Total Dose Effects on Error Rates in Linear Bipolar Systems
NASA Technical Reports Server (NTRS)
Buchner, Stephen; McMorrow, Dale; Bernard, Muriel; Roche, Nicholas; Dusseau, Laurent
2007-01-01
The shapes of single event transients in linear bipolar circuits are distorted by exposure to total ionizing dose radiation. Some transients become broader and others become narrower. Such distortions may affect SET system error rates in a radiation environment. If the transients are broadened by TID, the error rate could increase during the course of a mission, a possibility that has implications for hardness assurance.
Total Dose Effects on Single Event Transients in Linear Bipolar Systems
NASA Technical Reports Server (NTRS)
Buchner, Stephen; McMorrow, Dale; Bernard, Muriel; Roche, Nicholas; Dusseau, Laurent
2008-01-01
Single Event Transients (SETs) originating in linear bipolar integrated circuits are known to undermine the reliability of electronic systems operating in the radiation environment of space. Ionizing particle radiation produces a variety of SETs in linear bipolar circuits. The extent to which these SETs threaten system reliability depends on both their shapes (amplitude and width) and their threshold energies. In general, SETs with large amplitudes and widths are the most likely to propagate from a bipolar circuit's output through a subsystem. The danger these SET pose is that, if they become latched in a follow-on circuit, they could cause an erroneous system response. Long-term exposure of linear bipolar circuits to particle radiation produces total ionizing dose (TID) and/or displacement damage dose (DDD) effects that are characterized by a gradual degradation in some of the circuit's electrical parameters. For example, an operational amplifier's gain-bandwidth product is reduced by exposure to ionizing radiation, and it is this reduction that contributes to the distortion of the SET shapes. In this paper, we compare SETs produced in a pristine LM124 operational amplifier with those produced in one exposed to ionizing radiation for three different operating configurations - voltage follower (VF), inverter with gain (IWG), and non-inverter with gain (NIWG). Each configuration produces a unique set of transient shapes that change following exposure to ionizing radiation. An important finding is that the changes depend on operating configuration; some SETs decrease in amplitude, some remain relatively unchanged, some become narrower and some become broader.
Dose Rate Effects in Linear Bipolar Transistors
NASA Technical Reports Server (NTRS)
Johnston, Allan; Swimm, Randall; Harris, R. D.; Thorbourn, Dennis
2011-01-01
Dose rate effects are examined in linear bipolar transistors at high and low dose rates. At high dose rates, approximately 50% of the damage anneals at room temperature, even though these devices exhibit enhanced damage at low dose rate. The unexpected recovery of a significant fraction of the damage after tests at high dose rate requires changes in existing test standards. Tests at low temperature with a one-second radiation pulse width show that damage continues to increase for more than 3000 seconds afterward, consistent with predictions of the CTRW model for oxides with a thickness of 700 nm.
Dose Rate Effects in Linear Bipolar Transistors
NASA Technical Reports Server (NTRS)
Johnston, Allan; Swimm, Randall; Harris, R. D.; Thorbourn, Dennis
2011-01-01
Dose rate effects are examined in linear bipolar transistors at high and low dose rates. At high dose rates, approximately 50% of the damage anneals at room temperature, even though these devices exhibit enhanced damage at low dose rate. The unexpected recovery of a significant fraction of the damage after tests at high dose rate requires changes in existing test standards. Tests at low temperature with a one-second radiation pulse width show that damage continues to increase for more than 3000 seconds afterward, consistent with predictions of the CTRW model for oxides with a thickness of 700 nm.
Total dose dependency and ELDRS effects on bipolar linear devices
NASA Technical Reports Server (NTRS)
Yui, C. C.; McClure, S. S.; Rax, B. G.; Lehman, J. M.; Minto, T. D.; Wiedeman, M.
2002-01-01
The use of bipolar linear devices is prevalent in most satellite and some space applications. However, degradation as a result of low dose irradiations known as ELDERS (effects of enhanced low dose rate sensitivity) is a major concern when selecting flight hardware. Many studies and reports have been conducted on this possible phenomenon as well as their responsible physical mechanisms.
Total dose dependency and ELDRS effects on bipolar linear devices
NASA Technical Reports Server (NTRS)
Yui, C. C.; McClure, S. S.; Rax, B. G.; Lehman, J. M.; Minto, T. D.; Wiedeman, M.
2002-01-01
The use of bipolar linear devices is prevalent in most satellite and some space applications. However, degradation as a result of low dose irradiations known as ELDERS (effects of enhanced low dose rate sensitivity) is a major concern when selecting flight hardware. Many studies and reports have been conducted on this possible phenomenon as well as their responsible physical mechanisms.
Displacement Damage in Bipolar Linear Integrated Circuits
NASA Technical Reports Server (NTRS)
Rax, B. G.; Johnston, A. H.; Miyahira, T.
2000-01-01
Although many different processes can be used to manufacture linear integrated circuits, the process that is used for most circuits is optimized for high voltage -- a total power supply voltage of about 40 V -- and low cost. This process, which has changed little during the last twenty years, uses lateral and substrate p-n-p transistors. These p-n-p transistors have very wide base regions, increasing their sensitivity to displacement damage from electrons and protons. Although displacement damage effects can be easily treated for individual transistors, the net effect on linear circuits can be far more complex because circuit operation often depends on the interaction of several internal transistors. Note also that some circuits are made with more advanced processes with much narrower base widths. Devices fabricated with these newer processes are not expected to be significantly affected by displacement damage for proton fluences below 1 x 10(exp 12) p/sq cm. This paper discusses displacement damage in linear integrated circuits with more complex failure modes than those exhibited by simpler devices, such as the LM111 comparator, where the dominant response mode is gain degradation of the input transistor. Some circuits fail catastrophically at much lower equivalent total dose levels compared to tests with gamma rays. The device works satisfactorily up to nearly 1 Mrad(Si) when it is irradiated with gamma rays, but fails catastrophically between 50 and 70 krad(Si) when it is irradiated with protons.
New non-linear photovoltaic effect in uniform bipolar semiconductor
Volovichev, I.
2014-11-21
A linear theory of the new non-linear photovoltaic effect in the closed circuit consisting of a non-uniformly illuminated uniform bipolar semiconductor with neutral impurities is developed. The non-uniform photo-excitation of impurities results in the position-dependant current carrier mobility that breaks the semiconductor homogeneity and induces the photo-electromotive force (emf). As both the electron (or hole) mobility gradient and the current carrier generation rate depend on the light intensity, the photo-emf and the short-circuit current prove to be non-linear functions of the incident light intensity at an arbitrarily low illumination. The influence of the sample size on the photovoltaic effect magnitude is studied. Physical relations and distinctions between the considered effect and the Dember and bulk photovoltaic effects are also discussed.
Continuing evaluation of bipolar linear devices for total dose bias dependency and ELDRS effects
NASA Technical Reports Server (NTRS)
McClure, S. S.; Gorelick, J. J.; Yui, C. C.; Rax, B. G.; Wiedeman, M. D.
2003-01-01
We present results of continuing efforts to evaluate total dose bias dependency and ELDRS effects in bipolar linear microcircuits. Several devices were evaluated, each exhibiting moderate to significant bias and/or dose rate dependency.
Continuing evaluation of bipolar linear devices for total dose bias dependency and ELDRS effects
NASA Technical Reports Server (NTRS)
McClure, Steven S.; Gorelick, Jerry L.; Yui, Candice; Rax, Bernard G.; Wiedeman, Michael D.
2003-01-01
We present results of continuing efforts to evaluate total dose bias dependency and ELDRS effects in bipolar linear microcircuits. Several devices were evaluated, each exhibiting moderate to significant bias and/or dose rate dependency.
A new bipolar Qtrim power supply system
Mi, C.; Bruno, D.; Drozd, J.; Nolan, T.; Orsatti, F.; Heppener, G.; Di Lieto, A.; Schultheiss, C.; Samms, T.; Zapasek, R.; Sandberg, J.
2015-05-03
This year marks the 15th run of RHIC (Relativistic Heavy Ion Collider) operations. The reliability of superconducting magnet power supplies is one of the essential factors in the entire accelerator complex. Besides maintaining existing power supplies and their associated equipment, newly designed systems are also required based on the physicist’s latest requirements. A bipolar power supply was required for this year’s main quadruple trim power supply. This paper will explain the design, prototype, testing, installation and operation of this recently installed power supply system.
Total dose bias dependency and ELDRS effects in bipolar linear devices
NASA Technical Reports Server (NTRS)
Yui, C. C.; McClure, S. S.; Rex, B. G.; Lehman, J. M.; Minto, T. D.; Wiedeman, M.
2002-01-01
Total dose tests of several bipolar linear devices show sensitivity to both dose rate and bias during exposure. All devices exhibited Enhanced Low Dose Rate Sensitivity (ELDRS). An accelerated ELDRS test method for three different devices demonstrate results similar to tests at low dose rate. Behavior and critical parameters from these tests are compared and discussed.
Total dose bias dependency and ELDRS effects in bipolar linear devices
NASA Technical Reports Server (NTRS)
Yui, C. C.; McClure, S. S.; Rex, B. G.; Lehman, J. M.; Minto, T. D.; Wiedeman, M.
2002-01-01
Total dose tests of several bipolar linear devices show sensitivity to both dose rate and bias during exposure. All devices exhibited Enhanced Low Dose Rate Sensitivity (ELDRS). An accelerated ELDRS test method for three different devices demonstrate results similar to tests at low dose rate. Behavior and critical parameters from these tests are compared and discussed.
NASA Technical Reports Server (NTRS)
Callier, Frank M.; Desoer, Charles A.
1991-01-01
The aim of this book is to provide a systematic and rigorous access to the main topics of linear state-space system theory in both the continuous-time case and the discrete-time case; and the I/O description of linear systems. The main thrusts of the work are the analysis of system descriptions and derivations of their properties, LQ-optimal control, state feedback and state estimation, and MIMO unity-feedback systems.
NASA Technical Reports Server (NTRS)
Callier, Frank M.; Desoer, Charles A.
1991-01-01
The aim of this book is to provide a systematic and rigorous access to the main topics of linear state-space system theory in both the continuous-time case and the discrete-time case; and the I/O description of linear systems. The main thrusts of the work are the analysis of system descriptions and derivations of their properties, LQ-optimal control, state feedback and state estimation, and MIMO unity-feedback systems.
Kapczinski, F; Magalhães, P V S; Balanzá-Martinez, V; Dias, V V; Frangou, S; Gama, C S; Gonzalez-Pinto, A; Grande, I; Ha, K; Kauer-Sant'Anna, M; Kunz, M; Kupka, R; Leboyer, M; Lopez-Jaramillo, C; Post, R M; Rybakowski, J K; Scott, J; Strejilevitch, S; Tohen, M; Vazquez, G; Yatham, L; Vieta, E; Berk, M
2014-11-01
We discuss the rationale behind staging systems described specifically for bipolar disorders. Current applications, future directions and research gaps in clinical staging models for bipolar disorders are outlined. We reviewed the literature pertaining to bipolar disorders, focusing on the first episode onwards. We systematically searched data on staging models for bipolar disorders and allied studies that could inform the concept of staging. We report on several dimensions that are relevant to staging concepts in bipolar disorder. We consider whether staging offers a refinement to current diagnoses by reviewing clinical studies of treatment and functioning and the potential utility of neurocognitive, neuroimaging and peripheral biomarkers. Most studies to date indicate that globally defined late-stage patients have a worse overall prognosis and poorer response to standard treatment, consistent with patterns for end-stage medical disorders. We believe it is possible at this juncture to speak broadly of 'early'- and 'late'-stage bipolar disorder. Next steps require further collaborative efforts to consider the details of preillness onset and intermediary stages, and how many additional stages are optimal. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Comparison of Two Bipolar Systems in Laparoscopic Hysterectomy
Cho, Hye-Yon; Choi, Kong-Ju; Lee, Young-Lan; Chang, Kylie Hae-Jin; Kim, Hong-Bae
2012-01-01
Objective: To compare the efficacy of 2 bipolar systems during total laparoscopic hysterectomy (TLH): the pulsed bipolar system (PlasmaKinetic; Olympus, Japan) vs. conventional bipolar electrosurgery (Kleppinger bipolar forceps; Richard Wolf Instruments, Vernon Hills, IL). Methods: We retrospectively reviewed medical records of 80 women who underwent TLH for benign gynecologic disease between 2009 and 2010. Forty women received TLH using the conventional bipolar system and another 40 using the pulsed bipolar system. The clinical outcomes and complications were compared between the 2 groups. Results: No significant differences between the 2 groups were observed in terms of age, body mass index, and hospital stay. However, the blood loss was greater (515.3 ± 41.2mL vs. 467.9 ± 33.4mL, P < .05) and the operation time was longer (173.4 ± 33.4min vs. 157.3 ± 21.3min, P < .05) in the conventional group. Additionally, the uterine weight was lighter in the conventional group (218.5 ± 23.4g vs. 299.4 ± 41.1g, P < .05). None of the surgeries were required to be converted to laparotomy. No significant differences were found in intraoperative or postoperative complications between the groups. Conclusion: The pulsed bipolar system has some advantages over the conventional system, and therefore, may offer an alternative option for patients undergoing TLH. PMID:23318073
Radiation-induced 1/f noise degradation of bipolar linear voltage regulator
NASA Astrophysics Data System (ADS)
Qifeng, Zhao; Yiqi, Zhuang; Junlin, Bao; Wei, Hu
2016-03-01
Radiation-induced 1/f noise degradation in the LM117 bipolar linear voltage regulator is studied. Based on the radiation-induced degradation mechanism of the output voltage, it is suggested that the band-gap reference subcircuit is the critical component which leads to the 1/f noise degradation of the LM117. The radiation makes the base surface current of the bipolar junction transistors of the band-gap reference subcircuit increase, which leads to an increase in the output 1/f noise of the LM117. Compared to the output voltage, the 1/f noise parameter is more sensitive, it may be used to evaluate the radiation resistance capability of LM117. Project supported by the National Natural Science Foundation of China (Nos. 61076101, 61204092).
Ultrasonic linear measurement system
NASA Technical Reports Server (NTRS)
Marshall, Scot H. (Inventor)
1991-01-01
An ultrasonic linear measurement system uses the travel time of surface waves along the perimeter of a three-dimensional curvilinear body to determine the perimeter of the curvilinear body. The system can also be used piece-wise to measure distances along plane surfaces. The system can be used to measure perimeters where use of laser light, optical means or steel tape would be extremely difficult, time consuming or impossible. It can also be used to determine discontinuities in surfaces of known perimeter or dimension.
Composite Bipolar Plate for Unitized Fuel Cell/Electrolyzer Systems
NASA Technical Reports Server (NTRS)
Mittelsteadt, Cortney K.; Braff, William
2009-01-01
In a substantial improvement over present alkaline systems, an advanced hybrid bipolar plate for a unitized fuel cell/electrolyzer has been developed. This design, which operates on pure feed streams (H2/O2 and water, respectively) consists of a porous metallic foil filled with a polymer that has very high water transport properties. Combined with a second metallic plate, the pore-filled metallic plates form a bipolar plate with an empty cavity in the center.
20-μm deep trench isolation process characterization for linear bipolar ICs
NASA Astrophysics Data System (ADS)
Dyer, Terry; Doohan, Ian J.; Fallon, Martin; McAlpine, Dave; Aitkenhead, Adam; McGinty, Jim; Taylor, M.; Gravelle, Philip; Schouten, A.; Bryce, M.
2001-04-01
The use of junction isolation in linear bipolar ICs substantially consumes silicon area. The replacement of junction isolation with trench isolation has the potential to significantly reduce device area while maintaining high voltage operation. Deep trench isolation has been implemented on a conventional non- complementary 40V (NPN BVceo) linear IC process. A fully functional lower power operational amplifier has been fabricated as a technology driver. Device characterization shows that transistor leakage currents (Iceo) and leakage between trench tubs can be made comparable with junction isolated devices. The NPN buried layer can successfully be butted against the trench sidewall without device degradation, although this is currently not possible with the NPN base. An NPN device shrink of 3X has been achieved and further development is underway to increase this towards the 4X level, where the base diffusion front touches the trench sidewall.
Pease, R.L.; Gehlhausen, M.; Krieg, J.; Titus, J.; Turflinger, T.; Emily, D.; Cohn, L.
1998-12-01
Data are presented on several low dose rate sensitive bipolar linear circuits to evaluate a proposed hardness assurance method. The circuits include primarily operational amplifiers and voltage comparators with a variety of sensitive components and failure modes. The proposed method, presented in 1997, includes an option between a low dose rate test at 10 mrd(Si)/s and room temperature and a 100 C elevated temperature irradiation test at a moderate dose rate. The results of this evaluation demonstrate that a 10 mrd(Si)/s test is able (in all but one case) to bound the worst case response within a factor of 2. For the moderate dose rate, 100 C test the worst case response is within a factor of 3 for 8 of 11 circuits, and for some circuits overpredicts the low dose rate response. The irradiation bias used for these tests often represents a more degrading bias condition than would be encountered in a typical space system application.
Quasi-linear vacancy dynamics modeling and circuit analysis of the bipolar memristor.
Abraham, Isaac
2014-01-01
The quasi-linear transport equation is investigated for modeling the bipolar memory resistor. The solution accommodates vacancy and circuit level perspectives on memristance. For the first time in literature the component resistors that constitute the contemporary dual variable resistor circuit model are quantified using vacancy parameters and derived from a governing partial differential equation. The model describes known memristor dynamics even as it generates new insight about vacancy migration, bottlenecks to switching speed and elucidates subtle relationships between switching resistance range and device parameters. The model is shown to comply with Chua's generalized equations for the memristor. Independent experimental results are used throughout, to validate the insights obtained from the model. The paper concludes by implementing a memristor-capacitor filter and compares its performance to a reference resistor-capacitor filter to demonstrate that the model is usable for practical circuit analysis.
Quasi-Linear Vacancy Dynamics Modeling and Circuit Analysis of the Bipolar Memristor
Abraham, Isaac
2014-01-01
The quasi-linear transport equation is investigated for modeling the bipolar memory resistor. The solution accommodates vacancy and circuit level perspectives on memristance. For the first time in literature the component resistors that constitute the contemporary dual variable resistor circuit model are quantified using vacancy parameters and derived from a governing partial differential equation. The model describes known memristor dynamics even as it generates new insight about vacancy migration, bottlenecks to switching speed and elucidates subtle relationships between switching resistance range and device parameters. The model is shown to comply with Chua's generalized equations for the memristor. Independent experimental results are used throughout, to validate the insights obtained from the model. The paper concludes by implementing a memristor-capacitor filter and compares its performance to a reference resistor-capacitor filter to demonstrate that the model is usable for practical circuit analysis. PMID:25390634
Effect of component design in retrieved bipolar hip hemiarthroplasty systems.
Hess, Matthew D; Baker, Erin A; Salisbury, Meagan R; Kaplan, Lige M; Greene, Ryan T; Greene, Perry W
2013-09-01
Primary articulation of bipolar hemiarthroplasty systems is at the femoral head-liner interface. The purpose of this study was to compare observed damage modes on 36 retrieved bipolar systems with implant, demographic, intraoperative, and radiographic data to elucidate the effects of component design, specifically locking mechanism, on clinical performance. Retrieved bipolar hip hemiarthroplasty systems of 3 different design types were obtained, disassembled, and evaluated macro- and microscopically for varying modes of wear, including abrasion, burnishing, embedding, scratching, and pitting. Clinical record review and radiographic analysis were performed by a senior orthopedic surgery resident. Average bipolar hip hemiarthroplasty system term of service was 46 months (range, 0.27-187 months). All devices contained wear debris captured within the articulating space between the femoral head and liner. In 31% of patients without infection, lucency was observed on immediate prerevision radiographs. The system with a leaf locking mechanism showed significantly increased radiographically observed osteolysis (P=.03) compared with a system with a stopper ring locking mechanism. In addition, implant design and observed damage modes, including pitting and third-body particle embedding, were significantly associated with radiographically observed osteolysis.
Hadaeghi, Fatemeh; Hashemi Golpayegani, Mohammad Reza; Jafari, Sajad; Murray, Greg
2016-08-01
In the absence of a comprehensive neural model to explain the underlying mechanisms of disturbed circadian function in bipolar disorder, mathematical modeling is a helpful tool. Here, circadian activity as a response to exogenous daily cycles is proposed to be the product of interactions between neuronal networks in cortical (cognitive processing) and subcortical (pacemaker) areas of the brain. To investigate the dynamical aspects of the link between disturbed circadian activity rhythms and abnormalities of neurotransmitter functioning in frontal areas of the brain, we developed a novel mathematical model of a chaotic system which represents fluctuations in circadian activity in bipolar disorder as changes in the model's parameters. A novel map-based chaotic system was developed to capture disturbances in circadian activity across the two extreme mood states of bipolar disorder. The model uses chaos theory to characterize interplay between neurotransmitter functions and rhythm generation; it aims to illuminate key activity phenomenology in bipolar disorder, including prolonged sleep intervals, decreased total activity and attenuated amplitude of the diurnal activity rhythm. To test our new cortical-circadian mathematical model of bipolar disorder, we utilized previously collected locomotor activity data recorded from normal subjects and bipolar patients by wrist-worn actigraphs. All control parameters in the proposed model have an important role in replicating the different aspects of circadian activity rhythm generation in the brain. The model can successfully replicate deviations in sleep/wake time intervals corresponding to manic and depressive episodes of bipolar disorder, in which one of the excitatory or inhibitory pathways is abnormally dominant. Although neuroimaging research has strongly implicated a reciprocal interaction between cortical and subcortical regions as pathogenic in bipolar disorder, this is the first model to mathematically represent this
Linear Hereditary Control Systems,
Relationships between external and internal models for systems with time lags are discussed. The use of various canonical forms for the models in solving optimal control problems is considered. (Author)
2013-02-15
Universiti Teknikal Malaysia Melaka in Malaysia. The project was then used to partially support a new PhD student, Mr Shanon Vuglar (who is a former...method based on cascade realization of quantum systems is used and a conference and journal paper have been produced. In another approach, a method...based on singular perturbation is used and a conference and journal paper have resulted. This work was extended by the graduate student Shanon Vuglar to
Linearization of Nonlinear Systems.
1986-11-24
series. IEEE Trans. Circuits Syst., CAS-32(11):1150-1171, November 1985. [BC85b] S. Boyd and L. 0. Chua. Uniqueness of circuits and systems containing...Control and Information Sciences vol. 58, p10 1- 1 19 , June 1983. [BC85c] S. Boyd and L. 0. Chua. Volterra series for nonlinear circuits . In Proc. IEEE...ISCAS, Tokyo, June 1985. [BCD84] S. Boyd, L. 0. Chua, and C. A. Desoer . Analytical foundations of Volterra series. IMA Journal of Mathematical
Nickel-hydrogen bipolar battery system
NASA Technical Reports Server (NTRS)
Thaller, L. H.
1982-01-01
Rechargeable nickel-hydrogen systems are described that more closely resemble a fuel cell system than a traditional nickel-cadmium battery pack. This was stimulated by the currently emerging requirements related to large manned and unmanned low Earth orbit applications. The resultant nickel-hydrogen battery system should have a number of features that would lead to improved reliability, reduced costs as well as superior energy density and cycle lives as compared to battery systems constructed from the current state-of-the-art nickel-hydrogen individual pressure vessel cells.
Nickel-hydrogen bipolar battery systems
NASA Technical Reports Server (NTRS)
Thaller, L. H.
1982-01-01
Nickel-hydrogen cells are currently being manufactured on a semi-experimental basis. Rechargeable nickel-hydrogen systems are described that more closely resemble a fuel cell system than a traditional nickel-cadmium battery pack. This has been stimulated by the currently emerging requirements related to large manned and unmanned low earth orbit applications. The resultant nickel-hydrogen battery system should have a number of features that would lead to improved reliability, reduced costs as well as superior energy density and cycle lives as compared to battery systems constructed from the current state-of-the-art nickel-hydrogen individual pressure vessel cells.
Nickel-hydrogen bipolar battery system
Thaller, L.H.
1982-09-01
Rechargeable nickel-hydrogen systems are described that more closely resemble a fuel cell system than a traditional nickel-cadmium battery pack. This was stimulated by the currently emerging requirements related to large manned and unmanned low Earth orbit applications. The resultant nickel-hydrogen battery system should have a number of features that would lead to improved reliability, reduced costs as well as superior energy density and cycle lives as compared to battery systems constructed from the current state-of-the-art nickel-hydrogen individual pressure vessel cells.
Preconditioned quantum linear system algorithm.
Clader, B D; Jacobs, B C; Sprouse, C R
2013-06-21
We describe a quantum algorithm that generalizes the quantum linear system algorithm [Harrow et al., Phys. Rev. Lett. 103, 150502 (2009)] to arbitrary problem specifications. We develop a state preparation routine that can initialize generic states, show how simple ancilla measurements can be used to calculate many quantities of interest, and integrate a quantum-compatible preconditioner that greatly expands the number of problems that can achieve exponential speedup over classical linear systems solvers. To demonstrate the algorithm's applicability, we show how it can be used to compute the electromagnetic scattering cross section of an arbitrary target exponentially faster than the best classical algorithm.
On bipolar ejection. [of matter in astronomical systems
NASA Technical Reports Server (NTRS)
Cameron, A. G. W.
1985-01-01
Observations of bipolar outflows, including jets often with clumpy concentrations of matter, have been made for a wide variety of astronomical systems. In most but not all of the systems, an accretion disk is present. It is proposed that the general process responsible for bipolar ejection involves the conversion of rotational energy into magnetic energy, usually in the form of a polar magnetic torus, deep in the interiors of the systems involved. If the buoyancy of the torus resullts in draining the field lines of most of the matter which they thread, then the acceleration of the remaining matter in the toroidal bubble may produce velocities in excess of the escape velocity from the surface of the system. It is contemplated that this process will be repeated many times in most systems. A discussion is given of the application of these ideas to protostars, to stars evolved beyond the main sequence, to neutron stars, and to black holes on both stellar and galactic scales.
On bipolar ejection. [of matter in astronomical systems
NASA Technical Reports Server (NTRS)
Cameron, A. G. W.
1985-01-01
Observations of bipolar outflows, including jets often with clumpy concentrations of matter, have been made for a wide variety of astronomical systems. In most but not all of the systems, an accretion disk is present. It is proposed that the general process responsible for bipolar ejection involves the conversion of rotational energy into magnetic energy, usually in the form of a polar magnetic torus, deep in the interiors of the systems involved. If the buoyancy of the torus resullts in draining the field lines of most of the matter which they thread, then the acceleration of the remaining matter in the toroidal bubble may produce velocities in excess of the escape velocity from the surface of the system. It is contemplated that this process will be repeated many times in most systems. A discussion is given of the application of these ideas to protostars, to stars evolved beyond the main sequence, to neutron stars, and to black holes on both stellar and galactic scales.
