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Sample records for controls genome stability

  1. Ddb1 controls genome stability and meiosis in fission yeast

    DEFF Research Database (Denmark)

    Holmberg, Christian Henrik; Fleck, Oliver; Hansen, H. A.

    2005-01-01

    The human UV-damaged DNA-binding protein Ddb1 associates with cullin 4 ubiquitin ligases implicated in nucleotide excision repair (NER). These complexes also contain the signalosome (CSN), but NER-relevant ubiquitination targets have not yet been identified. We report that fission yeast Ddb1, Cul...... degradation becomes essential when cells differentiate into meiosis. These results suggest that Ddb1, along with Cullin 4 and the signalosome, constitute a major pathway controlling genome stability, repair, and differentiation via RNR regulation....

  2. YAP controls retinal stem cell DNA replication timing and genomic stability.

    Science.gov (United States)

    Cabochette, Pauline; Vega-Lopez, Guillermo; Bitard, Juliette; Parain, Karine; Chemouny, Romain; Masson, Christel; Borday, Caroline; Hedderich, Marie; Henningfeld, Kristine A; Locker, Morgane; Bronchain, Odile; Perron, Muriel

    2015-09-22

    The adult frog retina retains a reservoir of active neural stem cells that contribute to continuous eye growth throughout life. We found that Yap, a downstream effector of the Hippo pathway, is specifically expressed in these stem cells. Yap knock-down leads to an accelerated S-phase and an abnormal progression of DNA replication, a phenotype likely mediated by upregulation of c-Myc. This is associated with an increased occurrence of DNA damage and eventually p53-p21 pathway-mediated cell death. Finally, we identified PKNOX1, a transcription factor involved in the maintenance of genomic stability, as a functional and physical interactant of YAP. Altogether, we propose that YAP is required in adult retinal stem cells to regulate the temporal firing of replication origins and quality control of replicated DNA. Our data reinforce the view that specific mechanisms dedicated to S-phase control are at work in stem cells to protect them from genomic instability.

  3. Drosophila MOF controls Checkpoint protein2 and regulates genomic stability during early embryogenesis

    Directory of Open Access Journals (Sweden)

    Pushpavalli Sreerangam NCVL

    2013-01-01

    Full Text Available Abstract Background In Drosophila embryos, checkpoints maintain genome stability by delaying cell cycle progression that allows time for damage repair or to complete DNA synthesis. Drosophila MOF, a member of MYST histone acetyl transferase is an essential component of male X hyperactivation process. Until recently its involvement in G2/M cell cycle arrest and defects in ionizing radiation induced DNA damage pathways was not well established. Results Drosophila MOF is highly expressed during early embryogenesis. In the present study we show that haplo-insufficiency of maternal MOF leads to spontaneous mitotic defects like mitotic asynchrony, mitotic catastrophe and chromatid bridges in the syncytial embryos. Such abnormal nuclei are eliminated and digested in the yolk tissues by nuclear fall out mechanism. MOF negatively regulates Drosophila checkpoint kinase 2 tumor suppressor homologue. In response to DNA damage the checkpoint gene Chk2 (Drosophila mnk is activated in the mof mutants, there by causing centrosomal inactivation suggesting its role in response to genotoxic stress. A drastic decrease in the fall out nuclei in the syncytial embryos derived from mof1/+; mnkp6/+ females further confirms the role of DNA damage response gene Chk2 to ensure the removal of abnormal nuclei from the embryonic precursor pool and maintain genome stability. The fact that mof mutants undergo DNA damage has been further elucidated by the increased number of single and double stranded DNA breaks. Conclusion mof mutants exhibited genomic instability as evidenced by the occurance of frequent mitotic bridges in anaphase, asynchronous nuclear divisions, disruption of cytoskeleton, inactivation of centrosomes finally leading to DNA damage. Our findings are consistent to what has been reported earlier in mammals that; reduced levels of MOF resulted in increased genomic instability while total loss resulted in lethality. The study can be further extended using

  4. Drosophila MOF controls Checkpoint protein2 and regulates genomic stability during early embryogenesis.

    Science.gov (United States)

    Pushpavalli, Sreerangam N C V L; Sarkar, Arpita; Ramaiah, M Janaki; Chowdhury, Debabani Roy; Bhadra, Utpal; Pal-Bhadra, Manika

    2013-01-24

    In Drosophila embryos, checkpoints maintain genome stability by delaying cell cycle progression that allows time for damage repair or to complete DNA synthesis. Drosophila MOF, a member of MYST histone acetyl transferase is an essential component of male X hyperactivation process. Until recently its involvement in G2/M cell cycle arrest and defects in ionizing radiation induced DNA damage pathways was not well established. Drosophila MOF is highly expressed during early embryogenesis. In the present study we show that haplo-insufficiency of maternal MOF leads to spontaneous mitotic defects like mitotic asynchrony, mitotic catastrophe and chromatid bridges in the syncytial embryos. Such abnormal nuclei are eliminated and digested in the yolk tissues by nuclear fall out mechanism. MOF negatively regulates Drosophila checkpoint kinase 2 tumor suppressor homologue. In response to DNA damage the checkpoint gene Chk2 (Drosophila mnk) is activated in the mof mutants, there by causing centrosomal inactivation suggesting its role in response to genotoxic stress. A drastic decrease in the fall out nuclei in the syncytial embryos derived from mof¹/+; mnkp⁶/+ females further confirms the role of DNA damage response gene Chk2 to ensure the removal of abnormal nuclei from the embryonic precursor pool and maintain genome stability. The fact that mof mutants undergo DNA damage has been further elucidated by the increased number of single and double stranded DNA breaks. mof mutants exhibited genomic instability as evidenced by the occurance of frequent mitotic bridges in anaphase, asynchronous nuclear divisions, disruption of cytoskeleton, inactivation of centrosomes finally leading to DNA damage. Our findings are consistent to what has been reported earlier in mammals that; reduced levels of MOF resulted in increased genomic instability while total loss resulted in lethality. The study can be further extended using Drosophila as model system and carry out the interaction of MOF

  5. Genome stability in Caenorhabditis elegans

    NARCIS (Netherlands)

    Haaften, G.W. van

    2006-01-01

    Genome stability is closely linked to cancer. Most, if not all tumor cells show some form of genome instability, mutations can range from single point mutations to gross chromosomal rearrangements and aneuploidy. Genome instability is believed to be the driving force behind tumorigenesis. In order t

  6. Genome stability in Caenorhabditis elegans

    NARCIS (Netherlands)

    Haaften, G.W. van

    2006-01-01

    Genome stability is closely linked to cancer. Most, if not all tumor cells show some form of genome instability, mutations can range from single point mutations to gross chromosomal rearrangements and aneuploidy. Genome instability is believed to be the driving force behind tumorigenesis. In order t

  7. Autophagy plays a critical role in the degradation of active RHOA, the control of cell cytokinesis, and genomic stability.

    Science.gov (United States)

    Belaid, Amine; Cerezo, Michaël; Chargui, Abderrahman; Corcelle-Termeau, Elisabeth; Pedeutour, Florence; Giuliano, Sandy; Ilie, Marius; Rubera, Isabelle; Tauc, Michel; Barale, Sophie; Bertolotto, Corinne; Brest, Patrick; Vouret-Craviari, Valérie; Klionsky, Daniel J; Carle, Georges F; Hofman, Paul; Mograbi, Baharia

    2013-07-15

    Degradation of signaling proteins is one of the most powerful tumor-suppressive mechanisms by which a cell can control its own growth. Here, we identify RHOA as the molecular target by which autophagy maintains genomic stability. Specifically, inhibition of autophagosome degradation by the loss of the v-ATPase a3 (TCIRG1) subunit is sufficient to induce aneuploidy. Underlying this phenotype, active RHOA is sequestered via p62 (SQSTM1) within autolysosomes and fails to localize to the plasma membrane or to the spindle midbody. Conversely, inhibition of autophagosome formation by ATG5 shRNA dramatically increases localization of active RHOA at the midbody, followed by diffusion to the flanking zones. As a result, all of the approaches we examined that compromise autophagy (irrespective of the defect: autophagosome formation, sequestration, or degradation) drive cytokinesis failure, multinucleation, and aneuploidy, processes that directly have an impact upon cancer progression. Consistently, we report a positive correlation between autophagy defects and the higher expression of RHOA in human lung carcinoma. We therefore propose that autophagy may act, in part, as a safeguard mechanism that degrades and thereby maintains the appropriate level of active RHOA at the midbody for faithful completion of cytokinesis and genome inheritance.

  8. Stem Cells: The Pursuit of Genomic Stability

    Directory of Open Access Journals (Sweden)

    Saranya P. Wyles

    2014-11-01

    Full Text Available Stem cells harbor significant potential for regenerative medicine as well as basic and clinical translational research. Prior to harnessing their reparative nature for degenerative diseases, concerns regarding their genetic integrity and mutation acquisition need to be addressed. Here we review pluripotent and multipotent stem cell response to DNA damage including differences in DNA repair kinetics, specific repair pathways (homologous recombination vs. non-homologous end joining, and apoptotic sensitivity. We also describe DNA damage and repair strategies during reprogramming and discuss potential genotoxic agents that can reduce the inherent risk for teratoma formation and mutation accumulation. Ensuring genomic stability in stem cell lines is required to achieve the quality control standards for safe clinical application.

  9. Niacin requirements for genomic stability.

    Science.gov (United States)

    Kirkland, James B

    2012-05-01

    Through its involvement in over 400 NAD(P)-dependent reactions, niacin status has the potential to influence every area of metabolism. Niacin deficiency has been linked to genomic instability largely through impaired function of the poly ADP-ribose polymerase (PARP) family of enzymes. In various models, niacin deficiency has been found to cause impaired cell cycle arrest and apoptosis, delayed DNA excision repair, accumulation of single and double strand breaks, chromosomal breakage, telomere erosion and cancer development. Rat models suggest that most aspects of genomic instability are minimized by the recommended levels of niacin found in AIN-93 formulations; however, some beneficial responses do occur in the range from adequate up to pharmacological niacin intakes. Mouse models show a wide range of protection against UV-induced skin cancer well into pharmacological levels of niacin intake. It is currently a challenge to compare animal and human data to estimate the role of niacin status in the risk of genomic instability in human populations. It seems fairly certain that some portion of even affluent populations will benefit from niacin supplementation, and some subpopulations are likely well below an optimal intake of this vitamin. With exposure to stressors, like chemotherapy or excess sunlight, suraphysiological doses of niacin may be beneficial.

  10. COMMUNICATION: Alternative splicing and genomic stability

    Science.gov (United States)

    Cahill, Kevin

    2004-06-01

    Alternative splicing allows an organism to make different proteins in different cells at different times, all from the same gene. In a cell that uses alternative splicing, the total length of all the exons is much shorter than in a cell that encodes the same set of proteins without alternative splicing. This economical use of exons makes genes more stable during reproduction and development because a genome with a shorter exon length is more resistant to harmful mutations. Genomic stability may be the reason why higher vertebrates splice alternatively. For a broad class of alternatively spliced genes, a formula is given for the increase in their stability.

  11. MULTIPLE OSCILLATION STABILIZING CONTROL.

    Energy Technology Data Exchange (ETDEWEB)

    YUE,M.; SCHLUETER,R.; AZARM,M.; BARI,R.

    2004-07-23

    This paper presents a strategy that may be used to guide stabilizing control design for multiple oscillations, which are difficult to control using conventional control design procedures. A multiple oscillation phenomena is observed in an example power system. A local bifurcation and an interarea bifurcation develop in an example power system due to multiple bifurcation parameter variations. The dynamic behaviors of the bifurcating system are complex due to the overlapping of the two different bifurcation subsystems and are shown to be difficult to control. The double bifurcations are studied in this paper and in order to stabilize them, three kind of {mu}-synthesis robust controls are designed, (a) {mu}-synthesis power system stabilizer (MPSS); (b) {mu}-synthesis SVC control (MSVC); and (c) a mixed MPSS/MSVC control. Based on the bifurcation subsystem analysis, the measurement signals and locations of the controls are selected. The control performances of three kind of controls are evaluated and compared. The conclusions are given according to the analysis and time simulation results.

  12. Maintaining genome stability in the nervous system.

    Science.gov (United States)

    McKinnon, Peter J

    2013-11-01

    Active maintenance of genome stability is a prerequisite for the development and function of the nervous system. The high replication index during neurogenesis and the long life of mature neurons highlight the need for efficient cellular programs to safeguard genetic fidelity. Multiple DNA damage response pathways ensure that replication stress and other types of DNA lesions, such as oxidative damage, do not affect neural homeostasis. Numerous human neurologic syndromes result from defective DNA damage signaling and compromised genome integrity. These syndromes can involve different neuropathology, which highlights the diverse maintenance roles that are required for genome stability in the nervous system. Understanding how DNA damage signaling pathways promote neural development and preserve homeostasis is essential for understanding fundamental brain function.

  13. Iron and genome stability: An update

    Energy Technology Data Exchange (ETDEWEB)

    Pra, Daniel, E-mail: daniel_pra@yahoo.com [PPG em Promocao da Saude, Universidade de Santa Cruz do Sul (UNISC), Santa Cruz do Sul, RS (Brazil); PPG em Saude e Comportamento, Universidade Catolica de Pelotas, Pelotas, RS (Brazil); Franke, Silvia Isabel Rech [PPG em Promocao da Saude, Universidade de Santa Cruz do Sul (UNISC), Santa Cruz do Sul, RS (Brazil); Henriques, Joao Antonio Pegas [Instituto de Biotecnologia, Universidade de Caxias do Sul, Caxias do Sul, RS (Brazil); Fenech, Michael [CSIRO Food and Nutritional Sciences, Adelaide, SA (Australia)

    2012-05-01

    Iron is an essential micronutrient which is required in a relatively narrow range for maintaining metabolic homeostasis and genome stability. Iron participates in oxygen transport and mitochondrial respiration as well as in antioxidant and nucleic acid metabolism. Iron deficiency impairs these biological pathways, leading to oxidative stress and possibly carcinogenesis. Iron overload has been linked to genome instability as well as to cancer risk increase, as seen in hereditary hemochromatosis. Iron is an extremely reactive transition metal that can interact with hydrogen peroxide to generate hydroxyl radicals that form the 8-hydroxy-guanine adduct, cause point mutations as well as DNA single and double strand breaks. Iron overload also induces DNA hypermethylation and can reduce telomere length. The current Recommended Dietary Allowances (RDA) for iron, according with Institute of Medicine Dietary Reference Intake (DRI), is based in the concept of preventing anemia, and ranges from 7 mg/day to 18 mg/day depending on life stage and gender. Pregnant women need 27 mg/day. The maximum safety level for iron intake, the Upper Level (UL), is 40-45 mg/day, based on the prevention of gastrointestinal distress associated to high iron intakes. Preliminary evidence indicates that 20 mg/day iron, an intake slightly higher than the RDA, may reduce the risk of gastrointestinal cancer in the elderly as well as increasing genome stability in lymphocytes of children and adolescents. Current dietary recommendations do not consider the concept of genome stability which is of concern because damage to the genome has been linked to the origin and progression of many diseases and is the most fundamental pathology. Given the importance of iron for homeostasis and its potential influence over genome stability and cancer it is recommended to conduct further studies that conclusively define these relationships.

  14. High definition viral vaccine strain identity and stability testing using full-genome population data--The next generation of vaccine quality control.

    Science.gov (United States)

    Höper, Dirk; Freuling, Conrad M; Müller, Thomas; Hanke, Dennis; von Messling, Veronika; Duchow, Karin; Beer, Martin; Mettenleiter, Thomas C

    2015-10-26

    Vaccines are the most effective prophylactic public health tools. With the help of vaccines, prevention of infectious disease spread and, in concert with other measures, even eradication has become possible. Until now, licensing and quality control require the determination of consensus genome sequences of replication competent infectious agents contained in vaccines. Recent improvements in sequencing technologies now enable the sequencing of complete genomes and the genetic analysis of populations with high reliability and resolution. The latter is particularly important for RNA viruses, which consist of fluctuating heterogeneous populations rather than genetically stable entities. This information now has to be integrated into the existing regulatory framework, challenging both licensing authorities and vaccine producers to develop new quality control criteria. Commercially available modified-live oral rabies vaccines and their precursor strains were deep-sequenced to assess strain identity and relations between strains based on population diversity. Strain relations were inferred based on the Manhattan distances calculated between the compositions of the viral populations of the strains. We provide a novel approach to assess viral strain relations with high resolution and reliability by deep sequencing with subsequent analysis of the overall genetic diversity within the viral populations. A comparison of our novel approach of inferring strain relations based on population data with consensus sequence analysis clearly shows that consensus sequence analysis of diverse viral populations can be misleading. Therefore, for quality control of viral vaccines deep sequencing analysis is to be preferred over consensus sequence analysis. The presented methodology allows for routine integration of deep sequencing data in vaccine quality control and licensing for highly reliable assessment of strain identity and stability. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Menopause: Genome stability as new paradigm.

    Science.gov (United States)

    Laven, Joop S E; Visser, Jenny A; Uitterlinden, Andre G; Vermeij, Wilbert P; Hoeijmakers, Jan H J

    2016-10-01

    Menopause is defined as the age-dependent permanent cessation of menstruation and ovulation due to ovarian failure. Menopause occurs on average around the age of 51 years. Recent genome-wide association studies (GWAS) have identified over 44 genetic variants that are associated with age of onset of natural menopause. Genes linked with menopause can be classified into three major groups: genes implicated in genome stability (DNA repair), immune function and mitochondrial biogenesis. Biological and epidemiological data indicate that reproductive performance, age at menopause and longevity are interlinked through common genetic factors, which play a pivotal role in DNA repair and genome maintenance, which has been linked before with the process of ageing. Consequently, ageing of the soma as a result of inefficient DNA repair appears also to be responsible for failure to reproduce and the subsequent occurrence of menopause. In this way reproductive performance may be strongly linked to the physical condition of the soma and may be a very good predictor of general health in later life. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  16. Transient stability and emergency control

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Comparability of emergency control strategies with different instability modes is the key issue to decide which control strategy to be implemented. This paper considers that the essential factor causing instability should be used to form a unified standard to assess the effectiveness of control strategies with different instability modes. Thus a switching control stabilization principle was proposed based on elimination of the unbalanced energy between mechanical and electrical energies of generator sets. Along this way, the difficulty of seeking a Lyapunov function was circumvented. According to the principle, an emergency control algorithm framework was established to handle transient stability assessment, control location selection and control amount evaluation. Within the framework, this paper studied instability mode transition, then proposed an algorithm based on prediction function and a new approach to normalized stability margin stemmed from static EEAC method, which can increase comparability of various control locations. The simulations on the New-England System verified the proposed emergency control method for stabilizing transient stability.

  17. Electronic Stability Control

    Science.gov (United States)

    2013-12-05

    relationship between the steering wheel angle and lateral acceleration varies among vehicles because of differences in steering gear ratios, suspension...on-road, untripped truck rollovers by automatically decelerating the vehicle by applying the foundation brakes and reducing engine torque output...attributes: (1) Augments vehicle directional stability by applying and adjusting vehicle brake torques individually at each wheel position on at least

  18. Flotation control -- A multivariable stabilizer

    Energy Technology Data Exchange (ETDEWEB)

    Schubert, J.H.; Henning, R.G.D.; Hulbert, D.G.; Craig, I.K. [Mintek, Randburg (South Africa)

    1995-12-31

    This paper presents a stabilizing controller for flotation plants which uses a quasi-multivariable technique. The controller monitors all the levels in the plant, and by anticipating interactions between various parts of the plant, is able to stabilize the plant far more successfully than the normal plant control. Once stabilizing control has been achieved, optimization of the process becomes easier and more sustainable. An estimate of the improvement in metallurgical performance is made and a singular value analysis was conducted to verify that the multivariable algorithm will theoretically control better than a collection of individual PID loops. Metallurgical results are presented to show that the improvements are attainable in practice. Control by the Mintek algorithm was alternated with normal plant control, to show that the improvements are statistically significant.

  19. Transient stability and emergency control

    Institute of Scientific and Technical Information of China (English)

    ZHANG XueMin; MEI ShengWei; WU ShengYu

    2009-01-01

    Comparability of emergency control strategies with different instability modes is the key issue to de-cide which control strategy to be implemented. This paper considers that the essential factor causing instability should be used to form a unified standard to assess the effectiveness of control strategies with different instability modes. Thus a switching control stabilization principle was proposed based on elimination of the unbalanced energy between mechanical and electrical energies of generator sets. Along this way, the difficulty of seeking a Lyapunov function was circumvented. According to the prin-ciple, an emergency control algorithm framework was established to handle transient stability as-sessment, control location selection and control amount evaluation. Within the framework, this paper studied instability mode transition, then proposed an algorithm based on prediction function and a new approach to normalized stability margin stemmed from static EEAC method, which can increase com-parability of various control locations. The simulations on the New-England System verified the pro-posed emergency control method for stabilizing transient stability.

  20. Causal Factors in Genome Control

    NARCIS (Netherlands)

    O'Duibhir, E.

    2015-01-01

    The aim of this thesis is to study how genes are switched on and off in a coordinated way across an entire genome. In order to do this yeast is used as a model organism. The mechanisms that control gene expression in yeast are very similar to those of human cells. Chapter 1 provides a general introd

  1. ATM signaling and genomic stability in response to DNA damage

    Energy Technology Data Exchange (ETDEWEB)

    Lavin, Martin F. [Queensland Cancer Fund Research Unit, Queensland Institute of Medical Research, PO Box Royal Brisbane Hospital, Herston, Brisbane 4029 (Australia) and Central Clinical Division, University of Queensland, Brisbane (Australia)]. E-mail: martinl@qimr.edu.au; Birrell, Geoff [Queensland Cancer Fund Research Unit, Queensland Institute of Medical Research, PO Box Royal Brisbane Hospital, Herston, Brisbane 4029 (Australia); Chen, Philip [Queensland Cancer Fund Research Unit, Queensland Institute of Medical Research, PO Box Royal Brisbane Hospital, Herston, Brisbane 4029 (Australia); Kozlov, Sergei [Queensland Cancer Fund Research Unit, Queensland Institute of Medical Research, PO Box Royal Brisbane Hospital, Herston, Brisbane 4029 (Australia); Scott, Shaun [Queensland Cancer Fund Research Unit, Queensland Institute of Medical Research, PO Box Royal Brisbane Hospital, Herston, Brisbane 4029 (Australia); Gueven, Nuri [Queensland Cancer Fund Research Unit, Queensland Institute of Medical Research, PO Box Royal Brisbane Hospital, Herston, Brisbane 4029 (Australia)

    2005-01-06

    DNA double strand breaks represent the most threatening lesion to the integrity of the genome in cells exposed to ionizing radiation and radiomimetic chemicals. Those breaks are recognized, signaled to cell cycle checkpoints and repaired by protein complexes. The product of the gene (ATM) mutated in the human genetic disorder ataxia-telangiectasia (A-T) plays a central role in the recognition and signaling of DNA damage. ATM is one of an ever growing number of proteins which when mutated compromise the stability of the genome and predispose to tumour development. Mechanisms for recognising double strand breaks in DNA, maintaining genome stability and minimizing risk of cancer are discussed.

  2. Ancient hybridization and genomic stabilization in a swordtail fish.

    Science.gov (United States)

    Schumer, Molly; Cui, Rongfeng; Powell, Daniel L; Rosenthal, Gil G; Andolfatto, Peter

    2016-06-01

    A rapidly increasing body of work is revealing that the genomes of distinct species often exhibit hybrid ancestry, presumably due to postspeciation hybridization between closely related species. Despite the growing number of documented cases, we still know relatively little about how genomes evolve and stabilize following hybridization, and to what extent hybridization is functionally relevant. Here, we examine the case of Xiphophorus nezahualcoyotl, a teleost fish whose genome exhibits significant hybrid ancestry. We show that hybridization was relatively ancient and is unlikely to be ongoing. Strikingly, the genome of X. nezahualcoyotl has largely stabilized following hybridization, distinguishing it from examples such as human-Neanderthal hybridization. Hybridization-derived regions are remarkably distinct from other regions of the genome, tending to be enriched in genomic regions with reduced constraint. These results suggest that selection has played a role in removing hybrid ancestry from certain functionally important regions. Combined with findings in other systems, our results raise many questions about the process of genomic stabilization and the role of selection in shaping patterns of hybrid ancestry in the genome. © 2016 John Wiley & Sons Ltd.

  3. Genome Stability Pathways in Head and Neck Cancers

    Directory of Open Access Journals (Sweden)

    Glenn Jenkins

    2013-01-01

    Full Text Available Genomic instability underlies the transformation of host cells toward malignancy, promotes development of invasion and metastasis and shapes the response of established cancer to treatment. In this review, we discuss recent advances in our understanding of genomic stability in squamous cell carcinoma of the head and neck (HNSCC, with an emphasis on DNA repair pathways. HNSCC is characterized by distinct profiles in genome stability between similarly staged cancers that are reflected in risk, treatment response and outcomes. Defective DNA repair generates chromosomal derangement that can cause subsequent alterations in gene expression, and is a hallmark of progression toward carcinoma. Variable functionality of an increasing spectrum of repair gene polymorphisms is associated with increased cancer risk, while aetiological factors such as human papillomavirus, tobacco and alcohol induce significantly different behaviour in induced malignancy, underpinned by differences in genomic stability. Targeted inhibition of signalling receptors has proven to be a clinically-validated therapy, and protein expression of other DNA repair and signalling molecules associated with cancer behaviour could potentially provide a more refined clinical model for prognosis and treatment prediction. Development and expansion of current genomic stability models is furthering our understanding of HNSCC pathophysiology and uncovering new, promising treatment strategies.

  4. Break-Induced Replication and Genome Stability

    Directory of Open Access Journals (Sweden)

    Anna Malkova

    2012-10-01

    Full Text Available Genetic instabilities, including mutations and chromosomal rearrangements, lead to cancer and other diseases in humans and play an important role in evolution. A frequent cause of genetic instabilities is double-strand DNA breaks (DSBs, which may arise from a wide range of exogeneous and endogeneous cellular factors. Although the repair of DSBs is required, some repair pathways are dangerous because they may destabilize the genome. One such pathway, break-induced replication (BIR, is the mechanism for repairing DSBs that possesses only one repairable end. This situation commonly arises as a result of eroded telomeres or collapsed replication forks. Although BIR plays a positive role in repairing DSBs, it can alternatively be a dangerous source of several types of genetic instabilities, including loss of heterozygosity, telomere maintenance in the absence of telomerase, and non-reciprocal translocations. Also, mutation rates in BIR are about 1000 times higher as compared to normal DNA replication. In addition, micro-homology-mediated BIR (MMBIR, which is a mechanism related to BIR, can generate copy-number variations (CNVs as well as various complex chromosomal rearrangements. Overall, activation of BIR may contribute to genomic destabilization resulting in substantial biological consequences including those affecting human health.

  5. Arms Control and Strategic Stability

    Institute of Scientific and Technical Information of China (English)

    Hu; Yumin

    2014-01-01

    This essay intends to offer a comment on concepts, trends and attitudes concerning arms control and strategic stability with reference to the current international security situation. It also offers observations from two different perspectives about strategic stability: one proceeds from the concept of universal security and aims to prevent conflicts and instability from disrupting regional and international security environment on which nation states depend so much for their peaceful development; the other starts from maintaining the global leadership by a super power and aiming to contain any challenge that sways or is likely to sway its dominating status. If China and the United States commit themselves to the undertaking of a new type of major powers relationship that stresses win-win cooperation, they will be able to contribute greatly to a stable international security architecture that is good for world peaceful development.

  6. Genetic stability of pestivirus genomes cloned into BACs

    DEFF Research Database (Denmark)

    Rasmussen, Thomas Bruun; Reimann, Ilona; Uttenthal, Åse;

    chromosome (BAC) vector “pBeloBAC11”. This BAC vector provides a markedly higher stability of cloned sequences in E. coli compared to plasmids that form the basis for the existing pestivirus cDNA clones. In this study, two of the newly constructed BAC clones were analysed for genetic stability of the cloned...... pestivirus genomes to demonstrate the suitability of the BAC vector for harbouring pestivirus genomes. Two BAC clones, comprising the complete genomes of BDV Gifhorn (pBeloGif3) and CSFV Paderborn (pBeloPader10) were passaged 15 times in E.coli representing at least 360 bacteria generations. From 15th...... passage of the BAC clones, the entire 5’ and 3’ ends of the cloned genomes and parts of the open reading frame were sequenced and compared to the sequences of the parent BAC clones. The sequenced areas represent approximately 20 % of the cloned genome. No mutations were observed after the extensive...

  7. Proteotoxic stress in human genome stability

    OpenAIRE

    Santana, Inês Manuela do Vale

    2013-01-01

    Incorporation of errors during protein synthesis is denominated mistranslation. This compromises the acquisition of a correct final three dimensional structure and consequently the accumulation in the cell of proteins with abnormal conformations. Cells have protein quality control (PQC) mechanisms to counteract the accumulation of aberrant proteins, but when these systems are overloaded proteins aggregate, generating proteotoxic stress. Mistranslation is associated with several diseases and w...

  8. Genome-Wide Analysis of Human MicroRNA Stability

    Directory of Open Access Journals (Sweden)

    Yang Li

    2013-01-01

    Full Text Available Increasing studies have shown that microRNA (miRNA stability plays important roles in physiology. However, the global picture of miRNA stability remains largely unknown. Here, we had analyzed genome-wide miRNA stability across 10 diverse cell types using miRNA arrays. We found that miRNA stability shows high dynamics and diversity both within individual cells and across cell types. Strikingly, we observed a negative correlation between miRNA stability and miRNA expression level, which is different from current findings on other biological molecules such as proteins and mRNAs that show positive and not negative correlations between stability and expression level. This finding indicates that miRNA has a distinct action mode, which we called “rapid production, rapid turnover; slow production, slow turnover.” This mode further suggests that high expression miRNAs normally degrade fast and may endow the cell with special properties that facilitate cellular status-transition. Moreover, we revealed that the stability of miRNAs is affected by cohorts of factors that include miRNA targets, transcription factors, nucleotide content, evolution, associated disease, and environmental factors. Together, our results provided an extensive description of the global landscape, dynamics, and distinct mode of human miRNA stability, which provide help in investigating their functions in physiology and pathophysiology.

  9. Aspects of ribonucleotide reductase regulation and genome stability

    DEFF Research Database (Denmark)

    Nielsen, Helena Berner Nedergaard

    yeast, and Sml1, Hug1, and Dif1 in budding yeast. An elevated, as well as a reduced dNTP pool is shown to lead to an increase in spontaneous mutation rates, hence regulation of RNR is very important in order to maintain genomic stability. No human inhibitory proteins have yet been identified to regulate......In all living cells, synthesis of the DNA building blocks, deoxyribonucleoside triphosphates (dNTPs), is tightly regulated to ensure a precise DNA replication to maintain genomic stability. Ribonucleotide reductase (RNR) is the enzyme responsible for reducing ribonucleotides to their deoxy forms...... the human RNR enzyme. In this study regulation of human RNR was investigated using a fission yeast strain that depended solely on the human genes of R1 and R2 for dNTP synthesis. Even though this strain could grow like wild-type fission yeast it was hypersensitive to hydroxyurea (HU) and depended...

  10. Power System Security and Stability Control Company

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Branch Company Profile Power System Security and Stability Control Company is called "NARI Stability" to externals. It has a scientific research team, led by Prof. Yusheng Xue, who is an international renowned expert on stability technology, and an academician of the Chinese Academy of Engineering. Based on support and service of security and stability control technology and equipment,

  11. Stochastic stabilization analysis of networked control systems

    Institute of Scientific and Technical Information of China (English)

    Ma Changlin; Fang Huajing

    2007-01-01

    Considering the stochastic delay problems existing in networked control systems, a new control mode is proposed for networked control systems whose delay is longer than a sampling period. Under the control mode, the mathematical model of such a system is established. A stochastic stabilization condition for the system is given. The maximum delay can be derived from the stabilization condition.

  12. Practical stabilization of receding-horizon control

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The purpose of this work is to propose a scheme to stabilize the predictive control systems in the practical stability serse. In the paper, the authors dealt with a general discrete predictive control system xj = f( xj\\t, uj\\t) by using the Lyapunov direct method combining with receding-horizon control technique,and presented a new condition to guarantee the practical stabilization of the systems. With the proposed results, one can design the optimal controllers easily to practically stabilize the predictive control systems.

  13. The genomics of disulfide bonding and protein stabilization in thermophiles.

    Directory of Open Access Journals (Sweden)

    2005-09-01

    Full Text Available Thermophilic organisms flourish in varied high-temperature environmental niches that are deadly to other organisms. Recently, genomic evidence has implicated a critical role for disulfide bonds in the structural stabilization of intracellular proteins from certain of these organisms, contrary to the conventional view that structural disulfide bonds are exclusively extracellular. Here both computational and structural data are presented to explore the occurrence of disulfide bonds as a protein-stabilization method across many thermophilic prokaryotes. Based on computational studies, disulfide-bond richness is found to be widespread, with thermophiles containing the highest levels. Interestingly, only a distinct subset of thermophiles exhibit this property. A computational search for proteins matching this target phylogenetic profile singles out a specific protein, known as protein disulfide oxidoreductase, as a potential key player in thermophilic intracellular disulfide-bond formation. Finally, biochemical support in the form of a new crystal structure of a thermophilic protein with three disulfide bonds is presented together with a survey of known structures from the literature. Together, the results provide insight into biochemical specialization and the diversity of methods employed by organisms to stabilize their proteins in exotic environments. The findings also motivate continued efforts to sequence genomes from divergent organisms.

  14. Holliday junction processing enzymes as guardians of genome stability.

    Science.gov (United States)

    Sarbajna, Shriparna; West, Stephen C

    2014-09-01

    Holliday junctions (HJs) are four-stranded DNA intermediates that arise during the recombinational repair of DNA double-strand breaks (DSBs). Their timely removal is crucial for faithful chromosome segregation and genome stability. In mammalian cells, HJs are processed by the BTR (BLM-topoisomerase IIIα-RMI1-RMI2) complex, the SLX-MUS (SLX1-SLX4-MUS81-EME1) complex, and the GEN1 resolvase. Recent studies have linked the deficiency of one or more of these enzymes to perturbed DNA replication, impaired crosslink repair, chromosomal instability, and defective mitoses, coupled with the transmission of widespread DNA damage and high levels of mortality. We review these key advances and how they have cemented the status of HJ-processing enzymes as guardians of genome integrity and viability in mammalian cells. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Epigenetic regulation of ageing: linking environmental inputs to genomic stability

    Science.gov (United States)

    Benayoun, Bérénice A.; Pollina, Elizabeth A.; Brunet, Anne

    2016-01-01

    Preface Ageing is affected by both genetic and non-genetic factors. Here, we review the chromatin-based epigenetic changes that occur during ageing, the role of chromatin modifiers in modulating lifespan and the importance of epigenetic signatures as biomarkers of ageing. We also discuss how epigenome remodeling by environmental stimuli impacts several aspects of transcription and genomic stability, with important consequences on longevity, and outline epigenetic differences between the ‘mortal soma’ and the ‘immortal germline’. Finally, we discuss the inheritance of ageing characteristics and potential chromatin-based strategies to delay or reverse hallmarks of ageing or age-related diseases. PMID:26373265

  16. Maintenance of genome stability in plants: repairing DNA double strand breaks and chromatin structure stability

    Directory of Open Access Journals (Sweden)

    Sujit eRoy

    2014-09-01

    Full Text Available Plant cells are subject to high levels of DNA damage resulting from plant’s obligatory dependence on sunlight and the associated exposure to environmental stresses like solar UV radiation, high soil salinity, drought, chilling injury and other air and soil pollutants including heavy metals and metabolic byproducts from endogenous processes. The irreversible DNA damages, generated by the environmental and genotoxic stresses affect plant growth and development, reproduction and crop productivity. Thus, for maintaining genome stability, plants have developed an extensive array of mechanisms for the detection and repair of DNA damages. This review will focus recent advances in our understanding of mechanisms regulating plant genome stability in the context of repairing of double stand breaks and chromatin structure maintenance.

  17. MATLAB Stability and Control Toolbox Trim and Static Stability Module

    Science.gov (United States)

    Kenny, Sean P.; Crespo, Luis

    2012-01-01

    MATLAB Stability and Control Toolbox (MASCOT) utilizes geometric, aerodynamic, and inertial inputs to calculate air vehicle stability in a variety of critical flight conditions. The code is based on fundamental, non-linear equations of motion and is able to translate results into a qualitative, graphical scale useful to the non-expert. MASCOT was created to provide the conceptual aircraft designer accurate predictions of air vehicle stability and control characteristics. The code takes as input mass property data in the form of an inertia tensor, aerodynamic loading data, and propulsion (i.e. thrust) loading data. Using fundamental nonlinear equations of motion, MASCOT then calculates vehicle trim and static stability data for the desired flight condition(s). Available flight conditions include six horizontal and six landing rotation conditions with varying options for engine out, crosswind, and sideslip, plus three take-off rotation conditions. Results are displayed through a unique graphical interface developed to provide the non-stability and control expert conceptual design engineer a qualitative scale indicating whether the vehicle has acceptable, marginal, or unacceptable static stability characteristics. If desired, the user can also examine the detailed, quantitative results.

  18. Matlab Stability and Control Toolbox: Trim and Static Stability Module

    Science.gov (United States)

    Crespo, Luis G.; Kenny, Sean P.

    2006-01-01

    This paper presents the technical background of the Trim and Static module of the Matlab Stability and Control Toolbox. This module performs a low-fidelity stability and control assessment of an aircraft model for a set of flight critical conditions. This is attained by determining if the control authority available for trim is sufficient and if the static stability characteristics are adequate. These conditions can be selected from a prescribed set or can be specified to meet particular requirements. The prescribed set of conditions includes horizontal flight, take-off rotation, landing flare, steady roll, steady turn and pull-up/ push-over flight, for which several operating conditions can be specified. A mathematical model was developed allowing for six-dimensional trim, adjustable inertial properties, asymmetric vehicle layouts, arbitrary number of engines, multi-axial thrust vectoring, engine(s)-out conditions, crosswind and gyroscopic effects.

  19. Hybrid Intelligent Control for Submarine Stabilization

    Directory of Open Access Journals (Sweden)

    Minghui Wang

    2013-05-01

    Full Text Available While sailing near the sea surface, submarines will often undergo rolling motion caused by wave disturbance. Fierce rolling motion seriously affects their normal operation and even threatens their security. We propose a new control method for roll stabilization. This paper studies hybrid intelligent control combining a fuzzy control, a neural network and extension control technology. Every control strategy can achieve the ideal control effect within the scope of its effective control. The neuro‐fuzzy control strategy is used to improve the robustness of the controller. The speed control strategy and the course control strategy are conducted to extend the control range. The paper also proposes the design of the controller and carries out the simulation experiment in different sea conditions. The simulation results show that the control method proposed can indeed effectively improve the control performance of submarine stabilization.

  20. Hybrid Intelligent Control for Submarine Stabilization

    Directory of Open Access Journals (Sweden)

    Minghui Wang

    2013-05-01

    Full Text Available Abstract While sailing near the sea surface, submarines will often undergo rolling motion caused by wave disturbance. Fierce rolling motion seriously affects their normal operation and even threatens their security. We propose a new control method for roll stabilization. This paper studies hybrid intelligent control combining a fuzzy control, a neural network and extension control technology. Every control strategy can achieve the ideal control effect within the scope of its effective control. The neuro-fuzzy control strategy is used to improve the robustness of the controller. The speed control strategy and the course control strategy are conducted to extend the control range. The paper also proposes the design of the controller and carries out the simulation experiment in different sea conditions. The simulation results show that the control method proposed can indeed effectively improve the control performance of submarine stabilization.

  1. Parasitic nematodes - from genomes to control.

    Science.gov (United States)

    Mitreva, Makedonka; Zarlenga, Dante S; McCarter, James P; Jasmer, Douglas P

    2007-08-19

    The diseases caused by parasitic nematodes in domestic and companion animals are major factors that decrease production and quality of the agricultural products. Methods available for the control of the parasitic nematode infections are mainly based on chemical treatment, non-chemical management practices, immune modulation and biological control. However, even with integrated pest management that frequently combines these approaches, the effective and long-lasting control strategies are hampered by the persistent exposure of host animals to environmental stages of parasites, the incomplete protective response of the host and acquisition of anthelmintic resistance by an increasing number of parasitic nematodes. Therefore, the challenges to improve control of parasitic nematode infections are multi-fold and no single category of information will meet them all. However, new information, such as nematode genomics, functional genomics and proteomics, can strengthen basic and applied biological research aimed to develop improvements. In this review we will, summarize existing control strategies of nematode infections and discuss ongoing developments in nematode genomics. Genomics approaches offer a growing and fundamental base of information, which when coupled with downstream functional genomics and proteomics can accelerate progress towards developing more efficient and sustainable control programs.

  2. Can electronic stability control replace studded tyres?

    Science.gov (United States)

    Elvik, Rune

    2015-12-01

    Based on recent studies, this paper examines whether an increased use of electronic stability control can replace studded tyres. A re-analysis of a study that evaluated the effects on accidents of changes in the use of studded tyres in major cities in Norway is presented. It is found that if all cars have electronic stability control, the use of studded tyres can be reduced to about 15 percent before any increase in the number of accidents occurs. Even if studded tyres were eliminated entirely, any increase in the number of accidents is likely to be considerably smaller than it would have been if electronic stability control had never been invented.

  3. Power system stability modelling, analysis and control

    CERN Document Server

    Sallam, Abdelhay A

    2015-01-01

    This book provides a comprehensive treatment of the subject from both a physical and mathematical perspective and covers a range of topics including modelling, computation of load flow in the transmission grid, stability analysis under both steady-state and disturbed conditions, and appropriate controls to enhance stability.

  4. Cooperativity of the SUMO and Ubiquitin Pathways in Genome Stability

    Directory of Open Access Journals (Sweden)

    Minghua Nie

    2016-02-01

    Full Text Available Covalent attachment of ubiquitin (Ub or SUMO to DNA repair proteins plays critical roles in maintaining genome stability. These structurally related polypeptides can be viewed as distinct road signs, with each being read by specific protein interaction motifs. Therefore, via their interactions with selective readers in the proteome, ubiquitin and SUMO can elicit distinct cellular responses, such as directing DNA lesions into different repair pathways. On the other hand, through the action of the SUMO-targeted ubiquitin ligase (STUbL family proteins, ubiquitin and SUMO can cooperate in the form of a hybrid signal. These mixed SUMO-ubiquitin chains recruit “effector” proteins such as the AAA+ ATPase Cdc48/p97-Ufd1-Npl4 complex that contain both ubiquitin and SUMO interaction motifs. This review will summarize recent key findings on collaborative and distinct roles that ubiquitin and SUMO play in orchestrating DNA damage responses.

  5. Stability analysis of generalized predictive control based on Kleinman's controllers

    Institute of Scientific and Technical Information of China (English)

    DING Baocang; XI Yugeng

    2004-01-01

    With Kleinman's controller, its extended form and Riccati iteration as analyzing tools, the stability of GPC under various parameter cases is discussed. The overall closed-loop stability conclusions of GPC in equivalence with Kleinman's controller are obtained, which cover some existing results and provide the theoretical foundation for stable design of predictive control.

  6. CRISPR/Cas9-based genome editing for simultaneous interference with gene expression and protein stability

    DEFF Research Database (Denmark)

    Martinez, Virginia; Lauritsen, Ida; Hobel, Tonja

    2017-01-01

    Interference with genes is the foundation of reverse genetics and is key to manipulation of living cells for biomedical and biotechnological applications. However, classical genetic knockout and transcriptional knockdown technologies have different drawbacks and offer no control over existing...... protein levels. Here, we describe an efficient genome editing approach that affects specific protein abundances by changing the rates of both RNA synthesis and protein degradation, based on the two cross-kingdom control mechanisms CRISPRi and the N-end rule for protein stability. In addition, our approach...

  7. Can electronic stability control replace studded tyres?

    DEFF Research Database (Denmark)

    Elvik, Rune

    2015-01-01

    Highlights • Electronic stability control can substitute studded tyres. • This makes it easier to discourage the use of studded tyres. • A certain level of use of studded tyres makes roads less slippery.......Highlights • Electronic stability control can substitute studded tyres. • This makes it easier to discourage the use of studded tyres. • A certain level of use of studded tyres makes roads less slippery....

  8. Directional and Attitude Stability Control Kit

    Science.gov (United States)

    2014-07-01

    and Attitude Stability Control Kit Final Progress Report This report outlines progress on the DARPA M3 Program, project “Directional and Attitude ...2 ABSTRACT Number of Papers published in peer-reviewed journals: Number of Papers published in non peer-reviewed journals: Directional and Attitude ...Stability Control Kit Final Progress Report Report Title This report outlines progress on the DARPA M3 Program, project “Directional and Attitude

  9. Stability Constraints for Robust Model Predictive Control

    Directory of Open Access Journals (Sweden)

    Amanda G. S. Ottoni

    2015-01-01

    Full Text Available This paper proposes an approach for the robust stabilization of systems controlled by MPC strategies. Uncertain SISO linear systems with box-bounded parametric uncertainties are considered. The proposed approach delivers some constraints on the control inputs which impose sufficient conditions for the convergence of the system output. These stability constraints can be included in the set of constraints dealt with by existing MPC design strategies, in this way leading to the “robustification” of the MPC.

  10. Stabilized Feedback Control of Unicycle Mobile Robots

    Directory of Open Access Journals (Sweden)

    Khoukhi Amar

    2013-04-01

    Full Text Available In this paper, a stabilized feedback control is designed for a class of unicycle non‐holonomic mobile robots. The approach is based on kinematic polar coordinate transformations. The suggested control scheme allows the robot to achieve stabilized near‐ optimal trajectories, while satisfying the hard constraints of specified initial and final postures (positions and orientations. Simulation experiments showing the effectiveness of the proposed technique are provided and discussed.

  11. Stability and Control of Functional Differential Equations

    CERN Document Server

    Peet, M M

    2006-01-01

    This thesis addresses the question of stability of systems defined by differential equations which contain nonlinearity and delay. In particular, we analyze the stability of a well-known delayed nonlinear implementation of a certain Internet congestion control protocol. We also describe a generalized methodology for proving stability of time-delay systems through the use of semidefinite programming. In Chapters 4 and 5, we consider an Internet congestion control protocol based on the decentralized gradient projection algorithm. For a certain class of utility function, this algorithm was shown to be globally convergent for some sufficiently small value of a gain parameter. Later work gave an explicit bound on this gain for a linearized version of the system. This thesis proves that this bound also implies stability of the original system. In Chapter 7, we describe a general methodology for proving stability of linear time-delay systems by computing solutions to an operator-theoretic version of the Lyapunov ine...

  12. The design of image stabilization control system

    Science.gov (United States)

    Lin, Zhe; Wu, Chunnan; Yu, Fei; Kang, Xiaojun

    2012-09-01

    For high resolution satellite remote sensing cameras, the line of sight (LOS) moving during the image exposure period will cause the modulation transfer function (MTF) degradation and image blurring. Image stabilization component is used to improve image quality by actively removing the apparent motion induced by vibration, tracking error and attitude instability. In this paper, the image stabilization component is considered as a kind of closed loop servo control system, and the image stabilization effect is converted into servo control performance for research. Firstly, the image stabilization servo loop scheme and transfer function model are constructed and the LOS jitter is considered as the output of a stochastic system derived by white-Gaussian noise. Based on the proposed model, the demand boundary of jitter rejection function is described, and the design criterion to be satisfied is obtained according to the requirement of image stabilization performance. And then, a discrete Kalman estimation algorithm is introduced into image stabilization servo loop to filter out the noise caused by pixel-shift sensor (PSS) and compensate for the delay due to the PSS measurement. Based on the given design criterion, the control law is designed by using the output of Kalman filter. The computer simulation is achieved to show that the proposed control strategy can significantly improve the image stabilization performance.

  13. OPTIMAL CONTROL FOR ELECTRIC VEHICLE STABILIZATION

    Directory of Open Access Journals (Sweden)

    MARIAN GAICEANU

    2016-01-01

    Full Text Available This main objective of the paper is to stabilize an electric vehicle in optimal manner to a step lane change maneuver. To define the mathematical model of the vehicle, the rigid body moving on a plane is taken into account. An optimal lane keeping controller delivers the adequate angles in order to stabilize the vehicle’s trajectory in an optimal way. Two degree of freedom linear bicycle model is adopted as vehicle model, consisting of lateral and yaw motion equations. The proposed control maintains the lateral stability by taking the feedback information from the vehicle transducers. In this way only the lateral vehicle’s dynamics are enough to considerate. Based on the obtained linear mathematical model the quadratic optimal control is designed in order to maintain the lateral stability of the electric vehicle. The numerical simulation results demonstrate the feasibility of the proposed solution.

  14. Epigenetic control of mobile DNA as an interface between experience and genome change

    Directory of Open Access Journals (Sweden)

    James A. Shapiro

    2014-04-01

    Full Text Available Mobile DNA in the genome is subject to RNA-targeted epigenetic control. This control regulates the activity of transposons, retrotransposons and genomic proviruses. Many different life history experiences alter the activities of mobile DNA and the expression of genetic loci regulated by nearby insertions. The same experiences induce alterations in epigenetic formatting and lead to trans-generational modifications of genome expression and stability. These observations lead to the hypothesis that epigenetic formatting directed by non-coding RNA provides a molecular interface between life history events and genome alteration.

  15. Stability analysis of automobile driver steering control

    Science.gov (United States)

    Allen, R. W.

    1981-01-01

    In steering an automobile, the driver must basically control the direction of the car's trajectory (heading angle) and the lateral deviation of the car relative to a delineated pathway. A previously published linear control model of driver steering behavior which is analyzed from a stability point of view is considered. A simple approximate expression for a stability parameter, phase margin, is derived in terms of various driver and vehicle control parameters, and boundaries for stability are discussed. A field test study is reviewed that includes the measurement of driver steering control parameters. Phase margins derived for a range of vehicle characteristics are found to be generally consistent with known adaptive properties of the human operator. The implications of these results are discussed in terms of driver adaptive behavior.

  16. Plants from Chernobyl zone could shed light on genome stability in radioactive environment

    Science.gov (United States)

    Shevchenko, Galina; Talalaiev, Oleksandr; Doonan, John

    2016-07-01

    For nearly 30 years, despite of chronic radiation, flora in Chernobyl zone continue to flourish, evidencing the adaptation of plants to such an environment. Keeping in mind interplanetary missions, this phenomenon is a challenge for plant space research since it highlights the possible mechanisms of genome protection and stabilization in harmful environment. Plants are sessile organisms and, contrary to animals, could not escape the external impact. Therefore, plants should evolve the robust system allowing DNA-protection against damage, which is of special interest. Our investigations show that Arabidopsis thaliana from Chernobyl zone tolerate radiomimetics and heavy metals better than control plants from non-polluted areas. Besides, its genome is less affected by such mutagens. qPCR investigations have revealed up-regulation of some genes involved in DNA damage response. In particular, expression of ATR is increased slightly and downstream expression of CycB1:1 gene is increased significantly after bleomycin treatment suggesting role of ATR-dependent pathway in genome stabilization. Several DNA repair pathways are known to exist in plants. We continue investigations on gene expression from different DNA repair pathways as well as cell cycle regulation and investigation of PCD hallmarks in order to reveal the mechanism of plant tolerance to radiation environment. Our investigations provide unique information for space researchers working on biotechnology of radiation tolerant plants.

  17. Controllability, Observability, and Stability of Mathematical Models

    OpenAIRE

    Iggidr, Abderrahman

    2004-01-01

    International audience; This article presents an overview of three fundamental concepts in Mathematical System Theory: controllability, stability and observability. These properties play a prominent role in the study of mathematical models and in the understanding of their behavior. They constitute the main research subject in Control Theory. Historically the tools and techniques of Automatic Control have been developed for artificial engineering systems but nowadays they are more and more ap...

  18. Finite-time stability and control

    CERN Document Server

    Amato, Francesco; Ariola, Marco; Cosentino, Carlo; De Tommasi, Gianmaria

    2014-01-01

    Finite-time stability (FTS) is a more practical concept than classical Lyapunov stability, useful for checking whether the state trajectories of a system remain within pre-specified bounds over a finite time interval. In a linear systems framework, FTS problems can be cast as convex optimization problems and solved by the use of effective off-the-shelf computational tools such as LMI solvers. Finite-time Stability and Control exploits this benefit to present the practical applications of FTS and finite-time control-theoretical results to various engineering fields. The text is divided into two parts: ·         linear systems; and ·         hybrid systems. The building of practical motivating examples helps the reader to understand the methods presented. Finite-time Stability and Control is addressed to academic researchers and to engineers working in the field of robust process control. Instructors teaching graduate courses in advanced control will also find parts of this book useful for the...

  19. Stabilizing chaotic-scattering trajectories using control

    Science.gov (United States)

    Lai, Ying-Cheng; Tél, Tamás; Grebogi, Celso

    1993-08-01

    The method of stabilizing unstable periodic orbits in chaotic dynamical systems by Ott, Grebogi, and Yorke (OGY) is applied to control chaotic scattering in Hamiltonian systems. In particular, we consider the case of nonhyperbolic chaotic scattering, where there exist Kolmogorov-Arnold-Moser (KAM) surfaces in the scattering region. It is found that for short unstable periodic orbits not close to the KAM surfaces, both the probability that a particle can be controlled and the average time to achieve control are determined by the initial exponential decay rate of particles in the hyperbolic component. For periodic orbits near the KAM surfaces, due to the stickiness effect of the KAM surfaces on particle trajectories, the average time to achieve control can greatly exceed that determined by the hyperbolic component. The applicability of the OGY method to stabilize intermediate complexes of classical scattering systems is suggested.

  20. Selenium and its' role in the maintenance of genomic stability.

    Science.gov (United States)

    Ferguson, Lynnette R; Karunasinghe, Nishi; Zhu, Shuotun; Wang, Alice H

    2012-05-01

    Selenium (Se) is an essential micronutrient for humans, acting as a component of the unusual amino acids, selenocysteine (Se-Cys) and selenomethionine (Se-Met). Where Se levels are low, the cell cannot synthesise selenoproteins, although some selenoproteins and some tissues are prioritised over others. Characterised functions of known selenoproteins, include selenium transport (selenoprotein P), antioxidant/redox properties (glutathione peroxidases (GPxs), thioredoxin reductases and selenoprotein P) and anti-inflammatory properties (selenoprotein S and GPx4). Various forms of Se are consumed as part of a normal diet, or as a dietary supplement. Supplementation of tissue culture media, animal or human diets with moderate levels of certain Se compounds may protect against the formation of DNA adducts, DNA or chromosome breakage, and chromosome gain or loss. Protective effects have also been shown on mitochondrial DNA, and on telomere length and function. Some of the effects of Se compounds on gene expression may relate to modulation of DNA methylation or inhibition of histone deacetylation. Despite a large number of positive effects of selenium and selenoproteins in various model systems, there have now been some human clinical trials that have shown adverse effects of Se supplementation, according to various endpoints. Too much Se is as harmful as too little, with animal models showing a "U"-shaped efficacy curve. Current recommended daily allowances differ among countries, but are generally based on the amount of Se necessary to saturate GPx enzymes. However, increasing evidence suggests that other enzymes may be more important than GPx for Se action, that optimal levels may depend upon the form of Se being ingested, and vary according to genotype. New paradigms, possibly involving nutrigenomic tools, will be necessary to optimise the forms and levels of Se desirable for maximum protection of genomic stability in all humans.

  1. Stability of singular networked control systems with control constraint

    Institute of Scientific and Technical Information of China (English)

    Qiu Zhanzhi; Zhang Qingling; Zhao Zhiwu

    2007-01-01

    Based on bounded network-induced time-delay, the networked control system is modeled as a linear time-variant singular system.Using the Lyapunov theory and the linear matrix inequality approach, the criteria for delay-independent stability and delay-dependent stability of singular networked control systems are derived and transformed to a feasibility problem of linear matrix inequality formulation, which can be solved by the Matlab LMI toolbox, and the feasible solutions provide the maximum allowable delay bound that makes the system stable.A numerical example is provided, which shows that the analysis method is valid and the stability criteria are feasible.

