... by aspirin, ethylene glycol (found in antifreeze), or methanol Severe dehydration Lactic acidosis is a buildup of ... M. is among the first to achieve this important distinction for online health information and services. Learn ...
Delayed high anion gap metabolic acidosis after a suicide attempt: case report.
Hsiao, Po-Jen; Chen, Tsu-Yi; Chiu, Chih-Chien; Wu, Tsung-Jui; Chan, Jenq-Shyong; Wu, Chia-Chao; Chen, Jin-Shuen
2014-09-25
Metabolic acidosis, especially when induced by multiple drug poisoning, often makes rapid and accurate differential diagnosis of the condition challenging. We closely followed anion and osmolal gaps to differentiate among the aetiologies of metabolic acidosis caused by poisoning with unknown drugs. The patient was admitted to our emergency department (ED) in an alert and consciousness state after attempting suicide by ingestion of an uncertain quantity of rodenticides combined with an unknown liquid. Initially, metabolic acidosis (pH7.23) with normal anion gap (12.8) was observed. However, a change in consciousness and hypotension subsequently developed 6h later, combined with severe metabolic acidosis (pH7.16), high anion gap (25.5), and high osmolal gap (83). A presumed diagnosis of methanol intoxication was suspected. After 4h of high-flux haemodialysis (HD), the serum bicarbonate returned to 23 mmol/l, and the patient regained consciousness. The serum level of methanol before HD was 193.8 mg/dl. The patient was discharged nine days later without sequelae. Delayed high anion gap metabolic acidosis may occur in the ED. Frequent monitoring of anion and osmolal gaps is a feasible method to perform a rapid differential diagnosis, particularly in response to drug poisoning. Copyright © 2014 Elsevier B.V. All rights reserved.
Ventilatory failure; Respiratory failure; Acidosis - respiratory ... Causes of respiratory acidosis include: Diseases of the airways (such as asthma and COPD ) Diseases of the lung tissue (such as ...
... DKA. Hyperchloremic acidosis results from excessive loss of sodium bicarbonate from the body. This can occur with severe ... health problem causing the acidosis. In some cases, sodium bicarbonate (the chemical in baking soda) may be given ...
Control systems with network delay
Şabanoviç, Asif; Sabanovic, Asif; Ohnishi, Kouhei; Yashiro, Daisuke; Acer, Merve; Ş.-Behliloviç, Nadira; S.-Behlilovic, Nadira
2009-01-01
In this paper motion control systems with delay in measurement and control channels are discussed and a new structure of the observer-predictor is proposed. The feature of the proposed system is enforcement of the convergence in both the estimation and the prediction of the plant output in the presence of the variable, unknown delay in both measurement and in the control channels. The estimation is based on the available data – undelayed control input, the delayed measurement of position o...
Directory of Open Access Journals (Sweden)
Lletta Lewis
2018-04-01
Full Text Available Zebrafish (Danio rerio have become an important model for integrative physiological research. Zebrafish inhabit a hypo-osmotic environment; to maintain ionic and acid-base homeostasis, they must actively take up ions and secrete acid to the water. The gills in the adult and the skin at larval stage are the primary sites of ionic regulation in zebrafish. The uptake of ions in zebrafish is mediated by specific ion transporting cells termed ionocytes. Similarly, in mammals, ion reabsorption and acid excretion occur in specific cell types in the terminal region of the renal tubules (distal convoluted tubule and collecting duct. Previous studies have suggested that functional regulation of several ion transporters/channels in the zebrafish ionocytes resembles that in the mammalian renal cells. Additionally, several mechanisms involved in regulating the epithelial ion transport during metabolic acidosis are found to be similar between zebrafish and mammals. In this article, we systemically review the similarities and differences in ionic regulation between zebrafish and mammals during metabolic acidosis. We summarize the available information on the regulation of epithelial ion transporters during acidosis, with a focus on epithelial Na+, Cl− and Ca2+ transporters in zebrafish ionocytes and mammalian renal cells. We also discuss the neuroendocrine responses to acid exposure, and their potential role in ionic compensation. Finally, we identify several knowledge gaps that would benefit from further study.
Delays and networked control systems
Hetel, Laurentiu; Daafouz, Jamal; Johansson, Karl
2016-01-01
This edited monograph includes state-of-the-art contributions on continuous time dynamical networks with delays. The book is divided into four parts. The first part presents tools and methods for the analysis of time-delay systems with a particular attention on control problems of large scale or infinite-dimensional systems with delays. The second part of the book is dedicated to the use of time-delay models for the analysis and design of Networked Control Systems. The third part of the book focuses on the analysis and design of systems with asynchronous sampling intervals which occur in Networked Control Systems. The last part of the book exposes several contributions dealing with the design of cooperative control and observation laws for networked control systems. The target audience primarily comprises researchers and experts in the field of control theory, but the book may also be beneficial for graduate students. .
Directory of Open Access Journals (Sweden)
Young Larry
2011-03-01
Full Text Available Abstract Introduction Type 4 renal tubular acidosis is an uncommon clinical manifestation of systemic lupus erythematosus and has been reported to portend a poor prognosis. To the best of our knowledge, this is the first case report which highlights the successful management of a patient with systemic lupus erythematosus complicated by type 4 renal tubular acidosis who did not do poorly. Case presentation A 44-year-old Hispanic woman developed a non-anion gap hyperkalemic metabolic acidosis consistent with type 4 renal tubular acidosis while being treated in the hospital for recently diagnosed systemic lupus erythematosus with multi-organ involvement. She responded well to treatment with corticosteroids, hydroxychloroquine and mycophenolate mofetil. Normal renal function was achieved prior to discharge and remained normal at the patient's one-month follow-up examination. Conclusion This case increases awareness of an uncommon association between systemic lupus erythematosus and type 4 renal tubular acidosis and suggests a positive impact of early diagnosis and appropriate immunosuppressive treatment on the patient's outcome.
Lactic acidosis, hyperlactatemia and sepsis
Directory of Open Access Journals (Sweden)
Andrea Montagnani
2016-12-01
Full Text Available Among hospitalized patients, lactic acidosis represents the most common cause of metabolic acidosis. Lactate is not just a metabolic product of anaerobic glycolysis but is triggered by a variety of metabolites even before the onset of anaerobic metabolism as part of an adaptive response to a hypermetabolic state. On the basis of such considerations, lactic acidosis is divided into two classes: inadequate tissue oxygenation (type A and absence of tissue hypoxia (type B. Lactic acidosis is characterized by non-specific symptoms but it should be suspected in all critical patients who show hypovolemic, hypoxic, in septic or cardiogenic shock or if in the presence of an unexplained high anion gap metabolic acidosis. Lactic acidosis in sepsis and septic shock has traditionally been explained as a result of tissue hypoxia when whole-body oxygen delivery fails to meet whole body oxygen requirements. In sepsis lactate levels correlate with increased mortality with a poor prognostic threshold of 4 mmol/L. In hemodynamically stable patients with sepsis, hyperlactatemia might be the result of impaired lactate clearance rather than overproduction. In critically ill patients the speed at which hyperlactatemia resolves with appropriate therapy may be considered a useful prognostic indicator. The measure of blood lactate should be performed within 3 h of presentation in acute care setting. The presence of lactic acidosis requires early identification of the primary cause of shock for the best appropriate treatment. Since most cases of lactic acidosis depend on whole-body oxygen delivery failure, the maximization of systemic oxygen delivery remains the primary therapeutic option. When initial resuscitation does not substantially or completely correct lactic acidosis, it is also essential to consider other causes. The treatment of acidosis with buffering agents (specifically bicarbonate is generally advocated only in the setting of severe acidosis. Ongoing
... the body's immune system mistakenly attacks healthy tissue Wilson disease , an inherited disorder in which there is too much copper in the body's tissues Use of certain medicines, such as amphotericin B, lithium, and analgesics Symptoms Symptoms of distal renal tubular acidosis include any ...
Laskoski, Luciane M.; Muraro, Lívia S.; Santana Júnior, Marinho S.; Carvalho, Mariana B.; Freitas, Silvio H.; Dória, Renata G.S.; Santos, Marcelo D.; Dittrich, Rosangela Locatelli
2014-01-01
The aim of this study was to evaluate the preventive effect of sodium bicarbonate on systemic acidosis due to ruminal acidosis, which was induced by ingestion of concentrate after prolonged fasting. Fourteen sheep were divided into three experimental groups: control group (Cg), with four sheep, submitted to fasting without development of ruminal acidosis; no-treated group (NTg), with five sheep with rumen acidosis without preventive treatment; and treated group (Tg), with five sheep with rume...
Memorized discrete systems and time-delay
Luo, Albert C J
2017-01-01
This book examines discrete dynamical systems with memory—nonlinear systems that exist extensively in biological organisms and financial and economic organizations, and time-delay systems that can be discretized into the memorized, discrete dynamical systems. It book further discusses stability and bifurcations of time-delay dynamical systems that can be investigated through memorized dynamical systems as well as bifurcations of memorized nonlinear dynamical systems, discretization methods of time-delay systems, and periodic motions to chaos in nonlinear time-delay systems. The book helps readers find analytical solutions of MDS, change traditional perturbation analysis in time-delay systems, detect motion complexity and singularity in MDS; and determine stability, bifurcation, and chaos in any time-delay system.
Stability investigation of quadratic systems with delay
Directory of Open Access Journals (Sweden)
Vladimir Davydov
2000-01-01
Full Text Available Systems of differential equations with quadratic right-hand sides with delay are considered in the paper. Compact matrix notation form is proposed for the systems of such type. Stability investigations are performed by Lyapunov's second method with functions of quadratic form. Stability conditions of quadratic systems with delay, uniformly by argument deviation, and with delay depending on the system's parameters are derived. A guaranteed radius of the ball of asymptotic stability region for zero solution is obtained.
System delays in breast cancer
African Journals Online (AJOL)
we notice a discrepancy in incidence rates between various ethnic/race .... Thailand. 180. 2. 3. 5 to diagnosis NOT treatment‡. This study. South Africa 45. -. 2.5. 3. 1.25. 3. -. 10. *Total delay refers to totals for available datasets and not necessarily mean delay to treatment/surgery commencement. †Montella et al. presented ...
Controllability of nonlinear delay oscillating systems
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Chengbin Liang
2017-05-01
Full Text Available In this paper, we study the controllability of a system governed by second order delay differential equations. We introduce a delay Gramian matrix involving the delayed matrix sine, which is used to establish sufficient and necessary conditions of controllability for the linear problem. In addition, we also construct a specific control function for controllability. For the nonlinear problem, we construct a control function and transfer the controllability problem to a fixed point problem for a suitable operator. We give a sufficient condition to guarantee the nonlinear delay system is controllable. Two examples are given to illustrate our theoretical results by calculating a specific control function and inverse of a delay Gramian matrix.
Metabolic Acidosis: Diagnostics and Treatment
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R. F. Tepaev
2016-01-01
Full Text Available Metabolic acidosis is the most common child acid-base balance disorder. This condition accompanies a variety of diseases, and the degree of its severity correlates with the patients’ survival: although not a separate disease in itself, metabolic acidosis, however, can worsen the disease course and even lead to death. The pathology causes are various (in connection with life-threatening changes in various organs and systems — lungs, heart and blood vessels, kidneys, and also due to a violation of lipid metabolism, in case of diabetes, poisoning, etc., which determines the fact that a wide range of specialists are interested in the issue. Approaches to the diagnosis simplify the search for the etiology of metabolic acidosis. This study presents data on the physiological basis of acid-base balance regulation, and its etiology and pathophysiology; the principles of therapy are observed.
Delay differential systems for tick population dynamics.
Fan, Guihong; Thieme, Horst R; Zhu, Huaiping
2015-11-01
Ticks play a critical role as vectors in the transmission and spread of Lyme disease, an emerging infectious disease which can cause severe illness in humans or animals. To understand the transmission dynamics of Lyme disease and other tick-borne diseases, it is necessary to investigate the population dynamics of ticks. Here, we formulate a system of delay differential equations which models the stage structure of the tick population. Temperature can alter the length of time delays in each developmental stage, and so the time delays can vary geographically (and seasonally which we do not consider). We define the basic reproduction number [Formula: see text] of stage structured tick populations. The tick population is uniformly persistent if [Formula: see text] and dies out if [Formula: see text]. We present sufficient conditions under which the unique positive equilibrium point is globally asymptotically stable. In general, the positive equilibrium can be unstable and the system show oscillatory behavior. These oscillations are primarily due to negative feedback within the tick system, but can be enhanced by the time delays of the different developmental stages.
Lactic acidosis and status asthmaticus: how common in pediatrics?
Yousef, Ejaz; McGeady, Stephen J
2002-12-01
Lactic acidosis is a well described phenomenon in adult patients with severe asthma. However, this entity is rarely reported in children with status asthmaticus. To report our experience in a 13-year-old girl who developed lactic acidosis as a complication of status asthmaticus and to investigate the prevalence of this complication of severe asthma. We sought to determine the frequency of lactic acidosis in such patients and to review etiologies of lactic acidosis. 1) Observations on the clinical and laboratory findings in an adolescent girl with status asthmaticus who developed lactic acidosis were recorded. 2) The medical records of 100 children and adolescents with status asthmaticus admitted to an intensive care unit were reviewed for laboratory evidence of lactic acidosis. 3) We also reviewed our own previous experience of status asthmaticus with respiratory failure. Among 100 patients admitted to a pediatric intensive care unit for status asthmaticus, a single case of isolated metabolic acidosis was identified. This proved to be attributable to lactic acidosis. When records of patients with severe respiratory failure were examined, no cases of metabolic acidosis were found. Although rare, lactic acidosis does occur in pediatric-aged patients during status asthmaticus. It is important that this complication be recognized and treated because acidosis may inhibit the effectiveness of bronchodilator therapy, produce electrolyte disturbances, and cause serious adverse effects on the patient's cardiovascular system.
Kimia, Amir A; Johnston, Patrick; Capraro, Andrew; Harper, Marvin B
2010-10-01
We hypothesize that the occurrence of metabolic acidosis correlates with the cumulative rate of gastrointestinal (GI) illness and that incorporating acidosis surveillance would improve models used for the early detection of outbreaks of GI disease. We conducted a retrospective cohort study of consecutive patients seen in an urban pediatric tertiary care center from September 1995 to August 2005. All data were analyzed for correlation between acidosis and GI syndrome and for internal periodicities. Four years of data were used to create a model, and the first 100 days of 2004 were used for forecasting. Data collected included visit date, chief complaint (CC), International Classification of Diseases, 9th Revision, diagnoses (Dx), and limited laboratory data. Gastrointestinal syndrome was defined by either CC or Dx. Acidosis was defined as HCO₃ levels 19 mmol/dL or less. Exclusion criteria included hyperglycemia (glucose level >120 mg/dL), glycusoria, or having a test for glycosylated hemoglobin ordered. A simple regression model was used to measure correlation between rates of acidosis and GI_Dx and GI_CC. For acidosis and GI syndrome, we fitted a time series model to the daily data with an auto-regressive integrated moving average (1,1) error term. During the study period, there were 505,028 emergency department visits. The median age was 5.1 years (interquartile range, 1.6-11.8 years), and 46% of patients were females. Of these, 132,142 had GI_Dx and 136,304 had GI_CC. Blood chemistries were obtained from 91,052 patients (18.1%). Acidosis was detected in 32.4% of patients who had these laboratory tests sent.Periodicities were detected for GI_Dx, GI_CC, acidosis rates affected by day of the week, and seasonality, with no changes in incidence during the years of our study. Acidosis rates highly correlated with rates of GI syndrome on a daily basis (Pearson correlation coefficient, r = 0.66 for GI_Dx and r = 0.68 for GI_CC, P metabolic acidosis has a 42.2% positive
Earth system commitments due to delayed mitigation
International Nuclear Information System (INIS)
Pfister, Patrik L; Stocker, Thomas F
2016-01-01
As long as global CO 2 emissions continue to increase annually, long-term committed Earth system changes grow much faster than current observations. A novel metric linking this future growth to policy decisions today is the mitigation delay sensitivity (MDS), but MDS estimates for Earth system variables other than peak temperature (ΔT max ) are missing. Using an Earth System Model of Intermediate Complexity, we show that the current emission increase rate causes a ΔT max increase roughly 3–7.5 times as fast as observed warming, and a millenial steric sea level rise (SSLR) 7–25 times as fast as observed SSLR, depending on the achievable rate of emission reductions after the peak of emissions. These ranges are only slightly affected by the uncertainty range in equilibrium climate sensitivity, which is included in the above values. The extent of ocean acidification at the end of the century is also strongly dependent on the starting time and rate of emission reductions. The preservable surface ocean area with sufficient aragonite supersaturation for coral reef growth is diminished globally at an MDS of roughly 25%–80% per decade. A near-complete loss of this area becomes unavoidable if mitigation is delayed for a few years to decades. Also with respect to aragonite, 12%–18% of the Southern Ocean surface become undersaturated per decade, if emission reductions are delayed beyond 2015–2040. We conclude that the consequences of delaying global emission reductions are much better captured if the MDS of relevant Earth system variables is communicated in addition to current trends and total projected future changes. (letter)
Earth system commitments due to delayed mitigation
Pfister, Patrik L.; Stocker, Thomas F.
2016-01-01
As long as global CO2 emissions continue to increase annually, long-term committed Earth system changes grow much faster than current observations. A novel metric linking this future growth to policy decisions today is the mitigation delay sensitivity (MDS), but MDS estimates for Earth system variables other than peak temperature (ΔT max) are missing. Using an Earth System Model of Intermediate Complexity, we show that the current emission increase rate causes a ΔT max increase roughly 3-7.5 times as fast as observed warming, and a millenial steric sea level rise (SSLR) 7-25 times as fast as observed SSLR, depending on the achievable rate of emission reductions after the peak of emissions. These ranges are only slightly affected by the uncertainty range in equilibrium climate sensitivity, which is included in the above values. The extent of ocean acidification at the end of the century is also strongly dependent on the starting time and rate of emission reductions. The preservable surface ocean area with sufficient aragonite supersaturation for coral reef growth is diminished globally at an MDS of roughly 25%-80% per decade. A near-complete loss of this area becomes unavoidable if mitigation is delayed for a few years to decades. Also with respect to aragonite, 12%-18% of the Southern Ocean surface become undersaturated per decade, if emission reductions are delayed beyond 2015-2040. We conclude that the consequences of delaying global emission reductions are much better captured if the MDS of relevant Earth system variables is communicated in addition to current trends and total projected future changes.
Proximal renal tubular acidosis
... glands that produce tears and saliva are destroyed Wilson disease , an inherited disorder in which there is too much copper in the body's tissues Vitamin D deficiency Symptoms Symptoms of proximal renal tubular acidosis include any ...
Santos, Fernando; Gil-Peña, Helena; Alvarez-Alvarez, Silvia
2017-04-01
To facilitate the understanding and knowledge of renal tubular acidosis by providing a summarized information on the known clinical and biochemical characteristics of this group of diseases, by updating the genetic and molecular bases of the primary forms renal tubular acidosis and by examining some issues regarding the diagnosis of distal renal tubular acidosis (RTA) in the daily clinical practice. The manuscript presents recent findings on the potential of next-generation sequencing to disclose new pathogenic variants in patients with a clinical diagnosis of primary RTA and negative Sanger sequencing of known genes. The current review emphasizes the importance of measuring urinary ammonium for a correct clinical approach to the patients with metabolic acidosis and discusses the diagnosis of incomplete distal RTA. We briefly update the current information on RTA, put forward the need of additional studies in children to validate urinary indexes used in the diagnosis of RTA and offer a perspective on diagnostic genetic tests.
Differential games in economic systems with delays
Kim, A. V.; Kormyshev, V. M.; Novikov, M. Yu.; Nikonov, M. A.
2017-11-01
In the paper, we consider application of i-smooth analysis (A.V. Kim, 2015) to differential games with delays in economics (Dockner E.J., et all, 2000; R. Isaacs, 1999). The approach is developed in the framework of the theory of positional differential games (N.N. Krasovskii, A.I. Subbotin, 1988; A.V. Kryazhimskii, Yu.S. Osipov, 1973; Yu.S. Osipov, J. Appl. Math. Mech. Vol. 35, № 1, № 6, 1971) and is based on application of the extremal shift strategy. We consider basic notions and constructions of the approach-evasion problem for linear systems with delays. The necessary and sufficient conditions of solvability the approach-evasion problem in terms of special u-stable sets are presented in another paper.
Dynamics of delayed piecewise linear systems
Directory of Open Access Journals (Sweden)
Laszlo E. Kollar
2003-02-01
Full Text Available In this paper the dynamics of the controlled pendulum is investigated assuming backlash and time delays. The upper equilibrium of the pendulum is stabilized by a piecewise constant control force which is the linear combination of the sampled values of the angle and the angular velocity of the pendulum. The control force is provided by a motor which drives one of the wheels of the cart through an elastic teeth belt. The contact between the teeth of the gear (rigid and the belt (elastic introduces a nonlinearity known as ``backlash" and causes the oscillation of the controlled pendulum around its upper equilibrium. The processing and sampling delays in the determination of the control force tend to destabilize the controlled system as well. We obtain conditions guaranteeing that the pendulum remains in the neighborhood of the upper equilibrium. Experimental findings obtained on a computer controlled inverted pendulum cart structure are also presented showing good agreement with the simulation results.
DELAYED EFFECTS OF RADIATION ON THE HUMAN CENTRAL NERVOUS SYSTEM. EARLY AND LATE DELAYED REACTIONS,
Two cases of delayed effects of radiation on the central nervous system of man are reported. One demonstrates the rare early delayed reaction which...involvement. This patient is an extreme example of the well-documented late delayed effects of radiation and is presented for contrast with the patient in
Acidosis slows electrical conduction through the atrio-ventricular node
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Ashley Muir Nisbet
2014-06-01
Full Text Available Acidosis affects the mechanical and electrical activity of mammalian hearts but comparatively little is known about its effects on the function of the atrio-ventricular node (AVN. In this study, the electrical activity of the epicardial surface of the left ventricle of isolated Langendorff-perfused rabbit hearts was examined using optical methods. Perfusion with hypercapnic Tyrode’s solution (20% CO2, pH 6.7 increased the time of earliest activation (Tact from 100.5+7.9 to 166.1+7.2ms (n=8 at a pacing cycle length (PCL of 300ms (37oC. Tact increased at shorter PCL, and the hypercapnic solution prolonged Tact further: at 150ms PCL, Tact was prolonged from 131.0+5.2 to 174.9+16.3ms. 2:1 AVN block was common at shorter cycle lengths. Atrial and ventricular conduction times were not significantly affected by the hypercapnic solution suggesting that the increased delay originated in the AVN. Isolated right atrial preparations were superfused with Tyrode’s solutions at pH 7.4 (control, 6.8 and 6.3. Low pH prolonged the atrial-Hisian (AH interval, the effective and functional refractory periods and Wenckebach cycle length significantly. Complete AVN block occurred in 6 out of 9 preparations. Optical imaging of conduction at the AV junction revealed increased conduction delay in the region of the AVN, with less marked effects in atrial and ventricular tissue. Thus acidosis can dramatically prolong the AVN delay, and in combination with short cycle lengths, this can cause partial or complete AVN block and is therefore implicated in the development of brady-arrhythmias in conditions of local or systemic acidosis.
Acidosis slows electrical conduction through the atrio-ventricular node.
Nisbet, Ashley M; Burton, Francis L; Walker, Nicola L; Craig, Margaret A; Cheng, Hongwei; Hancox, Jules C; Orchard, Clive H; Smith, Godfrey L
2014-01-01
Acidosis affects the mechanical and electrical activity of mammalian hearts but comparatively little is known about its effects on the function of the atrio-ventricular node (AVN). In this study, the electrical activity of the epicardial surface of the left ventricle of isolated Langendorff-perfused rabbit hearts was examined using optical methods. Perfusion with hypercapnic Tyrode's solution (20% CO2, pH 6.7) increased the time of earliest activation (Tact) from 100.5 ± 7.9 to 166.1 ± 7.2 ms (n = 8) at a pacing cycle length (PCL) of 300 ms (37°C). Tact increased at shorter PCL, and the hypercapnic solution prolonged Tact further: at 150 ms PCL, Tact was prolonged from 131.0 ± 5.2 to 174.9 ± 16.3 ms. 2:1 AVN block was common at shorter cycle lengths. Atrial and ventricular conduction times were not significantly affected by the hypercapnic solution suggesting that the increased delay originated in the AVN. Isolated right atrial preparations were superfused with Tyrode's solutions at pH 7.4 (control), 6.8 and 6.3. Low pH prolonged the atrial-Hisian (AH) interval, the AVN effective and functional refractory periods and Wenckebach cycle length significantly. Complete AVN block occurred in 6 out of 9 preparations. Optical imaging of conduction at the AV junction revealed increased conduction delay in the region of the AVN, with less marked effects in atrial and ventricular tissue. Thus acidosis can dramatically prolong the AVN delay, and in combination with short cycle lengths, this can cause partial or complete AVN block and is therefore implicated in the development of brady-arrhythmias in conditions of local or systemic acidosis.
Virtual unit delay for digital frequency adaptive T/4 delay phase-locked loop system
DEFF Research Database (Denmark)
Yang, Yongheng; Zhou, Keliang; Blaabjerg, Frede
2016-01-01
/processor with a fixed sampling rate considering the cost and complexity, where the number of unit delays that have been adopted should be an integer. For instance, in conventional digital control systems, a single-phase T/4 Delay Phase-Locked Loop (PLL) system takes 50 unit delays (i.e., in a 50-Hz system...... Delay PLL system should be done in its implementation. This process will result in performance degradation in the digital control system, as the exactly required number of delays is not realized. Hence, in this paper, a Virtual Unit Delay (VUD) has been proposed to address such challenges to the digital......Digital micro-controllers/processors enable the cost-effective control of grid-connected power converter systems in terms of system monitoring, signal processing (e.g., grid synchronization), control (e.g., grid current and voltage control), etc. Normally, the control is implemented in a micro-controller...
Euclidean null controllability of nonlinear infinite delay systems with ...
African Journals Online (AJOL)
Sufficient conditions for the Euclidean null controllability of non-linear delay systems with time varying multiple delays in the control and implicit derivative are derived. If the uncontrolled system is uniformly asymptotically stable and if the control system is controllable, then the non-linear infinite delay system is Euclidean null ...
Chaos synchronization in time-delayed systems with parameter mismatches and variable delay times
International Nuclear Information System (INIS)
Shahverdiev, E.M.; Nuriev, R.A.; Hashimov, R.H.; Shore, K.A.
2004-06-01
We investigate synchronization between two undirectionally linearly coupled chaotic nonidentical time-delayed systems and show that parameter mismatches are of crucial importance to achieve synchronization. We establish that independent of the relation between the delay time in the coupled systems and the coupling delay time, only retarded synchronization with the coupling delay time is obtained. We show that with parameter mismatch or without it neither complete nor anticipating synchronization occurs. We derive existence and stability conditions for the retarded synchronization manifold. We demonstrate our approach using examples of the Ikeda and Mackey Glass models. Also for the first time we investigate chaos synchronization in time-delayed systems with variable delay time and find both existence and sufficient stability conditions for the retarded synchronization manifold with the coupling-delay lag time. (author)
Simplified Stability Criteria for Delayed Neutral Systems
Directory of Open Access Journals (Sweden)
Xinghua Zhang
2014-01-01
Full Text Available For a class of linear time-invariant neutral systems with neutral and discrete constant delays, several existing asymptotic stability criteria in the form of linear matrix inequalities (LMIs are simplified by using matrix analysis techniques. Compared with the original stability criteria, the simplified ones include fewer LMI variables, which can obviously reduce computational complexity. Simultaneously, it is theoretically shown that the simplified stability criteria and original ones are equivalent; that is, they have the same conservativeness. Finally, a numerical example is employed to verify the theoretic results investigated in this paper.
Patient delays and system delays in breast cancer treatment in developed and developing countries
Directory of Open Access Journals (Sweden)
Angela Gabrielly Quirino Freitas
2015-10-01
Full Text Available AbstractDelays in treating breast cancer have been associated with a more advanced stage of the disease and a decrease in patient survival rates. The scope of this integrative review was to analyze the main causal factors and types of patient and system delays. The underlying causal factors of delays were compared among studies conducted in developing and developed countries. Of the 53 studies selected, 24 were carried out in developing countries and 29 in developed countries, respectively. Non-attribution of symptoms to cancer, fear of the disease and treatment and low educational level were the most frequent causes of patient delay. Less comprehensive health insurance coverage, older/younger age and false negative diagnosis tests were the three most common causal factors of system delay. The effects of factors such as age were not decisive per se and depended mainly on the social and cultural context. Some factors caused both patient delay and system delay. Studies conducted in developing countries identified more causal factors of patient delay and had a stronger focus on patient delay or the combination of both. Studies conducted in developed countries had a stronger focus on aspects of system delay during treatment and guidance of breast cancer patients in the health care system.
Modeling of Random Delays in Networked Control Systems
Directory of Open Access Journals (Sweden)
Yuan Ge
2013-01-01
Full Text Available In networked control systems (NCSs, the presence of communication networks in control loops causes many imperfections such as random delays, packet losses, multipacket transmission, and packet disordering. In fact, random delays are usually the most important problems and challenges in NCSs because, to some extent, other problems are often caused by random delays. In order to compensate for random delays which may lead to performance degradation and instability of NCSs, it is necessary to establish the mathematical model of random delays before compensation. In this paper, four major delay models are surveyed including constant delay model, mutually independent stochastic delay model, Markov chain model, and hidden Markov model. In each delay model, some promising compensation methods of delays are also addressed.
Optimal Kalman Filtering for a Class of State Delay Systems with Randomly Multiple Sensor Delays
Directory of Open Access Journals (Sweden)
Dongyan Chen
2014-01-01
Full Text Available The optimal Kalman filtering problem is investigated for a class of discrete state delay stochastic systems with randomly multiple sensor delays. The phenomenon of measurement delay occurs in a random way and the delay rate for each sensor is described by a Bernoulli distributed random variable with known conditional probability. Based on the innovative analysis approach and recursive projection formula, a new linear optimal filter is designed such that, for the state delay and randomly multiple sensor delays with different delay rates, the filtering error is minimized in the sense of mean square and the filter gain is designed by solving the recursive matrix equation. Finally, a simulation example is given to illustrate the feasibility and effectiveness of the proposed filtering scheme.
Lag synchronization of chaotic systems with time-delayed linear ...
Indian Academy of Sciences (India)
In this paper, the lag synchronization of chaotic systems with time-delayed linear terms via impulsive control is investigated. Based on the stability theory of impulsive delayed differential equations, some sufficient conditions are obtained guaranteeing the synchronized behaviours between two delayed chaotic systems.
Lag synchronization of chaotic systems with time-delayed linear
Indian Academy of Sciences (India)
In this paper, the lag synchronization of chaotic systems with time-delayed linear terms via impulsive control is investigated. Based on the stability theory of impulsive delayed differential equations, some sufficient conditions are obtained guaranteeing the synchronized behaviours between two delayed chaotic systems.
Acidosis and Urinary Calcium Excretion
DEFF Research Database (Denmark)
Alexander, R Todd; Cordat, Emmanuelle; Chambrey, Régine
2016-01-01
Metabolic acidosis is associated with increased urinary calcium excretion and related sequelae, including nephrocalcinosis and nephrolithiasis. The increased urinary calcium excretion induced by metabolic acidosis predominantly results from increased mobilization of calcium out of bone...... in the renal tubule and then discuss why not all gene defects that cause renal tubular acidosis are associated with hypercalciuria and nephrocalcinosis....
On control of systems delays in economics
Kim, A. V.; Kormyshev, V. M.; Novikov, M. Yu.; Nikonov, M. A.
2017-11-01
The paper continues presentation of the differential game theory for systems with delays and is devoted to the solution of an approach problem in application to economic problems (Dockner E.J., et all, 2000; R. Isaacs, 1999). The results are obtained in the framework of the positional differential game theory (N.N. Krasovskii, A.I. Subbotin, 1988; A.V. Kryazhimskii, Yu.S. Osipov, 1973; Yu.S. Osipov, J. Appl. Math. Mech. Vol. 35, № 1, № 6, 1971) with application of the i-smooth analysis methodology (A.V. Kim, 2015). Effective construction of extremal positional control is based on the utilization of the so called u-stable sets The necessary and sufficient conditions of high u-stability are presented in the paper.
Relation between delayed feedback and delay-coupled systems and its application to chaotic lasers
Energy Technology Data Exchange (ETDEWEB)
Soriano, Miguel C., E-mail: miguel@ifisc.uib-csic.es; Flunkert, Valentin; Fischer, Ingo [Instituto de Física Interdisciplinar y Sistemas Complejos, IFISC (CSIC-UIB), Campus Universitat Illes Balears, E-07122 Palma de Mallorca (Spain)
2013-12-15
We present a systematic approach to identify the similarities and differences between a chaotic system with delayed feedback and two mutually delay-coupled systems. We consider the general case in which the coupled systems are either unsynchronized or in a generally synchronized state, in contrast to the mostly studied case of identical synchronization. We construct a new time-series for each of the two coupling schemes, respectively, and present analytic evidence and numerical confirmation that these two constructed time-series are statistically equivalent. From the construction, it then follows that the distribution of time-series segments that are small compared to the overall delay in the system is independent of the value of the delay and of the coupling scheme. By focusing on numerical simulations of delay-coupled chaotic lasers, we present a practical example of our findings.
Statin precipitated lactic acidosis?
Neale, R; Reynolds, T M; Saweirs, W
2004-09-01
An 82 year old woman was admitted with worsening dyspnoea. Arterial blood gases were taken on air and revealed a pH of 7.39, with a partial pressure of CO2 (pCO2) of 1.2 kPa, pO2 of 19.3 kPa, HCO3 of 13.8 mmol/litre, and base excess of -16.3 mmol/litre: a compensated metabolic acidosis with hyperventilation induced hypocapnia, which is known to be a feature of lactic acidosis. There was also an increased anion gap ((Na140 + K4.0) - (Cl 106 + HCO3 13.8) = 24.2 mEq/litre (reference range, 7-16)), consistent with unmeasured cation. Lactate was measured and found to be raised at 3.33 mmol/litre (reference range, 0.9-1.7). After exclusion of common causes of lactic acidosis Atorvastatin was stopped and her acid-base balance returned to normal. Subsequently, thiamine was also shown to be deficient. The acidosis was thought to have been the result of a mitochondrial defect caused by a deficiency of two cofactors, namely: ubiquinone (as a result of inhibition by statin) and thiamine (as a result of dietary deficiency).
Adaptive control of chaotic continuous-time systems with delay
Tian, Yu-Chu; Gao, Furong
1998-06-01
A simple delay system governed by a first-order differential-delay equation may behave chaotically, but the conditions for the system to have such behaviors have not been well recognized. In this paper, a set of rules is postulated first for the conditions for the delay system to display chaos. A model-reference adaptive control scheme is then proposed to control the chaotic system state to converge to an arbitrarily given reference trajectory with certain and uncertain system parameters. Numerical examples are given to analyze the chaotic behaviors of the delay system and to demonstrate the effectiveness of the proposed adaptive control scheme.
Delays in the operating room: signs of an imperfect system.
Wong, Janice; Khu, Kathleen Joy; Kaderali, Zul; Bernstein, Mark
2010-06-01
Delays in the operating room have a negative effect on its efficiency and the working environment. In this prospective study, we analyzed data on perioperative system delays. One neurosurgeon prospectively recorded all errors, including perioperative delays, for consecutive patients undergoing elective procedures from May 2000 to February 2009. We analyzed the prevalence, causes and impact of perioperative system delays that occurred in one neurosurgeon's practice. A total of 1531 elective surgical cases were performed during the study period. Delays were the most common type of error (33.6%), and more than half (51.4%) of all cases had at least 1 delay. The most common cause of delay was equipment failure. The first cases of the day and cranial cases had more delays than subsequent cases and spinal cases, respectively. A delay in starting the first case was associated with subsequent delays. Delays frequently occur in the operating room and have a major effect on patient flow and resource utilization. Thorough documentation of perioperative delays provides a basis for the development of solutions for improving operating room efficiency and illustrates the principles underlying the causes of operating room delays across surgical disciplines.
Stability analysis of linear switching systems with time delays
International Nuclear Information System (INIS)
Li Ping; Zhong Shouming; Cui Jinzhong
2009-01-01
The issue of stability analysis of linear switching system with discrete and distributed time delays is studied in this paper. An appropriate switching rule is applied to guarantee the stability of the whole switching system. Our results use a Riccati-type Lyapunov functional under a condition on the time delay. So, switching systems with mixed delays are developed. A numerical example is given to illustrate the effectiveness of our results.
Time delay systems theory, numerics, applications, and experiments
Ersal, Tulga; Orosz, Gábor
2017-01-01
This volume collects contributions related to selected presentations from the 12th IFAC Workshop on Time Delay Systems, Ann Arbor, June 28-30, 2015. The included papers present novel techniques and new results of delayed dynamical systems. The topical spectrum covers control theory, numerical analysis, engineering and biological applications as well as experiments and case studies. The target audience primarily comprises research experts in the field of time delay systems, but the book may also be beneficial for graduate students alike. .
Time-Delay System Identification Using Genetic Algorithm
DEFF Research Database (Denmark)
Yang, Zhenyu; Seested, Glen Thane
2013-01-01
Due to the unknown dead-time coefficient, the time-delay system identification turns to be a non-convex optimization problem. This paper investigates the identification of a simple time-delay system, named First-Order-Plus-Dead-Time (FOPDT), by using the Genetic Algorithm (GA) technique. The qual......Due to the unknown dead-time coefficient, the time-delay system identification turns to be a non-convex optimization problem. This paper investigates the identification of a simple time-delay system, named First-Order-Plus-Dead-Time (FOPDT), by using the Genetic Algorithm (GA) technique...
Severe metabolic acidosis following assault chemical burn
Roock, Sophie D; Deleuze, Jean-Paul; Rose, Thomas; Jennes, Serge; Hantson, Philippe
2012-01-01
Assault chemical burns are uncommon in northern Europe. Besides local toxicity, systemic manifestations are possible after strong acid exposure. A 40-year-old woman was admitted 1 h after a criminal assault with sulfuric acid. The total burned surface area was 35%, third degree. Injury was due to sulfuric acid (measured pH 0.9) obtained from a car battery. Immediate complications were obstructive dyspnea and metabolic acidosis. The admission arterial pH was 6.92, with total bicarbonate 8.6 mEq/l and base deficit 23.4 mEq/l. The correction of metabolic acidosis was achieved after several hours by the administration of bicarbonate and lactate buffers. The patient developed several burns-related complications (sepsis and acute renal failure). Cutaneous projections of strong acids may cause severe metabolic acidosis, particularly when copious irrigation and clothes removal cannot be immediately performed at the scene. PMID:22787349
Severe metabolic acidosis following assault chemical burn
Directory of Open Access Journals (Sweden)
Sophie De Roock
2012-01-01
Full Text Available Assault chemical burns are uncommon in northern Europe. Besides local toxicity, systemic manifestations are possible after strong acid exposure. A 40-year-old woman was admitted 1 h after a criminal assault with sulfuric acid. The total burned surface area was 35%, third degree. Injury was due to sulfuric acid (measured pH 0.9 obtained from a car battery. Immediate complications were obstructive dyspnea and metabolic acidosis. The admission arterial pH was 6.92, with total bicarbonate 8.6 mEq/l and base deficit 23.4 mEq/l. The correction of metabolic acidosis was achieved after several hours by the administration of bicarbonate and lactate buffers. The patient developed several burns-related complications (sepsis and acute renal failure. Cutaneous projections of strong acids may cause severe metabolic acidosis, particularly when copious irrigation and clothes removal cannot be immediately performed at the scene.
Control of District Heating System with Flow-dependent Delays
DEFF Research Database (Denmark)
Bendtsen, Jan Dimon; Ledesma, Jorge Val; Kallesøe, Carsten Skovmose
2017-01-01
All flow systems are subject to transport delays, which are governed by the flow rates in the system. When the flow rates themselves are control inputs, the system becomes subject to input-dependent state delays, which poses significant theoretical problems. In an earlier paper, we proposed...
Asymptotic Stability Results of Solutions of Neutral Delay Systems ...
African Journals Online (AJOL)
In this paper, a retarded delay system is transformed to a class of neutral delay system using the differentiability condition of the functional on the Banach space. The Leibnez-Newton formula and symmetric properties of some chosen matrices are utilized to formulate a Lyapunov functional of the transformed system, which ...
Owens, F N; Secrist, D S; Hill, W J; Gill, D R
1998-01-01
Acute and chronic acidosis, conditions that follow ingestion of excessive amounts of readily fermented carbohydrate, are prominent production problems for ruminants fed diets rich in concentrate. Often occurring during adaptation to concentrate-rich diets in feedyards, chronic acidosis may continue during the feeding period. With acute acidosis, ruminal acidity and osmolality increase markedly as acids and glucose accumulate; these can damage the ruminal and intestinal wall, decrease blood pH, and cause dehydration that proves fatal. Laminitis, polioencephalomalacia, and liver abscesses often accompany acidosis. Even after animals recover from a bout of acidosis, nutrient absorption may be retarded. With chronic acidosis, feed intake typically is reduced but variable, and performance is depressed, probably due to hypertonicity of digesta. Acidosis control measures include feed additives that inhibit microbial strains that produce lactate, that stimulate activity of lactate-using bacteria or starch-engulfing ruminal protozoa, and that reduce meal size. Inoculation with microbial strains capable of preventing glucose or lactate accumulation or metabolizing lactate at a low pH should help prevent acidosis. Feeding higher amounts of dietary roughage, processing grains less thoroughly, and limiting the quantity of feed should reduce the incidence of acidosis, but these practices often depress performance and economic efficiency. Continued research concerning grain processing, dietary cation-anion balance, narrow-spectrum antibiotics, glucose or lactate utilizing microbes, and feeding management (limit or program feeding) should yield new methods for reducing the incidence of acute and chronic acidosis.
New stability conditions for nonlinear time varying delay systems
Elmadssia, S.; Saadaoui, K.; Benrejeb, M.
2016-07-01
In this paper, new practical stability conditions for a class of nonlinear time varying delay systems are proposed. The study is based on the use of a specific state space description, known as the Benrejeb characteristic arrow form matrix, and aggregation techniques to obtain delay-dependent stability conditions. Application of this method to delayed Lurie-Postnikov nonlinear systems is given. Illustrative examples are presented to show the effectiveness of the proposed approach.
Robust filtering and fault detection of switched delay systems
Wang, Dong; Wang, Wei
2013-01-01
Switched delay systems appear in a wide field of applications including networked control systems, power systems, memristive systems. Though the large amount of ideas with respect to such systems have generated, until now, it still lacks a framework to focus on filter design and fault detection issues which are relevant to life safety and property loss. Beginning with the comprehensive coverage of the new developments in the analysis and control synthesis for switched delay systems, the monograph not only provides a systematic approach to designing the filter and detecting the fault of switched delay systems, but it also covers the model reduction issues. Specific topics covered include: (1) Arbitrary switching signal where delay-independent and delay-dependent conditions are presented by proposing a linearization technique. (2) Average dwell time where a weighted Lyapunov function is come up with dealing with filter design and fault detection issues beside taking model reduction problems. The monograph is in...
Relative null controllability of linear systems with multiple delays in ...
African Journals Online (AJOL)
varying multiple delays in state and control are developed. If the uncontrolled system is uniformly asymptotically stable, and if the linear system is controllable, then the linear system is null controllable. Journal of the Nigerian Association of ...
Delay or anticipatory synchronization in one-way coupled systems ...
Indian Academy of Sciences (India)
Abstract. We present a mechanism for the synchronization of one-way coupled nonlinear systems in which the coupling uses a variable delay, that is reset at finite intervals. Here the delay varies in the same way as the system in time and so the coupling function remains constant for the reset interval at the end of which it is ...
Exponential Stability of Stochastic Nonlinear Dynamical Price System with Delay
Directory of Open Access Journals (Sweden)
Wenli Zhu
2013-01-01
Full Text Available Based on Lyapunov stability theory, Itô formula, stochastic analysis, and matrix theory, we study the exponential stability of the stochastic nonlinear dynamical price system. Using Taylor's theorem, the stochastic nonlinear system with delay is reduced to an n-dimensional semilinear stochastic differential equation with delay. Some sufficient conditions of exponential stability and corollaries for such price system are established by virtue of Lyapunov function. The time delay upper limit is solved by using our theoretical results when the system is exponentially stable. Our theoretical results show that if the classical price Rayleigh equation is exponentially stable, so is its perturbed system with delay provided that both the time delay and the intensity of perturbations are small enough. Two examples are presented to illustrate our results.
Systemic delay propagation in the US airport network.
Fleurquin, Pablo; Ramasco, José J; Eguiluz, Victor M
2013-01-01
Technologically driven transport systems are characterized by a networked structure connecting operation centers and by a dynamics ruled by pre-established schedules. Schedules impose serious constraints on the timing of the operations, condition the allocation of resources and define a baseline to assess system performance. Here we study the performance of an air transportation system in terms of delays. Technical, operational or meteorological issues affecting some flights give rise to primary delays. When operations continue, such delays can propagate, magnify and eventually involve a significant part of the network. We define metrics able to quantify the level of network congestion and introduce a model that reproduces the delay propagation patterns observed in the U.S. performance data. Our results indicate that there is a non-negligible risk of systemic instability even under normal operating conditions. We also identify passenger and crew connectivity as the most relevant internal factor contributing to delay spreading.
Control of delay dominant systems with costs related to switching
DEFF Research Database (Denmark)
Deng, Honglian; Larsen, Lars Finn Sloth; Stoustrup, Jakob
2010-01-01
The objective of this paper is to extend a novel low complexity method for optimizing switch control developed by the authors earlier to work with delay dominant systems and demonstrate that the method works in practice with a refrigeration test system. The extended method solves switching problems...... for high order systems which can be approximated as a first order with a delay as well. The extension of the method is realized with an observer to retrieve the delay-free information. Experimental validation of the extended method is carried out with a test system. A comparison to a baseline relay...
Exponential Stability of Stochastic Systems with Delay and Poisson Jumps
Directory of Open Access Journals (Sweden)
Wenli Zhu
2014-01-01
Full Text Available This paper focuses on the model of a class of nonlinear stochastic delay systems with Poisson jumps based on Lyapunov stability theory, stochastic analysis, and inequality technique. The existence and uniqueness of the adapted solution to such systems are proved by applying the fixed point theorem. By constructing a Lyapunov function and using Doob’s martingale inequality and Borel-Cantelli lemma, sufficient conditions are given to establish the exponential stability in the mean square of such systems, and we prove that the exponentially stable in the mean square of such systems implies the almost surely exponentially stable. The obtained results show that if stochastic systems is exponentially stable and the time delay is sufficiently small, then the corresponding stochastic delay systems with Poisson jumps will remain exponentially stable, and time delay upper limit is solved by using the obtained results when the system is exponentially stable, and they are more easily verified and applied in practice.
Relative controllability of nonlinear systems with delays in state and ...
African Journals Online (AJOL)
In this work, sufficient conditions are developed for the relative controllability of perturbed nonlinear systems with time varying multiple delays in control with the perturbation function having implicit derivative with delays depending on both state and control variable, using Darbo's fixed points theorem. Journal of the Nigerian ...
Analysis of results from delay studies of isol-systems
International Nuclear Information System (INIS)
Rudstam, G.
1980-01-01
The delay between production and measurement is an important effect in ISOL-experiments aiming at the determination of nuclear reaction yields. The present report discusses methods to correct for decay losses caused by the delay in the target - ion source system of the isotope separator. (author)
Quadratic theory and feedback controllers for linear time delay systems
International Nuclear Information System (INIS)
Lee, E.B.
1976-01-01
Recent research on the design of controllers for systems having time delays is discussed. Results for the ''open loop'' and ''closed loop'' designs will be presented. In both cases results for minimizing a quadratic cost functional are given. The usefulness of these results is not known, but similar results for the non-delay case are being routinely applied. (author)
Directory of Open Access Journals (Sweden)
Sami G. Tantawi
2004-03-01
Full Text Available Pulse compression systems for future linear colliders, such as NLC and JLC, involve hundreds of kilometers of waveguide runs. These waveguides are highly overmoded to reduce the rf losses. In this paper we present a novel idea for utilizing these waveguides several times by using different modes. This idea is suitable for reflective delay lines. All the modes being used have low-loss characteristics. We describe mechanically simple mode transducers that switch the propagation mode from one configuration to another with no observable dispersion. We apply this technique to a resonant delay line pulse compression system. We also present experimental results that verify these theoretical developments.
Fundamental Matrix for a Class of Point Delay Linear Systems
International Nuclear Information System (INIS)
Sen, M. de la; Alastruey, C. F.
1998-01-01
It is difficult to establish explicit analytic forms for fundamental matrices of delayed linear systems. In this paper, an explicit form of exponential type is given for such a matrix in the case of punctual delays. The existence of real and complex fundamental matrices, for the case of real parameterizations of the differential system, is studied and discussed. Some additional commutativity properties involving the matrices parameters and the fundamental matrices as well as explicit expressions for the solution of the delayed differential system are also given. (Author)
Modeling delayed neutron monitoring systems for fast breeder reactors
International Nuclear Information System (INIS)
Bunch, W.L.; Tang, E.L.