1978-01-01
Variance 4-2 4.3 Principle Failure Mechanisms 4-7 4.4 Failure Rate Factor Development 4-9 4.5 Source Data Discussion 4-37 5 STORAGE FAILURE RATE...Temperature Factor Values for Bipolar Beam Lead and Bipolar ECL Digital Devices 6-4 6-2 Average Operating to Non-Operating Failure Rate Ratio & 6-14 vI...reliability 1i is the learning factor iI, is the quality factor 11 is the temperature factor 11 is the application environment factor C1 and C2 are the
Fovet, Thomas; Geoffroy, Pierre Alexis; Vaiva, Guillaume; Adins, Catherine; Thomas, Pierre; Amad, Ali
2015-04-01
Bipolar disorder is a severe and prevalent psychiatric disease. Poor outcomes include a high frequency of criminal acts, imprisonments, and repeat offenses. This critical review of the international literature examined several aspects of the complex relationship between individuals with bipolar disorder and the criminal justice system: risk factors for criminal acts, features of bipolar patients' incarceration, and their postrelease trajectories. Publications were obtained from the PubMed and Google Scholar electronic databases by using the following MeSH headings: prison, forensic psychiatry, criminal law, crime, and bipolar disorder. Among patients with bipolar disorder, the frequency of violent criminal acts is higher than in the general population (odds ratio [OR]=2.8, 95% confidence interval [CI]=1.8-4.3). The frequency is higher among patients with bipolar disorder and a comorbid substance use disorder than among those without either disorder (OR=10.1, CI=5.3-19.2). As a result, the prevalence of bipolar disorder among prisoners is high (2%-7%). In prison, patients' bipolar disorder symptoms can complicate their relationship with prison administrators, leading to an increased risk of multiple incarcerations. Moreover, the risk of suicide increases for these prisoners. Criminal acts are common among patients with bipolar disorder and are often associated with problems such as addiction. Thus it is important to improve the diagnosis and treatment of inmates with bipolar disorder.
Identification of multivariate linear systems
Griffith, J.M.
1981-01-01
This paper considers the problem of modeling multivariate linear systems where noisy output measurements are the only available data. The techniques presented are valid for a class of canonical forms. Results from several simulations demonstrate the capability for structure and parameter estimation.
Systems of Inhomogeneous Linear Equations
NASA Astrophysics Data System (ADS)
Scherer, Philipp O. J.
Many problems in physics and especially computational physics involve systems of linear equations which arise e.g. from linearization of a general nonlinear problem or from discretization of differential equations. If the dimension of the system is not too large standard methods like Gaussian elimination or QR decomposition are sufficient. Systems with a tridiagonal matrix are important for cubic spline interpolation and numerical second derivatives. They can be solved very efficiently with a specialized Gaussian elimination method. Practical applications often involve very large dimensions and require iterative methods. Convergence of Jacobi and Gauss-Seidel methods is slow and can be improved by relaxation or over-relaxation. An alternative for large systems is the method of conjugate gradients.
Masuda, Masaharu; Fujita, Masashi; Iida, Osamu; Okamoto, Shin; Ishihara, Takayuki; Nanto, Kiyonori; Kanda, Takashi; Sunaga, Akihiro; Tsujimura, Takuya; Matsuda, Yasuhiro; Mano, Toshiaki
2017-08-01
A bipolar voltage reflects a thick musculature where formation of a transmural lesion may be hard to achieve. The purpose of this study was to explore the association between local bipolar voltage and conduction gap in patients with persistent atrial fibrillation (AF) who underwent atrial roof or septal linear ablation. This prospective observational study included 42 and 36 consecutive patients with persistent AF who underwent roof or septal linear ablations, respectively. After pulmonary vein isolation, left atrial linear ablations were performed, and conduction gap sites were identified and ablated after first-touch radiofrequency application. Conduction gap(s) after the first-touch roof and septal linear ablation were observed in 13 (32%) and 19 patients (53%), respectively. Roof and septal area voltages were higher in patients with conduction gap(s) than in those without (roof, 1.23 ± 0.77 vs 0.73 ± 0.42 mV, p = 0.010; septal, 0.96 ± 0.43 vs 0.54 ± 0.18 mV, p = 0.001). Trisected regional analyses revealed that the voltage was higher at the region with a conduction gap than at the region without. Complete conduction block across the roof and septal lines was not achieved in 3 (7%) and 6 patients (17%), respectively. Patients in whom a linear conduction block could not be achieved demonstrated higher ablation area voltage than those with a successful conduction block (roof, 1.91 ± 0.74 vs 0.81 ± 0.51 mV, p = 0.001; septal, 1.15 ± 0.56 vs 0.69 ± 0.31 mV, p = 0.006). In conclusion, a high regional bipolar voltage predicts failure to achieve conduction block after left atrial roof or septal linear ablation. In addition, the conduction gap was located at the preserved voltage area. Copyright © 2017 Elsevier Inc. All rights reserved.
Total Dose Effects on Single Event Transients in Digital CMOS and Linear Bipolar Circuits
NASA Technical Reports Server (NTRS)
Buchner, S.; McMorrow, D.; Sibley, M.; Eaton, P.; Mavis, D.; Dusseau, L.; Roche, N. J-H.; Bernard, M.
2009-01-01
This presentation discusses the effects of ionizing radiation on single event transients (SETs) in circuits. The exposure of integrated circuits to ionizing radiation changes electrical parameters. The total ionizing dose effect is observed in both complementary metal-oxide-semiconductor (CMOS) and bipolar circuits. In bipolar circuits, transistors exhibit grain degradation, while in CMOS circuits, transistors exhibit threshold voltage shifts. Changes in electrical parameters can cause changes in single event upset(SEU)/SET rates. Depending on the effect, the rates may increase or decrease. Therefore, measures taken for SEU/SET mitigation might work at the beginning of a mission but not at the end following TID exposure. The effect of TID on SET rates should be considered if SETs cannot be tolerated.
Alloy, Lauren B.; Abramson, Lyn Y.; Urosevic, Snezana; Bender, Rachel E.; Wagner, Clara A.
2009-01-01
We review longitudinal predictors, primarily psychosocial, of the onset, course, and expression of bipolar spectrum disorders. We organize our review along a proximal – distal continuum, discussing the most proximal (i.e., prodromes) predictors of bipolar episodes first, then recent environmental (i.e., life events) predictors of bipolar symptoms and episodes next, followed by more distal psychological (i.e., cognitive styles) predictors, and ending with the most distal temperament (i.e., Behavioral Approach System sensitivity) predictors. We then present a theoretical model, the Behavioral Approach System (BAS) dysregulation model, for understanding and integrating the role of these predictors of bipolar spectrum disorders. Finally, we consider the implications of the reviewed longitudinal predictors for future research and psychosocial treatments of bipolar disorders. PMID:20161008
Nusslock, Robin; Abramson, Lyn Y.; Harmon-Jones, Eddie; Alloy, Lauren B.; Coan, James A.
2009-01-01
Research has emerged providing consistent support for the behavioral approach system (BAS) dysregulation theory of bipolar disorder. The objective of the current article is to examine the extent to which findings from the BAS dysregulation theory can inform psychosocial interventions for bipolar disorder. Towards this end, we first provide an overview of the BAS dysregulation theory. Second, we review extant research on psychosocial interventions for bipolar disorder. And, third, we discuss means by which research and theory in line with the BAS dysregulation model can inform psychosocial interventions for bipolar disorder. Particular attention is given to the clinical implications of research suggesting that bipolar disorder is characterized by high drive/incentive motivation, ambitious goal-setting, and perfectionism in the achievement domain. PMID:20161456
Urošević, Snez̆ana; Abramson, Lyn Y.; Harmon-Jones, Eddie; Alloy, Lauren B.
2008-01-01
In recent years, a call for increased research on bipolar disorder has been answered with methodologically diverse studies exploring goal striving, life events, cognitive style, decision-making, and neurobiological abnormalities in bipolar disorder. In order to further this spurt of research and to systematize our understanding of bipolar disorder, an integrative perspective is warranted. The behavioral approach system (BAS) dysregulation theory, proposed by Richard Depue and colleagues, provides such an integrated model for understanding psychosocial and biological aspects of bipolar disorder. In this paper, we review studies on life events, cognitive style and other psychosocial and neurobiological factors to examine whether the BAS dysregulation theory is supported by existing data. Then, we draw on recent advances in the study of emotion and motivation, and propose an expansion of the BAS dysregulation model of bipolar spectrum disorders to foster further biopsychosocial investigations of bipolar disorder. This expanded model provides greater specificity in predictions, especially about the nature of BAS dysregulation, environmental factors and psychological processes (e.g., appraisal processes) featured in a causal chain culminating in bipolar symptoms. Finally, we discuss the implications of the expanded BAS model for the course of bipolar spectrum disorders. PMID:18565633
Conditions for Stabilizability of Linear Switched Systems
NASA Astrophysics Data System (ADS)
Minh, Vu Trieu
2011-06-01
This paper investigates some conditions that can provide stabilizability for linear switched systems with polytopic uncertainties via their closed loop linear quadratic state feedback regulator. The closed loop switched systems can stabilize unstable open loop systems or stable open loop systems but in which there is no solution for a common Lyapunov matrix. For continuous time switched linear systems, we show that if there exists solution in an associated Riccati equation for the closed loop systems sharing one common Lyapunov matrix, the switched linear systems are stable. For the discrete time switched systems, we derive a Linear Matrix Inequality (LMI) to calculate a common Lyapunov matrix and solution for the stable closed loop feedback systems. These closed loop linear quadratic state feedback regulators guarantee the global asymptotical stability for any switched linear systems with any switching signal sequence.
Linear control design for guaranteed stability of uncertain linear systems
NASA Technical Reports Server (NTRS)
Yedavalli, R. K.
1986-01-01
In this paper, a linear control design algorithm based on the elemental perturbation bounds developed recently is presented for a simple second order linear uncertain system satisfying matching conditions. The proposed method is compared with Guaranteed Cost Control (GCC), Multistep Guaranteed Cost Control (MGCC) and the Matching Condition (MC) methods and is shown to give guaranteed stability with lesser values for the control gains than some of the existing methods for the example considered.
Bipolar incompatibility system of an ectomycorrhizal basidiomycete, Rhizopogon rubescens.
Kawai, Masataka; Yamahara, Mina; Ohta, Akira
2008-04-01
The mating systems of most ectomycorrhizal fungi have not been elucidated because of two reasons. One is the difficulty of obtaining homokaryotic isolates for mating tests caused by the low germination rate of basidiospores, and another is the difficulty of checking dikaryotization caused by the absence or inconsistent production of clamp connections on heterokaryotic mycelia under laboratory conditions. Basidiospore germination of a few ectomycorrhizal fungi has been induced by living roots of their host plants. Based on this information, we examined methods to obtain homokaryotic isolates of Rhizopogon rubescens using its host plant, Pinus thunbergii. The basidiospores of R. rubescens appeared to germinate well on an agar plate, on which axenic pine seedlings were grown in advance to induce germination, even when the seedlings were removed from the plate at the time of spore inoculation. To enhance the production rate of clamp connections on the heterokaryotic mycelia of R. rubescens, the culture medium composition was modified. The pH of the medium was critical for the production of clamp connections, and the optimal pH was higher for the production of clamp connections than for mycelial growth. These findings made it possible to conduct mating tests, and we found that the mating system of R. rubescens is bipolar with a multiallelic mating type factor.
Common and Dissociable Dysfunction of the Reward System in Bipolar and Unipolar Depression
Satterthwaite, Theodore D; Kable, Joseph W; Vandekar, Lillie; Katchmar, Natalie; Bassett, Danielle S; Baldassano, Claudia F; Ruparel, Kosha; Elliott, Mark A; Sheline, Yvette I; Gur, Ruben C; Gur, Raquel E; Davatzikos, Christos; Leibenluft, Ellen; Thase, Michael E; Wolf, Daniel H
2015-01-01
Unipolar and bipolar depressive episodes have a similar clinical presentation that suggests common dysfunction of the brain's reward system. Here, we evaluated the relationship of both dimensional depression severity and diagnostic category to reward system function in both bipolar and unipolar depression. In total, 89 adults were included, including 27 with bipolar depression, 25 with unipolar depression, and 37 healthy comparison subjects. Subjects completed both a monetary reward task and a resting-state acquisition during 3T BOLD fMRI. Across disorders, depression severity was significantly associated with reduced activation for wins compared with losses in bilateral ventral striatum, anterior cingulate cortex, posterior cingulate cortex, and right anterior insula. Resting-state connectivity within this reward network was also diminished in proportion to depression severity, most notably connectivity strength in the left ventral striatum. In addition, there were categorical differences between patient groups: resting-state connectivity at multiple reward network nodes was higher in bipolar than in unipolar depression. Reduced reward system task activation and resting-state connectivity therefore appear to be a brain phenotype that is dimensionally related to depression severity in both bipolar and unipolar depression. In contrast, categorical differences in reward system resting connectivity between unipolar and bipolar depression may reflect differential risk of mania. Reward system dysfunction thus represents a common brain mechanism with relevance that spans categories of psychiatric diagnosis. PMID:25767910
Common and Dissociable Dysfunction of the Reward System in Bipolar and Unipolar Depression.
Satterthwaite, Theodore D; Kable, Joseph W; Vandekar, Lillie; Katchmar, Natalie; Bassett, Danielle S; Baldassano, Claudia F; Ruparel, Kosha; Elliott, Mark A; Sheline, Yvette I; Gur, Ruben C; Gur, Raquel E; Davatzikos, Christos; Leibenluft, Ellen; Thase, Michael E; Wolf, Daniel H
2015-08-01
Unipolar and bipolar depressive episodes have a similar clinical presentation that suggests common dysfunction of the brain's reward system. Here, we evaluated the relationship of both dimensional depression severity and diagnostic category to reward system function in both bipolar and unipolar depression. In total, 89 adults were included, including 27 with bipolar depression, 25 with unipolar depression, and 37 healthy comparison subjects. Subjects completed both a monetary reward task and a resting-state acquisition during 3T BOLD fMRI. Across disorders, depression severity was significantly associated with reduced activation for wins compared with losses in bilateral ventral striatum, anterior cingulate cortex, posterior cingulate cortex, and right anterior insula. Resting-state connectivity within this reward network was also diminished in proportion to depression severity, most notably connectivity strength in the left ventral striatum. In addition, there were categorical differences between patient groups: resting-state connectivity at multiple reward network nodes was higher in bipolar than in unipolar depression. Reduced reward system task activation and resting-state connectivity therefore appear to be a brain phenotype that is dimensionally related to depression severity in both bipolar and unipolar depression. In contrast, categorical differences in reward system resting connectivity between unipolar and bipolar depression may reflect differential risk of mania. Reward system dysfunction thus represents a common brain mechanism with relevance that spans categories of psychiatric diagnosis.
Prochaska, Krystyna; Staszak, Katarzyna; Woźniak-Budych, Marta Joanna; Regel-Rosocka, Magdalena; Adamczak, Michalina; Wiśniewski, Maciej; Staniewski, Jacek
2014-09-01
A novel approach based on a hybrid system allowing nanofiltration, bipolar electrodialysis and reactive extraction, was proposed to remove fumaric acid from fermentation broth left after bioconversion of glycerol. The fumaric salts can be concentrated in the nanofiltration process to a high yield (80-95% depending on pressure), fumaric acid can be selectively separated from other fermentation components, as well as sodium fumarate can be conversed into the acid form in bipolar electrodialysis process (stack consists of bipolar and anion-exchange membranes). Reactive extraction with quaternary ammonium chloride (Aliquat 336) or alkylphosphine oxides (Cyanex 923) solutions (yield between 60% and 98%) was applied as the final step for fumaric acid recovery from aqueous streams after the membrane techniques. The hybrid system permitting nanofiltration, bipolar electrodialysis and reactive extraction was found effective for recovery of fumaric acid from the fermentation broth.
Can bipolar disorder be viewed as a multi-system inflammatory disease?
Leboyer, Marion; Soreca, Isabella; Scott, Jan; Frye, Mark; Henry, Chantal; Tamouza, Ryad; Kupfer, David J.
2012-01-01
Background Patients with bipolar disorder are known to be at high risk of premature death. Comorbid cardio-vascular diseases are a leading cause of excess mortality, well above the risk associated with suicide. In this review, we explore comorbid medical disorders, highlighting evidence that bipolar disorder can be effectively conceptualized as a multi-systemic inflammatory disease. Methods We conducted a systematic PubMed search of all English-language articles recently published with bipolar disorder cross-referenced with the following terms: mortality and morbidity, cardio-vascular, diabetes, obesity, metabolic syndrome, inflammation, auto-antibody, retro-virus, stress, sleep and circadian rhythm. Results Evidence gathered so far suggests that the multi-system involvement is present from the early stages, and therefore requires proactive screening and diagnostic procedures, as well as comprehensive treatment to reduce progression and premature mortality. Exploring the biological pathways that could account for the observed link show that dysregulated inflammatory background could be a common factor underlying cardio-vascular and bipolar disorders. Viewing bipolar disorder as a multi-system disorder should help us to re-conceptualize disorders of the mind as “disorders of the brain and the body”. Limitations The current literature substantially lacks longitudinal and mechanistic studies, as well as comparison studies to explore the magnitude of the medical burden in bipolar disorder compared to major mood disorders as well as psychotic disorders. It is also necessary to look for subgroups of bipolar disorder based on their rates of comorbid disorders. Conclusions Comorbid medical illnesses in bipolar disorder might be viewed not only as the consequence of health behaviors and of psychotropic medications, but rather as an early manifestation of a multi-systemic disorder. Medical monitoring is thus a critical component of case assessment. Exploring common
Linear quadratic optimal control for symmetric systems
NASA Technical Reports Server (NTRS)
Lewis, J. H.; Martin, C. F.
1983-01-01
Special symmetries are present in many control problems. This paper addresses the problem of determining linear-quadratic optimal control problems whose solutions preserve the symmetry of the initial linear control system.
Parametric Identification of Systems Via Linear Operators.
1978-09-01
A general parametric identification /approximation model is developed for the black box identification of linear time invariant systems in terms of... parametric identification techniques derive from the general model as special cases associated with a particular linear operator. Some possible
Characterization of Radiation Hardened Bipolar Linear Devices for High Total Dose Missions
NASA Technical Reports Server (NTRS)
McClure, Steven S.; Harris, Richard D.; Rax, Bernard G.; Thorbourn, Dennis O.
2012-01-01
Radiation hardened linear devices are characterized for performance in combined total dose and displacement damage environments for a mission scenario with a high radiation level. Performance at low and high dose rate for both biased and unbiased conditions is compared and the impact to hardness assurance methodology is discussed.
Characterization of Radiation Hardened Bipolar Linear Devices for High Total Dose Missions
NASA Technical Reports Server (NTRS)
McClure, Steven S.; Harris, Richard D.; Rax, Bernard G.; Thorbourn, Dennis O.
2012-01-01
Radiation hardened linear devices are characterized for performance in combined total dose and displacement damage environments for a mission scenario with a high radiation level. Performance at low and high dose rate for both biased and unbiased conditions is compared and the impact to hardness assurance methodology is discussed.
Stock, Matt S; Beck, Travis W; Defreitas, Jason M; Dillon, Michael A
2010-12-15
The purpose of this study was to examine the linearity and reliability of the electromyographic (EMG) amplitude versus dynamic constant external resistance (DCER) relationships for monopolar and bipolar recording techniques during concentric and eccentric muscle actions. Nineteen healthy men (mean ± SD age = 22.9 ± 2.5 years) performed a series of randomly ordered, submaximal to maximal, unilateral DCER muscle actions of the dominant forearm flexors on two occasions separated by at least 48 h. Specifically, the subjects lifted and lowered weights corresponding to 10-100% of the one repetition maximum (1-RM) in 10% increments. During each muscle action, monopolar and bipolar surface EMG signals were detected simultaneously from the biceps brachii. For the monopolar and bipolar methods, the coefficients of determination for the EMG amplitude versus DCER relationships ranged from 0.64-0.98 and 0.38-0.98 for the concentric muscle actions and 0.45-0.98 and 0.45-0.98 for the eccentric muscle actions, respectively. The intraclass correlation coefficients (ICC) and corresponding standard errors of measurement (SEM) for the linear slope coefficients for the EMG amplitude versus DCER relationships were 0.682 (18.4%) and 0.594 (21.8%) with the monopolar method and 0.810 (25.6%) and 0.774 (17.6%) with the bipolar method for the concentric and eccentric muscle actions, respectively. These findings indicated that monopolar and bipolar recording techniques may be used with a similar degree of linearity and reliability for the EMG amplitude versus concentric and eccentric DCER relationships. Copyright © 2010 Elsevier B.V. All rights reserved.
Linear systems, and ARMA- and Fliess models
NASA Astrophysics Data System (ADS)
Lomadze, Vakhtang; Khurram Zafar, M.
2010-10-01
Linear (dynamical) systems are central objects of study (in linear system theory), and ARMA- and Fliess models are two very important classes of models that are used to represent them. This article is concerned with the question of what is a relation between them (in case of higher dimensions). It is shown that the category of linear systems, the 'weak' category of ARMA-models and the category of Fliess models are equivalent to each other.
Thermal properties of contemporary bipolar systems using infrared imaging.
Keshavarzi, Sassan; Bolour, Armon; Yarbrough, Chester; Mendez, Karen; Behrouzi, Behzad; Kasasbeh, Aimen S; Levy, Michael L
2015-03-01
Bipolar coagulation has enhanced the capabilities and safety profile of contemporary neurosurgery and has become indispensable in the neurosurgical armamentarium. Nevertheless, significant heat transfer issues remain to be resolved before it can achieve the status of minimal risk. The Codman irrigating forceps, Codman ISOCOOL forceps, and Ellman bipolar forceps, powered by either Synergy or Ellman generators set at various power levels, were compared to investigate the combinations that would allow for the lowest rate of heat transfer. Using an infrared camera and ThermaGRAM imaging software, the temperature was calculated and used to estimate the degree of heat transfer. Codman ISOCOOL forceps powered the Ellman Surgitron generator showed the greatest dissipation (at mid-power, the luminance decreased from 250 units to 80 units within 60 seconds) and the least production of heat after activation. Codman ISOCOOL forceps powered by the Codman SYNERGY MALIS generator showed less heat dissipation (at mid-power, the luminance decreased from 250 units to 195 units within 60 seconds) than the Ellman forceps and Ellman Surgitron generator combination (at mid-power, the luminance decreased from 250 units to 125 units within 60 seconds). These data suggest that the incorporation of the Ellman Surgitron Generator can result in the reduction of thermal transfer with conventional bipolar forceps compared with other generators. The combination with Codman ISOCOOL forceps can maximize the potential safety associated with bipolar coagulation. With regard to the use of comarketed pairs of forceps and generators, the combination of Ellman Surgitron Generator and Ellman bipolar forceps provided the best thermal profile. Copyright © 2015 Elsevier Inc. All rights reserved.
Stabilization of nonlinear systems using linear observers
NASA Technical Reports Server (NTRS)
Strane, R. E.; Vogt, W. G.
1974-01-01
It is shown that a linear observer can always be employed to stabilize a nonlinear system which contains a true Popov type nonlinearity in the closed interval from 0 to k, where k is finite, provided the nonlinear function and a completely observable output of the linear portion are available as inputs to the observer. Taking into consideration the case in which a completely observable output is not available from the linear portion, stabilization is shown to be possible if the original linear approximation of the system is asymptotically stable.
James, Timothy Y; Sun, Sheng; Li, Wenjun; Heitman, Joseph; Kuo, Hsiao-Che; Lee, Yong-Hwan; Asiegbu, Frederick O; Olson, Ake
2013-01-01
The process of mating in Basidiomycota is regulated by homeodomain-encoding genes (HD) and pheromones and G protein-coupled pheromone receptor genes (P/R). Whether these genes are actually involved in determining mating type distinguishes mating systems that are considered tetrapolar (two locus) from bipolar (one locus). Polyporales are a diverse group of wood-decay basidiomycetes displaying high variability in mating and decay systems. Many of the bipolar species appear to be brown-rot fungi, and it has been hypothesized that there is a functional basis for this correlation. Here we characterize mating genes in recently sequenced Polyporales and other Agaricomycete genomes. All Agaricomycete genomes encode HD and pheromone receptor genes regardless of whether they are bipolar or tetrapolar. The HD genes are organized into a MAT-HD locus with a high degree of gene order conservation among neighboring genes, with the gene encoding mitochondrial intermediate peptidase consistently syntenic but no linkage to the P/R genes. To have a complete dataset of species with known mating systems we determined that Wolfiporia cocos appears to be bipolar, using the criterion that DNA polymorphism of MAT genes should be extreme. Testing the correlation of mating and decay systems while controlling for phylogenetic relatedness failed to identify a statistical association, likely due to the small number of taxa employed. Using a phylogenetic analysis of Ste3 proteins, we identified clades of sequences that contain no known mating type-specific receptors and therefore might have evolved novel functions. The data are consistent with multiple origins of bipolarity within the Agaricomycetes and Polyporales, although the alternative hypothesis that tetrapolarity and bipolarity are reversible states needs better testing.
Systems of Linear Equations on a Spreadsheet.
ERIC Educational Resources Information Center
Bosch, William W.; Strickland, Jeff
1998-01-01
The Optimizer in Quattro Pro and the Solver in Excel software programs make solving linear and nonlinear optimization problems feasible for business mathematics students. Proposes ways in which the Optimizer or Solver can be coaxed into solving systems of linear equations. (ASK)
Isolators Including Main Spring Linear Guide Systems
NASA Technical Reports Server (NTRS)
Goold, Ryan (Inventor); Buchele, Paul (Inventor); Hindle, Timothy (Inventor); Ruebsamen, Dale Thomas (Inventor)
2017-01-01
Embodiments of isolators, such as three parameter isolators, including a main spring linear guide system are provided. In one embodiment, the isolator includes first and second opposing end portions, a main spring mechanically coupled between the first and second end portions, and a linear guide system extending from the first end portion, across the main spring, and toward the second end portion. The linear guide system expands and contracts in conjunction with deflection of the main spring along the working axis, while restricting displacement and rotation of the main spring along first and second axes orthogonal to the working axis.