  2. MASCOT - MATLAB Stability and Control Toolbox

    Science.gov (United States)

    Kenny, Sean; Crespo, Luis

    2011-01-01

    MASCOT software was created to provide the conceptual aircraft designer accurate predictions of air vehicle stability and control characteristics. The code takes as input mass property data in the form of an inertia tensor, aerodynamic loading data, and propulsion (i.e. thrust) loading data. Using fundamental non-linear equations of motion, MASCOT then calculates vehicle trim and static stability data for any desired flight condition. Common predefined flight conditions are included. The predefined flight conditions include six horizontal and six landing rotation conditions with varying options for engine out, crosswind and sideslip, plus three takeoff rotation conditions. Results are displayed through a unique graphical interface developed to provide stability and control information to the conceptual design engineers using a qualitative scale indicating whether the vehicle has acceptable, marginal, or unacceptable static stability characteristics. This software allows the user to prescribe the vehicle s CG location, mass, and inertia tensor so that any loading configuration between empty weight and maximum take-off weight can be analyzed. The required geometric and aerodynamic data as well as mass and inertia properties may be entered directly, passed through data files, or come from external programs such as Vehicle Sketch Pad (VSP). The current version of MASCOT has been tested with VSP used to compute the required data, which is then passed directly into the program. In VSP, the vehicle geometry is created and manipulated. The aerodynamic coefficients, stability and control derivatives, are calculated using VorLax, which is now available directly within VSP. MASCOT has been written exclusively using the technical computing language MATLAB . This innovation is able to bridge the gap between low-fidelity conceptual design and higher-fidelity stability and control analysis. This new tool enables the conceptual design engineer to include detailed static stability

  3. Chromatin Dynamics in Genome Stability: Roles in Suppressing Endogenous DNA Damage and Facilitating DNA Repair

    Directory of Open Access Journals (Sweden)

    Nidhi Nair

    2017-07-01

    Full Text Available Genomic DNA is compacted into chromatin through packaging with histone and non-histone proteins. Importantly, DNA accessibility is dynamically regulated to ensure genome stability. This is exemplified in the response to DNA damage where chromatin relaxation near genomic lesions serves to promote access of relevant enzymes to specific DNA regions for signaling and repair. Furthermore, recent data highlight genome maintenance roles of chromatin through the regulation of endogenous DNA-templated processes including transcription and replication. Here, we review research that shows the importance of chromatin structure regulation in maintaining genome integrity by multiple mechanisms including facilitating DNA repair and directly suppressing endogenous DNA damage.

  4. Viral genome segmentation can result from a trade-off between genetic content and particle stability.

    Science.gov (United States)

    Ojosnegros, Samuel; García-Arriaza, Juan; Escarmís, Cristina; Manrubia, Susanna C; Perales, Celia; Arias, Armando; Mateu, Mauricio García; Domingo, Esteban

    2011-03-01

    The evolutionary benefit of viral genome segmentation is a classical, yet unsolved question in evolutionary biology and RNA genetics. Theoretical studies anticipated that replication of shorter RNA segments could provide a replicative advantage over standard size genomes. However, this question has remained elusive to experimentalists because of the lack of a proper viral model system. Here we present a study with a stable segmented bipartite RNA virus and its ancestor non-segmented counterpart, in an identical genomic nucleotide sequence context. Results of RNA replication, protein expression, competition experiments, and inactivation of infectious particles point to a non-replicative trait, the particle stability, as the main driver of fitness gain of segmented genomes. Accordingly, measurements of the volume occupation of the genome inside viral capsids indicate that packaging shorter genomes involves a relaxation of the packaging density that is energetically favourable. The empirical observations are used to design a computational model that predicts the existence of a critical multiplicity of infection for domination of segmented over standard types. Our experiments suggest that viral segmented genomes may have arisen as a molecular solution for the trade-off between genome length and particle stability. Genome segmentation allows maximizing the genetic content without the detrimental effect in stability derived from incresing genome length.

  5. Viral genome segmentation can result from a trade-off between genetic content and particle stability.

    Directory of Open Access Journals (Sweden)

    Samuel Ojosnegros

    2011-03-01

    Full Text Available The evolutionary benefit of viral genome segmentation is a classical, yet unsolved question in evolutionary biology and RNA genetics. Theoretical studies anticipated that replication of shorter RNA segments could provide a replicative advantage over standard size genomes. However, this question has remained elusive to experimentalists because of the lack of a proper viral model system. Here we present a study with a stable segmented bipartite RNA virus and its ancestor non-segmented counterpart, in an identical genomic nucleotide sequence context. Results of RNA replication, protein expression, competition experiments, and inactivation of infectious particles point to a non-replicative trait, the particle stability, as the main driver of fitness gain of segmented genomes. Accordingly, measurements of the volume occupation of the genome inside viral capsids indicate that packaging shorter genomes involves a relaxation of the packaging density that is energetically favourable. The empirical observations are used to design a computational model that predicts the existence of a critical multiplicity of infection for domination of segmented over standard types. Our experiments suggest that viral segmented genomes may have arisen as a molecular solution for the trade-off between genome length and particle stability. Genome segmentation allows maximizing the genetic content without the detrimental effect in stability derived from incresing genome length.

  6. Viral Genome Segmentation Can Result from a Trade-Off between Genetic Content and Particle Stability

    Science.gov (United States)

    Ojosnegros, Samuel; García-Arriaza, Juan; Escarmís, Cristina; Manrubia, Susanna C.; Perales, Celia; Arias, Armando; Mateu, Mauricio García; Domingo, Esteban

    2011-01-01

    The evolutionary benefit of viral genome segmentation is a classical, yet unsolved question in evolutionary biology and RNA genetics. Theoretical studies anticipated that replication of shorter RNA segments could provide a replicative advantage over standard size genomes. However, this question has remained elusive to experimentalists because of the lack of a proper viral model system. Here we present a study with a stable segmented bipartite RNA virus and its ancestor non-segmented counterpart, in an identical genomic nucleotide sequence context. Results of RNA replication, protein expression, competition experiments, and inactivation of infectious particles point to a non-replicative trait, the particle stability, as the main driver of fitness gain of segmented genomes. Accordingly, measurements of the volume occupation of the genome inside viral capsids indicate that packaging shorter genomes involves a relaxation of the packaging density that is energetically favourable. The empirical observations are used to design a computational model that predicts the existence of a critical multiplicity of infection for domination of segmented over standard types. Our experiments suggest that viral segmented genomes may have arisen as a molecular solution for the trade-off between genome length and particle stability. Genome segmentation allows maximizing the genetic content without the detrimental effect in stability derived from incresing genome length. PMID:21437265

  7. Editorial: 3Rs tightly intertwined to maintain genome stability

    DEFF Research Database (Denmark)

    2017-01-01

    DNA recombination, repair and replication are three large and vibrant research fields where each ‘R’ could deserve a series of reviews in its own right. However, as the 3Rs are tightly interwoven processes, one R can often not be fully understood without including the others. For example, replica......DNA recombination, repair and replication are three large and vibrant research fields where each ‘R’ could deserve a series of reviews in its own right. However, as the 3Rs are tightly interwoven processes, one R can often not be fully understood without including the others. For example......, replication of damaged DNA results in stalled replication forks that await DNA damage repair before replication can be resumed. In turn, the repair of most lesions depends on processes involving DNA synthesis. At the same time, the stalled forks may engage in recombination, either as part of a controlled...... repair process or by accident, just because it can, with the risk of producing genome rearrangements and loss of heterozygosity. The set of reviews presented in this thematic issue (https://academic-oup-com.proxy.findit.dtu.dk/femsyr/pages/replication_recombination_and_repair) of FEMSYR has been selected...

  8. Renewable source controls for grid stability.

    Energy Technology Data Exchange (ETDEWEB)

    Byrne, Raymond Harry; Elliott, Ryan Thomas; Neely, Jason C.; Silva Monroy, Cesar Augusto; Schoenwald, David Alan; Grant, Lisa

    2012-12-01

    The goal of this study was to evaluate the small signal and transient stability of the Western Electric- ity Coordinating Council (WECC) under high penetrations of renewable energy, and to identify control technologies that would improve the system performance. The WECC is the regional entity responsible for coordinating and promoting bulk electric system reliability in the Western Interconnection. Transient stability is the ability of the power system to maintain synchronism after a large disturbance while small signal stability is the ability of the power system to maintain synchronism after a small disturbance. Tran- sient stability analysis usually focuses on the relative rotor angle between synchronous machines compared to some stability margin. For this study we employed generator speed relative to system speed as a metric for assessing transient stability. In addition, we evaluated the system transient response using the system frequency nadir, which provides an assessment of the adequacy of the primary frequency control reserves. Small signal stability analysis typically identi es the eigenvalues or modes of the system in response to a disturbance. For this study we developed mode shape maps for the di erent scenarios. Prony analysis was applied to generator speed after a 1.4 GW, 0.5 second, brake insertion at various locations. Six di erent WECC base cases were analyzed, including the 2022 light spring case which meets the renewable portfolio standards. Because of the di culty in identifying the cause and e ect relationship in large power system models with di erent scenarios, several simulations were run on a 7-bus, 5-generator system to isolate the e ects of di erent con gurations. Based on the results of the study, for a large power system like the WECC, incorporating frequency droop into wind/solar systems provides a larger bene t to system transient response than replacing the lost inertia with synthetic inertia. From a small signal stability

  9. Studies on the molecular correlates of genomic stability in rat brain cells following Amalakirasayana therapy.

    Science.gov (United States)

    Swain, Umakanta; Sindhu, Kiran Kumar; Boda, Ushasri; Pothani, Suresh; Giridharan, Nappan V; Raghunath, Manchala; Rao, Kalluri Subba

    2012-04-01

    Adult Wistar NIN (WNIN) rats (6 months old) of both sexes were orally fed Amalakirasayana at a dose of 4.5 g per kg body weight, five days in a week. The Amalakirasayana was prepared by Arya Vaidya Sala, Kottakkal, Kerala, India, which is considered as gold standard. After 3, 9 and 15 months of such therapeutic regime, rats were sacrificed and various tissues including brain were removed. Isolated cell suspensions of neurons and astroglia were prepared from the cerebral cortex. DNA damage, as a prime indicator of the status of genomic stability was measured in terms of single (SSBs) and double strand breaks (DSBs) through (a). The "comet" assay and (b). The biochemical methods utilizing the unique properties of Escherichia coli DNA polymerase I (pol I) and calf thymus terminal transferase. The results convincingly indicate that while in control animals, there was a distinct increase in DNA damage with age in neurons and astrocytes, rasayana fed animals showed significantly less DNA damage in brain cells demonstrating beneficial effects of Rasayana therapy towards maintenance of genomic stability. DNA-damage may be the proximal cause of aging and strategies to reduce the rate of aging could be based on this fact.

  10. Criteria for Stability of Linear Control Systems

    Institute of Scientific and Technical Information of China (English)

    JING Yan-fei; HUANG Ting-zhu

    2007-01-01

    As it is well known, it is significant to know whether a matrix is an H-matrix or not in stability analysis of linear control systems. However, to distinguish H-matrices is difficult in real applications. In this paper, a practical extension of the sufficient conditions for H-matrices is investigated under some conditions. A larger scale of H-matrices which can be judged by the proposed method is shown by the numerical examples.

  11. Stability of self-control: Hirschi's redefined self-control.

    Science.gov (United States)

    Jo, Youngoh

    2015-01-01

    In 2004, Hirschi redefined self-control by using the framework of his social control theory while retaining assumptions of his original self-control theory. A few studies have provided supportive evidence for the relationship between the newly defined self-control and deviant behavior, whereas no study has tested stability hypothesis by using this new self-control. This is the first study that examines whether the stability hypothesis is still valid in the revised self-control theory. A recent longitudinal national sample of South Korean youths has been used for this purpose. Correlation analysis revealed moderate relationships among self-control measures for 5 years. Self-control differences across genders and across offenders/nonoffenders were significant and consistent. Finally, the results of growth-mixture modeling indicated that 89.5% of the sample exhibited stable group differences in self-control. These findings provide support for the stability thesis in the new version of self-control theory. The implications of these findings are discussed. © The Author(s) 2013.

  12. Liapunov Functions and Stability in Control Theory

    CERN Document Server

    Bacciotti, Andrea

    2005-01-01

    This book presents a modern and self-contained treatment of the Liapunov method for stability analysis, in the framework of mathematical nonlinear control theory. A Particular focus is on the problem of the existence of Liapunov functions (converse Liapunov theorems) and their regularity, whose interest is especially motivated by applications to automatic control. Many recent results in this area have been collected and presented in a systematic way. Some of them are given in extended, unified versions and with new, simpler proofs. In the 2nd edition of this successful book several new section

  13. ? stability of wind turbine switching control

    Science.gov (United States)

    Palejiya, Dushyant; Shaltout, Mohamed; Yan, Zeyu; Chen, Dongmei

    2015-01-01

    In order to maximise the wind energy capture, wind turbines are operated at variable speeds. Depending on the wind speed, a turbine switches between two operating modes: a low wind speed mode and a high wind speed mode. During the low wind speed mode, the control objective is to maximise wind energy capture by controlling both the blade pitch angle and the electrical generator torque. During the high wind speed mode, the control goal is to maintain the rated power generation by only adjusting the blade pitch angle. This paper establishes the stability criteria for the switching operation of wind turbines using ? gain under the nonlinear control framework. Also, the performance of the wind turbine system is analysed by using the step response, a well-known measure for second-order linear systems.

  14. Empowering African genomics for infectious disease control.

    Science.gov (United States)

    Folarin, Onikepe A; Happi, Anise N; Happi, Christian T

    2014-11-07

    At present, African scientists can only participate minimally in the genomics revolution that is transforming the understanding, surveillance and clinical treatment of infectious diseases. We discuss new initiatives to equip African scientists with knowledge of cutting-edge genomics tools, and build a sustainable critical mass of well-trained African infectious diseases genomics scientists.

  15. Phosphorylation of EB2 by Aurora B and CDK1 ensures mitotic progression and genome stability.

    Science.gov (United States)

    Iimori, Makoto; Watanabe, Sugiko; Kiyonari, Shinichi; Matsuoka, Kazuaki; Sakasai, Ryo; Saeki, Hiroshi; Oki, Eiji; Kitao, Hiroyuki; Maehara, Yoshihiko

    2016-03-31

    Temporal regulation of microtubule dynamics is essential for proper progression of mitosis and control of microtubule plus-end tracking proteins by phosphorylation is an essential component of this regulation. Here we show that Aurora B and CDK1 phosphorylate microtubule end-binding protein 2 (EB2) at multiple sites within the amino terminus and a cluster of serine/threonine residues in the linker connecting the calponin homology and end-binding homology domains. EB2 phosphorylation, which is strictly associated with mitotic entry and progression, reduces the binding affinity of EB2 for microtubules. Expression of non-phosphorylatable EB2 induces stable kinetochore microtubule dynamics and delays formation of bipolar metaphase plates in a microtubule binding-dependent manner, and leads to aneuploidy even in unperturbed mitosis. We propose that Aurora B and CDK1 temporally regulate the binding affinity of EB2 for microtubules, thereby ensuring kinetochore microtubule dynamics, proper mitotic progression and genome stability.

  16. COMSAC: Computational Methods for Stability and Control. Part 1

    Science.gov (United States)

    Fremaux, C. Michael (Compiler); Hall, Robert M. (Compiler)

    2004-01-01

    Work on stability and control included the following reports:Introductory Remarks; Introduction to Computational Methods for Stability and Control (COMSAC); Stability & Control Challenges for COMSAC: a NASA Langley Perspective; Emerging CFD Capabilities and Outlook A NASA Langley Perspective; The Role for Computational Fluid Dynamics for Stability and Control:Is it Time?; Northrop Grumman Perspective on COMSAC; Boeing Integrated Defense Systems Perspective on COMSAC; Computational Methods in Stability and Control:WPAFB Perspective; Perspective: Raytheon Aircraft Company; A Greybeard's View of the State of Aerodynamic Prediction; Computational Methods for Stability and Control: A Perspective; Boeing TacAir Stability and Control Issues for Computational Fluid Dynamics; NAVAIR S&C Issues for CFD; An S&C Perspective on CFD; Issues, Challenges & Payoffs: A Boeing User s Perspective on CFD for S&C; and Stability and Control in Computational Simulations for Conceptual and Preliminary Design: the Past, Today, and Future?

  17. Microsatellite interruptions stabilize primate genomes and exist as population-specific single nucleotide polymorphisms within individual human genomes.

    Science.gov (United States)

    Ananda, Guruprasad; Hile, Suzanne E; Breski, Amanda; Wang, Yanli; Kelkar, Yogeshwar; Makova, Kateryna D; Eckert, Kristin A

    2014-07-01

    Interruptions of microsatellite sequences impact genome evolution and can alter disease manifestation. However, human polymorphism levels at interrupted microsatellites (iMSs) are not known at a genome-wide scale, and the pathways for gaining interruptions are poorly understood. Using the 1000 Genomes Phase-1 variant call set, we interrogated mono-, di-, tri-, and tetranucleotide repeats up to 10 units in length. We detected ∼26,000-40,000 iMSs within each of four human population groups (African, European, East Asian, and American). We identified population-specific iMSs within exonic regions, and discovered that known disease-associated iMSs contain alleles present at differing frequencies among the populations. By analyzing longer microsatellites in primate genomes, we demonstrate that single interruptions result in a genome-wide average two- to six-fold reduction in microsatellite mutability, as compared with perfect microsatellites. Centrally located interruptions lowered mutability dramatically, by two to three orders of magnitude. Using a biochemical approach, we tested directly whether the mutability of a specific iMS is lower because of decreased DNA polymerase strand slippage errors. Modeling the adenomatous polyposis coli tumor suppressor gene sequence, we observed that a single base substitution interruption reduced strand slippage error rates five- to 50-fold, relative to a perfect repeat, during synthesis by DNA polymerases α, β, or η. Computationally, we demonstrate that iMSs arise primarily by base substitution mutations within individual human genomes. Our biochemical survey of human DNA polymerase α, β, δ, κ, and η error rates within certain microsatellites suggests that interruptions are created most frequently by low fidelity polymerases. Our combined computational and biochemical results demonstrate that iMSs are abundant in human genomes and are sources of population-specific genetic variation that may affect genome stability. The

  18. Fault zone roughness controls slip stability

    Science.gov (United States)

    Harbord, Christopher; Nielsen, Stefan; De Paola, Nicola

    2016-04-01

    Fault roughness is an important control factor in the mechanical behaviour of fault zones, in particular the frictional slip stability and subsequent earthquake nucleation. Despite this, there is little experimental quantification as to the effects of varying roughness upon rate- and state-dependant friction (RSF). Utilising a triaxial deformation apparatus and a novel adaptation of the direct shear methodology to simulate initially bare faults in Westerly Granite, we performed a series of velocity step frictional sliding experiments. Initial root mean square roughnesses (Sq) was varied in the range 6x10-7 - 2.4x10-5 m. We also investigated the effects upon slip stability of normal stress variation in the range σn = 30 - 200 MPa, and slip velocity between 0.1 - 10 μm s-1. A transition from stable sliding to unstable slip (manifested by stick-slip and slow slip events) was observed, depending on the parameter combination, thus covering the full spectrum of fault slip behaviours. At low normal stress (σn = 30MPa) smooth faults (Sqstress drops on slow slip events upon velocity increase), with strongly velocity weakening friction. When normal stress is increased to intermediate values (σn = 100 - 150 MPa), smooth faults (Sqstress (σn = 200 MPa) a transition from unstable to stable sliding is observed for smooth faults, which is not expected using RSF stability criteria. At all conditions sliding is stable for rough faults (Sq> 1x10-6 m). We find that instability can develop when the ratio of fault to critical stiffness kf kc > 10, or, alternatively, even when a - b > 0 at σn = 150MPa, suggesting that bare surfaces may not strictly obey the R+S stability condition. Additionally we present white light interferometry and SEM analysis of experimentally deformed samples which provide information about the distribution and physical nature of frictional contact. Significantly we suggest that bare fault surfaces may require a different stability criterion (based on

  19. Akt: A Double-Edged Sword in Cell Proliferation and Genome Stability

    Directory of Open Access Journals (Sweden)

    Naihan Xu

    2012-01-01

    Full Text Available The Akt family of serine/threonine protein kinases are key regulators of multiple aspects of cell behaviour, including proliferation, survival, metabolism, and tumorigenesis. Growth-factor-activated Akt signalling promotes progression through normal, unperturbed cell cycles by acting on diverse downstream factors involved in controlling the G1/S and G2/M transitions. Remarkably, several recent studies have also implicated Akt in modulating DNA damage responses and genome stability. High Akt activity can suppress ATR/Chk1 signalling and homologous recombination repair (HRR via direct phosphorylation of Chk1 or TopBP1 or, indirectly, by inhibiting recruitment of double-strand break (DSB resection factors, such as RPA, Brca1, and Rad51, to sites of damage. Loss of checkpoint and/or HRR proficiency is therefore a potential cause of genomic instability in tumor cells with high Akt. Conversely, Akt is activated by DNA double-strand breaks (DSBs in a DNA-PK- or ATM/ATR-dependent manner and in some circumstances can contribute to radioresistance by stimulating DNA repair by nonhomologous end joining (NHEJ. Akt therefore modifies both the response to and repair of genotoxic damage in complex ways that are likely to have important consequences for the therapy of tumors with deregulation of the PI3K-Akt-PTEN pathway.

  20. Identification and annotation of promoter regions in microbial genome sequences on the basis of DNA stability

    Indian Academy of Sciences (India)

    Vetriselvi Rangannan; Manju Bansal

    2007-08-01

    Analysis of various predicted structural properties of promoter regions in prokaryotic as well as eukaryotic genomes had earlier indicated that they have several common features, such as lower stability, higher curvature and less bendability, when compared with their neighboring regions. Based on the difference in stability between neighboring upstream and downstream regions in the vicinity of experimentally determined transcription start sites, a promoter prediction algorithm has been developed to identify prokaryotic promoter sequences in whole genomes. The average free energy (E) over known promoter sequences and the difference (D) between E and the average free energy over the entire genome (G) are used to search for promoters in the genomic sequences. Using these cutoff values to predict promoter regions across entire Escherichia coli genome, we achieved a reliability of 70% when the predicted promoters were cross verified against the 960 transcription start sites (TSSs) listed in the Ecocyc database. Annotation of the whole E. coli genome for promoter region could be carried out with 49% accuracy. The method is quite general and it can be used to annotate the promoter regions of other prokaryotic genomes.

  1. ABSOLUTE STABILITY OF GENERAL LURIE TYPE INDIRECT CONTROL SYSTEMS

    Institute of Scientific and Technical Information of China (English)

    甘作新; 葛渭高; 赵素霞; 仵永先

    2001-01-01

    In this paper, by introducing a new concept of absolute stability for a certain argument, necessary and sufficient conditions for absolute stability of general Lurie indirect control systems are obtained, and some practical sufficient conditions are also given.

  2. LHC beam stability and feedback control

    Energy Technology Data Exchange (ETDEWEB)

    Steinhagen, Ralph

    2007-07-20

    This report presents the stability and the control of the Large Hadron Collider's (LHC) two beam orbits and their particle momenta using beam-based feedback systems. The aim of this report is to contribute to a safe and reliable LHC commissioning and machine operation. The first part of the analysis gives an estimate of the expected sources of orbit and energy perturbations that can be grouped into environmental sources, machine-inherent sources and machine element failures: the slowest perturbation due to ground motion, tides, temperature fluctuations of the tunnel and other environmental influences are described in this report by a propagation model that is both qualitatively and quantitatively supported by geophone and beam motion measurements at LEP and other CERN accelerators. The second part of this analysis deals with the control of the two LHC beams' orbit and energy through automated feedback systems. Based on the reading of the more than 1056 beam position monitors (BPMs) that are distributed over the machine, a central global feedback controller calculates new deflection strengths for the more than 1060 orbit corrector magnets (CODs) that are suitable to correct the orbit and momentum around their references. this report provides an analysis of the BPMs and CODs involved in the orbit and energy feedback. The BPMs are based on a wide-band time normaliser circuit that converts the transverse beam position reading of each individual particle bunch into two laser pulses that are separated by a time delay and transmitted through optical fibres to an acquisition card that converts the delay signals into a digital position. A simple error model has been tested and compared to the measurement accuracy of LHC type BPMs, obtained through beam-based measurements in the SPS. The average beam position is controlled through 1060 superconducting and individually powered corrector dipole magnets. The proposed correction in 'time-domain' consists of a

  3. Frequency domain stability criteria for fractional-order control systems

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    This paper concerns about the frequency domain stability criteria for fractional-order control systems. On the base of characteristics of the fractional-order equations solutions, we consider the Nyquist stability criterion in a wider sense and obtain a more common means to analyze the stability of fractional-order systems conveniently. Finally, this paper illustrates the generalized stability criteria with an example to show the effect of the parameters variation on the fractional-order control systems.

  4. Comparison of genome stability in two pig breeds by using the sister chromatid exchange (SCE test

    Directory of Open Access Journals (Sweden)

    V. Barbieri

    2010-01-01

    Full Text Available The sister chromatid exchange (SCE test has been used to detect genome stability in humans (Chaganti, 1974 and the main livestock species (Ciotola et al., 2004; Di Meo et al., 2000; Di Berardino et al., 1979, and to discover DNA damage caused by a variety of natural and artificial chemical compounds (Iannuzzi et al., 1990.

  5. The Csr system regulates genome-wide mRNA stability and transcription and thus gene expression in Escherichia coli.

    Science.gov (United States)

    Esquerré, Thomas; Bouvier, Marie; Turlan, Catherine; Carpousis, Agamemnon J; Girbal, Laurence; Cocaign-Bousquet, Muriel

    2016-04-26

    Bacterial adaptation requires large-scale regulation of gene expression. We have performed a genome-wide analysis of the Csr system, which regulates many important cellular functions. The Csr system is involved in post-transcriptional regulation, but a role in transcriptional regulation has also been suggested. Two proteins, an RNA-binding protein CsrA and an atypical signaling protein CsrD, participate in the Csr system. Genome-wide transcript stabilities and levels were compared in wildtype E. coli (MG1655) and isogenic mutant strains deficient in CsrA or CsrD activity demonstrating for the first time that CsrA and CsrD are global negative and positive regulators of transcription, respectively. The role of CsrA in transcription regulation may be indirect due to the 4.6-fold increase in csrD mRNA concentration in the CsrA deficient strain. Transcriptional action of CsrA and CsrD on a few genes was validated by transcriptional fusions. In addition to an effect on transcription, CsrA stabilizes thousands of mRNAs. This is the first demonstration that CsrA is a global positive regulator of mRNA stability. For one hundred genes, we predict that direct control of mRNA stability by CsrA might contribute to metabolic adaptation by regulating expression of genes involved in carbon metabolism and transport independently of transcriptional regulation.

  6. Sequencing the CHO DXB11 genome reveals regional variations in genomic stability and haploidy

    DEFF Research Database (Denmark)

    Kaas, Christian Schrøder; Kristensen, Claus; Betenbaugh, Michael J.

    2015-01-01

    Background: The DHFR negative CHO DXB11 cell line (also known as DUX-B11 and DUKX) was historically the first CHO cell line to be used for large scale production of heterologous proteins and is still used for production of a number of complex proteins.  Results: Here we present the genomic sequen...

  7. Network Structure and Dynamics, and Emergence of Robustness by Stabilizing Selection in an Artificial Genome

    CERN Document Server

    Rohlf, Thimo

    2008-01-01

    Genetic regulation is a key component in development, but a clear understanding of the structure and dynamics of genetic networks is not yet at hand. In this work we investigate these properties within an artificial genome model originally introduced by Reil. We analyze statistical properties of randomly generated genomes both on the sequence- and network level, and show that this model correctly predicts the frequency of genes in genomes as found in experimental data. Using an evolutionary algorithm based on stabilizing selection for a phenotype, we show that robustness against single base mutations, as well as against random changes in initial network states that mimic stochastic fluctuations in environmental conditions, can emerge in parallel. Evolved genomes exhibit characteristic patterns on both sequence and network level.

  8. High Telomerase Activity Correlates with the Stabilities of Genome and DNA Ploidy in Renal Cell Carcinoma

    Directory of Open Access Journals (Sweden)

    Hideki Izumi

    2002-01-01

    Full Text Available Malignant tumors have telomerase activity, which is thought to play a critical role in tumor growth. However, the relation between telomerase activity and genomic DNA status in tumor cells is poorly understood. In the present study, we examined telomerase activity in 13 clear cell type renal cell carcinomas (CRCCs with similar clinicopathologic features by telomeric repeat amplification protocol assay (TRAP. Based on TRAP assay results, we divided the CRCCs into two groups: a high telomerase activity group and a low/no telomerase activity group. We then analyzed genomic aberration, DNA ploidy, and telomere status in these two groups by comparative genomic hybridization (CGH, laser scanning cytometry (LSC, and telomere-specific fluorescence in situ hybridization (T-FISH, respectively. CGH showed the high telomerase activity group to have fewer genomic changes than the low/no telomerase activity group, which had many genomic aberrations. Moreover, with LSC, DNA diploid cells were found more frequently in the high telomerase activity group than in the low/no telomerase activity group. In addition, T-FISH revealed strong telomere signal intensity in the high telomerase activity group compared with that of the low/no telomerase activity group. These results suggest that telomerase activity is linked to genomic DNA status and that high telomerase activity is associated with genomic stability, DNA ploidy, and telomere length in CRCC.

  9. Stabilization of model-based networked control systems

    Science.gov (United States)

    Miranda, Francisco; Abreu, Carlos; Mendes, Paulo M.

    2016-06-01

    A class of networked control systems called Model-Based Networked Control Systems (MB-NCSs) is considered. Stabilization of MB-NCSs is studied using feedback controls and simulation of stabilization for different feedbacks is made with the purpose to reduce the network trafic. The feedback control input is applied in a compensated model of the plant that approximates the plant dynamics and stabilizes the plant even under slow network conditions. Conditions for global exponential stabilizability and for the choosing of a feedback control input for a given constant time between the information moments of the network are derived. An optimal control problem to obtain an optimal feedback control is also presented.

  10. Maintaining Genome Stability: The Role of Helicases and Deaminases

    Science.gov (United States)

    2008-07-01

    and recovery. Trends Cell Biol. 16: 285–292. Keogh, M. C., T. A. Mennella, C. Sawa , S. Berthelet, N. J. Krogan et al., 2006 The Saccharomyces cerevisiae... Ishii , J. M. Sun, M. J. Pazin, J. R. Davie et al., 2006 Histone H4–K16 acetylation controls chromatin structure and protein interactions. Science 311

  11. ARTEMIS stabilizes the genome and modulates proliferative responses in multipotent mesenchymal cells

    Directory of Open Access Journals (Sweden)

    Tompkins Kathleen

    2010-10-01

    Full Text Available Abstract Background Unrepaired DNA double-stranded breaks (DSBs cause chromosomal rearrangements, loss of genetic information, neoplastic transformation or cell death. The nonhomologous end joining (NHEJ pathway, catalyzing sequence-independent direct rejoining of DSBs, is a crucial mechanism for repairing both stochastically occurring and developmentally programmed DSBs. In lymphocytes, NHEJ is critical for both development and genome stability. NHEJ defects lead to severe combined immunodeficiency (SCID and lymphoid cancer predisposition in both mice and humans. While NHEJ has been thoroughly investigated in lymphocytes, the importance of NHEJ in other cell types, especially with regard to tumor suppression, is less well documented. We previously reported evidence that the NHEJ pathway functions to suppress a range of nonlymphoid tumor types, including various classes of sarcomas, by unknown mechanisms. Results Here we investigate roles for the NHEJ factor ARTEMIS in multipotent mesenchymal stem/progenitor cells (MSCs, as putative sarcomagenic cells of origin. We demonstrate a key role for ARTEMIS in sarcoma suppression in a sensitized mouse tumor model. In this context, we found that ARTEMIS deficiency led to chromosomal damage but, paradoxically, enhanced resistance and proliferative potential in primary MSCs subjected to various stresses. Gene expression analysis revealed abnormally regulated stress response, cell proliferation, and signal transduction pathways in ARTEMIS-defective MSCs. Finally, we identified candidate regulatory genes that may, in part, mediate a stress-resistant, hyperproliferative phenotype in preneoplastic ARTEMIS-deficient MSCs. Conclusions Our discoveries suggest that Art prevents genome damage and restrains proliferation in MSCs exposed to various stress stimuli. We propose that deficiency leads to a preneoplastic state in primary MSCs and is associated with aberrant proliferative control and cellular stress

  12. Stabilization control of a bumblebee in hovering and forward flight

    Institute of Scientific and Technical Information of China (English)

    Yan Xiong; Mao Sun

    2009-01-01

    Our previous study shows that the hovering and forward flight of a bumblebee do not have inherent stabil-ity (passive stability). But the bumblebees are observed to fly stably. Stabilization control must have been applied. In this study, we investigate the longitudinal stabilization con-trol of the bumblebee. The method of computational fluid dynamics is used to compute the control derivatives and the techniques of eigenvalue and eigenvector analysis and modal decomposition are used for solving the equations of motion. Controllability analysis shows that at all flight speeds consid-ered, although inherently unstable, the flight is controllable. By feedbacking the state variables, i.e. vertical and horizon-tal velocities, pitching rate and pitch angle (which can be measured by the sensory system of the insect), to produce changes in stroke angle and angle of attack of the wings, the flight can be stabilized, explaining why the bumblebees can fly stably even if they are passively unstable.

  13. Quantized stabilization of wireless networked control systems with packet losses.

    Science.gov (United States)

    Qu, Feng-Lin; Hu, Bin; Guan, Zhi-Hong; Wu, Yong-Hong; He, Ding-Xin; Zheng, Ding-Fu

    2016-09-01

    This paper considers stabilization of discrete-time linear systems, where wireless networks exist for transmitting the sensor and controller information. Based on Markov jump systems, we show that the coarsest quantizer that stabilizes the WNCS is logarithmic in the sense of mean square quadratic stability and the stabilization of this system can be transformed into the robust stabilization of an equivalent uncertain system. Moreover, a method of optimal quantizer/controller design in terms of linear matrix inequality is presented. Finally, a numerical example is provided to illustrate the effectiveness of the developed theoretical results.

  14. RECG maintains plastid and mitochondrial genome stability by suppressing extensive recombination between short dispersed repeats.

    Directory of Open Access Journals (Sweden)

    Masaki Odahara

    2015-03-01

    Full Text Available Maintenance of plastid and mitochondrial genome stability is crucial for photosynthesis and respiration, respectively. Recently, we have reported that RECA1 maintains mitochondrial genome stability by suppressing gross rearrangements induced by aberrant recombination between short dispersed repeats in the moss Physcomitrella patens. In this study, we studied a newly identified P. patens homolog of bacterial RecG helicase, RECG, some of which is localized in both plastid and mitochondrial nucleoids. RECG partially complements recG deficiency in Escherichia coli cells. A knockout (KO mutation of RECG caused characteristic phenotypes including growth delay and developmental and mitochondrial defects, which are similar to those of the RECA1 KO mutant. The RECG KO cells showed heterogeneity in these phenotypes. Analyses of RECG KO plants showed that mitochondrial genome was destabilized due to a recombination between 8-79 bp repeats and the pattern of the recombination partly differed from that observed in the RECA1 KO mutants. The mitochondrial DNA (mtDNA instability was greater in severe phenotypic RECG KO cells than that in mild phenotypic ones. This result suggests that mitochondrial genomic instability is responsible for the defective phenotypes of RECG KO plants. Some of the induced recombination caused efficient genomic rearrangements in RECG KO mitochondria. Such loci were sometimes associated with a decrease in the levels of normal mtDNA and significant decrease in the number of transcripts derived from the loci. In addition, the RECG KO mutation caused remarkable plastid abnormalities and induced recombination between short repeats (12-63 bp in the plastid DNA. These results suggest that RECG plays a role in the maintenance of both plastid and mitochondrial genome stability by suppressing aberrant recombination between dispersed short repeats; this role is crucial for plastid and mitochondrial functions.

  15. Fuzzy-PID controlled lift feedback fin stabilizer

    Institute of Scientific and Technical Information of China (English)

    LIANG Yan-hua; JIN Hong-zhang; LIANG Li-hua

    2008-01-01

    Conventional PID controllers are widely used in fin stabilizer control systems,but they have time-variations,nonlinearity,and uncertainty influencing their control effects.A lift feedback fuzzy-PID control method was developed to better deal with these problems,and this lift feedback fin stabilizer system was simulated under different sea condition.Test results showed the system has better anti-rolling performance than traditional fin-angle PID control systems.

  16. Genome Stability of Lyme Disease Spirochetes: Comparative Genomics of Borrelia burgdorferi Plasmids

    Energy Technology Data Exchange (ETDEWEB)

    Casjens S. R.; Dunn J.; Mongodin, E. F.; Qiu, W.-G.; Luft, B. J.; Schutzer, S. E.; Gilcrease, E. B.; Huang, W. M.; Vujadinovic, M.; Aron, J. K.; Vargas, L. C.; Freeman, S.; Radune, D.; Weidman, J. F.; Dimitrov, G. I.; Khouri, H. M.; Sosa, J. E.; Halpin, R. A.; Fraser, C. M.

    2012-03-14

    Lyme disease is the most common tick-borne human illness in North America. In order to understand the molecular pathogenesis, natural diversity, population structure and epizootic spread of the North American Lyme agent, Borrelia burgdorferi sensu stricto, a much better understanding of the natural diversity of its genome will be required. Towards this end we present a comparative analysis of the nucleotide sequences of the numerous plasmids of B. burgdorferi isolates B31, N40, JD1 and 297. These strains were chosen because they include the three most commonly studied laboratory strains, and because they represent different major genetic lineages and so are informative regarding the genetic diversity and evolution of this organism. A unique feature of Borrelia genomes is that they carry a large number of linear and circular plasmids, and this work shows that strains N40, JD1, 297 and B31 carry related but non-identical sets of 16, 20, 19 and 21 plasmids, respectively, that comprise 33-40% of their genomes. We deduce that there are at least 28 plasmid compatibility types among the four strains. The B. burgdorferi {approx}900 Kbp linear chromosomes are evolutionarily exceptionally stable, except for a short {le}20 Kbp plasmid-like section at the right end. A few of the plasmids, including the linear lp54 and circular cp26, are also very stable. We show here that the other plasmids, especially the linear ones, are considerably more variable. Nearly all of the linear plasmids have undergone one or more substantial inter-plasmid rearrangements since their last common ancestor. In spite of these rearrangements and differences in plasmid contents, the overall gene complement of the different isolates has remained relatively constant.

  17. Genome stability of Lyme disease spirochetes: comparative genomics of Borrelia burgdorferi plasmids.

    Directory of Open Access Journals (Sweden)

    Sherwood R Casjens

    Full Text Available Lyme disease is the most common tick-borne human illness in North America. In order to understand the molecular pathogenesis, natural diversity, population structure and epizootic spread of the North American Lyme agent, Borrelia burgdorferi sensu stricto, a much better understanding of the natural diversity of its genome will be required. Towards this end we present a comparative analysis of the nucleotide sequences of the numerous plasmids of B. burgdorferi isolates B31, N40, JD1 and 297. These strains were chosen because they include the three most commonly studied laboratory strains, and because they represent different major genetic lineages and so are informative regarding the genetic diversity and evolution of this organism. A unique feature of Borrelia genomes is that they carry a large number of linear and circular plasmids, and this work shows that strains N40, JD1, 297 and B31 carry related but non-identical sets of 16, 20, 19 and 21 plasmids, respectively, that comprise 33-40% of their genomes. We deduce that there are at least 28 plasmid compatibility types among the four strains. The B. burgdorferi ∼900 Kbp linear chromosomes are evolutionarily exceptionally stable, except for a short ≤20 Kbp plasmid-like section at the right end. A few of the plasmids, including the linear lp54 and circular cp26, are also very stable. We show here that the other plasmids, especially the linear ones, are considerably more variable. Nearly all of the linear plasmids have undergone one or more substantial inter-plasmid rearrangements since their last common ancestor. In spite of these rearrangements and differences in plasmid contents, the overall gene complement of the different isolates has remained relatively constant.

  18. Genome engineering and gene expression control for bacterial strain development.

    Science.gov (United States)

    Song, Chan Woo; Lee, Joungmin; Lee, Sang Yup

    2015-01-01

    In recent years, a number of techniques and tools have been developed for genome engineering and gene expression control to achieve desired phenotypes of various bacteria. Here we review and discuss the recent advances in bacterial genome manipulation and gene expression control techniques, and their actual uses with accompanying examples. Genome engineering has been commonly performed based on homologous recombination. During such genome manipulation, the counterselection systems employing SacB or nucleases have mainly been used for the efficient selection of desired engineered strains. The recombineering technology enables simple and more rapid manipulation of the bacterial genome. The group II intron-mediated genome engineering technology is another option for some bacteria that are difficult to be engineered by homologous recombination. Due to the increasing demands on high-throughput screening of bacterial strains having the desired phenotypes, several multiplex genome engineering techniques have recently been developed and validated in some bacteria. Another approach to achieve desired bacterial phenotypes is the repression of target gene expression without the modification of genome sequences. This can be performed by expressing antisense RNA, small regulatory RNA, or CRISPR RNA to repress target gene expression at the transcriptional or translational level. All of these techniques allow efficient and rapid development and screening of bacterial strains having desired phenotypes, and more advanced techniques are expected to be seen.

  19. Regulation of PCNA-protein interactions for genome stability

    DEFF Research Database (Denmark)

    Mailand, Niels; Gibbs-Seymour, Ian; Bekker-Jensen, Simon

    2013-01-01

    Proliferating cell nuclear antigen (PCNA) has a central role in promoting faithful DNA replication, providing a molecular platform that facilitates the myriad protein-protein and protein-DNA interactions that occur at the replication fork. Numerous PCNA-associated proteins compete for binding...... to a common surface on PCNA; hence these interactions need to be tightly regulated and coordinated to ensure proper chromosome replication and integrity. Control of PCNA-protein interactions is multilayered and involves post-translational modifications, in particular ubiquitylation, accessory factors...... and regulated degradation of PCNA-associated proteins. This regulatory framework allows cells to maintain a fine-tuned balance between replication fidelity and processivity in response to DNA damage....

  20. Computation of robustly stabilizing PID controllers for interval systems.

    Science.gov (United States)

    Matušů, Radek; Prokop, Roman

    2016-01-01

    The paper is focused on the computation of all possible robustly stabilizing Proportional-Integral-Derivative (PID) controllers for plants with interval uncertainty. The main idea of the proposed method is based on Tan's (et al.) technique for calculation of (nominally) stabilizing PI and PID controllers or robustly stabilizing PI controllers by means of plotting the stability boundary locus in either P-I plane or P-I-D space. Refinement of the existing method by consideration of 16 segment plants instead of 16 Kharitonov plants provides an elegant and efficient tool for finding all robustly stabilizing PID controllers for an interval system. The validity and relatively effortless application of presented theoretical concepts are demonstrated through a computation and simulation example in which the uncertain mathematical model of an experimental oblique wing aircraft is robustly stabilized.

  1. Stabilization of nonlinear systems based on robust control Lyapunov function

    Institute of Scientific and Technical Information of China (English)

    CAI Xiu-shan; HAN Zheng-zhi; LU Gan-yun

    2007-01-01

    This paper deals with the robust stabilization problem for a class of nonlinear systems with structural uncertainty. Based on robust control Lyapunov function, a sufficient and necessary condition for a function to be a robust control Lyapunov function is given. From this condition, simply sufficient condition for the robust stabilization (robust practical stabilization) is deduced. Moreover, if the equilibrium of the closed-loop system is unique, the existence of such a robust control Lyapunov function will also imply robustly globally asymptotical stabilization. Then a continuous state feedback law can be constructed explicitly. The simulation shows the effectiveness of the method.

  2. Stabilization of rotational motion with application to spacecraft attitude control

    DEFF Research Database (Denmark)

    Wisniewski, Rafal

    2001-01-01

    on a Riemannian manifold. The Lyapnov stability theory is adapted and reformulated to fit to the new framework of Riemannian manifolds. Toillustrate the results a spacecraft attitude control problem is considered. Firstly, a global canonical representation for the spacecraft motion is found, then three spacecraft...... control problems are addressed: stabilization in the inertial frame, magnetic libration damping for the gravity gradient stabilization and a slew maneuver with obstacle avoidance...

  3. Stabilization of parameters of asynchronous electric drive with vector control

    Directory of Open Access Journals (Sweden)

    N.J. Khlopenko

    2015-03-01

    Full Text Available A problem of stabilization of parameters of the asynchronous electric drive vector control system is considered. Usually such systems have two control channels. The synthesis of stabilizing controllers is made for every control channel. The evaluation of variables of system status is made by observer. The problem of stabilizing controllers and observer synthesis consists in calculation of state feedback intensification. Its solution is based on existing approaches form vector control theories, matrix inequalities and Lyapunov stability. Several synthesis methods of stabilizing controllers have been proposed. Structural scheme of vector control system and observer has been built. The simulation of transient processes in the vector control system is carried out with MATLAB computing environment. The most important property of obtained solution is Lyapunov stability of control loops closed-looped by state vectors. Transient processes have been investigated on the particular example. Graphs confirming stability of such processes that flow in the vector control system in minimal period of time have been plotted down.

  4. Genomics of Entomopathogenic Nematodes and Implications for Pest Control.

    Science.gov (United States)

    Lu, Dihong; Baiocchi, Tiffany; Dillman, Adler R

    2016-08-01

    Entomopathogenic nematodes (EPNs) have been used in biological control but improvement is needed to realize their full potential for broader application in agriculture. Some improvements have been gained through selective breeding and the isolation of additional species and populations. Having genomic sequences for at least six EPNs opens the possibility of genetic improvement, either by facilitating the selection of candidate genes for hypothesis-driven studies of gene-trait relations or by genomics-assisted breeding for desirable traits. However, the genomic data will be of limited use without a more mechanistic understanding of the genes underlying traits that are important for biological control. Additionally, molecular tools are required to fully translate the genomic resources into further functional studies and better biological control. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Power system stabilizers based on modern control techniques

    Energy Technology Data Exchange (ETDEWEB)

    Malik, O.P.; Chen, G.P.; Zhang, Y.; El-Metwally, K. [Calgary Univ., AB (Canada). Dept. of Electrical and Computer Engineering

    1994-12-31

    Developments in digital technology have made it feasible to develop and implement improved controllers based on sophisticated control techniques. Power system stabilizers based on adaptive control, fuzzy logic and artificial networks are being developed. Each of these control techniques possesses unique features and strengths. In this paper, the relative performance of power systems stabilizers based on adaptive control, fuzzy logic and neural network, both in simulation studies and real time tests on a physical model of a power system, is presented and compared to that of a fixed parameter conventional power system stabilizer. (author) 16 refs., 45 figs., 3 tabs.

  6. Consensus and Stability Analysis of Networked Multiagent Predictive Control Systems.

    Science.gov (United States)

    Liu, Guo-Ping

    2017-04-01

    This paper is concerned with the consensus and stability problem of multiagent control systems via networks with communication delays and data loss. A networked multiagent predictive control scheme is proposed to achieve output consensus and also compensate for the communication delays and data loss actively. The necessary and sufficient conditions of achieving both consensus and stability of the closed-loop networked multiagent control systems are derived. An important result that is obtained is that the consensus and stability of closed-loop networked multiagent predictive control systems are not related to the communication delays and data loss. An example illustrates the performance of the networked multiagent predictive control scheme.

  7. Stability of Controlled Hamilton Systems Excited by Gaussian White Noise

    Institute of Scientific and Technical Information of China (English)

    SHANG Mei; GUO Yong-xin; MEI Feng-xiang

    2008-01-01

    A new method is introduced in this paper. This method can be used to study the stability of controlled holonomic Hamilton systems under disturbance of Gaussian white noise. At first, the motion equation of controlled holonomic Hamilton systems excited by Gaussian noise is formulated. A theory to stabilize the system is provided. Finally, one example is given to illustrate the application procedures.

  8. Stabilizing control for a class of delay unstable processes.

    Science.gov (United States)

    Lee, See Chek; Wang, Qing-Guo; Nguyen, Le Binh

    2010-07-01

    The stabilization of unstable first-order plus time-delay processes with a zero by means of simple controllers is investigated in detail. Explicit stabilizability conditions are established. And the computational methods for determining stabilizing controller parameters are also presented with illustrative examples.

  9. Control Lyapunov Stabilization of Nonlinear Systems with Structural Uncertainty

    Institute of Scientific and Technical Information of China (English)

    CAI Xiu-shan; HAN Zheng-zhi; TANG Hou-jun

    2005-01-01

    This paper deals with global stabilization problem for the nonlinear systems with structural uncertainty.Based on control Lyapunov function, a sufficient and necessary condition for the globally and asymptotically stabilizing the equailibrium of the closed system is given. Moreovery, an almost smooth state feedback control law is constructed. The simulation shows the effectiveness of the method.

  10. ABSOLUTE STABILITY OF GENERAL LURIE DISCRETE NONLINEAR CONTROL SYSTEMS

    Institute of Scientific and Technical Information of China (English)

    GAN Zuoxin; HAN Jingqing; ZHAO Suxia; WU Yongxian

    2002-01-01

    In the present paper, the absolute stability of general Lurie discrete nonlinear control systems has been discussed by Lyapunov function approach. A sufficient condition of absolute stability for the general Lurie discrete nonlinear control systems is derived, and some necessary and sufficient conditions are obtained in special cases. Meanwhile, we give a simple example to illustrate the effectiveness of the results.

  11. Inhibitory Phosphorylation of Separase Is Essential for Genome Stability and Viability of Murine Embryonic Germ Cells

    Science.gov (United States)

    Huang, Xingxu; Andreu-Vieyra, Claudia V; York, J. Philippe; Hatcher, Rashieda; Lu, Tao; Matzuk, Martin M; Zhang, Pumin

    2008-01-01

    Activity of separase, a cysteine protease that cleaves sister chromatid cohesin at the onset of anaphase, is tightly regulated to ensure faithful chromosome segregation and genome stability. Two mechanisms negatively regulate separase: inhibition by securin and phosphorylation on serine 1121. To gauge the physiological significance of the inhibitory phosphorylation, we created a mouse strain in which Ser1121 was mutated to Ala (S1121A). Here we report that this S1121A point mutation causes infertility in mice. We show that germ cells in the mutants are depleted during development. We further demonstrate that S1121A causes chromosome misalignment during proliferation of the postmigratory primordial germ cells, resulting in mitotic arrest, aneuploidy, and eventual cell death. Our results indicate that inhibitory phosphorylation of separase plays a critical role in the maintenance of sister chromatid cohesion and genome stability in proliferating postmigratory primordial germ cells. PMID:18232736

  12. Inhibitory phosphorylation of separase is essential for genome stability and viability of murine embryonic germ cells.

    Directory of Open Access Journals (Sweden)

    Xingxu Huang

    2008-01-01

    Full Text Available Activity of separase, a cysteine protease that cleaves sister chromatid cohesin at the onset of anaphase, is tightly regulated to ensure faithful chromosome segregation and genome stability. Two mechanisms negatively regulate separase: inhibition by securin and phosphorylation on serine 1121. To gauge the physiological significance of the inhibitory phosphorylation, we created a mouse strain in which Ser1121 was mutated to Ala (S1121A. Here we report that this S1121A point mutation causes infertility in mice. We show that germ cells in the mutants are depleted during development. We further demonstrate that S1121A causes chromosome misalignment during proliferation of the postmigratory primordial germ cells, resulting in mitotic arrest, aneuploidy, and eventual cell death. Our results indicate that inhibitory phosphorylation of separase plays a critical role in the maintenance of sister chromatid cohesion and genome stability in proliferating postmigratory primordial germ cells.

  13. Control of meiotic recombination frequency in plant genomes.

    Science.gov (United States)

    Henderson, Ian R

    2012-11-01

    Sexual eukaryotes reproduce via the meiotic cell division, where ploidy is halved and homologous chromosomes undergo reciprocal genetic exchange, termed crossover (CO). CO frequency has a profound effect on patterns of genetic variation and species evolution. Relative CO rates vary extensively both within and between plant genomes. Plant genome size varies by over 1000-fold, largely due to differential expansion of repetitive sequences, and increased genome size is associated with reduced CO frequency. Gene versus repeat sequences associate with distinct chromatin modifications, and evidence from plant genomes indicates that this epigenetic information influences CO patterns. This is consistent with data from diverse eukaryotes that demonstrate the importance of chromatin structure for control of meiotic recombination. In this review I will discuss CO frequency patterns in plant genomes and recent advances in understanding recombination distributions.

  14. Replicative Stress and the FHIT Gene: Roles in Tumor Suppression, Genome Stability and Prevention of Carcinogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Karras, Jenna R.; Paisie, Carolyn A.; Huebner, Kay, E-mail: kay.huebner@osumc.edu [Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University Wexner Medical Center, Columbus, OH 43210 (United States)

    2014-06-04

    The fragile FHIT gene, encompassing the chromosomal fragile site FRA3B, is an early target of DNA damage in precancerous cells. While vulnerable to DNA damage itself, FHIT protein expression is essential to protect from DNA damage-induced cancer initiation and progression by modulating genome stability, oxidative stress and levels of accumulating DNA damage. Thus, FHIT, whose expression is lost or reduced in many human cancers, is a tumor suppressor and genome caretaker whose loss initiates genome instability in preneoplastic lesions. Ongoing studies are seeking more detailed understanding of the role of FHIT in the cellular response to oxidative damage. This review discusses the relationship between FHIT, reactive oxygen species production, and DNA damage in the context of cancer initiation and progression.

  15. TRAIP is a PCNA-binding ubiquitin ligase that protects genome stability after replication stress

    DEFF Research Database (Denmark)

    Hoffmann, Saskia; Smedegaard, Stine; Nakamura, Kyosuke;

    2016-01-01

    , allowing cells to mitigate the threats to genome stability posed by replication stress. We identify the E3 ubiquitin ligase TRAIP as a new factor at active and stressed replication forks that directly interacts with PCNA via a conserved PCNA-interacting peptide (PIP) box motif. We show that TRAIP promotes......Cellular genomes are highly vulnerable to perturbations to chromosomal DNA replication. Proliferating cell nuclear antigen (PCNA), the processivity factor for DNA replication, plays a central role as a platform for recruitment of genome surveillance and DNA repair factors to replication forks...... ATR-dependent checkpoint signaling in human cells by facilitating the generation of RPA-bound single-stranded DNA regions upon replication stress in a manner that critically requires its E3 ligase activity and is potentiated by the PIP box. Consequently, loss of TRAIP function leads to enhanced...

  16. The contribution of dormant origins to genome stability: from cell biology to human genetics.

    Science.gov (United States)

    Alver, Robert C; Chadha, Gaganmeet Singh; Blow, J Julian

    2014-07-01

    The ability of a eukaryotic cell to precisely and accurately replicate its DNA is crucial to maintain genome stability. Here we describe our current understanding of the process by which origins are licensed for DNA replication and review recent work suggesting that fork stalling has exerted a strong selective pressure on the positioning of licensed origins. In light of this, we discuss the complex and disparate phenotypes observed in mouse models and humans patients that arise due to defects in replication licensing proteins.

  17. The C-terminal domain of the Bloom syndrome DNA helicase is essential for genomic stability

    Directory of Open Access Journals (Sweden)

    Noonan James P

    2001-07-01

    Full Text Available Abstract Background Bloom syndrome is a rare cancer-prone disorder in which the cells of affected persons have a high frequency of somatic mutation and genomic instability. Bloom syndrome cells have a distinctive high frequency of sister chromatid exchange and quadriradial formation. BLM, the protein altered in BS, is a member of the RecQ DNA helicase family, whose members share an average of 40% identity in the helicase domain and have divergent N-terminal and C-terminal flanking regions of variable lengths. The BLM DNA helicase has been shown to localize to the ND10 (nuclear domain 10 or PML (promyelocytic leukemia nuclear bodies, where it associates with TOPIIIα, and to the nucleolus. Results This report demonstrates that the N-terminal domain of BLM is responsible for localization of the protein to the nuclear bodies, while the C-terminal domain directs the protein to the nucleolus. Deletions of the N-terminal domain of BLM have little effect on sister chromatid exchange frequency and chromosome stability as compared to helicase and C-terminal mutations which can increase SCE frequency and chromosome abnormalities. Conclusion The helicase activity and the C-terminal domain of BLM are critical for maintaining genomic stability as measured by the sister chromatid exchange assay. The localization of BLM into the nucleolus by the C-terminal domain appears to be more important to genomic stability than localization in the nuclear bodies.

  18. Fault Tolerant Control: A Simultaneous Stabilization Result

    DEFF Research Database (Denmark)

    Stoustrup, Jakob; Blondel, V.D.

    2004-01-01

    This paper discusses the problem of designing fault tolerant compensators that stabilize a given system both in the nominal situation, as well as in the situation where one of the sensors or one of the actuators has failed. It is shown that such compensators always exist, provided that the system...

  19. A STABILITY THEOREM FOR CONSTRAINED OPTIMAL CONTROL PROBLEMS

    Institute of Scientific and Technical Information of China (English)

    M.H. Farag

    2004-01-01

    This paper presents the stability of difference approximations of an optimal control problem for a quasilinear parabolic equation with controls in the coefficients, boundary conditions and additional restrictions. The optimal control problem has been convered to one of the optimization problem using a penalty function technique. The difference approximations problem for the considered problem is obtained. The estimations of stability of the solution of difference approximations problem are proved. The stability estimation of the solution of difference approximations problem by the controls is obtained.