1983-10-01
The purpose of the present work was to develop a general expression relating the count rate of a delayed neutron monitoring system to the introduction rate of fission fragments into the sodium coolant of a fast breeder reactor. Most fast breeder reactors include a system for detecting the presence of breached fuel that permits contact between the sodium coolant and the mixed oxide fuel. These systems monitor for the presence of fission fragments in the sodium that emit delayed neutrons. For operational reasons, the goal is to relate the count rate of the delayed neutron monitor to the condition of the breach in order that appropriate action might be taken
Time delays and advances in classical and quantum systems
Kolomeitsev, E. E.; Voskresensky, D. N.
2013-11-01
This article reviews positive and negative time delays in various processes of classical and quantum physics. In the beginning, we demonstrate how a time-shifted response of a system to an external perturbation appears in classical mechanics and classical electrodynamics. Then we quantify durations of various quantum mechanical processes. The duration of the quantum tunneling is studied, and an interpretation of the Hartmann paradox is suggested. Time delays and advances appearing in the three-dimensional scattering problem on a central potential are considered. We then discuss delays and advances appearing in quantum field theory and after that we focus on the issue of time delays and advancements in quantum kinetics. We discuss problems of the application of generalized kinetic equations in simulations of the system relaxation toward equilibrium and analyze the kinetic entropy flow. Possible measurements of time delays and advancements in experiments similar to the recent OPERA neutrino experiment are also discussed.
Periodic Solutions of a System of Delay Differential Equations for a Small Delay
Directory of Open Access Journals (Sweden)
Adu A.M. Wasike
2002-06-01
Full Text Available We prove the existence of an asymptotically stable periodic solution of a system of delay differential equations with a small time delay t > 0. To achieve this, we transform the system of equations into a system of perturbed ordinary differential equations and then use perturbation results to show the existence of an asymptotically stable periodic solution. This approach is contingent on the fact that the system of equations with t = 0 has a stable limit cycle. We also provide a comparative study of the solutions of the original system and the perturbed system. This comparison lays the ground for proving the existence of periodic solutions of the original system by Schauder's fixed point theorem.
Distributed Optimal Consensus Control for Multiagent Systems With Input Delay.
Zhang, Huaipin; Yue, Dong; Zhao, Wei; Hu, Songlin; Dou, Chunxia
2017-06-27
This paper addresses the problem of distributed optimal consensus control for a continuous-time heterogeneous linear multiagent system subject to time varying input delays. First, by discretization and model transformation, the continuous-time input-delayed system is converted into a discrete-time delay-free system. Two delicate performance index functions are defined for these two systems. It is shown that the performance index functions are equivalent and the optimal consensus control problem of the input-delayed system can be cast into that of the delay-free system. Second, by virtue of the Hamilton-Jacobi-Bellman (HJB) equations, an optimal control policy for each agent is designed based on the delay-free system and a novel value iteration algorithm is proposed to learn the solutions to the HJB equations online. The proposed adaptive dynamic programming algorithm is implemented on the basis of a critic-action neural network (NN) structure. Third, it is proved that local consensus errors of the two systems and weight estimation errors of the critic-action NNs are uniformly ultimately bounded while the approximated control policies converge to their target values. Finally, two simulation examples are presented to illustrate the effectiveness of the developed method.
Complex Time-Delay Systems Theory and Applications
Atay, Fatihcan M
2010-01-01
Time delays in dynamical systems arise as an inevitable consequence of finite speeds of information transmission. Realistic models increasingly demand the inclusion of delays in order to properly understand, analyze, design, and control real-life systems. The goal of this book is to present the state-of-the-art in research on time-delay dynamics in the framework of complex systems and networks. While the mathematical theory of delay equations is quite mature, its application to the particular problems of complex systems and complexity is a newly emerging field, and the present volume aims to play a pioneering role in this perspective. The chapters in this volume are authored by renowned experts and cover both theory and applications in a wide range of fields, with examples extending from neuroscience and biology to laser physics and vehicle traffic. Furthermore, all chapters include sufficient introductory material and extensive bibliographies, making the book a self-contained reference for both students and ...
Multiconsensus of Second-Order Multiagent Systems with Input Delays
Directory of Open Access Journals (Sweden)
Jie Chen
2014-01-01
Full Text Available The multiconsensus problem of double-integrator dynamic multiagent systems has been investigated. Firstly, the dynamic multiconsensus, the static multiconsensus, and the periodic multiconsensus are considered as three cases of multiconsensus, respectively, in which the final multiconsensus convergence states are established by using matrix analysis. Secondly, as for the multiagent system with input delays, the maximal allowable upper bound of the delays is obtained by employing Hopf bifurcation of delayed networks theory. Finally, simulation results are presented to verify the theoretical analysis.
Further triple integral approach to mixed-delay-dependent stability of time-delay neutral systems.
Wang, Ting; Li, Tao; Zhang, Guobao; Fei, Shumin
2017-09-01
This paper studies the asymptotic stability for a class of neutral systems with mixed time-varying delays. Through utilizing some Wirtinger-based integral inequalities and extending the convex combination technique, the upper bound on derivative of Lyapunov-Krasovskii (L-K) functional can be estimated more tightly and three mixed-delay-dependent criteria are proposed in terms of linear matrix inequalities (LMIs), in which the nonlinearity and parameter uncertainties are also involved, respectively. Different from those existent works, based on the interconnected relationship between neutral delay and state one, some novel triple integral functional terms are constructed and the conservatism can be effectively reduced. Finally, two numerical examples are given to show the benefits of the proposed criteria. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.
Predictor feedback for delay systems implementations and approximations
Karafyllis, Iasson
2017-01-01
This monograph bridges the gap between the nonlinear predictor as a concept and as a practical tool, presenting a complete theory of the application of predictor feedback to time-invariant, uncertain systems with constant input delays and/or measurement delays. It supplies several methods for generating the necessary real-time solutions to the systems’ nonlinear differential equations, which the authors refer to as approximate predictors. Predictor feedback for linear time-invariant (LTI) systems is presented in Part I to provide a solid foundation on the necessary concepts, as LTI systems pose fewer technical difficulties than nonlinear systems. Part II extends all of the concepts to nonlinear time-invariant systems. Finally, Part III explores extensions of predictor feedback to systems described by integral delay equations and to discrete-time systems. The book’s core is the design of control and observer algorithms with which global stabilization, guaranteed in the previous literature with idealized (b...
Do health systems delay the treatment of poor children?
DEFF Research Database (Denmark)
Samuelsen, Helle; Tersbøl, Britt Pinkowski; Mbuyita, Selemani Said
2013-01-01
Child mortality remains one of the major public-health problems in Tanzania. Delays in receiving and accessing adequate care contribute to these high rates. The literature on public health often focuses on the role of mothers in delaying treatment, suggesting that they contact the health system t......-care facility. The overall objective is to analyse specific structural factors embedded in everyday practices at health facilities in a district in Tanzania which cause delays in the treatment of poor children and to discuss possible changes to institutions and social technologies....
Truncated predictor feedback for time-delay systems
Zhou, Bin
2014-01-01
This book provides a systematic approach to the design of predictor based controllers for (time-varying) linear systems with either (time-varying) input or state delays. Differently from those traditional predictor based controllers, which are infinite-dimensional static feedback laws and may cause difficulties in their practical implementation, this book develops a truncated predictor feedback (TPF) which involves only finite dimensional static state feedback. Features and topics: A novel approach referred to as truncated predictor feedback for the stabilization of (time-varying) time-delay systems in both the continuous-time setting and the discrete-time setting is built systematically Semi-global and global stabilization problems of linear time-delay systems subject to either magnitude saturation or energy constraints are solved in a systematic manner Both stabilization of a single system and consensus of a group of systems (multi-agent systems) are treated in a unified manner by applying the truncated pre...
Stability of neutral type descriptor system with mixed delays
International Nuclear Information System (INIS)
Li Hong; Li Houbiao; Zhong Shouming
2007-01-01
In this paper, the stability problems of general neutral type descriptor system with mixed delays are considered. Some new delay-independent stability and robust stability criteria, which are simpler and less conservative than existing results, are derived in terms of the stability of a new operator I and linear matrix inequalities (LMIs). Therefore, criteria can be easily checked by utilizing the Matlab LMI toolbox
Robotic reactions: delay-induced patterns in autonomous vehicle systems.
Orosz, Gábor; Moehlis, Jeff; Bullo, Francesco
2010-02-01
Fundamental design principles are presented for vehicle systems governed by autonomous cruise control devices. By analyzing the corresponding delay differential equations, it is shown that for any car-following model short-wavelength oscillations can appear due to robotic reaction times, and that there are tradeoffs between the time delay and the control gains. The analytical findings are demonstrated on an optimal velocity model using numerical continuation and numerical simulation.
Robotic reactions: Delay-induced patterns in autonomous vehicle systems
Orosz, Gábor; Moehlis, Jeff; Bullo, Francesco
2010-02-01
Fundamental design principles are presented for vehicle systems governed by autonomous cruise control devices. By analyzing the corresponding delay differential equations, it is shown that for any car-following model short-wavelength oscillations can appear due to robotic reaction times, and that there are tradeoffs between the time delay and the control gains. The analytical findings are demonstrated on an optimal velocity model using numerical continuation and numerical simulation.
Euclidean null controllability of perturbed infinite delay systems with ...
African Journals Online (AJOL)
Sufficient conditions for the Euclidean null controllability of perturbed infinite delay systems with limited control are developed. The results are established by placing conditions on the perturbation function which guarantee that, if the linear control base system is completely Euclidean controllable, then the perturbed system ...
Euclidean null controllability of linear systems with delays in state ...
African Journals Online (AJOL)
Sufficient conditions are developed for the Euclidean controllability of linear systems with delay in state and in control. Namely, if the uncontrolled system is uniformly asymptotically stable and the control equation proper, then the control system is Euclidean null controllable. Journal of the Nigerian Association of ...
Absolute Stability of Discrete-Time Systems with Delay
Directory of Open Access Journals (Sweden)
Medina Rigoberto
2008-01-01
Full Text Available We investigate the stability of nonlinear nonautonomous discrete-time systems with delaying arguments, whose linear part has slowly varying coefficients, and the nonlinear part has linear majorants. Based on the "freezing" technique to discrete-time systems, we derive explicit conditions for the absolute stability of the zero solution of such systems.
Stochastic systems with delay: Perturbation theory for second order statistics
Energy Technology Data Exchange (ETDEWEB)
Frank, T.D., E-mail: till.frank@uconn.edu
2016-03-24
Within the framework of delay Fokker–Planck equations, a perturbation theoretical method is developed to determine second-order statistical quantities such as autocorrelation functions for stochastic systems with delay. Two variants of the perturbation theoretical approach are presented. The first variant is based on a non-local Fokker–Planck operator. The second variant requires to solve a Fokker–Planck equation with source term. It is shown that the two variants yield consistent results. The perturbation theoretical approaches are applied to study negative autocorrelations that are induced by feedback delays and mediated by the strength of the fluctuating forces that act on the feedback systems. - Highlights: • A perturbation theory for stochastic delay systems is presented. • The perturbation theory yields second order statistical quantities. • The theory is developed within the framework of delay Fokker–Planck equations. • The effective Fokker–Planck operator is a non-local operator in space. • Negative autocorrelations can be induced by time-delayed feedback.
Willis, Monte S; Cairns, Bruce A; Purdy, Ashley; Bortsov, Andrey V; Jones, Samuel W; Ortiz-Pujols, Shiara M; Willis, Tina M Schade; Joyner, Benny L
2013-01-01
A 3-year old male who sustained 2(nd) and 3(rd) degree burns that covered approximately 60% TBSA presented to a large adult and pediatric verified burn center. On hospital day (HD) 26 of his stay, Candida fungemia was identified by blood culture, delaying operative management until HD 47. On HD 47, after his first operative intervention, the patient developed a persistent metabolic and lactic acidosis. On HD 66, a search for a cause of his osmol gap of 56 mOsm/kg revealed a potential source-propylene glycol. Previous studies have implicated the propylene glycol emulsifier in the silver sulfadiazine that was being applied to his skin as a rare cause of lactic acidosis in severely burned patients. Within 24 hours of stopping the silver sulfadiazine therapy, his lactic acidosis and osmol gap resolved; within 72 hours his metabolic acidosis resolved. Silver sulfadiazine is commonly used adjunct therapy in the treatment of 2(nd) and 3(rd) degree burns and generally has few adverse reactions. The absorption of propylene glycol systemically can rarely occur when applied to extensive burns, presumably due to the disruption of the skin barrier; the half-life of PG is 10 hours and can be prolonged with renal disease because ~50% of the sulfadiazine is excreted in the urine unchanged. When propylene glycol is present systemically, it is metabolized to lactic acid in the liver, which can cause a lactic acidosis. Several commonly used drugs also use propylene glycol as an emulsifier, including IV preparations of lorazepam, pentobarbital, phenobarbital, and phenytoin. In all of these clinical scenarios, including severe burn patients that are being treated with silver sulfadiazine, both lactic acid and propylene glycol levels should be measured to monitor for this rare, potentially serious co-morbidity.
Acidosis láctica: algunas consideraciones
Directory of Open Access Journals (Sweden)
Maia Heredero Valdés
2000-09-01
Full Text Available La hiperlactacidemia significa clínicamente problemas para los pacientes. La acidosis láctica es un trastorno ácido-básico consecutivo a la acumulación del ácido láctico, el cual se comporta en el nivel celular, como la contrapartida reducida del ácido pirúvico. Este último, resulta de la degradación de la glucosa en el citosol, proceso que se realiza de manera anaoeróbica y que puede culminar en CO2 H2O si sigue la vía del ácido cítrico de Krebs. El diagnóstico de esta entidad se confirma al medir la concentración sanguínea del lactato, aunque existen diversas características clínicas y de laboratorio que dan indicios de la existencia de este trastorno. Las causas de acidosis láctica se dividen en las producidas por hipoxia hística (tipo A y las no producidas por este trastorno (tipo B; dentro de estas últimas se sitúan las debidas a alteraciones sistémicas, al uso de fármacos o toxinas y a las que acompañan a errores innatos del metabolismo.Hyperlactatemia is a clinical problem for patients. The lactic acidosis is an acid-base disorder following the builup of lactic acid which at cellular level hehaves as a reduced counterpart of the pyruvic acid. The latter results from the degradation of glucose into citosol, a process that is anaerobically carried out and may end up in CO2 H2O if it takes the Krebs? citric acid route. The diagnosis sof this entity is confirmed by measuring blood lactate concentration although there are several clinical and lab characteristics that demonstrate the existance of this disorder. The causes of lactic acidosis are divided into those caused by hystic hypoxia (type A and those not caused by this disorder (type B such as lactic acidosis due to systemic disorders, use of drugs or toxins and acidosis resulting from inborn metabolic errors.
Dissipativity Analysis of Linear State/Input Delay Systems
Directory of Open Access Journals (Sweden)
Guifang Cheng
2012-01-01
Full Text Available This paper discusses dissipativity problem for system of linear state/input delay equations. Motivated by dissipativity theory of control systems, we choose a new quadratic supply rate. Using the concept of dissipativity, necessary and sufficient conditions for the linear state/input delay systems to be dissipative and exponentially dissipative are derived. The connection of dissipativity with stability is also considered. Finally, passivity and finite gain are explored, correspondingly. The positive-real and bounded-real lemmas are derived.
Coherence resonance in an excitable system with time delay
International Nuclear Information System (INIS)
Sethia, Gautam C.; Kurths, Juergen; Sen, Abhijit
2007-01-01
We study the noise activated dynamics of a model excitable system that consists of a subcritical Hopf oscillator with a time delayed nonlinear feedback. The coherence of the noise driven pulses of the system exhibits a novel double peaked structure as a function of the noise amplitude. The two peaks correspond to separate optimal noise levels for excitation of single spikes and multiple spikes (bursts) respectively. The relative magnitudes of these peaks are found to be a sensitive function of time delay. The physical significance of our results and its practical implications in various real life systems are discussed
Dynamics of fractional-ordered Chen system with delay
Indian Academy of Sciences (India)
In the present paper the effect of delay on chaos in fractional-order Chen system is investigated. It is observed that ... There has been an explosion of activity in dynamical systems theory in the past two decades. Most activity is ... open new possibilities since the evolution depends on entire history. Fractional differential ...
Stability of time-delay systems via Lyapunov functions
Directory of Open Access Journals (Sweden)
Carlos F. Alastruey
2002-01-01
Full Text Available In this paper, a Lyapunov function candidate is introduced for multivariable systems with inner delays, without assuming a priori stability for the nondelayed subsystem. By using this Lyapunov function, a controller is deduced. Such a controller utilizes an input–output description of the original system, a circumstance that facilitates practical applications of the proposed approach.
Criteria for stability of linear dynamical systems with multiple delays ...
African Journals Online (AJOL)
In this study we considered a linear Dynamical system with multiple delays and find suitable conditions on the systems parameters such that for a given initial function, we can define a mapping in a carefully chosen complete metric space on which the mapping has a unique fixed point. An asymptotic stability theory for the ...
Lag synchronization of chaotic systems with time-delayed linear ...
Indian Academy of Sciences (India)
sive control scheme can reduce the control cost significantly, and so it is of great use in practical applications. Now, in this paper, lag synchronization of chaotic systems with time-delayed linear terms will be investigated. The scheme is showed effective through numerical simulations on chaotic systems. The rest of the paper ...
Delayed Consensus Problem for Single and Double Integrator Systems
Directory of Open Access Journals (Sweden)
Martín Velasco-Villa
2015-01-01
Full Text Available This work deals with the analysis of the consensus problem for networks of agents constituted by single and double integrator systems. It is assumed that the communication among agents is affected by a constant time-delay. Previous and numerous analysis of the problem shows that the maximum communication time-delay that can be introduced to the network without affecting the consensus of the group of the agents depends on the considered topology. In this work, a control scheme that is based on the estimation of future states of the agents and that allows increasing the magnitude of a possible time-delay affecting the communication channels is proposed. How the proposed delay compensation strategy is independent of the network topology in the sense that the maximum allowable time-delay that could be supported by the network depends on a design parameter and not on the maximum eigenvalue of the corresponding Laplacian matrix is shown. It is formally proven that, under the proposed prediction scheme, the consensus of the group can be achieved by improving the maximum time-delay bounds previously reported in the literature. Numerical simulations show the effectiveness of the proposed solution.
Time-Delay Estimation in Dispersed Spectrum Cognitive Radio Systems
Directory of Open Access Journals (Sweden)
Celebi Hasari
2010-01-01
Full Text Available Time-delay estimation is studied for cognitive radio systems, which facilitate opportunistic use of spectral resources. A two-step approach is proposed to obtain accurate time-delay estimates of signals that occupy multiple dispersed bands simultaneously, with significantly lower computational complexity than the optimal maximum likelihood (ML estimator. In the first step of the proposed approach, an ML estimator is used for each band of the signal in order to estimate the unknown parameters of the signal occupying that band. Then, in the second step, the estimates from the first step are combined in various ways in order to obtain the final time-delay estimate. The combining techniques that are used in the second step are called optimal combining, signal-to-noise ratio (SNR combining, selection combining, and equal combining. It is shown that the performance of the optimal combining technique gets very close to the Cramer-Rao lower bound at high SNRs. These combining techniques provide various mechanisms for diversity combining for time-delay estimation and extend the concept of diversity in communications systems to the time-delay estimation problem in cognitive radio systems. Simulation results are presented to evaluate the performance of the proposed estimators and to verify the theoretical analysis.
Hopf bifurcation for tumor-immune competition systems with delay
Directory of Open Access Journals (Sweden)
Ping Bi
2014-01-01
Full Text Available In this article, a immune response system with delay is considered, which consists of two-dimensional nonlinear differential equations. The main purpose of this paper is to explore the Hopf bifurcation of a immune response system with delay. The general formula of the direction, the estimation formula of period and stability of bifurcated periodic solution are also given. Especially, the conditions of the global existence of periodic solutions bifurcating from Hopf bifurcations are given. Numerical simulations are carried out to illustrate the the theoretical analysis and the obtained results.
Low-complexity controllers for time-delay systems
Özbay, Hitay; Bonnet, Catherine; Mounier, Hugues
2014-01-01
This volume in the newly established series Advances in Delays and Dynamics (ADD@S) provides a collection of recent results on the design and analysis of Low Complexity Controllers for Time Delay Systems. A widely used indirect method to obtain low order controllers for time delay systems is to design a controller for the reduced order model of the plant. In the dual indirect approach, an infinite dimensional controller is designed first for the original plant model; then, the controller is approximated by keeping track of the degradation in performance and stability robustness measures. The present volume includes new techniques used at different stages of the indirect approach. It also includes new direct design methods for fixed structure and low order controllers. On the other hand, what is meant by low complexity controller is not necessarily low order controller. For example, Smith predictor or similar type of controllers include a copy of the plant internally in the controller, so they are technically ...
Swing Damping for Helicopter Slung Load Systems using Delayed Feedback
DEFF Research Database (Denmark)
Bisgaard, Morten; la Cour-Harbo, Anders; Bendtsen, Jan Dimon
2009-01-01
of swing. The design of the delayed feedback controller is presented as an optimization problem which gives the possibility of an automated design process. Simulations and flight test verifications of the control system on two different autonomous helicopters are presented and it is shown how a significant......This paper presents the design and verification of a swing reducing controller for helicopter slung load systems using intentional delayed feedback. It is intended for augmenting a trajectory tracking helicopter controller and thereby improving the slung load handing capabilities for autonomous...... helicopters. The delayed feedback controller is added to actively reduce oscillations of the slung load by improving the damping of the slung load pendulum modes. Furthermore, it is intended for integration with a feedforward control scheme based on input shaping for concurrent avoidance and dampening...
The Cricket Cercal System Implements Delay-Line Processing
Mulder-Rosi, Jonas; Cummins, Graham I.
2010-01-01
The cercal sensory system of crickets mediates sensitivity to low-amplitude air currents. The sense organ for this system is a pair of antenna-like abdominal appendages called cerci, each of which is about 1 cm long in normal adult crickets. Although this system has been used extensively as a model system for studying the mechanisms underlying neural coding at the cellular and system levels, no previous studies have considered the functional significance of the physical dimensions of cerci. We show that the differential conduction characteristics of the receptor array in Acheta domesticus crickets are of substantial significance. All filiform sensory afferent axons we examined had the same propagation speeds to within a small variance, resulting in a significant and systematic differential propagation time for spikes from sensory receptors at different locations along the structure. Thus the sensory structures operate as delay lines. The delay-line structure supports neural computations in many of the projecting cercal interneurons (INs) that yield substantial differential sensitivity to the direction and velocity of naturalistic stimuli. Several INs show delay-line-derived sensitivities that are equivalent, in an engineering sense, to “notch filtering,” through which background noise is selectively eliminated by the delay-line-based processing. PMID:20107118
Liu, Lingfeng; Miao, Suoxia; Cheng, Mengfan; Gao, Xiaojing
2016-02-01
A coupled system with varying parameters is proposed to improve the security of optoelectronic delayed feedback system. This system is coupled by two parameter-varied optoelectronic delayed feedback systems with chaotic modulation. Dynamics performance results show that this system has a higher complexity compared to the original one. Furthermore, this system can conceal the time delay effectively against the autocorrelation function and delayed mutual information method and can increase the dimension space of secure parameters to resist brute-force attack by introducing the digital chaotic systems.
Review of the Diagnostic Evaluation of Normal Anion Gap Metabolic Acidosis.
Berend, Kenrick
2017-12-01
Normal anion gap metabolic acidosis is a common but often misdiagnosed clinical condition associated with diarrhea and renal tubular acidosis (RTA). Early identification of RTA remains challenging for inexperienced physicians, and diagnosis and treatment are often delayed. The presence of RTA should be considered in any patient with a high chloride level when the CL - /Na + ratio is above 0.79, if the patient does not have diarrhea. In patients with significant hyperkalemia one should evaluate for RTA type 4, especially in diabetic patients, with a relatively conserved renal function. A still growing list of medications can produce RTA. This review highlights practical aspects concerning normal anion gap metabolic acidosis.
Combination synchronization of time-delay chaotic system via robust ...
Indian Academy of Sciences (India)
Ayub Khan
2017-06-01
Jun 1, 2017 ... Combination synchronization of time-delay chaotic system via robust adaptive sliding mode control. AYUB KHAN and SHIKHA. ∗. Department of Mathematics, Jamia Millia Islamia, New Delhi 110 025, India. ∗. Corresponding author. E-mail: sshikha7014@gmail.com. MS received 29 July 2016; revised 25 ...
A systems thinking approach to eliminate delays on building ...
African Journals Online (AJOL)
It is obvious that the performance of firms and their market competitiveness hinge on project delivery time. Many approaches have been used to reduce the effect of the potential factors of delay on project delivery time. In this study, the system approach has been employed and validated. Inferential statistical analysis was ...
Pattern reverberation in networks of excitable systems with connection delays
Lücken, Leonhard; Rosin, David P.; Worlitzer, Vasco M.; Yanchuk, Serhiy
2017-01-01
We consider the recurrent pulse-coupled networks of excitable elements with delayed connections, which are inspired by the biological neural networks. If the delays are tuned appropriately, the network can either stay in the steady resting state, or alternatively, exhibit a desired spiking pattern. It is shown that such a network can be used as a pattern-recognition system. More specifically, the application of the correct pattern as an external input to the network leads to a self-sustained reverberation of the encoded pattern. In terms of the coupling structure, the tolerance and the refractory time of the individual systems, we determine the conditions for the uniqueness of the sustained activity, i.e., for the functionality of the network as an unambiguous pattern detector. We point out the relation of the considered systems with cyclic polychronous groups and show how the assumed delay configurations may arise in a self-organized manner when a spike-time dependent plasticity of the connection delays is assumed. As excitable elements, we employ the simplistic coincidence detector models as well as the Hodgkin-Huxley neuron models. Moreover, the system is implemented experimentally on a Field-Programmable Gate Array.
Measurement System for Playout Delay of TV Signals
Kooij, W.J.; Stokking, H.M.; Brandenburg, R. van; Boer, P.T. de
2014-01-01
TV signals are carried towards end-users using different (broadcast) technologies and by different providers. This is causing differences in the playout timing of the TV signal at different locations and devices. Authors have developed a measurement system for measuring the relative playout delay of
Relative controllability of nonlinear systems with multiple delays in ...
African Journals Online (AJOL)
Sufficient conditions are developed for the relative controllability of nonlinear systems with time-varying multiple delays in the state and control. The results are obtained by defining an appropriate control and its corresponding solution by an integral equation. This equation is then solved using the Schauder's fixed point ...
Relative controllability and null controllability of linear delay systems ...
African Journals Online (AJOL)
Necessary and sufficient conditions are established for the relative, absolute controllability and null controllability of the generalized linear delay system and its discrete prototype. The paper presents illuminating examples on previous controllability results by Manitius and Olbrot [7] and carries over the results of Onwuatu [8] ...
Complex systems fractionality, time-delay and synchronization
Sun, Jian-Qiao
2012-01-01
"Complex Systems: Fractionality, Time-delay and Synchronization" covers the most recent developments and advances in the theory and application of complex systems in these areas. Each chapter was written by scientists highly active in the field of complex systems. The book discusses a new treatise on fractional dynamics and control, as well as the new methods for differential delay systems and control. Lastly, a theoretical framework for the complexity and synchronization of complex system is presented. The book is intended for researchers in the field of nonlinear dynamics in mathematics, physics and engineering. It can also serve as a reference book for graduate students in physics, applied mathematics and engineering. Dr. Albert C.J. Luo is a Professor at Southern Illinois University Edwardsville, USA. Dr. Jian-Qiao Sun is a Professor at the University of California, Merced, USA.
H-infty Control of systems with multiple i/o delays
Agoes Ariffin Moelja, A.A.; Meinsma, Gjerrit; Mirkin, Leonid
2003-01-01
In this paper the standard (four-block) H-infty control problem for systems with multiple i/o delays in the feedback loop is studied. The central idea is to see the multiple delay operator as a special series connection of elementary delay operators, called the adobe delay operators. The adobe delay
Adaptive Stabilization for Nonholonomic Systems with Unknown Time Delays
Directory of Open Access Journals (Sweden)
Yuanyuan Wu
2013-01-01
Full Text Available This paper presents an adaptive control strategy for a class of nonholonomic systems in chained form with virtual control coefficients, nonlinear uncertainties, and unknown time delays. State scaling technique and backstepping recursive approach are applied to design a nonlinear state feedback controller, which can guarantee the stabilization of the closed-loop systems. The simulation results are provided to show the effectiveness of the proposed method.
Relaxation periodic solutions of one singular perturbed system with delay
Kashchenko, A. A.
2017-12-01
In this paper, we consider a singularly perturbed system of two differential equations with delay, simulating two coupled oscillators with a nonlinear compactly supported feedback. We reduce studying nonlocal dynamics of initial system to studying dynamics of special finite-dimensional mappings: rough stable (unstable) cycles of these mappings correspond to exponentially orbitally stable (unstable) relaxation solutions of initial problem. We show that dynamics of initial model depends on coupling coefficient crucially. Multistability is proved.
Periodicity of a class of nonlinear fuzzy systems with delays
International Nuclear Information System (INIS)
Yu Jiali; Yi Zhang; Zhang Lei
2009-01-01
The well known Takagi-Sugeno (T-S) model gives an effective method to combine some simple local systems with their linguistic description to represent complex nonlinear dynamic systems. By using the T-S method, a class of local nonlinear systems having nice dynamic properties can be employed to represent some global complex nonlinear systems. This paper proposes to study the periodicity of a class of global nonlinear fuzzy systems with delays by using T-S method. Conditions for guaranteeing periodicity are derived. Examples are employed to illustrate the theory.
Introduction to time-delay systems analysis and control
Fridman, Emilia
2014-01-01
The beginning of the 21st century can be characterized as the ”time-delay boom” leading to numerous important results. The purpose of this book is two-fold, to familiarize the non-expert reader with time-delay systems and to provide a systematic treatment of modern ideas and techniques for experts. This book is based on the course ”Introduction to time-delay systems” for graduate students in Engineering and Applied Mathematics that the author taught in Tel Aviv University in 2011-2012 and 2012-2013 academic years. The sufficient background to follow most of the material are the undergraduate courses in mathematics and an introduction to control. The book leads the reader from some basic classical results on time-delay systems to recent developments on Lyapunov-based analysis and design with applications to the hot topics of sampled-data and network-based control. The objective is to provide useful tools that will allow the reader not only to apply the existing methods, but also to develop new ones. It...
Metabolic Acidosis with Ophthalmic Dorzolamide in a Neonate.
Capino, Amanda C; Dannaway, Douglas C; Miller, Jamie L
2016-01-01
Carbonic anhydrase inhibitors are a common cause of normal anion gap metabolic acidosis; however, development is less commonly associated with ophthalmic administration of these agents. We report a case of a premature neonate who was being treated at our institution with betaxolol, dorzolamide, and latanoprost ophthalmic products for suspected bilateral congenital glaucoma. In addition, the patient was also receiving caffeine, ursodiol, and acidified liquid human milk fortifier. The patient developed a normal anion gap metabolic acidosis, and both dorzolamide ophthalmic solution and the acidified human milk fortifier were considered potential causes. Upon discontinuation of the dorzolamide ophthalmic solution and the switching of liquid human milk fortifiers, the normal anion gap metabolic acidosis gradually resolved. As a result of the pH and acidity, the acidified liquid human milk fortifier is thought to be associated with an anion gap acidosis; therefore, dorzolamide is suspected to be the primary cause of a normal gap acidosis. This case demonstrates that systemic effects can occur with ophthalmic administration of dorzolamide in a premature neonate. Ophthalmic agents should not be overlooked as a potential cause of systemic toxicity.
Optimal control for parabolic-hyperbolic system with time delay
International Nuclear Information System (INIS)
Kowalewski, A.
1985-07-01
In this paper we consider an optimal control problem for a system described by a linear partial differential equation of the parabolic-hyperbolic type with time delay in the state. The right-hand side of this equation and the initial conditions are not continuous functions usually, but they are measurable functions belonging to L 2 or Lsup(infinity) spaces. Therefore, the solution of this equation is given by a certain Sobolev space. The time delay in the state is constant, but it can be also a function of time. The control time T is fixed in our problem. Making use of the Milutin-Dubovicki theorem, necessary and sufficient conditions of optimality with the quadratic performance functional and constrained control are derived for the Dirichlet problem. The flow chart of the algorithm which can be used in the numerical solving of certain optimization problems for distributed systems is also presented. (author)
Bifurcation Analysis and Application for Impulsive Systems with Delayed Impulses
Church, Kevin E. M.; Liu, Xinzhi
In this article, we present a systematic approach to bifurcation analysis of impulsive systems with autonomous or periodic right-hand sides that may exhibit delayed impulse terms. Methods include Lyapunov-Schmidt reduction and center manifold reduction. Both methods are presented abstractly in the context of the stroboscopic map associated to a given impulsive system, and are illustrated by way of two in-depth examples: the analysis of a SIR model of disease transmission with seasonality and unevenly distributed moments of treatment, and a scalar logistic differential equation with a delayed census impulsive harvesting effort. It is proven that in some special cases, the logistic equation can exhibit a codimension two bifurcation at a 1:1 resonance point.
Controlling uncertain neutral dynamic systems with delay in control input
International Nuclear Information System (INIS)
Park, Ju H.; Kwon, O.
2005-01-01
This article gives a novel criterion for the asymptotic stabilization of the zero solutions of a class of neutral systems with delays in control input. By constructing Lyapunov functionals, we have obtained the criterion which is expressed in terms of matrix inequalities. The solutions of the inequalities can be easily solved by efficient convex optimization algorithms. A numerical example is included to illustrate the design procedure of the proposed method
INTERVAL STATE ESTIMATION FOR SINGULAR DIFFERENTIAL EQUATION SYSTEMS WITH DELAYS
Directory of Open Access Journals (Sweden)
T. A. Kharkovskaia
2016-07-01
Full Text Available The paper deals with linear differential equation systems with algebraic restrictions (singular systems and a method of interval observer design for this kind of systems. The systems contain constant time delay, measurement noise and disturbances. Interval observer synthesis is based on monotone and cooperative systems technique, linear matrix inequations, Lyapunov function theory and interval arithmetic. The set of conditions that gives the possibility for interval observer synthesis is proposed. Results of synthesized observer operation are shown on the example of dynamical interindustry balance model. The advantages of proposed method are that it is adapted to observer design for uncertain systems, if the intervals of admissible values for uncertain parameters are given. The designed observer is capable to provide asymptotically definite limits on the estimation accuracy, since the interval of admissible values for the object state is defined at every instant. The obtained result provides an opportunity to develop the interval estimation theory for complex systems that contain parametric uncertainty, varying delay and nonlinear elements. Interval observers increasingly find applications in economics, electrical engineering, mechanical systems with constraints and optimal flow control.
Lag synchronization of chaotic systems with time-delayed linear ...
Indian Academy of Sciences (India)
delayed linear terms via impulsive control is investigated. Based on the stability theory of impulsive delayed differen- tial equations, some sufficient conditions are obtained guaranteeing the synchronized behaviours between two delayed chaotic ...
Metabolic acidosis, rhabdomyolysis, and cardiovascular collapse after prolonged propofol infusion.
Cannon, M L; Glazier, S S; Bauman, L A
2001-12-01
The authors present the hospital course of a 13-year-old girl with a closed head injury who received a prolonged infusion of propofol for sedation and, subsequently, died as a result of severe metabolic acidosis, rhabdomyolysis, and cardiovascular collapse. The patient had been treated for 4 days at a referring hospital for a severe closed head injury sustained in a fall from a bicycle. During treatment for elevations of intracranial pressure, she received a continuous propofol infusion (100 microg/kg/min). The patient began to exhibit severe high anion gap/low lactate metabolic acidosis, and was transferred to the pediatric intensive care unit at the authors' institution. On arrival there, the patient's Glasgow Coma Scale score was 3 and this remained unchanged during her brief stay. The severe metabolic acidosis was unresponsive to maximum therapy. Acute renal failure ensued as a result of rhabdomyolysis, and myocardial dysfunction with bizarre, wide QRS complexes developed without hyperkalemia. The patient died of myocardial collapse with severe metabolic acidosis and multisystem organ failure (involving renal, hepatic, and cardiac systems) approximately 15 hours after admission to the authors' institution. This patient represents another case of severe metabolic acidosis, rhabdomyolysis, and cardiovascular collapse observed after a prolonged propofol infusion in a pediatric patient. The authors suggest selection of other pharmacological agents for long-term sedation in pediatric patients.
Immediate and delayed hypersensitivity to systemic corticosteroids: 2 case reports.
Laberge, Lauren; Pratt, Melanie
2012-01-01
Both immediate, type I reactions and delayed hypersensitivity, type IV reactions to systemic corticosteroid preparations have been reported. Type I reactions are rare, with delayed hypersensitivity reactions being slightly more common. A 33-year-old woman presented repeatedly to the emergency department with asthma attacks. She developed pruritus and hives approximately 30 minutes after the administration of parenteral corticosteroids. Her respiratory status deteriorated approximately 6 hours after she received the corticosteroids. An acute eczematous dermatitis on her face, neck, and upper body appeared 24 hours after administration of the corticosteroids. The dermatitis peaked at 72 hours. Intradermal testing to Solu-Medrol, Solu-Cortef, prednisone, and Decadron confirmed a type I, anaphylactoid reaction. The dermatitis that presented 24 hours after administration of the parenteral corticosteroids is consistent clinically with a type IV delayed hypersensitivity reaction to the corticosteroids. A second patient, a 51-year-old woman, developed urticarial lesions that lasted approximately 30 minutes, immediately after intralesional triamcinolone injections for keloid scars. Intradermal testing was performed. She showed a positive reaction to triamcinolone confirming a type I allergy to this steroid. It is important to consider an allergy to corticosteroids in patients with worsening anaphylactic symptoms after administration of systemic corticosteroids.
Prediction-Based Control for Nonlinear Systems with Input Delay
Directory of Open Access Journals (Sweden)
I. Estrada-Sánchez
2017-01-01
Full Text Available This work has two primary objectives. First, it presents a state prediction strategy for a class of nonlinear Lipschitz systems subject to constant time delay in the input signal. As a result of a suitable change of variable, the state predictor asymptotically provides the value of the state τ units of time ahead. Second, it proposes a solution to the stabilization and trajectory tracking problems for the considered class of systems using predicted states. The predictor-controller convergence is proved by considering a complete Lyapunov functional. The proposed predictor-based controller strategy is evaluated using numerical simulations.
Directory of Open Access Journals (Sweden)
Weihua Mao
2012-01-01
Full Text Available This paper discusses the mean-square exponential stability of uncertain neutral linear stochastic systems with interval time-varying delays. A new augmented Lyapunov-Krasovskii functional (LKF has been constructed to derive improved delay-dependent robust mean-square exponential stability criteria, which are forms of linear matrix inequalities (LMIs. By free-weight matrices method, the usual restriction that the stability conditions only bear slow-varying derivative of the delay is removed. Finally, numerical examples are provided to illustrate the effectiveness of the proposed method.
New delay-dependent absolute stability criteria for Lur'e systems with time-varying delay
Chen, Yonggang; Bi, Weiping; Li, Wenlin
2011-07-01
In this article, the absolute stability problem is investigated for Lur'e systems with time-varying delay and sector-bounded nonlinearity. By employing the delay fractioning idea, the new augmented Lyapunov functional is first constructed. Then, by introducing some slack matrices and by reserving the useful term when estimating the upper bound of the derivative of Lyapunov functional, the new delay-dependent absolute stability criteria are derived in terms of linear matrix inequalities. Several numerical examples are presented to show the effectiveness and the less conservativeness of the proposed method.
Diabetes, metformin and lactic acidosis.
Scale, T; Harvey, J N
2011-02-01
Metformin has long been thought to cause lactic acidosis (LA) but evidence from various sources has led researchers to question a direct causative relationship. We assessed the relationship of metformin prescription and other factors to the incidence of LA. All cases of LA at a single hospital were identified from laboratory lactate measurements. We compared patients classified as Cohen and Woods class A and B, patients with and without diabetes, and those taking metformin or not. LA was more common than in published analyses based on hospital coding of diagnoses. The incidence of LA was greater in diabetes than in the nondiabetic population but with no further increase in patients taking metformin. Lactate levels were no greater in patients on metformin than in patients with type 2 diabetes not on metformin even if patients with acute cardiorespiratory disturbance (Cohen and Woods class A) were excluded. Acidosis was greater in diabetes (hydrogen ion 94·9 ± 4·6 vs 83·2 ± 2·3 10(-9) m, P = 0·027) but factors besides lactate contributed. Acute cardiorespiratory illness, acute renal impairment and sepsis were the most common of the recognized precipitating factors. Age (P = 0·01), acute renal failure (P = 0·015) and sepsis (P = 0·005) were associated with mortality. Diabetes rather than metformin therapy is the major risk factor for the development of LA. Lactic acidosis occurs in association with acute illness particularly in diabetes. Current guidance for the prevention of lactic acidosis may overemphasize the role of metformin. © 2011 Blackwell Publishing Ltd.
Clinical profile of distal renal tubular acidosis
Directory of Open Access Journals (Sweden)
Ratan Jha
2011-01-01
Full Text Available To determine the clinical profile and progression of renal dysfunction in distal renal tubular acidosis (dRTA, we retrospectively studied 96 consecutive cases of dRTA diagnosed at our center. Patients with unexplained metabolic bone disease, short stature, hypokalemia, re-current renal stones, chronic obstructive uropathy or any primary autoimmune condition known to cause dRTA were screened. Distal RTA was diagnosed on the basis of systemic metabolic acidosis with urine pH >5.5 and positive urine anion gap. In those patients who had fasting urine pH >5.5 with normal baseline systemic pH and bicarbonate levels (incomplete RTA, acid load test with ammonium chloride was done. A cause of dRTA could be established in 53 (54% patients. Urological defect in children (22/44 and autoimmune disease in adults (11/52 were the commonest causes. Hypokalemic paralysis, proximal muscle weakness and voiding difficulty were the common modes of presentation. Doubling of serum creatinine during the study period was noted in 13 out of 27 patients who had GFR 60 mL/min (P <0.005. In conclusion, urological disorders were the commonest cause of dRTA in children while autoimmune disorders were the commonest asso-ciation in adults. Worse baseline renal function, longer duration of disease and greater frequency of nephrolithiasis/nephrocalcinosis and urological disorders were noted in those who had wor-sening of renal dysfunction during the study period.
Directory of Open Access Journals (Sweden)
Hamid Reza Karimi
2009-01-01
Full Text Available The problem of stability analysis for a class of neutral systems with mixed time-varying neutral, discrete and distributed delays and nonlinear parameter perturbations is addressed. By introducing a novel Lyapunov-Krasovskii functional and combining the descriptor model transformation, the Leibniz-Newton formula, some free-weighting matrices, and a suitable change of variables, new sufficient conditions are established for the stability of the considered system, which are neutral-delay-dependent, discrete-delay-range-dependent, and distributed-delay-dependent. The conditions are presented in terms of linear matrix inequalities (LMIs and can be efficiently solved using convex programming techniques. Two numerical examples are given to illustrate the efficiency of the proposed method.
DEFF Research Database (Denmark)
Barforooshan, Mohsen; Østergaard, Jan; Stavrou, Fotios
2017-01-01
, in this NCS, a causal but otherwise unconstrained feedback system carries out zero-delay variable-rate coding, and control. Between the encoder and decoder, data is exchanged over a rate-limited noiseless digital channel with a known constant time delay. Here we propose a linear source-coding scheme...... time delay at any given performance. In other words, attaining a specific performance level necessitates achieving a higher data rate when the channel time delay grows. The theoretical framework is demonstrated via an illustrative example.......This paper presents an upper bound on the minimum data rate required to achieve a prescribed closed-loop performance level in networked control systems (NCSs). The considered feedback loop includes a linear time-invariant (LTI) plant with single measurement output and single control input. Moreover...
A Class of Stochastic Nonlinear Delay System with Jumps
Directory of Open Access Journals (Sweden)
Ling Bai
2014-01-01
Full Text Available We consider stochastic suppression and stabilization for nonlinear delay differential system. The system is assumed to satisfy local Lipschitz condition and one-side polynomial growth condition. Since the system may explode in a finite time, we stochastically perturb this system by introducing independent Brownian noises and Lévy noise feedbacks. The contributions of this paper are as follows. (a We show that Brownian noises or Lévy noise may suppress potential explosion of the solution for some appropriate parameters. (b Using the exponential martingale inequality with jumps, we discuss the fact that the sample Lyapunov exponent is nonpositive. (c Considering linear Lévy processes, by the strong law of large number for local martingale, sufficient conditions for a.s. exponentially stability are investigated in Theorem 13.
Stability Tests of Positive Fractional Continuous-time Linear Systems with Delays
Directory of Open Access Journals (Sweden)
Tadeusz Kaczorek
2013-06-01
Full Text Available Necessary and sufficient conditions for the asymptotic stability of positive fractional continuous-time linear systems with many delays are established. It is shown that: 1 the asymptotic stability of the positive fractional system is independent of their delays, 2 the checking of the asymptotic stability of the positive fractional systems with delays can be reduced to checking of the asymptotic stability of positive standard linear systems without delays.
Ose evaluation of delay systems in a high threat environment
International Nuclear Information System (INIS)
Rich, B.L.; Cook, B.G.
1988-01-01
The Office of Security Evaluations (OSE) has in place an Evaluation Program to assist the Department of Energy (DOE) Headquarters and operations office managers by assessing specific elements of protection programs and informing the managers of common strengths and weaknesses of these elements. This information is provided so that sufficient and cost effective protection programs are maintained or enhanced. The subject of this paper is the evaluation of delay systems in the high-threat environment defined for sensitive DOE security interests such as special nuclear materials, nuclear weapons, and related classified devices and information
Simplified dead-time compensator for multiple delay SISO systems.
Torrico, Bismark Claure; Correia, Wilkley Bezerra; Nogueira, Fabrício Gonzalez
2016-01-01
This paper presents a dead-time compensation structure able to deal with stable and unstable multiple delay single input single output (SISO) systems. The proposed method aims to simplify the primary controller by replacing it for FIR filters placed at the feedback path. Such modification reduces the total number of parameters to be tuned which facilitates the overall design in comparison with other primary controllers normally considered. Simulation results show a better performance for the proposed control approach compared with other dead-time compensator (DTC) recently proposed in the literature. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.
The syndrome of irreversible acidosis after prolonged propofol infusion.
Kumar, Monisha A; Urrutia, Victor C; Thomas, Carole E; Abou-Khaled, Karine J; Schwartzman, Robert J
2005-01-01
Propofol infusion syndrome is described in the pediatric literature as metabolic acidosis, rhabdomyolysis, and bradycardia that results in death. The pathogenesis of this syndrome is thought to be activation of the systemic inflammatory response, which culminates in acidosis and muscle necrosis. Retrospective chart review of three patients in the Neurological Critical Care Units at Hahnemann and Massachusetts General Hospitals between October 2001 and September 2004. Patient 1: A 27-year-old woman had seizures secondary to hemorrhage from an arteriovenous malformation. Propofol coma was induced for sedation. After initiation of propofol, she developed a metabolic acidosis, hypotension, and bradycardia and expired. Patient 2: A 64-year-old man presented in status epilepticus. After prolonged propofol administration, he developed metabolic acidosis, hypotension, and rhabdomyolysis and expired. Patient 3: A 24-year-old woman presented in status epilepticus secondary to encephalitis. Propofol was added for seizure control. She developed hypotension, metabolic acidosis, and bradyarrhythmias. Despite transvenous pacing, she expired. These data show an association between extended propofol use and metabolic acidosis, rhabdomyolysis, and death in adults, as well as children. Risk factors for propofol infusion syndrome in adults include lean body mass index, high dose, and administration of more than 24-hour duration. Creatine phosphokinase, lactic acid levels, electrolytes, and arterial blood gases should be monitored frequently. Both bacterial and fungal cultures should be obtained. If this syndrome is suspected, hemodialysis should be considered. In fatal cases, autopsy should include electron microscopy of cardiac and skeletal muscle to look for mitochondrial dysfunction. Further study is warranted.
A unified approach for impulsive lag synchronization of chaotic systems with time delay
International Nuclear Information System (INIS)
Li Chuandong; Liao Xiaofeng; Zhang Rong
2005-01-01
In this paper, we propose a unified approach for impulsive lag-synchronization of a class of chaotic systems with time delay by employing the stability theory of impulsive delayed differential equations. Three well-known delayed chaotic systems are presented to illustrate our results. Also, the estimates of the stable regions for these systems are given, respectively
Design of Distributed Engine Control Systems with Uncertain Delay.
Liu, Xiaofeng; Li, Yanxi; Sun, Xu
Future gas turbine engine control systems will be based on distributed architecture, in which, the sensors and actuators will be connected to the controllers via a communication network. The performance of the distributed engine control (DEC) is dependent on the network performance. This study introduces a distributed control system architecture based on a networked cascade control system (NCCS). Typical turboshaft engine-distributed controllers are designed based on the NCCS framework with a H∞ output feedback under network-induced time delays and uncertain disturbances. The sufficient conditions for robust stability are derived via the Lyapunov stability theory and linear matrix inequality approach. Both numerical and hardware-in-loop simulations illustrate the effectiveness of the presented method.
Brain carbonic acid acidosis after acetazolamide
DEFF Research Database (Denmark)
Heuser, D; Astrup, J; Lassen, N A
1975-01-01
acidosis by I.V. injection of HCO3-minus. Acetazolamide (25 mg/kg) i.v. was followed by a marked brain acidosis which after 10 min had progressed to a drop in pH of 0.203 plus or minus 0.046 (x bar plus or minus S.D., n equals 8). The slowness ofthe development of acidosis points to a direct effect...