Opinion Dynamics and Decision of Vote in Bipolar Political Systems
NASA Astrophysics Data System (ADS)
Caruso, Filippo; Castorina, Paolo
A model of the opinion dynamics underlying the political decision is proposed. The analysis is restricted to a bipolar scheme with a possible third political area. The interaction among voters is local but the final decision strongly depends on global effects such as the rating of the governments. As in the realistic case, the individual decision making process is determined by the most relevant personal interests and problems. The phenomenological analysis of the national vote in Italy and Germany has been carried out and a prediction of the next Italian vote as a function of the government rating is presented.
Stochastic stability properties of jump linear systems
NASA Technical Reports Server (NTRS)
Feng, Xiangbo; Loparo, Kenneth A.; Ji, Yuandong; Chizeck, Howard J.
1992-01-01
Jump linear systems are defined as a family of linear systems with randomly jumping parameters (usually governed by a Markov jump process) and are used to model systems subject to failures or changes in structure. The authors study stochastic stability properties in jump linear systems and the relationship among various moment and sample path stability properties. It is shown that all second moment stability properties are equivalent and are sufficient for almost sure sample path stability, and a testable necessary and sufficient condition for second moment stability is derived. The Lyapunov exponent method for the study of almost sure sample stability is discussed, and a theorem which characterizes the Lyapunov exponents of jump linear systems is presented.
Technology-Based Early Warning Systems for Bipolar Disorder: A Conceptual Framework
Torous, John; Thompson, Wesley
2016-01-01
Recognition and timely action around “warning signs” of illness exacerbation is central to the self-management of bipolar disorder. Due to its heterogeneity and fluctuating course, passive and active mobile technologies have been increasingly evaluated as adjunctive or standalone tools to predict and prevent risk of worsening of course in bipolar disorder. As predictive analytics approaches to big data from mobile health (mHealth) applications and ancillary sensors advance, it is likely that early warning systems will increasingly become available to patients. Such systems could reduce the amount of time spent experiencing symptoms and diminish the immense disability experienced by people with bipolar disorder. However, in addition to the challenges in validating such systems, we argue that early warning systems may not be without harms. Probabilistic warnings may be delivered to individuals who may not be able to interpret the warning, have limited information about what behaviors to change, or are unprepared to or cannot feasibly act due to time or logistic constraints. We propose five essential elements for early warning systems and provide a conceptual framework for designing, incorporating stakeholder input, and validating early warning systems for bipolar disorder with a focus on pragmatic considerations. PMID:27604265
Technology-Based Early Warning Systems for Bipolar Disorder: A Conceptual Framework.
Depp, Colin; Torous, John; Thompson, Wesley
2016-09-07
Recognition and timely action around "warning signs" of illness exacerbation is central to the self-management of bipolar disorder. Due to its heterogeneity and fluctuating course, passive and active mobile technologies have been increasingly evaluated as adjunctive or standalone tools to predict and prevent risk of worsening of course in bipolar disorder. As predictive analytics approaches to big data from mobile health (mHealth) applications and ancillary sensors advance, it is likely that early warning systems will increasingly become available to patients. Such systems could reduce the amount of time spent experiencing symptoms and diminish the immense disability experienced by people with bipolar disorder. However, in addition to the challenges in validating such systems, we argue that early warning systems may not be without harms. Probabilistic warnings may be delivered to individuals who may not be able to interpret the warning, have limited information about what behaviors to change, or are unprepared to or cannot feasibly act due to time or logistic constraints. We propose five essential elements for early warning systems and provide a conceptual framework for designing, incorporating stakeholder input, and validating early warning systems for bipolar disorder with a focus on pragmatic considerations.
Estimability And Regulability Of Linear Systems
NASA Technical Reports Server (NTRS)
Baram, Yoram; Kailath, Thomas
1990-01-01
Report presents two new properties of systems characterized by linear state space models (e.g., dynamical systems and associated control systems): estimability and regulability. Provides criteria for reductions of errors and cost functions in control systems. Useful in design of optimal controllers and estimators.
Simulation of linear mechanical systems
NASA Technical Reports Server (NTRS)
Sirlin, S. W.
1993-01-01
A dynamics and controls analyst is typically presented with a structural dynamics model and must perform various input/output tests and design control laws. The required time/frequency simulations need to be done many times as models change and control designs evolve. This paper examines some simple ways that open and closed loop frequency and time domain simulations can be done using the special structure of the system equations usually available. Routines were developed to run under Pro-Matlab in a mixture of the Pro-Matlab interpreter and FORTRAN (using the .mex facility). These routines are often orders of magnitude faster than trying the typical 'brute force' approach of using built-in Pro-Matlab routines such as bode. This makes the analyst's job easier since not only does an individual run take less time, but much larger models can be attacked, often allowing the whole model reduction step to be eliminated.
Design And Analysis Of Linear Control Systems
NASA Technical Reports Server (NTRS)
Jamison, John W.
1991-01-01
Package of five computer programs developed to assist in design and analysis of linear control systems by use of root-locus and frequency-response methods. Package written in FORTRAN (BODE, TPEAK) and BASIC (LOCUS, KTUNE, and POLYROOT).
Final focus systems for linear colliders
Erickson, R.A.
1987-11-01
The final focus system of a linear collider must perform two primary functions, it must focus the two opposing beams so that their transverse dimensions at the interaction point are small enough to yield acceptable luminosity, and it must steer the beams together to maintain collisions. In addition, the final focus system must transport the outgoing beams to a location where they can be recycled or safely dumped. Elementary optical considerations for linear collider final focus systems are discussed, followed by chromatic aberrations. The design of the final focus system of the SLAC Linear Collider (SLC) is described. Tuning and diagnostics and steering to collision are discussed. Most of the examples illustrating the concepts covered are drawn from the SLC, but the principles and conclusions are said to be generally applicable to other linear collider designs as well. 26 refs., 17 figs. (LEW)
Design And Analysis Of Linear Control Systems
NASA Technical Reports Server (NTRS)
Jamison, John W.
1991-01-01
Package of five computer programs developed to assist in design and analysis of linear control systems by use of root-locus and frequency-response methods. Package written in FORTRAN (BODE, TPEAK) and BASIC (LOCUS, KTUNE, and POLYROOT).
Santini, Mario; Fiorelli, Alfonso; Milione, Roberta; Vicidomini, Giovanni; Accardo, Marina
2014-10-01
Surgery is the treatment of choice for management of pulmonary hydatid cysts. Total pericystectomy provided the best results concerning the recurrence of the disease, but haemorrhagia and air leak during dissection of the pericystic space are the main disadvantages of such a method. To avoid these complications, we proposed the use of an electrothermal bipolar tissue sealing system. After the extraction of the hydatid cyst, a small space is created between the pericyst and normal lung, and the separation between the two zones is joined using the electrothermal bipolar tissue sealing system. This procedure reduces the risk of bleeding and of air leaks because the bronchi and the vessels encountered during dissection are sealed by the electrothermal bipolar tissue sealing system. When the pericystic membrane (inflammatory host reaction) is intimately adherent to the lung, total pericystectomy demands greater technical training because the bronchovascular axes of the healthy segments are situated in the pericyst. In such cases, the electrothermal bipolar tissue sealing system allowed creation of an appropriate plane through the parenchyma close to the pericyst, minimizing the normal lung exposed to resection as much as possible and reducing the resulting bleeding and air leak. This procedure was successfully applied in 4 consecutive patients each with a giant hydatid cyst.
Utilization of a bipolar lead acid battery for the advanced launch system
NASA Technical Reports Server (NTRS)
Gentry, William O.; Vidas, Robin; Miles, Ronald; Eckles, Steven
1991-01-01
The development of a battery comprised of bipolar lead acid modules is discussed. The battery is designed to satisfy the requirements of the Advanced Launch System (ALS). The battery will have the following design features: (1) conventional lead acid chemistry; (2) thin electrode/active materials; (3) a thin separator; (4) sealed construction (gas recombinant); and (5) welded plastic frames for the external seal.
Recursive inversion of externally defined linear systems
NASA Technical Reports Server (NTRS)
Bach, Ralph E., Jr.; Baram, Yoram
1988-01-01
The approximate inversion of an internally unknown linear system, given by its impulse response sequence, by an inverse system having a finite impulse response, is considered. The recursive least squares procedure is shown to have an exact initialization, based on the triangular Toeplitz structure of the matrix involved. The proposed approach also suggests solutions to the problems of system identification and compensation.
Digital simulation of stiff linear dynamic systems.
NASA Technical Reports Server (NTRS)
Holland, L. D.; Walsh, J. R., Jr.; Kerr, J. H.
1972-01-01
A method is derived for digital computer simulation of linear time-invariant systems when the insignificant eigenvalues involved in such systems are eliminated by an ALSAP root removal technique. The method is applied to a thirteenth-order dynamic system representing a passive RLC network.
A program for identification of linear systems
NASA Technical Reports Server (NTRS)
Buell, J.; Kalaba, R.; Ruspini, E.; Yakush, A.
1971-01-01
A program has been written for the identification of parameters in certain linear systems. These systems appear in biomedical problems, particularly in compartmental models of pharmacokinetics. The method presented here assumes that some of the state variables are regularly modified by jump conditions. This simulates administration of drugs following some prescribed drug regime. Parameters are identified by a least-square fit of the linear differential system to a set of experimental observations. The method is especially suited when the interval of observation of the system is very long.
Buttram, M.T.; Ginn, J.W.
1988-06-21
A linear induction accelerator includes a plurality of adder cavities arranged in a series and provided in a structure which is evacuated so that a vacuum inductance is provided between each adder cavity and the structure. An energy storage system for the adder cavities includes a pulsed current source and a respective plurality of bipolar converting networks connected thereto. The bipolar high-voltage, high-repetition-rate square pulse train sets and resets the cavities. 4 figs.
Reduced antioxidant defense systems in schizophrenia and bipolar I disorder.
Raffa, Monia; Barhoumi, Sana; Atig, Fatma; Fendri, Chiraz; Kerkeni, Abdelhamid; Mechri, Anwar
2012-12-03
Numerous evidence and proofs suggest that the oxidative stress contributes to the pathogenesis of schizophrenia (SZ) and bipolar disorder (BD). The aim of this study is to determine the glutathione levels and the antioxidant enzyme activities in blood samples of patients suffering from SZ and patients with bipolar disorder in comparison with the healthy controlled subjects. It was a case-controlled study carried on upon three groups: forty-six SZ patients (41 men and 5 women, mean age=33.2±7years), thirty BD patients (25 men and 5 women, mean age=31.3±8years) and forty healthy controls (33 men and 7 women, mean age=32.3±7years). The glutathione levels are the total glutathione (GSHt), the reduced glutathione (GSHr), and the oxidized glutathione (GSSG) and the antioxidant enzyme activities that are the superoxide dismutase (SOD), the glutathione peroxidase (GPx), and the catalase (CAT) are determined by the spectrophotometer. We noticed that the GSHt and the GSHr levels significantly decreased in both SZ and BD patients in comparison with the healthy control subjects. As for SOD and CAT activities they remained lower for the patients with SZ when compared both with the controls or the BD patients. We noticed as well that the CAT activity was significantly lower in the BD group than that in the control group, whereas, GPx activity showed no significant change in each group. Hence, this report of the decreased plasma levels of GSHt and GSHr, and the impaired antioxidant enzyme activities in SZ and BD patients aims at highlighting the GSH deficit that seems to be contributing to these disorders, and showing that it may be an important indirect biomarker of the oxidative stress for the SZ and BD.
Aircraft engine mathematical model - linear system approach
NASA Astrophysics Data System (ADS)
Rotaru, Constantin; Roateşi, Simona; Cîrciu, Ionicǎ
2016-06-01
This paper examines a simplified mathematical model of the aircraft engine, based on the theory of linear and nonlinear systems. The dynamics of the engine was represented by a linear, time variant model, near a nominal operating point within a finite time interval. The linearized equations were expressed in a matrix form, suitable for the incorporation in the MAPLE program solver. The behavior of the engine was included in terms of variation of the rotational speed following a deflection of the throttle. The engine inlet parameters can cover a wide range of altitude and Mach numbers.
Coprime factorizations in stable linear systems
NASA Technical Reports Server (NTRS)
Desoer, Charles A.; Gundes, A. Nazli; Kabuli, M. Guntekin
1988-01-01
A block-diagonal linear (not necessarily time-invariant) map P with a right-coprime factorization ND-1 (or a left-coprime factorization D-1N) is considered. It is shown that the individual blocks in P have right-coprime factorizations (left-coprime factorizations, respectively) if and only if the denominator map D has a special block-triangular structure. This condition is applied to the stable linear feedback system S(P1,P2).
Estimability and regulability of linear systems
NASA Technical Reports Server (NTRS)
Baram, Yoram; Kailath, Thomas
1987-01-01
A linear state-space system will be said to be estimable if in estimating its state from its output the posterior error covariance matrix is strictly smaller than the prior covariance matrix. It will be said to be regulable if the quadratic cost of state feedback control is strictly smaller than the cost when no feedback is used. These properties, which are shown to be dual, are different from the well known observability and controllability properties of linear systems. Necessary and sufficient conditions for estimability and regulability are derived for time variant and time invariant systems, in discrete and continuous time.
Estimability and regulability of linear systems
NASA Technical Reports Server (NTRS)
Baram, Yoram; Kailath, Thomas
1987-01-01
A linear state-space system will be said to be estimable if in estimating its state from its output the posterior error covariance matrix is strictly smaller than the prior covariance matrix. It will be said to be regulable if the quadratic cost of state feedback control is strictly smaller than the cost when no feedback is used. These properties, which are are shown to be dual, are different from the well known observability and controllability properties of linear systems. Necessary and sufficient conditions for estimability and regulability are derived for time variant and time invariant systems, in discrete and continuous time.
Finite solutions of fully fuzzy linear system
NASA Astrophysics Data System (ADS)
Malkawi, Ghassan; Ahmad, Nazihah; Ibrahim, Haslinda
2014-12-01
The solution of Fully Fuzzy Linear System (FFLS) is normally categorized as unique, finite and infinitely many solutions. However, in the case of more than one solution, the finite or alternative solution is not detected when linear programming is considered. Therefore this paper aims to provide a method of using min-max system and absolute system to append new concept for the consistency of FFLS, which is called finite solution of FFLS, where the FFLS have more than two solutions, and not only an infinite solution.
System interaction with linear and nonlinear characteristics
Lin, C.W. ); Tseng, W.S. )
1991-01-01
This book is covered under some of the following topics: seismic margins in piping systems, vibrational power flow in a cylindrical shell, inelastic pipework dynamics and aseismic design, an efficient method for dynamic analysis of a linearly elastic piping system with nonlinear supports.
The linear regulator problem for parabolic systems
NASA Technical Reports Server (NTRS)
Banks, H. T.; Kunisch, K.
1983-01-01
An approximation framework is presented for computation (in finite imensional spaces) of Riccati operators that can be guaranteed to converge to the Riccati operator in feedback controls for abstract evolution systems in a Hilbert space. It is shown how these results may be used in the linear optimal regulator problem for a large class of parabolic systems.
Controllability of non-linear biochemical systems.
Ervadi-Radhakrishnan, Anandhi; Voit, Eberhard O
2005-07-01
Mathematical methods of biochemical pathway analysis are rapidly maturing to a point where it is possible to provide objective rationale for the natural design of metabolic systems and where it is becoming feasible to manipulate these systems based on model predictions, for instance, with the goal of optimizing the yield of a desired microbial product. So far, theory-based metabolic optimization techniques have mostly been applied to steady-state conditions or the minimization of transition time, using either linear stoichiometric models or fully kinetic models within biochemical systems theory (BST). This article addresses the related problem of controllability, where the task is to steer a non-linear biochemical system, within a given time period, from an initial state to some target state, which may or may not be a steady state. For this purpose, BST models in S-system form are transformed into affine non-linear control systems, which are subjected to an exact feedback linearization that permits controllability through independent variables. The method is exemplified with a small glycolytic-glycogenolytic pathway that had been analyzed previously by several other authors in different contexts.
Conduction cooling systems for linear accelerator cavities
Kephart, Robert
2017-05-02
A conduction cooling system for linear accelerator cavities. The system conducts heat from the cavities to a refrigeration unit using at least one cavity cooler interconnected with a cooling connector. The cavity cooler and cooling connector are both made from solid material having a very high thermal conductivity of approximately 1.times.10.sup.4 W m.sup.-1 K.sup.-1 at temperatures of approximately 4 degrees K. This allows for very simple and effective conduction of waste heat from the linear accelerator cavities to the cavity cooler, along the cooling connector, and thence to the refrigeration unit.
Dual-range linearized transimpedance amplifier system
Wessendorf, Kurt O.
2010-11-02
A transimpedance amplifier system is disclosed which simultaneously generates a low-gain output signal and a high-gain output signal from an input current signal using a single transimpedance amplifier having two different feedback loops with different amplification factors to generate two different output voltage signals. One of the feedback loops includes a resistor, and the other feedback loop includes another resistor in series with one or more diodes. The transimpedance amplifier system includes a signal linearizer to linearize one or both of the low- and high-gain output signals by scaling and adding the two output voltage signals from the transimpedance amplifier. The signal linearizer can be formed either as an analog device using one or two summing amplifiers, or alternately can be formed as a digital device using two analog-to-digital converters and a digital signal processor (e.g. a microprocessor or a computer).
Feedback linearization application for LLRF control system
Kwon, S.; Regan, A.; Wang, Y.M.; Rohlev, T.
1998-12-31
The Low Energy Demonstration Accelerator (LEDA) being constructed at Los Alamos National Laboratory will serve as the prototype for the low energy section of Acceleration Production of Tritium (APT) accelerator. This paper addresses the problem of the LLRF control system for LEDA. The authors propose a control law which is based on exact feedback linearization coupled with gain scheduling which reduces the effect of the deterministic klystron cathode voltage ripple that is due to harmonics of the high voltage power supply and achieves tracking of desired set points. Also, they propose an estimator of the ripple and its time derivative and the estimates based feedback linearization controller.
Estimability and Regulability of Linear Systems
NASA Technical Reports Server (NTRS)
Baram, Yoram; Kailath, Thomas
1988-01-01
A linear state-space system will be said to be estimable if in estimating its state from its output the posterior error covariance matrix is strictly smaller than the prior covariance matrix. It will be said to be regulable if the quadratic cost of state feedback control is strictly smaller than the cost when no feedback is used. Estimability and regulability are shown to be dual properties, equivalent to the nonreducibility of the Kalman filter and of the optimal linear quadratic regulator, respectively.
Li, Xiaohu; Jin, Xiangdan; Zhao, Nannan; Angelidaki, Irini; Zhang, Yifeng
2017-08-01
Aniline-containing wastewater can cause significant environmental problems and threaten the humans's life. However, rapid degradation of aniline with cost-efficient methods remains a challenge. In this work, a novel microbial electrolysis cell with bipolar membrane was integrated with Fenton reaction (MEC-Fenton) for efficient treatment of real wastewater containing a high concentration (4460 ± 52 mg L(-1)) of aniline. In this system, H2O2 was in situ electro-synthesized from O2 reduction on the graphite cathode and was simultaneously used as source of OH for the oxidation of aniline wastewater under an acidic condition maintained by the bipolar membrane. The aniline was effectively degraded following first-order kinetics at a rate constant of 0.0166 h(-1) under an applied voltage of 0.5 V. Meanwhile, a total organic carbon (TOC) removal efficiency of 93.1 ± 1.2% was obtained, revealing efficient mineralization of aniline. The applicability of bipolar membrane MEC-Fenton system was successfully demonstrated with actual aniline wastewater. Moreover, energy balance showed that the system could be a promising technology for removal of biorefractory organic pollutants from wastewaters. Copyright © 2017 Elsevier Ltd. All rights reserved.
Park, Sinwook; Yossifon, Gilad
2016-06-01
The presence of a floating electrode array located within the depletion layer formed due to concentration polarization across a microchannel-membrane interface device may produce not only induced-charge electro-osmosis (ICEO) but also bipolar current resulting from the induced Faradaic reaction. It has been shown that there exists an optimal thickness of a thin dielectric coating that is sufficient to suppress bipolar currents but still enables ICEO vortices that stir the depletion layer, thereby affecting the system's current-voltage response. In addition, the use of alternating-current electro-osmosis by activating electrodes results in further enhancement of the fluid stirring and opens new routes for on-demand spatiotemporal control of the depletion layer length.
NASA Astrophysics Data System (ADS)
Park, Sinwook; Yossifon, Gilad
2016-06-01
The presence of a floating electrode array located within the depletion layer formed due to concentration polarization across a microchannel-membrane interface device may produce not only induced-charge electro-osmosis (ICEO) but also bipolar current resulting from the induced Faradaic reaction. It has been shown that there exists an optimal thickness of a thin dielectric coating that is sufficient to suppress bipolar currents but still enables ICEO vortices that stir the depletion layer, thereby affecting the system's current-voltage response. In addition, the use of alternating-current electro-osmosis by activating electrodes results in further enhancement of the fluid stirring and opens new routes for on-demand spatiotemporal control of the depletion layer length.
Lectures on algebraic system theory: Linear systems over rings
NASA Technical Reports Server (NTRS)
Kamen, E. W.
1978-01-01
The presentation centers on four classes of systems that can be treated as linear systems over a ring. These are: (1) discrete-time systems over a ring of scalars such as the integers; (2) continuous-time systems containing time delays; (3) large-scale discrete-time systems; and (4) time-varying discrete-time systems.
Minimal Solution of Singular LR Fuzzy Linear Systems
Nikuie, M.; Ahmad, M. Z.
2014-01-01
In this paper, the singular LR fuzzy linear system is introduced. Such systems are divided into two parts: singular consistent LR fuzzy linear systems and singular inconsistent LR fuzzy linear systems. The capability of the generalized inverses such as Drazin inverse, pseudoinverse, and {1}-inverse in finding minimal solution of singular consistent LR fuzzy linear systems is investigated. PMID:24737977
Minimal solution of singular LR fuzzy linear systems.
Nikuie, M; Ahmad, M Z
2014-01-01
In this paper, the singular LR fuzzy linear system is introduced. Such systems are divided into two parts: singular consistent LR fuzzy linear systems and singular inconsistent LR fuzzy linear systems. The capability of the generalized inverses such as Drazin inverse, pseudoinverse, and {1}-inverse in finding minimal solution of singular consistent LR fuzzy linear systems is investigated.
The circadian system of patients with bipolar disorder differs in episodes of mania and depression.
Nováková, Marta; Praško, Ján; Látalová, Klára; Sládek, Martin; Sumová, Alena
2015-05-01
Bipolar disorder is a common psychiatric disease characterized by mood disturbances with alternating episodes of mania and depression. Moreover, disturbances in the sleep/wake cycle are prevalent. We tested a hypothesis that the function of the circadian system, which drives the sleep/wake cycle, may differ in patients with bipolar disorder depending on whether they are experiencing an episode of mania or depression. To assess the functional state of the central circadian clock, daily profiles of melatonin levels in saliva were determined. The functional state of the peripheral clocks was assessed by determining daily profiles of Per1 and Nr1d1 clock gene expression in buccal mucosa cells. Sixteen patients with bipolar disorder in a manic episode, 22 patients in a depressive episode, and 19 healthy control subjects provided samples at regular intervals during a 24-hour cycle. During episodes of mania, the daily profiles of melatonin differed compared with healthy controls and patients in an episode of depression, mainly due to elevated melatonin levels during the daytime. No difference was found between melatonin profiles of control subjects and patients in depression. The Per1 and Nr1d1 profiles were advanced in patients in mania compared with those in depression. Compared with controls, a trend toward an advance was apparent in the profiles of patients during an episode of mania but not depression. The amplitude of the Nr1d1 expression profile was higher in mania than in depression. The data revealed differences in the functional state of the circadian system in patients with bipolar disorder depending on whether they were experiencing a manic or a depressive episode. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Identifiability of linear systems in physical coordinates
NASA Technical Reports Server (NTRS)
Su, Tzu-Jeng; Juang, Jer-Nan
1992-01-01
Identifiability of linear, time-invariant systems in physical coordinates is discussed. It is shown that identification of the system matrix in physical coordinates can be accomplished by determining a transformation matrix that relates the physical locations of actuators and sensors to the test-data-derived input and output matrices. For systems with symmetric matrices, the solution of a constrained optimization problem is used to characterize all the possible solutions of the transformation matrix. Conditions for the existence of a unique transformation matrix are established easily from the explicit form of the solutions. For systems with limited inputs and outputs, the question about which part of the system can be uniquely identified is also answered. A simple mass-spring system is used to verify the conclusions of this study.
Recursive Inversion Of Externally Defined Linear Systems
NASA Technical Reports Server (NTRS)
Bach, Ralph E., Jr.; Baram, Yoram
1992-01-01
Technical memorandum discusses mathematical technique described in "Recursive Inversion by Finite-Impulse-Response Filters" (ARC-12247). Technique is recursive algorithm yielding finite-impulse-response approximation of unknown single-input/single-output, causal, time-invariant, linear, real system, response of which is sequence of impulses. Useful in such diverse applications as medical diagnoses, identification of military targets, geophysical exploration, and nondestructive testing.
Nested observer for linear hybrid dynamical systems
Abdi, M.; Bensalah, H.; Cherki, B.
2009-03-05
The synthesis of observers for linear hybrid dynamical systems ''HDS,'' is significant from the point of view of the applications (control, diagnoses...); it is still, largely open. We proposed a new approach inspired from a new method of identification, where we could obtain better results with respect to discrimination between the discrete states in conflicts and time necessary to this latter. The results of the suggested technique proved to be satisfactory.
Recursive Inversion Of Externally Defined Linear Systems
NASA Technical Reports Server (NTRS)
Bach, Ralph E., Jr.; Baram, Yoram
1992-01-01
Technical memorandum discusses mathematical technique described in "Recursive Inversion by Finite-Impulse-Response Filters" (ARC-12247). Technique is recursive algorithm yielding finite-impulse-response approximation of unknown single-input/single-output, causal, time-invariant, linear, real system, response of which is sequence of impulses. Useful in such diverse applications as medical diagnoses, identification of military targets, geophysical exploration, and nondestructive testing.
Miller, Thomas H
2016-06-01
Bipolar disorder is a chronic mental health disorder that is frequently encountered in primary care. Many patients with depression may actually have bipolar disorder. The management of bipolar disorder requires proper diagnosis and awareness or referral for appropriate pharmacologic therapy. Patients with bipolar disorder require primary care management for comorbidities such as cardiovascular and metabolic disorders.