  20. Stabilization and Stochastic Control of a Class of Nonlinear Systems.

    Science.gov (United States)

    1980-10-01

    0 is infinite. Thus it is not sufficient that our composite control be only a stabilizing control . To qualify as a candidate for near-optimality uc...completes the proof. 8. Near Optimality The question can now be posed whether uc, being a stabilizing control which produces a bounded cost, is also...procedure when jjc is a small but unknown parameter. For u to be a meaningful feedback control of the system (2.1), it c must first of all be a stabilizing

  1. A bilinear self-tuning controller for multimachine transient stability

    Energy Technology Data Exchange (ETDEWEB)

    Rajkumar, V.; Zhu, W.; Mohler, R.R.; Spee, R. (Oregon State Univ., Corvallis, OR (United States). Dept. of Electrical and Computer Engineering); Mittelstadt, W.A. (Bonneville Power Administration, Portland, OR (United States)); Maratukulam, D. (Electric Power Research Inst., Palo Alto, CA (United States))

    1994-08-01

    Bilinear time-series model-based self-tuning control is proposed for a multimachine power system, controlled by a single variable series capacitor. When the faults of concern are large and de-stabilizing, it is proposed that nonlinear model-based controllers can enhance the region of stability of the power system, and return the states to their stable equilibrium. A simple predictive nonlinear self-tuning controller using local measurements of relative rotor angles is examined. It is shown to perform well in stabilizing different faults on a 45-bus, 17-generator low order model with the dynamic characteristics of the Western System Coordinating Council (WSCC) system.

  2. Stabilizing unstable steady states using multiple delay feedback control.

    Science.gov (United States)

    Ahlborn, Alexander; Parlitz, Ulrich

    2004-12-31

    Feedback control with different and independent delay times is introduced and shown to be an efficient method for stabilizing fixed points (equilibria) of dynamical systems. In comparison to other delay based chaos control methods multiple delay feedback control is superior for controlling steady states and works also for relatively large delay times (sometimes unavoidable in experiments due to system dead times). To demonstrate this approach for stabilizing unstable fixed points we present numerical simulations of Chua's circuit and a successful experimental application for stabilizing a chaotic frequency doubled Nd-doped yttrium aluminum garnet laser.

  3. New results in subspace-stabilization control theory

    Directory of Open Access Journals (Sweden)

    C. D. Johnson

    2000-01-01

    Full Text Available Subspace-stabilization is a generalization of the classical idea of stabilizing motions of a dynamical system to an equilibrium state. The concept of subspace-stabilization and a theory for designing subspace-stabilizing control laws was introduced in a previously published paper. In the present paper, two new alternative methods for designing control laws that achieve subspace-stabilization are presented. These two alternative design methods are based on: (i a novel application of existing Linear Quadratic Regulator optimal-control theory, and (ii an algebraic method in which the control-law is expressed as a linear feedback of certain “canonical variables.” In some cases, these new design methods may be more effective than existing ones. The results are illustrated by worked examples.

  4. Expression, tandem repeat copy number variation and stability of four macrosatellite arrays in the human genome

    Directory of Open Access Journals (Sweden)

    Chadwick Brian P

    2010-11-01

    Full Text Available Abstract Background Macrosatellites are some of the largest variable number tandem repeats in the human genome, but what role these unusual sequences perform is unknown. Their importance to human health is clearly demonstrated by the 4q35 macrosatellite D4Z4 that is associated with the onset of the muscle degenerative disease facioscapulohumeral muscular dystrophy. Nevertheless, many other macrosatellite arrays in the human genome remain poorly characterized. Results Here we describe the organization, tandem repeat copy number variation, transmission stability and expression of four macrosatellite arrays in the human genome: the TAF11-Like array located on chromosomes 5p15.1, the SST1 arrays on 4q28.3 and 19q13.12, the PRR20 array located on chromosome 13q21.1, and the ZAV array at 9q32. All are polymorphic macrosatellite arrays that at least for TAF11-Like and SST1 show evidence of meiotic instability. With the exception of the SST1 array that is ubiquitously expressed, all are expressed at high levels in the testis and to a lesser extent in the brain. Conclusions Our results extend the number of characterized macrosatellite arrays in the human genome and provide the foundation for formulation of hypotheses to begin assessing their functional role in the human genome.

  5. Predictive Control for Visual Servo Stabilization of Nonholonomic Mobile Robots

    Institute of Scientific and Technical Information of China (English)

    CAO Zheng-Cai; YIN Long-Jie; FU Yi-Li; LIU Tian-Long

    2013-01-01

    Visual servo stabilization of nonholonomic mobile robots has gained extensive attention.However,currently,the solution of the problem does not consider both the visibility constraints and the actuator limitations,so the designed controller is difficult to realize satisfactory performance in practical application.In this paper,a predictive controller for the visual servo stabilization of a mobile robot is presented.Firstly,a kinematic predictive stabilization controller utilized to generate the command of velocity is introduced.Then,in order to make the actual velocity of the mobile robot asymptotically approach to the desired one,a dynamic predictive controller is designed.The proposed predictive controller can deal with the constraints easily.Finally,several simulations are performed,and the results illustrate that the proposed control scheme is effective to solve the visual servo stabilization problem.

  6. Impulsive Stabilization of Uncertain Dynamical Systems and Chaos Control

    Institute of Scientific and Technical Information of China (English)

    LIUBin; YAOJian; FANGJinqing; LIUXinzhi

    2004-01-01

    In this paper, a general impulsive control problem for uncertain dynamical systems is investigated.By utilizing the method of Lyapunov functions, a set of stability criteria for uncertain impulsive dynamical systems are established. These obtained results are then appliedto derive conditions under which an uncertain dynamical system can be robustly stabilized by an impulsive control law. Finally, we demonstrate our method by controlling the famous Lorenz system with uncertain perturbation.

  7. Stability and Sensitivity Analysis of Fuzzy Control Systems. Mechatronics Applications

    OpenAIRE

    Radu-Emil Precup; Stefan Preitl

    2006-01-01

    The development of fuzzy control systems is usually performed by heuristicmeans, incorporating human skills, the drawback being in the lack of general-purposedevelopment methods. A major problem, which follows from this development, is theanalysis of the structural properties of the control system, such as stability, controllabilityand robustness. Here comes the first goal of the paper, to present a stability analysismethod dedicated to fuzzy control systems with mechatronics applications bas...

  8. Stability Analysis of Uncertain Discrete Time-Delay Control Systems

    Institute of Scientific and Technical Information of China (English)

    Long Xuming; Duan Ping

    2006-01-01

    Based on Lyapunov stability theory, a less conservative sufficient conditions for the stabilities of uncertain discrete delay-independent and delay-dependent control systems are obtained by using the linear matrix inequality (LMI) approach. Judgement of the stability of time-delay systems is transformed to judgement of the feasible solution of an LMI, and hence is solved by use of MATLAB. Numerical simulations verify the validity of the proposed method.

  9. Hybrid stabilizing control on a real mobile robot

    NARCIS (Netherlands)

    Oelen, Wilco; Berghuis, Harry; Nijmeijer, Henk; Canudas de Wit, Carlos

    1995-01-01

    To establish empirical verification of a stabilizing controller for nonholonomic systems, the authors implement a hybrid control concept on a 2-DOF mobile robot. Practical issues of velocity control are also addressed through a velocity controller which transforms the mobile robot to a new system wi

  10. Stochastic impulsive control for the stabilization of Lorenz system

    Institute of Scientific and Technical Information of China (English)

    Wang Liang; Zhao Rui; Xu Wei; Zhang Ying

    2011-01-01

    This paper derives some sufficient conditions for the stabilization of Lorenz system with stochastic impulsive control. The estimate of the upper bound of impulse interval for asymptotically stable control is obtained. Some differences between the system with stochastic impulsive control and with deterministic impulsive control are presented. Computer simulation is given to show the effectiveness of the proposed method.

  11. Stability Boundaries for Offshore Wind Park Distributed Voltage Control

    DEFF Research Database (Denmark)

    Gryning, Mikkel P.S.; Wu, Qiuwei; Kocewiak, Lukasz

    2017-01-01

    pilot control. Using data from the actual wind power plant, all stabilizing subsystem voltage proportional-integral controller parameters are first characterized based on their Hurwitz signature. Inner loop current control is then designed using Internal Mode Control principles, and guidelines for feed...

  12. Sde2: A novel nuclear protein essential for telomeric silencing and genomic stability in Schizosaccharomyces pombe

    Energy Technology Data Exchange (ETDEWEB)

    Sugioka-Sugiyama, Rie [Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8577 (Japan); Initiative for the Promotion of Young Scientists' Independent Research, University of Tsukuba, Tsukuba, Ibaraki 305-8577 (Japan); Sugiyama, Tomoyasu, E-mail: sugiyamt@biol.tsukuba.ac.jp [Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8577 (Japan); Initiative for the Promotion of Young Scientists' Independent Research, University of Tsukuba, Tsukuba, Ibaraki 305-8577 (Japan); Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012 (Japan)

    2011-03-18

    Research highlights: {yields} Sde2 is essential for telomere silencing. {yields} Sde2 is involved in the maintenance of genomic stability. {yields} Sde2 promotes the recruitment of SHREC, a histone deacetylase complex, to telomeres. -- Abstract: Telomeres, specialized domains assembled at the ends of linear chromosomes, are essential for genomic stability in eukaryotes. The formation and maintenance of telomeres are governed by numerous factors such as telomeric repeats, telomere-binding proteins, heterochromatin proteins, and telomerase. Here, we report Sde2, a novel nuclear protein essential for telomeric silencing and genomic stability in the fission yeast Schizosaccharomyces pombe. A deficiency in sde2 results in the derepression of the ura4{sup +} gene inserted near telomeric repeats, and the noncoding transcripts from telomeric regions accumulate in sde2{Delta} cells. The loss of Sde2 function compromises transcriptional silencing at telomeres, and this silencing defect is accompanied by increased levels of acetylated histone H3K14 and RNA polymerase II occupancy at telomeres as well as reduced recruitment of the SNF2 ATPase/histone deacetylase-containing complex SHREC to telomeres. Deletion of sde2 also leads to a higher frequency of mitotic minichromosome loss, and sde2{Delta} cells often form asci that contain spores in abnormal numbers, shapes, or both. In addition, sde2{Delta} cells are highly sensitive to several stresses, including high/low temperatures, bleomycin, which induces DNA damage, and thiabendazole, a microtubule-destabilizing agent. Furthermore, Sde2 genetically interacts with the telomere regulators Taz1, Pof3, and Ccq1. These findings demonstrate that Sde2 cooperates with other telomere regulators to maintain functional telomeres, thereby preventing genomic instability.

  13. Robust Stabilization of Nonlinear Systems with Uncertain Varying Control Coefficient

    Directory of Open Access Journals (Sweden)

    Zaiyue Yang

    2014-01-01

    Full Text Available This paper investigates the stabilization problem for a class of nonlinear systems, whose control coefficient is uncertain and varies continuously in value and sign. The study emphasizes the development of a robust control that consists of a modified Nussbaum function to tackle the uncertain varying control coefficient. By such a method, the finite-time escape phenomenon has been prevented when the control coefficient is crossing zero and varying its sign. The proposed control guarantees the asymptotic stabilization of the system and boundedness of all closed-loop signals. The control performance is illustrated by a numerical simulation.

  14. Robust stabilization of stochastic systems based on the LQ controller

    Institute of Scientific and Technical Information of China (English)

    Jundong BAO; Feiqi DENG; Qi LUO

    2005-01-01

    The robust exponential stability in mean square for a class of linear stochastic uncertain control systems is dealt with.For the uncertain stochastic systems,we have designed an optimal controller which guarantees the exponential stability of the system.Actually,we employed Lyapunov function approach and the stochastic algebraic Riccati equation (SARE) to have shown the robustness of the linear quadratic(LQ) optimal control law.And the algebraic criteria for the exponential stability on the linear stochastic uncertain closed-loop systems are given.

  15. SIRT7 and the DEAD-box helicase DDX21 cooperate to resolve genomic R loops and safeguard genome stability.

    Science.gov (United States)

    Song, Chenlin; Hotz-Wagenblatt, Agnes; Voit, Renate; Grummt, Ingrid

    2017-08-08

    R loops are three-stranded nucleic acid structures consisting of an RNA:DNA heteroduplex and a "looped-out" nontemplate strand. As aberrant formation and persistence of R loops block transcription elongation and cause DNA damage, mechanisms that resolve R loops are essential for genome stability. Here we show that the DEAD (Asp-Glu-Ala-Asp)-box RNA helicase DDX21 efficiently unwinds R loops and that depletion of DDX21 leads to accumulation of cellular R loops and DNA damage. Significantly, the activity of DDX21 is regulated by acetylation. Acetylation by CBP inhibits DDX21 activity, while deacetylation by SIRT7 augments helicase activity and overcomes R-loop-mediated stalling of RNA polymerases. Knockdown of SIRT7 leads to the same phenotype as depletion of DDX21 (i.e., increased formation of R loops and DNA double-strand breaks), indicating that SIRT7 and DDX21 cooperate to prevent R-loop accumulation, thus safeguarding genome integrity. Moreover, DDX21 resolves estrogen-induced R loops on estrogen-responsive genes in breast cancer cells, which prevents the blocking of transcription elongation on these genes. © 2017 Song et al.; Published by Cold Spring Harbor Laboratory Press.

  16. On stabilizing PI controller ranges for multivariable systems

    Energy Technology Data Exchange (ETDEWEB)

    Lin Chong [Institute of Complexity Science, Qingdao University, Qingdao, Shandong 266071 (China); Wang Qingguo; He Yong [Department of Electrical and Computer Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260 (Singapore); Wen Guilin [State Key Laboratory of Advanced Design and Manufactory for Vehicle Body, Hunan University, College of Mechanical and Automotive Engineering, Hunan University, Changsha, Hunan 410082 (China)], E-mail: wenguilin@yahoo.com.cn; Han Xu; Li Guangyao; Zhong Zhihua [State Key Laboratory of Advanced Design and Manufactory for Vehicle Body, Hunan University, College of Mechanical and Automotive Engineering, Hunan University, Changsha, Hunan 410082 (China)

    2008-02-15

    The paper is concerned with the computation of the maximum ranges of stabilizing proportional-integral (PI) controllers for multiple-input and multiple-output (MIMO) systems. A time-domain scheme is proposed by converting the considered problem to a robust stability problem for a polytopic system. An algorithm based on linear matrix inequality (LMI) is established to find the maximum ranges.

  17. A passivity-based approach to reset control systems stability

    NARCIS (Netherlands)

    Carrasco, Joaquín; Baños, Alfonso; Schaft, Arjan van der

    The stability of reset control systems has been mainly studied for the feedback interconnection of reset compensators with linear time-invariant systems. This work gives a stability analysis of reset compensators in feedback interconnection with passive nonlinear systems. The results are based on

  18. Passive stability and active control in a rhythmic task

    NARCIS (Netherlands)

    Wei, Kunlin; Dijkstra, Tjeerd M. H.; Sternad, Dagmar

    2007-01-01

    Rhythmically bouncing a ball with a racket is a task that affords passively stable solutions as demonstrated by stability analyses of a mathematical model of the task. Passive stability implies that no active control is needed as errors die out without requiring corrective actions. Empirical results

  19. Delay-dependent stability and stabilization criteria of networked control systems with multiple time-delays

    Institute of Scientific and Technical Information of China (English)

    Huaicheng YAN; Xinhan HUANG; Min WANG

    2006-01-01

    This paper deals with the problem of delay-dependent stability and stabilization for networked control systems(NCSs)with multiple time-delays. In view of multi-input and multi-output(MIMO) NCSs with many independent sensors and actuators, a continuous time model with distributed time-delays is proposed. Utilizing the Lyapunov stability theory combined with linear matrix inequalities(LMIs) techniques, some new delay-dependent stability criteria for NCSs in terms of generalized Lyapunov matrix equation and LMIs are derived. Stabilizing controller via state feedback is formulated by solving a set of LMIs. Compared with the reported methods, the proposed methods give a less conservative delay bound and more general results. Numerical example and simulation show that the methods are less conservative and more effective.

  20. The influence of micronutrients in cell culture: a reflection on viability and genomic stability.

    Science.gov (United States)

    Arigony, Ana Lúcia Vargas; de Oliveira, Iuri Marques; Machado, Miriana; Bordin, Diana Lilian; Bergter, Lothar; Prá, Daniel; Henriques, João Antonio Pêgas

    2013-01-01

    Micronutrients, including minerals and vitamins, are indispensable to DNA metabolic pathways and thus are as important for life as macronutrients. Without the proper nutrients, genomic instability compromises homeostasis, leading to chronic diseases and certain types of cancer. Cell-culture media try to mimic the in vivo environment, providing in vitro models used to infer cells' responses to different stimuli. This review summarizes and discusses studies of cell-culture supplementation with micronutrients that can increase cell viability and genomic stability, with a particular focus on previous in vitro experiments. In these studies, the cell-culture media include certain vitamins and minerals at concentrations not equal to the physiological levels. In many common culture media, the sole source of micronutrients is fetal bovine serum (FBS), which contributes to only 5-10% of the media composition. Minimal attention has been dedicated to FBS composition, micronutrients in cell cultures as a whole, or the influence of micronutrients on the viability and genetics of cultured cells. Further studies better evaluating micronutrients' roles at a molecular level and influence on the genomic stability of cells are still needed.

  1. The Influence of Micronutrients in Cell Culture: A Reflection on Viability and Genomic Stability

    Science.gov (United States)

    Arigony, Ana Lúcia Vargas; de Oliveira, Iuri Marques; Bordin, Diana Lilian; Prá, Daniel; Pêgas Henriques, João Antonio

    2013-01-01

    Micronutrients, including minerals and vitamins, are indispensable to DNA metabolic pathways and thus are as important for life as macronutrients. Without the proper nutrients, genomic instability compromises homeostasis, leading to chronic diseases and certain types of cancer. Cell-culture media try to mimic the in vivo environment, providing in vitro models used to infer cells' responses to different stimuli. This review summarizes and discusses studies of cell-culture supplementation with micronutrients that can increase cell viability and genomic stability, with a particular focus on previous in vitro experiments. In these studies, the cell-culture media include certain vitamins and minerals at concentrations not equal to the physiological levels. In many common culture media, the sole source of micronutrients is fetal bovine serum (FBS), which contributes to only 5–10% of the media composition. Minimal attention has been dedicated to FBS composition, micronutrients in cell cultures as a whole, or the influence of micronutrients on the viability and genetics of cultured cells. Further studies better evaluating micronutrients' roles at a molecular level and influence on the genomic stability of cells are still needed. PMID:23781504

  2. The Influence of Micronutrients in Cell Culture: A Reflection on Viability and Genomic Stability

    Directory of Open Access Journals (Sweden)

    Ana Lúcia Vargas Arigony

    2013-01-01

    Full Text Available Micronutrients, including minerals and vitamins, are indispensable to DNA metabolic pathways and thus are as important for life as macronutrients. Without the proper nutrients, genomic instability compromises homeostasis, leading to chronic diseases and certain types of cancer. Cell-culture media try to mimic the in vivo environment, providing in vitro models used to infer cells' responses to different stimuli. This review summarizes and discusses studies of cell-culture supplementation with micronutrients that can increase cell viability and genomic stability, with a particular focus on previous in vitro experiments. In these studies, the cell-culture media include certain vitamins and minerals at concentrations not equal to the physiological levels. In many common culture media, the sole source of micronutrients is fetal bovine serum (FBS, which contributes to only 5–10% of the media composition. Minimal attention has been dedicated to FBS composition, micronutrients in cell cultures as a whole, or the influence of micronutrients on the viability and genetics of cultured cells. Further studies better evaluating micronutrients' roles at a molecular level and influence on the genomic stability of cells are still needed.

  3. Control of centrin stability by Aurora A.

    Directory of Open Access Journals (Sweden)

    Kara B Lukasiewicz

    Full Text Available Aurora A is an oncogenic serine/threonine kinase which can cause cell transformation and centrosome amplification when over-expressed. Human breast tumors show excess Aurora A and phospho-centrin in amplified centrosomes. Here, we show that Aurora A mediates the phosphorylation of and localizes with centrin at the centrosome, with both proteins reaching maximum abundance from prophase through metaphase, followed by their precipitous loss in late stages of mitosis. Over-expression of Aurora A results in excess phospho-centrin and centrosome amplification. In contrast, centrosome amplification is not seen in cells over-expressing Aurora A in the presence of a recombinant centrin mutant lacking the serine phosphorylation site at residue 170. Expression of a kinase dead Aurora A results in a decrease in mitotic index and abrogation of centrin phosphorylation. Finally, a recombinant centrin mutation that mimics centrin phosphorylation increases centrin's stability against APC/C-mediated proteasomal degradation. Taken together, these results suggest that the stability of centrin is regulated in part by Aurora A, and that excess phosphorylated centrin may promote centrosome amplification in cancer.

  4. Algebraic stability criteria and symbolic derivation of stability conditions for feedback control systems

    Science.gov (United States)

    Wang, Dongming

    2012-10-01

    This article provides algebraic settings of the stability criteria of Nyquist and Popov and the circle criterion for closed-loop linear control systems with linear or nonlinear feedback whose transfer functions are rational ones with integer coefficients. The proposed settings make use of algebraic methods of parametric curve implicitisation, real root isolation, symbolic integration and quantifier elimination and allow one to derive exact stability conditions for feedback control systems with symbolic computation. An example is presented to illustrate the algebraic approach and its effectiveness. Some numerical stability results obtained previously are confirmed.

  5. Map-based control method for vehicle stability enhancement

    Institute of Scientific and Technical Information of China (English)

    Moon-Young Yoon; Seung-Hwan Baek; Kwang-Suk Boo; Heung-Seob Kim

    2015-01-01

    This work proposes a map-based control method to improve a vehicle’s lateral stability, and the performance of the proposed method is compared with that of the conventional model-referenced control method. Model-referenced control uses the sliding mode method to determine the compensated yaw moment;in contrast, the proposed map-based control uses the compensated yaw moment map acquired by vehicle stability analysis. The vehicle stability region is calculated by a topological method based on the trajectory reversal method. A 2-DOF vehicle model and Pacejka’s tire model are used to evaluate the proposed map-based control method. The properties of model-referenced control and map-based control are compared under various road conditions and driving inputs. Model-referenced control uses a control input to satisfy the linear reference model, and it generates unnecessary tire lateral forces that may lead to worse performance than an uncontrolled vehicle with step steering input on a road with a low friction coefficient. However, map-based control determines a compensated yaw moment to maintain the vehicle within the stability region, so the typical responses of vehicle enable to converge rapidly. The simulation results with sine and step steering show that map-based control provides better the tracking responsibility and control performance than model-referenced control.

  6. Absolute Stability for Lurie Control System with Unbound Time Delays

    Institute of Scientific and Technical Information of China (English)

    王天成; 王耀才; 洪留荣

    2004-01-01

    Time delay existes widely in various real engineering systems and can result in unsatisfactory performance or even an instability of control systems. Therefore, to investigate the stability for time delay systems is of vitul importance in control theory and its applications. Many researchers have studied the stability criteria of systems with constant delay or bound varying time delay, but few of them studied large time delay or unbound time delay. Large time delay existes commonly in various engineering applications. In this paper, the absolute stability of Lurie type direct control systems and indirect control systems with several time delays are discussed. Based on Lyapunov theory, the new delay dependent absolute stability criteria are derived. In our theorem, time delays can be unbound functions, which shows that the results are less conservative than that of existed criteria.

  7. Solar Dynamic Power System Stability Analysis and Control

    Science.gov (United States)

    Momoh, James A.; Wang, Yanchun

    1996-01-01

    The objective of this research is to conduct dynamic analysis, control design, and control performance test of solar power system. Solar power system consists of generation system and distribution network system. A bench mark system is used in this research, which includes a generator with excitation system and governor, an ac/dc converter, six DDCU's and forty-eight loads. A detailed model is used for modeling generator. Excitation system is represented by a third order model. DDCU is represented by a seventh order system. The load is modeled by the combination of constant power and constant impedance. Eigen-analysis and eigen-sensitivity analysis are used for system dynamic analysis. The effects of excitation system, governor, ac/dc converter control, and the type of load on system stability are discussed. In order to improve system transient stability, nonlinear ac/dc converter control is introduced. The direct linearization method is used for control design. The dynamic analysis results show that these controls affect system stability in different ways. The parameter coordination of controllers are recommended based on the dynamic analysis. It is concluded from the present studies that system stability is improved by the coordination of control parameters and the nonlinear ac/dc converter control stabilize system oscillation caused by the load change and system fault efficiently.

  8. Stability of piritramide in patient-controlled analgesia (PCA) solutions.

    Science.gov (United States)

    Remane, D; Scriba, G; Meissner, W; Hartmann, M

    2009-06-01

    For patient controlled analgesia, syringes with solutions of 1.5 mg/ml piritramide in 0.9% aqueous sodium chloride are used. The physical and chemical stability for dilutions of the commercially available preparation of piritramide is limited up to 72 hours by the manufacturer. Since application duration for patient-controlled analgesia can exceed that limited time, stability was investigated by HPLC. Our results show that these solutions are chemically stable over a time period of 60 days.

  9. Stabilization of discrete nonlinear systems based on control Lyapunov functions

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The stabilization of discrete nonlinear systems is studied.Based on control Lyapunov functions,asufficient and necessary condition for a quadratic function to be a control Lyapunov function is given.From this condition,a continuous state feedback law is constructed explicitly.It can globally asymptotically stabilize the equilibrium of the closed-loop system.A simulation example shows the effectiveness of the proposed method.

  10. Stabilizing model predictive control for constrained nonlinear distributed delay systems.

    Science.gov (United States)

    Mahboobi Esfanjani, R; Nikravesh, S K Y

    2011-04-01

    In this paper, a model predictive control scheme with guaranteed closed-loop asymptotic stability is proposed for a class of constrained nonlinear time-delay systems with discrete and distributed delays. A suitable terminal cost functional and also an appropriate terminal region are utilized to achieve asymptotic stability. To determine the terminal cost, a locally asymptotically stabilizing controller is designed and an appropriate Lyapunov-Krasoskii functional of the locally stabilized system is employed as the terminal cost. Furthermore, an invariant set for locally stabilized system which is established by using the Razumikhin Theorem is used as the terminal region. Simple conditions are derived to obtain terminal cost and terminal region in terms of Bilinear Matrix Inequalities. The method is illustrated by a numerical example.

  11. TRAIP is a PCNA-binding ubiquitin ligase that protects genome stability after replication stress

    DEFF Research Database (Denmark)

    Hoffmann, Saskia; Smedegaard, Stine; Nakamura, Kyosuke

    2016-01-01

    , allowing cells to mitigate the threats to genome stability posed by replication stress. We identify the E3 ubiquitin ligase TRAIP as a new factor at active and stressed replication forks that directly interacts with PCNA via a conserved PCNA-interacting peptide (PIP) box motif. We show that TRAIP promotes...... ATR-dependent checkpoint signaling in human cells by facilitating the generation of RPA-bound single-stranded DNA regions upon replication stress in a manner that critically requires its E3 ligase activity and is potentiated by the PIP box. Consequently, loss of TRAIP function leads to enhanced...... chromosomal instability and decreased cell survival after replication stress. These findings establish TRAIP as a PCNA-binding ubiquitin ligase with an important role in protecting genome integrity after obstacles to DNA replication....

  12. A Robust Stability and Control Theory for Hybrid Dynamical Systems

    Science.gov (United States)

    2006-09-30

    IEEE Transactions on Automatic Control , to...Dual Linear Differential Inclusions", IEEE Transactions on Automatic Control , Vol. 51, Issue 4, April 2006, pp. 661-666. D. Liberzon and J. Hespanha...34Stabilization of nonlinear systems with limited information feedback", IEEE Transactions on Automatic Control , vol. 50, no. 6, pp. 910-915,

  13. Stability and Stabilization of Networked Control System with Forward and Backward Random Time Delays

    Directory of Open Access Journals (Sweden)

    Ye-Guo Sun

    2012-01-01

    Full Text Available This paper deals with the problem of stabilization for a class of networked control systems (NCSs with random time delay via the state feedback control. Both sensor-to-controller and controller-to-actuator delays are modeled as Markov processes, and the resulting closed-loop system is modeled as a Markovian jump linear system (MJLS. Based on Lyapunov stability theorem combined with Razumikhin-based technique, a new delay-dependent stochastic stability criterion in terms of bilinear matrix inequalities (BMIs for the system is derived. A state feedback controller that makes the closed-loop system stochastically stable is designed, which can be solved by the proposed algorithm. Simulations are included to demonstrate the theoretical result.

  14. A Decision Support Tool for Transient Stability Preventive Control

    DEFF Research Database (Denmark)

    Pertl, Michael; Weckesser, Tilman; Rezkalla, Michel M.N.

    2017-01-01

    The paper presents a decision support tool for transient stability preventive control contributing to increased situation awareness of control room operators by providing additional information about the state of the power system in terms of transient stability. A time-domain approach is used...... to assess the transient stability for potentially critical faults. Potential critical fault locations are identified by a critical bus screening through analysis of pre-disturbance steady-state conditions. The identified buses are subject to a fast critical contingency screening determining the actual....... The effectiveness of the proposed method is demonstrated on a standard nine-bus and the New England test system...

  15. Sampled-Data State Feedback Stabilization of Boolean Control Networks.

    Science.gov (United States)

    Liu, Yang; Cao, Jinde; Sun, Liangjie; Lu, Jianquan

    2016-04-01

    In this letter, we investigate the sampled-data state feedback control (SDSFC) problem of Boolean control networks (BCNs). Some necessary and sufficient conditions are obtained for the global stabilization of BCNs by SDSFC. Different from conventional state feedback controls, new phenomena observed the study of SDSFC. Based on the controllability matrix, we derive some necessary and sufficient conditions under which the trajectories of BCNs can be stabilized to a fixed point by piecewise constant control (PCC). It is proved that the global stabilization of BCNs under SDSFC is equivalent to that by PCC. Moreover, algorithms are given to construct the sampled-data state feedback controllers. Numerical examples are given to illustrate the efficiency of the obtained results.

  16. Optimal boundary control and boundary stabilization of hyperbolic systems

    CERN Document Server

    Gugat, Martin

    2015-01-01

    This brief considers recent results on optimal control and stabilization of systems governed by hyperbolic partial differential equations, specifically those in which the control action takes place at the boundary.  The wave equation is used as a typical example of a linear system, through which the author explores initial boundary value problems, concepts of exact controllability, optimal exact control, and boundary stabilization.  Nonlinear systems are also covered, with the Korteweg-de Vries and Burgers Equations serving as standard examples.  To keep the presentation as accessible as possible, the author uses the case of a system with a state that is defined on a finite space interval, so that there are only two boundary points where the system can be controlled.  Graduate and post-graduate students as well as researchers in the field will find this to be an accessible introduction to problems of optimal control and stabilization.

  17. Response Based Emergency Control System for Power System Transient Stability

    Directory of Open Access Journals (Sweden)

    Huaiyuan Wang

    2015-11-01

    Full Text Available A transient stability control system for the electric power system composed of a prediction method and a control method is proposed based on trajectory information. This system, which is independent of system parameters and models, can detect the transient stability of the electric power system quickly and provide the control law when the system is unstable. Firstly, system instability is detected by the characteristic concave or convex shape of the trajectory. Secondly, the control method is proposed based on the analysis of the slope of the state plane trajectory when the power system is unstable. Two control objectives are provided according to the methods of acquiring the far end point: one is the minimal cost to restore the system to a stable state; the other one is the minimal cost to limit the maximum swing angle. The simulation indicates that the mentioned transient stability control system is efficient.

  18. Stability and Sensitivity Analysis of Fuzzy Control Systems. Mechatronics Applications

    Directory of Open Access Journals (Sweden)

    Radu-Emil Precup

    2006-01-01

    Full Text Available The development of fuzzy control systems is usually performed by heuristicmeans, incorporating human skills, the drawback being in the lack of general-purposedevelopment methods. A major problem, which follows from this development, is theanalysis of the structural properties of the control system, such as stability, controllabilityand robustness. Here comes the first goal of the paper, to present a stability analysismethod dedicated to fuzzy control systems with mechatronics applications based on the useof Popov’s hyperstability theory. The second goal of this paper is to perform the sensitivityanalysis of fuzzy control systems with respect to the parametric variations of the controlledplant for a class of servo-systems used in mechatronics applications based on theconstruction of sensitivity models. The stability and sensitivity analysis methods provideuseful information to the development of fuzzy control systems. The case studies concerningfuzzy controlled servo-systems, accompanied by digital simulation results and real-timeexperimental results, validate the presented methods.

  19. Power system dynamics stability and control

    CERN Document Server

    Padiyar, K R

    2008-01-01

    Modern power systems tend to be very Complex not only due to increasing Demand for quality power, but also on Account of extensive interconnections and increasing dependence on control for optimum utilization for existing resources. A good Knowledge of system dynamics and control is Essential for secure operation of the system. This book is intended to serve the needs of the Student and practicing engineers. A Large number of illustrative examples are included to provide an insight into the application of the theory.

  20. Robust Stability and Performance Comparison of PID and PPI Control

    Institute of Scientific and Technical Information of China (English)

    任正云; 张红; 邵惠鹤

    2004-01-01

    Predictive PI (PPI) control form, capable of time delay compensation, has been put forward recently. This control algorithm is essentially a PI controller with enhanced derivative action, which is not only suitable for long time delay process, but also of simple structure and excellent robust stability. The performance of PPI controller was demonstrated and compared with that of traditional PID controller by different tuning methods.

  1. Stability Analysis and Controller Synthesis for Single-Loop Voltage-Controlled VSIs

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Loh, Poh Chiang; Blaabjerg, Frede

    2017-01-01

    This paper analyzes the stability of the digital single-loop voltage-controlled Voltage-Source Inverters (VSIs) using linear voltage regulators. It reveals that the phase lags caused by using the resonant controller and the time delay of digital control system can stabilize the voltage loop without...... damping of the LC-filter resonance. The stability region for the digital single-loop resonant voltage control is then identified considering the effects of the discretization methods applied to the resonant controller. An enhanced voltage control scheme with widened stability region is subsequently...

  2. On the conjunction practical stability and controllability of large-scale impulsive control systems

    Institute of Scientific and Technical Information of China (English)

    Dilan CHEN; Jitao SUN

    2005-01-01

    We studied the conjunction practical stability and controllability of large-scale impulsive control systems by using the comparison systems and vector Lyapunov functions.Then the less conservative sufficient conditions for conjunction practical stability and controllability of large-scale impulsive control system were obtained.

  3. Local chromatin structure of heterochromatin regulates repeated DNA stability, nucleolus structure, and genome integrity

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Jamy C. [Univ. of California, Berkeley, CA (United States)

    2007-01-01

    Heterochromatin constitutes a significant portion of the genome in higher eukaryotes; approximately 30% in Drosophila and human. Heterochromatin contains a high repeat DNA content and a low density of protein-encoding genes. In contrast, euchromatin is composed mostly of unique sequences and contains the majority of single-copy genes. Genetic and cytological studies demonstrated that heterochromatin exhibits regulatory roles in chromosome organization, centromere function and telomere protection. As an epigenetically regulated structure, heterochromatin formation is not defined by any DNA sequence consensus. Heterochromatin is characterized by its association with nucleosomes containing methylated-lysine 9 of histone H3 (H3K9me), heterochromatin protein 1 (HP1) that binds H3K9me, and Su(var)3-9, which methylates H3K9 and binds HP1. Heterochromatin formation and functions are influenced by HP1, Su(var)3-9, and the RNA interference (RNAi) pathway. My thesis project investigates how heterochromatin formation and function impact nuclear architecture, repeated DNA organization, and genome stability in Drosophila melanogaster. H3K9me-based chromatin reduces extrachromosomal DNA formation; most likely by restricting the access of repair machineries to repeated DNAs. Reducing extrachromosomal ribosomal DNA stabilizes rDNA repeats and the nucleolus structure. H3K9me-based chromatin also inhibits DNA damage in heterochromatin. Cells with compromised heterochromatin structure, due to Su(var)3-9 or dcr-2 (a component of the RNAi pathway) mutations, display severe DNA damage in heterochromatin compared to wild type. In these mutant cells, accumulated DNA damage leads to chromosomal defects such as translocations, defective DNA repair response, and activation of the G2-M DNA repair and mitotic checkpoints that ensure cellular and animal viability. My thesis research suggests that DNA replication, repair, and recombination mechanisms in heterochromatin differ from those in

  4. Stability of DC Voltage Droop Controllers in VSC HVDC Systems

    DEFF Research Database (Denmark)

    Thams, Florian; Suul, Jon Are; D’Arco, Salvatore;

    2015-01-01

    Future multi-terminal HVDC systems are expected to utilize dc voltage droop controllers and several control implementations have been proposed in literature. This paper first classifies possible dc droop implementations in a simple framework. Then, the small-signal stability of a VSC-based conver......Future multi-terminal HVDC systems are expected to utilize dc voltage droop controllers and several control implementations have been proposed in literature. This paper first classifies possible dc droop implementations in a simple framework. Then, the small-signal stability of a VSC...

  5. Stability analysis of embedded nonlinear predictor neural generalized predictive controller

    Directory of Open Access Journals (Sweden)

    Hesham F. Abdel Ghaffar

    2014-03-01

    Full Text Available Nonlinear Predictor-Neural Generalized Predictive Controller (NGPC is one of the most advanced control techniques that are used with severe nonlinear processes. In this paper, a hybrid solution from NGPC and Internal Model Principle (IMP is implemented to stabilize nonlinear, non-minimum phase, variable dead time processes under high disturbance values over wide range of operation. Also, the superiority of NGPC over linear predictive controllers, like GPC, is proved for severe nonlinear processes over wide range of operation. The necessary conditions required to stabilize NGPC is derived using Lyapunov stability analysis for nonlinear processes. The NGPC stability conditions and improvement in disturbance suppression are verified by both simulation using Duffing’s nonlinear equation and real-time using continuous stirred tank reactor. Up to our knowledge, the paper offers the first hardware embedded Neural GPC which has been utilized to verify NGPC–IMP improvement in realtime.

  6. STABILITY ANALYSIS AND DESIGN OF PRESSURE CONTROL SYSTEM

    Directory of Open Access Journals (Sweden)

    Duraid F. Ahmed

    2013-05-01

    Full Text Available      The performance of pressure control system and stability analysis was studied for different types of controllers. A theoretical model for closed-loop system is developed and dynamic behavior of the control system was studied by introducing a step change in the pressure of the inlet stream. The results show that the theoretical response is faster than the experimental response due to the lags of the control valve and measuring elements. The pressure control system is stable for all conditions and for different control action because the real parts of roots of characteristics equation are negative but the response at PID controller is oscillatory stable. when PID controller used the response is improve due to eliminate the offset and stabilizing effect of derivative allow the proportional gain to be increased and increasing the speed of response compared to proportional and proportional-integral controllers.  

  7. Dynamics and Adaptive Control for Stability Recovery of Damaged Aircraft

    Science.gov (United States)

    Nguyen, Nhan; Krishnakumar, Kalmanje; Kaneshige, John; Nespeca, Pascal

    2006-01-01

    This paper presents a recent study of a damaged generic transport model as part of a NASA research project to investigate adaptive control methods for stability recovery of damaged aircraft operating in off-nominal flight conditions under damage and or failures. Aerodynamic modeling of damage effects is performed using an aerodynamic code to assess changes in the stability and control derivatives of a generic transport aircraft. Certain types of damage such as damage to one of the wings or horizontal stabilizers can cause the aircraft to become asymmetric, thus resulting in a coupling between the longitudinal and lateral motions. Flight dynamics for a general asymmetric aircraft is derived to account for changes in the center of gravity that can compromise the stability of the damaged aircraft. An iterative trim analysis for the translational motion is developed to refine the trim procedure by accounting for the effects of the control surface deflection. A hybrid direct-indirect neural network, adaptive flight control is proposed as an adaptive law for stabilizing the rotational motion of the damaged aircraft. The indirect adaptation is designed to estimate the plant dynamics of the damaged aircraft in conjunction with the direct adaptation that computes the control augmentation. Two approaches are presented 1) an adaptive law derived from the Lyapunov stability theory to ensure that the signals are bounded, and 2) a recursive least-square method for parameter identification. A hardware-in-the-loop simulation is conducted and demonstrates the effectiveness of the direct neural network adaptive flight control in the stability recovery of the damaged aircraft. A preliminary simulation of the hybrid adaptive flight control has been performed and initial data have shown the effectiveness of the proposed hybrid approach. Future work will include further investigations and high-fidelity simulations of the proposed hybrid adaptive Bight control approach.

  8. Stability Analysis on Speed Control System of Autonomous Underwater Vehicle

    Institute of Scientific and Technical Information of China (English)

    LI Ye; PANG Yong-jie; WAN Lei; WANG Fang; LIAO Yu-lei

    2009-01-01

    The stability of the motion control system is one of the decisive factors of the control quality for Autonomous Underwater Vehicle (AUV).The divergence of control,which the unstable system may be brought about,is fatal to the operation of AUV.The stability analysis of the PD and S-surface speed controllers based on the Lyapunov' s direct method is proposed in this paper.After decoupling the six degree-of-freedom (DOF) motions of the AUV,the axial dynamic behavior is discussed and the condition is deduced,in which the parameters selection within stability domain can guarantee the system asymptotically stable.The experimental results in a tank and on the sea have successfully verified the algorithm reliability,which can be served as a good reference for analyzing other AUV nonlinear control systems.

  9. Stability Analysis and Controller Synthesis for Digital Single-Loop Voltage-Controlled Inverters

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Loh, Poh Chiang; Blaabjerg, Frede

    2016-01-01

    This paper analyzes first the stability of single-loop digital voltage control scheme for the LC-filtered voltage source inverters. It turns out that the phase lag, caused by the time delay of digital control system and by the use of integral controller, can stabilize the voltage loop without...... damping of LC-filter resonance. The stability regions are then identified with alternative voltage controller synthesized. For further widening the stability region, an active damping approach is proposed and co-designed with the voltage controller in the discrete z-domain. Simulations and experimental...

  10. Estimation of multiply digital process control system extractive distillation stability

    Directory of Open Access Journals (Sweden)

    V. S. Kudryashov

    2016-01-01

    Full Text Available An approach to stability analysis of digital control systems associated non-stationary object on the example of the rectification process. Object modeling with cross-connections and the control scheme of the described system, discrete transfer functions in the shift operators. The equations of connection for each output of the closed-loop system. To solve this problem developed an algorithm for estimating the margin of stability of multivariable digital control systems based on the discrete root criterion, comprising the following main stages: obtaining of the characteristic polynomial of the closed-loop system for each output; computation of eigenvalues of the system matrix in the state space to determine roots of the characteristic equation and the stability of the system; determination of the stability and margin of stability by the deviation of maximum module of the root from the boundary of the high variability. To obtain the characteristic polynomial of a as discrete models of controllers and channels of IP object-use the transfer function of the first order with transport delay. The simulation was performed at different parameters of the control object, which is characterized by a stable and an unstable state of the system. VA-den analysis of the numerical values of the roots and character of their location on the complex plane, which to you-water that the system is stable or unstable. To confirm the obtained results were calculated and presented dynamic characteristics of the closed-loop system under different conditions, which confirm the initial assessment, the root criterion. To determine the factor stability of multivariable digital systems is proposed to use the deviation of the maximum root of the characteristic equation from the stability boundary. The obtained results apply to the class of symmetric multivariable control objects. The approach to assessing the sustainability of multivariable system regulation can be effectively

  11. Contribution to stability analysis of nonlinear control systems

    Directory of Open Access Journals (Sweden)

    Švarc Ivan

    2003-12-01

    Full Text Available The Popov criterion for the stability of nonlinear control systems is considered. The Popov criterion gives sufficient conditions for stability of nonlinear systems in the frequency domain. It has a direct graphical interpretation and is convenient for both design and analysis. In the article presented, a table of transfer functions of linear parts of nonlinear systems is constructed. The table includes frequency response functions and offers solutions to the stability of the given systems. The table makes a direct stability analysis of selected nonlinear systems possible. The stability analysis is solved analytically and graphically.Then it is easy to find out if the nonlinear system is or is not stable; the task that usually ranks among the difficult task in engineering practice.

  12. Linear control design for guaranteed stability of uncertain linear systems

    Science.gov (United States)

    Yedavalli, R. K.

    1986-01-01

    In this paper, a linear control design algorithm based on the elemental perturbation bounds developed recently is presented for a simple second order linear uncertain system satisfying matching conditions. The proposed method is compared with Guaranteed Cost Control (GCC), Multistep Guaranteed Cost Control (MGCC) and the Matching Condition (MC) methods and is shown to give guaranteed stability with lesser values for the control gains than some of the existing methods for the example considered.

  13. Stabilization of Networked Control Systems: Designing Effective Communication Sequences

    Science.gov (United States)

    2004-01-01

    IEEE Transactions on Automatic Control 45(7), 1279–1289. Elia, N. and S. K. Mitter (2001). Stabilization...of linear systems with limited information. IEEE Transactions on Automatic Control 46(9), 1384–1400. Hristu-Varsakelis, D. (2001). Feedback control...and R. W. Brockett (1997). Sys- tems with finite communication bandwidth constraints. i. state estimation problems.. IEEE Transactions on Automatic Control

  14. Transcription termination controls prophage maintenance in Escherichia coli genomes.

    Science.gov (United States)

    Menouni, Rachid; Champ, Stéphanie; Espinosa, Leon; Boudvillain, Marc; Ansaldi, Mireille

    2013-08-27

    Prophages represent a large fraction of prokaryotic genomes and often provide new functions to their hosts, in particular virulence and fitness. How prokaryotic cells maintain such gene providers is central for understanding bacterial genome evolution by horizontal transfer. Prophage excision occurs through site-specific recombination mediated by a prophage-encoded integrase. In addition, a recombination directionality factor (or excisionase) directs the reaction toward excision and prevents the phage genome from being reintegrated. In this work, we describe the role of the transcription termination factor Rho in prophage maintenance through control of the synthesis of transcripts that mediate recombination directionality factor expression and, thus, excisive recombination. We show that Rho inhibition by bicyclomycin allows for the expression of prophage genes that lead to excisive recombination. Thus, besides its role in the silencing of horizontally acquired genes, Rho also maintains lysogeny of defective and functional prophages.

  15. RMI, a new OB-fold complex essential for Bloom syndrome protein to maintain genome stability.

    Science.gov (United States)

    Xu, Dongyi; Guo, Rong; Sobeck, Alexandra; Bachrati, Csanad Z; Yang, Jay; Enomoto, Takemi; Brown, Grant W; Hoatlin, Maureen E; Hickson, Ian D; Wang, Weidong

    2008-10-15

    BLM, the helicase mutated in Bloom syndrome, associates with topoisomerase 3alpha, RMI1 (RecQ-mediated genome instability), and RPA, to form a complex essential for the maintenance of genome stability. Here we report a novel component of the BLM complex, RMI2, which interacts with RMI1 through two oligonucleotide-binding (OB)-fold domains similar to those in RPA. The resulting complex, named RMI, differs from RPA in that it lacks obvious DNA-binding activity. Nevertheless, RMI stimulates the dissolution of a homologous recombination intermediate in vitro and is essential for the stability, localization, and function of the BLM complex in vivo. Notably, inactivation of RMI2 in chicken DT40 cells results in an increased level of sister chromatid exchange (SCE)--the hallmark feature of Bloom syndrome cells. Epistasis analysis revealed that RMI2 and BLM suppress SCE within the same pathway. A point mutation in the OB domain of RMI2 disrupts the association between BLM and the rest of the complex, and abrogates the ability of RMI2 to suppress elevated SCE. Our data suggest that multi-OB-fold complexes mediate two modes of BLM action: via RPA-mediated protein-DNA interaction, and via RMI-mediated protein-protein interactions.

  16. Effects of antioxidants on the quality and genomic stability of induced pluripotent stem cells

    Science.gov (United States)

    Luo, Lan; Kawakatsu, Miho; Guo, Chao-Wan; Urata, Yoshishige; Huang, Wen-Jing; Ali, Haytham; Doi, Hanako; Kitajima, Yuriko; Tanaka, Takayuki; Goto, Shinji; Ono, Yusuke; Xin, Hong-Bo; Hamano, Kimikazu; Li, Tao-Sheng

    2014-01-01

    Effects of antioxidants on the quality and genomic stability of induced pluripotent stem (iPS) cells were investigated with two human iPS cell lines (201B7 and 253G1). Cells used in this study were expanded from a single colony of each cell line with the addition of proprietary antioxidant supplement or homemade antioxidant cocktail in medium, and maintained in parallel for 2 months. The cells grew well in all culture conditions and kept “stemness”. Although antioxidants modestly decreased the levels of intracellular reactive oxygen species, there were no differences in the expression of 53BP1 and pATM, two critical molecules related with DNA damage and repair, under various culture conditions. CGH analysis showed that the events of genetic aberrations were decreased only in the 253G1 iPS cells with the addition of homemade antioxidant cocktail. Long-term culture will be necessary to confirm whether low dose antioxidants improve the quality and genomic stability of iPS cells. PMID:24445363

  17. Graphic theory on interval stability of networked control systems

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A new method on the interval stability of networked control systems (NCSs) with random delay and data packet dropout is studied. Combining interval systems and NCSs, a graphic condition on judging interval stability is presented in terms of the weighted diagraph theory in graph theory. Furthermore, utilizing the graph-theoretic algorithm, the delay-depended controller gains are obtained. Aiming at the same delay and data packed dropout, several controller gains are obtained, simultaneously. The example and simulation illustrate the effectiveness of the proposed method.

  18. Power system small signal stability analysis and control

    CERN Document Server

    Mondal, Debasish; Sengupta, Aparajita

    2014-01-01

    Power System Small Signal Stability Analysis and Control presents a detailed analysis of the problem of severe outages due to the sustained growth of small signal oscillations in modern interconnected power systems. The ever-expanding nature of power systems and the rapid upgrade to smart grid technologies call for the implementation of robust and optimal controls. Power systems that are forced to operate close to their stability limit have resulted in the use of control devices by utility companies to improve the performance of the transmission system against commonly occurring power system

  19. An optimal real-time controller for vertical plasma stabilization

    CERN Document Server

    Cruz, N; Coda, S; Duval, B P; Le, H B; Rodrigues, A P; Varandas, C A F; Correia, C M B A; Goncalves, B S

    2014-01-01

    Modern Tokamaks have evolved from the initial axisymmetric circular plasma shape to an elongated axisymmetric plasma shape that improves the energy confinement time and the triple product, which is a generally used figure of merit for the conditions needed for fusion reactor performance. However, the elongated plasma cross section introduces a vertical instability that demands a real-time feedback control loop to stabilize the plasma vertical position and velocity. At the Tokamak \\`a Configuration Variable (TCV) in-vessel poloidal field coils driven by fast switching power supplies are used to stabilize highly elongated plasmas. TCV plasma experiments have used a PID algorithm based controller to correct the plasma vertical position. In late 2013 experiments a new optimal real-time controller was tested improving the stability of the plasma. This contribution describes the new optimal real-time controller developed. The choice of the model that describes the plasma response to the actuators is discussed. The ...

  20. Stabilization of synchronous generator by fuzzy logic controlled braking resistor

    Energy Technology Data Exchange (ETDEWEB)

    Ali, M.H.; Funamoto, T.; Murata, T.; Tamura, J. [Kitami Inst. of Technology, Dept. of Electrical and Electronic Engineering, Hokkaido (Japan)

    2000-08-01

    In order to enhance the transient stability of synchronous generator, a fuzzy logic switching control scheme for the braking resistor is proposed. Following a fault, variable rotor speed of the generator is measured and the firing-angle of the thyristor switch in the braking resistor is determined from the crispy output of the fuzzy controller. By controlling the firing-angle of the thyristor, braking resistor can control the accelerating power in generator and thus improves the transient stability. Simulation results have been demonstrated for both balanced and unbalanced faults. It can be concluded from the simulation results that the proposed strategy provides a simple and effective method of stabilization of synchronous generator under transient conditions. (orig.)

  1. Continuous control of chaos based on the stability criterion.

    Science.gov (United States)

    Yu, Hong Jie; Liu, Yan Zhu; Peng, Jian Hua

    2004-06-01

    A method of chaos control based on stability criterion is proposed in the present paper. This method can stabilize chaotic systems onto a desired periodic orbit by a small time-continuous perturbation nonlinear feedback. This method does not require linearization of the system around the stabilized orbit and only an approximate location of the desired periodic orbit is required which can be automatically detected in the control process. The control can be started at any moment by choosing appropriate perturbation restriction condition. It seems that more flexibility and convenience are the main advantages of this method. The discussions on control of attitude motion of a spacecraft, Rössler system, and two coupled Duffing oscillators are given as numerical examples.

  2. Controlled crystalline structure and surface stability of cobalt nanocrystals.

    Science.gov (United States)

    Bao, Yuping; Beerman, Michael; Pakhomov, Alexandre B; Krishnan, Kannan M

    2005-04-21

    The synthesis of monodispersed 10 nm cobalt nanocrystals with controlled crystal morphology and investigation of the surface stability of these nanocrystals are described. Depending on the surfactants used, single crystalline or multiple grain nanocrystals can be reproducibly produced. The relative surface stability of these nanocrystals is analyzed using the temperature dependences of the dc magnetic susceptibility. The novel method, which allows sensitive monitoring of the surface stability, is based on the observation that, with particle oxidation, an anomalous peak appears at 8 K in zero-field-cooled magnetization measurements. It is found that the surfactant protective layer is more important for long-term stability at room temperature, while the high-temperature oxidation rate is controlled by the crystal morphology of the nanoparticles.

  3. Stability of Unfalsified Adaptive Switching Control in Noisy Environments

    NARCIS (Netherlands)

    Battistelli, Giorgio; Mosca, Edoardo; Safonov, Michael G.; Tesi, Pietro

    2010-01-01

    In recent years, unfalsified adaptive switching control has emerged as a promising technique for the control of uncertain plants only on the basis of plant I/O data. This note analyzes the input-output stability of the resulting switched system in a noisy environment, and discusses the issue of equi

  4. Locus of Control and Marital Stability: A Longitudinal Study.

    Science.gov (United States)

    Constantine, John A.; Bahr, Stephen J.

    1980-01-01

    Investigated relationship between locus of control and marital stability of young men. Factors derived from locus of control measures included leadership, personal, and fate scales. Results indicated the only significant difference was on the leadership scale between men remaining married and those who did not. (RC)

  5. Discontinuous stabilization of nonlinear systems : Quantized and switching controls

    NARCIS (Netherlands)

    Ceragioli, Francesca; De Persis, Claudio

    2007-01-01

    In this paper we consider the classical problem of stabilizing nonlinear systems in the case the control laws take values in a discrete set. First, we present a robust control approach to the problem. Then, we focus on the class of dissipative systems and rephrase classical results available for thi

  6. Biomass Combustion Control and Stabilization Using Low-Cost Sensors

    Directory of Open Access Journals (Sweden)

    Ján Piteľ

    2013-01-01

    Full Text Available The paper describes methods for biomass combustion process control and burning stabilization based on low-cost sensing of carbon monoxide emissions and oxygen concentration in the flue gas. The designed control system was tested on medium-scale biomass-fired boilers and some results are evaluated and presented in the paper.

  7. Possible role of the WDR3 gene on genome stability in thyroid cancer patients.

    Directory of Open Access Journals (Sweden)

    Wilser Andrés García-Quispes

    Full Text Available The role of the WDR3 gene on genomic instability has been evaluated in a group of 115 differentiated thyroid cancer (DTC patients. Genomic instability has been measured according to the response of peripheral blood lymphocytes to ionizing radiation (0.5 Gy. The response has been measured with the micronucleus (MN test evaluating the frequency of binucleated cells with MN (BNMN, both before and after the irradiation. No differences between genotypes, for the BNMN frequencies previous the irradiation, were observed. Nevertheless significant decreases in DNA damage after irradiation were observed in individuals carrying the variant alleles for each of the three genotyped SNPs: rs3754127 [-8.85 (-15.01 to -2.70, P<0.01]; rs3765501 [-8.98 (-15.61 to -2.36, P<0.01]; rs4658973 [-8.70 (-14.94 to -2.46, P<0.01]. These values correspond to those obtained assuming a dominant model. This study shows for the first time that WDR3 can modulate genome stability.