Preoperative metabolic acidosis in infants with gastroschisis.
El-Naggar, W; Almudeer, A; Vincer, M; Yanchar, N L
2017-01-01
There is little in literature regarding preoperative management of infants with gastroschisis. It is unclear if these infants develop metabolic acidosis as a consequence of prolonged intrauterine gut compromise or dehydration secondary to increased fluid loss. To assess the frequency of preoperative metabolic acidosis in infants with gastroschisis and investigate whether this acidosis reflects degree of gut compromise. All infants with gastroschisis born between May 2005 and April 2013 in a single tertiary care center were reviewed. Metabolic acidosis was defined by the presence of pH preoperative metabolic acidosis and its association with gastroschisis prognostic score (GPS), time to first and time to reach full feeds were investigated. Sixty infants were identified, 11 were excluded (birth depression/lack of preoperative blood gases). Median preoperative total fluid intake was 130 ml/kg/d. Nine infants (18%) had metabolic acidosis at a median age of 1.2 hours. No association was found between metabolic acidosis or serum lactate and GPS, age at first feed or age at full feeds. Preoperative metabolic acidosis was identified in a significant number of patients with gastroschisis despite high fluid intake. It does not appear to be associated with the degree of gut compromise. Using metabolic acidosis as an indication of dehydration in these patients needs more investigation.
Modified Schur-Cohn Criterion for Stability of Delayed Systems
Directory of Open Access Journals (Sweden)
Juan Ignacio Mulero-Martínez
2015-01-01
Full Text Available A modified Schur-Cohn criterion for time-delay linear time-invariant systems is derived. The classical Schur-Cohn criterion has two main drawbacks; namely, (i the dimension of the Schur-Cohn matrix generates some round-off errors eventually resulting in a polynomial of s with erroneous coefficients and (ii imaginary roots are very hard to detect when numerical errors creep in. In contrast to the classical Schur-Cohn criterion an alternative approach is proposed in this paper which is based on the application of triangular matrices over a polynomial ring in a similar way as in the Jury test of stability for discrete systems. The advantages of the proposed approach are that it halves the dimension of the polynomial and it only requires seeking real roots, making this modified criterion comparable to the Rekasius substitution criterion.
Dietary Acid Load and Metabolic Acidosis in Renal Transplant Recipients
Berg, van den Else; Engberink, M.F.; Brink, E.J.; Baak, van M.A.; Joosten, M.M.; Gans, R.O.B.; Navis, G.; Bakker, S.J.L.
2012-01-01
Background and objectives Acidosis is prevalent among renal transplant recipients (RTRs) and adversely affects cardiometabolic processes. Factors contributing to acidosis are graft dysfunction and immunosuppressive drugs. Little is known about the potential influence of diet on acidosis in RTRs.
Heterogeneous delay-induced asynchrony and resonance in a small-world neuronal network system
Yu, Wen-Ting; Tang, Jun; Ma, Jun; Yang, Xianqing
2016-06-01
A neuronal network often involves time delay caused by the finite signal propagation time in a given biological network. This time delay is not a homogenous fluctuation in a biological system. The heterogeneous delay-induced asynchrony and resonance in a noisy small-world neuronal network system are numerically studied in this work by calculating synchronization measure and spike interval distribution. We focus on three different delay conditions: double-values delay, triple-values delay, and Gaussian-distributed delay. Our results show the following: 1) the heterogeneity in delay results in asynchronous firing in the neuronal network, and 2) maximum synchronization could be achieved through resonance given that the delay values are integer or half-integer times of each other.
Robust Moving Horizon H∞ Control of Discrete Time-Delayed Systems with Interval Time-Varying Delays
Directory of Open Access Journals (Sweden)
F. Yıldız Tascikaraoglu
2014-01-01
Full Text Available In this study, design of a delay-dependent type moving horizon state-feedback control (MHHC is considered for a class of linear discrete-time system subject to time-varying state delays, norm-bounded uncertainties, and disturbances with bounded energies. The closed-loop robust stability and robust performance problems are considered to overcome the instability and poor disturbance rejection performance due to the existence of parametric uncertainties and time-delay appeared in the system dynamics. Utilizing a discrete-time Lyapunov-Krasovskii functional, some delay-dependent linear matrix inequality (LMI based conditions are provided. It is shown that if one can find a feasible solution set for these LMI conditions iteratively at each step of run-time, then we can construct a control law which guarantees the closed-loop asymptotic stability, maximum disturbance rejection performance, and closed-loop dissipativity in view of the actuator limitations. Two numerical examples with simulations on a nominal and uncertain discrete-time, time-delayed systems, are presented at the end, in order to demonstrate the efficiency of the proposed method.
Finite-Time Attractivity for Diagonally Dominant Systems with Off-Diagonal Delays
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T. S. Doan
2012-01-01
Full Text Available We introduce a notion of attractivity for delay equations which are defined on bounded time intervals. Our main result shows that linear delay equations are finite-time attractive, provided that the delay is only in the coupling terms between different components, and the system is diagonally dominant. We apply this result to a nonlinear Lotka-Volterra system and show that the delay is harmless and does not destroy finite-time attractivity.
Directory of Open Access Journals (Sweden)
Agata Bronisz
2014-04-01
Full Text Available Lactic acidosis is a form of metabolic acidosis with a high anion gap, reduced rate of arterial blood pH under 7.35 mmol/l, and lactic acid concentration over 7 mmol/l. In the literature we can find some descriptions of the cases of lactic acidosis in patients with severe systemic diseases (cancer, acquired immunodeficiency syndrome, sepsis, diabetes with cardiovascular disease and after organ transplantations. We present the case of lactic acidosis in a patient with no chronic disease - a firefighter in whom lactic acidosis has developed during standard exercises in the smoke chamber.
Robust Overlapping Guaranteed Cost Control of Uncertain State Discrete-Time Systems-Delay Systems
Czech Academy of Sciences Publication Activity Database
Bakule, Lubomír; Rodellar, J.; Rossell, J.-M.
2006-01-01
Roč. 51, č. 12 (2006), s. 1943-1950 ISSN 0018-9286 R&D Projects: GA AV ČR IAA2075304 Institutional research plan: CEZ:AV0Z10750506 Keywords : Decentralized control * large-scale systems * delay systems * robust control * discrete time systems Subject RIV: BC - Control Systems Theory Impact factor: 2.772, year: 2006
Smart Telerobotic Surveillance System via Internet with Reduced Time Delay
Directory of Open Access Journals (Sweden)
Ashesh Vasalya
2012-09-01
Full Text Available This work provides an imperial solution to the problems faced by man while enduring hazardous tasks like handling and disposal of nuclear wastes, monitoring nuclear power plants, mining operations etc .which have to be aborted if expertise group running it is unavailable or on a run. This paper presents a distributed platform that allows the special group of user to control a gadget (possibly a robot through internet as a medium. An advanced version of this technology is capable of transmitting graphic images and other surrounding information as required, via internet back to the user to facilitate the effective monitoring of the existent situation using appropriate software tools. The project uses the SRV-1 Mobile Surveillance Robot which is a fully integrated system standard designed and other related technology for surveillance purposes. It is driven via web browser using JAVA based control applications with live video feeds. Specialised user group will be given separate account from where they can control and monitor the system even when they are not present at the site. End user will be connected to the gadget (robot through a central server which acts as a single channel for both sending and receiving information. But the subject of remote control over the internet has some possible anomalies namely network freezing, delay between host and recipient, congested network and many others. This system enables asynchronous object passing so that network bandwidth is used effectively and such parameters as the network condition and server states have less effect on the system. To resolve this issue, a fuzzy logic controller is used to control the robot’s motion along a predefined path with the necessary manipulation of the normal course. The robot was first modelled in Matlab Simulink and the fuzzy logic rules were optimized for the best results possible. In accordance with the fuzzy rules developed the fuzzy interference system generates the
Delayed system control in presence of actuator saturation
Directory of Open Access Journals (Sweden)
A. Mahjoub
2014-09-01
Full Text Available The paper is introducing a new design method for systems’ controllers with input delay and actuator saturations and focuses on how to force the system output to track a reference input not necessarily saturation-compatible. We propose a new norm based on the way we quantify tracking performance as a function of saturation errors found using the same norm. The newly defined norm is related to signal average power making possible to account for most common reference signals e.g. step, periodic. It is formally shown that, whatever the reference shape and amplitude, the achievable tracking quality is determined by a well defined reference tracking mismatch error. This latter depends on the reference rate and its compatibility with the actuator saturation constraint. In fact, asymptotic output-reference tracking is achieved in the presence of constraint-compatible step-like references.
Ruminant Nutrition Symposium: Acidosis: new insights into the persistent problem.
Oba, M; Wertz-Lutz, A E
2011-04-01
The Ruminant Nutrition Symposium titled "Acidosis: New insights into the persistent problem" was held at the Joint Annual Meeting of the American Dairy Science Association, American Society of Animal Science, Poultry Science Association, Asociación Mexicana de Producción Animal, Western Section-ASAS, and the Canadian Society of Animal Science in Denver, Colorado, July 11 to 15, 2010. The objective of the symposium was to provide the ruminant nutrition community with new insights and perspectives from recent research findings on acidosis. Under modern production systems, ruminants are fed high-grain diets to maximize their energy intake and productivity. However, feeding highly fermentable diets often causes excess fermentation and results in accumulation of fermentation acids in the rumen, leading to a decrease in feed intake, poor feed efficiency, liver abscesses, and lameness in feedlot cattle or lactating dairy cows. Although our understanding of nutritional factors (i.e., effects of type and processing method of grains and importance of physically effective fiber) affecting rumen pH have increased substantially over the past few decades, rumen acidosis has continued to be a common problem in the ruminant livestock industry. The symposium program was organized to review recent research findings in acidosis with more emphasis on physiological aspects, and provide novel insights into the persistent problem.
Acidosis, magnesium and acetylsalicylic acid: Effects on thrombin
Borisevich, Nikolaj; Loznikova, Svetlana; Sukhodola, Aleksandr; Halets, Inessa; Bryszewska, Maria; Shcharbin, Dzmitry
2013-03-01
Thrombin, an enzyme from the hydrolase family, is the main component of the blood coagulation system. In ischemic stroke it acts as a serine protease that converts soluble fibrinogen into insoluble strands of fibrin forming blood clots in the brain. It has been found to phosphoresce at room temperature in the millisecond and microsecond ranges. The phosphorescence of thrombin was studied under physiological conditions, in acidosis (decrease of pH from 8.0 to 5.0) and on the addition of salts (magnesium sulfate and sodium chloride) and of acetylsalicylic acid, and its connection with thrombin function is discussed. Acidosis significantly increased the internal dynamics of thrombin. We propose that lactate-acidosis plays a protective role in stroke, preventing the formation of clots. The addition of NaCl and MgSO4 in different concentrations increased the internal dynamics of thrombin. Also, the addition of MgSO4 decreased thrombin-induced platelet aggregation. However, magnesium sulfate and acetylsalicylic acid in the therapeutic concentrations used for treatment of ischemic stroke had no effect on thrombin internal dynamics. The data obtained will help to elucidate the conformational stability of thrombin under conditions modulating lactate-acidosis and in the presence of magnesium sulfate.
Statistics and dimension of chaos in differential delay systems
Energy Technology Data Exchange (ETDEWEB)
Dorizzi, B.; Grammaticos, B.; Le Berre, M.; Pomeau, Y.; Ressayre, E.; Tallet, A.
1987-01-01
The chaotic solution of dissipative scalar-delay-differential equations with a nonlinear feedback periodic with respect to its argument is shown to behave as a Gaussian-Markovian process in a large time scale. The short time scale is shown to be defined by the correlation time of the delayed feedback. The dimension of the chaotic attractor is shown to be approximately equal to the number of short times that are contained inside the delay.
Statistics and dimension of chaos in differential delay systems
International Nuclear Information System (INIS)
Dorizzi, B.; Grammaticos, B.; Le Berre, M.; Pomeau, Y.; Ressayre, E.; Tallet, A.
1987-01-01
The chaotic solution of dissipative scalar-delay-differential equations with a nonlinear feedback periodic with respect to its argument is shown to behave as a Gaussian-Markovian process in a large time scale. The short time scale is shown to be defined by the correlation time of the delayed feedback. The dimension of the chaotic attractor is shown to be approximately equal to the number of short times that are contained inside the delay
Metformin-associated lactic acidosis (MALA)
DEFF Research Database (Denmark)
Lalau, Jean-Daniel; Kajbaf, Farshad; Protti, Alessandro
2017-01-01
Although metformin has been used for over 60 years, the balance between the drug's beneficial and adverse effects is still subject to debate. Following an analysis of how cases of so-called "metformin-associated lactic acidosis" (MALA) are reported in the literature, the present article reviews...... the pitfalls to be avoided when assessing the purported association between metformin and lactic acidosis. By starting from pathophysiological considerations, we propose a new paradigm for lactic acidosis in metformin-treated patients. Metformin therapy does not necessarily induce metformin accumulation, just...... as metformin accumulation does not necessarily induce hyperlactatemia, and hyperlactatemia does not necessarily induce lactic acidosis. In contrast to the conventional view, MALA probably accounts for a smaller proportion of cases than either metformin-unrelated lactic acidosis or metformin-induced lactic...
Compensation of distributed delays in integrated communication and control systems
Ray, Asok; Luck, Rogelio
1991-01-01
The concept, analysis, implementation, and verification of a method for compensating delays that are distributed between the sensors, controller, and actuators within a control loop are discussed. With the objective of mitigating the detrimental effects of these network induced delays, a predictor-controller algorithm was formulated and analyzed. Robustness of the delay compensation algorithm was investigated relative to parametric uncertainties in plant modeling. The delay compensator was experimentally verified on an IEEE 802.4 network testbed for velocity control of a DC servomotor.
Effects of time delay on stochastic resonance of the stock prices in financial system
International Nuclear Information System (INIS)
Li, Jiang-Cheng; Li, Chun; Mei, Dong-Cheng
2014-01-01
The effect of time delay on stochastic resonance of the stock prices in finance system was investigated. The time delay is introduced into the Heston model driven by the extrinsic and intrinsic periodic information for stock price. The signal power amplification (SPA) was calculated by numerical simulation. The results indicate that an optimal critical value of delay time maximally enhances the reverse-resonance in the behaviors of SPA as a function of long-run variance of volatility or cross correlation coefficient between noises for both cases of intrinsic and extrinsic periodic information. Moreover, in both cases, being a critical value in the delay time, when the delay time takes value below the critical value, reverse-resonance increases with the delay time increasing, however, when the delay time takes value above the critical value, the reverse-resonance decrease with the delay time increasing. - Highlights: • The effects of delay time on stochastic resonance of the stock prices was investigated. • There is an optimal critical value of delay time maximally enhances the reverse-resonance • The reverse-resonance increases with the delay time increasing as the delay time takes value below the critical value • The reverse-resonance decrease with the delay time increasing as the delay time takes value above the critical value
Effects of time delay on stochastic resonance of the stock prices in financial system
Energy Technology Data Exchange (ETDEWEB)
Li, Jiang-Cheng [Department of Physics, Yunnan University, Kunming, 650091 (China); Li, Chun [Department of Computer Science, Puer Teachers' College, Puer 665000 (China); Mei, Dong-Cheng, E-mail: meidch@ynu.edu.cn [Department of Physics, Yunnan University, Kunming, 650091 (China)
2014-06-13
The effect of time delay on stochastic resonance of the stock prices in finance system was investigated. The time delay is introduced into the Heston model driven by the extrinsic and intrinsic periodic information for stock price. The signal power amplification (SPA) was calculated by numerical simulation. The results indicate that an optimal critical value of delay time maximally enhances the reverse-resonance in the behaviors of SPA as a function of long-run variance of volatility or cross correlation coefficient between noises for both cases of intrinsic and extrinsic periodic information. Moreover, in both cases, being a critical value in the delay time, when the delay time takes value below the critical value, reverse-resonance increases with the delay time increasing, however, when the delay time takes value above the critical value, the reverse-resonance decrease with the delay time increasing. - Highlights: • The effects of delay time on stochastic resonance of the stock prices was investigated. • There is an optimal critical value of delay time maximally enhances the reverse-resonance • The reverse-resonance increases with the delay time increasing as the delay time takes value below the critical value • The reverse-resonance decrease with the delay time increasing as the delay time takes value above the critical value.
International Nuclear Information System (INIS)
Frank, T.D.
2006-01-01
First-order approximations of time-dependent solutions are determined for stochastic systems perturbed by time-delayed feedback forces. To this end, the theory of delay Fokker-Planck equations is applied in combination with Bayes' theorem. Applications to a time-delayed Ornstein-Uhlenbeck process and the geometric Brownian walk of financial physics are discussed
International Nuclear Information System (INIS)
Yan Huaicheng; Huang Xinhan; Wang Min; Zhang Hao
2008-01-01
This paper deals with the problem of delay-dependent robust stability for linear systems with time-varying structured uncertainties and multiple time-varying state delays. Based on Lyapunov stability theory combined with linear matrix inequalities (LMIs) techniques, some new delay-dependent stability criteria in terms of LMIs are derived by taking the relationship between the terms in the Leibniz-Newton formula into account. Since free weighting matrices are used to express this relationship and appropriate ones are selected by means of LMIs, the new improved criteria are much less conservative and more general. Numerical examples and simulation suggest that the results are effective and are an improvement over previous ones
Efimov, Denis; Schiffer, Johannes; Ortega, Romeo
2016-05-01
Motivated by the problem of phase-locking in droop-controlled inverter-based microgrids with delays, the recently developed theory of input-to-state stability (ISS) for multistable systems is extended to the case of multistable systems with delayed dynamics. Sufficient conditions for ISS of delayed systems are presented using Lyapunov-Razumikhin functions. It is shown that ISS multistable systems are robust with respect to delays in a feedback. The derived theory is applied to two examples. First, the ISS property is established for the model of a nonlinear pendulum and delay-dependent robustness conditions are derived. Second, it is shown that, under certain assumptions, the problem of phase-locking analysis in droop-controlled inverter-based microgrids with delays can be reduced to the stability investigation of the nonlinear pendulum. For this case, corresponding delay-dependent conditions for asymptotic phase-locking are given.
Subsecond Tsunamis and Delays in Decentralized Electronic Systems
Directory of Open Access Journals (Sweden)
Pedro D. Manrique
2017-10-01
Full Text Available Driven by technological advances and economic gain, society’s electronic systems are becoming larger, faster, more decentralized and autonomous, and yet with increasing global reach. A prime example are the networks of financial markets which—in contrast to popular perception—are largely all-electronic and decentralized with no top-down real-time controller. This prototypical system generates complex subsecond dynamics that emerge from a decentralized network comprising heterogeneous hardware and software components, communications links, and a diverse ecology of trading algorithms that operate and compete within this all-electronics environment. Indeed, these same technological and economic drivers are likely to generate a similarly competitive all-electronic ecology in a variety of future cyberphysical domains such as e-commerce, defense and the transportation system, including the likely appearance of large numbers of autonomous vehicles on the streets of many cities. Hence there is an urgent need to deepen our understanding of stability, safety and security across a wide range of ultrafast, large, decentralized all-electronic systems—in short, society will eventually need to understand what extreme behaviors can occur, why, and what might be the impact of both intentional and unintentional system perturbations. Here we set out a framework for addressing this issue, using a generic model of heterogeneous, adaptive, autonomous components where each has a realistic limit on the amount of information and processing power available to it. We focus on the specific impact of delayed information, possibly through an accidental shift in the latency of information transmission, or an intentional attack from the outside. While much remains to be done in terms of developing formal mathematical results for this system, our preliminary results indicate the type of impact that can occur and the structure of a mathematical theory which may
Directory of Open Access Journals (Sweden)
Han Ruolan
2008-04-01
Full Text Available Abstract Background Cancer treatment with a variety of chemotherapeutic agents often is associated with delayed adverse neurological consequences. Despite their clinical importance, almost nothing is known about the basis for such effects. It is not even known whether the occurrence of delayed adverse effects requires exposure to multiple chemotherapeutic agents, the presence of both chemotherapeutic agents and the body's own response to cancer, prolonged damage to the blood-brain barrier, inflammation or other such changes. Nor are there any animal models that could enable the study of this important problem. Results We found that clinically relevant concentrations of 5-fluorouracil (5-FU; a widely used chemotherapeutic agent were toxic for both central nervous system (CNS progenitor cells and non-dividing oligodendrocytes in vitro and in vivo. Short-term systemic administration of 5-FU caused both acute CNS damage and a syndrome of progressively worsening delayed damage to myelinated tracts of the CNS associated with altered transcriptional regulation in oligodendrocytes and extensive myelin pathology. Functional analysis also provided the first demonstration of delayed effects of chemotherapy on the latency of impulse conduction in the auditory system, offering the possibility of non-invasive analysis of myelin damage associated with cancer treatment. Conclusions Our studies demonstrate that systemic treatment with a single chemotherapeutic agent, 5-FU, is sufficient to cause a syndrome of delayed CNS damage and provide the first animal model of delayed damage to white-matter tracts of individuals treated with systemic chemotherapy. Unlike that caused by local irradiation, the degeneration caused by 5-FU treatment did not correlate with either chronic inflammation or extensive vascular damage and appears to represent a new class of delayed degenerative damage in the CNS.
Health system delay in treatment of multidrug resistant tuberculosis patients in Bangladesh.
Rifat, Mahfuza; Hall, John; Oldmeadow, Christopher; Husain, Ashaque; Milton, Abul Hasnat
2015-11-16
Bangladesh is one of the 27 high burden countries for multidrug resistant tuberculosis listed by the World Health Organization. Delay in multidrug resistant tuberculosis treatment may allow progression of the disease and affect the attempts to curb transmission of drug resistant tuberculosis. The main objective of this study was to investigate the health system delay in multidrug resistant tuberculosis treatment in Bangladesh and to explore the factors related to the delay. Information related to the delay was collected as part of a previously conducted case-control study. The current study restricts analysis to patients with multidrug resistant tuberculosis who were diagnosed using rapid diagnostic methods (Xpert MTB/RIF or the line probe assay). Information was collected by face-to-face interviews and through record reviews from all three Government hospitals providing multidrug resistant tuberculosis services, from September 2012 to April 2013. Multivariable regression analysis was performed using Bootstrap variance estimators. Definitions were as follows: Provider delay: time between visiting a provider for first consultation on MDR-TB related symptom to visiting a designated diagnostic centre for testing; Diagnostic delay: time from date of diagnostic sample provided to date of result; Treatment initiation delay: time between the date of diagnosis and date of treatment initiation; Health system delay: time between visiting a provider to start of treatment. Health system delay was derived by adding provider delay, diagnostic delay and treatment initiation delay. The 207 multidrug resistant tuberculosis patients experienced a health system delay of median 7.1 weeks. The health system delay consists of provider delay (median 4 weeks), diagnostic delay (median 5 days) and treatment initiation delay (median 10 days). Health system delay (Coefficient: 37.7; 95 %; CI 15.0-60.4; p 0.003) was associated with the visit to private practitioners for first consultation
Effects of time delay on stochastic resonance of the stock prices in financial system
Li, Jiang-Cheng; Li, Chun; Mei, Dong-Cheng
2014-06-01
The effect of time delay on stochastic resonance of the stock prices in finance system was investigated. The time delay is introduced into the Heston model driven by the extrinsic and intrinsic periodic information for stock price. The signal power amplification (SPA) was calculated by numerical simulation. The results indicate that an optimal critical value of delay time maximally enhances the reverse-resonance in the behaviors of SPA as a function of long-run variance of volatility or cross correlation coefficient between noises for both cases of intrinsic and extrinsic periodic information. Moreover, in both cases, being a critical value in the delay time, when the delay time takes value below the critical value, reverse-resonance increases with the delay time increasing, however, when the delay time takes value above the critical value, the reverse-resonance decrease with the delay time increasing.
Lipid myopathy associated with renal tubular acidosis and spastic diplegia in two brothers.
Tung, Y C; Tsau, Y K; Chu, L W; Young, C; Shen, Y Z
2001-07-01
Lipid myopathy is a group of disorders involving mitochondrial fatty acid oxidation. We describe two brothers, 3 years 8 months old and 2 years 9 months old, respectively, with progressive spastic diplegia, developmental delay, failure to thrive, and chronic metabolic acidosis who had lipid myopathy and renal tubular acidosis. Brain magnetic resonance imaging revealed demyelinating changes in the periventricular white matter, which was compatible with spastic diplegia. These symptoms may be related to errors in fatty acid metabolism. Cerebral palsy had been misdiagnosed in both of these patients at another hospital. Therefore, for patients with late-onset and progressive spastic diplegia, detailed investigations for underlying diseases are warranted.
Directory of Open Access Journals (Sweden)
Riku Varjopuro
2014-12-01
Full Text Available In this paper we focus on systemic delays in the Baltic Sea that cause the problem of eutrophication to persist. These problems are demonstrated in our study by addressing three types of delays: (1 decision delay: the time it takes for an idea or perceived need to be launched as a policy; (2 implementation delay: the time from the launch of a policy to the actual implementation; (3 ecosystem delay: the time difference between the implementation and an actual measurable effects. A policy process is one characterized by delays. It may take years from problem identification to a decision to taking action and several years further for actual implementation. Ecosystem responses to measures illustrate that feedback can keep the ecosystem in a certain state and cause a delay in ecosystem response. These delays can operate on decadal scales. Our aim in this paper is to analyze these systemic delays and especially to discuss how the critical delays can be better addressed in marine protection policies by strengthening the adaptive capacity of marine protection. We conclude that the development of monitoring systems and reflexive, participatory analysis of dynamics involved in the implementation are keys to improve understanding of the systemic delays. The improved understanding is necessary for the adaptive management of a persistent environmental problem. In addition to the state of the environment, the monitoring and analysis should be targeted also at the implementation of policies to ensure that the societies are investing in the right measures.
Lactic acidosis in patients with diabetes.
Krzymień, Janusz; Karnafel, Waldemar
2013-01-01
Lactic acidosis is a relatively rare complication diagnosed in patients with diabetes. The aim of this study was to identify causes of lactic acidosis in patients with diabetes and to measure the extent of metabolic disturbances based on the available laboratory test results. A total of 29 diabetic patients aged 20-87 years were admitted to the Intensive Diabetes Care Unit of the Warsaw Medical University in the years 2007-2012 with the diagnosis of lactic acidosis (lactate level >5 mmol/l). A detailed medical history was taken from all patients or their caregivers. Lactate levels, glycemia, acetonuria, and gasometry were measured on admission. Eight patients with type 1 diabetes, 18 patients with type 2 diabetes, and 3 patients with other types of diabetes were hospitalized with the diagnosis of lactic acidosis. Lactic acidosis (lactate levels, 5.2-27 mmol/l) was associated with increased glycemia (13.3-91.7 mmol/l) and low pH (6.73-7.28). Alcohol abuse was reported in 12 subjects based on medical history. In 3 women, acute diabetic complication was caused by psychogenic eating disorders. There were 5 fatal cases including 3 cases of metformin treatment. Alcohol abuse and its effects on health seem to be the main cause of lactic acidosis in diabetic patients. Metformin-treated patients, especially elderly ones, are at a risk of sudden deterioration of renal function, which in turn may increase the risk of lactic acidosis.
Constructing optimized binary masks for reservoir computing with delay systems
Appeltant, Lennert; van der Sande, Guy; Danckaert, Jan; Fischer, Ingo
2014-01-01
Reservoir computing is a novel bio-inspired computing method, capable of solving complex tasks in a computationally efficient way. It has recently been successfully implemented using delayed feedback systems, allowing to reduce the hardware complexity of brain-inspired computers drastically. In this approach, the pre-processing procedure relies on the definition of a temporal mask which serves as a scaled time-mutiplexing of the input. Originally, random masks had been chosen, motivated by the random connectivity in reservoirs. This random generation can sometimes fail. Moreover, for hardware implementations random generation is not ideal due to its complexity and the requirement for trial and error. We outline a procedure to reliably construct an optimal mask pattern in terms of multipurpose performance, derived from the concept of maximum length sequences. Not only does this ensure the creation of the shortest possible mask that leads to maximum variability in the reservoir states for the given reservoir, it also allows for an interpretation of the statistical significance of the provided training samples for the task at hand.
On the delay effects of different channels in Internet-based networked control systems
Zhao, Yun-Bo; Kim, Jongrae; Sun, Xi-Ming; Liu, Guo-Ping
2013-11-01
The sensor-to-controller and the controller-to-actuator delays in networked control systems (NCSs) are investigated for the first time with respect to their different effects on the system performance. This study starts with identifying the delay-independent and delay-dependent control laws in NCSs, and confirms that only two delay-dependent control laws can cause different delay effects in different channels. The conditions under which the different delays in different channels can cause different effects are then given for both delay-dependent control laws. The results are verified by numerical examples. Potentially, these results can be regarded as important design principles in the practical implementation of NCSs.
Role of lactate in ischemic acidosis
International Nuclear Information System (INIS)
Nagai, Y.; Naruse, S.; Vink, R.; Weiner, M.W.
1987-01-01
Brain ischemia produces cerebral acidosis that is associated with a rise in lactic acid levels. It is generally thought that the acidosis is due to lactic acid. To investigate this, rats were made hypoglycemic with insulin and the cerebral ischemia was produced. P-31 MR imaging and H-1 MR spectroscopy were used to measure pH and lactate. Hypoclygemia inhibited the rise in lactic acid levels but did not affect pH. Therefore, the fall in pH produced by cerebral ischemia cannot be due to lactic acidosis
A system of abstract measure delay differential equations
Directory of Open Access Journals (Sweden)
Bapurao Dhage
2003-01-01
Full Text Available In this paper existence and uniqueness results for an abstract measure delay differential equation are proved, by using Leray-Schauder nonlinear alternative, under Carathéodory conditions.
From dynamical systems with time-varying delay to circle maps and Koopman operators
Müller, David; Otto, Andreas; Radons, Günter
2017-06-01
In this paper, we investigate the influence of the retarded access by a time-varying delay on the dynamics of delay systems. We show that there are two universality classes of delays, which lead to fundamental differences in dynamical quantities such as the Lyapunov spectrum. Therefore, we introduce an operator theoretic framework, where the solution operator of the delay system is decomposed into the Koopman operator describing the delay access and an operator similar to the solution operator known from systems with constant delay. The Koopman operator corresponds to an iterated map, called access map, which is defined by the iteration of the delayed argument of the delay equation. The dynamics of this one-dimensional iterated map determines the universality classes of the infinite-dimensional state dynamics governed by the delay differential equation. In this way, we connect the theory of time-delay systems with the theory of circle maps and the framework of the Koopman operator. In this paper, we extend our previous work [A. Otto, D. Müller, and G. Radons, Phys. Rev. Lett. 118, 044104 (2017), 10.1103/PhysRevLett.118.044104] by elaborating the mathematical details and presenting further results also on the Lyapunov vectors.
Recent results on nonlinear delay control systems in honor of Miroslav Krstic
Pepe, Pierdomenico; Mazenc, Frederic; Karafyllis, Iasson
2016-01-01
This volume collects recent advances in nonlinear delay systems, with an emphasis on constructive generalized Lyapunov and predictive approaches that certify stability properties. The book is written by experts in the field and includes two chapters by Miroslav Krstic, to whom this volume is dedicated. This volume is suitable for all researchers in mathematics and engineering who deal with nonlinear delay control problems and students who would like to understand the current state of the art in the control of nonlinear delay systems.
Identification and characterization of systems with delayed feedback: (I) Theory and tools
Bünner, Martin J.; Ciofini, Marco; Giaquinta, Antonino; Hegger, Rainer; Kantz, Holger; Meucci, Riccardo; Politi, Antonio
1999-01-01
High-dimensional chaos displayed by multi-component systems with a single time-delayed feedback is shown to be accessible to time series analysis of a scalar variable only. The mapping of the original dynamics onto scalar time-delay systems defined on sufficiently high dimensional spaces is thoroughly discussed. The dimension of the ``embedding'' space turns out to be independent of the delay time and thus of the dimensionality of the attractor dynamics. As a consequence, the procedure descri...
Directory of Open Access Journals (Sweden)
Hajnalka Péics
2016-08-01
Full Text Available The asymptotic behavior of solutions of the system of difference equations with continuous time and lag function between two known real functions is studied. The cases when the lag function is between two linear delay functions, between two power delay functions and between two constant delay functions are observed and illustrated by examples. The asymptotic estimates of solutions of the considered system are obtained.
Synchronization of Different Fractional Order Time-Delay Chaotic Systems Using Active Control
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Jianeng Tang
2014-01-01
Full Text Available Chaos synchronization of different fractional order time-delay chaotic systems is considered. Based on the Laplace transform theory, the conditions for achieving synchronization of different fractional order time-delay chaotic systems are analyzed by use of active control technique. Then numerical simulations are provided to verify the effectiveness and feasibility of the developed method. At last, effects of the fraction order and the time delay on synchronization are further researched.
Xu, Q; HowlettClyne, S; Fuezery, A; Cembrowski, G S
2017-12-01
Lactic acidosis represents the pathologic accumulation of lactate and hydrogen ions. It is important to efficiently diagnose lactic acidosis as delayed treatment will lead to poor patient outcomes. As plasma lactate levels may not be rapidly available, some physicians may use elevated anion gaps to test for the need to measure lactate. All Edmonton metropolitan hospitals have Radiometer blood gas/electrolyte instruments in the ED or close by. As lactate is measured for each set of electrolytes, we were able to determine the effectiveness of a screening anion gap for lactic acidosis. Two years of emergency department lactates and electrolytes from Edmonton's 5 metropolitan hospitals were analyzed. We determined the sensitivity, specificity and positive predictive value of detecting an elevated lactate, defined as ≥2.5mmol/L or ≥4mmol/L. Depending on the elevated anion gap cut-off and the definition of elevated lactate, between 40-80% of elevated lactates are missed. In general, the positive predictive value approaches 40% for AGs ≥12mmol/L and 60% for AGs ≥16mmol/L. Anion gap is an inadequate marker of lactic acidosis. We recommend that lactate be done with each set of electrolytes and/or blood gases. In this way lactic acidosis will not be missed. Copyright © 2017. Published by Elsevier Inc.
Asymptotic and numerical studies of a differential-delay system
Semak, Matthew Richard
A singularly-perturbed differential-delay equation is studied the form of which is seen in various fields. Relaxation effects are combined with nonlinear driving from the past in this system. Having an infinite dimensional phase space, this flow is capable of very interesting behavior. Among the rich aspects of the dynamics of such a relation, period doubling can be observed as parameters are varied. Rigorous proofs concerning the existence of such periodic solutions can be found in the literature. Attention is given to the (first) Hopf bifurcation as the periodic structure is born. Key questions concern the limit of fast relaxation. In this limit, one can analytically understand the development of the periodic solution in the neighborhood of the bifurcation along with the frequency shift which is encountered. This limit also reveals the underlying mapping structure present. In the model studied, this is the logistic map the behavior of which is well-known. Convergence of periodic solutions to the mapping's square wave involves central issues in this work. An analogue to Gibb's phenomenon presents itself as the mapping structure is approached for a certain range of parameters. Transition layers also exist and, together with the latter, present a challenge to various computational approaches. A highly accurate and efficient spectral numerical technique is introduced to properly resolve such behavior in the limit studied. This scheme is used to measure the period's dependence on the relaxation rate in this region of parameter space. Also, numerically assisted asymptotic analysis develops relations for the layers. Moreover, regimes of parameter values have been identified for which there exist extremely long-lived transient states of arbitrarily complex form. Finally, initial interval states are designed which lead to specific long-lived multi-layer patterns of significant complexity. Layer-layer interactions are considered concerning the formation and lifetime of
A neglected case of Renal Tubular Acidosis
International Nuclear Information System (INIS)
Derakhshan, A.; Basiratnia, M.; Fallahzadeh, M.H.; Al-Hashemi, G.H.
2007-01-01
In this report, we present a case of a child with distal renal tubular acidosis, severe failure to thrive and profound rickets, who was only 7.8 Kg when presented at 6 years of age. His response to treatment and his follow up for four years is discussed. Although failure to thrive is a common finding in renal tubular acidosis but the physical and x-ray findings in our case were unique. (author)
Delayed feedback on the dynamical model of a financial system
Energy Technology Data Exchange (ETDEWEB)
Son, Woo-Sik, E-mail: dawnmail@sogang.ac.k [Department of Physics, Sogang University, Seoul 121-742 (Korea, Republic of); Department of Service Systems Management and Engineering, Sogang University, Seoul 121-742 (Korea, Republic of); Park, Young-Jai, E-mail: yjpark@sogang.ac.k [Department of Physics, Sogang University, Seoul 121-742 (Korea, Republic of); Department of Service Systems Management and Engineering, Sogang University, Seoul 121-742 (Korea, Republic of)
2011-04-15
Research highlights: Effect of delayed feedbacks on the financial model. Proof on the occurrence of Hopf bifurcation by local stability analysis. Numerical bifurcation analysis on delay differential equations. Observation of supercritical and subcritical Hopf, fold limit cycle, Neimark-Sacker, double Hopf and generalized Hopf bifurcations. - Abstract: We investigate the effect of delayed feedbacks on the financial model, which describes the time variation of the interest rate, the investment demand, and the price index, for establishing the fiscal policy. By local stability analysis, we theoretically prove the occurrences of Hopf bifurcation. Through numerical bifurcation analysis, we obtain the supercritical and subcritical Hopf bifurcation curves which support the theoretical predictions. Moreover, the fold limit cycle and Neimark-Sacker bifurcation curves are detected. We also confirm that the double Hopf and generalized Hopf codimension-2 bifurcation points exist.
Bistable traveling waves for a competitive-cooperative system with nonlocal delays
Tian, Yanling; Zhao, Xiao-Qiang
2018-04-01
This paper is devoted to the study of bistable traveling waves for a competitive-cooperative reaction and diffusion system with nonlocal time delays. The existence of bistable waves is established by appealing to the theory of monotone semiflows and the finite-delay approximations. Then the global stability of such traveling waves is obtained via a squeezing technique and a dynamical systems approach.
Absolute stability of nonlinear systems with time delays and applications to neural networks
Directory of Open Access Journals (Sweden)
Xinzhi Liu
2001-01-01
Full Text Available In this paper, absolute stability of nonlinear systems with time delays is investigated. Sufficient conditions on absolute stability are derived by using the comparison principle and differential inequalities. These conditions are simple and easy to check. In addition, exponential stability conditions for some special cases of nonlinear delay systems are discussed. Applications of those results to cellular neural networks are presented.
Propagation Delay Uncertainty in Time-Of Systems
Feehrer, John Ross
1995-01-01
This dissertation presents a study of how propagation delay uncertainty affects the performance of time-of-flight synchronized digital circuits. Time-of-flight synchronization is a new timing method suitable for technologies such as optoelectronics having highly controllable propagation delay. No bistable memory elements are required, and synchronization is accomplished by precise adjustments of interconnect lengths. Delay is distributed over connections so that, nominally, pulses arrive at a common destination simultaneously. Clock gating and pulse stretching are used to restore timing of pulses. Time multiplexing is used to increase computational throughput, whereby a major cycle is divided into a number of minor cycles, each representing an independent virtual machine. What limits the amount of multiplexing that is feasible is the controllability of delay. The principle focus of this research is methods for computing the minimum feasible minor cycle and the amount of stretch needed to prevent synchronization errors. Due to the unique circuit features, timing analysis differs significantly from analysis of conventional digital circuits. Models of delay uncertainty accounting for static and dynamic effects are discussed for discrete and integrated implementations. Methods for placing a minimal set of clock gates necessary for a functional circuit are presented. The minimum feasible major cycle is computed using nominal delays. A method for computing the arrival time and pulse width uncertainty at each node in the circuit is presented. The circuit graph is traversed and device uncertainty functions operating on worst-case input pulse parameters are applied at vertices. Using pulse timing parameters obtained from the traversal, timing constraints are generated. A constrained minimization problem to find the minimum feasible minor cycle is then presented and solved. Two variations on this problem are presented. Circuit structural issues that affect the accuracy of
H∞ Consensus for Multiagent Systems with Heterogeneous Time-Varying Delays
Directory of Open Access Journals (Sweden)
Beibei Wang
2013-01-01
Full Text Available We apply the linear matrix inequality method to consensus and H∞ consensus problems of the single integrator multiagent system with heterogeneous delays in directed networks. To overcome the difficulty caused by heterogeneous time-varying delays, we rewrite the multiagent system into a partially reduced-order system and an integral system. As a result, a particular Lyapunov function is constructed to derive sufficient conditions for consensus of multiagent systems with fixed (switched topologies. We also apply this method to the H∞ consensus of multiagent systems with disturbances and heterogeneous delays. Numerical examples are given to illustrate the theoretical results.
Directory of Open Access Journals (Sweden)
Cheng Jiang
2014-01-01
Full Text Available This paper considers a discrete-time bulk-service queue with infinite buffer space and delay multiple working vacations. Considering a late arrival system with delayed access (LAS-AD, it is assumed that the inter-arrival times, service times, vacation times are all geometrically distributed. The server does not take a vacation immediately at service complete epoch but keeps idle period. According to a bulk-service rule, at least one customer is needed to start a service with a maximum serving capacity 'a'. Using probability analysis method and displacement operator method, the queue length and the probability generating function of waiting time at pre-arrival epochs are obtained. Furthermore, the outside observer’s observation epoch queue length distributions are given. Finally, computational examples with numerical results in the form of graphs and tables are discussed.
Equilibrium of a two-route system with delayed information feedback strategies
International Nuclear Information System (INIS)
Zhao, Xiao-mei; Xie, Dong-fan; Gao, Zi-you; Gao, Liang
2013-01-01
In intelligent transport system, some advanced information feedback strategies have been developed to reduce the oscillations and enhance the capacity on the road level. However, seldom strategies have considered the information delay and user equilibrium (UE) objective. Here, a derivative cost feedback strategy (DCFS) is proposed to reduce the influence of the delay, based on the UE principle. The simulation results show that in both no-delay and delay information cases, DCFS are the best and can make the system reaching the UE. Because DCFS can predict the trend of the travel cost.
Reconstruction of ensembles of coupled time-delay systems from time series.
Sysoev, I V; Prokhorov, M D; Ponomarenko, V I; Bezruchko, B P
2014-06-01
We propose a method to recover from time series the parameters of coupled time-delay systems and the architecture of couplings between them. The method is based on a reconstruction of model delay-differential equations and estimation of statistical significance of couplings. It can be applied to networks composed of nonidentical nodes with an arbitrary number of unidirectional and bidirectional couplings. We test our method on chaotic and periodic time series produced by model equations of ensembles of diffusively coupled time-delay systems in the presence of noise, and apply it to experimental time series obtained from electronic oscillators with delayed feedback coupled by resistors.
International Nuclear Information System (INIS)
Brett, Tobias; Galla, Tobias
2014-01-01
We present a heuristic derivation of Gaussian approximations for stochastic chemical reaction systems with distributed delay. In particular, we derive the corresponding chemical Langevin equation. Due to the non-Markovian character of the underlying dynamics, these equations are integro-differential equations, and the noise in the Gaussian approximation is coloured. Following on from the chemical Langevin equation, a further reduction leads to the linear-noise approximation. We apply the formalism to a delay variant of the celebrated Brusselator model, and show how it can be used to characterise noise-driven quasi-cycles, as well as noise-triggered spiking. We find surprisingly intricate dependence of the typical frequency of quasi-cycles on the delay period
Brett, Tobias; Galla, Tobias
2014-03-28
We present a heuristic derivation of Gaussian approximations for stochastic chemical reaction systems with distributed delay. In particular, we derive the corresponding chemical Langevin equation. Due to the non-Markovian character of the underlying dynamics, these equations are integro-differential equations, and the noise in the Gaussian approximation is coloured. Following on from the chemical Langevin equation, a further reduction leads to the linear-noise approximation. We apply the formalism to a delay variant of the celebrated Brusselator model, and show how it can be used to characterise noise-driven quasi-cycles, as well as noise-triggered spiking. We find surprisingly intricate dependence of the typical frequency of quasi-cycles on the delay period.
Directory of Open Access Journals (Sweden)
M.L.R. Leal
2007-08-01
Full Text Available Foram utilizados seis novilhos, providos de cânula ruminal, em delineamento experimental cross-over, para comparar a eficiência de soluções de bicarbonato de sódio e lactato-L de sódio na correção da acidose metabólica sistêmica (AMS, causada pela acidose láctica ruminal (ALR. Vinte horas após, quando apresentavam intensa AMS, os animais foram distribuídos aleatoriamente e tratados com cinco litros de 150mMol/l de bicarbonato de sódio ou de lactato-L de sódio, infundidas por via intravenosa, nas quatro horas seguintes. Amostras de sangue, para hemogasometria, foram coletadas no decorrer da infusão a zero, 1, 2, 3, 4, 6 e 8 horas. Ambos os tratamentos elevaram o pH sangüíneo já na primeira hora pós-infusão, corrigindo adequadamente a AMS. O tratamento com lactato-L de sódio aumentou as concentrações de bicarbonato, TCO2 e EAB sangüíneos já na segunda hora pós-infusão; com o bicarbonato essa elevação ocorreu a partir da terceira hora. Não houve diferenças entre tratamentos para pH sangüíneo, bicarbonato, TCO2 e excesso de base. Vinte e quatro horas após o tratamento todos os novilhos apresentaram plena recuperação. O lactato-L pode substituir o bicarbonato na correção da AMS em novilhos com ALR.The efficiency of sodium bicarbonate or l-lactate for correcting systemic metabolic acidosis (SMA caused by rumen lactic acidosis (RLA was evaluated using six rumen-cannulated steers in a cross-over experimental design. RLA was induced by administration of sucrose, intraruminally. Twenty hours later when the animals developed an intense SMA, the steers were randomly distributed and treated intravenously either with 5l of 15 mMol/l sodium bicarbonate or L-lactate solution, infused throughout 4h. Blood samples were colleted throughout the infusion at zero, 1, 2, 3, 4, 6 and 8h, for blood gas analysis. After 1hour, both sodium bicarbonate and L-lactate solutions increased blood pH and corrected adequately the SMA. Blood
Robust H∞ Control of Neutral System with Time-Delay for Dynamic Positioning Ships
Directory of Open Access Journals (Sweden)
Dawei Zhao
2015-01-01
Full Text Available Due to the input time-delay existing in most thrust systems of the ships, the robust H∞ controller is designed for the ship dynamic positioning (DP system with time-delay. The input delay system is turned to a neutral time-delay system by a state-derivative control law. The less conservative result is derived for the neutral system with state-derivative feedback by the delay-decomposition approach and linear matrix inequality (LMI. Finally, the numerical simulations demonstrate the asymptotic stability and robustness of the controller and verify that the designed DP controller is effective in the varying environment disturbances of wind, waves, and ocean currents.
Generalized synchronization-based multiparameter estimation in modulated time-delayed systems
Ghosh, Dibakar; Bhattacharyya, Bidyut K.
2011-09-01
We propose a nonlinear active observer based generalized synchronization scheme for multiparameter estimation in time-delayed systems with periodic time delay. A sufficient condition for parameter estimation is derived using Krasovskii-Lyapunov theory. The suggested tool proves to be globally and asymptotically stable by means of Krasovskii-Lyapunov method. With this effective method, parameter identification and generalized synchronization of modulated time-delayed systems with all the system parameters unknown, can be achieved simultaneously. We restrict our study for multiple parameter estimation in modulated time-delayed systems with single state variable only. Theoretical proof and numerical simulation demonstrate the effectiveness and feasibility of the proposed technique. The block diagram of electronic circuit for multiple time delay system shows that the method is easily applicable in practical communication problems.
Effects of intrinsic stochasticity on delayed reaction-diffusion patterning systems
Woolley, Thomas E.
2012-05-22
Cellular gene expression is a complex process involving many steps, including the transcription of DNA and translation of mRNA; hence the synthesis of proteins requires a considerable amount of time, from ten minutes to several hours. Since diffusion-driven instability has been observed to be sensitive to perturbations in kinetic delays, the application of Turing patterning mechanisms to the problem of producing spatially heterogeneous differential gene expression has been questioned. In deterministic systems a small delay in the reactions can cause a large increase in the time it takes a system to pattern. Recently, it has been observed that in undelayed systems intrinsic stochasticity can cause pattern initiation to occur earlier than in the analogous deterministic simulations. Here we are interested in adding both stochasticity and delays to Turing systems in order to assess whether stochasticity can reduce the patterning time scale in delayed Turing systems. As analytical insights to this problem are difficult to attain and often limited in their use, we focus on stochastically simulating delayed systems. We consider four different Turing systems and two different forms of delay. Our results are mixed and lead to the conclusion that, although the sensitivity to delays in the Turing mechanism is not completely removed by the addition of intrinsic noise, the effects of the delays are clearly ameliorated in certain specific cases. © 2012 American Physical Society.
System delays in breast cancer | Dalwai | South African Journal of ...
African Journals Online (AJOL)
Data extraction included demographic data, time to diagnosis and initial staging using a standardised data sheet. Specific care steps were identified, namely delays to initial imaging with mammography, pathology confirmation, staging work-up and eventual referral to a centralised breast clinic. Results: A total of 45 patients ...
