (Zea mays L.) lines cultivated in unlimed and limed Cerrado soil.

    PubMed

    Da Mota, Fabio Faria; Gomes, Eliane Aparecida; Marriel, Ivanildo Evodio; Paiva, Edilson; Seldin, Lucy

    2008-05-01

    Liming of acidic soils can prevent aluminum toxicity and improve crop production. Some maize lines show aluminum (Al) tolerance, and exudation of organic acids by roots has been considered to represent an important mechanism involved in the tolerance. However, there is no information about the impact of liming on the structures of bacterial and fungal communities in Cerrado soil, nor if there are differences between the microbial communities from the rhizospheres of Al-tolerant and Al-sensitive maize lines. This study evaluated the effects of liming on the structure of bacterial and fungal communities in bulk soil and rhizospheres of Al-sensitive and Al-tolerant maize (Zea mays L.) lines cultivated in Cerrado soil by PCR-DGGE, 30 and 90 days after sowing. Bacterial fingerprints revealed that the bacterial communities from rhizospheres were more affected by aluminum stress in soil than by the maize line (Al-sensitive or Al-tolerant). Differences in bacterial communities were also observed over time (30 and 90 days after sowing), and these occurred mainly in the Actinobacteria. Conversely, fungal communities from the rhizosphere were weakly affected either by liming or by the rhizosphere, as observed from the DGGE profiles. Furthermore, only a few differences were observed in the DGGE profiles of the fungal populations during plant development when compared with bacterial communities. Cloning and sequencing of 16S rRNA gene fragments obtained from dominant DGGE bands detected in the bacterial profiles of the Cerrado bulk soil revealed that Actinomycetales and Rhizobiales were among the dominant ribotypes.

  3. A Convex Approach to Fault Tolerant Control

    NASA Technical Reports Server (NTRS)

    Maghami, Peiman G.; Cox, David E.; Bauer, Frank (Technical Monitor)

    2002-01-01

    The design of control laws for dynamic systems with the potential for actuator failures is considered in this work. The use of Linear Matrix Inequalities allows more freedom in controller design criteria than typically available with robust control. This work proposes an extension of fault-scheduled control design techniques that can find a fixed controller with provable performance over a set of plants. Through convexity of the objective function, performance bounds on this set of plants implies performance bounds on a range of systems defined by a convex hull. This is used to incorporate performance bounds for a variety of soft and hard failures into the control design problem.

  4. Autonomous Congestion Control in Delay-Tolerant Networks

    NASA Technical Reports Server (NTRS)

    Burleigh, Scott; Jennings, Esther; Schoolcraft, Joshua

    2006-01-01

    This presentation highlights communication congestion control in delay-tolerant networks (DTNs). Large-scale future space exploration will offer complex communication challenges that may be best addressed by establishing a network infrastructure. However, current internet techniques for congestion control are not well suited for operation of a network over interplanetary distances. An alternative, delay-tolerant technique for congestion control in a delay-tolerant network is presented. A simple DTN was constructed and an experimental congestion control mechanism was applied. The mechanism appeared to be effective and each router was able to make its bundle acceptance decisions autonomously. Future research will examine more complex topologies and alternative bundle acceptance rules that might enhance performance.

  5. A Decentralized Adaptive Approach to Fault Tolerant Flight Control

    NASA Technical Reports Server (NTRS)

    Wu, N. Eva; Nikulin, Vladimir; Heimes, Felix; Shormin, Victor

    2000-01-01

    This paper briefly reports some results of our study on the application of a decentralized adaptive control approach to a 6 DOF nonlinear aircraft model. The simulation results showed the potential of using this approach to achieve fault tolerant control. Based on this observation and some analysis, the paper proposes a multiple channel adaptive control scheme that makes use of the functionally redundant actuating and sensing capabilities in the model, and explains how to implement the scheme to tolerate actuator and sensor failures. The conditions, under which the scheme is applicable, are stated in the paper.

  6. Fault tolerant kinematic control of hyper-redundant manipulators

    NASA Technical Reports Server (NTRS)

    Bedrossian, Nazareth S.

    1994-01-01

    Hyper-redundant spatial manipulators possess fault-tolerant features because of their redundant structure. The kinematic control of these manipulators is investigated with special emphasis on fault-tolerant control. The manipulator tasks are viewed in the end-effector space while actuator commands are in joint-space, requiring an inverse kinematic algorithm to generate joint-angle commands from the end-effector ones. The rate-inverse kinematic control algorithm presented in this paper utilizes the pseudoinverse to accommodate for joint motor failures. An optimal scale factor for the robust inverse is derived.

  7. A Formate Dehydrogenase Confers Tolerance to Aluminum and Low pH1[OPEN

    PubMed Central

    Gong, Yu Long; Fan, Wei; Xu, Jia Meng; Liu, Yu; Cao, Meng Jie; Wang, Ming-Hu

    2016-01-01

    Formate dehydrogenase (FDH) is involved in various higher plant abiotic stress responses. Here, we investigated the role of rice bean (Vigna umbellata) VuFDH in Al and low pH (H+) tolerance. Screening of various potential substrates for the VuFDH protein demonstrated that it functions as a formate dehydrogenase. Quantitative reverse transcription-PCR and histochemical analysis showed that the expression of VuFDH is induced in rice bean root tips by Al or H+ stresses. Fluorescence microscopic observation of VuFDH-GFP in transgenic Arabidopsis plants indicated that VuFDH is localized in the mitochondria. Accumulation of formate is induced by Al and H+ stress in rice bean root tips, and exogenous application of formate increases internal formate content that results in the inhibition of root elongation and induction of VuFDH expression, suggesting that formate accumulation is involved in both H+- and Al-induced root growth inhibition. Over-expression of VuFDH in tobacco (Nicotiana tabacum) results in decreased sensitivity to Al and H+ stress due to less production of formate in the transgenic tobacco lines under Al and H+ stresses. Moreover, NtMATE and NtALS3 expression showed no changes versus wild type in these over-expression lines, suggesting that herein known Al-resistant mechanisms are not involved. Thus, the increased Al tolerance of VuFDH over-expression lines is likely attributable to their decreased Al-induced formate production. Taken together, our findings advance understanding of higher plant Al toxicity mechanisms, and suggest a possible new route toward the improvement of plant performance in acidic soils, where Al toxicity and H+ stress coexist. PMID:27021188

  8. Physiological, molecular, and cellular mechanisms of impaired seawater tolerance following exposure of Atlantic salmon, Salmo salar, smolts to acid and aluminum

    USGS Publications Warehouse

    Monette, M.Y.; Yada, T.; Matey, V.; McCormick, S.D.

    2010-01-01

    We examined the physiological, molecular, and cellular mechanisms of impaired ion regulation in Atlantic salmon, Salmo salar, smolts following acute acid and aluminum (Al) exposure. Smolts were exposed to: control (pH 6.5, 3.4??gl-1 Al), acid and low Al (LAl: pH 5.4, 11??gl-1 Al), acid and moderate Al (MAl: pH 5.3, 42??gl-1 Al), and acid and high Al (HAl: pH 5.4, 56??gl-1 Al) for two and six days. At each time-point, smolts were sampled directly from freshwater treatment tanks and after a 24h seawater challenge. Exposure to acid/MAl and acid/HAl led to accumulation of gill Al, substantial alterations in gill morphology, reduced gill Na+/K+-ATPase (NKA) activity, and impaired ion regulation in both freshwater and seawater. Exposure to acid/MAl for six days also led to a decrease in gill mRNA expression of the apical Cl- channel (cystic fibrosis transmembrane conductance regulator I), increased apoptosis upon seawater exposure, an increase in the surface expression of mitochondria-rich cells (MRCs) within the filament epithelium of the gill, but reduced abundance of gill NKA-positive MRCs. By contrast, smolts exposed to acid and the lowest Al concentration exhibited minor gill Al accumulation, slight morphological modifications in the gill, and impaired seawater tolerance in the absence of a detectable effect on freshwater ion regulation. These impacts were accompanied by decreased cell proliferation, a slight increase in the surface expression of MRCs within the filament epithelium, but no impact on gill apoptosis or total MRC abundance was observed. However, MRCs in the gills of smolts exposed to acid/LAl exhibited morphological alterations including decreased size, staining intensity, and shape factor. We demonstrate that the seawater tolerance of Atlantic salmon smolts is extremely sensitive to acute exposure to acid and low levels of Al, and that the mechanisms underlying this depend on the time-course and severity of Al exposure. We propose that when smolts are

  9. Comparative study of aluminum and copper transport and toxicity in an acid-tolerant freshwater green alga

    SciTech Connect

    Folsom, B.R.; Popescu, N.A.; Wood, J.M.

    1986-06-01

    A comparative study of the transport and toxicity of one nonessential metal (aluminum), and one essential metal (copper), has been performed with the acid-tolerant green alga Chlorella saccarophila. This organism was isolated from a naturally acidified lake and grows well in laboratory cultures at pH 3.0. Our results show that the fast-exchange ions Ca/sup 2 +/, Mg/sup 2 +/, and Na/sup +/ offer some protection against both Al/sup 3 +/ and Cu/sup 2 +/ toxicity whereas K/sup +/ protects against Al/sup 3 +/ toxicity but enhances Cu/sup 2 +/ toxicity. Plasma emission spectroscopy shows that complexation of Al/sup 3 +/ and Fe/sup 3 +/ to cell surfaces is important in preventing toxic cytoplasmic levels of these metals, both in culture media and in acid mine water. The aqueous ion chemistry for toxic metal uptake is simplified considerably in acidic conditions, where competing hydrolysis and precipitation reactions are eliminated. Therefore, simple competitive experiments can be performed quantitatively. 12 references, 7 figures, 1 table.

  10. Active Fault Tolerant Control for Ultrasonic Piezoelectric Motor

    NASA Astrophysics Data System (ADS)

    Boukhnifer, Moussa

    2012-07-01

    Ultrasonic piezoelectric motor technology is an important system component in integrated mechatronics devices working on extreme operating conditions. Due to these constraints, robustness and performance of the control interfaces should be taken into account in the motor design. In this paper, we apply a new architecture for a fault tolerant control using Youla parameterization for an ultrasonic piezoelectric motor. The distinguished feature of proposed controller architecture is that it shows structurally how the controller design for performance and robustness may be done separately which has the potential to overcome the conflict between performance and robustness in the traditional feedback framework. A fault tolerant control architecture includes two parts: one part for performance and the other part for robustness. The controller design works in such a way that the feedback control system will be solely controlled by the proportional plus double-integral PI2 performance controller for a nominal model without disturbances and H∞ robustification controller will only be activated in the presence of the uncertainties or an external disturbances. The simulation results demonstrate the effectiveness of the proposed fault tolerant control architecture.

  11. Controlling harmful algae blooms using aluminum-modified clay.

    PubMed

    Liu, Yang; Cao, Xihua; Yu, Zhiming; Song, Xiuxian; Qiu, Lixia

    2016-02-15

    The performances of aluminum chloride modified clay (AC-MC), aluminum sulfate modified clay (AS-MC) and polyaluminum chloride modified clay (PAC-MC) in the removal of Aureococcus anophagefferens were compared, and the potential mechanisms were analyzed according to the dispersion medium, suspension pH and clay surface charges. The results showed that AC-MC and AS-MC had better efficiencies in removing A.anophagefferens than PAC-MC. The removal mechanisms of the three modified clays varied. At optimal coagulation conditions, the hydrolysates of AC and AS were mainly monomers, and they transformed into Al(OH)3(am) upon their addition to algae culture, with the primary mechanism being sweep flocculation. The PAC mainly hydrolyzed to the polyaluminum compounds, which remained stable when added to the algae culture, and the flocculation mainly occurred through polyaluminum compounds. The suspension pH significantly influenced the aluminum hydrolysate and affected the flocculation between the modified clay and algae cells.

  12. Efficacy and Safety of Aluminum Chloride in Controlling External Hemorrhage: An Animal Model Study

    PubMed Central

    Nouri, Saeed; Sharif, Mohammad Reza; Panahi, Yunes; Ghanei, Mostafa; Jamali, Bardia

    2015-01-01

    Background: Despite all the progress in surgical science, bleeding caused by traffic accidents is still one of the challenges surgeons face in saving patients’ lives. Therefore, introducing an effective method to control external bleeding is an important research priority. Objectives: This study aimed to compare the hemostatic effect of aluminum chloride versus simple suturing in controlling external bleeding. Materials and Methods: This experimental study was conducted in Kashan, Iran. In this study, 60 male Wistar rats were randomly allocated into six groups. An incision, two centimeters (cm) long and half a cm deep, was made on each rat’s shaved back skin and the hemostatic time was measured once using aluminum chloride with different concentrations (5%, 10%, 15%, 25%, and 50%) and then using the control method (controlling hemorrhage by simple suturing). The skin tissue was assessed for pathological changes. Results: The hemostatic time of aluminum chloride 50%, 25%, 15%, 10% and 5% were 8.20 ± 0.919, 14.10 ± 1.37, 21.20 ± 1.31, 30.80 ± 1.68 and 42.00 ± 4.19 seconds, respectively. Also, the mean hemostasis time in the control group (suture) was 84.00 ± 4.05 seconds. The hemostatic times of different concentrations of aluminum chloride were significantly less than that of the control group. There was a statistically significant difference between every two hemostatic time. The pathologic examination showed the highest frequency of low-grade inflammation based on the defined pathological grading. Conclusions: The aluminum chloride method needs less time to control external hemorrhage compared to the control method (controlling external hemorrhage by simple suturing). Aluminum chloride is an effective agent in controlling external hemorrhage in an animal model. PMID:25964855

  13. A benchmark for fault tolerant flight control evaluation

    NASA Astrophysics Data System (ADS)

    Smaili, H.; Breeman, J.; Lombaerts, T.; Stroosma, O.

    2013-12-01

    A large transport aircraft simulation benchmark (REconfigurable COntrol for Vehicle Emergency Return - RECOVER) has been developed within the GARTEUR (Group for Aeronautical Research and Technology in Europe) Flight Mechanics Action Group 16 (FM-AG(16)) on Fault Tolerant Control (2004 2008) for the integrated evaluation of fault detection and identification (FDI) and reconfigurable flight control strategies. The benchmark includes a suitable set of assessment criteria and failure cases, based on reconstructed accident scenarios, to assess the potential of new adaptive control strategies to improve aircraft survivability. The application of reconstruction and modeling techniques, based on accident flight data, has resulted in high-fidelity nonlinear aircraft and fault models to evaluate new Fault Tolerant Flight Control (FTFC) concepts and their real-time performance to accommodate in-flight failures.

  14. Synthesizing aluminum particles towards controlling electrostatic discharge ignition sensitivity

    SciTech Connect

    Eric S. Collins; Jeffery P. Gesner; Michelle L. Pantoya; Michael A. Daniels

    2014-02-01

    Aluminum particles were synthesized with shell thicknesses ranging from 2.7 to 8.3 nm and a constant diameter of 95 nm. These fuel particles were combined with molybdenum trioxide particles and the electrostatic discharge (ESD) sensitivity of the mixture was measured. Results show ignition delay increased as the alumina shell thickness increased. These results correlated with electrical resistivity measurements of the mixture which increased with alumina concentration. A model was developed using COMSOL for ignition of a single Al particle. The ignition delay in the model was consistent with the experimental results suggesting that the primary ESD ignition mechanism is joule heating.

  15. Reliability of Fault Tolerant Control Systems. Part 2

    NASA Technical Reports Server (NTRS)

    Wu, N. Eva

    2000-01-01

    This paper reports Part II of a two part effort that is intended to delineate the relationship between reliability and fault tolerant control in a quantitative manner. Reliability properties peculiar to fault-tolerant control systems are emphasized, such as the presence of analytic redundancy in high proportion, the dependence of failures on control performance, and high risks associated with decisions in redundancy management due to multiple sources of uncertainties and sometimes large processing requirements. As a consequence, coverage of failures through redundancy management can be severely limited. The paper proposes to formulate the fault tolerant control problem as an optimization problem that maximizes coverage of failures through redundancy management. Coverage modeling is attempted in a way that captures its dependence on the control performance and on the diagnostic resolution. Under the proposed redundancy management policy, it is shown that an enhanced overall system reliability can be achieved with a control law of a superior robustness, with an estimator of a higher resolution, and with a control performance requirement of a lesser stringency.

  16. A Loss Tolerant Rate Controller for Reliable Multicast

    NASA Technical Reports Server (NTRS)

    Montgomery, Todd

    1997-01-01

    This paper describes the design, specification, and performance of a Loss Tolerant Rate Controller (LTRC) for use in controlling reliable multicast senders. The purpose of this rate controller is not to adapt to congestion (or loss) on a per loss report basis (such as per received negative acknowledgment), but instead to use loss report information and perceived state to decide more prudent courses of action for both the short and long term. The goal of this controller is to be responsive to congestion, but not overly reactive to spurious independent loss. Performance of the controller is verified through simulation results.

  17. Fault tolerance control for proton exchange membrane fuel cell systems

    NASA Astrophysics Data System (ADS)

    Wu, Xiaojuan; Zhou, Boyang

    2016-08-01

    Fault diagnosis and controller design are two important aspects to improve proton exchange membrane fuel cell (PEMFC) system durability. However, the two tasks are often separately performed. For example, many pressure and voltage controllers have been successfully built. However, these controllers are designed based on the normal operation of PEMFC. When PEMFC faces problems such as flooding or membrane drying, a controller with a specific design must be used. This paper proposes a unique scheme that simultaneously performs fault diagnosis and tolerance control for the PEMFC system. The proposed control strategy consists of a fault diagnosis, a reconfiguration mechanism and adjustable controllers. Using a back-propagation neural network, a model-based fault detection method is employed to detect the PEMFC current fault type (flooding, membrane drying or normal). According to the diagnosis results, the reconfiguration mechanism determines which backup controllers to be selected. Three nonlinear controllers based on feedback linearization approaches are respectively built to adjust the voltage and pressure difference in the case of normal, membrane drying and flooding conditions. The simulation results illustrate that the proposed fault tolerance control strategy can track the voltage and keep the pressure difference at desired levels in faulty conditions.

  18. Highly selective and precisely controlled aluminum etching by Ar/HBr/CH3F/O2 gas chemistry

    NASA Astrophysics Data System (ADS)

    Suzuki, Eiji; Ohtake, Hiroto; Ohsawa, Yusuke; Kumar, Kaushik; Sasaki, Masaru

    2014-01-01

    Highly selective and precisely controlled aluminum etching was investigated by using plasma with a new Ar/HBr/CH3F/O2 gas chemistry. Generally, an aluminum surface is oxidized, leading to difficulties in the precise control of nm/min-level aluminum etching with a high selectivity to SiO2 of more than 10. The new gas chemistry enabled precise aluminum etching with a high selectivity to oxide of 10 and a low etching rate of 10 nm/min. In this gas chemistry, the aluminum surface remained oxidized by oxygen during etching and the oxidized surface was reduced by CH3F. The oxidized aluminum surface was etched by radicals from CH3F and the etching rate was decreased by HBr.

  19. Development and Evaluation of Fault-Tolerant Flight Control Systems

    NASA Technical Reports Server (NTRS)

    Song, Yong D.; Gupta, Kajal (Technical Monitor)

    2004-01-01

    The research is concerned with developing a new approach to enhancing fault tolerance of flight control systems. The original motivation for fault-tolerant control comes from the need for safe operation of control elements (e.g. actuators) in the event of hardware failures in high reliability systems. One such example is modem space vehicle subjected to actuator/sensor impairments. A major task in flight control is to revise the control policy to balance impairment detectability and to achieve sufficient robustness. This involves careful selection of types and parameters of the controllers and the impairment detecting filters used. It also involves a decision, upon the identification of some failures, on whether and how a control reconfiguration should take place in order to maintain a certain system performance level. In this project new flight dynamic model under uncertain flight conditions is considered, in which the effects of both ramp and jump faults are reflected. Stabilization algorithms based on neural network and adaptive method are derived. The control algorithms are shown to be effective in dealing with uncertain dynamics due to external disturbances and unpredictable faults. The overall strategy is easy to set up and the computation involved is much less as compared with other strategies. Computer simulation software is developed. A serious of simulation studies have been conducted with varying flight conditions.

  20. Modeling the Controlled Recrystallization of Particle-Containing Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Adam, Khaled; Root, Jameson M.; Long, Zhengdong; Field, David P.

    2017-01-01

    The recrystallized fraction for AA7050 during the solution heat treatment is highly dependent upon the history of deformation during thermomechanical processing. In this work, a state variable model was developed to predict the recrystallization volume fraction as a function of processing parameters. Particle stimulated nucleation (PSN) was observed as a dominant mechanism of recrystallization in AA7050. The mesoscale Monte Carlo Potts model was used to simulate the evolved microstructure during static recrystallization with the given recrystallization fraction determined already by the state variable model for AA7050 alloy. The spatial inhomogeneity of nucleation is obtained from the measurement of the actual second-phase particle distribution in the matrix identified using backscattered electron (BSE) imaging. The state variable model showed good fit with the experimental results, and the simulated microstructures were quantitatively comparable to the experimental results for the PSN recrystallized microstructure of 7050 aluminum alloy. It was also found that the volume fraction of recrystallization did not proceed as dictated by the Avrami equation in this alloy because of the presence of the growth inhibitors.

  1. Modeling the Controlled Recrystallization of Particle-Containing Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Adam, Khaled; Root, Jameson M.; Long, Zhengdong; Field, David P.

    2016-12-01

    The recrystallized fraction for AA7050 during the solution heat treatment is highly dependent upon the history of deformation during thermomechanical processing. In this work, a state variable model was developed to predict the recrystallization volume fraction as a function of processing parameters. Particle stimulated nucleation (PSN) was observed as a dominant mechanism of recrystallization in AA7050. The mesoscale Monte Carlo Potts model was used to simulate the evolved microstructure during static recrystallization with the given recrystallization fraction determined already by the state variable model for AA7050 alloy. The spatial inhomogeneity of nucleation is obtained from the measurement of the actual second-phase particle distribution in the matrix identified using backscattered electron (BSE) imaging. The state variable model showed good fit with the experimental results, and the simulated microstructures were quantitatively comparable to the experimental results for the PSN recrystallized microstructure of 7050 aluminum alloy. It was also found that the volume fraction of recrystallization did not proceed as dictated by the Avrami equation in this alloy because of the presence of the growth inhibitors.

  2. Design and simulation of advanced fault tolerant flight control schemes

    NASA Astrophysics Data System (ADS)

    Gururajan, Srikanth

    This research effort describes the design and simulation of a distributed Neural Network (NN) based fault tolerant flight control scheme and the interface of the scheme within a simulation/visualization environment. The goal of the fault tolerant flight control scheme is to recover an aircraft from failures to its sensors or actuators. A commercially available simulation package, Aviator Visual Design Simulator (AVDS), was used for the purpose of simulation and visualization of the aircraft dynamics and the performance of the control schemes. For the purpose of the sensor failure detection, identification and accommodation (SFDIA) task, it is assumed that the pitch, roll and yaw rate gyros onboard are without physical redundancy. The task is accomplished through the use of a Main Neural Network (MNN) and a set of three De-Centralized Neural Networks (DNNs), providing analytical redundancy for the pitch, roll and yaw gyros. The purpose of the MNN is to detect a sensor failure while the purpose of the DNNs is to identify the failed sensor and then to provide failure accommodation. The actuator failure detection, identification and accommodation (AFDIA) scheme also features the MNN, for detection of actuator failures, along with three Neural Network Controllers (NNCs) for providing the compensating control surface deflections to neutralize the failure induced pitching, rolling and yawing moments. All NNs continue to train on-line, in addition to an offline trained baseline network structure, using the Extended Back-Propagation Algorithm (EBPA), with the flight data provided by the AVDS simulation package. The above mentioned adaptive flight control schemes have been traditionally implemented sequentially on a single computer. This research addresses the implementation of these fault tolerant flight control schemes on parallel and distributed computer architectures, using Berkeley Software Distribution (BSD) sockets and Message Passing Interface (MPI) for inter

  3. Autonomous Congestion Control in Delay-Tolerant Networks

    NASA Technical Reports Server (NTRS)

    Burleigh, Scott; Jennings, Esther; Schoolcraft, Joshua

    2006-01-01

    Congestion control is an important feature that directly affects network performance. Network congestion may cause loss of data or long delays. Although this problem has been studied extensively in the Internet, the solutions for Internet congestion control do not apply readily to challenged network environments such as Delay Tolerant Networks (DTN) where end-to-end connectivity may not exist continuously and latency can be high. In DTN, end-to-end rate control is not feasible. This calls for congestion control mechanisms where the decisions can be made autonomously with local information only. We use an economic pricing model and propose a rule-based congestion control mechanism where each router can autonomously decide on whether to accept a bundle (data) based on local information such as available storage and the value and risk of accepting the bundle (derived from historical statistics). Preliminary experimental results show that this congestion control mechanism can protect routers from resource depletion without loss of data.

  4. Robust and fault tolerant control of modular and reconfigurable robots

    NASA Astrophysics Data System (ADS)

    Abdul, Sajan

    Modular and reconfigurable robot has been one of the main areas of robotics research in recent years due to its wide range of applications, especially in aerospace sector. Dynamic control of manipulators can be performed using joint torque sensing with little information of the link dynamics. From the modular robot perspective, this advantage offered by the torque sensor can be taken to enhance the modularity of the control system. Known modular robots though boast novel and diverse mechanical design on joint modules in one way or another, they still require the whole robot dynamic model for motion control, and modularity offered in the mechanical side does not offer any advantage in the control design. In this work, a modular distributed control technique is formulated for modular and reconfigurable robots that can instantly adapt to robot reconfigurations. Under this control methodology, a modular and reconfigurable robot is stabilized joint by joint, and modules can be added or removed without the need of re-tuning the controller. Model uncertainties associated with load and links are compensated by the use of joint torque sensors. Other model uncertainties at each joint module are compensated by a decomposition based robust controller for each module. The proposed distributed control technique offers a 'modular' approach, featuring a unique joint-by-joint control synthesis of the joint modules. Fault tolerance and fault detection are formulated as a decentralized control problem for modular and reconfigurable robots in this thesis work. The modularity of the system is exploited to derive a strategy dependent only on a single joint module, while eliminating the need for the motion states of other joint modules. While the traditional fault tolerant and detection schemes are suitable for robots with the whole dynamic model, this proposed technique is ideal for modular and reconfigurable robots because of its modular nature. The proposed methods have been

  5. Physical analysis of the complex rye (Secale cereale L.) Alt4 aluminium (aluminum) tolerance locus using a whole-genome BAC library of rye cv. Blanco.

    PubMed

    Shi, B-J; Gustafson, J P; Button, J; Miyazaki, J; Pallotta, M; Gustafson, N; Zhou, H; Langridge, P; Collins, N C

    2009-08-01

    Rye is a diploid crop species with many outstanding qualities, and is important as a source of new traits for wheat and triticale improvement. Rye is highly tolerant of aluminum (Al) toxicity, and possesses a complex structure at the Alt4 Al tolerance locus not found at the corresponding locus in wheat. Here we describe a BAC library of rye cv. Blanco, representing a valuable resource for rye molecular genetic studies, and assess the library's suitability for investigating Al tolerance genes. The library provides 6 x genome coverage of the 8.1 Gb rye genome, has an average insert size of 131 kb, and contains only ~2% of empty or organelle-derived clones. Genetic analysis attributed the Al tolerance of Blanco to the Alt4 locus on the short arm of chromosome 7R, and revealed the presence of multiple allelic variants (haplotypes) of the Alt4 locus in the BAC library. BAC clones containing ALMT1 gene clusters from several Alt4 haplotypes were identified, and will provide useful starting points for exploring the basis for the structural variability and functional specialization of ALMT1 genes at this locus.

  6. Analysis of GPS Abnormal Conditions within Fault Tolerant Control Laws

    NASA Astrophysics Data System (ADS)

    Al-Sinbol, Gahssan

    The Global Position System (GPS) is a critical element for the functionality of autonomous flying vehicles. The GPS operation at normal and abnormal conditions directly impacts the trajectory tracking performance of the autonomous Unmanned Aerial Vehicles (UAVs) controllers. The effects of GPS parameter variation must be well understood and user-friendly computational tools must be developed to facilitate the design and evaluation of fault tolerant control laws. This thesis presents the development of a simplified GPS error model in Matlab/Simulink and its use performing a sensitivity analysis of GPS parameters effect under system normal and abnormal operation on different UAV trajectory tracking controllers. The model statistically generates position and velocity errors, simulates the effect of GPS satellite configuration on the position and velocity measurement accuracy, and implements a set of failures to the GPS readings. The model and its graphical user interface was integrated within the WVU UAV simulation environment as a masked Simulink block. The effects on the controllers' trajectory tracking performance of the following GPS parameters were investigated within normal operation ranges and outside: time delay, update rate, error standard deviation, bias, and major position and velocity failures. Several sets of control laws with fixed and adaptive parameters and of different levels of complexity have been used in this investigation. A complex performance index formulated in terms of tracking errors and control activity was used for control laws performance evaluation. The composition of various metrics within the performance index was performed using fixed and variable weights depending on the local characteristics of the commanded trajectory. This study has revealed that GPS error parameters have a significant impact on control laws performance. The proposed GPS model has proved to be a valuable, flexible tool for testing and evaluation of the fault

  7. Gain-Scheduled Fault Tolerance Control Under False Identification

    NASA Technical Reports Server (NTRS)

    Shin, Jong-Yeob; Belcastro, Christine (Technical Monitor)

    2006-01-01

    An active fault tolerant control (FTC) law is generally sensitive to false identification since the control gain is reconfigured for fault occurrence. In the conventional FTC law design procedure, dynamic variations due to false identification are not considered. In this paper, an FTC synthesis method is developed in order to consider possible variations of closed-loop dynamics under false identification into the control design procedure. An active FTC synthesis problem is formulated into an LMI optimization problem to minimize the upper bound of the induced-L2 norm which can represent the worst-case performance degradation due to false identification. The developed synthesis method is applied for control of the longitudinal motions of FASER (Free-flying Airplane for Subscale Experimental Research). The designed FTC law of the airplane is simulated for pitch angle command tracking under a false identification case.

  8. Cascade structures of fault-tolerant control schemes with the static and dynamic output controllers

    NASA Astrophysics Data System (ADS)

    Krokavec, Dušan; Filasová, Anna

    2017-01-01

    An enhanced approach to fault-tolerant control design is proposed in the paper for linear systems subject to cascade control strategy, while static and dynamic output controllers are employed to maintain the stability of the overall interconnected control structure. The controller gains are solved simultaneously using two-step linear matrix inequality formulation, conditioned by linear matrix equalities. A simulation example, subject to a system matrix parameter fault, demonstrates the effiectiveness of the proposed method of design and cascade control technique.

  9. Aluminum doping improves silicon solar cells

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Aluminum doped silicon solar cells with resistivities in the 10- to 20-ohm centimeter range have broad spectral response, high efficiency and long lifetimes in nuclear radiation environments. Production advantages include low material rejection and increased production yields, and close tolerance control.

  10. Parameter Transient Behavior Analysis on Fault Tolerant Control System

    NASA Technical Reports Server (NTRS)

    Belcastro, Christine (Technical Monitor); Shin, Jong-Yeob

    2003-01-01

    In a fault tolerant control (FTC) system, a parameter varying FTC law is reconfigured based on fault parameters estimated by fault detection and isolation (FDI) modules. FDI modules require some time to detect fault occurrences in aero-vehicle dynamics. This paper illustrates analysis of a FTC system based on estimated fault parameter transient behavior which may include false fault detections during a short time interval. Using Lyapunov function analysis, the upper bound of an induced-L2 norm of the FTC system performance is calculated as a function of a fault detection time and the exponential decay rate of the Lyapunov function.

  11. Effects of aluminum and manganese on the growth of ectomycorrhizal fungi

    SciTech Connect

    Thompson, G.W.; Medve, R.J.

    1984-09-01

    Cenococcum graniforme, Suillus luteus, Thelephora terrestris, and three isolates of Pisolithus tinctorius were cultured on modified Melin-Norkrans medium at pH 3.4 and adjusted to 0 to 500 ppm (0 to 500 ..mu..g/ml) of aluminum or manganese sulfate. Except for T. terrestris, which was intolerant of aluminum at 150 and 250 to 500 ppm, and P. tinctorius isolate 250, which was intolerant of aluminum at 450 ppm, all fungi showed some growth at all concentrations of aluminum. S. luteus was the most tolerant to aluminum. Manganese was less fungitoxic than aluminum, with all fungi showing at least 65% growth at 500 ppm as compared with the control. C graniforme was not inhibited at any concentration of manganese, and S. luteus was only affected at 500 ppm. P. tinctorius isolate 230 showed no significant variation in growth when subjected to various concentrations of three forms of manganese salts. Significant differences in growth were detected in response to three aluminum salts, but no detectable pattern was apparent. Genotypic responses to aluminum and manganese were evident for P. tinctorius. Isolates 210 and 230 were more tolerant to manganese than was isolate 250. Aluminum tolerance was in the order of isolate 230 > 210 > 250. Results of in vitro studies concerning tolerance responses of ectomycorrhizal fungi to aluminum and manganese were not consistent with field observations of the successional sequence of these fungi on acid coal spoils. 43 references, 3 tables.

  12. SIFT - Design and analysis of a fault-tolerant computer for aircraft control. [Software Implemented Fault Tolerant systems

    NASA Technical Reports Server (NTRS)

    Wensley, J. H.; Lamport, L.; Goldberg, J.; Green, M. W.; Levitt, K. N.; Melliar-Smith, P. M.; Shostak, R. E.; Weinstock, C. B.

    1978-01-01

    SIFT (Software Implemented Fault Tolerance) is an ultrareliable computer for critical aircraft control applications that achieves fault tolerance by the replication of tasks among processing units. The main processing units are off-the-shelf minicomputers, with standard microcomputers serving as the interface to the I/O system. Fault isolation is achieved by using a specially designed redundant bus system to interconnect the processing units. Error detection and analysis and system reconfiguration are performed by software. Iterative tasks are redundantly executed, and the results of each iteration are voted upon before being used. Thus, any single failure in a processing unit or bus can be tolerated with triplication of tasks, and subsequent failures can be tolerated after reconfiguration. Independent execution by separate processors means that the processors need only be loosely synchronized, and a novel fault-tolerant synchronization method is described.

  13. Effects of advanced oxidation pretreatment on residual aluminum control in high humic acid water purification.

    PubMed

    Wang, Wendong; Li, Hua; Ding, Zhenzhen; Wang, Xiaochang

    2011-01-01

    Due to the formation of disinfection by-products and high concentrations of Al residue in drinking water purification, humic substances are a major component of organic matter in natural waters and have therefore received a great deal of attention in recent years. We investigated the effects of advanced oxidation pretreatment methods usually applied for removing dissolved organic matters on residual Al control. Results showed that the presence of humic acid increased residual Al concentration notably. With 15 mg/L of humic acid in raw water, the concentrations of soluble aluminum and total aluminum in the treated water were close to the quantity of Al addition. After increasing coagulant dosage from 12 to 120 mg/L, the total-Al in the treated water was controlled to below 0.2 mg/L. Purification systems with ozonation, chlorination, or potassium permanganate oxidation pretreatment units had little effects on residual Al control; while UV radiation decreased Al concentration notably. Combined with ozonation, the effects of UV radiation were enhanced. Optimal dosages were 0.5 mg O3/mg C and 3 hr for raw water with 15 mg/L of humic acid. Under UV light radiation, the combined forces or bonds that existed among humic acid molecules were destroyed; adsorption sites increased positively with radiation time, which promoted adsorption of humic acid onto polymeric aluminum and Al(OH)3(s). This work provides a new solution for humic acid coagulation and residual Al control for raw water with humic acid purification.

  14. Water deficit and aluminum interactive effects on generation of reactive oxygen species and responses of antioxidative enzymes in the seedlings of two rice cultivars differing in stress tolerance.

    PubMed

    Pandey, Poonam; Srivastava, Rajneesh Kumar; Rajpoot, Ritika; Rani, Anjana; Pandey, Akhilesh Kumar; Dubey, R S

    2016-01-01

    Aluminum (Al) is a major constraint to crop productivity in acid soils, whereas water deficit severely limits crop production in arid and semi-arid regions of the world. The objective of the present study was to examine the effects of both stresses, Al excess and water deficit, individually and in combination on the production of the reactive oxygen species (ROS) superoxide anion (O2˙(-)), hydrogen peroxide (H2O2), hydroxyl radical, and lipid peroxidation and the activity of antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and guaiacol peroxidase (GPX) in the seedlings of two rice (Oryza sativa L.) cvs. Malviya-36 (sensitive to water deficit and Al) and Vandana (tolerant to water deficit and Al). When 15-day grown seedlings were exposed to water deficit (created with 15% polyethylene glycol, PEG-6000) or Al (1 mM AlCl3) treatment or both treatments together for 24-72 h, the lengths and fresh weights of root/shoot declined in the seedlings of the sensitive cultivar, whereas in the tolerant seedlings, either little or insignificant decline in these parameters was observed due to the treatments. Biochemical determinations and histochemical studies revealed that under a similar level of water deficit, Al, or combined treatment, seedlings of sensitive cultivar showed a higher level of production of O2˙(-), H2O2, hydroxyl radical, and lipid peroxides compared to the tolerant seedlings. Seedlings of tolerant cultivars, both in roots and shoots, had constitutively higher activity levels of antioxidative enzymes SOD, CAT, and GPX and showed a greater increase in activity under water deficit or Al treatment alone or in combination compared to the similarly treated seedlings of sensitive cultivar. Our results suggest that a lower constitutive level of ROS and a high antioxidative enzyme capacity are associated with tolerance to both water deficit and Al excess in rice seedlings.

  15. Optimal control of an aluminum casting furnace: Part II. Fuel optimization

    NASA Astrophysics Data System (ADS)

    Bui, R. T.; Ouellet, R.

    1990-06-01

    In this second of a two-article series, the simplified model of the aluminum casting furnace presented in Part I is used to solve a fuel-optimal control problem. Basically a Lagrange problem with equality and inequality constraints, it is formulated through variational calculus into a two-point boundary-value problem with known initial and final conditions and specified final time. It yields an optimal solution with a time-vary ing fuel flow rate that gives 10.9 pct fuel economy over the conventional nonoptimal constant fuel flow rate. This shows that variational calculus can be used to solve optimal control problems for the aluminum casting furnace and for other similar thermal systems commonly encountered in the metallurgical industry.

  16. Engineering an Effective Immune Adjuvant by Designed Control of Shape and Crystallinity of Aluminum Oxyhydroxide Nanoparticles

    PubMed Central

    Sun, Bingbing; Ji, Zhaoxia; Liao, Yu-Pei; Wang, Meiying; Wang, Xiang; Dong, Juyao; Chang, Chong Hyun; Li, Ruibin; Zhang, Haiyuan; Nel, André E.; Xia, Tian

    2014-01-01

    Adjuvants based on aluminum salts (Alum) are commonly used in vaccines to boost the immune response against infectious agents. However, the detailed mechanism of how Alum enhances adaptive immunity and exerts its adjuvant immune effect remains unclear. Other than being comprised of micron-sized aggregates that include nanoscale particulates, Alum lacks specific physicochemical properties to explain activation of the innate immune system, including the mechanism by which aluminum-based adjuvants engage the NLRP3 inflammasome and IL-1β production. This is putatively one of the major mechanisms required for an adjuvant effect. Because we know that long aspect ratio nanomaterials trigger the NLRP3 inflammasome, we synthesized a library of aluminum oxyhydroxide (AlOOH) nanorods to determine whether control of the material shape and crystalline properties could be used to quantitatively assess NLRP3 inflammasome activation and linkage of the cellular response to the material’s adjuvant activities in vivo. Using comparison to commercial Alum, we demonstrate that the crystallinity and surface hydroxyl group display of AlOOH nanoparticles quantitatively impact the activation of the NLRP3 inflammasome in human THP-1 myeloid cells or murine bone marrow-derived dendritic cells (BMDCs). Moreover, these in vitro effects were correlated with the immunopotentiation capabilities of the AlOOH nanorods in a murine OVA immunization model. These results demonstrate that shape, crystallinity and hydroxyl content play an important role in NLRP3 inflammasome activation and are therefore useful for quantitative boosting of antigen-specific immune responses. These results show that the engineered design of aluminum-based adjuvants in combination with dendritic cell property-activity analysis can be used to design more potent aluminum-based adjuvants. PMID:24261790

  17. Corrosion control of cement-matrix and aluminum-matrix composites

    NASA Astrophysics Data System (ADS)

    Hou, Jiangyuan

    Corrosion control of composite materials, particularly aluminum-matrix and cement-matrix composites, was addressed by surface treatment, composite formulation and cathodic protection. Surface treatment methods studied include anodization in the case of aluminum-matrix composites and oxidation treatment (using water) in the case of steel rebar for reinforcing concrete. The effects of reinforcement species (aluminum nitride (AIN) versus silicon carbide (SiC) particles) in the aluminum-matrix composites and of admixtures (carbon fibers, silica fume, latex and methylcellulose) in concrete on the corrosion resistance of composites were addressed. Moreover, the effect of admixtures in concrete and of admixtures in mortar overlay (as anode on concrete) on the efficiency of cathodic protection of steel reinforced concrete was studied. For SiC particle filled aluminum, anodization was performed successfully in an acid electrolyte, as for most aluminum alloys. However, for AlN particle filled aluminum, anodization needs to be performed in an alkaline (0.7 N NaOH) electrolyte instead. The concentration of NaOH in the electrolyte was critical. It was found that both silica fume and latex improved the corrosion resistance of rebar in concrete in both Ca(OH)sb2 and NaCl solutions, mainly because these admixtures decreased the water absorptivity. Silica fume was more effective than latex. Methylcellulose improved the corrosion resistance of rebar in concrete a little in Ca(OH)sb2 solution. Carbon fibers decreased the corrosion resistance of rebar in concrete, but this effect could be made up for by either silica fume or latex, such that silica fume was more effective than latex. Surface treatment in the form of water immersion for two days was found to improve the corrosion resistance of rebar in concrete. This treatment resulted in a thin uniform layer of black iron oxide (containing Fesp{2+}) on the entire rebar surface except on the cross-sectional surface. Prior to the

  18. 40 CFR 180.1091 - Aluminum isopropoxide and aluminum secondary butoxide; exemption from the requirement of a...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 25 2013-07-01 2013-07-01 false Aluminum isopropoxide and aluminum... PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1091 Aluminum isopropoxide and aluminum secondary butoxide; exemption from the requirement of a tolerance. Aluminum isopropoxide (CAS Reg. No....

  19. 40 CFR 180.1091 - Aluminum isopropoxide and aluminum secondary butoxide; exemption from the requirement of a...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Aluminum isopropoxide and aluminum... PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1091 Aluminum isopropoxide and aluminum secondary butoxide; exemption from the requirement of a tolerance. Aluminum isopropoxide (CAS Reg. No....

  20. 40 CFR 180.1091 - Aluminum isopropoxide and aluminum secondary butoxide; exemption from the requirement of a...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Aluminum isopropoxide and aluminum... PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1091 Aluminum isopropoxide and aluminum secondary butoxide; exemption from the requirement of a tolerance. Aluminum isopropoxide (CAS Reg. No....

  1. 40 CFR 180.1091 - Aluminum isopropoxide and aluminum secondary butoxide; exemption from the requirement of a...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Aluminum isopropoxide and aluminum... PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1091 Aluminum isopropoxide and aluminum secondary butoxide; exemption from the requirement of a tolerance. Aluminum isopropoxide (CAS Reg. No....

  2. 40 CFR 180.1091 - Aluminum isopropoxide and aluminum secondary butoxide; exemption from the requirement of a...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Aluminum isopropoxide and aluminum... PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1091 Aluminum isopropoxide and aluminum secondary butoxide; exemption from the requirement of a tolerance. Aluminum isopropoxide (CAS Reg. No....

  3. Identification of a Cis-Acting Element of ART1, a C2H2-Type Zinc-Finger Transcription Factor for Aluminum Tolerance in Rice1[OA

    PubMed Central

    Tsutsui, Tomokazu; Yamaji, Naoki; Feng Ma, Jian

    2011-01-01

    Rice (Oryza sativa) is one of the most aluminum (Al)-tolerant species among small-grain cereals. Recent identification of a transcription factor AL RESISTANCE TRANSCRIPTION FACTOR1 (ART1) revealed that this high Al tolerance in rice is achieved by multiple genes involved in detoxification of Al at different cellular levels. ART1 is a C2H2-type zinc-finger transcription factor and regulates the expression of 31 genes in the downstream. In this study, we attempted to identify a cis-acting element of ART1. We used the promoter region of SENSITIVE TO AL RHIZOTOXICITY1, an Al tolerance gene in the downstream of ART1. With the help of gel-shift assay, we were able to identify the cis-acting element as GGN(T/g/a/C)V(C/A/g)S(C/G). This element was found in the promoter region of 29 genes among 31 ART1-regulated genes. To confirm this cis-acting element in vivo, we transiently introduced this element one or five times tandemly repeated sequence with 35S minimal promoter and green fluorescent protein reporter together with or without ART1 gene in the tobacco (Nicotiana tabacum) mesophyll protoplasts. The results showed that the expression of green fluorescent protein reporter responded to ART1 expression. Furthermore, the expression increased with repetition of the cis-acting element. Our results indicate that the five nucleotides identified are the target DNA-binding sequence of ART1. PMID:21502187

  4. Elevation of arginine decarboxylase-dependent putrescine production enhances aluminum tolerance by decreasing aluminum retention in root cell walls of wheat.

    PubMed

    Yu, Yan; Jin, Chongwei; Sun, Chengliang; Wang, Jinghong; Ye, Yiquan; Lu, Lingli; Lin, Xianyong

    2015-12-15

    Aluminum (Al) stress induces putrescine (Put) accumulation in several plants and this response is proposed to alleviate Al toxicity. However, the mechanisms underlying this alleviation remain largely unknown. Here, we show that exposure to Al clearly increases Put accumulation in the roots of wheat plants (Triticum aestivum L. 'Xi Aimai-1') and that this was accompanied by significant increase in the activity of arginine decarboxylase (ADC), a Put producing enzyme. Application of an ADC inhibitor (d-arginine) terminated the Al-induced Put accumulation, indicating that increased ADC activity may be responsible for the increase in Put accumulation in response to Al. The d-arginine treatment also increased the Al-induced accumulation of cell wall polysaccharides and the degree of pectin demethylation in wheat roots. Thus, it elevated Al retention in cell walls and exacerbated Al accumulation in roots, both of which aggravate Al toxicity in wheat plants. The opposite effects were true for exogenous Put application. These results suggest that ADC-dependent Put accumulation plays important roles in providing protection against Al toxicity in wheat plants through decreasing cell wall polysaccharides and increasing the degree of pectin methylation, thus decreasing Al retention in the cell walls.

  5. Sensor Fault and Delay Tolerant Control for Networked Control Systems Subject to External Disturbances.

    PubMed

    Han, Shi-Yuan; Chen, Yue-Hui; Tang, Gong-You

    2017-03-28

    In this paper, the problem of sensor fault and delay tolerant control problem for a class of networked control systems under external disturbances is investigated. More precisely, the dynamic characteristics of the external disturbance and sensor fault are described as the output of exogenous systems first. The original sensor fault and delay tolerant control problem is reformulated as an equivalence problem with designed available system output and reformed performance index. The feedforward and feedback sensor fault tolerant controller (FFSFTC) can be obtained by utilizing the solutions of Riccati matrix equation and Stein matrix equation. Based on the designed fault diagnoser, the proposed FFSFTC is further reconstructed to compensate for the sensor fault and delayed measurement effects. Finally, numerical examples are provided to illustrate the effectiveness of our proposed FFSFTC with different cases with various types of sensor faults, measurement delays and external disturbances.

  6. Characterization of an inducible C2 H2 -type zinc finger transcription factor VuSTOP1 in rice bean (Vigna umbellata) reveals differential regulation between low pH and aluminum tolerance mechanisms.

    PubMed

    Fan, Wei; Lou, He Qiang; Gong, Yu Long; Liu, Mei Ya; Cao, Meng Jie; Liu, Yu; Yang, Jian Li; Zheng, Shao Jian

    2015-10-01

    The rice bean (Vigna umbellata) root apex specifically secretes citrate through expression activation of Vigna umbellata Multidrug and Toxic Compound Extrusion 1 (VuMATE1) under aluminum (Al(3+) ) stress. However, the underlying mechanisms regulating VuMATE1 expression remain unknown. We isolated and characterized a gene encoding Sensitive to Proton Rhizotoxicity1 (STOP1)-like protein, VuSTOP1, from rice bean. The role of VuSTOP1 in regulating VuMATE1 expression was investigated using the yeast one-hybrid assay. We characterized the function of VuSTOP1 in Al(3)  (+)  - and H(+) -tolerance using in planta complementation assays. We demonstrated that VuSTOP1 has transactivation potential. We found that VuSTOP1 expression is inducible by Al(3+) and H(+) stress. However, although VuSTOP1 binds to the promoter of VuMATE1, the inconsistent tissue localization patterns of VuSTOP1 and VuMATE1 preclude VuSTOP1 as the major factor regulating VuMATE1 expression. In addition, when a protein translation inhibitor increased expression of VuSTOP1, VuMATE1 expression was inhibited. In planta complementation assay demonstrated that VuSTOP1 could fully restore expression of genes involved in H(+) tolerance, but could only partially restore expression of AtMATE. We conclude that VuSTOP1 plays a major role in H(+) tolerance, but only a minor role in Al(3+) tolerance. The differential transcriptional regulation of VuSTOP1 and VuMATE1 reveals a complex regulatory system controlling VuMATE1 expression.

  7. Fault tolerant vector control of induction motor drive

    NASA Astrophysics Data System (ADS)

    Odnokopylov, G.; Bragin, A.

    2014-10-01

    For electric composed of technical objects hazardous industries, such as nuclear, military, chemical, etc. an urgent task is to increase their resiliency and survivability. The construction principle of vector control system fault-tolerant asynchronous electric. Displaying recovery efficiency three-phase induction motor drive in emergency mode using two-phase vector control system. The process of formation of a simulation model of the asynchronous electric unbalance in emergency mode. When modeling used coordinate transformation, providing emergency operation electric unbalance work. The results of modeling transient phase loss motor stator. During a power failure phase induction motor cannot save circular rotating field in the air gap of the motor and ensure the restoration of its efficiency at rated torque and speed.

  8. Different effects of aluminum on the actin cytoskeleton and brefeldin A-sensitive vesicle recycling in root apex cells of two maize varieties differing in root elongation rate and aluminum tolerance.

    PubMed

    Amenós, Montse; Corrales, Isabel; Poschenrieder, Charlotte; Illés, Peter; Baluska, Frantisek; Barceló, Juan

    2009-03-01

    A relationship between aluminum (Al) toxicity, endocytosis, endosomes and vesicle recycling in the root transition zone has recently been demonstrated. Here the importance of filamentous actin (F-actin)-based vesicle trafficking for Al tolerance has been investigating in maize varieties differing in their Al sensitivities. More Al was internalized into root tip cells of the Al-sensitive variety 16x36 than in the Al-tolerant variety Cateto. The actin cytoskeleton and vesicle trafficking were primary targets for Al toxicity in the root tips of the sensitive variety. Visualization of boron-cross-linked rhamnogalacturonan II (RGII)-containing brefeldin A (BFA) compartments revealed that Al inhibited the formation of these compartments, especially in variety 16x36. The time sequence of Al effects on pectin recycling matches the growth effects of Al in this sensitive variety. These results support the hypothesis that Al binding to pectin-rich cell walls can contribute to reversible inhibition of root elongation. Al-induced alterations on F-actin were most evident in the central part of the transition zone of Al-sensitive 16x36, where Al was localized inside the nucleoli. In relation to this observation, a role for symplastic Al in both irreversible growth inhibition and amelioration of BFA-induced inhibition of root elongation is discussed.

  9. Plant tolerance: A unique approach to control hemipteran pests

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plant tolerance to insect pests has been indicated to be a unique category of resistance, however, very little information is available on the mechanism of tolerance against insect pests. Tolerance is distinctive in terms of the plant’s ability to withstand or recover from herbivore injury through g...

  10. Application of superplastically formed and diffusion bonded aluminum to a laminar flow control leading edge

    NASA Technical Reports Server (NTRS)

    Goodyear, M. D.

    1987-01-01

    NASA sponsored the Aircraft Energy Efficiency (ACEE) program in 1976 to develop technologies to improve fuel efficiency. Laminar flow control was one such technology. Two approaches for achieving laminar flow were designed and manufactured under NASA sponsored programs: the perforated skin concept used at McDonnell Douglas and the slotted design used at Lockheed-Georgia. Both achieved laminar flow, with the slotted design to a lesser degree (JetStar flight test program). The latter design had several fabrication problems concerning springback and adhesive flow clogging the air flow passages. The Lockheed-Georgia Company accomplishments is documented in designing and fabricating a small section of a leading edge article addressing a simpler fabrication method to overcome the previous program's manufacturing problems, i.e., design and fabrication using advanced technologies such as diffusion bonding of aluminum, which has not been used on aerospace structures to date, and the superplastic forming of aluminum.

  11. Controlling silicon crystallization in aluminum-induced crystallization via substrate plasma treatment

    NASA Astrophysics Data System (ADS)

    Hainey, Mel F.; Innocent-Dolor, Jon-L.; Choudhury, Tanushree H.; Redwing, Joan M.

    2017-03-01

    The effect of reactive ion etching using chlorine or fluorine-based plasmas on aluminum-induced crystallization (AIC) of silicon on fused silica glass substrates was investigated with the goal of chemically modifying the substrate surface and thereby influencing the crystallization behavior. Chlorine etching of the glass prior to AIC resulted in six times faster silicon crystallization times and smaller grain sizes than films formed on untreated substrates while fluorine etching resulted in crystallization times double than those on untreated surfaces. The differences in crystallization behavior were attributed to changes in surface chemistry and surface energy of the glass as a result of the plasma treatment as supported by X-ray photoelectron spectroscopy and contact angle measurements. The different surface treatments were then combined with optical lithography to control the location of crystallization on the substrate surface to realize the production of patterned polycrystalline silicon films from initially continuous aluminum and silicon.

  12. Fabrication of sub-15 nm aluminum wires by controlled etching

    SciTech Connect

    Morgan-Wall, T.; Hughes, H. J.; Hartman, N.; Marković, N.; McQueen, T. M.

    2014-04-28

    We describe a method for the fabrication of uniform aluminum nanowires with diameters below 15 nm. Electron beam lithography is used to define narrow wires, which are then etched using a sodium bicarbonate solution, while their resistance is simultaneously measured in-situ. The etching process can be stopped when the desired resistance is reached, and can be restarted at a later time. The resulting nanowires show a superconducting transition as a function of temperature and magnetic field that is consistent with their smaller diameter. The width of the transition is similar to that of the lithographically defined wires, indicating that the etching process is uniform and that the wires are undamaged. This technique allows for precise control over the normal state resistance and can be used to create a variety of aluminum nanodevices.

  13. Parameter Estimation Analysis for Hybrid Adaptive Fault Tolerant Control

    NASA Astrophysics Data System (ADS)

    Eshak, Peter B.