  8. Robust stabilization for a class of nonlinear networked control systems

    Institute of Scientific and Technical Information of China (English)

    Jinfeng GAO; Hongye SU; Xiaofu JI; Jian CHU

    2008-01-01

    The problem of robust stabilization for a class of uncertain networked control systems(NCSs)with nonlinearities satisfying a given sector condition is investigated in this paper.By introducing a new model of NCSs with parameter uncertainty,network.induced delay,nonlinearity and data packet dropout in the transmission,a strict linear matrix inequality(LMI)criterion is proposed for robust stabilization of the uncenmn nonlinear NCSs based on the Lyapunov stability theory.The maximum allowable transfer interval(MATI)can be derived by solving the feasibility problem of the corresponding LMI.Some numerical examples are provided to demonstrate the applicability of the proposed algorithm.

  9. An active interferometer-stabilization scheme with linear phase control

    DEFF Research Database (Denmark)

    Vardhan Krishnamachari, Vishnu; Andresen, Esben Ravn; Potma, Eric Olaf

    2006-01-01

    We report a simple and robust computer-based active interferometer stabilization scheme which does not require modulation of the interfering beams and relies on an error signal which is linearly related to the optical path difference. In this setup, a non-collinearly propagating reference laser...... beam stabilizes the interference output of the laser light propagating collinearly through the interferometer. This stabilization scheme enables adjustable phase control with 20 ms switching times in the range from 0.02π radians to 6π radians at 632.8 nm....

  10. Stabilization of multiple independent linear systems with control networks

    Institute of Scientific and Technical Information of China (English)

    Zhenfu BI; Fusheng WANG

    2004-01-01

    The problem of stabilizing multiple independent linear systems sharing one common network cable is presented and solved.Both the quantization and time sequencing are studied in the field of control over networks by providing the formulated stabilizing sufficient condition which illustrates the relationship between the system instability,quantization and time sequencing,and the data rate is also presented in terms of the quantization and time sequencing. A numerical example is given to illustrate the result.

  11. Adaptive Neural Network Controller for Thermogenerator Angular Velocity Stabilization System

    OpenAIRE

    2013-01-01

    The paper presents an analytical and simulation approach for the selection of activation functions for the class of neural network controllers for ship’s thermogenerator angular velocity stabilization system. Such systems can be found in many ships. A Lyapunov-like stability analysis is performed in order to obtain a weight update law. A number of simulations were performed to find the best activation function using integral error criteria and statistical T-tests.

  12. More relaxed conditions for model predictive control with guaranteed stability

    Institute of Scientific and Technical Information of China (English)

    Bin LIU; Yugeng XI

    2005-01-01

    For the model predictive controller,terminal state satisfying a certain inequality can guarantee the stability but it is somewhat conservative.In this paper,we give a more relaxed stability condition by considering the effect of the initial state.Based on that we propose an algorithm to guarantee that the closed loop system is asymptotically stable.Finally,the conclusions are verified by a simulation.

  13. Stabilizing equilibrium by linear feedback control for controlling chaos in Chen system

    Energy Technology Data Exchange (ETDEWEB)

    Costa, V A [Departamento de Ciencias Basicas, Facultad de IngenierIa (UNLP), La Plata (Argentina); Gonzalez, G A, E-mail: vacosta@ing.unlp.edu.ar, E-mail: ggonzal@fi.ub.ar [Departamento de Matematica, Facultad de Ingenieria (UBA), Buenos Aires (Argentina)

    2011-03-01

    Stabilization of a chaotic system in one of its unstable equilibrium points by applying small perturbations is studied. A two-stage control strategy based on linear feedback control is applied. Improvement of system performance is addressed by exploiting the ergodicity of the original dynamics and using Lyapunov stability results for control design. Extension to the not complete observability case is also analyzed.

  14. Stability of XIST repression in relation to genomic imprinting following global genome demethylation in a human cell line

    Energy Technology Data Exchange (ETDEWEB)

    Araújo, E.S.S. de [Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP (Brazil); Centro Internacional de Pesquisa, A.C. Camargo Cancer Center, São Paulo, SP (Brazil); Vasques, L.R. [Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP (Brazil); Stabellini, R.; Krepischi, A.C.V. [Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP (Brazil); Centro Internacional de Pesquisa, A.C. Camargo Cancer Center, São Paulo, SP (Brazil); Pereira, L.V. [Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP (Brazil)

    2014-10-17

    DNA methylation is essential in X chromosome inactivation and genomic imprinting, maintaining repression of XIST in the active X chromosome and monoallelic repression of imprinted genes. Disruption of the DNA methyltransferase genes DNMT1 and DNMT3B in the HCT116 cell line (DKO cells) leads to global DNA hypomethylation and biallelic expression of the imprinted gene IGF2 but does not lead to reactivation of XIST expression, suggesting that XIST repression is due to a more stable epigenetic mark than imprinting. To test this hypothesis, we induced acute hypomethylation in HCT116 cells by 5-aza-2′-deoxycytidine (5-aza-CdR) treatment (HCT116-5-aza-CdR) and compared that to DKO cells, evaluating DNA methylation by microarray and monitoring the expression of XIST and imprinted genes IGF2, H19, and PEG10. Whereas imprinted genes showed biallelic expression in HCT116-5-aza-CdR and DKO cells, the XIST locus was hypomethylated and weakly expressed only under acute hypomethylation conditions, indicating the importance of XIST repression in the active X to cell survival. Given that DNMT3A is the only active DNMT in DKO cells, it may be responsible for ensuring the repression of XIST in those cells. Taken together, our data suggest that XIST repression is more tightly controlled than genomic imprinting and, at least in part, is due to DNMT3A.

  15. Stability analysis of direct current control in current source rectifier

    DEFF Research Database (Denmark)

    Lu, Dapeng; Wang, Xiongfei; Blaabjerg, Frede

    2017-01-01

    Current source rectifier with high switching frequency has a great potential for improving the power efficiency and power density in ac-dc power conversion. This paper analyzes the stability of direct current control based on the time delay effect. Small signal model including dynamic behaviors...... of dc link is developed to identify the control plants of grid ac current control and dc current control. Analysis on the poles and zeros under dq frame is carried out. Base on this model, it turns out that the phase lag caused by the time delay can stabilized the grid ac current control while reduces...... the stable region for dc current control. Simulation and experimental results are presented to validate the theoretical analysis....

  16. Adaptive Dynamic Programming for Control Algorithms and Stability

    CERN Document Server

    Zhang, Huaguang; Luo, Yanhong; Wang, Ding

    2013-01-01

    There are many methods of stable controller design for nonlinear systems. In seeking to go beyond the minimum requirement of stability, Adaptive Dynamic Programming for Control approaches the challenging topic of optimal control for nonlinear systems using the tools of  adaptive dynamic programming (ADP). The range of systems treated is extensive; affine, switched, singularly perturbed and time-delay nonlinear systems are discussed as are the uses of neural networks and techniques of value and policy iteration. The text features three main aspects of ADP in which the methods proposed for stabilization and for tracking and games benefit from the incorporation of optimal control methods: • infinite-horizon control for which the difficulty of solving partial differential Hamilton–Jacobi–Bellman equations directly is overcome, and  proof provided that the iterative value function updating sequence converges to the infimum of all the value functions obtained by admissible control law sequences; • finite-...

  17. Method for rudder roll stabilization control by maintaining ship speed

    Directory of Open Access Journals (Sweden)

    LIU Zhiquan

    2017-01-01

    Full Text Available A ship navigating on the surface of the water may experience greater resistance, adversely affect-ing its speed and leading to energy loss. The added resistance of surface ships in both still water and waves are investigated, and the computation method of total speed loss is presented. An autopilot system is intro-duced to constrain the speed loss, and course keeping and rudder roll stabilization sliding mode control laws are proposed according to a compact control strategy. The two working conditions of "heading" and "heading plus anti-roll" are discussed, including roll stabilization, heading error, speed maintenance and rudder abrasion. The results show that the speed can be effectively maintained using this method, and from a commercial point of view, the fin-rudder roll stabilization control is not recommended for vessels equipped with both fins and rudders.

  18. Optimal Sliding Mode Controllers for Attitude Stabilization of Flexible Spacecraft

    Directory of Open Access Journals (Sweden)

    Chutiphon Pukdeboon

    2011-01-01

    Full Text Available The robust optimal attitude control problem for a flexible spacecraft is considered. Two optimal sliding mode control laws that ensure the exponential convergence of the attitude control system are developed. Integral sliding mode control (ISMC is applied to combine the first-order sliding mode with optimal control and is used to control quaternion-based spacecraft attitude manoeuvres with external disturbances and an uncertainty inertia matrix. For the optimal control part the state-dependent Riccati equation (SDRE and optimal Lyapunov techniques are employed to solve the infinite-time nonlinear optimal control problem. The second method of Lyapunov is used to guarantee the stability of the attitude control system under the action of the proposed control laws. An example of multiaxial attitude manoeuvres is presented and simulation results are included to verify the usefulness of the developed controllers.

  19. An Artificial Neural Network Control System for Spacecraft Attitude Stabilization

    Science.gov (United States)

    1990-06-01

    NAVAL POSTGRADUATE SCHOOL Monterey, California ’-DTIC 0 ELECT f NMARO 5 191 N S, U, THESIS B . AN ARTIFICIAL NEURAL NETWORK CONTROL SYSTEM FOR...NO. NO. NO ACCESSION NO 11. TITLE (Include Security Classification) AN ARTIFICIAL NEURAL NETWORK CONTROL SYSTEM FOR SPACECRAFT ATTITUDE STABILIZATION...obsolete a U.S. G v pi.. iim n P.. oiice! toog-eo.5s43 i Approved for public release; distribution is unlimited. AN ARTIFICIAL NEURAL NETWORK CONTROL

  20. Roles of human POLD1 and POLD3 in genome stability

    OpenAIRE

    Emanuela Tumini; Sonia Barroso; Carmen Pérez -Calero; Andrés Aguilera

    2016-01-01

    DNA replication is essential for cellular proliferation. If improperly controlled it can constitute a major source of genome instability, frequently associated with cancer and aging. POLD1 is the catalytic subunit and POLD3 is an accessory subunit of the replicative Pol ? polymerase, which also functions in DNA repair, as well as the translesion synthesis polymerase Pol ?, whose catalytic subunit is REV3L. In cells depleted of POLD1 or POLD3 we found a differential but general increase in gen...

  1. Large-scale stabilization control of input-constrained quadrotor

    Directory of Open Access Journals (Sweden)

    Jun Jiang

    2016-10-01

    Full Text Available The quadrotor has been the most popular aircraft in the last decade due to its excellent dynamics and continues to attract ever-increasing research interest. Delivering a quadrotor from a large fixed-wing aircraft is a promising application of quadrotors. In such an application, the quadrotor needs to switch from a highly unstable status, featured as large initial states, to a safe and stable flight status. This is the so-called large-scale stability control problem. In such an extreme scenario, the quadrotor is at risk of actuator saturation. This can cause the controller to update incorrectly and lead the quadrotor to spiral and crash. In this article, to safely control the quadrotor in such scenarios, the control input constraint is analyzed. The key states of a quadrotor dynamic model are selected, and a two-dimensional dynamic model is extracted based on a symmetrical body configuration. A generalized point-wise min-norm nonlinear control method is proposed based on the Lyapunov function, and large-scale stability control is hence achieved. An enhanced point-wise, min-norm control is further provided to improve the attitude control performance, with altitude performance degenerating slightly. Simulation results showed that the proposed control methods can stabilize the input-constrained quadrotor and the enhanced method can improve the performance of the quadrotor in critical states.

  2. Stability control of gate groups in deep wells

    Energy Technology Data Exchange (ETDEWEB)

    Zhi-biao Guo; Ping-ye Guo; Mao-hong Huang; Yin-gen Liu [China University of Mining & Technology, Beijing (China). School of Geotechnical Engineering

    2009-03-15

    In order to study stability control methods for a deep gate group under complex stresses, we conducted field investigations and analyses of reasons for damage in the Xuzhou coal mining district. Three reasons are proposed: deep high stress, improper roadway layout and support technology. The stability control countermeasures of the gate group consist of an intensive design technology and responding bolt-mesh-anchor truss support technology. Our research method has been applied at the -1000 m level gate group in Qishan Coal Mine. Suitable countermeasures have been tested by field monitoring. 16 refs., 9 figs.

  3. Introduction to Computational Methods for Stability and Control (COMSAC)

    Science.gov (United States)

    Hall, Robert M.; Fremaux, C. Michael; Chambers, Joseph R.

    2004-01-01

    This Symposium is intended to bring together the often distinct cultures of the Stability and Control (S&C) community and the Computational Fluid Dynamics (CFD) community. The COMSAC program is itself a new effort by NASA Langley to accelerate the application of high end CFD methodologies to the demanding job of predicting stability and control characteristics of aircraft. This talk is intended to set the stage for needing a program like COMSAC. It is not intended to give details of the program itself. The topics include: 1) S&C Challenges; 2) Aero prediction methodology; 3) CFD applications; 4) NASA COMSAC planning; 5) Objectives of symposium; and 6) Closing remarks.

  4. Stability control of gate groups in deep wells

    Institute of Scientific and Technical Information of China (English)

    GUO Zhi-biao; GUO Ping-ye; HUANG Mao-hong; LIU Yin-gen

    2009-01-01

    In order to study stability control methods for a deep gate group under complex stresses, we conducted field investiga-tions and analyses of reasons for damage in the Xuzhou mining district. Three reasons are proposed: deep high stress, improper roadway layout and support technology. The stability control countermeasures of the gate group consist of an intensive design technology and responding bolt-mesh-anchor truss support technology. Our research method has been applied at the -1000 m level gate group in Qishan Coal Mine. Suitable countermeasures have been tested by field monitoring.

  5. Experimental Investigations of Generalized Predictive Control for Tiltrotor Stability Augmentation

    Science.gov (United States)

    Nixon, Mark W.; Langston, Chester W.; Singleton, Jeffrey D.; Piatak, David J.; Kvaternik, Raymond G.; Bennett, Richard L.; Brown, Ross K.

    2001-01-01

    A team of researchers from the Army Research Laboratory, NASA Langley Research Center (LaRC), and Bell Helicopter-Textron, Inc. have completed hover-cell and wind-tunnel testing of a 1/5-size aeroelastically-scaled tiltrotor model using a new active control system for stability augmentation. The active system is based on a generalized predictive control (GPC) algorithm originally developed at NASA LaRC in 1997 for un-known disturbance rejection. Results of these investigations show that GPC combined with an active swashplate can significantly augment the damping and stability of tiltrotors in both hover and high-speed flight.

  6. A switched system approach to stabilization f networked control systems

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A switched system approach is proposed to model networked control systems (NCSs) with communication constraints. This enables us to apply the rich theory of switched systems to analyzing such NCSs. Sufficient conditions are presented on the stabilization of NCSs. Stabilizing state/output feedback controllers can be constructed by using the feasible solutions of some linear matrix inequalities (LMIs). The merit of our proposed approach is that the behavior of the NCSs can be studied by considering switched system without augmenting the system. A simulation example is worked out to illustrate the effectiveness of the proposed approach.

  7. Stability Aspects in One-Cycle Controlled Buck Converters

    Directory of Open Access Journals (Sweden)

    GURBINA, M.

    2014-02-01

    Full Text Available The paper aims to investigate issues related to one cycle controlled buck converters stability, in the situation when the integration capacitor discharging is performed through a non-zero value resistor, as it happens in practice. It is known that in this case the exponential discharge makes capacitor voltage theoretically never reach zero. Under these conditions, instability phenomena are expected when the discharge time is short, that is at high duty cycles. The stability condition is analytically derived with respect to the control voltage. It is shown that instability occurs with period doubling leading to a half switching frequency subharmonic. Computer simulations confirm the validity of theoretical considerations.

  8. Stabilization of third-order bilinear systems using constant controls

    Directory of Open Access Journals (Sweden)

    A. E. Golubev

    2014-01-01

    Full Text Available This paper deals with the zero equilibrium stabilization for dynamical systems that have control input singularities. A dynamical system with scalar control input is called nonregular if the coefficient of input becomes null on a subset of the phase space that contains the origin. One of the classes of nonregular dynamical systems is represented by bilinear systems. In case of second-order bilinear systems the necessary and sufficient conditions for the zero equilibrium stabilizability are known in the literature. However, in general case the stabilization problem in the presence of control input singularities has not been solved yet.In this note we solve the problem of the zero equilibrium stabilization for the third-order bilinear dynamical systems given in a canonical form. The solution is found in the class of constant controls. The necessary and sufficient conditions are obtained for the zero equilibrium stabilizability of the bilinear systems in question.The dependence of the zero equilibrium stabilizability on system parameter values is analyzed. The general criteria of stabilizability by means of constant controls are given for the bilinear systems in question. In case when all the system parameters have nonzero values the necessary and sufficient stabilizability conditions are proved. The case when some of the parameters are equal to zero is also considered.Further research can be focused on extending the obtained results to a higher-order case of bilinear and affine dynamical systems. The solution of the considered stabilization problem should also be found not only within constant controls but also in a class of state feedbacks, particularly, in the case when stabilizing constant control does not exist.One of the potential application areas for the obtained theoretical results is automatic control of technical plants like unmanned aerial vehicles and mobile robots.

  9. The Csr system regulates genome-wide mRNA stability and transcription and thus gene expression in Escherichia coli

    OpenAIRE

    Thomas Esquerré; Marie Bouvier; Catherine Turlan; Carpousis, Agamemnon J.; Laurence Girbal; Muriel Cocaign-Bousquet

    2016-01-01

    Bacterial adaptation requires large-scale regulation of gene expression. We have performed a genome-wide analysis of the Csr system, which regulates many important cellular functions. The Csr system is involved in post-transcriptional regulation, but a role in transcriptional regulation has also been suggested. Two proteins, an RNA-binding protein CsrA and an atypical signaling protein CsrD, participate in the Csr system. Genome-wide transcript stabilities and levels were compared in wildtype...

  10. The interplay between DNA damage response and RNA processing: the unexpected role of splicing factors as gatekeepers of genome stability

    Directory of Open Access Journals (Sweden)

    Chiara eNaro

    2015-04-01

    Full Text Available Genome integrity is constantly threatened by endogenous and exogenous factors. However its preservation is ensured by a network of pathways that prevent and/or repair the lesion, which constitute the DNA damage response (DDR. Expression of the key proteins involved in the DDR is controlled by numerous post-transcriptional mechanisms, among which pre-mRNA splicing stands out. Intriguingly, several splicing factors have been recently shown to play direct functions in DNA damage prevention and repair, which go beyond their expected splicing activity. At the same time, evidence is emerging that DNA repair proteins (DRPs can actively sustain the DDR by acting as post-transcriptional regulator of gene expression, in addition to their well-known role in the mechanisms of signaling and repair of the lesion. Herein, we will review these non-canonical functions of both splicing factors and DRPs, which suggest the existence of a tight interplay between splicing regulation and canonical DNA safeguard mechanisms ensuring genome stability.

  11. A genome-scale CRISPR-Cas9 screening method for protein stability reveals novel regulators of Cdc25A.

    Science.gov (United States)

    Wu, Yuanzhong; Zhou, Liwen; Wang, Xin; Lu, Jinping; Zhang, Ruhua; Liang, Xiaoting; Wang, Li; Deng, Wuguo; Zeng, Yi-Xin; Huang, Haojie; Kang, Tiebang

    2016-01-01

    The regulation of stability is particularly crucial for unstable proteins in cells. However, a convenient and unbiased method of identifying regulators of protein stability remains to be developed. Recently, a genome-scale CRISPR-Cas9 library has been established as a genetic tool to mediate loss-of-function screening. Here, we developed a protein stability regulators screening assay (Pro-SRSA) by combining the whole-genome CRISPR-Cas9 library with a dual-fluorescence-based protein stability reporter and high-throughput sequencing to screen for regulators of protein stability. Using Cdc25A as an example, Cul4B-DDB1(DCAF8) was identified as a new E3 ligase for Cdc25A. Moreover, the acetylation of Cdc25A at lysine 150, which was acetylated by p300/CBP and deacetylated by HDAC3, prevented the ubiquitin-mediated degradation of Cdc25A by the proteasome. This is the first study to report that acetylation, as a novel posttranslational modification, modulates Cdc25A stability, and we suggest that this unbiased CRISPR-Cas9 screening method at the genome scale may be widely used to globally identify regulators of protein stability.

  12. Stabilization of neutral-type indirect control systems to absolute stability state

    NARCIS (Netherlands)

    Shatyrko, A.; Van Nooyen, R.R.P.; Kolechkina, A.; Khusainov, D.

    2015-01-01

    This paper provides sufficient conditions for absolute stability of an indirect control Lur’e problem of neutral type. The conditions are derived using a Lyapunov-Krasovskii functional and are given in terms of a system of matrix algebraic inequalities. From these matrix inequalities a sufficient co

  13. Strong stabilization servo controller with optimization of performance criteria.

    Science.gov (United States)

    Sarjaš, Andrej; Svečko, Rajko; Chowdhury, Amor

    2011-07-01

    Synthesis of a simple robust controller with a pole placement technique and a H(∞) metrics is the method used for control of a servo mechanism with BLDC and BDC electric motors. The method includes solving a polynomial equation on the basis of the chosen characteristic polynomial using the Manabe standard polynomial form and parametric solutions. Parametric solutions are introduced directly into the structure of the servo controller. On the basis of the chosen parametric solutions the robustness of a closed-loop system is assessed through uncertainty models and assessment of the norm ‖•‖(∞). The design procedure and the optimization are performed with a genetic algorithm differential evolution - DE. The DE optimization method determines a suboptimal solution throughout the optimization on the basis of a spectrally square polynomial and Šiljak's absolute stability test. The stability of the designed controller during the optimization is being checked with Lipatov's stability condition. Both utilized approaches: Šiljak's test and Lipatov's condition, check the robustness and stability characteristics on the basis of the polynomial's coefficients, and are very convenient for automated design of closed-loop control and for application in optimization algorithms such as DE.

  14. Temperature sensitive influenza A virus genome replication results from low thermal stability of polymerase-cRNA complexes

    Directory of Open Access Journals (Sweden)

    Tiley Laurence S

    2006-08-01

    Full Text Available Abstract Background The RNA-dependent RNA polymerase of Influenza A virus is a determinant of viral pathogenicity and host range that is responsible for transcribing and replicating the negative sense segmented viral genome (vRNA. Transcription produces capped and polyadenylated mRNAs whereas genome replication involves the synthesis of an alternative plus-sense transcript (cRNA with unmodified termini that is copied back to vRNA. Viral mRNA transcription predominates at early stages of viral infection, while later, negative sense genome replication is favoured. However, the "switch" that regulates the transition from transcription to replication is poorly understood. Results We show that temperature strongly affects the balance between plus and minus-sense RNA synthesis with high temperature causing a large decrease in vRNA accumulation, a moderate decrease in cRNA levels but (depending on genome segment either increased or unchanged levels of mRNA. We found no evidence implicating cellular heat shock protein activity in this effect despite the known association of hsp70 and hsp90 with viral polymerase components. Temperature-shift experiments indicated that polymerase synthesised at 41°C maintained transcriptional activity even though genome replication failed. Reduced polymerase association with viral RNA was seen in vivo and in confirmation of this, in vitro binding assays showed that temperature increased the rate of dissociation of polymerase from both positive and negative sense promoters. However, the interaction of polymerase with the cRNA promoter was particularly heat labile, showing rapid dissociation even at 37°C. This suggested that vRNA synthesis fails at elevated temperatures because the polymerase does not bind the promoter. In support of this hypothesis, a mutant cRNA promoter with vRNA-like sequence elements supported vRNA synthesis at higher temperatures than the wild-type promoter. Conclusion The differential stability of

  15. Power System Stability Enhancement Using Unified Power Flow Controller

    Directory of Open Access Journals (Sweden)

    Prechanon Kumkratug

    2010-01-01

    Full Text Available Problem statement: The enhancement of transient stability of the power system is one of the most challenging research areas in power engineer. Approach: This study presents the method to enhance transient stability of power system by Unified Power Flow Controller (UPFC. The mathematical model of power system equipped with a UPFC is systematically derived. The parameters of UPFC are modeled into power flow equation and thus it is used to determine control strategy. The swing curves of the three phase faulted power system without and with a UPFC are tested and compared in various cases. Results: The swing curve of system without a UPFC gets increases monotonically and thus the system can be considered as unstable whereas the swing curves of system with a UPFC can return to stable equilibrium point. Conclusion: From the simulation results, the UPFC can enhance transient stability of power system.

  16. The role of autophagy in genome stability through suppression of abnormal mitosis under starvation.

    Directory of Open Access Journals (Sweden)

    Aiko Matsui

    Full Text Available The coordination of subcellular processes during adaptation to environmental change is a key feature of biological systems. Starvation of essential nutrients slows cell cycling and ultimately causes G1 arrest, and nitrogen starvation delays G2/M progression. Here, we show that budding yeast cells can be efficiently returned to the G1 phase under starvation conditions in an autophagy-dependent manner. Starvation attenuates TORC1 activity, causing a G2/M delay in a Swe1-dependent checkpoint mechanism, and starvation-induced autophagy assists in the recovery from a G2/M delay by supplying amino acids required for cell growth. Persistent delay of the cell cycle by a deficiency in autophagy causes aberrant nuclear division without sufficient cell growth, leading to an increased frequency in aneuploidy after refeeding the nitrogen source. Our data establish the role of autophagy in genome stability through modulation of cell division under conditions that repress cell growth.

  17. Floquet stability analysis of Ott Grebogi Yorke and difference control

    Science.gov (United States)

    Claussen, Jens Christian

    2008-06-01

    Stabilization of instable periodic orbits of nonlinear dynamical systems has been a widely explored field theoretically and in applications. The techniques can be grouped into time-continuous control schemes based on Pyragas, and the two Poincaré-based chaos control schemes, Ott-Gebogi-Yorke (OGY) and difference control. Here, a new stability analysis of these two Poincaré-based chaos control schemes is given by means of the Floquet theory. This approach allows to calculate exactly the stability restrictions occurring for small measurement delays and for an impulse length shorter than the length of the orbit. This is of practical experimental relevance; to avoid a selection of the relative impulse length by trial and error, it is advised to investigate whether the used control scheme itself shows systematic limitations on the choice of the impulse length. To investigate this point, a Floquet analysis is performed. For OGY control the influence of the impulse length is marginal. As an unexpected result, difference control fails when the impulse length is taken longer than a maximal value that is approximately one half of the orbit length for small Ljapunov numbers and decreases with the Ljapunov number.

  18. Gait Planning and Stability Control of a Quadruped Robot

    Directory of Open Access Journals (Sweden)

    Junmin Li

    2016-01-01

    Full Text Available In order to realize smooth gait planning and stability control of a quadruped robot, a new controller algorithm based on CPG-ZMP (central pattern generator-zero moment point is put forward in this paper. To generate smooth gait and shorten the adjusting time of the model oscillation system, a new CPG model controller and its gait switching strategy based on Wilson-Cowan model are presented in the paper. The control signals of knee-hip joints are obtained by the improved multi-DOF reduced order control theory. To realize stability control, the adaptive speed adjustment and gait switch are completed by the real-time computing of ZMP. Experiment results show that the quadruped robot’s gaits are efficiently generated and the gait switch is smooth in the CPG control algorithm. Meanwhile, the stability of robot’s movement is improved greatly with the CPG-ZMP algorithm. The algorithm in this paper has good practicability, which lays a foundation for the production of the robot prototype.

  19. Genomic control of neuronal demographics in the retina.

    Science.gov (United States)

    Reese, Benjamin E; Keeley, Patrick W

    2016-11-01

    The mature retinal architecture is composed of various types of neuron, each population differing in size and constrained to particular layers, wherein the cells achieve a characteristic patterning in their local organization. These demographic features of retinal nerve cell populations are each complex traits controlled by multiple genes affecting different processes during development, and their genetic determinants can be dissected by correlating variation in these traits with their genomic architecture across recombinant-inbred mouse strains. Using such a resource, we consider how the variation in the numbers of twelve different types of retinal neuron are independent of one another, including those sharing transcriptional regulation as well as those that are synaptically-connected, each mapping to distinct genomic loci. Using the populations of two retinal interneurons, the horizontal cells and the cholinergic amacrine cells, we present in further detail examples where the variation in neuronal number, as well as the variation in mosaic patterning or in laminar positioning, each maps to discrete genomic loci where allelic variants modulating these features must be present. At those loci, we identify candidate genes which, when rendered non-functional, alter those very demographic properties, and in turn, we identify candidate coding or regulatory variants that alter protein structure or gene expression, respectively, being prospective contributors to the variation in phenotype. This forward-genetic approach provides an alternative means for dissecting the molecular genetic control of neuronal population dynamics, with each genomic locus serving as a causal anchor from which we may ultimately understand the developmental principles responsible for the control of those traits.

  20. Identification of candidate genome regions controlling disease resistance in Arachis

    Directory of Open Access Journals (Sweden)

    Pike Jodie

    2009-08-01

    Full Text Available Abstract Background Worldwide, diseases are important reducers of peanut (Arachis hypogaea yield. Sources of resistance against many diseases are available in cultivated peanut genotypes, although often not in farmer preferred varieties. Wild species generally harbor greater levels of resistance and even apparent immunity, although the linkage of agronomically un-adapted wild alleles with wild disease resistance genes is inevitable. Marker-assisted selection has the potential to facilitate the combination of both cultivated and wild resistance loci with agronomically adapted alleles. However, in peanut there is an almost complete lack of knowledge of the regions of the Arachis genome that control disease resistance. Results In this work we identified candidate genome regions that control disease resistance. For this we placed candidate disease resistance genes and QTLs against late leaf spot disease on the genetic map of the A-genome of Arachis, which is based on microsatellite markers and legume anchor markers. These marker types are transferable within the genus Arachis and to other legumes respectively, enabling this map to be aligned to other Arachis maps and to maps of other legume crops including those with sequenced genomes. In total, 34 sequence-confirmed candidate disease resistance genes and five QTLs were mapped. Conclusion Candidate genes and QTLs were distributed on all linkage groups except for the smallest, but the distribution was not even. Groupings of candidate genes and QTLs for late leaf spot resistance were apparent on the upper region of linkage group 4 and the lower region of linkage group 2, indicating that these regions are likely to control disease resistance.

  1. Stabilization of rotational motion with application to spacecraft attitude control

    DEFF Research Database (Denmark)

    Wisniewski, Rafal

    2000-01-01

    on a Riemannian manifold. The Lyapnov stability theory is adapted and reformulated to fit to the new framework of Riemannian manifolds. Toillustrate the results a spacecraft attitude control problem is considered. Firstly, a global canonical representation for the spacecraft motion is found, then three spacecraft...

  2. Stabilizing control for power converters connected to transmission lines

    NARCIS (Netherlands)

    Zainea, Marius; Schaft, Arjan van der; Buisson, Jean

    2007-01-01

    This paper proposes a switching control strategy for the set-point stabilization of a power converter connected via a transmission line to a resistive load. The strategy employs a Lyapunov function that is directly based on energy considerations of the power converter, as well as of the transmission

  3. The longitudinal controls fixed static stability of tailless aircraft

    OpenAIRE

    de Castro, Helena V.

    2000-01-01

    This paper describes the development of a simple theory of the longitudinal controls fixed static stability of tailless aeroplanes. The classical theory, as developed for the conventional aircraft, is modified to accommodate the particular features of the tailless aeroplanes. The theory was then applied to a particular blended-wing-body tailless civil transport aircraft, BWB-98. Cranfield University

  4. Selection and control of limb posture for stability

    NARCIS (Netherlands)

    Franklin, D.W.; Selen, L.P.J.; Franklin, S.; Wolpert, D.M.

    2013-01-01

    Impedance control can be used to stabilize the limb against both instability and unpredictable perturbations. Limb posture influences motor noise, energy usage and limb impedance as well as their interaction. Here we examine whether subjects use limb posture as part of a mechanism to regulate limb s

  5. Microgrid Stability Controller Based on Adaptive Robust Total SMC

    DEFF Research Database (Denmark)

    Su, Xiaoling; Han, Minxiao; Guerrero, Josep M.

    2015-01-01

    and mathematical models of the MSC indicate that the system is inherently nonlinear and time-variable. Therefore, this paper proposes an adaptive robust total sliding-mode control (ARTSMC) system for the MSC. It is proved that the ARTSMC system is insensitive to parametric uncertainties and external disturbances......This paper presents a microgrid stability controller (MSC) in order to provide existing DGs the additional functionality of working in islanding mode without changing their control strategies in grid-connected mode and to enhance the stability of the microgrid. Microgrid operating characteristics....... The MSC provides fast dynamic response and robustness to the microgrid. When the system is operating in grid-connected mode, it is able to improve the controllability of the exchanged power between the microgrid and the utility grid, while smoothing DG’s output power. When the microgrid is operating...

  6. Stability Analysis and Design of Impulsive Control Lorenz Systems Family

    Institute of Scientific and Technical Information of China (English)

    YU Yong-Bin; ZHANG Hong-Bin; ZHANG Feng-Li; YU Jue-Bang; LIAO Xiao-Feng

    2009-01-01

    Lorenz systems family unifying Lorenz system, Chen system and Lu system is a typical chaotic family.In this paper, we consider impulsive control Lorenz chaotic systems family with time-varying impulse intervals. By establishing an effective tool of a set of inequalities, we analyze the asymptotic stability of impulsive control Lorenz systems family and obtain some new less conservative conditions. Based on the stability analysis, we design a novel impulsive controller with time-varying impulse intervals. Illustrative examples are provided to show the feasibility and effectiveness of our method. The obtained results not only can be used to design impulsive control for Lorenz systems family, but also can be extended to other chaotic systems.

  7. Glycemic control and implant stabilization in type 2 diabetes mellitus.

    Science.gov (United States)

    Oates, T W; Dowell, S; Robinson, M; McMahan, C A

    2009-04-01

    Diabetes mellitus is considered a relative contra-indication for implant therapy. However, the effect of glycemic level on implant integration in persons with diabetes remains poorly understood. The hypothesis of this research was that poor glycemic control is directly related to short-term-impairment implant stabilization. This prospective clinical study evaluated 10 non-diabetic individuals (12 implants) and 20 persons with type 2 diabetes (30 implants). Glycated hemoglobin (HbA1c) levels ranged from 4.7-12.6%. Implant stability was assessed by resonance frequency analysis over 4 months following placement. Minimum stability levels were observed 2-6 weeks following placement for all 42 implants. Persons with HbA1c > or = 8.1% had a greater maximum decrease in stability from baseline and required a longer time for healing, as indicated by return of stability level to baseline. This study demonstrates alterations in implant stability consistent with impaired implant integration for persons with type 2 diabetes mellitus in direct relation to hyperglycemic conditions.

  8. Translational Control of the HIV Unspliced Genomic RNA

    Directory of Open Access Journals (Sweden)

    Bárbara Rojas-Araya

    2015-08-01

    Full Text Available Post-transcriptional control in both HIV-1 and HIV-2 is a highly regulated process that commences in the nucleus of the host infected cell and finishes by the expression of viral proteins in the cytoplasm. Expression of the unspliced genomic RNA is particularly controlled at the level of RNA splicing, export, and translation. It appears increasingly obvious that all these steps are interconnected and they result in the building of a viral ribonucleoprotein complex (RNP that must be efficiently translated in the cytosolic compartment. This review summarizes our knowledge about the genesis, localization, and expression of this viral RNP.

  9. RAG2’s Acidic Hinge Restricts Repair-Pathway Choice and Promotes Genomic Stability

    Directory of Open Access Journals (Sweden)

    Marc A. Coussens

    2013-09-01

    Full Text Available V(DJ recombination-associated DNA double-strand breaks (DSBs are normally repaired by the high-fidelity classical nonhomologous end-joining (cNHEJ machinery. Previous studies implicated the recombination-activating gene (RAG/DNA postcleavage complex (PCC in regulating pathway choice by preventing access to inappropriate repair mechanisms such as homologous recombination (HR and alternative NHEJ (aNHEJ. Here, we report that RAG2’s “acidic hinge,” previously of unknown function, is critical for several key steps. Mutations that reduce the hinge’s negative charge destabilize the PCC, disrupt pathway choice, permit repair of RAG-mediated DSBs by the translocation-prone aNHEJ machinery, and reduce genomic stability in developing lymphocytes. Structural predictions and experimental results support our hypothesis that reduced flexibility of the hinge underlies these outcomes. Furthermore, sequence variants present in the human population reduce the hinge’s negative charge, permit aNHEJ, and diminish genomic integrity.

  10. Human single-stranded DNA binding proteins: guardians of genome stability

    Institute of Scientific and Technical Information of China (English)

    Yuanzhong Wu; Jinping Lu; Tiebang Kang

    2016-01-01

    Single-stranded DNA-binding proteins (SSBs) are essential for maintaining the integrity of the genome in all organisms.All processes related to DNA,such as replication,excision,repair,and recombination,require the participation of SSBs whose oligonucleotideaoligosaccharide-binding (OB)-fold domain is responsible for the interaction with single-stranded DNA (ssDNA).For a long time,the heterotrimeric replication protein A (RPA) complex was believed to be the only nuclear SSB in eukanyotes to participate in ssDNA processing,while mitochondrial SSBs that are consewed with prokaryotic SSBs were shown to be essential for maintaining genome stability in eukaryotic mitochondria.In recent years,two new proteins,hSSB1 and hSSB2 (human SSBs 1/2),were identified and have better sequence similarity to bacterial and archaeal SSBs than RPA.This review summarizes the current understanding of these human SSBs in DNA damage repair and in cell-cycle checkpoint activation following DNA damage,as well as their relationships with cancer.

  11. DNA replication factor C1 mediates genomic stability and transcriptional gene silencing in Arabidopsis

    KAUST Repository

    Liu, Qian

    2010-07-01

    Genetic screening identified a suppressor of ros1-1, a mutant of REPRESSOR OF SILENCING1 (ROS1; encoding a DNA demethylation protein). The suppressor is a mutation in the gene encoding the largest subunit of replication factor C (RFC1). This mutation of RFC1 reactivates the unlinked 35S-NPTII transgene, which is silenced in ros1 and also increases expression of the pericentromeric Athila retrotransposons named transcriptional silent information in a DNA methylationindependent manner. rfc1 is more sensitive than the wild type to the DNA-damaging agent methylmethane sulphonate and to the DNA inter- and intra- cross-linking agent cisplatin. The rfc1 mutant constitutively expresses the G2/M-specific cyclin CycB1;1 and other DNA repair-related genes. Treatment with DNA-damaging agents mimics the rfc1 mutation in releasing the silenced 35S-NPTII, suggesting that spontaneously induced genomic instability caused by the rfc1 mutation might partially contribute to the released transcriptional gene silencing (TGS). The frequency of somatic homologous recombination is significantly increased in the rfc1 mutant. Interestingly, ros1 mutants show increased telomere length, but rfc1 mutants show decreased telomere length and reduced expression of telomerase. Our results suggest that RFC1 helps mediate genomic stability and TGS in Arabidopsis thaliana. © 2010 American Society of Plant Biologists.

  12. Thermal stabilization of a microring modulator using feedback control.

    Science.gov (United States)

    Padmaraju, Kishore; Chan, Johnnie; Chen, Long; Lipson, Michal; Bergman, Keren

    2012-12-17

    We describe and demonstrate the use of a feedback control system to thermally stabilize a silicon microring modulator subjected to a thermally volatile environment. Furthermore, we establish power monitoring as an effective and appropriate mechanism to infer the temperature drift of a microring modulator. Our demonstration shows that a high-performance silicon microring-based device, normally inoperable in thermally volatile environments, can maintain error-free performance when a feedback control system is implemented.

  13. Control and stability problems of remote orbital capture

    Science.gov (United States)

    Kaplan, M. H.; Nadkarni, A. A.

    1977-01-01

    Certain space shuttle missions may require retrieval of passive spinning and precessing satellites. One proposed means of retrieval utilizes a free-flying teleoperator launched from the shuttle. A study of misalignment, stability, and certain control aspects during capture of an object is reported here. The approach used is to model the dynamics by a Lagrangian formulation and apply torque components to dissipate motion. Differential angular rates between teleoperator and object are assumed, and control responses after capture are reviewed.

  14. Stability analysis of fixed points via chaos control.

    Science.gov (United States)

    Locher, M.; Johnson, G. A.; Hunt, E. R.

    1997-12-01

    This paper reviews recent advances in the application of chaos control techniques to the stability analysis of two-dimensional dynamical systems. We demonstrate how the system's response to one or multiple feedback controllers can be utilized to calculate the characteristic multipliers associated with an unstable periodic orbit. The experimental results, obtained for a single and two coupled diode resonators, agree well with the presented theory. (c) 1997 American Institute of Physics.

  15. Stability and optimal parameters for continuous feedback chaos control.

    Science.gov (United States)

    Kouomou, Y Chembo; Woafo, P

    2002-09-01

    We investigate the conditions under which an optimal continuous feedback control can be achieved. Chaotic oscillations in the single-well Duffing model, with either a positive or a negative nonlinear stiffness term, are tuned to their related Ritz approximation. The Floquet theory enables the stability analysis of the control. Critical values of the feedback control coefficient fulfilling the optimization criteria are derived. The influence of the chosen target orbit, of the feedback coefficient, and of the onset time of control on its duration is discussed. The analytic approach is confirmed by numerical simulations.

  16. Certifiable higher order sliding mode control: Practical stability margins approach

    Science.gov (United States)

    Panathula, Chandrasekhara Bharath

    The Higher Order Sliding Mode (HOSM) controllers are well known for their robustness/insensitivity to bounded perturbations and for handling any given arbitrary relative degree system. The HOSM controller is to be certified for robustness to unmodeled dynamics, before deploying the controller for practical applications. Phase Margin (PM) and Gain Margin ( GM) are the classical characteristics used in linear systems to quantify the linear controller robustness to unmodeled dynamics, and certain values of these margins are required to certify the controller. These conventional margins (PM and GM) are extended to Practical Stability Phase Margin (PSPM) and Practical Stability Gain Margin (PSGM) in this dissertation, and are used to quantify the HOSM control robustness to unmodeled dynamics, presiding the tool to close the gap for HOSM control certification. The proposed robustness metrics ( PSPM and PSGM) are identified by developing tools/algorithms based on Describing Function-Harmonic Balance method. In order for the HOSM controller to achieve the prescribed values on robustness metrics ( PSPM and PSGM), the HOSM controller is cascaded with a linear compensator. A case study of the application of the proposed metrics (PSPM and PSGM) for the certification of F-16 aircraft HOSM attitude control robustness to cascade unmodeled dynamics is presented. In addition, several simulation examples are presented to verify and to validate the proposed methodology.

  17. DNA damage checkpoint kinase ATM regulates germination and maintains genome stability in seeds.

    Science.gov (United States)

    Waterworth, Wanda M; Footitt, Steven; Bray, Clifford M; Finch-Savage, William E; West, Christopher E

    2016-08-23

    Genome integrity is crucial for cellular survival and the faithful transmission of genetic information. The eukaryotic cellular response to DNA damage is orchestrated by the DNA damage checkpoint kinases ATAXIA TELANGIECTASIA MUTATED (ATM) and ATM AND RAD3-RELATED (ATR). Here we identify important physiological roles for these sensor kinases in control of seed germination. We demonstrate that double-strand breaks (DSBs) are rate-limiting for germination. We identify that desiccation tolerant seeds exhibit a striking transcriptional DSB damage response during germination, indicative of high levels of genotoxic stress, which is induced following maturation drying and quiescence. Mutant atr and atm seeds are highly resistant to aging, establishing ATM and ATR as determinants of seed viability. In response to aging, ATM delays germination, whereas atm mutant seeds germinate with extensive chromosomal abnormalities. This identifies ATM as a major factor that controls germination in aged seeds, integrating progression through germination with surveillance of genome integrity. Mechanistically, ATM functions through control of DNA replication in imbibing seeds. ATM signaling is mediated by transcriptional control of the cell cycle inhibitor SIAMESE-RELATED 5, an essential factor required for the aging-induced delay to germination. In the soil seed bank, seeds exhibit increased transcript levels of ATM and ATR, with changes in dormancy and germination potential modulated by environmental signals, including temperature and soil moisture. Collectively, our findings reveal physiological functions for these sensor kinases in linking genome integrity to germination, thereby influencing seed quality, crucial for plant survival in the natural environment and sustainable crop production.

  18. The electric power engineering handbook power system stability and control

    CERN Document Server

    Grisby, Leonard L

    2012-01-01

    With contributions from worldwide leaders in the field, Power System Stability and Control, Third Edition (part of the five-volume set, The Electric Power Engineering Handbook) updates coverage of recent developments and rapid technological growth in essential aspects of power systems. Edited by L.L. Grigsby, a respected and accomplished authority in power engineering, and section editors Miroslav Begovic, Prabha Kundur, and Bruce Wollenberg, this reference presents substantially new and revised content. Topics covered include: * Power System Protection * Power System Dynamics and Stability *

  19. Stability Boundaries for Offshore Wind Park Distributed Voltage Control

    DEFF Research Database (Denmark)

    Gryning, Mikkel P.S.; Wu, Qiuwei; Kocewiak, Lukasz;

    2016-01-01

    In order to identify mechanisms causing slow reactive power oscillations observed in an existing offshore wind power plant, and be able to avoid similar events in the future, voltage control is studied in this paper for a plant with a static synchronous compensator, type-4 wind turbines and a park...... pilot control. Using data from the actual wind power plant, all stabilizing subsystem voltage proportional-integral controller parameters are first characterized based on their Hurwitz signature. Inner loop current control is then designed using Internal Mode Control principles, and guidelines for feed...... forward filter design are given to obtain required disturbance rejection properties. The paper contributes by providing analytical relations between power plant control, droop, sampling time, electrical parameters and voltage control characteristics, and by assessing frequencies and damping of reactive...

  20. Transient stability improvement by nonlinear controllers based on tracking

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez, Juan M. [Centro de Investigacion y Estudios Avanzados, Guadalajara, Mexico. Av. Cientifica 1145. Col. El Bajio. Zapopan, Jal. 45015 (Mexico); Arroyave, Felipe Valencia; Correa Gutierrez, Rosa Elvira [Universidad Nacional de Colombia, Sede Medellin. Facultad de Minas, Escuela de Mecatronica (Colombia)

    2011-02-15

    This paper deals with the control problem in multi-machine electric power systems, which represent complex great scale nonlinear systems. Thus, the controller design is a challenging problem. These systems are subjected to different perturbations, such as short circuits, connection and/or disconnection of loads, lines, or generators. Then, the utilization of controllers which guarantee good performance under those perturbations is required in order to provide electrical energy to the loads with admissible stability margins. The proposed controllers are based on a systematic strategy, which calculate nonlinear controllers for generating units in a power plant, both for voltage and velocity regulation. The formulation allows designing controllers in a multi-machine power system without intricate calculations. Results on a power system of the open research indicate the proposition's suitability. The problem is formulated as a tracking problem. The designed controllers may be implemented in any electric power system. (author)

  1. Moving Constraints as Stabilizing Controls in Classical Mechanics

    Science.gov (United States)

    Bressan, Alberto; Rampazzo, Franco

    2010-04-01

    The paper analyzes a Lagrangian system which is controlled by directly assigning some of the coordinates as functions of time, by means of frictionless constraints. In a natural system of coordinates, the equations of motion contain terms which are linear or quadratic with respect to time derivatives of the control functions. After reviewing the basic equations, we explain the significance of the quadratic terms related to geodesics orthogonal to a given foliation. We then study the problem of stabilization of the system to a given point by means of oscillating controls. This problem is first reduced to theweak stability for a related convex-valued differential inclusion, then studied by Lyapunov functions methods. In the last sections, we illustrate the results by means of various mechanical examples.

  2. Moving constraints as stabilizing controls in classical mechanics

    CERN Document Server

    Bressan, A

    2008-01-01

    The paper analyzes a Lagrangian system which is controlled by directly assigning some of the coordinates as functions of time, by means of frictionless constraints. In a natural system of coordinates, the equations of motions contain terms which are linear or quadratic w.r.t.time derivatives of the control functions. After reviewing the basic equations, we explain the significance of the quadratic terms, related to geodesics orthogonal to a given foliation. We then study the problem of stabilization of the system to a given point, by means of oscillating controls. This problem is first reduced to the weak stability for a related convex-valued differential inclusion, then studied by Lyapunov functions methods. In the last sections, we illustrate the results by means of various mechanical examples.

  3. Study on modeling of vehicle dynamic stability and control technique

    Institute of Scientific and Technical Information of China (English)

    GAO Yun-ting; LI Pan-feng

    2012-01-01

    In order to solve the problem of enhancing the vehicle driving stability and safety,which has been the hot question researched by scientific and engineering in the vehicle industry,the new control method was investigated.After the analysis of tire moving characteristics and the vehicle stress analysis,the tire model based on the extension pacejka magic formula which combined longitudinal motion and lateral motion was developed and a nonlinear vehicle dynamical stability model with seven freedoms was made.A new model reference adaptive control project which made the slip angle and yaw rate of vehicle body as the output and feedback variable in adjusting the torque of vehicle body to control the vehicle stability was designed.A simulation model was also built in Matlab/Simulink to evaluate this control project.It was made up of many mathematical subsystem models mainly including the tire model module,the yaw moment calculation module,the center of mass parameter calculation module,tire parameter calculation module of multiple and so forth.The severe lane change simulation result shows that this vehicle model and the model reference adaptive control method have an excellent performance.

  4. Super DNAging-New insights into DNA integrity, genome stability and telomeres in the oldest old.

    Science.gov (United States)

    Franzke, Bernhard; Neubauer, Oliver; Wagner, Karl-Heinz

    2015-01-01

    Reductions in DNA integrity, genome stability, and telomere length are strongly associated with the aging process, age-related diseases as well as the age-related loss of muscle mass. However, in people reaching an age far beyond their statistical life expectancy the prevalence of diseases, such as cancer, cardiovascular disease, diabetes or dementia, is much lower compared to "averagely" aged humans. These inverse observations in nonagenarians (90-99 years), centenarians (100-109 years) and super-centenarians (110 years and older) require a closer look into dynamics underlying DNA damage within the oldest old of our society. Available data indicate improved DNA repair and antioxidant defense mechanisms in "super old" humans, which are comparable with much younger cohorts. Partly as a result of these enhanced endogenous repair and protective mechanisms, the oldest old humans appear to cope better with risk factors for DNA damage over their lifetime compared to subjects whose lifespan coincides with the statistical life expectancy. This model is supported by study results demonstrating superior chromosomal stability, telomere dynamics and DNA integrity in "successful agers". There is also compelling evidence suggesting that life-style related factors including regular physical activity, a well-balanced diet and minimized psycho-social stress can reduce DNA damage and improve chromosomal stability. The most conclusive picture that emerges from reviewing the literature is that reaching "super old" age appears to be primarily determined by hereditary/genetic factors, while a healthy lifestyle additionally contributes to achieving the individual maximum lifespan in humans. More research is required in this rapidly growing population of super old people. In particular, there is need for more comprehensive investigations including short- and long-term lifestyle interventions as well as investigations focusing on the mechanisms causing DNA damage, mutations, and telomere

  5. Word Reading Fluency: Role of Genome-Wide Single-Nucleotide Polymorphisms in Developmental Stability and Correlations with Print Exposure

    Science.gov (United States)

    Harlaar, Nicole; Trzaskowski, Maciej; Dale, Philip S.; Plomin, Robert

    2014-01-01

    The genetic effects on individual differences in reading development were examined using genome-wide complex trait analysis (GCTA) in a twin sample. In unrelated individuals (one twin per pair, n = 2,942), the GCTA-based heritability of reading fluency was ~20%-29% at ages 7 and 12. GCTA bivariate results showed that the phenotypic stability of…

  6. Global insights into acetic acid resistance mechanisms and genetic stability of Acetobacter pasteurianus strains by comparative genomics.

    Science.gov (United States)

    Wang, Bin; Shao, Yanchun; Chen, Tao; Chen, Wanping; Chen, Fusheng

    2015-12-22

    Acetobacter pasteurianus (Ap) CICC 20001 and CGMCC 1.41 are two acetic acid bacteria strains that, because of their strong abilities to produce and tolerate high concentrations of acetic acid, have been widely used to brew vinegar in China. To globally understand the fermentation characteristics, acid-tolerant mechanisms and genetic stabilities, their genomes were sequenced. Genomic comparisons with 9 other sequenced Ap strains revealed that their chromosomes were evolutionarily conserved, whereas the plasmids were unique compared with other Ap strains. Analysis of the acid-tolerant metabolic pathway at the genomic level indicated that the metabolism of some amino acids and the known mechanisms of acetic acid tolerance, might collaboratively contribute to acetic acid resistance in Ap strains. The balance of instability factors and stability factors in the genomes of Ap CICC 20001 and CGMCC 1.41 strains might be the basis for their genetic stability, consistent with their stable industrial performances. These observations provide important insights into the acid resistance mechanism and the genetic stability of Ap strains and lay a foundation for future genetic manipulation and engineering of these two strains.

  7. Global insights into acetic acid resistance mechanisms and genetic stability of Acetobacter pasteurianus strains by comparative genomics

    Science.gov (United States)

    Wang, Bin; Shao, Yanchun; Chen, Tao; Chen, Wanping; Chen, Fusheng

    2015-12-01

    Acetobacter pasteurianus (Ap) CICC 20001 and CGMCC 1.41 are two acetic acid bacteria strains that, because of their strong abilities to produce and tolerate high concentrations of acetic acid, have been widely used to brew vinegar in China. To globally understand the fermentation characteristics, acid-tolerant mechanisms and genetic stabilities, their genomes were sequenced. Genomic comparisons with 9 other sequenced Ap strains revealed that their chromosomes were evolutionarily conserved, whereas the plasmids were unique compared with other Ap strains. Analysis of the acid-tolerant metabolic pathway at the genomic level indicated that the metabolism of some amino acids and the known mechanisms of acetic acid tolerance, might collaboratively contribute to acetic acid resistance in Ap strains. The balance of instability factors and stability factors in the genomes of Ap CICC 20001 and CGMCC 1.41 strains might be the basis for their genetic stability, consistent with their stable industrial performances. These observations provide important insights into the acid resistance mechanism and the genetic stability of Ap strains and lay a foundation for future genetic manipulation and engineering of these two strains.

  8. Exonuclease 1 is essential for maintaining genomic stability and the proliferative capacity of neural but not hematopoietic stem cells

    Directory of Open Access Journals (Sweden)

    Junling Zhang

    2014-01-01

    Full Text Available Exonuclease 1 (Exo1 has been implicated in the regulation of DNA damage responses in stem cells with dysfunctional telomeres. However, it is unclear whether Exo1-mediated DNA maintenance pathways play a role in the maintenance of genomic stability and the self-renewal of tissue stem cells in mice with functional telomeres. Here, we analyzed the proliferative capacity of neural stem cells (NSCs and hematopoietic stem cells (HSCs from Exo1−/− mice. Our study shows that Exo1 deficiency impairs the maintenance of genomic stability and proliferative capacity in NSCs but not HSCs. In line with these results, we detected a decrease in proliferation and an up-regulation of p21 expression levels in Exo1-deficient NSCs but not Exo1-deficient HSCs. Our data provide experimental evidence that Exo1 deficiency has a differential impact on the homeostasis and proliferative capacity of tissue stem cells in the brain and bone marrow, suggesting that different tissue stem cells utilize distinct mechanisms for maintaining their genomic stability. Our current study provides important insight into the role of Exo1-mediated DNA maintenance pathways in the maintenance of genomic stability and the proliferative capacity of tissue stem cells.

  9. Neural Network Predictive Control Based Power System Stabilizer

    Directory of Open Access Journals (Sweden)

    Ali Mohamed Yousef

    2012-04-01

    Full Text Available The present study investigates the power system stabilizer based on neural predictive control for improving power system dynamic performance over a wide range of operating conditions. In this study a design and application of the Neural Network Model Predictive Controller (NN-MPC on a simple power system composed of a synchronous generator connected to an infinite bus through a transmission line is proposed. The synchronous machine is represented in detail, taking into account the effect of the machine saliency and the damper winding. Neural network model predictive control combines reliable prediction of neural network model with excellent performance of model predictive control using nonlinear Levenberg-Marquardt optimization. This control system is used the rotor speed deviation as a feedback signal. Furthermore, the using performance system of the proposed controller is compared with the system performance using conventional one (PID controller through simulation studies. Digital simulation has been carried out in order to validate the effectiveness proposed NN-MPC power system stabilizer for achieving excellent performance. The results demonstrate that the effectiveness and superiority of the proposed controller in terms of fast response and small settling time.

  10. Improved stability and stabilization design for networked control systems using new quadruple-integral functionals.

    Science.gov (United States)

    Li, Zhichen; Bai, Yan; Li, Tianqi

    2016-07-01

    This paper investigates stability analysis and stabilization for networked control systems. By a refined delay decomposition approach, slightly different Lyapunov-Krasovskii functionals (LKFs) with quadruple-integral terms and augmented vectors containing triple-integral forms of state are constructed. New integral inequalities are proposed to estimate the cross terms from derivatives of the LKFs, which can be proved to offer tighter bounds than what the Jensen one produces theoretically. Moreover, the non-strictly proper rational functions in deriving process are fully handled via reciprocally convex approach. A state feedback controller design approach is also developed. Numerical examples and applications to practical power and oscillator systems demonstrate the superiority of the proposed criteria in conservatism reduction compared to some existing ones.