A simple time-delayed method to control chaotic systems
International Nuclear Information System (INIS)
Chen Maoyin; Zhou Donghua; Shang Yun
2004-01-01
Based on the adaptive iterative learning strategy, a simple time-delayed controller is proposed to stabilize unstable periodic orbits (UPOs) embedded in chaotic attractors. This controller includes two parts: one is a linear feedback part; the other is an adaptive iterative learning estimation part. Theoretical analysis and numerical simulation show the effectiveness of this controller
On Tuning PI Controllers for Integrating Plus Time Delay Systems
Directory of Open Access Journals (Sweden)
David Di Ruscio
2010-10-01
Full Text Available Some analytical results concerning PI controller tuning based on integrator plus time delay models are worked out and presented. A method for obtaining PI controller parameters, Kp=alpha/(k*tau, and, Ti=beta*tau, which ensures a given prescribed maximum time delay error, dtau_max, to time delay, tau, ratio parameter delta=dau_max/tau, is presented. The corner stone in this method, is a method product parameter, c=alpha*beta. Analytical relations between the PI controller parameters, Ti, and, Kp, and the time delay error parameter, delta, is presented, and we propose the setting, beta=c/a*(delta+1, and, alpha=a/(delta+1, which gives, Ti=c/a*(delta+1*tau, and Kp=a/((delta+1*k*tau, where the parameter, a, is constant in the method product parameter, c=alpha*beta. It also turns out that the integral time, Ti, is linear in, delta, and the proportional gain, Kp, inversely proportional to, delta+1. For the original Ziegler Nichols (ZN method this parameter is approximately, c=2.38, and the presented method may e.g., be used to obtain new modified ZN parameters with increased robustness margins, also documented in the paper.
Dynamics and control of a financial system with time-delayed feedbacks
International Nuclear Information System (INIS)
Chen, W.-C.
2008-01-01
Complex behaviors in a financial system with time-delayed feedbacks are discussed in this study via numerical modeling. The system shows complex dynamics such as periodic, quasi-periodic, and chaotic behaviors. Both period doubling and inverse period doubling routes were found in this system. This paper also shows that the attractor merging crisis is a fundamental feature of nonlinear financial systems with time-delayed feedbacks. Control of the deterministic chaos in the financial system can be realized using Pyragas feedbacks
Dynamics and control of a financial system with time-delayed feedbacks
Energy Technology Data Exchange (ETDEWEB)
Chen, W.-C. [Department of Information Management, Yuanpei University, No. 306, Yuanpei St., Hsinchu, Taiwan 30015 (China)], E-mail: wcc137@mail.yust.edu.tw
2008-08-15
Complex behaviors in a financial system with time-delayed feedbacks are discussed in this study via numerical modeling. The system shows complex dynamics such as periodic, quasi-periodic, and chaotic behaviors. Both period doubling and inverse period doubling routes were found in this system. This paper also shows that the attractor merging crisis is a fundamental feature of nonlinear financial systems with time-delayed feedbacks. Control of the deterministic chaos in the financial system can be realized using Pyragas feedbacks.
Stability Analysis for Fractional-Order Linear Singular Delay Differential Systems
Directory of Open Access Journals (Sweden)
Hai Zhang
2014-01-01
Full Text Available We investigate the delay-independently asymptotic stability of fractional-order linear singular delay differential systems. Based on the algebraic approach, the sufficient conditions are presented to ensure the asymptotic stability for any delay parameter. By applying the stability criteria, one can avoid solving the roots of transcendental equations. An example is also provided to illustrate the effectiveness and applicability of the theoretical results.
The solutions of second-order linear differential systems with constant delays
Diblík, Josef; Svoboda, Zdeněk
2017-07-01
The representations of solutions to initial problems for non-homogenous n-dimensional second-order differential equations with delays x″(t )-2 A x'(t -τ )+(A2+B2)x (t -2 τ )=f (t ) by means of special matrix delayed functions are derived. Square matrices A and B are commuting and τ > 0. Derived representations use what is called a delayed exponential of a matrix and results generalize some of known results previously derived for homogenous systems.
Directory of Open Access Journals (Sweden)
Mingzhu Song
2016-01-01
Full Text Available We address the problem of globally asymptotic stability for a class of stochastic nonlinear systems with time-varying delays. By the backstepping method and Lyapunov theory, we design a linear output feedback controller recursively based on the observable linearization for a class of stochastic nonlinear systems with time-varying delays to guarantee that the closed-loop system is globally asymptotically stable in probability. In particular, we extend the deterministic nonlinear system to stochastic nonlinear systems with time-varying delays. Finally, an example and its simulations are given to illustrate the theoretical results.
Dual-anticipating, dual and dual-lag synchronization in modulated time-delayed systems
International Nuclear Information System (INIS)
Ghosh, Dibakar; Chowdhury, A. Roy
2010-01-01
In this Letter, dual synchronization in modulated time delay system using delay feedback controller is proposed. Based on Lyapunov stability theory, we suggest a general method to achieve the dual-anticipating, dual, dual-lag synchronization of time-delayed chaotic systems and we find both its existing and sufficient stability conditions. Numerically it is shown that the dual synchronization is also possible when driving system contain two completely different systems. Effect of parameter mismatch on dual synchronization is also discussed. As an example, numerical simulations for the Mackey-Glass and Ikeda systems are conducted, which is in good agreement with the theoretical analysis.
International Nuclear Information System (INIS)
Frank, T.D.; Friedrich, R.; Beek, P.J.
2005-01-01
A data driven characterization of time-delayed stochastic systems is proposed in terms of linear delay differential equations and two drift parameters. It is shown how these parameters determine the states of such systems with respect to generalized phase diagrams. This approach allows for a comparison of systems with different parameters as exemplified for two motor control tasks: tracking and force production
DEFF Research Database (Denmark)
Terkelsen, Christian Juhl; Sørensen, Jacob Thorsted; Maeng, Michael
2010-01-01
Timely reperfusion therapy is recommended for patients with ST-segment elevation myocardial infarction (STEMI), and door-to-balloon delay has been proposed as a performance measure in triaging patients for primary percutaneous coronary intervention (PCI). However, focusing on the time from first...... contact with the health care system to the initiation of reperfusion therapy (system delay) may be more relevant, because it constitutes the total time to reperfusion modifiable by the health care system. No previous studies have focused on the association between system delay and outcome in patients...
Average Delay Guarantee in Server Systems Using Admission Control
Malrait, Luc; Marchand, Nicolas; Bouchenak, Sara
2009-01-01
International audience; Although server technology provides a mean to support a wide range of online services and applications, their ad-hoc conguration poses signicant challenges to the perfor- mance, availability and economical costs of applications. One of the main concerns is that under a heavy load, the delay introduced by a server in the transaction process may grow unbounded. This paper precisely addresses this issue. First, we present the design of a server model as a non-linear conti...
Lyapunov exponents for complex systems with delayed feedback
Dailyudenko, V F
2003-01-01
Analytical and numerical analysis is implemented for two methods of Lyapunov exponents calculation. The first is based on successive multiplication of functional matrixes corresponding to discrete transformations and calculation of eigenvalues for the obtained matrix. The second approach is based on successive orthogonalization of multiplied matrixes using QR-decomposition. The analytical model for describing functional maps of discrete iterations derived from delay differential equation is proposed, which implements representation of the product matrix through matrixes of canonical form that reduces calculation complexity.
Periodic and chaotic oscillations in a tumor and immune system interaction model with three delays
International Nuclear Information System (INIS)
Bi, Ping; Ruan, Shigui; Zhang, Xinan
2014-01-01
In this paper, a tumor and immune system interaction model consisted of two differential equations with three time delays is considered in which the delays describe the proliferation of tumor cells, the process of effector cells growth stimulated by tumor cells, and the differentiation of immune effector cells, respectively. Conditions for the asymptotic stability of equilibria and existence of Hopf bifurcations are obtained by analyzing the roots of a second degree exponential polynomial characteristic equation with delay dependent coefficients. It is shown that the positive equilibrium is asymptotically stable if all three delays are less than their corresponding critical values and Hopf bifurcations occur if any one of these delays passes through its critical value. Numerical simulations are carried out to illustrate the rich dynamical behavior of the model with different delay values including the existence of regular and irregular long periodic oscillations
PI Controller Design for Time Delay Systems Using an Extension of the Hermite-Biehler Theorem
Elmadssia, Sami; Saadaoui, Karim; Benrejeb, Mohamed
2013-01-01
We consider stabilizing first-order systems with time delay. The set of all stabilizing proportional-integral PI controllers are determined using an extension of the Hermite-Biehler theorem. The time delay is approximated by a second-order Padé approximation. For uncertain plants, with interval type uncertainty, robust stabilizing PI controllers are determined.
Playout delay of TV signals: measurement system design, validation and results
Kooij, Wouter J.; Stokking, Hans M.; van Brandenburg, Ray; de Boer, Pieter-Tjerk
Due to new interactive TV services, synchronizing the playout of content on different TVs is becoming important. To synchronize, knowledge of delay differences is needed. In this study, a measurement system is developed to gain insight into the magnitude of delay differences of different TV setups
Playout Delay of TV Signals: Measurement System Design, Validation and Results
Kooij, W.J.; Stokking, H.M.; Brandenburg, R. van; Boer, P.T. de
2014-01-01
Due to new interactive TV services, synchronizing the playout of content on different TVs is becoming important. To synchronize, knowledge of delay differences is needed. In this study, a measurement system is developed to gain insight into the magnitude of delay differences of different TV setups
Parameter estimation of a delay dynamical system using synchronization in presence of noise
International Nuclear Information System (INIS)
Rakshit, Biswambhar; Chowdhury, A. Roy; Saha, Papri
2007-01-01
A method of parameter estimation of a time delay chaotic system through synchronization is discussed. It is assumed that the observed data can always be effected with some white Gaussian noise. A least square approach is used to derive a system of differential equations which governs the temporal evolution of the parameters. These system of equations together with the coupled delay dynamical systems, when integrated, leads to asymptotic convergence to the value of the parameter along with synchronization of the two system variables. This method is quite effective for estimating the delay time which is an important characteristic feature of a delay dynamical system. The procedure is quite robust in the presence of noise
Directory of Open Access Journals (Sweden)
Ashfaque Ahmed Hashmani
2011-04-01
Full Text Available A long time delay due to the transmission and processing of remote signal may degrade stability of power system. This paper discusses the design of H? -based local decentralized delayed-input PSS (Power System Stabilizer controllers for a separate better damping of inter-area modes. The controllers use selected suitable remote signals from whole system as supplementary inputs. The local and remote input signals, used by the controller, are the ones in which the assigned single inter-area mode is most observable. The controller is located at a generator which is most effective in controlling the assigned mode. The controller, designed for a particular single interarea mode, also works mainly in the natural frequency of the assigned mode. Pade approximation approach is used to model time delay. The time delay model is then merged into delay-free power system model to obtain the delayed-input power system model. The controllers are then redesigned for the delayed-input system.
Fission delay and GDR γ-ray from very heavy system
International Nuclear Information System (INIS)
Shen, W.Q.; Wang, J.S.; Ye, W.; Cai, Y.H.; Ma, Y.G.; Feng, J.; Fang, D.Q.; Cai, X.Z.
1999-01-01
The study of the fission delay in reaction of 84 Kr+ 27 Al at 10.6 Mev/u and the systematics of fission delay are described. Authors also discussed the possibility to study the GDR γ rays emitted from the super-heavy compound system on the basis of the strong increasing of the GDR γ rays duo to the fission delay. The calculation results of the GDR γ rays from the super-heavy compound system via microscopic semi-classical Vlasov equation and the experimental data analysis for searching the super-heavy compound system via GDR γ were given
Numerical test for hyperbolicity in chaotic systems with multiple time delays
Kuptsov, Pavel V.; Kuznetsov, Sergey P.
2018-03-01
We develop an extension of the fast method of angles for hyperbolicity verification in chaotic systems with an arbitrary number of time-delay feedback loops. The adopted method is based on the theory of covariant Lyapunov vectors and provides an efficient algorithm applicable for systems with high-dimensional phase space. Three particular examples of time-delay systems are analyzed and in all cases the expected hyperbolicity is confirmed.
Mittag-Leffler Stability Theorem for Fractional Nonlinear Systems with Delay
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S. J. Sadati
2010-01-01
Full Text Available Fractional calculus started to play an important role for analysis of the evolution of the nonlinear dynamical systems which are important in various branches of science and engineering. In this line of taught in this paper we studied the stability of fractional order nonlinear time-delay systems for Caputo's derivative, and we proved two theorems for Mittag-Leffler stability of the fractional nonlinear time delay systems.
Cracking chaos-based encryption systems ruled by nonlinear time delay differential equations
International Nuclear Information System (INIS)
Udaltsov, Vladimir S.; Goedgebuer, Jean-Pierre; Larger, Laurent; Cuenot, Jean-Baptiste; Levy, Pascal; Rhodes, William T.
2003-01-01
We report that signal encoding with high-dimensional chaos produced by delayed feedback systems with a strong nonlinearity can be broken. We describe the procedure and illustrate the method with chaotic waveforms obtained from a strongly nonlinear optical system that we used previously to demonstrate signal encryption/decryption with chaos in wavelength. The method can be extended to any systems ruled by nonlinear time-delayed differential equations
Bifurcations of Tumor-Immune Competition Systems with Delay
Directory of Open Access Journals (Sweden)
Ping Bi
2014-01-01
Full Text Available A tumor-immune competition model with delay is considered, which consists of two-dimensional nonlinear differential equation. The conditions for the linear stability of the equilibria are obtained by analyzing the distribution of eigenvalues. General formulas for the direction, period, and stability of the bifurcated periodic solutions are given for codimension one and codimension two bifurcations, including Hopf bifurcation, steady-state bifurcation, and B-T bifurcation. Numerical examples and simulations are given to illustrate the bifurcations analysis and obtained results.
$H^\\infty$ control of systems with multiple I/O delays via decomposition to adobe problems
Meinsma, Gjerrit; Mirkin, Leonid
In this paper, the standard (four-block) $H^\\infty$ control problem for systems with multiple input-output delays in the feedback loop is studied. The central idea is to see the multiple delay operator as a special series connection of elementary delay operators, called the adobe delay operators.
A note on chaotic synchronization of time-delay secure communication systems
International Nuclear Information System (INIS)
Li Demin; Wang Zidong; Zhou Jie; Fang Jianan; Ni Jinjin
2008-01-01
In a real world, the signals are often transmitted through a hostile environment, and therefore the secure communication system has attracted considerable research interests. In this paper, the observer-based chaotic synchronization problem is studied for a class of time-delay secure communication systems. The system under consideration is subject to delayed state and nonlinear disturbances. The time-delay is allowed to be time-varying, and the nonlinearities are assumed to satisfy global Lipschitz conditions. The problem addressed is the design of a synchronization scheme such that, for the admissible time-delay as well as nonlinear disturbances, the response system can globally synchronize the driving system. An effective algebraic matrix inequality approach is developed to solve the chaotic synchronization problem. A numerical example is presented to show the effectiveness and efficiency of the proposed secure communication scheme
Delay-Dependent Robust Stabilization for Nonlinear Large Systems via Decentralized Fuzzy Control
Directory of Open Access Journals (Sweden)
Chun-xia Dou
2011-01-01
Full Text Available A delay-dependent robust fuzzy control approach is developed for a class of nonlinear uncertain interconnected time delay large systems in this paper. First, an equivalent T–S fuzzy model is extended in order to accurately represent nonlinear dynamics of the large system. Then, a decentralized state feedback robust controller is proposed to guarantee system stabilization with a prescribed H∞ disturbance attenuation level. Furthermore, taking into account the time delays in large system, based on a less conservative delay-dependent Lyapunov function approach combining with linear matrix inequalities (LMI technique, some sufficient conditions for the existence of H∞ robust controller are presented in terms of LMI dependent on the upper bound of time delays. The upper bound of time-delay and minimized H∞ performance index can be obtained by using convex optimization such that the system can be stabilized and for all time delays whose sizes are not larger than the bound. Finally, the effectiveness of the proposed controller is demonstrated through simulation example.
The effects of perceived USB-delay for sensor and embedded system development.
Du, J; Kade, D; Gerdtman, C; Ozcan, O; Linden, M
2016-08-01
Perceiving delay in computer input devices is a problem which gets even more eminent when being used in healthcare applications and/or in small, embedded systems. Therefore, the amount of delay found as acceptable when using computer input devices was investigated in this paper. A device was developed to perform a benchmark test for the perception of delay. The delay can be set from 0 to 999 milliseconds (ms) between a receiving computer and an available USB-device. The USB-device can be a mouse, a keyboard or some other type of USB-connected input device. Feedback from performed user tests with 36 people form the basis for the determination of time limitations for the USB data processing in microprocessors and embedded systems without users' noticing the delay. For this paper, tests were performed with a personal computer and a common computer mouse, testing the perception of delays between 0 and 500 ms. The results of our user tests show that perceived delays up to 150 ms were acceptable and delays larger than 300 ms were not acceptable at all.
Constructing Hopf bifurcation lines for the stability of nonlinear systems with two time delays
Nguimdo, Romain Modeste
2018-03-01
Although the plethora real-life systems modeled by nonlinear systems with two independent time delays, the algebraic expressions for determining the stability of their fixed points remain the Achilles' heel. Typically, the approach for studying the stability of delay systems consists in finding the bifurcation lines separating the stable and unstable parameter regions. This work deals with the parametric construction of algebraic expressions and their use for the determination of the stability boundaries of fixed points in nonlinear systems with two independent time delays. In particular, we concentrate on the cases for which the stability of the fixed points can be ascertained from a characteristic equation corresponding to that of scalar two-delay differential equations, one-component dual-delay feedback, or nonscalar differential equations with two delays for which the characteristic equation for the stability analysis can be reduced to that of a scalar case. Then, we apply our obtained algebraic expressions to identify either the parameter regions of stable microwaves generated by dual-delay optoelectronic oscillators or the regions of amplitude death in identical coupled oscillators.
Identification of fractional-order systems with time delays using block pulse functions
Tang, Yinggan; Li, Ning; Liu, Minmin; Lu, Yao; Wang, Weiwei
2017-07-01
In this paper, a novel method based on block pulse functions is proposed to identify continuous-time fractional-order systems with time delays. First, the operational matrices of block pulse functions for fractional integral operator and time delay operator are derived. Then, these operational matrices are applied to convert the continuous-time fractional-order systems with time delays to an algebraic equation. Finally, the system's parameters along with the differentiation orders and the time delays are all simultaneously estimated through minimizing a quadric error function. The proposed method reduces the computation complexity of the identification process, and also it does not require the system's differentiation orders to be commensurate. The effectiveness of the proposed method are demonstrated by several numerical examples.
Instability in time-delayed switched systems induced by fast and random switching
Guo, Yao; Lin, Wei; Chen, Yuming; Wu, Jianhong
2017-07-01
In this paper, we consider a switched system comprising finitely or infinitely many subsystems described by linear time-delayed differential equations and a rule that orchestrates the system switching randomly among these subsystems, where the switching times are also randomly chosen. We first construct a counterintuitive example where even though all the time-delayed subsystems are exponentially stable, the behaviors of the randomly switched system change from stable dynamics to unstable dynamics with a decrease of the dwell time. Then by using the theories of stochastic processes and delay differential equations, we present a general result on when this fast and random switching induced instability should occur and we extend this to the case of nonlinear time-delayed switched systems as well.
Szalai, Róbert; Orosz, Gábor
2013-10-01
Delay-coupled networks are investigated with nonidentical delay times and the effects of such heterogeneity on the emergent dynamics of complex systems are characterized. A simple decomposition method is presented that decouples the dynamics of the network into node-size modal equations in the vicinity of equilibria. The resulting independent components contain distributed delays that map the spatiotemporal complexity of the system to the time domain. We demonstrate that this approach can be used to reveal physical phenomena in heterogenous vehicular traffic when vehicles are linked via vehicle-to-vehicle communication.
Dynamical Consensus Algorithm for Second-Order Multi-Agent Systems Subjected to Communication Delay
International Nuclear Information System (INIS)
Liu Chenglin; Liu Fei
2013-01-01
To solve the dynamical consensus problem of second-order multi-agent systems with communication delay, delay-dependent compensations are added into the normal asynchronously-coupled consensus algorithm so as to make the agents achieve a dynamical consensus. Based on frequency-domain analysis, sufficient conditions are gained for second-order multi-agent systems with communication delay under leaderless and leader-following consensus algorithms respectively. Simulation illustrates the correctness of the results. (interdisciplinary physics and related areas of science and technology)
International Nuclear Information System (INIS)
Feng Cun-Fang; Wang Ying-Hai
2011-01-01
Projective synchronization in modulated time-delayed systems is studied by applying an active control method. Based on the Lyapunov asymptotical stability theorem, the controller and sufficient condition for projective synchronization are calculated analytically. We give a general method with which we can achieve projective synchronization in modulated time-delayed chaotic systems. This method allows us to adjust the desired scaling factor arbitrarily. The effectiveness of our method is confirmed by using the famous delay-differential equations related to optical bistable or hybrid optical bistable devices. Numerical simulations fully support the analytical approach. (general)
Geometric methods of global attraction in systems of delay differential equations
El-Morshedy, Hassan A.; Ruiz-Herrera, Alfonso
2017-11-01
In this paper we deduce criteria of global attraction in systems of delay differential equations. Our methodology is new and consists in "dominating" the nonlinear terms of the system by a scalar function and then studying some dynamical properties of that function. One of the crucial benefits of our approach is that we obtain delay-dependent results of global attraction that cover the best delay-independent conditions. We apply our results in a gene regulatory model and the classical Nicholson's blowfly equation with patch structure.
Lyapunov matrices approach to the parametric optimization of time-delay systems
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Duda Józef
2015-09-01
Full Text Available In the paper a Lyapunov matrices approach to the parametric optimization problem of time-delay systems with a P-controller is presented. The value of integral quadratic performance index of quality is equal to the value of Lyapunov functional for the initial function of the time-delay system. The Lyapunov functional is determined by means of the Lyapunov matrix
Xiao, Tiejun
2016-11-01
In this paper, stochastic thermodynamics of delayed bistable Langevin systems near coherence resonance is discussed. We calculate the heat dissipation rate and the information flow of a delayed bistable Langevin system under various noise intensities. Both the heat dissipation rate and the information flow are found to be bell-shaped functions of the noise intensity, which implies that coherence resonance manifests itself in the thermodynamic properties.
Rebenda, Josef; Šmarda, Zdeněk
2017-07-01
In the paper, we propose a correct and efficient semi-analytical approach to solve initial value problem for systems of functional differential equations with delay. The idea is to combine the method of steps and differential transformation method (DTM). In the latter, formulas for proportional arguments and nonlinear terms are used. An example of using this technique for a system with constant and proportional delays is presented.
Stability result of the Timoshenko system with delay and boundary feedback
Said-Houari, Belkacem
2012-01-06
Our interest in this paper is to analyse the asymptotic behaviour of a Timoshenko beam system together with two boundary controls, with delay terms in the first and second equation. Assuming the weights of the delay are small enough, we show that the system is well-posed using the semigroup theory. Furthermore, we introduce a Lyapunov functional that gives the exponential decay of the total energy. © 2012 The author.
Numerical Solution of Piecewise Constant Delay Systems Based on a Hybrid Framework
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H. R. Marzban
2016-01-01
Full Text Available An efficient numerical scheme for solving delay differential equations with a piecewise constant delay function is developed in this paper. The proposed approach is based on a hybrid of block-pulse functions and Taylor’s polynomials. The operational matrix of delay corresponding to the proposed hybrid functions is introduced. The sparsity of this matrix significantly reduces the computation time and memory requirement. The operational matrices of integration, delay, and product are employed to transform the problem under consideration into a system of algebraic equations. It is shown that the developed approach is also applicable to a special class of nonlinear piecewise constant delay differential equations. Several numerical experiments are examined to verify the validity and applicability of the presented technique.
Stochastic resonance in a time-delayed asymmetric bistable system with mixed periodic signal
International Nuclear Information System (INIS)
Yong-Feng, Guo; Wei, Xu; Liang, Wang
2010-01-01
This paper studies the phenomenon of stochastic resonance in an asymmetric bistable system with time-delayed feedback and mixed periodic signal by using the theory of signal-to-noise ratio in the adiabatic limit. A general approximate Fokker–Planck equation and the expression of the signal-to-noise ratio are derived through the small time delay approximation at both fundamental harmonics and mixed harmonics. The effects of the additive noise intensity Q, multiplicative noise intensity D, static asymmetry r and delay time τ on the signal-to-noise ratio are discussed. It is found that the higher mixed harmonics and the static asymmetry r can restrain stochastic resonance, and the delay time τ can enhance stochastic resonance. Moreover, the longer the delay time τ is, the larger the additive noise intensity Q and the multiplicative noise intensity D are, when the stochastic resonance appears. (general)
Yao, Chenggui; Zhan, Meng; Shuai, Jianwei; Ma, Jun; Kurths, Jürgen
2017-12-01
It has been generally believed that both time delay and network structure could play a crucial role in determining collective dynamical behaviors in complex systems. In this work, we study the influence of coupling strength, time delay, and network topology on synchronization behavior in delay-coupled networks of chaotic pendulums. Interestingly, we find that the threshold value of the coupling strength for complete synchronization in such networks strongly depends on the time delay in the coupling, but appears to be insensitive to the network structure. This lack of sensitivity was numerically tested in several typical regular networks, such as different locally and globally coupled ones as well as in several complex networks, such as small-world and scale-free networks. Furthermore, we find that the emergence of a synchronous periodic state induced by time delay is of key importance for the complete synchronization.
Bifurcation Regulations Governed by Delay Self-Control Feedback in a Stochastic Birhythmic System
Ma, Zhidan; Ning, Lijuan
2017-12-01
We aim to investigate bifurcation behaviors in a stochastic birhythmic van der Pol (BVDP) system subjected to delay self-control feedback. First, the harmonic approximation is adopted to drive the delay self-control feedback to state variables without delay. Then, Fokker-Planck-Kolmogorov (FPK) equation and stationary probability density function (SPDF) for amplitude are obtained by applying stochastic averaging method. Finally, dynamical scenarios of the change of delay self-control feedback as well as noise that markedly influence bifurcation performance are observed. It is found that: the big feedback strength and delay will suppress the large amplitude limit cycle (LC) while the relatively big noise strength facilitates the large amplitude LC, which imply the proposed regulation strategies are feasible. Interestingly enough, the inner LC is never destroyed due to noise. Furthermore, the validity of analytical results was verified by Monte Carlo simulation of the dynamics.
A frequency-domain method for solving linear time delay systems with constant coefficients
Jin, Mengshi; Chen, Wei; Song, Hanwen; Xu, Jian
2018-03-01
In an active control system, time delay will occur due to processes such as signal acquisition and transmission, calculation, and actuation. Time delay systems are usually described by delay differential equations (DDEs). Since it is hard to obtain an analytical solution to a DDE, numerical solution is of necessity. This paper presents a frequency-domain method that uses a truncated transfer function to solve a class of DDEs. The theoretical transfer function is the sum of infinite items expressed in terms of poles and residues. The basic idea is to select the dominant poles and residues to truncate the transfer function, thus ensuring the validity of the solution while improving the efficiency of calculation. Meanwhile, the guideline of selecting these poles and residues is provided. Numerical simulations of both stable and unstable delayed systems are given to verify the proposed method, and the results are presented and analysed in detail.
An Efficient Offloading Scheme For MEC System Considering Delay and Energy Consumption
Sun, Yanhua; Hao, Zhe; Zhang, Yanhua
2018-01-01
With the increasing numbers of mobile devices, mobile edge computing (MEC) which provides cloud computing capabilities proximate to mobile devices in 5G networks has been envisioned as a promising paradigm to enhance users experience. In this paper, we investigate a joint consideration of delay and energy consumption offloading scheme (JCDE) for MEC system in 5G heterogeneous networks. An optimization is formulated to minimize the delay as well as energy consumption of the offloading system, which the delay and energy consumption of transmitting and calculating tasks are taken into account. We adopt an iterative greedy algorithm to solve the optimization problem. Furthermore, simulations were carried out to validate the utility and effectiveness of our proposed scheme. The effect of parameter variations on the system is analysed as well. Numerical results demonstrate delay and energy efficiency promotion of our proposed scheme compared with another paper’s scheme.
Stability and Relative Stability of Linear Systems with Many Constant Time Delays. Ph.D. Thesis
Barker, Larry Keith
1976-01-01
A method of determining the stability of linear systems with many constant time delays is developed. This technique, an extension of the tau-decomposition method, is used to examine not only the stability but also the relative stability of retarded systems with many delays and a class of neutral equations with one delay. Analytical equations are derived for partitioning the delay space of a retarded system with two time delays. The stability of the system in each of the regions defined by the partitioning curves in the parameter plane is determined using the extended tau-decomposition method. In addition, relative stability boundaries are defined using the extended tau-decompositon method in association with parameter plane techniques. Several applications of the extended tau-decomposition method are presented and compared with stability results obtained from other analyses. In all cases the results obtained using the method outlined herein coincide with and extend those of previous investigations. The extended tau-decomposition method applied to systems with time delays requires less computational effort and yields more complete stability analyses than previous techniques.
Energy Technology Data Exchange (ETDEWEB)
Patanarapeelert, K. [Faculty of Science, Department of Mathematics, Mahidol University, Rama VI Road, Bangkok 10400 (Thailand); Frank, T.D. [Institute for Theoretical Physics, University of Muenster, Wilhelm-Klemm-Str. 9, 48149 Muenster (Germany)]. E-mail: tdfrank@uni-muenster.de; Friedrich, R. [Institute for Theoretical Physics, University of Muenster, Wilhelm-Klemm-Str. 9, 48149 Muenster (Germany); Beek, P.J. [Faculty of Human Movement Sciences and Institute for Fundamental and Clinical Human Movement Sciences, Vrije Universiteit, Van der Boechorststraat 9, 1081 BT Amsterdam (Netherlands); Tang, I.M. [Faculty of Science, Department of Physics, Mahidol University, Rama VI Road, Bangkok 10400 (Thailand)
2006-12-18
A method is proposed to identify deterministic components of stable and unstable time-delayed systems subjected to noise sources with finite correlation times (colored noise). Both neutral and retarded delay systems are considered. For vanishing correlation times it is shown how to determine their noise amplitudes by minimizing appropriately defined Kullback measures. The method is illustrated by applying it to simulated data from stochastic time-delayed systems representing delay-induced bifurcations, postural sway and ship rolling.
Lanot, A; Henri, P; Nowoczyn, M; Read, M H; Maucorps, C; Sassier, M; Lobbedez, T
2018-02-01
The most common causes of high anion gap metabolic acidosis (HAGMA) are lactic acidosis, ketoacidosis, and intoxications. Nevertheless, clinicians can be faced with unexplained HAGMA, with a need to look for less common etiologies. We describe a case of 5-oxoproline (pyroglutamate) acidosis due to chronic acetaminophen ingestion at therapeutic dose in a 79-year-old inpatient. The pathophysiology of this condition is detailed, with abnormalities in the gamma-glutamyl cycle due to acetaminophen ingestion and severe chronic morbidities, resulting in glutathione and cysteine deficiency and then accumulation of 5-oxoproline. In HAGMA, when usual causes have been excluded, 5-oxoproline acidosis should be suspected in patients with chronic morbidities and acetaminophen ingestion. This diagnosis should be kept in mind because it generally resolves quickly with cessation of acetaminophen and administration of intravenous fluids. Copyright © 2017 Société Nationale Française de Médecine Interne (SNFMI). Published by Elsevier SAS. All rights reserved.
Type B lactic acidosis in solid malignancies
Groot, R. de; Sprenger, R.A.; Imholz, A.L.; Gerding, M.N.
2011-01-01
BACKGROUND: Type B lactic acidosis is thought to be a rare complication of malignancy. It was first described in patients with acute leukaemia by Field et al. in 1963. Since then, it has been observed more often, in particular in haematological malignancies and rarely in solid tumours. METHODS:
NRTI-ASSOCIATED HYPERLACTATAEMIA AND LACTIC ACIDOSIS
African Journals Online (AJOL)
Hopkins HIVReport, 2002. NRTI-ASSOCIATED HYPERLACTATAEMIA. AND LACTIC ACIDOSIS. BACKGROUND. Since the advent of highly active antiretroviral therapy. (HAARl]. the prognosis of patients with HIV infection has improved dramatically - as evidenced by the decrease in mortality and morbidity rates.' However ...
Development of an acoustic steam generator leak detection system using delay-and-sum beamformer
International Nuclear Information System (INIS)
Chikazawa, Yoshitaka
2009-01-01
A new acoustic steam generator leak detection system using delay-and-sum beamformer is proposed. The major advantage of the delay-and-sum beamformer is it could provide information of acoustic source direction. An acoustic source of a sodium-water reaction is supposed to be localized while the background noise of the steam generator operation is uniformly distributed in the steam generator tube region. Therefore the delay-and-sum beamformer could distinguish the acoustic source of the sodium-water reaction from steam generator background noise. In this paper, results from numerical analyses are provided to show fundamental feasibility of the new method. (author)
Design and Performance of Cyclic Delay Diversity in UWB-OFDM Systems
Directory of Open Access Journals (Sweden)
Tarasak Poramate
2008-01-01
Full Text Available This paper addresses cyclic delay diversity (CDD in an ultra-wideband communication system based on orthogonal frequency division multiplexing (OFDM technique. Symbol error rate and outage probability have been derived. It is shown that with only two transmit antennas, CDD effectively improves SER performance and reduces outage probability significantly especially when the channel delay spread is short. Both simulation and analytical results agree well in all considered cases. The selection of delay times for CDD is also addressed for some special cases.
International Nuclear Information System (INIS)
Jin, Maolin; Chang, Pyung Hun
2009-01-01
This work presents two simple and robust techniques based on time delay estimation for the respective control and synchronization of chaos systems. First, one of these techniques is applied to the control of a chaotic Lorenz system with both matched and mismatched uncertainties. The nonlinearities in the Lorenz system is cancelled by time delay estimation and desired error dynamics is inserted. Second, the other technique is applied to the synchronization of the Lue system and the Lorenz system with uncertainties. The synchronization input consists of three elements that have transparent and clear meanings. Since time delay estimation enables a very effective and efficient cancellation of disturbances and nonlinearities, the techniques turn out to be simple and robust. Numerical simulation results show fast, accurate and robust performance of the proposed techniques, thereby demonstrating their effectiveness for the control and synchronization of Lorenz systems.
A normalized PID controller in networked control systems with varying time delays.
Tran, Hoang-Dung; Guan, Zhi-Hong; Dang, Xuan-Kien; Cheng, Xin-Ming; Yuan, Fu-Shun
2013-09-01
It requires not only simplicity and flexibility but also high specified stability and robustness of system to design a PI/PID controller in such complicated networked control systems (NCSs) with delays. By gain and phase margins approach, this paper proposes a novel normalized PI/PID controller for NCSs based on analyzing the stability and robustness of system under the effect of network-induced delays. Specifically, We take into account the total measured network delays to formulate the gain and phase margins of the closed-loop system in the form of a set of equations. With pre-specified values of gain and phase margins, this set of equations is then solved for calculating the closed forms of control parameters which enable us to propose the normalized PI/PID controller simultaneously satisfying the following two requirements: (1) simplicity without re-solving the optimization problem for a new process, (2) high flexibility to cope with large scale of random delays and deal with many different processes in different conditions of network. Furthermore, in our method, the upper bound of random delay can be estimated to indicate the operating domain of proposed PI/PID controller. Finally, simulation results are shown to demonstrate the advantages of our proposed controller in many situations of network-induced delays. Copyright © 2013 ISA. Published by Elsevier Ltd. All rights reserved.
H∞ output-feedback fuzzy proportional-integral control of fully delayed input/output systems.
Chiu, Chian-Song; Chiang, Tung-Sheng
2017-01-01
This paper presents the output-feedback fuzzy proportional-integral (PI) controller design for uncertain nonlinear systems with both fully delayed input and output. Based on the Takagi-Sugeno (T-S) fuzzy model representation, the output-feedback PI control is realized via parallel distributed PI compensation and novel LMI gain design. Although the T-S fuzzy PI controller is simple, asymptotic output regulation is assured to overcome the effect of uncertainty, state delay, and full input/output delays. When considering disturbance and measurement noise, the control performance is achieved by robust gain design. Furthermore, state observers and bilinear matrix inequality conditions are removed in this paper. Finally, time-delay Chua׳s circuit system and a continuous-time stirred tank reactor are taken as applications to show the expected performance. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.
Delay dynamical systems and applications to nonlinear machine-tool chatter
International Nuclear Information System (INIS)
Fofana, M.S.
2003-01-01
The stability behaviour of machine chatter that exhibits Hopf and degenerate bifurcations has been examined without the assumption of small delays between successive cuts. Delay dynamical system theory leading to the reduction of the infinite-dimensional character of the governing delay differential equations (DDEs) to a finite-dimensional set of ordinary differential equations have been employed. The essential mathematical arguments for these systems in the context of retarded DDEs are summarized. Then the application of these arguments in the stability study of machine-tool chatter with multiple time delays is presented. Explicit analytical expressions ensuring stable and unstable machining when perturbations are periodic, stochastic and nonlinear have been derived using the integral averaging method and Lyapunov exponents
Directory of Open Access Journals (Sweden)
Saïda Bedoui
2013-01-01
Full Text Available This paper addresses the problem of simultaneous identification of linear discrete time delay multivariable systems. This problem involves both the estimation of the time delays and the dynamic parameters matrices. In fact, we suggest a new formulation of this problem allowing defining the time delay and the dynamic parameters in the same estimated vector and building the corresponding observation vector. Then, we use this formulation to propose a new method to identify the time delays and the parameters of these systems using the least square approach. Convergence conditions and statistics properties of the proposed method are also developed. Simulation results are presented to illustrate the performance of the proposed method. An application of the developed approach to compact disc player arm is also suggested in order to validate simulation results.
Topiramate and metabolic acidosis in pediatric epilepsy.
Takeoka, M; Holmes, G L; Thiele, E; Bourgeois, B F; Helmers, S L; Duffy, F H; Riviello, J J
2001-03-01
Topiramate (TPM) has been widely used as an adjunctive therapy for treating epilepsy. TPM is reported to have multiple mechanisms of action, including inhibition of carbonic anhydrase, which may result in metabolic acidosis from decreased serum bicarbonate (HCO3-). Clinical data from 30 children who received TPM as adjunctive therapy for medically refractory epilepsy were reviewed at Children's Hospital, Boston. Serum HCO3- levels were assessed before, during, and after discontinuing TPM (n = 9). When multiple data were available, mean values were used for analysis. Of the 30 patients, 21 had a >10% decrease in HCO3- levels. The mean decrease in HCO3- among the 21 patients was 4.7 mEq/L, and maximum was 10 mEq/L. No clinical symptoms occurred, and HCO3- supplement was not needed, except for one patient who developed tachypnea from worsened acidosis after prolonged status epilepticus during a suspected viral illness. Among the 21 patients, TPM was discontinued in seven children because of a lack of efficacy, and in two because of anorexia. After discontinuing TPM, the serum HCO3- returned to the previous level before starting TPM in all nine. Decreased HCO3- levels occurred in the majority of patients reviewed, usually only to a small to moderate extent, but by 8 and 10 mEq/L in two cases. In patients at risk for acidosis, the decrease in HCO3- may cause significant consequences, such as severe acidosis or renal calculi. Monitoring HCO3- levels before and during TPM therapy may be indicated, especially with conditions that predispose to acidosis.
On a new time-delayed feedback control of chaotic systems
International Nuclear Information System (INIS)
Tian Lixin; Xu Jun; Sun Mei; Li Xiuming
2009-01-01
In this paper, using the idea of the successive dislocation feedback method, a new time-delayed feedback control method called the successive dislocation time-delayed feedback control (SDTDFC) is designed. Firstly, the idea of SDTDFC is introduced. Then some analytic sufficient conditions of the chaos control from the SDTDFC approach are derived for stabilization. Finally, some established results are further clarified via a case study of the Lorenz system with the numerical simulations.
Chen, Bo; Ho, Daniel W. C.; Hu, Guoqiang; Yu, Li
2018-01-01
This paper studies the distributed dimensionality reduction fusion estimation problem with communication delays for a class of cyber-physical systems (CPSs). The raw measurements are preprocessed in each sink node to obtain the local optimal estimate (LOE) of a CPS, and the compressed LOE under dimensionality reduction encounters with communication delays during the transmission. Under this case, a mathematical model with compensation strategy is proposed to characterize the dimensionality re...
Bifurcation in Z2-symmetry quadratic polynomial systems with delay
International Nuclear Information System (INIS)
Zhang Chunrui; Zheng Baodong
2009-01-01
Z 2 -symmetry systems are considered. Firstly the general forms of Z 2 -symmetry quadratic polynomial system are given, and then a three-dimensional Z 2 equivariant system is considered, which describes the relations of two predator species for a single prey species. Finally, the explicit formulas for determining the Fold and Hopf bifurcations are obtained by using the normal form theory and center manifold argument.
Consensus of heterogeneous multi-agent systems based on sampled data with a small sampling delay
International Nuclear Information System (INIS)
Wang Na; Wu Zhi-Hai; Peng Li
2014-01-01
In this paper, consensus problems of heterogeneous multi-agent systems based on sampled data with a small sampling delay are considered. First, a consensus protocol based on sampled data with a small sampling delay for heterogeneous multi-agent systems is proposed. Then, the algebra graph theory, the matrix method, the stability theory of linear systems, and some other techniques are employed to derive the necessary and sufficient conditions guaranteeing heterogeneous multi-agent systems to asymptotically achieve the stationary consensus. Finally, simulations are performed to demonstrate the correctness of the theoretical results. (interdisciplinary physics and related areas of science and technology)
Khazaee, Mostafa; Markazi, Amir H D; Omidi, Ehsan
2015-11-01
In this paper, a new Adaptive Fuzzy Predictive Sliding Mode Control (AFP-SMC) is presented for nonlinear systems with uncertain dynamics and unknown input delay. The control unit consists of a fuzzy inference system to approximate the ideal linearization control, together with a switching strategy to compensate for the estimation errors. Also, an adaptive fuzzy predictor is used to estimate the future values of the system states to compensate for the time delay. The adaptation laws are used to tune the controller and predictor parameters, which guarantee the stability based on a Lyapunov-Krasovskii functional. To evaluate the method effectiveness, the simulation and experiment on an overhead crane system are presented. According to the obtained results, AFP-SMC can effectively control the uncertain nonlinear systems, subject to input delays of known bound. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.
Distributed Consensus of Stochastic Delayed Multi-agent Systems Under Asynchronous Switching.
Wu, Xiaotai; Tang, Yang; Cao, Jinde; Zhang, Wenbing
2016-08-01
In this paper, the distributed exponential consensus of stochastic delayed multi-agent systems with nonlinear dynamics is investigated under asynchronous switching. The asynchronous switching considered here is to account for the time of identifying the active modes of multi-agent systems. After receipt of confirmation of mode's switching, the matched controller can be applied, which means that the switching time of the matched controller in each node usually lags behind that of system switching. In order to handle the coexistence of switched signals and stochastic disturbances, a comparison principle of stochastic switched delayed systems is first proved. By means of this extended comparison principle, several easy to verified conditions for the existence of an asynchronously switched distributed controller are derived such that stochastic delayed multi-agent systems with asynchronous switching and nonlinear dynamics can achieve global exponential consensus. Two examples are given to illustrate the effectiveness of the proposed method.
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.
International Nuclear Information System (INIS)
Sudheer, K. Sebastian; Sabir, M.
2011-01-01
In this Letter we consider modified function projective synchronization of unidirectionally coupled multiple time-delayed Rossler chaotic systems using adaptive controls. Recently, delay differential equations have attracted much attention in the field of nonlinear dynamics. The high complexity of the multiple time-delayed systems can provide a new architecture for enhancing message security in chaos based encryption systems. Adaptive control can be used for synchronization when the parameters of the system are unknown. Based on Lyapunov stability theory, the adaptive control law and the parameter update law are derived to make the state of two chaotic systems are function projective synchronized. Numerical simulations are presented to demonstrate the effectiveness of the proposed adaptive controllers.
Overlapping controllers for uncertain delay conitunous-time systems
Czech Academy of Sciences Publication Activity Database
Bakule, Lubomír; Rossell, J. M.
2008-01-01
Roč. 44, č. 1 (2008), s. 17-34 ISSN 0023-5954 R&D Projects: GA AV ČR IAA2075304 Institutional research plan: CEZ:AV0Z10750506 Keywords : decentralized control * large-scale complex systems * overlapping decompositions Subject RIV: BC - Control Systems Theory Impact factor: 0.281, year: 2008
Combination synchronization of time-delay chaotic system via robust ...
Indian Academy of Sciences (India)
Ayub Khan
2017-06-01
, which is an important issue. By utilizing ... tor [8], road traffic [9], food web systems [10], etc. can be described more accurately by using .... To design sliding mode controller, there are two basic steps: (1) select an appropriate ...
Dual role of delay effects in a tumour-immune system.
Yu, Min; Dong, Yueping; Takeuchi, Yasuhiro
2017-08-01
In this paper, a previous tumour-immune interaction model is simplified by neglecting a relatively weak direct immune activation by the tumour cells, which can still keep the essential dynamics properties of the original model. As the immune activation process is not instantaneous, we now incorporate one delay for the activation of the effector cells (ECs) by helper T cells (HTCs) into the model. Furthermore, we investigate the stability and instability regions of the tumour-presence equilibrium state of the delay-induced system with respect to two parameters, the activation rate of ECs by HTCs and the HTCs stimulation rate by the presence of identified tumour antigens. We show the dual role of this delay that can induce stability switches exhibiting destabilization as well as stabilization of the tumour-presence equilibrium. Besides, our results reveal that an appropriate immune activation time delay plays a significant role in control of tumour growth.
Non-Gaussian noise-weakened stability in a foraging colony system with time delay
Dong, Xiaohui; Zeng, Chunhua; Yang, Fengzao; Guan, Lin; Xie, Qingshuang; Duan, Weilong
2018-02-01
In this paper, the dynamical properties in a foraging colony system with time delay and non-Gaussian noise were investigated. Using delay Fokker-Planck approach, the stationary probability distribution (SPD), the associated relaxation time (ART) and normalization correlation function (NCF) are obtained, respectively. The results show that: (i) the time delay and non-Gaussian noise can induce transition from a single peak to double peaks in the SPD, i.e., a type of bistability occurring in a foraging colony system where time delay and non-Gaussian noise not only cause transitions between stable states, but also construct the states themselves. Numerical simulations are presented and are in good agreement with the approximate theoretical results; (ii) there exists a maximum in the ART as a function of the noise intensity, this maximum for ART is identified as the characteristic of the non-Gaussian noise-weakened stability of the foraging colonies in the steady state; (iii) the ART as a function of the noise correlation time exhibits a maximum and a minimum, where the minimum for ART is identified as the signature of the non-Gaussian noise-enhanced stability of the foraging colonies; and (iv) the time delay can enhance the stability of the foraging colonies in the steady state, while the departure from Gaussian noise can weaken it, namely, the time delay and departure from Gaussian noise play opposite roles in ART or NCF.
Stable Formation Control of Multi-Robot System with Communication Delay
Directory of Open Access Journals (Sweden)
Limei Jiang
2012-03-01
Full Text Available In this paper, a distributed formation control algorithm with delayed information exchange is discussed. The algorithm, which is derived from the flocking behaviour of birds and consensus theory, enables robots to move in formation at a desired velocity. After a series of orthogonal transformations to the original formation system, the upper bound tolerable delay is obtained by using matrix theory and the Nyquist criterion. According to the results, the upper bound tolerable delay depends on the control parameters and eigenvalues of the Laplacian matrix. Therefore, the effect of the parameters on the maximum tolerable delay is analysed, obtaining the following conclusions: the upper bound tolerable delay is proportional to the parameters associated with the velocity, inversely proportional to the parameters associated with the position, and inversely proportional to the difference between the eigenvalue of Laplacian matrix and 1. The simulation results of a four-robot formation system with different communication delays verify the effectiveness of the formation control algorithm and the correctness of the theoretical analysis.
Oscillation of Two-Dimensional Neutral Delay Dynamic Systems
Directory of Open Access Journals (Sweden)
Xinli Zhang
2013-01-01
Full Text Available We consider a class of nonlinear two-dimensional dynamic systems of the neutral type (x(t-a(tx(τ1(tΔ=p(tf1(y(t, yΔ(t=-q(tf2(x(τ2(t. We obtain sufficient conditions for all solutions of the system to be oscillatory. Our oscillation results when a(t=0 improve the oscillation results for dynamic systems on time scales that have been established by Fu and Lin (2010, since our results do not restrict to the case where f(u=u. Also, as a special case when =ℝ, our results do not require an to be a positive real sequence. Some examples are given to illustrate the main results.
Directory of Open Access Journals (Sweden)
Rong Li
2018-01-01
Full Text Available This paper investigates a class of nonlinear time-delayed systems with output prescribed performance constraint. The neural network and DOB (disturbance observer are designed to tackle the uncertainties and external disturbance, and prescribed performance function is constructed for the output prescribed performance constrained problem. Then the robust controller is designed by using adaptive backstepping method, and the stability analysis is considered by using Lyapunov-Krasovskii. Furthermore, the proposed method is employed into the unmanned helicopter system with time-delay aerodynamic uncertainty. Finally, the simulation results illustrate that the proposed robust prescribed performance control system achieved a good control performance.