    Research efforts have increased in recent years toward the development of intelligent fault tolerant control laws, which are capable of helping the pilot to safely maintain aircraft control at post failure conditions. Researchers at West Virginia University (WVU) have been actively involved in the development of fault tolerant adaptive control laws in all three major categories: direct, indirect, and hybrid. The first implemented design to provide adaptation was a direct adaptive controller, which used artificial neural networks to generate augmentation commands in order to reduce the modeling error. Indirect adaptive laws were implemented in another controller, which utilized online PID to estimate and update the controller parameter. Finally, a new controller design was introduced, which integrated both direct and indirect control laws. This controller is known as hybrid adaptive controller. This last control design outperformed the two earlier designs in terms of less NNs effort and better tracking quality. The performance of online PID has an important role in the quality of the hybrid controller; therefore, the quality of the estimation will be of a great importance. Unfortunately, PID is not perfect and the online estimation process has some inherited issues; the online PID estimates are primarily affected by delays and biases. In order to ensure updating reliable estimates to the controller, the estimator consumes some time to converge. Moreover, the estimator will often converge to a biased value. This thesis conducts a sensitivity analysis for the estimation issues, delay and bias, and their effect on the tracking quality. In addition, the performance of the hybrid controller as compared to direct adaptive controller is explored. In order to serve this purpose, a simulation environment in MATLAB/SIMULINK has been created. The simulation environment is customized to provide the user with the flexibility to add different combinations of biases and delays to

  14. Fault tolerant control of multivariable processes using auto-tuning PID controller.

    PubMed

    Yu, Ding-Li; Chang, T K; Yu, Ding-Wen

    2005-02-01

    Fault tolerant control of dynamic processes is investigated in this paper using an auto-tuning PID controller. A fault tolerant control scheme is proposed composing an auto-tuning PID controller based on an adaptive neural network model. The model is trained online using the extended Kalman filter (EKF) algorithm to learn system post-fault dynamics. Based on this model, the PID controller adjusts its parameters to compensate the effects of the faults, so that the control performance is recovered from degradation. The auto-tuning algorithm for the PID controller is derived with the Lyapunov method and therefore, the model predicted tracking error is guaranteed to converge asymptotically. The method is applied to a simulated two-input two-output continuous stirred tank reactor (CSTR) with various faults, which demonstrate the applicability of the developed scheme to industrial processes.

  15. A fault-tolerant control architecture for unmanned aerial vehicles

    NASA Astrophysics Data System (ADS)

    Drozeski, Graham R.

    Research has presented several approaches to achieve varying degrees of fault-tolerance in unmanned aircraft. Approaches in reconfigurable flight control are generally divided into two categories: those which incorporate multiple non-adaptive controllers and switch between them based on the output of a fault detection and identification element, and those that employ a single adaptive controller capable of compensating for a variety of fault modes. Regardless of the approach for reconfigurable flight control, certain fault modes dictate system restructuring in order to prevent a catastrophic failure. System restructuring enables active control of actuation not employed by the nominal system to recover controllability of the aircraft. After system restructuring, continued operation requires the generation of flight paths that adhere to an altered flight envelope. The control architecture developed in this research employs a multi-tiered hierarchy to allow unmanned aircraft to generate and track safe flight paths despite the occurrence of potentially catastrophic faults. The hierarchical architecture increases the level of autonomy of the system by integrating five functionalities with the baseline system: fault detection and identification, active system restructuring, reconfigurable flight control; reconfigurable path planning, and mission adaptation. Fault detection and identification algorithms continually monitor aircraft performance and issue fault declarations. When the severity of a fault exceeds the capability of the baseline flight controller, active system restructuring expands the controllability of the aircraft using unconventional control strategies not exploited by the baseline controller. Each of the reconfigurable flight controllers and the baseline controller employ a proven adaptive neural network control strategy. A reconfigurable path planner employs an adaptive model of the vehicle to re-shape the desired flight path. Generation of the revised

  16. Fault tolerance control of phase current in permanent magnet synchronous motor control system

    NASA Astrophysics Data System (ADS)

    Chen, Kele; Chen, Ke; Chen, Xinglong; Li, Jinying

    2014-08-01

    As the Photoelectric tracking system develops from earth based platform to all kinds of moving platform such as plane based, ship based, car based, satellite based and missile based, the fault tolerance control system of phase current sensor is studied in order to detect and control of failure of phase current sensor on a moving platform. By using a DC-link current sensor and the switching state of the corresponding SVPWM inverter, the failure detection and fault control of three phase current sensor is achieved. Under such conditions as one failure, two failures and three failures, fault tolerance is able to be controlled. The reason why under the method, there exists error between fault tolerance control and actual phase current, is analyzed, and solution to weaken the error is provided. The experiment based on permanent magnet synchronous motor system is conducted, and the method is proven to be capable of detecting the failure of phase current sensor effectively and precisely, and controlling the fault tolerance simultaneously. With this method, even though all the three phase current sensors malfunction, the moving platform can still work by reconstructing the phase current of the motor.

  17. Fault-tolerant control of heavy-haul trains

    NASA Astrophysics Data System (ADS)

    Zhuan, Xiangtao; Xia, Xiaohua

    2010-06-01

    The fault-tolerant control (FTC) of heavy-haul trains is discussed on the basis of the speed regulation proposed in previous works. The fault modes of trains are assumed and the corresponding fault detection and isolation (FDI) are studied. The FDI of sensor faults is based on a geometric approach for residual generators. The FDI of a braking system is based on the observation of the steady-state speed. From the difference of the steady-state speeds between the fault system and the faultless system, one can get fault information. Simulation tests were conducted on the suitability of the FDIs and the redesigned speed regulators. It is shown that the proposed FTC does not explicitly worsen the performance of the speed regulator in the case of a faultless system, while it obviously improves the performance of the speed regulator in the case of a faulty system.

  18. Network Monitor and Control of Disruption-Tolerant Networks

    NASA Technical Reports Server (NTRS)

    Torgerson, J. Leigh

    2014-01-01

    For nearly a decade, NASA and many researchers in the international community have been developing Internet-like protocols that allow for automated network operations in networks where the individual links between nodes are only sporadically connected. A family of Disruption-Tolerant Networking (DTN) protocols has been developed, and many are reaching CCSDS Blue Book status. A NASA version of DTN known as the Interplanetary Overlay Network (ION) has been flight-tested on the EPOXI spacecraft and ION is currently being tested on the International Space Station. Experience has shown that in order for a DTN service-provider to set up a large scale multi-node network, a number of network monitor and control technologies need to be fielded as well as the basic DTN protocols. The NASA DTN program is developing a standardized means of querying a DTN node to ascertain its operational status, known as the DTN Management Protocol (DTNMP), and the program has developed some prototypes of DTNMP software. While DTNMP is a necessary component, it is not sufficient to accomplish Network Monitor and Control of a DTN network. JPL is developing a suite of tools that provide for network visualization, performance monitoring and ION node control software. This suite of network monitor and control tools complements the GSFC and APL-developed DTN MP software, and the combined package can form the basis for flight operations using DTN.

  19. Control of Crystal Orientation and Diameter of Silicon Nanowire Using Anodic Aluminum Oxide Template

    NASA Astrophysics Data System (ADS)

    Shimizu, Tomohiro; Inoue, Fumihiro; Wang, Chonge; Otsuka, Shintaro; Tada, Yoshihiro; Koto, Makoto; Shingubara, Shoso

    2013-06-01

    The control of the crystal orientation and diameter of vertically grown epitaxial Si nanowires was demonstrated using a combination of a vapor-liquid-solid (VLS) growth technique and the use of an anodic aluminum oxide (AAO) template on a single-crystal Si substrate. The [100], [110], and [111] nanowires were selectively obtained by choosing the Si substrate with appropriate crystal orientation. The diameter of a Si nanowire in the AAO template could be controlled by the modification of the pore size of the AAO template with anodic voltage during anodization.

  20. Novel neural networks-based fault tolerant control scheme with fault alarm.

    PubMed

    Shen, Qikun; Jiang, Bin; Shi, Peng; Lim, Cheng-Chew

    2014-11-01

    In this paper, the problem of adaptive active fault-tolerant control for a class of nonlinear systems with unknown actuator fault is investigated. The actuator fault is assumed to have no traditional affine appearance of the system state variables and control input. The useful property of the basis function of the radial basis function neural network (NN), which will be used in the design of the fault tolerant controller, is explored. Based on the analysis of the design of normal and passive fault tolerant controllers, by using the implicit function theorem, a novel NN-based active fault-tolerant control scheme with fault alarm is proposed. Comparing with results in the literature, the fault-tolerant control scheme can minimize the time delay between fault occurrence and accommodation that is called the time delay due to fault diagnosis, and reduce the adverse effect on system performance. In addition, the FTC scheme has the advantages of a passive fault-tolerant control scheme as well as the traditional active fault-tolerant control scheme's properties. Furthermore, the fault-tolerant control scheme requires no additional fault detection and isolation model which is necessary in the traditional active fault-tolerant control scheme. Finally, simulation results are presented to demonstrate the efficiency of the developed techniques.

  1. Control of back surface reflectance from aluminum alloyed contacts on silicon solar cells

    SciTech Connect

    Cudzinovic, M.; Sopori, B.

    1996-05-01

    A process for forming highly reflective aluminum back contacts with low contact resistance to silicon solar cells is described. By controlling the process conditions, it is possible to vary the silicon/aluminum interface from a specular to a diffuse reflector while maintaining a high interface reflectance. The specular interface is found to be a uniform silicon/aluminum alloy layer a few angstroms thick that has epitaxially regrown on the silicon. The diffuse interface consists of randomly distributed (111) pyramids produced by crystallographic out-diffusion of the bulk silicon. The light trapping ability of the diffuse contact is found to be close to the theoretical limit. Both types of contacts are found to have specific contact resistivities of 10{sup {minus}5} {Omega}-cm{sup 2}. The process for forming the contacts involves illuminating the devices with tungsten halogen lamps. The process is rapid (under 100 s) and low temperature (peak temperature < 580{degrees}C), making it favorable for commercial solar cell fabrication.

  2. Solubility controls on aluminum in drinking water at relatively low and high pH.

    PubMed

    Kvech, Steve; Edwards, Marc

    2002-10-01

    Potential control of soluble aluminum in drinking water by formation of solids other than Al(OH)3 was examined. At pHs below 6.0, Al(+3) solids containing sulfate, silica or potassium are thermodynamically favored versus amorphous Al(OH)3; however, in this work no evidence could be obtained that solids other than Al(OH)3 would form in practice. At pHs above 9, aluminum and magnesium were discovered to form complex solid phases of approximate composition AlMg2(OH)7, AlMg2SiO2(OH)7 or Al(SiO2)2(OH)3 dependent on circumstance. Formation of these solids provide a mechanistic explanation for enhancements to precipitative softening obtained in practice by dosing Al(+3) salts; that is, improved flocculation/settling and removal of silica from water that interferes with calcium precipitation. The solids also maintain residual aluminum below regulatory guidelines at high pH > 9.5.

  3. Integrated sensor and actuator fault-tolerant control

    NASA Astrophysics Data System (ADS)

    Seron, María M.; De Doná, José A.; Richter, Jan H.

    2013-04-01

    We propose a fault-tolerant control scheme that deals with sensor and actuator faults through the use of a virtual actuator (VA) and a bank of virtual sensors (VSs). A novel feature of the scheme is that the VSs implicitly integrate both fault detection and isolation (FDI) and - in conjunction with the VA - controller reconfiguration tasks. The VA and the bank of VSs operate in closed-loop with an observer-based tracking controller designed for a nominal (fault free) model of the plant. A switching rule that reconfigures the VA and engages the suitable VS from the bank is based on sets defined for measurable residual signals constructed directly from the VS signals. Our method handles abrupt actuator and sensor faults of arbitrary magnitude including complete outage. The overall scheme is shown to guarantee closed-loop boundedness and setpoint tracking under all considered fault situations. Enhancements of the scheme to deal with errors in the fault detection and isolation are also proposed. Applications of the scheme to a winding machine and an interconnected tank system are presented.

  4. Plant Tolerance: A Unique Approach to Control Hemipteran Pests

    PubMed Central

    Koch, Kyle G.; Chapman, Kaitlin; Louis, Joe; Heng-Moss, Tiffany; Sarath, Gautam

    2016-01-01

    Plant tolerance to insect pests has been indicated to be a unique category of resistance, however, very little information is available on the mechanism of tolerance against insect pests. Tolerance is distinctive in terms of the plant’s ability to withstand or recover from herbivore injury through growth and compensatory physiological processes. Because plant tolerance involves plant compensatory characteristics, the plant is able to harbor large numbers of herbivores without interfering with the insect pest’s physiology or behavior. Some studies have observed that tolerant plants can compensate photosynthetically by avoiding feedback inhibition and impaired electron flow through photosystem II that occurs as a result of insect feeding. Similarly, the up-regulation of peroxidases and other oxidative enzymes during insect feeding, in conjunction with elevated levels of phytohormones can play an important role in providing plant tolerance to insect pests. Hemipteran insects comprise some of the most economically important plant pests (e.g., aphids, whiteflies), due to their ability to achieve high population growth and their potential to transmit plant viruses. In this review, results from studies on plant tolerance to hemipterans are summarized, and potential models to understand tolerance are presented. PMID:27679643

  5. Fault tolerant, reliable and scalable scientific ballooning control software

    NASA Astrophysics Data System (ADS)

    Stewart, Michael F.; Ellison, Steven B.; Isbert, Joachim; Granger, Doug; Guzik, T. Gregory; Wefel, John P.

    The Universal Balloon Control Software package (UBCS) was first designed and developed for the ATIC experiment in 1997 and has evolved over the years into a highly reliable and adaptable control system. The system has logged thousands of hours of operation time on ATIC with few reboots and has been adapted for the HASP balloon payload which has had two successful flights in 2006 and 2007. The goal was to develop a UBCS that was fault tolerant and auto-recoverable while at the same time extremely reliable and scalable. In order to meet these goals, we designed a modular software system where each process was able to run in parallel with other processes on the same or different CPUs. These modular processes needed to be relatively independent; so that one process didn't rely on another in order to function. We chose QNX 4.25 as the operating system because of its multi-tasking abilities and the level of abstraction offered in communication between processes. Another key component in the UBCS, called the Buffer Process Group (BPG), was developed to de-couple processes from one another allowing each to operate independently. The BPG is a client/server process data port with a standardized interface allowing any given server to load records for access by an independent client at any given time. The BPG is capable of handling many data servers and clients simultaneously. Examples of data servers are the data acquisition process and housekeeping processes and examples of data clients are the archive process, the down link telemetry processes and the ground display processes. Together, the BPG process and the QNX 4.25 OS allow the UBCS to meet all of its design goals. In particular they allow the system to be highly fault tolerant and recoverable. A monitoring process is able to restart failed processes and reboot the computers on which they reside, if necessary. This allows the UBCS to recover from software errors or bugs as well as hardware glitches such as temporary

  6. Anodic aluminum oxide with fine pore size control for selective and effective particulate matter filtering

    NASA Astrophysics Data System (ADS)

    Zhang, Su; Wang, Yang; Tan, Yingling; Zhu, Jianfeng; Liu, Kai; Zhu, Jia

    2016-07-01

    Air pollution is widely considered as one of the most pressing environmental health issues. Particularly, atmospheric particulate matters (PM), a complex mixture of solid or liquid matter suspended in the atmosphere, are a harmful form of air pollution due to its ability to penetrate deep into the lungs and blood streams, causing permanent damages such as DNA mutations and premature death. Therefore, porous materials which can effectively filter out particulate matters are highly desirable. Here, for the first time, we demonstrate that anodic aluminum oxide with fine pore size control fabricated through a scalable process can serve as effective and selective filtering materials for different types of particulate matters (such as PM2.5, PM10). Combining selective and dramatic filtering effect, fine pore size control and a scalable process, this type of anodic aluminum oxide templates can potentially serve as a novel selective filter for different kinds of particulate matters, and a promising and complementary solution to tackle this serious environmental issue.

  7. Tolerance of Sitophilus zeamais (Coleoptera: Curculionidae) to heated controlled atmosphere treatments

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Combination heat and controlled atmosphere (CA) postharvest phytosanitary treatments are environmentally friendly alternatives to chemical fumigants. A controlled atmosphere/ heating block system (CA-HBS) was used to rapidly assess tolerances of adult maize weevil, Sitophilus zeamais, both under reg...

  8. Validation Methods for Fault-Tolerant avionics and control systems, working group meeting 1

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The proceedings of the first working group meeting on validation methods for fault tolerant computer design are presented. The state of the art in fault tolerant computer validation was examined in order to provide a framework for future discussions concerning research issues for the validation of fault tolerant avionics and flight control systems. The development of positions concerning critical aspects of the validation process are given.

  9. Attack-tolerant networked control system: an approach for detection the controller stealthy hijacking attack

    NASA Astrophysics Data System (ADS)

    Atta Yaseen, Amer; Bayart, Mireille

    2017-01-01

    In this work, a new approach will be introduced as a development for the attack-tolerant scheme in the Networked Control System (NCS). The objective is to be able to detect an attack such as the Stuxnet case where the controller is reprogrammed and hijacked. Besides the ability to detect the stealthy controller hijacking attack, the advantage of this approach is that there is no need for a priori mathematical model of the controller. In order to implement the proposed scheme, a specific detector for the controller hijacking attack is designed. The performance of this scheme is evaluated be connected the detector to NCS with basic security elements such as Data Encryption Standard (DES), Message Digest (MD5), and timestamp. The detector is tested along with networked PI controller under stealthy hijacking attack. The test results of the proposed method show that the hijacked controller can be significantly detected and recovered.

  10. Metallurgical Mechanisms Controlling Mechanical Properties of Aluminum Alloy 2219 Produced by Electron Beam Freeform Fabrication

    NASA Technical Reports Server (NTRS)

    Domack, Marcia S.; Tainger, Karen M.

    2006-01-01

    The electron beam freeform fabrication (EBF3) layer-additive manufacturing process has been developed to directly fabricate complex geometry components. EBF3 introduces metal wire into a molten pool created on the surface of a substrate by a focused electron beam. Part geometry is achieved by translating the substrate with respect to the beam to build the part one layer at a time. Tensile properties demonstrated for electron beam deposited aluminum and titanium alloys are comparable to wrought products, although the microstructures of the deposits exhibit cast features. Understanding the metallurgical mechanisms controlling mechanical properties is essential to maximizing application of the EBF3 process. Tensile mechanical properties and microstructures were examined for aluminum alloy 2219 fabricated over a range of EBF3 process variables. Unique microstructures were observed within the deposited layers and at interlayer boundaries, which varied within the deposit height due to microstructural evolution associated with the complex thermal history experienced during subsequent layer deposition. Microstructures exhibited irregularly shaped grains with interior dendritic structures, described based on overall grain size, morphology, distribution, and dendrite spacing, and were correlated with deposition parameters. Fracture features were compared with microstructural elements to define fracture paths and aid in definition of basic processing-microstructure-property correlations.

  11. Metallurgical Mechanisms Controlling Mechanical Properties of Aluminum Alloy 2219 Produced By Electron Beam Freeform Fabrication

    NASA Technical Reports Server (NTRS)

    Domack, Marcia S.; Taminger, Karen M. B.; Begley, Matthew

    2006-01-01

    The electron beam freeform fabrication (EBF3) layer-additive manufacturing process has been developed to directly fabricate complex geometry components. EBF3 introduces metal wire into a molten pool created on the surface of a substrate by a focused electron beam. Part geometry is achieved by translating the substrate with respect to the beam to build the part one layer at a time. Tensile properties have been demonstrated for electron beam deposited aluminum and titanium alloys that are comparable to wrought products, although the microstructures of the deposits exhibit features more typical of cast material. Understanding the metallurgical mechanisms controlling mechanical properties is essential to maximizing application of the EBF3 process. In the current study, mechanical properties and resulting microstructures were examined for aluminum alloy 2219 fabricated over a range of EBF3 process variables. Material performance was evaluated based on tensile properties and results were compared with properties of Al 2219 wrought products. Unique microstructures were observed within the deposited layers and at interlayer boundaries, which varied within the deposit height due to microstructural evolution associated with the complex thermal history experienced during subsequent layer deposition. Microstructures exhibited irregularly shaped grains, typically with interior dendritic structures, which were described based on overall grain size, morphology, distribution, and dendrite spacing, and were correlated with deposition parameters. Fracture features were compared with microstructural elements to define fracture paths and aid in definition of basic processing-microstructure-property correlations.

  12. An Integrated Fault Tolerant Robotic Controller System for High Reliability and Safety

    NASA Technical Reports Server (NTRS)

    Marzwell, Neville I.; Tso, Kam S.; Hecht, Myron

    1994-01-01

    This paper describes the concepts and features of a fault-tolerant intelligent robotic control system being developed for applications that require high dependability (reliability, availability, and safety). The system consists of two major elements: a fault-tolerant controller and an operator workstation. The fault-tolerant controller uses a strategy which allows for detection and recovery of hardware, operating system, and application software failures.The fault-tolerant controller can be used by itself in a wide variety of applications in industry, process control, and communications. The controller in combination with the operator workstation can be applied to robotic applications such as spaceborne extravehicular activities, hazardous materials handling, inspection and maintenance of high value items (e.g., space vehicles, reactor internals, or aircraft), medicine, and other tasks where a robot system failure poses a significant risk to life or property.

  13. DC-SIGN(+) Macrophages Control the Induction of Transplantation Tolerance.

    PubMed

    Conde, Patricia; Rodriguez, Mercedes; van der Touw, William; Jimenez, Ana; Burns, Matthew; Miller, Jennifer; Brahmachary, Manisha; Chen, Hui-ming; Boros, Peter; Rausell-Palamos, Francisco; Yun, Tae Jin; Riquelme, Paloma; Rastrojo, Alberto; Aguado, Begoña; Stein-Streilein, Joan; Tanaka, Masato; Zhou, Lan; Zhang, Junfeng; Lowary, Todd L; Ginhoux, Florent; Park, Chae Gyu; Cheong, Cheolho; Brody, Joshua; Turley, Shannon J; Lira, Sergio A; Bronte, Vincenzo; Gordon, Siamon; Heeger, Peter S; Merad, Miriam; Hutchinson, James; Chen, Shu-Hsia; Ochando, Jordi

    2015-06-16

    Tissue effector cells of the monocyte lineage can differentiate into different cell types with specific cell function depending on their environment. The phenotype, developmental requirements, and functional mechanisms of immune protective macrophages that mediate the induction of transplantation tolerance remain elusive. Here, we demonstrate that costimulatory blockade favored accumulation of DC-SIGN-expressing macrophages that inhibited CD8(+) T cell immunity and promoted CD4(+)Foxp3(+) Treg cell expansion in numbers. Mechanistically, that simultaneous DC-SIGN engagement by fucosylated ligands and TLR4 signaling was required for production of immunoregulatory IL-10 associated with prolonged allograft survival. Deletion of DC-SIGN-expressing macrophages in vivo, interfering with their CSF1-dependent development, or preventing the DC-SIGN signaling pathway abrogated tolerance. Together, the results provide new insights into the tolerogenic effects of costimulatory blockade and identify DC-SIGN(+) suppressive macrophages as crucial mediators of immunological tolerance with the concomitant therapeutic implications in the clinic.

  14. Genetic control of cadmium tolerance in Drosophila melanogaster

    SciTech Connect

    Maroni, G.; Ann-Shu Ho; Theodore, L.

    1995-12-01

    Flies from a transgenic line of Drosophila melanogaster with two copies of the metallothionein allele Mtn{sup 3} were more tolerant to cadmium than strains with only one copy of the gene. However, flies with the Mtn{sup 3} allele were as tolerant as flies with the Mtn{sup 1} allele, despite the level of expression of Mtn{sup {minus}3} allele were as tolerant as flies with the Mtn{sup 1} allele, despite the level of expression of Mtn{sup 1} being three times higher than that of Mtn{sup {minus}3}. We propose that the substitution of Lys-40 (in Mtn{sup 3}) for Glu-40 (in Mtn{sup 1}) accounts for a reduction in binding affinity of Mtn{sup 1}, which offsets the increased expression levels. 6 refs., 3 figs., 2 tabs.

  15. SIFT - Multiprocessor architecture for Software Implemented Fault Tolerance flight control and avionics computers

    NASA Technical Reports Server (NTRS)

    Forman, P.; Moses, K.

    1979-01-01

    A brief description of a SIFT (Software Implemented Fault Tolerance) Flight Control Computer with emphasis on implementation is presented. A multiprocessor system that relies on software-implemented fault detection and reconfiguration algorithms is described. A high level reliability and fault tolerance is achieved by the replication of computing tasks among processing units.

  16. Searching in sequences of Leymus BAC clones for genes controlling salt tolerance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many species of Thinopyrum and Leymus are known to be highly salt tolerant. Salinity tolerance in diploid Thinopyrum elongatum, thus all polyploid Thinopyrum species too, is controlled by genes on different chromosomes. Some candidate genes, including genes for peroxidase precursor, for salinity t...

  17. Complex shape product tolerance and accuracy control method for virtual assembly

    NASA Astrophysics Data System (ADS)

    Ma, Huiping; Jin, Yuanqiang; Zhang, Xiaoguang; Zhou, Hai

    2015-02-01

    The simulation of virtual assembly process for engineering design lacks of accuracy in the software of three-dimension CAD at present. Product modeling technology with tolerance, assembly precision preanalysis technique and precision control method are developed. To solve the problem of lack of precision information transmission in CAD, tolerance mathematical model of Small Displacement Torsor (SDT) is presented, which can bring about technology transfer and establishment of digital control function for geometric elements from the definition, description, specification to the actual inspection and evaluation process. Current tolerance optimization design methods for complex shape product are proposed for optimization of machining technology, effective cost control and assembly quality of the products.

  18. Regulation of Galactolipid Biosynthesis by Overexpression of the Rice MGD Gene Contributes to Enhanced Aluminum Tolerance in Tobacco

    PubMed Central

    Zhang, Meijuan; Deng, Xiping; Yin, Lina; Qi, Lingyun; Wang, Xinyue; Wang, Shiwen; Li, Hongbing

    2016-01-01

    Membrane lipid alterations affect Al tolerance in plants, but little is known about the regulation of membrane lipid metabolism in response to Al stress. Transgenic tobacco (Nicotiana tabacum) overexpressing rice monogalactosyldiacylglycerol (MGDG) synthase (OsMGD) gene and wild-type tobacco plants were exposed to AlCl3, and the impact of Al toxicity on root growth, Al accumulation, plasma membrane integrity, lipid peroxidation and membrane lipid composition were investigated. Compared with the wild type, the transgenic plants exhibited rapid regrowth of roots after removal of Al and less damage to membrane integrity and lipid peroxidation under Al stress, meanwhile, the Al accumulation showed no difference between wild-type and transgenic plants. Lipid analysis showed that Al treatment dramatically decreased the content of MGDG and the ratio of MGDG to digalactosyldiacylglycerol (DGDG) in wild-type plants, while it was unchanged in transgenic plants. The stable of MGDG level and the ratio of MGDG/DGDG contribute to maintain the membrane stability and permeability. Moreover, Al caused a significant increase in phospholipids in wild-type plants, resulting in a high proportion of phospholipids and low proportion of galactolipids, but these proportions were unaffected in transgenic plants. The high proportion of phospholipids could contribute to a higher rate of Al3+ binding in the membrane and thereby leads to more membrane perturbation and damage. These results show that the regulation of galactolipid biosynthesis could play an important role in maintaining membrane structure and function under Al stress. PMID:27066017

  19. Defectivity control of aluminum chemical mechanical planarization in replacement metal gate process of MOSFET

    NASA Astrophysics Data System (ADS)

    Jin, Zhang; Yuling, Liu; Chenqi, Yan; Yangang, He; Baohong, Gao

    2016-04-01

    The replacement metal gate (RMG) defectivity performance control is very challenging in high-k metal gate (HKMG) chemical mechanical polishing (CMP). In this study, three major defect types, including fall-on particles, micro-scratch and corrosion have been investigated. The research studied the effects of polishing pad, pressure, rotating speed, flow rate and post-CMP cleaning on the three kinds of defect, which finally eliminated the defects and achieved good surface morphology. This study will provide an important reference value for the future research of aluminum metal gate CMP. Project supported by the Major National Science and Technology Special Projects (No. 2009ZX02308), the Natural Science Foundation for the Youth of Hebei Province (Nos. F2012202094, F2015202267), and the Outstanding Youth Science and Technology Innovation Fund of Hebei University of Technology (No. 2013010).

  20. Controlling Pore Geometries and Interpore Distances of Anodic Aluminum Oxide Templates via Three-Step Anodization.

    PubMed

    Lim, Jin-Hee; Wiley, John B

    2015-01-01

    Porous alumina membranes have attracted much attention because they are very useful templates for the fabrication of various nanostructures important to nanotechnology. However, there are challenges in controlling pore geometries and interpore distances in alumina templates while maintaining highly ordered hexagonal pore structures. Herein, a three-step anodization method is utilized to prepare anodic alumina templates with various pore morphologies (e.g., arched-shape, tree-like, branched-shape) and tunable interpore distances. Such structures are not found within the more traditional alumina templates fabricated by a two-step anodization of aluminum films. The range of interpore distances and pore diameters within the modified templates increases with increasing voltages. In contrast, under decreasing voltages, hexagonally ordered pores can also branch into several pores with smaller sizes and reduced interpore distances. Electrochemical growth of metal nanowires in the modified templates helps to highlight details of the pore structures and which pore channels are active.

  1. Evolution and Control of 2219 Aluminum Microstructural Features through Electron Beam Freeform Fabrication

    NASA Technical Reports Server (NTRS)

    Taminger, Karen M.; Hafley, Robert A.; Domack, Marcia S.

    2006-01-01

    Electron beam freeform fabrication (EBF3) is a new layer-additive process that has been developed for near-net shape fabrication of complex structures. EBF3 uses an electron beam to create a molten pool on the surface of a substrate. Wire is fed into the molten pool and the part translated with respect to the beam to build up a 3-dimensional structure one layer at a time. Unlike many other freeform fabrication processes, the energy coupling of the electron beam is extremely well suited to processing of aluminum alloys. The layer-additive nature of the EBF3 process results in a tortuous thermal path producing complex microstructures including: small homogeneous equiaxed grains; dendritic growth contained within larger grains; and/or pervasive dendritic formation in the interpass regions of the deposits. Several process control variables contribute to the formation of these different microstructures, including translation speed, wire feed rate, beam current and accelerating voltage. In electron beam processing, higher accelerating voltages embed the energy deeper below the surface of the substrate. Two EBF3 systems have been established at NASA Langley, one with a low-voltage (10-30kV) and the other a high-voltage (30-60 kV) electron beam gun. Aluminum alloy 2219 was processed over a range of different variables to explore the design space and correlate the resultant microstructures with the processing parameters. This report is specifically exploring the impact of accelerating voltage. Of particular interest is correlating energy to the resultant material characteristics to determine the potential of achieving microstructural control through precise management of the heat flux and cooling rates during deposition.

  2. How to avoid the `invisible gorilla' in aluminum smelting process control: Visual guidelines

    NASA Astrophysics Data System (ADS)

    Gao, Yashuang; Taylor, Mark P.; Chen, John J. J.; Hautus, Michael J.

    2011-08-01

    Over the last three decades, process control in aluminum smelters has improved significantly as it is the biggest leverage for cost and energy reduction in production and product quality improvement, as well as for meeting environmental compliance. The implementation of computerized automatic control systems two decades ago was a step change in improvement in the state of the art of process control. However, the complex and dynamic nature of the process requires human monitoring, diagnosis, and intervention from time to time. This study investigates the use of the supervisory screen of the control system of a smelter, as well as the effectiveness of visual guidelines to help the operators to identify process abnormalities. The results show that visual guidelines such as voltage patterns which are used as a reference improve the performance of the operators. Detection time and falsealarm rates were reduced in addition to increasing detection sensitivities. It is proposed that a higher level of human and system interaction would improve the overall performance process control.

  3. Aluminum reference electrode

    DOEpatents

    Sadoway, D.R.

    1988-08-16

    A stable reference electrode is described for use in monitoring and controlling the process of electrolytic reduction of a metal. In the case of Hall cell reduction of aluminum, the reference electrode comprises a pool of molten aluminum and a solution of molten cryolite, Na[sub 3]AlF[sub 6], wherein the electrical connection to the molten aluminum does not contact the highly corrosive molten salt solution. This is accomplished by altering the density of either the aluminum (decreasing the density) or the electrolyte (increasing the density) so that the aluminum floats on top of the molten salt solution. 1 fig.

  4. Aluminum reference electrode

    DOEpatents

    Sadoway, Donald R.

    1988-01-01

    A stable reference electrode for use in monitoring and controlling the process of electrolytic reduction of a metal. In the case of Hall cell reduction of aluminum, the reference electrode comprises a pool of molten aluminum and a solution of molten cryolite, Na.sub.3 AlF.sub.6, wherein the electrical connection to the molten aluminum does not contact the highly corrosive molten salt solution. This is accomplished by altering the density of either the aluminum (decreasing the density) or the electrolyte (increasing the density) so that the aluminum floats on top of the molten salt solution.

  5. Design of fault tolerant control system for individual blade control helicopters

    NASA Astrophysics Data System (ADS)

    Tamayo, Sergio

    This dissertation presents the development of a fault tolerant control scheme for helicopters fitted with individually controlled blades. This novel approach attempts to improve fault tolerant capabilities of helicopter control system by increasing control redundancy using additional actuators for individual blade input and software re-mixing to obtain nominal or close to nominal conditions under failure. An advanced interactive simulation environment has been developed including modeling of sensor failure, swashplate actuator failure, individual blade actuator failure, and blade delamination to support the design, testing, and evaluation of the control laws. This simulation environment is based on the blade element theory for the calculation of forces and moments generated by the main rotor. This discretized model allows for individual blade analysis, which in turn allows measuring the consequences of a stuck blade, or loss of the surface area of the blade itself, with respect to the dynamics of the whole helicopter. The control laws are based on non-linear dynamic inversion and artificial neural network augmentation, which is a mix of linear and nonlinear methods that compensates for model inaccuracies due to linearization or failure. A stability analysis based on the Lyapunov function approach has shown that bounded tracking error is guaranteed, and under specific circumstances, global stability is guaranteed as well. An analysis over the degrees of freedom of the mechanical system and its impact over the helicopter handling qualities is also performed to measure the degree of redundancy achieved with the addition of individual blade actuators as compared to a classic swashplate helicopter configuration. Mathematical analysis and numerical simulation, using reconfiguration of the individual blade control under failure have shown that this control architecture can potentially improve the survivability of the aircraft and reduce pilot workload under failure

  6. Observer-based fault-tolerant control for a class of nonlinear networked control systems

    NASA Astrophysics Data System (ADS)

    Mahmoud, M. S.; Memon, A. M.; Shi, Peng

    2014-08-01

    This paper presents a fault-tolerant control (FTC) scheme for nonlinear systems which are connected in a networked control system. The nonlinear system is first transformed into two subsystems such that the unobservable part is affected by a fault and the observable part is unaffected. An observer is then designed which gives state estimates using a Luenberger observer and also estimates unknown parameter of the system; this helps in fault estimation. The FTC is applied in the presence of sampling due to the presence of a network in the loop. The controller gain is obtained using linear-quadratic regulator technique. The methodology is applied on a mechatronic system and the results show satisfactory performance.

  7. A Highly Controllable Electrochemical Anodization Process to Fabricate Porous Anodic Aluminum Oxide Membranes.

    PubMed

    Lin, Yuanjing; Lin, Qingfeng; Liu, Xue; Gao, Yuan; He, Jin; Wang, Wenli; Fan, Zhiyong

    2015-12-01

    Due to the broad applications of porous alumina nanostructures, research on fabrication of anodized aluminum oxide (AAO) with nanoporous structure has triggered enormous attention. While fabrication of highly ordered nanoporous AAO with tunable geometric features has been widely reported, it is known that its growth rate can be easily affected by the fluctuation of process conditions such as acid concentration and temperature during electrochemical anodization process. To fabricate AAO with various geometric parameters, particularly, to realize precise control over pore depth for scientific research and commercial applications, a controllable fabrication process is essential. In this work, we revealed a linear correlation between the integrated electric charge flow throughout the circuit in the stable anodization process and the growth thickness of AAO membranes. With this understanding, we developed a facile approach to precisely control the growth process of the membranes. It was found that this approach is applicable in a large voltage range, and it may be extended to anodization of other metal materials such as Ti as well.

  8. Control of the anodic aluminum oxide barrier layer opening process by wet chemical etching.

    PubMed

    Han, Catherine Y; Willing, Gerold A; Xiao, Zhili; Wang, H Hau

    2007-01-30

    In this work, it has been shown that, through a highly controlled process, the chemical etching of the anodic aluminum oxide membrane barrier layer can be performed in such a way as to achieve nanometer-scale control of the pore opening. As the barrier layer is etched away, subtle differences revealed through AFM phase imaging in the alumina composition in the barrier layer give rise to a unique pattern of hexagonal walls surrounding each of the barrier layer domes. These nanostructures observed in both topography and phase images can be understood as differences in the oxalate anion contaminated alumina versus pure alumina. This information bears significant implication for catalysis, template synthesis, and chemical sensing applications. From the pore opening etching studies, the etching rate of the barrier layer (1.3 nm/min) is higher than that of the inner cell wall (0.93 nm/min), both of which are higher than the etching rate of pure alumina layer (0.5-0.17 nm/min). The established etching rates together with the etching temperature allow one to control the pore diameter systematically from 10 to 95 nm.

  9. Glucose tolerance in depressed inpatients, under treatment with mirtazapine and in healthy controls.

    PubMed

    Hennings, J M; Ising, M; Grautoff, S; Himmerich, H; Pollmächer, T; Schaaf, L

    2010-02-01

    Impaired glucose tolerance and diabetes have been associated with depression, and antidepressant treatment is assumed to improve impaired glucose tolerance. However, antidepressant treatment is also considered as a risk factor for the development of diabetes. Reports about glucose tolerance under antidepressant treatment frequently lack appropriate control groups. We conducted the oral glucose tolerance test (OGTT) in 10 healthy controls selected from an epidemiological sample with a negative lifetime history of mental Axis I disorder. Controls were carefully matched to a sample of inpatients with major depression that participated in an OGTT before and after antidepressant treatment with mirtazapine. All participants underwent a standard OGTT protocol. In patients, a second (after 2 weeks) and a third (after 4-6 weeks) OGTT was performed under treatment with mirtazapine. Compared to healthy controls, we observed significantly impaired glucose tolerance in acutely depressed patients. Effect size calculation indicated a moderate to large effects on glucose and insulin concentrations in response to an OGTT. Although glucose tolerance improved under mirtazapine treatment, insulin sensitivity was still impaired and remained significantly lower in patients compared to controls.

  10. On the Controller Synthesis for Markov Decision Process of Conflict Tolerant Specification

    NASA Astrophysics Data System (ADS)

    Zhang, Junhua; Huang, Zhiqiu; Cao, Zining

    For an embedded control system, different requirements often need be satisfied at same time, and some of them make the system to act conflicted. Conflict tolerant specification is provided to denote this situation. In such a system, there often exist probabilistic and non-deterministic behaviors. We use Markov Decision Process (MDP) to denote these features. We study the controller synthesis for MDP over conflict tolerant specification. We extend PCTL star by adding past operator to denote the conflict tolerant specification succinctly. We use CT-PLTL to denote conflicted actions and PCTL to denote the specification for probability demand. We first synthesize a controller on a base system over CT-PLTL and then use it to prune the corresponding MDP of the system model. We use the resulting sub-MDP as the model to further synthesis a controller over PCTL. The whole controller for MDP is a conjunction of the two controllers obtained.

  11. Real-time optimal torque control of fault-tolerant permanent magnet brushless machines

    NASA Astrophysics Data System (ADS)

    Max, L.; Wang, J.; Atallah, K.; Howe, D.

    2005-05-01

    The paper describes issues that are pertinent to control system hardware and software design for the real-time implementation of an optimal torque control strategy for fault-tolerant permanent magnet brushless ac drives, and reports experimental results. The influence of the current control loop bandwidth and pulse width modulation on the torque ripple are investigated and quantified.

  12. 76 FR 67315 - Supplemental Nutrition Assistance Program: Quality Control Error Tolerance Threshold

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-01

    ... Service 7 CFR Part 275 RIN 0584-AE24 Supplemental Nutrition Assistance Program: Quality Control Error... direct final rule is amending the Quality Control (QC) review error threshold in our regulations from $25... Assistance Program: Quality Control Error Tolerance Threshold Direct Rule, in the subject line of the...

  13. Evolution and Control of 2219 Aluminum Microstructural Features Through Electron Beam Freeform Fabrication

    NASA Technical Reports Server (NTRS)

    Taminger, Karen M.; Hafley, Robert A.; Domack, Marcia S.

    2006-01-01

    The layer-additive nature of the electron beam freeform fabrication (EBF3) process results in a tortuous thermal path producing complex microstructures including: small homogeneous equiaxed grains; dendritic growth contained within larger grains; and/or pervasive dendritic formation in the interpass regions of the deposits. Several process control variables contribute to the formation of these different microstructures, including translation speed, wire feed rate, beam current and accelerating voltage. In electron beam processing, higher accelerating voltages embed the energy deeper below the surface of the substrate. Two EBF3 systems have been established at NASA Langley, one with a low-voltage (10-30kV) and the other a high-voltage (30-60 kV) electron beam gun. Aluminum alloy 2219 was processed over a range of different variables to explore the design space and correlate the resultant microstructures with the processing parameters. This report is specifically exploring the impact of accelerating voltage. Of particular interest is correlating energy to the resultant material characteristics to determine the potential of achieving microstructural control through precise management of the heat flux and cooling rates during deposition.

  14. Control of Crystal Morphology for Mold Flux During High-Aluminum AHSS Continuous Casting Process

    NASA Astrophysics Data System (ADS)

    GUO, Jing; SEO, Myung-Duk; SHI, Cheng-Bin; CHO, Jung-Wook; KIM, Seon-Hyo

    2016-08-01

    In the present manuscript, the efforts to control the crystal morphology are carried out aiming at improving the lubrication of lime-alumina-based mold flux for casting advanced high-strength steel with high aluminum. Jackson α factors for crystals of melt crystallization in multi-component mold fluxes are established and reasonably evaluated by applying thermodynamic databases to understand the crystal morphology control both in lime-alumina-based and lime-silica-based mold fluxes. The results show that Jackson α factor and supercooling are the most critical factors to determine the crystal morphology in a mold flux. Crystals precipitating in mold fluxes appear with different morphologies due to their different Jackson α factors and are likely to be more faceted with higher Jackson α factor. In addition, there is a critical supercooling degree for crystal morphology dendritic transition. When the supercooling over the critical value, the crystals transform from faceted shape to dendritic ones in morphology as the kinetic roughening occurs. Typically, the critical supercooling degrees for cuspidine dendritic transition in the lime-silica-based mold fluxes are evaluated to be between 0.05 and 0.06. Finally, addition of a small amount of Li2O in the mold flux can increase the Jackson α factor and decrease the supercooling for cuspidine precipitation; thus, it is favorable to enhance a faceted cuspidine crystal.

  15. 76 FR 23490 - Aluminum tris (O

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-27

    .... Also, EPA is revoking the tolerances for aluminum tris (O-ethylphosphonate) on pineapple fodder and... aluminum tris (O-ethylphosphonate) on pineapple fodder and forage because they are not considered to be... for aluminum tris (O-ethylphosphonate) on pineapple fodder and forage because they are not...

  16. Modeling the Fault Tolerant Capability of a Flight Control System: An Exercise in SCR Specification

    NASA Technical Reports Server (NTRS)

    Alexander, Chris; Cortellessa, Vittorio; DelGobbo, Diego; Mili, Ali; Napolitano, Marcello

    2000-01-01

    In life-critical and mission-critical applications, it is important to make provisions for a wide range of contingencies, by providing means for fault tolerance. In this paper, we discuss the specification of a flight control system that is fault tolerant with respect to sensor faults. Redundancy is provided by analytical relations that hold between sensor readings; depending on the conditions, this redundancy can be used to detect, identify and accommodate sensor faults.

  17. On Microstructural Control of Near-Threshold Fatigue Crack Growth in 7000-Series Aluminum Alloys.

    DTIC Science & Technology

    1982-04-02

    crack growth rate behavior for different microstruc - tural conditions in aluminum alloys is also in quantitative agreement with the predictions of the...34 .. . -~ Introduction ! A number of recent studies have been conducted to ascertain the influence of microstructure on fatigue crack growth behavior in aluminum...161. The da/dN data, obtained over a very broad spectrum of ,K, characterize the near-threshold growth-rate behavior unusually well. Predictions of

  18. Shape-controlled growth of indium and aluminum nanostructures on MoS2(0001).

    PubMed

    Kushvaha, S S; Xu, H; Zhang, H L; Wee, A T S; Wang, X S

    2008-05-01

    The growth of indium and aluminum nanostructures on molybdenum disulphide (MoS2)(0001) substrate has been studied using scanning tunneling microscopy in ultra-high vacuum. At low coverage and room temperature (RT), mostly ultra-thin (approximately 1.2-2 nm) triangular In islands were observed on MoS2. With increasing coverage or high flux, large coalesced irregular islands along with triangular and round-shaped ones of increased average height were found. Triangular and round-shaped islands were obtained after annealing the RT-deposited In on MoS2 sample at 450 K. At approximately 375 K, exclusively triangular In islands were observed. Al nanoparticles with diameter in 4-16 nm range were obtained after a low-flux deposited whereas ramified islands were observed in a high flux at RT. Ultra-thin (approximately 1.20-2 nm) Al islands and films were obtained on MoS2 after deposition at 500 K. These results demonstrate that the shape of In and Al nanostructures grown on MoS2 can be controlled in self-assembly by adjusting substrate temperature, deposition flux and amount.

  19. Integrated design of fault reconstruction and fault-tolerant control against actuator faults using learning observers

    NASA Astrophysics Data System (ADS)

    Jia, Qingxian; Chen, Wen; Zhang, Yingchun; Li, Huayi

    2016-12-01

    This paper addresses the problem of integrated fault reconstruction and fault-tolerant control in linear systems subject to actuator faults via learning observers (LOs). A reconfigurable fault-tolerant controller is designed based on the constructed LO to compensate for the influence of actuator faults by stabilising the closed-loop system. An integrated design of the proposed LO and the fault-tolerant controller is explored such that their performance can be simultaneously considered and their coupling problem can be effectively solved. In addition, such an integrated design is formulated in terms of linear matrix inequalities (LMIs) that can be conveniently solved in a unified framework using LMI optimisation technique. At last, simulation studies on a micro-satellite attitude control system are provided to verify the effectiveness of the proposed approach.

  20. A modal H∞-norm-based performance requirement for damage-tolerant active controller design

    NASA Astrophysics Data System (ADS)

    Genari, Helói F. G.; Mechbal, Nazih; Coffignal, Gérard; Nóbrega, Eurípedes G. O.

    2017-04-01

    Damage-tolerant active control (DTAC) is a recent research area that encompasses control design methodologies resulting from the application of fault-tolerant control methods to vibration control of structures subject to damage. The possibility of damage occurrence is not usually considered in the active vibration control design requirements. Damage changes the structure dynamics, which may produce unexpected modal behavior of the closed-loop system, usually not anticipated by the controller design approaches. A modal H∞ norm and a respective robust controller design framework were recently introduced, and this method is here extended to face a new DTAC strategy implementation. Considering that damage affects each vibration mode differently, this paper adopts the modal H∞ norm to include damage as a design requirement. The basic idea is to create an appropriate energy distribution over the frequency range of interest and respective vibration modes, guaranteeing robustness, damage tolerance, and adequate overall performance, taking into account that it is common to have previous knowledge of the structure regions where damage may occur during its operational life. For this purpose, a structural health monitoring technique is applied to evaluate modal modifications caused by damage. This information is used to create modal weighing matrices, conducting to the modal H∞ controller design. Finite element models are adopted for a case study structure, including different damage severities, in order to validate the proposed control strategy. Results show the effectiveness of the proposed methodology with respect to damage tolerance.

  1. Fault-tolerant controlled deterministic secure quantum communication using EPR states against collective noise

    NASA Astrophysics Data System (ADS)

    Kao, Shih-Hung; Yang, Chun-Wei; Hwang, Tzonelih

    2016-11-01

    This paper proposes two new fault-tolerant controlled deterministic secure quantum communication (CDSQC) protocols based only on Einstein-Podolsky-Rosen (EPR) entangled states. The proposed protocols are designed to be robust against the collective-dephasing noise and the collective-rotation noise, respectively. Compared to the existing fault-tolerant controlled quantum communication protocols, the proposed protocols not only can do without a quantum channel between the receiver and the controller as the state-of-the-art protocols do, but also have the advantage that the number of quantum particles required in the CDSQC protocols is reduced owing to the use of the simplest entangled states.

  2. Surface-Tolerant Coatings for Aircraft Hangars, Flight Control Tower, and Deluge Tanks at Fort Campbell

    DTIC Science & Technology

    2007-06-01

    and ranged from No. 0 (total) to No. 4 . The hangar doors were in good condition, having been re- cently overcoated. Degree of flaking was No. 10...ER D C/ CE RL T R- 07 -2 4 DoD Corrosion Prevention and Control Program Surface-Tolerant Coatings for Aircraft Hangars, Flight Control... 4 Risk associated with overcoating

  3. Cold tolerance of bed bugs and practical recommendations for control.

    PubMed

    Olson, Joelle F; Eaton, Marc; Kells, Stephen A; Morin, Victor; Wang, Changlu

    2013-12-01

    Bed bugs were exposed to freezing temperatures for various exposure times to determine cold tolerance and mortality estimates for multiple life stages. The mean supercooling point for all bed bug life stages ranged from -21.3 degrees C to -30.3 degrees C, with the egg stage reporting the lowest value. A probit analysis provided a lower lethal temperature (LLT99) of -31.2 degrees C when estimates from all life stages were combined, demonstrating that all stages of bed bugs are not capable of surviving temperatures below body freezing and are therefore freeze intolerant. At conditions above the LLT99, bed bug mortality depended on temperature and exposure time at temperatures above LLT99. Based on our model estimates, survival was estimated for temperatures above -12 degrees C even after 1 wk of continuous exposure. However, exposure to temperatures below -13 degrees C will result in 100% mortality in d to ensure mortality of all life stages. Unfortunately, sublethal exposure to lower temperatures did not prevent subsequent feeding behavior in surviving stages. Practical recommendations for management of potentially infested items are discussed.

  4. Simulation of Spacecraft Damage Tolerance and Adaptive Controls

    DTIC Science & Technology

    2013-06-01

    operator. Limitations of current technology abounded, leaving the X-15 with a successful, but severely limited adaptive control system. Since then...many limitations have fallen away, allowing for the first time employment of adaptive controls on a large scale. The nature of adaptive controls, or...THIS PAGE Unclassified 19. SECURITY CLASSIFICATION OF ABSTRACT Unclassified 20. LIMITATION OF ABSTRACT UU NSN 7540–01–280–5500 Standard Form

  5. Evaluation of borated aluminum products for criticality control in 235-F

    SciTech Connect

    Crouch, W.

    2003-04-01

    Plutonium-containing materials are destined for storage in the 235-F vault. The projected amount of stored materials will require the presence of neutron absorber materials. The leading design concept is for the neutron absorber materials to be in non-load-bearing borated aluminum plates lining the walls of the vault. A comprehensive evaluation of the borated aluminum plate materials was performed to identify a suitable material, and verify that these materials would remain effective as neutron absorbers under normal service conditions and for design-basis events, including the fire accident scenario, throughout a 20-year service life. Aluminum 1100 with boron additions is the recommended neutron absorber material for plutonium material storage in the 235-F vault based on boron loading capacity and durability in the storage environment. Borated aluminum 1100 is commercially available up to 4.5 wt. % boron. A detailed comparison was made of the physical, mechanical, and corrosion properties of borated aluminum alloy 1100 to standard alloy 1100-O1 to demonstrate near-equivalency in properties and to justify application of alloy 1100-O properties to the borated product as needed for the degradation analysis. The expected degradation of the borated aluminum is extremely low for storage conditions, including the bounding scenario of an aggressive atmospheric condition. A maximum loss of 0.00029 inches/year would be expected under potentially aggressive atmospheric conditions and would result in a fractional loss of only 0.42 wt. % of the boron present in a 7mm plate for a 20-year storage period. The fraction of Boron-10 consumption by spontaneous neutrons is expected to be less than 10-8 for the 20-year storage in 235-F fully loaded with Pu materials. The borated aluminum alloy 1100 will be thermally stable and unaltered up to near-melt temperature (643°C). Mechanical testing data at elevated temperatures show that the strengths (yield and ultimate) of the borated

  6. Evaluation of borated aluminum products for criticality control in 235-F

    SciTech Connect

    Duncan, A.; Sindelar, R.

    2003-05-06

    Plutonium-containing materials are destined for storage in the 235-F vault. The projected amount of stored materials will require the presence of neutron absorber materials. The leading design concept is for the neutron absorber materials to be in non-load-bearing borated aluminum plates lining the walls of the vault. A comprehensive evaluation of the borated aluminum plate materials was performed to identify a suitable material, and verify that these materials would remain effective as neutron absorbers under normal service conditions and for design-basis events, including the fire accident scenario, throughout a 20-year service life. Aluminum 1100 with boron additions is the recommended neutron absorber material for plutonium material storage in the 235-F vault based on boron loading capacity and durability in the storage environment. Borated aluminum 1100 is commercially available up to 4.5 wt. % boron. A detailed comparison was made of the physical, mechanical, and corrosion properties of borated aluminum alloy 1100 to standard alloy 1100-O (-O designating the fully annealed condition) to demonstrate near-equivalency in properties and to justify application of alloy 1100-O properties to the borated product as needed for the degradation analysis. The expected degradation of the borated aluminum is extremely low for storage conditions, including the bounding scenario of an aggressive atmospheric condition. A maximum loss of 0.00029 inches/year would be expected under potentially aggressive atmospheric conditions and would result in a fractional loss of only 0.42 wt.% of the boron present in a 7mm plate for a 20-year storage period. The fraction of Boron-10 consumption by spontaneous neutrons is expected to be less than 10{sup -8} for the 20-year storage in 235-F fully loaded with Pu materials. The borated aluminum alloy 1100 will be thermally stable and unaltered up to near-melt temperature (643°C). Mechanical testing data at elevated temperatures show that the

  7. Modeling, simulation and control of pulsed DE-GMA welding process for joining of aluminum to steel

    NASA Astrophysics Data System (ADS)

    Zhang, Gang; Shi, Yu; Li, Jie; Huang, Jiankang; Fan, Ding

    2014-09-01

    Joining of aluminum to steel has attracted significant attention from the welding research community, automotive and rail transportation industries. Many current welding methods have been developed and applied, however, they can not precisely control the heat input to work-piece, they are high costs, low efficiency and consist lots of complex welding devices, and the generated intermetallic compound layer in weld bead interface is thicker. A novel pulsed double electrode gas metal arc welding(Pulsed DE-GMAW) method is developed. To achieve a stable welding process for joining of aluminum to steel, a mathematical model of coupled arc is established, and a new control scheme that uses the average feedback arc voltage of main loop to adjust the wire feed speed to control coupled arc length is proposed and developed. Then, the impulse control simulation of coupled arc length, wire feed speed and wire extension is conducted to demonstrate the mathematical model and predict the stability of welding process by changing the distance of contact tip to work-piece(CTWD). To prove the proposed PSO based PID control scheme's feasibility, the rapid prototyping experimental system is setup and the bead-on-plate control experiments are conducted to join aluminum to steel. The impulse control simulation shows that the established model can accurately represent the variation of coupled arc length, wire feed speed and the average main arc voltage when the welding process is disturbed, and the developed controller has a faster response and adjustment, only runs about 0.1 s. The captured electric signals show the main arc voltage gradually closes to the supposed arc voltage by adjusting the wire feed speed in 0.8 s. The obtained typical current waveform demonstrates that the main current can be reduced by controlling the bypass current under maintaining a relative large total current. The control experiment proves the accuracy of proposed model and feasibility of new control scheme

  8. Controlled faceting and morphology for light trapping in aluminum-catalyzed silicon nanostructures

    NASA Astrophysics Data System (ADS)

    Hainey, Mel F.; Chen, Chen; Ke, Yue; Black, Marcie R.; Redwing, Joan M.