Non-linear dynamic compensation system
NASA Technical Reports Server (NTRS)
Lin, Yu-Hwan (Inventor); Lurie, Boris J. (Inventor)
1992-01-01
A non-linear dynamic compensation subsystem is added in the feedback loop of a high precision optical mirror positioning control system to smoothly alter the control system response bandwidth from a relatively wide response bandwidth optimized for speed of control system response to a bandwidth sufficiently narrow to reduce position errors resulting from the quantization noise inherent in the inductosyn used to measure mirror position. The non-linear dynamic compensation system includes a limiter for limiting the error signal within preselected limits, a compensator for modifying the limiter output to achieve the reduced bandwidth response, and an adder for combining the modified error signal with the difference between the limited and unlimited error signals. The adder output is applied to control system motor so that the system response is optimized for accuracy when the error signal is within the preselected limits, optimized for speed of response when the error signal is substantially beyond the preselected limits and smoothly varied therebetween as the error signal approaches the preselected limits.
Linear relationships in systems with non linear kinetics.
Fagiolino, P; Savio, E; Stareczek, S
1991-01-01
The elimination rate of drug from a capacity-limited one-compartment model can be expressed by equation (1): [formula: see text] Traditionally equation (1) was linearized according to equation (2): [formula: see text] Here, an alternative linear relationships between concentration and the area under the curve of C/(Km + c]) is proposed: [formula: see text] By iteration of Km into equation (3) until the statistic of analysis of variance for the regression is maximized, both Km and Vmax can be obtained. Several cases were considered: a) Intravenous bolus (single dose): Km (mg/L), Vmax (mg/L h), Vd (L) and V (mg/h) can be estimated. b) Extravascular administration (single dose): by the method of residuals it is possible to make additional estimations of FD/Vd (mg/L) and Ka (1/h). c) Bioequivalence studies: with parameters obtained at single dose, the simulated levels at steady-state are considered for the bioequivalence assessments. d) Km, Vmax estimation with two (C,t) points (single dose): double iteration (Km values and interpolated fictitious third points) are needed. e) Multiple dose: [formula: see text] If t2-t1 = T (interval of administration) it is possible to calculate operatives Km, Vmax, FD/Vd and to estimate Css (steady-state concentration). C1 and C2 correspond to different intervals. All the areas were calculated by the trapezoidal rule.
NASA Astrophysics Data System (ADS)
Komatsu, Kazuo; Takata, Hitoshi
2012-11-01
In this paper, we consider an observer design by using a formal linearization based on Fourier expansion for nonlinear dynamic and measurement systems. A non-linear dynamic system is given by a nonlinear ordinary differential equation, and a measurement sysetm is done by a nonlinear equation. Defining a linearization function which consists of the trigonometric functions considered up to the higher-order, a nonlinear dynamic system is transformed into an augmented linear one with respect to this linearization function by using Fourier expansion. Introducing an augmented measurement vector which consists of polynomials of measurement data, a measurement equation is transformed into an augmented linear one with respect to the linearization function in the same way. To these augmented linearized systems, a linear estimation theory is applied to design a new non-linear observer.
A scaling theory for linear systems
NASA Technical Reports Server (NTRS)
Brockett, R. W.; Krishnaprasad, P. S.
1980-01-01
A theory of scaling for rational (transfer) functions in terms of transformation groups is developed. Two different four-parameter scaling groups which play natural roles in studying linear systems are identified and the effect of scaling on Fisher information and related statistical measures in system identification are studied. The scalings considered include change of time scale, feedback, exponential scaling, magnitude scaling, etc. The scaling action of the groups studied is tied to the geometry of transfer functions in a rather strong way as becomes apparent in the examination of the invariants of scaling. As a result, the scaling process also provides new insight into the parameterization question for rational functions.
Hamlat, Elissa J.; Garro-Moore, Jared K. O'; Nusslock, Robin; Alloy, Lauren B.
2016-01-01
Bipolar disorder is associated with a host of negative physical and interpersonal outcomes including suicide. Emerging adulthood is an age of risk for the onset of bipolar spectrum disorders (BSD) and there has been increased effort to focus on early identification and subsequent intervention for BSDs during this developmental period. Recent research on the behavioral approach system (BAS) hypersensitivity model of bipolar disorder may have implications for the assessment and treatment of BSD in emerging adulthood. We summarize relevant findings on the BAS hypersensitivity model that support the use of reward sensitivity in the early identification of BSDs and suggest evidence-based strategies for clinical work with emerging adults with bipolar spectrum disorders. PMID:28133431
Hamlat, Elissa J; Garro-Moore, Jared K O'; Nusslock, Robin; Alloy, Lauren B
2016-08-01
Bipolar disorder is associated with a host of negative physical and interpersonal outcomes including suicide. Emerging adulthood is an age of risk for the onset of bipolar spectrum disorders (BSD) and there has been increased effort to focus on early identification and subsequent intervention for BSDs during this developmental period. Recent research on the behavioral approach system (BAS) hypersensitivity model of bipolar disorder may have implications for the assessment and treatment of BSD in emerging adulthood. We summarize relevant findings on the BAS hypersensitivity model that support the use of reward sensitivity in the early identification of BSDs and suggest evidence-based strategies for clinical work with emerging adults with bipolar spectrum disorders.
Design of a 2.7-GHz linear OTA and a 250-MHz elliptic filter in bipolar transistor-array technology
NASA Astrophysics Data System (ADS)
Wyszynski, Adam; Schaumann, Rolf; Szczepanski, Stanislaw; van Halen, Paul
1993-01-01
The design of a tunable high-frequency fully differential bipolar operational transconductance amplifier (OTA) is presented. Techniques resulting in tunability and broadbanding are discussed, as well as unavoidable tradeoffs resulting from the lack of a vertical pnp device. Using an 8 GHz bipolar transistor array process, the simulated -3 dB frequency of the OTA is over 2.7 GHz, the maximum linear input range is +/- 2.5 V, and the power dissipation is 28 mW for a power supply of +/- 5 V. The OTA can also operate at a low power supply of +/- 2.5 V. Applying the OTA as a building block, the design of a third-order elliptic OTA-C filter with cutoff frequency of 250 MHz and tuning range from 200 to 290 MHz is presented. Analysis of filter nonidealities, as well as predistortion and compensation techniques, are discussed. Detailed SPICE simulations verify the results of hand calculations and show that temperature variations from -30 to +100 C and supply variations from +/- 4.5 to +/- 7.5 V change the cutoff frequency of the filter by less than 10 percent. The Q-factor can be electronically adjusted for all frequencies in the tuning range.
Robust observer for uncertain linear quantum systems
Yamamoto, Naoki
2006-09-15
In the theory of quantum dynamical filtering, one of the biggest issues is that the underlying system dynamics represented by a quantum stochastic differential equation must be known exactly in order that the corresponding filter provides an optimal performance; however, this assumption is generally unrealistic. Therefore, in this paper, we consider a class of linear quantum systems subjected to time-varying norm-bounded parametric uncertainties and then propose a robust observer such that the variance of the estimation error is guaranteed to be within a certain bound. Although in the linear case much of classical control theory can be applied to quantum systems, the quantum robust observer obtained in this paper does not have a classical analog due to the system's specific structure with respect to the uncertainties. Moreover, by considering a typical quantum control problem, we show that the proposed robust observer is fairly robust against a parametric uncertainty of the system even when the other estimators--the optimal Kalman filter and risk-sensitive observer--fail in the estimation.
Flexible least squares for approximately linear systems
NASA Astrophysics Data System (ADS)
Kalaba, Robert; Tesfatsion, Leigh
1990-10-01
A probability-free multicriteria approach is presented to the problem of filtering and smoothing when prior beliefs concerning dynamics and measurements take an approximately linear form. Consideration is given to applications in the social and biological sciences, where obtaining agreement among researchers regarding probability relations for discrepancy terms is difficult. The essence of the proposed flexible-least-squares (FLS) procedure is the cost-efficient frontier, a curve in a two-dimensional cost plane which provides an explicit and systematic way to determine the efficient trade-offs between the separate costs incurred for dynamic and measurement specification errors. The FLS estimates show how the state vector could have evolved over time in a manner minimally incompatible with the prior dynamic and measurement specifications. A FORTRAN program for implementing the FLS filtering and smoothing procedure for approximately linear systems is provided.
Modeling of linear time-varying systems by linear time-invariant systems of lower order.
NASA Technical Reports Server (NTRS)
Nosrati, H.; Meadows, H. E.
1973-01-01
A method for modeling linear time-varying differential systems by linear time-invariant systems of lower order is proposed, extending the results obtained by Bierman (1972) by resolving such qualities as the model stability, various possible models of differing dimensions, and the uniqueness or nonuniqueness of the model coefficient matrix. In addition to the advantages cited by Heffes and Sarachik (1969) and Bierman, often by modeling a subsystem of a larger system it is possible to analyze the overall system behavior more easily, with resulting savings in computation time.
Linear unsaturating magnetoresistance in disordered systems
NASA Astrophysics Data System (ADS)
Lai, Ying Tong; Lara, Silvia; Love, Cameron; Ramakrishnan, Navneeth; Adam, Shaffique
Theoretical works have shown that disordered systems exhibit classical magnetoresistance (MR). In this talk, we examine a variety of experimental systems that observe linear MR at high magnetic fields, including silver chalcogenides, graphene, graphite and Weyl semimetals. We show that a careful analysis of the magnitude of the MR, as well as the field strength at which the MR changes from quadratic to linear, reveal important properties of the system, such as the ratio of the root-mean-square fluctuations in the carrier density and the average carrier density. By looking at other properties such as the zero-field mobility, we show that this carrier density inhomogeneity is consistent with what is known about the microscopic impurities in these experiments. The application of this disorder-induced MR to a variety of different experimental scenarios underline the universality of these theoretical models. This work is supported by the Singapore National Research Foundation (NRF-NRFF2012-01) and the Singapore Ministry of Education and Yale-NUS College through Grant Number R-607-265-01312.
Abbasi, Moslem; Sadeghi, Hasan; Pirani, Zabih; Vatandoust, Leyla
2016-01-01
Nowadays, prevalence of addictive behaviors among bipolar patients is considered to be a serious health threat by the World Health Organization. The aim of this study is to investigate the role of behavioral activation and inhibition systems in predicting addictive behaviors of male patients with bipolar disorder at the Roozbeh Psychiatric Hospital. The research method used in this study is correlation. The study population consisted of 80 male patients with bipolar disorder referring to the psychiatrics clinics of Tehran city in 2014 who were referred to the Roozbeh Psychiatric Hospital. To collect data, the international and comprehensive inventory diagnostic interview, behavioral activation and inhibition systems scale, and addictive behaviors scale were used. The results showed that there is a positive and significant relationship between behavioral activation systems and addictive behaviors (addictive eating, alcohol addiction, television addiction, cigarette addiction, mobile addiction, etc.). In addition, correlation between behavioral inhibition systems and addictive behaviors (addictive eating, alcohol addiction, TV addiction, cigarette addiction, mobile addiction) is significantly negative. Finally, regression analysis showed that behavioral activation and inhibition systems could significantly predict 47% of addictive behaviors in patients with bipolar disorder. It can be said that the patients with bipolar disorder use substance and addictive behaviors for enjoyment and as pleasure stimulants; they also use substances to suppress unpleasant stimulants and negative emotions. These results indicate that behavioral activation and inhibition systems have an important role in the incidence and exacerbation of addictive behaviors. Therefore, preventive interventions in this direction seem to be necessary.
Yan, Shengjie; Wu, Xiaomei; Wang, Weiqi
2017-09-01
Radiofrequency (RF) energy is often used to create a linear lesion or discrete lesions for blocking the accessory conduction pathways for treating atrial fibrillation. By using finite element analysis, we study the ablation effect of amplitude control ablation mode (AcM) and bipolar ablation mode (BiM) in creating a linear lesion and discrete lesions in a 5-mm-thick atrial wall; particularly, the characteristic of lesion shape has been investigated in amplitude control ablation. Computer models of multipolar catheter were developed to study the lesion dimensions in atrial walls created through AcM, BiM and special electrodes activated ablation methods in AcM and BiM. To validate the theoretical results in this study, an in vitro experiment with porcine cardiac tissue was performed. At 40 V/20 V root mean squared (RMS) of the RF voltage for AcM, the continuous and transmural lesion was created by AcM-15s, AcM-5s and AcM-ad-20V ablation in 5-mm-thick atrial wall. At 20 V RMS for BiM, the continuous but not transmural lesion was created. AcM ablation yielded asymmetrical and discrete lesions shape, whereas the lesion shape turned to more symmetrical and continuous as the electrodes alternative activated period decreased from 15 s to 5 s. Two discrete lesions were created when using AcM, AcM-ad-40V, BiM-ad-20V and BiM-ad-40V. The experimental and computational thermal lesion shapes created in cardiac tissue were in agreement. Amplitude control ablation technology and bipolar ablation technology are feasible methods to create continuous lesion or discrete for pulmonary veins isolation.
Latimer, Cassandra A; Nelson, Meghan; Moore, Camille M; Martin, Kimberly E
2014-01-01
Bipolar devices are routinely used to seal blood vessels instead of sutures and clips. Recent work examining the impact of vascular proteins on bipolar seal performance found that collagen and elastin (CE) content within porcine arteries was a significant predictor of a vessel's burst pressure (VBPr). This study examined seal performance across a range of human blood vessels to investigate whether a similar relationship existed. In addition, we compared VBPr and CE content between porcine and human blood vessels. Our primary hypothesis is that higher collagen-to-elastin ratio will predict higher VBPr in human vasculature. In six cadavers, 185 blood vessels from nine anatomic locations were sealed using a bipolar electrosurgical system. A linear mixed model framework was used to evaluate the impact of vessel diameter and CE content on VBPr. The effect of CE ratio on VBPr is modified by vessel size, with CE ratio having larger influence on VBPr in smaller diameter vessels. Seal burst pressure of vessels 2-5 mm in diameter was significantly associated with their CE content. Comparison of average VBPr between species revealed porcine carotid and iliac arteries (440-670 mmHg) to be the best vessel types for predicting the seal strength of most human blood vessels (420-570 mmHg) examined. CE content significantly modified the seal strength of small to medium sized blood vessels but had limited impact on vessels >5 mm. Copyright © 2014 Elsevier Inc. All rights reserved.
Design of bipolar, flowing-electrolyte zinc-bromine electric-vehicle battery systems
NASA Astrophysics Data System (ADS)
Malachesky, P. A.; Bellows, R. J.; Einstein, H. E.; Grimes, P. G.; Newby, K.; Young, A.
1983-01-01
The integration of bipolar, flowing electrolyte zinc-bromine technology into a viable electric vehicle battery system requires careful analysis of the requirements placed on the battery system by the EV power train. In addition to the basic requirement of an appropriate battery voltage and power density, overall battery system energy efficiency must also be considered and parasitic losses from auxiliaries such as pumps and shunt current protection minimized. An analysis of the influence of these various factors on zinc-bromine EV battery system design has been carried out for two types of EV propulsion systems. The first of these is a nominal 100V dc system, while the second is a high voltage (200V dc) system as might be used with an advanced design ac propulsion system. Battery performance was calculated using an experimentally determined relationship which expresses battery voltage as a function of current density and state-of-charge.
Linear Actuator System for the NASA Docking System
NASA Technical Reports Server (NTRS)
Dick, Brandon N.; Oesch, Christopher; Rupp, Timothy W.
2017-01-01
The Linear Actuator System (LAS) is a major sub-system within the NASA Docking System (NDS). The NDS Block 1 will be used on the Boeing Crew Space Transportation (CST-100) system to achieve docking with the International Space Station. Critical functions in the Soft Capture aspect of docking are performed by the LAS. This paper describes the general function of the LAS, the system's key requirements and technical challenges, and the development and qualification approach for the system.
Lee, Kyung-Sang; Park, Young-Min
2012-01-01
Objective The loudness dependence of the auditory evoked potential (LDAEP) is suggested to be a marker of serotonin system function. This study explored the LDAEP of multiple mood statuses (depression, mania, and euthymia) and its clinical implication in bipolar disorder patients. Methods A total of 89 subjects, comprising 35 patients with bipolar disorder, 32 patients with schizophrenia, and 22 healthy controls were evaluated. The bipolar disorder cases comprised 10 depressed patients, 15 patients with mania, and 10 euthymic patients. The N1/P2 peak-to-peak amplitudes were measured at 5 stimulus intensities, and the LDAEP was calculated as the slope of the linear regression. Both cortical and source LDAEP values were calculated. Results LDAEP varied according to mood statuses, and was significantly stronger in cases of euthymia, depression, and mania. Cortical LDAEP was significantly stronger in patients with bipolar euthymia compared with schizophrenia, stronger in bipolar depression than in schizophrenia, stronger in healthy controls than in schizophrenia patients, and stronger in healthy controls than in patients with bipolar mania. Source LDAEP was significantly stronger in patients with bipolar euthymia, bipolar depression, and bipolar mania compared with schizophrenia, stronger in bipolar euthymia than in bipolar mania. Psychotic features weakened the source LDAEP relative to nonpsychotic features. The severity of the depressive symptom was negatively correlated with source LDAEP. Conclusion These findings suggest that the serotonin activity of patients with bipolar disorder may vary according to mood status. A longitudinal follow-up study should be pursued using drug-naive subjects. PMID:22993531
Systems tunnel linear shaped charge lightning strike
NASA Technical Reports Server (NTRS)
Cook, M.
1989-01-01
Simulated lightning strike testing of the systems tunnel linear shaped charge (LSC) was performed at the Thiokol Lightning Test Complex in Wendover, Utah, on 23 Jun. 1989. The test article consisted of a 160-in. section of the LSC enclosed within a section of the systems tunnel. The systems tunnel was bonded to a section of a solid rocket motor case. All test article components were full scale. The systems tunnel cover of the test article was subjected to three discharges (each discharge was over a different grounding strap) from the high-current generator. The LSC did not detonate. All three grounding straps debonded and violently struck the LSC through the openings in the systems tunnel floor plates. The LSC copper surface was discolored around the areas of grounding strap impact, and arcing occurred at the LSC clamps and LSC ends. This test verified that the present flight configuration of the redesigned solid rocket motor systems tunnel, when subjected to simulated lightning strikes with peak current levels within 71 percent of the worst-case lightning strike condition of NSTS-07636, is adequate to prevent LSC ignition. It is therefore recommended that the design remain unchanged.
CONTROL SYSTEM ANALYSIS FOR THE PERTURBED LINEAR ACCELERATOR RF SYSTEM
SUNG-IL KWON; AMY H. REGAN
2002-04-10
This paper addresses the modeling problem of the linear accelerator RF system in SNS. Klystrons are modeled as linear parameter varying systems. The effect of the high voltage power supply ripple on the klystron output voltage and the output phase is modeled as an additive disturbance. The cavity is modeled as a linear system and the beam current is modeled as the exogenous disturbance. The output uncertainty of the low level RF system which results from the uncertainties in the RF components and cabling is modeled as multiplicative uncertainty. Also, the feedback loop uncertainty and digital signal processing signal conditioning subsystem uncertainties are lumped together and are modeled as multiplicative uncertainty. Finally, the time delays in the loop are modeled as a lumped time delay. For the perturbed open loop system, the closed loop system performance, and stability are analyzed with the PI feedback controller.
Stochastic robustness of linear control systems
NASA Technical Reports Server (NTRS)
Stengel, Robert F.; Ryan, Laura E.
1990-01-01
A simple numerical procedure for estimating the stochastic robustness of a linear, time-invariant system is described. Monte Carlo evaluation of the system's eigenvalues allows the probability of instability and the related stochastic root locus to be estimated. This definition of robustness is an alternative to existing deterministic definitions that address both structured and unstructured parameter variations directly. This analysis approach treats not only Gaussian parameter uncertainties but non-Gaussian cases, including uncertain-but-bounded variations. Trivial extensions of the procedure admit alternate discriminants to be considered. Thus, the probabilities that stipulated degrees of instability will be exceeded or that closed-loop roots will leave desirable regions also can be estimated. Results are particularly amenable to graphical presentation.
Linear optical response of finite systems using multishift linear system solvers
Hübener, Hannes; Giustino, Feliciano
2014-07-28
We discuss the application of multishift linear system solvers to linear-response time-dependent density functional theory. Using this technique the complete frequency-dependent electronic density response of finite systems to an external perturbation can be calculated at the cost of a single solution of a linear system via conjugate gradients. We show that multishift time-dependent density functional theory yields excitation energies and oscillator strengths in perfect agreement with the standard diagonalization of the response matrix (Casida's method), while being computationally advantageous. We present test calculations for benzene, porphin, and chlorophyll molecules. We argue that multishift solvers may find broad applicability in the context of excited-state calculations within density-functional theory and beyond.
Control of Linear Systems Over Commutative Normed Algebras with Applications.
1987-02-01
Identify by block number) System Theory, Linear Systems, Control, Systems with Time Delays, Time - Varying Systems, State- Space Models, Pole...modes for the class of linear time -varying systems. These concepts are defined in terms of a noncommutative factorization of opera- tor polynomials...classes of complex linear systems, including systems with time delays, systems with unknown parameters and time -varying systems. In the work on
Bipolar disorder is a serious mental illness. People who have it go through unusual mood changes. They go ... The down feeling is depression. The causes of bipolar disorder aren't always clear. It runs in families. ...
Bipolar disorder Overview By Mayo Clinic Staff Bipolar disorder, formerly called manic depression, is a mental health condition that causes extreme mood swings that include emotional highs (mania or hypomania) and lows ( ...
Ludtmann, Marthe H.R.; Boeckeler, Katrina; Williams, Robin S.B.
2011-01-01
Understanding the mechanisms of drug action has been the primary focus for pharmacological researchers, traditionally using rodent models. However, non-sentient model systems are now increasingly being used as an alternative approach to better understand drug action or targets. One of these model systems, the social amoeba Dictyostelium, enables the rapid ablation or over-expression of genes, and the subsequent use of isogenic cell culture for the analysis of cell signalling pathways in pharmacological research. The model also supports an increasingly important ethical view of research, involving the reduction, replacement and refinement of animals in biomedical research. This review outlines the use of Dictyostelium in understanding the pharmacological action of two commonly used bipolar disorder treatments (valproic acid and lithium). Both of these compounds regulate mitogen activated protein (MAP) kinase and inositol phospholipid-based signalling by unknown means. Analysis of the molecular pathways targeted by these drugs in Dictyostelium and translation of discoveries to animal systems has helped to further understand the molecular mechanisms of these bipolar disorder treatments. PMID:21093602
Finite Hamiltonian Systems: Linear Transformations and Aberrations
NASA Astrophysics Data System (ADS)
Wolf, Kurt Bernardo
2008-11-01
In finite Hamiltonian systems, the operators of position, momentum, and energy have a finite number N of eigenvalues. These operators can be naturally realized as generators of the Lie algebra su(2), in a representation of spin j, of dimension N = 2j+1. Time evolution is rotation of a phase space sphere, whose projections perform the harmonic motion of an oscillator. The (centrally extended) group of rigid—linear—motions of this phase space is then U(2). On the other hand, N-point wavefunctions—signals—can be subject to a U(N) group of unitary matrices, containing the linear U(2); aberrations are transformations outside that subgroup. As in geometric optics, we classify the aberration multiplets by order and weight. Their action on phase space is displayed by means of a Wigner function on the sphere, to be compared with the corresponding geometric canonical transformations.
System theory as applied differential geometry. [linear system
NASA Technical Reports Server (NTRS)
Hermann, R.
1979-01-01
The invariants of input-output systems under the action of the feedback group was examined. The approach used the theory of Lie groups and concepts of modern differential geometry, and illustrated how the latter provides a basis for the discussion of the analytic structure of systems. Finite dimensional linear systems in a single independent variable are considered. Lessons of more general situations (e.g., distributed parameter and multidimensional systems) which are increasingly encountered as technology advances are presented.
Unsplit bipolar pulse forming line
Rhodes, Mark A [Pleasanton, CA
2011-05-24
A bipolar pulse forming transmission line module and system for linear induction accelerators having first, second, third, and fourth planar conductors which form a sequentially arranged interleaved stack having opposing first and second ends, with dielectric layers between the conductors. The first and second planar conductors are connected to each other at the first end, and the first and fourth planar conductors are connected to each other at the second end via a shorting plate. The third planar conductor is electrically connectable to a high voltage source, and an internal switch functions to short at the first end a high voltage from the third planar conductor to the fourth planar conductor to produce a bipolar pulse at the acceleration axis with a zero net time integral. Improved access to the switch is enabled by an aperture through the shorting plate and the proximity of the aperture to the switch.
Time-varying linear systems and the theory of non-linear waves
NASA Technical Reports Server (NTRS)
Hermann, R.
1979-01-01
The isospectral deformation of a Sturm-Liouville equation is extended to general linear time-varying systems and a method is described for determining the resulting nonlinear partial differential equations. Consideration is given to (1) isospectral deformation of I/O systems with boundary value conditions and (2) the spectral vector bundles attached to linear time-varying systems.
Generic perturbations of linear integrable Hamiltonian systems
NASA Astrophysics Data System (ADS)
Bounemoura, Abed
2016-11-01
In this paper, we investigate perturbations of linear integrable Hamiltonian systems, with the aim of establishing results in the spirit of the KAM theorem (preservation of invariant tori), the Nekhoroshev theorem (stability of the action variables for a finite but long interval of time) and Arnold diffusion (instability of the action variables). Whether the frequency of the integrable system is resonant or not, it is known that the KAM theorem does not hold true for all perturbations; when the frequency is resonant, it is the Nekhoroshev theorem that does not hold true for all perturbations. Our first result deals with the resonant case: we prove a result of instability for a generic perturbation, which implies that the KAM and the Nekhoroshev theorem do not hold true even for a generic perturbation. The case where the frequency is nonresonant is more subtle. Our second result shows that for a generic perturbation the KAM theorem holds true. Concerning the Nekhrosohev theorem, it is known that one has stability over an exponentially long (with respect to some function of ɛ -1) interval of time and that this cannot be improved for all perturbations. Our third result shows that for a generic perturbation one has stability for a doubly exponentially long interval of time. The only question left unanswered is whether one has instability for a generic perturbation (necessarily after this very long interval of time).
Linear Actuator System for the NASA Docking System
NASA Technical Reports Server (NTRS)
Dick, Brandon; Oesch, Chris
2017-01-01
The Linear Actuator System (LAS) is a major sub-system within the NASA Docking System (NDS). The NDS Block 1 will be used on the Boeing Crew Space Transportation (CST-100) system to achieve docking with the International Space Station. Critical functions in the Soft Capture aspect of docking are performed by the LAS, which implements the Soft Impact Mating and Attenuation Concept (SIMAC). This paper describes the general function of the LAS, the system's key requirements and technical challenges, and the development and qualification approach for the system.
Linear tracking systems with applications to aircraft control system design
NASA Technical Reports Server (NTRS)
Lee, W. H.; Athans, M.; Castanon, D.; Bacchioloni, F.