Bipartite consensus for multi-agent systems with antagonistic interactions and communication delays
Guo, Xing; Lu, Jianquan; Alsaedi, Ahmed; Alsaadi, Fuad E.
2018-04-01
This paper studies the consensus problems over signed digraphs with arbitrary finite communication delays. For the considered system, the information flow is directed and only locally delayed information can be used for each node. We derive that bipartite consensus of this system can be realized when the associated signed digraph is strongly connected. Furthermore, for structurally balanced networks, this paper studies the pinning partite consensus for the considered system. we design a pinning scheme to pin any one agent in the signed network, and obtain that the network achieves pinning bipartite consensus with any initial conditions. Finally, two examples are provided to demonstrate the effectiveness of our main results.
An automated delayed neutron counting system for mass determinations of special nuclear materials
International Nuclear Information System (INIS)
Sellers, M.T.; Kelly, D.G.; Corcoran, E.C.
2012-01-01
An automated delayed neutron counting (DNC) system has been developed at the Royal Military College of Canada (RMC) to enhance nuclear forensics capabilities pertaining to special nuclear material analysis. The system utilises the SLOWPOKE-2 Facility at RMC as a neutron source and 3 He detectors. System control and data acquisition occur through a LabVIEW platform. The time dependent count rate of the delayed neutron production has been examined for 235 U, using certified reference materials. Experimental validation according to ISO 17025 protocols suggests typical errors and precision of -3.6 and 3.1%, respectively, and a detection limit of 0.26 μg 235 U. (author)
Control of Thermodynamical System with Input-Dependent State Delays
DEFF Research Database (Denmark)
Bendtsen, Jan Dimon; Krstic, Miroslav
2013-01-01
We consider control of a cooling system with several consumers that require cooling from a common source. The flow feeding coolant to the consumers can be controlled, but due to significant physical distances between the common source and the consumers, the coolant flow takes a non...
Compactness of cores of targets for nonlinear delay systems ...
African Journals Online (AJOL)
We complement Ukwu [9] and Chukwu [1] by answering in the affirmative that under certain smoothness conditions, the compactness of cores of targets for a linear system guarantees the compactness of cores of target for the linear perturbation. Journal of the Nigerian Association of Mathematical Physics Vol. 8 2004: pp.
Time-Delay System Identification Using Genetic Algorithm
DEFF Research Database (Denmark)
Yang, Zhenyu; Seested, Glen Thane
2013-01-01
problem through an identification approach using the real coded Genetic Algorithm (GA). The desired FOPDT/SOPDT model is directly identified based on the measured system's input and output data. In order to evaluate the quality and performance of this GA-based approach, the proposed method is compared...
Advanced Takagi‒Sugeno fuzzy systems delay and saturation
Benzaouia, Abdellah
2014-01-01
This monograph puts the reader in touch with a decade’s worth of new developments in the field of fuzzy control specifically those of the popular Takagi-Sugeno (T-S) type. New techniques for stabilizing control analysis and design based on multiple Lyapunov functions and linear matrix inequalities (LMIs), are proposed. All the results are illustrated with numerical examples and figures and a rich bibliography is provided for further investigation. Control saturations are taken into account within the fuzzy model. The concept of positive invariance is used to obtain sufficient asymptotic stability conditions for the fuzzy system with constrained control inside a subset of the state space. The authors also consider the non-negativity of the states. This is of practical importance in many chemical, physical and biological processes that involve quantities that have intrinsically constant and non-negative sign: concentration of substances, level of liquids, etc. Results for linear systems are then extended to l...
FUNDAMENTAL MATRIX OF LINEAR CONTINUOUS SYSTEM IN THE PROBLEM OF ESTIMATING ITS TRANSPORT DELAY
Directory of Open Access Journals (Sweden)
N. A. Dudarenko
2014-09-01
Full Text Available The paper deals with the problem of quantitative estimation for transport delay of linear continuous systems. The main result is received by means of fundamental matrix of linear differential equations solutions specified in the normal Cauchy form for the cases of SISO and MIMO systems. Fundamental matrix has the dual property. It means that the weight function of the system can be formed as a free motion of systems. Last one is generated by the vector of initial system conditions, which coincides with the matrix input of the system being researched. Thus, using the properties of the system- solving for fundamental matrix has given the possibility to solve the problem of estimating transport linear continuous system delay without the use of derivation procedure in hardware environment and without formation of exogenous Dirac delta function. The paper is illustrated by examples. The obtained results make it possible to solve the problem of modeling the pure delay links using consecutive chain of aperiodic links of the first order with the equal time constants. Modeling results have proved the correctness of obtained computations. Knowledge of transport delay can be used when configuring multi- component technological complexes and in the diagnosis of their possible functional degeneration.
IMC based Smith predictor design with PI+CI structure : Control of delayed MIMO systems
Shakibjoo, A.D.; Vasegh, N.; Hossein Nia Kani, S.H.
2016-01-01
In this study a novel structure for time-delay MIMO systems controller design is introduced. In this method decoupled Smith predictor (SP) controller is designed using Internal Model Control structure (IMC). In order to approximate decoupled system, step response model approximation is employed and
Li, Zhichen; Bai, Yan; Huang, Congzhi; Yan, Huaicheng
2017-05-01
This paper investigates the stability and stabilization problems for interval time-delay systems. By introducing a new delay partitioning approach, various Lyapunov-Krasovskii functionals with triple-integral terms are established to make full use of system information. In order to reduce the conservatism, improved integral inequalities are developed for estimation of double integrals, which show remarkable outperformance over the Jensen and Wirtinger ones. Particularly, the relationship between the time-delay and each subinterval is taken into consideration. The resulting stability criteria are less conservative than some recent methods. Based on the derived condition, the state-feedback controller design approach is also given. Finally, the numerical examples and the application to inverted pendulum system are provided to illustrate the effectiveness of the proposed approaches. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.
Directory of Open Access Journals (Sweden)
Jie Zhang
2014-01-01
Full Text Available This paper is concerned with fault detection problem for a class of network control systems (NCSs with multiple communication delays and stochastic missing measurements. The missing measurement phenomenon occurs in a random way and the occurrence probability for each measurement output is governed by an individual random variable. Besides, the multiple communication delay phenomenon reflects that networked control systems have different communication delays when the signals are transferred via different channels. We aim to design a fault detection filter so that the overall fault detection dynamics is exponentially stable in the mean square. By constructing proper Lyapunov-Krasovskii functional, we acquire sufficient conditions to guarantee the stability of the fault detection filter for the discrete systems, and the filter parameters are also derived by solving linear matrix inequality. Finally, an illustrative example is provided to show the usefulness and effectiveness of the proposed design method.
H∞ Filtering for Networked Markovian Jump Systems with Multiple Stochastic Communication Delays
Directory of Open Access Journals (Sweden)
Hui Dong
2015-01-01
Full Text Available This paper is concerned with the H∞ filtering for a class of networked Markovian jump systems with multiple communication delays. Due to the existence of communication constraints, the measurement signal cannot arrive at the filter completely on time, and the stochastic communication delays are considered in the filter design. Firstly, a set of stochastic variables is introduced to model the occurrence probabilities of the delays. Then based on the stochastic system approach, a sufficient condition is obtained such that the filtering error system is stable in the mean-square sense and with a prescribed H∞ disturbance attenuation level. The optimal filter gain parameters can be determined by solving a convex optimization problem. Finally, a simulation example is given to show the effectiveness of the proposed filter design method.
Reconstruction of systems with impulses and delays from time series data
International Nuclear Information System (INIS)
Jeon, Jong-ha; Kim, Pilwon
2014-01-01
In this paper, we present an approach to identification of dynamical systems with irregular impulses and time delays. The suggested method enables one to reconstruct the underlying differential equations, using the l 1 -minimization technique in signal processing which takes advantage of the signal’s sparseness. Based on the idea that irregular impulses can be regarded as sparse error in the fitting procedure, we obtain an efficient algorithm for reconstructions that separates the regular parts of dynamics from impulsive ones. From time series data sampled from an impulsive ecological models, the suggested method restores an essential dynamics of the original systems. The method also applies to chaotic systems perturbed by intermittent impacts and successfully captures dynamics reflecting qualitative behavior independent of impacts. In addition, we can identify a time-delay Lotka–Volterra model with no prior information on delay time given, to which conventional parameter estimate methods are hardly applicable
Extinction and permanence in delayed stage-structure predator-prey system with impulsive effects
International Nuclear Information System (INIS)
Pang Guoping; Wang Fengyan; Chen Lansun
2009-01-01
Based on the classical stage-structured model and Lotka-Volterra predator-prey model, an impulsive delayed differential equation to model the process of periodically releasing natural enemies at fixed times for pest control is proposed and investigated. We show that the conditions for global attractivity of the 'pest-extinction' ('prey-eradication') periodic solution and permanence of the population of the model depend on time delay. We also show that constant maturation time delay and impulsive releasing for the predator can bring great effects on the dynamics of system by numerical analysis. As a result, the pest maturation time delay is considered to establish a procedure to maintain the pests at an acceptably low level in the long term. In this paper, the main feature is that we introduce time delay and pulse into the predator-prey (natural enemy-pest) model with age structure, exhibit a new modelling method which is applied to investigate impulsive delay differential equations, and give some reasonable suggestions for pest management.
Directory of Open Access Journals (Sweden)
Hawa Edriss
2013-11-01
Full Text Available We report a 53-year-old man who ingested 2400 mg of citalopram and presented to the emergency department three hours post-ingestion with altered mental status, somnolence, and a blood pressure of 67/45 mmHg. He failed to respond to three boluses of normal saline (1000 ml each and required vasopressors. The patient developed serotonin syndrome with hyper-reflexia, rigidity, and ankle myoclonus. He had a tonic-clonic seizure in the ER requiring intravenous lorazepam and phenytoin. An ECG showed QT prolongation. Chest x-ray on presentation was normal. Within 32 hours the patient developed acute respiratory distress, hypoxemia, a wide A-a gradient, PaO2/FiO2< 200, and chest x-ray changes compatible with acute respiratory distress syndrome (ARDS. He had normal central venous pressures, normal cardiac biomarkers, normal systolic and diastolic functions on echocardiography, and no acute ST/T wave changes. His ABG showed a metabolic acidosis and a respiratory acidosis. The patient required intubation and ventilation. Citalopram has been associated with seizures and ECG abnormalities after overdoses. The respiratory complications and metabolic acidosis have been reported only a few times in the literature. We are reporting the second case of ARDS and the fifth case of metabolic acidosis due to citalopram overdose and suggest that the metabolic acidemia is explained by propionic acid. The respiratory acidosis seen in this patient has not been reported previously.
Directory of Open Access Journals (Sweden)
T. Ortega-Montiel
2017-01-01
Full Text Available The design and tuning of a simple feedback strategy with delay to stabilize a class of underactuated mechanical systems with dead time are presented. A linear time-invariant (LTI model with time delay of fourth order and a Proportional Retarded (PR controller are considered. The PR controller is shown as an appealing alternative to the application of observer-based controllers. This paper gives a step forward to obtain a better understanding of the effect of output delays and related phenomena in mechatronic systems, making it possible to design resilient control laws under the presence of uncertain time delays in measurements and obtain an acceptable performance without using a derivative action. The Furuta pendulum is a standard two-degrees-of-freedom benchmark example from the class of underactuated mechanical systems. The configuration under study includes an inherent output delay due to wireless communication used to transmit measurements of the pendulum’s angular position. Our approach offers a constructive design and a procedure based on a combination of root loci and Mikhailov methods for the analysis of stability. Experiments over a laboratory platform are reported and a comparison with a standard linear state feedback control law shows the advantages of the proposed scheme.
Ruminal Acidosis in Feedlot: From Aetiology to Prevention
Directory of Open Access Journals (Sweden)
Joaquín Hernández
2014-01-01
Full Text Available Acute ruminal acidosis is a metabolic status defined by decreased blood pH and bicarbonate, caused by overproduction of ruminal D-lactate. It will appear when animals ingest excessive amount of nonstructural carbohydrates with low neutral detergent fiber. Animals will show ruminal hypotony/atony with hydrorumen and a typical parakeratosis-rumenitis liver abscess complex, associated with a plethora of systemic manifestations such as diarrhea and dehydration, liver abscesses, infections of the lung, the heart, and/or the kidney, and laminitis, as well as neurologic symptoms due to both cerebrocortical necrosis and the direct effect of D-lactate on neurons. In feedlots, warning signs include decrease in chewing activity, weight, and dry matter intake and increase in laminitis and diarrhea prevalence. The prognosis is quite variable. Treatment will be based on the control of systemic acidosis and dehydration. Prevention is the most important tool and will require normalization of ruminal pH and microbiota. Appropriate feeding strategies are essential and involve changing the dietary composition to increase neutral detergent fiber content and greater particle size and length. Appropriate grain processing can control the fermentation rate while additives such as prebiotics or probiotics can help to stabilize the ruminal environment. Immunization against producers of D-lactate is being explored.
Directory of Open Access Journals (Sweden)
Jing Wang
2012-01-01
Full Text Available The stabilization problem of a wireless networked control system is considered in this paper. Both time delay and packet loss exist simultaneously in the wireless network. The system is modeled as an asynchronous dynamic system (ADS with unstable subsystems. A sufficient condition for the system to be stable is presented. A numerical example is given to demonstrate the effectiveness of the proposed approach.
pth moment asymptotic stability of stochastic delayed hybrid systems with Lévy noise
Yang, Jun; Zhou, Wuneng; Yang, Xueqing; Hu, Xiaotao; Xie, Lili
2015-09-01
The problem of pth moment asymptotic stability analysis is considered for stochastic delayed hybrid systems with Lévy noise. By virtue of Itô's formula and M-matrix theories, we propose some sufficient conditions to guarantee the asymptotic stability and exponential stability of the system. The criterion of mean square asymptotic stability is derived as well for delayed neural networks with Lévy noise. A numerical example is provided to show the usefulness of the proposed asymptotic stability criterion.
On-line parameter and delay estimation of continuous-time dynamic systems
Directory of Open Access Journals (Sweden)
Kozłowski Janusz
2015-06-01
Full Text Available The problem of on-line identification of non-stationary delay systems is considered. The dynamics of supervised industrial processes are usually modeled by ordinary differential equations. Discrete-time mechanizations of continuous-time process models are implemented with the use of dedicated finite-horizon integrating filters. Least-squares and instrumental variable procedures mechanized in recursive forms are applied for simultaneous identification of input delay and spectral parameters of the system models. The performance of the proposed estimation algorithms is verified in an illustrative numerical simulation study.
On the Pontryagin maximum principle for systems with delays. Economic applications
Kim, A. V.; Kormyshev, V. M.; Kwon, O. B.; Mukhametshin, E. R.
2017-11-01
The Pontryagin maximum principle [6] is the key stone of finite-dimensional optimal control theory [1, 2, 5]. So beginning with opening the maximum principle it was important to extend the maximum principle on various classes of dynamical systems. In t he paper we consider some aspects of application of i-smooth analysis [3, 4] in the theory of the Pontryagin maximum principle [6] for systems with delays, obtained results can be applied by elaborating optimal program controls in economic models with delays.
Understanding lactic acidosis in paracetamol (acetaminophen) poisoning
Shah, Anoop D; Wood, David M; Dargan, Paul I
2011-01-01
Paracetamol (acetaminophen) is one of the most commonly taken drugs in overdose in many areas of the world, and the most common cause of acute liver failure in both the UK and USA. Paracetamol poisoning can result in lactic acidosis in two different scenarios. First, early in the course of poisoning and before the onset of hepatotoxicity in patients with massive ingestion; a lactic acidosis is usually associated with coma. Experimental evidence from studies in whole animals, perfused liver slices and cell cultures has shown that the toxic metabolite of paracetamol, N-acetyl-p-benzo-quinone imine, inhibits electron transfer in the mitochondrial respiratory chain and thus inhibits aerobic respiration. This occurs only at very high concentrations of paracetamol, and precedes cellular injury by several hours. The second scenario in which lactic acidosis can occur is later in the course of paracetamol poisoning as a consequence of established liver failure. In these patients lactate is elevated primarily because of reduced hepatic clearance, but in shocked patients there may also be a contribution of peripheral anaerobic respiration because of tissue hypoperfusion. In patients admitted to a liver unit with paracetamol hepatotoxicity, the post-resuscitation arterial lactate concentration has been shown to be a strong predictor of mortality, and is included in the modified King's College criteria for consideration of liver transplantation. We would therefore recommend that post-resuscitation lactate is measured in all patients with a severe paracetamol overdose resulting in either reduced conscious level or hepatic failure. PMID:21143497
Delayed cell death signaling in traumatized central nervous system: hypoxia.
Chu, Danielle; Qiu, JingXin; Grafe, Marjorie; Fabian, Roderick; Kent, Thomas A; Rassin, David; Nesic, Olivera; Werrbach-Perez, Karin; Perez-Polo, Regino
2002-02-01
There are two different ways for cells to die: necrosis and apoptosis. Cell death has traditionally been described as necrotic or apoptotic based on morphological criteria. There are controversy about the respective roles of apoptosis and necrosis in cell death resulting from trauma to the central nervous system (CNS). An evaluation of work published since 1997 in which electron microscopy was applied to ascertain the role of apoptosis and necrosis in: spinal cord injury, stroke, and hypoxia/ischemia (H/I) showed evidence for necrosis and apoptosis based on DNA degradation, presence of histones in cytoplasm, and morphological evidence in spinal cord. In the aftermath of stroke, many of the biochemical markers for apoptosis were present but the morphological determinations suggested that necrosis is the major source of post-traumatic cell death. This was not the case in H/I where both biochemical assays and the morphological studies gave more consistent results in a manner similar to the spinal cord injury studies. After H/I, major factors affecting cell death outcomes are DNA damage and repair processes, expression of bcl-like gene products and inflammation-triggered cytokine production.
Robust decentralised PI based LFC design for time delay power systems
International Nuclear Information System (INIS)
Bevrani, Hassan; Hiyama, Takashi
2008-01-01
In this paper, two robust decentralised proportional integral (PI) control designs are proposed for load frequency control (LFC) with communication delays. In both methodologies, the PI based LFC problem is reduced to a static output feedback (SOF) control synthesis for a multiple delay system. The first one is based on the optimal H ∞ control design using a linear matrix inequalities (LMI) technique. The second control design gives a suboptimal solution using a developed iterative linear matrix inequalities (ILMI) algorithm via the mixed H 2 /H ∞ control technique. The control strategies are suitable for LFC applications that usually employ PI control. The proposed control strategies are applied to a three control area power system with time delays and load disturbance to demonstrate their robustness
Directory of Open Access Journals (Sweden)
Jianxin Feng
2014-01-01
Full Text Available The recursive estimation problem is studied for a class of uncertain dynamical systems with different delay rates sensor network and autocorrelated process noises. The process noises are assumed to be autocorrelated across time and the autocorrelation property is described by the covariances between different time instants. The system model under consideration is subject to multiplicative noises or stochastic uncertainties. The sensor delay phenomenon occurs in a random way and each sensor in the sensor network has an individual delay rate which is characterized by a binary switching sequence obeying a conditional probability distribution. By using the orthogonal projection theorem and an innovation analysis approach, the desired recursive robust estimators including recursive robust filter, predictor, and smoother are obtained. Simulation results are provided to demonstrate the effectiveness of the proposed approaches.
Directory of Open Access Journals (Sweden)
Chen Yuming
2011-01-01
Full Text Available Though boundary value problems for fractional differential equations have been extensively studied, most of the studies focus on scalar equations and the fractional order between 1 and 2. On the other hand, delay is natural in practical systems. However, not much has been done for fractional differential equations with delays. Therefore, in this paper, we consider a boundary value problem of a general delayed nonlinear fractional system. With the help of some fixed point theorems and the properties of the Green function, we establish several sets of sufficient conditions on the existence of positive solutions. The obtained results extend and include some existing ones and are illustrated with some examples for their feasibility.
Stability and Hopf Bifurcation of a Reaction-Diffusion Neutral Neuron System with Time Delay
Dong, Tao; Xia, Linmao
2017-12-01
In this paper, a type of reaction-diffusion neutral neuron system with time delay under homogeneous Neumann boundary conditions is considered. By constructing a basis of phase space based on the eigenvectors of the corresponding Laplace operator, the characteristic equation of this system is obtained. Then, by selecting time delay and self-feedback strength as the bifurcating parameters respectively, the dynamic behaviors including local stability and Hopf bifurcation near the zero equilibrium point are investigated when the time delay and self-feedback strength vary. Furthermore, the direction of the Hopf bifurcation and the stability of bifurcating periodic solutions are obtained by using the normal form and the center manifold theorem for the corresponding partial differential equation. Finally, two simulation examples are given to verify the theory.
The diffusive Lotka-Volterra predator-prey system with delay.
Al Noufaey, K S; Marchant, T R; Edwards, M P
2015-12-01
Semi-analytical solutions for the diffusive Lotka-Volterra predator-prey system with delay are considered in one and two-dimensional domains. The Galerkin method is applied, which approximates the spatial structure of both the predator and prey populations. This approach is used to obtain a lower-order, ordinary differential delay equation model for the system of governing delay partial differential equations. Steady-state and transient solutions and the region of parameter space, in which Hopf bifurcations occur, are all found. In some cases simple linear expressions are found as approximations, to describe steady-state solutions and the Hopf parameter regions. An asymptotic analysis for the periodic solution near the Hopf bifurcation point is performed for the one-dimensional domain. An excellent agreement is shown in comparisons between semi-analytical and numerical solutions of the governing equations. Copyright © 2015 Elsevier Inc. All rights reserved.
Almost Sure Stability and Stabilization for Hybrid Stochastic Systems with Time-Varying Delays
Directory of Open Access Journals (Sweden)
Hua Yang
2012-01-01
Full Text Available The problems of almost sure (a.s. stability and a.s. stabilization are investigated for hybrid stochastic systems (HSSs with time-varying delays. The different time-varying delays in the drift part and in the diffusion part are considered. Based on nonnegative semimartingale convergence theorem, Hölder’s inequality, Doob’s martingale inequality, and Chebyshev’s inequality, some sufficient conditions are proposed to guarantee that the underlying nonlinear hybrid stochastic delay systems (HSDSs are almost surely (a.s. stable. With these conditions, a.s. stabilization problem for a class of nonlinear HSDSs is addressed through designing linear state feedback controllers, which are obtained in terms of the solutions to a set of linear matrix inequalities (LMIs. Two numerical simulation examples are given to show the usefulness of the results derived.
Consensus of Discrete Multiagent System with Various Time Delays and Environmental Disturbances
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Zheping Yan
2014-12-01
Full Text Available In this paper, the consensus problem of discrete multiagent systems with time varying sampling periods is studied. Firstly, with thorough analysis of various delays among agents, the control input of each agent is designed with consideration of sending delay and receiving delay. With construction of discrete dynamics of state error vector, it is proved by applying Halanay inequality that consensus of the system can be reached. Further, the definition of bounded consensus is proposed in the situation where environmental disturbances exist. In order to handle this problem, the Halanay inequality is extended into a more general one with boundedness property. Based on the new Halanay inequality obtained, the boundedness of consensus error is guaranteed. At last, simulation examples are presented to demonstrate the theoretical conclusions.
Delayed information flow effect in economy systems. An ACP model study
Miśkiewicz, Janusz; Ausloos, M.
2007-08-01
Applying any strategy requires some knowledge about the past state of the system. Unfortunately in the case of economy, collecting information is a difficult, expensive and time consuming process. Therefore, the information about the system is usually known only at the end of some well-defined intervals, e.g. through company, national bank inflation data and Gross Domestic Product (GDP) reports, etc. They describe a (market) situation in the past. The time delay is specific to the market branch. It can be very short (e.g. stock market offer is updated every minute or so and this information is quasi-immediately available) or long, like months in the case of agricultural markets, when the decisions are taken based on the results from the previous harvest. The analysis of the information flow delay can be based on the Ausloos-Clippe-Pękalski (ACP) model of spatial evolution of economic systems. The entities can move on a (square) lattice and when meeting take one of the two following decisions: merge or create a new entity. The decision is based on the system state, which is known with some time delay. The effect of system's feedback is hereby investigated. We consider the case of company distribution evolution in a heterogeneous field. The information flow time delay implies different final states, including cycles; it is like a control parameter in a logistic map.
Predictor-based stabilization for chained form systems with input time delay
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Mnif Faïçal
2016-12-01
Full Text Available This note addresses the stabilization problem of nonlinear chained-form systems with input time delay. We first employ the so-called σ-process transformation that renders the feedback system under a linear form. We introduce a particular transformation to convert the original system into a delay-free system. Finally, we apply a state feedback control, which guarantees a quasi-exponential stabilization to all the system states, which in turn converge exponentially to zero. Then we employ the so-called -type control to achieve a quasi-exponential stabilization of the subsequent system. A simulation example illustrated on the model of a wheeled mobile robot is provided to demonstrate the effectiveness of the proposed approach.
Refractory rickets caused by mild distal renal tubular acidosis
Ji-Ho Lee; Joo Hyun Park; Tae-Sun Ha; Heon-Seok Han
2013-01-01
Type I (distal) renal tubular acidosis (RTA) is a disorder associated with the failure to excrete hydrogen ions from the distal renal tubule. It is characterized by hyperchloremic metabolic acidosis, an abnormal increase in urine pH, reduced urinary excretion of ammonium and bicarbonate ions, and mild deterioration in renal function. Hypercalciuria is common in distal RTA because of bone resorption, which increases as a buffer against metabolic acidosis. This can result in intractable rickets...
Fatal acidosis in a neonate with Pearson syndrome.
Gürakan, B; Ozbek, N; Varan, B; Demirhan, B
1999-01-01
We report a neonate who presented with hypotonia, hypoglycemia, and severe lactic acidosis. The patient's acidosis did not respond to bicarbonate replacement and dialysis. Postmortem liver samples revealed portal dilatation, fibrosis, canalicular proliferation, cholestasis, and hepatocellular hemosiderosis. Vacuolization of bone marrow precursors suggested a diagnosis of Pearson syndrome. A common mitochondrial DNA deletion of 4,978 bp was found. We emphasize that Pearson syndrome should be considered in neonates with lactic acidosis despite absence of anemia.
Metabolic acidosis and its association with nutritional status in hemodialysis.
de Oliveira, Claudia Maria Costa; Vidal, Caroline Lustosa da Costa; Cristino, Eurinice Fontenele; Pinheiro, Francisco Marto Leal; Kubrusly, Marcos
2015-01-01
Metabolic acidosis is a common problem in dialysis patients and plays an important role in the pathogenesis of protein-energy malnutrition in these patients. To assess the prevalence of metabolic acidosis in hemodialysis and search their association with nutritional status. A cross-sectional study was performed in hemodialysis patients at a single center. Nutritional status was assessed by anthropometric, biochemical and multifrequency bioelectrical impedance analysis. Metabolic acidosis was defined as serum bicarbonate (BIC) nutritional status, inflammation and bone disease.
Observer Design for a Time Delay System via the Razumikhin Approach
Czech Academy of Sciences Publication Activity Database
Rehák, Branislav
2017-01-01
Roč. 19, č. 6 (2017), s. 2226-2231 ISSN 1561-8625 R&D Projects: GA ČR GA13-02149S Institutional support: RVO:67985556 Keywords : observer * time-delay system * input-to-state stability * quantization Subject RIV: BC - Control System s Theory OBOR OECD: Automation and control system s Impact factor: 1.421, year: 2016 http://onlinelibrary.wiley.com/doi/10.1002/asjc.1507/full
Ma, Linlin; Liang, Yanping; Chen, Jian
2016-01-01
This paper studies the stabilization problem for damping multimachine power system with time-varying delays and sector saturating actuator. The multivariable proportional plus derivative (PD) type stabilizer is designed by transforming the problem of PD controller design to that of state feedback stabilizer design for a system in descriptor form. A new sufficient condition of closed-loop multimachine power system asymptomatic stability is derived based on the Lyapunov theory. Computer simulat...
DEFF Research Database (Denmark)
Dou, Chun-Xia; Yue, Dong; Guerrero, Josep M.
2017-01-01
This paper focuses on a multi-agent based distributed coordinated control for radial DC microgrid considering trans-mission time delays. Firstly, a two-level multi-agent system is constructed, where local control is formulated based on local states and executed by means of the first-level agent...
Stability bound analysis of singularly perturbed systems with time-delay
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Sun Fengqi
2013-01-01
Full Text Available This paper considers the stability bound problem of singularly perturbed systems with time-delay. Some stability criteria are derived by constructing appropriate Lyapunov-Krasovskii functionals. The proposed criteria are less conservative than the existing ones. Two numerical examples are given to illustrate the advantages and effectiveness of the proposed methods.
Multimoded rf delay line distribution system for the Next Linear Collider
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S. G. Tantawi
2002-03-01
Full Text Available The delay line distribution system is an alternative to conventional pulse compression, which enhances the peak power of rf sources while matching the long pulse of those sources to the shorter filling time of accelerator structures. We present an implementation of this scheme that combines pairs of parallel delay lines of the system into single lines. The power of several sources is combined into a single waveguide delay line using a multimode launcher. The output mode of the launcher is determined by the phase coding of the input signals. The combined power is extracted from the delay line using mode-selective extractors, each of which extracts a single mode. Hence, the phase coding of the sources controls the output port of the combined power. The power is then fed to the local accelerator structures. We present a detailed design of such a system, including several implementation methods for the launchers, extractors, and ancillary high power rf components. The system is designed so that it can handle the 600 MW peak power required by the Next Linear Collider design while maintaining high efficiency.
LMI optimization approach to stabilization of time-delay chaotic systems
International Nuclear Information System (INIS)
Park, Ju H.; Kwon, O.M.
2005-01-01
Based on the Lyapunov stability theory and linear matrix inequality (LMI) technique, this paper proposes a novel control method for stabilization of a class of time-delay chaotic systems. A stabilization criterion is derived in terms of LMIs which can be easily solved by efficient convex optimization algorithms. A numerical example is included to show the advantage of the result derived
pth Moment stability of impulsive stochastic delay differential systems with Markovian switching
Wu, Xiaotai; Zhang, Wenbing; Tang, Yang
2013-07-01
This paper is concerned with the pth moment stability of impulsive stochastic delay differential systems with Markovian switching. By using the Razumikhin-type method, some stability criteria are obtained, which can loosen the constraints of the existing results and thus reduce the conservativeness. Two examples are presented to demonstrate the usefulness of the proposed results.
Inverse chaos synchronization in linearly and nonlinearly coupled systems with multiple time-delays
International Nuclear Information System (INIS)
Shahverdiev, E.M.; Hashimov, R.H.; Nuriev, R.A.; Hashimova, L.H.; Huseynova, E.M.; Shore, K.A.
2005-04-01
We report on inverse chaos synchronization between two unidirectionally linearly and nonlinearly coupled chaotic systems with multiple time-delays and find the existence and stability conditions for different synchronization regimes. We also study the effect of parameter mismatches on synchonization regimes. The method is tested on the famous Ikeda model. Numerical simulations fully support the analytical approach. (author)
Controllability of impulsive functional differential systems with infinite delay in Banach spaces
International Nuclear Information System (INIS)
Chang Yongkui
2007-01-01
The paper establishes a sufficient condition for the controllability of the first-order impulsive functional differential systems with infinite delay in Banach spaces. We use Schauder's fixed point theorem combined with a strongly continuous operator semigroup. An example is given to illustrate our results
Directory of Open Access Journals (Sweden)
Azizollah Babakhani
2010-01-01
Full Text Available We investigate the existence and uniqueness of positive solution for system of nonlinear fractional differential equations in two dimensions with delay. Our analysis relies on a nonlinear alternative of Leray-Schauder type and Krasnoselskii's fixed point theorem in a cone.
11th International Federation of Automatic Control (IFAC) Workshop on Time-Delay Systems
Fridman, Emilia; Sename, Olivier; Dugard, Luc
2016-01-01
This book mostly results from a selection of papers presented during the 11th IFAC (International Federation of Automatic Control) Workshop on Time-Delay Systems, which took place in Grenoble, France, February 4 - 6, 2013. During this event, 37 papers were presented. Taking into account the reviewers' evaluation and the papers' presentation the best papers have been selected and collected into the present volume. The authors of 13 selected papers were invited to participate to this book and provided a more detailed and improved version of the conference paper. To enrich the book, three more chapters have been included from specialists on time-delay systems who presented their work during the 52nd IEEE Conference on Decision and Control, which held in December 10 - 13, 2013, at Florence, Italy. The content of the book is divided into four main parts as follows: Modeling, Stability analysis, Stabilization and control, and Input-delay systems. Focusing on various topics of time-delay systems, this book will be...
An improved condition for master-slave synchronization of Lur'e systems with time delay
International Nuclear Information System (INIS)
Xiang, Ji; Li, Yanjun; Wei, Wei
2007-01-01
In this Letter, a new sufficient condition is proposed for master-slave synchronization of Lur'e system with time delay. This condition is constructed on the new integral inequality method such that the obtained result is much sharper than that in [M.E.Y. Yalcin, J.A.K. Suykens, J. Vandewalle, Int. J. Bifur. Chaos 11 (2001) 1707
A martingale approach to state estimation in delay-differential systems
Bagchi, Arunabha
1976-01-01
A rigorous derivation of filtering arid smoothing equations for linear stochastic systems with time delay is presented. The estimation equations are obtained in term of the innovation process of the problem under consideration. The method used is based on a representation theorem on Gaussian
Drug-Induced Metabolic Acidosis [version 1; referees: 3 approved
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Amy Quynh Trang Pham
2015-12-01
Full Text Available Metabolic acidosis could emerge from diseases disrupting acid-base equilibrium or from drugs that induce similar derangements. Occurrences are usually accompanied by comorbid conditions of drug-induced metabolic acidosis, and clinical outcomes may range from mild to fatal. It is imperative that clinicians not only are fully aware of the list of drugs that may lead to metabolic acidosis but also understand the underlying pathogenic mechanisms. In this review, we categorized drug-induced metabolic acidosis in terms of pathophysiological mechanisms, as well as individual drugs’ characteristics.
D-lactic acidosis in humans: systematic literature review.
Bianchetti, Davide G A M; Amelio, Giacomo S; Lava, Sebastiano A G; Bianchetti, Mario G; Simonetti, Giacomo D; Agostoni, Carlo; Fossali, Emilio F; Milani, Gregorio P
2018-04-01
D-lactic acidosis is an uncommon and challenging form of metabolic acidosis that may develop in short bowel syndrome. It has been documented exclusively in case reports and small case series. We performed a review of the literature in the National Library of Medicine and Excerpta Medica databases. We identified 84 original reports published between 1977 and 2017. D-lactic acidosis was observed in 98 individuals ranging in age from 7 months to 86 years with short bowel syndrome. The clinical presentation included Kussmaul breathing, confusion, slurred speech, and gait disturbances. Furthermore, among 99 consecutive patients with short bowel syndrome, 21 reported having episodes with symptoms consistent with D-lactic acidosis. In addition, D-lactic acid might also contribute to acidosis in diabetes mellitus. Finally, abnormally high D-lactic acid was documented after administration or ingestion of large amounts of propylene glycol, as paraneoplastic phenomenon and perhaps also in a so far poorly characterized inherited inborn error of metabolism. In humans with short bowel syndrome (or carbohydrate malabsorption), D-lactic acidosis is likely rather common and under-recognized. This condition should be included in the differential diagnosis of unexplained high-gap metabolic acidosis where the anion causing the acidosis is not known. Furthermore, diabetic acidosis might be caused by accumulation of both ketone bodies and D-lactic acid. Finally, there are endogenous sources of D-lactic acid in subjects with propylene glycol intoxication.
Distal renal tubular acidosis in recurrent renal stone formers
DEFF Research Database (Denmark)
Osther, P J; Hansen, A B; Røhl, H F
1989-01-01
(1.1%) had complete distal renal tubular acidosis and 14 (15.5%) incomplete distal renal tubular acidosis. Our results confirm that distal renal tubular acidification defects are associated with a more severe form of stone disease and make distal renal tubular acidosis one of the most frequent...... metabolic disturbances in renal stone formers. Distal renal tubular acidosis (dRTA) was relatively more common in female stone formers and most often found in patients with bilateral stone disease (36%). Since prophylactic treatment in renal stone formers with renal acidification defects is available...
Severe lactic acidosis and neonatal death in Pearson syndrome.
Muraki, K; Goto, Y; Nishino, I; Hayashidani, M; Takeuchi, S; Horai, S; Sakura, N; Ueda, K
1997-03-01
Pearson marrow-pancreas syndrome, a fatal disease associated with mitochondrial DNA rearrangements, is characterized by refractory sideroblastic anaemia during infancy. Only a few neonates with Pearson syndrome have been reported with metabolic acidosis. A female neonate who exhibited severe metabolic acidosis and anaemia at birth is described here. Her condition progressively worsened, with pancytopenia and uncontrollable metabolic acidosis resulting in death at the age of 14 days. A 4988-base pair deletion of mtDNA was detected in the patient's leukocytes, liver and muscle. When a neonate exhibits severe metabolic acidosis of unknown cause, the possibility of Pearson syndrome should be considered.
Quasipolynomial Approach to Simultaneous Robust Control of Time-Delay Systems
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Nikolaj Semenič
2014-01-01
Full Text Available A control law for retarded time-delay systems is considered, concerning infinite closed-loop spectrum assignment. An algebraic method for spectrum assignment is presented with a unique optimization algorithm for minimization of spectral abscissa and effective shaping of the chains of infinitely many closed-loop poles. Uncertainty of plant delays of a certain structure is considered in a sense of a robust simultaneous stabilization. Robust performance is achieved using mixed sensitivity design, which is incorporated into the addressed control law.
ANOMALY NETWORK INTRUSION DETECTION SYSTEM BASED ON DISTRIBUTED TIME-DELAY NEURAL NETWORK (DTDNN
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LAHEEB MOHAMMAD IBRAHIM
2010-12-01
Full Text Available In this research, a hierarchical off-line anomaly network intrusion detection system based on Distributed Time-Delay Artificial Neural Network is introduced. This research aims to solve a hierarchical multi class problem in which the type of attack (DoS, U2R, R2L and Probe attack detected by dynamic neural network. The results indicate that dynamic neural nets (Distributed Time-Delay Artificial Neural Network can achieve a high detection rate, where the overall accuracy classification rate average is equal to 97.24%.
Model Predictive Optimal Control of a Time-Delay Distributed-Parameter Systems
Nguyen, Nhan
2006-01-01
This paper presents an optimal control method for a class of distributed-parameter systems governed by first order, quasilinear hyperbolic partial differential equations that arise in many physical systems. Such systems are characterized by time delays since information is transported from one state to another by wave propagation. A general closed-loop hyperbolic transport model is controlled by a boundary control embedded in a periodic boundary condition. The boundary control is subject to a nonlinear differential equation constraint that models actuator dynamics of the system. The hyperbolic equation is thus coupled with the ordinary differential equation via the boundary condition. Optimality of this coupled system is investigated using variational principles to seek an adjoint formulation of the optimal control problem. The results are then applied to implement a model predictive control design for a wind tunnel to eliminate a transport delay effect that causes a poor Mach number regulation.
Formation tracking control for time-delayed multi-agent systems with second-order dynamics
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Liang Han
2017-02-01
Full Text Available In this paper, formation tracking control problems for second-order multi-agent systems (MASs with time-varying delays are studied, specifically those where the position and velocity of followers are designed to form a time-varying formation while tracking those of the leader. A neighboring relative state information based formation tracking protocol with an unknown gain matrix and time-varying delays is presented. The formation tracking problems are then transformed into asymptotically stable problems. Based on the Lyapunov-Krasovskii functional approach, conditions sufficient for second-order MASs with time-varying delays to realize formation tracking are examined. An approach to obtain the unknown gain matrix is given and, since neighboring relative velocity information is difficult to measure in practical applications, a formation tracking protocol with time-varying delays using only neighboring relative position information is introduced. The proposed results can be used on target enclosing problems for MASs with second-order dynamics and time-varying delays. An application for target enclosing by multiple unmanned aerial vehicles (UAVs is given to demonstrate the feasibility of theoretical results.
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. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.
Anticipated and zero-lag synchronization in motifs of delay-coupled systems.
Mirasso, Claudio R; Carelli, Pedro V; Pereira, Tiago; Matias, Fernanda S; Copelli, Mauro
2017-11-01
Anticipated and zero-lag synchronization have been observed in different scientific fields. In the brain, they might play a fundamental role in information processing, temporal coding and spatial attention. Recent numerical work on anticipated and zero-lag synchronization studied the role of delays. However, an analytical understanding of the conditions for these phenomena remains elusive. In this paper, we study both phenomena in systems with small delays. By performing a phase reduction and studying phase locked solutions, we uncover the functional relation between the delay, excitation and inhibition for the onset of anticipated synchronization in a sender-receiver-interneuron motif. In the case of zero-lag synchronization in a chain motif, we determine the stability conditions. These analytical solutions provide an excellent prediction of the phase-locked regimes of Hodgkin-Huxley models and Roessler oscillators.
Anticipated and zero-lag synchronization in motifs of delay-coupled systems
Mirasso, Claudio R.; Carelli, Pedro V.; Pereira, Tiago; Matias, Fernanda S.; Copelli, Mauro
2017-11-01
Anticipated and zero-lag synchronization have been observed in different scientific fields. In the brain, they might play a fundamental role in information processing, temporal coding and spatial attention. Recent numerical work on anticipated and zero-lag synchronization studied the role of delays. However, an analytical understanding of the conditions for these phenomena remains elusive. In this paper, we study both phenomena in systems with small delays. By performing a phase reduction and studying phase locked solutions, we uncover the functional relation between the delay, excitation and inhibition for the onset of anticipated synchronization in a sender-receiver-interneuron motif. In the case of zero-lag synchronization in a chain motif, we determine the stability conditions. These analytical solutions provide an excellent prediction of the phase-locked regimes of Hodgkin-Huxley models and Roessler oscillators.
Metabolic acidosis and ventilatory response
Langbroek, Aart Jan Mattheüs
1988-01-01
In terrestrial vertebrates lung ventilation is nescessary to accmplish exchange of oxygen (O2) and carbon dioxide (CO2) between the gas phase (lung alveoli) and the fluid phase (the blood flowing through the lung capillaries). The ventilatory control system adjusts the arterial carbon dioxide
Building an Energy-efficient Uplink and Downlink Delay Aware TDM-PON System
Newaz, S. H. Shah; Jang, Min Seok; Alaelddin, Fuad Yousif Mohammed; Lee, Gyu Myoung; Choi, Jun Kyun
2016-05-01
With the increasing concern over the energy expenditure due to rapid ICT expansion and growth of Internet traffic volume, there is a growing trend towards developing energy-efficient ICT solutions. Passive Optical Network (PON), which is regarded as a key enabler to facilitate high speed broadband connection to individual subscribers, is considered as one of the energy-efficient access network technologies. However, an immense amount of research effort can be noticed in academia and industries to make PON more energy-efficient. In this paper, we aim at improving energy saving performance of Time Division Multiplexing (TDM)-PON, which is the most widely deployed PON technology throughout the world. A commonly used approach to make TDM-PON energy-efficient is to use sleep mode in Optical Network Units (ONUs), which are the customer premises equipment of a TDM-PON system. However, there is a strong trade-off relationship between traffic delay performance of an ONU and its energy saving (the longer the sleep interval length of an ONU, the lower its energy consumption, but the higher the traffic delay, and vice versa). In this paper, we propose an Energy-efficient Uplink and Downlink Delay Aware (EUDDA) scheme for TDM-PON system. The prime object of EUDDA is to meet both downlink and uplink traffic delay requirement while maximizing energy saving performance of ONUs as much as possible. In EUDDA, traffic delay requirement is given more priority over energy saving. Even so, it still can improve energy saving of ONUs noticeably. We evaluate performance of EUDDA in front of two existing solutions in terms of traffic delay, jitter, and ONU energy consumption. The performance results show that EUDDA significantly outperforms the other existing solutions.
Effects of delayed immune-response in tumor immune-system interplay
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Alberto d'Onofrio
2012-08-01
Full Text Available Tumors constitute a wide family of diseases kinetically characterized by the co-presence of multiple spatio-temporal scales. So, tumor cells ecologically interplay with other kind of cells, e.g. endothelial cells or immune system effectors, producing and exchanging various chemical signals. As such, tumor growth is an ideal object of hybrid modeling where discrete stochastic processes model agents at low concentrations, and mean-field equations model chemical signals. In previous works we proposed a hybrid version of the well-known Panetta-Kirschner mean-field model of tumor cells, effector cells and Interleukin-2. Our hybrid model suggested -at variance of the inferences from its original formulation- that immune surveillance, i.e. tumor elimination by the immune system, may occur through a sort of side-effect of large stochastic oscillations. However, that model did not account that, due to both chemical transportation and cellular differentiation/division, the tumor-induced recruitment of immune effectors is not instantaneous but, instead, it exhibits a lag period. To capture this, we here integrate a mean-field equation for Interleukins-2 with a bi-dimensional delayed stochastic process describing such delayed interplay. An algorithm to realize trajectories of the underlying stochastic process is obtained by coupling the Piecewise Deterministic Markov process (for the hybrid part with a Generalized Semi-Markovian clock structure (to account for delays. We (i relate tumor mass growth with delays via simulations and via parametric sensitivity analysis techniques, (ii we quantitatively determine probabilistic eradication times, and (iii we prove, in the oscillatory regime, the existence of a heuristic stochastic bifurcation resulting in delay-induced tumor eradication, which is neither predicted by the mean-field nor by the hybrid non-delayed models.
Yu, Yue; Zhang, Zhengdi; Han, Xiujing
2018-03-01
In this work, we aim to demonstrate the novel routes to periodic and chaotic bursting, i.e., the different bursting dynamics via delayed pitchfork bifurcations around stable attractors, in the classical controlled Lü system. First, by computing the corresponding characteristic polynomial, we determine where some critical values about bifurcation behaviors appear in the Lü system. Moreover, the transition mechanism among different stable attractors has been introduced including homoclinic-type connections or chaotic attractors. Secondly, taking advantage of the above analytical results, we carry out a study of the mechanism for bursting dynamics in the Lü system with slowly periodic variation of certain control parameter. A distinct delayed supercritical pitchfork bifurcation behavior can be discussed when the control item passes through bifurcation points periodically. This delayed dynamical behavior may terminate at different parameter areas, which leads to different spiking modes around different stable attractors (equilibriums, limit cycles, or chaotic attractors). In particular, the chaotic attractor may appear by Shilnikov connections or chaos boundary crisis, which leads to the occurrence of impressive chaotic bursting oscillations. Our findings enrich the study of bursting dynamics and deepen the understanding of some similar sorts of delayed bursting phenomena. Finally, some numerical simulations are included to illustrate the validity of our study.
Model Predictive Load Frequency Control of two-area Interconnected Time Delay Power System with TCSC
Deng, Yan; Liu, Wenze
2017-05-01
In order to reduce the influence of non-linear constraint and time delay on load frequency control of interconnected power system, this paper, based on Model Predictive Control (MPC), designed a load frequency control scheme for two-area interconnected power system with TCSC device. First, considering the Generation Rate Constraint (GRC) and time delay, this paper builds the dynamics model of two-area interconnected power system with Thyristor Controlled Series Compensation device (TCSC). Then the whole system is decomposed into two subsystems. And each subsystem has its own local area MPC controller. Second, collaborative control is implemented by integrating the control information (measurement value, predictive value, etc.) of subsystems’ MPC controllers into the local control goal. In the end, under consideration of physical constraints, the Matlab simulation is conducted. The calculation results showed that the MPC strategy has better dynamic performance and robustness compared to the traditional PI control.
Multifractal chaotic attractors in a system of delay-differential equations modeling road traffic.
Safonov, Leonid A.; Tomer, Elad; Strygin, Vadim V.; Ashkenazy, Yosef; Havlin, Shlomo
2002-12-01
We study a system of delay-differential equations modeling single-lane road traffic. The cars move in a closed circuit and the system's variables are each car's velocity and the distance to the car ahead. For low and high values of traffic density the system has a stable equilibrium solution, corresponding to the uniform flow. Gradually decreasing the density from high to intermediate values we observe a sequence of supercritical Hopf bifurcations forming multistable limit cycles, corresponding to flow regimes with periodically moving traffic jams. Using an asymptotic technique we find approximately small limit cycles born at Hopf bifurcations and numerically preform their global continuations with decreasing density. For sufficiently large delay the system passes to chaos following the Ruelle-Takens-Newhouse scenario (limit cycles-two-tori-three-tori-chaotic attractors). We find that chaotic and nonchaotic attractors coexist for the same parameter values and that chaotic attractors have a broad multifractal spectrum. (c) 2002 American Institute of Physics.
Directory of Open Access Journals (Sweden)
Chao Sun
2016-01-01
Full Text Available The problem of delay-dependent robust fault estimation for a class of Takagi-Sugeno (T-S fuzzy singular systems is investigated. By decomposing the delay interval into two unequal subintervals and with a new and tighter integral inequality transformation, an improved delay-dependent stability criterion is given in terms of linear matrix inequalities (LMIs to guarantee that the fuzzy singular system with time-varying delay is regular, impulse-free, and stable firstly. Then, based on this criterion, by considering the system fault as an auxiliary disturbance vector and constructing an appropriate fuzzy augmented system, a fault estimation observer is designed to ensure that the error dynamic system is regular, impulse-free, and robustly stable with a prescribed H∞ performance satisfied for all actuator and sensor faults simultaneously, and the obtained fault estimates can practically better depict the size and shape of the faults. Finally, numerical examples are given to show the effectiveness of the proposed approach.