  11. Roles of human POLD1 and POLD3 in genome stability

    OpenAIRE

    Tumini, Emanuela; Barroso, Sonia; -Calero, Carmen Pérez; Aguilera, Andrés

    2016-01-01

    DNA replication is essential for cellular proliferation. If improperly controlled it can constitute a major source of genome instability, frequently associated with cancer and aging. POLD1 is the catalytic subunit and POLD3 is an accessory subunit of the replicative Pol δ polymerase, which also functions in DNA repair, as well as the translesion synthesis polymerase Pol ζ, whose catalytic subunit is REV3L. In cells depleted of POLD1 or POLD3 we found a differential but general increase in gen...

  12. Stability and synchronization control of stochastic neural networks

    CERN Document Server

    Zhou, Wuneng; Zhou, Liuwei; Tong, Dongbing

    2016-01-01

    This book reports on the latest findings in the study of Stochastic Neural Networks (SNN). The book collects the novel model of the disturbance driven by Levy process, the research method of M-matrix, and the adaptive control method of the SNN in the context of stability and synchronization control. The book will be of interest to university researchers, graduate students in control science and engineering and neural networks who wish to learn the core principles, methods, algorithms and applications of SNN.

  13. Design of a Helicopter Stability and Control Augmentation System Using Optimal Control Theory.

    Science.gov (United States)

    technique is described for the design of multivariable feedback controllers based upon results in optimal control theory . For a specified performance...helicopter flight envelope. The results show that optimal control theory can be used to design a helicopter stability and control augmentation system

  14. Stabilization and tracking control of X-Z inverted pendulum with sliding-mode control.

    Science.gov (United States)

    Wang, Jia-Jun

    2012-11-01

    X-Z inverted pendulum is a new kind of inverted pendulum which can move with the combination of the vertical and horizontal forces. Through a new transformation, the X-Z inverted pendulum is decomposed into three simple models. Based on the simple models, sliding-mode control is applied to stabilization and tracking control of the inverted pendulum. The performance of the sliding mode control is compared with that of the PID control. Simulation results show that the design scheme of sliding-mode control is effective for the stabilization and tracking control of the X-Z inverted pendulum.

  15. Quality guaranteed aggregation based model predictive control and stability analysis

    Institute of Scientific and Technical Information of China (English)

    LI DeWei; XI YuGeng

    2009-01-01

    The input aggregation strategy can reduce the online computational burden of the model predictive controller. But generally aggregation based MPC controller may lead to poor control quality. Therefore, a new concept, equivalent aggregation, is proposed to guarantee the control quality of aggregation based MPC. From the general framework of input linear aggregation, the design methods of equivalent aggregation are developed for unconstrained and terminal zero constrained MPC, which guarantee the actual control inputs exactly to be equal to that of the original MPC. For constrained MPC, quasi-equivalent aggregation strategies are also discussed, aiming to make the difference between the control inputs of aggregation based MPC and original MPC as small as possible. The stability conditions are given for the quasi-equivalent aggregation based MPC as well.

  16. Multivariable nonlinear control of STATCOM for synchronous generator stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Sahoo, N.C. [Multimedia Univ., Melaka (Malaysia). Faculty of Engineering and Technology; Panigrahi, B.K.; Panda, G. [Multimedia Univ., Selangor (Malaysia); Dash, P.K. [National Inst. of Technology, Rourkela (India)

    2004-01-01

    A static synchronous compensator (STATCOM) is a typical flexible ac transmission system device playing a vital role as a stability aid for small and large transient disturbances in an interconnected power system. This article deals with design and evaluation of a feedback linearizing nonlinear controller for STATCOM installed in a single-machine infinite-bus power system. In addition to the coordinated control of ac and dc bus voltages, the proposed controller also provides good damping to the electromechanical oscillation of the synchronous generator under transient disturbances. The efficiency of the control strategy is evaluated by computer simulation studies. The comparative study of these results with the conventional cascade control structure establishes the elegance of the proposed control scheme. (author)

  17. Stability and Control. Volume 2. Stability and Control Flight Test Theory

    Science.gov (United States)

    1974-07-01

    standby capable of reverting to manual revtrsible control. B.a AIRCRAFT FEIL SYSTEMS Aircraft feel was discussed at some length in section 9.1...pensate for unstable stick force gradients in the transonic speed region. MARTIN B-57E ^ v/1 The longitudinal control sys- tem is a reversible type

  18. Regular exercise participation improves genomic stability in diabetic patients: an exploratory study to analyse telomere length and DNA damage.

    Science.gov (United States)

    Dimauro, Ivan; Sgura, Antonella; Pittaluga, Monica; Magi, Fiorenza; Fantini, Cristina; Mancinelli, Rosa; Sgadari, Antonio; Fulle, Stefania; Caporossi, Daniela

    2017-06-23

    Physical activity has been demonstrated to be effective in the prevention and treatment of different chronic conditions, including type 2 diabetes (T2D). In particular, several studies highlighted how the beneficial effects of physical activity may be related to the stability of the DNA molecule, such as longer telomeric ends. Here we analyze the effect of exercise training on telomere length, spontaneous and H2O2-induced DNA damage, as well as the apoptosis level in leukocytes from untrained or trained T2D patients vs. age-matched control subjects (CS) (57-66 years). Moreover, expression analysis of selected genes belonging to DNA repair systems, cell cycle control, antioxidant and defence systems was performed. Subjects that participated in a regular exercise program showed a longer telomere sequence than untrained counterparts. Moreover, ex vivo treatment of leukocytes with H2O2 highlighted that: (1) oxidative DNA damage induced similar telomere attrition in all groups; (2) in T2D subjects, physical activity seemed to prevent a significant increase of genomic oxidative DNA damage induced by chronic exposure to pro-oxidant stimulus, and (3) decreased the sensitivity of leukocytes to apoptosis. Finally, the gene expression analysis in T2D subjects suggested an adaptive response to prolonged exercise training that improved the response of specific genes.

  19. Stability Control of Vehicle Emergency Braking with Tire Blowout

    Directory of Open Access Journals (Sweden)

    Qingzhang Chen

    2014-01-01

    Full Text Available For the stability control and slowing down the vehicle to a safe speed after tire failure, an emergency automatic braking system with independent intellectual property is developed. After the system has received a signal of tire blowout, the automatic braking mode of the vehicle is determined according to the position of the failure tire and the motion state of vehicle, and a control strategy for resisting tire blowout additional yaw torque and deceleration is designed to slow down vehicle to a safe speed in an expected trajectory. The simulating test system is also designed, and the testing results show that the vehicle can be quickly stabilized and kept in the original track after tire blowout with the emergency braking system described in the paper.

  20. Robust stability in predictive control with soft constraints

    DEFF Research Database (Denmark)

    Thomsen, Sven Creutz; Niemann, Hans Henrik; Poulsen, Niels Kjølstad

    2010-01-01

    In this paper we take advantage of the primary and dual Youla parameterizations for setting up a soft constrained model predictive control (MPC) scheme for which stability is guaranteed in face of norm-bounded uncertainties. Under special conditions guarantees are also given for hard input...... consisting of the primary and dual Youla parameter. This is included in the MPC optimization as a constraint on the induced gain of the optimization variable. We illustrate the method with a numerical simulation example....

  1. STABILIZATION OF NONLINEAR TIME-VARYING SYSTEMS: A CONTROL LYAPUNOV FUNCTION APPROACH

    Institute of Scientific and Technical Information of China (English)

    Zhongping JIANG; Yuandan LIN; Yuan WANG

    2009-01-01

    This paper presents a control Lyapunov function approach to the global stabilization problem for general nonlinear and time-varying systems. Explicit stabilizing feedback control laws are proposed based on the method of control Lyapunov functions and Sontag's universal formula.

  2. A comprehensive gaze stabilization controller based on cerebellar internal models

    DEFF Research Database (Denmark)

    Vannucci, Lorenzo; Falotico, Egidio; Tolu, Silvia

    2017-01-01

    based on the coordination of VCR and VOR and OKR. The model, inspired by neuroscientific cerebellar theories, is provided with learning and adaptation capabilities based on internal models. We present the results for the gaze stabilization model on three sets of experiments conducted on the SABIAN robot...... and on the iCub simulator, validating the robustness of the proposed control method. The first set of experiments focused on the controller response to a set of disturbance frequencies along the vertical plane. The second shows the performances of the system under three-dimensional disturbances. The last set...

  3. Fault Tolerant Emergency Control to Preserve Power System Stability

    DEFF Research Database (Denmark)

    Pedersen, Andreas Søndergaard; Richter, Jan H.; Tabatabaeipour, Mojtaba;

    2016-01-01

    This paper introduces a method for fault-masking and system reconfiguration in power transmission systems. The paper demonstrates how faults are handled by reconfiguring remaining controls through utilisation of wide-area measurement in real time. It is shown how reconfiguration can be obtained...... using a virtual actuator concept, which covers Lure-type systems. The paper shows the steps needed to calculate a virtual actuator, which relies on the solution of a linear matrix inequality. The solution is shown to work with existing controls by adding a compensation signal. Simulation results...... of a benchmark system show ability of the reconfiguration to maintain stability...

  4. Stability analysis of traffic flow with extended CACC control models

    Science.gov (United States)

    Ya-Zhou, Zheng; Rong-Jun, Cheng; Siu-Ming, Lo; Hong-Xia, Ge

    2016-06-01

    To further investigate car-following behaviors in the cooperative adaptive cruise control (CACC) strategy, a comprehensive control system which can handle three traffic conditions to guarantee driving efficiency and safety is designed by using three CACC models. In this control system, some vital comprehensive information, such as multiple preceding cars’ speed differences and headway, variable safety distance (VSD) and time-delay effect on the traffic current and the jamming transition have been investigated via analytical or numerical methods. Local and string stability criterion for the velocity control (VC) model and gap control (GC) model are derived via linear stability theory. Numerical simulations are conducted to study the performance of the simulated traffic flow. The simulation results show that the VC model and GC model can improve driving efficiency and suppress traffic congestion. Project supported by the National Natural Science Foundation of China (Grant Nos. 71571107 and 11302110). The Scientific Research Fund of Zhejiang Province, China (Grant Nos. LY15A020007, LY15E080013, and LY16G010003). The Natural Science Foundation of Ningbo City (Grant Nos. 2014A610030 and 2015A610299), the Fund from the Government of the Hong Kong Administrative Region, China (Grant No. CityU11209614), and the K C Wong Magna Fund in Ningbo University, China.

  5. Lyapunov function gradient generated robust control in the absence of the nominal stabilizing control

    Science.gov (United States)

    Blackwell, C. C.

    1987-01-01

    A relevant facet of the application of Lyapunov gradient-generated robust control to unstable linear autonomous plants is explored. It is demonstrated that if the plant, the output, and the nominal stabilizing control satisfy certain conditions, then the robust component alone stabilizes the nominal plant. An example characterized by two zero eigenvalues and two negative real value poles is presented. These results assure that the robust component will fulfill the role of nominal stabilization successfully so long as the possible magnitude of the robust component can overcome the contribution of the instability to positiveness of the Lyapunov rate.

  6. Lyapunov function gradient generated robust control in the absence of the nominal stabilizing control

    Science.gov (United States)

    Blackwell, C. C.

    1987-01-01

    A relevant facet of the application of Lyapunov gradient-generated robust control to unstable linear autonomous plants is explored. It is demonstrated that if the plant, the output, and the nominal stabilizing control satisfy certain conditions, then the robust component alone stabilizes the nominal plant. An example characterized by two zero eigenvalues and two negative real value poles is presented. These results assure that the robust component will fulfill the role of nominal stabilization successfully so long as the possible magnitude of the robust component can overcome the contribution of the instability to positiveness of the Lyapunov rate.

  7. Control of time stability of scintillation spectrometer of delayed coincidences

    CERN Document Server

    Morozov, V A

    2002-01-01

    Paper describes a system to control time stability of a two-detector plastic scintillation spectrometer of three-dimensional coincides. A two-reference control system incorporates a light guide base delay optical line, two light diodes and a two-channel generator of nanosecond pulses. A distinguishing feature of the design system is application of one delay line to form both advance and delay time signal as to the real coincidences in the studied radioactive source. The designed system of control enables to measure periods of half-decay of nuclei excited states within 40-100 ns range ensuring control of position of coincidence curve gravity centers within 4 ps limits

  8. Rotational Stabilization of Cylinder Wakes Using Linear Feedback Control

    Science.gov (United States)

    Borggaard, Jeff; Gugercin, Serkan; Zietsman, Lizette

    2015-11-01

    We demonstrate the feasibility of linear feedback control to stabilize vortex shedding behind twin cylinders using the cylinder rotations. Our approach is to linearize the flow about a desired steady-state flow, use interpolation-based model reduction on the resulting linear model to generate a low-dimensional model of the input-output system with input-independent error bounds, then use this reduced model to design the feedback control law. We then consider the practical issue of limited state measurements by building a nonlinear compensator that is computed from the same linear reduced-order model an constructed through an extended Kalman filter with a proper orthogonal decomposition (POD) model. Closed-loop simulations of the Navier-Stokes equations coupled with controls generated through flow measurements demonstrate the effectiveness of this control strategy. Supported in part by the National Science Foundation.

  9. Stability Concerns for Indirect Consumer Control in Smart Grids

    DEFF Research Database (Denmark)

    Juelsgaard, Morten; Andersen, Palle; Wisniewski, Rafal

    2013-01-01

    by an external third party, and indirect consumer control through incentives and price signals. In this work we present a simple formulation of indirect control, where the behavior of each consumer, is governed by local optimization of energy consumption. The local optimization accounts for both cost of energy...... and distribution losses, as well as any discomfort incurred by consumers from any shift in energy consumption. Our work will illustrate that in the simplest formulation of indirect control, the stability is greatly affected of both the behavior of consumers, and the number of consumers to include. We will show how......Demand side management will be an important tool for maintaining a balanced electrical grid in the future, when the penetration of volatile resources, such as wind and solar energy increases. Recent research focuses on two different management approaches, namely direct consumer control...

  10. p53 Maintains Genomic Stability by Preventing Interference between Transcription and Replication

    Directory of Open Access Journals (Sweden)

    Constance Qiao Xin Yeo

    2016-04-01

    Full Text Available p53 tumor suppressor maintains genomic stability, typically acting through cell-cycle arrest, senescence, and apoptosis. We discovered a function of p53 in preventing conflicts between transcription and replication, independent of its canonical roles. p53 deficiency sensitizes cells to Topoisomerase (Topo II inhibitors, resulting in DNA damage arising spontaneously during replication. Topoisomerase IIα (TOP2A-DNA complexes preferentially accumulate in isogenic p53 mutant or knockout cells, reflecting an increased recruitment of TOP2A to regulate DNA topology. We propose that p53 acts to prevent DNA topological stress originating from transcription during the S phase and, therefore, promotes normal replication fork progression. Consequently, replication fork progression is impaired in the absence of p53, which is reversed by transcription inhibition. Pharmacologic inhibition of transcription also attenuates DNA damage and decreases Topo-II-DNA complexes, restoring cell viability in p53-deficient cells. Together, our results demonstrate a function of p53 that may underlie its role in tumor suppression.

  11. Chlorine ions but not sodium ions alter genome stability of Arabidopsis thaliana.

    Science.gov (United States)

    Boyko, Alex; Golubov, Andrey; Bilichak, Andriy; Kovalchuk, Igor

    2010-06-01

    Various environmental stresses influence plant genome stability. Most of these stresses, such as ionizing radiation, heavy metals and organic chemicals, represent potent DNA-damaging agents. Here, we show that exposure to NaCl, the stress that is not thought to cause direct DNA damage, results in an increase in the level of strand breaks and homologous recombination rates (RRs) in Arabidopsis thaliana plants. The effect of salt stress on the RR was found to be primarily associated with Cl(-) ions, since exposure of plants to Na(2)SO(4) did not increase the RR, whereas exposure to MgCl(2) resulted in an increase. Changes in the number of strand breaks and in the RR were also paralleled by transcriptional activation of AtRad51 and down-regulation of AtKu70. The progeny of exposed plants exhibited higher RRs, higher expression of AtRad51, lower expression of AtKu70, higher tolerance to salt and methyl methane sulfate (MMS) stresses, as well as a higher increase in RR upon further exposure to stress. Our experiments showed that NaCl is a genotoxic stress that leads to somatic and transgenerational changes in recombination rates, and these changes are primarily triggered by exposure to Cl(-) ions.

  12. LHC Beam Stability and Feedback Control - Orbit and Energy -

    CERN Document Server

    Steinhagen, R J

    2007-01-01

    This report presents the stability and control of the Large Hadron Collider's (LHC) two beam orbits and their particle momenta using beam-based feedback systems. The LHC, presently being built at CERN, will store, accelerate and provide particle collisions with a maximum particle momentum of 7TeV/c and a nominal luminosity of L = 10^34 cm^−2s^−1. The presence of two beams, with both high intensity as well as high particle energies, requires excellent control of particle losses inside a superconducting environment, which will be provided by the LHC Cleaning and Machine Protection System. The performance and function of this and other systems depends critically on the stability of the beam and may eventually limit the LHC performance. Environmental and accelerator-inherent sources as well as failure of magnets and their power converters may perturb and reduce beam stability and may consequently lead to an increase of particle loss inside the cryogenic mass. In order to counteract these disturbances, c...

  13. Controls of nucleosome positioning in the human genome.

    Directory of Open Access Journals (Sweden)

    Daniel J Gaffney

    Full Text Available Nucleosomes are important for gene regulation because their arrangement on the genome can control which proteins bind to DNA. Currently, few human nucleosomes are thought to be consistently positioned across cells; however, this has been difficult to assess due to the limited resolution of existing data. We performed paired-end sequencing of micrococcal nuclease-digested chromatin (MNase-seq from seven lymphoblastoid cell lines and mapped over 3.6 billion MNase-seq fragments to the human genome to create the highest-resolution map of nucleosome occupancy to date in a human cell type. In contrast to previous results, we find that most nucleosomes have more consistent positioning than expected by chance and a substantial fraction (8.7% of nucleosomes have moderate to strong positioning. In aggregate, nucleosome sequences have 10 bp periodic patterns in dinucleotide frequency and DNase I sensitivity; and, across cells, nucleosomes frequently have translational offsets that are multiples of 10 bp. We estimate that almost half of the genome contains regularly spaced arrays of nucleosomes, which are enriched in active chromatin domains. Single nucleotide polymorphisms that reduce DNase I sensitivity can disrupt the phasing of nucleosome arrays, which indicates that they often result from positioning against a barrier formed by other proteins. However, nucleosome arrays can also be created by DNA sequence alone. The most striking example is an array of over 400 nucleosomes on chromosome 12 that is created by tandem repetition of sequences with strong positioning properties. In summary, a large fraction of nucleosomes are consistently positioned--in some regions because they adopt favored sequence positions, and in other regions because they are forced into specific arrangements by chromatin remodeling or DNA binding proteins.

  14. Variable selection with error control: Another look at Stability Selection

    CERN Document Server

    Shah, Rajen

    2011-01-01

    Stability Selection was recently introduced by Meinshausen and Buhlmann (2010) as a very general technique designed to improve the performance of a variable selection algorithm. It is based on aggregating the results of applying a selection procedure to subsamples of the data. We introduce a variant, called Complementary Pairs Stability Selection (CPSS), and derive bounds both on the expected number of variables included by CPSS that have low selection probability under the original procedure, and on the expected number of high selection probability variables that are excluded. These results require no (e.g. exchangeability) assumptions on the underlying model or on the quality of the original selection procedure. Under reasonable shape restrictions, the bounds can be further tightened, yielding improved error control, and therefore increasing the applicability of the methodology.

  15. Streamlining genomes: toward the generation of simplified and stabilized microbial systems

    NARCIS (Netherlands)

    Leprince, A.; Passel, van M.W.J.; Martins Dos Santos, V.A.P.

    2012-01-01

    At the junction between systems and synthetic biology, genome streamlining provides a solid foundation both for increased understanding of cellular circuitry, and for the tailoring of microbial chassis towards innovative biotechnological applications. Iterative genomic deletions (targeted and random

  16. Microgrid Stability Controller Based on Adaptive Robust Total SMC

    Directory of Open Access Journals (Sweden)

    Xiaoling Su

    2015-03-01

    Full Text Available This paper presents a microgrid stability controller (MSC in order to provide existing distributed generation units (DGs the additional functionality of working in islanding mode without changing their control strategies in grid-connected mode and to enhance the stability of the microgrid. Microgrid operating characteristics and mathematical models of the MSC indicate that the system is inherently nonlinear and time-variable. Therefore, this paper proposes an adaptive robust total sliding-mode control (ARTSMC system for the MSC. It is proved that the ARTSMC system is insensitive to parametric uncertainties and external disturbances. The MSC provides fast dynamic response and robustness to the microgrid. When the system is operating in grid-connected mode, it is able to improve the controllability of the exchanged power between the microgrid and the utility grid, while smoothing the DGs’ output power. When the microgrid is operating in islanded mode, it provides voltage and frequency support, while guaranteeing seamless transition between the two operation modes. Simulation and experimental results show the effectiveness of the proposed approach.

  17. Stability and Bifurcation in Magnetic Flux Feedback Maglev Control System

    Directory of Open Access Journals (Sweden)

    Wen-Qing Zhang

    2013-01-01

    Full Text Available Nonlinear properties of magnetic flux feedback control system have been investigated mainly in this paper. We analyzed the influence of magnetic flux feedback control system on control property by time delay and interfering signal of acceleration. First of all, we have established maglev nonlinear model based on magnetic flux feedback and then discussed hopf bifurcation’s condition caused by the acceleration’s time delay. The critical value of delayed time is obtained. It is proved that the period solution exists in maglev control system and the stable condition has been got. We obtained the characteristic values by employing center manifold reduction theory and normal form method, which represent separately the direction of hopf bifurcation, the stability of the period solution, and the period of the period motion. Subsequently, we discussed the influence maglev system on stability of by acceleration’s interfering signal and obtained the stable domain of interfering signal. Some experiments have been done on CMS04 maglev vehicle of National University of Defense Technology (NUDT in Tangshan city. The results of experiments demonstrate that viewpoints of this paper are correct and scientific. When time lag reaches the critical value, maglev system will produce a supercritical hopf bifurcation which may cause unstable period motion.

  18. Biological Stability of Drinking Water: Controlling Factors, Methods, and Challenges

    KAUST Repository

    Prest, Emmanuelle I.

    2016-02-01

    Biological stability of drinking water refers to the concept of providing consumers with drinking water of same microbial quality at the tap as produced at the water treatment facility. However, uncontrolled growth of bacteria can occur during distribution in water mains and premise plumbing, and can lead to hygienic (e.g., development of opportunistic pathogens), aesthetic (e.g., deterioration of taste, odor, color) or operational (e.g., fouling or biocorrosion of pipes) problems. Drinking water contains diverse microorganisms competing for limited available nutrients for growth. Bacterial growth and interactions are regulated by factors, such as (i) type and concentration of available organic and inorganic nutrients, (ii) type and concentration of residual disinfectant, (iii) presence of predators, such as protozoa and invertebrates, (iv) environmental conditions, such as water temperature, and (v) spatial location of microorganisms (bulk water, sediment, or biofilm). Water treatment and distribution conditions in water mains and premise plumbing affect each of these factors and shape bacterial community characteristics (abundance, composition, viability) in distribution systems. Improved understanding of bacterial interactions in distribution systems and of environmental conditions impact is needed for better control of bacterial communities during drinking water production and distribution. This article reviews (i) existing knowledge on biological stability controlling factors and (ii) how these factors are affected by drinking water production and distribution conditions. In addition, (iii) the concept of biological stability is discussed in light of experience with well-established and new analytical methods, enabling high throughput analysis and in-depth characterization of bacterial communities in drinking water. We discussed, how knowledge gained from novel techniques will improve design and monitoring of water treatment and distribution systems in order

  19. Biological Stability of Drinking Water: Controlling Factors, Methods, and Challenges

    Science.gov (United States)

    Prest, Emmanuelle I.; Hammes, Frederik; van Loosdrecht, Mark C. M.; Vrouwenvelder, Johannes S.

    2016-01-01

    Biological stability of drinking water refers to the concept of providing consumers with drinking water of same microbial quality at the tap as produced at the water treatment facility. However, uncontrolled growth of bacteria can occur during distribution in water mains and premise plumbing, and can lead to hygienic (e.g., development of opportunistic pathogens), aesthetic (e.g., deterioration of taste, odor, color) or operational (e.g., fouling or biocorrosion of pipes) problems. Drinking water contains diverse microorganisms competing for limited available nutrients for growth. Bacterial growth and interactions are regulated by factors, such as (i) type and concentration of available organic and inorganic nutrients, (ii) type and concentration of residual disinfectant, (iii) presence of predators, such as protozoa and invertebrates, (iv) environmental conditions, such as water temperature, and (v) spatial location of microorganisms (bulk water, sediment, or biofilm). Water treatment and distribution conditions in water mains and premise plumbing affect each of these factors and shape bacterial community characteristics (abundance, composition, viability) in distribution systems. Improved understanding of bacterial interactions in distribution systems and of environmental conditions impact is needed for better control of bacterial communities during drinking water production and distribution. This article reviews (i) existing knowledge on biological stability controlling factors and (ii) how these factors are affected by drinking water production and distribution conditions. In addition, (iii) the concept of biological stability is discussed in light of experience with well-established and new analytical methods, enabling high throughput analysis and in-depth characterization of bacterial communities in drinking water. We discussed, how knowledge gained from novel techniques will improve design and monitoring of water treatment and distribution systems in order

  20. Biological Stability of Drinking Water: Controlling Factors, Methods, and Challenges.

    Science.gov (United States)

    Prest, Emmanuelle I; Hammes, Frederik; van Loosdrecht, Mark C M; Vrouwenvelder, Johannes S

    2016-01-01

    Biological stability of drinking water refers to the concept of providing consumers with drinking water of same microbial quality at the tap as produced at the water treatment facility. However, uncontrolled growth of bacteria can occur during distribution in water mains and premise plumbing, and can lead to hygienic (e.g., development of opportunistic pathogens), aesthetic (e.g., deterioration of taste, odor, color) or operational (e.g., fouling or biocorrosion of pipes) problems. Drinking water contains diverse microorganisms competing for limited available nutrients for growth. Bacterial growth and interactions are regulated by factors, such as (i) type and concentration of available organic and inorganic nutrients, (ii) type and concentration of residual disinfectant, (iii) presence of predators, such as protozoa and invertebrates, (iv) environmental conditions, such as water temperature, and (v) spatial location of microorganisms (bulk water, sediment, or biofilm). Water treatment and distribution conditions in water mains and premise plumbing affect each of these factors and shape bacterial community characteristics (abundance, composition, viability) in distribution systems. Improved understanding of bacterial interactions in distribution systems and of environmental conditions impact is needed for better control of bacterial communities during drinking water production and distribution. This article reviews (i) existing knowledge on biological stability controlling factors and (ii) how these factors are affected by drinking water production and distribution conditions. In addition, (iii) the concept of biological stability is discussed in light of experience with well-established and new analytical methods, enabling high throughput analysis and in-depth characterization of bacterial communities in drinking water. We discussed, how knowledge gained from novel techniques will improve design and monitoring of water treatment and distribution systems in order

  1. Biological stability of drinking water: controlling factors, methods and challenges

    Directory of Open Access Journals (Sweden)

    Emmanuelle ePrest

    2016-02-01

    Full Text Available Biological stability of drinking water refers to the concept of providing consumers with drinking water of same microbial quality at the tap as produced at the water treatment facility. However, uncontrolled growth of bacteria can occur during distribution in water mains and premise plumbing, and can lead to hygienic (e.g. development of opportunistic pathogens, aesthetic (e.g. deterioration of taste, odour, colour or operational (e.g. fouling or biocorrosion of pipes problems. Drinking water contains diverse microorganisms competing for limited available nutrients for growth. Bacterial growth and interactions are regulated by factors such as (i type and concentration of available organic and inorganic nutrients, (ii type and concentration of residual disinfectant, (iii presence of predators such as protozoa and invertebrates, (iv environmental conditions such as water temperature, and (v spatial location of microorganisms (bulk water, sediment or biofilm. Water treatment and distribution conditions in water mains and premise plumbing affect each of these factors and shape bacterial community characteristics (abundance, composition, viability in distribution systems. Improved understanding of bacterial interactions in distribution systems and of environmental conditions impact is needed for better control of bacterial communities during drinking water production and distribution. This article reviews (i existing knowledge on biological stability controlling factors and (ii how these factors are affected by drinking water production and distribution conditions. In addition, (iii the concept of biological stability is discussed in light of experience with well-established and new analytical methods, enabling high throughput analysis and in-depth characterization of bacterial communities in drinking water. We discuss how knowledge gained from novel techniques will improve design and monitoring of water treatment and distribution systems in order to

  2. Research on the stability of control systems described by fractional-order transfer functions

    Institute of Scientific and Technical Information of China (English)

    Zeng Qingshan; Zhu Xinjian; Cao Guangyi

    2005-01-01

    The stability of control systems described by fractional-order transfer function form is mainly investigated. The stability analysis of integer-order linear systems was extended to the fractional-order control systems. The stability definition of fractional-order linear control systems is presented in terms of the Lyapunov's stability theory. Using the theorems of the Mittag-Leffler function in two parameters directly derives the stability conclusion. The illustrative examples are also given by simulation results.

  3. Interline power flow controller (IPFC) based damping recurrent neural network controllers for enhancing stability

    Energy Technology Data Exchange (ETDEWEB)

    Banaei, M.R., E-mail: m.banaei@azaruniv.ed [Electrical Engineering Department, Faculty of Engineering, Azarbaijan University of Tarbiat Moallem, Tabriz (Iran, Islamic Republic of); Kami, A. [Electrical Engineering Department, Faculty of Engineering, Azarbaijan University of Tarbiat Moallem, Tabriz (Iran, Islamic Republic of)

    2011-07-15

    Highlights: {yields} A method is presented to improve power system stability using IPFC. {yields} Recurrent neural network controllers damp oscillations in a power system. {yields} Training is based on back propagation with adaptive training parameters. {yields} Selection of effectiveness damping control signal carried out using SVD method. -- Abstract: This paper presents a method to improve power system stability using IPFC based damping online learning recurrent neural network controllers for damping oscillations in a power system. Parameters of equipped controllers for enhancing dynamical stability at the IPFC are tuned using mathematical methods. Therefore these control parameters are often fixed and are set for particular system configurations or operating points. Multilayer recurrent neural network, which can be tuned for changing system conditions, is used in this paper for effectively damp the oscillations. Training is based on back propagation with adaptive training parameters. This controller is tested to variations in system loading and fault in the power system and its performance is compared with performance of a controller that the phase compensation method is used to set its parameters. Selection of effectiveness damping control signal for the design of robust IPFC damping controller carried out through singular value decomposition (SVD) method. Simulation studies show the superior robustness and stabilizing effect of the proposed controller in comparison with phase compensation method.

  4. Designing hybrid grass genomes to control runoff generation

    Science.gov (United States)

    MacLeod, C.; Binley, A.; Humphreys, M.; King, I. P.; O'Donovan, S.; Papadopoulos, A.; Turner, L. B.; Watts, C.; Whalley, W. R.; Haygarth, P.

    2010-12-01

    Sustainable management of water in landscapes requires balancing demands of agricultural production whilst moderating downstream effects like flooding. Pasture comprises 69% of global agricultural areas and is essential for producing food and fibre alongside environmental goods and services. Thus there is a need to breed forage grasses that deliver multiple benefits through increased levels of productivity whilst moderating fluxes of water. Here we show that a novel grass hybrid that combines the entire genomes of perennial ryegrass (Lolium perenne - the grass of choice for Europe’s forage agriculture) and meadow fescue (Festuca pratensis) has a significant role in flood prevention. Field plot experiments established differences in runoff generation with the hybrid cultivar reducing runoff by 50% compared to perennial ryegrass cultivar, and by 35% compared to a meadow fescue cultivar (34 events over two years, replicated randomized-block design, statistically significant differences). This important research outcome was the result of a project that combined plant genetics, soil physics and plot scale hydrology to identify novel grass genotypes that can reduce runoff from grassland systems. Through a coordinated series of experiments examining effects from the gene to plot scale, we have identified that the rapid growth and then turnover of roots in the L. perenne x F. pratensis hybrid is likely to be a key mechanism in reducing runoff generation. More broadly this is an exciting first step to realizing the potential to design grass genomes to achieve both food production, and to deliver flood control, a key ecosystem service.

  5. Deregulation of DNA double-strand break repair in multiple myeloma: implications for genome stability.

    Directory of Open Access Journals (Sweden)

    Ana B Herrero

    Full Text Available Multiple myeloma (MM is a hematological malignancy characterized by frequent chromosome abnormalities. However, the molecular basis for this genome instability remains unknown. Since both impaired and hyperactive double strand break (DSB repair pathways can result in DNA rearrangements, we investigated the functionality of DSB repair in MM cells. Repair kinetics of ionizing-radiation (IR-induced DSBs was similar in MM and normal control lymphoblastoid cell lines, as revealed by the comet assay. However, four out of seven MM cell lines analyzed exhibited a subset of persistent DSBs, marked by γ-H2AX and Rad51 foci that elicited a prolonged G2/M DNA damage checkpoint activation and hypersensitivity to IR, especially in the presence of checkpoint inhibitors. An analysis of the proteins involved in DSB repair in MM cells revealed upregulation of DNA-PKcs, Artemis and XRCC4, that participate in non-homologous end joining (NHEJ, and Rad51, involved in homologous recombination (HR. Accordingly, activity of both NHEJ and HR were elevated in MM cells compared to controls, as determined by in vivo functional assays. Interestingly, levels of proteins involved in a highly mutagenic, translocation-promoting, alternative NHEJ subpathway (Alt-NHEJ were also increased in all MM cell lines, with the Alt-NHEJ protein DNA ligase IIIα, also overexpressed in several plasma cell samples isolated from MM patients. Overactivation of the Alt-NHEJ pathway was revealed in MM cells by larger deletions and higher sequence microhomology at repair junctions, which were reduced by chemical inhibition of the pathway. Taken together, our results uncover a deregulated DSB repair in MM that might underlie the characteristic genome instability of the disease, and could be therapeutically exploited.

  6. Control of Yaw Disturbance Using Fuzzy Logic Based Yaw Stability Controller

    Directory of Open Access Journals (Sweden)

    S. Krishna

    2014-01-01

    Full Text Available Yaw stability is an important consideration for the vehicle directional stability and handling behavior during emergency maneuvers. In order to maintain the desired path of the vehicle, in presence of disturbances due to cross wind, different road conditions, and tire deflections, a fuzzy logic based yaw stability controller is proposed in this paper. Proposed control system receives yaw rate error, steering angle given by the driver, and side slip angle as inputs, for calculating the additional steering angle as output, for maintaining the yaw stability of the vehicle. As the side slip angle cannot be measured directly in a vehicle, it was estimated using a model based Kalman observer. A two-degrees-of-freedom vehicle model is considered in the present work. The effect of disturbance on yaw rate and yaw rate error of the vehicle is simulated for sinusoidal, step maneuver and compared with the existing fuzzy control system which uses two inputs such as steering angle and yaw rate. The simulation results show better performance of the proposed fuzzy based yaw controller as compared with existing control system. Proposed fuzzy based yaw stability controller can be implemented in steer-by-wire system for an active front steering of a road vehicle.

  7. Design and Stability of an On-Orbit Attitude Control System Using Reaction Control Thrusters

    Science.gov (United States)

    Hall, Robert A.; Hough, Steven; Orphee, Carolina; Clements, Keith

    2016-01-01

    NASA is providing preliminary design and requirements for the Space Launch System Exploration Upper Stage (EUS). The EUS will provide upper stage capability for vehicle ascent as well as on-orbit control capability. Requirements include performance of on-orbit burn to provide Orion vehicle with escape velocity. On-orbit attitude control is accommodated by a on-off Reaction Control System (RCS). Paper provides overview of approaches for design and stability of an attitude control system using a RCS.

  8. Improving electrokinetic microdevice stability by controlling electrolysis bubbles.

    Science.gov (United States)

    Lee, Hwi Yong; Barber, Cedrick; Minerick, Adrienne R

    2014-07-01

    The voltage-operating window for many electrokinetic microdevices is limited by electrolysis gas bubbles that destabilize microfluidic system causing noise and irreproducible responses above ∼3 V DC and less than ∼1 kHz AC at 3 Vpp. Surfactant additives, SDS and Triton X-100, and an integrated semipermeable SnakeSkin® membrane were employed to control and assess electrolysis bubbles from platinum electrodes in a 180 by 70 μm, 10 mm long microchannel. Stabilized current responses at 100 V DC were observed with surfactant additives or SnakeSkin® barriers. Electrolysis bubble behaviors, visualized via video microscopy at the electrode surface and in the microchannels, were found to be influenced by surfactant function and SnakeSkin® barriers. Both SDS and Triton X-100 surfactants promoted smaller bubble diameters and faster bubble detachment from electrode surfaces via increasing gas solubility. In contrast, SnakeSkin® membranes enhanced natural convection and blocked bubbles from entering the microchannels and thus reduced current disturbances in the electric field. This data illustrated that electrode surface behaviors had substantially greater impacts on current stability than microbubbles within microchannels. Thus, physically blocking bubbles from microchannels is less effective than electrode functionalization approaches to stabilize electrokinetic microfluidic systems.

  9. Numerical stability analysis in respiratory control system models

    Directory of Open Access Journals (Sweden)

    Laszlo E. Kollar

    2005-04-01

    Full Text Available Stability of the unique equilibrium in two mathematical models (based on chemical balance dynamics of human respiration is examined using numerical methods. Due to the transport delays in the respiratory control system these models are governed by delay differential equations. First, a simplified two-state model with one delay is considered, then a five-state model with four delays (where the application of numerical methods is essential is investigated. In particular, software is developed to perform linearized stability analysis and simulations of the model equations. Furthermore, the Matlab package DDE-BIFTOOL v.~2.00 is employed to carry out numerical bifurcation analysis. Our main goal is to study the effects of transport delays on the stability of the model equations. Critical values of the transport delays (i.e., where Hopf bifurcations occur are determined, and stable periodic solutions are found as the delays pass their critical values. The numerical findings are in good agreement with analytic results obtained earlier for the two-state model.

  10. Robust stability in constrained predictive control through the Youla parameterisations

    DEFF Research Database (Denmark)

    Thomsen, Sven Creutz; Niemann, Hans Henrik; Poulsen, Niels Kjølstad

    2011-01-01

    In this article we take advantage of the primary and dual Youla parameterisations to set up a soft constrained model predictive control (MPC) scheme. In this framework it is possible to guarantee stability in face of norm-bounded uncertainties. Under special conditions guarantees are also given...... arguments on the loop consisting of the primary and dual Youla parameter. This is included in the MPC optimisation as a constraint on the induced gain of the optimisation variable. We illustrate the method with a numerical simulation example....

  11. Handbook of electrical power system dynamics modeling, stability, and control

    CERN Document Server

    Eremia, Mircea

    2013-01-01

    Complete guidance for understanding electrical power system dynamics and blackouts This handbook offers a comprehensive and up-to-date treatment of power system dynamics. Addressing the full range of topics, from the fundamentals to the latest technologies in modeling, stability, and control, Handbook of Electrical Power System Dynamics provides engineers with hands-on guidance for understanding the phenomena leading to blackouts so they can design the most appropriate solutions for a cost-effective and reliable operation. Focusing on system dynamics, the book details

  12. Voltage stability and controllability indices for multimachine power systems

    Energy Technology Data Exchange (ETDEWEB)

    Vournas, C.D. [National Technical Univ., Athens (Greece). Electrical Energy Systems Lab.

    1995-08-01

    This paper presents a voltage stability index (VSI) and a voltage controllability index (VCI), related to the eigenvalues of mxm matrices in a multimachine power system made up of m synchronous generators and a number of infinite buses. System loads can have an arbitrary voltage sensitivity described by generalized voltage exponents. These nonlinear loads are linearized around an operating point and incorporated into a modified admittance matrix, which is subsequently reduced to the generator terminals using an efficient algorithm and sparsity techniques. The indices proposed are tested in a practical system and it is demonstrated that they provide a timely warning during a sequence of events leading to voltage collapse.

  13. STABILIZATION OF VIBRATING BEAM BY VELOCITY FEEDBACK CONTROL

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A flexible structure consisting of a Euler-Bernoulli beam with co-located sensors and actuators is considered.The control is a shear force in proportion to velocity.It is known that uniform exponential stability can be achieved with velocity feedback.A sensitivity asymptotic analysis of the system's eigenvalues and eigenfunctions is set up.The authors prove that,for K1 ∈ [0,+∞),all of the generalized eigenvectors of A form a Riesz basis of H.It is also proved that the optimal exponential decay rate can be obtained from the spectrum of the system for 0 < Kl < +∞.

  14. Optimal Control of a Ballast-Stabilized Floating Wind Turbine

    DEFF Research Database (Denmark)

    Christiansen, Søren; Knudsen, Torben; Bak, Thomas

    2011-01-01

    Offshore wind energy capitalizes on the higher and less turbulent wind speeds at sea. The use of floating structures for deeper waters is being explored. The control objective is a tradeoff between power capture and fatigue, especially that produced by the oscillations caused by the reduced...... structural stiffness of a floating installation in combination with a coupling between the fore–aft motion of the tower and the blade pitch. To address this problem, the present paper models a ballast-stabilized floating wind turbine, and suggests a linear quadratic regulator (LQR) in combination with a wind...

  15. Model Predictive Control of Nonlinear Systems: Stability Region and Feasible Initial Control

    Institute of Scientific and Technical Information of China (English)

    Xiao-Bing Hu; Wen-Hua Chen

    2007-01-01

    This paper proposes a new method for model predictive control (MPC) of nonlinear systems to calculate stability region and feasible initial control profile/sequence, which are important to the implementations of MPC. Different from many existing methods,this paper distinguishes stability region from conservative terminal region. With global linearization, linear differential inclusion (LDI)and linear matrix inequality (LMI) techniques, a nonlinear system is transformed into a convex set of linear systems, and then the vertices of the set are used off-line to design the controller, to estimate stability region, and also to determine a feasible initial control profile/sequence. The advantages of the proposed method are demonstrated by simulation study.

  16. Online Learning ARMA Controllers With Guaranteed Closed-Loop Stability.

    Science.gov (United States)

    Sahin, Savas; Guzelis, Cuneyt

    2016-11-01

    This paper presents a novel online block adaptive learning algorithm for autoregressive moving average (ARMA) controller design based on the real data measured from the plant. The method employs ARMA input-output models both for the plant and the resulting closed-loop system. In a sliding window, the plant model parameters are identified first offline using a supervised learning algorithm minimizing an ε -insensitive and regularized identification error, which is the window average of the distances between the measured plant output and the model output for the input provided by the controller. The optimal controller parameters are then determined again offline for another sliding window as the solution to a constrained optimization problem, where the cost is the ε -insensitive and regularized output tracking error and the constraints that are linear inequalities of the controller parameters are imposed for ensuring the closed-loop system to be Schur stable. Not only the identification phase but also the controller design phase uses the input-output samples measured from the plant during online learning. In the developed online controller design method, the controller parameters can always be kept in a parameter region providing Schur stability for the closed-loop system. The ε -insensitiveness provides robustness against disturbances, so does the regularization better generalization performance in the identification and the control. The method is tested on benchmark plants, including the inverted pendulum and dc motor models. The method is also tested on an emulated and also a real dc motor by online block adaptive learning ARMA controllers, in particular, Proportional-Integral-Derivative controllers.

  17. Stability of Closed Loop Controlled Repetitive Periodic System applied to control of CD-Player

    DEFF Research Database (Denmark)

    Odgaard, Peter Fogh; Stoustrup, Jakob; Andersen, Palle

    2005-01-01

    In this paper a criterion for stability of specific control scheme for handling linear dynamic control systems with repetitive periodic sensor faults is derived. The given system and control scheme are described and defined. By combining these with the lifting technique a necessary and sufficient...... the repetitive sensor faults (surface faults). The fault approximations are subsequently subtracted from the measurements, and the influence from these repetitive sensor faults are thereby removed from the computed control signals....... stability criterion is derived. This criterion is following applied to an example on a feature based control scheme for handling CD-players playing CDs with surface faults. This feature based control scheme is handling repetitive periodic sensor faults. The feature based control scheme approximates...

  18. High-precision temperature control and stabilization using a cryocooler.

    Science.gov (United States)

    Hasegawa, Yasuhiro; Nakamura, Daiki; Murata, Masayuki; Yamamoto, Hiroya; Komine, Takashi

    2010-09-01

    We describe a method for precisely controlling temperature using a Gifford-McMahon (GM) cryocooler that involves inserting fiber-reinforced-plastic dampers into a conventional cryosystem. Temperature fluctuations in a GM cryocooler without a large heat bath or a stainless-steel damper at 4.2 K are typically of the order of 200 mK. It is particularly difficult to control the temperature of a GM cryocooler at low temperatures. The fiber-reinforced-plastic dampers enabled us to dramatically reduce temperature fluctuations at low temperatures. A standard deviation of the temperature fluctuations of 0.21 mK could be achieved when the temperature was controlled at 4.200 0 K using a feedback temperature control system with two heaters. Adding the dampers increased the minimum achievable temperature from 3.2 to 3.3 K. Precise temperature control between 4.200 0 and 300.000 K was attained using the GM cryocooler, and the standard deviation of the temperature fluctuations was less than 1.2 mK even at 300 K. This technique makes it possible to control and stabilize the temperature using a GM cryocooler.

  19. Stability of XIST repression in relation to genomic imprinting following global genome demethylation in a human cell line

    OpenAIRE

    E.S.S. de Araújo; Vasques, L.R.; Stabellini,R.; A.C.V. Krepischi; Pereira, L.V.

    2014-01-01

    DNA methylation is essential in X chromosome inactivation and genomic imprinting, maintaining repression of XIST in the active X chromosome and monoallelic repression of imprinted genes. Disruption of the DNA methyltransferase genes DNMT1 and DNMT3B in the HCT116 cell line (DKO cells) leads to global DNA hypomethylation and biallelic expression of the imprinted gene IGF2 but does not lead to reactivation of XIST expression, suggesting thatXIST repression is due to a more stable epigenetic mar...

  20. 77 FR 39206 - Public Hearing on Proposed Rule for Heavy Vehicle Electronic Stability Control Systems

    Science.gov (United States)

    2012-07-02

    ... Vehicle Electronic Stability Control Systems AGENCY: National Highway Traffic Safety Administration (NHTSA... No. 136, Electronic Stability Control Systems for Heavy Vehicles (77 FR 30766). The standard would... kilograms (26,000 pounds), to be equipped with an electronic stability control (ESC) system that meets...

  1. 77 FR 30765 - Federal Motor Vehicle Safety Standards; Electronic Stability Control Systems for Heavy Vehicles

    Science.gov (United States)

    2012-05-23

    ... CFR Part 571 Federal Motor Vehicle Safety Standards; Electronic Stability Control Systems for Heavy... 571 RIN 2127-AK97 Federal Motor Vehicle Safety Standards; Electronic Stability Control Systems for... a new Federal Motor Vehicle Safety Standard No. 136 to require electronic stability control (ESC...

  2. 76 FR 49532 - Federal Motor Vehicle Safety Standards; Electronic Stability Control; Technical Report on the...

    Science.gov (United States)

    2011-08-10

    ... National Highway Traffic Safety Administration Federal Motor Vehicle Safety Standards; Electronic Stability Control; Technical Report on the Effectiveness of Electronic Stability Control Systems for Cars and LTVs... Technical Report on its existing Safety Standard 126, Electronic Stability Control Systems. The report's...

  3. Temporary stabilization of air pollution control residues using carbonation.

    Science.gov (United States)

    Zhang, Hua; He, Pin-Jing; Shao, Li-Ming; Lee, Duu-Jong

    2008-01-01

    Carbonation presents a good prospect for stabilizing alkaline waste materials. The risk of metal leaching from carbonated waste was investigated in the present study; in particular, the effect of the carbonation process and leachate pH on the leaching toxicity of the alkaline air pollution control (APC) residues from municipal solid waste incinerator was evaluated. The pH varying test was conducted to characterize the leaching characteristics of the raw and carbonated residue over a broad range of pH. Partial least square modeling and thermodynamic modeling using Visual MINTEQ were applied to highlight the significant process parameters that controlled metal leaching from the carbonated residue. By lowering the pH to 8-11, the carbonation process reduced markedly the leaching toxicity of the alkaline APC residue; however, the treated APC residue showed similar potential risk of heavy metal release as the raw ash when subjected to an acid shock. The carbonated waste could, thereby, not be disposed of safely. Nonetheless, carbonation could be applied as a temporary stabilization process for heavy metals in APC residues in order to reduce the leaching risk during its transportation and storage before final disposal.

  4. Stability investigation of an airfoil section with active flap control

    DEFF Research Database (Denmark)

    Bergami, Leonardo; Gaunaa, Mac

    2010-01-01

    This work presents a method to determine flutter and divergence instability limits for a two-dimensional (2-D) airfoil section fitted with an actively controlled trailing edge flap. This flap consists of a deformable trailing edge, which deformation is governed by control algorithms based...... for fatigue load alleviation. The structural model of the 2-D airfoil section contains three degrees of freedom: heave translation, pitch rotation and flap deflection. A potential flow model provides the aerodynamic forces and their distribution. The unsteady aerodynamics are described using an indicial...... function approximation. Stability of the full aeroservoelastic system is determined through eigenvalue analysis by state-space formulation of the indicial approximation. Validation is carried out against an implementation of the recursive method by Theodorsen and Garrick for flexure-torsion-aileron flutter...

  5. COMSAC: Computational Methods for Stability and Control. Part 2

    Science.gov (United States)

    Fremaux, C. Michael (Compiler); Hall, Robert M. (Compiler)

    2004-01-01

    The unprecedented advances being made in computational fluid dynamic (CFD) technology have demonstrated the powerful capabilities of codes in applications to civil and military aircraft. Used in conjunction with wind-tunnel and flight investigations, many codes are now routinely used by designers in diverse applications such as aerodynamic performance predictions and propulsion integration. Typically, these codes are most reliable for attached, steady, and predominantly turbulent flows. As a result of increasing reliability and confidence in CFD, wind-tunnel testing for some new configurations has been substantially reduced in key areas, such as wing trade studies for mission performance guarantees. Interest is now growing in the application of computational methods to other critical design challenges. One of the most important disciplinary elements for civil and military aircraft is prediction of stability and control characteristics. CFD offers the potential for significantly increasing the basic understanding, prediction, and control of flow phenomena associated with requirements for satisfactory aircraft handling characteristics.

  6. Controllability, observability, realizability, and stability of dynamic linear systems

    Directory of Open Access Journals (Sweden)

    John M. Davis

    2009-03-01

    Full Text Available We develop a linear systems theory that coincides with the existing theories for continuous and discrete dynamical systems, but that also extends to linear systems defined on nonuniform time scales. The approach here is based on generalized Laplace transform methods (e.g. shifts and convolution from the recent work [13]. We study controllability in terms of the controllability Gramian and various rank conditions (including Kalman's in both the time invariant and time varying settings and compare the results. We explore observability in terms of both Gramian and rank conditions and establish related realizability results. We conclude by applying this systems theory to connect exponential and BIBO stability problems in this general setting. Numerous examples are included to show the utility of these results.

  7. Controllability, Observability, Reachability, and Stability of Dynamic Linear Systems

    CERN Document Server

    Jackson, Billy J; Gravagne, Ian A; Marks, Robert J

    2009-01-01

    We develop a linear systems theory that coincides with the existing theories for continuous and discrete dynamical systems, but that also extends to linear systems defined on nonuniform time domains. The approach here is based on generalized Laplace transform methods (e.g. shifts and convolution) from our recent work \\cite{DaGrJaMaRa}. We study controllability in terms of the controllability Gramian and various rank conditions (including Kalman's) in both the time invariant and time varying settings and compare the results. We also explore observability in terms of both Gramian and rank conditions as well as realizability results. We conclude by applying this systems theory to connect exponential and BIBO stability problems in this general setting. Numerous examples are included to show the utility of these results.

  8. Genome-health nutrigenomics and nutrigenetics: nutritional requirements or 'nutriomes' for chromosomal stability and telomere maintenance at the individual level.

    Science.gov (United States)

    Bull, Caroline; Fenech, Michael

    2008-05-01

    It is becoming increasingly evident that (a) risk for developmental and degenerative disease increases with more DNA damage, which in turn is dependent on nutritional status, and (b) the optimal concentration of micronutrients for prevention of genome damage is also dependent on genetic polymorphisms that alter the function of genes involved directly or indirectly in the uptake and metabolism of micronutrients required for DNA repair and DNA replication. The development of dietary patterns, functional foods and supplements that are designed to improve genome-health maintenance in individuals with specific genetic backgrounds may provide an important contribution to an optimum health strategy based on the diagnosis and individualised nutritional prevention of genome damage, i.e. genome health clinics. The present review summarises some of the recent knowledge relating to micronutrients that are associated with chromosomal stability and provides some initial insights into the likely nutritional factors that may be expected to have an impact on the maintenance of telomeres. It is evident that developing effective strategies for defining nutrient doses and combinations or 'nutriomes' for genome-health maintenance at the individual level is essential for further progress in this research field.

  9. The Second Subunit of DNA Polymerase Delta Is Required for Genomic Stability and Epigenetic Regulation1[OPEN

    Science.gov (United States)

    Cheng, Jinkui; Lai, Jinsheng; Gong, Zhizhong

    2016-01-01

    DNA polymerase δ plays crucial roles in DNA repair and replication as well as maintaining genomic stability. However, the function of POLD2, the second small subunit of DNA polymerase δ, has not been characterized yet in Arabidopsis (Arabidopsis thaliana). During a genetic screen for release of transcriptional gene silencing, we identified a mutation in POLD2. Whole-genome bisulfite sequencing indicated that POLD2 is not involved in the regulation of DNA methylation. POLD2 genetically interacts with Ataxia Telangiectasia-mutated and Rad3-related and DNA polymerase α. The pold2-1 mutant exhibits genomic instability with a high frequency of homologous recombination. It also exhibits hypersensitivity to DNA-damaging reagents and short telomere length. Whole-genome chromatin immunoprecipitation sequencing and RNA sequencing analyses suggest that pold2-1 changes H3K27me3 and H3K4me3 modifications, and these changes are correlated with the gene expression levels. Our study suggests that POLD2 is required for maintaining genome integrity and properly establishing the epigenetic markers during DNA replication to modulate gene expression. PMID:27208288

  10. Towards a typing strategy for Arcobacter species isolated from humans and animals and assessment of the in vitro genomic stability.

    Science.gov (United States)

    Douidah, Laid; De Zutter, Lieven; Baré, Julie; Houf, Kurt

    2014-04-01

    Arcobacter species have a widespread distribution with a broad range of animal hosts and environmental reservoirs, and are increasingly associated with human illness. To elucidate the routes of infection, several characterization methods such as pulsed-field gel electrophoresis (PFGE), amplified fragment-length polymorphism, and enterobacterial repetitive intergenic consensus (ERIC)-PCR have already been applied, but without proper validation or comparison. At present, no criterion standard typing method or strategy has been proposed. Therefore, after the validation of PFGE, those commonly applied typing methods were compared for the characterization of six human- and animal-associated Arcobacter species. With a limited number of isolates to be characterized, PFGE with restriction by KpnI is proposed as the first method of choice. However, ERIC-PCR represents a more convenient genomic fingerprinting technique when a large number of isolates is involved. Therefore, a first clustering of similar patterns obtained after ERIC-PCR, with a subsequent typing of some representatives per ERIC cluster by PFGE, is recommended. As multiple genotypes are commonly isolated from the same host and food, genomic plasticity has been suggested. The in vitro genomic stability of Arcobacter butzleri and A. cryaerophilus was assessed under two temperatures and two oxygen concentrations. Variability in the genomic profile of A. cryaerophilus was observed after different passages for different strains at 37°C under microaerobic conditions. The bias due to these genomic changes must be taken into account in the evaluation of the relationship of strains.