1977-01-01
A class of optimal linear time invariant tracking systems, both in continuous time and discrete time, of which the number of inputs (which are restricted to be step functions) is equal to the number of system outputs, is studied. Along with derivation of equations and design procedures, two discretization schemes are presented, constraining either the control or its time derivative, to be a constant over each sampling period. Descriptions are given for the linearized model of the F-8C aircraft longitudinal dynamics, and the C* handling qualities criterion, which then serve as an illustration of the applications of these linear tracking designs. A suboptimal reduced state design is also presented. Numerical results are given for both the continuous time and discrete time designs.
Nondeterministic Noiseless Linear Amplification of Quantum Systems
NASA Astrophysics Data System (ADS)
Ralph, T. C.; Lund, A. P.
2009-04-01
We introduce the concept of non-deterministic noiseless linear amplification. We propose a linear optical realization of this transformation that could be built with current technology. We discuss the application of the device to distillation of continuous variable entanglement. We demonstrate that highly pure entanglement can be distilled from transmission over a lossy channel.
Linear stability in an extended ring system
NASA Astrophysics Data System (ADS)
Arribas, M.; Elipe, A.; Palacios, M.
2010-10-01
The planar n+1 ring body problem consists of n bodies of equal mass m uniformly distributed around a central body of mass m0. The bodies are rotating on its own plane about its center of mass with a constant angular velocity. Since Maxwell introduced the problem to understand the stability of Saturn's rings, many authors have studied and extended the problem. In particular, we proved that if forces that are functions of the mutual distances are considered the n-gon is a central configuration. Examples of this kind are the quasi-homogeneous potentials. In a previous work we analyzed the linear stability of a system where the potential of the central body is a Manev's type potential. By introducing a perturbation parameter (ɛ0) to the Newtonian potential associated with the central primary, we showed that unstable cases for the unperturbed problem, for n<=6, may become stable for some values of the perturbation. The purpose of this paper is to show that it is possible to increase the range of values of the mass parameter (μ = m/m0) and the parameter (V0) in order to render a stable configuration. In order to get it, we introduce a second perturbation term (with parameter (V1) to the Newtonian potential of the bodies in the ring. We show some results for the problem with n = 7.
Symmetric linear systems - An application of algebraic systems theory
NASA Technical Reports Server (NTRS)
Hazewinkel, M.; Martin, C.
1983-01-01
Dynamical systems which contain several identical subsystems occur in a variety of applications ranging from command and control systems and discretization of partial differential equations, to the stability augmentation of pairs of helicopters lifting a large mass. Linear models for such systems display certain obvious symmetries. In this paper, we discuss how these symmetries can be incorporated into a mathematical model that utilizes the modern theory of algebraic systems. Such systems are inherently related to the representation theory of algebras over fields. We will show that any control scheme which respects the dynamical structure either implicitly or explicitly uses the underlying algebra.
Symmetric linear systems - An application of algebraic systems theory
NASA Technical Reports Server (NTRS)
Hazewinkel, M.; Martin, C.
1983-01-01
Dynamical systems which contain several identical subsystems occur in a variety of applications ranging from command and control systems and discretization of partial differential equations, to the stability augmentation of pairs of helicopters lifting a large mass. Linear models for such systems display certain obvious symmetries. In this paper, we discuss how these symmetries can be incorporated into a mathematical model that utilizes the modern theory of algebraic systems. Such systems are inherently related to the representation theory of algebras over fields. We will show that any control scheme which respects the dynamical structure either implicitly or explicitly uses the underlying algebra.
Perfect decoupling of linear systems with discrete parameter uncertainties
NASA Technical Reports Server (NTRS)
Dorato, P.; Wang, S.-H.; Asher, R.
1977-01-01
A design procedure based on Gilbert's decoupling parameters for determining a fixed state feedback control law which decouples a linear system with discrete parameter uncertainties is described. Perfect decoupling conditions are established which involve a test for the existence of a solution to a system of linear equations. An actual solution of the linear equations yields the decoupling control law.
Lin Teng Shee, Fabrice; Arul, Joseph; Brunet, Serge; Bazinet, Laurent
2008-11-12
Chitosan, a linear polysaccharide composed of beta-1,4 linked d-glucosamine residues, can be depolymerized into oligomers by enzymatic reaction with chitosanase. Recently, bipolar membrane electrodialysis (BMED) has been used for chitosan solubilization and for terminating the enzymatic reaction by action of electrogenerated acid and base, respectively. The aim of the present study was to test a complete "3-in-1" process using a three-compartment BMED configuration to perform simultaneously the solubilization of chitosan, the inactivation of chitosanase, and the demineralization of the oligomers. In addition, the BMED process was compared to a conventional process using chemical acid and base. The BMED method was found to be as effective as the conventional method for solubilizing the chitosan and for inactivating the chitosanase. Furthermore, the use of BMED allowed a demineralization rate of 53% of the chito-oligomer solution in the diluate compartment. A global process of chitosan hydrolysis into its oligomers using a BMED system was proposed. This technology has great potential for industrial application in chitosan oligomer preparation, because it is convenient and ecological and it produces chito-oligomers with a lower mineral content compared with the conventional method.
Abbasi, Moslem; Sadeghi, Hasan; Pirani, Zabih; Vatandoust, Leyla
2016-01-01
Background: Nowadays, prevalence of addictive behaviors among bipolar patients is considered to be a serious health threat by the World Health Organization. The aim of this study is to investigate the role of behavioral activation and inhibition systems in predicting addictive behaviors of male patients with bipolar disorder at the Roozbeh Psychiatric Hospital. Materials and Methods: The research method used in this study is correlation. The study population consisted of 80 male patients with bipolar disorder referring to the psychiatrics clinics of Tehran city in 2014 who were referred to the Roozbeh Psychiatric Hospital. To collect data, the international and comprehensive inventory diagnostic interview, behavioral activation and inhibition systems scale, and addictive behaviors scale were used. Results: The results showed that there is a positive and significant relationship between behavioral activation systems and addictive behaviors (addictive eating, alcohol addiction, television addiction, cigarette addiction, mobile addiction, etc.). In addition, correlation between behavioral inhibition systems and addictive behaviors (addictive eating, alcohol addiction, TV addiction, cigarette addiction, mobile addiction) is significantly negative. Finally, regression analysis showed that behavioral activation and inhibition systems could significantly predict 47% of addictive behaviors in patients with bipolar disorder. Conclusions: It can be said that the patients with bipolar disorder use substance and addictive behaviors for enjoyment and as pleasure stimulants; they also use substances to suppress unpleasant stimulants and negative emotions. These results indicate that behavioral activation and inhibition systems have an important role in the incidence and exacerbation of addictive behaviors. Therefore, preventive interventions in this direction seem to be necessary. PMID:28194203
McElroy, James F.
1989-01-01
The present invention discloses an improved fuel cell utilizing an ion transporting membrane having a catalytic anode and a catalytic cathode bonded to opposite sides of the membrane, a wet-proofed carbon sheet in contact with the cathode surface opposite that bonded to the membrane and a bipolar separator positioned in electrical contact with the carbon sheet and the anode of the adjacent fuel cell. Said bipolar separator and carbon sheet forming an oxidant flowpath, wherein the improvement comprises an electrically conductive screen between and in contact with the wet-proofed carbon sheet and the bipolar separator improving the product water removal system of the fuel cell.
Decay estimates of solutions to the bipolar non-isentropic compressible Euler–Maxwell system
NASA Astrophysics Data System (ADS)
Tan, Zhong; Wang, Yong; Tong, Leilei
2017-10-01
We consider the global existence and large time behavior of solutions near a constant equilibrium state to the bipolar non-isentropic compressible Euler–Maxwell system in {R}3 , where the background magnetic field could be non-zero. The global existence is established under the assumption that the H 3 norm of the initial data is small, but its higher order derivatives could be large. Combining the negative Sobolev (or Besov) estimates with the interpolation estimates, we prove the optimal time decay rates of the solution and its higher order spatial derivatives. In this sense, our results improve the similar ones in Wang et al (2012 SIAM J. Math. Anal. 44 3429–57).
Polynomial compensation, inversion, and approximation of discrete time linear systems
NASA Technical Reports Server (NTRS)
Baram, Yoram
1987-01-01
The least-squares transformation of a discrete-time multivariable linear system into a desired one by convolving the first with a polynomial system yields optimal polynomial solutions to the problems of system compensation, inversion, and approximation. The polynomial coefficients are obtained from the solution to a so-called normal linear matrix equation, whose coefficients are shown to be the weighting patterns of certain linear systems. These, in turn, can be used in the recursive solution of the normal equation.
Formal modeling and verification of fractional order linear systems.
Zhao, Chunna; Shi, Likun; Guan, Yong; Li, Xiaojuan; Shi, Zhiping
2016-05-01
This paper presents a formalization of a fractional order linear system in a higher-order logic (HOL) theorem proving system. Based on the formalization of the Grünwald-Letnikov (GL) definition, we formally specify and verify the linear and superposition properties of fractional order systems. The proof provides a rigor and solid underpinnings for verifying concrete fractional order linear control systems. Our implementation in HOL demonstrates the effectiveness of our approach in practical applications.
Systemic challenges in bipolar disorder management: A patient-centered approach.
Nestsiarovich, Anastasiya; Hurwitz, Nathaniel G; Nelson, Stuart J; Crisanti, Annette S; Kerner, Berit; Kuntz, Matt J; Smith, Alicia N; Volesky, Emma; Schroeter, Quentin L; DeShaw, Jason L; Young, S Stanley; Obenchain, Robert L; Krall, Ronald L; Jordan, Kimmie; Fawcett, Jan; Tohen, Mauricio; Perkins, Douglas J; Lambert, Christophe G
2017-09-13
As part of a series of Patient-Centered Outcomes Research Institute-funded large-scale retrospective observational studies on bipolar disorder (BD) treatments and outcomes, we sought the input of patients with BD and their family members to develop research questions. We aimed to identify systemic root causes of patient-reported challenges with BD management in order to guide subsequent studies and initiatives. Three focus groups were conducted where patients and their family members (total n = 34) formulated questions around the central theme, "What do you wish you had known in advance or over the course of treatment for BD?" In an affinity mapping exercise, participants clustered their questions and ranked the resulting categories by importance. The research team and members of our patient partner advisory council further rated the questions by expected impact on patients. Using a Theory of Constraints systems thinking approach, several causal models of BD management challenges and their potential solution were developed with patients using the focus group data. A total of 369 research questions were mapped to 33 categories revealing 10 broad themes. The top priorities for patient stakeholders involved pharmacotherapy and treatment alternatives. Analysis of causal relationships underlying 47 patient concerns revealed two core conflicts: for patients, whether or not to take pharmacotherapy, and for mental health services, the dilemma of care quality vs quantity. To alleviate the core conflicts identified, BD management requires a coordinated multidisciplinary approach including: improved access to mental health services, objective diagnostics, sufficient provider visit time, evidence-based individualized treatment, and psychosocial support. © 2017 The Authors. Bipolar Disorders Published by John Wiley & Sons Ltd.
Linear System of Equations, Matrix Inversion, and Linear Programming Using MS Excel
ERIC Educational Resources Information Center
El-Gebeily, M.; Yushau, B.
2008-01-01
In this note, we demonstrate with illustrations two different ways that MS Excel can be used to solve Linear Systems of Equation, Linear Programming Problems, and Matrix Inversion Problems. The advantage of using MS Excel is its availability and transparency (the user is responsible for most of the details of how a problem is solved). Further, we…
Linear System of Equations, Matrix Inversion, and Linear Programming Using MS Excel
ERIC Educational Resources Information Center
El-Gebeily, M.; Yushau, B.
2008-01-01
In this note, we demonstrate with illustrations two different ways that MS Excel can be used to solve Linear Systems of Equation, Linear Programming Problems, and Matrix Inversion Problems. The advantage of using MS Excel is its availability and transparency (the user is responsible for most of the details of how a problem is solved). Further, we…
Non-linear system identification in flow-induced vibration
Spanos, P.D.; Zeldin, B.A.; Lu, R.
1996-12-31
The paper introduces a method of identification of non-linear systems encountered in marine engineering applications. The non-linearity is accounted for by a combination of linear subsystems and known zero-memory non-linear transformations; an equivalent linear multi-input-single-output (MISO) system is developed for the identification problem. The unknown transfer functions of the MISO system are identified by assembling a system of linear equations in the frequency domain. This system is solved by performing the Cholesky decomposition of a related matrix. It is shown that the proposed identification method can be interpreted as a {open_quotes}Gram-Schmidt{close_quotes} type of orthogonal decomposition of the input-output quantities of the equivalent MISO system. A numerical example involving the identification of unknown parameters of flow (ocean wave) induced forces on offshore structures elucidates the applicability of the proposed method.
A Cognitive Approach to Solving Systems of Linear Equations
ERIC Educational Resources Information Center
Ramirez, Ariel A.
2009-01-01
Systems of linear equations are used in a variety of fields. Exposure to the concept of systems of equations initially occurs at the high school level and continues through college. Attempts to unearth what students understand about the solutions of linear systems have been limited. Gaps exist in our knowledge of how students understand systems…
A Cognitive Approach to Solving Systems of Linear Equations
ERIC Educational Resources Information Center
Ramirez, Ariel A.
2009-01-01
Systems of linear equations are used in a variety of fields. Exposure to the concept of systems of equations initially occurs at the high school level and continues through college. Attempts to unearth what students understand about the solutions of linear systems have been limited. Gaps exist in our knowledge of how students understand systems…
A stabilization algorithm for linear discrete constant systems
NASA Technical Reports Server (NTRS)
Armstrong, E. S.; Rublein, G. T.
1976-01-01
A procedure is derived for stabilizing linear constant discrete systems which is a discrete analog to the extended Bass algorithm for stabilizing linear constant continuous systems. The procedure offers a method for constructing a stabilizing feedback without the computational difficulty of raising the unstable open-loop response matrix to powers thus making the method attractive for high order or poorly conditioned systems.
ERIC Educational Resources Information Center
Spearing, Melissa
Bipolar disorder, a brain disorder that causes unusual shifts in a person's mood, affects approximately one percent of the population. It commonly occurs in late adolescence and is often unrecognized. The diagnosis of bipolar disorder is made on the basis of symptoms, course of illness, and when possible, family history. Thoughts of suicide are…
Le Bas, James; Castle, David; Newton, Richard; O'Loughlin, Denis
2013-10-01
To explore aspects of prestige in the bipolar disorders. Conceptualisation around bipolar spectrum disorders is in its infancy, in particular with relation to their neurobiological and evolutionary underpinnings. While research has privileged proximate causation, a separate, nascent dialogue in relation to the 'aboutness' of affective syndromes exists. Arguably, affective disorders can be considered in relation to the social group phenomena of self-esteem and prestige. A conceptualisation of Panksepp's PLAY and Thayer's energetic arousal systems combined- Hedonic Energetic Social Engagement- can be invoked as a mechanism for bipolarity. This has been acted upon by prestige competition to create a selection pressure for prestige. In this model, bipolar spectrum conditions evolved as a by-product of this process.
Singular linear quadratic control problem for systems with linear and constant delay
NASA Astrophysics Data System (ADS)
Sesekin, A. N.; Andreeva, I. Yu.; Shlyakhov, A. S.
2016-12-01
This article is devoted to the singular linear-quadratic optimization problem on the trajectories of the linear non-autonomous system of differential equations with linear and constant delay. It should be noted that such task does not solve the class of integrable controls, so to ensure the existence of a solution is needed to expand the class of controls to include the control impulse components. For the problem under consideration, we have built program control containing impulse components in the initial and final moments time. This is done under certain assumptions on the functional and the right side of the control system.
Grande, Iria; Berk, Michael; Birmaher, Boris; Vieta, Eduard
2016-04-09
Bipolar disorder is a recurrent chronic disorder characterised by fluctuations in mood state and energy. It affects more than 1% of the world's population irrespective of nationality, ethnic origin, or socioeconomic status. Bipolar disorder is one of the main causes of disability among young people, leading to cognitive and functional impairment and raised mortality, particularly death by suicide. A high prevalence of psychiatric and medical comorbidities is typical in affected individuals. Accurate diagnosis of bipolar disorder is difficult in clinical practice because onset is most commonly a depressive episode and looks similar to unipolar depression. Moreover, there are currently no valid biomarkers for the disorder. Therefore, the role of clinical assessment remains key. Detection of hypomanic periods and longitudinal assessment are crucial to differentiate bipolar disorder from other conditions. Current knowledge of the evolving pharmacological and psychological strategies in bipolar disorder is of utmost importance. Copyright © 2016 Elsevier Ltd. All rights reserved.
Asymptotic Stability of Interconnected Passive Non-Linear Systems
NASA Technical Reports Server (NTRS)
Isidori, A.; Joshi, S. M.; Kelkar, A. G.
1999-01-01
This paper addresses the problem of stabilization of a class of internally passive non-linear time-invariant dynamic systems. A class of non-linear marginally strictly passive (MSP) systems is defined, which is less restrictive than input-strictly passive systems. It is shown that the interconnection of a non-linear passive system and a non-linear MSP system is globally asymptotically stable. The result generalizes and weakens the conditions of the passivity theorem, which requires one of the systems to be input-strictly passive. In the case of linear time-invariant systems, it is shown that the MSP property is equivalent to the marginally strictly positive real (MSPR) property, which is much simpler to check.
Self-characterization of linear and nonlinear adaptive optics systems
NASA Astrophysics Data System (ADS)
Hampton, Peter J.; Conan, Rodolphe; Keskin, Onur; Bradley, Colin; Agathoklis, Pan
2008-01-01
We present methods used to determine the linear or nonlinear static response and the linear dynamic response of an adaptive optics (AO) system. This AO system consists of a nonlinear microelectromechanical systems deformable mirror (DM), a linear tip-tilt mirror (TTM), a control computer, and a Shack-Hartmann wavefront sensor. The system is modeled using a single-input-single-output structure to determine the one-dimensional transfer function of the dynamic response of the chain of system hardware. An AO system has been shown to be able to characterize its own response without additional instrumentation. Experimentally determined models are given for a TTM and a DM.
Decentrally stabilizable linear and bilinear large-scale systems
NASA Technical Reports Server (NTRS)
Siljak, D. D.; Vukcevic, M. B.
1977-01-01
Two classes of large-scale systems are identified, which can always be stabilized by decentralized feedback control. For the class of systems composed of interconnected linear subsystems, we can choose local controllers for the subsystems to achieve stability of the overall system. The same linear feedback scheme can be used to stabilize a class of linear systems with bilinear interconnections. In this case, however, the scheme is used to establish a finite region of stability for the overall system. The stabilization algorithm is applied to the design of a control system for the Large-Space Telescope.
Electronic Non-Contacting Linear Position Measuring System
Post, Richard F.
2005-06-14
A non-contacting linear position location system employs a special transmission line to encode and transmit magnetic signals to a receiver on the object whose position is to be measured. The invention is useful as a non-contact linear locator of moving objects, e.g., to determine the location of a magnetic-levitation train for the operation of the linear-synchronous motor drive system.
A proposed method for solving fuzzy system of linear equations.
Kargar, Reza; Allahviranloo, Tofigh; Rostami-Malkhalifeh, Mohsen; Jahanshaloo, Gholam Reza
2014-01-01
This paper proposes a new method for solving fuzzy system of linear equations with crisp coefficients matrix and fuzzy or interval right hand side. Some conditions for the existence of a fuzzy or interval solution of m × n linear system are derived and also a practical algorithm is introduced in detail. The method is based on linear programming problem. Finally the applicability of the proposed method is illustrated by some numerical examples.
A Proposed Method for Solving Fuzzy System of Linear Equations
Rostami-Malkhalifeh, Mohsen; Jahanshaloo, Gholam Reza
2014-01-01
This paper proposes a new method for solving fuzzy system of linear equations with crisp coefficients matrix and fuzzy or interval right hand side. Some conditions for the existence of a fuzzy or interval solution of m × n linear system are derived and also a practical algorithm is introduced in detail. The method is based on linear programming problem. Finally the applicability of the proposed method is illustrated by some numerical examples. PMID:25215332
NASA Technical Reports Server (NTRS)
Pilkey, W. D.; Chen, Y. H.
1974-01-01
An indirect synthesis method is used in the efficient optimal design of multi-degree of freedom, multi-design element, nonlinear, transient systems. A limiting performance analysis which requires linear programming for a kinematically linear system is presented. The system is selected using system identification methods such that the designed system responds as closely as possible to the limiting performance. The efficiency is a result of the method avoiding the repetitive systems analyses accompanying other numerical optimization methods.
Processing in (linear) systems with stochastic input
NASA Astrophysics Data System (ADS)
Nutu, Catalin Silviu; Axinte, Tiberiu
2016-12-01
The paper is providing a different approach to real-world systems, such as micro and macro systems of our real life, where the man has little or no influence on the system, either not knowing the rules of the respective system or not knowing the input of the system, being thus mainly only spectator of the system's output. In such a system, the input of the system and the laws ruling the system could be only "guessed", based on intuition or previous knowledge of the analyzer of the respective system. But, as we will see in the paper, it exists also another, more theoretical and hence scientific way to approach the matter of the real-world systems, and this approach is mostly based on the theory related to Schrödinger's equation and the wave function associated with it and quantum mechanics as well. The main results of the paper are regarding the utilization of the Schrödinger's equation and related theory but also of the Quantum mechanics, in modeling real-life and real-world systems.
Linear response theory for open systems: Quantum master equation approach
NASA Astrophysics Data System (ADS)
Ban, Masashi; Kitajima, Sachiko; Arimitsu, Toshihico; Shibata, Fumiaki
2017-02-01
A linear response theory for open quantum systems is formulated by means of the time-local and time-nonlocal quantum master equations, where a relevant quantum system interacts with a thermal reservoir as well as with an external classical field. A linear response function that characterizes how a relaxation process deviates from its intrinsic process by a weak external field is obtained by extracting the linear terms with respect to the external field from the quantum master equation. It consists of four parts. One represents the linear response of a quantum system when system-reservoir correlation at an initial time and correlation between reservoir states at different times are neglected. The others are correction terms due to these effects. The linear response function is compared with the Kubo formula in the usual linear response theory. To investigate the properties of the linear response of an open quantum system, an exactly solvable model for a stochastic dephasing of a two-level system is examined. Furthermore, the method for deriving the linear response function is applied for calculating two-time correlation functions of open quantum systems. It is shown that the quantum regression theorem is not valid for open quantum systems unless their reduced time evolution is Markovian.
[The security system of SIEMENS digital linear accelerator].
Wang, Jianping
2013-03-01
The security system plays an important role to protect the safety of patients and equipment in radiotherapy. The principle and structure of three kinds of security system of the Siemens digital linear accelerator were analyzed with some examples.
Two level optimization of a redundant linear control system
NASA Technical Reports Server (NTRS)
Martin, C. F.; Harding, R. S.
1975-01-01
A linear system with two sets of controls, one primary and the other redundant, is considered. A two level optimization procedure is used to control the system and to maintain maximal availability of the primary control.
Yan, Shengjie; Wu, Xiaomei; Wang, Weiqi
2016-05-01
Purpose In pulmonary veins (PVs) isolation (PVI), radiofrequency (RF) energy is often used to create a linear lesion for blocking the accessory conduction pathways around PVs. By using transient finite element analysis, this study compared the effectiveness of phase-shift mode (PsM) ablation with bipolar mode (BiM) and unipolar mode (UiM) in creating a continuous lesion and lesion depth in a 5-mm thick atrial wall. Materials and methods Computer models were developed to study the temperature distributions and lesion dimensions in atrial walls created through PsM, BiM, and UiM. Four phase-shift angles - 45°, 90°, 135°, and 180° - were considered in PsM ablation (hereafter, PsM-45°, PsM-90°, PsM-135°, and PsM-180°, respectively). Results At 60 s/30 V peak value of RF voltage, UiM and PsM-45° did not create an effective lesion, whereas BiM created a lesion of maximum depth and width approximately 1.01 and 1.62 mm, respectively. PsM-135° and PsM-180° not only created transmural lesions in 5-mm thick atrial walls but also created continuous lesions between electrodes spaced 4 mm apart; similarly, PsM-90° created a continuous lesion with a maximum depth and width of nearly 4.09 and 6.12 mm. Conclusions Compared with UiM and BiM, PsM-90°, PsM-135° and PsM-180° created continuous and larger lesions in a single ablation procedure and at 60 s/30 V peak value of RF voltage. Therefore, the proposed PsM ablation method is suitable for PVI and linear isolation at the left atrial roof for treating atrial fibrillation.
Singular linear-quadratic control problem for systems with linear delay
Sesekin, A. N.
2013-12-18
A singular linear-quadratic optimization problem on the trajectories of non-autonomous linear differential equations with linear delay is considered. The peculiarity of this problem is the fact that this problem has no solution in the class of integrable controls. To ensure the existence of solutions is required to expand the class of controls including controls with impulse components. Dynamical systems with linear delay are used to describe the motion of pantograph from the current collector with electric traction, biology, etc. It should be noted that for practical problems fact singularity criterion of quality is quite commonly occurring, and therefore the study of these problems is surely important. For the problem under discussion optimal programming control contained impulse components at the initial and final moments of time is constructed under certain assumptions on the functional and the right side of the control system.
Hadaeghi, Fatemeh; Hashemi Golpayegani, Mohammad Reza; Murray, Greg
2015-07-07
Bipolar disorder is characterized by repeated erratic episodes of mania and depression, which can be understood as pathological complex system behavior involving cognitive, affective and psychomotor disturbance. In order to illuminate dynamical aspects of the longitudinal course of the illness, we propose here a novel complex model based on the notion of competition between recurrent maps, which mathematically represent the dynamics of activation in excitatory (Glutamatergic) and inhibitory (GABAergic) pathways. We assume that manic and depressive states can be considered stable sub attractors of a dynamical system through which the mood trajectory moves. The model provides a theoretical framework which can account for a number of complex phenomena of bipolar disorder, including intermittent transition between the two poles of the disorder, rapid and ultra-rapid cycling of episodes and manicogenic effects of antidepressants.
Generation of chaotic attractors without equilibria via piecewise linear systems
NASA Astrophysics Data System (ADS)
Escalante-González, R. J.; Campos-Cantón, E.
In this paper, we present a mechanism of generation of a class of switched dynamical system without equilibrium points that generates a chaotic attractor. The switched dynamical systems are based on piecewise linear (PWL) systems. The theoretical results are formally given through a theorem and corollary which give necessary and sufficient conditions to guarantee that a linear affine dynamical system has no equilibria. Numerical results are in accordance with the theory.
Gender differences in thyroid system function: relevance to bipolar disorder and its treatment.