Message-Passing Receiver for OFDM Systems over Highly Delay-Dispersive Channels
DEFF Research Database (Denmark)
Barbu, Oana-Elena; Manchón, Carles Navarro; Rom, Christian
2017-01-01
Propagation channels with maximum excess delay exceeding the duration of the cyclic prefix (CP) in OFDM systems cause intercarrier and intersymbol interference which, unless accounted for, degrade the receiver performance. Using tools from Bayesian inference and sparse signal reconstruction, we...... and future wireless communications systems. By enabling the OFDM receiver experiencing these harsh conditions to locally cancel the interference, our design circumvents the spectral efficiency loss incurred by extending the CP duration, otherwise a straightforward solution. Furthermore, it sets the premises...
Characteristics of a delay-line readout in a cylindrical drift chamber system
International Nuclear Information System (INIS)
Barber, R.; Ahmed, M.W.; Dzemidzic, M.; Empl, A.; Hungerford, E.V.; Lan, K.J.; Wilson, J.; Cooper, M.D.; Gagliardi, C.A.; Haim, D.; Kim, G.J.; Koetke, D.D.; Tribble, R.E.; Van Ausdeln, L.A.
2002-01-01
This paper reports on the design, construction, and operational characteristics of a delay-line readout implemented on the cathode foils of a cylindrical drift chamber system. The readout was used to determine the position of an event along the length of the 1.74 m drift wires in the MEGA detectors used at the Los Alamos Meson Physics Facility. The performance of the system is interpreted by comparison to a PSPICE simulation, and to simple analytical models
Yousef, Hamood. M.; Ismail, A. I. B. MD.
2017-08-01
Many attempts have been presented to solve the system of Delay Differential Equations (DDE) with Initial Value Problem. As a result, it has shown difficulties when getting the solution or cannot be solved. In this paper, a Variational Iteration Method is employed to find out an approximate solution for the system of DDE with initial value problems. The example illustrates convenient and an efficiency comparison with the exact solution.
Temperature Control of Gas Chromatograph Based on Switched Delayed System Techniques
Directory of Open Access Journals (Sweden)
Xiao-Liang Wang
2014-01-01
Full Text Available We address the temperature control problem of the gas chromatograph. We model the temperature control system of the gas chromatograph into a switched delayed system and analyze the stability by common Lyapunov functional technique. The PI controller parameters can be given based on the proposed linear matrix inequalities (LMIs condition and the designed controller can make the temperature of gas chromatograph track the reference signal asymptotically. An experiment is given to illustrate the effectiveness of the stability criterion.
[The plasma anion gap is a useful tool for evaluating children with metabolic acidosis].
Pivkovska, Julijana; Born, Peter; Kvist, Nina Eva; Nygaard, Ulrikka
2013-10-14
Metabolic acidosis occurs frequently in hospitalized children. The causes are many and often apparent from the history and physical examination. However, if the aetiology is unclear, the plasma anion gap is a useful tool for evaluating patients with metabolic acidosis. In this case report we describe two children in which the aetiology to the metabolic acidosis was unknown, one with normal anion gap who was diagnosed with renal tubular acidosis, and one with increased anion gap acidosis due to D-lactic acidosis.
Controller Design of Multiinput Multioutput Time-Delay Large-Scale System
Directory of Open Access Journals (Sweden)
Chia-Wei Lin
2013-01-01
Full Text Available The paper presents a novel feedback linearization controller of nonlinear multiinput multioutput time-delay large-scale systems to obtain both the tracking and almost disturbance decoupling (ADD performances. The significant contribution of this paper is to build up a control law such that the overall closed-loop system is stable for given initial condition and bounded tracking trajectory with the input-to-state-stability characteristic and almost disturbance decoupling performance. We have simulated the two-inverted-pendulum system coupled by a spring for networked control systems which has been used as a test bed for the study of decentralized control of large-scale systems.
Fuzzy model-based adaptive synchronization of time-delayed chaotic systems
International Nuclear Information System (INIS)
Vasegh, Nastaran; Majd, Vahid Johari
2009-01-01
In this paper, fuzzy model-based synchronization of a class of first order chaotic systems described by delayed-differential equations is addressed. To design the fuzzy controller, the chaotic system is modeled by Takagi-Sugeno fuzzy system considering the properties of the nonlinear part of the system. Assuming that the parameters of the chaotic system are unknown, an adaptive law is derived to estimate these unknown parameters, and the stability of error dynamics is guaranteed by Lyapunov theory. Numerical examples are given to demonstrate the validity of the proposed adaptive synchronization approach.
Bai, Mingsian R; Lin, Yuanpei; Lai, Jienwen
2002-02-01
Electronic delay has been a critical problem in active noise control (ANC) systems. This is true whether a feedforward structure or a feedback structure is adopted. In particular, excessive delays would create a causality problem in a feedforward ANC system of a finite-length duct. This paper suggests a multirate signal-processing approach for minimizing the electronic delay in the control loop. In this approach, digital controllers are required in decimation and interpolation of discrete-time signals. The computation efficiency is further enhanced by a polyphase method, where the phases of low-pass finite impulse response (FIR) filters must be carefully designed to avoid unnecessary delays. Frequency domain optimization procedures based on H1, H2, and Hinfinity norms, respectively, are utilized in the FIR filter design. The proposed method was implemented by using a floating-point digital signal processor. Experimental results showed that the multirate approach remains effective for suppressing a broadband (200-600 Hz) noise in a duct with a minimum upstream measurement microphone placement of 20 cm.
Robust stability of a class of uncertain fractional order linear systems with pure delay
Directory of Open Access Journals (Sweden)
Busłowicz Mikołaj
2015-06-01
Full Text Available The paper considers the robust stability problem of uncertain continuous-time fractional order linear systems with pure delay in the following two cases: a the state matrix is a linear convex combination of two known constant matrices, b the state matrix is an interval matrix. It is shown that the system is robustly stable if and only if all the eigenvalues of the state matrix multiplied by delay in power equal to fractional order are located in the open stability region in the complex plane. Parametric description of boundary of this region is derived. In the case a the necessary and sufficient computational condition for robust stability is established. This condition is given in terms of eigenvalue-loci of the state matrix, fractional order and time delay. In the case b the method for determining the rectangle with sides parallel to the axes of the complex plane in which all the eigenvalues of interval matrix are located is given and the sufficient condition for robust stability is proposed. This condition is satisfied if the rectangle multiplied by delay in power equal to fractional order lie in the stability region. The considerations are illustrated by numerical examples.
Ma, Huanfei; Leng, Siyang; Tao, Chenyang; Ying, Xiong; Kurths, Jürgen; Lai, Ying-Cheng; Lin, Wei
2017-07-01
Data-based and model-free accurate identification of intrinsic time delays and directional interactions is an extremely challenging problem in complex dynamical systems and their networks reconstruction. A model-free method with new scores is proposed to be generally capable of detecting single, multiple, and distributed time delays. The method is applicable not only to mutually interacting dynamical variables but also to self-interacting variables in a time-delayed feedback loop. Validation of the method is carried out using physical, biological, and ecological models and real data sets. Especially, applying the method to air pollution data and hospital admission records of cardiovascular diseases in Hong Kong reveals the major air pollutants as a cause of the diseases and, more importantly, it uncovers a hidden time delay (about 30-40 days) in the causal influence that previous studies failed to detect. The proposed method is expected to be universally applicable to ascertaining and quantifying subtle interactions (e.g., causation) in complex systems arising from a broad range of disciplines.
Mode Selection Rules for a Two-Delay System with Positive and Negative Feedback Loops
Takahashi, Kin'ya; Kobayashi, Taizo
2018-04-01
The mode selection rules for a two-delay system, which has negative feedback with a short delay time t1 and positive feedback with a long delay time t2, are studied numerically and theoretically. We find two types of mode selection rules depending on the strength of the negative feedback. When the strength of the negative feedback |α1| (α1 0), 2m + 1-th harmonic oscillation is well sustained in a neighborhood of t1/t2 = even/odd, i.e., relevant condition. In a neighborhood of the irrelevant condition given by t1/t2 = odd/even or t1/t2 = odd/odd, higher harmonic oscillations are observed. However, if |α1| is slightly less than α2, a different mode selection rule works, where the condition t1/t2 = odd/even is relevant and the conditions t1/t2 = odd/odd and t1/t2 = even/odd are irrelevant. These mode selection rules are different from the mode selection rule of the normal two-delay system with two positive feedback loops, where t1/t2 = odd/odd is relevant and the others are irrelevant. The two types of mode selection rules are induced by individually different mechanisms controlling the Hopf bifurcation, i.e., the Hopf bifurcation controlled by the "boosted bifurcation process" and by the "anomalous bifurcation process", which occur for |α1| below and above the threshold value αth, respectively.
Song, Zhibao; Zhai, Junyong
2018-02-22
This paper addresses the problem of adaptive output-feedback control for a class of switched stochastic time-delay nonlinear systems with uncertain output function, where both the control coefficients and time-varying delay are unknown. The drift and diffusion terms are subject to unknown homogeneous growth condition. By virtue of adding a power integrator technique, an adaptive output-feedback controller is designed to render that the closed-loop system is bounded in probability, and the state of switched stochastic nonlinear system can be globally regulated to the origin almost surely. A numerical example is provided to demonstrate the validity of the proposed control method. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.
Directory of Open Access Journals (Sweden)
Dongyan Chen
2015-01-01
Full Text Available This paper is concerned with the optimal Kalman filtering problem for a class of discrete stochastic systems with multiplicative noises and random two-step sensor delays. Three Bernoulli distributed random variables with known conditional probabilities are introduced to characterize the phenomena of the random two-step sensor delays which may happen during the data transmission. By using the state augmentation approach and innovation analysis technique, an optimal Kalman filter is constructed for the augmented system in the sense of the minimum mean square error (MMSE. Subsequently, the optimal Kalman filtering is derived for corresponding augmented system in initial instants. Finally, a simulation example is provided to demonstrate the feasibility and effectiveness of the proposed filtering method.
An optimal PID controller via LQR for standard second order plus time delay systems.
Srivastava, Saurabh; Misra, Anuraag; Thakur, S K; Pandit, V S
2016-01-01
An improved tuning methodology of PID controller for standard second order plus time delay systems (SOPTD) is developed using the approach of Linear Quadratic Regulator (LQR) and pole placement technique to obtain the desired performance measures. The pole placement method together with LQR is ingeniously used for SOPTD systems where the time delay part is handled in the controller output equation instead of characteristic equation. The effectiveness of the proposed methodology has been demonstrated via simulation of stable open loop oscillatory, over damped, critical damped and unstable open loop systems. Results show improved closed loop time response over the existing LQR based PI/PID tuning methods with less control effort. The effect of non-dominant pole on the stability and robustness of the controller has also been discussed. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.
Krein Space-Based H∞ Fault Estimation for Discrete Time-Delay Systems
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Xinmin Song
2014-01-01
Full Text Available This paper investigates the finite-time H∞ fault estimation problem for linear time-delay systems, where the delay appears in both state and measurement equations. Firstly, the design of finite horizon H∞ fault estimation is converted into a minimum problem of certain quadratic form. Then we introduce a stochastic system in Krein space, and a sufficient and necessary condition for the minimum is derived by applying innovation analysis approach and projection theory. Finally, a solution to the H∞ fault estimation is obtained by recursively computing a partial difference Riccati equation, which has the same dimension as the original system. Compared with the conventional augmented approach, the solving of a high dimension Riccati equation is avoided.
DEFF Research Database (Denmark)
Rasmussen, Martin Bøhme; Frost, Lars; Stengaard, Carsten
2014-01-01
percutaneous coronary intervention (PPCI)). There are limited data on achievable system delays in an optimal STEMI system of care using prehospital diagnosis to triage patients with STEMI directly to percutaneous coronary intervention (PCI) centres. We examined the proportion of tentative prehospital STEMI...... diagnoses established by telemedicine confirmed on hospital arrival, and we determined system delay in patients diagnosed before hospital arrival and triaged directly to the catheterisation laboratory. Methods: Design: Population-based follow-up study. Setting: Central Denmark Region. Participants: 15 992...... patients diagnosed using telemedicine. Results: During the study period, a tentative diagnosis of STEMI was established in 1061 patients, of whom 919 were triaged directly to the PCI centre. In 771 (84%) patients, a diagnosis of STEMI was confirmed. Patients transported
Ding, Da-Wei; Liu, Fang-Fang; Chen, Hui; Wang, Nian; Liang, Dong
2017-12-01
In this paper, a simplest fractional-order delayed memristive chaotic system is proposed in order to control the chaos behaviors via sliding mode control strategy. Firstly, we design a sliding mode control strategy for the fractional-order system with time delay to make the states of the system asymptotically stable. Then, we obtain theoretical analysis results of the control method using Lyapunov stability theorem which guarantees the asymptotic stability of the non-commensurate order and commensurate order system with and without uncertainty and an external disturbance. Finally, numerical simulations are given to verify that the proposed sliding mode control method can eliminate chaos and stabilize the fractional-order delayed memristive system in a finite time. Supported by the National Nature Science Foundation of China under Grant No. 61201227, Funding of China Scholarship Council, the Natural Science Foundation of Anhui Province under Grant No. 1208085M F93, 211 Innovation Team of Anhui University under Grant Nos. KJTD007A and KJTD001B
Research and Design on Trigger System Based on Acoustic Delay Correlation Filtering
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Zhiyong Lei
2014-01-01
Full Text Available In the exterior trajectory test, there usually needs a muzzle or a gun muzzle trigger system to be used as start signal for other measuring device, the customary trigger systems include off- target, infrared and acoustic detection system. But inherent echo reflection of the acoustic detection system makes the original signal of sound trigger submerged in various echo interference for bursts and shooting in a closed room, so that it can’t produce accurate trigger. In order to solve this defect, this paper analyzed the mathematical model based on acoustic delay correlation filtering in detail, then put forward the constraint condition with minimum path for delay correlation filtering. In this constraint condition, delay correlation filtering can do de-noising operation accurately. In order to verify accuracy and actual performance of the model, a MEMS sound sensor was used to implement mathematical model onto project, experimental results show that this system can filter out the every path sound bounce echoes of muzzle shock wave signal and produce the desired trigger signal accurately.
Distal Renal Tubular Acidosis, an Uncommonly diagnosed Cause of ...
African Journals Online (AJOL)
Five cases of distal renal tubular acidosis aged between 2½ weeks and 2½ months are described. The presenting features included lethargy, refusal to feed, high density of periodic respiration, vomiting and recurrent episodes of unexplained metabolic acidosis. A constant feature was failure to thrive despite caloric intakes ...
Response of hepatic amino acid consumption to chronic metabolic acidosis
Boon, L.; Blommaart, P. J.; Meijer, A. J.; Lamers, W. H.; Schoolwerth, A. C.
1996-01-01
In a previous paper, we showed that an inhibition of amino acid transport across the liver plasma membrane is responsible for the decrease in urea synthesis in acute metabolic acidosis. We have now studied the mechanism responsible for the decline in urea synthesis in chronic acidosis. Chronic
Dichloroacetate prevents hypoxic lactic acidosis in rats | Bosco ...
African Journals Online (AJOL)
acidosis, particularly in the cerebral tissue and the cerebrospinal fluid. Assess the efficiency of dichloroacetate in the prevention of hypoxia-induced lactic acidosis. We used adult rats, 3 months old, with a weight of 250-300 grams. Anesthesia was achieved by intraperitoneal injection of pentobarbital (Nembutal®), at the ...
Lactic acidosis, risk factors and predictive laboratory markers: a ...
African Journals Online (AJOL)
Background: The incidence of antiretroviral therapy (ART)-induced lactic acidosis and its associated mortality may be reduced by appropriate dosing, risk stratification and early detection. Objectives: To describe the epidemiology of lactic acidosis, define the risk factors and identify predictive laboratory markers in the context ...
Incidence and risk factors of linezolid-induced lactic acidosis
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Jae Hyoung Im
2015-02-01
Conclusions: Linezolid showed an association with treatment-related lactic acidosis. A longer duration of linezolid use (>6 weeks was one of the risk factors for metabolic acidosis. We suggest checking serum lactate concentrations regularly, especially in those on long-term use.
An unrecognised case of metabolic acidosis following neobladder augmentation cystoplasty
Directory of Open Access Journals (Sweden)
David Eldred-Evans
2015-01-01
Conclusion: Hyperchloremic metabolic acidosis is a well-established complication of urinary diversion. Patient with orthotopic neobladder with high residual urine and large capacity are at even higher risk of metabolic acidosis. This information should be clearly documented in the post-operative discharge documentation to ensure early recognition by non-specialists.
Treatment of acute non-anion gap metabolic acidosis.
Kraut, Jeffrey A; Kurtz, Ira
2015-02-01
Acute non-anion gap metabolic acidosis, also termed hyperchloremic acidosis, is frequently detected in seriously ill patients. The most common mechanisms leading to this acid-base disorder include loss of large quantities of base secondary to diarrhea and administration of large quantities of chloride-containing solutions in the treatment of hypovolemia and various shock states. The resultant acidic milieu can cause cellular dysfunction and contribute to poor clinical outcomes. The associated change in the chloride concentration in the distal tubule lumen might also play a role in reducing the glomerular filtration rate. Administration of base is often recommended for the treatment of acute non-anion gap acidosis. Importantly, the blood pH and/or serum bicarbonate concentration to guide the initiation of treatment has not been established for this type of metabolic acidosis; and most clinicians use guidelines derived from studies of high anion gap metabolic acidosis. Therapeutic complications resulting from base administration such as volume overload, exacerbation of hypertension and reduction in ionized calcium are likely to be as common as with high anion gap metabolic acidosis. On the other hand, exacerbation of intracellular acidosis due to the excessive generation of carbon dioxide might be less frequent than in high anion gap metabolic acidosis because of better tissue perfusion and the ability to eliminate carbon dioxide. Further basic and clinical research is needed to facilitate development of evidence-based guidelines for therapy of this important and increasingly common acid-base disorder.
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Linlin Ma
2016-01-01
Full Text Available This paper studies the stabilization problem for damping multimachine power system with time-varying delays and sector saturating actuator. The multivariable proportional plus derivative (PD type stabilizer is designed by transforming the problem of PD controller design to that of state feedback stabilizer design for a system in descriptor form. A new sufficient condition of closed-loop multimachine power system asymptomatic stability is derived based on the Lyapunov theory. Computer simulation of a two-machine power system has verified the effectiveness and efficiency of the proposed approach.
Distributed Interplanetary Delay/Disruption Tolerant Network (DTN) Monitor and Control System
Wang, Shin-Ywan
2012-01-01
The main purpose of Distributed interplanetary Delay Tolerant Network Monitor and Control System as a DTN system network management implementation in JPL is defined to provide methods and tools that can monitor the DTN operation status, detect and resolve DTN operation failures in some automated style while either space network or some heterogeneous network is infused with DTN capability. In this paper, "DTN Monitor and Control system in Deep Space Network (DSN)" exemplifies a case how DTN Monitor and Control system can be adapted into a space network as it is DTN enabled.
[Primary distal renal tubular acidosis in children in the South of Tunisia: study of 15 cases].
Kamoun, T; Sfaihi, L; Kamoun, F; Chabchoub, I; Aloulou, H; Hachicha, M
2013-04-01
primary distal renal tubular acidosis in children (RTA) is characterized by metabolic acidosis due to defect in urinary excretion of hydrogen (H+) in the distal tubular. To report the epidemiological, clinical, therapeutic and evolutionary of distal RTA in our patients. We conducted a retrospective study of all cases of distal RTA collected in the department of pediatrics of Hedi Chaker University hospital in the south of Tunisia, during a period of 23 years (1988-2010). We studied the epidemiological, clinical, biological, evolutionary and therapeutic data. During the study period 15 cases of distal RTA were collected. The average age was 6 months (1 month -2 years). Most common presenting symptoms were vomiting (8cases), failure to thrive (4cases), lack of appetite, polyuria-polydipsia syndrome (1case) and urinary infection (2cases). The clinical examination showed staturoponderal delay (9 cases), dehydration (6 cases), signs of rickets (3 cases) and polyuria (10 cases). Biological data showed high urine pH in the presence of metabolic acidosis in 11 cases, hypokalaemia in 10 cases and hypercalciuria in all cases. Urine acidification test with ammonium chloride was performed in 4 cases, the urinary pH was always higher than 5.5 in all cases. Ammoniuria performed in 9 cases was less than 40mmol/l. Radiological investigation objectified a nephrocalcinosis in fourteen patients and signs of rickets in three cases. Deafness was found in three patients. Genetic study performed in two cases showed mutation of ATP6V1B1 gene. The medical treatment involved an alkali load. Long-term outcome was favorable in 7 cases. The distal renal tubular acidosis is a rare pathology in our country but probably under diagnosed. The clinical gravity of this disease and the risk of evolution towards the terminal renal insufficiency justify an antenatal diagnosis to establish a neonatal management or propose a therapeutic interruption of the pregnancy if the distal RTA is associated with a
Kohrs, Christin; Hrabal, David; Angenstein, Nicole; Brechmann, André
2014-11-01
System response time research is an important issue in human-computer interactions. Experience with technical devices and general rules of human-human interactions determine the user's expectation, and any delay in system response time may lead to immediate physiological, emotional, and behavioral consequences. We investigated such effects on a trial-by-trial basis during a human-computer interaction by measuring changes in skin conductance (SC), heart rate (HR), and the dynamics of button press responses. We found an increase in SC and a deceleration of HR for all three delayed system response times (0.5, 1, 2 s). Moreover, the data on button press dynamics was highly informative since subjects repeated a button press with more force in response to delayed system response times. Furthermore, the button press dynamics could distinguish between correct and incorrect decisions and may thus even be used to infer the uncertainty of a user's decision. Copyright © 2014 Society for Psychophysiological Research.
Murguia, C; Fey, Rob H B; Nijmeijer, H
2015-02-01
We study the problem of controlled network synchronization of coupled semipassive systems in the case when the outputs (the coupling variables) and the inputs are subject to constant time-delay (as it is often the case in a networked context). Predictor-based dynamic output feedback controllers are proposed to interconnect the systems on a given network. Using Lyapunov-Krasovskii functional and the notion of semipassivity, we prove that under some mild assumptions, the solutions of the interconnected systems are globally ultimately bounded. Sufficient conditions on the systems to be interconnected, on the network topology, on the coupling dynamics, and on the time-delays that guarantee global state synchronization are derived. A local analysis is provided in which we compare the performance of our predictor-based control scheme against the existing static diffusive couplings available in the literature. We show (locally) that the time-delay that can be induced to the network may be increased by including the predictors in the loop. The results are illustrated by computer simulations of coupled Hindmarsh-Rose neurons.
Murguia, C.; Fey, Rob H. B.; Nijmeijer, H.
2015-02-01
We study the problem of controlled network synchronization of coupled semipassive systems in the case when the outputs (the coupling variables) and the inputs are subject to constant time-delay (as it is often the case in a networked context). Predictor-based dynamic output feedback controllers are proposed to interconnect the systems on a given network. Using Lyapunov-Krasovskii functional and the notion of semipassivity, we prove that under some mild assumptions, the solutions of the interconnected systems are globally ultimately bounded. Sufficient conditions on the systems to be interconnected, on the network topology, on the coupling dynamics, and on the time-delays that guarantee global state synchronization are derived. A local analysis is provided in which we compare the performance of our predictor-based control scheme against the existing static diffusive couplings available in the literature. We show (locally) that the time-delay that can be induced to the network may be increased by including the predictors in the loop. The results are illustrated by computer simulations of coupled Hindmarsh-Rose neurons.
Forced phase-locked response of a nonlinear system with time delay after Hopf bifurcation
International Nuclear Information System (INIS)
Ji, J.C.; Hansen, Colin H.
2005-01-01
The trivial equilibrium of a nonlinear autonomous system with time delay may become unstable via a Hopf bifurcation of multiplicity two, as the time delay reaches a critical value. This loss of stability of the equilibrium is associated with two coincident pairs of complex conjugate eigenvalues crossing the imaginary axis. The resultant dynamic behaviour of the corresponding nonlinear non-autonomous system in the neighbourhood of the Hopf bifurcation is investigated based on the reduction of the infinite-dimensional problem to a four-dimensional centre manifold. As a result of the interaction between the Hopf bifurcating periodic solutions and the external periodic excitation, a primary resonance can occur in the forced response of the system when the forcing frequency is close to the Hopf bifurcating periodic frequency. The method of multiple scales is used to obtain four first-order ordinary differential equations that determine the amplitudes and phases of the phase-locked periodic solutions. The first-order approximations of the periodic solutions are found to be in excellent agreement with those obtained by direct numerical integration of the delay-differential equation. It is also found that the steady state solutions of the nonlinear non-autonomous system may lose their stability via either a pitchfork or Hopf bifurcation. It is shown that the primary resonance response may exhibit symmetric and asymmetric phase-locked periodic motions, quasi-periodic motions, chaotic motions, and coexistence of two stable motions
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Yuqiang Luo
2013-01-01
Full Text Available This paper deals with a robust H∞ deconvolution filtering problem for discrete-time nonlinear stochastic systems with randomly occurring sensor delays. The delayed measurements are assumed to occur in a random way characterized by a random variable sequence following the Bernoulli distribution with time-varying probability. The purpose is to design an H∞ deconvolution filter such that, for all the admissible randomly occurring sensor delays, nonlinear disturbances, and external noises, the input signal distorted by the transmission channel could be recovered to a specified extent. By utilizing the constructed Lyapunov functional relying on the time-varying probability parameters, the desired sufficient criteria are derived. The proposed H∞ deconvolution filter parameters include not only the fixed gains obtained by solving a convex optimization problem but also the online measurable time-varying probability. When the time-varying sensor delays occur randomly with a time-varying probability sequence, the proposed gain-scheduled filtering algorithm is very effective. The obtained design algorithm is finally verified in the light of simulation examples.
Embedding the dynamics of a single delay system into a feed-forward ring
Klinshov, Vladimir; Shchapin, Dmitry; Yanchuk, Serhiy; Wolfrum, Matthias; D'Huys, Otti; Nekorkin, Vladimir
2017-10-01
We investigate the relation between the dynamics of a single oscillator with delayed self-feedback and a feed-forward ring of such oscillators, where each unit is coupled to its next neighbor in the same way as in the self-feedback case. We show that periodic solutions of the delayed oscillator give rise to families of rotating waves with different wave numbers in the corresponding ring. In particular, if for the single oscillator the periodic solution is resonant to the delay, it can be embedded into a ring with instantaneous couplings. We discover several cases where the stability of a periodic solution for the single unit can be related to the stability of the corresponding rotating wave in the ring. As a specific example, we demonstrate how the complex bifurcation scenario of simultaneously emerging multijittering solutions can be transferred from a single oscillator with delayed pulse feedback to multijittering rotating waves in a sufficiently large ring of oscillators with instantaneous pulse coupling. Finally, we present an experimental realization of this dynamical phenomenon in a system of coupled electronic circuits of FitzHugh-Nagumo type.
Application of Monte Carlo Method to Design a Delayed Neutron Counting System
International Nuclear Information System (INIS)
Ahn, Gil Hoon; Park, Il Jin; Kim, Jung Soo; Min, Gyung Sik
2006-01-01
The quantitative determination of fissile materials in environmental samples is becoming more and more important because of the increasing demand for nuclear nonproliferation. A number of methods have been proposed for screening environmental samples to measure fissile material content. Among them, delayed neutron counting (DNC) that is a nondestructive neutron activation analysis (NAA) method without chemical preparation has numerous advantages over other screening techniques. Fissile materials such as 239 Pu and 235 U can be made to undergo fission in the intense neutron field. Some of the fission products emit neutrons referred to as 'delayed neutrons' because they are emitted after a brief decay period following irradiation. Counting these delayed neutrons provides a simple method for determining the total fissile content in the sample. In delayed neutron counting, the chemical bonding environment of a fissile atom has no effect on the measurement process. Therefore, NAA is virtually immune to the 'matrix' effects that complicate other methods. The present study aims at design of a DNC system. In advance, neutron detector, gamma ray shielding material, and neutron thermalizing material should be selected. Next, investigation should be done to optimize the thickness of gamma ray shielding material and neutron thermalizing material using the MCNPX that is a well-known and widely-used Monte Carlo radiation transport code to find the following
Fault Detection for Non-Gaussian Stochastic Systems with Time-Varying Delay
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Tao Li
2013-01-01
Full Text Available Fault detection (FD for non-Gaussian stochastic systems with time-varying delay is studied. The available information for the addressed problem is the input and the measured output probability density functions (PDFs of the system. In this framework, firstly, by constructing an augmented Lyapunov functional, which involves some slack variables and a tuning parameter, a delay-dependent condition for the existence of FD observer is derived in terms of linear matrix inequality (LMI and the fault can be detected through a threshold. Secondly, in order to improve the detection sensitivity performance, the optimal algorithm is applied to minimize the threshold value. Finally, paper-making process example is given to demonstrate the applicability of the proposed approach.
Consensus of discrete-time multi-agent systems with adversaries and time delays
Wu, Yiming; He, Xiongxiong; Liu, Shuai; Xie, Lihua
2014-05-01
This paper studies the resilient asymptotic consensus problem for discrete-time multi-agent systems in the presence of adversaries and transmission delays. The network is assumed to have ? loyal agents and ? adversarial agents, and each loyal agent in the network has no knowledge of the network topology other than an upper bound on the number of adversarial agents in its neighborhood. For the considered networked system, only locally delayed information is available for each loyal agent, and also the information flow is directed and a control protocol using only local information is designed to guarantee the realization of consensus with respect to communication graph, which satisfies a featured network robustness. Numerical examples are finally given to demonstrate the effectiveness of theoretical results.
Directory of Open Access Journals (Sweden)
Wenzhen Gan
2013-01-01
Full Text Available This paper is concerned with the asymptotical behavior of solutions to the reaction-diffusion system under homogeneous Neumann boundary condition. By taking food ingestion and species' moving into account, the model is further coupled with Michaelis-Menten type functional response and nonlocal delay. Sufficient conditions are derived for the global stability of the positive steady state and the semitrivial steady state of the proposed problem by using the Lyapunov functional. Our results show that intraspecific competition benefits the coexistence of prey and predator. Furthermore, the introduction of Michaelis-Menten type functional response positively affects the coexistence of prey and predator, and the nonlocal delay is harmless for stabilities of all nonnegative steady states of the system. Numerical simulations are carried out to illustrate the main results.
Stability and Hopf Bifurcation for a Delayed Computer Virus Model with Antidote in Vulnerable System
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Zizhen Zhang
2017-01-01
Full Text Available A delayed computer virus model with antidote in vulnerable system is investigated. Local stability of the endemic equilibrium and existence of Hopf bifurcation are discussed by analyzing the associated characteristic equation. Further, direction of the Hopf bifurcation and stability of the bifurcating periodic solutions are investigated by using the normal form theory and the center manifold theorem. Finally, numerical simulations are presented to show consistency with the obtained results.
Adaptive Neural Control for a Class of Outputs Time-Delay Nonlinear Systems
Directory of Open Access Journals (Sweden)
Ruliang Wang
2012-01-01
Full Text Available This paper considers an adaptive neural control for a class of outputs time-delay nonlinear systems with perturbed or no. Based on RBF neural networks, the radius basis function (RBF neural networks is employed to estimate the unknown continuous functions. The proposed control guarantees that all closed-loop signals remain bounded. The simulation results demonstrate the effectiveness of the proposed control scheme.
Synchronization of Time-Delay Chaotic System in Presence of Noise
Directory of Open Access Journals (Sweden)
Min Lei
2012-09-01
Full Text Available Chaotic synchronization, as a key technique of chaotic secure communication, has received much attention in recent years. This paper proposes a nonlinear synchronization scheme for the time-delay chaotic system in the presence of noise. In this scheme, an integrator is introduced to suppress the influence of channel noise in the synchronization process. The experimental results demonstrate the effectiveness and feasibility of the proposed scheme which is strongly robust against noises, especially the high-frequency noises.
Bifurcation analysis in delayed feedback Jerk systems and application of chaotic control
International Nuclear Information System (INIS)
Zheng Baodong; Zheng Huifeng
2009-01-01
Jerk systems with delayed feedback are considered. Firstly, by employing the polynomial theorem to analyze the distribution of the roots to the associated characteristic equation, the conditions of ensuring the existence of Hopf bifurcation are given. Secondly, the stability and direction of the Hopf bifurcation are determined by applying the normal form method and center manifold theorem. Finally, the application to chaotic control is investigated, and some numerical simulations are carried out to illustrate the obtained results.
2014-01-01
This paper provides improved time delay-dependent stability criteria for multi-input and multi-output (MIMO) network control systems (NCSs) with nonlinear perturbations. Without the stability assumption on the neutral operator after the descriptor approach, the new proposed stability theory is less conservative than the existing stability condition. Theoretical proof is given in this paper to demonstrate the effectiveness of the proposed stability condition. PMID:24744679
A predator-prey system with stage-structure for predator and nonlocal delay
DEFF Research Database (Denmark)
Lin, Z.G.; Pedersen, Michael; Zhang, Lai
2010-01-01
This paper deals with the behavior of solutions to the reaction-diffusion system under homogeneous Neumann boundary condition, which describes a prey-predator model with nonlocal delay. Sufficient conditions for the global stability of each equilibrium are derived by the Lyapunov functional...... and the results show that the introduction of stage-structure into predator positively affects the coexistence of prey and predator. Numerical simulations are performed to illustrate the results....
Phase-Shift Cyclic-Delay Diversity for MIMO OFDM Systems
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Young-Han Nam
2010-01-01
Full Text Available Phase-shift cyclic-delay diversity (PS CDD scheme and space-frequency-block-code (SFBC PS CDD are developed for multiple-input-multiple-output (MIMO orthogonal frequency division multiplexing (OFDM systems. The proposed PS CDD scheme preserves the diversity advantage of traditional CDD in uncorrelated multiantenna channels, and furthermore removes frequency-selective nulling problem of the traditional CDD in correlated multiantenna channels.
Liu, Hexing; Tomoda, Fumihiro; Koike, Tsutomu; Ohara, Maiko; Nakagawa, Taizo; Kagitani, Satoshi; Inoue, Hiroshi
2011-01-01
We report herein a 27-year-old male case of inherited distal renal tubular acidosis complicated with renal diabetes insipidus, the symptoms of which were aggravated by the occurrence of diabetes mellitus. At 2 months after birth, he was diagnosed as having inherited distal renal tubular acidosis and thereafter supplementation of both potassium and alkali was started to treat his hypokalemia and metabolic acidosis. At the age of 4 years, calcification of the bilateral renal medulla was detected by computed tomography. Subsequently his urinary volume gradually increased and polyuria of approximately 4 L/day persisted. At the age of 27 years, he became fond of sugar-sweetened drinks and also often forgot to take the medicine. He was admitted to our hospital due to polyuria of more than 10 L day, muscle weakness and gait disturbance. Laboratory tests disclosed worsening of both hypokalemia and metabolic acidosis in addition to severe hyperglycemia. It seemed likely that occurrence of diabetes mellitus and cessation of medications can induce osmotic diuresis and aggravate hypokalemia and metabolic acidosis. Consequently, severe dehydration, hypokalemia-induced damage of his urinary concentration ability and enhancement of the renin angiotensin system occurred and thereby possibly worsened his hypokalemia and metabolic acidosis. As normalization of hyperglycemia and metabolic acidosis might have exacerbated hypokalemia further, dehydration and hypokalemia were treated first. Following intensive treatment, these abnormalities were improved, but polyuria persisted. Elevated plasma antidiuretic hormone (12.0 pg/mL) and deficit of renal responses to antidiuretic hormone suggested that the polyuria was attributable to the preexisting renal diabetes insipidus possibly caused by bilateral renal medulla calcification. Thiazide diuretic or nonsteroidal anti-inflammatory drugs were not effective for the treatment of diabetes insipidus in the present case.
International Nuclear Information System (INIS)
Feng Cunfang; Guan Wei; Wang Yinghai
2013-01-01
We investigate different types of projective (projective-anticipating, projective and projective-lag) synchronization in unidirectionally nonlinearly coupled time-delayed chaotic systems with variable time delays. Based on the Krasovskii–Lyapunov approach, we find both the existence and sufficient stability conditions, using a general class of time-delayed chaotic systems related to optical bistable or hybrid optical bistable devices. Our method has the advantage that it requires only one nonlinearly coupled term to achieve different types of projective synchronization in time-delayed chaotic systems with variable time delays. Compared with other existing works, our result provides an easy way to achieve projective-anticipating, projective and projective-lag synchronization. Numerical simulations of the Ikeda system are given to demonstrate the validity of the proposed method. (paper)
Stability and periodicity of solutions for delay dynamic systems on time scales
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Zhi-Qiang Zhu
2014-04-01
Full Text Available This article concerns the stability and periodicity of solutions to the delay dynamic system $$ x^{\\triangle}(t=A(t x(t + F(t, x(t, x(g(t+C(t $$ on a time scale. By the inequality technique for vectors, we obtain some stability criteria for the above system. Then, by using the Horn fixed point theorem, we present some conditions under which our system is asymptotically periodic and its periodic solution is unique. In particular, the periodic solution is positive under proper assumptions.
Finite-Time Stabilization of Uncertain Switched Positive Linear Systems with Time-Varying Delays
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Tianjian Yu
2015-01-01
Full Text Available This paper is concerned with finite-time stabilization (FTS analysis for a class of uncertain switched positive linear systems with time-varying delays. First, a new definition of finite-time boundedness (FTB is introduced for switched positive system. This definition can simplify FTS analysis. Taking interval and polytopic uncertainties into account, a robust state feedback controller is built such that the switched positive linear system is finite-time bounded. Finally, an example is employed to illustrate the validities of obtained results.
DEFF Research Database (Denmark)
Nielsen, Kræn V.; Blanke, Mogens; Eriksson, Lars
2017-01-01
Taking offspring in a problem of ship emission reduction by exhaust gas recirculation control for large diesel engines, an underlying generic estimation challenge is formulated as a problem of joint state and parameter estimation for a class of multiple-input single-output Hammerstein systems...... with first order dynamics, sensor delay and a bounded time-varying parameter in the nonlinear part. The paper suggests a novel scheme for this estimation problem that guarantees exponential convergence to an interval that depends on the sensitivity of the system. The system is allowed to be nonlinear...
Directory of Open Access Journals (Sweden)
Il Young Song
2015-01-01
Full Text Available This paper focuses on estimation of a nonlinear function of state vector (NFS in discrete-time linear systems with time-delays and model uncertainties. The NFS represents a multivariate nonlinear function of state variables, which can indicate useful information of a target system for control. The optimal nonlinear estimator of an NFS (in mean square sense represents a function of the receding horizon estimate and its error covariance. The proposed receding horizon filter represents the standard Kalman filter with time-delays and special initial horizon conditions described by the Lyapunov-like equations. In general case to calculate an optimal estimator of an NFS we propose using the unscented transformation. Important class of polynomial NFS is considered in detail. In the case of polynomial NFS an optimal estimator has a closed-form computational procedure. The subsequent application of the proposed receding horizon filter and nonlinear estimator to a linear stochastic system with time-delays and uncertainties demonstrates their effectiveness.
Nonlinear Control and Synchronization with Time Delays of Multiagent Robotic Systems
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Yassine Bouteraa
2011-01-01
Full Text Available We investigate the cooperative control and global asymptotic synchronization Lagrangian system groups, such as industrial robots. The proposed control approach works to accomplish multirobot systems synchronization under an undirected connected communication topology. The control strategy is to synchronize each robot in position and velocity to others robots in the network with respect to the common desired trajectory. The cooperative robot network only requires local neighbor-to-neighbor information exchange between manipulators and does not assume the existence of an explicit leader in the team. It is assumed that network robots have the same number of joints and equivalent joint work spaces. A combination of the lyapunov-based technique and the cross-coupling method has been used to establish the multirobot system asymptotic stability. The developed control combines trajectory tracking and coordination algorithms. To address the time-delay problem in the cooperative network communication, the suggested synchronization control law is shown to synchronize multiple robots as well as to track given trajectory, taking into account the presence of the time delay. To this end, Krasovskii functional method has been used to deal with the delay-dependent stability problem.
Tuning of IMC based PID controllers for integrating systems with time delay.
Kumar, D B Santosh; Padma Sree, R
2016-07-01
Design of Proportional Integral and Derivative (PID) controllers based on IMC principles for various types of integrating systems with time delay is proposed. PID parameters are given in terms of process model parameters and a tuning parameter. The tuning parameter is IMC filter time constant. In the present work, the IMC filter (Q) is chosen in such a manner that the order of the denominator of IMC controller is one less than the order of the numerator. The IMC filter time constant (λ) is tuned in such a way that a good compromise is made between performance and robustness for both servo and regulatory problems. To improve servo response of the controller a set point filter is designed such that the closed loop response is similar to that of first order plus time delay system. The proposed controller design method is applied to various transfer function models and to the non-linear model equations of jacketed CSTR to demonstrate its applicability and effectiveness. The performance of the proposed controller is compared with the recently reported methods in terms of IAE and ITAE. The smooth functioning of the controller is determined in terms of total variation and compared with recently reported methods. Simulation studies are carried out on various integrating systems with time delay to show the effectiveness and superiority of the proposed controllers. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.
The giant acoustic atom - a single quantum system with a deterministic time delay
Guo, Lingzhen; Grimsmo, Arne; Frisk Kockum, Anton; Pletyukhov, Mikhail; Johansson, Göran
2017-04-01
We investigate the quantum dynamics of a single transmon qubit coupled to surface acoustic waves (SAWs) via two distant connection points. Since the acoustic speed is five orders of magnitude slower than the speed of light, the travelling time between the two connection points needs to be taken into account. Therefore, we treat the transmon qubit as a giant atom with a deterministic time delay. We find that the spontaneous emission of the system, formed by the giant atom and the SAWs between its connection points, initially follows a polynomial decay law instead of an exponential one, as would be the case for a small atom. We obtain exact analytical results for the scattering properties of the giant atom up to two-phonon processes by using a diagrammatic approach. The time delay gives rise to novel features in the reflection, transmission, power spectra, and second-order correlation functions of the system. Furthermore, we find the short-time dynamics of the giant atom for arbitrary drive strength by a numerically exact method for open quantum systems with a finite-time-delay feedback loop. L. G. acknowledges financial support from Carl-Zeiss Stiftung (0563-2.8/508/2).
Piotrowska, M. J.; Bodnar, M.
2018-01-01
We present a generalisation of the mathematical models describing the interactions between the immune system and tumour cells which takes into account distributed time delays. For the analytical study we do not assume any particular form of the stimulus function describing the immune system reaction to presence of tumour cells but we only postulate its general properties. We analyse basic mathematical properties of the considered model such as existence and uniqueness of the solutions. Next, we discuss the existence of the stationary solutions and analytically investigate their stability depending on the forms of considered probability densities that is: Erlang, triangular and uniform probability densities separated or not from zero. Particular instability results are obtained for a general type of probability densities. Our results are compared with those for the model with discrete delays know from the literature. In addition, for each considered type of probability density, the model is fitted to the experimental data for the mice B-cell lymphoma showing mean square errors at the same comparable level. For estimated sets of parameters we discuss possibility of stabilisation of the tumour dormant steady state. Instability of this steady state results in uncontrolled tumour growth. In order to perform numerical simulation, following the idea of linear chain trick, we derive numerical procedures that allow us to solve systems with considered probability densities using standard algorithm for ordinary differential equations or differential equations with discrete delays.
Munir, Abid; Xin, Xiang-jun; Liu, Bo; Latif, Abdul; Hussain, Aftab; Niazi, Shahab Ahmad
2012-03-01
In order to achieve higher spectral efficiency, mode division multiplexing (MDM) in few-mode fibers is a new research area. The idea faces lots of technical issues including intermodal delay and mode coupling which limit the achievable length of the system. This paper is designated to complete the analysis of intermodal delay in step-index few-mode fibers. We analyze numerically all the parameters of fiber, which could impact intermodal delay in few-mode fibers and identify the conditions which can increase the number of multiplex modes without significant increase in maximum intermodal delay.
Directory of Open Access Journals (Sweden)
Chiang Cheng Chiang
2013-01-01
Full Text Available An observer-based robust adaptive fuzzy control scheme is presented to tackle the problem of the robust stability and the tracking control for a class of multiinput multioutput (MIMO nonlinear uncertain systems with delayed output. Because the nonlinear system functions and the uncertainties of the controlled system including structural uncertainties are supposed to be unknown, fuzzy logic systems are utilized to approximate these nonlinear system functions and the upper bounded functions of the uncertainties. Moreover, the upper bound of uncertainties caused by these fuzzy modeling errors is also estimated. In addition, the state observer based on state variable filters is designed to estimate all states which are not available for measurement in the controlled system. By constructing an appropriate Lyapunov function and using strictly positive-real (SPR stability theorem, the proposed robust adaptive fuzzy controller not only guarantees the robust stability of a class of multivariable nonlinear uncertain systems with delayed output but also maintains a good tracking performance. Finally, some simulation results are illustrated to verify the effectiveness of the proposed control approach.
A Control Method to Balance the Efficiency and Reliability of a Time-Delayed Pump-Valve System
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Zhounian Lai
2016-01-01
Full Text Available The efficiency and reliability of pumps are highly related to their operation conditions. The concept of the optimization pump operation conditions is to adjust the operation point of the pump to obtain higher reliability at the cost of lower system efficiency using a joint regulation of valve and frequency convertor. This paper realizes the control of the fluid conveying system based on the optimization results. The system is a nonlinear Multi-Input Multioutput (MIMO system with time delays. In this paper, the time delays are separated from the system. The delay-free system is linearized using input-output linearization and controlled using a sliding mode method. A modified Smith predictor is used to compensate time delays of the system. The control strategy is validated to be effective on the test bench. The comparison of energy consumption and operation point deviation between conventional speed regulation and the new method is presented.
Directory of Open Access Journals (Sweden)
Shengwei Yao
2014-01-01
Full Text Available A FitzHugh-Nagumo (FHN neural system with multiple delays has been proposed. The number of equilibrium point is analyzed. It implies that the neural system exhibits a unique equilibrium and three ones for the different values of coupling weight by employing the saddle-node bifurcation of nontrivial equilibrium point and transcritical bifurcation of trivial one. Further, the stability of equilibrium point is studied by analyzing the corresponding characteristic equation. Some stability criteria involving the multiple delays and coupling weight are obtained. The results show that the neural system exhibits the delay-independence and delay-dependence stability. Increasing delay induces the stability switching between resting state and periodic activity in some parameter regions of coupling weight. Finally, numerical simulations are taken to support the theoretical results.
Experimental Study on Communication Delay of Powertrain System of Plug-In Hybrid Electric Vehicles
Directory of Open Access Journals (Sweden)
Dafang Wang
2013-01-01
Full Text Available In order to contrast and analyze the real-time performance of the powertrain system of a plug-in hybrid electric vehicle, a mathematical model of the system delay is established under the circumstances that the transmission adopts the CAN (controller area network protocol and the TTCAN (time-triggered CAN protocol, respectively, and the interior of the controller adopts the foreground-background mode and the OSEK mode respectively. In addition, an experimental platform is developed to test communication delays of messages under 4 different implementation models. The 4 models are testing under the CAN protocol while the controller interior adopts the foreground-background mode; testing under the CAN protocol while the controller interior adopts the OSEK mode; testing under the TTCAN protocol while the controller interior adopts the foreground-background mode, and testing under the TTCAN protocol while the controller interior adopts the OSEK mode. The theoretical and testing results indicate that the communication delay of the OSEK mode is a little longer than the one of the foreground-background mode. Moreover, compared with the CAN protocol, the periodic message has a better real-time performance under the TTCAN protocol, while the nonperiodic message has a worse one.
ADL ORVIS: an air-delay-leg, line-imaging optically recording velocity interferometer system.
Trott, Wayne M; Castañeda, Jaime N; Cooper, Marcia A
2014-04-01
An interferometry system that enables acquisition of spatially resolved velocity-time profiles with very high velocity sensitivity has been designed and applied to two diverse, instructive experimental problems: (1) measurement of low-amplitude reverberations in laser-driven flyer plates and (2) measurement of ramp-wave profiles in symmetric impact studies of fused silica. The delay leg in this version of a line-imaging optically recording velocity interferometer system (ORVIS) consists of a long air path that includes relay optics to transmit the optical signal through the interferometer cavity. Target image quality from the delay path at the image recombination plane is preserved by means of a compact and flexible optical design utilizing two parabolic reflectors (serving as the relay optics) in a folded path. With an instrument tuned to a velocity per fringe constant of 22.4 m s(-1) fringe(-1), differences of 1-2 m s(-1) across the probe line segment can be readily distinguished. Measurements that capture small spatial variations in flyer velocity are presented and briefly discussed. In the fused silica impact experiments, the ramp-wave profile observed by this air-delay instrument compares favorably to the profile recorded simultaneously by a conventional line-imaging ORVIS.
Force-linearization closure for non-Markovian Langevin systems with time delay
Loos, Sarah A. M.; Klapp, Sabine H. L.