    2016-10-01

    Aluminum-catalyzed silicon nanopyramids grown using low-pressure chemical vapor deposition (LPCVD) are presented as an approach to silicon surface texturing. The nanopyramids are grown by vapor-liquid-solid growth using aluminum thin films on silicon. Silicon nanowires with hexagonal cross-sections are formed at a growth temperature of 650 °C; as the temperature is increased to 700 °C, the wires become pyramid-shaped with triangular cross-sections. The silicon nanopyramids are single-crystal and grow in the <111>direction with (112) facets, as confirmed by transmission electron microscopy. Pyramid tapering increases with increasing growth temperatures and the pyramid arrays grown at 700 °C show reflectivities between 4 and 6% between 400 nm and 800 nm and appear black to the eye. Based on these results, aluminum-catalyzed nanopyramids present themselves as a plausible alternative to etch-based silicon surface textures.

  9. Aluminum electrocoagulation as pretreatment during microfiltration of surface water containing NOM: A review of fouling, NOM, DBP, and virus control.

    PubMed

    Chellam, Shankararaman; Sari, Mutiara Ayu

    2016-03-05

    Electrocoagulation (EC) is the intentional corrosion of sacrificial anodes (typically aluminum or iron) by passing electricity to release metal-ion coagulant species and destabilize a wide range of suspended, dissolved, and macromolecular contaminants. It can be integrated ahead of microfiltration (MF) to effectively control turbidity, microorganisms, and disinfection by-products (DBPs) and simultaneously maintain a high MF specific flux. This manuscript summarizes the current knowledge on MF pretreatment by aluminum EC particularly focusing on mechanisms of (i) electrocoagulant dosing, (ii) (bio)colloid destabilization, (iii) fouling reductions, and (iv) enhanced removal of viruses, natural organic matter (NOM), and DBP precursors. Electrolysis efficiently removes hydrophobic NOM, viruses, and siliceous foulants. Aluminum effectively electrocoagulates viruses by physically encapsulating them in flocs, neutralizing their surface charge and reducing electrostatic repulsion, and increasing hydrophobic interactions between any sorbed NOM and free viruses. New results included herein demonstrate that EC achieves DBP control by removing NOM, reducing chlorine-reactivity of remaining NOM, and inducing a slight shift toward more brominated trihalomethanes and haloacetic acids. EC reduces MF fouling by forming large flocs that tend to deposit on the membrane surface, i.e. decrease pore penetration and forming more permeable cakes and by reducing foulant mass in case of significant floc-flotation.

  10. Physiological hemostasis based intelligent integrated cooperative controller for precise fault-tolerant control of redundant parallel manipulator

    NASA Astrophysics Data System (ADS)

    Hao, Kuangrong; Guo, Chongbin; Ding, Yongsheng

    2014-10-01

    This paper focuses on precise fault-tolerant control for actual redundant parallel manipulator. Based on kinematic redundancy, some unnoticed influences such as mechanical clearance have been considered to design a more precise and intelligent fault-tolerant plan for actual plants. According to regulation principles in human hemostasis system, a bio-inspired intelligent integrated cooperative controller (BIICC) is developed including system structure, algorithm and step in parameter tuning. The proposed BIICC optimises partial error signal and improves control performance in each sub-channel. Moreover, the new controller transfers and disposes cooperative control signals among different sub-channels to achieve an intelligent integrated fault-tolerant system. The proposed BIICC is applied to an actual 2-DOF (degrees of freedom) redundant parallel manipulator where the feasibility of the new controller is demonstrated. The BIICC is beneficial to control precision and fault-tolerant capability of redundant plant. The improvements are more obvious in cases where extra actuators of redundant manipulator are broken.

  11. Condensate microdrop self-propelling aluminum surfaces based on controllable fabrication of alumina rod-capped nanopores.

    PubMed

    Zhao, Ye; Luo, Yuting; Li, Juan; Yin, Fei; Zhu, Jie; Gao, Xuefeng

    2015-06-03

    Here, we report a type of aluminum-based condensate microdrop self-propelling (CMDSP) functional films based on the controllable fabrication of anodic alumina rod-capped nanopores, which can be realized by a three-step method based on the skillful combinations of well-established hard anodization, mild anodization and chemical etching techniques. Such a surface nanoengineering strategy is verified to be feasible via our exemplified experiments and scanning electronic microscopy characterizations. After fluorosilane modification, the surface nanostructure can induce the efficient self-jumping of small-scale condensate microdrops, especially below 50 μm. This work offers an avenue for developing CMDSP aluminum surfaces with self-cleaning, antifrosting, and antidewing functions.

  12. Robust Gain-Scheduled Fault Tolerant Control for a Transport Aircraft

    NASA Technical Reports Server (NTRS)

    Shin, Jong-Yeob; Gregory, Irene

    2007-01-01

    This paper presents an application of robust gain-scheduled control concepts using a linear parameter-varying (LPV) control synthesis method to design fault tolerant controllers for a civil transport aircraft. To apply the robust LPV control synthesis method, the nonlinear dynamics must be represented by an LPV model, which is developed using the function substitution method over the entire flight envelope. The developed LPV model associated with the aerodynamic coefficient uncertainties represents nonlinear dynamics including those outside the equilibrium manifold. Passive and active fault tolerant controllers (FTC) are designed for the longitudinal dynamics of the Boeing 747-100/200 aircraft in the presence of elevator failure. Both FTC laws are evaluated in the full nonlinear aircraft simulation in the presence of the elevator fault and the results are compared to show pros and cons of each control law.

  13. Fault-Tolerant, Multiple-Zone Temperature Control

    NASA Technical Reports Server (NTRS)

    Granger, James; Franklin, Brian; Michalik, Martin; Yates, Phillip; Peterson, Erik; Borders, James

    2008-01-01

    A computer program has been written as an essential part of an electronic temperature control system for a spaceborne instrument that contains several zones. The system was developed because the temperature and the rate of change of temperature in each zone are required to be maintained to within limits that amount to degrees of precision thought to be unattainable by use of simple bimetallic thermostats. The software collects temperature readings from six platinum resistance thermometers, calculates temperature errors from the readings, and implements a proportional + integral + derivative (PID) control algorithm that adjusts heater power levels. The software accepts, via a serial port, commands to change its operational parameters. The software attempts to detect and mitigate a host of potential faults. It is robust to many kinds of faults in that it can maintain PID control in the presence of those faults.

  14. The method providing fault-tolerance for information and control systems of the industrial mechatronic objects

    NASA Astrophysics Data System (ADS)

    Melnik, E. V.; Klimenko, A. B.; Korobkin, V. V.

    2017-02-01

    The paper deals with the provision of information and control system fault-tolerance. Nowadays, a huge quantity of industrial mechatronic objects operate within hazardous environments, where the human is not supposed to be. So the question of fault-tolerant information and control system design and development becomes the cornerstone of a large amount of industrial mechatronic objects. Within this paper, a new complex method of providing the reconfigurable systems fault-tolerance is represented. It bases on performance redundancy and decentralized dispatching principles. The key term within the method presented is a ‘configuration’, so the model of the configuration forming problem is represented too, and simulation results are given and discussed briefly.

  15. Fault tolerant computer control for a Maglev transportation system

    NASA Technical Reports Server (NTRS)

    Lala, Jaynarayan H.; Nagle, Gail A.; Anagnostopoulos, George

    1994-01-01

    Magnetically levitated (Maglev) vehicles operating on dedicated guideways at speeds of 500 km/hr are an emerging transportation alternative to short-haul air and high-speed rail. They have the potential to offer a service significantly more dependable than air and with less operating cost than both air and high-speed rail. Maglev transportation derives these benefits by using magnetic forces to suspend a vehicle 8 to 200 mm above the guideway. Magnetic forces are also used for propulsion and guidance. The combination of high speed, short headways, stringent ride quality requirements, and a distributed offboard propulsion system necessitates high levels of automation for the Maglev control and operation. Very high levels of safety and availability will be required for the Maglev control system. This paper describes the mission scenario, functional requirements, and dependability and performance requirements of the Maglev command, control, and communications system. A distributed hierarchical architecture consisting of vehicle on-board computers, wayside zone computers, a central computer facility, and communication links between these entities was synthesized to meet the functional and dependability requirements on the maglev. Two variations of the basic architecture are described: the Smart Vehicle Architecture (SVA) and the Zone Control Architecture (ZCA). Preliminary dependability modeling results are also presented.

  16. Formal specification of requirements for analytical redundancy-based fault-tolerant flight control systems

    NASA Astrophysics Data System (ADS)

    Del Gobbo, Diego

    2000-10-01

    Flight control systems are undergoing a rapid process of automation. The use of Fly-By-Wire digital flight control systems in commercial aviation (Airbus 320 and Boeing FBW-B777) is a clear sign of this trend. The increased automation goes in parallel with an increased complexity of flight control systems with obvious consequences on reliability and safety. Flight control systems must meet strict fault-tolerance requirements. The standard solution to achieving fault tolerance capability relies on multi-string architectures. On the other hand, multi-string architectures further increase the complexity of the system inducing a reduction of overall reliability. In the past two decades a variety of techniques based on analytical redundancy have been suggested for fault diagnosis purposes. While research on analytical redundancy has obtained desirable results, a design methodology involving requirements specification and feasibility analysis of analytical redundancy based fault tolerant flight control systems is missing. The main objective of this research work is to describe within a formal framework the implications of adopting analytical redundancy as a basis to achieve fault tolerance. The research activity involves analysis of the analytical redundancy approach, analysis of flight control system informal requirements, and re-engineering (modeling and specification) of the fault tolerance requirements. The USAF military specification MIL-F-9490D and supporting documents are adopted as source for the flight control informal requirements. The De Havilland DHC-2 general aviation aircraft equipped with standard autopilot control functions is adopted as pilot application. Relational algebra is adopted as formal framework for the specification of the requirements. The detailed analysis and formalization of the requirements resulted in a better definition of the fault tolerance problem in the framework of analytical redundancy. Fault tolerance requirements and related

  17. Fault Tolerant Considerations and Methods for Guidance and Control Systems

    DTIC Science & Technology

    1987-07-01

    nations to use their research and development capabilities for the common benefit of the NATO community . The highest authority within AGARD is the...input data. Most of the papers deal with the reliability problem through various approaches . Two papers concern applications directly but all papers...ANALYSIS OF HIGHLY RELIABLE GUIDANCE AND CONTROL COMPUTER SYSTEMS by G.E.Migneault 2 SOME APPROACHES TO THE DESIGN OF HIGH INTEGRITY SOFTWARE by

  18. Adaptive fuzzy fault-tolerant output feedback control of uncertain nonlinear systems with actuator faults

    NASA Astrophysics Data System (ADS)

    Huo, Baoyu; Tong, Shaocheng; Li, Yongming

    2013-12-01

    This article develops an adaptive fuzzy control method for accommodating actuator faults in a class of unknown nonlinear systems with unmeasured states. The considered faults are modelled as both loss of effectiveness and lock-in-place (stuck at unknown place). With the help of fuzzy logic systems to approximate the unknown nonlinear functions, a fuzzy adaptive observer is developed for estimating the unmeasured states. Combining the backstepping technique with the nonlinear tolerant-fault control theory, a novel adaptive fuzzy faults-tolerant control approach is constructed. It is proved that the proposed control approach can guarantee that all the signals of the resulting closed-loop system are bounded and the tracking error between the system output and the reference signal converges to a small neighbourhood of zero by appropriate choice of the design parameters. Simulation results are provided to show the effectiveness of the control approach.

  19. Actuator fault tolerant multi-controller scheme using set separation based diagnosis

    NASA Astrophysics Data System (ADS)

    Seron, María M.; De Doná, José A.

    2010-11-01

    We present a fault tolerant control strategy based on a new principle for actuator fault diagnosis. The scheme employs a standard bank of observers which match the different fault situations that can occur in the plant. Each of these observers has an associated estimation error with distinctive dynamics when an estimator matches the current fault situation of the plant. Based on the information from each observer, a fault detection and isolation (FDI) module is able to reconfigure the control loop by selecting the appropriate control law from a bank of controllers, each of them designed to stabilise and achieve reference tracking for one of the given fault models. The main contribution of this article is to propose a new FDI principle which exploits the separation of sets that characterise healthy system operation from sets that characterise transitions from healthy to faulty behaviour. The new principle allows to provide pre-checkable conditions for guaranteed fault tolerance of the overall multi-controller scheme.

  20. Zero Tolerance for Marginal Populations: Examining Neoliberal Social Controls in American Schools

    ERIC Educational Resources Information Center

    Sellers, Brian G.

    2013-01-01

    This study's purpose is to investigate the expansion of social control efforts in American elementary and secondary school settings, particularly the use of zero-tolerance policies. These policies entail automatic punishments, such as suspensions, expulsions, and referrals to the juvenile and criminal justice systems for a host of school-based…

  1. Cost and benefits design optimization model for fault tolerant flight control systems

    NASA Technical Reports Server (NTRS)

    Rose, J.

    1982-01-01

    Requirements and specifications for a method of optimizing the design of fault-tolerant flight control systems are provided. Algorithms that could be used for developing new and modifying existing computer programs are also provided, with recommendations for follow-on work.

  2. Sliding mode based fault detection, reconstruction and fault tolerant control scheme for motor systems.

    PubMed

    Mekki, Hemza; Benzineb, Omar; Boukhetala, Djamel; Tadjine, Mohamed; Benbouzid, Mohamed

    2015-07-01

    The fault-tolerant control problem belongs to the domain of complex control systems in which inter-control-disciplinary information and expertise are required. This paper proposes an improved faults detection, reconstruction and fault-tolerant control (FTC) scheme for motor systems (MS) with typical faults. For this purpose, a sliding mode controller (SMC) with an integral sliding surface is adopted. This controller can make the output of system to track the desired position reference signal in finite-time and obtain a better dynamic response and anti-disturbance performance. But this controller cannot deal directly with total system failures. However an appropriate combination of the adopted SMC and sliding mode observer (SMO), later it is designed to on-line detect and reconstruct the faults and also to give a sensorless control strategy which can achieve tolerance to a wide class of total additive failures. The closed-loop stability is proved, using the Lyapunov stability theory. Simulation results in healthy and faulty conditions confirm the reliability of the suggested framework.

  3. Sliding mode fault detection and fault-tolerant control of smart dampers in semi-active control of building structures

    NASA Astrophysics Data System (ADS)

    Yeganeh Fallah, Arash; Taghikhany, Touraj

    2015-12-01

    Recent decades have witnessed much interest in the application of active and semi-active control strategies for seismic protection of civil infrastructures. However, the reliability of these systems is still in doubt as there remains the possibility of malfunctioning of their critical components (i.e. actuators and sensors) during an earthquake. This paper focuses on the application of the sliding mode method due to the inherent robustness of its fault detection observer and fault-tolerant control. The robust sliding mode observer estimates the state of the system and reconstructs the actuators’ faults which are used for calculating a fault distribution matrix. Then the fault-tolerant sliding mode controller reconfigures itself by the fault distribution matrix and accommodates the fault effect on the system. Numerical simulation of a three-story structure with magneto-rheological dampers demonstrates the effectiveness of the proposed fault-tolerant control system. It was shown that the fault-tolerant control system maintains the performance of the structure at an acceptable level in the post-fault case.

  4. The SIFT computer and its development. [Software Implemented Fault Tolerance for aircraft control

    NASA Technical Reports Server (NTRS)

    Goldberg, J.

    1981-01-01

    Software Implemented Fault Tolerance (SIFT) is an aircraft control computer designed to allow failure probability of less than 10 to the -10th/hour. The system is based on advanced fault-tolerance computing and validation methodology. Since confirmation of reliability by observation is essentially impossible, system reliability is estimated by a Markov model. A mathematical proof is used to justify the validity of the Markov model. System design is represented by a hierarchy of abstract models, and the design proof comprises mathematical proofs that each model is, in fact, an elaboration of the next more abstract model.

  5. Aluminum Hydroxide

    MedlinePlus

    Aluminum hydroxide is used for the relief of heartburn, sour stomach, and peptic ulcer pain and to ... Aluminum hydroxide comes as a capsule, a tablet, and an oral liquid and suspension. The dose and ...

  6. Distributed Fault-Tolerant Control of Networked Uncertain Euler-Lagrange Systems Under Actuator Faults.

    PubMed

    Chen, Gang; Song, Yongduan; Lewis, Frank L

    2016-05-03

    This paper investigates the distributed fault-tolerant control problem of networked Euler-Lagrange systems with actuator and communication link faults. An adaptive fault-tolerant cooperative control scheme is proposed to achieve the coordinated tracking control of networked uncertain Lagrange systems on a general directed communication topology, which contains a spanning tree with the root node being the active target system. The proposed algorithm is capable of compensating for the actuator bias fault, the partial loss of effectiveness actuation fault, the communication link fault, the model uncertainty, and the external disturbance simultaneously. The control scheme does not use any fault detection and isolation mechanism to detect, separate, and identify the actuator faults online, which largely reduces the online computation and expedites the responsiveness of the controller. To validate the effectiveness of the proposed method, a test-bed of multiple robot-arm cooperative control system is developed for real-time verification. Experiments on the networked robot-arms are conduced and the results confirm the benefits and the effectiveness of the proposed distributed fault-tolerant control algorithms.

  7. Enhancing radiation tolerance by controlling defect mobility and migration pathways in multicomponent single-phase alloys

    NASA Astrophysics Data System (ADS)

    Lu, Chenyang; Niu, Liangliang; Chen, Nanjun; Jin, Ke; Yang, Taini; Xiu, Pengyuan; Zhang, Yanwen; Gao, Fei; Bei, Hongbin; Shi, Shi; He, Mo-Rigen; Robertson, Ian M.; Weber, William J.; Wang, Lumin

    2016-12-01

    A grand challenge in material science is to understand the correlation between intrinsic properties and defect dynamics. Radiation tolerant materials are in great demand for safe operation and advancement of nuclear and aerospace systems. Unlike traditional approaches that rely on microstructural and nanoscale features to mitigate radiation damage, this study demonstrates enhancement of radiation tolerance with the suppression of void formation by two orders magnitude at elevated temperatures in equiatomic single-phase concentrated solid solution alloys, and more importantly, reveals its controlling mechanism through a detailed analysis of the depth distribution of defect clusters and an atomistic computer simulation. The enhanced swelling resistance is attributed to the tailored interstitial defect cluster motion in the alloys from a long-range one-dimensional mode to a short-range three-dimensional mode, which leads to enhanced point defect recombination. The results suggest design criteria for next generation radiation tolerant structural alloys.

  8. Enhancing radiation tolerance by controlling defect mobility and migration pathways in multicomponent single-phase alloys

    PubMed Central

    Lu, Chenyang; Niu, Liangliang; Chen, Nanjun; Jin, Ke; Yang, Taini; Xiu, Pengyuan; Zhang, Yanwen; Gao, Fei; Bei, Hongbin; Shi, Shi; He, Mo-Rigen; Robertson, Ian M.; Weber, William J.; Wang, Lumin

    2016-01-01

    A grand challenge in material science is to understand the correlation between intrinsic properties and defect dynamics. Radiation tolerant materials are in great demand for safe operation and advancement of nuclear and aerospace systems. Unlike traditional approaches that rely on microstructural and nanoscale features to mitigate radiation damage, this study demonstrates enhancement of radiation tolerance with the suppression of void formation by two orders magnitude at elevated temperatures in equiatomic single-phase concentrated solid solution alloys, and more importantly, reveals its controlling mechanism through a detailed analysis of the depth distribution of defect clusters and an atomistic computer simulation. The enhanced swelling resistance is attributed to the tailored interstitial defect cluster motion in the alloys from a long-range one-dimensional mode to a short-range three-dimensional mode, which leads to enhanced point defect recombination. The results suggest design criteria for next generation radiation tolerant structural alloys. PMID:27976669

  9. Enhancing radiation tolerance by controlling defect mobility and migration pathways in multicomponent single-phase alloys

    DOE PAGES

    Lu, Chenyang; Niu, Liangliang; Chen, Nanjun; ...

    2016-12-15

    A grand challenge in material science is to understand the correlation between intrinsic properties and defect dynamics. Radiation tolerant materials are in great demand for safe operation and advancement of nuclear and aerospace systems. Unlike traditional approaches that rely on microstructural and nanoscale features to mitigate radiation damage, this study demonstrates enhancement of radiation tolerance with the suppression of void formation by two orders magnitude at elevated temperatures in equiatomic single-phase concentrated solid solution alloys, and more importantly, reveals its controlling mechanism through a detailed analysis of the depth distribution of defect clusters and an atomistic computer simulation. The enhancedmore » swelling resistance is attributed to the tailored interstitial defect cluster motion in the alloys from a long-range one-dimensional mode to a short-range three-dimensional mode, which leads to enhanced point defect recombination. Finally, the results suggest design criteria for next generation radiation tolerant structural alloys.« less

  10. Enhancing radiation tolerance by controlling defect mobility and migration pathways in multicomponent single-phase alloys

    SciTech Connect

    Lu, Chenyang; Niu, Liangliang; Chen, Nanjun; Jin, Ke; Yang, Taini; Xiu, Pengyuan; Zhang, Yanwen; Gao, Fei; Bei, Hongbin; Shi, Shi; He, Mo-Rigen; Robertson, Ian M.; Weber, William J.; Wang, Lumin

    2016-12-15

    A grand challenge in material science is to understand the correlation between intrinsic properties and defect dynamics. Radiation tolerant materials are in great demand for safe operation and advancement of nuclear and aerospace systems. Unlike traditional approaches that rely on microstructural and nanoscale features to mitigate radiation damage, this study demonstrates enhancement of radiation tolerance with the suppression of void formation by two orders magnitude at elevated temperatures in equiatomic single-phase concentrated solid solution alloys, and more importantly, reveals its controlling mechanism through a detailed analysis of the depth distribution of defect clusters and an atomistic computer simulation. The enhanced swelling resistance is attributed to the tailored interstitial defect cluster motion in the alloys from a long-range one-dimensional mode to a short-range three-dimensional mode, which leads to enhanced point defect recombination. Finally, the results suggest design criteria for next generation radiation tolerant structural alloys.

  11. Control of Pratylenchus brachyurus with Selected Nonfumigant Nematicides on a Tolerant and a Sensitive Soybean Cultivar.

    PubMed

    Koenning, S R; Schmitt, D P

    1987-10-01

    A field study was conducted to evaluate soybean cultivar sensitivity to Pratylenchus brachyurus and selected nonfumigant nematicides for control of this nematode. 'Essex', a tolerant cultivar, yielded more than 'Forrest' , a sensitive cultivar, in an infested field. Plots treated with aldicarb, carbofuran, and fenamiphos had fewer nematodes 40 days after planting than nontreated plots. Plots planted with Forrest and treated with carbofuran had a greater yield than the untreated controls.

  12. Slow breathing as a means to improve orthostatic tolerance: a randomized sham-controlled trial.

    PubMed

    Lucas, Samuel J E; Lewis, Nia C S; Sikken, Elisabeth L G; Thomas, Kate N; Ainslie, Philip N

    2013-07-15

    Endogenous oscillations in blood pressure (BP) and cerebral blood flow have been associated with improved orthostatic tolerance. Although slow breathing induces such responses, it has not been tested as a therapeutic strategy to improve orthostatic tolerance. With the use of a randomized, crossover sham-controlled design, we tested the hypothesis that breathing at six breaths/min (vs. spontaneous breathing) would improve orthostatic tolerance via inducing oscillations in mean arterial BP (MAP) and cerebral blood flow. Sixteen healthy participants (aged 25 ± 4 yr; mean ± SD) had continuous beat-to-beat measurements of middle cerebral artery blood velocity (MCAv), BP (finometer), heart rate (ECG), and end-tidal carbon dioxide partial pressure during an incremental orthostatic stress test to presyncope by combining head-up tilt with incremental lower-body negative pressure. Tolerance time to presyncope was improved (+15%) with slow breathing compared with spontaneous breathing (29.2 ± 5.4 vs. 33.7 ± 6.0 min; P < 0.01). The improved tolerance was reflected in elevations in low-frequency (LF; 0.07-0.2 Hz) oscillations of MAP and mean MCAv, improved metrics of dynamic cerebrovascular control (increased LF phase and reduced LF gain), and a reduced rate of decline for MCAv (-0.60 ± 0.27 vs. -0.99 ± 0.51 cm·s(-1)·min(-1); P < 0.01) and MAP (-0.50 ± 0.37 vs. -1.03 ± 0.80 mmHg/min; P = 0.01 vs. spontaneous breathing) across time from baseline to presyncope. Our findings show that orthostatic tolerance can be improved within healthy individuals with a simple, nonpharmacological breathing strategy. The mechanisms underlying this improvement are likely mediated via the generation of negative intrathoracic pressure during slow and deep breathing and the related beneficial impact on cerebrovascular and autonomic function.

  13. A multi-layer robust adaptive fault tolerant control system for high performance aircraft

    NASA Astrophysics Data System (ADS)

    Huo, Ying

    Modern high-performance aircraft demand advanced fault-tolerant flight control strategies. Not only the control effector failures, but the aerodynamic type failures like wing-body damages often result in substantially deteriorate performance because of low available redundancy. As a result the remaining control actuators may yield substantially lower maneuvering capabilities which do not authorize the accomplishment of the air-craft's original specified mission. The problem is to solve the control reconfiguration on available control redundancies when the mission modification is urged to save the aircraft. The proposed robust adaptive fault-tolerant control (RAFTC) system consists of a multi-layer reconfigurable flight controller architecture. It contains three layers accounting for different types and levels of failures including sensor, actuator, and fuselage damages. In case of the nominal operation with possible minor failure(s) a standard adaptive controller stands to achieve the control allocation. This is referred to as the first layer, the controller layer. The performance adjustment is accounted for in the second layer, the reference layer, whose role is to adjust the reference model in the controller design with a degraded transit performance. The upmost mission adjust is in the third layer, the mission layer, when the original mission is not feasible with greatly restricted control capabilities. The modified mission is achieved through the optimization of the command signal which guarantees the boundedness of the closed-loop signals. The main distinguishing feature of this layer is the the mission decision property based on the current available resources. The contribution of the research is the multi-layer fault-tolerant architecture that can address the complete failure scenarios and their accommodations in realities. Moreover, the emphasis is on the mission design capabilities which may guarantee the stability of the aircraft with restricted post

  14. Novel properties of the wheat aluminum tolerance organic acid transporter (TaALMT1) revealed by electrophysiological characterization in Xenopus oocytes: Functional and structural implications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many plant species avoid the phytotoxic effects of aluminum (Al) by exuding organic acid anions which chelate Al3+ and prevent its entry into the root. Several novel genes that encode membrane transporters from the ALMT and MATE families have recently been cloned and implicated in mediating the orga...

  15. Corrosion and corrosion control of aluminum and steel in lightweight automotive applications

    SciTech Connect

    Simpson, T.C.; Moran, J.P.; Soepenberg, E.N.

    1995-12-31

    This book features 23 papers presented at the Corrosion/95 symposium, Corrosion of Light-Weight and Precoated Metals for Automotive Applications, and selected Corrosion/93 papers. It is one of the first symposia covering both lightweight and durability effects for steel and aluminum in automotive body construction. Topics include conversion coatings, laboratory and field testing, novel applications, and the study of automotive corrosion mechanisms.

  16. Manufacturing process controls for high reliability carbon filament-wound seamless-aluminum-lined composite pressure vessels

    NASA Astrophysics Data System (ADS)

    Braun, C. A.; Haddock, R. C.

    1992-07-01

    An account is given of the manufacturing, inspection, and test-process variables associated with the production of carbon filament-wound/epoxy-matrix, seamless aluminum-lined pressure vessels, which have achieved operating pressures of the order of 10,000 psi and burst-to-operating safety factors of as low as 1.5-1.0. Attention is given to the process controls that are needed to reach current reliability requirements. Attention is given to liner surface preparation, age sensitivity, and the dangers of exposure to heat and stress.

  17. Safety Verification of a Fault Tolerant Reconfigurable Autonomous Goal-Based Robotic Control System

    NASA Technical Reports Server (NTRS)

    Braman, Julia M. B.; Murray, Richard M; Wagner, David A.

    2007-01-01

    Fault tolerance and safety verification of control systems are essential for the success of autonomous robotic systems. A control architecture called Mission Data System (MDS), developed at the Jet Propulsion Laboratory, takes a goal-based control approach. In this paper, a method for converting goal network control programs into linear hybrid systems is developed. The linear hybrid system can then be verified for safety in the presence of failures using existing symbolic model checkers. An example task is simulated in MDS and successfully verified using HyTech, a symbolic model checking software for linear hybrid systems.

  18. Non-Chromate Aluminum Pretreatments, Phase 2

    DTIC Science & Technology

    2004-09-01

    September 2004 78 ALUMINUM AL2024-T3 ALUMINUM AL7075 -T6 PNL ID 4 Control 5...ALUMINUM - AL2024-T3 192 ALUMINUM - AL7075 -T6 112 Table 5.13: AMCOM – NAVAIR PANEL TEST MATRIX OCTOBER 2003 NCAP Phase II Interim Report

  19. A fault-tolerant attitude control system for a satellite based on fuzzy global sliding mode control algorithm

    NASA Astrophysics Data System (ADS)

    Liang, Jinjin; Dong, Chaoyang; Wang, Qing

    2008-10-01

    The structures and missions of modern satellites are very complicated, so the reliability of satellites is becoming increasingly important. This paper proposed a fault-tolerant attitude control system for a satellite based on Fuzzy Global Sliding Mode Control (FGSMC) algorithm. We designed a controller for the nonlinear model of a satellite. By designing a global sliding surface, this controller can ensure that the response of the system has global robustness against the uncertainties of system and external disturbances. In this paper attitude control is performed by four reaction flywheels. The attitude control system distributed the three control torques to the four reaction flywheels according to the distribution matrix. We deduced the formula to calculate the distribution matrix. Paper proved the stability of the designed control law, and simulated the attitude control system. The simulation results show that the attitude control law has high accuracy and robustness.

  20. Double-blind, vehicle-controlled randomized twelve-month neurodevelopmental toxicity study of common aluminum salts in the rat.

    PubMed

    Poirier, J; Semple, H; Davies, J; Lapointe, R; Dziwenka, M; Hiltz, M; Mujibi, D

    2011-10-13

    This good laboratory practice (GLP) study of aluminum salts in Sprague-Dawley rats was conducted according to double-blind, vehicle-controlled randomized design by exposing offspring to aluminum citrate in-utero, through lactation, and then in drinking water post-weaning. Three dose levels were used: 30, 100, 300 mg Al/kg bw/day, in addition to control groups that received either water or a sodium citrate solution (27.2 g/L). Endpoints were assessed in both female and male pups: behavioral (motor activity, T-maze, auditory startle, the Functional Observational Battery (FOB) with domains targeting autonomic function, activity, neuromuscular function, sensimotor function, and physiological function), cognitive function (Morris swim maze), brain weight, clinical chemistry, hematology, tissue/blood levels of aluminum and neuropathology. The most notable treatment-related effect observed in the offspring was renal pathology, most prominently in the male pups. Higher mortality and significant morbidity were observed in the male pups in the high Al-citrate dose group; leading to euthanization of this group at day 89. There was evidence for dose-response relationships between neuromuscular measurements-hind-limb and fore-limb grip strength-and Al-treatment in both males and females, although some of the effects may be secondary to body weight changes. No consistent treatment-related effects were observed in ambulatory counts (motor activity) in the different cohorts. No significant effects were observed for the auditory startle response, T-maze tests (pre-weaning day 23 cohort) or the Morris water maze test (day 120 cohort). None of the lesions seen on histopathological examination of brain tissues of the day 364 group was reported as treatment-related and, as these were also seen in the control group, were likely due to aging. In conclusion, these results indicate that concentrations of aluminum in the drinking water that are required to produce minimally detectable

  1. Backstepping Design of Adaptive Neural Fault-Tolerant Control for MIMO Nonlinear Systems.

    PubMed

    Gao, Hui; Song, Yongduan; Wen, Changyun

    2016-08-24

    In this paper, an adaptive controller is developed for a class of multi-input and multioutput nonlinear systems with neural networks (NNs) used as a modeling tool. It is shown that all the signals in the closed-loop system with the proposed adaptive neural controller are globally uniformly bounded for any external input in L[₀,∞]. In our control design, the upper bound of the NN modeling error and the gains of external disturbance are characterized by unknown upper bounds, which is more rational to establish the stability in the adaptive NN control. Filter-based modification terms are used in the update laws of unknown parameters to improve the transient performance. Finally, fault-tolerant control is developed to accommodate actuator failure. An illustrative example applying the adaptive controller to control a rigid robot arm shows the validation of the proposed controller.

  2. Fault-tolerant control for a class of non-linear systems with dead-zone

    NASA Astrophysics Data System (ADS)

    Chen, Mou; Jiang, Bin; Guo, William W.

    2016-05-01

    In this paper, a fault-tolerant control scheme is proposed for a class of single-input and single-output non-linear systems with the unknown time-varying system fault and the dead-zone. The non-linear state observer is designed for the non-linear system using differential mean value theorem, and the non-linear fault estimator that estimates the unknown time-varying system fault is developed. On the basis of the designed fault estimator, the observer-based fault-tolerant tracking control is then developed using the backstepping technique for non-linear systems with the dead-zone. The stability of the whole closed-loop system is rigorously proved via Lyapunov analysis and the satisfactory tracking control performance is guaranteed in the presence of the unknown time-varying system fault and the dead-zone. Numerical simulation results are presented to illustrate the effectiveness of the proposed backstepping fault-tolerant control scheme for non-linear systems.

  3. Adaptive Fault-Tolerant Control of Uncertain Nonlinear Large-Scale Systems With Unknown Dead Zone.

    PubMed

    Chen, Mou; Tao, Gang

    2016-08-01

    In this paper, an adaptive neural fault-tolerant control scheme is proposed and analyzed for a class of uncertain nonlinear large-scale systems with unknown dead zone and external disturbances. To tackle the unknown nonlinear interaction functions in the large-scale system, the radial basis function neural network (RBFNN) is employed to approximate them. To further handle the unknown approximation errors and the effects of the unknown dead zone and external disturbances, integrated as the compounded disturbances, the corresponding disturbance observers are developed for their estimations. Based on the outputs of the RBFNN and the disturbance observer, the adaptive neural fault-tolerant control scheme is designed for uncertain nonlinear large-scale systems by using a decentralized backstepping technique. The closed-loop stability of the adaptive control system is rigorously proved via Lyapunov analysis and the satisfactory tracking performance is achieved under the integrated effects of unknown dead zone, actuator fault, and unknown external disturbances. Simulation results of a mass-spring-damper system are given to illustrate the effectiveness of the proposed adaptive neural fault-tolerant control scheme for uncertain nonlinear large-scale systems.

  4. Distributed Interplanetary Delay/Disruption Tolerant Network (DTN) Monitor and Control System

    NASA Technical Reports Server (NTRS)

    Wang, Shin-Ywan

    2012-01-01

    The main purpose of Distributed interplanetary Delay Tolerant Network Monitor and Control System as a DTN system network management implementation in JPL is defined to provide methods and tools that can monitor the DTN operation status, detect and resolve DTN operation failures in some automated style while either space network or some heterogeneous network is infused with DTN capability. In this paper, "DTN Monitor and Control system in Deep Space Network (DSN)" exemplifies a case how DTN Monitor and Control system can be adapted into a space network as it is DTN enabled.

  5. Improvement of the liquid segregation phenomena of semisolid aluminum alloys by the multistage strain rate control in the compression test

    NASA Astrophysics Data System (ADS)

    Kang, C. G.; Jung, K. D.

    2001-08-01

    The deformation behavior of semisolid aluminum alloys in the range of solid fraction ( f s ) between 55 and 90% was investigated through compression tests for the variation of strain rate. In order to obtain the optimal conditions of the net shape forging process, the rheological behavior of aluminum alloy in the semisolid state has been examined by using parallel plate compression. The strain rate is the value of the strain rate corresponding to the stress to avoid the liquid segregation phenomena during compression tests. The material constants of semisolid material in the stress-strain curve are proposed to perform the numerical analysis for a die design of semisolid forging. The starting materials used in this experiment are A357, 86S (similar to A319), and A390 alloys, which are fabricated by the electromagnetic stirring process. The intelligent compression test with a controlled strain rate was performed. The liquid segregation in the overall cross-sectional areas is controlled as the multistage variation of the pressing velocity and variation of the solid fraction during the compression process. The characteristics of materials flow between solid and liquid phases, considering the liquid segregation, are discussed for various solid fractions and pressing velocities.

  6. Minimum sliding mode error feedback control for fault tolerant reconfigurable satellite formations with J2 perturbations

    NASA Astrophysics Data System (ADS)

    Cao, Lu; Chen, Xiaoqian; Misra, Arun K.

    2014-03-01

    Minimum Sliding Mode Error Feedback Control (MSMEFC) is proposed to improve the control precision of spacecraft formations based on the conventional sliding mode control theory. This paper proposes a new approach to estimate and offset the system model errors, which include various kinds of uncertainties and disturbances, as well as smoothes out the effect of nonlinear switching control terms. To facilitate the analysis, the concept of equivalent control error is introduced, which is the key to the utilization of MSMEFC. A cost function is formulated on the basis of the principle of minimum sliding mode error; then the equivalent control error is estimated and fed back to the conventional sliding mode control. It is shown that the sliding mode after the MSMEFC will approximate to the ideal sliding mode, resulting in improved control performance and quality. The new methodology is applied to spacecraft formation flying. It guarantees global asymptotic convergence of the relative tracking error in the presence of J2 perturbations. In addition, some fault tolerant situations such as thruster failure for a period of time, thruster degradation and so on, are also considered to verify the effectiveness of MSMEFC. Numerical simulations are performed to demonstrate the efficacy of the proposed methodology to maintain and reconfigure the satellite formation with the existence of initial offsets and J2 perturbation effects, even in the fault-tolerant cases.

  7. A novel mathematical setup for fault tolerant control systems with state-dependent failure process

    NASA Astrophysics Data System (ADS)

    Chitraganti, S.; Aberkane, S.; Aubrun, C.

    2014-12-01

    In this paper, we consider a fault tolerant control system (FTCS) with state- dependent failures and provide a tractable mathematical model to handle the state-dependent failures. By assuming abrupt changes in system parameters, we use a jump process modelling of failure process and the fault detection and isolation (FDI) process. In particular, we assume that the failure rates of the failure process vary according to which set the state of the system belongs to.

  8. Characterization and control of the microbial community affiliated with copper or aluminum heat exchangers of HVAC systems.

    PubMed

    Schmidt, Michael G; Attaway, Hubert H; Terzieva, Silva; Marshall, Anna; Steed, Lisa L; Salzberg, Deborah; Hamoodi, Hameed A; Khan, Jamil A; Feigley, Charles E; Michels, Harold T

    2012-08-01

    Microbial growth in heating ventilation and air-conditioning (HVAC) systems with the subsequent contamination of indoor air is of increasing concern. Microbes and the subsequent biofilms grow easily within heat exchangers. A comparative study where heat exchangers fabricated from antimicrobial copper were evaluated for their ability to limit microbial growth was conducted using a full-scale HVAC system under conditions of normal flow rates using single-pass outside air. Resident bacterial and fungal populations were quantitatively assessed by removing triplicate sets of coupons from each exchanger commencing the fourth week after their installation for the next 30 weeks. The intrinsic biofilm associated with each coupon was extracted and characterized using selective and differential media. The predominant organisms isolated from aluminum exchangers were species of Methylobacterium of which at least three colony morphologies and 11 distinct PFGE patterns we found; of the few bacteria isolated from the copper exchangers, the majority were species of Bacillus. The concentrations and type of bacteria recovered from the control, aluminum, exchangers were found to be dependent on the type of plating media used and were 11,411-47,257 CFU cm(-2) per coupon surface. The concentration of fungi was found to average 378 CFU cm(-2). Significantly lower concentrations of bacteria, 3 CFU cm(-2), and fungi, 1 CFU cm(-2), were recovered from copper exchangers regardless of the plating media used. Commonly used aluminum heat exchangers developed stable, mixed, bacterial/fungal biofilms in excess of 47,000 organisms per cm(2) within 4 weeks of operation, whereas the antimicrobial properties of metallic copper were able to limit the microbial load affiliated with the copper heat exchangers to levels 99.97 % lower during the same time period.

  9. Reconfigurable fault-tolerant multiprocessor system for real-time control

    SciTech Connect

    Kao, M.L.

    1986-01-01

    Real-time control applications place stringent constraints in computers controlling them since the failure of a computer could result in costly damages and even loss of human lives. Fault-tolerant computers, therefore, have been always in high demand in critical avionic and aerospace applications. However, the use of redundancy techniques to achieve fault tolerance in industrial applications has only recently become feasible due to the rapid decrease in cost and increase in performance of microprocessors. As more and more robots are being built to replace human beings in dangerous and difficult tasks, the need for a reliable computer for robotics control increases. This need, in particular, motivated the research described in this dissertation - the design and implementation of a reconfigurable fault-tolerant multiprocessor system (the FREMP system). The FREMP system consists of four processing units (PUs) and three common parallel buses. Each PU is a combination of an Intel 86/30 single board computer and a custom fault detection/masking circuit board (FDM board). A hardware/software combined scheme was devised to detect faults and correct errors. This scheme has shown to be more efficient than software voting while maintaining the flexibility of software approaches. Time-frame scheduling was adopted to schedule tasks for execution.

  10. A robust adaptive nonlinear fault-tolerant controller via norm estimation for reusable launch vehicles

    NASA Astrophysics Data System (ADS)

    Hu, Chaofang; Gao, Zhifei; Ren, Yanli; Liu, Yunbing

    2016-11-01

    In this paper, a reusable launch vehicle (RLV) attitude control problem with actuator faults is addressed via the robust adaptive nonlinear fault-tolerant control (FTC) with norm estimation. Firstly, the accurate tracking task of attitude angles in the presence of parameter uncertainties and external disturbances is considered. A fault-free controller is proposed using dynamic surface control (DSC) combined with fuzzy adaptive approach. Furthermore, the minimal learning parameter strategy via norm estimation technique is introduced to reduce the multi-parameter adaptive computation burden of fuzzy approximation of the lump uncertainties. Secondly, a compensation controller is designed to handle the partial loss fault of actuator effectiveness. The unknown maximum eigenvalue of actuator efficiency loss factors is estimated online. Moreover, stability analysis guarantees that all signals of the closed-loop control system are semi-global uniformly ultimately bounded. Finally, illustrative simulations show the effectiveness of the proposed method.

  11. Improvements in springback control by external force laser-assisted sheet bending of titanium and aluminum alloys

    NASA Astrophysics Data System (ADS)

    Gisario, A.; Barletta, M.; Venettacci, S.

    2016-12-01

    The present investigation deals with an external-force laser assisted bending process of Grade 2 CP titanium and AA 7075 T6 aluminum sheets. High bending angles, sharp fillet radii and control of springback were achieved by tuning the contact pressure of a hydraulically driven tool with the local and selective heating of the bending zone by irradiation with a high power diode laser. First, the role of laser operational parameters, namely power, scanning speed and number of passes, in metal bending was investigated, allowing to identify the most suitable processing window. Second, a custom-built equipment to measure the bending angle during the forming process, together with the metal temperature, was implemented. Real-time monitoring of the bending angle and temperature allowed to evaluate the continuous evolution of the geometry of the metal substrates during the external force laser-assisted bending process. Experimental results showed both metal sheets could be bent to high angles with very low fillet radii by the appropriate combination of the tooling contact pressure and selective laser heating of the bending zone. Laser heating also reduces the risk of rupture in both metals during bending at high angles, limits the springback extent up to 10 times on titanium and 30 times on aluminum in comparison with conventional bending process and does not affect significantly the visual appearance of the bending zone.

  12. ALLIANCE: An architecture for fault tolerant, cooperative control of heterogeneous mobile robots

    SciTech Connect

    Parker, L.E.

    1995-02-01

    This research addresses the problem of achieving fault tolerant cooperation within small- to medium-sized teams of heterogeneous mobile robots. The author describes a novel behavior-based, fully distributed architecture, called ALLIANCE, that utilizes adaptive action selection to achieve fault tolerant cooperative control in robot missions involving loosely coupled, largely independent tasks. The robots in this architecture possess a variety of high-level functions that they can perform during a mission, and must at all times select an appropriate action based on the requirements of the mission, the activities of other robots, the current environmental conditions, and their own internal states. Since such cooperative teams often work in dynamic and unpredictable environments, the software architecture allows the team members to respond robustly and reliably to unexpected environmental changes and modifications in the robot team that may occur due to mechanical failure, the learning of new skills, or the addition or removal of robots from the team by human intervention. After presenting ALLIANCE, the author describes in detail experimental results of an implementation of this architecture on a team of physical mobile robots performing a cooperative box pushing demonstration. These experiments illustrate the ability of ALLIANCE to achieve adaptive, fault-tolerant cooperative control amidst dynamic changes in the capabilities of the robot team.

  13. RAMP: A fault tolerant distributed microcomputer structure for aircraft navigation and control

    NASA Technical Reports Server (NTRS)

    Dunn, W. R.

    1980-01-01

    RAMP consists of distributed sets of parallel computers partioned on the basis of software and packaging constraints. To minimize hardware and software complexity, the processors operate asynchronously. It was shown that through the design of asymptotically stable control laws, data errors due to the asynchronism were minimized. It was further shown that by designing control laws with this property and making minor hardware modifications to the RAMP modules, the system became inherently tolerant to intermittent faults. A laboratory version of RAMP was constructed and is described in the paper along with the experimental results.

  14. Fault tolerant control for switching discrete-time systems with delays: an improved cone complementarity approach

    NASA Astrophysics Data System (ADS)

    Benzaouia, Abdellah; Ouladsine, Mustapha; Ananou, Bouchra

    2014-10-01

    In this paper, fault tolerant control problem for discrete-time switching systems with delay is studied. Sufficient conditions of building an observer are obtained by using multiple Lyapunov function. These conditions are worked out in a new way, using cone complementarity technique, to obtain new LMIs with slack variables and multiple weighted residual matrices. The obtained results are applied on a numerical example showing fault detection, localisation of fault and reconfiguration of the control to maintain asymptotic stability even in the presence of a permanent sensor fault.

  15. A hybrid robust fault tolerant control based on adaptive joint unscented Kalman filter.

    PubMed

    Shabbouei Hagh, Yashar; Mohammadi Asl, Reza; Cocquempot, Vincent

    2017-01-01

    In this paper, a new hybrid robust fault tolerant control scheme is proposed. A robust H∞ control law is used in non-faulty situation, while a Non-Singular Terminal Sliding Mode (NTSM) controller is activated as soon as an actuator fault is detected. Since a linear robust controller is designed, the system is first linearized through the feedback linearization method. To switch from one controller to the other, a fuzzy based switching system is used. An Adaptive Joint Unscented Kalman Filter (AJUKF) is used for fault detection and diagnosis. The proposed method is based on the simultaneous estimation of the system states and parameters. In order to show the efficiency of the proposed scheme, a simulated 3-DOF robotic manipulator is used.

  16. Controlled-strain rate tests at very low strain rates of 2618 aluminum at 200 C

    NASA Technical Reports Server (NTRS)

    Ding, J. L.; Lee, S. R.

    1988-01-01

    Constant strain rate tests and constant load creep tests were performed on 2618 aluminum at 200 C. The strain rates used in the constant strain rate tests were 10 to the minus 6, 10 to the minus 7, 10 to the minum 8, and 10 to the minus 9/sec. Due to the fact that the strain rates in both tests were comparable to each other, the similarities between them can therefore be studied. It was concluded that metals are essentially rate sensitive at elevated temperatures. The traditional definition of creep and plasticity used in the classical creep analysis is actually a reflection of the material behavior under different loading conditions. A constitutive equation based on the test data under one loading condition should work well for other loading conditions as long as the strain rates are in the same range as those under which the material constants are determined.

  17. Controlled Release from Core-Shell Nanoporous Silica Particles for Corrosion Inhibition of Aluminum Alloys

    DOE PAGES

    Jiang, Xingmao; Jiang, Ying-Bing; Liu, Nanguo; ...

    2011-01-01

    Ceriumore » m (Ce) corrosion inhibitors were encapsulated into hexagonally ordered nanoporous silica particles via single-step aerosol-assisted self-assembly. The core/shell structured particles are effective for corrosion inhibition of aluminum alloy AA2024-T3. Numerical simulation proved that the core-shell nanostructure delays the release process. The effective diffusion coefficient elucidated from release data for monodisperse particles in water was 1.0 × 10 − 14  m 2 s for Ce 3+ compared to 2.5 × 10 − 13  m 2 s for NaCl. The pore size, pore surface chemistry, and the inhibitor solubility are crucial factors for the application. Microporous hydrophobic particles encapsulating a less soluble corrosion inhibitor are desirable for long-term corrosion inhibition.« less

  18. An S-adenosyl Methionine Synthetase (SAMS) Gene from Andropogon virginicus L. Confers Aluminum Stress Tolerance and Facilitates Epigenetic Gene Regulation in Arabidopsis thaliana

    PubMed Central

    Ezaki, Bunichi; Higashi, Aiko; Nanba, Norie; Nishiuchi, Takumi

    2016-01-01

    Candidate clones which conferred Al tolerance to yeast transformants (TFs) were obtained from a cDNA library derived from a highly Al-tolerant poaceae, Andropogon virginicus L. One such clone, AL3A-4, encoded an S-adenosyl methionine synthetase (SAMS) gene. A full-length cDNA was obtained by 5′-RACE, designated AvSAMS1, and introduced into Arabidopsis thaliana to investigate its biological functions under Al stress. Two TF plant lines both showed higher tolerance than the Col-0 ecotype (non-TF) not only for Al stress, but also for Cu, Pb, Zn and diamide stresses, suggesting the AvSAMS1 was a multiple tolerance gene. More than 40 of A. thaliana Al response-genes (Al induced genes and Al repressed genes) were selected from microarray results and then used for investigations of DNA or histone methylation status under Al stress in Col-0 and the AvSAMS1 TF line. The results indicated that Al stress caused alterations of methylation status in both DNA and histone H3 (H3K4me3 and H3K9me3) and that these alterations were different between the AvSAMS1 TF and Col-0, suggesting the differences were AvSAMS1-gene dependent. These results suggested the existence of AvSAMS1-related epigenetic gene-regulation under Al stress. PMID:27877178

  19. Fault tolerant formation control of nonholonomic mobile robots using online approximators

    NASA Astrophysics Data System (ADS)

    Thumati, Balaje T.; Dierks, Travis A.; Jagannathan, S.

    2010-04-01

    For unmanned systems, it is desirable to have some sort of fault tolerant ability in order to accomplish the mission. Therefore, in this paper, the fault tolerant control of a formation of nonholonomic mobile robots in the presence unknown faults is undertaken. Initially, a kinematic/torque leader-follower formation control law is developed for the robots under the assumption of normal operation, and the stability of the formation is verified using Lyapunov theory. Subsequently, the control law for the formation is modified by incorporating an additional term, and this new control law compensates the effects of the faults. Moreover, the faults could be incipient or abrupt in nature. The additional term used in the modified control law is a function of the unknown fault dynamics which are recovered using the online learning capabilities of online approximators. Additionally, asymptotic convergence of the FDA scheme and the formation errors in the presence of faults is shown using Lyapunov theory. Finally, numerical results are provided to verify the theoretical conjectures.

  20. Finite Element Analysis and Die Design of Non-specific Engineering Structure of Aluminum Alloy during Extrusion

    SciTech Connect

    Chen, D.-C.; Lu, Y.-Y.

    2010-06-15

    Aluminum extension applies to industrial structure, light load, framework rolls and conveyer system platform. Many factors must be controlled in processing the non-specific engineering structure (hollow shape) of the aluminum alloy during extrusion, to obtain the required plastic strain and desired tolerance values. The major factors include the forming angle of the die and temperature of billet and various materials. This paper employs rigid-plastic finite element (FE) DEFORM 3D software to investigate the plastic deformation behavior of an aluminum alloy (A6061, A5052, A3003) workpiece during extrusion for the engineering structure of the aluminum alloy. This work analyzes effective strain, effective stress, damage and die radius load distribution of the billet under various conditions. The analytical results confirm the suitability of the current finite element software for the non-specific engineering structure of aluminum alloy extrusion.

  1. 21 CFR 582.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Aluminum calcium silicate. 582.2122 Section 582.2122 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2 percent....

  2. 21 CFR 182.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Aluminum calcium silicate. 182.2122 Section 182...) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Anticaking Agents § 182.2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2 percent. (c) Limitations, restrictions, or explanation....

  3. 21 CFR 582.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Aluminum calcium silicate. 582.2122 Section 582.2122 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2 percent....

  4. 21 CFR 582.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Aluminum calcium silicate. 582.2122 Section 582.2122 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2 percent....

  5. 21 CFR 182.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Aluminum calcium silicate. 182.2122 Section 182.2122 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2 percent....

  6. 21 CFR 582.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Aluminum calcium silicate. 582.2122 Section 582.2122 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2 percent....

  7. 21 CFR 182.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Aluminum calcium silicate. 182.2122 Section 182.2122 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2 percent....

  8. 21 CFR 582.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Aluminum calcium silicate. 582.2122 Section 582.2122 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2 percent....

  9. 21 CFR 182.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Aluminum calcium silicate. 182.2122 Section 182.2122 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2 percent....

  10. 21 CFR 182.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Aluminum calcium silicate. 182.2122 Section 182.2122 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2 percent....

  11. Mechanisms Controlling Species Responses to Climate Change: Thermal Tolerances and Shifting Range Limits. (Invited)

    NASA Astrophysics Data System (ADS)

    Sage, R. F.; Bykova, O.; Coiner, H.

    2010-12-01

    One of the main effects of anthropogenic climate change will be widespread shifts in species distribution, with the common assumption that they will migrate to higher elevation and latitude. While this assumption is supported by migration patterns following climate warming in the past 20,000 years, it has not been rigorously evaluated in terms of physiological mechanism, despite the implication that migration in response to climate warming is controlled by some form of thermal adaptation. We have been evaluating the degree to which species range limits are controlled by physiological patterns of thermal tolerance in bioinvaders of North America. Bioinvaders presumably have few biotic controls over their distribution and thus are more likely to fully exploit their thermal niche. In cheatgrass (Bromus tectorum), the minimum lethal temperature in winter is -32C, which corresponds to the mean winter minimum temperature at its northern range limit. In red brome (Bromus rubens), the minimum lethal temperature is also near -32C, which is well below the minimum winter temperature near -20C that corresponds to its northern distribution limit. In kudzu (Pueraria lobata), the minimum lethal temperature is near -20C, which corresponds to the midwinter minimum at its northern distribution limit; however, overwintering kudzu tissues are insulated by soil and snow cover, and thus do not experience lethal temperatures at kudzu's northern range limit. These results demonstrate that some invasive species can exploit the potential range defined by their low temperature tolerance and thus can be predicted by mechanistic models to migrate to higher latitudes with moderation of winter cold. The distribution of other invaders such as kudzu and red brome are not controlled by tolerance of midwinter cold. Developing mechanistic models of their distributions, and how these might change with climate warming, will require extensive physiological study.

  12. Optimised configuration of sensors for fault tolerant control of an electro-magnetic suspension system

    NASA Astrophysics Data System (ADS)

    Michail, K.; Zolotas, A. C.; Goodall, R. M.; Whidborne, J. F.