Bauer, Michael; Glenn, Tasha; Pilhatsch, Maximilian; Pfennig, Andrea; Whybrow, Peter C
2014-02-01
Thyroid hormones play a critical role in the functioning of the adult brain, and thyroid diseases impair both mood and cognition. This paper reviews gender differences in thyroid system function that are relevant to the diagnosis and treatment of bipolar disorder. The study comprised a comprehensive literature review of gender differences in thyroid disease that are pertinent to mood disorders. The prevalence of thyroid disease was found to be much higher in females than males, and to increase with age. The most commonly detected abnormality was subclinical hypothyroidism, which was found to occur in up to 20% of postmenopausal women. Females also had higher rates of thyroid autoimmunity. Individuals at risk for thyroid disease, such as adult females, may have had less ability to compensate for additional challenges to thyroid metabolism, including lithium treatment. Thyroid abnormalities were associated with a poorer response to standard treatments for mood disorders. Females with treatment-resistant mood disorders may have responded better than males to adjunctive therapy with thyroid hormones. Disturbances of thyroid system function, which occur commonly in females, may complicate the diagnosis and treatment of mood disorders. In particular, this is clinically relevant during lithium treatment because lithium may impair vital thyroid metabolic pathways secondary to its anti-thyroid activity. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Wang, Shilong; Yin, Changchun; Lin, Jun; Yang, Yu; Hu, Xueyan
2016-03-01
Cooperative work of multiple magnetic transmitting sources is a new trend in the development of transient electromagnetic system. The key is the bipolar current waves shutdown, concurrently in the inductive load. In the past, it was difficult to use the constant clamping voltage technique to realize the synchronized shutdown of currents with different peak values. Based on clamping voltage technique, we introduce a new controlling method with constant shutdown time. We use the rising time to control shutdown time and use low voltage power source to control peak current. From the viewpoint of the circuit energy loss, by taking the high-voltage capacitor bypass resistance and the capacitor of the passive snubber circuit into account, we establish the relationship between the rising time and the shutdown time. Since the switch is not ideal, we propose a new method to test the shutdown time by the low voltage, the high voltage and the peak current. Experimental results show that adjustment of the current rising time can precisely control the value of the clamp voltage. When the rising time is fixed, the shutdown time is unchanged. The error for shutdown time deduced from the energy consumption is less than 6%. The new controlling method on current shutdown proposed in this paper can be used in the cooperative work of borehole and ground transmitting system.
Jiang, Xiaowei; Dai, Xu; Kale Edmiston, Elliot; Zhou, Qian; Xu, Ke; Zhou, Yifang; Wu, Feng; Kong, Lingtao; Wei, Shengnan; Zhou, Yuning; Chang, Miao; Geng, Haiyang; Wang, Dahai; Wang, Ye; Cui, Wenhui; Wang, Fei; Tang, Yanqing
2017-10-15
It is often difficult to differentiate major depressive disorder (MDD) and bipolar disorder (BD) merely according to clinical symptoms. Similarities and differences in neural activity between the two disorders remain unclear. In current study, we use amplitude of low-frequency fluctuations (ALFF) to compare neural activation changes between MDD and BD patients. One hundred and eighty-three adolescents and young adults (57 MDD, 46 BD and 80 healthy controls, HC) were scanned during resting state. The ALFF for each participant was calculated, and were then compared among all groups using voxel-based analysis. There was a significant effect of diagnosis in the core regions of cortico-limbic-striatal neural system. Furthermore, MDD showed left-sided abnormal neural activity while BD showed a bilateral abnormality in this neural system. This study was underpowered to consider medications, mood states and neural developmental effects on the neural activation. Differences in lateralization of ALFF alterations were found. Alterations predominated in the left hemisphere for MDD, whereas alterations were bilateral for BD. Copyright © 2017 Elsevier B.V. All rights reserved.
Lee, Jeong Min; Han, Joon Koo; Kim, Se Hyung; Sohn, Kyu Li; Choi, Seung Hong; Choi, Byung Ihn
2005-04-01
The aim of this study was to investigate the efficacy of bipolar radiofrequency ablation (RFA) with the open-perfused electrode and cooled-wet electrode. Bipolar RF was applied for 20 min to the ex vivo bovine liver using either the Berchtold system with two 16-gauge open-perfused electrodes (group A, n=15) or the Radionics system with two 15-gauge cooled-wet electrodes (group B, n=15). In both groups, two electrodes were placed 3 cm apart. The ablation zone was created by the RF energy delivered together with the infusion of 5% hypertonic saline (2 ml/min). The dimension of the ablation zone, its shape and the changes in the impedance and W s of two groups during the RFA were examined and documented. The vertical diameter (Dv) along the probe, the long-axis diameter (Dl) perpendicular to the Dv in the longitudinal plane and the short-axis diameter of the ablation zone (Ds) in the transverse plane through the midpoint between the tips of two probes were measured. The mean accumulated energy output in the Radionics system was higher than in the Berchtold system (159,887.0+/-36,423 W s vs. 87,555.1+/-86,787 W s). The difference was statistically significant (P<0.05). In group A, the impedance intermittently rose to above 700 Omega during the RFA in all sessions, which led to a gradual decrease of the power output to lower than 30 W. In group B, on the other hand, the impedance did not change markedly. The mean Dv value of the coagulation necrosis in group B was significantly longer than in group A (5.0+/-0.4 cm vs. 4.3+/-0.6 cm, P<0.05). The mean Dl and Ds were 6.7+/-0.5 cm and 5.0+/-0.8 cm in group A, and 6.5+/-0.8 cm and 5.5+/-0.7 cm in group B, respectively (P>0.05). The data demonstrate that the cooled-wet electrode generates the more spherical ablation zone than the open-perfused electrode. With approximately doubled power output, the bipolar RFA with the cooled-wet electrodes induces a larger volume of tissue coagulation than with the open-perfused electrodes.
A linear quadratic regulator approach to the stabilization of uncertain linear systems
NASA Technical Reports Server (NTRS)
Shieh, L. S.; Sunkel, J. W.; Wang, Y. J.
1990-01-01
This paper presents a linear quadratic regulator approach to the stabilization of uncertain linear systems. The uncertain systems under consideration are described by state equations with the presence of time-varying unknown-but-bounded uncertainty matrices. The method is based on linear quadratic regulator (LQR) theory and Liapunov stability theory. The robust stabilizing control law for a given uncertain system can be easily constructed from the symmetric positive-definite solution of the associated augmented Riccati equation. The proposed approach can be applied to matched and/or mismatched systems with uncertainty matrices in which only their matrix norms are bounded by some prescribed values and/or their entries are bounded by some prescribed constraint sets. Several numerical examples are presented to illustrate the results.
Output Synchronization of Nonidentical Linear Multiagent Systems.
Wu, Yuanqing; Su, Hongye; Shi, Peng; Lu, Renquan; Wu, Zheng-Guang
2017-01-01
In this paper, the problem of output synchronization is investigated for the heterogeneous network with an uncertain leader. It is assumed that parameter perturbations influence the nonidentical linear agents, whose outputs are controlled to track the output of an uncertain leader. Based on the hierarchical structure of the communication graph, a novel control scheme is proposed to guarantee the output synchronization. As there exist parameter uncertainties in the models of the agents, the internal model principle is used to gain robustness versus plant parameter uncertainties. Furthermore, as the precise model of the leader is also not available, the adaptive control principle is adopted to tune the parameters in the local controllers. The developed new technique is able to simultaneously handle uncertainties in the follower parameters as well as the leader parameters. The agents in the upper layers will be treated as the exosystems of the agents in the lower layers. The local controllers are constructed in a sequential order. It is shown that the output synchronization can be achieved globally asymptotically and locally exponentially. Finally, a simulation example is given to illustrate the effectiveness and potential of the theoretic results obtained.
On Optimal Feedback Control for Stationary Linear Systems
Russell, David L.
2010-04-15
We study linear-quadratic optimal control problems for finite dimensional stationary linear systems AX+BU=Z with output Y=CX+DU from the viewpoint of linear feedback solution. We interpret solutions in relation to system robustness with respect to disturbances Z and relate them to nonlinear matrix equations of Riccati type and eigenvalue-eigenvector problems for the corresponding Hamiltonian system. Examples are included along with an indication of extensions to continuous, i.e., infinite dimensional, systems, primarily of elliptic type.
Virtual Estimator for Piecewise Linear Systems Based on Observability Analysis
Morales-Morales, Cornelio; Adam-Medina, Manuel; Cervantes, Ilse; Vela-Valdés and, Luis G.; García Beltrán, Carlos Daniel
2013-01-01
This article proposes a virtual sensor for piecewise linear systems based on observability analysis that is in function of a commutation law related with the system's outpu. This virtual sensor is also known as a state estimator. Besides, it presents a detector of active mode when the commutation sequences of each linear subsystem are arbitrary and unknown. For the previous, this article proposes a set of virtual estimators that discern the commutation paths of the system and allow estimating their output. In this work a methodology in order to test the observability for piecewise linear systems with discrete time is proposed. An academic example is presented to show the obtained results. PMID:23447007
McKenna, Benjamin S; Eyler, Lisa T
2013-01-01
Prefrontal cortex (PFC) mediated cognitive and emotional processing deficits in bipolar disorder lead to functional limitations even during periods of mood stability. Alterations of sleep and circadian functioning are well-documented in bipolar disorder, but there is little research directly examining the mechanistic role of sleep and/or circadian rhythms in the observed cognitive and emotional processing deficits. We systematically review the cognitive and emotional processing deficits reliant upon PFC functioning of euthymic patients with bipolar disorder and in healthy individuals deprived of sleep. The evidence from two parallel lines of investigation suggests that sleep and circadian rhythms may be involved in the cognitive and emotional processing deficits seen in bipolar disorder through overlapping neurobiological systems. We discuss current models of bipolar highlighting the PFC-limbic connections and discuss inclusion of sleep-related mechanisms. Sleep and circadian dysfunction is a core feature of bipolar disorder and models of neurobiological abnormalities should incorporate chronobiological measures. Further research into the role of sleep and circadian rhythms in cognition and emotional processing in bipolar disorder is warranted. PMID:22926687
Fears, Scott C.; Service, Susan K.; Kremeyer, Barbara; Araya, Carmen; Araya, Xinia; Bejarano, Julio; Ramirez, Margarita; Castrillón, Gabriel; Gomez-Franco, Juliana; Lopez, Maria C.; Montoya, Gabriel; Montoya, Patricia; Aldana, Ileana; Teshiba, Terri M.; Abaryan, Zvart; Al-Sharif, Noor B.; Ericson, Marissa; Jalbrzikowski, Maria; Luykx, Jurjen J.; Navarro, Linda; Tishler, Todd A.; Altshuler, Lori; Bartzokis, George; Escobar, Javier; Glahn, David C.; Ospina-Duque, Jorge; Risch, Neil; Ruiz-Linares, Andrés; Thompson, Paul M.; Cantor, Rita M.; Lopez-Jaramillo, Carlos; Macaya, Gabriel; Molina, Julio; Reus, Victor I.; Sabatti, Chiara; Freimer, Nelson B.; Bearden, Carrie E.
2014-01-01
IMPORTANCE Genetic factors contribute to risk for bipolar disorder (BP), yet its pathogenesis remains poorly understood. A focus on measuring multi-system quantitative traits that may be components of BP psychopathology may enable genetic dissection of this complex disorder, and investigation of extended pedigrees from genetically isolated populations may facilitate the detection of specific genetic variants that impact on BP as well as its component phenotypes. OBJECTIVE To identify quantitative neurocognitive, temperament-related, and neuroanatomic phenotypes that appear heritable and associated with severe bipolar disorder (BP-I), and therefore suitable for genetic linkage and association studies aimed at identifying variants contributing to BP-I risk. DESIGN Multi-generational pedigree study in two closely related, genetically isolated populations: the Central Valley of Costa Rica (CVCR) and Antioquia, Colombia (ANT). PARTICIPANTS 738 individuals, all from CVCR and ANT pedigrees, of whom 181 are affected with BP-I. MAIN OUTCOME MEASURE Familial aggregation (heritability) and association with BP-I of 169 quantitative neurocognitive, temperament, magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) phenotypes. RESULTS Seventy-five percent (126) of the phenotypes investigated were significantly heritable, and 31% (53) were associated with BP-I. About 1/4 of the phenotypes, including measures from each phenotype domain, were both heritable and associated with BP-I. Neuroimaging phenotypes, particularly cortical thickness in prefrontal and temporal regions, and volume and microstructural integrity of the corpus callosum, represented the most promising candidate traits for genetic mapping related to BP based on strong heritability and association with disease. Analyses of phenotypic and genetic covariation identified substantial correlations among the traits, at least some of which share a common underlying genetic architecture. CONCLUSIONS AND
... clear cause for the periods (episodes) of extreme happiness and high activity or energy (mania) or depression ... A.D.A.M. Editorial team. Related MedlinePlus Health Topics Bipolar Disorder Browse the Encyclopedia A.D. ...
Kaun, Thomas D.
1992-01-01
A bipolar battery having a plurality of cells. The bipolar battery includes: a negative electrode; a positive electrode and a separator element disposed between the negative electrode and the positive electrode, the separator element electrically insulating the electrodes from one another; an electrolyte disposed within at least one of the negative electrode, the positive electrode and the separator element; and an electrode containment structure including a cup-like electrode holder.
Bipolar-power-transistor-based limiter for high frequency ultrasound imaging systems.
Choi, Hojong; Yang, Hao-Chung; Shung, K Kirk
2014-03-01
High performance limiters are described in this paper for applications in high frequency ultrasound imaging systems. Limiters protect the ultrasound receiver from the high voltage (HV) spikes produced by the transmitter. We present a new bipolar power transistor (BPT) configuration and compare its design and performance to a diode limiter used in traditional ultrasound research and one commercially available limiter. Limiter performance depends greatly on the insertion loss (IL), total harmonic distortion (THD) and response time (RT), each of which will be evaluated in all the limiters. The results indicated that, compared with commercial limiter, BPT-based limiter had less IL (-7.7 dB), THD (-74.6 dB) and lower RT (43 ns) at 100 MHz. To evaluate the capability of these limiters, they were connected to a 100 MHz single element transducer and a two-way pulse-echo test was performed. It was found that the -6 dB bandwidth and sensitivity of the transducer using BPT-based limiter were better than those of the commercial limiter by 22% and 140%, respectively. Compared to the commercial limiter, BPT-based limiter is shown to be capable of minimizing signal attenuation, RT and THD at high frequencies and is thus suited for high frequency ultrasound applications.
Bipolar-power-transistor-based limiter for high frequency ultrasound imaging systems
Choi, Hojong; Yang, Hao-Chung; Shung, K. Kirk
2013-01-01
High performance limiters are described in this paper for applications in high frequency ultrasound imaging systems. Limiters protect the ultrasound receiver from the high voltage (HV) spikes produced by the transmitter. We present a new bipolar power transistor (BPT) configuration and compare its design and performance to a diode limiter used in traditional ultrasound research and one commercially available limiter. Limiter performance depends greatly on the insertion loss (IL), total harmonic distortion (THD) and response time (RT), each of which will be evaluated in all the limiters. The results indicated that, compared with commercial limiter, BPT-based limiter had less IL (–7.7 dB), THD (–74.6 dB) and lower RT (43 ns) at 100MHz. To evaluate the capability of these limiters, they were connected to a 100 MHz single element transducer and a two-way pulse-echo test was performed. It was found that the -6 dB bandwidth and sensitivity of the transducer using BPT-based limiter were better than those of the commercial limiter by 22 % and 140 %, respectively. Compared to the commercial limiter, BPT-based limiter is shown to be capable of minimizing signal attenuation, RT and THD at high frequencies and is thus suited for high frequency ultrasound applications. PMID:24199954
Numerical methods for control optimization in linear systems
NASA Astrophysics Data System (ADS)
Tyatyushkin, A. I.
2015-05-01
Numerical methods are considered for solving optimal control problems in linear systems, namely, terminal control problems with control and phase constraints and time-optimal control problems. Several algorithms with various computer storage requirements are proposed for solving these problems. The algorithms are intended for finding an optimal control in linear systems having certain features, for example, when the reachable set of a system has flat faces.
Complex modes and solvability of nonclassical linear systems
NASA Astrophysics Data System (ADS)
Caughey, T. K.; Ma, F.
1993-03-01
Some basic properties of nonclassical linear systems are examined to determine necessary and sufficient conditions under which nonclassical linear systems can be decoupled or become solvable in n-space. It was found that a necessary and sufficient condition under which a nonclassical system can be decoupled is for the coefficient matrices M, C, and K (where M is the mass matrix, C is the damping matrix, and K is the stiffness matrix) to be diagonalizable and pairwise commutative.
Linear decentralized systems with special structure. [for twin lift helicopters
NASA Technical Reports Server (NTRS)
Martin, C. F.
1982-01-01
Certain fundamental structures associated with linear systems having internal symmetries are outlined. It is shown that the theory of finite-dimensional algebras and their representations are closely related to such systems. It is also demonstrated that certain problems in the decentralized control of symmetric systems are equivalent to long-standing problems of linear systems theory. Even though the structure imposed arose in considering the problems of twin-lift helicopters, any large system composed of several identical intercoupled control systems can be modeled by a linear system that satisfies the constraints imposed. Internal symmetry can be exploited to yield new system-theoretic invariants and a better understanding of the way in which the underlying structure affects overall system performance.
Response characteristics and receptive field widths of on-bipolar cells in the mouse retina
Berntson, Amy; Taylor, W Rowland
2000-01-01
Voltage-clamp and current-clamp recordings were made from bipolar cells in dark-adapted mouse retinal slices. Light-evoked responses fell into three groups corresponding to the rod bipolar cells, on-cone bipolar cells and off-cone bipolar cells. The morphology of the recorded cells confirmed this classification. Intensity-response relations were well fitted by a Michaelis saturation function with Hill coefficients of 1.15 ± 0.11 (n = 6) for rod bipolar cells and 2.33 ± 0.06 (n = 4) for cone inputs onto on-cone bipolar cells. In the absence of antagonists for GABA or glycine receptors, light-evoked synaptic currents for all cells displayed linear current-voltage relations that reversed near 0 mV, indicating that very little inhibition was activated under dark-adapted recording conditions. Saturating light stimuli evoked conductances of 0.81 ± 0.56 nS (n = 4) in rod bipolar cells and 1.1 ± 0.8 nS (n = 4) in on-cone bipolar cells. Receptive field widths were estimated by flashing a vertical light bar at various locations along the slice. Rod and on-cone bipolar cells had receptive field widths of 67 ± 16 μm (n = 6) and 43 ± 7 μm (n = 5), respectively. The maximum spatial resolution of an array of such cone bipolar cells was estimated to be 0.3 cycles deg−1, compared with a maximum resolution of 0.5 cycles deg−1 obtained from behavioural studies in mice. Our results suggest that this limit to spatial resolution could be imposed early in the visual system by the size of the bipolar cell receptive fields. PMID:10790165
Bergé, Matthieu; Campagne, Sébastien; Mignolet, Johann; Holden, Seamus; Théraulaz, Laurence; Manley, Suliana; Allain, Frédéric H-T; Viollier, Patrick H
2016-01-01
Although free-living and obligate intracellular bacteria are both polarized it is unclear whether the underlying polarization mechanisms and effector proteins are conserved. Here we dissect at the cytological, functional and structural level a conserved polarization module from the free living α-proteobacterium Caulobacter crescentus and an orthologous system from an obligate intracellular (rickettsial) pathogen. The NMR solution structure of the zinc-finger (ZnR) domain from the bifunctional and bipolar ZitP pilus assembly/motility regulator revealed conserved interaction determinants for PopZ, a bipolar matrix protein that anchors the ParB centromere-binding protein and other regulatory factors at the poles. We show that ZitP regulates cytokinesis and the localization of ParB and PopZ, targeting PopZ independently of the previously known binding sites for its client proteins. Through heterologous localization assays with rickettsial ZitP and PopZ orthologs, we document the shared ancestries, activities and structural determinants of a (bi-)polarization system encoded in free-living and obligate intracellular α-proteobacteria. DOI: http://dx.doi.org/10.7554/eLife.20640.001 PMID:28008852
Capacities of linear quantum optical systems
NASA Astrophysics Data System (ADS)
Lupo, Cosmo; Giovannetti, Vittorio; Pirandola, Stefano; Mancini, Stefano; Lloyd, Seth
2012-06-01
A wide variety of communication channels employ the quantized electromagnetic field to convey information. Their communication capacity crucially depends on losses associated to spatial characteristics of the channel such as diffraction and antenna design. Here we focus on the communication via a finite pupil, showing that diffraction is formally described as a memory channel. By exploiting this equivalence we then compute the communication capacity of an optical refocusing system, modeled as a converging lens. Even though loss of information originates from the finite pupil of the lens, we show that the presence of the refocusing system can substantially enhance the communication capacity. We mainly concentrate on communication of classical information, the extension to quantum information being straightforward.
The case for unified linear reference system
Espinoza, J. Jr.; Mackoy, R.D.; Fletcher, D.R.
1997-06-01
The transportation industry distinguishes its activities and data into three functionally and institutionally distinct domains. Transportation infrastructure management activities make transport links (e.g., roads, rail lines, transit routes) available for travel. In contrast, civilian and military transport operations focus on finding and using the best transport links. Each of these three transportation interest groups - transportation facility operators, civilian and military transportation users - currently collects and maintains separate, often redundant or inconsistent information concerning the location and status of the transportation system, the vehicles using the system, and the passengers and freight (or material) being conveyed. Although there has been some progress made in integrating data within each domain, little emphasis has been placed on identifying and improving the flow of information between them. Because activities initiated in one domain affect conditions in the others, defining these flows is crucial to the next generation of planners, traffic managers and customers of transportation services. For example, construction and maintenance activities affect civilian and military route choices and travel times; large scale military movements disrupt civilian travel and have potentially major effects on the infrastructure and so on. This intertwined interest in the transportation system implies the need for data integration not only within each sphere of interest but among the spheres as well. Although recent policy statements by the U.S. Departments of Transportation and Defense and ITS America indicate a desire to combine and share information resources, there are enormous technical and institutional barriers that need to be overcome.
Feedback linearizing control of a MIMO power system
NASA Astrophysics Data System (ADS)
Ilyes, Laszlo
Prior research has demonstrated that either the mechanical or electrical subsystem of a synchronous electric generator may be controlled using single-input single-output (SISO) nonlinear feedback linearization. This research suggests a new approach which applies nonlinear feedback linearization to a multi-input multi-output (MIMO) model of the synchronous electric generator connected to an infinite bus load model. In this way, the electrical and mechanical subsystems may be linearized and simultaneously decoupled through the introduction of a pair of auxiliary inputs. This allows well known, linear, SISO control methods to be effectively applied to the resulting systems. The derivation of the feedback linearizing control law is presented in detail, including a discussion on the use of symbolic math processing as a development tool. The linearizing and decoupling properties of the control law are validated through simulation. And finally, the robustness of the control law is demonstrated.
Decoupling in linear time-varying multivariable systems
NASA Technical Reports Server (NTRS)
Sankaran, V.
1973-01-01
The necessary and sufficient conditions for the decoupling of an m-input, m-output, linear time varying dynamical system by state variable feedback is described. The class of feedback matrices which decouple the system are illustrated. Systems which do not satisfy these results are described and systems with disturbances are considered. Some examples are illustrated to clarify the results.
Eiring, Øystein; Nytrøen, Kari; Kienlin, Simone; Khodambashi, Soudabeh; Nylenna, Magne
2017-07-10
People with bipolar disorder often experience ill health and have considerably reduced life expectancies. Suboptimal treatment is common and includes a lack of effective medicines, overtreatment, and non-adherence to medical interventions and lifestyle measures. E- and m-health applications support patients in optimizing their treatment but often exhibit conceptual and technical shortcomings. The objective of this work was to develop and test the usability of a system targeting suboptimal treatment and compare the service to other genres and strategies. Based on the frameworks of shared decision-making, multi-criteria decision analysis, and single-subject research design, we interviewed potential users, reviewed research and current approaches, and created a first version using a rapid prototyping framework. We then iteratively improved and expanded the service based on formative usability testing with patients, healthcare providers, and laypeople from Norway, the UK, and Ukraine. The evidence-based health-optimization system was developed using systematic methods. The System Usability Scale and a questionnaire were administered in formative and summative tests. A comparison of the system to current standards for clinical practice guidelines and patient decision aids was performed. Seventy-eight potential users identified 82 issues. Driven by user feedback, the limited first version was developed into a more comprehensive system. The current version encompasses 21 integrated core features, supporting 6 health-optimization strategies. One crucial feature enables patients and clinicians to explore the likely value of treatments based on mathematical integration of self-reported and research data and the patient's preferences. The mean ± SD (median) system usability score of the patient-oriented subsystem was 71 ± 18 (73). The mean ± SD (median) system usability score in the summative usability testing was 78 ± 18 (75), well above the norm score of
... Loss Surgery? A Week of Healthy Breakfasts Shyness Bipolar Disorder KidsHealth > For Teens > Bipolar Disorder A A A ... Bipolar Disorder en español Trastorno bipolar What Is Bipolar Disorder? Bipolar disorders are one of several medical conditions ...
Decentralization, stabilization, and estimation of large-scale linear systems
NASA Technical Reports Server (NTRS)
Siljak, D. D.; Vukcevic, M. B.
1976-01-01
In this short paper we consider three closely related aspects of large-scale systems: decentralization, stabilization, and estimation. A method is proposed to decompose a large linear system into a number of interconnected subsystems with decentralized (scalar) inputs or outputs. The procedure is preliminary to the hierarchic stabilization and estimation of linear systems and is performed on the subsystem level. A multilevel control scheme based upon the decomposition-aggregation method is developed for stabilization of input-decentralized linear systems Local linear feedback controllers are used to stabilize each decoupled subsystem, while global linear feedback controllers are utilized to minimize the coupling effect among the subsystems. Systems stabilized by the method have a tolerance to a wide class of nonlinearities in subsystem coupling and high reliability with respect to structural perturbations. The proposed output-decentralization and stabilization schemes can be used directly to construct asymptotic state estimators for large linear systems on the subsystem level. The problem of dimensionality is resolved by constructing a number of low-order estimators, thus avoiding a design of a single estimator for the overall system.
Perfect commuting-operator strategies for linear system games
NASA Astrophysics Data System (ADS)
Cleve, Richard; Liu, Li; Slofstra, William
2017-01-01
Linear system games are a generalization of Mermin's magic square game introduced by Cleve and Mittal. They show that perfect strategies for linear system games in the tensor-product model of entanglement correspond to finite-dimensional operator solutions of a certain set of non-commutative equations. We investigate linear system games in the commuting-operator model of entanglement, where Alice and Bob's measurement operators act on a joint Hilbert space, and Alice's operators must commute with Bob's operators. We show that perfect strategies in this model correspond to possibly infinite-dimensional operator solutions of the non-commutative equations. The proof is based around a finitely presented group associated with the linear system which arises from the non-commutative equations.