  11. Optimization of Fuzzy Logic Controller for Supervisory Power System Stabilizers

    Directory of Open Access Journals (Sweden)

    Y. A. Al-Turki

    2012-01-01

    Full Text Available This paper presents a powerful supervisory power system stabilizer (PSS using an adaptive fuzzy logic controller driven by an adaptive fuzzy set (AFS. The system under study consists of two synchronous generators, each fitted with a PSS, which are connected via double transmission lines. Different types of PSS-controller techniques are considered. The proposed genetic adaptive fuzzy logic controller (GAFLC-PSS, using 25 rules, is compared with a static fuzzy logic controller (SFLC driven by a fixed fuzzy set (FFS which has 49 rules. Both fuzzy logic controller (FLC algorithms utilize the speed error and its rate of change as an input vector. The adaptive FLC algorithm uses a genetic algorithmto tune the parameters of the fuzzy set of each PSS. The FLC’s are simulated and tested when the system is subjected to different disturbances under a wide range of operating points. The proposed GAFLC using AFS reduced the computational time of the FLC, where the number of rules is reduced from 49 to 25 rules. In addition, the proposed adaptive FLC driven by a genetic algorithm also reduced the complexity of the fuzzy model, while achieving a good dynamic response of the system under study.

  12. Estimation of Stability and Control Derivatives of an F-15

    Science.gov (United States)

    Smith, Mark; Moes, Tim

    2006-01-01

    A technique for real-time estimation of stability and control derivatives (derivatives of moment coefficients with respect to control-surface deflection angles) was used to support a flight demonstration of a concept of an indirect-adaptive intelligent flight control system (IFCS). Traditionally, parameter identification, including estimation of stability and control derivatives, is done post-flight. However, for the indirect-adaptive IFCS concept, parameter identification is required during flight so that the system can modify control laws for a damaged aircraft. The flight demonstration was carried out on a highly modified F-15 airplane (see Figure 1). The main objective was to estimate the stability and control derivatives of the airplane in nearly real time. A secondary goal was to develop a system to automatically assess the quality of the results, so as to be able to tell a learning neural network which data to use. Parameter estimation was performed by use of Fourier-transform regression (FTR) a technique developed at NASA Langley Research Center. FTR is an equation- error technique that operates in the frequency domain. Data are put into the frequency domain by use of a recursive Fourier transform for a discrete frequency set. This calculation simplifies many subsequent calculations, removes biases, and automatically filters out data beyond the chosen frequency range. FTR as applied here was tailored to work with pilot inputs, which produce correlated surface positions that prevent accurate parameter estimates, by replacing half the derivatives with predicted values. FTR was also set up to work only on a recent window of data, to accommodate changes in flight condition. A system of confidence measures was developed to identify quality-parameter estimates that a learning neural network could use. This system judged the estimates primarily on the basis of their estimated variances and of the level of aircraft response. The resulting FTR system was implemented

  13. Sex differences in brain aromatase activity: genomic and non-genomic controls

    Directory of Open Access Journals (Sweden)

    Jacques eBalthazart

    2011-09-01

    Full Text Available Aromatization of testosterone into estradiol in the preoptic area plays a critical role in the activation of male copulation in quail and in many other vertebrate species. Aromatase expression in quail and in other birds is higher than in rodents and other mammals, which has facilitated the study of the controls and functions of this enzyme. Over relatively long time periods (days to months, brain aromatase activity and transcription are markedly (4-6 fold increased by genomic actions of sex steroids. Initial work indicated that the preoptic aromatase activity is higher in males than in females and it was hypothesized that this differential production of estrogen could be a critical factor responsible for the lack of behavioral activation in females. Subsequent studies revealed, however, that this enzymatic sex difference might contribute but is not sufficient to explain the sex difference in behavior. Studies of aromatase activity, immunoreactivity and mRNA concentrations revealed that sex differences observed when measuring enzymatic activity are not necessarily observed when one measures mRNA concentrations. Discrepancies potentially reflect post-translational controls of the enzymatic activity. Aromatase activity in quail brain homogenates is rapidly inhibited by phosphorylation processes. Similar rapid inhibitions occur in hypothalamic explants maintained in vitro and exposed to agents affecting intracellular calcium concentrations or to glutamate agonists. Rapid changes in aromatase activity have also been observed in vivo following sexual interactions or exposure to short-term restraint stress and these rapid changes in estrogen production modulate expression of male sexual behaviors. These data suggest that brain estrogens display most if not all characteristics of neuromodulators if not neurotransmitters. Many questions remain however concerning the mechanisms controlling these rapid changes in estrogen production and their behavioral

  14. Maximum likelihood identification of aircraft stability and control derivatives

    Science.gov (United States)

    Mehra, R. K.; Stepner, D. E.; Tyler, J. S.

    1974-01-01

    Application of a generalized identification method to flight test data analysis. The method is based on the maximum likelihood (ML) criterion and includes output error and equation error methods as special cases. Both the linear and nonlinear models with and without process noise are considered. The flight test data from lateral maneuvers of HL-10 and M2/F3 lifting bodies are processed to determine the lateral stability and control derivatives, instrumentation accuracies, and biases. A comparison is made between the results of the output error method and the ML method for M2/F3 data containing gusts. It is shown that better fits to time histories are obtained by using the ML method. The nonlinear model considered corresponds to the longitudinal equations of the X-22 VTOL aircraft. The data are obtained from a computer simulation and contain both process and measurement noise. The applicability of the ML method to nonlinear models with both process and measurement noise is demonstrated.

  15. Effect of electronic stability control on automobile crash risk.

    Science.gov (United States)

    Farmer, Charles

    2004-12-01

    Per vehicle crash involvement rates were compared for otherwise identical vehicle models with and without electronic stability control (ESC) systems. ESC was found to affect single-vehicle crashes to a greater extent than multiple-vehicle crashes, and crashes with fatal injuries to a greater extent than less severe crashes. Based on all police-reported crashes in 7 states over 2 years, ESC reduced single-vehicle crash involvement risk by approximately 41 percent (95 percent confidence limits 3348) and single-vehicle injury crash involvement risk by 41 percent (2752). This translates to an estimated 7 percent reduction in overall crash involvement risk (310) and a 9 percent reduction in overall injury crash involvement risk (314). Based on all fatal crashes in the United States over 3 years, ESC was found to have reduced single-vehicle fatal crash involvement risk by 56 percent (3968). This translates to an estimated 34 percent reduction in overall fatal crash involvement risk (2145).

  16. Landslide Geohazard Monitoring, Early Warning and Stabilization Control Methods

    Directory of Open Access Journals (Sweden)

    Bednarczyk Zbigniew

    2014-03-01

    Full Text Available This paper is a presentation of landslide monitoring, early warning and remediation methods recommended for the Polish Carpathians. Instrumentation included standard and automatic on-line measurements with the real-time transfer of data to an Internet web server. The research was funded through EU Innovative Economy Programme and also by the SOPO Landslide Counteraction Project. The landslides investigated were characterized by relatively low rates of the displacements. These ranged from a few millimetres to several centimetres per year. Colluviums of clayey flysch deposits were of a soil-rock type with a very high plasticity and moisture content. The instrumentation consisted of 23 standard inclinometers set to depths of 5-21 m. The starting point of monitoring measurements was in January 2006. These were performed every 1-2 months over the period of 8 years. The measurements taken detected displacements from several millimetres to 40 cm set at a depth of 1-17 m. The modern, on-line monitoring and early warning system was installed in May 2010. The system is the first of its kind in Poland and only one of several such real-time systems in the world. The installation was working with the Local Road Authority in Gorlice. It contained three automatic field stations for investigation of landslide parameters to depths of 12-16 m and weather station. In-place tilt transducers and innovative 3D continuous inclinometer systems with sensors located every 0.5 m were used. It has the possibility of measuring a much greater range of movements compared to standard systems. The conventional and real-time data obtained provided a better recognition of the triggering parameters and the control of geohazard stabilizations. The monitoring methods chosen supplemented by numerical modelling could lead to more reliable forecasting of such landslides and could thus provide better control and landslide remediation possibilities also to stabilization works which

  17. Landslide Geohazard Monitoring, Early Warning and Stabilization Control Methods

    Science.gov (United States)

    Bednarczyk, Zbigniew

    2014-03-01

    This paper is a presentation of landslide monitoring, early warning and remediation methods recommended for the Polish Carpathians. Instrumentation included standard and automatic on-line measurements with the real-time transfer of data to an Internet web server. The research was funded through EU Innovative Economy Programme and also by the SOPO Landslide Counteraction Project. The landslides investigated were characterized by relatively low rates of the displacements. These ranged from a few millimetres to several centimetres per year. Colluviums of clayey flysch deposits were of a soil-rock type with a very high plasticity and moisture content. The instrumentation consisted of 23 standard inclinometers set to depths of 5-21 m. The starting point of monitoring measurements was in January 2006. These were performed every 1-2 months over the period of 8 years. The measurements taken detected displacements from several millimetres to 40 cm set at a depth of 1-17 m. The modern, on-line monitoring and early warning system was installed in May 2010. The system is the first of its kind in Poland and only one of several such real-time systems in the world. The installation was working with the Local Road Authority in Gorlice. It contained three automatic field stations for investigation of landslide parameters to depths of 12-16 m and weather station. In-place tilt transducers and innovative 3D continuous inclinometer systems with sensors located every 0.5 m were used. It has the possibility of measuring a much greater range of movements compared to standard systems. The conventional and real-time data obtained provided a better recognition of the triggering parameters and the control of geohazard stabilizations. The monitoring methods chosen supplemented by numerical modelling could lead to more reliable forecasting of such landslides and could thus provide better control and landslide remediation possibilities also to stabilization works which prevent landslides.

  18. Large-scale contamination of microbial isolate genomes by Illumina PhiX control.

    Science.gov (United States)

    Mukherjee, Supratim; Huntemann, Marcel; Ivanova, Natalia; Kyrpides, Nikos C; Pati, Amrita

    2015-01-01

    With the rapid growth and development of sequencing technologies, genomes have become the new go-to for exploring solutions to some of the world's biggest challenges such as searching for alternative energy sources and exploration of genomic dark matter. However, progress in sequencing has been accompanied by its share of errors that can occur during template or library preparation, sequencing, imaging or data analysis. In this study we screened over 18,000 publicly available microbial isolate genome sequences in the Integrated Microbial Genomes database and identified more than 1000 genomes that are contaminated with PhiX, a control frequently used during Illumina sequencing runs. Approximately 10% of these genomes have been published in literature and 129 contaminated genomes were sequenced under the Human Microbiome Project. Raw sequence reads are prone to contamination from various sources and are usually eliminated during downstream quality control steps. Detection of PhiX contaminated genomes indicates a lapse in either the application or effectiveness of proper quality control measures. The presence of PhiX contamination in several publicly available isolate genomes can result in additional errors when such data are used in comparative genomics analyses. Such contamination of public databases have far-reaching consequences in the form of erroneous data interpretation and analyses, and necessitates better measures to proofread raw sequences before releasing them to the broader scientific community.

  19. Pitch Motion Stabilization by Propeller Speed Control Using Statistical Controller Design

    DEFF Research Database (Denmark)

    Nakatani, Toshihiko; Blanke, Mogens; Galeazzi, Roberto

    2006-01-01

    This paper describes dynamics analysis of a small training boat and a possibility of ship pitch stabilization by control of propeller speed. After upgrading the navigational system of an actual small training boat, in order to identify the model of the ship, the real data collected by sea trials...

  20. PARTIAL STABILIZATION OF A CLASS OF CONTINUOUS NONLINEAR CONTROL SYSTEMS WITH SEPARATED VARIABLES

    Institute of Scientific and Technical Information of China (English)

    Jigui JIAN; Xiaoxin LIAO

    2005-01-01

    In this paper, the partial stabilization problem for a class of nonlinear continuous control systems with separated variables is investigated. Several stabilizing controllers are constructed based on the partial stability theory of Lyapunov and the property of M-matrix, and some of these stabilizing controllers are only related to partial state variables. The controllers constructed here are shown to guarantee partial asymptotic stability of the closed-loop systems and these sufficient conditions may give some instructions to actual engineering application. A example is also given to illustrate the design method.

  1. The bornavirus-derived human protein EBLN1 promotes efficient cell cycle transit, microtubule organisation and genome stability

    Science.gov (United States)

    Myers, Katie N.; Barone, Giancarlo; Ganesh, Anil; Staples, Christopher J.; Howard, Anna E.; Beveridge, Ryan D.; Maslen, Sarah; Skehel, J. Mark; Collis, Spencer J.

    2016-01-01

    It was recently discovered that vertebrate genomes contain multiple endogenised nucleotide sequences derived from the non-retroviral RNA bornavirus. Strikingly, some of these elements have been evolutionary maintained as open reading frames in host genomes for over 40 million years, suggesting that some endogenised bornavirus-derived elements (EBL) might encode functional proteins. EBLN1 is one such element established through endogenisation of the bornavirus N gene (BDV N). Here, we functionally characterise human EBLN1 as a novel regulator of genome stability. Cells depleted of human EBLN1 accumulate DNA damage both under non-stressed conditions and following exogenously induced DNA damage. EBLN1-depleted cells also exhibit cell cycle abnormalities and defects in microtubule organisation as well as premature centrosome splitting, which we attribute in part, to improper localisation of the nuclear envelope protein TPR. Our data therefore reveal that human EBLN1 possesses important cellular functions within human cells, and suggest that other EBLs present within vertebrate genomes may also possess important cellular functions. PMID:27739501

  2. Stability Problems for Chua System with One Linear Control

    Directory of Open Access Journals (Sweden)

    Camelia Pop Arieşanu

    2013-01-01

    Full Text Available A Hamilton-Poisson realization and some stability problems for a dynamical system arisen from Chua system are presented. The stability and dynamics of a linearized smooth version of the Chua system are analyzed using the Hamilton-Poisson formalism. This geometrical approach allows to deduce the nonlinear stabilization near different equilibria.

  3. Improvement of Power System Stability using Artificial Neural Network based HVDC Controls

    Directory of Open Access Journals (Sweden)

    Nagu Bhookya

    2013-06-01

    Full Text Available In this paper, investigation is carried out for the improvement of power system stability by utilizing auxiliary controls for controlling HVDC power flow. The current controller model and the line dynamics are considered in the stability analysis. Transient stability analysis is done on a multi-machine system, where, a neural network controller is developed to improve the stability of the power system and to improve the response time of the controller to the changing conditions in power system. The results show the application of the neural network controller in AC-DC power systems.

  4. Stability and Speed Control of a Series-Wound DC Motor

    Science.gov (United States)

    Khoroshun, A. S.

    2016-07-01

    A speed control for a series-wound DC motor is proposed. It is shown that steady-state rotation is stabile and robust. Stability is analyzed using a quadratic Lyapunov function. Its explicit expression is derived

  5. Studies on the effects of persistent RNA priming on DNA replication and genomic stability

    OpenAIRE

    Stuckey, Ruth

    2014-01-01

    [EN]: DNA replication and transcription take place on the same DNA template, and the correct interplay between these processes ensures faithful genome duplication. DNA replication must be highly coordinated with other cell cycle events, such as segregation of fully replicated DNA in order to maintain genomic integrity. Transcription generates RNA:DNA hybrids, transient intermediate structures that are degraded by the ribonuclease H (RNaseH) class of enzymes. RNA:DNA hybrids can form R-loops, ...

  6. Studies on the effects of persistent RNA priming on DNA replication and genomic stability

    OpenAIRE

    Stuckey, Ruth

    2014-01-01

    [EN]: DNA replication and transcription take place on the same DNA template, and the correct interplay between these processes ensures faithful genome duplication. DNA replication must be highly coordinated with other cell cycle events, such as segregation of fully replicated DNA in order to maintain genomic integrity. Transcription generates RNA:DNA hybrids, transient intermediate structures that are degraded by the ribonuclease H (RNaseH) class of enzymes. RNA:DNA hybrids can form R-loops, ...

  7. Patient-controlled encrypted genomic data: an approach to advance clinical genomics

    Directory of Open Access Journals (Sweden)

    Trakadis Yannis J

    2012-07-01

    Full Text Available Abstract Background The revolution in DNA sequencing technologies over the past decade has made it feasible to sequence an individual’s whole genome at a relatively low cost. The potential value of the information generated by genomic technologies for medicine and society is enormous. However, in order for exome sequencing, and eventually whole genome sequencing, to be implemented clinically, a number of major challenges need to be overcome. For instance, obtaining meaningful informed-consent, managing incidental findings and the great volume of data generated (including multiple findings with uncertain clinical significance, re-interpreting the genomic data and providing additional counselling to patients as genetic knowledge evolves are issues that need to be addressed. It appears that medical genetics is shifting from the present “phenotype-first” medical model to a “data-first” model which leads to multiple complexities. Discussion This manuscript discusses the different challenges associated with integrating genomic technologies into clinical practice and describes a “phenotype-first” approach, namely, “Individualized Mutation-weighed Phenotype Search”, and its benefits. The proposed approach allows for a more efficient prioritization of the genes to be tested in a clinical lab based on both the patient’s phenotype and his/her entire genomic data. It simplifies “informed-consent” for clinical use of genomic technologies and helps to protect the patient’s autonomy and privacy. Overall, this approach could potentially render widespread use of genomic technologies, in the immediate future, practical, ethical and clinically useful. Summary The “Individualized Mutation-weighed Phenotype Search” approach allows for an incremental integration of genomic technologies into clinical practice. It ensures that we do not over-medicalize genomic data but, rather, continue our current medical model which is based on serving

  8. Stabilizing control for a pulsatile cardiovascular mathematical model.

    Science.gov (United States)

    de los Reyes, Aurelio A; Jung, Eunok; Kappel, Franz

    2014-06-01

    In this paper, we develop a pulsatile model for the cardiovascular system which describes the reaction of this system to a submaximal constant workload imposed on a person at a bicycle ergometer test after a period of rest. Furthermore, the model should allow to use measurements for the pulsatile pressure in fingertips which provide information on the diastolic and the systolic pressure for parameter estimation. Based on the assumption that the baroreceptor loop is the essential control loop in this case, we design a stabilizing feedback control for the pulsatile model which is obtained by solving a linear-quadratic regulator problem for the linearization of a non-pulsatile counterpart of the pulsatile model. We also investigate the behavior of the model with respect to changes in the weight of the term in the cost functional for the linear-quadratic regulator problem which penalizes the deviation of the momentary pressure in the aorta from the pressure at the stationary situation which should be obtained.

  9. Role of Intrinsic and Reflexive Dynamics in the Control of Spinal Stability

    OpenAIRE

    Moorhouse, Kevin Michael

    2005-01-01

    Role of Intrinsic and Reflexive Dynamics in the Control of Spinal Stability Kevin M. Moorhouse Abstract Spinal stability describes the ability of the neuromuscular system to maintain equilibrium in the presence of kinematic and control variability, and may play an important role in the etiology of low-back disorders (LBDs). The primary mechanism for the neuromuscular control of spinal stability is the recruitment and control of active paraspinal muscle stiffness (i.e., trunk stif...

  10. Non-catalytic Roles for XPG with BRCA1 and BRCA2 in Homologous Recombination and Genome Stability

    DEFF Research Database (Denmark)

    Trego, Kelly S.; Groesser, Torsten; Davalos, Albert R.;

    2016-01-01

    about how XPG loss results in this devastating disease. We identify XPG as a partner of BRCA1 and BRCA2 in maintaining genomic stability through homologous recombination (HRR). XPG depletion causes DNA double-strand breaks, chromosomal abnormalities, cell-cycle delays, defective HRR, inability...... to overcome replication fork stalling,and replication stress. XPG directly interacts withBRCA2, RAD51, and PALB2, and XPG depletion reduces their chromatin binding and subsequent RAD51 foci formation. Upstream in HRR, XPG interacts directly with BRCA1. Its depletion causes BRCA1 hyper...

  11. PID Controller Stabilization for First-order Integral Processes with Time Delay

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Due to the widespread application of the PID controller in industrial control systems, it is desirable to know the complete set of all the stabilizing PID controllers for a given plant before the controller design and tuning. In this paper,the stabilization problems of the classical proportionalintegral-derivative (PID) controller and the singleparameter PID controller (containing only one adjustable parameter) for integral processes with time delay are investigated, respectively. The complete set of stabilizing parameters of the classical PID controller is determined using a version of the Hermite-Biehler Theorem applicable to quasipolynomials. Since the stabilization problem of the single-parameter PID controller cannot be treated by the Hermite-Biehler Theorem, a simple method called duallocus diagram is employed to derive the stabilizing range of the single-parameter PID controller. These results provide insight into the tuning of the PID controllers.

  12. A Practical Fast Acting Control Scheme For Fuzzy Logic-Based Voltage Stabilization Control

    Directory of Open Access Journals (Sweden)

    E. E. EL-Kholy

    2005-03-01

    Full Text Available This paper presents a simplified control model for stabilizing a load voltage using a switched reactor in parallel with a fixed capacitor of static VAR compensator. Two IGBT’s are used to control the reactance of the switched reactor. A uniform pulse width modulation is used for controlling the two switches. The compensator has a simple control circuit and structure. A complete modeling and numerical simulation for the proposed systems is presented. A high speed Digital Signal Processor is used for implementing proportional-integral (PI and fuzzy load voltage controllers. Experimental results indicate the superiority of fuzzy logic control over the conventional proportional-integral control method. Simulation results are reported and proved to be in good agreement with the relevant experimental results.

  13. Stability and control of wind farms in power systems

    Energy Technology Data Exchange (ETDEWEB)

    Jauch, C.

    2006-10-15

    The Ph.D. project 'Stability and Control of Wind Farms in Power Systems' deals with some selected problems related to wind power in power systems. With increasing wind power penetration, wind turbines substitute the power production of conventional power plants. Therefore, wind turbines also have to take over the power system stabilisation and control tasks, that were traditionally carried out by conventional power plants. Out of the many aspects related to this problem, this project focuses on transient fault ride-through and power system stabilisation. The selection of turbine types considered in this project is limited to active-stall turbines and variable speed, variable pitch turbines with gearboxes and full-scale converter-connected synchronous generators. As a basis for the project, a study into the state of the art is conducted at the beginning of the project. Grid connection requirements that were in force, or published as drafts, at the time, and scientific literature related to the topic, are studied. The project is based on simulations of wind turbines in a power system simulations tool. Some of the models used in this project were readily available prior to the project; the development of others is part of the project. The most extensive modelling work deals with the design of the electrical part of the variable speed turbine and its controls. To simulate realistic grid operation the wind turbine models are connected to an aggregated model of the Nordic power system. For that purpose the Nordic power system model, which was available prior to the project, is extended with a realistic feeder configuration. It is commonly demanded from modern wind turbines, that they must not disconnect in case of transient faults. Therefore, controllers are designed that enable the two turbine types to ride through transient faults. With these transient fault controllers the wind turbines can stay connected to the grid, such that their generation capacity is

  14. Stabilizing feedback controls for nonlinear Hamiltonian systems and nonconservative bilinear systems in elasticity

    Science.gov (United States)

    Singh, S. N.

    1982-03-01

    Using the invariance principle of LaSalle (1962) sufficient conditions for the existence of linear and nonlinear control laws for local and global asymptotic stability of nonlinear Hamiltonian systems are derived. An instability theorem is also presented which identifies the control laws from the given class which cannot achieve asymptotic stability. Some of the stability results are based on certain results for the univalence of nonlinear maps. A similar approach for the stabilization of bilinear systems which include nonconservative systems in elasticity is used and a necessary and sufficient condition for stabilization is obtained. An application to attitude control of a gyrostat Satellite is presented.

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

    DEFF Research Database (Denmark)

    Jbabdi, Myriam; Boissy, Patrice; Hamel, Mathieu

    2008-01-01

    . Results showed that a motor learning effect was present as the participants optimized their weight-shifting strategy through the first three trials of each task using the visual biofeedback provided on their COP. Reliable measures of control of postural stability at performance-based LOS can be obtained...... during weight-shifting postural tasks with real time visual feedback of the COP displacement to assess postural stability of community-living older adults. In order to obtain reliable results, a learning phase allowing subjects to learn how to control their COP displacement is needed.......BACKGROUND: Balance disability measurements routinely used to identify fall risks in frail populations have limited value in the early detection of postural stability deficits in community-living older adults. The objectives of the study were to 1) measure performance-based limits of stability (LOS...

  16. New functions of Ctf18-RFC in preserving genome stability outside its role in sister chromatid cohesion.

    Science.gov (United States)

    Gellon, Lionel; Razidlo, David F; Gleeson, Olive; Verra, Lauren; Schulz, Danae; Lahue, Robert S; Freudenreich, Catherine H

    2011-02-10

    Expansion of DNA trinucleotide repeats causes at least 15 hereditary neurological diseases, and these repeats also undergo contraction and fragility. Current models to explain this genetic instability invoke erroneous DNA repair or aberrant replication. Here we show that CAG/CTG tracts are stabilized in Saccharomyces cerevisiae by the alternative clamp loader/unloader Ctf18-Dcc1-Ctf8-RFC complex (Ctf18-RFC). Mutants in Ctf18-RFC increased all three forms of triplet repeat instability--expansions, contractions, and fragility--with effect over a wide range of allele lengths from 20-155 repeats. Ctf18-RFC predominated among the three alternative clamp loaders, with mutants in Elg1-RFC or Rad24-RFC having less effect on trinucleotide repeats. Surprisingly, chl1, scc1-73, or scc2-4 mutants defective in sister chromatid cohesion (SCC) did not increase instability, suggesting that Ctf18-RFC protects triplet repeats independently of SCC. Instead, three results suggest novel roles for Ctf18-RFC in facilitating genomic stability. First, genetic instability in mutants of Ctf18-RFC was exacerbated by simultaneous deletion of the fork stabilizer Mrc1, but suppressed by deletion of the repair protein Rad52. Second, single-cell analysis showed that mutants in Ctf18-RFC had a slowed S phase and a striking G2/M accumulation, often with an abnormal multi-budded morphology. Third, ctf18 cells exhibit increased Rad52 foci in S phase, often persisting into G2, indicative of high levels of DNA damage. The presence of a repeat tract greatly magnified the ctf18 phenotypes. Together these results indicate that Ctf18-RFC has additional important functions in preserving genome stability, besides its role in SCC, which we propose include lesion bypass by replication forks and post-replication repair.

  17. New functions of Ctf18-RFC in preserving genome stability outside its role in sister chromatid cohesion.

    Directory of Open Access Journals (Sweden)

    Lionel Gellon

    Full Text Available Expansion of DNA trinucleotide repeats causes at least 15 hereditary neurological diseases, and these repeats also undergo contraction and fragility. Current models to explain this genetic instability invoke erroneous DNA repair or aberrant replication. Here we show that CAG/CTG tracts are stabilized in Saccharomyces cerevisiae by the alternative clamp loader/unloader Ctf18-Dcc1-Ctf8-RFC complex (Ctf18-RFC. Mutants in Ctf18-RFC increased all three forms of triplet repeat instability--expansions, contractions, and fragility--with effect over a wide range of allele lengths from 20-155 repeats. Ctf18-RFC predominated among the three alternative clamp loaders, with mutants in Elg1-RFC or Rad24-RFC having less effect on trinucleotide repeats. Surprisingly, chl1, scc1-73, or scc2-4 mutants defective in sister chromatid cohesion (SCC did not increase instability, suggesting that Ctf18-RFC protects triplet repeats independently of SCC. Instead, three results suggest novel roles for Ctf18-RFC in facilitating genomic stability. First, genetic instability in mutants of Ctf18-RFC was exacerbated by simultaneous deletion of the fork stabilizer Mrc1, but suppressed by deletion of the repair protein Rad52. Second, single-cell analysis showed that mutants in Ctf18-RFC had a slowed S phase and a striking G2/M accumulation, often with an abnormal multi-budded morphology. Third, ctf18 cells exhibit increased Rad52 foci in S phase, often persisting into G2, indicative of high levels of DNA damage. The presence of a repeat tract greatly magnified the ctf18 phenotypes. Together these results indicate that Ctf18-RFC has additional important functions in preserving genome stability, besides its role in SCC, which we propose include lesion bypass by replication forks and post-replication repair.

  18. Control of Collagen Triple Helix Stability by Phosphorylation.

    Science.gov (United States)

    Acevedo-Jake, Amanda M; Ngo, Daniel H; Hartgerink, Jeffrey D

    2017-03-10

    The phosphorylation of the collagen triple helix plays an important role in collagen synthesis, assembly, signaling, and immune response, although no reports detailing the effect this modification has on the structure and stability of the triple helix exist. Here we investigate the changes in stability and structure resulting from the phosphorylation of collagen. Additionally, the formation of pairwise interactions between phosphorylated residues and lysine is examined. In all tested cases, phosphorylation increases helix stability. When charged-pair interactions are possible, stabilization via phosphorylation can play a very large role, resulting inasmuch as a 13.0 °C increase in triple helix stability. Two-dimensional NMR and molecular modeling are used to study the local structure of the triple helix. Our results suggest a mechanism of action for phosphorylation in the regulation of collagen and also expand upon our understanding of pairwise amino acid stabilization of the collagen triple helix.

  19. Using intelligent controller to enhance the walking stability of bipedal walking robot

    Science.gov (United States)

    Hsieh, Tsung-Che; Chang, Chia-Der

    2016-07-01

    This paper is to improve the stability issue of the bipedal walking robot. The study of robot's pivot joint constructs the driver system to control the implementation. First, a Proportion-Integral-Derivative (PID) controller is designed by which is used the concept of tuning parameter to achieve the stability of the system. Second, Fuzzy controller and tradition PID controller is used to maintain output. It improved original PID controller efficacy. Finally, Artificial Neuro-Fuzzy Inference System (ANFIS) is utilized which is made the controller to achieve self-studying and modify the effect which is completed by the intelligent controller. It improved bipedal robot's stability control of realization. The result is verified that the walking stability of the bipedal walking robot in Matlab/Simulink. The intelligent controller has achieved the desired position of motor joint and the target stability performance.

  20. Case-Control Genome-Wide Association Study of Attention-Deficit/Hyperactivity Disorder

    Science.gov (United States)

    Neale, Benjamin M.; Medland, Sarah; Ripke, Stephan; Anney, Richard J. L.; Asherson, Philip; Buitelaar, Jan; Franke, Barbara; Gill, Michael; Kent, Lindsey; Holmans, Peter; Middleton, Frank; Thapar, Anita; Lesch, Klaus-Peter; Faraone, Stephen V.; Daly, Mark; Nguyen, Thuy Trang; Schafer, Helmut; Steinhausen, Hans-Christoph; Reif, Andreas; Renner, Tobias J.; Romanos, Marcel; Romanos, Jasmin; Warnke, Andreas; Walitza, Susanne; Freitag, Christine; Meyer, Jobst; Palmason, Haukur; Rothenberger, Aribert; Hawi, Ziarih; Sergeant, Joseph; Roeyers, Herbert; Mick, Eric; Biederman, Joseph

    2010-01-01

    Objective: Although twin and family studies have shown attention-deficit/hyperactivity disorder (ADHD) to be highly heritable, genetic variants influencing the trait at a genome-wide significant level have yet to be identified. Thus additional genome-wide association studies (GWAS) are needed. Method: We used case-control analyses of 896 cases…

  1. Applications of Computational Methods for Dynamic Stability and Control Derivatives

    Science.gov (United States)

    Green, Lawrence L.; Spence, Angela M.

    2004-01-01

    Initial steps in the application o f a low-order panel method computational fluid dynamic (CFD) code to the calculation of aircraft dynamic stability and control (S&C) derivatives are documented. Several capabilities, unique to CFD but not unique to this particular demonstration, are identified and demonstrated in this paper. These unique capabilities complement conventional S&C techniques and they include the ability to: 1) perform maneuvers without the flow-kinematic restrictions and support interference commonly associated with experimental S&C facilities, 2) easily simulate advanced S&C testing techniques, 3) compute exact S&C derivatives with uncertainty propagation bounds, and 4) alter the flow physics associated with a particular testing technique from those observed in a wind or water tunnel test in order to isolate effects. Also presented are discussions about some computational issues associated with the simulation of S&C tests and selected results from numerous surface grid resolution studies performed during the course of the study.

  2. Robust Absolute Stability of General Interval Lur'e Type Nonlinear Control Systems

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In this paper, Lyapunov function method isused to study the robust absolute stability of general interval Lur'e type nonlinear control systems. As a result, algebraically sufficient conditions with interval matrix inequality form are obtained for the general interval Lur'e type nonlinear control systems, thus the relationship between the stability of symmetrical interval matrix and the robust absolute stability of general interval Lur'e type nonlinear control systems is established.

  3. Slx8 removes Pli1-dependent protein-SUMO conjugates including SUMOylated topoisomerase I to promote genome stability.

    Directory of Open Access Journals (Sweden)

    Roland Steinacher

    Full Text Available The SUMO-dependent ubiquitin ligase Slx8 plays key roles in promoting genome stability, including the processing of trapped Topoisomerase I (Top1 cleavage complexes and removal of toxic SUMO conjugates. We show that it is the latter function that constitutes Slx8's primary role in fission yeast. The SUMO conjugates in question are formed by the SUMO ligase Pli1, which is necessary for limiting spontaneous homologous recombination when Top1 is present. Surprisingly there is no requirement for Pli1 to limit recombination in the vicinity of a replication fork blocked at the programmed barrier RTS1. Notably, once committed to Pli1-mediated SUMOylation Slx8 becomes essential for genotoxin resistance, limiting both spontaneous and RTS1 induced recombination, and promoting normal chromosome segregation. We show that Slx8 removes Pli1-dependent Top1-SUMO conjugates and in doing so helps to constrain recombination at RTS1. Overall our data highlight how SUMOylation and SUMO-dependent ubiquitylation by the Pli1-Slx8 axis contribute in different ways to maintain genome stability.

  4. Slx8 Removes Pli1-Dependent Protein-SUMO Conjugates Including SUMOylated Topoisomerase I to Promote Genome Stability

    Science.gov (United States)

    Steinacher, Roland; Osman, Fekret; Lorenz, Alexander; Bryer, Claire; Whitby, Matthew C.

    2013-01-01

    The SUMO-dependent ubiquitin ligase Slx8 plays key roles in promoting genome stability, including the processing of trapped Topoisomerase I (Top1) cleavage complexes and removal of toxic SUMO conjugates. We show that it is the latter function that constitutes Slx8's primary role in fission yeast. The SUMO conjugates in question are formed by the SUMO ligase Pli1, which is necessary for limiting spontaneous homologous recombination when Top1 is present. Surprisingly there is no requirement for Pli1 to limit recombination in the vicinity of a replication fork blocked at the programmed barrier RTS1. Notably, once committed to Pli1-mediated SUMOylation Slx8 becomes essential for genotoxin resistance, limiting both spontaneous and RTS1 induced recombination, and promoting normal chromosome segregation. We show that Slx8 removes Pli1-dependent Top1-SUMO conjugates and in doing so helps to constrain recombination at RTS1. Overall our data highlight how SUMOylation and SUMO-dependent ubiquitylation by the Pli1-Slx8 axis contribute in different ways to maintain genome stability. PMID:23936535

  5. White spot syndrome virus (WSSV) genome stability maintained over six passages through three different penaeid shrimp species.

    Science.gov (United States)

    Sindhupriya, M; Saravanan, P; Otta, S K; Amarnath, C Bala; Arulraj, R; Bhuvaneswari, T; Praveena, P Ezhil; Jithendran, K P; Ponniah, A G

    2014-08-21

    White spot syndrome virus (WSSV) replicates rapidly, can be extremely pathogenic and is a common cause of mass mortality in cultured shrimp. Variable number tandem repeat (VNTR) sequences present in the open reading frame (ORF)94, ORF125 and ORF75 regions of the WSSV genome have been used widely as genetic markers in epidemiological studies. However, reports that VNTRs might evolve rapidly following even a single transmission through penaeid shrimp or other crustacean hosts have created confusion as to how VNTR data is interpreted. To examine VNTR stability again, 2 WSSV strains (PmTN4RU and LvAP11RU) with differing ORF94 tandem repeat numbers and slight differences in apparent virulence were passaged sequentially 6 times through black tiger shrimp Penaeus monodon, Indian white shrimp Feneropenaeus indicus or Pacific white leg shrimp Litopenaeus vannamei. PCR analyses to genotype the ORF94, ORF125 and ORF75 VNTRs did not identify any differences from either of the 2 parental WSSV strains after multiple passages through any of the shrimp species. These data were confirmed by sequence analysis and indicate that the stability of the genome regions containing these VNTRs is quite high at least for the WSSV strains, hosts and number of passages examined and that the VNTR sequences thus represent useful genetic markers for studying WSSV epidemiology.

  6. Control design for robust stability in linear regulators: Application to aerospace flight control

    Science.gov (United States)

    Yedavalli, R. K.

    1986-01-01

    Time domain stability robustness analysis and design for linear multivariable uncertain systems with bounded uncertainties is the central theme of the research. After reviewing the recently developed upper bounds on the linear elemental (structured), time varying perturbation of an asymptotically stable linear time invariant regulator, it is shown that it is possible to further improve these bounds by employing state transformations. Then introducing a quantitative measure called the stability robustness index, a state feedback conrol design algorithm is presented for a general linear regulator problem and then specialized to the case of modal systems as well as matched systems. The extension of the algorithm to stochastic systems with Kalman filter as the state estimator is presented. Finally an algorithm for robust dynamic compensator design is presented using Parameter Optimization (PO) procedure. Applications in a aircraft control and flexible structure control are presented along with a comparison with other existing methods.

  7. Asymptotic stabilization via control by interconnection of port-Hamiltonian systems

    NARCIS (Netherlands)

    Castaños, Fernando; Ortega, Romeo; Schaft, Arjan van der; Astolfi, Alessandro

    2009-01-01

    We study the asymptotic properties of control by interconnection, a passivity-based controller design methodology for stabilization of port-Hamiltonian systems. It is well-known that the method, in its basic form, imposes some unnatural controller initialization to yield asymptotic stability of the

  8. Stability analysis and design of fuzzy control system with bounded uncertain delays

    Institute of Scientific and Technical Information of China (English)

    Jianguo GUO; Juntao LI; Fengqi ZHOU; Jun ZHOU

    2005-01-01

    Fuzzy control problems for systems with bounded uncertain delays were studied.Based on Lyapunov stability theory and matrix theory,a nonlinear state feedback fuzzy controller was designed by linear matrix inequalities (LMI) approach,and the global exponential stability of the closed-loop system was strictly proved.For a fuzzy control system with bounded uncertain delays,under the global exponential stability condition which is reduced to p linear matrix inequalities,the controller guarantees stability performances of state variables.Finally,the simulation shows the validity of the method in this paper.

  9. Local controllability and stabilization of spacecraft attitude by two single-gimbal control moment gyros

    Institute of Scientific and Technical Information of China (English)

    Gui Haichao; Jin Lei; Xu Shijie

    2013-01-01

    The attitude control problem of a spacecraft underactuated by two single-gimbal control moment gyros (SGCMGs) is investigated. Small-time local controllability (STLC) of the attitude dynamics of the spacecraft-SGCMGs system is analyzed via nonlinear controllability theory. The conditions that guarantee STLC of the spacecraft attitude by two non-coaxial SGCMGs are obtained with the momentum of the SGCMGs as inputs, implying that the spacecraft attitude is STLC when the total angular momentum of the whole system is zero. Moreover, our results indi-cate that under the zero-momentum restriction, full attitude stabilization is possible for a spacecraft using two non-coaxial SGCMGs. For the case of two coaxial SGCMGs, the STLC property of the spacecraft cannot be determined. In this case, an improvement to the previous full attitude stabiliz-ing control law, which requires zero-momentum presumption, is proposed to account for the singu-larity of SGCMGs and enhance the steady state performance. Numerical simulation results demonstrate the effectiveness and advantages of the new control law.

  10. Static Synchronous Series Compensator Controller based on Fuzzy Logic Control for Power System Stabilization

    Directory of Open Access Journals (Sweden)

    Prechanon Kumkratug

    2011-01-01

    Full Text Available Problem statement: Modern power system consists of the complicated network of transmission lines and carries heavy demand. Thus they cause in the stability problem. Approach: Static Synchronous Series Compensator (SSSC is a power electronic based device that has the capability of controlling the power flow through a line. The series voltage injection model of SSSC is modeled into power flow equation and thus it is used to determine its control strategy. This study applies the fuzzy logic applies the SSSC to improve stability of power system. The mathematical model and control strategy of a SSSC are presented. The SSSC is represented by variable voltage injection with associate transformer leakage control to derive control strategy of SSSC. The swing curves of the three phase faulted power system without and with a SSSC is tested and compared in various cases. Results: The swing curve of the system with SSSC based fuzzy logic control has the less amplitude during the dynamic period. Conclusion: It was found from simulation results that SSSC can improve the power system oscillation after disturbance.

  11. Use of a general control simulation program to evaluate HVAC control stability

    Science.gov (United States)

    Zhang, Xinbang; Warren, M. L.

    1987-08-01

    A general process engineering simulation program for a microcomputer is used to evaluate the response of a cooling system to changes in load, set point, and controller tuning parameters to better understand the control stability of a supply air cooling system used in the Mobile Windows Thermal Test (MoWiTT) Facility. A detailed system model is built out of standard components and is used to plot the steady state performance under different operating conditions. The response of the cooling coil output depends strongly on the transport delays. For a system with a linear control valve, the process gain of the cooling coil increases rapidly as the valve flow fraction decreases. A system which is stable at mid-range is shown to become marginally unstable at the low end of the control range. The application of both an equal percentage valve and reheat are shown to improve the control response of the system under low cooling load conditions.

  12. HPLC FOR CONTROL STABILITY OF QUERCETIN INJECTABLE DOSAGE FORM

    Directory of Open Access Journals (Sweden)

    Martynov AV

    2016-12-01

    retention time and spectral relations in the UV region from the database of DB-2003 spectrums. HPLC analysis results show that the quercetin is stable in ampouled form under autoclave and storage and freshly diluted quercetin concentrate for infusion are identical. Quercetin aqueous solution which was stored at room temperature for 14 days in the light, turned out to be unstable. It was found that aqueous solutions of polysorbate-80 was full hydrolyzed to the initial compounds. Conclusions In this work the ability of quercetin’s perspective concentrates to be stable were checked. The stability of concentrates was determined by HPLC chromatograph "Millichrome A - 02» (SiChrom, Knauer. It is shown that the HPLC methods can be used to establish the smallest difference in the samples. The quercetin’s non-aqueous concentrate is capable of withstanding retorting and remains in standard indestructible state in nonaqueous media (glycerol, ethanol, polysorbate 80. Quercetin is unstable in aqueous solutions and are destroyed during prolonged storage. HPLC- chromatogram is presented in the article and show that gradient HPLC with UV- detection can be used for quality control of quercetin.

  13. Definition of Soybean Genomic Regions That Control Seed Phytoestrogen Amounts

    Directory of Open Access Journals (Sweden)

    Kassem My A.

    2004-01-01

    Full Text Available Soybean seeds contain large amounts of isoflavones or phytoestrogens such as genistein, daidzein, and glycitein that display biological effects when ingested by humans and animals. In seeds, the total amount, and amount of each type, of isoflavone varies by 5 fold between cultivars and locations. Isoflavone content and quality are one key to the biological effects of soy foods, dietary supplements, and nutraceuticals. Previously we had identified 6 loci (QTL controlling isoflavone content using 150 DNA markers. This study aimed to identify and delimit loci underlying heritable variation in isoflavone content with additional DNA markers. We used a recombinant inbred line (RIL population ( n=100 derived from the cross of “Essex” by “Forrest,” two cultivars that contrast for isoflavone content. Seed isoflavone content of each RIL was determined by HPLC and compared against 240 polymorphic microsatellite markers by one-way analysis of variance. Two QTL that underlie seed isoflavone content were newly discovered. The additional markers confirmed and refined the positions of the six QTL already reported. The first new region anchored by the marker BARC-Satt063 was significantly associated with genistein ( P=0.009 , R 2 =29.5% and daidzein ( P=0.007 , R 2 =17.0% . The region is located on linkage group B2 and derived the beneficial allele from Essex. The second new region defined by the marker BARC-Satt129 was significantly associated with total glycitein ( P=0.0005 , R 2 =32.0% . The region is located on linkage group D1a+Q and also derived the beneficial allele from Essex. Jointly the eight loci can explain the heritable variation in isoflavone content. The loci may be used to stabilize seed isoflavone content by selection and to isolate the underlying genes.

  14. Application of Bounded Linear Stability Analysis Method for Metrics-Driven Adaptive Control

    Science.gov (United States)

    Bakhtiari-Nejad, Maryam; Nguyen, Nhan T.; Krishnakumar, Kalmanje

    2009-01-01

    This paper presents the application of Bounded Linear Stability Analysis (BLSA) method for metrics-driven adaptive control. The bounded linear stability analysis method is used for analyzing stability of adaptive control models, without linearizing the adaptive laws. Metrics-driven adaptive control introduces a notion that adaptation should be driven by some stability metrics to achieve robustness. By the application of bounded linear stability analysis method the adaptive gain is adjusted during the adaptation in order to meet certain phase margin requirements. Analysis of metrics-driven adaptive control is evaluated for a second order system that represents a pitch attitude control of a generic transport aircraft. The analysis shows that the system with the metrics-conforming variable adaptive gain becomes more robust to unmodeled dynamics or time delay. The effect of analysis time-window for BLSA is also evaluated in order to meet the stability margin criteria.

  15. Computation of stabilizing PI and PID controllers by using Kronecker summation method

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Jian' an; Zheng, Da; Ren, Zhengyun [College of Information Science and Technology, Donghua University, Shanghai 201620 (China)

    2009-07-15

    In this paper, a new method for computation of all stabilizing PI controllers is given. The method is based on the plant model in time domain, and by using the extraordinary feature results from Kronecker sum operation, an explicit equation of control parameters defining the stability boundary in parametric space is obtained. Beyond stabilization, the method is used to shift all poles to a shifted half plane that guarantees a specified settling time of response. The stability regions of PID controllers are given in (k{sub p}, k{sub i}), (k{sub p}, k{sub d}) and (k{sub i}, k{sub d}) plane, respectively. The proposed method is also used to compute all the values of a PI controller stabilizing a control system with uncertain parameters. The proposed method is further extended to determine stability regions of uncertain coefficients of the system. Examples are given to show the benefits of the proposed method. (author)

  16. Computation of stabilizing PI and PID controllers by using Kronecker summation method

    Energy Technology Data Exchange (ETDEWEB)

    Fang Jianan [College of Information Science and Technology, Donghua University, Shanghai 201620 (China); Zheng Da [College of Information Science and Technology, Donghua University, Shanghai 201620 (China)], E-mail: zhengda@mail.dhu.edu.cn; Ren Zhengyun [College of Information Science and Technology, Donghua University, Shanghai 201620 (China)

    2009-07-15

    In this paper, a new method for computation of all stabilizing PI controllers is given. The method is based on the plant model in time domain, and by using the extraordinary feature results from Kronecker sum operation, an explicit equation of control parameters defining the stability boundary in parametric space is obtained. Beyond stabilization, the method is used to shift all poles to a shifted half plane that guarantees a specified settling time of response. The stability regions of PID controllers are given in (k{sub p}, k{sub i}), (k{sub p}, k{sub d}) and (k{sub i}, k{sub d}) plane, respectively. The proposed method is also used to compute all the values of a PI controller stabilizing a control system with uncertain parameters. The proposed method is further extended to determine stability regions of uncertain coefficients of the system. Examples are given to show the benefits of the proposed method.

  17. Computation of Stability Delay Margin of Time-Delayed Generator Excitation Control System with a Stabilizing Transformer

    Directory of Open Access Journals (Sweden)

    Saffet Ayasun

    2014-01-01

    Full Text Available This paper investigates the effect of time delays on the stability of a generator excitation control system compensated with a stabilizing transformer known as rate feedback stabilizer to damp out oscillations. The time delays are due to the use of measurement devices and communication links for data transfer. An analytical method is presented to compute the delay margin for stability. The delay margin is the maximum amount of time delay that the system can tolerate before it becomes unstable. First, without using any approximation, the transcendental characteristic equation is converted into a polynomial without the transcendentality such that its real roots coincide with the imaginary roots of the characteristic equation exactly. The resulting polynomial also enables us to easily determine the delay dependency of the system stability and the sensitivities of crossing roots with respect to the time delay. Then, an expression in terms of system parameters and imaginary root of the characteristic equation is derived for computing the delay margin. Theoretical delay margins are computed for a wide range of controller gains and their accuracy is verified by performing simulation studies. Results indicate that the addition of a stabilizing transformer to the excitation system increases the delay margin and improves the system damping significantly.

  18. STABILIZED CONTROLLER DESIGN FOR ATTITUDE AND ALTITUDE CONTROLLING OF QUAD-ROTOR UNDER DISTURBANCE AND NOISY CONDITIONS

    Directory of Open Access Journals (Sweden)

    M. Hassan Tanveer

    2013-01-01

    Full Text Available This article presents a control approach to obtain the better stabilization in attitude and altitude of quad-rotor under different disturbance conditions. In the standard Quad-rotor rotor type UAV, controlling of attitude and altitude is one of the most critical tasks and appropriate controller for stabilization of UAV is essential and necessary. These two controls under various conditions of disturbances was a field of research stimulating for the researchers. The controller proposed is contingent on the PID feedback structure with Extended Kalman Filter (EKF. From Lyapunov Stability Theorem, it is proved that quad-rotor proposed altitude control system is asymptotic as well exponentially stability. Extended Kalman Filter (EKF is used to filter out the sensors and system noises. Finally, the simulations carried out on MATLAB and the result proved the effectiveness of proposed recommended method for stabilization of attitude and altitude of quad-rotor.

  19. Flight Control System Design by Quadratic Stabilization with Partial Pole Placement

    Science.gov (United States)

    Satoh, Atsushi; Sugimoto, Kenji

    The most fundamental requirements for flight control system are ensuring robust stability and improving flying quality. Quadratic stabilization is a powerful technique ensuring robust stability against parameter change of aircraft due to flight condition. Furthermore, flying quality requirements are regarded as eigenstructure assignment specifications. This paper proposes a new design method of feedback gain which simultaneously achieves quadratic stabilization and partial pole placement. This design method is reduced to a numerical optimization problem including linear matrix inequality (LMI) constraints.

  20. Stability of a neural predictive controller scheme on a neural model

    DEFF Research Database (Denmark)

    Luther, Jim Benjamin; Sørensen, Paul Haase

    2009-01-01

    In previous works presenting various forms of neural-network-based predictive controllers, the main emphasis has been on the implementation aspects, i.e. the development of a robust optimization algorithm for the controller, which will be able to perform in real time. However, the stability issue...... has not been addressed specifically for these controllers. On the other hand a number of results concerning the stability of receding horizon controllers on a nonlinear system exist. In this paper we present a proof of stability for a predictive controller controlling a neural network model...

  1. Computerized dynamic posturography: the influence of platform stability on postural control.

    Science.gov (United States)

    Palm, Hans-Georg; Lang, Patricia; Strobel, Johannes; Riesner, Hans-Joachim; Friemert, Benedikt

    2014-01-01

    Postural stability can be quantified using posturography systems, which allow different foot platform stability settings to be selected. It is unclear, however, how platform stability and postural control are mathematically correlated. Twenty subjects performed tests on the Biodex Stability System at all 13 stability levels. Overall stability index, medial-lateral stability index, and anterior-posterior stability index scores were calculated, and data were analyzed using analysis of variance and linear regression analysis. A decrease in platform stability from the static level to the second least stable level was associated with a linear decrease in postural control. The overall stability index scores were 1.5 ± 0.8 degrees (static), 2.2 ± 0.9 degrees (level 8), and 3.6 ± 1.7 degrees (level 2). The slope of the regression lines was 0.17 for the men and 0.10 for the women. A linear correlation was demonstrated between platform stability and postural control. The influence of stability levels seems to be almost twice as high in men as in women.

  2. The DNA helicase Pfh1 promotes fork merging at replication termination sites to ensure genome stability

    Science.gov (United States)

    Steinacher, Roland; Osman, Fekret; Dalgaard, Jacob Z.; Lorenz, Alexander; Whitby, Matthew C.

    2012-01-01

    Bidirectionally moving DNA replication forks merge at termination sites composed of accidental or programmed DNA–protein barriers. If merging fails, then regions of unreplicated DNA can result in the breakage of DNA during mitosis, which in turn can give rise to genome instability. Despite its importance, little is known about the mechanisms that promote the final stages of fork merging in eukaryotes. Here we show that the Pif1 family DNA helicase Pfh1 plays a dual role in promoting replication fork termination. First, it facilitates replication past DNA–protein barriers, and second, it promotes the merging of replication forks. A failure of these processes in Pfh1-deficient cells results in aberrant chromosome segregation and heightened genome instability. PMID:22426535

  3. Stabilization Controller Design for a class of Inverted Pendulums via Adaptive Fuzzy Sliding Mode Control

    Directory of Open Access Journals (Sweden)

    Heng Liu

    2013-07-01

    Full Text Available X–Z inverted pendulum is a new kind of inverted pendulum and it can move with the combination of the vertical and horizontal forces. This paper addresses  the control problem of X-Z inverted pendulum in the presents of system uncertainties and external disturbances, and an adaptive fuzzy sliding mode control approach is proposed. The fuzzy  system is used to approximate the system uncertainties and the complicated intermediate control functions in the backstepping control design. To update the parameters of the fuzzy system, a proper proportional-integral adaptation law is introduced.  Finally, simulation studies are done to show the stabilization of the X-Z inverted pendulum under the proposed method.

  4. Controllability and stability of primary frequency control from thermostatic loads with delays

    DEFF Research Database (Denmark)

    Ziras, Charalampos; Vrettos, Evangelos; You, Shi

    2017-01-01

    There is an increasing interest in exploiting the flexibility of loads to provide ancillary services to the grid. In this paper we study how response delays and lockout constraints affect the controllability of an aggregation of refrigerators offering primary frequency control (PFC). First we...... examine the effect of delays in PFC provision from an aggregation of refrigerators, using a two-area power system. We propose a framework to systematically address frequency measurement and response delays and we determine safe values for the total delays via simulations. We introduce a controllability...... index to evaluate PFC provision under lockout constraints of refrigerators compressors. We conduct extensive simulations to study the effects of measurement delay, ramping times, lockout durations and rotational inertia on the controllability of the aggregation and system stability. Finally, we discuss...

  5. PID self tuning control based on Mamdani fuzzy logic control for quadrotor stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Priyambodo, Tri Kuntoro, E-mail: mastri@ugm.ac.id; Putra, Agfianto Eko [Aerospace and Aeronautics Electronics Research Group, Universitas Gadjah Mada, Yogyakarta (Indonesia); Department of Computer Science and Electronics, Universitas Gadjah Mada, Yogyakarta (Indonesia); Dharmawan, Andi, E-mail: andi-dharmawan@ugm.ac.id [Department of Computer Science and Electronics, Universitas Gadjah Mada, Yogyakarta (Indonesia)

    2016-02-01

    Quadrotor as one type of UAV have the ability to perform Vertical Take Off and Landing (VTOL). It allows the Quadrotor to be stationary hovering in the air. PID (Proportional Integral Derivative) control system is one of the control methods that are commonly used. It is usually used to optimize the Quadrotor stabilization at least based on the three Eulerian angles (roll, pitch, and yaw) as input parameters for the control system. The three constants of PID can be obtained in various methods. The simplest method is tuning manually. This method has several weaknesses. For example if the three constants are not exact, the resulting response will deviate from the desired result. By combining the methods of PID with fuzzy logic systems where human expertise is implemented into the machine language is expected to further optimize the control system.

  6. Genomic Stability of Lyophilized Sheep Somatic Cells before and after Nuclear Transfer

    OpenAIRE

    Domenico Iuso; Marta Czernik; Fiorella Di Egidio; Silvestre Sampino; Federica Zacchini; Michal Bochenek; Zdzislaw Smorag; Modlinski, Jacek A.; Grazyna Ptak; Pasqualino Loi

    2013-01-01

    The unprecedented decline of biodiversity worldwide is urging scientists to collect and store biological material from seriously threatened animals, including large mammals. Lyophilization is being explored as a low-cost system for storage in bio-banks of cells that might be used to expand or restore endangered or extinct species through the procedure of Somatic Cell Nuclear Transfer (SCNT). Here we report that the genome is intact in about 60% of lyophylized sheep lymphocytes, whereas DNA da...

  7. Global Asymptotic Stability of the Classical PID Controller by Considering Saturation Effects in Industrial Robots

    Directory of Open Access Journals (Sweden)

    Antonio Yarza

    2011-09-01

    Full Text Available An unsolved ancient problem in position control of robot manipulators is to find a stability analysis that proves global asymptotic stability of the classical PID control in closed loop with robot manipulators. The practical evidence suggests that in fact the classical PID in industrial robots is a global regulator. The main goal of the present paper is theoretically to show why in the practice such a fact is achieved. We show that considering the natural saturations of every control stage in practical robots, the classical PID becomes a type of saturated nonlinear PID controller. In this work such a nonlinear PID controller with bounded torques for robot manipulators is proposed. This controller, unlike other saturated nonlinear PID controllers previously proposed, uses a single saturation for the three terms of the controller. Global asymptotical stability is proved via Lyapunov stability theory. Experimental results are presented in order to observe the performance of the proposed controller.