2017-07-01
This paper is concerned with the Fokker-Planck (FP) description of classical stochastic systems with discrete time delay. The non-Markovian character of the corresponding Langevin dynamics naturally leads to a coupled infinite hierarchy of FP equations for the various n -time joint distribution functions. Here, we present an approach to close the hierarchy at the one-time level based on a linearization of the deterministic forces in all members of the hierarchy starting from the second one. This leads to a closed equation for the one-time probability density in the steady state. Considering two generic nonlinear systems, a colloidal particle in a sinusoidal or bistable potential supplemented by a linear delay force, we demonstrate that our approach yields a very accurate representation of the density as compared to quasiexact numerical results from direct solution of the Langevin equation. Moreover, the results are significantly improved against those from a small-delay approximation and a perturbation-theoretical approach. We also discuss the possibility of accessing transport-related quantities, such as escape times, based on an additional Kramers approximation. Our approach applies to a wide class of models with nonlinear deterministic forces.
A detection system for very low-energy protons from β-delayed proton decay
International Nuclear Information System (INIS)
Spiridon, A.; Pollacco, E.; Trache, L.; Simmons, E.; McCleskey, M.; Roeder, B. T.; Tribble, R. E.; Pascovici, G.; Riallot, M.; Mols, J. P.; Kebbiri, M.
2012-01-01
We have recently developed a gas based detection system called AstroBox, motivated by nuclear astrophysics studies. The goal was to detect very low-energy protons from β-delayed p-decay with reduced beta background and improved energy resolution. The detector was tested using the β-delayed proton-emitter 23Al previously studied with a set-up based on thin double-sided Si strip detectors. The proton spectrum obtained with AstroBox showed no beta background down to ∼80 keV. The low energy (206 keV, 267 keV) proton peaks were positively identified, well separated, and the resolution was improved.
Ma, Chao; Shi, Peng; Zhao, Xudong; Zeng, Qingshuang
2015-06-01
This paper investigates the consensus problem of multiple Euler-Lagrange systems under directed topology. Unlike the common assumptions on continuous-time information exchanges, a more realistic sampled-data communication strategy is proposed with probabilistic occurrence of time-varying delays. Both of the sampling period and the delays are assumed to be time-varying, which is more general in some practical situations. In addition, the relative coordinate derivative information is not required in the distributed controllers such that the communication network burden can be further reduced. In particular, a distinct feature of the proposed scheme lies in the fact that it can effectively reduce the energy consumption. By employing the stochastic analysis techniques, sufficient conditions are established to guarantee that the consensus can be achieved. Finally, a numerical example is provided to illustrate the applicability and benefits of the theoretical results.
Minimization of Delay Costs in the Realization of Production Orders in Two-Machine System
Dylewski, Robert; Jardzioch, Andrzej; Dworak, Oliver
2018-03-01
The article presents a new algorithm that enables the allocation of the optimal scheduling of the production orders in the two-machine system based on the minimum cost of order delays. The formulated algorithm uses the method of branch and bounds and it is a particular generalisation of the algorithm enabling for the determination of the sequence of the production orders with the minimal sum of the delays. In order to illustrate the proposed algorithm in the best way, the article contains examples accompanied by the graphical trees of solutions. The research analysing the utility of the said algorithm was conducted. The achieved results proved the usefulness of the proposed algorithm when applied to scheduling of orders. The formulated algorithm was implemented in the Matlab programme. In addition, the studies for different sets of production orders were conducted.
Sodium Bicarbonate Therapy in Patients with Metabolic Acidosis
Adeva-Andany, María M.; Fernández-Fernández, Carlos; Mouriño-Bayolo, David; Castro-Quintela, Elvira; Domínguez-Montero, Alberto
2014-01-01
Metabolic acidosis occurs when a relative accumulation of plasma anions in excess of cations reduces plasma pH. Replacement of sodium bicarbonate to patients with sodium bicarbonate loss due to diarrhea or renal proximal tubular acidosis is useful, but there is no definite evidence that sodium bicarbonate administration to patients with acute metabolic acidosis, including diabetic ketoacidosis, lactic acidosis, septic shock, intraoperative metabolic acidosis, or cardiac arrest, is beneficial regarding clinical outcomes or mortality rate. Patients with advanced chronic kidney disease usually show metabolic acidosis due to increased unmeasured anions and hyperchloremia. It has been suggested that metabolic acidosis might have a negative impact on progression of kidney dysfunction and that sodium bicarbonate administration might attenuate this effect, but further evaluation is required to validate such a renoprotective strategy. Sodium bicarbonate is the predominant buffer used in dialysis fluids and patients on maintenance dialysis are subjected to a load of sodium bicarbonate during the sessions, suffering a transient metabolic alkalosis of variable severity. Side effects associated with sodium bicarbonate therapy include hypercapnia, hypokalemia, ionized hypocalcemia, and QTc interval prolongation. The potential impact of regular sodium bicarbonate therapy on worsening vascular calcifications in patients with chronic kidney disease has been insufficiently investigated. PMID:25405229
Early anion gap metabolic acidosis in acetaminophen overdose.
Zein, Joe G; Wallace, David J; Kinasewitz, Gary; Toubia, Nagib; Kakoulas, Christine
2010-09-01
The study aimed to determine the incidence and clinical significance of early high (>15 mEq/L) anion gap metabolic acidosis in acetaminophen (APAP) overdose. A retrospective review of a cohort of 74 patients presenting within 24 hours of APAP overdose was conducted. Early high anion gap metabolic acidosis was present in 41% of patients on admission and persisted for 1.5 ± 0.1 days. The anion gap was associated with an elevated lactate level (4.5 ± 1 mmol/L) (r(2) = 0.66, P anion gap had a higher incidence of confusion (48% vs 3%; P anion gap metabolic acidosis was found in the absence of shock or liver failure. All patients were treated with N-acetylcysteine and, despite the early high anion gap metabolic acidosis, none developed hepatic failure or hypoglycemia. Early high anion gap metabolic acidosis in patients with APAP overdose is self-limited and does not predict clinical or laboratory outcomes. Persistent or late metabolic acidosis in the absence of liver failure is not likely due to APAP and should prompt a search for other causes of metabolic acidosis. Finally, APAP overdose should be considered in patients presenting to the emergency department with altered mental status, as this is a treatable condition when detected early. Copyright © 2010 Elsevier Inc. All rights reserved.
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Lun Zhai
2014-01-01
Full Text Available A parametric learning based robust iterative learning control (ILC scheme is applied to the time varying delay multiple-input and multiple-output (MIMO linear systems. The convergence conditions are derived by using the H∞ and linear matrix inequality (LMI approaches, and the convergence speed is analyzed as well. A practical identification strategy is applied to optimize the learning laws and to improve the robustness and performance of the control system. Numerical simulations are illustrated to validate the above concepts.
Existence and exponential stability of traveling waves for delayed reaction-diffusion systems
Hsu, Cheng-Hsiung; Yang, Tzi-Sheng; Yu, Zhixian
2018-03-01
The purpose of this work is to investigate the existence and exponential stability of traveling wave solutions for general delayed multi-component reaction-diffusion systems. Following the monotone iteration scheme via an explicit construction of a pair of upper and lower solutions, we first obtain the existence of monostable traveling wave solutions connecting two different equilibria. Then, applying the techniques of weighted energy method and comparison principle, we show that all solutions of the Cauchy problem for the considered systems converge exponentially to traveling wave solutions provided that the initial perturbations around the traveling wave fronts belong to a suitable weighted Sobolev space.
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Qi Wang
2012-01-01
Full Text Available This paper deals with the oscillations of numerical solutions for the nonlinear delay differential equations in physiological control systems. The exponential θ-method is applied to p′(t=β0ωμp(t−τ/(ωμ+pμ(t−τ−γp(t and it is shown that the exponential θ-method has the same order of convergence as that of the classical θ-method. Several conditions under which the numerical solutions oscillate are derived. Moreover, it is proven that every nonoscillatory numerical solution tends to positive equilibrium of the continuous system. Finally, the main results are illustrated with numerical examples.
Acidosis láctica: algunas consideraciones
Maia Heredero Valdés; Vivian R. Mena Miranda; Raúl L. Riverón Corteguera
2000-01-01
La hiperlactacidemia significa clínicamente problemas para los pacientes. La acidosis láctica es un trastorno ácido-básico consecutivo a la acumulación del ácido láctico, el cual se comporta en el nivel celular, como la contrapartida reducida del ácido pirúvico. Este último, resulta de la degradación de la glucosa en el citosol, proceso que se realiza de manera anaoeróbica y que puede culminar en CO2 H2O si sigue la vía del ácido cítrico de Krebs. El diagnóstico de esta entidad se confirma al...
Refractory rickets caused by mild distal renal tubular acidosis
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Ji-Ho Lee
2013-09-01
Full Text Available Type I (distal renal tubular acidosis (RTA is a disorder associated with the failure to excrete hydrogen ions from the distal renal tubule. It is characterized by hyperchloremic metabolic acidosis, an abnormal increase in urine pH, reduced urinary excretion of ammonium and bicarbonate ions, and mild deterioration in renal function. Hypercalciuria is common in distal RTA because of bone resorption, which increases as a buffer against metabolic acidosis. This can result in intractable rickets. We describe a case of distal RTA with nephrocalcinosis during follow-up of rickets in a patient who presented with clinical manifestations of short stature, failure to thrive, recurrent vomiting, dehydration, and irritability.
Concomitant hypercalcemia and hyperammonemia associated with distal renal tubular acidosis.
Saini, Arun; Karmakar, Swati A; Kannikeswaran, Nirupama
2012-03-01
We describe an infant with concomitant hypercalcemia and hyperammonemia associated with nonanion gap metabolic acidosis secondary to distal renal tubular acidosis (dRTA). The levels of both serum calcium and ammonia rapidly normalized with the correction of dehydration and metabolic acidosis. To the best of our knowledge, there has been only one previous case report of concomitant hypercalcemia and hyperammonemia associated with dRTA that has been reported in the literature. We describe the causes and emergent management of hypercalcemia and review the possible mechanisms of this rare association with dRTA.
Metformin-associated lactic acidosis in a peritoneal dialysis patient
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Najlaa Almaleki
2015-01-01
Full Text Available Metformin is one of the commonly used drugs in type-2 diabetes mellitus. It reduces glucose levels by increasing insulin sensitivity, reducing hepatic glucose release and increasing muscle uptake. One of the serious complications associated with metformin use is lactic acidosis, and it is associated with high morbidity and mortality. This is more likely to happen in patients with renal failure due to reduced clearance. International guidelines recommend discontinuing metformin in advanced renal failure. We report a case of metformin-associated lactic acidosis in a patient with end-stage renal disease on peritoneal dialysis. The patient presented with severe lactic acidosis, which was successfully treated with hemodialysis.
Distal renal tubular acidosis and amelogenesis imperfecta: A rare association
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P Ravi
2013-01-01
Full Text Available Renal tubular acidosis (RTA is characterized by a normal anion gap with hyperchloremic metabolic acidosis. Primary distal RTA (type I is the most common RTA in children. Childhood presentation of distal RTA includes vomiting, failure to thrive, metabolic acidosis, and hypokalemia. Amelogenesis imperfecta (AI represents a condition where the dental enamel and oral tissues are affected in an equal manner resulting in the hypoplastic or hypopigmented teeth. We report a 10-year-old girl, previously asymptomatic presented with the hypokalemic paralysis and on work-up found out to have type I RTA. The discoloration of teeth and enamel was diagnosed as AI.
A Quick Reference on High Anion Gap Metabolic Acidosis.
Funes, Silvia; de Morais, Helio Autran
2017-03-01
High anion gap (AG) metabolic acidoses can be identified by a decrease in pH, decrease in HCO 3 - or base excess, and an increased AG. The AG represents the difference between unmeasured cations and unmeasured anions; it increases secondary to the accumulation of anions other than bicarbonate and chloride. The most common causes of high AG acidosis are renal failure, diabetic ketoacidosis, and lactic acidosis. Severe increases in concentration of phosphorus can cause hyperphosphatemic acidosis. Copyright © 2016 Elsevier Inc. All rights reserved.
Zhong, Zhixiong; Zhu, Yanzheng; Ahn, Choon Ki
2018-03-20
In this paper, we address the problem of reachable set estimation for continuous-time Takagi-Sugeno (T-S) fuzzy systems subject to unknown output delays. Based on the reachable set concept, a new controller design method is also discussed for such systems. An effective method is developed to attenuate the negative impact from the unknown output delays, which likely degrade the performance/stability of systems. First, an augmented fuzzy observer is proposed to capacitate a synchronous estimation for the system state and the disturbance term owing to the unknown output delays, which ensures that the reachable set of the estimation error is limited via the intersection operation of ellipsoids. Then, a compensation technique is employed to eliminate the influence on the system performance stemmed from the unknown output delays. Finally, the effectiveness and correctness of the obtained theories are verified by the tracking control of autonomous underwater vehicles. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.
Sabahi, Kamel; Ghaemi, Sehraneh; Liu, Jianxing; Badamchizadeh, Mohammad Ali
2017-11-01
In this paper a new indirect type-2 fuzzy neural network predictive (T2FNNP) controller has been proposed for a class of nonlinear systems with input-delay in presence of unknown disturbance and uncertainties. In this method, the predictor has been utilized to estimate the future state variables of the controlled system to compensate for the time-varying delay. The T2FNN is used to estimate some unknown nonlinear functions to construct the controller. By introducing a new adaptive compensator for the predictor and controller, the effects of the external disturbance, estimation errors of the unknown nonlinear functions, and future sate estimation errors have been eliminated. In the proposed method, using an appropriate Lyapunov function, the stability analysis as well as the adaptation laws is carried out for the T2FNN parameters in a way that all the signals in the closed-loop system remain bounded and the tracking error converges to zero asymptotically. Moreover, compared to the related existence predictive controllers, as the number of T2FNN estimators are reduced, the computation time in the online applications decreases. In the proposed method, T2FNN is used due to its ability to effectively model uncertainties, which may exist in the rules and data measured by the sensors. The proposed T2FNNP controller is applied to a nonlinear inverted pendulum and single link robot manipulator systems with input time-varying delay and compared with a type-1 fuzzy sliding predictive (T1FSP) controller. Simulation results indicate the efficiency of the proposed T2FNNP controller. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.
Menstrual suppression with the levonorgestrel intrauterine system in girls with developmental delay.
Hillard, Paula J Adams
2012-10-01
To describe the experiences of 21 girls with developmental delay accompanied by multiple other medical problems, seen over a 3-year interval, who underwent insertion of the levonorgestrel intrauterine system (LNG-IUS) for menstrual suppression. Retrospective chart review. A referral pediatric and adolescent gynecology clinic within a tertiary care medical center with referrals from community pediatricians, pediatric subspecialists including developmental and behavioral pediatricians, community gynecologists, and adolescent medicine specialists. Adolescents and young women with developmental delay and multiple comorbid conditions who were seen for consultation with their families requesting menstrual suppression. Participants were offered hormonal options, for menstrual suppression including the LNG-IUS. Satisfaction with menstrual suppression among families electing the LNG-IUS. Adolescents and young women seen at CCHMC with developmental delay and multiple comorbid conditions with requests for menstrual suppression were offered hormonal options, including the LNG-IUS. Twenty-one families chose this option. Fifteen of 21 girls had previously used hormonal menstrual suppression. General anesthesia was required for 20 of 21 insertions, and 9 of 20 of these insertions were combined with other surgical procedures. There were no unsuccessful insertions or major complications. Mean duration of follow-up was 11 months, and families were satisfied with this option for menstrual suppression. There was 1 request for removal. LNG-IUS for menstrual suppression, in girls with developmental delay and multiple comorbid medical conditions for which amenorrhea is desirable and therapeutic, appears promising. Copyright © 2012 North American Society for Pediatric and Adolescent Gynecology. Published by Elsevier Inc. All rights reserved.
Crépeaux, Guillemette; Eidi, Housam; David, Marie-Odile; Tzavara, Eleni; Giros, Bruno; Exley, Christopher; Curmi, Patrick A; Shaw, Christopher A; Gherardi, Romain K; Cadusseau, Josette
2015-11-01
Concerns regarding vaccine safety have emerged following reports of potential adverse events in both humans and animals. In the present study, alum, alum-containing vaccine and alum adjuvant tagged with fluorescent nanodiamonds were used to evaluate i) the persistence time at the injection site, ii) the translocation of alum from the injection site to lymphoid organs, and iii) the behavior of adult CD1 mice following intramuscular injection of alum (400 μg Al/kg). Results showed for the first time a strikingly delayed systemic translocation of adjuvant particles. Alum-induced granuloma remained for a very long time in the injected muscle despite progressive shrinkage from day 45 to day 270. Concomitantly, a markedly delayed translocation of alum to the draining lymph nodes, major at day 270 endpoint, was observed. Translocation to the spleen was similarly delayed (highest number of particles at day 270). In contrast to C57BL/6J mice, no brain translocation of alum was observed by day 270 in CD1 mice. Consistently neither increase of Al cerebral content, nor behavioral changes were observed. On the basis of previous reports showing alum neurotoxic effects in CD1 mice, an additional experiment was done, and showed early brain translocation at day 45 of alum injected subcutaneously at 200 μg Al/kg. This study confirms the striking biopersistence of alum. It points out an unexpectedly delayed diffusion of the adjuvant in lymph nodes and spleen of CD1 mice, and suggests the importance of mouse strain, route of administration, and doses, for future studies focusing on the potential toxic effects of aluminum-based adjuvants. Copyright © 2015 Elsevier Inc. All rights reserved.
Impact of wave propagation delay on latency in optical communication systems
Kawanishi, Tetsuya; Kanno, Atsushi; Yoshida, Yuki; Kitayama, Ken-ichi
2012-12-01
Latency is an important figure to describe performance of transmission systems for particular applications, such as data transfer for earthquake early warning, transaction for financial businesses, interactive services such as online games, etc. Latency consists of delay due to signal processing at nodes and transmitters, and of signal propagation delay due to propagation of electromagnetic waves. The lower limit of the latency in transmission systems using conventional single mode fibers (SMFs) depends on wave propagation speed in the SMFs which is slower than c. Photonic crystal fibers, holly fibers and large core fibers can have low effective refractive indices, and can transfer light faster than in SMFs. In free-space optical systems, signals propagate with the speed c, so that the latency could be smaller than in optical fibers. For example, LEO satellites would transmit data faster than optical submarine cables, when the transmission distance is longer than a few thousand kilometers. This paper will discuss combination of various transmission media to reduce negative impact of the latency, as well as applications of low-latency systems.
A Delayed Neutron Counting System for the Analysis of Special Nuclear Materials
Sellers, Madison Theresa
Nuclear forensic analysis is a modem science that uses numerous analytical techniques to identify and attribute nuclear materials in the event of a nuclear explosion, radiological terrorist attack or the interception of illicit nuclear material smuggling. The Canadian Department of National Defence has participated in recent international exercises that have highlighted the Nation's requirement to develop nuclear forensics expertise, protocol and capabilities, specifically pertaining to the analysis of special nuclear materials (SNM). A delayed neutron counting (DNC) system has been designed and established at the Royal Military College of Canada (RMC) to enhance the Government's SNM analysis capabilities. This analytical technique complements those already at RMC by providing a rapid and non-destructive method for the analysis of the fissile isotopes of both uranium (U) and plutonium (Pu). The SLOWPOKE-2 reactor at RMC produces a predominately thermal neutron flux. These neutrons induce fission in the SNM isotopes 233U, 235U and 239Pu releasing prompt fast neutrons, energy and radioactive fission fragments. Some of these fission fragments undergo beta - decay and subsequently emit neutrons, which can be recorded by an array of sensitive 3He detectors. The significant time period between the fission process and the release of these neutrons results in their identification as 'delayed neutrons'. The recorded neutron spectrum varies with time and the count rate curve is unique to each fissile isotope. In-house software, developed by this project, can analyze this delayed neutron curve and provides the fissile mass in the sample. Extensive characterization of the DNC system has been performed with natural U samples with 235 U content ranging from 2--7 microg. The system efficiency and dead time behaviour determined by the natural uranium sample analyses were validated by depleted uranium samples with similar quantities of 235 U resulting in a typical relative error of
Directory of Open Access Journals (Sweden)
Pengfei Guo
2014-01-01
Full Text Available This paper deals with the fault detection problem for a class of discrete-time wireless networked control systems described by switching topology with uncertainties and disturbances. System states of each individual node are affected not only by its own measurements, but also by other nodes’ measurements according to a certain network topology. As the topology of system can be switched in a stochastic way, we aim to design H∞ fault detection observers for nodes in the dynamic time-delay systems. By using the Lyapunov method and stochastic analysis techniques, sufficient conditions are acquired to guarantee the existence of the filters satisfying the H∞ performance constraint, and observer gains are derived by solving linear matrix inequalities. Finally, an illustrated example is provided to verify the effectiveness of the theoretical results.
Stability Analysis and H∞ Model Reduction for Switched Discrete-Time Time-Delay Systems
Directory of Open Access Journals (Sweden)
Zheng-Fan Liu
2014-01-01
Full Text Available This paper is concerned with the problem of exponential stability and H∞ model reduction of a class of switched discrete-time systems with state time-varying delay. Some subsystems can be unstable. Based on the average dwell time technique and Lyapunov-Krasovskii functional (LKF approach, sufficient conditions for exponential stability with H∞ performance of such systems are derived in terms of linear matrix inequalities (LMIs. For the high-order systems, sufficient conditions for the existence of reduced-order model are derived in terms of LMIs. Moreover, the error system is guaranteed to be exponentially stable and an H∞ error performance is guaranteed. Numerical examples are also given to demonstrate the effectiveness and reduced conservatism of the obtained results.
Directory of Open Access Journals (Sweden)
Noriki Uchida
2017-02-01
Full Text Available It is considered that the road condition in the winter is one of the significant issues for the safety driving by tourists or residents. However, there are many difficulties of the V2V networks such as the transmission range of wireless networks and the noises from the automobilefs bodies. Thus, this paper introduces the Adaptive Array Antenna (AAA controls for the vehicle-to-vehicle (V2V networks based the Delay Tolerant Networking (DTN in the road surveillance system. In the proposed system, the vehicles equip the AAA control systems with IEEE802.11a/b/g based the DTN, and the wireless directions are controlled by the visual recognitions with Kalman filter algorithm to make the longer and stable wireless connections for the efficiency of the DTN. The porotype system is introduced in this paper, and the results are discussed for the future studies.
Robust stabilizing first-order controllers for a class of time delay systems.
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. 2010 ISA. Published by Elsevier Ltd. All rights reserved.
Optimal control strategy for an impulsive stochastic competition system with time delays and jumps
Liu, Lidan; Meng, Xinzhu; Zhang, Tonghua
2017-07-01
Driven by both white and jump noises, a stochastic delayed model with two competitive species in a polluted environment is proposed and investigated. By using the comparison theorem of stochastic differential equations and limit superior theory, sufficient conditions for persistence in mean and extinction of two species are established. In addition, we obtain that the system is asymptotically stable in distribution by using ergodic method. Furthermore, the optimal harvesting effort and the maximum of expectation of sustainable yield (ESY) are derived from Hessian matrix method and optimal harvesting theory of differential equations. Finally, some numerical simulations are provided to illustrate the theoretical results.
Fault Estimation for Fuzzy Delay Systems: A Minimum Norm Least Squares Solution Approach.
Huang, Sheng-Juan; Yang, Guang-Hong
2017-09-01
This paper mainly focuses on the problem of fault estimation for a class of Takagi-Sugeno fuzzy systems with state delays. A minimum norm least squares solution (MNLSS) approach is first introduced to establish a fault estimation compensator, which is able to optimize the fault estimator. Compared with most of the existing fault estimation methods, the MNLSS-based fault estimation method can effectively decrease the effect of state errors on the accuracy of fault estimation. Finally, three examples are given to illustrate the effectiveness and merits of the proposed method.
Persistent villi hypoperfusion explains intramucosal acidosis in sheep endotoxemia
Dubin, Arnaldo; Edul, Vanina Siham Kanoore; Pozo, Mario Omar; Murias, Gastón; Canullán, Carlos Manuel; Martins, Enrique Francisco; Ferrara, Gonzalo; Canales, Héctor Saul; Laporte, Mercedes; Estenssoro, Elisa; Ince, Can
2008-01-01
OBJECTIVE: To test the hypothesis that persistent villi hypoperfusion explains intramucosal acidosis after endotoxemic shock resuscitation. DESIGN: Controlled experimental study. SETTING: University-based research laboratory. SUBJECTS: A total of 14 anesthetized, mechanically ventilated sheep.
Tolerance of hypercapnic acidosis by the European eel, Anguilla anguilla
DEFF Research Database (Denmark)
McKenzie, DJ; Dalla Valle, AZ; Steffensen, JF
2000-01-01
content (ca,O2) from 9.6 ± 0.7 to 2.0 ± 0.5 vol%. There was a significant increase in fG and POP at Pw,CO2 values of 10, 20, 40 mmHg, then a decline in fG but further increase in POP at Pw,CO2 = 60 and 80 mmHg. Despite the severe acidosis and hypoxaemia, there were no significant effects on CO or O2...... in tailbeat frequencies, aerobic scope or maximum sustainable swimming speed. The results indicate that the eel is extremely tolerant of hypercapnic acidosis. Acute, severe acidosis and hypoxaemia had no effect on CO or whole animal O2 uptake; chronic acidosis and hypoxaemia had no effect on the ability...
Distal renal tubular acidosis in recurrent renal stone formers
DEFF Research Database (Denmark)
Osther, P J; Hansen, A B; Røhl, H F
1989-01-01
Renal acidification ability was examined in 90 recurrent renal stone formers, using fasting morning urinary pH levels followed by a short ammonium chloride loading test in subjects with pH levels above 6.0. Fifteen patients (16.6%) revealed a distal renal tubular acidification defect: one patient...... (1.1%) had complete distal renal tubular acidosis and 14 (15.5%) incomplete distal renal tubular acidosis. Our results confirm that distal renal tubular acidification defects are associated with a more severe form of stone disease and make distal renal tubular acidosis one of the most frequent...... metabolic disturbances in renal stone formers. Distal renal tubular acidosis (dRTA) was relatively more common in female stone formers and most often found in patients with bilateral stone disease (36%). Since prophylactic treatment in renal stone formers with renal acidification defects is available...
Genetics Home Reference: renal tubular acidosis with deafness
... Disorders and Deafness Health Topic: Hearing Problems in Children Health Topic: Kidney Diseases Genetic and Rare Diseases Information Center (1 link) Renal tubular acidosis with deafness Additional NIH Resources (2 ...
Side Effects of HIV Medicines: HIV and Lactic Acidosis
... some HIV medicines. HIV medicines in the nucleoside reverse transcriptase inhibitor (NRTI) drug class may cause lactic acidosis. ... some HIV medicines. HIV medicines in the nucleoside reverse transcriptase inhibitor (NRTI) drug class can cause the body ...
Pyroglutamic acid-induced metabolic acidosis: a case report
Luyasu, S.; Wamelink, M.M.C.; Galanti, L.; Dive, A.
2014-01-01
High anion gap metabolic acidosis due to pyroglutamic acid (5-oxoproline) is a rare complication of acetaminophen treatment (which depletes glutathione stores) and is often associated with clinically moderate to severe encephalopathy. Acquired 5-oxoprolinase deficiency (penicillins) or the presence
Gomes, Weglis Dyanne de Souza; Silva, Cristina Antoniali; Melo, Moriel Evangelista; Silva, Vanessa Ferreira da; Almeida, Melyna Marques de; Pedrini, Denise; Poi, Wilson Roberto; Sonoda, Celso Koogi; Panzarini, Sônia Regina
2015-12-01
Systemic antibiotic therapy (SAT) has usually been recommended after tooth replantation, but its actual value has been questioned. As there are no reports in the literature about its influence on tooth replantation, the aim of this study was to evaluate the influence of systemic administration of antibiotics (amoxicillin and tetracycline) at the different phases of the repair process (7, 15, 30 days) in delayed rat tooth replantation. Ninety Wistar rats (Rattus norvegicus albinus) had their maxillary right incisors extracted and bench-dried for 60 min. The dental papilla, enamel organ, pulp tissue, and root surface-adhered periodontal ligament were removed, and the teeth were replanted. The animals received no antibiotics (n = 30) or were medicated systemically with amoxicillin (n = 30) and tetracycline (n = 30), and were euthanized after 7, 15, and 30 days. Regardless of the evaluation period, the acute inflammatory infiltrate was less intense and root resorption presented smaller extent and depth in the group treated with amoxicillin. The results suggest that SAT has a positive influence on the repair process in delayed tooth replantation and that amoxicillin is an excellent treatment option. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Local and global Hopf bifurcation analysis in a neutral-type neuron system with two delays
Lv, Qiuyu; Liao, Xiaofeng
2018-03-01
In recent years, neutral-type differential-difference equations have been applied extensively in the field of engineering, and their dynamical behaviors are more complex than that of the delay differential-difference equations. In this paper, the equations used to describe a neutral-type neural network system of differential difference equation with two delays are studied (i.e. neutral-type differential equations). Firstly, by selecting τ1, τ2 respectively as a parameter, we provide an analysis about the local stability of the zero equilibrium point of the equations, and sufficient conditions of asymptotic stability for the system are derived. Secondly, by using the theory of normal form and applying the theorem of center manifold introduced by Hassard et al., the Hopf bifurcation is found and some formulas for deciding the stability of periodic solutions and the direction of Hopf bifurcation are given. Moreover, by applying the theorem of global Hopf bifurcation, the existence of global periodic solution of the system is studied. Finally, an example is given, and some computer numerical simulations are taken to demonstrate and certify the correctness of the presented results.
Directory of Open Access Journals (Sweden)
Samardzija Dragan
2005-01-01
Full Text Available The advances in programmable and reconfigurable radios have rendered feasible transmitter optimization schemes that can greatly improve the performance of multiple-antenna multiuser systems. Reconfigurable radio platforms are particularly suitable for implementation of transmitter optimization at the base station. We consider the downlink of a wireless system with multiple transmit antennas at the base station and a number of mobile terminals (i.e., users each with a single receive antenna. Under an average transmit power constraint, we consider the maximum achievable sum data rates in the case of (1 zero-forcing (ZF spatial prefilter, (2 modified zero-forcing (MZF spatial prefilter, and (3 triangularization spatial prefilter coupled with dirty-paper coding (DPC transmission scheme. We show that the triangularization with DPC approaches the closed-loop MIMO rates (upper bound for higher SNRs. Further, the MZF solution performs very well for lower SNRs, while for higher SNRs, the rates for the ZF solution converge to the MZF rates. An important impediment that degrades the performance of such transmitter optimization schemes is the delay in channel state information (CSI. We characterize the fundamental limits of performance in the presence of delayed CSI and then propose performance enhancements using a linear MMSE predictor of the CSI that can be used in conjunction with transmitter optimization in multiple-antenna multiuser systems.
Food-grade micro-encapsulation systems that may induce satiety via delayed lipolysis: A review.
Corstens, Meinou N; Berton-Carabin, Claire C; de Vries, Renko; Troost, Freddy J; Masclee, Ad A M; Schroën, Karin
2017-07-03
The increasing prevalence of overweight and obesity requires new, effective prevention and treatment strategies. One approach to reduce energy intake is by developing novel foods with increased satiating properties, which may be accomplished by slowing down lipolysis to deliver substrates to the ileum, thereby enhancing natural gut-brain signaling pathways of satiety that are normally induced by meal intake. To develop slow release food additives, their processing in the gastrointestinal tract has to be understood; therefore, we start from a general description of the digestive system and relate that to in vitro modeling, satiety, and lipolytic mechanisms. The effects of physicochemical lipid composition, encapsulation matrix, and interfacial structure on lipolysis are emphasized. We give an overview of techniques and materials used, and discuss partitioning, which may be a key factor for encapsulation performance. Targeted release capsules that delay lipolysis form a real challenge because of the high efficiency of the digestive system; hardly any proof was found that intact orally ingested lipids can be released in the ileum and thereby induce satiety. We expect that this challenge could be tackled with structured o/w-emulsion-based systems that have some protection against lipase, e.g., by hindering bile salt adsorption and/or delaying lipase diffusion.
Ding, Yuting; Cao, Jun
In this paper, we study the dynamics in delayed nonlinear financial system, with particular attention focused on Hopf and double Hopf bifurcations. Firstly, we identify the critical values for stability switches, Hopf and double Hopf bifurcations. We show how the parameters affect the dynamical behavior of the system. Secondly, the normal forms near the Hopf and double Hopf bifurcations, as well as the classifications of local dynamics are analyzed. These bifurcations lead a chaotic system to be stable states, such as the coexistence of a pair of stable equilibria or a pair of stable periodic oscillations, and then chaos disappears. Numerical simulations are presented to verify the analytical predictions. Furthermore, detailed numerical analysis using MATLAB extends the local bifurcation analysis to a global picture, namely, a family of stable periodic solutions exist in a large region of delay and “chaos switchover” phenomenon appears. Therefore, in accordance with the above theoretical analysis, reasonable parameters can be designed in order to achieve various applications.
International Nuclear Information System (INIS)
Zhang Min-Min; Mei Dong-Cheng; Wang Can-Jun
2011-01-01
The effects of the time delay on the upper bound of the time derivative of information entropy are investigated in a time-delayed dynamical system driven by correlated noise. Using the Markov approximation of the stochastic delay differential equations and the Schwartz inequality principle, we obtain an analytical expression for the upper bound U B (t) of the time derivative of the information entropy. The results show that there is a critical value of τ (delay time), and U B (t) presents opposite behaviours on difference sides of the critical value. For the case of the weak additive noise, τ can induce a reentrance transition. Delay time τ also causes a reversal behaviour in U B (t)-λ plot, where λ denotes the degree of the correlation between the two noises. (general)
Benign duodenocolic fistula. A case presenting with acidosis
DEFF Research Database (Denmark)
Benn, Marianne; Nielsen, F T; Antonsen, H K
1997-01-01
A case of benign duodenocolic fistula as a complication to peptic ulcer disease is presented, the case being interesting for the rarity of the diagnosis and by being complicated with acidosis. The etiology, clinical features, diagnosis, and treatment are reviewed.......A case of benign duodenocolic fistula as a complication to peptic ulcer disease is presented, the case being interesting for the rarity of the diagnosis and by being complicated with acidosis. The etiology, clinical features, diagnosis, and treatment are reviewed....
Metabolic acidosis in childhood: why, when and how to treat.
Andrade, Olberes V B; Ihara, Flávio O; Troster, Eduardo J
2007-05-01
To critically discuss the treatment of metabolic acidosis and the main mechanisms of disease associated with this disorder; and to describe controversial aspects related to the risks and benefits of using sodium bicarbonate and other therapies. Review of PubMed/MEDLINE, LILACS and Cochrane Library databases for articles published between 1996 and 2006 using the following keywords: metabolic acidosis, lactic acidosis, ketoacidosis, diabetic ketoacidosis, cardiopulmonary resuscitation, sodium bicarbonate, treatment. Classical publications concerning the topic were also reviewed. The most recent and representative were selected, with emphasis on consensus statements and guidelines. There is no evidence of benefits resulting from the use of sodium bicarbonate for the hemodynamic status, clinical outcome, morbidity and mortality in high anion gap metabolic acidosis associated with lactic acidosis, diabetic ketoacidosis and cardiopulmonary resuscitation. Therefore, the routine use of sodium bicarbonate is not indicated. Potential side effects must be taken into consideration. Treating the underlying disease is essential to reverse the process. The efficacy of other alternative therapies has not been demonstrated in large-scale studies. Despite the known effects of acidemia on the organism in critical situations, a protective role of acidemia in hypoxic cells and the risk of alkalemia secondary to drug interventions are being considered. There is consensus regarding the advantages of alkali and sodium bicarbonate therapy in cases with normal anion gap; however, in the presence of high anion gap acidosis, especially lactic acidosis, diabetic acidosis and cardiopulmonary resuscitation, the use of sodium bicarbonate is not beneficial and has potential adverse effects, limiting its indication. The only points of agreement in the literature refer to the early treatment of the underlying disease and the mechanisms generating metabolic acidemia. Other promising treatment
Renal tubular acidosis secondary to jejunoileal bypass for morbid obesity
DEFF Research Database (Denmark)
Schaffalitzky de Muckadell, O B; Ladefoged, Jens; Thorup, Jørgen Mogens
1985-01-01
Renal handling of acid and base was studied in patients with persistent metabolic acidosis 3-9 years after jejunoileal bypass for morbid obesity. Excretion of acid was studied before and after intravenous infusion of NH4Cl and excretion of bicarbonate after infusion of NaHCO3. Bypass patients...... groups. Fractional loss of bicarbonate in urine was higher in controls than in bypass patients. The renal impairment is classified as distal renal tubular acidosis....
Renal tubular acidosis secondary to jejunoileal bypass for morbid obesity
DEFF Research Database (Denmark)
Schaffalitzky de Muckadell, O B; Ladefoged, Jens; Thorup, Jørgen Mogens
1985-01-01
Renal handling of acid and base was studied in patients with persistent metabolic acidosis 3-9 years after jejunoileal bypass for morbid obesity. Excretion of acid was studied before and after intravenous infusion of NH4Cl and excretion of bicarbonate after infusion of NaHCO3. Bypass patients sho...... groups. Fractional loss of bicarbonate in urine was higher in controls than in bypass patients. The renal impairment is classified as distal renal tubular acidosis....
Directory of Open Access Journals (Sweden)
Jagadish Siddalinga Devaru
2013-01-01
Full Text Available Setting: TU/DMCs of Bangalore city. India. All new sputum positive patients registered to the selected TU/DMCs were interviewed. A total of 468 patients aged above 20 years were enrolled. The study period was from January to June 2009. Objectives: To track the delay in diagnosis and treatment of patients reporting to tuberculosis units and microscopy centers. Design: A cross sectional study. TU/DMCs were randomly selected. A pretested questionnaire was administered to collect data. Results: The study population had 326 (69.7% males. The mean age of study population was 38.5 years. 74.4% were married, 20.7% were illiterates, 27.8% were daily wagers, 10.5% were unemployed. The median and mean total delays from development of cough to diagnosis were 41 days and 36.04 days; the median and mean patient delay was 24 days and 20.7 days, and health system delay was 18 and 15.31 days respectively. There was a significant difference among the different age group of patients with older people having longer patient delay (p<0.0001. Lower income, illiteracy, unemployment, showed significant association with patients delay (p<0.0001. Alcohol intake and smoking habit among the male patients had significant association for longer patient delay (p=0.00004. Health seeking behavior like self medication, also had longer patient delay. Other socio demographic factors had no significant influence on the patient delay. Longer health system delay was found among patients who visited general practitioners and Ayurvedic medicine. Conclusion: More specific and effective health education of the general public on tuberculosis and seeking of appropriate medical consultation are likely to improve case detection.
Act-and-wait time-delayed feedback control of autonomous systems
Pyragas, Viktoras; Pyragas, Kestutis
2018-02-01
Recently an act-and-wait modification of time-delayed feedback control has been proposed for the stabilization of unstable periodic orbits in nonautonomous dynamical systems (Pyragas and Pyragas, 2016 [30]). The modification implies a periodic switching of the feedback gain and makes the closed-loop system finite-dimensional. Here we extend this modification to autonomous systems. In order to keep constant the phase difference between the controlled orbit and the act-and-wait switching function an additional small-amplitude periodic perturbation is introduced. The algorithm can stabilize periodic orbits with an odd number of real unstable Floquet exponents using a simple single-input single-output constraint control.
Robust Fault Tolerant Control for a Class of Time-Delay Systems with Multiple Disturbances
Directory of Open Access Journals (Sweden)
Songyin Cao
2013-01-01
Full Text Available A robust fault tolerant control (FTC approach is addressed for a class of nonlinear systems with time delay, actuator faults, and multiple disturbances. The first part of the multiple disturbances is supposed to be an uncertain modeled disturbance and the second one represents a norm-bounded variable. First, a composite observer is designed to estimate the uncertain modeled disturbance and actuator fault simultaneously. Then, an FTC strategy consisting of disturbance observer based control (DOBC, fault accommodation, and a mixed H2/H∞ controller is constructed to reconfigure the considered systems with disturbance rejection and attenuation performance. Finally, simulations for a flight control system are given to show the efficiency of the proposed approach.
Simon, Ann M; Ingraham, Kimberly A; Spanias, John A; Young, Aaron J; Finucane, Suzanne B; Halsne, Elizabeth G; Hargrove, Levi J
2017-08-01
Powered lower limb prostheses can assist users in a variety of ambulation modes by providing knee and/or ankle joint power. This study's goal was to develop a flexible control system to allow users to perform a variety of tasks in a natural, accurate, and reliable way. Six transfemoral amputees used a powered knee-ankle prosthesis to ascend/descend a ramp, climb a 3- and 4-step staircase, perform walking and standing transitions to and from the staircase, and ambulate at various speeds. A mode-specific classification architecture was developed to allow seamless transitions at four discrete gait events. Prosthesis mode transitions (i.e., the prosthesis' mechanical response) were delayed by 90 ms. Overall, users were not affected by this small delay. Offline classification results demonstrate significantly reduced error rates with the delayed system compared to the non-delayed system (p knee-ankle prosthesis.
Derivative-Free Distributed Filtering for MIMO Robotic Systems under Delays and Packet Drops
Directory of Open Access Journals (Sweden)
Gerasimos G. Rigatos
2013-02-01
Full Text Available This paper presents an approach to distributed state estimation-based control of nonlinear MIMO systems, capable of incorporating delayed measurements in the estimation algorithm while also being robust to packet losses. First, the paper examines the problem of distributed nonlinear filtering over a communication/sensors network, and the use of the estimated state vector in a control loop. As a possible filtering approach, an extended information filter (EIF is proposed. The extended information filter requires the computation of Jacobians which in the case of high order nonlinear dynamical systems can be a cumbersome procedure, while it also introduces cumulative errors to the state estimation due to the approximative linearization performed in the Taylor series expansion of the system's nonlinear model. To overcome the aforementioned weaknesses of the extended information filter, a derivative-free approach to extended information filtering has been proposed. Distributed filtering is now based on a derivative-free implementation of Kalman filtering which is shown to be applicable to MIMO nonlinear dynamical systems. In the proposed derivative-free extended information filtering, the system is first subject to a linearization transformation that makes use of the differential flatness theory. It is shown how the proposed distributed filtering method can succeed in compensation of random delays and packet drops which may appear during the transmission of measurements and of state vector estimates, thus assuring a reliable performance of the distributed filtering-based control scheme. Evaluation tests are carried out on benchmark MIMO nonlinear systems, such as multi-DOF robotic manipulators.
The bioethanol from bagasse with the approach of discontinuous systems and the delay phenomena
International Nuclear Information System (INIS)
Albernas Carvajal, Yailet; Gonzalez Cortes, Meilyn; Mesa Garriga, Leyanis; Pedraza Garciga, Julio; Gonzalez Suarez, Erenio
2011-01-01
In this paper was analyzed the Bioethanol technology from bagasse considering discontinuous systems' and the delay phenomena. This technology have two stages that are key to succeed in obtaining the fermentable sugars, they are the pretreatment stage and enzymatic hydrolysis for subsequent fermentation. The great obstacle of the two latter stages, is that for best results, need long residence times (and this is where the delay phenomena it appears). For that reason the analysis require a study on how to carry out to ensure that the process global continuous. The enzymatic hydrolysis stage last an average of 24 h, while fermentation stage is accomplishes in 12 h. In this paper, the bioethanol technology was studied taking into account the basic concepts of discontinuous systems. Different technological configurations were studied, obtaining the best configuration: the presaccharification process, according to technical and economics criterions. The process profitability is achieved considering the total process as a bio refinery, which allows the production of high added value by-products such as furfural. (author)
Optimal design of PID controller for second order plus time delay systems
International Nuclear Information System (INIS)
Srivastava, S.; Misra, A.; Kumar, Y.; Thakur, S.K.
2015-01-01
It is well known that the effect of time delay in the forward path of control loop deteriorates the system performance and at the same time makes it difficult to compute the optimum PID controller parameters of the feedback control systems. PI/PID controller is most popular and used more than 80% in industries as well as in accelerators lab due to its simple structure and appropriate robustness. At VECC we have planned to use a PID controller for the speed control of DC motor which will be used to adjust the solenoid coil position of the 2.45 GHz microwave ion source for optimum performance during the online operation. In this paper we present a comparison of the two methods which have been used to design the optimum PID controller parameters: one by optimizing different time domain performance indices such as lAE, ITSE etc. and other using analytical formulation based on Linear Quadratic Regulator (LQR). We have performed numerical simulations using MATLAB and compare the closed loop time response performance measures using the PID parameters obtained from above mentioned two methods on a second order transfer function of a DC motor with time delay. (author)
Power Optimization of Multimode Mobile Embedded Systems with Workload-Delay Dependency
Directory of Open Access Journals (Sweden)
Hoeseok Yang
2016-01-01
Full Text Available This paper proposes to take the relationship between delay and workload into account in the power optimization of microprocessors in mobile embedded systems. Since the components outside a device continuously change their values or properties, the workload to be handled by the systems becomes dynamic and variable. This variable workload is formulated as a staircase function of the delay taken at the previous iteration in this paper and applied to the power optimization of DVFS (dynamic voltage-frequency scaling. In doing so, a graph representation of all possible workload/mode changes during the lifetime of a device, Workload Transition Graph (WTG, is proposed. Then, the power optimization problem is transformed into finding a cycle (closed walk in WTG which minimizes the average power consumption over it. Out of the obtained optimal cycle of WTG, one can derive the optimal power management policy of the target device. It is shown that the proposed policy is valid for both continuous and discrete DVFS models. The effectiveness of the proposed power optimization policy is demonstrated with the simulation results of synthetic and real-life examples.
Changes in bone sodium and carbonate in metabolic acidosis and alkalosis in the dog
Burnell, James M.
1971-01-01
Metabolic acidosis and alkalosis were produced in adult dogs over 5- to 10-day periods. Midtibial cortical bone was analyzed for calcium, sodium, phosphorus, and carbonate. In acidosis bone CO3/Ca decreased 9.5% and bone Na/Ca decreased 6.3%. In alkalosis bone CO3/Ca increased 3.1% and bone Na/Ca increased 3.0%. Previous attempts to account for changes in net acid balance by summation of extra- and intracellular acid-base changes have uniformly resulted in about 40-60% of acid gained or lost being “unaccounted for.” If it is assumed that changes in tibial cortex reflect changes in the entire skeletal system, changes in bone CO3= are sufficiently large to account for the “unaccounted for” acid change without postulating changes in cellular metabolic acid production. PMID:5540172
Distal renal tubular acidosis and quadriparaesis in Sjögren′s syndrome: A cunning congregate
Directory of Open Access Journals (Sweden)
Arundhati G Diwan
2014-01-01
Full Text Available Sjögren′s syndrome (SS is a chronic autoimmune disease, chiefly affecting the exocrine glandular function of salivary glands and lacrimal glands. Rarely, it involves the kidneys, central and peripheral nervous system, muscloskeletal apparatus and lungs. We report a rare constellation of SS with distal renal tubular acidosis and quadriparaesis in a young female. History of quadriparaesis was acute, with rapid progression. Supplementary treatment for severe hypokalemia was instituted at the earliest, lest the patient develop respiratory muscle weakness. Concomitantly, metabolic acidosis with alkaline urine was suspected and subsequently investigated. Eventually, this was attributed to impaired renal acidification of urine in the distal tubules. History of dryness of eyes and mouth since 6 months justified salivary gland biopsy. The results yielded a lymphocytic infiltrative pathology strongly favoring SS. The patient benefited from prompt potassium replacement therapy and had complete resolution over the next week. Supportive treatment for predictable manifestations was continued along with potassium supplements.
[High anion gap metabolic acidosis (pyroglutamic acidosis) induced by chronic acetaminophen use].
Tchougang Nono, J; Mistretta, V; Noirot, I; Canivet, J L; Damas, P
2018-01-01
Acetaminophen is the most consumable analgesic in the world in the form of medical prescription or self-medication. It is one of the active ingredients most often involved in voluntary poisoning. Lethal dose of acetaminophen classically induces acute hepatic failure on hepatic necrosis. Chronic intake of sub-lethal doses (i.e. near recommended therapeutic doses) of acetaminophen in the presence of certain risk factors may be responsible for another much less recognized pathological manifestation: severe metabolic acidosis with an increased anion gap due to the accumulation of 5-oxoproline or pyroglutamic acid.
A fast position encoding system for a delay line based gas filled area detector
Epstein, A.; Boulin, C.
1998-08-01
Delay line based readout electronics for X-ray area detectors used to carry out kinetic measurements with synchrotron radiation is used mostly because of its relative simplicity and low cost. The key element in the system is a fast multichannel real-time encoding time to digital converter (TDC). For fast time-resolved applications the detector is a 200/spl times/200 mm multi-wire gas filled chamber, coupled to two delay lines of about 250 ns to encode the position of the X-ray photon interaction in the X and Y cathode planes. The anode plane of the detector delivers a fast prompt signal which is characteristic of the arrival time of the event. Our method of measurement consists of the simultaneous capture of five time components. These are a time stamp of the anode signal and the relative time for the two pairs of cathode signals collected at the end of the delay lines. These cathode signals arrive at times that are directly proportional to the X and Y co-ordinates of the event. Our electronics is designed around the commercially available LRS 4208 CAMAC time measurement unit. This unit is modified in a way to allow the direct connection of a daughter board which consists of two Logic Cell Arrays (LCA) and some external synchronization and control logic. The first LCA collects the values of the real-time digital interpolators (I ns resolution) and the first level of real-time counters (8 ns resolution) coming from the LRS 4208. Furthermore, it adds another level of real-time counters and is responsible for the computation of the X and Y locations, as well as the rejection of double or incomplete events.