    2012-10-01

    For any given system the number and location of sensors can affect the closed-loop performance as well as the reliability of the system. Hence, one problem in control system design is the selection of the sensors in some optimum sense that considers both the system performance and reliability. Although some methods have been proposed that deal with some of the aforementioned aspects, in this work, a design framework dealing with both control and reliability aspects is presented. The proposed framework is able to identify the best sensor set for which optimum performance is achieved even under single or multiple sensor failures with minimum sensor redundancy. The proposed systematic framework combines linear quadratic Gaussian control, fault tolerant control and multiobjective optimisation. The efficacy of the proposed framework is shown via appropriate simulations on an electro-magnetic suspension system.

  13. Design and verification of a multiple fault tolerant control system for STS applications using computer simulation

    NASA Technical Reports Server (NTRS)

    Szatkowski, G. P.; Karas, J. C.

    1981-01-01

    General Dynamics/Convair is under NASA contract to integrate the Centaur upper stage into the space transportation system for future planetary missions. This requires that control of all safety critical functions be two-failure tolerant. The control system developed consists of five asynchronous computers, each contributing at their outputs to a 3-out-of-5 voting plane. Subsystem control is based on an end function redundancy management scheme. Analysis of multiple component failures and worst-case time-phase asynchrony among the computers is performed by a real-time computer simulation. The simulation emulates the hardware and subsystem interfaces, wire by wire, providing assessibility to any component for the insertion of preprogrammed failures. Observability is provided via a graphics system and diagnostic software. The simulation provides an engineering tool where the integrity of control system hardware and imbedded software can be demonstrated.

  14. Controlled polarity of sputter-deposited aluminum nitride on metals observed by aberration corrected scanning transmission electron microscopy

    SciTech Connect

    Harumoto, T.; Sannomiya, T.; Matsukawa, Y.; Muraishi, S.; Shi, J.; Nakamura, Y.; Sawada, H.; Tanaka, T.; Tanishiro, Y.; Takayanagi, K.

    2013-02-28

    The polarity determination process of sputter-deposited aluminum nitride (AlN) on metals has been analyzed using aberration corrected atomic resolution scanning transmission electron microscope. Direct growth of c-axis orientated AlN on face centered cubic metals (fcc) (111) with the local epitaxy has been observed, and the polarity was determined at the AlN/metal interface. We found that the AlN polarity can be controlled by the base metal layer: N-polarity AlN grows on Pt(111) while Al-polarity AlN forms on Al(111). Based on these results, the growth mechanism of AlN on metals is discussed.

  15. Evaluation of availability of cluster distributed disaster tolerant systems for control and information processing based on a cluster quorum

    NASA Astrophysics Data System (ADS)

    Tsarev, R. Yu; Gruzenkin, D. V.; Kovalev, I. V.; Prokopenko, A. V.; Knyazkov, A. N.

    2016-11-01

    Control and information processing systems, which often executes critical functions, must satisfy requirements not only of fault tolerance, but also of disaster tolerance. Cluster architecture is reasonable to be applied to provide disaster tolerance of these systems. In this case clusters are separate control and information processing centers united by means of communication channels. Thus, clusters are a single hardware resource interacting with each other to achieve system objectives. Remote cluster positioning allows ensuring system availability and disaster tolerance even in case of some units’ failures or a whole cluster crash. A technique for evaluation of availability of cluster distributed systems for control and information processing based on a cluster quorum is presented in the paper. This technique can be applied to different cluster distributed control and information processing systems, claimed to be based on the disaster tolerance principles. In the article we discuss a communications satellite system as an example of a cluster distributed disaster tolerant control and information processing system. Evaluation of availability of the communications satellite system is provided. Possible scenarios of communications satellite system cluster-based components failures were analyzed. The analysis made it possible to choose the best way to implement the cluster structure for a distributed control and information processing system.

  16. Fault-tolerant control of electric vehicles with in-wheel motors using actuator-grouping sliding mode controllers

    NASA Astrophysics Data System (ADS)

    Li, Boyuan; Du, Haiping; Li, Weihua

    2016-05-01

    Although electric vehicles with in-wheel motors have been regarded as one of the promising vehicle architectures in recent years, the probability of in-wheel motor fault is still a crucial issue due to the system complexity and large number of control actuators. In this study, a modified sliding mode control (SMC) is applied to achieve fault-tolerant control of electric vehicles with four-wheel-independent-steering (4WIS) and four-wheel-independent-driving (4WID). Unlike in traditional SMC, in this approach the steering geometry is re-arranged according to the location of faulty wheels in the modified SMC. Three SMC control laws for longitudinal velocity control, lateral velocity control and yaw rate control are designed based on specific vehicle motion scenarios. In addition the actuator-grouping SMC method is proposed so that driving actuators are grouped and each group of actuators can be used to achieve the specific control target, which avoids the strong coupling effect between each control target. Simulation results prove that the proposed modified SMC can achieve good vehicle dynamics control performance in normal driving and large steering angle turning scenarios. In addition, the proposed actuator-grouping SMC can solve the coupling effect of different control targets and the control performance is improved.

  17. Fault Tolerant Attitude Control for spacecraft with SGCMGs under actuator partial failure and actuator saturation

    NASA Astrophysics Data System (ADS)

    Zhang, Fuzhen; Jin, Lei; Xu, Shijie

    2017-03-01

    A Fault Tolerant Attitude Control algorithm for the spacecraft using Single Gimbal Control Moment Gyros (SGCMGs) as actuator is proposed. The controller is designed using the sliding mode control theory to control the gimbal rate directly and there is no singular point in the control algorithm, which means that we don't need to design the steering laws again and the singularity problems can be avoided. Also the gimbal rate saturation is considered when designing the control method. The adaptive control algorithm is used to estimate the disturbance and the boundary of the fault and saturation, which means that no prior information of the fault is needed. Although the controller is designed based on the SGCMGs, it can also be employed when reaction wheels work as the actuator of the spacecraft. Also the complete failure of several SGCMGs is allowed. It is proved based on the Lyapunov stability theorem that the designed control algorithm can achieve the attitude asymptotic stability both on the fault or fault-free condition. The simulation results show that the proposed method has a strong robustness.

  18. Adaptive backstepping fault-tolerant control for flexible spacecraft with unknown bounded disturbances and actuator failures.

    PubMed

    Jiang, Ye; Hu, Qinglei; Ma, Guangfu

    2010-01-01

    In this paper, a robust adaptive fault-tolerant control approach to attitude tracking of flexible spacecraft is proposed for use in situations when there are reaction wheel/actuator failures, persistent bounded disturbances and unknown inertia parameter uncertainties. The controller is designed based on an adaptive backstepping sliding mode control scheme, and a sufficient condition under which this control law can render the system semi-globally input-to-state stable is also provided such that the closed-loop system is robust with respect to any disturbance within a quantifiable restriction on the amplitude, as well as the set of initial conditions, if the control gains are designed appropriately. Moreover, in the design, the control law does not need a fault detection and isolation mechanism even if the failure time instants, patterns and values on actuator failures are also unknown for the designers, as motivated from a practical spacecraft control application. In addition to detailed derivations of the new controller design and a rigorous sketch of all the associated stability and attitude error convergence proofs, illustrative simulation results of an application to flexible spacecraft show that high precise attitude control and vibration suppression are successfully achieved using various scenarios of controlling effective failures.

  19. Sensor and sensorless fault tolerant control for induction motors using a wavelet index.

    PubMed

    Gaeid, Khalaf Salloum; Ping, Hew Wooi; Khalid, Mustafa; Masaoud, Ammar

    2012-01-01

    Fault Tolerant Control (FTC) systems are crucial in industry to ensure safe and reliable operation, especially of motor drives. This paper proposes the use of multiple controllers for a FTC system of an induction motor drive, selected based on a switching mechanism. The system switches between sensor vector control, sensorless vector control, closed-loop voltage by frequency (V/f) control and open loop V/f control. Vector control offers high performance, while V/f is a simple, low cost strategy with high speed and satisfactory performance. The faults dealt with are speed sensor failures, stator winding open circuits, shorts and minimum voltage faults. In the event of compound faults, a protection unit halts motor operation. The faults are detected using a wavelet index. For the sensorless vector control, a novel Boosted Model Reference Adaptive System (BMRAS) to estimate the motor speed is presented, which reduces tuning time. Both simulation results and experimental results with an induction motor drive show the scheme to be a fast and effective one for fault detection, while the control methods transition smoothly and ensure the effectiveness of the FTC system. The system is also shown to be flexible, reverting rapidly back to the dominant controller if the motor returns to a healthy state.

  20. Sensor and Sensorless Fault Tolerant Control for Induction Motors Using a Wavelet Index

    PubMed Central

    Gaeid, Khalaf Salloum; Ping, Hew Wooi; Khalid, Mustafa; Masaoud, Ammar

    2012-01-01

    Fault Tolerant Control (FTC) systems are crucial in industry to ensure safe and reliable operation, especially of motor drives. This paper proposes the use of multiple controllers for a FTC system of an induction motor drive, selected based on a switching mechanism. The system switches between sensor vector control, sensorless vector control, closed-loop voltage by frequency (V/f) control and open loop V/f control. Vector control offers high performance, while V/f is a simple, low cost strategy with high speed and satisfactory performance. The faults dealt with are speed sensor failures, stator winding open circuits, shorts and minimum voltage faults. In the event of compound faults, a protection unit halts motor operation. The faults are detected using a wavelet index. For the sensorless vector control, a novel Boosted Model Reference Adaptive System (BMRAS) to estimate the motor speed is presented, which reduces tuning time. Both simulation results and experimental results with an induction motor drive show the scheme to be a fast and effective one for fault detection, while the control methods transition smoothly and ensure the effectiveness of the FTC system. The system is also shown to be flexible, reverting rapidly back to the dominant controller if the motor returns to a healthy state. PMID:22666016

  1. Fault-tolerant analysis and control of SSRMS-type manipulators with single-joint failure

    NASA Astrophysics Data System (ADS)

    She, Yu; Xu, Wenfu; Su, Haijun; Liang, Bin; Shi, Hongliang

    2016-03-01

    Several space manipulators, whose configurations are similar to that of the Space Station Remote Manipulator System (SSRMS, also called Canadarm2), are playing important roles in the construction and maintenance of the International Space Station. Working in the harsh orbital environment, they are at high risk of single-joint failure. Fault-tolerant capability is critical for those manipulators to complete their on-orbital tasks. In this paper, we analysed and compared the manipulation capability of SSRMS-type manipulators with joints locked at arbitrary positions, and proposed efficient path planning via a fault-tolerant control method. First, a unified kinematic model of this type of manipulators was established. Second, the manipulation capability of the original 7-DOF (degrees of freedom) redundant manipulator was analysed and compared with its degraded 6-DOF counterparts formed by different joint locking configurations. Then, we identified those joints with large sensitivity to fault tolerance performance. The influences of different positions of all joints were also determined by numerical computation. Based on the analysis, the relatively safe and dangerous regions for each joint failure were identified. Finally, we proposed a path planning strategy and realized by a H∞ controller which enables the failure joint locked in the safe region, and simulations were carried on a degraded 3-DOF planar redundant manipulator to verify the planning strategy and control approach. This paper provided important analysis results and efficient methods to address the possible problems of SSRMS-type manipulators caused by single-joint failure that can be extended to other types of manipulators. Moreover, the proposed method is useful for designing the optimal configuration of a redundant manipulator.

  2. Plasma and urinary aluminum concentrations in severely anemic geophagous pregnant women in the Bas Maroni region of French Guiana: a case-control study.

    PubMed

    Lambert, Veronique; Boukhari, Rachida; Nacher, Mathieu; Goullé, Jean-Pierre; Roudier, Estelle; Elguindi, Wael; Laquerrière, Annie; Carles, Gabriel

    2010-11-01

    The clays consumed by geophagous individuals contain large quantities of aluminum, a known neurological and hematological toxin. This is the first study to evaluate the risk of aluminum poisoning in geophagous individuals. Blind determinations of plasma and urinary aluminum concentrations were carried out in 98 anemic geophagous pregnant women and 85 non-anemic non-geophagous pregnant women. Aluminum concentrations were significantly higher (P < 0.0001) in the geophagous anemic women than in the controls, with odds ratios of 6.83 (95% confidence interval [CI] = 2.72-19.31) for plasma concentrations (13.92 ± 14.09 μg/L versus 4.95 ± 7.11 μg/L) and 5.44 (95% CI = 2.17-14.8) for urinary concentrations (92.83 ± 251.21 μg/L versus 12.11 ± 23 μg/L). The ingested clay is the most likely source of this overexposure to aluminum. If confirmed, the clinical consequences of this absorption for pregnant women and their offspring should be explored.

  3. Plasma and Urinary Aluminum Concentrations in Severely Anemic Geophagous Pregnant Women in the Bas Maroni Region of French Guiana: A Case-Control Study

    PubMed Central

    Lambert, Veronique; Boukhari, Rachida; Nacher, Mathieu; Goullé, Jean-Pierre; Roudier, Estelle; Elguindi, Wael; Laquerrière, Annie; Carles, Gabriel

    2010-01-01

    The clays consumed by geophagous individuals contain large quantities of aluminum, a known neurological and hematological toxin. This is the first study to evaluate the risk of aluminum poisoning in geophagous individuals. Blind determinations of plasma and urinary aluminum concentrations were carried out in 98 anemic geophagous pregnant women and 85 non-anemic non-geophagous pregnant women. Aluminum concentrations were significantly higher (P < 0.0001) in the geophagous anemic women than in the controls, with odds ratios of 6.83 (95% confidence interval [CI] = 2.72–19.31) for plasma concentrations (13.92 ± 14.09 μg/L versus 4.95 ± 7.11 μg/L) and 5.44 (95% CI = 2.17–14.8) for urinary concentrations (92.83 ± 251.21 μg/L versus 12.11 ± 23 μg/L). The ingested clay is the most likely source of this overexposure to aluminum. If confirmed, the clinical consequences of this absorption for pregnant women and their offspring should be explored. PMID:21036845

  4. Fault-tolerant control of large space structures using the stable factorization approach

    NASA Technical Reports Server (NTRS)

    Razavi, H. C.; Mehra, R. K.; Vidyasagar, M.

    1986-01-01

    Large space structures are characterized by the following features: they are in general infinite-dimensional systems, and have large numbers of undamped or lightly damped poles. Any attempt to apply linear control theory to large space structures must therefore take into account these features. Phase I consisted of an attempt to apply the recently developed Stable Factorization (SF) design philosophy to problems of large space structures, with particular attention to the aspects of robustness and fault tolerance. The final report on the Phase I effort consists of four sections, each devoted to one task. The first three sections report theoretical results, while the last consists of a design example. Significant results were obtained in all four tasks of the project. More specifically, an innovative approach to order reduction was obtained, stabilizing controller structures for plants with an infinite number of unstable poles were determined under some conditions, conditions for simultaneous stabilizability of an infinite number of plants were explored, and a fault tolerance controller design that stabilizes a flexible structure model was obtained which is robust against one failure condition.

  5. ADP-ribosylating bacterial enzymes for the targeted control of mucosal tolerance and immunity.

    PubMed

    Lycke, Nils

    2004-12-01

    in the spleen after intravenous injection. Only active CTA1-DD, but not the inactive mutant CTA1R7K-DD, provided enhancing effects on immune responses. By contrast, antigen delivered by the CTA1R7K-DD stimulated specific tolerance in adoptively transferred T cell receptor transgenic CD4(+) T cells. Whether targeting of B cells suffices for tolerance induction or requires participation of DCs remains to be investigated. With CT we found that enzyme-dependent modulation of DCs affects migration, maturation, and differentiation of DCs, which resulted in CD4(+) T cell help for IgA B cell development. On the contrary, antigen presentation in the absence of ADP-ribosylating enzyme, as seen with CTB or CTA1R7K-DD, appears to expand specific T cells to a similar extent as enzymatically active CT or CTA1-DD, but fails to recruit help for germinal center (GC) formation and the necessary expansion of activated B cells. Also, the CD41 T cells that are primed in a suboptimal, tolerogenic, fashion do not migrate to the B cell follicle to provide T cell help. Thus, ADP-ribosylating enzymes may be used to selectively control the induction of an active IgA response or promote the development of tolerance. In particular, on the targeted APC, modulation of the expression of costimulatory molecules, CD80, CD86, CD83, and B7RP-1, plays an important role in the effect of the ADP-ribosylating CTA1-based adjuvants on the development of tolerance or active IgA immunity. For example, the expression of CD86 in vivo was a prominent feature of the enzymatically active CT or CTA1-DD adjuvants. By contrast, CD80 expression appeared not to be important in CTA1-augmented APCs for an adjuvant function.

  6. Enhanced Phosphorus Locking by Novel Lanthanum/Aluminum-Hydroxide Composite: Implications for Eutrophication Control.

    PubMed

    Xu, Rui; Zhang, Meiyi; Mortimer, Robert J G; Pan, Gang

    2017-03-21

    Lanthanum (La) bearing materials have been widely used to remove phosphorus (P) in water treatment. However, it remains a challenge to enhance phosphate (PO4) adsorption capacity and La usage efficiency. In this study, La was coprecipitated with aluminum (Al) to obtain a La/Al-hydroxide composite (LAH) for P adsorption. The maximum PO4 adsorption capacities of LAH (5.3% La) were 76.3 and 45.3 mg P g(-1) at pH 4.0 and 8.5, which were 8.5 and 5.3 times higher than those of commercially available La-modified bentonite (Phoslock, 5.6% La), respectively. P K-edge X-ray absorption near edge structure analysis showed that PO4 was preferentially bonded with Al under weakly acid conditions (pH 4.0), while tended to associate with La under alkaline conditions (pH 8.5). La LIII-edge extended X-ray absorption fine structure analysis indicated that PO4 was bonded on La sites by forming inner sphere bidentate-binuclear complexes and oxygen defects exhibited on LAH surfaces, which could be active adsorption sites for PO4. The electrostatic interaction, ligand exchange, and oxygen defects on LAH surfaces jointly facilitated PO4 adsorption but with varied contribution under different pH conditions. The combined contribution of two-component of La and Al may be an important direction for the next generation of commercial products for eutrophication mitigation.

  7. Reactive solute transport in an acidic stream: Experimental pH increase and simulation of controls on pH, aluminum, and iron

    USGS Publications Warehouse

    Broshears, R.E.; Runkel, R.L.; Kimball, B.A.; McKnight, Diane M.; Bencala, K.E.

    1996-01-01

    Solute transport simulations quantitatively constrained hydrologic and geochemical hypotheses about field observations of a pH modification in an acid mine drainage stream. Carbonate chemistry, the formation of solid phases, and buffering interactions with the stream bed were important factors in explaining the behavior of pH, aluminum, and iron. The precipitation of microcrystalline gibbsite accounted for the behavior of aluminum; precipitation of Fe(OH)3 explained the general pattern of iron solubility. The dynamic experiment revealed limitations on assumptions that reactions were controlled only by equilibrium chemistry. Temporal variation in relative rates of photoreduction and oxidation influenced iron behavior. Kinetic limitations on ferrous iron oxidation and hydrous oxide precipitation and the effects of these limitations on field filtration were evident. Kinetic restraints also characterized interaction between the water column and the stream bed, including sorption and desorption of protons from iron oxides at the sediment-water interface and post-injection dissolution of the precipitated aluminum solid phase.

  8. Decentralized Fault-Tolerant Control of Inland Navigation Networks: a Challenge

    NASA Astrophysics Data System (ADS)

    Segovia, P.; Rajaoarisoa, L.; Nejjari, F.; Blesa, J.; Puig, V.; Duviella, E.

    2017-01-01

    Inland waterways are large-scale networks used principally for navigation. Even if the transport planning is an important issue, the water resource management is a crucial point. Indeed, navigation is not possible when there is too little or too much water inside the waterways. Hence, the water resource management of waterways has to be particularly efficient in a context of climate change and increase of water demand. This management has to be done by considering different time and space scales and still requires the development of new methodologies and tools in the topics of the Control and Informatics communities. This work addresses the problem of waterways management in terms of modeling, control, diagnosis and fault-tolerant control by focusing in the inland waterways of the north of France. A review of proposed tools and the ongoing research topics are provided in this paper.

  9. Controls on dissolved cobalt in surface waters of the Sargasso Sea: Comparisons with iron and aluminum

    NASA Astrophysics Data System (ADS)

    Shelley, R. U.; Sedwick, P. N.; Bibby, T. S.; Cabedo-Sanz, P.; Church, T. M.; Johnson, R. J.; Macey, A. I.; Marsay, C. M.; Sholkovitz, E. R.; Ussher, S. J.; Worsfold, P. J.; Lohan, M. C.

    2012-06-01

    Dissolved cobalt (dCo), iron (dFe) and aluminum (dAl) were determined in water column samples along a meridional transect (˜31°N to 24°N) south of Bermuda in June 2008. A general north-to-south increase in surface concentrations of dFe (0.3-1.6 nM) and dAl (14-42 nM) was observed, suggesting that aerosol deposition is a significant source of dFe and dAl, whereas no clear trend was observed for near-surface dCo concentrations. Shipboard aerosol samples indicate fractional solubility values of 8-100% for aerosol Co, which are significantly higher than corresponding estimates of the solubility of aerosol Fe (0.44-45%). Hydrographic observations and analysis of time series rain samples from Bermuda indicate that wet deposition accounts for most (>80%) of the total aeolian flux of Co, and hence a significant proportion of the atmospheric input of dCo to our study region. Our aerosol data imply that the atmospheric input of dCo to the Sargasso Sea is modest, although this flux may be more significant in late summer. The water column dCo profiles reveal a vertical distribution that predominantly reflects `nutrient-type' behavior, versus scavenged-type behavior for dAl, and a hybrid of nutrient- and scavenged-type behavior for dFe. Mesoscale eddies also appear to impact on the vertical distribution of dCo. The effects of biological removal of dCo from the upper water column were apparent as pronounced sub-surface minima (21 ± 4 pM dCo), coincident with maxima in Prochlorococcus abundance. These observations imply that Prochlorococcus plays a major role in removing dCo from the euphotic zone, and that the availability of dCo may regulate Prochlorococcus growth in the Sargasso Sea.

  10. Aluminum battery alloys

    DOEpatents

    Thompson, David S.; Scott, Darwin H.

    1985-01-01

    Aluminum alloys suitable for use as anode structures in electrochemical cs are disclosed. These alloys include iron levels higher than previously felt possible, due to the presence of controlled amounts of manganese, with possible additions of magnesium and controlled amounts of gallium.

  11. Aluminum battery alloys

    DOEpatents

    Thompson, D.S.; Scott, D.H.

    1984-09-28

    Aluminum alloys suitable for use as anode structures in electrochemical cells are disclosed. These alloys include iron levels higher than previously felt possible, due to the presence of controlled amounts of manganese, with possible additions of magnesium and controlled amounts of gallium.

  12. Aluminum Analysis.

    ERIC Educational Resources Information Center

    Sumrall, William J.

    1998-01-01

    Presents three problems based on the price of aluminum designed to encourage students to be cooperative and to use an investigative approach to learning. Students collect and synthesize information, analyze results, and draw conclusions. (AIM)

  13. Fault tolerant control based on interval type-2 fuzzy sliding mode controller for coaxial trirotor aircraft.

    PubMed

    Zeghlache, Samir; Kara, Kamel; Saigaa, Djamel

    2015-11-01

    In this paper, a robust controller for a Six Degrees of Freedom (6 DOF) coaxial trirotor helicopter control is proposed in presence of defects in the system. A control strategy based on the coupling of the interval type-2 fuzzy logic control and sliding mode control technique are used to design a controller. The main purpose of this work is to eliminate the chattering phenomenon and guaranteeing the stability and the robustness of the system. In order to achieve this goal, interval type-2 fuzzy logic control has been used to generate the discontinuous control signal. The simulation results have shown that the proposed control strategy can greatly alleviate the chattering effect, and perform good reference tracking in presence of defects in the system.

  14. Tolerating dissimilar other when primed with death: neural evidence of self-control engaged by interdependent people in Japan.

    PubMed

    Yanagisawa, Kuniaki; Kashima, Emiko S; Moriya, Hiroki; Masui, Keita; Furutani, Kaichiro; Yoshida, Hiroshi; Ura, Mitsuhiro; Nomura, Michio

    2017-02-17

    Mortality salience (MS) has been shown to lead to derogation of others with dissimilar worldviews, yet recent research has shown that Asian-Americans who presumably adopt an interdependent self-construal (SC) tend to reveal greater tolerance after MS induction. In the present study, we demonstrated that Japanese individuals who are high on interdependent SC indeed show greater tolerance toward worldview-threatening other in the MS (vs control) condition, thus replicating the prior research. Extending this research, we also found that interdependent people's tolerance toward worldview-threatening other was mediated by increased activity in the right ventrolateral prefrontal cortex in the MS condition. These data suggested that when exposed to death-related stimuli, highly interdependent individuals may spontaneously activate their neural self-control system which may serve to increase tolerance toward others.

  15. A Framework for Probabilistic Evaluation of Interval Management Tolerance in the Terminal Radar Control Area

    NASA Technical Reports Server (NTRS)

    Hercencia-Zapana, Heber; Herencia-Zapana, Heber; Hagen, George E.; Neogi, Natasha

    2012-01-01

    Projections of future traffic in the national airspace show that most of the hub airports and their attendant airspace will need to undergo significant redevelopment and redesign in order to accommodate any significant increase in traffic volume. Even though closely spaced parallel approaches increase throughput into a given airport, controller workload in oversubscribed metroplexes is further taxed by these approaches that require stringent monitoring in a saturated environment. The interval management (IM) concept in the TRACON area is designed to shift some of the operational burden from the control tower to the flight deck, placing the flight crew in charge of implementing the required speed changes to maintain a relative spacing interval. The interval management tolerance is a measure of the allowable deviation from the desired spacing interval for the IM aircraft (and its target aircraft). For this complex task, Formal Methods can help to ensure better design and system implementation. In this paper, we propose a probabilistic framework to quantify the uncertainty and performance associated with the major components of the IM tolerance. The analytical basis for this framework may be used to formalize both correctness and probabilistic system safety claims in a modular fashion at the algorithmic level in a way compatible with several Formal Methods tools.

  16. Results and perspectives on fault tolerant control for a class of hybrid systems

    NASA Astrophysics Data System (ADS)

    Jiang, Bin; Yang, Hao; Cocquempot, Vincent

    2011-02-01

    This article addresses the fault tolerant control (FTC) issue for a class of hybrid systems (HS) modelled by hybrid automata. Two kinds of faults are considered: continuous fault that affects each continuous system mode; discrete fault that affects the switching conditions. In these two faulty cases, the FTC design has two main objectives: (1) maintain the continuous performances including various stabilities of the origin and the output tracking/regulation behaviours along the trajectories of HS; (2) maintain the discrete specifications that have to be followed by HS, e.g. a desired switching sequence. The following three FTC methodologies are considered: FTC for HS with continuous stability goal; FTC for HS with discrete specifications; supervisory FTC design via hybrid control techniques. Some perspectives are also provided. This article provides the readers a survey on the main techniques that can be used to achieve these FTC goals of HS.

  17. Hybridization of an invasive shrub affects tolerance and resistance to defoliation by a biological control agent

    USGS Publications Warehouse

    Williams, Wyatt I.; Friedman, Jonathan M.; Gaskin, John F.; Norton, Andrew P.

    2014-01-01

    Evolution has contributed to the successful invasion of exotic plant species in their introduced ranges, but how evolution affects particular control strategies is still under evaluation. For instance, classical biological control, a common strategy involving the utilization of highly specific natural enemies to control exotic pests, may be negatively affected by host hybridization because of shifts in plant traits, such as root allocation or chemical constituents. We investigated introgression between two parent species of the invasive shrub tamarisk (Tamarix spp.) in the western United States, and how differences in plant traits affect interactions with a biological control agent. Introgression varied strongly with latitude of origin and was highly correlated with plant performance. Increased levels of T. ramosissima introgression resulted in both higher investment in roots and tolerance to defoliation and less resistance to insect attack. Because tamarisk hybridization occurs predictably on the western U.S. landscape, managers may be able to exploit this information to maximize control efforts. Genetic differentiation in plant traits in this system underpins the importance of plant hybridization and may explain why some biological control releases are more successful than others.

  18. Laboratory test methodology for evaluating the effects of electromagnetic disturbances on fault-tolerant control systems

    NASA Technical Reports Server (NTRS)

    Belcastro, Celeste M.

    1989-01-01

    Control systems for advanced aircraft, especially those with relaxed static stability, will be critical to flight and will, therefore, have very high reliability specifications which must be met for adverse as well as nominal operating conditions. Adverse conditions can result from electromagnetic disturbances caused by lightning, high energy radio frequency transmitters, and nuclear electromagnetic pulses. Tools and techniques must be developed to verify the integrity of the control system in adverse operating conditions. The most difficult and illusive perturbations to computer based control systems caused by an electromagnetic environment (EME) are functional error modes that involve no component damage. These error modes are collectively known as upset, can occur simultaneously in all of the channels of a redundant control system, and are software dependent. A methodology is presented for performing upset tests on a multichannel control system and considerations are discussed for the design of upset tests to be conducted in the lab on fault tolerant control systems operating in a closed loop with a simulated plant.

  19. Disturbance observer based fault estimation and dynamic output feedback fault tolerant control for fuzzy systems with local nonlinear models.

    PubMed

    Han, Jian; Zhang, Huaguang; Wang, Yingchun; Liu, Yang

    2015-11-01

    This paper addresses the problems of fault estimation (FE) and fault tolerant control (FTC) for fuzzy systems with local nonlinear models, external disturbances, sensor and actuator faults, simultaneously. Disturbance observer (DO) and FE observer are designed, simultaneously. Compared with the existing results, the proposed observer is with a wider application range. Using the estimation information, a novel fuzzy dynamic output feedback fault tolerant controller (DOFFTC) is designed. The controller can be used for the fuzzy systems with unmeasurable local nonlinear models, mismatched input disturbances, and measurement output affecting by sensor faults and disturbances. At last, the simulation shows the effectiveness of the proposed methods.

  20. SKIP Confers Osmotic Tolerance during Salt Stress by Controlling Alternative Gene Splicing in Arabidopsis.

    PubMed

    Feng, Jinlin; Li, Jingjing; Gao, Zhaoxu; Lu, Yaru; Yu, Junya; Zheng, Qian; Yan, Shuning; Zhang, Wenjiao; He, Hang; Ma, Ligeng; Zhu, Zhengge

    2015-07-01

    Deciphering the mechanisms underlying plant responses to abiotic stress is key for improving plant stress resistance. Much is known about the regulation of gene expression in response to salt stress at the transcriptional level; however, little is known about this process at the posttranscriptional level. Recently, we demonstrated that SKIP is a component of spliceosome that interacts with clock gene pre-mRNAs and is essential for regulating their alternative splicing and mRNA maturation. In this study, we found that skip-1 plants are hypersensitive to both salt and osmotic stresses, and that SKIP is required for the alternative splicing and mRNA maturation of several salt-tolerance genes, including NHX1, CBL1, P5CS1, RCI2A, and PAT10. A genome-wide analysis revealed that SKIP mediates the alternative splicing of many genes under salt-stress conditions, and that most of the alternative splicing events in skip-1 involve intron retention and can generate a premature termination codon in the transcribed mRNA. SKIP also controls alternative splicing by modulating the recognition or cleavage of 5' and 3' splice donor and acceptor sites under salt-stress conditions. Therefore, this study addresses the fundamental question of how the mRNA splicing machinery in plants contributes to salt-stress responses at the posttranscriptional level, and provides a link between alternative splicing and salt tolerance.

  1. Calcineurin controls drug tolerance, hyphal growth, and virulence in Candida dubliniensis.

    PubMed

    Chen, Ying-Lien; Brand, Alexandra; Morrison, Emma L; Silao, Fitz Gerald S; Bigol, Ursela G; Malbas, Fedelino F; Nett, Jeniel E; Andes, David R; Solis, Norma V; Filler, Scott G; Averette, Anna; Heitman, Joseph

    2011-06-01

    Candida dubliniensis is an emerging pathogenic yeast species closely related to Candida albicans and frequently found colonizing or infecting the oral cavities of HIV/AIDS patients. Drug resistance during C. dubliniensis infection is common and constitutes a significant therapeutic challenge. The calcineurin inhibitor FK506 exhibits synergistic fungicidal activity with azoles or echinocandins in the fungal pathogens C. albicans, Cryptococcus neoformans, and Aspergillus fumigatus. In this study, we show that calcineurin is required for cell wall integrity and wild-type tolerance of C. dubliniensis to azoles and echinocandins; hence, these drugs are candidates for combination therapy with calcineurin inhibitors. In contrast to C. albicans, in which the roles of calcineurin and Crz1 in hyphal growth are unclear, here we show that calcineurin and Crz1 play a clearly demonstrable role in hyphal growth in response to nutrient limitation in C. dubliniensis. We further demonstrate that thigmotropism is controlled by Crz1, but not calcineurin, in C. dubliniensis. Similar to C. albicans, C. dubliniensis calcineurin enhances survival in serum. C. dubliniensis calcineurin and crz1/crz1 mutants exhibit attenuated virulence in a murine systemic infection model, likely attributable to defects in cell wall integrity, hyphal growth, and serum survival. Furthermore, we show that C. dubliniensis calcineurin mutants are unable to establish murine ocular infection or form biofilms in a rat denture model. That calcineurin is required for drug tolerance and virulence makes fungus-specific calcineurin inhibitors attractive candidates for combination therapy with azoles or echinocandins against emerging C. dubliniensis infections.

  2. Neuregulin improves response to glucose tolerance test in control and diabetic rats.

    PubMed

    López-Soldado, Iliana; Niisuke, Katrin; Veiga, Catarina; Adrover, Anna; Manzano, Anna; Martínez-Redondo, Vicente; Camps, Marta; Bartrons, Ramon; Zorzano, Antonio; Gumà, Anna

    2016-03-15

    Neuregulin (NRG) is an EGF-related growth factor that binds to the tyrosine kinase receptors ErbB3 and ErbB4, thus inducing tissue development and muscle glucose utilization during contraction. Here, we analyzed whether NRG has systemic effects regulating glycemia in control and type 2 diabetic rats. To this end, recombinant NRG (rNRG) was injected into Zucker diabetic fatty (ZDF) rats and their respective lean littermates 15 min before a glucose tolerance test (GTT) was performed. rNRG enhanced glucose tolerance without promoting the activation of the insulin receptor (IR) or insulin receptor substrates (IRS) in muscle and liver. However, in control rats, rNRG induced the phosphorylation of protein kinase B (PKB) and glycogen synthase kinase-3 (GSK-3) in liver but not in muscle. In liver, rNRG increased ErbB3 tyrosine phosphorylation and its binding to phosphatidylinositol 3-kinase (PI3K), thus indicating that rNRG activates the ErbB3/PI3K/PKB signaling pathway. rNRG increased glycogen content in liver but not in muscle. rNRG also increased the content of fructose-2,6-bisphosphate (Fru-2,6-P2), an activator of hepatic glycolysis, and lactate in liver but not in muscle. Increases in lactate were abrogated by wortmannin, a PI3K inhibitor, in incubated hepatocytes. The liver of ZDF rats showed a reduced content of ErbB3 receptors, entailing a minor stimulation of the rNRG-induced PKB/GSK-3 cascade and resulting in unaltered hepatic glycogen content. Nonetheless, rNRG increased hepatic Fru-2,6-P2 and augmented lactate both in liver and in plasma of diabetic rats. As a whole, rNRG improved response to the GTT in both control and diabetic rats by enhancing hepatic glucose utilization.

  3. Novel control of lactate dehydrogenase from the freeze tolerant wood frog: role of posttranslational modifications

    PubMed Central

    Abboud, Jean

    2013-01-01

    Lactate dehydrogenase (LDH), the terminal enzyme of anaerobic glycolysis, plays a crucial role both in sustaining glycolytic ATP production under oxygen-limiting conditions and in facilitating the catabolism of accumulated lactate when stress conditions are relieved. In this study, the effects on LDH of in vivo freezing and dehydration stresses (both of which impose hypoxia/anoxia stress on tissues) were examined in skeletal muscle of the freeze-tolerant wood frog, Rana sylvatica. LDH from muscle of control, frozen and dehydrated wood frogs was purified to homogeneity in a two-step process. The kinetic properties and stability of purified LDH were analyzed, revealing no significant differences in Vmax, Km and I50 values between control and frozen LDH. However, control and dehydrated LDH differed significantly in Km values for pyruvate, lactate, and NAD, I50 urea, and in temperature, glucose, and urea effects on these parameters. The possibility that posttranslational modification of LDH was responsible for the stable differences in enzyme behavior between control and dehydrated states was assessed using ProQ diamond staining to detect phosphorylation and immunoblotting to detect acetylation, methylation, ubiquitination, SUMOylation and nitrosylation of the enzyme. LDH from muscle of dehydrated wood frogs showed significantly lower levels of acetylation, providing one of the first demonstrations of a potential role for protein acetylation in the stress-responsive control of a metabolic enzyme. PMID:23638346

  4. Novel control of lactate dehydrogenase from the freeze tolerant wood frog: role of posttranslational modifications.

    PubMed

    Abboud, Jean; Storey, Kenneth B

    2013-01-01

    Lactate dehydrogenase (LDH), the terminal enzyme of anaerobic glycolysis, plays a crucial role both in sustaining glycolytic ATP production under oxygen-limiting conditions and in facilitating the catabolism of accumulated lactate when stress conditions are relieved. In this study, the effects on LDH of in vivo freezing and dehydration stresses (both of which impose hypoxia/anoxia stress on tissues) were examined in skeletal muscle of the freeze-tolerant wood frog, Rana sylvatica. LDH from muscle of control, frozen and dehydrated wood frogs was purified to homogeneity in a two-step process. The kinetic properties and stability of purified LDH were analyzed, revealing no significant differences in V max, K m and I 50 values between control and frozen LDH. However, control and dehydrated LDH differed significantly in K m values for pyruvate, lactate, and NAD, I 50 urea, and in temperature, glucose, and urea effects on these parameters. The possibility that posttranslational modification of LDH was responsible for the stable differences in enzyme behavior between control and dehydrated states was assessed using ProQ diamond staining to detect phosphorylation and immunoblotting to detect acetylation, methylation, ubiquitination, SUMOylation and nitrosylation of the enzyme. LDH from muscle of dehydrated wood frogs showed significantly lower levels of acetylation, providing one of the first demonstrations of a potential role for protein acetylation in the stress-responsive control of a metabolic enzyme.

  5. Genotypic difference in salinity tolerance in quinoa is determined by differential control of xylem Na(+) loading and stomatal density.

    PubMed

    Shabala, Sergey; Hariadi, Yuda; Jacobsen, Sven-Erik

    2013-07-01

    Quinoa is regarded as a highly salt tolerant halophyte crop, of great potential for cultivation on saline areas around the world. Fourteen quinoa genotypes of different geographical origin, differing in salinity tolerance, were grown under greenhouse conditions. Salinity treatment started on 10 day old seedlings. Six weeks after the treatment commenced, leaf sap Na and K content and osmolality, stomatal density, chlorophyll fluorescence characteristics, and xylem sap Na and K composition were measured. Responses to salinity differed greatly among the varieties. All cultivars had substantially increased K(+) concentrations in the leaf sap, but the most tolerant cultivars had lower xylem Na(+) content at the time of sampling. Most tolerant cultivars had lowest leaf sap osmolality. All varieties reduced stomata density when grown under saline conditions. All varieties clustered into two groups (includers and excluders) depending on their strategy of handling Na(+) under saline conditions. Under control (non-saline) conditions, a strong positive correlation was observed between salinity tolerance and plants ability to accumulate Na(+) in the shoot. Increased leaf sap K(+), controlled Na(+) loading to the xylem, and reduced stomata density are important physiological traits contributing to genotypic differences in salinity tolerance in quinoa, a halophyte species from Chenopodium family.

  6. Overexpression of Arabidopsis translationally controlled tumor protein gene AtTCTP enhances drought tolerance with rapid ABA-induced stomatal closure.

    PubMed

    Kim, Yong-Min; Han, Yun-Jeong; Hwang, Ok-Jin; Lee, Si-Seok; Shin, Ah-Young; Kim, Soo Young; Kim, Jeong-Il

    2012-06-01

    Translationally controlled tumor protein (TCTP), also termed P23 in human, belongs to a family of calcium- and tubulin-binding proteins, and it is generally regarded as a growth-regulating protein. Recently, Arabidopsis TCTP (AtTCTP) has been reported to function as an important growth regulator in plants. On the other hand, plant TCTP has been suggested to be involved in abiotic stress signaling such as aluminum, salt, and water deficit by a number of microarray or proteomic analyses. In this study, the biological functions of AtTCTP were investigated by using transgenic Arabidopsis plants overexpressing AtTCTP. Interestingly, AtTCTP overexpression enhanced drought tolerance in plants. The expression analysis showed that AtTCTP was expressed in guard cells as well as in actively growing tissues. Physiological studies of the overexpression lines showed increased ABA- and calcium-induced stomatal closure ratios and faster stomatal closing responses to ABA. Furthermore, in vitro protein-protein interaction analysis confirmed the interaction between AtTCTP and microtubules, and microtubule cosedimentation assays revealed that the microtubule binding of AtTCTP increased after calcium treatment. These results demonstrate that the overexpression of AtTCTP confers drought tolerance to plants by rapid ABA-mediated stomatal closure via the interaction with microtubules in which calcium binding enhances the interaction. Collectively, the present results suggest that the plant TCTP has molecular properties similar to animal TCTPs, such as tubulin- and calcium-binding, and that it functions in ABA-mediated stomatal movement, in addition to regulating the growth of plants.

  7. Fault tolerant synchronization of chaotic heavy symmetric gyroscope systems versus external disturbances via Lyapunov rule-based fuzzy control.

    PubMed

    Farivar, Faezeh; Shoorehdeli, Mahdi Aliyari

    2012-01-01

    In this paper, fault tolerant synchronization of chaotic gyroscope systems versus external disturbances via Lyapunov rule-based fuzzy control is investigated. Taking the general nature of faults in the slave system into account, a new synchronization scheme, namely, fault tolerant synchronization, is proposed, by which the synchronization can be achieved no matter whether the faults and disturbances occur or not. By making use of a slave observer and a Lyapunov rule-based fuzzy control, fault tolerant synchronization can be achieved. Two techniques are considered as control methods: classic Lyapunov-based control and Lyapunov rule-based fuzzy control. On the basis of Lyapunov stability theory and fuzzy rules, the nonlinear controller and some generic sufficient conditions for global asymptotic synchronization are obtained. The fuzzy rules are directly constructed subject to a common Lyapunov function such that the error dynamics of two identical chaotic motions of symmetric gyros satisfy stability in the Lyapunov sense. Two proposed methods are compared. The Lyapunov rule-based fuzzy control can compensate for the actuator faults and disturbances occurring in the slave system. Numerical simulation results demonstrate the validity and feasibility of the proposed method for fault tolerant synchronization.

  8. Fault-tolerant strategies for an implantable centrifugal blood pump using a radially controlled magnetic bearing.

    PubMed

    Pai, Chi Nan; Shinshi, Tadahiko

    2011-10-01

    In our laboratory, an implantable centrifugal blood pump (CBP) with a two degrees-of-freedom radially controlled magnetic bearing (MB) to support the impeller without contact has been developed to assist the pumping function of the weakened heart ventricle. In order to maintain the function of the CBP after damage to the electromagnets (EMs) of the MB, fault-tolerant strategies for the CBP are proposed in this study. Using a redundant MB design, magnetic levitation of the impeller was maintained with damage to up to two out of a total of four EMs of the MB; with damage to three EMs, contact-free support of the impeller was achieved using hydrodynamic and electromagnetic forces; and with damage to all four EMs, the pump operating point, of 5 l/min against 100 mmHg, was achieved using the motor for rotation of the impeller, with contact between the impeller and the stator.

  9. Healthcare-associated infections, medical devices and biofilms: risk, tolerance and control.

    PubMed

    Percival, Steven L; Suleman, Louise; Vuotto, Claudia; Donelli, Gianfranco

    2015-04-01

    Biofilms are of great importance in infection control and healthcare-associated infections owing to their inherent tolerance and 'resistance' to antimicrobial therapies. Biofilms have been shown to develop on medical device surfaces, and dispersal of single and clustered cells implies a significant risk of microbial dissemination within the host and increased risk of infection. Although routine microbiological testing assists with the diagnosis of a clinical infection, there is no 'gold standard' available to reveal the presence of microbial biofilm from samples collected within clinical settings. Furthermore, such limiting factors as viable but non-culturable micro-organisms and small-colony variants often prevent successful detection. In order to increase the chances of detection and provide a more accurate diagnosis, a combination of microbiological culture techniques and molecular methods should be employed. Measures such as antimicrobial coating and surface alterations of medical devices provide promising opportunities in the prevention of biofilm formation on medical devices.

  10. Data-based fault-tolerant control for affine nonlinear systems with actuator faults.

    PubMed

    Xie, Chun-Hua; Yang, Guang-Hong

    2016-09-01

    This paper investigates the fault-tolerant control (FTC) problem for unknown nonlinear systems with actuator faults including stuck, outage, bias and loss of effectiveness. The upper bounds of stuck faults, bias faults and loss of effectiveness faults are unknown. A new data-based FTC scheme is proposed. It consists of the online estimations of the bounds and a state-dependent function. The estimations are adjusted online to compensate automatically the actuator faults. The state-dependent function solved by using real system data helps to stabilize the system. Furthermore, all signals in the resulting closed-loop system are uniformly bounded and the states converge asymptotically to zero. Compared with the existing results, the proposed approach is data-based. Finally, two simulation examples are provided to show the effectiveness of the proposed approach.

  11. A Preliminary Randomized Controlled Trial of a Distress Tolerance Treatment for Opioid Dependent Persons Initiating Buprenorphine

    PubMed Central

    Stein, Michael D.; Herman, Debra S.; Moitra, Ethan; Hecht, Jacki; Lopez, Rosalie; Anderson, Bradley J; Brown, Richard A.

    2014-01-01

    Background Buprenorphine opioid agonist treatment (OAT) has established efficacy for treating opioid dependency but early relapse rates are high and are often associated with withdrawal-related or emotional distress. Methods To determine whether a novel distress tolerance (DT) intervention during buprenorphine initiation decreases opioid relapse, we conducted a preliminary randomized controlled trial with opioid-dependent outpatients. Participants received buprenorphine-naloxone induction and 3-months of maintenance buprenorphine plus seven, 50-minute manualized, individual sessions (DT vs. Health Education (HE) control) over a 28-day period, linked to clinician medication dosing visits, and beginning 2 days prior to buprenorphine induction. Primary outcomes included use of illicit opioids (positive defined as any self-reported use in the prior 28 days or detected by urine toxicology) and treatment drop out. Results Among 49 participants, the mean age was 41 years, 65.3% were male. Persons randomized to DT had lower rates of opioid use at all three monthly assessments, and at 3-months, 72% of HE participants were opioid positive compared with 62.5% of DT participants. Rates of dropout were 24% and 25% in the HE and DT arms, respectively. Conclusions This distress tolerance treatment produced a small, but not statistically significant reduction in opioid use during the first three months of treatment although no differences were found in drop-out rates between conditions. If replicated in a larger study, DT could offer clinicians a useful behavioral treatment to complement the effects of buprenorphine. Trial registered at clinicaltrials.org. Trial number NCT01556087. PMID:25510307

  12. 6-Phosphofructo-2-kinase and control of cryoprotectant synthesis in freeze tolerant frogs.

    PubMed

    Vazquez Illanes, M D; Storey, K B

    1993-08-20

    A critical part of natural freeze tolerance is the production of low molecular weight cryoprotectants; in freeze tolerant frogs this involves a freezing-induced activation of liver glycogenolysis that leads to the accumulation of glucose as the cryoprotectant, in amounts up to 300 mM, in all organs. The present study shows that the synthesis and maintenance of high organ glucose pools is facilitated by changes in the levels of fructose-2,6-bisphosphate (F2,6P2) and an inhibition of liver 6-phosphofructo-2-kinase (PFK-2) activity that blocks the catabolism of glucose by glycolysis. Freezing exposure (24 h at -2.5 degrees C) resulted in a sharp drop in F2,6P2 levels in four organs, to 23-75% of control values, but F2,6P2 rebounded when frogs were thawed. Freezing also stimulated changes in the properties of liver PFK-2 including a decrease in maximal velocity, a basic shift in pH optimum, a 10-fold increase in Km for fructose-6-phosphate, and increased I50 values for enzyme inhibitors. I50 values for glycerol-3-phosphate and phosphoenolpyruvate were 60- and 2.4-fold higher, respectively, for liver PFK-2 from frozen frogs compared with controls. Changes in liver PFK-2 properties are consistent with a freezing-induced phosphorylation of the enzyme to produce a less active enzyme form, resulting in reduced organ F2,6P2 levels and a decrease in 6-phosphofructo-1-kinase activity.

  13. Controlled aluminum-induced crystallization of an amorphous silicon thin film by using an oxide-layer diffusion barrier

    NASA Astrophysics Data System (ADS)

    Hwang, Ji-Hyun; Kwak, Hyunmin; Kwon, Myeung Hoi

    2014-03-01

    Aluminum-induced crystallization (AIC) of amorphous silicon with an Al2O3 diffusion barrier was investigated for controlling Si crystallization and preventing layer exchange during the annealing process. An Al2O3 layer was deposited between the a-Si and the Al films (a-Si/Al2O3/Al/Glass) and was blasted with an air spray gun with alumina beads to form diffusion channels between the Si and the Al layers. During the annealing process, small grain Si x Al seeds were formed at the channels. Then, the Al2O3 diffusion barrier was restructured to close the channels and prevent further diffusion of Al atoms into the a-Si layer. A polycrystalline Si film with (111), (220) and (311) crystallization peaks in the X-ray diffraction pattern was formed by annealing at 560 °C in a conventional furnace. That film showed a p-type semiconducting behavior with good crystallinity and a large grain size of up to 14.8 µm. No layer conversion occurred between the Si and the Al layers, which had been the fundamental obstacle to the applications in the crystallization of a-Si films by using the AIC method.

  14. Controlled preparation of aluminum borate powders for the development of defect-related phosphors for warm white LED lighting

    NASA Astrophysics Data System (ADS)

    Guimarães, Vinicius F.; Salaün, Mathieu; Burner, Pauline; Maia, Lauro J. Q.; Ferrier, Alban; Viana, Bruno; Gautier-Luneau, Isabelle; Ibanez, Alain

    2017-03-01

    The optimization of the elaboration conditions of a new family of highly emissive white phosphors based on glassy yttrium aluminum borates (g-YAB) compositions is presented. Their preparation from solutions is based on the polymeric precursor method (modified Pechini process), involving non-toxic and low cost precursors. The resulting resins were first dried at moderate temperatures followed by two-step annealing treatments of the obtain powders under controlled atmospheres: a first pyrolysis under nitrogen followed by a calcination under oxygen. This favored the gradual oxidation of organic moieties coming from starting materials, avoiding uncontrolled self-combustion reactions, which generate localized hot spots. This prevented phase segregations and the formation of pyrolytic carbon or carbonates, which are strongly detrimental to the luminescence properties. Thus, coupled chemical analyses and luminescence characterizations showed the high chemical homogeneity of the resulting powders and their intense emissions in the whole visible range. These emissions can be tuned from blue to warm white by adjusting the calcination temperature that is an important advantage for the development of LED devices. We showed that impurities of monovalent and divalent cations act as quenching emission centers for these phosphors. Therefore, by increasing the purity grade, we significantly enhanced the PL emissions leading to high internal quantum yields (80-90%). Finally, cathodoluminescence emissions showed the homogeneous dispersion of emitting centers in the g-YAB matrix.

  15. Aluminum alloy

    NASA Technical Reports Server (NTRS)

    Blackburn, Linda B. (Inventor); Starke, Edgar A., Jr. (Inventor)

    1989-01-01

    This invention relates to aluminum alloys, particularly to aluminum-copper-lithium alloys containing at least about 0.1 percent by weight of indium as an essential component, which are suitable for applications in aircraft and aerospace vehicles. At least about 0.1 percent by weight of indium is added as an essential component to an alloy which precipitates a T1 phase (Al2CuLi). This addition enhances the nucleation of the precipitate T1 phase, producing a microstructure which provides excellent strength as indicated by Rockwell hardness values and confirmed by standard tensile tests.

  16. An observer based approach for achieving fault diagnosis and fault tolerant control of systems modeled as hybrid Petri nets.

    PubMed

    Renganathan, K; Bhaskar, VidhyaCharan

    2011-07-01

    In this paper, we propose an approach for achieving detection and identification of faults, and provide fault tolerant control for systems that are modeled using timed hybrid Petri nets. For this purpose, an observer based technique is adopted which is useful in detection of faults, such as sensor faults, actuator faults, signal conditioning faults, etc. The concepts of estimation, reachability and diagnosability have been considered for analyzing faulty behaviors, and based on the detected faults, different schemes are proposed for achieving fault tolerant control using optimization techniques. These concepts are applied to a typical three tank system and numerical results are obtained.

  17. Finite Time Fault Tolerant Control for Robot Manipulators Using Time Delay Estimation and Continuous Nonsingular Fast Terminal Sliding Mode Control.

    PubMed

    Van, Mien; Ge, Shuzhi Sam; Ren, Hongliang

    2016-04-28

    In this paper, a novel finite time fault tolerant control (FTC) is proposed for uncertain robot manipulators with actuator faults. First, a finite time passive FTC (PFTC) based on a robust nonsingular fast terminal sliding mode control (NFTSMC) is investigated. Be analyzed for addressing the disadvantages of the PFTC, an AFTC are then investigated by combining NFTSMC with a simple fault diagnosis scheme. In this scheme, an online fault estimation algorithm based on time delay estimation (TDE) is proposed to approximate actuator faults. The estimated fault information is used to detect, isolate, and accommodate the effect of the faults in the system. Then, a robust AFTC law is established by combining the obtained fault information and a robust NFTSMC. Finally, a high-order sliding mode (HOSM) control based on super-twisting algorithm is employed to eliminate the chattering. In comparison to the PFTC and other state-of-the-art approaches, the proposed AFTC scheme possess several advantages such as high precision, strong robustness, no singularity, less chattering, and fast finite-time convergence due to the combined NFTSMC and HOSM control, and requires no prior knowledge of the fault due to TDE-based fault estimation. Finally, simulation results are obtained to verify the effectiveness of the proposed strategy.

  18. Closed-Loop HIRF Experiments Performed on a Fault Tolerant Flight Control Computer

    NASA Technical Reports Server (NTRS)

    Belcastro, Celeste M.

    1997-01-01

    ABSTRACT Closed-loop HIRF experiments were performed on a fault tolerant flight control computer (FCC) at the NASA Langley Research Center. The FCC used in the experiments was a quad-redundant flight control computer executing B737 Autoland control laws. The FCC was placed in one of the mode-stirred reverberation chambers in the HIRF Laboratory and interfaced to a computer simulation of the B737 flight dynamics, engines, sensors, actuators, and atmosphere in the Closed-Loop Systems Laboratory. Disturbances to the aircraft associated with wind gusts and turbulence were simulated during tests. Electrical isolation between the FCC under test and the simulation computer was achieved via a fiber optic interface for the analog and discrete signals. Closed-loop operation of the FCC enabled flight dynamics and atmospheric disturbances affecting the aircraft to be represented during tests. Upset was induced in the FCC as a result of exposure to HIRF, and the effect of upset on the simulated flight of the aircraft was observed and recorded. This paper presents a description of these closed- loop HIRF experiments, upset data obtained from the FCC during these experiments, and closed-loop effects on the simulated flight of the aircraft.