  8. A Network of Multi-Tasking Proteins at the DNA Replication Fork Preserves Genome Stability.

    Directory of Open Access Journals (Sweden)

    2005-12-01

    Full Text Available To elucidate the network that maintains high fidelity genome replication, we have introduced two conditional mutant alleles of DNA2, an essential DNA replication gene, into each of the approximately 4,700 viable yeast deletion mutants and determined the fitness of the double mutants. Fifty-six DNA2-interacting genes were identified. Clustering analysis of genomic synthetic lethality profiles of each of 43 of the DNA2-interacting genes defines a network (consisting of 322 genes and 876 interactions whose topology provides clues as to how replication proteins coordinate regulation and repair to protect genome integrity. The results also shed new light on the functions of the query gene DNA2, which, despite many years of study, remain controversial, especially its proposed role in Okazaki fragment processing and the nature of its in vivo substrates. Because of the multifunctional nature of virtually all proteins at the replication fork, the meaning of any single genetic interaction is inherently ambiguous. The multiplexing nature of the current studies, however, combined with follow-up supporting experiments, reveals most if not all of the unique pathways requiring Dna2p. These include not only Okazaki fragment processing and DNA repair but also chromatin dynamics.

  9. A network of multi-tasking proteins at the DNA replication fork preserves genome stability.

    Directory of Open Access Journals (Sweden)

    Martin E Budd

    2005-12-01

    Full Text Available To elucidate the network that maintains high fidelity genome replication, we have introduced two conditional mutant alleles of DNA2, an essential DNA replication gene, into each of the approximately 4,700 viable yeast deletion mutants and determined the fitness of the double mutants. Fifty-six DNA2-interacting genes were identified. Clustering analysis of genomic synthetic lethality profiles of each of 43 of the DNA2-interacting genes defines a network (consisting of 322 genes and 876 interactions whose topology provides clues as to how replication proteins coordinate regulation and repair to protect genome integrity. The results also shed new light on the functions of the query gene DNA2, which, despite many years of study, remain controversial, especially its proposed role in Okazaki fragment processing and the nature of its in vivo substrates. Because of the multifunctional nature of virtually all proteins at the replication fork, the meaning of any single genetic interaction is inherently ambiguous. The multiplexing nature of the current studies, however, combined with follow-up supporting experiments, reveals most if not all of the unique pathways requiring Dna2p. These include not only Okazaki fragment processing and DNA repair but also chromatin dynamics.

  10. End-to-end rate-based congestion control with random loss: convergence and stability

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The convergence and stability analysis for two end-to-end rate-based congestion control algorithms with unavoidable random loss in packets are presented, which can be caused by, for example, errors on wireless links. The convergence rates of these two algorithms are analyzed by linearizing them around their equilibrium points, since they are globally stable and can converge to their unique equilibrium points. Some sufficient conditions for local stability in the presence of round-trip delay are obtained based on the general Nyquist criterion of stability. The stability conditions can be considered to be more general. If random loss in the first congestion control algorithm is not considered, they reduce to the local stability conditions which have been obtained in some literatures. Furthermore, sufficient conditions for local stability of a new congestion control algorithm have also been obtained if random loss is not considered in the second congestion control algorithm.

  11. Stability analysis of a noise control system in a duct by using delay differential equation

    Institute of Scientific and Technical Information of China (English)

    Masakazu Haraguchi; Hai Yan Hu

    2009-01-01

    The paper deals with the criteria for the closed-loop stability of a noise control system in a duct. To study the stability of the system, the model of delay differential equation is derived from the propagation of acoustic wave governed by a partial differential equation of hyperbolic type. Then, a simple feedback controller is designed, and its closed-loop stability is analyzed on the basis of the derived model of delay differential equation. The obtained criteria reveal the influence of the controller gain and the positions of a sensor and an actuator on the closed-loop stability. Finally, numerical simulations are presented to support the theoreti-cal results.

  12. Strategies for Voltage Control and Transient Stability Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Hiskens, Ian A.

    2013-09-25

    As wind generation grows, its influence on power system performance will becoming increasingly noticeable. Wind generation di ffers from traditional forms of generation in numerous ways though, motivating the need to reconsider the usual approaches to power system assessment and performance enhancement. The project has investigated the impact of wind generation on transient stability and voltage control, identifying and addressing issues at three distinct levels of the power system: 1) at the device level, the physical characteristics of wind turbine generators (WTGs) are quite unlike those of synchronous machines, 2) at the wind-farm level, the provision of reactive support is achieved through coordination of numerous dissimilar devices, rather than straightforward generator control, and 3) from a systems perspective, the location of wind-farms on the sub-transmission network, coupled with the variability inherent in their power output, can cause complex voltage control issues. The project has sought to develop a thorough understanding of the dynamic behaviour of type-3 WTGs, and in particular the WECC generic model. The behaviour of such models is governed by interactions between the continuous dynamics of state variables and discrete events associated with limits. It was shown that these interactions can be quite complex, and may lead to switching deadlock that prevents continuation of the trajectory. Switching hysteresis was proposed for eliminating deadlock situations. Various type-3 WTG models include control blocks that duplicate integrators. It was shown that this leads to non-uniqueness in the conditions governing steady-state, and may result in pre- and post-disturbance equilibria not coinciding. It also gives rise to a zero eigenvalue in the linearized WTG model. In order to eliminate the anomalous behaviour revealed through this investigation, WECC has now released a new generic model for type-3 WTGs. Wind-farms typically incorporate a variety of

  13. Genomic stability of Palmer amaranth plants derived by macro-vegetative propagation

    Science.gov (United States)

    Q-PCR (quantitative polymerase chain reaction) and random amplified polymorphic DNA (RAPD) were utilized to investigate genetic stability of Palmer amaranth cloned plants over 10 generations. Q-PCR analysis of DNA from parent Palmer amaranth plants was repeated and confidence levels for determining ...

  14. Optimal placement of unified power flow controllers to improve dynamic voltage stability using power system variable based voltage stability indices.

    Science.gov (United States)

    Albatsh, Fadi M; Ahmad, Shameem; Mekhilef, Saad; Mokhlis, Hazlie; Hassan, M A

    2015-01-01

    This study examines a new approach to selecting the locations of unified power flow controllers (UPFCs) in power system networks based on a dynamic analysis of voltage stability. Power system voltage stability indices (VSIs) including the line stability index (LQP), the voltage collapse proximity indicator (VCPI), and the line stability index (Lmn) are employed to identify the most suitable locations in the system for UPFCs. In this study, the locations of the UPFCs are identified by dynamically varying the loads across all of the load buses to represent actual power system conditions. Simulations were conducted in a power system computer-aided design (PSCAD) software using the IEEE 14-bus and 39- bus benchmark power system models. The simulation results demonstrate the effectiveness of the proposed method. When the UPFCs are placed in the locations obtained with the new approach, the voltage stability improves. A comparison of the steady-state VSIs resulting from the UPFCs placed in the locations obtained with the new approach and with particle swarm optimization (PSO) and differential evolution (DE), which are static methods, is presented. In all cases, the UPFC locations given by the proposed approach result in better voltage stability than those obtained with the other approaches.

  15. Optimal placement of unified power flow controllers to improve dynamic voltage stability using power system variable based voltage stability indices.

    Directory of Open Access Journals (Sweden)

    Fadi M Albatsh

    Full Text Available This study examines a new approach to selecting the locations of unified power flow controllers (UPFCs in power system networks based on a dynamic analysis of voltage stability. Power system voltage stability indices (VSIs including the line stability index (LQP, the voltage collapse proximity indicator (VCPI, and the line stability index (Lmn are employed to identify the most suitable locations in the system for UPFCs. In this study, the locations of the UPFCs are identified by dynamically varying the loads across all of the load buses to represent actual power system conditions. Simulations were conducted in a power system computer-aided design (PSCAD software using the IEEE 14-bus and 39- bus benchmark power system models. The simulation results demonstrate the effectiveness of the proposed method. When the UPFCs are placed in the locations obtained with the new approach, the voltage stability improves. A comparison of the steady-state VSIs resulting from the UPFCs placed in the locations obtained with the new approach and with particle swarm optimization (PSO and differential evolution (DE, which are static methods, is presented. In all cases, the UPFC locations given by the proposed approach result in better voltage stability than those obtained with the other approaches.

  16. Optimal Placement of Unified Power Flow Controllers to Improve Dynamic Voltage Stability Using Power System Variable Based Voltage Stability Indices

    Science.gov (United States)

    Albatsh, Fadi M.; Ahmad, Shameem; Mekhilef, Saad; Mokhlis, Hazlie; Hassan, M. A.

    2015-01-01

    This study examines a new approach to selecting the locations of unified power flow controllers (UPFCs) in power system networks based on a dynamic analysis of voltage stability. Power system voltage stability indices (VSIs) including the line stability index (LQP), the voltage collapse proximity indicator (VCPI), and the line stability index (Lmn) are employed to identify the most suitable locations in the system for UPFCs. In this study, the locations of the UPFCs are identified by dynamically varying the loads across all of the load buses to represent actual power system conditions. Simulations were conducted in a power system computer-aided design (PSCAD) software using the IEEE 14-bus and 39- bus benchmark power system models. The simulation results demonstrate the effectiveness of the proposed method. When the UPFCs are placed in the locations obtained with the new approach, the voltage stability improves. A comparison of the steady-state VSIs resulting from the UPFCs placed in the locations obtained with the new approach and with particle swarm optimization (PSO) and differential evolution (DE), which are static methods, is presented. In all cases, the UPFC locations given by the proposed approach result in better voltage stability than those obtained with the other approaches. PMID:25874560

  17. Variable Speed CMG Control of a Dual-Spin Stabilized Unconventional VTOL Air Vehicle

    Science.gov (United States)

    Lim, Kyong B.; Moerder, Daniel D.; Shin, J-Y.

    2004-01-01

    This paper describes an approach based on using both bias momentum and multiple control moment gyros for controlling the attitude of statically unstable thrust-levitated vehicles in hover or slow translation. The stabilization approach described in this paper uses these internal angular momentum transfer devices for stability, augmented by thrust vectoring for trim and other outer loop control functions, including CMG stabilization/ desaturation under persistent external disturbances. Simulation results show the feasibility of (1) improved vehicle performance beyond bias momentum assisted vector thrusting control, and (2) using control moment gyros to significantly reduce the external torque required from the vector thrusting machinery.

  18. STATE-FEEDBACK ADAPTIVE STABILIZING CONTROL DESIGN FOR A CLASS OF HIGH-ORDER NONLINEAR SYSTEMS WITH UNKNOWN CONTROL COEFFICIENTS

    Institute of Scientific and Technical Information of China (English)

    Zongyao SUN; Yungang LIU

    2007-01-01

    In this paper, a new approach is successfully addressed to design the state-feedback adaptive stabilizing control law for a class of high-order nonlinear systems in triangular form and with unknown and nonidentical control coefficients, whose stabilizing control has been investigated recently under the knowledge that the lower bounds of the control coefficients are exactly known. In the present paper,without any knowledge of the lower bounds of the control coefficients, based on the adaptive technique and appropriately choosing design parameters, we give the recursive design procedure of the stabilizing control law by utilizing the approach of adding a power integrator together with tuning functions. The state-feedback adaptive control law designed not only preserves the equilibrium at the origin, but also guarantees the global asymptotic stability of the closed-loop states and the uniform boundedness of all the other closed-loop signals.

  19. Integral input-to-state stability of nonlinear control systems with delays

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Wenli [Department of Economics Mathematics, South Western University of Finance and Economics, Chengdu 610074 (China)]. E-mail: zhuwl@swufe.edu.cn; Yi Zhang [Computational Intelligence Laboratory, School of Computer Science and Engineering, University of Electronic Science and Technology of China, Chengdu 610054 (China)]. E-mail: zhangyi@uestc.edu.cn

    2007-10-15

    Integral input-to-state stability is an interesting concept that has been recently introduced to nonlinear control systems. This paper generalizes this concept to nonlinear control systems with delays. These delays can be bounded, unbounded, and even infinite. Theorems for integral input-to-state stability are derived by developing the method of Razumikhin technique in the theory of functional differential equations.

  20. Stabilization of Parametric Roll Resonance with Active U-Tanks via Lyapunov Control Design

    DEFF Research Database (Denmark)

    Holden, Christian; Galeazzi, Roberto; Fossen, Thor Inge;

    2009-01-01

    design of an active u-tank stabilizer is carried out using Lyapunov theory. A nonlinear backstepping controller is developed to provide global exponential stability of roll. An extension of commonly used u-tank models is presented to account for large roll angles, and the control design is tested via...

  1. Stabilization and shape control of a 1D piezoelectric Timoshenko beam

    NARCIS (Netherlands)

    Voss, T.; Scherpen, J. M. A.

    2011-01-01

    In this paper we show how to perform stabilization and shape control for a finite dimensional model that recasts the dynamics of an inflatable space reflector in port-Hamiltonian (pH) form. We show how to derive a decentralized passivity-based controller which can be used to stabilize a 1D piezoelec

  2. Nonlinear control for global stabilization of multiple-integrator system by bounded controls

    Institute of Scientific and Technical Information of China (English)

    Bin ZHOU; Guangren DUAN; Liu ZHANG

    2008-01-01

    The global stabilization problem of the multiple-integrator system by bounded controls is considered.A nonlinear feedback law consisting of nested saturation functions is proposed.This type of nonlinear feedback law that is a modification and generalization of the result given in[1] needs only[(n+1)/2](n is the dimensions of the system)saturation elements,which is fewer than that which the other nonlinear laws need.Funhermore.the poles of the closedloop system Can be placed on any location on the left real axis when none of the saturafion elements in the control laws is saturated.This type of nonlinear control law exhibits a simpler structure and call significantly improve the transient performances of the closed-loop system,and is very superior to the other existing methods.Simulation on a fourth-order system is used to validate the proposed method.

  3. IMPULSIVE CONTROL FOR THE STABILIZATION AND SYNCHRONIZATION OF LUR'E SYSTEMS

    Institute of Scientific and Technical Information of China (English)

    孙继涛; 吴启迪

    2004-01-01

    An impulsive control scheme of the Lur' e system and several theorems on stability of impulsive control systems was presented, these theorems were then used to find the conditions under which the Lur' e system can be stabilized by using impulsive control with varying impulsive intervals.The parameters of Lur' e system and impulsive control law are given, a theory of impulsive synchronization of two Lur' e system is also presented. A numerical example is used to verify the theoretical result.

  4. Control and Stabilization of a Class of Nonlinear Systems With Symmetry

    Science.gov (United States)

    1998-01-01

    this dissertation is to study issues related to controllability and stabilization of a class of underactuated mechanical systems with symmetry. In...this dissertation issues related to controllability and stabilization of a class of underactuated mechanical systems was studied. For the class of...control for underactuated mechanical systems on Lie group. In Proc. of European Control Conference, 1997. 132 [Bullo and Lewis, 1996] F. Bullo and A.D

  5. Unified power flow controller: Modeling, stability analysis, control strategy and control system design

    Science.gov (United States)

    Sreenivasachar, Kannan

    2001-07-01

    Unified power flow controller (UPFC) has been the most versatile Flexible AC Transmission System (FACTS) device due to its ability to control real and reactive power flow on transmission lines while controlling the voltage of the bus to which it is connected. UPFC being a multi-variable power system controller it is necessary to analyze its effect on power system operation. To study the performance of the UPFC in damping power oscillations using PSCAD-EMTDC software, a de-coupled control system has been designed for the shunt inverter to control the UPFC bus voltage and the DC link capacitor voltage. The series inverter of a UPFC controls the real power flow in the transmission line. One problem associated with using a high gain PI controller (used to achieve fast control of transmission line real power flow) for the series inverter of a UPFC to control the real power flow in a transmission line is the presence of low damping. This problem is solved in this research by using a fuzzy controller. A method to model a fuzzy controller in PSCAD-EMTDC software has also been described. Further, in order to facilitate proper operation between the series and the shunt inverter control system, a new real power coordination controller has been developed and its performance was evaluated. The other problem concerning the operation of a UPFC is with respect to transmission line reactive power flow control. Step changes to transmission line reactive power references have significant impact on the UPFC bus voltage. To reduce the adverse effect of step changes in transmission line reactive power references on the UPFC bus voltage, a new reactive power coordination controller has been designed. Transient response studies have been conducted using PSCAD-EMTDC software to show the improvement in power oscillation damping with UPFC. These simulations include the real and reactive power coordination controllers. Finally, a new control strategy has been proposed for UPFC. In this

  6. Stabilization of three-dimensional chaotic systems via single state feedback controller

    Energy Technology Data Exchange (ETDEWEB)

    Yu Wenguang, E-mail: smilewgyu@163.co [School of Statistics and Mathematics, Shandong Economic University, Jinan 250014 (China)

    2010-03-29

    This Letter investigates the stabilization of three-dimensional chaotic systems, and proposes a novel simple adaptive-feedback controller for chaos control. In comparison with previous methods, the present controller which only contains single state feedback, to our knowledge, is the simplest control scheme for controlling the three-dimensional chaotic system. The results are validated using numerical simulations.

  7. The beauty of simple adaptive control and new developments in nonlinear systems stability analysis

    Science.gov (United States)

    Barkana, Itzhak

    2014-12-01

    Although various adaptive control techniques have been around for a long time and in spite of successful proofs of stability and even successful demonstrations of performance, the eventual use of adaptive control methodologies in practical real world systems has met a rather strong resistance from practitioners and has remained limited. Apparently, it is difficult to guarantee or even understand the conditions that can guarantee stable operations of adaptive control systems under realistic operational environments. Besides, it is difficult to measure the robustness of adaptive control system stability and allow it to be compared with the common and widely used measure of phase margin and gain margin that is utilized by present, mainly LTI, controllers. Furthermore, customary stability analysis methods seem to imply that the mere stability of adaptive systems may be adversely affected by any tiny deviation from the pretty idealistic and assumably required stability conditions. This paper first revisits the fundamental qualities of customary direct adaptive control methodologies, in particular the classical Model Reference Adaptive Control, and shows that some of their basic drawbacks have been addressed and eliminated within the so-called Simple Adaptive Control methodology. Moreover, recent developments in the stability analysis methods of nonlinear systems show that prior conditions that were customarily assumed to be needed for stability are only apparent and can be eliminated. As a result, sufficient conditions that guarantee stability are clearly stated and lead to similarly clear proofs of stability. As many real-world applications show, once robust stability of the adaptive systems can be guaranteed, the added value of using Add-On Adaptive Control along with classical Control design techniques is pushing the desired performance beyond any previous limits.

  8. The beauty of simple adaptive control and new developments in nonlinear systems stability analysis

    Energy Technology Data Exchange (ETDEWEB)

    Barkana, Itzhak, E-mail: ibarkana@gmail.com [BARKANA Consulting, Ramat Hasharon (Israel)

    2014-12-10

    Although various adaptive control techniques have been around for a long time and in spite of successful proofs of stability and even successful demonstrations of performance, the eventual use of adaptive control methodologies in practical real world systems has met a rather strong resistance from practitioners and has remained limited. Apparently, it is difficult to guarantee or even understand the conditions that can guarantee stable operations of adaptive control systems under realistic operational environments. Besides, it is difficult to measure the robustness of adaptive control system stability and allow it to be compared with the common and widely used measure of phase margin and gain margin that is utilized by present, mainly LTI, controllers. Furthermore, customary stability analysis methods seem to imply that the mere stability of adaptive systems may be adversely affected by any tiny deviation from the pretty idealistic and assumably required stability conditions. This paper first revisits the fundamental qualities of customary direct adaptive control methodologies, in particular the classical Model Reference Adaptive Control, and shows that some of their basic drawbacks have been addressed and eliminated within the so-called Simple Adaptive Control methodology. Moreover, recent developments in the stability analysis methods of nonlinear systems show that prior conditions that were customarily assumed to be needed for stability are only apparent and can be eliminated. As a result, sufficient conditions that guarantee stability are clearly stated and lead to similarly clear proofs of stability. As many real-world applications show, once robust stability of the adaptive systems can be guaranteed, the added value of using Add-On Adaptive Control along with classical Control design techniques is pushing the desired performance beyond any previous limits.

  9. New approach to stochastic stability and controller design for networked control systems

    Institute of Scientific and Technical Information of China (English)

    Shanbin LI; Youxian SUN

    2005-01-01

    This paper addresses the random time-delays and packet losses issues of networked control systems (NCS) within the framework of jump linear systems with mode-dependent time-delays.A new delay-dependent condition on the stochastic stability is proposed by a new stochastic Lyapunov-Krasovskii functional.The condition is formulated as a set of coupled linear matrix inequalities (LMIs).As an example to verify the proposed method,an inverted-pendulum system with network is considered.The simulation results demonstrate the effectiveness of the method.

  10. Effects of chlorine and chlorine dioxide on human rotavirus infectivity and genome stability.

    Science.gov (United States)

    Xue, Bin; Jin, Min; Yang, Dong; Guo, Xuan; Chen, Zhaoli; Shen, Zhiqiang; Wang, Xinwei; Qiu, Zhigang; Wang, Jingfeng; Zhang, Bin; Li, Junwen

    2013-06-15

    Despite the health risks posed by waterborne human rotavirus (HRV), little information is available concerning the effectiveness of chlorine or chlorine dioxide (ClO2), two common disinfectants of public water sources, against HRV and their effects on its genome remain poorly understood. This study investigated the effects of chlorine and ClO2 on purified HRV by using cell culture and RT-PCR to assess virus infectivity and genetic integrity, respectively. The disinfection efficacy of ClO2 was found to be higher than that of chlorine. According to the efficiency factor Hom model, Ct value (mg/L min) ranges required for a 4-log reduction of HRV at 20 °C by chlorine and ClO2 were 5.55-5.59 and 1.21-2.47 mg/L min, respectively. Detection of the 11 HRV genome segments revealed that damage to the 1227-2354 bp of the VP4 gene was associated with the disappearance of viral infectivity by chlorine. However, no complete accordance between culturing and RT-PCR assays was observed after treatment of HRV with ClO2. These results collectively indicate that the current practice of chlorine disinfection may be inadequate to manage the risk of waterborne HRV infection, and offer the potential to monitor the infectivity of HRV adapting PCR-based protocols in chlorine disinfection. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Roles of POLD4, smallest subunit of DNA polymerase {delta}, in nuclear structures and genomic stability of human cells

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Qin Miao [Division of Molecular Carcinogenesis, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya (Japan); Akashi, Tomohiro [Division of Molecular Mycology and Medicine, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya (Japan); Masuda, Yuji; Kamiya, Kenji [Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima 734-8553 (Japan); Takahashi, Takashi [Division of Molecular Carcinogenesis, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya (Japan); Suzuki, Motoshi, E-mail: msuzuki@med.nagoya-u.ac.jp [Division of Molecular Carcinogenesis, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya (Japan)

    2010-01-01

    Mammalian DNA polymerase {delta} (pol {delta}) is essential for DNA replication, though the functions of this smallest subunit of POLD4 have been elusive. We investigated pol {delta} activities in vitro and found that it was less active in the absence of POLD4, irrespective of the presence of the accessory protein PCNA. shRNA-mediated reduction of POLD4 resulted in a marked decrease in colony formation activity by Calu6, ACC-LC-319, and PC-10 cells. We also found that POLD4 reduction was associated with an increased population of karyomere-like cells, which may be an indication of DNA replication stress and/or DNA damage. The karyomere-like cells retained an ability to progress through the cell cycle, suggesting that POLD4 reduction induces modest genomic instability, while allowing cells to grow until DNA damage reaches an intolerant level. Our results indicate that POLD4 is required for the in vitro pol {delta} activity, and that it functions in cell proliferation and maintenance of genomic stability of human cells.

  12. Biological stability of drinking water: Controlling factors, methods, and challenges

    NARCIS (Netherlands)

    Prest, E.I.E.D.; Hammes, F.; Van Loosdrecht, M.C.M.; Vrouwenvelder, J.S.

    2016-01-01

    Biological stability of drinking water refers to the concept of providing consumers with drinking water of same microbial quality at the tap as produced at the water treatment facility. However, uncontrolled growth of bacteria can occur during distribution in water mains and premise plumbing, and ca

  13. Biological stability of drinking water: Controlling factors, methods, and challenges

    NARCIS (Netherlands)

    Prest, E.I.E.D.; Hammes, F.; Van Loosdrecht, M.C.M.; Vrouwenvelder, J.S.

    2016-01-01

    Biological stability of drinking water refers to the concept of providing consumers with drinking water of same microbial quality at the tap as produced at the water treatment facility. However, uncontrolled growth of bacteria can occur during distribution in water mains and premise plumbing, and ca

  14. Biological stability of drinking water: Controlling factors, methods, and challenges

    NARCIS (Netherlands)

    Prest, E.I.E.D.; Hammes, F.; Van Loosdrecht, M.C.M.; Vrouwenvelder, J.S.

    2016-01-01

    Biological stability of drinking water refers to the concept of providing consumers with drinking water of same microbial quality at the tap as produced at the water treatment facility. However, uncontrolled growth of bacteria can occur during distribution in water mains and premise plumbing, and

  15. A Review of Active Yaw Control System for Vehicle Handling and Stability Enhancement

    Directory of Open Access Journals (Sweden)

    M. K. Aripin

    2014-01-01

    Full Text Available Yaw stability control system plays a significant role in vehicle lateral dynamics in order to improve the vehicle handling and stability performances. However, not many researches have been focused on the transient performances improvement of vehicle yaw rate and sideslip tracking control. This paper reviews the vital elements for control system design of an active yaw stability control system; the vehicle dynamic models, control objectives, active chassis control, and control strategies with the focus on identifying suitable criteria for improved transient performances. Each element is discussed and compared in terms of their underlying theory, strengths, weaknesses, and applicability. Based on this, we conclude that the sliding mode control with nonlinear sliding surface based on composite nonlinear feedback is a potential control strategy for improving the transient performances of yaw rate and sideslip tracking control.

  16. Stabilization

    Directory of Open Access Journals (Sweden)

    Muhammad H. Al-Malack

    2016-07-01

    Full Text Available Fuel oil flyash (FFA produced in power and water desalination plants firing crude oils in the Kingdom of Saudi Arabia is being disposed in landfills, which increases the burden on the environment, therefore, FFA utilization must be encouraged. In the current research, the effect of adding FFA on the engineering properties of two indigenous soils, namely sand and marl, was investigated. FFA was added at concentrations of 5%, 10% and 15% to both soils with and without the addition of Portland cement. Mixtures of the stabilized soils were thoroughly evaluated using compaction, California Bearing Ratio (CBR, unconfined compressive strength (USC and durability tests. Results of these tests indicated that stabilized sand mixtures could not attain the ACI strength requirements. However, marl was found to satisfy the ACI strength requirement when only 5% of FFA was added together with 5% of cement. When the FFA was increased to 10% and 15%, the mixture’s strength was found to decrease to values below the ACI requirements. Results of the Toxicity Characteristics Leaching Procedure (TCLP, which was performed on samples that passed the ACI requirements, indicated that FFA must be cautiously used in soil stabilization.

  17. Design of UPFC Controller Using Modified Bilinear Equation for Improving Transient Stability

    Directory of Open Access Journals (Sweden)

    Majid Nayeripour

    2008-01-01

    Full Text Available Based on the use of the modified bilinear equation for the unified power flow controller (UPFC, this paper proposes a new control strategy to improve the transient stability of power system. This control strategy is applied to shunt and series inverters of UPFC as the modulating signals at the operating point. This input signals are such that the derivative of Liapunov energy function is negative definite. Simulation results show that the transient stability of power system has improved more effectively than the conventional PI controllers. Moreover, the coordination between series and shunt controllers of UPFC via one control law is considered as the main advantages of the designed controllers.

  18. Traffic behavior of mixed traffic flow with two kinds of different self-stabilizing control vehicles

    Science.gov (United States)

    Li, Zhipeng; Li, Wenzhong; Xu, Shangzhi; Qian, Yeqing; Sun, Jian

    2015-10-01

    In this paper, we propose a heterogeneous car following model in terms of an extension to the original optimal velocity model characterizing two classes of different self-stabilizing control vehicles. Linear stability analysis method is utilized to the extended model, for purpose to explore how the varying percentages of the vehicles with short-duration self-stabilizing control influence the stability of the heterogeneous traffic flow. We obtain the neutral stability lines for different percentages of two classes of vehicles, with finding that the traffic flow trends to stable with the decrease of the percentage for short-duration self-stabilizing control vehicles. Moreover, we explore a special case that the same numbers of two different classes of vehicles with self-stabilizing control. We theoretically derive the stability condition of the special case, and conclude the effect of the average value and the standard deviation of two time gaps, on the heterogeneous traffic stability. At last, direct simulations are conducted to verify the conclusion of theoretical analysis.

  19. Budding Yeast Rif1 Controls Genome Integrity by Inhibiting rDNA Replication.

    Science.gov (United States)

    Shyian, Maksym; Mattarocci, Stefano; Albert, Benjamin; Hafner, Lukas; Lezaja, Aleksandra; Costanzo, Michael; Boone, Charlie; Shore, David

    2016-11-01

    The Rif1 protein is a negative regulator of DNA replication initiation in eukaryotes. Here we show that budding yeast Rif1 inhibits DNA replication initiation at the rDNA locus. Absence of Rif1, or disruption of its interaction with PP1/Glc7 phosphatase, leads to more intensive rDNA replication. The effect of Rif1-Glc7 on rDNA replication is similar to that of the Sir2 deacetylase, and the two would appear to act in the same pathway, since the rif1Δ sir2Δ double mutant shows no further increase in rDNA replication. Loss of Rif1-Glc7 activity is also accompanied by an increase in rDNA repeat instability that again is not additive with the effect of sir2Δ. We find, in addition, that the viability of rif1Δ cells is severely compromised in combination with disruption of the MRX or Ctf4-Mms22 complexes, both of which are implicated in stabilization of stalled replication forks. Significantly, we show that removal of the rDNA replication fork barrier (RFB) protein Fob1, alleviation of replisome pausing by deletion of the Tof1/Csm3 complex, or a large deletion of the rDNA repeat array all rescue this synthetic growth defect of rif1Δ cells lacking in addition either MRX or Ctf4-Mms22 activity. These data suggest that the repression of origin activation by Rif1-Glc7 is important to avoid the deleterious accumulation of stalled replication forks at the rDNA RFB, which become lethal when fork stability is compromised. Finally, we show that Rif1-Glc7, unlike Sir2, has an important effect on origin firing outside of the rDNA locus that serves to prevent activation of the DNA replication checkpoint. Our results thus provide insights into a mechanism of replication control within a large repetitive chromosomal domain and its importance for the maintenance of genome stability. These findings may have important implications for metazoans, where large blocks of repetitive sequences are much more common.

  20. Budding Yeast Rif1 Controls Genome Integrity by Inhibiting rDNA Replication.

    Directory of Open Access Journals (Sweden)

    Maksym Shyian

    2016-11-01

    Full Text Available The Rif1 protein is a negative regulator of DNA replication initiation in eukaryotes. Here we show that budding yeast Rif1 inhibits DNA replication initiation at the rDNA locus. Absence of Rif1, or disruption of its interaction with PP1/Glc7 phosphatase, leads to more intensive rDNA replication. The effect of Rif1-Glc7 on rDNA replication is similar to that of the Sir2 deacetylase, and the two would appear to act in the same pathway, since the rif1Δ sir2Δ double mutant shows no further increase in rDNA replication. Loss of Rif1-Glc7 activity is also accompanied by an increase in rDNA repeat instability that again is not additive with the effect of sir2Δ. We find, in addition, that the viability of rif1Δ cells is severely compromised in combination with disruption of the MRX or Ctf4-Mms22 complexes, both of which are implicated in stabilization of stalled replication forks. Significantly, we show that removal of the rDNA replication fork barrier (RFB protein Fob1, alleviation of replisome pausing by deletion of the Tof1/Csm3 complex, or a large deletion of the rDNA repeat array all rescue this synthetic growth defect of rif1Δ cells lacking in addition either MRX or Ctf4-Mms22 activity. These data suggest that the repression of origin activation by Rif1-Glc7 is important to avoid the deleterious accumulation of stalled replication forks at the rDNA RFB, which become lethal when fork stability is compromised. Finally, we show that Rif1-Glc7, unlike Sir2, has an important effect on origin firing outside of the rDNA locus that serves to prevent activation of the DNA replication checkpoint. Our results thus provide insights into a mechanism of replication control within a large repetitive chromosomal domain and its importance for the maintenance of genome stability. These findings may have important implications for metazoans, where large blocks of repetitive sequences are much more common.

  1. Parkin Regulates Mitosis and Genomic Stability through Cdc20/Cdh1.

    Science.gov (United States)

    Lee, Seung Baek; Kim, Jung Jin; Nam, Hyun-Ja; Gao, Bowen; Yin, Ping; Qin, Bo; Yi, Sang-Yeop; Ham, Hyoungjun; Evans, Debra; Kim, Sun-Hyun; Zhang, Jun; Deng, Min; Liu, Tongzheng; Zhang, Haoxing; Billadeau, Daniel D; Wang, Liewei; Giaime, Emilie; Shen, Jie; Pang, Yuan-Ping; Jen, Jin; van Deursen, Jan M; Lou, Zhenkun

    2015-10-01

    Mutations in the E3 ubiquitin ligase Parkin have been linked to familial Parkinson's disease. Parkin has also been implicated in mitosis through mechanisms that are unclear. Here we show that Parkin interacts with anaphase promoting complex/cyclosome (APC/C) coactivators Cdc20 and Cdh1 to mediate the degradation of several key mitotic regulators independent of APC/C. We demonstrate that ordered progression through mitosis is orchestrated by two distinct E3 ligases through the shared use of Cdc20 and Cdh1. Furthermore, Parkin is phosphorylated and activated by polo-like kinase 1 (Plk1) during mitosis. Parkin deficiency results in overexpression of its substrates, mitotic defects, genomic instability, and tumorigenesis. These results suggest that the Parkin-Cdc20/Cdh1 complex is an important regulator of mitosis.

  2. Genomic stability of lyophilized sheep somatic cells before and after nuclear transfer.

    Directory of Open Access Journals (Sweden)

    Domenico Iuso

    Full Text Available The unprecedented decline of biodiversity worldwide is urging scientists to collect and store biological material from seriously threatened animals, including large mammals. Lyophilization is being explored as a low-cost system for storage in bio-banks of cells that might be used to expand or restore endangered or extinct species through the procedure of Somatic Cell Nuclear Transfer (SCNT. Here we report that the genome is intact in about 60% of lyophylized sheep lymphocytes, whereas DNA damage occurs randomly in the remaining 40%. Remarkably, lyophilized nuclei injected into enucleated oocytes are repaired by a robust DNA repairing activity of the oocytes, and show normal developmental competence. Cloned embryos derived from lyophylized cells exhibited chromosome and cellular composition comparable to those of embryos derived from fresh donor cells. These findings support the feasibility of lyophylization as a storage procedure of mammalian cells to be used for SCNT.

  3. Controllability,Observability and Stability for a Class of Fractional-Order Linear Time-Invariant Control Systems

    Institute of Scientific and Technical Information of China (English)

    曾庆山; 曹广益; 朱新坚

    2004-01-01

    The definitions of controllability, observability and stability were presented for fractional-order linear systems. Using the Cayley-Hamilton theorem and Mittag-Leffler function in two parameters, the sufficient and necessary conditions of controllability and observability for such systems were derived. In terms of Lyapunov's stability theory, using the theorems of Mittage-Leffler function in two parameters this paper directly derived the sufficient and necessary condition of stability for such systems. The results obtained are useful for the analysis and synthesis of fractional-order linear control systems.

  4. Nonlinear and Variable Structure Excitation Controller for Power System Stability

    Institute of Scientific and Technical Information of China (English)

    Wang Ben; Ronnie Belmans

    2006-01-01

    A new nonlinear variable structure excitation controller is proposed. Its design combines the differential geometry theory and the variable structure controlling theory. The mathematical model in the form of "an affine nonlinear system" is set up for the control of a large-scale power system. The static and dynamic performances of the nonlinear variable structure controller are simulated. The response of system with the controller proposed is compared to that of the nonlinear optimal controller when the system is subjected to a variety of disturbances. Simulation results show that the nonlinear variable structure excitation controller gives more satisfactorily static and dynamic performance and better robustness.

  5. Computational Methods for Dynamic Stability and Control Derivatives

    Science.gov (United States)

    Green, Lawrence L.; Spence, Angela M.; Murphy, Patrick C.

    2004-01-01

    Force and moment measurements from an F-16XL during forced pitch oscillation tests result in dynamic stability derivatives, which are measured in combinations. Initial computational simulations of the motions and combined derivatives are attempted via a low-order, time-dependent panel method computational fluid dynamics code. The code dynamics are shown to be highly questionable for this application and the chosen configuration. However, three methods to computationally separate such combined dynamic stability derivatives are proposed. One of the separation techniques is demonstrated on the measured forced pitch oscillation data. Extensions of the separation techniques to yawing and rolling motions are discussed. In addition, the possibility of considering the angles of attack and sideslip state vector elements as distributed quantities, rather than point quantities, is introduced.

  6. PI Stabilization for Congestion Control of AQM Routers with Tuning Parameter Optimization

    Directory of Open Access Journals (Sweden)

    S. Chebli

    2016-09-01

    Full Text Available In this paper, we consider the problem of stabilizing network using a new proportional- integral (PI based congestion controller in active queue management (AQM router; with appropriate model approximation in the first order delay systems, we seek a stability region of the controller by using the Hermite- Biehler theorem, which isapplicable to quasipolynomials. A Genetic Algorithm technique is employed to derive optimal or near optimal PI controller parameters.

  7. Event-triggered nonlinear control for attitude stabilization of a quadrotor

    OpenAIRE

    Guerrero Castellanos, Fermi; Téllez-Guzmán, J. J.; Durand, Sylvain; Marchand, Nicolas; Álvarez-Muñoz, J. U.

    2013-01-01

    International audience; Event-triggered control is a ressource-aware sampling strategy that updates the control value only when a certain condition is satisfied, which denotes event instants. Such a technique allows to reduce the control computational cost and communications. In this paper, a quaternion-based feedback is developed for event-triggered attitude stabilization of a quadrotor mini-helicopter. The feedback is derived from the universal formula for event-triggered stabilization of g...

  8. Attitude stabilization of a rigid spacecraft using two control torques: A nonlinear control approach based on the spacecraft attitude dynamics

    Science.gov (United States)

    Krishnan, Hariharan; Reyhanoglu, Mahmut; McClamroch, Harris

    1994-06-01

    The attitude stabilization problem of a rigid spacecraft using control torques supplied by gas jet actuators about only two of its principal axes is considered. If the uncontrolled principal axis of the spacecraft is not an axis of symmetry, then the complete spacecraft dynamics are small time locally controllable. However, the spacecraft cannot be asymptotically stabilized to any equilibrium attitude using time-invariant continuous feedback. A discontinuous stabilizing feedback control strategy is constructed which stabilizes the spacecraft to any equilibrium attitude. If the uncontrolled principal axis of the spacecraft is an axis of symmetry, the complete spacecraft dynamics are not even assessible. However, the spacecraft dynamics are strongly accessible and small time locally controllable in a reduced sense. The reduced spacecraft dynamics cannot be asymptotically stabilized to any equilibrium attitude using time-invariant continuous feedback, but again a discontinuous stabilizing feedback control strategy is constructed. In both cases, the discontinuous feedback controllers are constructed by switching between several feedback functions which are selected to accomplish a sequence of spacecraft maneuvers. The results of the paper show that although standard nonlinear control techniques are not applicable, it is possible to construct a nonlinear discontinuous control law based on the dynamics of the particular physical system.

  9. Low-level laser irradiation alters mRNA expression from genes involved in DNA repair and genomic stabilization in myoblasts

    Science.gov (United States)

    Trajano, L. A. S. N.; Sergio, L. P. S.; Silva, C. L.; Carvalho, L.; Mencalha, A. L.; Stumbo, A. C.; Fonseca, A. S.

    2016-07-01

    Low-level lasers are used for the treatment of diseases in soft and bone tissues, but few data are available regarding their effects on genomic stability. In this study, we investigated mRNA expression from genes involved in DNA repair and genomic stabilization in myoblasts exposed to low-level infrared laser. C2C12 myoblast cultures in different fetal bovine serum concentrations were exposed to low-level infrared laser (10, 35 and 70 J cm-2), and collected for the evaluation of DNA repair gene expression. Laser exposure increased gene expression related to base excision repair (8-oxoguanine DNA glycosylase and apurinic/apyrimidinic endonuclease 1), nucleotide excision repair (excision repair cross-complementation group 1 and xeroderma pigmentosum C protein) and genomic stabilization (ATM serine/threonine kinase and tumor protein p53) in normal and low fetal bovine serum concentrations. Results suggest that genomic stability could be part of a biostimulation effect of low-level laser therapy in injured muscles.

  10. Impulsive control of stochastic system under the sense of stochastic asymptotical stability

    Institute of Scientific and Technical Information of China (English)

    Niu Yu-Jun; Ma Ge

    2010-01-01

    This paper studies the stochastic asymptotical stability of stochastic impulsive differential equations,and establishes a comparison theory to ensure the trivial solution's stochastic asymptotical stability.From the comparison theory,it can find out whether the stochastic impulsive differential system is stable just by studying the stability of a deterimpulsive control method,and numerical simulations are employed to verify the feasibility of this method.

  11. Stability condition of FAST TCP in high speed network Oil the basis of control theory

    Institute of Scientific and Technical Information of China (English)

    Zhao Fuzhe; Zhou Jianzhong; Luo Zhimeng; Xiao Yang

    2008-01-01

    Considering the instability of data transferred existing in high speed network.a near method is proposed for improving the stability using control theory.Under this method,the mathematical model of such a network is established.Stability condition is derived from the mathematical model.Several sivaulation experiments are performed.The results show that the method can increase the stability of data transferred in terms of the congestion window,queue size,and sending rate of the source.

  12. Control optimization, stabilization and computer algorithms for aircraft applications

    Science.gov (United States)

    Athans, M. (Editor); Willsky, A. S. (Editor)

    1982-01-01

    The analysis and design of complex multivariable reliable control systems are considered. High performance and fault tolerant aircraft systems are the objectives. A preliminary feasibility study of the design of a lateral control system for a VTOL aircraft that is to land on a DD963 class destroyer under high sea state conditions is provided. Progress in the following areas is summarized: (1) VTOL control system design studies; (2) robust multivariable control system synthesis; (3) adaptive control systems; (4) failure detection algorithms; and (5) fault tolerant optimal control theory.

  13. A particle-swarm-based approach of power system stability enhancement with unified power flow controller

    Energy Technology Data Exchange (ETDEWEB)

    Al-Awami, Ali T.; Abido, M.A. [Electrical Engineering Department, King Fahd University of Petroleum and Minerals, Dhahran 31261, Box 784 (Saudi Arabia); Abdel-Magid, Y.L. [Electrical Engineering Program, The Petroleum Institute, P.O. Box 2533, Abu Dhabi (United Arab Emirates)

    2007-03-15

    The use of the supplementary controllers of a unified power flow controller (UPFC) to damp low frequency oscillations in a weakly connected system is investigated. The potential of the UPFC supplementary controllers to enhance the dynamic stability is evaluated by measuring the electromechanical controllability through singular value decomposition (SVD) analysis. Individual designs of the UPFC controllers and power system stabilizer (PSS) using particle-swarm optimization (PSO) technique are discussed. The effectiveness of the proposed controllers on damping low frequency oscillations is tested through eigenvalue analysis and non-linear time simulation. (author)

  14. Optimal Stabilization of A Quadrotor UAV by a Constrained Fuzzy Control and PSO

    Directory of Open Access Journals (Sweden)

    Boubertakh Hamid

    2017-01-01

    Full Text Available This work aims to design an optimal fuzzy PD (FPD control for the attitude and altitude stabilization of a quadrotor. The control design is done by mean of the particle swarm optimization (PSO under the constraints of the controller interpretability and the saturation of the actuators. Concretely, a decentralized control structure is adopted where four FPD controllers are used to stabilize the quadrotor angles (roll, pitch and yaw and height. A PSO-based algorithm is used to simultaneously tune the four constrained controllers regarding a cost function quantifying the whole system performances. The simulation results are presented to show the efficiency of the proposed approach.

  15. Stabilization of Networked Control System with Packet-Dropout

    Directory of Open Access Journals (Sweden)

    Hooman Sanatizadeh

    2014-10-01

    Secondly, by above method an inverted pendulum which was controlled in a network with delays, is controlled in a network through packet-dropouts. simulation results show the effectiveness of the above method.

  16. Robust stabilizing first-order controllers for a class of time delay systems.

    Science.gov (United States)

    Saadaoui, Karim; Testouri, Sana; Benrejeb, Mohamed

    2010-07-01

    In this paper, stabilizing regions of a first-order controller for an all poles system with time delay are computed via parametric methods. First, the admissible ranges of one of the controller's parameters are obtained. Then, for a fixed value of this parameter, stabilizing regions in the remaining two parameters are determined using the D-decomposition method. Phase and gain margin specifications are then included in the design. Finally, robust stabilizing first-order controllers are determined for uncertain plants with an interval type uncertainty in the coefficients. Examples are given to illustrate the effectiveness of the proposed method.

  17. DESIGN OF A NEW INTERPOLATED CONTROLLER FOR STABILIZATION OF A SET OF INTERPOLATED PLANTS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Stabilization of a plant with variable operating conditions was considered. The plant is assumed to lie in a set of interpolated models composed of all interpolations generated between certain sets of proper stable coprime factorizations of transfer functions of two representative models that are defined at two representative operating points. An interpolated controller that is linear interpolation of coprime factorizations of two stabilizing controllers for the two representative models is designed to stabilize this set of interpolated models. Design of such an interpolated controller was converted to a feasibility problem constrained by several LMIs and a BMI, and a two-step iteration algorithm was employed to solve it.

  18. Stochastic stability of networked control systems with network-induced delay and data dropout

    Institute of Scientific and Technical Information of China (English)

    Xiaomei ZHANG; Yufan ZHENG; Guoping LU

    2008-01-01

    This paper deals with the stochastic stability of networked control systems with the presence of networkinduced delay and transmitted data dropout.Based on the Lyapunov approach.safficient conditions for the mean-square stability of the networked control system are derived subiect that the sequence of transmission interval is driven by an identicaily independently distributed sequence and by a finite state Markov chain.respectively.Stabilization controllers are constructed in tcrims of linear matrix inequalities correspondingly.An example is provided to illustrate our results.

  19. Stability Analysis and H∞ Output Tracking Control for Linear Systems with Time-Varying Delays

    Directory of Open Access Journals (Sweden)

    K. H. Kim

    2014-01-01

    Full Text Available The problem of stability analysis and H∞ output tracking control for linear systems with time-varying delays is studied. First, by construction of a newly augmented Lyapunov-Krasovskii functional, a delay-dependent stability criterion for nominal systems with time-varying delays is established in terms of linear matrix inequalities (LMIs. Second, based on the H∞ sense, the proposed method is extended to solve the problem of designing an H∞ output tracking controller to track the output of a given reference model. Finally, three examples are included to show the validity and effectiveness of the presented delay-dependent stability and the H∞ output tracking controller design.

  20. The study of the emission frequency control system stability in hydropulse generator

    Science.gov (United States)

    Kapelyuhovskiy, Andrey A.; Kapelyuhovskaya, Alexandra A.; Stepanova, Elena P.

    2017-08-01

    During a low-frequency acoustic treatment of the oil-bearing formation, downhole hydraulic vibrators are used. Their efficient operation is possible when using the automatic frequency control system due to the change of the expenditure pump flow rate. A long hydraulic line specifies additional requirements to the parameters of the control system in terms of its stability. The stability of a control system using the Nyquist criterion is made. Approximating the delay by the second degree of the Pade polynomial, the stability region is determined by the D-decomposition method. The dependence of the critical delay on the system transfer ratio is found out.

  1. Stability Analysis of Predator-Prey System with Fuzzy Impulsive Control

    Directory of Open Access Journals (Sweden)

    Yuangan Wang

    2012-01-01

    Full Text Available Having attracted much attention in the past few years, predator-prey system provides a good mathematical model to present the correlation between predators and preys. This paper focuses on the robust stability of Lotka-Volterra predator-prey system with the fuzzy impulsive control model, and Takagi-Sugeno (T-S fuzzy impulsive control model as well. Via the T-S model and the Lyapunov method, the controlling conditions of the asymptotical stability and exponential stability are established. Furthermore, the numerical simulation for the Lotka-Volterra predator-prey system with impulsive effects verifies the effectiveness of the proposed methods.

  2. The use of "stabilization exercises" to affect neuromuscular control in the lumbopelvic region: a narrative review.

    Science.gov (United States)

    Bruno, Paul

    2014-06-01

    It is well-established that the coordination of muscular activity in the lumbopelvic region is vital to the generation of mechanical spinal stability. Several models illustrating mechanisms by which dysfunctional neuromuscular control strategies may serve as a cause and/or effect of low back pain have been described in the literature. The term "core stability" is variously used by clinicians and researchers, and this variety has led to several rehabilitative approaches suggested to affect the neuromuscular control strategies of the lumbopelvic region (e.g. "stabilization exercise", "motor control exercise"). This narrative review will highlight: 1) the ongoing debate in the clinical and research communities regarding the terms "core stability" and "stabilization exercise", 2) the importance of sub-grouping in identifying those patients most likely to benefit from such therapeutic interventions, and 3) two protocols that can assist clinicians in this process.

  3. Dynamic stabilization methods for bilateral control of remote manipulation

    Science.gov (United States)

    Handlykken, M.

    1982-01-01

    This paper discusses and analyses several control strategies for generalized, bilateral master/slave manipulator systems. In these manipulators the two arms have different dynamic/kinematic properties which implies a more difficult control problem. Attention is focused on torque/force driven arms. Required performance for the necessary control computer(s) is discussed.

  4. Study of fuzzy adaptive PID controller on thermal frequency stabilizing laser with double longitudinal modes

    Science.gov (United States)

    Mo, Qingkai; Zhang, Tao; Yan, Yining

    2016-10-01

    There are contradictions among speediness, anti-disturbance performance, and steady-state accuracy caused by traditional PID controller in the existing light source systems of thermal frequency stabilizing laser with double longitudinal modes. In this paper, a new kind of fuzzy adaptive PID controller was designed by combining fuzzy PID control technology and expert system to make frequency stabilizing system obtain the optimal performance. The experiments show that the frequency stability of the designed PID controller is similar to the existing PID controller (the magnitude of frequency stability is less than 10-9 in constant temperature and 10-7 in open air). But the preheating time is shortened obviously (from 10 minutes to 5 minutes) and the anti-disturbance capability is improved significantly (the recovery time needed after strong interference is reduced from 1 minute to 10 seconds).

  5. Heterochromatic genome stability requires regulators of histone H3 K9 methylation.

    Directory of Open Access Journals (Sweden)

    Jamy C Peng

    2009-03-01

    Full Text Available Heterochromatin contains many repetitive DNA elements and few protein-encoding genes, yet it is essential for chromosome organization and inheritance. Here, we show that Drosophila that lack the Su(var3-9 H3K9 methyltransferase display significantly elevated frequencies of spontaneous DNA damage in heterochromatin, in both somatic and germ-line cells. Accumulated DNA damage in these mutants correlates with chromosomal defects, such as translocations and loss of heterozygosity. DNA repair and mitotic checkpoints are also activated in mutant animals and are required for their viability. Similar effects of lower magnitude were observed in animals that lack the RNA interference pathway component Dcr2. These results suggest that the H3K9 methylation and RNAi pathways ensure heterochromatin stability.

  6. Heterochromatic genome stability requires regulators of histone H3 K9 methylation.

    Science.gov (United States)

    Peng, Jamy C; Karpen, Gary H

    2009-03-01

    Heterochromatin contains many repetitive DNA elements and few protein-encoding genes, yet it is essential for chromosome organization and inheritance. Here, we show that Drosophila that lack the Su(var)3-9 H3K9 methyltransferase display significantly elevated frequencies of spontaneous DNA damage in heterochromatin, in both somatic and germ-line cells. Accumulated DNA damage in these mutants correlates with chromosomal defects, such as translocations and loss of heterozygosity. DNA repair and mitotic checkpoints are also activated in mutant animals and are required for their viability. Similar effects of lower magnitude were observed in animals that lack the RNA interference pathway component Dcr2. These results suggest that the H3K9 methylation and RNAi pathways ensure heterochromatin stability.

  7. Genomics in Public Health: Perspective from the Office of Public Health Genomics at the Centers for Disease Control and Prevention (CDC

    Directory of Open Access Journals (Sweden)

    Ridgely Fisk Green

    2015-09-01

    Full Text Available The national effort to use genomic knowledge to save lives is gaining momentum, as illustrated by the inclusion of genomics in key public health initiatives, including Healthy People 2020, and the recent launch of the precision medicine initiative. The Office of Public Health Genomics (OPHG at the Centers for Disease Control and Prevention (CDC partners with state public health departments and others to advance the translation of genome-based discoveries into disease prevention and population health. To do this, OPHG has adopted an “identify, inform, and integrate” model: identify evidence-based genomic applications ready for implementation, inform stakeholders about these applications, and integrate these applications into public health at the local, state, and national level. This paper addresses current and future work at OPHG for integrating genomics into public health programs.

  8. Human Exonuclease 5 Is a Novel Sliding Exonuclease Required for Genome Stability*

    Science.gov (United States)

    Sparks, Justin L.; Kumar, Rakesh; Singh, Mayank; Wold, Marc S.; Pandita, Tej K.; Burgers, Peter M.

    2012-01-01

    Previously, we characterized Saccharomyces cerevisiae exonuclease 5 (EXO5), which is required for mitochondrial genome maintenance. Here, we identify the human homolog (C1orf176; EXO5) that functions in the repair of nuclear DNA damage. Human EXO5 (hEXO5) contains an iron-sulfur cluster. It is a single-stranded DNA (ssDNA)-specific bidirectional exonuclease with a strong preference for 5′-ends. After loading at an ssDNA end, hEXO5 slides extensively along the ssDNA prior to cutting, hence the designation sliding exonuclease. However, the single-stranded binding protein human replication protein A (hRPA) restricts sliding and enforces a unique, species-specific 5′-directionality onto hEXO5. This specificity is lost with a mutant form of hRPA (hRPA-t11) that fails to interact with hEXO5. hEXO5 localizes to nuclear repair foci in response to DNA damage, and its depletion in human cells leads to an increased sensitivity to DNA-damaging agents, in particular interstrand cross-linking-inducing agents. Depletion of hEXO5 also results in an increase in spontaneous and damage-induced chromosome abnormalities including the frequency of triradial chromosomes, suggesting an additional defect in the resolution of stalled DNA replication forks in hEXO5-depleted cells. PMID:23095756

  9. The Stability Analysis of Multimedia Playout Synchronization Using Buffer Level Control

    Institute of Scientific and Technical Information of China (English)

    CHEN Bin; ZHU Xiang-Hua

    2004-01-01

    From the viewpoint of Cybernetics, multimedia playout synchronization system is a closed loop control system. The paper analyses the stability of a typical buffer-oriented playout synchronization model[1] with Routh criterion. The sufficient and necessary condition of system stability is obtained. The restriction relationship between two important system parameters: synchronization adaptation phase L and smoothing factor а is also given.

  10. Energy cost of balance control during walking decreases with external stabilizer stiffness independent of walking speed

    NARCIS (Netherlands)

    Ijmker, Trienke; Houdijk, Han; Lamoth, Claudine J. C.; Beek, Peter J.; van der Woude, Lucas H. V.

    2013-01-01

    Human walking requires active neuromuscular control to ensure stability in the lateral direction, which inflicts a certain metabolic load. The magnitude of this metabolic load has previously been investigated by means of passive external lateral stabilization via spring-like cords. In the present

  11. Stability and boundedness in terms of two measures for nonlinear impulsive control systems

    Institute of Scientific and Technical Information of China (English)

    Qiang XI

    2009-01-01

    In this paper we study stability and boundedness in terms of two measures for impulsive control systems. By using variational Lyapunov method, a new variational comparison principle and some criteria on stability and boundedness are obtained. An example is presented to illustrate the efficiency of proposed result.

  12. Asymptotic stability for a class of boundary control systems with non-linear damping

    OpenAIRE

    Zwart, Heiko J.; Ramirez, Hector; Le Gorrec, Yann

    2016-01-01

    The asymptotic stability of boundary controlled port-Hamiltonian systems defined on a 1D spatial domain interconnected to a class of non-linear boundary damping is addressed. It is shown that if the port-Hamiltonian system is approximately observable, then any boundary damping which behaves linear for small velocities asymptotically stabilizes the system.