A fast position encoding system for a delay line based gas filled area detector
International Nuclear Information System (INIS)
Epstein, A.; Boulin, C.
1998-01-01
Delay line based readout electronics for X-ray area detectors used to carry out kinetic measurements with synchrotron radiation is used mostly because of its relative simplicity and low cost. The key element in the system is a fast multichannel real-time encoding time to digital converter (TDC). For fast time-resolved applications the detector is a 200 x 200 mm multi-wire gas filled chamber, coupled to two delay lines of about 250 ns to encode the position of the X-ray photon interaction in the X and Y cathode planes. The anode plane of the detector delivers a fast prompt signal which is characteristic of the arrival time of the event. The method of measurement consists of the simultaneous capture of five time components. These are a time stamp of the anode signal and the relative time for the two pairs of cathode signals collected at the end of the delay lines. These cathode signals arrive at times that are directly proportional to the X and Y coordinates of the event. The electronics is designed around the commercially available LRS 4208 CAMAC time measurement unit. This unit is modified in a way to allow the direct connection of a daughter board which consists of two Logic Cell Arrays (LCA) and some external synchronization and control logic. The first LCA collects the values of the real-time digital interpolators (1 ns resolution) and the first level of real-time counters (8 ns resolution) coming from the LRS 4208. Furthermore, it adds another level of real-time counters and is responsible for the computation of the X and Y locations, as well as the rejection of double or incomplete events
International Nuclear Information System (INIS)
Wen Guilin; Wang Qingguo; Lin Chong; Han Xu; Li Guangyao
2006-01-01
Synchronization under output feedback control with multiple random time delays is studied, using the paradigm in nonlinear physics-Chua's circuit. Compared with other synchronization control methods, output feedback control with multiple random delay is superior for a realistic synchronization application to secure communications. Sufficient condition for global stability of delay-dependent synchronization is established based on the LMI technique. Numerical simulations fully support the analytical approach, in spite of the random delays
Evidence for a Detrimental Effect of Bicarbonate Therapy in Hypoxic Lactic Acidosis
Graf, Helmut; Leach, William; Arieff, Allen I.
1985-02-01
Lactic acidosis, a clinical syndrome caused by the accumulation of lactic acid, is characterized by lactate concentration in blood greater than 5 mM. Therapy usually consists of intravenous sodium bicarbonate (NaHCO3), but resultant mortality is greater than 60 percent. The metabolic and systemic effects of NaHCO3 therapy of hypoxic lactic acidosis in dogs were studied and compared to the effects of sodium chloride or no therapy. Sodium bicarbonate elevated blood lactate concentrations to a greater extent than did either sodium chloride or no treatment. Despite the infusion of NaHCO3, both arterial pH and bicarbonate concentration decreased by a similar amount in all three groups of dogs. Additional detrimental effects of NaHCO3 were observed on the cardiovascular system, including decreases in cardiac output and blood pressure that were not observed with either sodium chloride or no treatment. Thus there is evidence for a harmful effect of NaHCO3 in the treatment of hypoxic lactic acidosis.
Directory of Open Access Journals (Sweden)
G. Peláez
2007-01-01
Full Text Available An investigation of the response of a physical pendulum to time delay filtered inputs was conducted. It was shown that the physical pendulum model is more accurate than the simple pendulum for modelling the dynamic response of overhead cranes with loads hanging from hooks. Based on the physical pendulum model a Specified Time Delay filter for an experimental mini overhead crane was synthesized. While somewhat limited in the scope by the hardware conditions placed in the system, the results provide basic insights into the successful application of the Time Delay Filtering method to overhead cranes.
Directory of Open Access Journals (Sweden)
Maode Yan
2008-01-01
Full Text Available This paper considers the problem of robust discrete-time sliding-mode control (DT-SMC design for a class of uncertain linear systems with time-varying delays. By applying a descriptor model transformation and Moon's inequality for bounding cross terms, a delay-dependent sufficient condition for the existence of stable sliding surface is given in terms of linear matrix inequalities (LMIs. Based on this existence condition, the synthesized sliding mode controller can guarantee the sliding-mode reaching condition of the specified discrete-time sliding surface for all admissible uncertainties and time-varying delays. An illustrative example verifies the effectiveness of the proposed method.
Directory of Open Access Journals (Sweden)
Zbynek Kocur
2014-01-01
Full Text Available There is a great diversity in the transmission technologies in current data networks. Individual technologies are in most cases incompatible at physical and partially also at the link layer of the reference ISO/OSI model. Network compatibility, as the ability to transmit data, is realizable through the third layer, which is able to guarantee the operation of the different devices across their technological differences. The proposed inverse packet multiplexer addresses increase of the speed and reliability of packet transmission to the third layer, and at the same time it increases the stability of the data communication by the regulation of the delay value during the transmission. This article presents implementation of a communication system and its verification in real conditions. The conclusion compares the strengths and weaknesses of the proposed control system.
Directory of Open Access Journals (Sweden)
Brandt D Pence
Full Text Available Research has shown that aging is associated with increased systemic inflammation as well as a reduction in the strength of immune responses. However, little evidence exists linking the decrease in cell-mediated immunity in older adults with other health parameters. We sought to examine the relationship between cell-mediated immunity as measured in vivo by the delayed-type hypersensitivity (DTH response to candida antigen and demographic and physiological variables in older (65-80 y.o. adults. Candida antigen response was not related to gender or obesity, or to a number of other physiological variables including fitness and body composition. However, positive responders had significantly lower serum C-reactive protein levels (CRP, p4.75 mg•L(-1. Therefore, positive responses to candida antigen in older adults appears to be related to lower levels of systemic inflammation.
Robust Estimation for Discrete Markov System with Time-Varying Delay and Missing Measurements
Directory of Open Access Journals (Sweden)
Jia You
2013-01-01
Full Text Available This paper addresses the ℋ∞ filtering problem for time-delayed Markov jump systems (MJSs with intermittent measurements. Within network environment, missing measurements are taken into account, since the communication channel is supposed to be imperfect. A Bernoulli process is utilized to describe the phenomenon of the missing measurements. The original system is transformed into an input-output form consisting of two interconnected subsystems. Based on scaled small gain (SSG theorem and proposed Lyapunov-Krasovskii functional (LKF, the scaled small gains of the subsystems are analyzed, respectively. New conditions for the existence of the ℋ∞ filters are established, and the corresponding ℋ∞ filter design scheme is proposed. Finally, a simulation example is provided to demonstrate the effectiveness of the proposed approach.
Disordered Stabilization of Stochastic Delay Systems: The Disorder-Dependent Approach
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Guoliang Wang
2017-01-01
Full Text Available In this paper, a general stabilization problem of stochastic delay systems is realized by a disordered controller and studied by exploiting the disorder-dependent approach. Different from the traditional results, the stabilizing controller here experiences a disorder between control gains and system states. Firstly, the above disorder is described by the robust method, whose probability distribution is embodied by a Markov process with two modes. Based on this description, a kind of disordered controller having special uncertainties and depending on a Markov process is proposed. Then, by exploiting a disorder-dependent Lyapunov functional, two respective conditions for the existence of such a disordered controller are provided with LMIs. Moreover, the presented results are further extended to a general case that the corresponding transition rate matrix of the disordered controller has uncertainties. Finally, a numerical example is exploited to demonstrate the effectiveness and superiority of the proposed methods.
Factorization and the synthesis of optimal feedback kernels for differential-delay systems
Milman, Mark M.; Scheid, Robert E.
1987-01-01
A combination of ideas from the theories of operator Riccati equations and Volterra factorizations leads to the derivation of a novel, relatively simple set of hyperbolic equations which characterize the optimal feedback kernel for the finite-time regulator problem for autonomous differential-delay systems. Analysis of these equations elucidates the underlying structure of the feedback kernel and leads to the development of fast and accurate numerical methods for its computation. Unlike traditional formulations based on the operator Riccati equation, the gain is characterized by means of classical solutions of the derived set of equations. This leads to the development of approximation schemes which are analogous to what has been accomplished for systems of ordinary differential equations with given initial conditions.
Hashemi, Mahnaz; Ghaisari, Jafar; Askari, Javad
2015-07-01
This paper investigates an adaptive controller for a class of Multi Input Multi Output (MIMO) nonlinear systems with unknown parameters, bounded time delays and in the presence of unknown time varying actuator failures. The type of considered actuator failure is one in which some inputs may be stuck at some time varying values where the values, times and patterns of the failures are unknown. The proposed approach is constructed based on a backstepping design method. The boundedness of all the closed-loop signals is guaranteed and the tracking errors are proved to converge to a small neighborhood of the origin. The proposed approach is employed for a double inverted pendulums benchmark and a chemical reactor system. The simulation results show the effectiveness of the proposed method. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.
CALCULUS FROM THE PAST: MULTIPLE DELAY SYSTEMS ARISING IN CANCER CELL MODELLING
WAKE, G. C.
2013-01-01
Nonlocal calculus is often overlooked in the mathematics curriculum. In this paper we present an interesting new class of nonlocal problems that arise from modelling the growth and division of cells, especially cancer cells, as they progress through the cell cycle. The cellular biomass is assumed to be unstructured in size or position, and its evolution governed by a time-dependent system of ordinary differential equations with multiple time delays. The system is linear and taken to be autonomous. As a result, it is possible to reduce its solution to that of a nonlinear matrix eigenvalue problem. This method is illustrated by considering case studies, including a model of the cell cycle developed recently by Simms, Bean and Koeber. The paper concludes by explaining how asymptotic expressions for the distribution of cells across the compartments can be determined and used to assess the impact of different chemotherapeutic agents. Copyright © 2013 Australian Mathematical Society.
Shen, Qinghua; Liang, Xiaohui; Shen, Xuemin; Lin, Xiaodong; Luo, Henry Y
2014-03-01
In this paper, we propose an e-health monitoring system with minimum service delay and privacy preservation by exploiting geo-distributed clouds. In the system, the resource allocation scheme enables the distributed cloud servers to cooperatively assign the servers to the requested users under the load balance condition. Thus, the service delay for users is minimized. In addition, a traffic-shaping algorithm is proposed. The traffic-shaping algorithm converts the user health data traffic to the nonhealth data traffic such that the capability of traffic analysis attacks is largely reduced. Through the numerical analysis, we show the efficiency of the proposed traffic-shaping algorithm in terms of service delay and privacy preservation. Furthermore, through the simulations, we demonstrate that the proposed resource allocation scheme significantly reduces the service delay compared to two other alternatives using jointly the short queue and distributed control law.
Directory of Open Access Journals (Sweden)
Zhaohui Chen
2013-01-01
Full Text Available The delay-dependent exponential L2-L∞ performance analysis and filter design are investigated for stochastic systems with mixed delays and nonlinear perturbations. Based on the delay partitioning and integral partitioning technique, an improved delay-dependent sufficient condition for the existence of the L2-L∞ filter is established, by choosing an appropriate Lyapunov-Krasovskii functional and constructing a new integral inequality. The full-order filter design approaches are obtained in terms of linear matrix inequalities (LMIs. By solving the LMIs and using matrix decomposition, the desired filter gains can be obtained, which ensure that the filter error system is exponentially stable with a prescribed L2-L∞ performance γ. Numerical examples are provided to illustrate the effectiveness and significant improvement of the proposed method.
Ncomanzi, Dumisani; Sicat, Rhea Mae R; Sundararajan, Krishnaswamy
2014-05-21
Lactic acidosis is the most common cause of metabolic acidosis in hospitalized patients. It is recognized as a potential complication of metformin use, particularly in patients with risk factors such as renal dysfunction, liver disease, and heavy alcohol ingestion. These conditions are associated with systemic hypoxemia, which may be caused by cardiorespiratory disease, major surgery, sepsis, dehydration, old age, and overdose. The reported frequency of lactic acidosis is 0.06 per 1000 patient-years, mostly in patients with predisposing factors. This case is important because it details the seriousness of metformin-associated lactic acidosis in a critically ill patient and because, to the best of our knowledge, our patient survived with minimal residual defect despite experiencing a cardiac arrest. A 66-year-old Caucasian woman presented to our hospital with profound lactic acidosis, which was initially thought to be ischemic gut. She then survived an in-hospital pulseless electrical activity arrest. Metformin-associated lactic acidosis is a diagnosis by exclusion; however, a high degree of clinical suspicion supplemented by prompt multisystem organ support can significantly influence the outcome in critically ill patients.
Si, Wenjie; Dong, Xunde; Yang, Feifei
2018-03-01
This paper is concerned with the problem of decentralized adaptive backstepping state-feedback control for uncertain high-order large-scale stochastic nonlinear time-delay systems. For the control design of high-order large-scale nonlinear systems, only one adaptive parameter is constructed to overcome the over-parameterization, and neural networks are employed to cope with the difficulties raised by completely unknown system dynamics and stochastic disturbances. And then, the appropriate Lyapunov-Krasovskii functional and the property of hyperbolic tangent functions are used to deal with the unknown unmatched time-delay interactions of high-order large-scale systems for the first time. At last, on the basis of Lyapunov stability theory, the decentralized adaptive neural controller was developed, and it decreases the number of learning parameters. The actual controller can be designed so as to ensure that all the signals in the closed-loop system are semi-globally uniformly ultimately bounded (SGUUB) and the tracking error converges in the small neighborhood of zero. The simulation example is used to further show the validity of the design method. Copyright © 2018 Elsevier Ltd. All rights reserved.
The Influence of Gene Expression Time Delays on Gierer–Meinhardt Pattern Formation Systems
Seirin Lee, S.
2010-03-23
There are numerous examples of morphogen gradients controlling long range signalling in developmental and cellular systems. The prospect of two such interacting morphogens instigating long range self-organisation in biological systems via a Turing bifurcation has been explored, postulated, or implicated in the context of numerous developmental processes. However, modelling investigations of cellular systems typically neglect the influence of gene expression on such dynamics, even though transcription and translation are observed to be important in morphogenetic systems. In particular, the influence of gene expression on a large class of Turing bifurcation models, namely those with pure kinetics such as the Gierer-Meinhardt system, is unexplored. Our investigations demonstrate that the behaviour of the Gierer-Meinhardt model profoundly changes on the inclusion of gene expression dynamics and is sensitive to the sub-cellular details of gene expression. Features such as concentration blow up, morphogen oscillations and radical sensitivities to the duration of gene expression are observed and, at best, severely restrict the possible parameter spaces for feasible biological behaviour. These results also indicate that the behaviour of Turing pattern formation systems on the inclusion of gene expression time delays may provide a means of distinguishing between possible forms of interaction kinetics. Finally, this study also emphasises that sub-cellular and gene expression dynamics should not be simply neglected in models of long range biological pattern formation via morphogens. © 2010 Society for Mathematical Biology.
Niu, Ben; Li, Lu
2017-04-17
This brief proposes a new neural-network (NN)-based adaptive output tracking control scheme for a class of disturbed multiple-input multiple-output uncertain nonlinear switched systems with input delays. By combining the universal approximation ability of radial basis function NNs and adaptive backstepping recursive design with an improved multiple Lyapunov function (MLF) scheme, a novel adaptive neural output tracking controller design method is presented for the switched system. The feature of the developed design is that different coordinate transformations are adopted to overcome the conservativeness caused by adopting a common coordinate transformation for all subsystems. It is shown that all the variables of the resulting closed-loop system are semiglobally uniformly ultimately bounded under a class of switching signals in the presence of MLF and that the system output can follow the desired reference signal. To demonstrate the practicability of the obtained result, an adaptive neural output tracking controller is designed for a mass-spring-damper system.
DEFF Research Database (Denmark)
Laut, Kristina Grønborg; Hjort, Jacob; Engstrøm, Thomas
2014-01-01
system delay and time to return to the labor market was analyzed using a competing-risk regression analysis. Association between system delay and time to retirement from work was analyzed using a Cox regression model. A total of 4,061 patients were included. Ninety-three percent returned to the labor......System delay (delay from emergency medical service call to reperfusion with primary percutaneous coronary intervention [PPCI]) is acknowledged as a performance measure in ST-elevation myocardial infarction (STEMI), as shorter system delay is associated with lower mortality. It is unknown whether...... system delay also impacts ability to stay in the labor market. Therefore, the aim of the study was to evaluate whether system delay is associated with duration of absence from work or time to retirement from work among patients with STEMI treated with PPCI. We conducted a population-based cohort study...
Bifurcation onset delay in magnetic bearing systems by time varying stiffness
Ghazavi, M. R.; Sun, Q.
2017-06-01
We study the nonlinear dynamics behaviours of a rigid rotor supported by magnetic bearings. In particular, we consider the effect of rotor unbalanced mass and geometric coupling. Existing works in literature have mostly focused on a single value of parameter or a smaller range of the nonlinearities introduced by rotor imbalance and geometric coupling. This is partly due to the use of a linear PD controller which limits the system performance. In this paper, we use a nonlinear PD controller by adopting a time varying stiffness term. The control gains are chosen according to the stability chart for a Mathieu's equation. Consequently, we observe a delay in the onset of bifurcation indicating an improved rotor performance.
Delay-feedback control strategy for reducing CO2 emission of traffic flow system
Zhang, Li-Dong; Zhu, Wen-Xing
2015-06-01
To study the signal control strategy for reducing traffic emission theoretically, we first presented a kind of discrete traffic flow model with relative speed term based on traditional coupled map car-following model. In the model, the relative speed difference between two successive running cars is incorporated into following vehicle's acceleration running equation. Then we analyzed its stability condition with discrete control system stability theory. Third, we designed a delay-feedback controller to suppress traffic jam and decrease traffic emission based on modern controller theory. Last, numerical simulations are made to support our theoretical results, including the comparison of models' stability analysis, the influence of model type and signal control on CO2 emissions. The results show that the temporal behavior of our model is superior to other models, and the traffic signal controller has good effect on traffic jam suppression and traffic CO2 emission, which fully supports the theoretical conclusions.
Low Access Delay Anti-Collision Algorithm for Reader in RFID systems
DEFF Research Database (Denmark)
Galiotto, Carlo; Marchetti, Nicola; Prasad, Neeli R.
2010-01-01
Radio Frequency Identification (RFID) is a technology which is spreading more and more as a medium to identify, locate and track assets through the productive chain. As all the wireless communication devices sharing the same transmission channel, RFID readers and tags experience collisions whenever...... deployed over the same area. In this work, the RFID reader collision problem is studied and a centralized scheduling-based algorithm is proposed as possible candidate solution, especially for those scenarios involving static or low mobility readers. Taking into account the circuitry limitations of the tags......, which do not allow to use frequency or code division multiple access schemes in the RFID systems, this paper proposes an algorithm aiming to prevent the readers collisions, while keeping the access delay of the readers to the channel possibly low. The simulation results show that this algorithm performs...
Directory of Open Access Journals (Sweden)
Koofigar Hamid Reza
2017-09-01
Full Text Available A robust auxiliary wide area damping controller is proposed for a unified power flow controller (UPFC. The mixed H2 / H∞ problem with regional pole placement, resolved by linear matrix inequality (LMI, is applied for controller design. Based on modal analysis, the optimal wide area input signals for the controller are selected. The time delay of input signals, due to electrical distance from the UPFC location is taken into account in the design procedure. The proposed controller is applied to a multi-machine interconnected power system from the IRAN power grid. It is shown that the both transient and dynamic stability are significantly improved despite different disturbances and loading conditions.
Cardullo, Frank M.; Lewis, Harold W., III; Panfilov, Peter B.
2007-01-01
An extremely innovative approach has been presented, which is to have the surgeon operate through a simulator running in real-time enhanced with an intelligent controller component to enhance the safety and efficiency of a remotely conducted operation. The use of a simulator enables the surgeon to operate in a virtual environment free from the impediments of telecommunication delay. The simulator functions as a predictor and periodically the simulator state is corrected with truth data. Three major research areas must be explored in order to ensure achieving the objectives. They are: simulator as predictor, image processing, and intelligent control. Each is equally necessary for success of the project and each of these involves a significant intelligent component in it. These are diverse, interdisciplinary areas of investigation, thereby requiring a highly coordinated effort by all the members of our team, to ensure an integrated system. The following is a brief discussion of those areas. Simulator as a predictor: The delays encountered in remote robotic surgery will be greater than any encountered in human-machine systems analysis, with the possible exception of remote operations in space. Therefore, novel compensation techniques will be developed. Included will be the development of the real-time simulator, which is at the heart of our approach. The simulator will present real-time, stereoscopic images and artificial haptic stimuli to the surgeon. Image processing: Because of the delay and the possibility of insufficient bandwidth a high level of novel image processing is necessary. This image processing will include several innovative aspects, including image interpretation, video to graphical conversion, texture extraction, geometric processing, image compression and image generation at the surgeon station. Intelligent control: Since the approach we propose is in a sense predictor based, albeit a very sophisticated predictor, a controller, which not only
Liu, Shichao; Liu, Peter Xiaoping; Wang, Xiaoyu
2017-01-01
This survey is to summarize and compare existing and recently emerging approaches for the analysis and compensation of the effects of network-induced delays on the stability and performance of communication-based power control systems. Several important communication-based power control systems are briefly introduced. The deterministic and stochastic methodologies of analyzing the impacts of network-induced delays on the stability of the communication-based power control systems are summarized and compared. A variety of control approaches are reviewed and compared for mitigating the effects of network-induced delays, depending on several design requirements, such as model dependence and design difficulty. The summary and comparison of these control approaches in this survey provide researchers and utilities valuable guidance for designing advanced communication-based power control systems in the future. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.
Directory of Open Access Journals (Sweden)
Yuan Ren
2016-01-01
Full Text Available This paper analyzes the effects of time delay on the stability of the rotation modes for the magnetically suspended flywheel (MSFW with strong gyroscopic effects. A multi-input multioutput system is converted into a single-input single-output control system with complex coefficient by variable reconstruction, and the stability equivalence of the systems before and after variable reconstruction is proven. For the rotation modes, the stability limits and corresponding vibration frequencies are found as a function of nondimensional magnetic stiffness and damping and nondimensional parameters of rotor speed and time delay. Additionally, the relationship between cross feedback control system stability and time delay is investigated. And an effective phase compensation method based on cross-channel is further presented. Simulation and experimental results are presented to demonstrate the correctness of the stability analysis method and the superiority of the phase compensation strategy.
DEFF Research Database (Denmark)
Mi, Yang; Hao, Xuezhi; Liu, Yongjuan
2017-01-01
The interconnected time-delay power system has become an important issue for the open communication network. Meanwhile, due to the output power fluctuation of integrated wind energy, load frequency control (LFC) for power system with variable sources and loads has become more complicated. The novel...... the hitting condition. At last, the SM controller is proved by using the real-time digital simulator device under different case of time delay, wind penetration, load disturbance and operating point. The test results show that the proposed SM LFC can reduce frequency deviation and tie-line power fluctuation...... decentralised sliding mode (SM) LFC strategy is proposed for multi-area time-delay power system with significant wind power penetration. The appropriate switching surface gain is selected to assure the stability of power system with mismatched uncertainties. The SM controller is constructed to satisfy...
Budzinskiy, S. S.; Razgulin, A. V.
2017-08-01
In this paper we study one-dimensional rotating and standing waves in a model of an O(2)-symmetric nonlinear optical system with diffraction and delay in the feedback loop whose dynamics is governed by a system of coupled delayed parabolic equation and linear Schrodinger-type equation. We elaborate a two-step approach: transition to a rotating coordinate system to obtain the profiles of the waves as small parameter expansions and the normal form technique to study their qualitative dynamic behavior and stability. Theoretical results stand in a good agreement with direct computer simulations presented.
Priya, B. Ganesh; Muthukumar, P.
2018-02-01
This paper deals with the trajectory controllability for a class of multi-order fractional linear systems subject to a constant delay in state vector. The solution for the coupled fractional delay differential equation is established by the Mittag-Leffler function. The necessary and sufficient condition for the trajectory controllability is formulated and proved by the generalized Gronwall's inequality. The approximate trajectory for the proposed system is obtained through the shifted Jacobi operational matrix method. The numerical simulation of the approximate solution shows the theoretical results. Finally, some remarks and comments on the existing results of constrained controllability for the fractional dynamical system are also presented.
International Nuclear Information System (INIS)
Lin Juisheng; Liao Tehlu; Yan Junjuh; Yau Herterng
2005-01-01
In this paper, an adaptive robust observer-based scheme for the synchronization of unidirectional coupled chaotic systems with unknown channel time-delay and system uncertainties is proposed. The effects of time-delay arise from the physical characteristics of coupled channel, while the system uncertainties arise due to unknown but bounded external disturbances and parametric perturbations. By appropriately selecting the observer controller and adaptation mechanism, the master-slave chaotic synchronization can be guaranteed by Lyapunov approach. Finally, the Chua's circuit is used as an illustrative example, where simulation results are given to demonstrate the effectiveness of the proposed scheme
Rajagopal, Karthikeyan; Pham, Viet-Thanh; Tahir, Fadhil Rahma; Akgul, Akif; Abdolmohammadi, Hamid Reza; Jafari, Sajad
2018-04-01
The literature on chaos has highlighted several chaotic systems with special features. In this work, a novel chaotic jerk system with non-hyperbolic equilibrium is proposed. The dynamics of this new system is revealed through equilibrium analysis, phase portrait, bifurcation diagram and Lyapunov exponents. In addition, we investigate the time-delay effects on the proposed system. Realisation of such a system is presented to verify its feasibility.
Delay-induced stochastic bifurcations in a bistable system under white noise
Energy Technology Data Exchange (ETDEWEB)
Sun, Zhongkui, E-mail: sunzk@nwpu.edu.cn; Fu, Jin; Xu, Wei [Department of Applied Mathematics, Northwestern Polytechnical University, Xi' an 710072 (China); Xiao, Yuzhu [Department of Mathematics and Information Science, Chang' an University, Xi' an 710086 (China)
2015-08-15
In this paper, the effects of noise and time delay on stochastic bifurcations are investigated theoretically and numerically in a time-delayed Duffing-Van der Pol oscillator subjected to white noise. Due to the time delay, the random response is not Markovian. Thereby, approximate methods have been adopted to obtain the Fokker-Planck-Kolmogorov equation and the stationary probability density function for amplitude of the response. Based on the knowledge that stochastic bifurcation is characterized by the qualitative properties of the steady-state probability distribution, it is found that time delay and feedback intensity as well as noise intensity will induce the appearance of stochastic P-bifurcation. Besides, results demonstrated that the effects of the strength of the delayed displacement feedback on stochastic bifurcation are accompanied by the sensitive dependence on time delay. Furthermore, the results from numerical simulations best confirm the effectiveness of the theoretical analyses.
Delay-induced stochastic bifurcations in a bistable system under white noise
International Nuclear Information System (INIS)
Sun, Zhongkui; Fu, Jin; Xu, Wei; Xiao, Yuzhu
2015-01-01
In this paper, the effects of noise and time delay on stochastic bifurcations are investigated theoretically and numerically in a time-delayed Duffing-Van der Pol oscillator subjected to white noise. Due to the time delay, the random response is not Markovian. Thereby, approximate methods have been adopted to obtain the Fokker-Planck-Kolmogorov equation and the stationary probability density function for amplitude of the response. Based on the knowledge that stochastic bifurcation is characterized by the qualitative properties of the steady-state probability distribution, it is found that time delay and feedback intensity as well as noise intensity will induce the appearance of stochastic P-bifurcation. Besides, results demonstrated that the effects of the strength of the delayed displacement feedback on stochastic bifurcation are accompanied by the sensitive dependence on time delay. Furthermore, the results from numerical simulations best confirm the effectiveness of the theoretical analyses
Atrioventricular conduction abnormality and hyperchloremic metabolic acidosis in toluene sniffing
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Jian-Hsiung Tsao
2011-10-01
Full Text Available Toluene is an aromatic hydrocarbon with widespread industrial use as an organic solvent. As a result of the euphoric effect and availability of these substances, inhalation of toluene-based products is popular among young adults and children. Chronic or acute exposure is known to cause acid–base and electrolyte disorders, and to be toxic to the nervous and hematopoietic systems. We report a 38-year-old man who suffered from general muscular weakness of all extremities after toluene sniffing, which was complicated with hypokalemic paralysis, atrioventricular conduction abnormality, and normal anion gap hyperchloremic metabolic acidosis. Renal function, serum potassium and acid–base status normalized within 3 days after aggressive potassium chloride and intravenous fluid replacement. Electrocardiography showed regression of first-degree atrioventricular block. Exposure to toluene can lead to cardiac arrhythmias and sudden sniffing death syndrome. Tachyarrhythmia is the classical manifestation of toluene cardiotoxicity. Atrioventricular conduction abnormalities have been rarely mentioned in the literature. Knowledge of the toxicology and medical complications associated with toluene sniffing is essential for clinical management of these patients.
Chen, Dongyan; Xu, Long; Du, Junhua
2016-03-01
The optimal filtering problem is investigated for a class of discrete stochastic systems with finite-step autocorrelated process noises, random one-step sensor delay and missing measurements. The random disturbances existing in the system are characterized by the multiplicative noises and the phenomena of sensor delay and missing measurements occur in a random way. The random sensor delay and missing measurements are described by two Bernoulli distributed random variables with known conditional probabilities. By using the state augmentation approach, the original system is converted into a new discrete system where the random one-step sensor delay and missing measurements exist in the sensor output. The new process noises and observation noises consist of the original stochastic terms, and the process noises are still autocorrelated. Then, based on the minimum mean square error (MMSE) principle, a new linear optimal filter is designed such that, for the finite-step autocorrelated process noises, random one-step sensor delay and missing measurements, the estimation error is minimized. By solving the recursive matrix equation, the filter gain is designed. Finally, a simulation example is given to illustrate the feasibility and effectiveness of the proposed filtering scheme.
Klotz, Justin R; Obuz, Serhat; Kan, Zhen; Dixon, Warren E
2018-02-01
A decentralized controller is designed for leader-based synchronization of communication-delayed networked agents. The agents have heterogeneous dynamics modeled by uncertain, nonlinear Euler-Lagrange equations of motion affected by heterogeneous, unknown, exogenous disturbances. The developed controller requires only one-hop (delayed) communication from network neighbors and the communication delays are assumed to be heterogeneous, uncertain, and time-varying. Each agent uses an estimate of communication delay to provide feedback of estimated recent tracking error. Simulation results are provided to demonstrate the improved performance of the developed controller over other popular control designs.
Robust L2-L∞ Filtering of Time-Delay Jump Systems with Respect to the Finite-Time Interval
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Shuping He
2011-01-01
Full Text Available This paper studied the problem of stochastic finite-time boundedness and disturbance attenuation for a class of linear time-delayed systems with Markov jumping parameters. Sufficient conditions are provided to solve this problem. The L2-L∞ filters are, respectively, designed for time-delayed Markov jump linear systems with/without uncertain parameters such that the resulting filtering error dynamic system is stochastically finite-time bounded and has the finite-time interval disturbance attenuation γ for all admissible uncertainties, time delays, and unknown disturbances. By using stochastic Lyapunov-Krasovskii functional approach, it is shown that the filter designing problem is in terms of the solutions of a set of coupled linear matrix inequalities. Simulation examples are included to demonstrate the potential of the proposed results.
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Fengxia Xu
2014-01-01
Full Text Available U-model can approximate a large class of smooth nonlinear time-varying delay system to any accuracy by using time-varying delay parameters polynomial. This paper proposes a new approach, namely, U-model approach, to solving the problems of analysis and synthesis for nonlinear systems. Based on the idea of discrete-time U-model with time-varying delay, the identification algorithm of adaptive neural network is given for the nonlinear model. Then, the controller is designed by using the Newton-Raphson formula and the stability analysis is given for the closed-loop nonlinear systems. Finally, illustrative examples are given to show the validity and applicability of the obtained results.
Faria, Teresa
2017-07-01
For a family of n-dimensional periodic delay differential equations which encompasses a broad set of models used in structured population dynamics, the existence of a positive periodic solution is obtained under very mild conditions. The proof uses the Schauder fixed point theorem and relies on the permanence of the system. A general criterion for the existence of a positive periodic solution for Nicholson's blowflies periodic systems (with both distributed and discrete time-varying delays) is derived as a simple application of our main result, generalizing the few existing results concerning multi-dimensional Nicholson models. In the case of a Nicholson system with discrete delays all multiples of the period, the global attractivity of the positive periodic solution is further analyzed, improving results in recent literature.
D'Agostino, Dominic P; Pilla, Raffaele; Held, Heather E; Landon, Carol S; Puchowicz, Michelle; Brunengraber, Henri; Ari, Csilla; Arnold, Patrick; Dean, Jay B
2013-05-15
Central nervous system oxygen toxicity (CNS-OT) seizures occur with little or no warning, and no effective mitigation strategy has been identified. Ketogenic diets (KD) elevate blood ketones and have successfully treated drug-resistant epilepsy. We hypothesized that a ketone ester given orally as R,S-1,3-butanediol acetoacetate diester (BD-AcAc(2)) would delay CNS-OT seizures in rats breathing hyperbaric oxygen (HBO(2)). Adult male rats (n = 60) were implanted with radiotelemetry units to measure electroencephalogram (EEG). One week postsurgery, rats were administered a single oral dose of BD-AcAc(2), 1,3-butanediol (BD), or water 30 min before being placed into a hyperbaric chamber and pressurized to 5 atmospheres absolute (ATA) O2. Latency to seizure (LS) was measured from the time maximum pressure was reached until the onset of increased EEG activity and tonic-clonic contractions. Blood was drawn at room pressure from an arterial catheter in an additional 18 animals that were administered the same compounds, and levels of glucose, pH, Po(2), Pco(2), β-hydroxybutyrate (BHB), acetoacetate (AcAc), and acetone were analyzed. BD-AcAc(2) caused a rapid (30 min) and sustained (>4 h) elevation of BHB (>3 mM) and AcAc (>3 mM), which exceeded values reported with a KD or starvation. BD-AcAc(2) increased LS by 574 ± 116% compared with control (water) and was due to the effect of AcAc and acetone but not BHB. BD produced ketosis in rats by elevating BHB (>5 mM), but AcAc and acetone remained low or undetectable. BD did not increase LS. In conclusion, acute oral administration of BD-AcAc(2) produced sustained ketosis and significantly delayed CNS-OT seizures by elevating AcAc and acetone.
Rosinberg, M. L.; Munakata, T.; Tarjus, G.
2015-04-01
Response lags are generic to almost any physical system and often play a crucial role in the feedback loops present in artificial nanodevices and biological molecular machines. In this paper, we perform a comprehensive study of small stochastic systems governed by an underdamped Langevin equation and driven out of equilibrium by a time-delayed continuous feedback control. In their normal operating regime, these systems settle in a nonequilibrium steady state in which work is permanently extracted from the surrounding heat bath. By using the Fokker-Planck representation of the dynamics, we derive a set of second-law-like inequalities that provide bounds to the rate of extracted work. These inequalities involve additional contributions characterizing the reduction of entropy production due to the continuous measurement process. We also show that the non-Markovian nature of the dynamics requires a modification of the basic relation linking dissipation to the breaking of time-reversal symmetry at the level of trajectories. The modified relation includes a contribution arising from the acausal character of the reverse process. This, in turn, leads to another second-law-like inequality. We illustrate the general formalism with a detailed analytical and numerical study of a harmonic oscillator driven by a linear feedback, which describes actual experimental setups.
Testing Solutions of the Protection Systems Provided with Delay Maximum Current Relays
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Horia BALAN
2017-12-01
Full Text Available Relay protection is one of the main forms of automation control of electro energy systems, having as primary aims fault detection and disconnection of the faulty element in order to avoid the extent of damages and the as fast as possible recovery to the normal operation regime for the rest of the system. Faults that occur in the electro energy system can be classified considering on one hand their causes and on the other their types, but in the vast majority of cases the causes of the faults are combined. Further, considering their nature, faults are classified in faults due to the insulation’s damage, in faults due to the destruction of the integrity of the circuits and faults determined by interruptions. With respect to their nature, faults are short circuits, earthing faults and phases interruptions. At the same time, considering their type, faults are divided in transversal and longitudinal ones. The paper presents a testing solution of the delayed maximal current relays using a T3000 ISA Test measuring equipment.
Metabolic acidosis in an infant associated with permethrin toxicity.
Goksugur, Sevil B; Karatas, Zehra; Goksugur, Nadir; Bekdas, Mervan; Demircioglu, Fatih
2015-01-01
Pyrethroids are broad-spectrum insecticides. Permethrin intoxication due to topical application has not been documented in humans. We report a 20-month-old infant who had used 5% permethrin lotion topically for scabies treatment. Approximately 60 mL (20 mL/day) was used and after the third application he developed agitation, nausea, vomiting, respiratory distress, tachycardia, and metabolic acidosis. His clinical symptoms and metabolic acidosis normalized within 20 hours. His follow-up was unremarkable. Toxicity of permethrin is rare, and although permethrin is a widely and safely used topical agent in the treatment of scabies and lice, inappropriate use may rarely cause toxicity. Moreover, in cases of unexplained metabolic acidosis, topically applied medications should be carefully investigated. © 2014 Wiley Periodicals, Inc.
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Weiwei Lyu
2017-11-01
Full Text Available Transfer alignment is always a key technology in a strapdown inertial navigation system (SINS because of its rapidity and accuracy. In this paper a transfer alignment model is established, which contains the SINS error model and the measurement model. The time delay in the process of transfer alignment is analyzed, and an H∞ filtering method with delay compensation is presented. Then the H∞ filtering theory and the robust mechanism of H∞ filter are deduced and analyzed in detail. In order to improve the transfer alignment accuracy in SINS with time delay, an adaptive H∞ filtering method with delay compensation is proposed. Since the robustness factor plays an important role in the filtering process and has effect on the filtering accuracy, the adaptive H∞ filter with delay compensation can adjust the value of robustness factor adaptively according to the dynamic external environment. The vehicle transfer alignment experiment indicates that by using the adaptive H∞ filtering method with delay compensation, the transfer alignment accuracy and the pure inertial navigation accuracy can be dramatically improved, which demonstrates the superiority of the proposed filtering method.
Lyu, Weiwei; Cheng, Xianghong
2017-11-28
Transfer alignment is always a key technology in a strapdown inertial navigation system (SINS) because of its rapidity and accuracy. In this paper a transfer alignment model is established, which contains the SINS error model and the measurement model. The time delay in the process of transfer alignment is analyzed, and an H∞ filtering method with delay compensation is presented. Then the H∞ filtering theory and the robust mechanism of H∞ filter are deduced and analyzed in detail. In order to improve the transfer alignment accuracy in SINS with time delay, an adaptive H∞ filtering method with delay compensation is proposed. Since the robustness factor plays an important role in the filtering process and has effect on the filtering accuracy, the adaptive H∞ filter with delay compensation can adjust the value of robustness factor adaptively according to the dynamic external environment. The vehicle transfer alignment experiment indicates that by using the adaptive H∞ filtering method with delay compensation, the transfer alignment accuracy and the pure inertial navigation accuracy can be dramatically improved, which demonstrates the superiority of the proposed filtering method.
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Chen Lansun
2010-01-01
Full Text Available We consider a delayed Holling type II predator-prey system with birth pulse and impulsive harvesting on predator population at different moments. Firstly, we prove that all solutions of the investigated system are uniformly ultimately bounded. Secondly, the conditions of the globally attractive prey-extinction boundary periodic solution of the investigated system are obtained. Finally, the permanence of the investigated system is also obtained. Our results provide reliable tactic basis for the practical biological economics management.
DEFF Research Database (Denmark)
Jing, Lishuai; Pedersen, Troels; Fleury, Bernard Henri
2013-01-01
We address the problem of searching for the optimal pilot signal, i.e. pattern and signature, of an orthogonal frequency-division multiplexing (OFDM) system when the purpose is to estimate the delay and Doppler shift under the assumption of a single-path propagation channel. This problem is relev......We address the problem of searching for the optimal pilot signal, i.e. pattern and signature, of an orthogonal frequency-division multiplexing (OFDM) system when the purpose is to estimate the delay and Doppler shift under the assumption of a single-path propagation channel. This problem...
Pan, Indranil; Das, Saptarshi; Gupta, Amitava
2011-01-01
An optimal PID and an optimal fuzzy PID have been tuned by minimizing the Integral of Time multiplied Absolute Error (ITAE) and squared controller output for a networked control system (NCS). The tuning is attempted for a higher order and a time delay system using two stochastic algorithms viz. the Genetic Algorithm (GA) and two variants of Particle Swarm Optimization (PSO) and the closed loop performances are compared. The paper shows that random variation in network delay can be handled efficiently with fuzzy logic based PID controllers over conventional PID controllers. Copyright © 2010 ISA. Published by Elsevier Ltd. All rights reserved.
Koffarnus, Mikhail N.; Jarmolowicz, David P.; Mueller, E. Terry; Bickel, Warren K.
2013-01-01
Excessively devaluing delayed reinforcers co-occurs with a wide variety of clinical conditions such as drug dependence, obesity, and excessive gambling. If excessive delay discounting is a trans-disease process that underlies the choice behavior leading to these and other negative health conditions, efforts to change an individual's discount rate…
Differential Diagnosis of Nongap Metabolic Acidosis: Value of a Systematic Approach
Kraut, Jeffrey A.; Madias, Nicolaos E.
2012-01-01
Nongap metabolic acidosis is a common form of both acute and chronic metabolic acidosis. Because derangements in renal acid-base regulation are a common cause of nongap metabolic acidosis, studies to evaluate renal acidification often serve as the mainstay of differential diagnosis. However, in many cases, information obtained from the history and physical examination, evaluation of the electrolyte pattern (to determine if a nongap acidosis alone or a combined nongap and high anion gap metabo...
Respiration of Chemodenervated Goats in Acute Metabolic Acidosis,
1983-08-02
metabolic ) alkalosis . Furthermore, the ventilatory responses to increase in PaCO2 produced by CO2 inhalation are shifted to lower values of PaCO2 in...the presence of metabolic acidosis, and to higher PaCO2 vaiues in metabolic alkalosis (Fencl et al. [1966]). The roles played by the carotid bodies (CB...and J.A. Broch (1969). Respiration and cerebral blood flow in metabolic acidosis and alkalosis in humans. J. Appl. Physiol. 27: 67-76. Gabel, R.A
Type 4 renal tubular acidosis in a kidney transplant recipient
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Manjunath Kulkarni
2016-02-01
Full Text Available We report a case of a 66-year-old diabetic patient who presented with muscle weakness 2 weeks after kidney transplantation. Her immunosuppressive regimen included tacrolimus, mycophenolate mofetil, and steroids. She was found to have hyperkalemia and normal anion gap metabolic acidosis. Tacrolimus levels were in therapeutic range. All other drugs such as beta blockers and trimethoprim – sulfamethoxazole were stopped. She did not respond to routine antikalemic measures. Further evaluation revealed type 4 renal tubular acidosis. Serum potassium levels returned to normal after starting sodium bicarbonate and fludrocortisone therapy. Though hyperkalemia is common in kidney transplant recipients, determining exact cause can guide specific treatment.
Willis, Monte S; Cairns, Bruce A; Purdy, Ashley; Bortsov, Andrey V; Jones, Samuel W; Ortiz-Pujols, Shiara M; Willis, Tina M Schade; Jr, Benny L Joyner
2013-01-01
A 3-year old male who sustained 2nd and 3rd degree burns that covered approximately 60% TBSA presented to a large adult and pediatric verified burn center. On hospital day (HD) 26 of his stay, Candida fungemia was identified by blood culture, delaying operative management until HD 47. On HD 47, after his first operative intervention, the patient developed a persistent metabolic and lactic acidosis. On HD 66, a search for a cause of his osmol gap of 56 mOsm/kg revealed a potential source-propy...
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Hongtao Yang
2018-01-01
Full Text Available This paper proposes a novel strong tracking filter (STF, which is suitable for dealing with the filtering problem of nonlinear systems when the following cases occur: that is, the constructed model does not match the actual system, the measurements have the one-step random delay, and the process and measurement noises are correlated at the same epoch. Firstly, a framework of decoupling filter (DF based on equivalent model transformation is derived. Further, according to the framework of DF, a new extended Kalman filtering (EKF algorithm via using first-order linearization approximation is developed. Secondly, the computational process of the suboptimal fading factor is derived on the basis of the extended orthogonality principle (EOP. Thirdly, the ultimate form of the proposed STF is obtained by introducing the suboptimal fading factor into the above EKF algorithm. The proposed STF can automatically tune the suboptimal fading factor on the basis of the residuals between available and predicted measurements and further the gain matrices of the proposed STF tune online to improve the filtering performance. Finally, the effectiveness of the proposed STF has been proved through numerical simulation experiments.
Critical capacity, travel time delays and travel time distribution of rapid mass transit systems
Legara, Erika Fille; Monterola, Christopher; Lee, Kee Khoon; Hung, Gih Guang
2014-07-01
We set up a mechanistic agent-based model of a rapid mass transit system. Using empirical data from Singapore's unidentifiable smart fare card, we validate our model by reconstructing actual travel demand and duration of travel statistics. We subsequently use this model to investigate two phenomena that are known to significantly affect the dynamics within the RTS: (1) overloading in trains and (2) overcrowding in the RTS platform. We demonstrate that by varying the loading capacity of trains, a tipping point emerges at which an exponential increase in the duration of travel time delays is observed. We also probe the impact on the rail system dynamics of three types of passenger growth distribution across stations: (i) Dirac delta, (ii) uniform and (iii) geometric, which is reminiscent of the effect of land use on transport. Under the assumption of a fixed loading capacity, we demonstrate the dependence of a given origin-destination (OD) pair on the flow volume of commuters in station platforms.
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Se Young Kim
2015-12-01
Full Text Available It is important to fast diagnosis and management of the pediatric patients of the endocrine metabolic emergencies because the signs and symptoms of these disorders are nonspecific. Delayed diagnosis and treatment may lead to serious consequences of the pediatric patients, for example, cerebral dysfunction leading to coma or death of the patients with hypoglycemia, hypocalcemia, adrenal insufficiency, or diabetic ketoacidosis. The index of suspicion of the endocrine metabolic emergencies should be preceded prior to the starting nonspecific treatment. Importantly, proper diagnosis depends on the collection of blood and urine specimen before nonspecific therapy (intravenous hydration, electrolytes, glucose or calcium injection. At the same time, the taking of precise history and searching for pathognomonic physical findings should be performed. This review was described for fast diagnosis and proper management of hypoglycemic emergencies, hypocalcemia, adrenal insufficiency, and metabolic acidosis including diabetic ketoacidosis.
Kim, Se Young
2015-12-01
It is important to fast diagnosis and management of the pediatric patients of the endocrine metabolic emergencies because the signs and symptoms of these disorders are nonspecific. Delayed diagnosis and treatment may lead to serious consequences of the pediatric patients, for example, cerebral dysfunction leading to coma or death of the patients with hypoglycemia, hypocalcemia, adrenal insufficiency, or diabetic ketoacidosis. The index of suspicion of the endocrine metabolic emergencies should be preceded prior to the starting nonspecific treatment. Importantly, proper diagnosis depends on the collection of blood and urine specimen before nonspecific therapy (intravenous hydration, electrolytes, glucose or calcium injection). At the same time, the taking of precise history and searching for pathognomonic physical findings should be performed. This review was described for fast diagnosis and proper management of hypoglycemic emergencies, hypocalcemia, adrenal insufficiency, and metabolic acidosis including diabetic ketoacidosis.
Directory of Open Access Journals (Sweden)
Dan Ye
2013-01-01
Full Text Available This paper is concerned with delay-dependent stochastic stability for time-delay Markovian jump systems (MJSs with sector-bounded nonlinearities and more general transition probabilities. Different from the previous results where the transition probability matrix is completely known, a more general transition probability matrix is considered which includes completely known elements, boundary known elements, and completely unknown ones. In order to get less conservative criterion, the state and transition probability information is used as much as possible to construct the Lyapunov-Krasovskii functional and deal with stability analysis. The delay-dependent sufficient conditions are derived in terms of linear matrix inequalities to guarantee the stability of systems. Finally, numerical examples are exploited to demonstrate the effectiveness of the proposed method.
Minding the Gap: Utility of the Anion Gap in the Differential Diagnosis of Metabolic Acidosis.
Bell, Susan Givens
2017-07-01
The anion gap, in conjunction with other laboratory results, can be a useful clue in the differential diagnosis of metabolic acidosis. There are three primary causes of metabolic acidosis: loss of base, decreased renal excretion of acid, and increased acid production. Depending on the cause of metabolic acidosis, the anion gap may be elevated or normal.
Impact of size and delay on neural activity in the rat limbic corticostriatal system
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Matthew R Roesch
2011-12-01
Full Text Available A number of factors influence an animal’s economic decisions. Two most commonly studied are the magnitude of and delay to reward. To investigate how these factors are represented in the firing rates of single neurons, we devised a behavioral task that independently manipulated the expected delay to and size of reward. Rats perceived the differently delayed and sized rewards as having different values and were more motivated under short-delay and big-reward conditions than under long-delay and small-reward conditions as measured by percent choice, accuracy and reaction time. Since the creation of this task, we have recorded from several different brain areas including, orbitofrontal cortex, striatum, amygdala, substantia nigra pars reticulata, and midbrain dopamine neurons. Here, we review and compare those data with a substantial focus on those areas that have been shown to be critical for performance on classic time discounting procedures and provide a potential mechanism by which they might interact when animals are deciding between differently delayed rewards. We found that most brain areas in the cortico-limbic circuit encode both the magnitude and delay to reward delivery in one form or another, but only a few encode them together at the single neuron level.