  19. Dissolution and Separation of Aluminum and Aluminosilicates

    SciTech Connect

    McFarlane, Joanna; Benker, Dennis; DePaoli, David W.; Felker, Leslie Kevin; Mattus, Catherine H.

    2015-12-19

    The selection of an aluminum alloy for target irradiation affects post-irradiation target dissolution and separations. Recent tests with aluminum alloy 6061 yielded greater than expected precipitation in the dissolver, forming up to 10 wt.% solids of aluminum hydroxides and aluminosilicates. Aluminosilicate dissolution presents challenges in a number of different areas, metals extraction from minerals, flyash treatment, and separations from aluminum alloys. We present experimental work that attempts to maximize dissolution of aluminum metal, along with silicon, magnesium, and copper impurities, through control of temperature, the rate of reagent addition, and incubation time. Aluminum phase transformations have been identified as a function of time and temperature, using X-ray diffraction. Solutions have been analyzed using wet chemical methods and X-ray fluorescence. Our data have been compared with published calculations of aluminum phase diagrams. Approaches are given to enhance the dissolution of aluminum and aluminosilicate phases in caustic solution.

  20. Dissolution and Separation of Aluminum and Aluminosilicates

    DOE PAGES

    McFarlane, Joanna; Benker, Dennis; DePaoli, David W.; ...

    2015-12-19

    The selection of an aluminum alloy for target irradiation affects post-irradiation target dissolution and separations. Recent tests with aluminum alloy 6061 yielded greater than expected precipitation in the dissolver, forming up to 10 wt.% solids of aluminum hydroxides and aluminosilicates. Aluminosilicate dissolution presents challenges in a number of different areas, metals extraction from minerals, flyash treatment, and separations from aluminum alloys. We present experimental work that attempts to maximize dissolution of aluminum metal, along with silicon, magnesium, and copper impurities, through control of temperature, the rate of reagent addition, and incubation time. Aluminum phase transformations have been identified as amore » function of time and temperature, using X-ray diffraction. Solutions have been analyzed using wet chemical methods and X-ray fluorescence. Our data have been compared with published calculations of aluminum phase diagrams. Approaches are given to enhance the dissolution of aluminum and aluminosilicate phases in caustic solution.« less

  1. Parameters Controlling Dimensional Accuracy of Aluminum Extrusions Formed in Stretch Bending

    NASA Astrophysics Data System (ADS)

    Baringbing, Henry Ako; Welo, Torgeir

    2007-04-01

    For stretch formed components used in the automotive industry, such as bumper beams, it is of primary importance to control parameters affecting dimensional accuracy. The variations in geometry and mechanical properties induced in extrusion and stretch forming lead to subsequent dimensional inaccuracy of the final product. In this work, tensile and compression samples were taken at three different positions along AA7108W extruded profiles in order to determine material parameters for a constitutive model particularly suited for strong texture materials. In addition, geometry were measured and analyzed statistically in order to study its impact on local cross sectional distortions (sagging) and springback in stretch bending of a bumper beam. These full scale experiments were combined with analytical and numerical simulations to quantify the impact of each basic parameter on product quality. It is concluded that this methodology provides a means to systematically control the product quality by focusing on reducing the acceptance limits of the main parameters controlling basic mechanisms in stretch forming. Despite the assumptions and simplifications made in order to make the analytical expressions solvable, the approach has proven its capability in establishing accurate closed-form expressions including the main influential parameters.

  2. Redundant and fault-tolerant algorithms for real-time measurement and control systems for weapon equipment.

    PubMed

    Li, Dan; Hu, Xiaoguang

    2017-03-01

    Because of the high availability requirements from weapon equipment, an in-depth study has been conducted on the real-time fault-tolerance of the widely applied Compact PCI (CPCI) bus measurement and control system. A redundancy design method that uses heartbeat detection to connect the primary and alternate devices has been developed. To address the low successful execution rate and relatively large waste of time slices in the primary version of the task software, an improved algorithm for real-time fault-tolerant scheduling is proposed based on the Basic Checking available time Elimination idle time (BCE) algorithm, applying a single-neuron self-adaptive proportion sum differential (PSD) controller. The experimental validation results indicate that this system has excellent redundancy and fault-tolerance, and the newly developed method can effectively improve the system availability.

  3. Aluminum phosphide

    Integrated Risk Information System (IRIS)

    Aluminum phosphide ; CASRN 20859 - 73 - 8 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinoge

  4. An improved fault-tolerant control scheme for PWM inverter-fed induction motor-based EVs.

    PubMed

    Tabbache, Bekheïra; Benbouzid, Mohamed; Kheloui, Abdelaziz; Bourgeot, Jean-Matthieu; Mamoune, Abdeslam

    2013-11-01

    This paper proposes an improved fault-tolerant control scheme for PWM inverter-fed induction motor-based electric vehicles. The proposed strategy deals with power switch (IGBTs) failures mitigation within a reconfigurable induction motor control. To increase the vehicle powertrain reliability regarding IGBT open-circuit failures, 4-wire and 4-leg PWM inverter topologies are investigated and their performances discussed in a vehicle context. The proposed fault-tolerant topologies require only minimum hardware modifications to the conventional off-the-shelf six-switch three-phase drive, mitigating the IGBTs failures by specific inverter control. Indeed, the two topologies exploit the induction motor neutral accessibility for fault-tolerant purposes. The 4-wire topology uses then classical hysteresis controllers to account for the IGBT failures. The 4-leg topology, meanwhile, uses a specific 3D space vector PWM to handle vehicle requirements in terms of size (DC bus capacitors) and cost (IGBTs number). Experiments on an induction motor drive and simulations on an electric vehicle are carried-out using a European urban driving cycle to show that the proposed fault-tolerant control approach is effective and provides a simple configuration with high performance in terms of speed and torque responses.

  5. Thymus-derived regulatory T cells control tolerance to commensal microbiota

    PubMed Central

    Cebula, Anna; Seweryn, Michal; Rempala, Grzegorz A.; Pabla, Simarjot Singh; McIndoe, Richard A.; Denning, Timothy L.; Bry, Lynn; Kraj, Piotr; Kisielow, Pawel; Ignatowicz, Leszek

    2013-01-01

    Peripheral mechanisms preventing autoimmunity and maintaining tolerance to commensal microbiota involve CD4+Foxp3+ regulatory T cells1,2 generated in the thymus (tTregs) or extrathymically by induction of naive CD4+Foxp3− T cells (iTregs). Prior studies suggested that the T cell receptor (TCR) repertoires of tTregs and iTregs are biased towards self and non-self antigens, respectively 3–6 but their relative contribution in controlling immunopathology, e.g. colitis and other untoward inflammatory responses triggered by different types of antigens, remains unresolved 7. The intestine, and especially the colon, is a particularly suitable organ to study this question, given the variety of self-, microbiota- and food-derived antigens to which Tregs and other T cell populations are exposed. Intestinal environments can enhance conversion to a regulatory lineage 8,9 and favor tolerogenic presentation of antigens to naive CD4+ T cells 10,11, suggesting that intestinal homeostasis depends on microbiota-specific iTregs 12–15. Here, to identify the origin and antigen-specificity of intestinal Tregs, we performed single cell as well as high-throughput (HT) sequencing of the TCR repertoires of CD4+Foxp3+ and CD4+Foxp3− T cells and analyzed their reactivity against specific commensal species. We show that tTregs constitute the majority of Tregs in all lymphoid and intestinal organs, including colon, where their repertoire is heavily influenced by the composition of the microbiota. Our results suggest that tTregs, and not iTregs, dominantly mediate tolerance to antigens produced by intestinal commensals. PMID:23624374

  6. Burkholderia acidipaludis sp. nov., aluminum-tolerant bacteria isolated from Chinese water chestnut (Eleocharis dulcis) growing in highly acidic swamps in South-East Asia.

    PubMed

    Aizawa, Tomoko; Bao Ve, Nguyen; Vijarnsorn, Pisoot; Nakajima, Mutsuyasu; Sunairi, Michio

    2010-09-01

    Two strains of aluminium-tolerant bacteria, SA33(T) and 7A078, were isolated from Chinese water chestnut (Eleocharis dulcis) growing in highly acidic swamps (pH 2-4) in actual acid sulfate soil areas of Vietnam (SA33(T)) and Thailand (7A078). The strains were Gram-negative, aerobic, non-spore-forming rods, 0.6-0.7 mum wide and 1.3-1.7 mum long. These strains showed good growth at pH 3.0-8.0 and 17-37 degrees C. The organisms contained ubiquinone Q-8 as the predominant isoprenoid quinone and C(16 : 0), C(18 : 1) ω 7c and C(17 : 0) cyclo as the major fatty acids. Their fatty acid profiles were similar to those reported for other Burkholderia species. The DNA G+C content of these strains was 64 mol%. On the basis of 16S rRNA gene sequence similarity, the strains were shown to belong to the genus Burkholderia. Although the 16S rRNA gene sequence similarity values calculated for strain SA33(T) to 7A078 and the type strains of Burkholderia kururiensis, B. sacchari and B. tuberum were 100, 97.3, 97.1 and 97.0 %, respectively, strains SA33(T) and 7A078 formed a group that was distinct in the phylogenetic trees; the DNA-DNA relatedness of strain SA33(T) to 7A078 and these three type strains were respectively 90, 47, 46 and 45 %. The results of physiological and biochemical tests, including whole-cell protein pattern analysis, allowed phenotypic differentiation of these strains from described Burkholderia species. Therefore, strains SA33(T) and 7A078 represent a novel species, for which the name Burkholderia acidipaludis sp. nov. is proposed. The type strain is SA33(T) (=NBRC 101816(T) =VTCC-D6-6(T)). Strain 7A078 (=NBRC 103872 =BCC 36999) is a reference strain.

  7. A Direct Design from Input/Output Data of Fault-Tolerant Control System Based on GIMC Structure

    NASA Astrophysics Data System (ADS)

    Sakuishi, Tsubasa; Yubai, Kazuhiro; Hirai, Junji

    This paper deals with a design method of fault-tolerant control system based on Generalized Internal Model Control (GIMC) structure consisting of a standard outer loop feedback controller and an extra inner loop controller. The distinguished feature of GIMC structure is that the controller design for performance and robustness may be done separately. The outer loop controller is designed for nominal performance using some controller synthesis to meet (nominal) control specification, while the inner loop controller is designed to make a trade-off between robustness and performance. This feature is suitable for fault-tolerant control. The outer loop controller is designed for fault-free case, and the inner loop controller for faulty case. In the conventional methods, the inner loop controller is designed to maximize the robust stability margin without information on fault. Therefore, the performance in the faulty case tends to become conservative. In this paper, the inner loop controller is directly designed from experimental data collected from the faulty system. Since the collected data contains information on the fault, conservativeness in the conventional methods is decreased. The inner loop controller is designed by Virtual Reference Feedback Tuning (VRFT). VRFT is a direct design method from input-output data without identifying any models. Since complexity of the controller can be specified by the designer, no complexity reduction has to be required, which becomes advantageous upon implementation. The effectiveness of the proposed design method is confirmed by an experiment.

  8. Mineralogical controls on aluminum and magnesium in uranium mill tailings: Key Lake, Saskatchewan, Canada.

    PubMed

    Gomez, M A; Hendry, M J; Koshinsky, J; Essilfie-Dughan, J; Paikaray, S; Chen, J

    2013-07-16

    The mineralogy and evolution of Al and Mg in U mill tailings are poorly understood. Elemental analyses (ICP-MS) of both solid and aqueous phases show that precipitation of large masses of secondary Al and Mg mineral phases occurs throughout the raffinate neutralization process (pH 1-11) at the Key Lake U mill, Saskatchewan, Canada. Data from a suite of analytical methods (ICP-MS, EMPA, laboratory- and synchrotron-based XRD, ATR-IR, Raman, TEM, EDX, ED) and equilibrium thermodynamic modeling showed that nanoparticle-sized, spongy, porous, Mg-Al hydrotalcite is the dominant mineralogical control on Al and Mg in the neutralized raffinate (pH ≥ 6.7). The presence of this secondary Mg-Al hydrotalcite in mineral samples of both fresh and 15-year-old tailings indicates that the Mg-Al hydrotalcite is geochemically stable, even after >16 years in the oxic tailings body. Data shows an association between the Mg-Al hydrotalcite and both As and Ni and point to this Mg-Al hydrotalcite exerting a mineralogical control on the solubility of these contaminants.

  9. Control and elimination of cracking in aluminum(0.20) gallium(0.80) nitrogen using aluminum(x) gallium(1-x) nitrogen interlayers and application toward a near ultraviolet vertical cavity surface emitting laser

    NASA Astrophysics Data System (ADS)

    Waldrip, Karen Elizabeth

    Thin film heterostructures based on aluminum gallium nitride and gallium nitride are of particular interest for applications such as ultraviolet light emitters and detectors. Due to the elastic mismatch strain between the materials, the AlGaN films tend to crack at thicknesses and aluminum compositions that are useful for device fabrication (e.g., 0.1 mum at 10% AlN mole fraction), and cracking has been shown to be deleterious to device performance. In this work, a method has been developed to control and eliminate cracking in 0.9-mum thick Al0.20Ga0.80N films grown on GaN by inserting a thin layer of AlxGa1-xN between the Al 0.20Ga0.80N and GaN films grown by metalorganic chemical vapor deposition. The strain state of the thin interlayers is determined through a combination of in situ and ex situ characterization techniques. It is shown that the interlayer partially relaxes through the nucleation and glide of misfit dislocations to the interlayer/GaN interface, and that although the edge dislocation content in AlGaN overlayers increases by a factor of 5--10, screw dislocations from GaN underlayers are filtered by the interlayer. The number of excess threading dislocations present in AlGaN overlayers can be manipulated by controlling the amount of relaxation of the AlGaN interlayers, which can in turn be controlled by the morphology of the interlayer. It has been found that the morphology of the interlayer is affected by a combination of the strain and the aluminum surface mobility during growth, which can be controlled by adjusting growth parameters such as interlayer composition, growth temperature, interlayer thickness, and V/III ratio. These parameters are explored and guidelines for choosing an interlayer composition, thickness, and morphology are outlined based on the chosen end application for the AlGaN overlayer. Finally, the interlayer technique is applied towards the development of the world's first (at time of announcement) room temperature, quasi

  10. Control of surface defects on plasma-MIG hybrid welds in cryogenic aluminum alloys

    NASA Astrophysics Data System (ADS)

    Lee, Hee-Keun; Chun, Kwang-San; Park, Sang-Hyeon; Kang, Chung-Yun

    2015-07-01

    Lately, high production rate welding processes for Al alloys, which are used as LNG FPSO cargo containment system material, have been developed to overcome the limit of installation and high rework rates. In particular, plasma-metal inert gas (MIG) hybrid (PMH) welding can be used to obtain a higher deposition rate and lower porosity, while facilitating a cleaning effect by preheating and post heating the wire and the base metal. However, an asymmetric undercut and a black-colored deposit are created on the surface of PMH weld in Al alloys. For controlling the surface defect formation, the wire feeding speed and nozzle diameter in the PMH weld was investigated through arc phenomena with high-speed imaging and metallurgical analysis.

  11. Brassinosteroids participate in the control of basal and acquired freezing tolerance of plants.

    PubMed

    Eremina, Marina; Unterholzner, Simon J; Rathnayake, Ajith I; Castellanos, Marcos; Khan, Mamoona; Kugler, Karl G; May, Sean T; Mayer, Klaus F X; Rozhon, Wilfried; Poppenberger, Brigitte

    2016-10-04

    Brassinosteroids (BRs) are growth-promoting plant hormones that play a role in abiotic stress responses, but molecular modes that enable this activity remain largely unknown. Here we show that BRs participate in the regulation of freezing tolerance. BR signaling-defective mutants of Arabidopsis thaliana were hypersensitive to freezing before and after cold acclimation. The constitutive activation of BR signaling, in contrast, enhanced freezing resistance. Evidence is provided that the BR-controlled basic helix-loop-helix transcription factor CESTA (CES) can contribute to the constitutive expression of the C-REPEAT/DEHYDRATION-RESPONSIVE ELEMENT BINDING FACTOR (CBF) transcriptional regulators that control cold responsive (COR) gene expression. In addition, CBF-independent classes of BR-regulated COR genes are identified that are regulated in a BR- and CES-dependent manner during cold acclimation. A model is presented in which BRs govern different cold-responsive transcriptional cascades through the posttranslational modification of CES and redundantly acting factors. This contributes to the basal resistance against freezing stress, but also to the further improvement of this resistance through cold acclimation.

  12. Fault tolerant cooperative control for UAV rendezvous problem subject to actuator faults

    NASA Astrophysics Data System (ADS)

    Jiang, T.; Meskin, N.; Sobhani-Tehrani, E.; Khorasani, K.; Rabbath, C. A.

    2007-04-01

    This paper investigates the problem of fault tolerant cooperative control for UAV rendezvous problem in which multiple UAVs are required to arrive at their designated target despite presence of a fault in the thruster of any UAV. An integrated hierarchical scheme is proposed and developed that consists of a cooperative rendezvous planning algorithm at the team level and a nonlinear fault detection and isolation (FDI) subsystem at individual UAV's actuator/sensor level. Furthermore, a rendezvous re-planning strategy is developed that interfaces the rendezvous planning algorithm with the low-level FDI. A nonlinear geometric approach is used for the FDI subsystem that can detect and isolate faults in various UAV actuators including thrusters and control surfaces. The developed scheme is implemented for a rendezvous scenario with three Aerosonde UAVs, a single target, and presence of a priori known threats. Simulation results reveal the effectiveness of our proposed scheme in fulfilling the rendezvous mission objective that is specified as a successful intercept of Aerosondes at their designated target, despite the presence of severe loss of effectiveness in Aerosondes engine thrusters.

  13. Filtering and fault tolerant control of parameter-varying time-delay systems and applications

    NASA Astrophysics Data System (ADS)

    Mohammadpour Velni, Javad

    This dissertation addresses some open problems in control systems theory. The problems considered include the dynamic controller and filter design for Linear Parameter Varying (LPV) time-delay systems, the reconfigurable control design in Fault Tolerant Control Systems (FTCS) and fault diagnostics in Diesel engines. In the first part of this thesis, we investigate the problem of designing parameter-dependent filters for output estimation of LPV time-delay systems. The filters are designed such that the filtering error system guarantees an optimum level of H2 or Hinfinity performance. A state-delay term is included in the filter dynamics to reduce the design conservatism and improve the performance. The Linear Matrix Inequality (LMI)-based synthesis conditions developed for the filter design purposes are categorized into the rate-dependent and delay-dependent conditions which could handle the time-varying state-delay and bounded small delay cases, respectively. Among these two, the latter one is shown to provide a significant reduction in the conservativeness in the filter design. The second part of the thesis examines the analysis and synthesis of Fault Tolerant Control (FTC) systems in an LPV framework. For reconfigurable control design purposes, the information from Fault Detection and Isolation (FDI) module, that provides an estimate of the fault parameters, is utilized to schedule the controller matrices. We will also present a formulation that incorporates the factor of detection delay in the FTC supervisory system. It is shown that including this delay in the synthesis conditions leads to improved performance and reduced control effort. For analysis of the FTC systems including time-delay, where the fault parameters might be identified inaccurately, we first introduce the notion of brief instability for LPV time-delay systems. In these systems it is possible that the output trajectory converges to zero even though there are parameter trajectories for which

  14. Efficacy and tolerability of oxycodone versus fentanyl for intravenous patient-controlled analgesia after gastrointestinal laparotomy

    PubMed Central

    Ding, Zhen; Wang, Kaiguo; Wang, Baosheng; Zhou, Naibao; Li, Hao; Yan, Bo

    2016-01-01

    Abstract Background: It has been suggested that oxycodone is effective in relieving acute postoperative pain. The aim of this study was to investigate the efficacy and tolerability of oxycodone (O) versus fentanyl (F), and the adequate potency ratio of oxycodone and fentanyl in patients with intravenous patient-controlled analgesia after gastric laparotomy. Methods: In this double-blinded, randomized, controlled study, 60 patients undergoing elective gastric laparotomy were allocated to receive either oxycodone or fentanyl for postoperative intravenous patient-controlled analgesia (potency ratio 60:1). The patients received ketorolac 60 mg before the end of anesthesia and then continued with patient-controlled analgesia for 48 hours postsurgery. Pain severity, side effects and respiration rate were recorded 30 minutes, 3, 6, 12, 24, and 48 hours after the surgery. Cumulative opioid requirements and patient satisfaction were also measured. Results: The median consumption more than 48 hours after operation of oxycodone was 50 mg (range: 40.0–62.4 mg) and fentanyl was 0.8 mg (range: 0.6–1.1 mg), and the percentage of patients requiring rescue medication was not statistically significant. Numeric rating scores at rest and upon movement were significantly lower in group O than in F (P < 0.05). Whereas the incidences of adverse events were similar between the groups (33.3% vs 27.6%, P = 0.64), a significant higher sedation scores were found in patients given fentanyl at 30 minutes after the surgery (P = 0.04). Conclusion: Oxycodone was comparable to fentanyl in the relief of postoperative pain following gastric laparotomy. Oxycodone not only provides better postoperative pain relief and less sedation, but also there was a tendency toward more side effects with oxycodone. PMID:27684835

  15. The Efficacy and Tolerability of ‘Polypills’: Meta-Analysis of Randomised Controlled Trials

    PubMed Central

    Elley, C Raina; Gupta, Ajay K.; Webster, Ruth; Selak, Vanessa; Jun, Min; Patel, Anushka; Rodgers, Anthony; Thom, Simon

    2012-01-01

    Background To assess the blood pressure and lipid-lowering efficacy and tolerability of ‘polypills’ used in cardiovascular disease prevention trials. Methodology/Principal Findings Systematic review and meta-analysis. Search strategy: The Cochrane Central Register of Controlled Trials, Medline, and PubMed databases were searched for eligible trials. Study inclusion criteria: Randomised controlled trials of at least six weeks duration, which compared a ‘polypill’ (that included at least one anti-hypertensive and one lipid-lowering medication) with a placebo (or one active component). Outcome measures: Change from baseline in systolic and diastolic blood pressures, and total and LDL-cholesterol; discontinuation of study medication and reported adverse effects. Of 44 potentially eligible studies, six trials (including 2,218 patients without previous cardiovascular disease) fulfilled the inclusion criteria. Compared with placebo, ‘polypills’ reduced systolic blood pressure by −9.2 mmHg (95% confidence interval (CI): −13.4, −5.0) diastolic blood pressure by −5.0 mmHg (95%CI: −7.4, −2.6), total cholesterol by −1.22 mmol/L (95%CI: −1.60, −0.84) and LDL-cholesterol by −1.02 mmol/L (95%CI: −1.37, −0.67). However, those taking a ‘polypill’ (vs. placebo or component) were more likely to discontinue medication (20% vs 14%) (Odds ratio: 1.5 (95% CI: 1.2, 1.9)). There was no significant difference in reported adverse effects amongst those on a ‘polypill’ (36% vs. 28%) (OR: 1.3 (95%CI: 0.7, 2.5)). There was high statistical heterogeneity in comparisons for blood pressure and lipid-lowering but use of random-effects and quality-effects models produced very similar results. Conclusions/Significance Compared with placebo, the ‘polypills’ reduced blood pressure and lipids. Tolerability was lower amongst those on ‘polypills’ than those on placebo or one component, but differences were moderate. Effectiveness trials are needed to help

  16. A review on prevalence, control measure, and tolerance of Tanzania Shorthorn Zebu cattle to East Coast fever in Tanzania.

    PubMed

    Laisser, E L K; Chenyambuga, S W; Karimuribo, E D; Msalya, G; Kipanyula, M J; Mwilawa, A J; Mdegela, R H; Kusiluka, L J M

    2017-04-01

    In Tanzania, control of East Coast fever (ECF) has predominantly relied on tick control using acaricides and chemotherapy, little on ECF vaccination, and very little on dissemination regarding animal immunization. In this paper, the prevalence, control measure, and tolerance of Tanzania Shorthorn Zebu (TSHZ) cattle to ECF are reviewed. In addition, the opportunities available for reducing the use of acaricides for the benefit of the farmers in terms of reduction of costs of purchasing acaricides and environmental pollution are described. The tick distribution and epidemiological factors for ECF such as the agro-ecological zones (AEZ), livestock production systems (LPS), strain, and age of the animals are also described. These factors influence the epidemiology of ECF and the distribution of TSHZ strains in different geographic locations of Tanzania. We have further showed that there is a tendency of farmers to select among the strains of TSHZ for animals which can tolerate ticks and ECF and crossbreed them with their local strains with the aim of benefiting from the inherent characteristics of the most tolerant strains. Generally, many strains of TSHZ cattle are tolerant to tick infestation and ECF infection and can be bred to respond to the needs of the people. In this review paper, we recommend that in future, ECF epidemiological studies should account for factors such as livestock production system, agro-climate, breed of animal, tick control strategy, and the dynamic interactions between them. In conclusion, we have demonstrated that an integrated control method involving use of acaricides, immunization, and ECF-tolerant/-resistant animals is required.

  17. Genetic mapping of a 7R Al tolerance QTL in triticale (x Triticosecale Wittmack).

    PubMed

    Niedziela, A; Bednarek, P T; Labudda, M; Mańkowski, D R; Anioł, A

    2014-02-01

    Triticale (x Triticosecale Wittmack) is a relatively new cereal crop. In Poland, triticale is grown on 12 % of arable land ( http://www.stat.gov.pl ). There is an increasing interest in its cultivation due to lowered production costs and increased adaptation to adverse environmental conditions. However, it has an insufficient tolerance to the presence of aluminum ions (Al(3+)) in the soil. The number of genes controlling aluminum tolerance in triticale and their chromosomal location is not known. Two F2 mapping biparental populations (MP1 and MP15) segregating for aluminum (Al) tolerance were tested with AFLP, SSR, DArT, and specific PCR markers. Genetic mapping enabled the construction of linkage groups representing chromosomes 7R, 5R and 2B. Obtained linkage groups were common for both mapping populations and mostly included the same markers. Composite interval mapping (CIM) allowed identification of a single QTL that mapped to the 7R chromosome and explained 25 % (MP1) and 36 % (MP15) of phenotypic variation. The B1, B26 and Xscm150 markers were 0.04 cM and 0.02 cM from the maximum of the LOD function in the MP1 and MP15, respectively and were highly associated with aluminum tolerance as indicated by Kruskal-Wallis nonparametric test. Moreover, the molecular markers B1, B26, Xrems1162 and Xscm92, previously associated with the Alt4 locus that encoded an aluminum-activated malate transporter (ScALMT1) that was involved in Al tolerance in rye (Secale cereale) also mapped within QTL. Biochemical analysis of plants represented MP1 and MP15 mapping populations confirmed that the QTL located on 7R chromosome in both mapping populations is responsible for Al tolerance.

  18. Dual-quaternion based fault-tolerant control for spacecraft formation flying with finite-time convergence.

    PubMed

    Dong, Hongyang; Hu, Qinglei; Ma, Guangfu

    2016-03-01

    Study results of developing control system for spacecraft formation proximity operations between a target and a chaser are presented. In particular, a coupled model using dual quaternion is employed to describe the proximity problem of spacecraft formation, and a nonlinear adaptive fault-tolerant feedback control law is developed to enable the chaser spacecraft to track the position and attitude of the target even though its actuator occurs fault. Multiple-task capability of the proposed control system is further demonstrated in the presence of disturbances and parametric uncertainties as well. In addition, the practical finite-time stability feature of the closed-loop system is guaranteed theoretically under the designed control law. Numerical simulation of the proposed method is presented to demonstrate the advantages with respect to interference suppression, fast tracking, fault tolerant and practical finite-time stability.

  19. A previously unknown zinc finger protein, DST, regulates drought and salt tolerance in rice via stomatal aperture control

    PubMed Central

    Huang, Xin-Yuan; Chao, Dai-Yin; Gao, Ji-Ping; Zhu, Mei-Zhen; Shi, Min; Lin, Hong-Xuan

    2009-01-01

    Abiotic stresses, such as drought and salinity, lead to crop growth damage and a decrease in crop yields. Stomata control CO2 uptake and optimize water use efficiency, thereby playing crucial roles in abiotic stress tolerance. Hydrogen peroxide (H2O2) is an important signal molecule that induces stomatal closure. However, the molecular pathway that regulates the H2O2 level in guard cells remains largely unknown. Here, we clone and characterize DST (drought and salt tolerance)—a previously unknown zinc finger transcription factor that negatively regulates stomatal closure by direct modulation of genes related to H2O2 homeostasis—and identify a novel pathway for the signal transduction of DST-mediated H2O2-induced stomatal closure. Loss of DST function increases stomatal closure and reduces stomatal density, consequently resulting in enhanced drought and salt tolerance in rice. These findings provide an interesting insight into the mechanism of stomata-regulated abiotic stress tolerance, and an important genetic engineering approach for improving abiotic stress tolerance in crops. PMID:19651988

  20. A previously unknown zinc finger protein, DST, regulates drought and salt tolerance in rice via stomatal aperture control.

    PubMed

    Huang, Xin-Yuan; Chao, Dai-Yin; Gao, Ji-Ping; Zhu, Mei-Zhen; Shi, Min; Lin, Hong-Xuan

    2009-08-01

    Abiotic stresses, such as drought and salinity, lead to crop growth damage and a decrease in crop yields. Stomata control CO(2) uptake and optimize water use efficiency, thereby playing crucial roles in abiotic stress tolerance. Hydrogen peroxide (H(2)O(2)) is an important signal molecule that induces stomatal closure. However, the molecular pathway that regulates the H(2)O(2) level in guard cells remains largely unknown. Here, we clone and characterize DST (drought and salt tolerance)-a previously unknown zinc finger transcription factor that negatively regulates stomatal closure by direct modulation of genes related to H(2)O(2) homeostasis-and identify a novel pathway for the signal transduction of DST-mediated H(2)O(2)-induced stomatal closure. Loss of DST function increases stomatal closure and reduces stomatal density, consequently resulting in enhanced drought and salt tolerance in rice. These findings provide an interesting insight into the mechanism of stomata-regulated abiotic stress tolerance, and an important genetic engineering approach for improving abiotic stress tolerance in crops.

  1. Interplay between reactive oxygen species and hormones in the control of plant development and stress tolerance.

    PubMed

    Xia, Xiao-Jian; Zhou, Yan-Hong; Shi, Kai; Zhou, Jie; Foyer, Christine H; Yu, Jing-Quan

    2015-05-01

    As a consequence of a sessile lifestyle, plants are continuously exposed to changing environmental conditions and often life-threatening stresses caused by exposure to excessive light, extremes of temperature, limiting nutrient or water availability, and pathogen/insect attack. The flexible coordination of plant growth and development is necessary to optimize vigour and fitness in a changing environment through rapid and appropriate responses to such stresses. The concept that reactive oxygen species (ROS) are versatile signalling molecules in plants that contribute to stress acclimation is well established. This review provides an overview of our current knowledge of how ROS production and signalling are integrated with the action of auxin, brassinosteroids, gibberellins, abscisic acid, ethylene, strigolactones, salicylic acid, and jasmonic acid in the coordinate regulation of plant growth and stress tolerance. We consider the local and systemic crosstalk between ROS and hormonal signalling pathways and identify multiple points of reciprocal control, as well as providing insights into the integration nodes that involve Ca(2+)-dependent processes and mitogen-activated protein kinase phosphorylation cascades.

  2. New method for the controlled creation of sub-15 nm aluminum nanowires to probe the 1D superconductor-insulator transition

    NASA Astrophysics Data System (ADS)

    Morgan-Wall, Tyler; Hughes, Hannah; Hartman, Nik; McQueen, Tyrell; Markovic, Nina

    2014-03-01

    We have developed a new method for the creation of sub-15 nm aluminum nanostructures using a sodium bicarbonate solution. Using PMMA masks patterned with e-beam lithography, we can controllably etch lithographically-produced nanostructures while measuring their resistances in-situ using a 4-probe measurement. This technique allows for precise control over the final resistance and thus can be used to create a wide variety of nanodevices. In particular, this technique allows for the creation of nanowires to probe the superconductor-insulator transition in 1D.

  3. Size- and shape-controlled synthesis and catalytic performance of iron-aluminum mixed oxide nanoparticles for NOX and SO₂ removal with hydrogen peroxide.

    PubMed

    Ding, Jie; Zhong, Qin; Zhang, Shule; Cai, Wei

    2015-01-01

    A novel, simple, reproducible and low-cost strategy is introduced for the size- and shape-controlled synthesis of iron-aluminum mixed oxide nanoparticles (NIAO(x/y)). The as-synthesized NIAO(x/y) catalyze decomposition of H2O2 yielding highly reactive hydroxyl radicals (OH) for NOX and SO2 removal. 100% SO2 removal is achieved. NIAO(x/y) with Fe/Al molar ratio of 7/3 (NIAO(7/3)) shows the highest NOX removal of nearly 80% at >170°C, whereas much lower NOX removal (<63%) is obtained for NIAO(3/7). The melting of aluminum oxides in NIAO(7/3) promotes the formation of lamellar products, thus improving the specific surface areas and mesoporous distribution, benefiting the production of OH radicals. Furthermore, the NIAO(7/3) leads to the minor increase of points of zero charges (PZC), apparent enhancement of FeOH content and high oxidizing ability of Fe(III), further improving the production of OH radicals. However, the NIAO(3/7) results in the formation of aluminum surface-enriched spherical particles, thus decreasing the surface atomic ratio of iron oxides, decreasing OH radical production. More importantly, the generation of FeOAl causes the decline of active sites. Finally, the catalytic decomposition of H2O2 on NIAO(x/y) is proposed. And the well catalytic stability of NIAO(7/3) is obtained for evaluation of 30 h.

  4. Weed control changes and genetically modified herbicide tolerant crops in the USA 1996-2012.

    PubMed

    Brookes, Graham

    2014-01-01

    Crops that have been genetically modified (GM) to be tolerant to herbicides have been widely grown in the USA since 1996. The rapid and widespread adoption of this technology reflects the important economic and environmental benefits that farmers have derived from its use (equal to $21.7 billion additional farm income and a 225 million kg reduction in herbicide active ingredient use 1996-2012). During this time, weed control practices in these crops relative to the 'conventional alternative' have evolved to reflect experience of using the technology, the challenges that have arisen and the increasing focus in recent years on developing sustainable production systems. This paper examines the evidence on the changing nature of herbicides used with these crops and in particular how farmers addressed the challenge of weed resistance. The evidence shows that use of the technology has resulted in a net reduction in both the amount of herbicide used and the associated environmental impact, as measured by the EIQ indicator when compared to what can reasonably be expected if the area planted to GM HT crops reverted to conventional production methods. It also facilitated many farmers being able to derive the economic and environmental benefits associated with switching from a plough-based to a no tillage or conservation tillage production system. In terms of herbicide use, the technology has also contributed to a change the profile of herbicides used. A broad range of, mostly selective herbicides has been replaced by one or 2 broad-spectrum herbicides (mostly glyphosate) used in conjunction with one or 2 other (complementary) herbicides. Since the mid-2000s, the average amount of herbicide applied and the associated environmental load, as measured by the EIQ indicator, have increased on both GM HT and conventional crops. A primary reason for these changes has been increasing incidence of weed species developing populations resistant to herbicides and increased awareness of

  5. Weed control changes and genetically modified herbicide tolerant crops in the USA 1996–2012

    PubMed Central

    Brookes, Graham

    2014-01-01

    Crops that have been genetically modified (GM) to be tolerant to herbicides have been widely grown in the USA since 1996. The rapid and widespread adoption of this technology reflects the important economic and environmental benefits that farmers have derived from its use (equal to $21.7 billion additional farm income and a 225 million kg reduction in herbicide active ingredient use 1996–2012). During this time, weed control practices in these crops relative to the ‘conventional alternative’ have evolved to reflect experience of using the technology, the challenges that have arisen and the increasing focus in recent years on developing sustainable production systems. This paper examines the evidence on the changing nature of herbicides used with these crops and in particular how farmers addressed the challenge of weed resistance. The evidence shows that use of the technology has resulted in a net reduction in both the amount of herbicide used and the associated environmental impact, as measured by the EIQ indicator when compared to what can reasonably be expected if the area planted to GM HT crops reverted to conventional production methods. It also facilitated many farmers being able to derive the economic and environmental benefits associated with switching from a plough-based to a no tillage or conservation tillage production system. In terms of herbicide use, the technology has also contributed to a change the profile of herbicides used. A broad range of, mostly selective herbicides has been replaced by one or 2 broad-spectrum herbicides (mostly glyphosate) used in conjunction with one or 2 other (complementary) herbicides. Since the mid-2000s, the average amount of herbicide applied and the associated environmental load, as measured by the EIQ indicator, have increased on both GM HT and conventional crops. A primary reason for these changes has been increasing incidence of weed species developing populations resistant to herbicides and increased

  6. Fault diagnosis and fault-tolerant finite control set-model predictive control of a multiphase voltage-source inverter supplying BLDC motor.

    PubMed

    Salehifar, Mehdi; Moreno-Equilaz, Manuel

    2016-01-01

    Due to its fault tolerance, a multiphase brushless direct current (BLDC) motor can meet high reliability demand for application in electric vehicles. The voltage-source inverter (VSI) supplying the motor is subjected to open circuit faults. Therefore, it is necessary to design a fault-tolerant (FT) control algorithm with an embedded fault diagnosis (FD) block. In this paper, finite control set-model predictive control (FCS-MPC) is developed to implement the fault-tolerant control algorithm of a five-phase BLDC motor. The developed control method is fast, simple, and flexible. A FD method based on available information from the control block is proposed; this method is simple, robust to common transients in motor and able to localize multiple open circuit faults. The proposed FD and FT control algorithm are embedded in a five-phase BLDC motor drive. In order to validate the theory presented, simulation and experimental results are conducted on a five-phase two-level VSI supplying a five-phase BLDC motor.

  7. Avoidance of stress corrosion susceptibility in high strength aluminum alloys by control of grain boundary and matrix microstructure

    NASA Technical Reports Server (NTRS)

    Adler, P.; Deiasi, R.

    1974-01-01

    The relation of microstructure to the mechanical strength and stress corrosion resistance of highest strength and overaged tempers of BAR and 7050 aluminum alloys was investigated. Comparison is made with previously studied 7075 aluminum alloy. Optical microscopy, transmission electron microscopy, and differential scanning calorimetry were used to characterize the grain morphology, matrix microstructure, and grain boundary microstructure of these tempers. Grain boundary interparticle spacing was significant to stress corrosion crack propagation for all three alloys; increasing interparticle spacing led to increased resistance to crack propagation. In addition, the fire grain size in Bar and 7050 appears to enhance crack propagation. The highest strength temper of 7050 has a comparatively high resistance to crack initiation. Overall stress corrosion behavior is dependent on environment pH, and evaluation over a range of pH is recommended.

  8. Aluminum tolerance in sorghum and maize

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The soils of the tropics and subtropics are highly weathered, leading to poor soil fertility and low soil pH. Root growth and function on these acid soils is impaired by aluminium (Al) toxicity, leading to yield instability that jeopardizes food security worldwide. A wealth of physiological evidence...

  9. Validation Methods Research for Fault-Tolerant Avionics and Control Systems Sub-Working Group Meeting. CARE 3 peer review

    NASA Technical Reports Server (NTRS)

    Trivedi, K. S. (Editor); Clary, J. B. (Editor)

    1980-01-01

    A computer aided reliability estimation procedure (CARE 3), developed to model the behavior of ultrareliable systems required by flight-critical avionics and control systems, is evaluated. The mathematical models, numerical method, and fault-tolerant architecture modeling requirements are examined, and the testing and characterization procedures are discussed. Recommendations aimed at enhancing CARE 3 are presented; in particular, the need for a better exposition of the method and the user interface is emphasized.

  10. Application of an alcohol clamp paradigm to examine inhibitory control, subjective responses, and acute tolerance in late adolescence.

    PubMed

    Hendershot, Christian S; Wardell, Jeffrey D; Strang, Nicole M; Markovich, Mike S D; Claus, Eric D; Ramchandani, Vijay A

    2015-06-01

    Individual differences in acute alcohol effects on cognitive control and subjective responses--and acute tolerance to these effects--are implicated in the risk for heavy drinking and alcohol-related harms. Few studies have examined these effects in drinkers under age 21. Additionally, studies of acute tolerance typically involve bolus oral alcohol administration, such that estimates of tolerance are confounded with blood alcohol concentration (BAC) limb. The current study examined cognitive control and subjective responses in young heavy drinkers (n = 88; M = 19.8 years old, SD = 0.8) during a single-session alcohol clamp protocol. Participants completed an intravenous alcohol session comprising an ascending limb (0 to 80 mg% in 20 min) and a BAC plateau (80 mg% for 80 min). Serial assessments included a cued go/no-go task and measures of stimulation, sedation, and craving. Relevant individual difference factors (attention-deficit hyperactivity disorder [ADHD] symptoms and sensation seeking) were examined as moderators. Multilevel modeling demonstrated that response inhibition worsened following initial rise in BAC and showed increasing impairment during the BAC plateau. ADHD symptoms and sensation seeking moderated this effect. Significant within-person associations between stimulation and craving were evident on the ascending limb only. Participants with higher ADHD symptoms reported steeper increases in stimulation during the ascending limb. These findings provide initial information about subjective and behavioral responses during pseudoconstant BAC, and potential moderators of these outcomes, in late adolescence. Additional studies with placebo-controlled designs are necessary to confirm these findings.

  11. Validation Methods Research for Fault-Tolerant Avionics and Control Systems: Working Group Meeting, 2

    NASA Technical Reports Server (NTRS)

    Gault, J. W. (Editor); Trivedi, K. S. (Editor); Clary, J. B. (Editor)

    1980-01-01

    The validation process comprises the activities required to insure the agreement of system realization with system specification. A preliminary validation methodology for fault tolerant systems documented. A general framework for a validation methodology is presented along with a set of specific tasks intended for the validation of two specimen system, SIFT and FTMP. Two major areas of research are identified. First, are those activities required to support the ongoing development of the validation process itself, and second, are those activities required to support the design, development, and understanding of fault tolerant systems.

  12. Tolerating Zero Tolerance?

    ERIC Educational Resources Information Center

    Moore, Brian N.

    2010-01-01

    The concept of zero tolerance dates back to the mid-1990s when New Jersey was creating laws to address nuisance crimes in communities. The main goal of these neighborhood crime policies was to have zero tolerance for petty crime such as graffiti or littering so as to keep more serious crimes from occurring. Next came the war on drugs. In federal…

  13. IMPROVEMENT OF SMVGEAR II ON VECTOR AND SCALAR MACHINES THROUGH ABSOLUTE ERROR TOLERANCE CONTROL (R823186)

    EPA Science Inventory

    The computer speed of SMVGEAR II was improved markedly on scalar and vector machines with relatively little loss in accuracy. The improvement was due to a method of frequently recalculating the absolute error tolerance instead of keeping it constant for a given set of chemistry. ...

  14. Phytochrome B control of total leaf area and stomatal density affects drought tolerance in rice.

    PubMed

    Liu, Jing; Zhang, Fang; Zhou, Jinjun; Chen, Fan; Wang, Baoshan; Xie, Xianzhi

    2012-02-01

    We report that phytochrome B (phyB) mutants exhibit improved drought tolerance compared to wild type (WT) rice (Oryza sativa L. cv. Nipponbare). To understand the underlying mechanism by which phyB regulates drought tolerance, we analyzed root growth and water loss from the leaves of phyB mutants. The root system showed no significant difference between the phyB mutants and WT, suggesting that improved drought tolerance has little relation to root growth. However, phyB mutants exhibited reduced total leaf area per plant, which was probably due to a reduction in the total number of cells per leaf caused by enhanced expression of Orysa;KRP1 and Orysa;KRP4 (encoding inhibitors of cyclin-dependent kinase complex activity) in the phyB mutants. In addition, the developed leaves of phyB mutants displayed larger epidermal cells than WT leaves, resulting in reduced stomatal density. phyB deficiency promoted the expression of both putative ERECTA family genes and EXPANSIN family genes involved in cell expansion in leaves, thus causing greater epidermal cell expansion in the phyB mutants. Reduced stomatal density resulted in reduced transpiration per unit leaf area in the phyB mutants. Considering all these findings, we propose that phyB deficiency causes both reduced total leaf area and reduced transpiration per unit leaf area, which explains the reduced water loss and improved drought tolerance of phyB mutants.

  15. Melatonin for Sleep in Children with Autism: A Controlled Trial Examining Dose, Tolerability, and Outcomes

    ERIC Educational Resources Information Center

    Malow, Beth; Adkins, Karen W.; McGrew, Susan G.; Wang, Lily; Goldman, Suzanne E.; Fawkes, Diane; Burnette, Courtney

    2012-01-01

    Supplemental melatonin has shown promise in treating sleep onset insomnia in children with autism spectrum disorders (ASD). Twenty-four children, free of psychotropic medications, completed an open-label dose-escalation study to assess dose-response, tolerability, safety, feasibility of collecting actigraphy data, and ability of outcome measures…

  16. Standardized Fault-Tolerant Sensing Nodes for an Intelligent Turbine Engine Control System (Preprint)

    DTIC Science & Technology

    2013-05-01

    Fault detection and isolation is improved. For example, when a thermocouple is malfunctioning, the problem...converting the analog voltage to a temperature (or pressure, or position etc.). Any electronic interface must have fault detection and isolation built...added benefits – Increase Noise Immunity – Sensor Calibration Made Easy – Fault Detection and Isolation – Fault Tolerance – Prognostic Functions

  17. Efficacy and tolerability of Hairgain in individuals with hair loss: a placebo-controlled, double-blind study.

    PubMed

    Thom, E

    2001-01-01

    This randomized, placebo-controlled, double-blind study was designed to investigate the efficacy and tolerability of a new agent for the treatment of hair loss, based on a marine protein, minerals and vitamins. Sixty subjects with hair loss of different aetiologies participated in the 6-month blinded phase of the study. Objective assessments indicated that the treatment was effective and subjective assessments showed a statistically significant positive effect of treatment. Exposure to the active preparation for a further 6 months in an open phase indicated a further improvement in hair growth. Exposure of the patients previously treated with placebo to the active preparation for 12 months gave similar results. Tolerability was good and no side-effects were reported. The product investigated may provide an alternative to pharmacotherapy for the treatment of hair-loss problems in individuals with androgenic alopecia.

  18. Design for aluminum recycling

    SciTech Connect

    Not Available

    1993-10-01

    This article describes the increasing use of aluminum in automobiles and the need to recycle to benefit further growth of aluminum applications by assuring an economical, high-quality source of metal. The article emphasizes that coordination of material specifications among designers can raise aluminum scrap value and facilitate recycling. Applications of aluminum in automobile construction are discussed.

  19. Decentralized Sliding Mode Observer Based Dual Closed-Loop Fault Tolerant Control for Reconfigurable Manipulator against Actuator Failure

    PubMed Central

    Zhao, Bo; Li, Yuanchun

    2015-01-01

    This paper considers a decentralized fault tolerant control (DFTC) scheme for reconfigurable manipulators. With the appearance of norm-bounded failure, a dual closed-loop trajectory tracking control algorithm is proposed on the basis of the Lyapunov stability theory. Characterized by the modularization property, the actuator failure is estimated by the proposed decentralized sliding mode observer (DSMO). Moreover, the actuator failure can be treated in view of the local joint information, so its control performance degradation is independent of other normal joints. In addition, the presented DFTC scheme is significantly simplified in terms of the structure of the controller due to its dual closed-loop architecture, and its feasibility is highly reflected in the control of reconfigurable manipulators. Finally, the effectiveness of the proposed DFTC scheme is demonstrated using simulations. PMID:26181826

  20. Tolerance and Safety Evaluation in a Large Cohort of Healthy Infants Fed an Innovative Prebiotic Formula: A Randomized Controlled Trial

    PubMed Central

    Piemontese, Pasqua; Giannì, Maria L.; Braegger, Christian P.; Chirico, Gaetano; Grüber, Christoph; Riedler, Josef; Arslanoglu, Sertac; van Stuijvenberg, Margriet; Boehm, Günther; Jelinek, Jürgen; Roggero, Paola

    2011-01-01

    Background the addition of oligosaccharides to infant formula has been shown to mimic some of the beneficial effects of human milk. The aim of the study was to assess the tolerance and safety of a formula containing an innovative mixture of oligosaccharides in early infancy. Methodology/Principal Findings this study was performed as a multi-center, randomized, double-blind, placebo-controlled trial including healthy term infants. Infants were recruited before the age of 8 weeks, either having started with formula feeding or being fully breast-fed (breastfeeding group). Formula-fed infants were randomized to feeding with a regular formula containing a mixture of neutral oligosaccharides and pectin-derived acidic oligosaccharides (prebiotic formula group) or regular formula without oligosaccharides (control formula group). Growth, tolerance and adverse events were assessed at 8, 16, 24 and 52 weeks of age. The prebiotic and control groups showed similar mean weight, length and head circumference, skin fold thicknesses, arm circumference gains and stool frequency at each study point. As far as the anthropometric parameters are concerned, the prebiotic group and the control group did not attain the values shown by the breastfeeding group at any study point. The skin fold thicknesses assessed in the breastfeeding group at 8 weeks were strikingly larger than those in formula fed infants, whereas at 52 weeks were strikingly smaller. The stool consistency in the prebiotic group was softer than in the control group at 8, 16 and 24 weeks (p<0.001) and closer to that of the breastfeeding group. There was no difference in the incidence of adverse events between the two formula groups. Conclusions our findings demonstrate the tolerability and the long term safety of a formula containing an innovative mixture of oligosaccharides in a large cohort of healthy infants. Trial Registration: drks-neu.uniklinik-freiburg.de DRKS 00000201 PMID:22140499

  1. Density control and wettability enhancement by functionalizing carbon nanotubes with nickel oxide in aluminum-carbon nanotube system.

    PubMed

    Kim, Tae-Hoon; Park, Min-Ho; Song, Kwan-Woo; Bae, Jee-Hwan; Lee, Jae-Wook; Lee, Choong Do; Yang, Cheol-Woong

    2013-11-01

    Excellent mechanical properties of carbon nanotubes (CNTs) make them ideal reinforcements for synthesizing light weight, high strength metal matrix composite. Aluminum is attractive matrix due to its light weight and Al/CNT composites are promising materials for various industrial applications. Powder metallurgy and casting techniques are normally used for bulk fabrications of composites. Casting process which can mass-produce delicate product is more suitable than existing powder metallurgy in view point of application in industries. In CNT-metal matrix composites, however, composite bulk fabrication has been limited because of the large density gap and poor wettability between the metal and CNTs. This study suggests a method for alleviating such problems. It was found that the wettability between aluminum and CNT could be enhanced by functionalizing the CNTs with nickel oxide. This functionalization of CNTs with heavier element also reduces the density gap between the matrix and reinforcements. It is suggested that this method could possibly be used in a casting process to enable mass fabrication of CNT-metal matrix composites.

  2. Melatonin for sleep in children with autism: a controlled trial examining dose, tolerability, and outcomes.

    PubMed

    Malow, Beth; Adkins, Karen W; McGrew, Susan G; Wang, Lily; Goldman, Suzanne E; Fawkes, Diane; Burnette, Courtney

    2012-08-01

    Supplemental melatonin has shown promise in treating sleep onset insomnia in children with autism spectrum disorders (ASD). Twenty-four children, free of psychotropic medications, completed an open-label dose-escalation study to assess dose-response, tolerability, safety, feasibility of collecting actigraphy data, and ability of outcome measures to detect change during a 14-week intervention. Supplemental melatonin improved sleep latency, as measured by actigraphy, in most children at 1 or 3 mg dosages. It was effective in week 1 of treatment, maintained effects over several months, was well tolerated and safe, and showed improvement in sleep, behavior, and parenting stress. Our findings contribute to the growing literature on supplemental melatonin for insomnia in ASD and inform planning for a large randomized trial in this population.

  3. Yin-Yang of costimulation: crucial controls of immune tolerance and function

    PubMed Central

    Nurieva, Roza I.; Liu, Xikui; Dong, Chen

    2010-01-01

    Summary In addition to signals from the T cell receptor complex, it has been recognized for many years that a “second” signal, most notably from CD28, is also important in T cell activation. In the recent years, many new members of CD28 family as well as the molecules that are share structural homology to CD28 ligands CD80 and CD86 have been discovered. Interestingly, some of these proteins function to dampen T cell activation and regulate the induction of T cell tolerance. Therefore, positive and negative costimulation are the two sides of the coin to fine tune T cell receptor signaling to determine the outcome of T cell receptor engagement- tolerance vs. function. PMID:19426216

  4. Intrinsic and extrinsic control of peripheral T-cell tolerance by costimulatory molecules of the CD28/B7 family

    PubMed Central

    Bour-Jordan, Hélène; Esensten, Jonathan H.; Martinez-Llordella, Marc; Penaranda, Cristina; Stumpf, Melanie; Bluestone, Jeffrey A.

    2011-01-01

    Summary Positive and negative costimulation by members of the CD28 family is critical for the development of productive immune responses against foreign pathogens and their proper termination to prevent inflammation-induced tissue damage. In addition, costimulatory signals are critical for the establishment and maintenance of peripheral tolerance. This paradigm has been established in many animal models and has led to the development of immunotherapies targeting costimulation pathways for the treatment of cancer, autoimmune disease, and allograft rejection. During the last decade, the complexity of the biology of costimulatory pathways has greatly increased due to the realization that costimulation does not affect only effector T cells but also influences regulatory T cells and antigen-presenting cells. Thus, costimulation controls T-cell tolerance through both intrinsic and extrinsic pathways. In this review, we discuss the influence of costimulation on intrinsic and extrinsic pathways of peripheral tolerance, with emphasis on members of the CD28 family, CD28, cytotoxic T-lymphocyte antigen-4 (CTLA-4), and programmed death-1 (PD-1), as well as the downstream cytokine interleukin-1 (IL-2). PMID:21488898

  5. Generating a fault-tolerant global clock using high-speed control signals for the MetaNet architecture

    SciTech Connect

    Ofek, Y. )

    1994-05-01

    This work describes a new technique, based on exchanging control signals between neighboring nodes, for constructing a stable and fault-tolerant global clock in a distributed system with an arbitrary topology. It is shown that it is possible to construct a global clock reference with time step that is much smaller than the propagation delay over the network's links. The synchronization algorithm ensures that the global clock tick' has a stable periodicity, and therefore, it is possible to tolerate failures of links and clocks that operate faster and/or slower than nominally specified, as well as hard failures. The approach taken in this work is to generate a global clock from the ensemble of the local transmission clocks and not to directly synchronize these high-speed clocks. The steady-state algorithm, which generates the global clock, is executed in hardware by the network interface of each node. At the network interface, it is possible to measure accurately the propagation delay between neighboring nodes with a small error or uncertainty and thereby to achieve global synchronization that is proportional to these error measurements. It is shown that the local clock drift (or rate uncertainty) has only a secondary effect on the maximum global clock rate. The synchronization algorithm can tolerate any physical failure. 18 refs.