  13. On the Feasibility of Stabilizing Parametric Roll with Active Bifurcation Control

    DEFF Research Database (Denmark)

    Galeazzi, Roberto; Blanke, Mogens

    2007-01-01

    to dynamically modify the instability region where parametric roll can occur. It is shown how a control strategy for roll stabilization could be modi…ed to change a bifurcation in roll motion and stabilize the motion, even after parametric resonance has started. The paper addresses issues of achievable...

  14. Robustly stabilizing controllers with respect to left coprime factor perturbations for irrational transfer functions.

    NARCIS (Netherlands)

    Curtain, RF

    2004-01-01

    We solve the problem of robust stabilization with respect to left coprime factor perturbations for a class of irrational transfer functions with a state space realization. We obtain a parameterization of the robustly stabilizing controllers in terms of the generating operators and an arbitrary

  15. An analysis of the stability and monotonicity of a kind of control models

    Directory of Open Access Journals (Sweden)

    LU Yifa

    2013-06-01

    Full Text Available The stability and monotonicity of control systems with parameters are considered.By the iterative relationship of the coefficients of characteristic polynomials and the Mathematica software,some sufficient conditions for the monotonicity and stability of systems are given.

  16. Stability and accuracy control of k · p parameters

    Science.gov (United States)

    Bastos, Carlos M. O.; Sabino, Fernando P.; Faria Junior, Paulo E.; Campos, Tiago; Da Silva, Juarez L. F.; Sipahi, Guilherme M.

    2016-10-01

    The k · p method is a successful approach to obtain band structure, optical and transport properties of semiconductors and it depends on external parameters that are obtained either from experiments, tight binding or ab initio calculations. Despite the widespread use of the k · p method, a systematic analysis of the stability and the accuracy of its parameters is not usual in the literature. In this work, we report a theoretical framework to determine the k · p parameters from state-of-the-art hybrid density functional theory including spin-orbit coupling, providing a calculation where the gap and spin-orbit energy splitting are in agreement with the experimental values. The accuracy of the set of parameters is enhanced by fitting over several directions at once, minimizing the overall deviation from the original data. This strategy allows us to systematically evaluate the stability, preserving the accuracy of the parameters, providing a tool to determine optimal parameters for specific ranges around the Γ-point. To prove our concept, we investigate the zinc blende GaAs that shows results in excellent agreement with the most reliable data in the literature.

  17. Optimization of linear parametric circuits by the control of stability

    Directory of Open Access Journals (Sweden)

    Yu. I. Shapovalov

    2013-07-01

    Full Text Available Introduction. A brief description of the symbolic frequency method for linear parametric circuit analysis is adduced. In particular it comes to parametric transfer functions and assessment of asymptotic stability of such circuits. The formulation of optimization task. The objective function formation is done via two functions - the function of goal defined by desirable circuit characteristics (goal of optimization and function characteristics of circuit defined by the selected values of the varied parameters during optimization of electrical circuit characteristics. The coincidence degree of these two functions is objective function which is formed on their basis by the chosen method. The procedure of optimization. The solution of optimization task is determining the values с0* and m* that provide minimum value of objective function, satisfy the condition of circuit stability and conditions of physical parametric element realizability Example. There is example of single-circuit parametric amplifier optimization using the objective function based on the calculation of parametric circuit transfer function with a symbolic representation of the parametric capacity parameters. Conclusions. Frequency symbolic analysis method allows solving optimization task of parametric linear circuits designing in the frequency domain based on use of the frequency symbolic transfer functions which are approximated by trigonometric polynomials of Fourier, particularly in complex form.

  18. Biologically Inspired Self-Stabilizing Control for Bipedal Robots

    Directory of Open Access Journals (Sweden)

    Woosung Yang

    2013-02-01

    Full Text Available Despite recent major advances in computational power and control algorithms, the stable and robust control of a bipedal robot is still a challenging issue due to the complexity and high nonlinearity of robot dynamics. To address the issue an efficient and powerful alternative based on a biologically inspired control framework employing neural oscillators is proposed and tested. In a numerical test the virtual force controller combined with the neural oscillator of a humanoid robot generated rhythmic control signals and stable bipedal locomotion when coupled with proper impedance components. The entrainment nature inherent to neural oscillators also achieved stable and robust walking even in the presence of unexpected disturbances, in that the centre of mass (COM was successfully kept in phase with the zero moment point (ZMP input trajectory. The efficiency of the proposed control scheme is discussed alongside simulation results.

  19. Comparing the Power System Stabilizer Based on Sliding Mode Control with the Fuzzy Power System Stabilizer for Single Machine Infinite Bus System (SMIB

    Directory of Open Access Journals (Sweden)

    Atabak Kolabi

    2013-01-01

    Full Text Available This study compares the power system stabilizer based on sliding mode control with the fuzzy power system stabilizer for Single Machine Infinite Bus System (SMIB. Using the sliding mode control, a range is obtained for the changes in system parameters; and a stabilizer is designed to have a proper performance in this wide range. The purpose of designing the sliding mode stabilizer and fuzzy stabilizer is the increased stability and improving the dynamic response of the single machine system connected to the infinite bus in different working conditions. In this study, simulation results are compared in case of conventional PSS, no PSS, PSS based on sliding mode control and PSS based fuzzy logic. The results of simulations performed on the model of nonlinear system shows good performance of sliding mode controller and the Fuzzy controller. SMIB system was selected because of its simple structure, which is very useful in understanding the effects and implications of the PSS.

  20. Global stabilization of nonlinear systems based on vector control lyapunov functions

    CERN Document Server

    Karafyllis, Iasson

    2012-01-01

    This paper studies the use of vector Lyapunov functions for the design of globally stabilizing feedback laws for nonlinear systems. Recent results on vector Lyapunov functions are utilized. The main result of the paper shows that the existence of a vector control Lyapunov function is a necessary and sufficient condition for the existence of a smooth globally stabilizing feedback. Applications to nonlinear systems are provided: simple and easily checkable sufficient conditions are proposed to guarantee the existence of a smooth globally stabilizing feedback law. The obtained results are applied to the problem of the stabilization of an equilibrium point of a reaction network taking place in a continuous stirred tank reactor.

  1. Comparative genomic reconstruction of transcriptional networks controlling central metabolism in the Shewanella genus

    Directory of Open Access Journals (Sweden)

    Kovaleva Galina

    2011-06-01

    Full Text Available Abstract Background Genome-scale prediction of gene regulation and reconstruction of transcriptional regulatory networks in bacteria is one of the critical tasks of modern genomics. The Shewanella genus is comprised of metabolically versatile gamma-proteobacteria, whose lifestyles and natural environments are substantially different from Escherichia coli and other model bacterial species. The comparative genomics approaches and computational identification of regulatory sites are useful for the in silico reconstruction of transcriptional regulatory networks in bacteria. Results To explore conservation and variations in the Shewanella transcriptional networks we analyzed the repertoire of transcription factors and performed genomics-based reconstruction and comparative analysis of regulons in 16 Shewanella genomes. The inferred regulatory network includes 82 transcription factors and their DNA binding sites, 8 riboswitches and 6 translational attenuators. Forty five regulons were newly inferred from the genome context analysis, whereas others were propagated from previously characterized regulons in the Enterobacteria and Pseudomonas spp.. Multiple variations in regulatory strategies between the Shewanella spp. and E. coli include regulon contraction and expansion (as in the case of PdhR, HexR, FadR, numerous cases of recruiting non-orthologous regulators to control equivalent pathways (e.g. PsrA for fatty acid degradation and, conversely, orthologous regulators to control distinct pathways (e.g. TyrR, ArgR, Crp. Conclusions We tentatively defined the first reference collection of ~100 transcriptional regulons in 16 Shewanella genomes. The resulting regulatory network contains ~600 regulated genes per genome that are mostly involved in metabolism of carbohydrates, amino acids, fatty acids, vitamins, metals, and stress responses. Several reconstructed regulons including NagR for N-acetylglucosamine catabolism were experimentally validated in S

  2. Analyzing the dynamic stability of controlled electric power systems

    Energy Technology Data Exchange (ETDEWEB)

    Nikolaeva, S.I.

    1983-01-01

    Techniques from the theory of optimal control are used to consider the possibilities for evaluating the effectiveness of emergency control of turbines at power plants of complex electric power systems. An algorithm is given for calculating the optimal control functions; it has been developed on the basis of the Pontryagin principle of the maximum and the method of quasi-linearization. Calculations for a particular four-machine circuit are used to evaluate the factors affecting the computational effectiveness of the algorithm.

  3. Attitude Stabilization Control of a Quadrotor UAV by Using Backstepping Approach

    Directory of Open Access Journals (Sweden)

    Xing Huo

    2014-01-01

    Full Text Available The modeling and attitude stabilization control problems of a four-rotor vertical takeoff and landing unmanned air vehicle (UAV known as the quadrotor are investigated. The quadrotor’s attitude is represented by the unit quaternion rather than Euler angles to avoid singularity problem. Taking dynamical behavior of motors into consideration and ignoring aerodynamic effect, a nonlinear controller is developed to stabilize the attitude. The control design is accomplished by using backstepping control technique. The proposed control law is based on the compensation for the Coriolis and gyroscope torques. Applying Lyapunov stability analysis proves that the closed-loop attitude system is asymptotic stable. Moreover, the controller can guarantee that all the states of the system are uniformly ultimately bounded in the presence of external disturbance torque. The effectiveness of the proposed control approach is analytically authenticated and also validated via simulation study.

  4. DC Microgrids – Part I: A Review of Control Strategies and Stabilization Techniques

    DEFF Research Database (Denmark)

    Dragicevic, Tomislav; Lu, Xiaonan; Quintero, Juan Carlos Vasquez;

    2016-01-01

    This paper presents a review of control strategies, stability analysis and stabilization techniques for DC microgrids (MGs). Overall control is systematically classified into local and coordinated control levels according to respective functionalities in each level. As opposed to local control...... which relies only on local measurements, some line of communication between units needs to be made available in order to achieve coordinated control. Depending on the communication method, three basic coordinated control strategies can be distinguished, i.e. decentralized, centralized and distributed...... control. Decentralized control can be regarded as an extension of local control since it is also based exclusively on local measurements. In contrast, centralized and distributed control strategies rely on digital communication technologies. A number of approaches to using these three coordinated control...

  5. On the stability of interval type-2 TSK fuzzy logic control systems.

    Science.gov (United States)

    Biglarbegian, Mohammad; Melek, William W; Mendel, Jerry M

    2010-06-01

    Type-2 fuzzy logic systems have recently been utilized in many control processes due to their ability to model uncertainties. This paper proposes a novel inference mechanism for an interval type-2 Takagi-Sugeno-Kang fuzzy logic control system (IT2 TSK FLCS) when antecedents are type-2 fuzzy sets and consequents are crisp numbers (A2-C0). The proposed inference mechanism has a closed form which makes it more feasible to analyze the stability of this FLCS. This paper focuses on control applications for the following cases: 1) Both plant and controller use A2-C0 TSK models, and 2) the plant uses type-1 Takagi-Sugeno (TS) and the controller uses IT2 TS models. In both cases, sufficient stability conditions for the stability of the closed-loop system are derived. Furthermore, novel linear-matrix-inequality-based algorithms are developed for satisfying the stability conditions. Numerical analyses are included which validate the effectiveness of the new inference methods. Case studies reveal that an IT2 TS FLCS using the proposed inference engine clearly outperforms its type-1 TSK counterpart. Moreover, due to the simple nature of the proposed inference engine, it is easy to implement in real-time control systems. The methods presented in this paper lay the mathematical foundations for analyzing the stability and facilitating the design of stabilizing controllers of IT2 TSK FLCSs and IT2 TS FLCSs with significantly improved performance over type-1 approaches.

  6. Power flow control and voltage stability limit: regulating transformer versus UPFC

    Energy Technology Data Exchange (ETDEWEB)

    Haque, M.H. [Nanyang Technological Univ., Center for Advanced Power Electronics, Nanyang (Singapore)

    2004-05-01

    Power flow through an AC transmission line can be controlled by injecting an adjustable compensating voltage in series with the line. This paper evaluates and compares the power flow control ranges of a simple system obtained by injecting an adjustable series compensating voltage produced by a regulating transformer and unified power flow controller. The static voltage stability limits of the system with a regulating transformer and unified power flow controller are also determined and compared. In evaluating the power flow control ranges and voltage stability limits, the transmission line of the system is modelled in four different ways. The results obtained for various line models are also compared. (Author)

  7. Energy cost of balance control during walking decreases with external stabilizer stiffness independent of walking speed.

    Science.gov (United States)

    Ijmker, Trienke; Houdijk, Han; Lamoth, Claudine J C; Beek, Peter J; van der Woude, Lucas H V

    2013-09-03

    Human walking requires active neuromuscular control to ensure stability in the lateral direction, which inflicts a certain metabolic load. The magnitude of this metabolic load has previously been investigated by means of passive external lateral stabilization via spring-like cords. In the present study, we applied this method to test two hypotheses: (1) the effect of external stabilization on energy cost depends on the stiffness of the stabilizing springs, and (2) the energy cost for balance control, and consequently the effect of external stabilization on energy cost, depends on walking speed. Fourteen healthy young adults walked on a motor driven treadmill without stabilization and with stabilization with four different spring stiffnesses (between 760 and 1820 Nm(-1)) at three walking speeds (70%, 100%, and 130% of preferred speed). Energy cost was calculated from breath-by-breath oxygen consumption. Gait parameters (mean and variability of step width and stride length, and variability of trunk accelerations) were calculated from kinematic data. On average external stabilization led to a decrease in energy cost of 6% (pwalking speed (p=0.111). These results show that active lateral stabilization during walking involves an energetic cost, which is independent of walking speed. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Detecting altered postural control after cerebral concussion in athletes with normal postural stability

    OpenAIRE

    Cavanaugh, J; Guskiewicz, K.; Giuliani, C.; Marshall, S.; Mercer, V; Stergiou, N.

    2005-01-01

    Objective: To determine if approximate entropy (ApEn), a regularity statistic from non-linear dynamics, could detect changes in postural control during quiet standing in athletes with normal postural stability after cerebral concussion.

  9. Stabilization of ODE-Schrodinger cascaded systems subject to boundary control matched disturbance

    Directory of Open Access Journals (Sweden)

    Ya-Ping Guo

    2015-09-01

    Full Text Available In this article, we consider the state feedback stabilization of ODE-Schrodinger cascaded systems with the external disturbance. We use the backstepping transformation to handle the unstable part of the ODE, then design a feedback control which is used to cope with the disturbance and stabilize the Schrodinger part. By active disturbance rejection control (ADRC approach, the disturbance is estimated by a constant high gain estimator, then the feedback control law can be designed. Next, we show that the resulting closed-loop system is practical stable, where the peaking value appears in the initial stage and the stabilized result requires that the derivative of disturbance be uniformly bounded. To avoid the peak phenomenon and to relax the restriction on the disturbance, a time varying high gain estimator is presented and asymptotical stabilization of the corresponding closed-loop system is proved. Finally, the effectiveness of the proposed control is verified by numerical simulations.

  10. Hypoxia and Human Genome Stability: Downregulation of BRCA2 Expression in Breast Cancer Cell Lines

    Directory of Open Access Journals (Sweden)

    Daniele Fanale

    2013-01-01

    Full Text Available Previously, it has been reported that hypoxia causes increased mutagenesis and alteration in DNA repair mechanisms. In 2005, an interesting study showed that hypoxia-induced decreases in BRCA1 expression and the consequent suppression of homologous recombination may lead to genetic instability. However, nothing is yet known about the involvement of BRCA2 in hypoxic conditions in breast cancer. Initially, a cell proliferation assay allowed us to hypothesize that hypoxia could negatively regulate the breast cancer cell growth in short term in vitro studies. Subsequently, we analyzed gene expression in breast cancer cell lines exposed to hypoxic condition by microarray analysis. Interestingly, genes involved in DNA damage repair pathways such as mismatch repair, nucleotide excision repair, nonhomologous end-joining and homologous recombination repair were downregulated. In particular, we focused on the BRCA2 downregulation which was confirmed at mRNA and protein level. In addition, breast cancer cells were treated with dimethyloxalylglycine (DMOG, a cell-permeable inhibitor of both proline and asparaginyl hydroxylases able to induce HIF-1α stabilization in normoxia, providing results comparable to those previously described. These findings may provide new insights into the mechanisms underlying genetic instability mediated by hypoxia and BRCA involvement in sporadic breast cancers.

  11. Controllability and Stabilization of Bilinear and Semilinear Partial Differential Equations

    DEFF Research Database (Denmark)

    Krishnaswamy, Vijayaraghavan

    The topic of the thesis is the investigation of the question of controllability of weakly nonlinear partial differntial equations. The method is based on the Hilbert Uniqueness Method.......The topic of the thesis is the investigation of the question of controllability of weakly nonlinear partial differntial equations. The method is based on the Hilbert Uniqueness Method....

  12. The Class of Stabilizing Nonlinear Plant Controller Pairs

    NARCIS (Netherlands)

    Paice, A.D.B.; Schaft, Arjan J. van der

    1996-01-01

    In this paper a general approach is taken to yield a characterization of the class of stable plant controller pairs which is a generalization of the Youla parameterization for linear systems. This is based on the idea of representing the input-output pairs of the plant and controller as elements of

  13. Control Mechanism Strategies for Spin-Stabilized Projectiles

    Science.gov (United States)

    2008-09-01

    from more traditional smart weapons, thus warranting basic research into guidance and control strategies. Conventional methods include canards, fins...moment arms. AACC XNXN  . (1) 14 CG CP Nose Base Figure 13. Relationship between maneuver footprint and control axial location. XC CG MC

  14. Fairness and Stability Analysis of Congestion Control Schemes in Vehicular Ad-hoc Networks

    CERN Document Server

    Nasiriani, Neda; Krishnan, Hariharan

    2012-01-01

    Cooperative vehicle safety (CVS) systems operate based on broadcast of vehicle position and safety information to neighboring cars. The communication medium of CVS is a vehicular ad-hoc network. One of the main challenges in large scale deployment of CVS systems is the issue of scalability. To address the scalability problem, several congestion control methods have been proposed and are currently under field study. These algorithms adapt transmission rate and power based on network measures such as channel busy ratio. We examine two such algorithms and study their dynamic behavior in time and space to evaluate stability (in time) and fairness (in space) properties of these algorithms. We present stability conditions and evaluate stability and fairness of the algorithms through simulation experiments. Results show that there is a trade-off between fast convergence, temporal stability and spatial fairness. The proper ranges of parameters for achieving stability are presented for the discussed algorithms. Stabil...

  15. Stability and control of wind farms in power systems

    DEFF Research Database (Denmark)

    Jauch, Clemens

    oscillating power injection can only be realised by controlling the pitch angle.Hence the power system stabiliser of an active-stall turbine is a pitch angle controller. Two different approaches are chosen for designing such a power system stabiliser: a conventional PID controller, and a fuzzy logic...... is part of the project. The mostextensive modelling work deals with the design of the electrical part of the variable speed turbine and its controls. To simulate realistic grid operation the wind turbine models are connected to an aggregated model of the Nordic power system. For thatpurpose the Nordic...... power system model, which was available prior to the project, is extended with a realistic feeder configuration. It is commonly demanded from modern wind turbines, that they must not disconnect in case of transient faults. Therefore,controllers are designed that enable the two turbine types to ride...

  16. Comparative genomic reconstruction of transcriptional networks controlling central metabolism in the Shewanella genus

    Energy Technology Data Exchange (ETDEWEB)

    Rodionov, Dmitry A.; Novichkov, Pavel; Stavrovskaya, Elena D.; Rodionova, Irina A.; Li, Xiaoqing; Kazanov, Marat D.; Ravcheev, Dmitry A.; Gerasimova, Anna V.; Kazakov, Alexey E.; Kovaleva, Galina Y.; Permina, Elizabeth A.; Laikova, Olga N.; Overbeek, Ross; Romine, Margaret F.; Fredrickson, Jim K.; Arkin, Adam P.; Dubchak, Inna; Osterman, Andrei L.; Gelfand, Mikhail S.

    2011-06-15

    Genome-scale prediction of gene regulation and reconstruction of transcriptional regulatory networks in bacteria is one of the critical tasks of modern genomics. Despite the growing number of genome-scale gene expression studies, our abilities to convert the results of these studies into accurate regulatory annotations and to project them from model to other organisms are extremely limited. The comparative genomics approaches and computational identification of regulatory sites are useful for the in silico reconstruction of transcriptional regulatory networks in bacteria. The Shewanella genus is comprised of metabolically versatile gamma-proteobacteria, whose lifestyles and natural environments are substantially different from Escherichia coli and other model bacterial species. To explore conservation and variations in the Shewanella transcriptional networks we analyzed the repertoire of transcription factors and performed genomics-based reconstruction and comparative analysis of regulons in 16 Shewanella genomes. The inferred regulatory network includes 82 transcription factors and their DNA binding sites, 8 riboswitches and 6 translational attenuators. Forty five regulons were newly inferred from the genome context analysis, whereas others were propagated from previously characterized regulons in the Enterobacteria and Pseudomonas spp.. However, even orthologous regulators with conserved DNA-binding motifs may control substantially different gene sets, revealing striking differences in regulatory strategies between the Shewanella spp. and E. coli. Multiple examples of regulatory network rewiring include regulon contraction and expansion (as in the case of PdhR, HexR, FadR), and numerous cases of recruiting non-orthologous regulators to control equivalent pathways (e.g. NagR for N-acetylglucosamine catabolism and PsrA for fatty acid degradation) and, conversely, orthologous regulators to control distinct pathways (e.g. TyrR, ArgR, Crp).

  17. Stability and Multiscroll Attractors of Control Systems via the Abscissa

    Directory of Open Access Journals (Sweden)

    Edgar-Cristian Díaz-González

    2017-01-01

    Full Text Available We present an approach to generate multiscroll attractors via destabilization of piecewise linear systems based on Hurwitz matrix in this paper. First we present some results about the abscissa of stability of characteristic polynomials from linear differential equations systems; that is, we consider Hurwitz polynomials. The starting point is the Gauss–Lucas theorem, we provide lower bounds for Hurwitz polynomials, and by successively decreasing the order of the derivative of the Hurwitz polynomial one obtains a sequence of lower bounds. The results are extended in a straightforward way to interval polynomials; then we apply the abscissa as a measure to destabilize Hurwitz polynomial for the generation of a family of multiscroll attractors based on a class of unstable dissipative systems (UDS of affine linear type.

  18. Advanced nonlinear control: Robustness and stability with applications to aircraft flight control systems

    Science.gov (United States)

    Frye, Michael Takaichi

    This dissertation examines the problem of global decentralized control by output feedback for large-scale uncertain nonlinear systems whose subsystems are interconnected not only by their outputs but also by their unmeasurable states. Several innovative techniques will be developed to create decentralized output feedback controllers rendering the closed-loop systems globally asymptotically stable. This is accomplished by extending an output feedback domination design that requires only limited information about the nonlinear system. We will apply our design to lower, upper, and non-triangular nonlinear systems. A time-varying output feedback controller is also constructed for use with large-scale systems that have unknown parameters. Furthermore, a mixed large-scale system consisting of both lower and upper triangular systems is shown to be stabilizable by employing a combined high and low gain domination technique. The significance of our results is that we do not need to have prior information about the nonlinearities of the system. In addition, a new design technique was developed using homogeneous system theory, which allows for the design of nonsmooth controllers and observers to stabilize a class of feedforward system with uncontrollable and unobservable linearization. An example of a large-scale system is a group of autonomous airships performing the function of a temporary mobile cell phone network. An airship mobile cell phone network is a novel solution to the problem of maintaining communication during the advent of extensive damage to the communication infrastructure; be it from a flood, earthquake, hurricane, or terrorist attack. A first principle force-based dynamic model for the Tri-Turbofan Airship was developed and will be discussed in detail. The mathematical model was based on actual flight test data that has been collected at the Gait Analysis and Innovative Technologies Laboratory. This model was developed to research autonomous airship

  19. Control design and comprehensive stability analysis of acrobots based on Lyapunov functions

    Institute of Scientific and Technical Information of China (English)

    LAI Xu-zhi; WU Yun-xin; SHE Jin-hua; WU Min

    2005-01-01

    A design method for controllers and a comprehensive stability analysis for an acrobat based on Lyapunov functions are presented. Three control laws based on three Lyapunov functions are designed to increase the energy so as to move the acrobot into the unstable inverted equilibrium position, and solve the problem of posture and energy. The concept of a non-smooth Lyapunov function is employed to analyze the stability of the whole system. The validity of this strategy is demonstrated by simulations.

  20. Active Disturbance Rejection Fuzzy Controller for Roll Stabilization of Autonomous Underwater Vehicle under Wave Disturbance

    OpenAIRE

    Lin-Lin Wang; Hong-Jian Wang; Li-Xin Pan; Jun-Xi Guo

    2015-01-01

    Considering the case of autonomous underwater vehicle navigating with low speed near water surface, a new method for designing of roll motion controller is proposed in order to restrain wave disturbance effectively and improve roll stabilizing performance under different sea conditions. Active disturbance rejection fuzzy control is applied, which is based on nonlinear motion model of autonomous underwater vehicle and the principle of zero-speed fin stabilizer. Extended state observer is used...

  1. p-moment stability of stochastic impulsive differential equations and its application in impulsive control

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The exponential p-moment stability of stochastic impulsive differential equations is addressed. A new theorem to ensure the p-moment stability is established for the trivial solution of the stochastic impul- sive differential system. As an application of the theorem proposed, the problem of controlling chaos of Lorenz system which is excited by parameter white-noise excitation is considered using impulsive control method. Finally, numerical simulation results are given to verify the feasibility of our approach.

  2. Robust Stability of Fractional Order Time-Delay Control Systems: A Graphical Approach

    OpenAIRE

    Radek Matušů; Roman Prokop

    2015-01-01

    The paper deals with a graphical approach to investigation of robust stability for a feedback control loop with an uncertain fractional order time-delay plant and integer order or fractional order controller. Robust stability analysis is based on plotting the value sets for a suitable range of frequencies and subsequent verification of the zero exclusion condition fulfillment. The computational examples present the typical shapes of the value sets of a family of closed-loop characteristic qua...

  3. Improved Stability Analysis of Nonlinear Networked Control Systems over Multiple Communication Links

    OpenAIRE

    Delavar, Rahim; Tavassoli, Babak; Beheshti, Mohammad Taghi Hamidi

    2015-01-01

    In this paper, we consider a nonlinear networked control system (NCS) in which controllers, sensors and actuators are connected via several communication links. In each link, networking effects such as the transmission delay, packet loss, sampling jitter and data packet miss-ordering are captured by time-varying delays. Stability analysis is carried out based on the Lyapunov Krasovskii method to obtain a condition for stability of the nonlinear NCS in the form of linear matrix inequality (LMI...

  4. p-moment stability of stochastic impulsive differential equations and its application in impulsive control

    Institute of Scientific and Technical Information of China (English)

    XU Wei; NIU Yudun; RONG HaiWu; SUN ZhongKui

    2009-01-01

    The exponential p-moment stability of stochastic impulsive differential equations is addressed. A new theorem to ensure the p-moment stability is established for the trivial solution of the stochastic impul-sive differential system. As an application of the theorem proposed, the problem of controlling chaos of Lorenz system which is excited by parameter white-noise excitation is considered using impulsive control method. Finally, numerical simulation results are given to verify the feasibility of our approach.

  5. Gain Scheduling Control of Gas Turbine Engines: Stability by Computing a Single Quadratic Lyapunov Function

    Science.gov (United States)

    2013-06-01

    STABILITY BY COMPUTING A SINGLE QUADRATIC LYAPUNOV FUNCTION Mehrdad Pakmehr∗ PhD Candidate Decision and Control Laboratory (DCL) School of Aerospace...linearization and linear matrix inequality (LMI) techniques. Using convex optimization tools, a single quadratic Lyapunov function is computed for multiple...Scheduling Control of Gas Turbine Engines: Stability by Computing a Single Quadratic Lyapunov Function 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c

  6. Controls on soil microbial community stability under climate change

    Directory of Open Access Journals (Sweden)

    Franciska T De Vries

    2013-09-01

    Full Text Available Soil microbial communities are intricately linked to ecosystem functioning because they play important roles in carbon and nitrogen cycling. Still, we know little about how soil microbial communities will be affected by disturbances expected with climate change. This is a significant gap in understanding, as the stability of microbial communities, defined as a community's ability to resist and recover from disturbances, likely has consequences for ecosystem function. Here, we propose a framework for predicting a community’s response to climate change, based on specific functional traits present in the community, the relative dominance of r- and K-strategists, and the soil environment. We hypothesize that the relative abundance of r- and K-strategists will inform about a community’s resistance and resilience to climate change associated disturbances. We also propose that other factors specific to soils, such as moisture content and the presence of plants, may enhance a community’s resilience. For example, recent evidence suggests microbial grazers, resource availability, and plant roots each impact on microbial community stability. We explore these hypotheses by offering three vignettes of published data that that we re-analyzed. Our results show that community measures of the relative abundance of r- and K-strategists, as well as environmental properties like resource availability and the abundance and diversity of higher trophic levels, can contribute to explaining the response of microbial community composition to climate change-related disturbances. However, further investigation and experimental validation is necessary to directly test these hypotheses across a wide range of soil ecosystems.

  7. Structural control of the stability of nuclear waste glasses

    Science.gov (United States)

    Calas, G.; Galoisy, L.; Cormier, L.; Bergeron, B.; Jollivet, P.

    2009-05-01

    Vitrification of liquid high-level radioactive waste in borosilicate glasses has received a great attention in several countries. The fundamental properties of the waste forms are their chemical and mechanical durability. We present an overview of the local structure of inactive analogs of the French nuclear glass, using structural information obtained by a combination of X-ray absorption Fine Structure (XAFS) and Wide Angle X-ray Scattering (WAXS). We will first contrast several classes of elements, such as Zr, Mo or Zn, which give nuclear glasses peculiar positive or adverse properties for the industrial process: enhanced chemical stability, phase separation, crystal nucleation and separation. These properties may be rationalized using Pauling rules, familiar to Mineralogists, as other properties are correctly modelled in simplified glass compositions using molecular dynamics. We will also point out the importance of the melt-to-glass transition and the consequence of the glass structural properties on the resistance of glassy matrices to irradiation. Glass alteration affects the long-term stability of the glass. It is characterized by an amorphous (glass)-amorphous (gel) transformation. Depending on alteration conditions, alteration layers may have or not a protective character, which will influence radionuclide retention over time. We will present the structural modification of the surface chemistry of the glass monoliths during short-term experiments and the evolution towards a gel, which forms progressively at the expense of the glass. The protective character of the gel, observed during glass leaching under near-saturated conditions, will be rationalized by its structural properties.

  8. Novel delay-partitioning stabilization approach for networked control system via Wirtinger-based inequalities.

    Science.gov (United States)

    Li, Zhichen; Bai, Yan; Huang, Congzhi; Cai, Yunfei

    2016-03-01

    This paper studies the problems of stability analysis and state feedback stabilization for networked control system. By developing a novel delay-partitioning approach, the information on both the range of network-induced delay and the maximum number of consecutive data packet dropouts can be taken into full consideration. Various augmented Lyapunov-Krasovskii functionals (LKFs) with triple-integral terms are constructed for the two delay subintervals. Moreover, the Wirtinger-based inequalities in combination with an improved reciprocal convexity are utilized to estimate the derivatives of LKFs more accurately. The proposed approaches have improved the stability conditions without increasing much computational complexity. Based on the obtained stability criterion, a stabilization controller design approach is also given. Finally, four numerical examples are presented to illustrate the effectiveness and outperformance of the proposed approaches.

  9. Stabilization of prescribed values and periodic orbits with regular and pulse target oriented control

    Energy Technology Data Exchange (ETDEWEB)

    Braverman, E., E-mail: maelena@ucalgary.ca; Chan, B. [Department of Mathematics and Statistics, University of Calgary, 2500 University Drive N.W., Calgary AB T2N 1N4 (Canada)

    2014-03-15

    Investigating a method of chaos control for one-dimensional maps, where the intervention is proportional to the difference between a fixed value and a current state, we demonstrate that stabilization is possible in one of the two following cases: (1) for small values, the map is increasing and the slope of the line connecting the points on the line with the origin is decreasing; (2) the chaotic map is locally Lipschitz. Moreover, in the latter case we prove that any point of the map can be stabilized. In addition, we study pulse stabilization when the intervention occurs each m-th step and illustrate that stabilization is possible for the first type of maps. In the context of population dynamics, we notice that control with a positive target, even if stabilization is not achieved, leads to persistent solutions and prevents extinction in models which experience the Allee effect.

  10. Stabilization of prescribed values and periodic orbits with regular and pulse target oriented control

    Science.gov (United States)

    Braverman, E.; Chan, B.

    2014-03-01

    Investigating a method of chaos control for one-dimensional maps, where the intervention is proportional to the difference between a fixed value and a current state, we demonstrate that stabilization is possible in one of the two following cases: (1) for small values, the map is increasing and the slope of the line connecting the points on the line with the origin is decreasing; (2) the chaotic map is locally Lipschitz. Moreover, in the latter case we prove that any point of the map can be stabilized. In addition, we study pulse stabilization when the intervention occurs each m-th step and illustrate that stabilization is possible for the first type of maps. In the context of population dynamics, we notice that control with a positive target, even if stabilization is not achieved, leads to persistent solutions and prevents extinction in models which experience the Allee effect.

  11. Genetic Control of Canine Leishmaniasis: Genome-Wide Association Study and Genomic Selection Analysis

    OpenAIRE

    Javier Quilez; Verónica Martínez; Woolliams, John A; Armand Sanchez; Ricardo Pong-Wong; Kennedy, Lorna J.; Quinnell, Rupert J.; Ollier, William E R; Xavier Roura; Lluís Ferrer; Laura Altet; Olga Francino

    2012-01-01

    BACKGROUND: The current disease model for leishmaniasis suggests that only a proportion of infected individuals develop clinical disease, while others are asymptomatically infected due to immune control of infection. The factors that determine whether individuals progress to clinical disease following Leishmania infection are unclear, although previous studies suggest a role for host genetics. Our hypothesis was that canine leishmaniasis is a complex disease with multiple loci responsible for...

  12. Global Output-Feedback Control for Simultaneous Tracking and Stabilization of Wheeled Mobile Robots

    Science.gov (United States)

    Chang, J.; Zhang, L. J.; Xue, D.

    A time-varying global output-feedback controller is presented that solves both tracking and stabilization for wheeled mobile robots simultaneously at the torque level. The controller synthesis is based on a coordinate transformation, Lyapunov direct method and backstepping technique. The performance of the proposed controller is demonstrated by simulation.

  13. Method of Time-Delay Calculating and Correcting to Control Spin-Stabilized Satellite Synchronously

    Institute of Scientific and Technical Information of China (English)

    YangTianshe; LiJisheng; HuangYongxuan

    2005-01-01

    The key to control Spin-Stabilized Satellites Synchronously is to determine the models for calculating and correcting of time-delay at the different situations. Based on the principle of Synchronous-Control mode, the methods of determining the models of calculating and correcting of time-delay are proposed. The methods have been proved to be effective in real satellite control engineering.

  14. The challenge of stabilizing control for queueing systems with unobservable server states

    NARCIS (Netherlands)

    Nazarathy, Y.; Taimre, T.; Asanjarani, A.; Kuhn, J.; Patch, B.; Vuorinen, A.

    2016-01-01

    We address the problem of stabilizing control for complex queueing systems where servers follow unobservable Markovian environments. The controller needs to assign servers to queues without full information about the servers' states. A control challenge is to devise a policy that matches servers to

  15. Variation Analysis and Stability Control for Measurement Process

    Institute of Scientific and Technical Information of China (English)

    ZHAO Feng-yu; MA Yi-zhong; Bo Bergman; XU Ji-chao

    2002-01-01

    Based on a two-section measuring method, a data collection sheet is formed. According to the data collected, the variation sources of a measurement process are analyzed and general guidelines for variation diagnosis are suggested. In our previous study, a method is presented to control the deviation of measurement system, but it is not sensitive to mean value variation and mean value drift. In this paper, a simplified data collection scheme via two-section measuring method is introduced to control both variation and center drift of measurement process. Based on this scheme, traditional SPC charts for variation control and EWMA chart for mean value drift are given.

  16. Optimal Control of a Ballast-Stabilized Floating Wind Turbine

    DEFF Research Database (Denmark)

    Christiansen, Søren; Knudsen, Torben; Bak, Thomas

    2011-01-01

    Offshore wind energy capitalizes on the higher and less turbulent wind speeds at sea. The use of floating structures for deeper waters is being explored. The control objective is a tradeoff between power capture and fatigue, especially that produced by the oscillations caused by the reduced...... estimator and a state observer. The results are simulated using aero elastic code and analysed in terms of damage equivalent loads. When compared to a baseline controller, this controller clearly demonstrates better generator speed and power tracking while reducing fatigue loads....

  17. Stability

    Directory of Open Access Journals (Sweden)

    Nada S. Abdelwahab

    2017-05-01

    Full Text Available The present work concerns with the development of stability indicating the RP-HPLC method for simultaneous determination of guaifenesin (GUF and pseudoephedrine hydrochloride (PSH in the presence of guaifenesin related substance (Guaiacol. GUC, and in the presence of syrup excepients with minimum sample pre-treatment. In the developed RP-HPLC method efficient chromatographic separation was achieved for GUF, PSH, GUC and syrup excepients using ODS column as a stationary phase and methanol: water (50:50, v/v, pH = 4 with orthophosphoric acid as a mobile phase with a flow rate of 1 mL min−1 and UV detection at 210 nm. The chromatographic run time was approximately 10 min. Calibration curves were drawn relating the integrated area under peak to the corresponding concentrations of PSH, GUF and GUC in the range of 1–8, 1–20, 0.4–8 μg mL−1, respectively. The developed method has been validated and met the requirements delineated by ICH guidelines with respect to linearity, accuracy, precision, specificity and robustness. The validated method was successfully applied for determination of the studied drugs in triaminic chest congestion® syrup; moreover its results were statistically compared with those obtained by the official method and no significant difference was found between them.

  18. Stability analysis via the concept of Lyapunov exponents: a case study in optimal controlled biped standing

    Science.gov (United States)

    Sun, Yuming; Wu, Christine Qiong

    2012-12-01

    Balancing control is important for biped standing. In spite of large efforts, it is very difficult to design balancing control strategies satisfying three requirements simultaneously: maintaining postural stability, improving energy efficiency and satisfying the constraints between the biped feet and the ground. In this article, a proportional-derivative (PD) controller is proposed for a standing biped, which is simplified as a two-link inverted pendulum with one additional rigid foot-link. The genetic algorithm (GA) is used to search for the control gain meeting all three requirements. The stability analysis of such a deterministic biped control system is carried out using the concept of Lyapunov exponents (LEs), based on which, the system stability, where the disturbance comes from the initial states, and the structural stability, where the disturbance comes from the PD gains, are examined quantitively in terms of stability region. This article contributes to the biped balancing control, more significantly, the method shown in the studied case of biped provides a general framework of systematic stability analysis for certain deterministic nonlinear dynamical systems.

  19. Computation of stabilizing PI and PID controllers for processes with time delay.

    Science.gov (United States)

    Tan, Nusret

    2005-04-01

    In this paper, a new method for the computation of all stabilizing PI controllers for processes with time delay is given. The proposed method is based on plotting the stability boundary locus in the (kp, ki) plane and then computing the stabilizing values of the parameters of a PI controller for a given time delay system. The technique presented does not need to use Pade approximation and does not require sweeping over the parameters and also does not use linear programming to solve a set of inequalities. Thus it offers several important advantages over existing results obtained in this direction. Beyond stabilization, the method is used to compute stabilizing PI controllers which achieve user specified gain and phase margins. The proposed method is also used to design PID controllers for control systems with time delay. The limiting values of a PID controller which stabilize a given system with time delay are obtained in the (kp, ki) plane, (kp, kd) plane, and (ki, kd) plane. Examples are given to show the benefits of the method presented.

  20. Stabilizing control system preventing loss of synchronism from extension and its actual operating experience

    Energy Technology Data Exchange (ETDEWEB)

    Matsuzawa, K.; Yanagihashi, K.; Tsukita, J. [Tokyo Electric Power Co. (Japan); Sato, M.; Nakamura, T.; Takeuchi, A.

    1995-08-01

    This paper presents a stabilizing control system that was implemented to the power system of Tokyo Electric Power Company and worked successfully, shedding the minimum number of generators and preventing the extension of loss of synchronism to the other generators when a severe fault occurred on May 22, 1992. The stabilizing control system measures voltage and current at the rate of 600 Hz, predicts the change of phase angles of generators and decides the minimum number of generators to be shed for stabilization when instability is predicted and sheds them.

  1. RESEARCH ON STABILITY AND MINIMUM ORIFICE AREA OF HYDRAULIC SERVO POSITION CONTROL SYSTEM

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper reports results of research on the stability of a hydraulic servo position system using generalization pulse code modulation (GPCM) and common on/off valves for hydraulic servo control. The de- scribing function was first used to analyze the system′s stability, and based on the nonlinear theory, an equation calculating the minimum orifice area of GPCM valves was derived by applying results of analysis on the stability of the GPCM control system. In the end, aimed at developing a hydraulic servo position system to be used in a paint robot, simulation and experiment were carried out. The results show that the theoretical conclusions accorded with practical results.

  2. Exponential stability of a PI plus reset integrator controller by a sampled-data system approach

    OpenAIRE

    Davó, M. A.; Gouaisbaut, F.; Baños, A; Tarbouriech, S.; Seuret, A.

    2016-01-01

    The paper deals with the stability analysis of time-delay reset control systems, for which the resetting law is assumed to satisfy a time-dependent condition. A stability analysis of the closed-loop system is performed based on an appropriate sampled-data system. New linear matrix inequality (LMI) conditions are proposed to ensure the exponential stability of the closed-loop resulting of the connection of a plant with a proportional and integral controller together with a reset integrator (PI...

  3. Floquet-based chaos control for continuous-time systems with stability analysis

    Energy Technology Data Exchange (ETDEWEB)

    Sakamoto, Noboru [Department of Aerospace Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)]. E-mail: sakamoto@nuae.nagoya-u.ac.jp

    2006-08-14

    In this Letter, a framework for controlling continuous-time chaotic systems is proposed. The framework is based on the Floquet theory of linear periodic differential equations and provides a practical method to stabilize unstable periodic orbits (UPOs) and a stability analysis of the closed loop systems. An example of controlling the circular restricted three-body problem known as halo orbits is illustrated. It is also reported that stabilization of UPOs can be effective by using the maximum principle to select a nominal orbit. It also turns out that the proposed framework enables us to give a theoretical account of the well-known occasional proportional feedback (OPF)

  4. Robust stabilization control based on guardian maps theory for a longitudinal model of hypersonic vehicle.

    Science.gov (United States)

    Liu, Yanbin; Liu, Mengying; Sun, Peihua

    2014-01-01

    A typical model of hypersonic vehicle has the complicated dynamics such as the unstable states, the nonminimum phases, and the strong coupling input-output relations. As a result, designing a robust stabilization controller is essential to implement the anticipated tasks. This paper presents a robust stabilization controller based on the guardian maps theory for hypersonic vehicle. First, the guardian maps theories are provided to explain the constraint relations between the open subsets of complex plane and the eigenvalues of the state matrix of closed-loop control system. Then, a general control structure in relation to the guardian maps theories is proposed to achieve the respected design demands. Furthermore, the robust stabilization control law depending on the given general control structure is designed for the longitudinal model of hypersonic vehicle. Finally, a simulation example is provided to verify the effectiveness of the proposed methods.

  5. Stabilization of a (3,0) mobile robot by means of an event-triggered control.

    Science.gov (United States)

    Villarreal-Cervantes, Miguel G; Guerrero-Castellanos, J Fermi; Ramírez-Martínez, Soledad; Sánchez-Santana, J Pedro

    2015-09-01

    Event-triggered control (ETC) is a sampling strategy that updates the control value only when some events related to the state of the system occurs. It therefore relaxes the periodicity of control updates without deteriorating the closed-loop performance. This paper develops a nonlinear ETC for the stabilization of a (3,0) mobile robot. The construction of an event function and a feedback function is carried out based on the existence of a stabilizing control law and a Control Lyapunov Function (CLF). The event function is dependent on the time derivative of the CLF and the feedback function results from the extension of Sontag's formula, which ensures asymptotic stability, smoothness everywhere and continuity at the equilibrium. Experimental results, compared with a computed torque control, validate the theoretical analysis.

  6. Stabilization and Control Models of Systems With Hysteresis Nonlinearities

    Directory of Open Access Journals (Sweden)

    Mihail E. Semenov

    2012-05-01

    Full Text Available Mechanical and economic systems with hysteresis nonlinearities are studied in article. Dissipativity condition of inverted pendulum under the hysteresis control is obtained. The solution of the optimal production strategy problem was found where price has hysteresis behaviour.

  7. Controllability, observability, realizability, and stability of dynamic linear systems

    OpenAIRE

    Davis, John M.; Gravagne, Ian A.; Jackson, Billy J.; Marks II, Robert J.

    2009-01-01

    We develop a linear systems theory that coincides with the existing theories for continuous and discrete dynamical systems, but that also extends to linear systems defined on nonuniform time scales. The approach here is based on generalized Laplace transform methods (e.g. shifts and convolution) from the recent work [13]. We study controllability in terms of the controllability Gramian and various rank conditions (including Kalman's) in both the time invariant and time varying settings...

  8. Input-output stability for accelerometer control systems

    Science.gov (United States)

    Banks, H. T.; Morris, K. A.

    1991-01-01

    It is shown that, although accelerometer control systems are not well-posed in the sense of Salamon, a well-defined input-output relation exists. It is established that the output of an accelerometer control system can be described by the convolution of the input and a distribution. This distribution is Laplace transformable, and the Laplace transform of the distribution is the transfer function of the system.

  9. Echinococcus granulosus genomics: a new dawn for improved diagnosis, treatment, and control of echinococcosis.

    Science.gov (United States)

    Zhang, Wenbao; Wang, Shengyue; McManus, Donald P

    2014-01-01

    Cystic echinococcosis (CE) is a cosmopolitan disease caused by the dog tapeworm Echinococcus granulosus. The disease is difficult to diagnose, treat, and control and is responsible for considerable human morbidity and mortality globally. There is an urgent need for new diagnostic tests and new drugs for treatment of CE and the development of a vaccine against adult worms of E. granulosus in dogs. We recently presented a draft genomic sequence for the worm comprising 151.6 Mb encoding 11,325 proteins. We undertook an extensive comparative analysis of the E. granulosus transcriptome using representative life stages (protoscoleces, cyst germinal cells and membranes, adult worms, and oncospheres) to explore different aspects of tapeworm biology and parasitism. The genome and transcriptome of E. granulosus provide a unique platform for post-genomic research and to facilitate the development of new, effective treatments and interventions for echinococcosis control.

  10. Gain Scheduling Control of Gas Turbine Engines: Absolute Stability by Finding a Common Lyapunov Matrix

    OpenAIRE

    Pakmehr, Mehrdad; Fitzgerald, Nathan; Feron, Eric; Shamma, Jeff; Behbahani, Alireza

    2012-01-01

    This manuscript aims to develop and describe gain scheduling control concept for a gas turbine engine which drives a variable pitch propeller. An architecture for gain-scheduling control is developed that controls the turboshaft engine for large thrust commands in stable fashion with good performance. Fuel ow and propeller pitch angle are the two control inputs of the system. New stability proof has been developed for gain scheduling control of gas turbine engines using global linearization a...

  11. Electric Machine with Boosted Inductance to Stabilize Current Control

    Science.gov (United States)

    Abel, Steve

    2013-01-01

    High-powered motors typically have very low resistance and inductance (R and L) in their windings. This makes the pulse-width modulated (PWM) control of the current very difficult, especially when the bus voltage (V) is high. These R and L values are dictated by the motor size, torque (Kt), and back-emf (Kb) constants. These constants are in turn set by the voltage and the actuation torque-speed requirements. This problem is often addressed by placing inductive chokes within the controller. This approach is undesirable in that space is taken and heat is added to the controller. By keeping the same motor frame, reducing the wire size, and placing a correspondingly larger number of turns in each slot, the resistance, inductance, torque constant, and back-emf constant are all increased. The increased inductance aids the current control but ruins the Kt and Kb selections. If, however, a fraction of the turns is moved from their "correct slot" to an "incorrect slot," the increased R and L values are retained, but the Kt and Kb values are restored to the desired values. This approach assumes that increased resistance is acceptable to a degree. In effect, the heat allocated to the added inductance has been moved from the controller to the motor body, which in some cases is preferred.

  12. Robust D-Stability Controller Design for a Ducted Fan Unmanned Aerial Vehicle

    Directory of Open Access Journals (Sweden)

    Xiao-lu Ren

    2014-01-01

    Full Text Available This paper deals with the aerodynamic modeling of a small ducted fan UAV and the problem of attitude stabilization when the parameter of the vehicle is varied. The main aerodynamic model of the hovering flight UAV is first presented. Then, an attitude control is designed from a linearization of the dynamic model around the hovering flight, which is based on the H∞ output feedback control theory with D-stability. Simulation results show that such method has good robustness to the attitude system. They can meet the requirements of attitude control and verify further the feasibility of such a control strategy.

  13. STUDY ON DYNAMICS, STABILITY AND CONTROL OF MULTI-BODY FLEXIBLE STRUCTURE SYSTEM IN FUNCTIONAL SPACE

    Institute of Scientific and Technical Information of China (English)

    徐建国; 贾军国

    2001-01-01

    The dynamics, stability and control problem of a kind of infinite dimensional system are studied in the functional space with the method of modern mathematics. First,the dynamical control model of the distributed parameter system with multi-body flexible and multi-topological structure was established which has damping, gyroscopic parts and constrained damping. Secondly, the necessary and sufficient condition of controllability and observability, the stability theory and asymptotic property of the system were obtained.These results expand the theory of the field about the dynamics and control of the system with multi-body flexible structure, and have important engineering significance.

  14. Nonlinear model predictive control with guaraneed stability based on pesudolinear neural networks

    Institute of Scientific and Technical Information of China (English)

    WANG Yongji; WANG Hong

    2004-01-01

    A nonlinear model predictive control problem based on pseudo-linear neural network (PNN) is discussed, in which the second order on-line optimization method is adopted. The recursive computation of Jacobian matrix is investigated. The stability of the closed loop model predictive control system is analyzed based on Lyapunov theory to obtain the sufficient condition for the asymptotical stability of the neural predictive control system. A simulation was carried out for an exothermic first-order reaction in a continuous stirred tank reactor. It is demonstrated that the proposed control strategy is applicable to some of nonlinear systems.

  15. Global stability and optimal control of an SIRS epidemic model on heterogeneous networks

    Science.gov (United States)

    Chen, Lijuan; Sun, Jitao

    2014-09-01

    In this paper, we consider an SIRS epidemic model with vaccination on heterogeneous networks. By constructing suitable Lyapunov functions, global stability of the disease-free equilibrium and the endemic equilibrium of the model is investigated. Also we firstly study an optimally controlled SIRS epidemic model on complex networks. We show that an optimal control exists for the control problem. Finally some examples are presented to show the global stability and the efficiency of this optimal control. These results can help in adopting pragmatic treatment upon diseases in structured populations.

  16. Backstepping Controller with Intelligent Parameters Selection for Stabilization of Quadrotor Helicopter

    Directory of Open Access Journals (Sweden)

    Mohd Ariffanan Mohd Basri

    2016-07-01

    Full Text Available In this paper, the dynamic model of quadrotor helicopter has been mathematically formulated. Then, an intelligent backstepping controller (IBC is designed for the quadrotor altitude and attitude stabilization in the existence of external disturbances and measurement noise. The designed controller consists of a backstepping controller which can automatically select its parameters on-line by a fuzzy supervisory mechanism. The stability criterion for the stabilization of the quadrotor is proven by the Lyapunov theorem. Several numerical simulations using the dynamic model of a four degree of freedom (DOF quadrotor helicopter show the effectiveness of the approach. Besides, the simulation results indicate that the proposed design techniques can stabilize the quadrotor helicopter with better performance than established linear design techniques.

  17. ATC Enhancement Considering Transient Stability by Optimal Power Flow Control Using UPFC

    Science.gov (United States)

    Masuta, Taisuke; Motoki, Hiroaki; Yokoyama, Akihiko

    With recent development of power electronics technology, power system stability enhancement and optimal power flow control by using Flexible AC Transmission System (FACTS) devices have so far been studied. The FACTS devices to relieve multiple constraints can also make it possible to enhance Available Transfer Capability (ATC) without construction of new transmission lines. In this paper, a new method for improving transient stability by Unified Power Flow Controller (UPFC) is proposed. Then the proposed method is applied to an OPF control method by using UPFC for relieving multiple constraints. The new OPF method is used for enhancement of ATC taking into account Transient stability constraints as well as overload and steady-state stability constraints. The OPF problem is formulated to minimize total capacity of inverters of UPFC. Effectiveness of the proposed method is shown by numerical examples for IEEJ East-10-machine test system.

  18. Conserved interaction of Ctf18-RFC with DNA polymerase ε is critical for maintenance of genome stability in Saccharomyces cerevisiae.

    Science.gov (United States)

    Okimoto, Hiroko; Tanaka, Seiji; Araki, Hiroyuki; Ohashi, Eiji; Tsurimoto, Toshiki

    2016-05-01

    Human Ctf18-RFC, a PCNA loader complex, interacts with DNA polymerase ε (Polε) through a structure formed by the Ctf18, Dcc1 and Ctf8 subunits. The C-terminal stretch of Ctf18, which is highly conserved from yeast to human, is necessary to form the Polε-capturing structure. We found that in the budding yeast Saccharomyces cerevisiae, Ctf18, Dcc1 and Ctf8 formed the same structure through the conserved C-terminus and interacted specifically with Polε. Thus, the specific interaction of Ctf18-RFC with Polε is a conserved feature between these proteins. A C-terminal deletion mutant of Ctf18 (ctf18(ΔC) ) exhibited the same high sensitivity to hydroxyurea as the complete deletion strain (ctf18Δ) or ATPase-deficient mutant (ctf18(K189A) ), but was somewhat less sensitive to methyl methanesulfonate than either of them. These phenotypes were also observed in dcc1Δ and ctf8Δ, predicted to be deficient in the interaction with Polε. Furthermore, both plasmid loss and gross chromosomal rearrangement (GCR) rates were increased in ctf18(ΔC) cells to the same extent as in ctf18Δ cells. These results indicate that the Ctf18-RFC/Polε interaction plays a crucial role in maintaining genome stability in budding yeast, probably through recruitment of this PCNA loader to the replication fork.

  19. Redox regulation of genome stability by effects on gene expression, epigenetic pathways and DNA damage/repair.

    Science.gov (United States)

    Mikhed, Yuliya; Görlach, Agnes; Knaus, Ulla G; Daiber, Andreas

    2015-08-01

    Reactive oxygen and nitrogen species (e.g. H2O2, nitric oxide) confer redox regulation of essential cellular signaling pathways such as cell differentiation, proliferation, migration and apoptosis. In addition, classical regulation of gene expression or activity, including gene transcription to RNA followed by translation to the protein level, by transcription factors (e.g. NF-κB, HIF-1α) and mRNA binding proteins (e.g. GAPDH, HuR) is subject to redox regulation. This review will give an update of recent discoveries in this field, and specifically highlight the impact of reactive oxygen and nitrogen species on DNA repair systems that contribute to genomic stability. Emphasis will be placed on the emerging role of redox mechanisms regulating epigenetic pathways (e.g. miRNA, DNA methylation and histone modifications). By providing clinical correlations we discuss how oxidative stress can impact on gene regulation/activity and vise versa, how epigenetic processes, other gene regulatory mechanisms and DNA repair can influence the cellular redox state and contribute or prevent development or progression of disease.

  20. Essential developmental, genomic stability, and tumour suppressor functions of the mouse orthologue of hSSB1/NABP2.

    Directory of Open Access Journals (Sweden)

    Wei Shi

    Full Text Available Single-stranded DNA binding proteins (SSBs regulate multiple DNA transactions, including replication, transcription, and repair. We recently identified SSB1 as a novel protein critical for the initiation of ATM signaling and DNA double-strand break repair by homologous recombination. Here we report that germline Ssb1(-/- embryos die at birth from respiratory failure due to severe rib cage malformation and impaired alveolar development, coupled with additional skeletal defects. Unexpectedly, Ssb1(-/- fibroblasts did not exhibit defects in Atm signaling or γ-H2ax focus kinetics in response to ionizing radiation (IR, and B-cell specific deletion of Ssb1 did not affect class-switch recombination in vitro. However, conditional deletion of Ssb1 in adult mice led to increased cancer susceptibility with broad tumour spectrum, impaired male fertility with testicular degeneration, and increased radiosensitivity and IR-induced chromosome breaks in vivo. Collectively, these results demonstrate essential roles of Ssb1 in embryogenesis, spermatogenesis, and genome stability in vivo.