Kaminaka, Chikako; Uede, Mikiko; Matsunaka, Hiroshi; Furukawa, Fukumi; Yamamoto, Yuki
2015-06-01
Few clinical studies have examined the utility of bipolar fractional radiofrequency (FRF) therapy as a treatment for atrophic acne scars and active acne in people with darker skin. This study was designed to compare the safety and efficacy of bipolar FRF therapy as a treatment for atrophic acne scars and acne vulgaris. Twenty-three Japanese patients with atrophic acne scars and mild to severe acne on both cheeks were treated with a bipolar FRF system (eMatrix; Syneron, Yokneam Illit, Israel). Five treatment sessions were carried out at 1-month intervals, and the patients were followed up for 3 months after the final treatment. Assessments of scar severity and the number of acne lesions and 3-D in vivo imaging analysis were performed. Evaluations of the treatment outcomes and their effects on the patients' quality of life (QOL) were also carried out. We demonstrated that the improvement in scar volume was marked in the patients with mild scars and was at least moderate in 23 (57.5%) of the treated areas. With regard to the number of acne lesions, the treated areas exhibited significantly fewer lesions compared with the baseline at each time point (P < 0.05). The patients' assessments of the treatment outcomes and their QOL indicated that both had improved significantly by the end of the study. Furthermore, significant reductions in the patients' sebum levels, skin roughness and scar depth were observed. Bipolar FRF treatment significantly improved the atrophic acne scars and acne of Japanese patients and had minimal side-effects. © 2015 Japanese Dermatological Association.
Complexity of Dense Linear System Solution on a Multiprocessor Ring.
1985-01-01
Lawrie and Sameh [4] present a technique for solving symmetric positive definite banded systems, which is a generalization of a method for tridiagonal...Numerical Linear Algebra, SIAM Review. 20 (1978), pp. 740-777. [4] D. Lawrie, A.H. Sameh , The Computation and Communication Complexity of a Parallel Banded...409. [7] , Parallel, Iterative Solution of Sparse Linear Systems : Models and Architectures. Technical Report 84-35, ICASE, 1984. (81 A.H. Sameh , On
Iterative algorithms for large sparse linear systems on parallel computers
NASA Technical Reports Server (NTRS)
Adams, L. M.
1982-01-01
Algorithms for assembling in parallel the sparse system of linear equations that result from finite difference or finite element discretizations of elliptic partial differential equations, such as those that arise in structural engineering are developed. Parallel linear stationary iterative algorithms and parallel preconditioned conjugate gradient algorithms are developed for solving these systems. In addition, a model for comparing parallel algorithms on array architectures is developed and results of this model for the algorithms are given.
Goodwin, Frederick K.; Ghaemi, S. Nassir
1999-01-01
Bipolar disorder's unique combination of three characteristics - clear genetic diathesis, distinctive clinical features, early availability of an effective treatment (lithium) - explains its special place in the history of psychiatry and its contribution to the current explosive growth of neuroscience. This article looks at the state of the art in bipolar disorder from the vantage point of: (i) genetics (possible linkages on chromosomes 18 and 21q, polygenic hypothesis, research into genetic markers); (ii) diagnosis (new focus on the subjective aspects of bipolar disorder to offset the current trend of underdiagnosis due to overreliance on standardized interviews and rating scales); (iii) outcome (increase in treatment-resistant forms signaling a change in the natural history of bipolar disorder); (iv) pathophysiology (research into circadian biological rhythms and the kindling hypothesis to explain recurrence); (v) treatment (emergence of the anticonvulsants, suggested role of chronic antidepressant treatment in the development of treatment resistance); (vi) neurobiology (evaluation of regulatory function in relation to affective disturbances, role of postsynaptic second-messenger mechanisms, advances in functional neuroimaging); and (vii) psychosocial research (shedding overly dualistic theories of the past to understand the mind and brain as an entity, thus emphasizing the importance of balancing the psychopharmacological and psychotherapeutic approaches). Future progress in the understanding and treatment of bipolar disorder will rely on successful integration of the biological and psychosocial lines of investigation. PMID:22033232
Solution of generalized shifted linear systems with complex symmetric matrices
NASA Astrophysics Data System (ADS)
Sogabe, Tomohiro; Hoshi, Takeo; Zhang, Shao-Liang; Fujiwara, Takeo
2012-07-01
We develop the shifted COCG method [R. Takayama, T. Hoshi, T. Sogabe, S.-L. Zhang, T. Fujiwara, Linear algebraic calculation of Green's function for large-scale electronic structure theory, Phys. Rev. B 73 (165108) (2006) 1-9] and the shifted WQMR method [T. Sogabe, T. Hoshi, S.-L. Zhang, T. Fujiwara, On a weighted quasi-residual minimization strategy of the QMR method for solving complex symmetric shifted linear systems, Electron. Trans. Numer. Anal. 31 (2008) 126-140] for solving generalized shifted linear systems with complex symmetric matrices that arise from the electronic structure theory. The complex symmetric Lanczos process with a suitable bilinear form plays an important role in the development of the methods. The numerical examples indicate that the methods are highly attractive when the inner linear systems can efficiently be solved.
Recursive inversion of externally defined linear systems by FIR filters
NASA Technical Reports Server (NTRS)
Bach, Ralph E., Jr.; Baram, Yoram
1989-01-01
The approximate inversion of an internally unknown linear system, given by its impulse response sequence, by an inverse system having a finite impulse response, is considered. The recursive least-squares procedure is shown to have an exact initialization, based on the triangular Toeplitz structure of the matrix involved. The proposed approach also suggests solutions to the problem of system identification and compensation.
Recursive inversion of externally defined linear systems by FIR filters
NASA Technical Reports Server (NTRS)
Bach, Ralph E., Jr.; Baram, Yoram
1989-01-01
The approximate inversion of an internally unknown linear system, given by its impulse response sequence, by an inverse system having a finite impulse response, is considered. The recursive least-squares procedure is shown to have an exact initialization, based on the triangular Toeplitz structure of the matrix involved. The proposed approach also suggests solutions to the problem of system identification and compensation.
Equi-surjective systems of linear operators and applications
NASA Astrophysics Data System (ADS)
Luc, D. T.; Minh, N. B.
2008-01-01
In this paper we study a system of linear operators between finite-dimensional Euclidean spaces. Emphasis is made on unbounded systems and sufficient conditions are established for their equi-surjectivity. An application is presented in which a system of approximate Jacobian matrices is used to obtain a parametric interior mapping theorem. A multiplier rule for vector problems is also derived.
Exact linearization of the radiation-damped spin system
Rourke; Augustine
2000-02-21
Nonlinear evolution of the Landau-Lifshitz type can be exactly linearized. Special cases include the radiation-damped spin system and the superradiant system in the semiclassical regime, in the presence of time-varying driving fields. For these, the resultant linear system is simply that of a spin 1 / 2 particle, with the radiation damping rate, or superradiant characteristic time, manifested as an imaginary addition to the spin's resonance frequency. Consequently, methods from inverse scattering theory can be used to design driving fields. The behavior of these systems under stochastic excitation can be determined exactly.
Development of a portable wireless system for bipolar concentric ECG recording
NASA Astrophysics Data System (ADS)
Prats-Boluda, G.; Ye-Lin, Y.; Bueno Barrachina, J. M.; Senent, E.; Rodriguez de Sanabria, R.; Garcia-Casado, J.
2015-07-01
Cardiovascular diseases (CVDs) remain the biggest cause of deaths worldwide. ECG monitoring is a key tool for early diagnosis of CVDs. Conventional monitors use monopolar electrodes resulting in poor spatial resolution surface recordings and requiring extensive wiring. High-spatial resolution surface electrocardiographic recordings provide valuable information for the diagnosis of a wide range of cardiac abnormalities, including infarction and arrhythmia. The aim of this work was to develop and test a wireless recording system for acquiring high spatial resolution ECG signals, based on a flexible tripolar concentric electrode (TCE) without cable wiring or external reference electrode which would make more comnfortable its use in clinical practice. For this, a portable, wireless sensor node for analogue conditioning, digitalization and transmission of a bipolar concentric ECG signal (BC-ECG) using a TCE and a Mason-likar Lead-I ECG (ML-Lead-I ECG) signal was developed. Experimental results from a total of 32 healthy volunteers showed that the ECG fiducial points in the BC-ECG signals, recorded with external and internal reference electrode, are consistent with those of simultaneous ML-Lead-I ECG. No statistically significant difference was found in either signal amplitude or morphology, regardless of the reference electrode used, being the signal-to-noise similar to that of ML-Lead-I ECG. Furthermore, it has been observed that BC-ECG signals contain information that could not available in conventional records, specially related to atria activity. The proposed wireless sensor node provides non-invasive high-local resolution ECG signals using only a TCE without additional wiring, which would have great potential in medical diagnosis of diseases such as atrial or ventricular fibrillations or arrhythmias that currently require invasive diagnostic procedures (catheterization).
Alloy, Lauren B.; Bender, Rachel E.; Whitehouse, Wayne G.; Wagner, Clara A.; Liu, Richard T.; Grant, David A.; Jager-Hyman, Shari; Molz, Ashleigh; Choi, James Y.; Harmon-Jones, Eddie; Abramson, Lyn Y.
2012-01-01
A prospective, behavioral high-risk design provided a theoretically guided examination of vulnerability to first onset of bipolar spectrum disorder based on the Behavioral Approach System (BAS) model. Adolescents (ages 14–19) at an “age of risk” for bipolar disorder onset were screened on BAS sensitivity by interviewers blind to current symptoms, lifetime history, and family history of psychopathology. Participants were selected with high versus moderate levels of BAS sensitivity and administered a lifetime diagnostic interview. Those with a bipolar spectrum disorder, psychosis, or hypomanic episode with onset prior to the BAS sensitivity assessment were excluded. High BAS (n = 171) and Moderate BAS (n = 119) sensitivity participants in the final sample completed baseline measures of symptoms, goal-setting, and reward responsiveness and were followed prospectively with semistructured diagnostic interviews every 6 months. Consistent with the vulnerability hypothesis of the BAS model of bipolar disorder, high BAS participants had a greater likelihood, and shorter time to onset, of bipolar spectrum disorder than moderate BAS participants across an average of 12.8 months of follow-up (12.9% vs. 4.2%), controlling for baseline depressive and hypomanic symptoms, and family history of bipolar disorder. High reward responsiveness on a behavioral task and ambitious goal-striving for popular fame and financial success (but not impulsivity) also predicted first onset of bipolar spectrum disorder controlling for the covariates and BAS risk group, and ambitious goal-striving partially mediated the BAS risk group effect. We discuss implications of the findings for the BAS model of bipolar disorder and early intervention efforts. PMID:22004113
Modal interaction in linear dynamic systems near degenerate modes
NASA Technical Reports Server (NTRS)
Afolabi, D.
1991-01-01
In various problems in structural dynamics, the eigenvalues of a linear system depend on a characteristic parameter of the system. Under certain conditions, two eigenvalues of the system approach each other as the characteristic parameter is varied, leading to modal interaction. In a system with conservative coupling, the two eigenvalues eventually repel each other, leading to the curve veering effect. In a system with nonconservative coupling, the eigenvalues continue to attract each other, eventually colliding, leading to eigenvalue degeneracy. Modal interaction is studied in linear systems with conservative and nonconservative coupling using singularity theory, sometimes known as catastrophe theory. The main result is this: eigenvalue degeneracy is a cause of instability; in systems with conservative coupling, it induces only geometric instability, whereas in systems with nonconservative coupling, eigenvalue degeneracy induces both geometric and elastic instability. Illustrative examples of mechanical systems are given.
Dynamic modeling of electrochemical systems using linear graph theory
NASA Astrophysics Data System (ADS)
Dao, Thanh-Son; McPhee, John
An electrochemical cell is a multidisciplinary system which involves complex chemical, electrical, and thermodynamical processes. The primary objective of this paper is to develop a linear graph-theoretical modeling for the dynamic description of electrochemical systems through the representation of the system topologies. After a brief introduction to the topic and a review of linear graphs, an approach to develop linear graphs for electrochemical systems using a circuitry representation is discussed, followed in turn by the use of the branch and chord transformation techniques to generate final dynamic equations governing the system. As an example, the application of linear graph theory to modeling a nickel metal hydride (NiMH) battery will be presented. Results show that not only the number of equations are reduced significantly, but also the linear graph model simulates faster compared to the original lumped parameter model. The approach presented in this paper can be extended to modeling complex systems such as an electric or hybrid electric vehicle where a battery pack is interconnected with other components in many different domains.
Switching control of linear systems subject to asymmetric actuator saturation
NASA Astrophysics Data System (ADS)
Yuan, Chengzhi; Wu, Fen
2015-01-01
In this paper, we study the saturation control problem for linear time-invariant (LTI) systems subject to asymmetric actuator saturation under a switching control framework. The LTI plant with asymmetric saturation is first transformed to an equivalent switched linear model with each subsystem subject to symmetric actuator saturation, based on which a dwell-time switching controller augmented with a controller state reset is then developed by using multiple Lyapunov functions. The controller synthesis conditions are formulated as linear matrix inequalities (LMIs), which can be solved efficiently. Simulation results are also included to illustrate the effectiveness and advantages of the proposed approach.
Robust H∞ state-feedback control for linear systems.
Chen, Hao; Zhang, Zhenzhen; Wang, Huazhang
2017-04-01
This paper investigates the problem of robust H∞ control for linear systems. First, the state-feedback closed-loop control algorithm is designed. Second, by employing the geometric progression theory, a modified augmented Lyapunov-Krasovskii functional (LKF) with the geometric integral interval is established. Then, parameter uncertainties and the derivative of the delay are flexibly described by introducing the convex combination skill. This technique can eliminate the unnecessary enlargement of the LKF derivative estimation, which gives less conservatism. In addition, the designed controller can ensure that the linear systems are globally asymptotically stable with a guaranteed H∞ performance in the presence of a disturbance input and parameter uncertainties. A liquid monopropellant rocket motor with a pressure feeding system is evaluated in a simulation example. It shows that this proposed state-feedback control approach achieves the expected results for linear systems in the sense of the prescribed H∞ performance.
Linear adaptive control of a single-tether system
NASA Technical Reports Server (NTRS)
Greene, M. E.; Carter, J. T.; Walls, J. L.
1992-01-01
A control law for a single-tether orbiting satellite system based on a reduced order linear adaptive control technique is presented. The main advantages of this technique are its design simplicity and the facts that specific system parameters and model linearization are not required when designing the controller. Two controllers are developed: one which uses only tension in the tether as control actuation and one which uses both tension and in-plane thrusters as control actuation. Both a sixth-order nonlinear and an 11th-order bead model of a tethered satellite system are used for simulation purposes, demonstrating the ability of the controller to manage an uncertain system. Retrieval and stationkeeping results using these nonlinear models and the linear adaptive controller demonstrate the feasibility of the method. The robustness of the controller with respect to parameter uncertainties is also demonstrated by changing the nonlinear model and parameters within the model without redesigning the controller.
Duality between noise and spatial resolution in linear systems.
Gureyev, Timur E; Nesterets, Yakov I; de Hoog, Frank; Schmalz, Gerd; Mayo, Sheridan C; Mohammadi, Sara; Tromba, Giuliana
2014-04-21
It is shown that in a broad class of linear systems, including general linear shift-invariant systems, the spatial resolution and the noise satisfy a duality relationship, resembling the uncertainty principle in quantum mechanics. The product of the spatial resolution and the standard deviation of output noise in such systems represents a type of phase-space volume that is invariant with respect to linear scaling of the point-spread function, and it cannot be made smaller than a certain positive absolute lower limit. A corresponding intrinsic "quality" characteristic is introduced and then evaluated for the cases of some popular imaging systems, including computed tomography, generic image convolution and phase-contrast imaging. It is shown that in the latter case the spatial resolution and the noise can sometimes be decoupled, potentially leading to a substantial increase in the imaging quality.
Geometric and asymptotic properties associated with linear switched systems
NASA Astrophysics Data System (ADS)
Chitour, Y.; Gaye, M.; Mason, P.
2015-12-01
Consider a continuous-time linear switched system on Rn associated with a compact convex set of matrices. When it is irreducible and its largest Lyapunov exponent is zero there always exists a Barabanov norm associated with the system. This paper deals with two types of issues: (a) properties of Barabanov norms such as uniqueness up to homogeneity and strict convexity; (b) asymptotic behavior of the extremal solutions of the linear switched system. Regarding Issue (a), we provide partial answers and propose four related open problems. As for Issue (b), we establish, when n = 3, a Poincaré-Bendixson theorem under a regularity assumption on the set of matrices. We then revisit a noteworthy result of N.E. Barabanov describing the asymptotic behavior of linear switched system on R3 associated with a pair of Hurwitz matrices { A , A + bcT }. After pointing out a gap in Barabanov's proof we partially recover his result by alternative arguments.
Powerful tool for design analysis of linear control systems
Maddux, Jr, A S
1982-05-10
The methods for designing linear controls for electronic or mechanical systems have been understood and put to practice. What has not been readily available to engineers, however, is a practical, quick and inexpensive method for analyzing these linear control (feedback) systems once they have been designed into the electronic or mechanical hardware. Now, the PET, manufactured by Commodore Business Machines (CBM), operating with several peripherals via the IEEE 488 Bus, brings to the engineer for about $4000 a complete set of office tools for analyzing these system designs.
LDRD final report on a unified linear reference system
Espinoza, J. Jr.; Mackoy, R.D.; Fletcher, D.R.
1997-06-01
The purpose of the project was to describe existing deficiencies in Geographic Information Systems for transportation (GIS-T) applications and prescribe solutions that would benefit the transportation community in general. After an in-depth literature search and much consultation with noted transportation experts, the need for a common linear reference system that integrated and supported the planning and operational needs of the transportation community became very apparent. The focus of the project was set on a unified linear reference system and how to go about its requirements definition, design, implementation, and promulgation to the transportation community.
A New Device for Bimorph Mirrors Technology: the A1902BS Bipolar Power Supply System
NASA Astrophysics Data System (ADS)
Cautero, M.; Cautero, G.; Krastanov, B.; Billè, F.; Borghes, R.; Iviani, L.; Cocco, D.; Sostero, G.; Signorato, R.
2007-01-01
An important feature of X-ray Piezoelectric Bimorph Mirror (PBM) is the possibility to continuously vary its curvature (dynamical bending); this ability allows the precise adjustment of their optical properties to different beamline geometries and permits the variation of the grazing angle of incidence or to optimize the focal spot dimensions in the experimental chamber. When a driving voltage is applied at a particular position of the mirror, one of the piezo plates shrinks while the other one expands and, as an example, it can result in a purely spherical bending of the device if the same voltage is applied to all electrodes. The applied voltages have to be kept extremely stable on a very long time scale (weeks or even months). This means that the performance and the general behavior of the mirror are strongly dependent on the power supply used to drive it. For this challenging application, Sincrotrone Trieste developed a particularly stable high voltage bipolar power supply system (ranging from -2kV to + 2kV, zero crossing). This system is controlled by an Intel SBC board and accessible via Ethernet through any common web browser, Lab VIEW client or some of the most popular synchrotron facility control systems (Epics and Tango for instance). The maximum drain and source capabilities are 500uA per channel. Voltage monitoring is achieved by sensing the real output and feeding it to a true 16bit ADC. The voltage resolution achieved is about 60mV while the current resolution is about 60nA. Noise and residual ripple (rms) are better than 15ppm/FS and, most important, the long term stability (1 week observation) is better than 100ppm/FS. Some metrological measurements, on different bimorph mirrors, was carried out at the optical laboratory of Elettra. These measures demonstrate the high level of resolution and stability of the power supplies, able to change considerably the radius of curvature of the mirror and, in the meantime, correct even very small shape error.
Non-linear dynamic analysis of geared systems, part 2
NASA Technical Reports Server (NTRS)
Singh, Rajendra; Houser, Donald R.; Kahraman, Ahmet
1990-01-01
A good understanding of the steady state dynamic behavior of a geared system is required in order to design reliable and quiet transmissions. This study focuses on a system containing a spur gear pair with backlash and periodically time-varying mesh stiffness, and rolling element bearings with clearance type non-linearities. A dynamic finite element model of the linear time-invariant (LTI) system is developed. Effects of several system parameters, such as torsional and transverse flexibilities of the shafts and prime mover/load inertias, on free and force vibration characteristics are investigated. Several reduced order LTI models are developed and validated by comparing their eigen solution with the finite element model results. Several key system parameters such as mean load and damping ratio are identified and their effects on the non-linear frequency response are evaluated quantitatively. Other fundamental issues such as the dynamic coupling between non-linear modes, dynamic interactions between component non-linearities and time-varying mesh stiffness, and the existence of subharmonic and chaotic solutions including routes to chaos have also been examined in depth.
Preprocessing Inconsistent Linear System for a Meaningful Least Squares Solution
NASA Technical Reports Server (NTRS)
Sen, Syamal K.; Shaykhian, Gholam Ali
2011-01-01
Mathematical models of many physical/statistical problems are systems of linear equations. Due to measurement and possible human errors/mistakes in modeling/data, as well as due to certain assumptions to reduce complexity, inconsistency (contradiction) is injected into the model, viz. the linear system. While any inconsistent system irrespective of the degree of inconsistency has always a least-squares solution, one needs to check whether an equation is too much inconsistent or, equivalently too much contradictory. Such an equation will affect/distort the least-squares solution to such an extent that renders it unacceptable/unfit to be used in a real-world application. We propose an algorithm which (i) prunes numerically redundant linear equations from the system as these do not add any new information to the model, (ii) detects contradictory linear equations along with their degree of contradiction (inconsistency index), (iii) removes those equations presumed to be too contradictory, and then (iv) obtain the minimum norm least-squares solution of the acceptably inconsistent reduced linear system. The algorithm presented in Matlab reduces the computational and storage complexities and also improves the accuracy of the solution. It also provides the necessary warning about the existence of too much contradiction in the model. In addition, we suggest a thorough relook into the mathematical modeling to determine the reason why unacceptable contradiction has occurred thus prompting us to make necessary corrections/modifications to the models - both mathematical and, if necessary, physical.
Asymptotically optimal feedback control for a system of linear oscillators
NASA Astrophysics Data System (ADS)
Ovseevich, Alexander; Fedorov, Aleksey
2013-12-01
We consider problem of damping of an arbitrary number of linear oscillators under common bounded control. We are looking for a feedback control steering the system to the equilibrium. The obtained control is asymptotically optimal: the ratio of motion time to zero with this control to the minimum one is close to 1, if the initial energy of the system is large.
Asymptotic behavior of coupled linear systems modeling suspension bridges
NASA Astrophysics Data System (ADS)
Dell'Oro, Filippo; Giorgi, Claudio; Pata, Vittorino
2015-06-01
We consider the coupled linear system describing the vibrations of a string-beam system related to the well-known Lazer-McKenna suspension bridge model. For ɛ > 0 and k > 0, the decay properties of the solution semigroup are discussed in dependence of the nonnegative parameters γ and h, which are responsible for the damping effects.
Detail, Face C (rear), showing Interference Analysis System Linear Test ...
Detail, Face C (rear), showing Interference Analysis System Linear Test Array mounted at Level 4A - Beale Air Force Base, Perimeter Acquisition Vehicle Entry Phased-Array Warning System, Techinical Equipment Building, End of Spencer Paul Road, north of Warren Shingle Road (14th Street), Marysville, Yuba County, CA
A Methodology and Linear Model for System Planning and Evaluation.
ERIC Educational Resources Information Center
Meyer, Richard W.
1982-01-01
The two-phase effort at Clemson University to design a comprehensive library automation program is reported. Phase one was based on a version of IBM's business system planning methodology, and the second was based on a linear model designed to compare existing program systems to the phase one design. (MLW)
Feedback stabilization and control of linear neutral systems
NASA Technical Reports Server (NTRS)
Tarn, T. J.; Spong, M. W.; Ito, K.
1982-01-01
The first problem treated here is the realization and stabilization of linear neutral systems with discrete delays. It is shown that any autonomous linear neutral system with discrete delays is zero-state equivalent to an abstract linear system over a local ring of operators. Using the abstract model, the basic existence question for neutral realization is then settled. For general infinite dimensional linear systems, there is no precise analog of the finite dimensional state space isomorphism theorem. Because of this, the notion of spectral minimality must be introduced. For the case of single input-single output systems, realizations are obtained that are both minimal and spectrally minimal. Using the Cruz-Hale theory of stable D-operators, conditions are given that ensure that any poles introduced into the realization are strictly contained in the left half plane and indeed are characterized as characteristic values of the D-operator. The problem of the feedback stabilization of neutral systems is then considered using the abstract model. It is shown that, for neutral systems with commensurable delays and a stable D-operator in the sense of Cruz and Hale, Morses theorem (1976) on pole assignment over a PID implies stabilizability in the reachable case.
Parallel preconditioning for the solution of nonsymmetric banded linear systems
Amodio, P.; Mazzia, F.
1994-12-31
Many computational techniques require the solution of banded linear systems. Common examples derive from the solution of partial differential equations and of boundary value problems. In particular the authors are interested in the parallel solution of block Hessemberg linear systems Gx = f, arising from the solution of ordinary differential equations by means of boundary value methods (BVMs), even if the considered preconditioning may be applied to any block banded linear system. BVMs have been extensively investigated in the last few years and their stability properties give promising results. A new class of BVMs called Reverse Adams, which are BV-A-stable for orders up to 6, and BV-A{sub 0}-stable for orders up to 9, have been studied.
Optimal second order sliding mode control for linear uncertain systems.
Das, Madhulika; Mahanta, Chitralekha
2014-11-01
In this paper an optimal second order sliding mode controller (OSOSMC) is proposed to track a linear uncertain system. The optimal controller based on the linear quadratic regulator method is designed for the nominal system. An integral sliding mode controller is combined with the optimal controller to ensure robustness of the linear system which is affected by parametric uncertainties and external disturbances. To achieve finite time convergence of the sliding mode, a nonsingular terminal sliding surface is added with the integral sliding surface giving rise to a second order sliding mode controller. The main advantage of the proposed OSOSMC is that the control input is substantially reduced and it becomes chattering free. Simulation results confirm superiority of the proposed OSOSMC over some existing.
Linear induction accelerator and pulse forming networks therefor
Buttram, Malcolm T.; Ginn, Jerry W.