  6. The immunology of pregnancy: regulatory T cells control maternal immune tolerance toward the fetus.

    PubMed

    La Rocca, Claudia; Carbone, Fortunata; Longobardi, Salvatore; Matarese, Giuseppe

    2014-11-01

    Establishment and maintenance of pregnancy represents a challenge for the maternal immune system since it has to defend against pathogens and tolerate paternal alloantigens expressed in fetal tissues. Regulatory T (Treg) cells, a subset of suppressor CD4(+) T cells, play a dominant role in the maintenance of immunological self-tolerance by preventing immune and autoimmune responses against self-antigens. Although localized mechanisms contribute to fetal evasion from immune attack, in the last few years it has been observed that Treg cells are essential in promoting fetal survival avoiding the recognition of paternal semi-allogeneic tissues by maternal immune system. Several functional studies have shown that unexplained infertility, miscarriage and pre-clampsia are often associated with deficit in Treg cell number and function while normal pregnancy selectively stimulates the accumulation of maternal forkhead-box-P3(+) (FoxP3(+)) CD4(+) Treg cells with fetal specificity. Some papers have been reported that the number of Treg cells persists at elevated levels long after delivery developing an immune regulatory memory against father's antigens, moreover these memory Treg cells rapidly proliferate during subsequent pregnancies, however, on the other hand, there are several evidence suggesting a clear decline of Treg cells number after delivery. Different factors such as cytokines, adipokines, pregnancy hormones and seminal fluid have immunoregulatory activity and influence the success of pregnancy by increasing Treg cell number and activity. The development of strategies capable of modulating immune responses toward fetal antigens through Treg cell manipulation, could have an impact on the induction of tolerance against fetal antigens during immune-mediated recurrent abortion.

  7. SIFT - A preliminary evaluation. [Software Implemented Fault Tolerant computer for aircraft control

    NASA Technical Reports Server (NTRS)

    Palumbo, D. L.; Butler, R. W.

    1983-01-01

    This paper presents the results of a performance evaluation of the SIFT computer system conducted in the NASA AIRLAB facility. The essential system functions are described and compared to both earlier design proposals and subsequent design improvements. The functions supporting fault tolerance are found to consume significant computing resources. With SIFT's specimen task load, scheduled at a 30-Hz rate, the executive tasks such as reconfiguration, clock synchronization and interactive consistency, require 55 percent of the available task slots. Other system overhead (e.g., voting and scheduling) use an average of 50 percent of each remaining task slot.

  8. RNA binding protein Pub1p regulates glycerol production and stress tolerance by controlling Gpd1p activity during winemaking.

    PubMed

    Orozco, Helena; Sepúlveda, Ana; Picazo, Cecilia; Matallana, Emilia; Aranda, Agustín

    2016-06-01

    Glycerol is a key yeast metabolite in winemaking because it contributes to improve the organoleptic properties of wine. It is also a cellular protective molecule that enhances the tolerance of yeasts to osmotic stress and promotes longevity. Thus, its production increases by genetic manipulation, which is of biotechnological and basic interest. Glycerol is produced by diverting glycolytic glyceraldehyde-3-phosphate through the action of glycerol-3-phosphate dehydrogenase (coded by genes GPD1 and GPD2). Here, we demonstrate that RNA-binding protein Pub1p regulates glycerol production by controlling Gpd1p activity. Its deletion does not alter GPD1 mRNA levels, but protein levels and enzymatic activity increase, which explains the higher intracellular glycerol concentration and greater tolerance to osmotic stress of the pub1∆ mutant. PUB1 deletion also enhances the activity of nicotinamidase, a longevity-promoting enzyme. Both enzymatic activities are partially located in peroxisomes, and we detected peroxisome formation during wine fermentation. The role of Pub1p in life span control depends on nutrient conditions and is related with the TOR pathway, and a major connection between RNA metabolism and the nutrient signaling response is established.

  9. Fault detection and fault tolerant control of a smart base isolation system with magneto-rheological damper

    NASA Astrophysics Data System (ADS)

    Wang, Han; Song, Gangbing

    2011-08-01

    Fault detection and isolation (FDI) in real-time systems can provide early warnings for faulty sensors and actuator signals to prevent events that lead to catastrophic failures. The main objective of this paper is to develop FDI and fault tolerant control techniques for base isolation systems with magneto-rheological (MR) dampers. Thus, this paper presents a fixed-order FDI filter design procedure based on linear matrix inequalities (LMI). The necessary and sufficient conditions for the existence of a solution for detecting and isolating faults using the H_{\\infty } formulation is provided in the proposed filter design. Furthermore, an FDI-filter-based fuzzy fault tolerant controller (FFTC) for a base isolation structure model was designed to preserve the pre-specified performance of the system in the presence of various unknown faults. Simulation and experimental results demonstrated that the designed filter can successfully detect and isolate faults from displacement sensors and accelerometers while maintaining excellent performance of the base isolation technology under faulty conditions.

  10. Tolerance of freshwater test organisms to formulated sediments for use as control materials in whole-sediment toxicity tests

    SciTech Connect

    Kemble, N.E.; Dwyer, F.J.; Ingersoll, C.G.; Dawson, T.D.; Norberg-King, T.J.

    1999-02-01

    A method is described for preparing formulated sediments for use in toxicity testing. Ingredients used to prepare formulated sediments included commercially available silt, clay, sand, humic acid, dolomite, and {alpha}-cellulose (as a source of organic carbon). {alpha}-Cellulose was selected as the source of organic carbon because it is commercially available, consistent from batch to batch, and low in contaminant concentrations. The tolerance of freshwater test organisms to formulated sediments for use as control materials in whole-sediment toxicity testing was evaluated. Sediment exposures were conducted for 10 d with the amphipod Hyalella azteca, the midges Chironomus riparius and C. tentans, and the oligochaete Lumbriculus variegatus and for 28 d with H. azteca. Responses of organisms in formulated sediments was compared with a field-collected control sediment that has routinely been used to determine test acceptability. Tolerance of organisms to formulated sediments was evaluated by determining responses to varying levels of {alpha}-cellulose, to varying levels of grain size, to evaluation of different food types, or to evaluation of different sources of overlying water. In the 10-d exposures, survival of organisms exposed to the formulated sediments routinely met or exceeded the responses of test organisms exposed to the control sediment and routinely met test acceptability criteria required in standard methods. Growth of amphipods and oligochaetes in 10-d exposures with formulated sediment was often less than growth of organisms in the field-collected control sediment. Additional research is needed, using the method employed to prepare formulated sediment, to determine if conditioning formulated sediments before starting 10-d tests would improve the growth of amphipods. In the 28-d exposures, survival of H. azteca was low when reconstituted water was used as the source of overlying water. However, when well water was used as the source of overlying water in

  11. Tolerance of freshwater test organisms to formulated sediments for use as control materials in whole-sediment toxicity tests

    USGS Publications Warehouse

    Kemble, N.E.; Dwyer, F.J.; Ingersoll, C.G.; Dawson, T.D.; Norberg-King, T. J.

    1999-01-01

    A method is described for preparing formulated sediments for use intoxicity testing. Ingredients used to prepare formulated sediments included commercially available silt, clay, sand, humic acid, dolomite, and α-cellulose (as a source of organic carbon). α-Cellulose was selected as the source of organic carbon because it is commercially available, consistent from batch to batch, and low in contaminant concentrations. The tolerance of freshwater test organisms to formulated sediments for use as control materials in whole-sediment toxicity testing was evaluated. Sediment exposures were conducted for 10 d with the amphipod Hyalella azteca, the midges Chironomus riparius and C. tentans, and the oligochaete Lumbriculus variegatus and for 28 d with H. azteca. Responses of organisms in formulated sediments was compared with a field-collected control sediment that has routinely been used to determine test acceptability. Tolerance of organisms to formulated sediments was evaluated by determining responses to varying levels of α-cellulose, to varying levels of grain size, to evaluation of different food types, or to evaluation of different sources of overlying water. In the 10-d exposures, survival of organisms exposed to the formulated sediments routinely met or exceeded the responses of test organisms exposed to the control sediment and routinely met test acceptability criteria required in standard methods. Growth of amphipods and oligochaetes in 10-d exposures with formulated sediment was often less than growth of organisms in the field-collected control sediment. Additional research is needed, using the method employed to prepare formulated sediment, to determine if conditioning formulated sediments before starting 10-d tests would improve the growth of amphipods. In the 28-d exposures, survival of H. azteca was low when reconstituted water was used as the source of overlying water. However, when well water was used as the source of overlying water in 28-d exposures

  12. Quantitative sensory testing and pain tolerance in patients with mild to moderate Alzheimer disease compared to healthy control subjects.

    PubMed

    Jensen-Dahm, Christina; Werner, Mads U; Dahl, Jørgen B; Jensen, Troels Staehelin; Ballegaard, Martin; Hejl, Anne-Mette; Waldemar, Gunhild

    2014-08-01

    Patients with Alzheimer disease (AD) report pain less frequently than their cognitively intact peers. It has been hypothesized that pain processing is altered in AD. The aim of this study was to investigate agreement and reliability of 3 pain sensitivity tests and to examine pain threshold and tolerance in patients with AD. We examined 29 patients with mild to moderate AD and 29 age- and gender-matched healthy control subjects with quantitative sensory testing, ie, assessments of detection threshold (warmth detection threshold [WDT]) and pain threshold (heat pain threshold [HPT], pressure algometry, cold pressor test), and assessments of tolerance (pressure algometry, cold pressor test). All procedures were done twice on day 1, 1 hour apart, and repeated on day 2. We found no difference between groups for WDT (patient vs control subjects: mean [95% confidence interval]: 35.5°C [33.4°C to 37.6°C] vs 35.4°C [34.3°C to 36.5°C], P=.8) or HPT (41.2°C [40.0°C to 42.4°C] vs 42.3°C [41.1°C to 43.5°C], P=.24). We observed comparable thresholds for pressure algometry (median [25% to 75% interquartile range]: 120 kPa [100 to 142 kPa] vs 131 kPa [113 to 192 kPa], P=.10), but significantly lower tolerance in AD patients (213 kPa [188 to 306 kPa] vs 289 kPa [262 to 360 kPa], P=.008). No differences were found for the cold pressor test. The study demonstrated good replicability of the sensory testing data with comparable data variability, for both groups, which supports the use of these methods in studies of patients with mild to moderate AD. Contrary to previous studies, we observed a reduced pain tolerance in patients with mild to moderate AD, which suggests that the reduced report of pain cannot be explained by reduced processing of painful stimuli.

  13. Effects of head-up tilting on baroreceptor control in subjects with different tolerances to orthostatic stress.

    PubMed

    Cooper, V L; Hainsworth, R

    2002-09-01

    During orthostatic stress, an increase in peripheral vascular resistance normally results in arterial blood pressure being well maintained, despite a decrease in cardiac output. The present study was undertaken to determine whether the sensitivity of the carotid baroreceptor reflex was increased during orthostatic stress and whether failure to develop this increase was associated with poor orthostatic tolerance. Three groups of subjects were studied: asymptomatic controls; patients investigated for suspected posturally related syncope but who had normal responses to an orthostatic stress test (normal patients); and patients who were shown to have low orthostatic tolerance (early fainters). We determined responses of R-R interval and forearm vascular resistance (mean arterial pressure/brachial artery velocity by Doppler ultrasonography) to the loading and unloading of carotid baroreceptors by application of pressures of -30 and +30 mmHg to a chamber fitted over the neck. Responses were determined after 20 min of supine rest and after 10 min of head-up tilt at 60 degrees. Responses of cardiac interval were not significantly different between the three groups, and they were not altered by the postural change. Vascular responses also did not differ between the groups during supine rest. However, in healthy volunteers and in normal patients, responses to both neck suction and pressure were significantly enhanced during head-up tilt. In controls, responses to suction were increased by tilt from 0.04+/-0.1 to -1.01+/-0.2%.mmHg(-1) (means+/-S.E.M.; P<0.001) and those to neck pressure from -0.6+/-0.3 to -3.1+/-1.1%.mmHg(-1) (P<0.05). In the normal patients, the corresponding changes were: during suction, from -0.2+/-0.1 to -0.7+/-0.1%.mmHg(-1) (P<0.05); during pressure, from -0.7+/-0.1 to -1.5+/-0.3%.mmHg(-1) (P<0.05). In contrast, in patients with low orthostatic tolerance, posture had no effect on the reflex (neck suction, from -0.3+/-0.1 to -0.3+/-0.1%.mmHg(-1); neck

  14. Corrosion of aluminum and aluminum alloys

    SciTech Connect

    Davis, J.R.

    1999-01-01

    This new handbook presents comprehensive coverage of the corrosion behavior of aluminum and aluminum alloys, with emphasis on practical information about how to select and process these materials in order to prevent corrosion attack. Described are the characteristics of these materials and the influences of composition, mechanical working, heat treatment, joining methods, microstructure, and environmental variables on their corrosion.

  15. Understanding genetic control of drought tolerance through meta-QTL analysis for genomics-assisted improvement of drought tolerance in peanut (Arachis hypogaeaL.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Majority of peanut is cultivated in the semi-arid tropical regions of the world where abiotic stresses especially drought is a major constraint for crop production. With an objective of undertaking molecular breeding approaches for developing superior lines with enhanced drought tolerance, several Q...

  16. An Improved Mobility-Based Control Protocol for Tolerating Clone Failures in Wireless Sensor Networks

    PubMed Central

    Zhou, Yuping; Xiong, Naixue; Tan, Mingxin; Huang, Rufeng; Kleonbet, Jon

    2016-01-01

    Nowadays, with the ubiquitous presence of the Internet of Things industry, the application of emerging sensor networks has become a focus of public attention. Unattended sensor nodes can be comprised and cloned to destroy the network topology. This paper proposes a novel distributed protocol and management technique for the detection of mobile replicas to tolerate node failures. In our scheme, sensors’ location claims are forwarded to obtain samples only when the corresponding witnesses meet. Meanwhile, sequential tests of statistical hypotheses are applied to further detect the cloned node by witnesses. The combination of randomized detection based on encountering and sequential tests drastically reduces the routing overhead and false positive/negative rate for detection. Theoretical analysis and simulation results show the detection efficiency and reasonable overhead of the proposed method. PMID:27886054

  17. A fault tolerant design for autonomous attitude control of the DSCS-III communication satellite

    NASA Technical Reports Server (NTRS)

    Matijevic, J.; Mettler, E.

    1983-01-01

    The first of a new series of satellites, which will provide the principal elements in the Defense Space Communications System (DSCS), was launched on Oct. 31, 1982. This satellite, DSCS-III, is part of a system which will consist of super-high frequency communications satellites in synchronous, equatorial orbits, continuously operating in four widely separate geographic regions. The DSCS-III is designed both to maintain critical communications in the presence of an electronic jamming threat and to survive nuclear radiation exposure. The results of the present investigation are to provide a basis for the design of a spacecraft tolerant of on-board failures, survivable against external threats, and capable of performing its mission autonomously for periods as long as six months.

  18. ALUMINUM-CONTAINING POLYMERS

    DTIC Science & Technology

    ALUMINUM COMPOUNDS, *ORGANOMETALLIC COMPOUNDS, *POLYMERIZATION, *POLYMERS, ACRYLIC RESINS, ALKYL RADICALS, CARBOXYLIC ACIDS, COPOLYMERIZATION, LIGHT TRANSMISSION, STABILITY, STYRENES, TRANSPARENT PANELS.

  19. Influence of Protoplasmic Water Loss on the Control of Protein Synthesis in the Desiccation-Tolerant Moss Tortula ruralis 1

    PubMed Central

    Oliver, Melvin J.

    1991-01-01

    Desiccation tolerance of the moss Tortula ruralis is characterized by a desiccation-induced change in gene expression that becomes evident upon rehydration. As reported earlier, this change in gene expression is apparently brought about by a change in the control of translation and does not include a major shift in mRNA abundance. A full qualitative and quantitative analysis of the alteration in gene expression, which is characterized by the loss of (or greater than fivefold decrease in) the synthesis of 25 hydration (h) proteins and initiation (or greater than fivefold increase) of the synthesis of 74 rehydration (r) proteins, is given in this report. Exposure to a desiccating atmosphere, for times that result in varying levels of water loss, enabled the determination that the control of synthesis of r proteins is different from the control of synthesis of h proteins. The r and h protein synthesis responses are internally coordinate, however. Similarly, the return to normal levels of h protein synthesis differs from that of the r proteins. The return to normal synthetic levels for all h proteins is synchronous, but the rate of loss of r protein synthesis varies with each individual r protein. Run-off translation of polysomes isolated from gametophytes during the drying phase demonstrates that there are no novel mRNAs recruited and no particular mRNA is favored for translation during desiccation. These findings add credence to the argument that translational control is the major component of the desiccation-induced alteration in gene expression in this plant, as discussed. Aspects of the response of protein synthesis to desiccation are consistent with the hypothesis that T. ruralis exhibits a repair-based mechanism of desiccation tolerance. ImagesFigure 2Figure 3Figure 5Figure 6Figure 7 PMID:16668577

  20. Aluminum and Young Artists.

    ERIC Educational Resources Information Center

    Anderson, Thomas

    1980-01-01

    The author suggests a variety of ways in which aluminum and aluminum foil can be used in elementary and junior high art classes: relief drawing and rubbing; printing; repousse; sculpture; mobiles; foil sculpture; and three dimensional design. Sources of aluminum supplies are suggested. (SJL)

  1. Safety and Tolerability of Panax ginseng Root Extract: A Randomized, Placebo-Controlled, Clinical Trial in Healthy Korean Volunteers

    PubMed Central

    Lee, Nam-Hun; Yoo, Sa-Ra; Kim, Hyeong-Geug; Cho, Jung-Hyo

    2012-01-01

    Abstract Objectives Panax ginseng has been extensively used as an adaptogen and is among the top 10 selling herbal supplements in the United States over the past decade. However, there have been few reports about the toxicity of P. ginseng in human studies. Given the lack of toxicological studies in human, this study investigated whether P. ginseng administration causes any noticeable toxic effects in healthy volunteers. Methods This study was designed as a randomized, double-blind, placebo-controlled, and parallel group trial in healthy volunteers. The subjects were required to be healthy, free from any significant disease, as assessed at screening by physical examination, medical history, and laboratory (hematological and biochemical) tests. Eligible subjects received P. ginseng extract (1 g/day or 2 g/day) or placebo over a 4-week period. Results Although mild adverse events, such as dyspepsia, hot flash, insomnia, and constipation, were reported in both P. ginseng and placebo group, no serious untoward reactions were reported following P. ginseng administration. Nonsignificant changes were observed in hematological and biochemical tests. Conclusions P. ginseng administration for 4 weeks was shown to be safe, tolerable, and free of any untoward toxic effect in healthy male and female volunteers. Future results from ongoing multicenter collaborative efforts to evaluate short- and long-term effects of P. ginseng may contribute to our current understanding of safety and tolerability of this herbal product. PMID:22909282

  2. Fault Tolerance Analysis of L1 Adaptive Control System for Unmanned Aerial Vehicles

    NASA Astrophysics Data System (ADS)

    Krishnamoorthy, Kiruthika

    Trajectory tracking is a critical element for the better functionality of autonomous vehicles. The main objective of this research study was to implement and analyze L1 adaptive control laws for autonomous flight under normal and upset flight conditions. The West Virginia University (WVU) Unmanned Aerial Vehicle flight simulation environment was used for this purpose. A comparison study between the L1 adaptive controller and a baseline conventional controller, which relies on position, proportional, and integral compensation, has been performed for a reduced size jet aircraft, the WVU YF-22. Special attention was given to the performance of the proposed control laws in the presence of abnormal conditions. The abnormal conditions considered are locked actuators (stabilator, aileron, and rudder) and excessive turbulence. Several levels of abnormal condition severity have been considered. The performance of the control laws was assessed over different-shape commanded trajectories. A set of comprehensive evaluation metrics was defined and used to analyze the performance of autonomous flight control laws in terms of control activity and trajectory tracking errors. The developed L1 adaptive control laws are supported by theoretical stability guarantees. The simulation results show that L1 adaptive output feedback controller achieves better trajectory tracking with lower level of control actuation as compared to the baseline linear controller under nominal and abnormal conditions.

  3. Allotropic control: How certain fluorinated carbonate electrolytes protect aluminum current collectors by promoting the formation of insoluble coordination polymers

    SciTech Connect

    Shkrob, Ilya A.; Pupek, Krzysztof Z.; Abraham, Daniel P.

    2016-07-28

    Here, there is a strong incentive for increasing the operation voltage of Li-ion cells above 4.5 V in order to increase the density of stored energy. Aluminum is an inexpensive, lightweight metal that is commonly used as a positive electrode current collector in these cells. Imide LiX salts, such as lithium bis(trifluoromethylsulfonyl)imide (X = TFSI), and lithium bis(fluorosulfonyl)imide (X = FSI), are chemically stable on the energized lithiated transition metal oxide electrodes, but their presence in the electrolyte causes rapid anodic dissolution and pitting of Al current collectors at potentials exceeding 4.0 V versus Li/Li+. For LiBF4 and LiPF6, the release of HF near the energized surfaces passivates the exposed Al metal, inhibiting this pitting corrosion, but it also causes the gradual degradation of the cathode active material, negating this important advantage. Here we report that in certain electrolytes containing fluorinated carbonate solvents and LiX salts, the threshold voltage for safe operation of Al current collectors can be increased to 5.5 V versus Li/Li+. Interestingly, the most efficient solvent also facilitates the formation of an insoluble gel when AlX3 is introduced into this solvent. We suggest that this solvent promotes the aggregation of coordination polymers of AlX3 at the exposed Al surface that isolate this surface from the electrolyte, thereby preventing further Al dissolution and corrosion. Other examples of Al collector protection may also involve this mechanism. Our study suggests that such “allotropic control” could be a way of widening the operation window of Li-ion cells without electrode deterioration, Al current collector corrosion, and electrolyte breakdown.

  4. Allotropic control: How certain fluorinated carbonate electrolytes protect aluminum current collectors by promoting the formation of insoluble coordination polymers

    DOE PAGES

    Shkrob, Ilya A.; Pupek, Krzysztof Z.; Abraham, Daniel P.

    2016-07-28

    Here, there is a strong incentive for increasing the operation voltage of Li-ion cells above 4.5 V in order to increase the density of stored energy. Aluminum is an inexpensive, lightweight metal that is commonly used as a positive electrode current collector in these cells. Imide LiX salts, such as lithium bis(trifluoromethylsulfonyl)imide (X = TFSI), and lithium bis(fluorosulfonyl)imide (X = FSI), are chemically stable on the energized lithiated transition metal oxide electrodes, but their presence in the electrolyte causes rapid anodic dissolution and pitting of Al current collectors at potentials exceeding 4.0 V versus Li/Li+. For LiBF4 and LiPF6, themore » release of HF near the energized surfaces passivates the exposed Al metal, inhibiting this pitting corrosion, but it also causes the gradual degradation of the cathode active material, negating this important advantage. Here we report that in certain electrolytes containing fluorinated carbonate solvents and LiX salts, the threshold voltage for safe operation of Al current collectors can be increased to 5.5 V versus Li/Li+. Interestingly, the most efficient solvent also facilitates the formation of an insoluble gel when AlX3 is introduced into this solvent. We suggest that this solvent promotes the aggregation of coordination polymers of AlX3 at the exposed Al surface that isolate this surface from the electrolyte, thereby preventing further Al dissolution and corrosion. Other examples of Al collector protection may also involve this mechanism. Our study suggests that such “allotropic control” could be a way of widening the operation window of Li-ion cells without electrode deterioration, Al current collector corrosion, and electrolyte breakdown.« less

  5. Electro-thermal control of aluminum-doped zinc oxide/vanadium dioxide multilayered thin films for smart-device applications

    NASA Astrophysics Data System (ADS)

    Skuza, J. R.; Scott, D. W.; Mundle, R. M.; Pradhan, A. K.

    2016-02-01

    We demonstrate the electro-thermal control of aluminum-doped zinc oxide (Al:ZnO) /vanadium dioxide (VO2) multilayered thin films, where the application of a small electric field enables precise control of the applied heat to the VO2 thin film to induce its semiconductor-metal transition (SMT). The transparent conducting oxide nature of the top Al:ZnO film can be tuned to facilitate the fine control of the SMT of the VO2 thin film and its associated properties. In addition, the Al:ZnO film provides a capping layer to the VO2 thin film, which inhibits oxidation to a more energetically favorable and stable V2O5 phase. It also decreases the SMT of the VO2 thin film by approximately 5–10 °C because of an additional stress induced on the VO2 thin film and/or an alteration of the oxygen vacancy concentration in the VO2 thin film. These results have significant impacts on technological applications for both passive and active devices by exploiting this near-room-temperature SMT.

  6. Electro-thermal control of aluminum-doped zinc oxide/vanadium dioxide multilayered thin films for smart-device applications.

    PubMed

    Skuza, J R; Scott, D W; Mundle, R M; Pradhan, A K

    2016-02-17

    We demonstrate the electro-thermal control of aluminum-doped zinc oxide (Al:ZnO) /vanadium dioxide (VO2) multilayered thin films, where the application of a small electric field enables precise control of the applied heat to the VO2 thin film to induce its semiconductor-metal transition (SMT). The transparent conducting oxide nature of the top Al:ZnO film can be tuned to facilitate the fine control of the SMT of the VO2 thin film and its associated properties. In addition, the Al:ZnO film provides a capping layer to the VO2 thin film, which inhibits oxidation to a more energetically favorable and stable V2O5 phase. It also decreases the SMT of the VO2 thin film by approximately 5-10 °C because of an additional stress induced on the VO2 thin film and/or an alteration of the oxygen vacancy concentration in the VO2 thin film. These results have significant impacts on technological applications for both passive and active devices by exploiting this near-room-temperature SMT.

  7. Electro-thermal control of aluminum-doped zinc oxide/vanadium dioxide multilayered thin films for smart-device applications

    PubMed Central

    Skuza, J. R.; Scott, D. W.; Mundle, R. M.; Pradhan, A. K.

    2016-01-01

    We demonstrate the electro-thermal control of aluminum-doped zinc oxide (Al:ZnO) /vanadium dioxide (VO2) multilayered thin films, where the application of a small electric field enables precise control of the applied heat to the VO2 thin film to induce its semiconductor-metal transition (SMT). The transparent conducting oxide nature of the top Al:ZnO film can be tuned to facilitate the fine control of the SMT of the VO2 thin film and its associated properties. In addition, the Al:ZnO film provides a capping layer to the VO2 thin film, which inhibits oxidation to a more energetically favorable and stable V2O5 phase. It also decreases the SMT of the VO2 thin film by approximately 5–10 °C because of an additional stress induced on the VO2 thin film and/or an alteration of the oxygen vacancy concentration in the VO2 thin film. These results have significant impacts on technological applications for both passive and active devices by exploiting this near-room-temperature SMT. PMID:26884225

  8. The chemistry of iron, aluminum, and dissolved organic material in three acidic, metal-enriched, mountain streams, as controlled by watershed and in-stream processes

    USGS Publications Warehouse

    McKnight, Diane M.; Bencala, Kenneth E.

    1990-01-01

    Several studies were conducted in three acidic, metal-enriched, mountain streams, and the results are discussed together in this paper to provide a synthesis of watershed and in-stream processes controlling Fe, Al, and DOC (dissolved organic carbon) concentrations. One of the streams, the Snake River, is naturally acidic; the other two, Peru Creek and St. Kevin Gulch, receive acid mine drainage. Analysis of stream water chemistry data for the acidic headwaters of the Snake River shows that some trace metal solutes (Al, Mn, Zn) are correlated with major ions, indicating that watershed processes control their concentrations. Once in the stream, biogeochemical processes can control transport if they occur over time scales comparable to those for hydrologic transport. Examples of the following in-stream reactions are presented: (1) photoreduction and dissolution of hydrous iron oxides in response to an experimental decrease in stream pH, (2) precipitation of Al at three stream confluences, and (3) sorption of dissolved organic material by hydrous iron and aluminum oxides in a stream confluence. The extent of these reactions is evaluated using conservative tracers and a transport model that includes storage in the substream zone.

  9. Know Thyself: NK-Cell Inhibitory Receptors Prompt Self-Tolerance, Education, and Viral Control

    PubMed Central

    Nash, William T.; Teoh, Jeffrey; Wei, Hairong; Gamache, Awndre; Brown, Michael G.

    2014-01-01

    Natural killer (NK) cells provide essential protection against viral infections. One of the defining features of this lymphocyte population is the expression of a wide array of variable cell surface stimulatory and inhibitory NK receptors (sNKR and iNKR, respectively). The iNKR are particularly important in terms of NK-cell education. As receptors specific for MHC class I (MHC I) molecules, they are responsible for self-tolerance and adjusting NK-cell reactivity based on the expression level of self-MHC I. The end result of this education is twofold: (1) inhibitory signaling tunes the functional capacity of the NK cell, endowing greater potency with greater education, and (2) education on self allows the NK cell to detect aberrations in MHC I expression, a common occurrence during many viral infections. Many studies have indicated an important role for iNKR and MHC I in disease, making these receptors attractive targets for manipulating NK-cell reactivity in the clinic. A greater understanding of iNKR and their ability to regulate NK cells will provide a basis for future attempts at translating their potential utility into benefits for human health. PMID:24795719

  10. Controlling diffusion for a self-healing radiation tolerant nanostructured ferritic alloy

    SciTech Connect

    Miller, Michael K.; Parish, Chad M.; Bei, Hongbin

    2014-12-18

    Diffusion plays a major role in the stability of microstructures to extreme conditions of high temperature and high doses of irradiation. In nanostructured ferritic alloys, first principle calculations indicate that the binding energy of vacancies is reduced by the presence of oxygen, titanium and yttrium atoms. Therefore, the number of free vacancies available for diffusion can be greatly reduced. The mechanical properties of these alloys, compared to traditional wrought alloys of similar composition and grain structure, is distinctly different, and the ultrafine grained alloy is distinguished by a high number density of Ti–Y–O-enriched nanoclusters and solute clusters, which drives the mechanical response. When a displacement cascade interacts with a nanocluster, the solute atoms are locally dispersed into the matrix by ballistic collisions, but immediately a new nanocluster reforms due to the local supersaturation of solutes and vacancies until the excess vacancies are consumed. Furthermore, the result of these processes is a structural material for advanced energy systems with a microstructure that is self-healing and tolerant to high doses of radiation and high temperatures.

  11. Community structure and nutrient level control the tolerance of autotrophic biofilm to silver contamination.

    PubMed

    Leflaive, J; Felten, V; Ferriol, J; Lamy, A; Ten-Hage, L; Bec, A; Danger, M

    2015-09-01

    Autotrophic biofilms are complex and fundamental biological compartments of many aquatic ecosystems. Since microbial species differ in their sensitivity to stressors, biofilms have long been proposed for assessing the quality of aquatic ecosystems. Among the many stressors impacting aquatic ecosystems, eutrophication and metal pollution are certainly the most common. Despite that these stressors often occur together, their effects on biofilms have been far much studied separately than interactively. In this study, we evaluated the interactive effects of silver (Ag), a reemerging contaminant, and phosphorus (P), a nutrient often associated with freshwater eutrophication, on the structure and functioning of two types of autotrophic biofilms, one dominated by diatoms and another one dominated by cyanobacteria. We hypothesized that P would alleviate the toxic effects of Ag, either directly, through the contribution of P in metal detoxification processes, or indirectly, through P-mediated shifts in biofilm community compositions and associated divergences in metal tolerance. Results showed that Ag impacted biofilm community structure and functioning but only at unrealistic concentrations (50 μg/L). P availability led to significant shifts in biofilm community composition, these changes being more pronounced in diatom- than those in cyanobacteria-dominated biofilm. In addition, P tended to reduce the impact of Ag but only for the cyanobacteria-dominated biofilm. More generally, our results highlight the preponderant role of the initial community structure and nutrient level on biofilm response to metallic pollutants.

  12. Controlling diffusion for a self-healing radiation tolerant nanostructured ferritic alloy

    DOE PAGES

    Miller, Michael K.; Parish, Chad M.; Bei, Hongbin

    2014-12-18

    Diffusion plays a major role in the stability of microstructures to extreme conditions of high temperature and high doses of irradiation. In nanostructured ferritic alloys, first principle calculations indicate that the binding energy of vacancies is reduced by the presence of oxygen, titanium and yttrium atoms. Therefore, the number of free vacancies available for diffusion can be greatly reduced. The mechanical properties of these alloys, compared to traditional wrought alloys of similar composition and grain structure, is distinctly different, and the ultrafine grained alloy is distinguished by a high number density of Ti–Y–O-enriched nanoclusters and solute clusters, which drives themore » mechanical response. When a displacement cascade interacts with a nanocluster, the solute atoms are locally dispersed into the matrix by ballistic collisions, but immediately a new nanocluster reforms due to the local supersaturation of solutes and vacancies until the excess vacancies are consumed. Furthermore, the result of these processes is a structural material for advanced energy systems with a microstructure that is self-healing and tolerant to high doses of radiation and high temperatures.« less

  13. Implementing fault-tolerant sensors

    NASA Technical Reports Server (NTRS)

    Marzullo, Keith

    1989-01-01

    One aspect of fault tolerance in process control programs is the ability to tolerate sensor failure. A methodology is presented for transforming a process control program that cannot tolerate sensor failures to one that can. Additionally, a hierarchy of failure models is identified.

  14. Cast Aluminum Structures Technology (CAST). Phase I. Preliminary Design

    DTIC Science & Technology

    1977-05-01

    49 26 Assumed Crack Growth Rate -- A357 . . . . . . . . . .. 50 27 Flaw Growth at Hole of Gear Attachment Point .... .... 52 28 A357 S-N...wo TABLES Number ?Ile 1 Statistics on.16 Classes of A357 Aluminum Casting Data .. 14 2 "CAST" Preliminary Design Allowables .. .. .. ....... 20 3...damage tolerance criteria; development of preliminary design allowables data for A357 aluminum casting alloy to be used for design until completion

  15. A tutorial on the CARE III approach to reliability modeling. [of fault tolerant avionics and control systems

    NASA Technical Reports Server (NTRS)

    Trivedi, K. S.; Geist, R. M.

    1981-01-01

    The CARE 3 reliability model for aircraft avionics and control systems is described by utilizing a number of examples which frequently use state-of-the-art mathematical modeling techniques as a basis for their exposition. Behavioral decomposition followed by aggregration were used in an attempt to deal with reliability models with a large number of states. A comprehensive set of models of the fault-handling processes in a typical fault-tolerant system was used. These models were semi-Markov in nature, thus removing the usual restrictions of exponential holding times within the coverage model. The aggregate model is a non-homogeneous Markov chain, thus allowing the times to failure to posses Weibull-like distributions. Because of the departures from traditional models, the solution method employed is that of Kolmogorov integral equations, which are evaluated numerically.

  16. Aging Optimization of Aluminum-Lithium Alloy L277 for Application to Cryotank Structures

    NASA Technical Reports Server (NTRS)

    Sova, B. J.; Sankaran, K. K.; Babel, H.; Farahmand, B.; Cho, A.

    2003-01-01

    Compared with aluminum alloys such as 2219, which is widely used in space vehicle for cryogenic tanks and unpressurized structures, aluminum-lithium alloys possess attractive combinations of lower density and higher modulus along with comparable mechanical properties and improved damage tolerance. These characteristics have resulted in the successful use of the aluminum-lithium alloy 2195 for the Space Shuttle External Tank, and the consideration of newer U.S. aluminum-lithium alloys such as L277 and C458 for future space vehicles. A design of experiments aging study was conducted for plate and a limited study on extrusions. To achieve the T8 temper, Alloy L277 is typically aged at 290 F for 40 hours. In the study for plate, a two-step aging treatment was developed through a design of experiments study and the one step aging used as a control. Based on the earlier NASA studies on 2195, the first step aging temperature was varied between 220 F and 260 F. The second step aging temperatures was varied between 290 F and 310 F, which is in the range of the single-step aging temperature. For extrusions, two, single-step, and one two-step aging condition were evaluated. The results of the design of experiments used for the T8 temper as well as a smaller set of experiments for the T6 temper for plate and the results for extrusions will be presented.

  17. Design of a Failure Tolerant Flight Control System via Coprime Factorization Method

    NASA Astrophysics Data System (ADS)

    Kameyama, Takeharu; Ochi, Yoshimasa

    This paper presents a design method of reconfigurable flight control systems based on the coprime factorization method. The baseline robust control system is designed using the normalized coprime factorization method. The identification method employed is a closed-loop one, which is also based on coprime factorization; therefore, the method is suitable to the robust control system. The ν-gap metric is chosen as a criterion that indicates the effects of failures on stabilizability of the robust control system. The ν-gap metric can be computed using the identified parameters. To illustrate the effectiveness of the control and identification method, a design example and simulation results for the F-18 HARV are shown.

  18. Preparation and controlled-release studies of a protocatechuic acid-magnesium/aluminum-layered double hydroxide nanocomposite

    PubMed Central

    Barahuie, Farahnaz; Hussein, Mohd Zobir; Hussein-Al-Ali, Samer Hasan; Arulselvan, Palanisamy; Fakurazi, Sharida; Zainal, Zulkarnain

    2013-01-01

    In the study reported here, magnesium/aluminum (Mg/Al)-layered double hydroxide (LDH) was intercalated with an anticancer drug, protocatechuic acid, using ion-exchange and direct coprecipitation methods, with the resultant products labeled according to the method used to produce them: “PANE” (ie, protocatechuic acid-Mg/Al nanocomposite synthesized using the ion-exchange method) and “PAND” (ie, protocatechuic acid-Mg/Al nanocomposite synthesized using the direct method), respectively. Powder X-ray diffraction and Fourier transform infrared spectroscopy confirmed the intercalation of protocatechuic acid into the inter-galleries of Mg/Al-LDH. The protocatechuic acid between the interlayers of PANE and PAND was found to be a monolayer, with an angle from the z-axis of 8° for PANE and 15° for PAND. Thermogravimetric and differential thermogravimetric analysis results revealed that the thermal stability of protocatechuic acid was markedly enhanced upon intercalation. The loading of protocatechuic acid in PANE and PAND was estimated to be about 24.5% and 27.5% (w/w), respectively. The in vitro release study of protocatechuic acid from PANE and PAND in phosphate-buffered saline at pH 7.4, 5.3, and 4.8 revealed that the nanocomposites had a sustained release property. After 72 hours incubation of PANE and PAND with MCF-7 human breast cancer and HeLa human cervical cancer cell lines, it was found that the nanocomposites had suppressed the growth of these cancer cells, with a half maximal inhibitory concentration of 35.6 μg/mL for PANE and 36.0 μg/mL for PAND for MCF-7 cells, and 19.8 μg/mL for PANE and 30.3 μg/mL for PAND for HeLa cells. No half maximal inhibitory concentration for either nanocomposite was found for 3T3 cells. PMID:23737666

  19. Aluminum: Recycling of Aluminum Dross/Saltcake

    SciTech Connect

    Blazek, S.

    1999-01-29

    As this NICE3 publication details, the objective of this project is to commercialize the process technology to eliminate all landfill waste associated with black dross and saltcake generated from aluminum recycling in the United States.

  20. Factors controlling soil water and stream water aluminum concentrations after a clearcut in a forested watershed with calcium-poor soils

    USGS Publications Warehouse

    McHale, M.R.; Burns, Douglas A.; Lawrence, G.B.; Murdoch, Peter S.

    2007-01-01

    The 24 ha Dry Creek watershed in the Catskill Mountains of southeastern New York State USA was clearcut during the winter of 1996-1997. The interactions among acidity, nitrate (NO3- ), aluminum (Al), and calcium (Ca2+) in streamwater, soil water, and groundwater were evaluated to determine how they affected the speciation, solubility, and concentrations of Al after the harvest. Watershed soils were characterized by low base saturation, high exchangeable Al concentrations, and low exchangeable base cation concentrations prior to the harvest. Mean streamwater NO3- concentration was about 20 ??mol l-1 for the 3 years before the harvest, increased sharply after the harvest, and peaked at 1,309 ??mol l -1 about 5 months after the harvest. Nitrate and inorganic monomeric aluminum (Alim) export increased by 4-fold during the first year after the harvest. Alim mobilization is of concern because it is toxic to some fish species and can inhibit the uptake of Ca2+ by tree roots. Organic complexation appeared to control Al solubility in the O horizon while ion exchange and possibly equilibrium with imogolite appeared to control Al solubility in the B horizon. Alim and NO3- concentrations were strongly correlated in B-horizon soil water after the clearcut (r2 = 0.96), especially at NO3- concentrations greater than 100 ??mol l-1. Groundwater entering the stream from perennial springs contained high concentrations of base cations and low concentrations of NO3- which mixed with acidic, high Alim soil water and decreased the concentration of Alim in streamwater after the harvest. Five years after the harvest soil water NO 3- concentrations had dropped below preharvest levels as the demand for nitrogen by regenerating vegetation increased, but groundwater NO3- concentrations remained elevated because groundwater has a longer residence time. As a result streamwater NO3- concentrations had not fallen below preharvest levels, even during the growing season, 5 years after the harvest

  1. Development and Preliminary Randomized Controlled Trial of a Distress Tolerance Treatment for Smokers With a History of Early Lapse

    PubMed Central

    2013-01-01

    Introduction: An inability to tolerate distress is a significant predictor of early smoking lapse following a cessation attempt. We conducted a preliminary randomized controlled trial to compare a distress tolerance (DT) treatment that incorporated elements of exposure-based therapies and Acceptance and Commitment Therapy to standard smoking cessation treatment (ST). Methods: Smokers with a history of early lapse in prior quit attempts received either DT (N = 27; 9 2-hr group and 6 50-min individual sessions) or ST (N = 22; 6 90-min group and 1 20-min individual session), plus 8 weeks of transdermal nicotine patch. Results: At the end of behavioral treatment, odds of abstinence among participants receiving DT were 6.46 times greater than among participants receiving ST (66.7% vs. 31.8%), equivalent to a medium- to large-effect size. Odds of abstinence for DT were still 1.73 times greater at 8 weeks, corresponding to a small- to medium-effect size, although neither this difference nor those at 13 and 26 weeks were statistically significant. Furthermore, of those who lapsed to smoking during the first week postquit, DT participants had more than 4 times greater odds of abstinence than ST participants at the end of treatment. Relative to ST, DT participants also reported a larger decrease in experiential avoidance, a hypothesized DT treatment mediator, prior to quit day. The trajectory of negative mood and withdrawal symptoms in DT differed from ST and was largely consistent with hypotheses. Conclusions: Reasons for the decrease in abstinence in DT after treatment discontinuation and suggestions for future research are discussed. PMID:23884317

  2. Aspects of aluminum toxicity

    SciTech Connect

    Hewitt, C.D.; Savory, J.; Wills, M.R. )

    1990-06-01

    Aluminum is the most abundant metal in the earth's crust. The widespread occurrence of aluminum, both in the environment and in foodstuffs, makes it virtually impossible for man to avoid exposure to this metal ion. Attention was first drawn to the potential role of aluminum as a toxic metal over 50 years ago, but was dismissed as a toxic agent as recently as 15 years ago. The accumulation of aluminum, in some patients with chronic renal failure, is associated with the development of toxic phenomena; dialysis encephalopathy, osteomalacic dialysis osteodystrophy, and an anemia. Aluminum accumulation also occurs in patients who are not on dialysis, predominantly infants and children with immature or impaired renal function. Aluminum has also been implicated as a toxic agent in the etiology of Alzheimer's disease, Guamiam amyotrophic lateral sclerosis, and parkinsonism-dementia. 119 references.

  3. Fault-tolerant adaptive control for load-following in static space nuclear power systems

    NASA Technical Reports Server (NTRS)

    Parlos, Alexander G.; Onbasioglu, Fetiye O.; Peddicord, Kenneth L.; Metzger, John D.

    1992-01-01

    The possible use of a dual-loop model-based adaptive control system for load following in static space nuclear power systems is investigated. The proposed approach has thus far been applied only to a thermoelectric space nuclear power system but is equally applicable to other static space nuclear power systems such as thermionic systems.

  4. Putative paternal factors controlling chilling tolerance in Korean market-type cucumber (Cucumis sativus L.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chilling temperatures (<10 degrees C) may cause damage to Korean market-type cucumber (Cucumis sativus L.) plants during winter and early spring growing seasons. Inheritance to chilling in U.S. processing cucumber is controlled by cytoplasmic (maternally) and nuclear factors. To understand inherit...

  5. Electromagnetic treatment of shoulder periarthritis: a randomized controlled trial of the efficiency and tolerance of magnetotherapy.

    PubMed

    Leclaire, R; Bourgouin, J

    1991-04-01

    The potential benefit of magnetotherapy was investigated in 47 consecutive outpatients with periarthritis of the shoulder. Using a controlled triple-blind study design, one group of patients received hot pack applications and passive manual stretching and pulley exercises; the other group received the same therapy plus magnetotherapy. Treatment was administered three times a week. For a maximum of three months, a standardized treatment protocol was used. There was no significant improvement in pain reduction or in range of motion with electromagnetic field therapy. After 12 weeks of therapy, the patients who received magnetotherapy showed mean pain scores of 1.5 (+/- .61 SD) at rest, 2.2 (+/- .76 SD) on movement, and 1.9 (+/- .94 SD), on lying, compared to scores for the control group of 1.4 (+/- .65 SD), 2.2 (+/- .7 SD), and 1.9 (+/- .95 SD), respectively. Linear pain scale scores improved from 71 to 21 for both groups. At 12 weeks the gain in range of motion was mean 109 degrees +/- 46.8 in patients receiving electromagnetic field therapy, compared to 122 degrees +/- 33.4 for the controls (not significant). At entry, the functional handicap score was 53.5 for both groups. At 12 weeks, it was 24 for the magnetotherapy group and 17 for the control group (difference not significant). In conclusion, this study showed no benefit from magnetotherapy in the pain score, range of motion, or improvement of functional status in patients with periarthritis of the shoulder.

  6. Fine Grain Aluminum Superplasticity

    DTIC Science & Technology

    1980-02-01

    time at elevated temperature for 7475 aluminum alloy 5 2 Optical micrographs of 7075 aluminum alloy after exposure to 5160C (960oF) for times...applied to Al-Zn-Mg-Cu ( 7075 Al) alloy. Subsequent developments by Waldman et al. (refs. 8-11) resulted in the demonstration that 7000 series alloys...a number of aluminum alloys. With such a fine grain structure, high temperature deformation character- istics approaching superplastic behavior

  7. BONDING ALUMINUM METALS

    DOEpatents

    Noland, R.A.; Walker, D.E.

    1961-06-13

    A process is given for bonding aluminum to aluminum. Silicon powder is applied to at least one of the two surfaces of the two elements to be bonded, the two elements are assembled and rubbed against each other at room temperature whereby any oxide film is ruptured by the silicon crystals in the interface; thereafter heat and pressure are applied whereby an aluminum-silicon alloy is formed, squeezed out from the interface together with any oxide film, and the elements are bonded.

  8. Aluminum powder metallurgy processing

    SciTech Connect

    Flumerfelt, J.F.

    1999-02-12

    The objective of this dissertation is to explore the hypothesis that there is a strong linkage between gas atomization processing conditions, as-atomized aluminum powder characteristics, and the consolidation methodology required to make components from aluminum powder. The hypothesis was tested with pure aluminum powders produced by commercial air atomization, commercial inert gas atomization, and gas atomization reaction synthesis (GARS). A comparison of the GARS aluminum powders with the commercial aluminum powders showed the former to exhibit superior powder characteristics. The powders were compared in terms of size and shape, bulk chemistry, surface oxide chemistry and structure, and oxide film thickness. Minimum explosive concentration measurements assessed the dependence of explosibility hazard on surface area, oxide film thickness, and gas atomization processing conditions. The GARS aluminum powders were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization processing conditions. The GARS aluminum powders were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization oxidation of aluminum powder. An Al-Ti-Y GARS alloy exposed in ambient air at different temperatures revealed the effect of reactive alloy elements on post-atomization powder oxidation. The pure aluminum powders were consolidated by two different routes, a conventional consolidation process for fabricating aerospace components with aluminum powder and a proposed alternative. The consolidation procedures were compared by evaluating the consolidated microstructures and the corresponding mechanical properties. A low temperature solid state sintering experiment demonstrated that tap densified GARS aluminum powders can form sintering necks between contacting powder particles, unlike the total resistance to sintering of commercial air atomization aluminum powder.

  9. Sensor and Actuator Selection for Fault-Tolerant Control of Flexible Structures

    DTIC Science & Technology

    1989-02-01

    the ’instance’ of the problem. We may now call upon a basic result of optimization theory : local maximal points of concave functions on convex sets...counsel on systems and controls theory , and to Mr. Tim Henderson for further assistance with the ACOSS model. The Draper Laboratory provided a superb...forms of MIL-STD-1543A for military [1] and NASA Handbook 5300.4 for civil [2] programs, stating certain basic requirements such as no single-point

  10. Aluminum Target Dissolution in Support of the Pu-238 Program

    SciTech Connect

    McFarlane, Joanna; Benker, Dennis; DePaoli, David W; Felker, Leslie Kevin; Mattus, Catherine H

    2014-09-01

    Selection of an aluminum alloy for target cladding affects post-irradiation target dissolution and separations. Recent tests with aluminum alloy 6061 yielded greater than expected precipitation in the caustic dissolution step, forming up to 10 wt.% solids of aluminum hydroxides and aluminosilicates. We present a study to maximize dissolution of aluminum metal alloy, along with silicon, magnesium, and copper impurities, through control of temperature, the rate of reagent addition, and incubation time. Aluminum phase transformations have been identified as a function of time and temperature, using X-ray diffraction. Solutions have been analyzed using wet chemical methods and X-ray fluorescence. These data have been compared with published calculations of aluminum phase diagrams. Temperature logging during the transients has been investigated as a means to generate kinetic and mass transport data on the dissolution process. Approaches are given to enhance the dissolution of aluminum and aluminosilicate phases in caustic solution.

  11. Closed-Loop Evaluation of an Integrated Failure Identification and Fault Tolerant Control System for a Transport Aircraft

    NASA Technical Reports Server (NTRS)

    Shin, Jong-Yeob; Belcastro, Christine; Khong, thuan

    2006-01-01

    Formal robustness analysis of aircraft control upset prevention and recovery systems could play an important role in their validation and ultimate certification. Such systems developed for failure detection, identification, and reconfiguration, as well as upset recovery, need to be evaluated over broad regions of the flight envelope or under extreme flight conditions, and should include various sources of uncertainty. To apply formal robustness analysis, formulation of linear fractional transformation (LFT) models of complex parameter-dependent systems is required, which represent system uncertainty due to parameter uncertainty and actuator faults. This paper describes a detailed LFT model formulation procedure from the nonlinear model of a transport aircraft by using a preliminary LFT modeling software tool developed at the NASA Langley Research Center, which utilizes a matrix-based computational approach. The closed-loop system is evaluated over the entire flight envelope based on the generated LFT model which can cover nonlinear dynamics. The robustness analysis results of the closed-loop fault tolerant control system of a transport aircraft are presented. A reliable flight envelope (safe flight regime) is also calculated from the robust performance analysis results, over which the closed-loop system can achieve the desired performance of command tracking and failure detection.

  12. Fault-Tolerant and Reconfigurable Control of Unmanned Aerial Vehicles (UAVs)

    DTIC Science & Technology

    2008-02-29

    01- I 0 5 10t 15 2 3 35 40 45 go Figure 23 - Weights profile of the funneling NN Project Publications 1. Bin Li, Zhao Sun, X. H. Liao, Liguo Weng...Southeast Symposium on Systems Theory, Cookeville, TN, pp. 406-410, March, 2006. 6. Liguo Weng, Wenchuan Cai, M. J. Zhang; X. H. Liao and David Song, "Neural...7. Yao Li, Zhao Sun, Ran Zhang, Liguo Weng, and David Y. Song, "Close Formation Flight Control of Multi-UAVs via Fuzzy Logic Technique," Advanced

  13. Carbothermic Aluminum Production Using Scrap Aluminum As A Coolant

    DOEpatents

    LaCamera, Alfred F.

    2002-11-05

    A process for producing aluminum metal by carbothermic reduction of alumina ore. Alumina ore is heated in the presence of carbon at an elevated temperature to produce an aluminum metal body contaminated with about 10-30% by wt. aluminum carbide. Aluminum metal or aluminum alloy scrap then is added to bring the temperature to about 900-1000.degree. C. and precipitate out aluminum carbide. The precipitated aluminum carbide is filtered, decanted, or fluxed with salt to form a molten body having reduced aluminum carbide content.

  14. 75 FR 44184 - Aluminum tris(O-ethylphosphonate), Butylate, Chlorethoxyfos, Clethodim, et al.; Proposed...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-28

    ... for aluminum tris(O-ethylphosphonate) on pineapple fodder and forage because they are not considered... to revoke the tolerances for aluminum tris(O- ] ethylphosphonate) on pineapple fodder and forage... on the commodity. Because pineapple, fodder and pineapple, forage are no longer considered by...

  15. MTBE OXIDATION BY BIFUNCTIONAL ALUMINUM

    EPA Science Inventory

    Bifunctional aluminum, prepared by sulfating zero-valent aluminum with sulfuric acid, has a dual functionality of simultaneously decomposing both reductively- and oxidatively-degradable contaminants. In this work, the use of bifunctional aluminum for the degradation of methyl te...

  16. Fault tolerant attitude control for small unmanned aircraft systems equipped with an airflow sensor array.

    PubMed

    Shen, H; Xu, Y; Dickinson, B T

    2014-11-18

    Inspired by sensing strategies observed in birds and bats, a new attitude control concept of directly using real-time pressure and shear stresses has recently been studied. It was shown that with an array of onboard airflow sensors, small unmanned aircraft systems can promptly respond to airflow changes and improve flight performances. In this paper, a mapping function is proposed to compute aerodynamic moments from the real-time pressure and shear data in a practical and computationally tractable formulation. Since many microscale airflow sensors are embedded on the small unmanned aircraft system surface, it is highly possible that certain sensors may fail. Here, an adaptive control system is developed that is robust to sensor failure as well as other numerical mismatches in calculating real-time aerodynamic moments. The advantages of the proposed method are shown in the following simulation cases: (i) feedback pressure and wall shear data from a distributed array of 45 airflow sensors; (ii) 50% failure of the symmetrically distributed airflow sensor array; and (iii) failure of all the airflow sensors on one wing. It is shown that even if 50% of the airflow sensors have failures, the aircraft is still stable and able to track the attitude commands.

  17. Temperature Tolerant Evolvable Systems Utilizing FPGA Boards and Bias-Controlled Amplifiers

    NASA Technical Reports Server (NTRS)

    Kumar, Nikhil R.

    2005-01-01

    Space missions often require radiation and extreme-temperature hardened electronics to survive the harsh environments beyond Earth's atmosphere. Traditional approaches to preserve electronics incorporate shielding, insulation and redundancy at the expense of power and weight. However, a novel way of bypassing these problems is the concept of evolutionary hardware. A reconfigurable device, consisting of several switches interconnected with analog/digital parts, is controlled by an evolutionary processor (EP). When the EP detects degradation in the circuit it sends signals to reconfigure the switches, thus forming a new circuit with the desired output. This concept has been developed since the mid-l990s, but one problem remains-the EP cannot degrade substantially. For this reason, extensive testing at extreme temperatures (-180 to 120 C) has been done on devices found on FPGA boards (taking the role of the EP), such as the Analog to Digital and the Digital to Analog Converter. The EP is used in conjunction with a bias-controlled amplifier and a new prototype relay board, which is interconnected with 6 G4-FETs, a tri-input transistor-like element developed at JPL. The greatest improvements to be made lie in the reconfigurable device, so future design and testing of the G4-FET chip is required.

  18. Randomized, Placebo-Controlled Trial of Mipomersen in Patients with Severe Hypercholesterolemia Receiving Maximally Tolerated Lipid-Lowering Therapy

    PubMed Central

    McGowan, Mary P.; Tardif, Jean-Claude; Ceska, Richard; Burgess, Lesley J.; Soran, Handrean; Gouni-Berthold, Ioanna; Wagener, Gilbert; Chasan-Taber, Scott

    2012-01-01

    Objectives Mipomersen, an antisense oligonucleotide targeting apolipoprotein B synthesis, significantly reduces LDL-C and other atherogenic lipoproteins in familial hypercholesterolemia when added to ongoing maximally tolerated lipid-lowering therapy. Safety and efficacy of mipomersen in patients with severe hypercholesterolemia was evaluated. Methods and Results Randomized, double-blind, placebo-controlled, multicenter trial. Patients (n  = 58) were ≥18 years with LDL-C ≥7.8 mmol/L or LDL-C ≥5.1 mmol/L plus CHD disease, on maximally tolerated lipid-lowering therapy that excluded apheresis. Weekly subcutaneous injections of mipomersen 200 mg (n  = 39) or placebo (n  = 19) were added to lipid-lowering therapy for 26 weeks. Main outcome: percent reduction in LDL-C from baseline to 2 weeks after the last dose of treatment. Mipomersen (n = 27) reduced LDL-C by 36%, from a baseline of 7.2 mmol/L, for a mean absolute reduction of 2.6 mmol/L. Conversely, mean LDL-C increased 13% in placebo (n = 18) from a baseline of 6.5 mmol/L (mipomersen vs placebo p<0.001). Mipomersen produced statistically significant (p<0.001) reductions in apolipoprotein B and lipoprotein(a), with no change in high-density lipoprotein cholesterol. Mild-to-moderate injection site reactions were the most frequently reported adverse events with mipomersen. Mild-to-moderate flu-like symptoms were reported more often with mipomersen. Alanine transaminase increase, aspartate transaminase increase, and hepatic steatosis occurred in 21%, 13% and 13% of mipomersen treated patients, respectively. Adverse events by category for the placebo and mipomersen groups respectively were: total adverse events, 16(84.2%), 39(100%); serious adverse events, 0(0%), 6(15.4%); discontinuations due to adverse events, 1(5.3%), 8(20.5%) and cardiac adverse events, 1(5.3%), 5(12.8%). Conclusion Mipomersen significantly reduced LDL-C, apolipoprotein B, total cholesterol and non-HDL-cholesterol, and

  19. Open-Loop HIRF Experiments Performed on a Fault Tolerant Flight Control Computer

    NASA Technical Reports Server (NTRS)

    Koppen, Daniel M.

    1997-01-01

    During the third quarter of 1996, the Closed-Loop Systems Laboratory was established at the NASA Langley Research Center (LaRC) to study the effects of High Intensity Radiated Fields on complex avionic systems and control system components. This new facility provided a link and expanded upon the existing capabilities of the High Intensity Radiated Fields Laboratory at LaRC that were constructed and certified during 1995-96. The scope of the Closed-Loop Systems Laboratory is to place highly integrated avionics instrumentation into a high intensity radiated field environment, interface the avionics to a real-time flight simulation that incorporates aircraft dynamics, engines, sensors, actuators and atmospheric turbulence, and collect, analyze, and model aircraft performance. This paper describes the layout and functionality of the Closed-Loop Systems Laboratory, and the open-loop calibration experiments that led up to the commencement of closed-loop real-time flight experiments.

  20. High energy density aluminum battery

    SciTech Connect

    Brown, Gilbert M.; Paranthaman, Mariappan Parans; Dai, Sheng; Dudney, Nancy J.; Manthiram, Arumugan; McIntyre, Timothy J.; Sun, Xiao-Guang; Liu, Hansan

    2016-10-11

    Compositions and methods of making are provided for a high energy density aluminum battery. The battery comprises an anode comprising aluminum metal. The battery further comprises a cathode comprising a material capable of intercalating aluminum or lithium ions during a discharge cycle and deintercalating the aluminum or lithium ions during a charge cycle. The battery further comprises an electrolyte capable of supporting reversible deposition and stripping of aluminum at the anode, and reversible intercalation and deintercalation of aluminum or lithium at the cathode.

  1. A randomized, double-blind, placebo-controlled study to investigate the safety, tolerability, and pharmacokinetics of single enantiomer (+)-mefloquine compared with racemic mefloquine in healthy persons.

    PubMed

    Tansley, Robert; Lotharius, Julie; Priestley, Anthony; Bull, Fiona; Duparc, Stephan; Möhrle, Jörg

    2010-12-01

    Racemic mefloquine is a highly effective antimalarial whose clinical utility has been compromised by its association with neuropsychiatric and gastrointestinal side effects. It is hypothesized that the cause of the side effects may reside in the (-) enantiomer. We sought to compare the safety, tolerability and pharmacokinetic profile of (+)-mefloquine with racemic mefloquine in a randomized, ascending-dose, double-blind, active and placebo-controlled, parallel cohort study in healthy male and female adult volunteers. Although differing in its manifestations, both study drugs displayed a substantially worse tolerability profile compared with placebo. The systemic clearance was slower for (-)-mefloquine than (+)-mefloquine. Thus, (+)-mefloquine has a different safety and tolerability profile compared with racemic mefloquine but its global safety profile is not superior and replacement of the currently used antimalarial drug with (+)-mefloquine is not warranted.

  2. Is the Aluminum Hypothesis Dead?

    PubMed Central

    2014-01-01

    The Aluminum Hypothesis, the idea that aluminum exposure is involved in the etiology of Alzheimer disease, dates back to a 1965 demonstration that aluminum causes neurofibrillary tangles in the brains of rabbits. Initially the focus of intensive research, the Aluminum Hypothesis has gradually been abandoned by most researchers. Yet, despite this current indifference, the Aluminum Hypothesis continues to attract the attention of a small group of scientists and aluminum continues to be viewed with concern by some of the public. This review article discusses reasons that mainstream science has largely abandoned the Aluminum Hypothesis and explores a possible reason for some in the general public continuing to view aluminum with mistrust. PMID:24806729

  3. SIZ1 deficiency causes reduced stomatal aperture and enhanced drought tolerance via controlling salicylic acid-induced accumulation of reactive oxygen species in Arabidopsis.

    PubMed

    Miura, Kenji; Okamoto, Hiroyuki; Okuma, Eiji; Shiba, Hayato; Kamada, Hiroshi; Hasegawa, Paul M; Murata, Yoshiyuki

    2013-01-01

    Transpiration and gas exchange occur through stomata. Thus, the control of stomatal aperture is important for the efficiency and regulation of water use, and for the response to drought. Here, we demonstrate that SIZ1-mediated endogenous salicylic acid (SA) accumulation plays an important role in stomatal closure and drought tolerance. siz1 reduced stomatal apertures. The reduced stomatal apertures of siz1 were inhibited by the application of peroxidase inhibitors, salicylhydroxamic acid and azide, which inhibits SA-dependent reactive oxygen species (ROS) production, but not by an NADPH oxidase inhibitor, diphenyl iodonium chloride, which inhibits ABA-dependent ROS production. Furthermore, the introduction of nahG into siz1, which reduces SA accumulation, restored stomatal opening. Stomatal closure is generally induced by water deficit. The siz1 mutation caused drought tolerance, whereas nahG siz1 suppressed the tolerant phenotype. Drought stresses also induced expression of SA-responsive genes, such as PR1 and PR2. Furthermore, other SA-accumulating mutants, cpr5 and acd6, exhibited stomatal closure and drought tolerance, and nahG suppressed the phenotype of cpr5 and acd6, as did siz1 and nahG siz1. Together, these results suggest that SIZ1 negatively affects stomatal closure and drought tolerance through the accumulation of SA.

  4. Anodizing Aluminum with Frills.

    ERIC Educational Resources Information Center

    Doeltz, Anne E.; And Others

    1983-01-01

    "Anodizing Aluminum" (previously reported in this journal) describes a vivid/relevant laboratory experience for general chemistry students explaining the anodizing of aluminum in sulfuric acid and constrasting it to electroplating. Additions to this procedure and the experiment in which they are used are discussed. Reactions involved are…

  5. Building blocks of self-control: increased tolerance for delay with bundled rewards.

    PubMed Central

    Ainslie, George; Monterosso, John R

    2003-01-01

    Impulsive choice can be defined as temporary preference for a smaller-sooner reward (SS) over a larger-later reward (LL). Hyperbolic discounting implies that impulsive choices will occur less when organisms choose between a series of SSs versus LLs all at once than when they choose between single SS versus LL pairs. Eight rats were exposed to two conditions of an intertemporal choice paradigm using sucrose solution as reward. In both conditions, the LL was 150 microl delayed by 3 s, while the SS was an immediate reward that ranged from 25-150 microl across sessions. Preference for the LL was greater when the chosen reward was automatically delivered three times in succession (bundled) than when it was chosen singly and delivered after each choice. For each of the 8 rats, the estimated SS amount that produced indifference was higher in the bundled condition than in the single condition. Because bundling in humans may be based on the perception that one's current choice is predictive of future choices, the data presented here may demonstrate an important building block of self-control. PMID:12696740

  6. The Aluminum Smelting Process

    PubMed Central

    2014-01-01

    This introduction to the industrial primary aluminum production process presents a short description of the electrolytic reduction technology, the history of aluminum, and the importance of this metal and its production process to modern society. Aluminum's special qualities have enabled advances in technologies coupled with energy and cost savings. Aircraft capabilities have been greatly enhanced, and increases in size and capacity are made possible by advances in aluminum technology. The metal's flexibility for shaping and extruding has led to architectural advances in energy-saving building construction. The high strength-to-weight ratio has meant a substantial reduction in energy consumption for trucks and other vehicles. The aluminum industry is therefore a pivotal one for ecological sustainability and strategic for technological development. PMID:24806722

  7. Effect of environment on the quality of aluminum joints brazed in partial nitrogen atmospheres

    SciTech Connect

    Pai, D.M.; Zhong, G.; Shafiq, P.; Badgley, S.

    1995-06-01

    The vacuum brazing of aluminum is an established process for producing parts such as radiators and heater cores used in automobiles. The process forms connecting fillets between component parts by the melting and flow of aluminum-silicon alloy cladding. The operating procedures developed for vacuum brazing are largely empirical, and rely on process and materials control. Past studies have examined the effects of factors such as moisture, heating rate, the wetting and flow characteristics of filler alloy and the role of the magnesium promoter in the vacuum brazing process. While vacuum brazing has traditionally been done under high vacuum conditions, it is economically desirable to have less stringent vacuum requirements. This study focuses on the effect of environment on the quality of aluminum joints brazed in an atmosphere where a high vacuum has been produced and then backfilled partially with nitrogen. Microscopic examination of the braze quality together with an analysis of the vacuum furnace atmosphere reveals a possible correlation between gaseous impurity levels in the brazing environment and the quality of the brazed joint. This paper reports the results of this study and provides data on limits of environmental impurities that can be tolerated by the process. This data can eventually be used for intelligent computer control, and thereby optimization, of the vacuum brazing process.

  8. Transcript profiling of the salt-tolerant Festuca rubra ssp. litoralis reveals a regulatory network controlling salt acclimatization.

    PubMed

    Diédhiou, Calliste J; Popova, Olga V; Golldack, Dortje

    2009-05-01

    We report an analysis of salt-stress responses in the monocotyledonous halophyte Festuca rubra ssp. litoralis. Salt-dependent expression of transcripts encoding a PIP2;1 aquaporin, V-ATPase subunit B, and the Na+/H+ antiporter NHX was characterized. Transcription of FrPIP2;1, FrVHA-B, and FrNHX1 was induced in root tissue of F. rubra ssp. litoralis by salt treatment, and during salt-stress F. rubra ssp. litoralis accumulated sodium in leaves and roots. Cell specificity of FrPIP2;1, FrVHA-B, and FrNHX1 transcription was analyzed by in situ PCR in roots of F. rubra ssp. litoralis. Expression of the genes was localized to the root epidermis, cortex cells, endodermis, and the vascular tissue. In plants treated with 500 mM NaCl, transcripts were repressed in the epidermis and the outer cortex cells, whereas endodermis and vasculature showed strong signals. These data demonstrate that transcriptional regulation of the aquaporin PIP2;1, V-ATPase, and the Na+/H+ antiporter NHX is correlated with salt tolerance in F. rubra ssp. litoralis and suggests coordinated control of ion homeostasis and water status at high salinity in plants. Salt-induced transcript accumulation in F. rubra ssp. litoralis was further monitored by cDNA-arrays with expressed sequence tags derived from a cDNA subtraction library. The salt-regulated transcripts included those involved in the control of gene expression and signal transduction elements such as a serine/threonine protein kinase, an SNF1-related protein kinase, and a WRKY-type transcription factor. Other ESTs with salt-dependent regulation included transcripts encoding proteins that function in metabolism, general stress responses, and defense and transport proteins.

  9. Boron/aluminum fan blades for SCAR engines

    NASA Technical Reports Server (NTRS)

    Stabrylla, R. G.; Carlson, R. G.

    1977-01-01

    Processing procedures were developed to enhance boron/aluminum bond behavior and foreign object damage (FOD) tolerance. Design and analysis indicated that the J101 Stage 1 fan blade meets the required frequencies without a midspan shroud. The fabricability of full size J101 blades was assessed, while six blades were fabricated and finished machined.

  10. The effect of gallium arsenide aluminum laser therapy in the management of cervical myofascial pain syndrome: a double blind, placebo-controlled study.

    PubMed

    Dundar, U; Evcik, D; Samli, F; Pusak, H; Kavuncu, V

    2007-06-01

    The efficacy of low-level laser therapy (LLLT) in myofascial pain syndrome (MPS) seems controversial. A prospective, double-blind, randomized controlled trial was conducted in patients with chronic MPS in the neck to evaluate the effects of low-level 830-nm gallium arsenide aluminum (Ga-As-Al) laser therapy. The study group consisted of 64 MPS patients. The patients were randomly assigned into two groups. In group 1 (n = 32), Ga-As-Al laser treatment was applied over three trigger points bilaterally for 2 min over each point once a day for 15 days during a period of 3 weeks. In group 2 (n = 32), the same treatment protocol was given, but the laser instrument was switched off during applications. All patients in both groups performed daily isometric exercise and stretching exercises for cervical region. Parameters were measured at baseline and after 4 weeks. All patients were evaluated with respect to pain (at rest, movement, and night) and assessed by visual analog scale, measurement of active range of motion using an inclinometer and a goniometer, and the neck disability index. In both groups, statistically significant improvements were detected in all outcome measures compared with baseline (p < 0.05). However, no significant differences were obtained between the two groups (p > 0.05). In conclusion, although the laser therapy has no superiority over placebo groups in this study, we cannot exclude the possibility of effectivity with another treatment regimen including different laser wavelengths and dosages (different intensity and density and/or treatment interval).

  11. Wastewater sludge dewaterability enhancement using hydroxyl aluminum conditioning: Role of aluminum speciation.

    PubMed

    Cao, Bingdi; Zhang, Weijun; Wang, Qiandi; Huang, Yangrui; Meng, Chenrui; Wang, Dongsheng

    2016-11-15

    dewatering property by controlling aluminum speciation.

  12. Clinical biochemistry of aluminum

    SciTech Connect

    King, S.W.; Savory, J.; Wills, M.R.

    1981-05-01

    Aluminum toxicity has been implicated in the pathogenesis of a number of clinical disorders in patients with chronic renal failure on long-term intermittent hemodialysis treatment. The predominant disorders have been those involving either bone (osteomalacic dialysis osteodystrophy) or brain (dialysis encephalopathy). In nonuremic patients, an increased brain aluminum concentration has been implicated as a neurotoxic agent in the pathogenesis of Alzheimer's disease and was associated with experimental neurofibrillary degeneration in animals. The brain aluminum concentrations of patients dying with the syndrome of dialysis encephalopathy (dialysis dementia) are significantly higher than in dialyzed patients without the syndrome and in nondialyzed patients. Two potential sources for the increased tissue content of aluminum in patients on hemodialysis have been proposed: (1) intestinal absorption from aluminum containing phosphate-binding gels, and (2) transfer across the dialysis membrane from aluminum in the water used to prepare the dialysate. These findings, coupled with our everyday exposure to the ubiquitous occurrence of aluminum in nature, have created concerns over the potential toxicity of this metal.

  13. A double-blind, placebo-controlled, crossover trial comparing the effects of amiloride and hydrochlorothiazide on glucose tolerance in patients with essential hypertension.

    PubMed

    Stears, Anna J; Woods, Sarah H; Watts, Michaela M; Burton, Timothy J; Graggaber, Johann; Mir, Fraz A; Brown, Morris J

    2012-05-01

    Hypertension guidelines advise limiting the dose of thiazide diuretics and avoiding combination with β-blockade, because of increased risk of diabetes mellitus. We tested whether changes in the 2-hour oral glucose tolerance test could be detected after 4 weeks of treatment with a thiazide and could be avoided by switching to amiloride. Two double-blind, placebo-controlled, crossover studies were performed. In study 1 (41 patients), we found that changes in glucose during a 2-hour oral glucose tolerance test could be detected after 4 weeks of treatment with bendroflumethiazide. In study 2, 37 patients with essential hypertension received, in random order, 4 weeks of once-daily treatment with hydrochlorothiazide (HCTZ) 25 to 50 mg, nebivolol 5 to 10 mg, combination (HCTZ 25-50 mg+nebivolol 5-10 mg), amiloride (10-20 mg), and placebo. Each drug was force titrated at 2 weeks and separated by a 4-week placebo washout. At each visit, we recorded blood pressure and performed a 75-g oral glucose tolerance test. Primary outcome was the difference in glucose (over the 2 hours of the oral glucose tolerance test) between 0 and 4 weeks, when HCTZ and amiloride were compared by repeated-measures analysis. For similar blood pressure reductions, there were opposite changes in glucose between the 2 diuretics (P<0.0001). Nebivolol did not impair glucose tolerance, either alone or in combination. There was a negative correlation between Δpotassium and Δ2-hour glucose (r=-0.28; P<0.0001). In 2 crossover studies, 4 weeks of treatment with a thiazide diuretic impaired glucose tolerance. No impairment was seen with K(+)-sparing diuretic or β(1)-selective blockade. Substitution or addition of amiloride may be the solution to preventing thiazide-induced diabetes mellitus.

  14. Cast Aluminum Bonding Study

    DTIC Science & Technology

    1988-05-01

    fabricated using P?-’r;est11 bur)ld II19 te(hnll I Oly with 6 cIsL nqs. The cast a lumi num alloy used was A357 . The sur- face preparation was phosphoric acid...from a cast aluminum alloy designated A357 . The bonding surfaces of the adherends were prepared using PAA. One primer and two adhesives considered...System, Cast Aluminum Lap Shear 18 11 Bond Area of 350°F Adhesive System, Cast Aluminum Lap Shear 19 vi LIST OF TABLES TABLE PAGE 1 A357 Chemical

  15. Purifying Aluminum by Vacuum Distillation

    NASA Technical Reports Server (NTRS)

    Du Fresne, E. R.

    1985-01-01

    Proposed method for purifying aluminum employs one-step vacuum distillation. Raw material for process impure aluminum produced in electrolysis of aluminum ore. Impure metal melted in vacuum. Since aluminum has much higher vapor pressure than other constituents, boils off and condenses on nearby cold surfaces in proportions much greater than those of other constituents.

  16. Studies of aluminum in rat brain

    SciTech Connect

    Lipman, J.J.; Brill, A.B.; Som, P.; Jones, K.W.; Colowick, S.; Cholewa, M.

    1985-01-01

    The effects of high aluminum concentrations in rat brains were studied using /sup 14/C autoradiography to measure the uptake of /sup 14/C 2-deoxy-D-glucose (/sup 14/C-2DG) and microbeam proton-induced x-ray emission (microPIXE) with a 20-..mu..m resolution to measure concentrations of magnesium, aluminum, potassium, and calcium. The aluminum was introduced intracisternally in the form of aluminum tartrate (Al-T) while control animals were given sodium tartrate (Na-T). The /sup 14/C was administered intravenously. The animals receiving Al-T developed seizure disorders and had pathological changes that included cerebral cortical atrophy. The results showed that there was a decreased uptake of /sup 14/C-2DG in cortical regions in which increased aluminum levels were measured, i.e., there is a correlation between the aluminum in the rat brain and decreased brain glucose metabolism. A minimum detection limit of about 16 ppM (mass fraction) or 3 x 10/sup 9/ Al atoms was obtained for Al under the conditions employed. 14 refs., 4 figs., 1 tab.

  17. [Effects of temperature and pH on the distribution of aluminum species in drinking water].

    PubMed

    Wang, Wen-dong; Yang, Hong-wei; Jiang, Jing; Zhu, Wan-peng; Jiang, Zhan-peng

    2009-08-15

    The effects of aluminum on water distribution system and human health are mainly attributable to their presence in drinking water. Laboratory experiments were performed to investigate the influence of temperature and pH on the distribution of aluminum species applying alum synthetic water. Aluminum species studied in the experiments included monomeric aluminum, soluble aluminum, suspended aluminum, and polymeric aluminum, which were determined by fluorescence spectrophotometry method. Results indicated that suspended aluminum was the major species at pH 6.5, occupied about 62.2% in the total aluminum mass concentration. While at pH above 7.0, monomeric aluminum was the major species; and varied little as reaction time increased. Polymeric aluminum mass concentration was low at studied water quality condition and also varied little as reaction time increased. The influence of temperature on aluminum species distribution was similar to solution pH; and both could be explained by pOH. Aluminum species in drinking water could be controlled by adjusting the pOH value, which provided theoretical guidance for the operation of the water distribution system and aluminum toxicity control.

  18. Electrically Conductive Anodized Aluminum Surfaces

    NASA Technical Reports Server (NTRS)

    Nguyen, Trung Hung

    2006-01-01

    Anodized aluminum components can be treated to make them sufficiently electrically conductive to suppress discharges of static electricity. The treatment was conceived as a means of preventing static electric discharges on exterior satin-anodized aluminum (SAA) surfaces of spacecraft without adversely affecting the thermal-control/optical properties of the SAA and without need to apply electrically conductive paints, which eventually peel off in the harsh environment of outer space. The treatment can also be used to impart electrical conductivity to anodized housings of computers, medical electronic instruments, telephoneexchange equipment, and other terrestrial electronic equipment vulnerable to electrostatic discharge. The electrical resistivity of a typical anodized aluminum surface layer lies between 10(exp 11) and 10(exp 13) Omega-cm. To suppress electrostatic discharge, it is necessary to reduce the electrical resistivity significantly - preferably to < or = 10(exp 9) Omega-cm. The present treatment does this. The treatment is a direct electrodeposition process in which the outer anodized surface becomes covered and the pores in the surface filled with a transparent, electrically conductive metal oxide nanocomposite. Filling the pores with the nanocomposite reduces the transverse electrical resistivity and, in the original intended outer-space application, the exterior covering portion of the nanocomposite would afford the requisite electrical contact with the outer-space plasma. The electrical resistivity of the nanocomposite can be tailored to a value between 10(exp 7) and 10(exp 12) Omega-cm. Unlike electrically conductive paint, the nanocomposite becomes an integral part of the anodized aluminum substrate, without need for adhesive bonding material and without risk of subsequent peeling. The electrodeposition process is compatible with commercial anodizing production lines. At present, the electronics industry uses expensive, exotic

  19. Corrosion Inhibitors for Aluminum.

    ERIC Educational Resources Information Center

    Muller, Bodo

    1995-01-01

    Describes a simple and reliable test method used to investigate the corrosion-inhibiting effects of various chelating agents on aluminum pigments in aqueous alkaline media. The experiments that are presented require no complicated or expensive electronic equipment. (DDR)

  20. Walnut Hulls Clean Aluminum

    NASA Technical Reports Server (NTRS)

    Colberg, W. R.; Gordon, G. H.; Jackson, C. H.

    1984-01-01

    Hulls inflict minimal substrate damage. Walnut hulls found to be best abrasive for cleaning aluminum surfaces prior to painting. Samples blasted with walnut hulls showed no compressive stress of surface.

  1. Achromobacter denitrificans Strain YD35 Pyruvate Dehydrogenase Controls NADH Production To Allow Tolerance to Extremely High Nitrite Levels

    PubMed Central

    Doi, Yuki; Shimizu, Motoyuki; Fujita, Tomoya; Nakamura, Akira; Takizawa, Noboru

    2014-01-01

    We identified the extremely nitrite-tolerant bacterium Achromobacter denitrificans YD35 that can grow in complex medium containing 100 mM nitrite (NO2−) under aerobic conditions. Nitrite induced global proteomic changes and upregulated tricarboxylate (TCA) cycle enzymes as well as antioxidant proteins in YD35. Transposon mutagenesis generated NO2−-hypersensitive mutants of YD35 that had mutations at genes for aconitate hydratase and α-ketoglutarate dehydrogenase in the TCA cycle and a pyruvate dehydrogenase (Pdh) E1 component, indicating the importance of TCA cycle metabolism to NO2− tolerance. A mutant in which the pdh gene cluster was disrupted (Δpdh mutant) could not grow in the presence of 100 mM NO2−. Nitrite decreased the cellular NADH/NAD+ ratio and the cellular ATP level. These defects were more severe in the Δpdh mutant, indicating that Pdh contributes to upregulating cellular NADH and ATP and NO2−-tolerant growth. Exogenous acetate, which generates acetyl coenzyme A and then is metabolized by the TCA cycle, compensated for these defects caused by disruption of the pdh gene cluster and those caused by NO2−. These findings demonstrate a link between NO2− tolerance and pyruvate/acetate metabolism through the TCA cycle. The TCA cycle mechanism in YD35 enhances NADH production, and we consider that this contributes to a novel NO2−-tolerating mechanism in this strain. PMID:24413603

  2. Production of Reliable Flight Crucial Software: Validation Methods Research for Fault Tolerant Avionics and Control Systems Sub-Working Group Meeting

    NASA Technical Reports Server (NTRS)

    Dunham, J. R. (Editor); Knight, J. C. (Editor)

    1982-01-01

    The state of the art in the production of crucial software for flight control applications was addressed. The association between reliability metrics and software is considered. Thirteen software development projects are discussed. A short term need for research in the areas of tool development and software fault tolerance was indicated. For the long term, research in format verification or proof methods was recommended. Formal specification and software reliability modeling, were recommended as topics for both short and long term research.

  3. Aluminum powder applications

    SciTech Connect

    Gurganus, T.B.

    1995-08-01

    Aluminum powders have physical and metallurgical characteristics related to their method of manufacture that make them extremely important in a variety of applications. They can propel rockets, improve personal hygiene, increase computer reliability, refine exotic alloys, and reduce weight in the family sedan or the newest Air Force fighter. Powders formed into parts for structural and non-structural applications hold the key to some of the most exciting new developments in the aluminum future.

  4. CORROSION PROTECTION OF ALUMINUM

    DOEpatents

    Dalrymple, R.S.; Nelson, W.B.

    1963-07-01

    Treatment of aluminum-base metal surfaces in an autoclave with an aqueous chromic acid solution of 0.5 to 3% by weight and of pH below 2 for 20 to 50 hrs at 160 to 180 deg C produces an extremely corrosion-resistant aluminum oxidechromium film on the surface. A chromic acid concentration of 1 to 2% and a pH of about 1 are preferred. (D.C.W.)

  5. Corrosion Protection of Aluminum

    DOEpatents

    Dalrymple, R. S.; Nelson, W. B.

    1963-07-01

    Treatment of aluminum-base metal surfaces in an autoclave with an aqueous chromic acid solution of 0.5 to 3% by weight and of pH below 2 for 20 to 50 hrs at 160 to 180 deg C produces an extremely corrosion-resistant aluminum oxidechromium film on the surface. A chromic acid concentration of 1 to 2% and a pH of about 1 are preferred.

  6. Brazing of dispersion-strengthened aluminum

    SciTech Connect

    Bjoerneklett, B.; Grong, O.; Anisdahl, L.; Hellum, E.; Sande, V.

    1996-03-01

    In recent years, the use of rapid solidification powder metallurgy has made it possible to develop a new family of aluminum alloys exhibiting unique properties. One of these materials, dispersion-strengthened (DS) aluminum, is currently being produced for commercial purposes at Raufoss Technology AS, Norway. Dispersion-strengthened aluminum derives its high strength from nanoscale AlN particles embedded in an aluminum matrix. DS Al is expected to be well suited as construction material for high-temperature applications where weight reductions are of particular concern. The present investigation has focused on the wetting behavior of DS aluminum under conditions applicable to brazing. The results from the Sessile drop experiments show that a eutectic Al-Si brazing alloy will completely wet the base metal both under high-vacuum conditions and in controlled argon atmospheres, provided that the partial pressure of oxygen is sufficiently low. The main problem appears to be the stability of the matrix grain structure. In general, the process of grain erosion and coarsening can be controlled by restricting the supply of the brazing alloy so that only a small metal volume is exposed to erosion. In addition, there is a great potential for reducing the thermodynamic driving force of the erosion reaction by proper adjustments of the brazing alloy composition and/or the brazing temperature. Sill, grain boundary liquidation may be a problem which, in turn, may require additions of surface active elements to the filler metal to control the wetting behavior.

  7. The Effect of Anodic Oxide Films on the Nickel-Aluminum Reaction in Aluminum Braze Sheet

    NASA Astrophysics Data System (ADS)

    Tadgell, Colin A.; Wells, Mary A.; Corbin, Stephen F.; Colley, Leo; Cheadle, Brian; Winkler, Sooky

    2017-01-01

    The influence of an anodic oxide surface film on the nickel-aluminum reaction at the surface of aluminum brazing sheet has been investigated. Samples were anodized in a barrier-type solution and subsequently sputtered with nickel. Differential scanning calorimetry (DSC) and metallography were used as the main investigative techniques. The thickness of the anodic film was found to control the reaction between the aluminum substrate and nickel coating. Solid-state formation of nickel-aluminum intermetallic phases occurred readily when a relatively thin oxide film (13 to 25 nm) was present, whereas intermetallic formation was suppressed in the presence of thicker oxides ( 60 nm). At an intermediate oxide film thickness of 35 nm, the Al3Ni phase formed shortly after the initiation of melting in the aluminum substrate. Analysis of DSC traces showed that formation of nickel-aluminum intermetallic phases changed the melting characteristics of the aluminum substrate, and that the extent of this change can be used as an indirect measure of the amount of nickel incorporated into the intermetallic phases.

  8. Air-Impregnated Nanoporous Anodic Aluminum Oxide Layers for Enhancing the Corrosion Resistance of Aluminum.

    PubMed

    Jeong, Chanyoung; Lee, Junghoon; Sheppard, Keith; Choi, Chang-Hwan

    2015-10-13

    Nanoporous anodic aluminum oxide layers were fabricated on aluminum substrates with systematically varied pore diameters (20-80 nm) and oxide thicknesses (150-500 nm) by controlling the anodizing voltage and time and subsequent pore-widening process conditions. The porous nanostructures were then coated with a thin (only a couple of nanometers thick) Teflon film to make the surface hydrophobic and trap air in the pores. The corrosion resistance of the aluminum substrate was evaluated by a potentiodynamic polarization measurement in 3.5 wt % NaCl solution (saltwater). Results showed that the hydrophobic nanoporous anodic aluminum oxide layer significantly enhanced the corrosion resistance of the aluminum substrate compared to a hydrophilic oxide layer of the same nanostructures, to bare (nonanodized) aluminum with only a natural oxide layer on top, and to the latter coated with a thin Teflon film. The hydrophobic nanoporous anodic aluminum oxide layer with the largest pore diameter and the thickest oxide layer (i.e., the maximized air fraction) resulted in the best corrosion resistance with a corrosion inhibition efficiency of up to 99% for up to 7 days. The results demonstrate that the air impregnating the hydrophobic nanopores can effectively inhibit the penetration of corrosive media into the pores, leading to a significant improvement in corrosion resistance.

  9. The Effect of Anodic Oxide Films on the Nickel-Aluminum Reaction in Aluminum Braze Sheet

    NASA Astrophysics Data System (ADS)

    Tadgell, Colin A.; Wells, Mary A.; Corbin, Stephen F.; Colley, Leo; Cheadle, Brian; Winkler, Sooky

    2017-03-01

    The influence of an anodic oxide surface film on the nickel-aluminum reaction at the surface of aluminum brazing sheet has been investigated. Samples were anodized in a barrier-type solution and subsequently sputtered with nickel. Differential scanning calorimetry (DSC) and metallography were used as the main investigative techniques. The thickness of the anodic film was found to control the reaction between the aluminum substrate and nickel coating. Solid-state formation of nickel-aluminum intermetallic phases occurred readily when a relatively thin oxide film (13 to 25 nm) was present, whereas intermetallic formation was suppressed in the presence of thicker oxides ( 60 nm). At an intermediate oxide film thickness of 35 nm, the Al3Ni phase formed shortly after the initiation of melting in the aluminum substrate. Analysis of DSC traces showed that formation of nickel-aluminum intermetallic phases changed the melting characteristics of the aluminum substrate, and that the extent of this change can be used as an indirect measure of the amount of nickel incorporated into the intermetallic phases.

  10. A Single Bout of Aerobic Exercise Reduces Anxiety Sensitivity But Not Intolerance of Uncertainty or Distress Tolerance: A Randomized Controlled Trial.

    PubMed

    LeBouthillier, Daniel M; Asmundson, Gordon J G

    2015-01-01

    Several mechanisms have been posited for the anxiolytic effects of exercise, including reductions in anxiety sensitivity through interoceptive exposure. Studies on aerobic exercise lend support to this hypothesis; however, research investigating aerobic exercise in comparison to placebo, the dose-response relationship between aerobic exercise anxiety sensitivity, the efficacy of aerobic exercise on the spectrum of anxiety sensitivity and the effect of aerobic exercise on other related constructs (e.g. intolerance of uncertainty, distress tolerance) is lacking. We explored reductions in anxiety sensitivity and related constructs following a single session of exercise in a community sample using a randomized controlled trial design. Forty-one participants completed 30 min of aerobic exercise or a placebo stretching control. Anxiety sensitivity, intolerance of uncertainty and distress tolerance were measured at baseline, post-intervention and 3-day and 7-day follow-ups. Individuals in the aerobic exercise group, but not the control group, experienced significant reductions with moderate effect sizes in all dimensions of anxiety sensitivity. Intolerance of uncertainty and distress tolerance remained unchanged in both groups. Our trial supports the efficacy of aerobic exercise in uniquely reducing anxiety sensitivity in individuals with varying levels of the trait and highlights the importance of empirically validating the use of aerobic exercise to address specific mental health vulnerabilities. Aerobic exercise may have potential as a temporary substitute for psychotherapy aimed at reducing anxiety-related psychopathology.

  11. ALUMINUM AND CHROMIUM LEACHING WORKSHOP WHITEPAPER

    SciTech Connect

    McCabe, D; Jeff Pike, J; Bill Wilmarth, B

    2007-04-25

    A workshop was held on January 23-24, 2007 to discuss the status of processes to leach constituents from High Level Waste (HLW) sludges at the Hanford and Savannah River Sites. The objective of the workshop was to examine the needs and requirements for the HLW flowsheet for each site, discuss the status of knowledge of the leaching processes, communicate the research plans, and identify opportunities for synergy to address knowledge gaps. The purpose of leaching of non-radioactive constituents from the sludge waste is to reduce the burden of material that must be vitrified in the HLW melter systems, resulting in reduced HLW glass waste volume, reduced disposal costs, shorter process schedules, and higher facility throughput rates. The leaching process is estimated to reduce the operating life cycle of SRS by seven years and decrease the number of HLW canisters to be disposed in the Repository by 1000 [Gillam et al., 2006]. Comparably at Hanford, the aluminum and chromium leaching processes are estimated to reduce the operating life cycle of the Waste Treatment Plant by 20 years and decrease the number of canisters to the Repository by 15,000-30,000 [Gilbert, 2007]. These leaching processes will save the Department of Energy (DOE) billions of dollars in clean up and disposal costs. The primary constituents targeted for removal by leaching are aluminum and chromium. It is desirable to have some aluminum in glass to improve its durability; however, too much aluminum can increase the sludge viscosity, glass viscosity, and reduce overall process throughput. Chromium leaching is necessary to prevent formation of crystalline compounds in the glass, but is only needed at Hanford because of differences in the sludge waste chemistry at the two sites. Improving glass formulations to increase tolerance of aluminum and chromium is another approach to decrease HLW glass volume. It is likely that an optimum condition can be found by both performing leaching and improving

  12. Energy Assessment Helps Kaiser Aluminum Save Energy and Improve Productivity

    SciTech Connect

    2008-07-01

    The Kaiser Aluminum plant in Sherman, Texas, adjusted controls and made repairs to a furnace for a simple payback of 1 month. Kaiser adopted DOE's Process Heating Assessment and Survey Tool (PHAST) software as the corporate diagnostic tool and has used it to evaluate process heating systems at five other aluminum plants.

  13. Composites Damage Tolerance Workshop

    NASA Technical Reports Server (NTRS)

    Gregg, Wayne

    2006-01-01

    The Composite Damage Tolerance Workshop included participants from NASA, academia, and private industry. The objectives of the workshop were to begin dialogue in order to establish a working group within the Agency, create awareness of damage tolerance requirements for Constellation, and discuss potential composite hardware for the Crew Launch Vehicle (CLV) Upper Stage (US) and Crew Module. It was proposed that a composites damage tolerance working group be created that acts within the framework of the existing NASA Fracture Control Methodology Panel. The working group charter would be to identify damage tolerance gaps and obstacles for implementation of composite structures into manned space flight systems and to develop strategies and recommendations to overcome these obstacles.

  14. Aluminum, parathyroid hormone, and osteomalacia

    SciTech Connect

    Burnatowska-Hledin, M.A.; Kaiser, L.; Mayor, G.H.

    1983-01-01

    Aluminum exposure in man is unavoidable. The occurrence of dialysis dementia, vitamin D-resistant osteomalacia, and hypochromic microcytic anemia in dialysis patients underscores the potential for aluminum toxicity. Although exposure via dialysate and hyperalimentation leads to significant tissue aluminum accumulation, the ubiquitous occurrence of aluminum and the severe pathology associated with large aluminum burdens suggest that smaller exposures via the gastrointestinal tract and lungs could represent an important, though largely unrecognized, public health problem. It is clear that some aluminum absorption occurs with the ingestion of small amounts of aluminum in the diet and medicines, and even greater aluminum absorption is seen in individuals consuming large amounts of aluminum present in antacids. Aluminum absorption is enhanced in the presence of elevated circulating parathyroid hormone. In addition, elevated PTH leads to the preferential deposition of aluminum in brain and bone. Consequently, PTH is likely to be involved in the pathogenesis of toxicities in those organs. PTH excess also seems to lead to the deposition of aluminum in the parathyroid gland. The in vitro demonstration that aluminum inhibits parathyroid hormone release is consistent with the findings of a euparathyroid state in dialysis patients with aluminum related vitamin D-resistant osteomalacia. Nevertheless, it seems likely that hyperparathyroidism is at least initially involved in the pathogenesis of aluminum neurotoxicity and osteomalacia; the increases in tissue aluminum stores are followed by suppression of parathyroid hormone release, which is required for the evolution of osteomalacia. Impaired renal function is not a prerequisite for increased tissue aluminum burdens, nor for aluminum-related organ toxicity. Consequently, it is likely that these diseases will be observed in populations other than those with chronic renal disease.

  15. Comparison of the efficacy and patients’ tolerability of Nepafenac and Ketorolac in the treatment of ocular inflammation following cataract surgery: A meta-analysis of randomized controlled trials

    PubMed Central

    Zhao, Xinyu; Xia, Song; Wang, Erqian

    2017-01-01

    As a new ophthalmic non-steroidal anti-inflammatory drug (NSAID) with prodrug structure, Nepafenac was supposed to have a better efficacy than conventional NSAIDs both in patients’ tolerability and ocular inflammation associated with cataract surgery. However, many current studies reached contradictory conclusions on the superiority of Nepafenac over Ketorolac. The objective of our study is to evaluate the efficacy and patients’ tolerability of Nepafenac and Ketorolac following cataract surgery. To clarify this, we conducted a meta-analysis of randomized controlled trials. Eleven articles were included in this study. The dataset consisted of 1165 patients, including 1175 cataract surgeries. Among them, 574 patients were in the Nepafenac group and 591 in the Ketorolac group. Our analysis indicated that these two drugs were equally effective in controlling post cataract surgery ocular inflammation, reducing macular edema, achieving a better visual ability and maintaining intraoperative mydriasis during cataract surgery. However, Nepafenac was more effective than Ketorolac in reducing the incidence of postoperative conjunctival hyperemia and ocular discomfort. This meta-analysis indicated that topical Nepafenac is superior to Ketorolac in patients’ tolerability following cataract surgery. However, these two drugs are equally desirable in the management of anterior chamber inflammation, visual rehabilitation and intraoperative mydriasis. Given the limitations in our study, more researches with larger sample sizes and focused on more specific indicators such as peak aqueous concentrations of drugs or PEG2 levels are required to reach a firmer conclusion. PMID:28253334

  16. Controlled Directional Solidification of Aluminum - 7 wt Percent Silicon Alloys: Comparison Between Samples Processed on Earth and in the Microgravity Environment Aboard the International Space Station

    NASA Technical Reports Server (NTRS)

    Grugel, Richard N.; Tewari, Surendra N.; Erdman, Robert G.; Poirier, David R.

    2012-01-01

    An overview of the international "MIcrostructure Formation in CASTing of Technical Alloys" (MICAST) program is given. Directional solidification processing of metals and alloys is described, and why experiments conducted in the microgravity environment aboard the International Space Station (ISS) are expected to promote our understanding of this commercially relevant practice. Microstructural differences observed when comparing the aluminum - 7 wt% silicon alloys directionally solidified on Earth to those aboard the ISS are presented and discussed.

  17. Technological, Economic, and Environmental Optimization of Aluminum Recycling

    NASA Astrophysics Data System (ADS)

    Ioana, Adrian; Semenescu, Augustin

    2013-08-01

    The four strategic directions (referring to the entire life cycle of aluminum) are as follows: production, primary use, recycling, and reuse. Thus, in this work, the following are analyzed and optimized: reducing greenhouse gas emissions from aluminum production, increasing energy efficiency in aluminum production, maximizing used-product collection, recycling, and reusing. According to the energetic balance at the gaseous environment level, the conductive transfer model is also analyzed through the finished elements method. Several principles of modeling and optimization are presented and analyzed: the principle of analogy, the principle of concepts, and the principle of hierarchization. Based on these principles, an original diagram model is designed together with the corresponding logic diagram. This article also presents and analyzes the main benefits of aluminum recycling and reuse. Recycling and reuse of aluminum have the main advantage that it requires only about 5% of energy consumed to produce it from bauxite. The aluminum recycling and production process causes the emission of pollutants such as dioxides and furans, hydrogen chloride, and particulate matter. To control these emissions, aluminum recyclers are required to comply with the National Emission Standards for Hazardous Air Pollutants for Secondary Aluminum Production. The results of technological, economic, and ecological optimization of aluminum recycling are based on the criteria function's evaluation in the modeling system.

  18. Proteomic changes associated with expression of a gene (ipt) controlling cytokinin synthesis for improving heat tolerance in a perennial grass species.

    PubMed

    Xu, Yan; Gianfagna, Thomas; Huang, Bingru

    2010-07-01

    Cytokinins (CKs) are known to regulate leaf senescence and affect heat tolerance, but mechanisms underlying CK regulation of heat tolerance are not well understood. A comprehensive proteomic study was conducted to identify proteins altered by the expression of the adenine isopentenyl transferase (ipt) gene controlling CK synthesis and associated with heat tolerance in transgenic plants for a C(3) perennial grass species, Agrostis stolonifera. Transgenic plants with two different inducible promoters (SAG12 and HSP18) and a null transformant (NT) containing the vector without ipt were exposed to 20 degrees C (control) or 35 degrees C (heat stress) in growth chambers. Two-dimensional electrophoresis and mass spectrometry analysis were performed to identify protein changes in leaves and roots in response to ipt expression under heat stress. Transformation with ipt resulted in protein changes in leaves and roots involved in multiple functions, particularly in energy metabolism, protein destination and storage, and stress defence. The abundance levels of six leaf proteins (enolase, oxygen-evolving enhancer protein 2, putative oxygen-evolving complex, Rubisco small subunit, Hsp90, and glycolate oxidase) and nine root proteins (Fd-GOGAT, nucleotide-sugar dehydratase, NAD-dependent isocitrate dehydrogenase, ferredoxin-NADP reductase precursor, putative heterogeneous nuclear ribonucleoprotein A2, ascorbate peroxidase, dDTP-glucose 4-6-dehydratases-like protein, and two unknown proteins) were maintained or increased in at least one ipt transgenic line under heat stress. The diversity of proteins altered in transgenic plants in response to heat stress suggests a regulatory role for CKs in various metabolic pathways associated with heat tolerance in C(3) perennial grass species.

  19. Data-based fault-tolerant control of high-speed trains with traction/braking notch nonlinearities and actuator failures.

    PubMed

    Song, Qi; Song, Yong-Duan

    2011-12-01

    This paper investigates the position and velocity tracking control problem of high-speed trains with multiple vehicles connected through couplers. A dynamic model reflecting nonlinear and elastic impacts between adjacent vehicles as well as traction/braking nonlinearities and actuation faults is derived. Neuroadaptive fault-tolerant control algorithms are developed to account for various factors such as input nonlinearities, actuator failures, and uncertain impacts of in-train forces in the system simultaneously. The resultant control scheme is essentially independent of system model and is primarily data-driven because with the appropriate input-output data, the proposed control algorithms are capable of automatically generating the intermediate control parameters, neuro-weights, and the compensation signals, literally producing the traction/braking force based upon input and response data only--the whole process does not require precise information on system model or system parameter, nor human intervention. The effectiveness of the proposed approach is also confirmed through numerical simulations.

  20. Damage Tolerance: Assessment Handbook. Volume 2: Airframe Damage Tolerance Evaluation

    DTIC Science & Technology

    1993-10-01

    Airframe Damage Tolerance Evaluation NJ 084u5 DTIC FLE 15 1994 Research and Special Programs Administration John A. Volpe National Transportation Systems...permission of John Wiley and Sons, New York, N.Y.] (4-5] CORRODED END Magnes;um Magnesium alloys Zinc Galvanized steel or galvanized wrought iron Aluminum...Reprinted from M M. Ratwani and D.P. Wilhem , iDeelopment andEvaluation of Methods of Plane Strain Fractuire Analysis, Northrop Corporation, AFFDL-TR-73-42

  1. Fatal aluminum phosphide poisoning.

    PubMed

    Anger, F; Paysant, F; Brousse, F; Le Normand, I; Develay, P; Gaillard, Y; Baert, A; Le Gueut, M A; Pepin, G; Anger, J P

    2000-03-01

    A 39-year-old man committed suicide by ingestion of aluminum phosphide, a potent mole pesticide, which was available at the victim's workplace. The judicial authority ordered an autopsy, which ruled out any other cause of death. The victim was discovered 10 days after the ingestion of the pesticide. When aluminum phosphide comes into contact with humidity, it releases large quantities of hydrogen phosphine (PH3), a very toxic gas. Macroscopic examination during the autopsy revealed a very important asphyxia syndrome with major visceral congestion. Blood, urine, liver, kidney, adrenal, and heart samples were analyzed. Phosphine gas was absent in the blood and urine but present in the brain (94 mL/g), the liver (24 mL/g), and the kidneys (41 mL/g). High levels of phosphorus were found in the blood (76.3 mg/L) and liver (8.22 mg/g). Aluminum concentrations were very high in the blood (1.54 mg/L), brain (36 microg/g), and liver (75 microg/g) compared to the usual published values. Microscopic examination revealed congestion of all the organs studied and obvious asphyxia lesions in the pulmonary parenchyma. All these results confirmed a diagnosis of poisoning by aluminum phosphide. This report points out that this type of poisoning is rare and that hydrogen phosphine is very toxic. The phosphorus and aluminum concentrations observed and their distribution in the different viscera are discussed in relation to data in the literature.

  2. Folic acid improve developmental toxicity induced by aluminum sulphates.

    PubMed

    Yassa, Heba A; George, Safaa M; Mohamed, Heba K

    2017-03-01

    Aluminum sulphate has a significant toxic effects for humans. Aluminum is one of the most abundant metal on the Earth crust. The purpose of this study is to evaluate the effects of short term exposure to aluminum sulphate on the bone development of the fetuses in rats, and if folic acid has a protective role upon that effects or not. Forty female rats were used, ten per group, GI served as negative control (receive nothing except normal feeding and water), GII served as positive control (receive water by gastric gavage), GIII treated with aluminum sulphate orally by gastric gavage and GIV treated with aluminum sulphate with folic acid. Mating occurred and known by presence of vaginal plug in the female rats. Rats were killed on day 18 of gestation.

  3. Zopiclone and nitrazepam: a multicenter placebo controlled comparative study of efficacy and tolerance in insomniac patients in general practice.

    PubMed

    Anderson, A A

    1987-01-01

    The efficacy and tolerance of zopiclone were compared with nitrazepam and placebo in a multicenter double-blind parallel-group study in insomniac patients. Following a 7-day placebo washout period, 99 patients (age range 20 to 69 years) received oral capsules of 7.5 mg zopiclone or 5 mg nitrazepam or placebo for 2 weeks. During the fourth week all patients received placebo treatment. Sleep assessments by the patients showed that, compared with placebo, zopiclone and nitrazepam improved all sleep measures of efficacy from the first night and that effectiveness was maintained throughout treatment. The physicians global assessment of efficacy also favored zopiclone and nitrazepam over placebo treatment. Subjective morning drowsiness during treatment was significantly less for zopiclone than for either nitrazepam or placebo and represents a clear advantage for ambulatory patients. No rebound insomnia was evident during a 7 day post-treatment withdrawal period for either zopiclone or nitrazepam. Tolerance was good for all treatments.

  4. Regeneration of aluminum hydride

    DOEpatents

    Graetz, Jason Allan; Reilly, James J; Wegrzyn, James E

    2012-09-18

    The present invention provides methods and materials for the formation of hydrogen storage alanes, AlH.sub.x, where x is greater than 0 and less than or equal to 6 at reduced H.sub.2 pressures and temperatures. The methods rely upon reduction of the change in free energy of the reaction between aluminum and molecular H.sub.2. The change in free energy is reduced by lowering the entropy change during the reaction by providing aluminum in a state of high entropy, and by increasing the magnitude of the change in enthalpy of the reaction or combinations thereof.

  5. Regeneration of aluminum hydride

    DOEpatents

    Graetz, Jason Allan; Reilly, James J.

    2009-04-21

    The present invention provides methods and materials for the formation of hydrogen storage alanes, AlH.sub.x, where x is greater than 0 and less than or equal to 6 at reduced H.sub.2 pressures and temperatures. The methods rely upon reduction of the change in free energy of the reaction between aluminum and molecular H.sub.2. The change in free energy is reduced by lowering the entropy change during the reaction by providing aluminum in a state of high entropy, by increasing the magnitude of the change in enthalpy of the reaction or combinations thereof.

  6. Trajectory-Oriented and Fault-Tolerant-Based Intelligent Process Control for Flexible CIGS PV Module Manufacturing; Final Technical Report, 13 May 2002--30 May 2005

    SciTech Connect

    Simpson, L.; Britt, J.; Birkmire, R.; Vincent, T.

    2005-10-01

    ITN Energy Systems, Inc., and Global Solar Energy, Inc., assisted by NREL's PV Manufacturing R&D program, have continued to advance CIGS production technology by developing trajectory-oriented predictive/control models, fault-tolerance control, control platform development, in-situ sensors, and process improvements. Modeling activities included developing physics-based and empirical models for CIGS and sputter-deposition processing, implementing model-based control, and applying predictive models to the construction of new evaporation sources and for control. Model-based control is enabled by implementing reduced or empirical models into a control platform. Reliability improvement activities include implementing preventive maintenance schedules; detecting failed sensors/equipment and reconfiguring to tinue processing; and systematic development of fault prevention and reconfiguration strategies for the full range of CIGS PV production deposition processes. In-situ sensor development activities have resulted in improved control and indicated the potential for enhanced process status monitoring and control of the deposition processes. Substantial process improvements have been made, including significant improvement in CIGS uniformity, thickness control, efficiency, yield, and throughput. In large measure, these gains have been driven by process optimization, which in turn have been enabled by control and reliability improvements due to this PV Manufacturing R&D program.

  7. Ascorbic acid enhances oxidative stress tolerance and biological control efficacy of Pichia caribbica against postharvest blue mold decay of apples.

    PubMed

    Li, Chaolan; Zhang, Hongyin; Yang, Qiya; Komla, Mahunu Gustav; Zhang, Xiaoyun; Zhu, Shuyun

    2014-07-30

    The effect of ascorbic acid (VC) on improving oxidative stress tolerance of Pichia caribbica and biocontrol efficacy against blue mold caused by Penicillium expansum on apples was investigated. P. caribbica showed susceptibility to the oxidative stress in vitro test, and 250 μg/mL VC treatment improved its oxidative stress tolerance. The higher viability exhibited by VC-treated yeast was associated with a lower intracellular ROS level. The activities of antioxidant enzymes of P. caribbica were improved by VC treatment, including catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPX). Additionally, VC-treated yeast exhibited greater biocontrol activity against P. expansum and faster growth when stored at 25 and 4 °C, respectively, compared to the performance of the non-VC-treated yeast. In response to the VC treatment under oxidative stress, several differentially expressed proteins were identified in P. caribbica, and most of the poteins were confirmed to be related to basic metabolism. Therefore, the application of ascorbic acid is a useful approach to improve oxidative stress tolerance of P. caribbica and its biocontrol efficacy on apples.

  8. Efficacy and tolerability of vilazodone for major depressive disorder: evidence from phase III/IV randomized controlled trials

    PubMed Central

    Shi, Ligen; Wang, Jingyi; Xu, Shenbin; Lu, Yunrong

    2016-01-01

    Vilazodone is a new molecule approved for major depressive disorder (MDD). This report focuses on the efficacy and tolerability of vilazodone for MDD. MEDLINE, EMBASE, and Cochrane Library were searched. A total of 1,930 patients from four trials were included. A significant improvement in the Montgomery–Asberg Depression Rating Scale (MADRS) total score was seen as early as week 2 (P<0.01) in vilazodone-treated patients. The results showed a higher rate of MADRS response with vilazodone compared with placebo (P<0.001). There were also greater improvements in the Hamilton Rating Scale for Anxiety as well as the Clinical Global Impressions (severity of illness and improvement of illness) scores from baseline in vilazodone-treated patients compared to placebo patients (P<0.001). Discontinuation rates due to adverse events were higher with vilazodone than placebo (P=0.0002). The most common adverse events of vilazodone were vomiting, nausea, diarrhea, insomnia, somnolence, dizziness, and dry mouth (P<0.05). Treatment-related effects on sexual function were mild compared to placebo in men (P=0.03). In conclusion, 40 mg/day of vilazodone had a rapid onset of response and showed good improvement in anxiety symptoms as well as good tolerability during short-term treatment (8–10 weeks) for MDD. Further studies should focus on the efficacy and tolerability of vilazodone over a longer duration and should utilize active comparators. PMID:27932864

  9. The unified ICE-CBF pathway provides a transcriptional feedback control of freezing tolerance during cold acclimation in Arabidopsis.

    PubMed

    Kim, Ye Seul; Lee, Minyoung; Lee, Jae-Hyung; Lee, Hyo-Jun; Park, Chung-Mo

    2015-09-01

    During cold acclimation, C-repeat binding factors (CBFs) activate downstream targets, such as cold-regulated genes, leading to the acquisition of freezing tolerance in plants. Inducer of CBF expression 1 (ICE1) plays a key role by activating CBF3 expression in shaping the cold-induced transcriptome. While the ICE1-CBF3 regulon constitutes a major cold acclimation pathway, gene regulatory networks governing the CBF signaling are poorly understood. Here, we demonstrated that ICE1 and its paralog ICE2 induce CBF1, CBF2, and CBF3 by binding to the gene promoters. ICE2, like ICE1, was ubiquitinated by the high expression of osmotically responsive gene 1 (HOS1) E3 ubiquitin ligase. Whereas ICE2-defective ice2-2 mutant did not exhibit any discernible freezing-sensitive phenotypes, ice1-2 ice2-2/+ plant, which is defective in ICE1 and has a heterozygotic ice2 mutation, exhibited significantly reduced freezing tolerance. Accordingly, all three CBF genes were markedly down-regulated in the ice1-2 ice2-2/+ plant, indicating that ICE1 and ICE2 are functionally redundant with different implementations in inducing CBF genes. Together with the negative regulation of CBF3 by CBF2, we propose that the unified ICE-CBF pathway provides a transcriptional feedback of freezing tolerance to sustain plant development and survival during cold acclimation.

  10. Low absorptance porcelain-on-aluminum coating

    NASA Technical Reports Server (NTRS)

    Leggett, H.

    1979-01-01

    Porcelain thermal-control coating for aluminum sheet and foil has solar absorptance of 0.22. Specially formulated coating absorptance is highly stable, changing only 0.03 after 1,000 hours of exposure to simulated sunlight and can be applied by standard commercial methods.

  11. Major and Minor Constituents of Aluminum Alloys

    DTIC Science & Technology

    1986-03-01

    sample alloys obtained by both techniques. Keywords: Atomic Absorption Spectroscopy (AAS), Inductively Coupled Plasma Atomic Emission Spectroscopy(ICP-AES).... absorption spectroscopy and inductively coupled plasma atomic emission spectroscopy are used for the determination of major magnesium, lithium, copper, zinc...An accurate analysis of aluminum alloys is required for quality control and characterization purposes. The two analytical techniques atomic

  12. Cross-repressive interactions between SOC1 and the GATAs GNC and GNL/CGA1 in the control of greening, cold tolerance, and flowering time in Arabidopsis.

    PubMed

    Richter, René; Bastakis, Emmanouil; Schwechheimer, Claus

    2013-08-01

    The paralogous and functionally redundant GATA transcription factors GNC (for GATA, NITRATE-INDUCIBLE, CARBON-METABOLISM INVOLVED) and GNL/CGA1 (for GNC-LIKE/CYTOKININ-RESPONSIVE GATA FACTOR1) from Arabidopsis (Arabidopsis thaliana) promote greening and repress flowering downstream from the phytohormone gibberellin. The target genes of GNC and GNL with regard to flowering time control have not been identified as yet. Here, we show by genetic and molecular analysis that the two GATA factors act upstream from the flowering time regulator SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1) to directly repress SOC1 expression and thereby repress flowering. Interestingly, this analysis inversely also reveals that the MADS box transcription factor SOC1 directly represses GNC and GNL expression to control cold tolerance and greening, two further physiological processes that are under the control of SOC1. In summary, these findings support the case of a cross-repressive interaction between the GATA factors GNC and GNL and the MADS box transcription factor SOC1 in flowering time control on the one side and greening and cold tolerance on the other that may be governed by the various signaling inputs that are integrated at the level of SOC1 expression.

  13. PROCESS FOR REMOVING ALUMINUM COATINGS

    DOEpatents

    Flox, J.

    1959-07-01

    A process is presented for removing aluminum jackets or cans from uranium slugs. This is accomplished by immersing the aluminum coated uranium slugs in an aqueous solution of 9 to 20% sodium hydroxide and 35 to 12% sodium nitrate to selectively dissolve the aluminum coating, the amount of solution being such as to obtain a molar ratio of sodium hydroxide to aluminum of at least

  14. Efficacy, safety, and tolerance of the non-ergoline dopamine agonist pramipexole in the treatment of advanced Parkinson's disease: a double blind, placebo controlled, randomised, multicentre study

    PubMed Central

    Pinter, M; Pogarell, O; Oertel, W

    1999-01-01

    OBJECTIVES—Pramipexole, a non-ergot dopamine D2/D3 receptor agonist, was investigated as an add on drug in advanced parkinsonian patients with motor fluctuations to assess efficacy, safety, and tolerance.
METHODS—Seventy eight patients of either sex with advanced Parkinson's disease and treatment complications such as motor fluctuations were enrolled into a double blind, placebo controlled, randomised, multicentre study (phase II) and assigned to add on treatment with pramipexole (n=34) versus placebo (n=44) to a previously stabilised antiparkinsonian medication (7 week dose titration interval, 4 week maintenance period). The primary end point of efficacy was the change from baseline in the total score of the unified Parkinson's disease rating scale (UPDRS) in the on "period" (2 hours after intake of study medication). Safety and tolerability were assessed on the basis of adverse events, vital signs, laboratory measurements, and ECG recordings.
RESULTS—There was a significant improvement of the pramipexole group in UPDRS total scores, subscores part II, III (activities of daily living and motor examination), and IV (complications of therapy). Mean UPDRS total score decreased by 37.3% under pramipexole compared with 12.2% under placebo (p<0.001). Patients under pramipexole reported an overall reduction in "off" periods of 12%—resulting in 1.7 more hours "on" time a day—compared with an increase in "off" periods of 2% under placebo. There were no unexpected safety results. The adverse event profile disclosed a high tolerability. The most important adverse events under pramipexole were fatigue, dyskinesia, and vivid dreams.
CONCLUSION—Pramipexole administration is an efficacious and well tolerated add on therapy in patients with advanced Parkinson's disease with an improvement in activities of daily living, motor function, and treatment associated complications.

 PMID:10201413

  15. Electrically conductive anodized aluminum coatings

    NASA Technical Reports Server (NTRS)

    Alwitt, Robert S. (Inventor); Liu, Yanming (Inventor)

    2001-01-01

    A process for producing anodized aluminum with enhanced electrical conductivity, comprising anodic oxidation of aluminum alloy substrate, electrolytic deposition of a small amount of metal into the pores of the anodized aluminum, and electrolytic anodic deposition of an electrically conductive oxide, including manganese dioxide, into the pores containing the metal deposit; and the product produced by the process.

  16. Beneficial effects of vildagliptin combined with miglitol on glucose tolerance and islet morphology in diet-controlled db/db mice.

    PubMed

    Ishibashi, Keita; Hara, Akemi; Fujitani, Yoshio; Uchida, Toyoyoshi; Komiya, Koji; Tamaki, Motoyuki; Abe, Hiroko; Ogihara, Takeshi; Kanazawa, Akio; Kawamori, Ryuzo; Watada, Hirotaka

    2013-11-01

    Dipeptidyl peptidase-4 (DPP-4) inhibitors improve glycemic control in patients with type 2 diabetes primarily by increasing plasma active glucagon-like peptide-1 (GLP-1) levels. While various combination therapies based on DPP-4 inhibitors have been proposed for treatment of type 2 diabetes, the effects of combination therapy of DPP-4 inhibitors and alpha-glucosidase inhibitors on β-cell function are less characterized. We evaluated the effects of long-term treatment with vildagliptin, a DPP-4 inhibitor, on metabolic parameters and β-cell function, in combination with miglitol, an alpha-glucosidase inhibitor, in diet-controlled db/db mice. In this study, 6-week-old male db/db mice were provided with standard chow twice a day for 6 weeks. Meal tolerance tests and glucose tolerance tests showed that the combination therapy of vildagliptin with miglitol, but not each alone, suppressed postprandial glycemic excursion, enhanced postprandial active GLP-1 levels and prevented deterioration of glucose tolerance in the db/db mice. The combination treatment did not alter β-cell mass, but resulted in preserved expression of glucose transporter 2, Zinc transporter 8 and MafA and reduced the number of α cells. These results suggest that the combination of vildagliptin and miglitol prevents the development of overt diabetes in diet-controlled pre-diabetic db/db mice by normalizing postprandial glucose and incretin response, and by preserving β-cell structure and the expression of factors essential for β-cell function.

  17. Detachment of Tertiary Dendrite Arms during Controlled Directional Solidification in Aluminum - 7 wt Percent Silicon Alloys: Observations from Ground-based and Microgravity Processed Samples

    NASA Technical Reports Server (NTRS)

    Grugel, Richard N.; Erdman, Robert; Van Hoose, James R.; Tewari, Surendra; Poirier, David

    2012-01-01

    Electron Back Scattered Diffraction results from cross-sections of directionally solidified aluminum 7wt% silicon alloys unexpectedly revealed tertiary dendrite arms that were detached and mis-oriented from their parent arm. More surprisingly, the same phenomenon was observed in a sample similarly processed in the quiescent microgravity environment aboard the International Space Station (ISS) in support of the joint US-European MICAST investigation. The work presented here includes a brief introduction to MICAST and the directional solidification facilities, and their capabilities, available aboard the ISS. Results from the ground-based and microgravity processed samples are compared and possible mechanisms for the observed tertiary arm detachment are suggested.

  18. REMOVAL OF ALUMINUM COATINGS

    DOEpatents

    Peterson, J.H.

    1959-08-25

    A process is presented for dissolving aluminum jackets from uranium fuel elements without attack of the uranium in a boiling nitric acid-mercuric nitrate solution containing up to 50% by weight of nitrtc acid and mercuric nitrate in a concentration of between 0.05 and 1% by weight.

  19. Markets for recovered aluminum

    SciTech Connect

    Not Available

    1993-04-01

    The study describes the operation of the markets for scrap aluminum as an example of how recycling markets are structured, what factors influence the supply of and demand for materials, what projections can be made about recycling markets, and how government policies to increase recycling may affect these markets.

  20. Building an aluminum car

    SciTech Connect

    Ashley, S.

    1994-05-01

    This article examines the increasing use of aluminum in automobiles to decrease weight and consequently increase fuel economy. The topics of the article include federal fuel economy goals, the development of optimum body structure and manufacturing techniques, comparison with steel, cost of materials, weight reduction and recycling of materials.

  1. Fluxless aluminum brazing

    DOEpatents

    Werner, W.J.

    1974-01-01

    This invention relates to a fluxless brazing alloy for use in forming brazed composites made from members of aluminum and its alloys. The brazing alloy consists of 35-55% Al, 10--20% Si, 25-60% Ge; 65-88% Al, 2-20% Si, 2--18% In; 65--80% Al, 15-- 25% Si, 5- 15% Y. (0fficial Gazette)

  2. Aluminum Sulfate 18 Hydrate

    ERIC Educational Resources Information Center

    Young, Jay A.

    2004-01-01

    A chemical laboratory information profile (CLIP) of the chemical, aluminum sulfate 18 hydrate, is presented. The profile lists physical and harmful properties, exposure limits, reactivity risks, and symptoms of major exposure for the benefit of teachers and students using the chemical in the laboratory.

  3. Bonding aluminum beam leads

    NASA Technical Reports Server (NTRS)

    Burkett, F. S.

    1978-01-01

    Report makes it relatively easy for hybrid-circuit manufacturers to convert integrated circuit chips with aluminum bead leads. Report covers: techniques for handling tiny chips; proper geometries for ultrasonic bonding tips; best combinations of pressure, pulse time, and ultrasonic energy for bonding; and best thickness for metal films to which beam leads are bonded.

  4. Fault tolerant magnetic bearings

    SciTech Connect

    Maslen, E.H.; Sortore, C.K.; Gillies, G.T.; Williams, R.D.; Fedigan, S.J.; Aimone, R.J.

    1999-07-01

    A fault tolerant magnetic bearing system was developed and demonstrated on a large flexible-rotor test rig. The bearing system comprises a high speed, fault tolerant digital controller, three high capacity radial magnetic bearings, one thrust bearing, conventional variable reluctance position sensors, and an array of commercial switching amplifiers. Controller fault tolerance is achieved through a very high speed voting mechanism which implements triple modular redundancy with a powered spare CPU, thereby permitting failure of up to three CPU modules without system failure. Amplifier/cabling/coil fault tolerance is achieved by using a separate power amplifier for each bearing coil and permitting amplifier reconfiguration by the controller upon detection of faults. This allows hot replacement of failed amplifiers without any system degradation and without providing any excess amplifier kVA capacity over the nominal system requirement. Implemented on a large (2440 mm in length) flexible rotor, the system shows excellent rejection of faults including the failure of three CPUs as well as failure of two adjacent amplifiers (or cabling) controlling an entire stator quadrant.

  5. Radiation Tolerant Embedded Memory

    DTIC Science & Technology

    2007-11-02

    REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188 Public reporting burden for this collection of information is estimated to average 1 ...currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1 . REPORT DATE (DD-MM-YYYY) 27-06-2003 2. REPORT TYPE SBIR...Tolerant Embedded Memory 1 Table of Contents: Table of Contents

  6. Superconducting structure with layers of niobium nitride and aluminum nitride

    DOEpatents

    Murduck, James M.; Lepetre, Yves J.; Schuller, Ivan K.; Ketterson, John B.

    1989-01-01

    A superconducting structure is formed by depositing alternate layers of aluminum nitride and niobium nitride on a substrate. Deposition methods include dc magnetron reactive sputtering, rf magnetron reactive sputtering, thin-film diffusion, chemical vapor deposition, and ion-beam deposition. Structures have been built with layers of niobium nitride and aluminum nitride having thicknesses in a range of 20 to 350 Angstroms. Best results have been achieved with films of niobium nitride deposited to a thickness of approximately 70 Angstroms and aluminum nitride deposited to a thickness of approximately 20 Angstroms. Such films of niobium nitride separated by a single layer of aluminum nitride are useful in forming Josephson junctions. Structures of 30 or more alternating layers of niobium nitride and aluminum nitride are useful when deposited on fixed substrates or flexible strips to form bulk superconductors for carrying electric current. They are also adaptable as voltage-controlled microwave energy sources.

  7. Superconducting structure with layers of niobium nitride and aluminum nitride

    DOEpatents

    Murduck, J.M.; Lepetre, Y.J.; Schuller, I.K.; Ketterson, J.B.

    1989-07-04

    A superconducting structure is formed by depositing alternate layers of aluminum nitride and niobium nitride on a substrate. Deposition methods include dc magnetron reactive sputtering, rf magnetron reactive sputtering, thin-film diffusion, chemical vapor deposition, and ion-beam deposition. Structures have been built with layers of niobium nitride and aluminum nitride having thicknesses in a range of 20 to 350 Angstroms. Best results have been achieved with films of niobium nitride deposited to a thickness of approximately 70 Angstroms and aluminum nitride deposited to a thickness of approximately 20 Angstroms. Such films of niobium nitride separated by a single layer of aluminum nitride are useful in forming Josephson junctions. Structures of 30 or more alternating layers of niobium nitride and aluminum nitride are useful when deposited on fixed substrates or flexible strips to form bulk superconductors for carrying electric current. They are also adaptable as voltage-controlled microwave energy sources. 8 figs.

  8. Solid-particle erosion of aluminum/particulate ceramic composites

    SciTech Connect

    Goretta, K.C.; Wu, W.; Routbort, J.L. ); Rohatgi, P.K. )

    1990-06-01

    Impact erosion of 2014 aluminum, 2014 aluminum + 20 vol % particulate silicon carbide, and 2014 aluminum + 20 vol % particulate aluminum oxide has been studied at room temperature. The alloys were tested in the as-received and heat-treated conditions. Experiments were conducted with aluminum oxide abrasive in vacuum in a slinger-type apparatus over a range of abrasive size, velocity, and angle of impact. Erosion rates were influenced by reinforcement and heat treatment. Reduced ductility, both overall and local, attributed to reinforcement or heat treatment, caused, under most conditions, more rapid erosion of the composites. The data suggest that erosion rate can be minimized by proper microstructural control, involving reducing reinforcement segregation and the amount of intermetallic compounds. 37 refs., 7 figs.

  9. Pesticide Tolerances

    EPA Pesticide Factsheets

    EPA regulates pesticides used to protect crops and sets limits on the amount of pesticide remaining in or on foods in the U.S. The limits on pesticides on foods are called tolerances in the U.S. (maximum residue limits (MRLs) in many other countries).

  10. SOLDERING OF ALUMINUM BASE METALS

    DOEpatents

    Erickson, G.F.

    1958-02-25

    This patent deals with the soldering of aluminum to metals of different types, such as copper, brass, and iron. This is accomplished by heating the aluminum metal to be soldered to slightly above 30 deg C, rubbing a small amount of metallic gallium into the part of the surface to be soldered, whereby an aluminum--gallium alloy forms on the surface, and then heating the aluminum piece to the melting point of lead--tin soft solder, applying lead--tin soft solder to this alloyed surface, and combining the aluminum with the other metal to which it is to be soldered.

  11. New water-soluble metal working fluids additives from phosphonic acid derivatives for aluminum alloy materials.

    PubMed

    Kohara, Ichitaro; Tomoda, Hideyuki; Watanabe, Shoji

    2007-01-01

    Water-soluble metal working fluids are used for processing of aluminum alloy materials. This short paper describes properties of new additives for water-soluble cutting fluids for aluminum alloy materials. Some alkyldiphosphonic acids were prepared with known method. Amine salts of these phosphonic acids showed anti-corrosion property for aluminum alloy materials. However, they have no hard water tolerance. Monoesters of octylphosphonic acid were prepared by the reaction of octylphosphonic acid dichloride with various alcohols in the presence of triethylamine. Amine salts of monoester of octylphosphonic acid with diethyleneglycol monomethyl ether, ethyleneglycol monomethyl ether and triethyleneglycol monomethyl ether showed both of a good anti-corrosion property for aluminum alloy materials and hard water tolerance.

  12. Fault tolerant linear actuator

    DOEpatents

    Tesar, Delbert

    2004-09-14

    In varying embodiments, the fault tolerant linear actuator of the present invention is a new and improved linear actuator with fault tolerance and positional control that may incorporate velocity summing, force summing, or a combination of the two. In one embodiment, the invention offers a velocity summing arrangement with a differential gear between two prime movers driving a cage, which then drives a linear spindle screw transmission. Other embodiments feature two prime movers driving separate linear spindle screw transmissions, one internal and one external, in a totally concentric and compact integrated module.

  13. Damage Tolerance of Composites

    NASA Technical Reports Server (NTRS)

    Hodge, Andy

    2007-01-01

    Fracture control requirements have been developed to address damage tolerance of composites for manned space flight hardware. The requirements provide the framework for critical and noncritical hardware assessment and testing. The need for damage threat assessments, impact damage protection plans, and nondestructive evaluation are also addressed. Hardware intended to be damage tolerant have extensive coupon, sub-element, and full-scale testing requirements in-line with the Building Block Approach concept from the MIL-HDBK-17, Department of Defense Composite Materials Handbook.

  14. Thermodynamic analysis of contamination by alloying elements in aluminum recycling.

    PubMed

    Nakajima, Kenichi; Takeda, Osamu; Miki, Takahiro; Matsubae, Kazuyo; Nakamura, Shinichiro; Nagasaka, Tetsuya

    2010-07-15

    In previous studies on the physical chemistry of pyrometallurgical processing of aluminum scrap, only a limited number of thermodynamic parameters, such as the Gibbs free energy change of impurity reactions and the variation of activity of an impurity in molten aluminum, were taken into account. In contrast, in this study we thermodynamically evaluated the quantitative removal limit of impurities during the remelting of aluminum scrap; all relevant parameters, such as the total pressure, the activity coefficient of the target impurity, the temperature, the oxygen partial pressure, and the activity coefficient of oxidation product, were considered. For 45 elements that usually occur in aluminum products, the distribution ratios among the metal, slag, and gas phases in the aluminum remelting process were obtained. Our results show that, except for elements such as Mg and Zn, most of the impurities occurred as troublesome tramp elements that are difficult to remove, and our results also indicate that the extent to which the process parameters such as oxygen partial pressure, temperature, and flux composition can be changed in aluminum production is quite limited compared to that for iron and copper production, owing to aluminum's relatively low melting point and strong affinity for oxygen. Therefore, the control of impurities in the disassembly process and the quality of scrap play important roles in suppressing contamination in aluminum recycling.

  15. Numerical Simulation and Chaotic Analysis of an Aluminum Holding Furnace

    NASA Astrophysics Data System (ADS)

    Wang, Ji-min; Zhou, Yuan-yuan; Lan, Shen; Chen, Tao; Li, Jie; Yan, Hong-jie; Zhou, Jie-min; Tian, Rui-jiao; Tu, Yan-wu; Li, Wen-ke

    2014-12-01

    To achieve high heat efficiency, low pollutant emission and homogeneous melt temperature during thermal process of secondary aluminum, taking into account the features of aluminum alloying process, a CFD process model was developed and integrated with heat load and aluminum temperature control model. This paper presented numerical simulation of aluminum holding furnaces using the customized code based on FLUENT packages. Thermal behaviors of aluminum holding furnaces were investigated by probing into main physical fields such as flue gas temperature, velocity, and concentration, and combustion instability of aluminum holding process was represented by chaos theory. The results show that aluminum temperature uniform coefficient firstly decreases during heating phase, then increases and reduces alternately during holding phase, lastly rises during standing phase. Correlation dimension drops with fuel velocity. Maximal Lyapunov exponent reaches to a maximum when air-fuel ratio is close to 1. It would be a clear comprehension about each phase of aluminum holding furnaces to find new technology, retrofit furnace design, and optimize parameters combination.

  16. Pharmacokinetics, Safety and Tolerability of Melissa officinalis Extract which Contained Rosmarinic Acid in Healthy Individuals: A Randomized Controlled Trial

    PubMed Central

    Noguchi-Shinohara, Moeko; Ono, Kenjiro; Hamaguchi, Tsuyoshi; Iwasa, Kazuo; Nagai, Toshitada; Kobayashi, Shoko; Nakamura, Hiroyuki; Yamada, Masahito

    2015-01-01

    The aim of this study was to evaluate the safety, tolerability and pharmacokinetics of single dose of Melissa officinalis extract which contained rosmarinic acid, including food-effects in healthy individuals. A total of eleven healthy individuals were randomly assigned to treatment arms in the two studies [Study 1 (fasted state) and Study 2 (fed state)]. Rosmarinic acid in serum was measured by a coulometric detection method using High-Performance Liquid Chromatography electrochemical detector. The serum concentration of total rosmarinic acid peaked at 1 hour after administration of Melissa officinalis extract containing 500mg rosmarinic acid in fasted state, with a maximum serum concentration 162.20 nmol/ L. The area under the curve for intact rosmarinic acid was calculated from the serum concentration-time profile to be 832.13 nmol • hour/ L. Food intake increases area under the curve and delayed time at which the maximum serum concentration. Rosmarinic acid supplementation did not affect liver, kidney, or blood cell function parameters. No adverse event was reported by any of the participants due to the study treatment. Single dose of Melissa officinalis extract containing 500 mg rosmarinic acid appears to be safe and tolerable in healthy individuals. Food intake increased the exposure of rosmarinic acid and delayed absorption of rosmarinic acid in healthy individuals. Trial Registration Trial Registration: UMIN-CTR UMIN000004997 PMID:25978046

  17. Environmental effects on aluminum fracture

    NASA Technical Reports Server (NTRS)

    Schwartzberg, F. R.; Shepic, J. A.

    1976-01-01

    The sustained load stress corrosion cracking (SCC) threshold for aluminum alloy 214 was determined using smooth (sigma sub TH) and precracked (K sub ISCC) specimens, and cyclic load growth behavior in 3.5% NaCl salt solution was studied. The relationship between K sub ISCC and sigma sub TH was also studied. The work showed that 2124-T851 aluminum alloy in plate gage has a moderately high resistance to stress corrosion attack. Experimental results showed that no SCC occurred in the longitudinal and long transverse directions in any of the tests. Some SCC was found by smooth tests in the short transverse direction, and the data were confirmed by two test methods-sigma sub TH = 275 MN/sq m (40 ksi). No SCC was found from compact specimen tests in any direction: surface flaw and center notch specimens evaluated in the short transverse direction exhibited SCC. The data indicate that stress corrosion behavior is defect, size, and stress dependent, but not entirely in accordance with a stress intensity controlled mechanism.

  18. Do copper tolerant fathead minnows produce copper tolerant adult offspring?

    PubMed Central

    Kolok, Alan S.; L’Etoile-Lopes, Darcy

    2009-01-01

    The objective of this study was to determine if the relative Cu tolerance of fathead minnow parents determines the, relative Cu tolerance of their adult offspring. It was hypothesized that the adult offspring of Cu-tolerant minnows would inherit Cu tolerance from their parents. The relative Cu tolerance of 96 adult fish was determined based upon their reduction in swim performance following a sublethal exposure to 150 μg Cu/l. Control, Cu-tolerant and Cu-susceptible lines of fish were produced and fish within each line were allowed to breed. The offspring were raised to adults, then exposed to one of two sublethal Cu concentrations (150 or 225 (μg Cu/l) for 8 days. There were no significant differences in relative Cu tolerance, as measured by reduction in swim performance, among the three lines of fish at either dose. However, significant differences in whole body Na+ occurred among the fish lines after exposure to 150 μg Cu/l, but not after exposure to 225 μg Cu/l. Significant differences in whole body Cu occurred between Cu-tolerant and Cu-susceptible fish lines after exposure to either Cu dose. The offspring did not inherit the relative Cu tolerance of their parents, however, the selection lines had diverged from each other, particularly with respect to their whole body Cu concentrations after exposure. PMID:15820103

  19. Effect of Low pH and Aluminum Toxicity on the Photosynthetic Characteristics of Different Fast-Growing Eucalyptus Vegetatively Propagated Clones

    PubMed Central

    Yang, Mei; Tan, Ling; Xu, Yuanyuan; Zhao, Yihui; Cheng, Fei; Ye, Shaoming; Jiang, Weixin

    2015-01-01

    Knowing how acid soils and aluminum in soils may limit the growth of Eucalyptus trees in plantations is important because these plantations grow in many tropical and subtropical regions. Seedlings of four vegetatively propagated Eucalyptus clones, E. grandis × E. urophylla ‘GLGU9’(G9), E. grandis × E. urophylla ‘GLGU12’ (G12), E. urophylla × E. camaldulensis ‘GLUC3’ (G3) and E. urophylla ‘GLU4’(G4), were subjected to liquid culture with Hoagland nutrient solution for 40 days, then treated with four different treatments of acid and aluminum for 1 day. The four treatments used either pH 3.0 or 4.0 with or without added aluminum (4.4 mM) in all possible combinations; a control used no added aluminum at pH 4.8. Subsequently, the photosynthetic parameters and morphology of leaves from eucalypt seedlings were determined and observed. The results showed that the tested chlorophyll content, net photosynthetic rate, transpiration rate and water use efficiency were apparently inhibited by aluminum. Under uniform Al concentration (4.4 mM), the Al-induced limitation to photosynthetic parameters increased with pH, indicating acid stimulation to Al toxicity. Among all treatments, the most significant reduction was found in the combination of pH 3.0 and 4.4 mM Al. The photosynthetic and transpiration rates showed similar trends with G9 > G12 > G3 > G4, suggesting that G9 and G12 had higher Al-tolerance than other two clones. Microscopic observation revealed changes in leaf morphology when exposed to Al stress; for example, a reduced thickness of leaf epidermis and palisade tissue, the descendant palisade tissue/spongy tissue ratio and leaf tissue looseness. Overall, the acid and aluminum stress exerted negative effects on the photosynthetic activity of eucalypt seedlings, but the differences in tolerance to Al toxicity between the clones were favorable, offering potential to improve Eucalyptus plantation productivity by selecting Al tolerant clones. PMID

  20. Effect of Low pH and Aluminum Toxicity on the Photosynthetic Characteristics of Different Fast-Growing Eucalyptus Vegetatively Propagated Clones.

    PubMed

    Yang, Mei; Tan, Ling; Xu, Yuanyuan; Zhao, Yihui; Cheng, Fei; Ye, Shaoming; Jiang, Weixin

    2015-01-01

    Knowing how acid soils and aluminum in soils may limit the growth of Eucalyptus trees in plantations is important because these plantations grow in many tropical and subtropical regions. Seedlings of four vegetatively propagated Eucalyptus clones, E. grandis × E. urophylla 'GLGU9'(G9), E. grandis × E. urophylla 'GLGU12' (G12), E. urophylla × E. camaldulensis 'GLUC3' (G3) and E. urophylla 'GLU4'(G4), were subjected to liquid culture with Hoagland nutrient solution for 40 days, then treated with four different treatments of acid and aluminum for 1 day. The four treatments used either pH 3.0 or 4.0 with or without added aluminum (4.4 mM) in all possible combinations; a control used no added aluminum at pH 4.8. Subsequently, the photosynthetic parameters and morphology of leaves from eucalypt seedlings were determined and observed. The results showed that the tested chlorophyll content, net photosynthetic rate, transpiration rate and water use efficiency were apparently inhibited by aluminum. Under uniform Al concentration (4.4 mM), the Al-induced limitation to photosynthetic parameters increased with pH, indicating acid stimulation to Al toxicity. Among all treatments, the most significant reduction was found in the combination of pH 3.0 and 4.4 mM Al. The photosynthetic and transpiration rates showed similar trends with G9 > G12 > G3 > G4, suggesting that G9 and G12 had higher Al-tolerance than other two clones. Microscopic observation revealed changes in leaf morphology when exposed to Al stress; for example, a reduced thickness of leaf epidermis and palisade tissue, the descendant palisade tissue/spongy tissue ratio and leaf tissue looseness. Overall, the acid and aluminum stress exerted negative effects on the photosynthetic activity of eucalypt seedlings, but the differences in tolerance to Al toxicity between the clones were favorable, offering potential to improve Eucalyptus plantation productivity by selecting Al tolerant clones.

  1. Fracture behavior of laminated discontinuously reinforced aluminum material

    SciTech Connect

    Osman, T.M. |; Lewandowski, J.J.; Lesuer, D.R.; Syn, C.K.; Hunt, W.H. Jr

    1994-05-01

    Laminated metallic composites are being developed for applications which require high specific stiffness and fracture resistance. Recent work with laminated discontinuously reinforced aluminum (DRA) materials has demonstrated the potential for marked improvements in stable crack growth resistance via extrinsic toughening. The purpose of this work is to compare the fracture mechanisms and fracture resistance of laminated DRA materials to unlaminated DRA materials. In particular, the production of extensive stable crack growth and the associated improvement in damage tolerance in DRA laminates is documented.

  2. Central role of the flowering repressor ZCCT2 in the redox control of freezing tolerance and the initial development of flower primordia in wheat

    PubMed Central

    2014-01-01

    Background As both abiotic stress response and development are under redox control, it was hypothesised that the pharmacological modification of the redox environment would affect the initial development of flower primordia and freezing tolerance in wheat (Triticum aestivum L.). Results Pharmacologically induced redox changes were monitored in winter (T. ae. ssp. aestivum cv. Cheyenne, Ch) and spring (T. ae. ssp. spelta; Tsp) wheat genotypes grown after germination at 20/17°C for 9 d (chemical treatment: last 3 d), then at 5°C for 21 d (chemical treatment: first 4 d) and subsequently at 20/17°C for 21 d (recovery period). Thiols and their disulphide forms were measured and based on these data reduction potentials were calculated. In the freezing-tolerant Ch the chemical treatments generally increased both the amount of thiol disulphides and the reduction potential after 3 days at 20/17°C. In the freezing-sensitive Tsp a similar effect of the chemicals on these parameters was only observed after the continuation of the treatments for 4 days at 5°C. The applied chemicals slightly decreased root fresh weight and increased freezing tolerance in Ch, whereas they increased shoot fresh weight in Tsp after 4 days at 5°C. As shown after the 3-week recovery at 20/17°C, the initial development of flower primordia was accelerated in Tsp, whereas it was not affected by the treatments in Ch. The chemicals differently affected the expression of ZCCT2 and that of several other genes related to freezing tolerance and initial development of flower primordia in Ch and Tsp after 4 d at 5°C. Conclusions Various redox-altering compounds and osmotica had differential effects on glutathione disulphide content and reduction potential, and consequently on the expression of the flowering repressor ZCCT2 in the winter wheat Ch and the spring wheat Tsp. We propose that the higher expression of ZCCT2 in Ch may be associated with activation of genes of cold acclimation and its lower

  3. Interactions of aluminum with forest soils and vegetation: Implications for acid deposition

    SciTech Connect

    Maynard, A.A.

    1989-01-01

    Recent evidence suggests that an important ecological consequence of acidic deposition is increased aluminum mobilization. There is concern that increased aluminum activity may produce toxic effects in forested ecosystems. My studies were concerned with the behavior of pedogenic and added aluminum in soils derived from chemically different parent material. Soil aluminum was related to the aluminum content of the vegetation found growing in the soils. In addition, aluminum levels of forest litter was compared to levels determined 40 years ago. Field, greenhouse, and laboratory investigations were conducted in which the effects of aluminum concentration on germination and early growth was determined. Soils were then used in greenhouse and laboratory studies to establish patterns of soil and plant aluminum behavior with implications to acid deposition. Results show that the amount of aluminum extracted was related to the pH value of the extracting solution and to the chemical characteristics of the soil. Some acid rain solutions extracted measurable amounts of aluminum from selected primary minerals. Germination and early growth of Pinus radiata was controlled by levels of aluminum in the soil or in solution. Field studies indicated that most forest species were sensitive to rising levels of aluminum in the soil. In general, ferns and fern allies were less sensitive to very high levels of aluminum in the soil, continuing to grow when more advanced dicots have disappeared. Aluminum tissue levels of all species were related to the concentration of aluminum in the soil as was the reappearance of species. Aluminum levels in leaf litter have risen at least 50% in the last 40 years. These values were consistent over 3 years. The implications to acid deposition were discussed.

  4. Zero-tolerance for faecal contamination of carcasses as a tool in the control of O157 VTEC infections.

    PubMed

    Heuvelink, A E; Roessink, G L; Bosboom, K; de Boer, E

    2001-05-21

    The Dutch government, the meat producers organisation and the meat industry have recognised O157 VTEC as an important public health hazard, and agreed on the necessity to improve the hygiene in Dutch cattle- and calf-slaughtering establishments. This paper reports activities within a national action programme to achieve this objective, "Zero-tolerance for faecal contamination during slaughter of cattle and calves". The study included inspection of hygienic performances in slaughterhouses, and visual and microbiological (aerobic plate counts, Enterobacteriaceae counts and O157 VTEC presence/absence on visually clean cattle and calf carcasses) assessment of carcass cleanliness. Initial studies concluded that the hygienic performances in the Dutch cattle and calf slaughterhouses should be immediately improved. In 52% of the slaughterhouses inspected, carcasses were observed to be contaminated with hide, hair or faeces. Around 45% of the slaughterhouses had constructural deficiencies likely to lead to structural cross-contamination of carcasses, by direct carcass-carcass contact, or by indirect contacts with floors, walls or steps. In 39% of the slaughterhouses, cleaning and disinfection procedures were inadequate. Visual inspection of chilled carcasses found that in 11 of the 27 slaughterhouses visited, more than 10% of the carcasses were visibly contaminated. In 6 of the 27 slaughterhouses visited, more than 50% of the carcasses inspected were visibly contaminated. Microbiological analysis of visually clean carcasses noted contamination levels similar to those reported from other countries. O157 VTEC were not isolated during this study. Circulation of these findings lead to increased efforts by all parties to fulfil the requirements of the statutory "Zero-tolerance" programme. A follow-up study noted a significant decrease in the proportions of faecally contaminated carcasses, i.e., 7% of chilled carcasses were visibly contaminated with faeces, as opposed to 22

  5. Nitrate tolerance.

    PubMed

    Parker, J O

    1987-11-16

    The organic nitrates are the most widely used agents in the management of patients with angina pectoris. When initially administered by the oral route, the nitrates produce profound changes in systemic hemodynamics and significant and prolonged improvement in exercise duration. It has been shown that during short periods of regular oral nitrate administration, the hemodynamic, antiischemic and antianginal effects of the nitrates are greatly reduced. Thus, when initially administered, oral isosorbide dinitrate prolongs exercise duration for a period of several hours, but during sustained 4-times-daily therapy, exercise tolerance is improved for only 2 hours after administration. Studies with transdermal preparations of isosorbide dinitrate and nitroglycerin also show improvement during short-term administration for up to 8 hours, but after several days of once-daily therapy, the effects of these agents are similar to placebo. It is apparent that nitrate tolerance is a clinically relevant problem. Although tolerance develops rapidly during nitrate therapy, it is reversed promptly during nitrate-free periods. Oral nitrates maintain their antianginal effects when given 2 or 3 times daily with provision of a nitrate-free period. Studies are currently underway to investigate the effects of intermittent administration schedules with transdermal nitrate preparations.

  6. Double-blind, randomized, placebo-controlled study of safety, tolerability, pharmacokinetics and pharmacodynamics of TAK-683, an investigational metastin analogue in healthy men

    PubMed Central

    Scott, Graham; Ahmad, Irfan; Howard, Katy; MacLean, David; Oliva, Cristina; Warrington, Steve; Wilbraham, Darren; Worthington, Paul

    2013-01-01

    Aims Two randomized, double-blind, placebo-controlled studies were performed to characterize the safety, tolerability, pharmacokinetics (PK) and pharmacodynamics (PD) of the investigational metastin analogue, TAK-683, in healthy men. Methods We first investigated a single subcutaneous (s.c.) dose of TAK-683 (0.01–2.0 mg) in 60 subjects (TAK-683, n = 42; placebo, n = 18). We then assessed a single s.c. bolus of 0.03–1.0 mg TAK-683 on day 1, followed by a 0.01–2.0 mg day−1 continuous infusion on days 2–13, to simulate a depot formulation, in 30 subjects (TAK-683, n = 25; placebo, n = 5) for 14 days. Results TAK-683 was well tolerated up to a dose of 2.0 mg day−1 by continuous s.c. infusion for 14 days. Adverse events were similar between TAK-683 and placebo subjects at all dose levels. TAK-683 plasma concentrations generally increased in proportion to dose with single and continuous dosing, with steady-state concentrations achieved by day 2 of continuous dosing. TAK-683 at 2.0 mg day−1 suppressed testosterone below castration level (<50 ng dl−1) in four of five subjects by day 7 of continuous dosing. Luteinizing hormone and follicle stimulating hormone concentrations were suppressed with TAK-683 continuous dosing compared with placebo by up to 70 and 43%, respectively, but this was not consistently dose-dependent. Conclusions In healthy men, s.c. administration of TAK-683 was well tolerated at all dose levels. The PK profile of TAK-683 was favourable, and TAK-683 suppressed testosterone profoundly during continuous dosing. Further investigation of metastin analogues is warranted for the treatment of castration-resistant prostate cancer. PMID:22803642

  7. Tolerance and efficacy of a low dose of the calcimimetic agent cinacalcet in controlling moderate to severe secondary hyperparathyroidism in hemodialysis patients.

    PubMed

    Bashir, Salah O; Omer, Hayder A; Aamer, Mahmoud A; Somialy, Rashid; Morsy, Mohamed D

    2015-11-01

    Secondary hyperparathyroidism is almost a constant feature in chronic kidney disease (CKD) patients maintained on hemodialysis (HD). Calcimimetic agents appear to offer an alternative to surgery in controlling secondary hyperparathyroidism in these patients. Recent studies provide conflicting data on the benefits, efficacy and tolerance of cinacalcet as first-line therapy for the treatment of secondary hyperparathyroidism in CKD. This study was designed to investigate the efficacy and tolerance of a low dose of the calcimimetic agent cinacalcet in patients on long-term HD having moderate to severe secondary hyperparathyroidism. Twenty five adult male patients on HD for more than three years were included in the study. All had moderate to severe secondary hyperparathyroidism with serum intact parathyroid hormone (iPTH) >50 pmol/L, resistant to conventional treatment. We used the targets of Chronic Kidney Disease: Outcomes Quality Initiative (K/DOQI) clinical guidelines as optimal target of serum iPTH, calcium and phosphate. Patients were administered cinacalcet as a single oral daily dose of 30 mg and were followed-up for six months. Cinacalcet treatment for six months resulted in a significant reduction in the serum phosphate and iPTH levels while the serum calcium levels remained unchanged. Thirty-six percent of the patients attained the recommended serum iPTH levels, 40% achieved significant reduction of the serum iPTH levels and 24% showed no favorable response. Only one patient dropped out because of severe gastrointestinal symptoms. Our results suggest that treatment of CKD patients, having moderate to severe secondary hyperparathyroidism, with low-dose cinacalcet is effective and well tolerated.

  8. The efficacy and tolerability of risedronate on bone mineral density and bone turnover markers in osteoporotic Chinese women: a randomized placebo-controlled study.

    PubMed

    Leung, Jenny Y Y; Ho, Andrew Y Y; Ip, T P; Lee, Gavin; Kung, Annie W C

    2005-02-01

    Osteoporosis has become an important health problem in postmenopausal Asian populations as the prevalence of hip and vertebral fractures in some Asian countries has risen to approach that of Caucasian populations. Risedronate, a pyridinyl-bisphosphonate agent, is a potent inhibitor of bone resorption. Risedronate increases bone mineral density (BMD), reduces markers of bone turnover, and reduces the risk of fractures in Caucasian postmenopausal women. To determine the efficacy and tolerability of risedronate in Chinese, a multicenter, randomized, double blind, placebo controlled study was performed in Hong Kong. Sixty-five (65) postmenopausal osteoporotic Southern Chinese women, aged 67+/-6 years, were randomly assigned to receive either risedronate 5 mg daily (n=31) or placebo (n=34) for 12 months. All women received calcium carbonate 500 mg daily and vitamin D 400 IU daily. Mean baseline BMD T-score at the spine and total hip was -3.4 and -2.6, respectively. A significant increase in spine BMD was already evident at month 3 of risedronate treatment (P<0.001). Risedronate significantly increased BMD and reduced bone turnover markers as compared with placebo. The risedronate group had significant increase in BMD at 12 months at both the spine and hip when compared with the placebo group (L1-4 6.6% vs. 0.4%, P<0.001; total hip 2.7% vs. 0.3, P<0.0001; femoral neck 1.8% vs. 1.1%, P<0.02; trochanter 4% vs. 1.1%, P<0.0001, respectively). Significant changes in urine N-telopeptide (NTx) and serum osteocalcin were evident as early as 1 and 3 months, respectively, with risedronate treatment. No significant changes were seen in both BMD and bone markers in the placebo group. Risedronate was well tolerated without major adverse effects. We conclude that risedronate is an effective and well-tolerated agent for the treatment of postmenopausal osteoporosis in Asian population.

  9. Comparative efficacy and tolerability of duloxetine, pregabalin, and milnacipran for the treatment of fibromyalgia: a Bayesian network meta-analysis of randomized controlled trials.

    PubMed

    Lee, Young Ho; Song, Gwan Gyu

    2016-05-01

    The aim of this study was to assess the relative efficacy and tolerability of duloxetine, pregabalin, and milnacipran at the recommended doses in patients with fibromyalgia. Randomized controlled trials (RCTs) examining the efficacy and safety of duloxetine 60 mg, pregabalin 300 mg, pregabalin 150 mg, milnacipran 200 mg, and milnacipran 100 mg compared to placebo in patients with fibromyalgia were included in this Bayesian network meta-analysis. Nine RCTs including 5140 patients met the inclusion criteria. The proportion of patients with >30 % improvement from baseline in pain was significantly higher in the duloxetine 60 mg, pregabalin 300 mg, milnacipran 100 mg, and milnacipran 200 mg groups than in the placebo group [pairwise odds ratio (OR) 2.33, 95 % credible interval (CrI) 1.50-3.67; OR 1.68, 95 % CrI 1.25-2.28; OR 1.62, 95 % CrI 1.16-2.25; and OR 1.61; 95 % CrI 1.15-2.24, respectively]. Ranking probability based on the surface under the cumulative ranking curve (SUCRA) indicated that duloxetine 60 mg had the highest probability of being the best treatment for achieving the response level (SUCRA = 0.9431), followed by pregabalin 300 mg (SUCRA = 0.6300), milnacipran 100 mg (SUCRA = 0.5680), milnacipran 200 mg (SUCRA = 0.5617), pregabalin 150 mg (SUCRA = 0.2392), and placebo (SUCRA = 0.0580). The risk of withdrawal due to adverse events was lower in the placebo group than in the pregabalin 300 mg, duloxetine 60 mg, milnacipran 100 mg, and milnacipran 200 mg groups. However, there was no significant difference in the efficacy and tolerability between the medications at the recommended doses. Duloxetine 60 mg, pregabalin 300 mg, milnacipran 100 mg, and milnacipran 200 mg were more efficacious than placebo. However, there was no significant difference in the efficacy and tolerability between the medications at the recommended doses.

  10. Effects of aluminum and zirconia contents on the reaction bonded aluminum oxide process

    NASA Astrophysics Data System (ADS)

    Sheedy, Paul Martin

    The effects of aluminum and ZrO2 contents on the reaction and sintering of reaction bonded aluminum oxide (RBAO) were investigated. It was apparent that ZrO2-containing RBAO powders with higher initial aluminum contents (>45 vol%) were increasingly more difficult to react and sinter. During oxidation in air, samples often underwent a self-propagating high-temperature synthesis (SHS) reaction which led to catastrophic failure. This reaction and cracking behavior was more pronounced with increasing aluminum and ZrO2 contents of the powders. Subsequently, it was shown that the SHS reaction was actually two combustion phenomena: a thermal explosion reaction on the surface of the sample between aluminum and oxygen, which (in ZrO2-containing samples) triggered a self propagating aluminothermic reduction of ZrO2, forming Al2O3 and Al 3Zr. Therefore, methods for controlling the rate of the initial oxidation reaction were effective since both SHS reactions were prevented. Despite the use of controlled firing, initial samples with increasing aluminum contents proved difficult to densify. It was found that in all RBAO samples (regardless of ZrO2 content), the reactively formed Al 2O3 underwent the gamma to alpha-Al2O 3 transformation, which resulted in the development of a vermicular microstructure. In ZrO2-containing RBAO samples, this transformation was inhibited and occurred concurrently with the start of densification. In addition, the start of bulk shrinkage in these samples was delayed and the densification rates were decreased in comparison to samples without ZrO 2. This ultimately resulted in a decrease in the limiting density to which ZrO2-containing RBAO samples could be sintered. Surprisingly, in samples without ZrO2, increasing the aluminum content did not appear to have any effects upon the densification behavior of RBAO. In examining RBAO samples with similar aluminum contents but increasing ZrO2 contents, it became apparent that the grain growth inhibiting

  11. Aluminum Carbothermic Technology

    SciTech Connect

    Bruno, Marshall J.

    2005-03-31

    This report documents the non-proprietary research and development conducted on the Aluminum Carbothermic Technology (ACT) project from contract inception on July 01, 2000 to termination on December 31, 2004. The objectives of the program were to demonstrate the technical and economic feasibility of a new carbothermic process for producing commercial grade aluminum, designated as the ''Advanced Reactor Process'' (ARP). The scope of the program ranged from fundamental research through small scale laboratory experiments (65 kW power input) to larger scale test modules at up to 1600 kW power input. The tasks included work on four components of the process, Stages 1 and 2 of the reactor, vapor recovery and metal alloy decarbonization; development of computer models; and economic analyses of capital and operating costs. Justification for developing a new, carbothermic route to aluminum production is defined by the potential benefits in reduced energy, lower costs and more favorable environmental characteristics than the conventional Hall-Heroult process presently used by the industry. The estimated metrics for these advantages include energy rates at approximately 10 kWh/kg Al (versus over 13 kWh/kg Al for Hall-Heroult), capital costs as low as $1250 per MTY (versus 4,000 per MTY for Hall-Heroult), operating cost reductions of over 10%, and up to 37% reduction in CO2 emissions for fossil-fuel power plants. Realization of these benefits would be critical to sustaining the US aluminum industries position as a global leader in primary aluminum production. One very attractive incentive for ARP is its perceived ability to cost effectively produce metal over a range of smelter sizes, not feasible for Hall-Heroult plants which must be large, 240,000 TPY or more, to be economical. Lower capacity stand alone carbothermic smelters could be utilized to supply molten metal at fabrication facilities similar to the mini-mill concept employed by the steel industry. Major

  12. 21 CFR 73.1645 - Aluminum powder.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Aluminum powder. 73.1645 Section 73.1645 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1645 Aluminum powder. (a) Identity. (1) The color additive aluminum powder shall be composed of finely divided particles of aluminum prepared from virgin aluminum....

  13. 21 CFR 73.1645 - Aluminum powder.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Aluminum powder. 73.1645 Section 73.1645 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1645 Aluminum powder. (a) Identity. (1) The color additive aluminum powder shall be composed of finely divided particles of aluminum prepared from virgin aluminum....

  14. 21 CFR 73.1645 - Aluminum powder.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Aluminum powder. 73.1645 Section 73.1645 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1645 Aluminum powder. (a) Identity. (1) The color additive aluminum powder shall be composed of finely divided particles of aluminum prepared from virgin aluminum....

  15. 21 CFR 73.1645 - Aluminum powder.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Aluminum powder. 73.1645 Section 73.1645 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1645 Aluminum powder. (a) Identity. (1) The color additive aluminum powder shall be composed of finely divided particles of aluminum prepared from virgin aluminum....

  16. 21 CFR 73.1645 - Aluminum powder.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Aluminum powder. 73.1645 Section 73.1645 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1645 Aluminum powder. (a) Identity. (1) The color additive aluminum powder shall be composed of finely divided particles of aluminum prepared from virgin aluminum....

  17. The safety and tolerability of vortioxetine: Analysis of data from randomized placebo-controlled trials and open-label extension studies.

    PubMed

    Baldwin, David S; Chrones, Lambros; Florea, Ioana; Nielsen, Rebecca; Nomikos, George G; Palo, William; Reines, Elin

    2016-03-01

    The safety and tolerability of vortioxetine in adults with major depressive disorder was assessed. Tolerability was based on the nature, incidence and severity of treatment-emergent adverse events (TEAEs) during acute (6/8) week treatment in 11 randomized, double-blind placebo-controlled short-term studies in major depressive disorder: six with an active reference. Symptoms following discontinuation were assessed through the Discontinuation-Emergent Signs and Symptoms checklist in three studies. Long-term (⩽52 weeks) tolerability was evaluated in five open-label extension studies. Patients (n =5701) were acutely treated with either placebo (n=1817), vortioxetine (5-20mg/day; n=3018), venlafaxine XR (225mg/day; n=113) or duloxetine (60mg/day; n=753). The withdrawal rate due to TEAEs during treatment with vortioxetine (5-20mg/day) was 4.5-7.8%, compared with placebo (3.6%), venlafaxine XR (14.2%) or duloxetine (8.8%). Common TEAEs (incidence ⩾5% and >2 × placebo) with vortioxetine (5-20mg/day) were nausea (20.9-31.2%) and vomiting (2.9-6.5%). For vortioxetine (5-20mg/day), the incidence of TEAEs associated with insomnia was 2.0-5.1% versus 4.0% for placebo, and with sexual dysfunction 1.6-1.8% versus 1.0% for placebo. Discontinuation symptoms as assessed by the mean Discontinuation-Emergent Signs and Symptoms total score after abrupt discontinuation were comparable to placebo in the first and second week. Vortioxetine had no effect relative to placebo on clinical laboratory parameters, body weight, heart rate or blood pressure. Vortioxetine showed no clinically relevant effect on ECG parameters, including the QTcF interval. In long-term treatment, no new types of TEAEs were seen; the mean weight gain was 0.7-0.8kg. Thus, vortioxetine (5-20mg/day) appears safe and generally well tolerated in the treatment of major depressive disorder.

  18. The safety and tolerability of vortioxetine: Analysis of data from randomized placebo-controlled trials and open-label extension studies

    PubMed Central

    Baldwin, David S; Chrones, Lambros; Florea, Ioana; Nielsen, Rebecca; Nomikos, George G; Palo, William; Reines, Elin

    2016-01-01

    The safety and tolerability of vortioxetine in adults with major depressive disorder was assessed. Tolerability was based on the nature, incidence and severity of treatment-emergent adverse events (TEAEs) during acute (6/8) week treatment in 11 randomized, double-blind placebo-controlled short-term studies in major depressive disorder: six with an active reference. Symptoms following discontinuation were assessed through the Discontinuation-Emergent Signs and Symptoms checklist in three studies. Long-term (⩽52 weeks) tolerability was evaluated in five open-label extension studies. Patients (n =5701) were acutely treated with either placebo (n=1817), vortioxetine (5–20mg/day; n=3018), venlafaxine XR (225mg/day; n=113) or duloxetine (60mg/day; n=753). The withdrawal rate due to TEAEs during treatment with vortioxetine (5–20mg/day) was 4.5–7.8%, compared with placebo (3.6%), venlafaxine XR (14.2%) or duloxetine (8.8%). Common TEAEs (incidence ⩾5% and >2 × placebo) with vortioxetine (5–20mg/day) were nausea (20.9–31.2%) and vomiting (2.9–6.5%). For vortioxetine (5–20mg/day), the incidence of TEAEs associated with insomnia was 2.0–5.1% versus 4.0% for placebo, and with sexual dysfunction 1.6–1.8% versus 1.0% for placebo. Discontinuation symptoms as assessed by the mean Discontinuation-Emergent Signs and Symptoms total score after abrupt discontinuation were comparable to placebo in the first and second week. Vortioxetine had no effect relative to placebo on clinical laboratory parameters, body weight, heart rate or blood pressure. Vortioxetine showed no clinically relevant effect on ECG parameters, including the QTcF interval. In long-term treatment, no new types of TEAEs were seen; the mean weight gain was 0.7–0.8kg. Thus, vortioxetine (5–20mg/day) appears safe and generally well tolerated in the treatment of major depressive disorder. PMID:26864543

  19. pH Response Transcription Factor PacC Controls Salt Stress Tolerance and Expression of the P-Type Na+-ATPase Ena1 in Fusarium oxysporum

    PubMed Central

    Caracuel, Zaira; Casanova, Carlos; Roncero, M. Isabel G.; Di Pietro, Antonio; Ramos, José

    2003-01-01

    Fungi possess efficient mechanisms of pH and ion homeostasis, allowing them to grow over a wide range of environmental conditions. In this study, we addressed the role of the pH response transcription factor PacC in salt tolerance of the vascular wilt pathogen Fusarium oxysporum. Loss-of-function pacC+/− mutants showed increased sensitivity to Li+ and Na+ and accumulated higher levels of these cations than the wild type. In contrast, strains expressing a dominant activating pacCc allele were more salt tolerant and had lower intracellular Li+ and Na+ concentrations. Although the kinetics of Li+ influx were not altered by mutations in pacC, we found that Li+ efflux at an alkaline, but not at an acidic, ambient pH was significantly reduced in pacC+/− loss-of-function mutants. To explore the presence of a PacC-dependent efflux mechanism in F. oxysporum, we cloned ena1 encoding an orthologue of the yeast P-type Na+-ATPase ENA1. Northern analysis revealed that efficient transcriptional activation of ena1 in F. oxysporum required the presence of high Na+ concentrations and alkaline ambient pH and was dependent on PacC function. We propose a model in which PacC controls ion homeostasis in F. oxysporum at a high pH by activating expression of ena1 coordinately with a second Na+-responsive signaling pathway. PMID:14665459

  20. Ignition and Combustion of Aluminum and Aluminum/Carbon Slurry Agglomerates.

    DTIC Science & Technology

    1986-05-01

    aluminum drople4 the vapor-phase combustion analysis of Law was adapted and extended to a’ ount for oxide build-up and convective effects . The...steady, instantaneously adjusting to changing boundary conditions at the droplet surface. 2. Convective effects are treated using film theory for both...to the aluminum phase change is controlled by the combined effects of convection and radiation as given below. ml C T qc q(9 Al p,Al d’ = q q (29