1989-01-01
A linear induction accelerator includes a plurality of adder cavities arranged in a series and provided in a structure which is evacuated so that a vacuum inductance is provided between each adder cavity and the structure. An energy storage system for the adder cavities includes a pulsed current source and a respective plurality of bipolar converting networks connected thereto. The bipolar high-voltage, high-repetition-rate square pulse train sets and resets the cavities.
Kemp, David E; Gao, Keming; Chan, Philip; Ganocy, Stephen J; Findling, Robert L; Calabrese, Joseph R
2010-01-01
Objective The present study examined the relationship between medical burden in bipolar disorder and several indicators of illness severity and outcome. It was hypothesized that illnesses of the endocrine/metabolic system would be associated with greater psychiatric symptom burden and would impact the response to treatment with lithium and valproate. Method Data were analyzed from two studies evaluating lithium and valproate for rapid-cycling presentations of bipolar I and II disorder. General medical comorbidity was assessed by the Cumulative Illness Rating Scale (CIRS). Descriptive statistics and logistic regression analyses were conducted to explore the relationships between medical burden, body mass index (BMI), substance use disorder status, and depressive symptom severity. Results Of 225 patients enrolled, 41.8% had a recent substance use disorder, 50.7% were male, and 69.8% had bipolar I disorder. The mean age of the sample was 36.8 (SD = 10.8) years old. The mean number of comorbid medical disorders per patient was 2.5 (SD = 2.5), and the mean CIRS total score was 4.3 (SD = 3.1). A significant positive correlation was observed between baseline depression severity and the number of organ systems affected by medical illness (p = 0.04). Illnesses of the endocrine/metabolic system were inversely correlated with remission from depressive symptoms (p = 0.02), and obesity was specifically associated with poorer treatment outcome. For every 1-unit increase in BMI, the likelihood of response decreased by 7.5% [odds ratio (OR) = 0.93, 95% confidence interval (CI): 0.87–0.99; p = 0.02] and the likelihood of remission decreased by 7.3% (OR = 0.93, 95% CI: 0.87–0.99; p = 0.03). The effect of comorbid substance use on the likelihood of response differed significantly according to baseline BMI. The presence of a comorbid substance use disorder resulted in a lower odds of response, but only among patients with a BMI ≥ 23 (p = 0.02). Conclusion Among patients with
Robot arm force control through system linearization by nonlinear feedback
NASA Technical Reports Server (NTRS)
Tarn, T. J.; Bejczy, A. K.; Yun, Xiaoping
1988-01-01
Based on a differential geometric feedback linearization technique for nonlinear time-varying systems, a dynamic force control method for robot arms is developed. It uses active force-moment measurements at the robot wrist. The controller design fully incorporate the robot-arm dynamics and is so general that it can be reduced to pure position control, hybrid position/force control, pure force control. The controller design is independent of the tasks to be performed. Computer simulations show that the controller improves the position error by a factor of ten in cases in which position errors generate force measurements. A theorem on linearization of time-varying system is also presented.
Conference on iterative methods for large linear systems
Kincaid, D.R.
1988-12-01
This conference is dedicated to providing an overview of the state of the art in the use of iterative methods for solving sparse linear systems with an eye to contributions of the past, present and future. The emphasis is on identifying current and future research directions in the mainstream of modern scientific computing. Recently, the use of iterative methods for solving linear systems has experienced a resurgence of activity as scientists attach extremely complicated three-dimensional problems using vector and parallel supercomputers. Many research advances in the development of iterative methods for high-speed computers over the past forty years are reviewed, as well as focusing on current research.
Solution of linear systems by a singular perturbation technique
NASA Technical Reports Server (NTRS)
Ardema, M. D.
1976-01-01
An approximate solution is obtained for a singularly perturbed system of initial valued, time invariant, linear differential equations with multiple boundary layers. Conditions are stated under which the approximate solution converges uniformly to the exact solution as the perturbation parameter tends to zero. The solution is obtained by the method of matched asymptotic expansions. Use of the results for obtaining approximate solutions of general linear systems is discussed. An example is considered to illustrate the method and it is shown that the formulas derived give a readily computed uniform approximation.
Conference on iterative methods for large linear systems
Kincaid, D.R.
1988-12-01
This conference is dedicated to providing an overview of the state of the art in the use of iterative methods for solving sparse linear systems with an eye to contributions of the past, present and future. The emphasis is on identifying current and future research directions in the mainstream of modern scientific computing. Recently, the use of iterative methods for solving linear systems has experienced a resurgence of activity as scientists attach extremely complicated three-dimensional problems using vector and parallel supercomputers. Many research advances in the development of iterative methods for high-speed computers over the past forty years are reviewed, as well as focusing on current research.
Computer-aided-analysis of linear control system robustness
NASA Technical Reports Server (NTRS)
Stengel, Robert F.; Ray, Laura R.
1990-01-01
Stochastic robustness is a simple technique used to estimate the stability and performance robustness of linear, time-invariant systems. The use of high-speed graphics workstations and control system design software in stochastic robustness analysis is discussed and demonstrated. It is shown that stochastic robustness makes good use of modern computational and graphic tools, and it is easily implemented using commercial control system design and analysis software.
Stability analysis of linear fractional differential system with distributed delays
NASA Astrophysics Data System (ADS)
Veselinova, Magdalena; Kiskinov, Hristo; Zahariev, Andrey
2015-11-01
In the present work we study the Cauchy problem for linear incommensurate fractional differential system with distributed delays. For the autonomous case with distributed delays with derivatives in Riemann-Liouville or Caputo sense, we establish sufficient conditions under which the zero solution is globally asymptotic stable. The established conditions coincide with the conditions which guaranty the same result in the particular case of system with constant delays and for the case of system without delays in the commensurate case too.
Stabilization of linear distributed control systems with unbounded delay
NASA Astrophysics Data System (ADS)
Henríquez, Hernán R.; Hernández M., Eduardo
2005-07-01
In this paper we study the asymptotic stabilization of linear distributed parameter control systems with unbounded delay. Assuming that the semigroup of operators associated with the uncontrolled and nondelayed equation is compact and that the phase space is a uniform fading memory space, we characterize those systems that can be stabilized using a feedback control. As consequence we conclude that every system of this type is stabilizable with an appropriated finite dimensional control.
Colorized linear CCD data acquisition system with automatic exposure control
NASA Astrophysics Data System (ADS)
Li, Xiaofan; Sui, Xiubao
2014-11-01
Colorized linear cameras deliver superb color fidelity at the fastest line rates in the industrial inspection. It's RGB trilinear sensor eliminates image artifacts by placing a separate row of pixels for each color on a single sensor. It's advanced design minimizes distance between rows to minimize image artifacts due to synchronization. In this paper, the high-speed colorized linear CCD data acquisition system was designed take advantages of the linear CCD sensor μpd3728. The hardware and software design of the system based on FPGA is introduced and the design of the functional modules is performed. The all system is composed of CCD driver module, data buffering module, data processing module and computer interface module. The image data was transferred to computer by Camera link interface. The system which automatically adjusts the exposure time of linear CCD, is realized with a new method. The integral time of CCD can be controlled by the program. The method can automatically adjust the integration time for different illumination intensity under controlling of FPGA, and respond quickly to brightness changes. The data acquisition system is also offering programmable gains and offsets for each color. The quality of image can be improved after calibration in FPGA. The design has high expansibility and application value. It can be used in many application situations.
A linear distribution of orbits in compact planetary systems?
NASA Astrophysics Data System (ADS)
Migaszewski, Cezary; Goździewski, Krzysztof; Słonina, Mariusz
2013-11-01
We report a linear ordering of orbits in a sample of multiple extrasolar planetary systems with super-Earth planets. We selected 20 cases, mostly discovered by the Kepler mission, hosting at least four planets within ˜0.5 au. The semimajor axis an of an nth planet in each system of this sample obeys a(n) = a1 + (n - 1) Δa, where a1 is the semimajor axis of the innermost orbit and Δa is a spacing between subsequent planets, which are specific for a particular system. For instance, the Kepler-33 system hosting five super-Earth planets exhibits the relative deviations between the observed and linearly predicted semimajor axes of only a few per cent. At least half of systems in the sample fulfil the linear law with a similar accuracy. We explain the linear distribution of semimajor axes as a natural implication of multiple chains of mean-motion resonances between subsequent planets, which emerge due to planet-disc interactions and convergent migration at early stages of their evolution.
Exploring the association between bipolar disorder and uric acid: A mediation analysis.
Bartoli, Francesco; Crocamo, Cristina; Gennaro, Giulia Maria; Castagna, Gloria; Trotta, Giulia; Clerici, Massimo; Carrà, Giuseppe
2016-05-01
Recent evidence shows that bipolar disorder might be associated with a purinergic system dysfunction. This study aimed at (i) testing the association between bipolar disorder and uric acid serum levels, and (ii) clarifying whether this relationship is mediated by metabolic syndrome and other relevant metabolic parameters. Patients consecutively admitted to a Mental Health Inpatient Unit, with a diagnosis of bipolar disorder or other severe mental disorders, and an appropriate healthy control sample, were included in this cross-sectional, exploratory study. We performed linear regression analyses, to explore factors associated with uric acid levels, and formal tests of mediation to assess mediating effect of candidate variables. 176 individuals with mental disorders and 89 healthy controls met inclusion criteria. Bipolar disorder was the only diagnostic subgroup significantly associated with increased uric acid levels. Furthermore, male gender, metabolic syndrome, as well as abdominal circumference and triglycerides levels, had a significant effect on uric acid. Relevant mediation analyses showed that the estimated effect between bipolar disorder and uric acid levels was only partially mediated by metabolic abnormalities. This study suggests a direct association between bipolar disorder and uric acid levels, only partially mediated by metabolic abnormalities. It seems consistent with results of previous studies highlighting a purinergic dysfunction in bipolar disorder and the role that purinergic modulators, lowering uric acid levels, could have in clinical practice. Copyright © 2016 Elsevier Inc. All rights reserved.
Chapman, Michael J; Godfrey, Keith R; Chappell, Michael J; Evans, Neil D
2003-05-01
Under certain controllability and observability restrictions, two different parameterisations for a non-linear compartmental model can only have the same input-output behaviour if they differ by a locally diffeomorphic change of basis for the state space. With further restrictions, it is possible to gain valuable information with respect to identifiability via a linear analysis. Examples are presented where non-linear identifiability analyses are substantially simplified by means of an initial linear analysis. For complex models, with four or more compartments, this linear analysis can prove lengthy to perform by hand and so symbolic computation has been employed to aid this procedure.
Stabilising compensators for linear time-varying differential systems
NASA Astrophysics Data System (ADS)
Oberst, Ulrich
2016-04-01
In this paper, we describe a constructive test to decide whether a given linear time-varying (LTV) differential system admits a stabilising compensator for the control tasks of tracking, disturbance rejection or model matching and construct and parametrise all of them if at least one exists. In analogy to the linear time-invariant (LTI) case, the ring of stable rational functions, noncommutative in the LTV situation, and the Kučera-Youla parametrisation play prominent parts in the theory. We transfer Blumthaler's thesis from the LTI to the LTV case and sharpen, complete and simplify the corresponding results in the book 'Linear Time-Varying Systems' by Bourlès and Marinescu.
Experimental quantum computing to solve systems of linear equations.
Cai, X-D; Weedbrook, C; Su, Z-E; Chen, M-C; Gu, Mile; Zhu, M-J; Li, Li; Liu, Nai-Le; Lu, Chao-Yang; Pan, Jian-Wei
2013-06-07
Solving linear systems of equations is ubiquitous in all areas of science and engineering. With rapidly growing data sets, such a task can be intractable for classical computers, as the best known classical algorithms require a time proportional to the number of variables N. A recently proposed quantum algorithm shows that quantum computers could solve linear systems in a time scale of order log(N), giving an exponential speedup over classical computers. Here we realize the simplest instance of this algorithm, solving 2×2 linear equations for various input vectors on a quantum computer. We use four quantum bits and four controlled logic gates to implement every subroutine required, demonstrating the working principle of this algorithm.
Fluctuation loops in noise-driven linear dynamical systems
NASA Astrophysics Data System (ADS)
Ghanta, Akhil; Neu, John C.; Teitsworth, Stephen
2017-03-01
Understanding the spatiotemporal structure of most probable fluctuation pathways to rarely occurring states is a central problem in the study of noise-driven, nonequilibrium dynamical systems. When the underlying system does not possess detailed balance, the optimal fluctuation pathway to a particular state and relaxation pathway from that state may combine to form a looplike structure in the system phase space called a fluctuation loop. Here, fluctuation loops are studied in a linear circuit model consisting of coupled R C elements, where each element is driven by its own independent noise source. Using a stochastic Hamiltonian approach, we determine the optimal fluctuation pathways, and analytically construct corresponding fluctuation loops. To quantitatively characterize fluctuation loops, we study the time-dependent area tensor that is swept out by individual stochastic trajectories in the system phase space. At long times, the area tensor scales linearly with time, with a coefficient that precisely vanishes when the system satisfies detailed balance.
Linear monogamy of entanglement in three-qubit systems
NASA Astrophysics Data System (ADS)
Liu, Feng; Gao, Fei; Wen, Qiao-Yan
2015-11-01
For any three-qubit quantum systems ABC, Oliveira et al. numerically found that both the concurrence and the entanglement of formation (EoF) obey the linear monogamy relations in pure states. They also conjectured that the linear monogamy relations can be saturated when the focus qubit A is maximally entangled with the joint qubits BC. In this work, we prove analytically that both the concurrence and EoF obey linear monogamy relations in an arbitrary three-qubit state. Furthermore, we verify that all three-qubit pure states are maximally entangled in the bipartition A|BC when they saturate the linear monogamy relations. We also study the distribution of the concurrence and EoF. More specifically, when the amount of entanglement between A and B equals to that of A and C, we show that the sum of EoF itself saturates the linear monogamy relation, while the sum of the squared EoF is minimum. Different from EoF, the concurrence and the squared concurrence both saturate the linear monogamy relations when the entanglement between A and B equals to that of A and C.
Recent Developments In Theory Of Balanced Linear Systems
NASA Technical Reports Server (NTRS)
Gawronski, Wodek
1994-01-01
Report presents theoretical study of some issues of controllability and observability of system represented by linear, time-invariant mathematical model of the form. x = Ax + Bu, y = Cx + Du, x(0) = xo where x is n-dimensional vector representing state of system; u is p-dimensional vector representing control input to system; y is q-dimensional vector representing output of system; n,p, and q are integers; x(0) is intial (zero-time) state vector; and set of matrices (A,B,C,D) said to constitute state-space representation of system.
Linear optimal control of continuous time chaotic systems.
Merat, Kaveh; Abbaszadeh Chekan, Jafar; Salarieh, Hassan; Alasty, Aria
2014-07-01
In this research study, chaos control of continuous time systems has been performed by using dynamic programming technique. In the first step by crossing the response orbits with a selected Poincare section and subsequently applying linear regression method, the continuous time system is converted to a discrete type. Then, by solving the Riccati equation a sub-optimal algorithm has been devised for the obtained discrete chaotic systems. In the next step, by implementing the acquired algorithm on the quantized continuous time system, the chaos has been suppressed in the Rossler and AFM systems as some case studies.
Stochastic Satbility and Performance Robustness of Linear Multivariable Systems
NASA Technical Reports Server (NTRS)
Ryan, Laurie E.; Stengel, Robert F.
1990-01-01
Stochastic robustness, a simple technique used to estimate the robustness of linear, time invariant systems, is applied to a single-link robot arm control system. Concepts behind stochastic stability robustness are extended to systems with estimators and to stochastic performance robustness. Stochastic performance robustness measures based on classical design specifications are introduced, and the relationship between stochastic robustness measures and control system design parameters are discussed. The application of stochastic performance robustness, and the relationship between performance objectives and design parameters are demonstrated by means of example. The results prove stochastic robustness to be a good overall robustness analysis method that can relate robustness characteristics to control system design parameters.
Recent Developments In Theory Of Balanced Linear Systems
NASA Technical Reports Server (NTRS)
Gawronski, Wodek
1994-01-01
Report presents theoretical study of some issues of controllability and observability of system represented by linear, time-invariant mathematical model of the form. x = Ax + Bu, y = Cx + Du, x(0) = xo where x is n-dimensional vector representing state of system; u is p-dimensional vector representing control input to system; y is q-dimensional vector representing output of system; n,p, and q are integers; x(0) is intial (zero-time) state vector; and set of matrices (A,B,C,D) said to constitute state-space representation of system.
Linear-constraint wavefront control for exoplanet coronagraphic imaging systems
NASA Astrophysics Data System (ADS)
Sun, He; Eldorado Riggs, A. J.; Kasdin, N. Jeremy; Vanderbei, Robert J.; Groff, Tyler Dean
2017-01-01
A coronagraph is a leading technology for achieving high-contrast imaging of exoplanets in a space telescope. It uses a system of several masks to modify the diffraction and achieve extremely high contrast in the image plane around target stars. However, coronagraphic imaging systems are very sensitive to optical aberrations, so wavefront correction using deformable mirrors (DMs) is necessary to avoid contrast degradation in the image plane. Electric field conjugation (EFC) and Stroke minimization (SM) are two primary high-contrast wavefront controllers explored in the past decade. EFC minimizes the average contrast in the search areas while regularizing the strength of the control inputs. Stroke minimization calculates the minimum DM commands under the constraint that a target average contrast is achieved. Recently in the High Contrast Imaging Lab at Princeton University (HCIL), a new linear-constraint wavefront controller based on stroke minimization was developed and demonstrated using numerical simulation. Instead of only constraining the average contrast over the entire search area, the new controller constrains the electric field of each single pixel using linear programming, which could led to significant increases in speed of the wavefront correction and also create more uniform dark holes. As a follow-up of this work, another linear-constraint controller modified from EFC is demonstrated theoretically and numerically and the lab verification of the linear-constraint controllers is reported. Based on the simulation and lab results, the pros and cons of linear-constraint controllers are carefully compared with EFC and stroke minimization.
Scalable Library for the Parallel Solution of Sparse Linear Systems
Jones, Mark; Plassmann, Paul E.
1993-07-14
BlockSolve is a scalable parallel software library for the solution of large sparse, symmetric systems of linear equations. It runs on a variety of parallel architectures and can easily be ported to others. BlockSovle is primarily intended for the solution of sparse linear systems that arise from physical problems having multiple degrees of freedom at each node point. For example, when the finite element method is used to solve practical problems in structural engineering, each node will typically have anywhere from 3-6 degrees of freedom associated with it. BlockSolve is written to take advantage of problems of this nature; however, it is still reasonably efficient for problems that have only one degree of freedom associated with each node, such as the three-dimensional Poisson problem. It does not require that the matrices have any particular structure other than being sparse and symmetric. BlockSolve is intended to be used within real application codes. It is designed to work best in the context of our experience which indicated that most application codes solve the same linear systems with several different right-hand sides and/or linear systems with the same structure, but different matrix values multiple times.
Robustness with observers. [linear optimal feedback control systems
NASA Technical Reports Server (NTRS)
Doyle, J. C.; Stein, G.
1979-01-01
The paper describes an adjustment procedure for observer-based linear control systems which asymptotically achieves the same loop transfer functions (and hence the same relative stability, robustness, and disturbance rejection properties) as full-state feedback control implementations. Full-state loop-transfer properties can be recovered asymptotically if the plant is minimum phase; this occurs at the expense of noise performance.
Generating Nice Linear Systems for Matrix Gaussian Elimination
ERIC Educational Resources Information Center
Homewood, L. James
2004-01-01
In this article an augmented matrix that represents a system of linear equations is called nice if a sequence of elementary row operations that reduces the matrix to row-echelon form, through matrix Gaussian elimination, does so by restricting all entries to integers in every step. Many instructors wish to use the example of matrix Gaussian…
Stabilization of linear multivariable systems by output feedback.
NASA Technical Reports Server (NTRS)
Mcbrinn, D. E.; Roy, R. J.
1972-01-01
A method is developed for improving the stability of linear multivariable systems using output feedback. The technique, which utilizes a gradient approach, has been mechanized in a digital computer program. Illustrative results are given for a seven-state two-feedback model of the Saturn V booster.
Optimal Regulator Algorithms For The Control Of Linear Systems (ORACLS)
NASA Technical Reports Server (NTRS)
Frisch, Harold P.
1990-01-01
Control theory design package offers engineer full range of subroutines to manipulate and solve Linear-Quadratic-Gaussian types of problems. ORACLS is rigorous tool, intended for multi-input and multi-output dynamic systems in both continuous and discrete form. Written in FORTRAN.
Alshehri, Noura O.
2013-01-01
We introduce the concept of Cayley bipolar fuzzy graphs and investigate some of their properties. We present some interesting properties of bipolar fuzzy graphs in terms of algebraic structures. We also discuss connectedness in Cayley bipolar fuzzy graphs. PMID:24453797
Comparative index and Sturmian theory for linear Hamiltonian systems
NASA Astrophysics Data System (ADS)
Šepitka, Peter; Šimon Hilscher, Roman
2017-01-01
The comparative index was introduced by J. Elyseeva (2007) as an efficient tool in matrix analysis, which has fundamental applications in the discrete oscillation theory. In this paper we implement the comparative index into the theory of continuous time linear Hamiltonian systems, study its properties, and apply it to obtain new Sturmian separation theorems as well as new and optimal estimates for left and right proper focal points of conjoined bases of these systems on bounded intervals. We derive our results for general possibly abnormal (or uncontrollable) linear Hamiltonian systems. The results turn out to be new even in the case of completely controllable systems. We also provide several examples, which illustrate our new theory.
Parallel/distributed direct method for solving linear systems
NASA Technical Reports Server (NTRS)
Lin, Avi
1990-01-01
A new family of parallel schemes for directly solving linear systems is presented and analyzed. It is shown that these schemes exhibit a near optimal performance and enjoy several important features: (1) For large enough linear systems, the design of the appropriate paralleled algorithm is insensitive to the number of processors as its performance grows monotonically with them; (2) It is especially good for large matrices, with dimensions large relative to the number of processors in the system; (3) It can be used in both distributed parallel computing environments and tightly coupled parallel computing systems; and (4) This set of algorithms can be mapped onto any parallel architecture without any major programming difficulties or algorithmical changes.
Fosdick, Stephen E; Knust, Kyle N; Scida, Karen; Crooks, Richard M
2013-09-27
A bipolar electrode (BPE) is an electrically conductive material that promotes electrochemical reactions at its extremities (poles) even in the absence of a direct ohmic contact. More specifically, when sufficient voltage is applied to an electrolyte solution in which a BPE is immersed, the potential difference between the BPE and the solution drives oxidation and reduction reactions. Because no direct electrical connection is required to activate redox reactions, large arrays of electrodes can be controlled with just a single DC power supply or even a battery. The wireless aspect of BPEs also makes it possible to electrosynthesize and screen novel materials for a wide variety of applications. Finally, bipolar electrochemistry enables mobile electrodes, dubbed microswimmers, that are able to move freely in solution. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Design and performance of the Stanford Linear Collider Control System
Melen, R.E.
1984-10-01
The success of the Stanford Linear Collider (SLC) will be dependent upon the implementation of a very large advanced computer-based instrumentation and control system. This paper describes the architectural design of this system as well as a critique of its performance. This critique is based on experience obtained from its use in the control and monitoring of 1/3 of the SLAC linac and in support of an expensive experimental machine physics experimental program. 11 references, 3 figures.
Robust stability analysis of linear systems with parametric uncertainty
NASA Astrophysics Data System (ADS)
Zhai, Ding; Zhang, Qing-Ling; Liu, Guo-Yi
2012-09-01
This article is concerned with the problem of robust stability analysis of linear systems with uncertain parameters. By constructing an equivalent system with positive uncertain parameters and using the properties of these parameters, a new stability analysis condition is derived. Due to making use of the properties of uncertain parameters, the new proposed method has potential to give less conservative results than the existing approaches. A numerical example is given to illustrate the effectiveness of the proposed method.
A biased filter for linear discrete dynamic systems.
NASA Technical Reports Server (NTRS)
Chang, J. W.; Hoerl, A. E.; Leathrum, J. F.
1972-01-01
A recursive estimator, the ridge filter, was developed for the linear discrete dynamic estimation problem. Theorems were established to show that the ridge filter can be, on the average, closer to the expected value of the system state than the Kalman filter. On the other hand, Kalman filter, on the average, is closer to the instantaneous system state than the ridge filter. The ridge filter has been formulated in such a way that the computational features of the Kalman filter are preserved.
New timing system for the Stanford Linear Collider
Paffrath, L.; Bernstein, D.; Kang, H.; Koontz, R.; Leger, G.; Ross, M.; Pierce, W.; Wilmunder, A.
1984-11-01
In order to be able to meet the goals of the Stanford Linear Collider, a much more precise timing system had to be implemented. This paper describes the specification and design of this system, and the results obtained from its use on 1/3 of the SLAC linac. The functions of various elements are described, and a programmable delay unit (PDU) is described in detail.
Active Control of Linear Periodic System with Two Unstable Modes.
1982-12-01
tV;;;.~II.~9 - B ~ZV ~- p1 . ,,~ >. ~ ACTIVE CONTROL OF LINEAR PERIODIC SYSTEM WITH TWO UNSTABLE MODES THESIS by Gregory E. Myers, B.S.E. 2nd Lt...PERIODIC SYSTEM WITH TWO UNSTABLE MODES THESIS Presented to the Faculty of the School of Engineering of the Air Force Institute of Technology Air University...December 1982 Approved for public release; distribution unlimited -ow PREFACE This thesis is a continuation of the work done by Yeakel in the control of
Robust fault detection observer design for linear uncertain systems
NASA Astrophysics Data System (ADS)
Wei, Xiukun; Verhaegen, Michel
2011-01-01
This article addresses the fault detection observer design issue for linear time invariant (LTI) systems with additive or multiplicative uncertainties, which are also subject to unknown disturbances. The observer design is investigated under the ℋ∞/ℋ- index framework using the generalised KYP lemma in the finite-frequency domain. Sufficient conditions for the existence of such a fault detection observer are given in terms of linear matrix inequalities (LMIs). The threshold design issue is discussed and a method for estimating the worst undetectable fault size is proposed. The effectiveness of the proposed algorithms is illustrated by numerical simulation examples.
Identification of single-input-single-output quantum linear systems
NASA Astrophysics Data System (ADS)
Levitt, Matthew; GuÅ£ǎ, Mǎdǎlin
2017-03-01
The purpose of this paper is to investigate system identification for single-input-single-output general (active or passive) quantum linear systems. For a given input we address the following questions: (1) Which parameters can be identified by measuring the output? (2) How can we construct a system realization from sufficient input-output data? We show that for time-dependent inputs, the systems which cannot be distinguished are related by symplectic transformations acting on the space of system modes. This complements a previous result of Guţă and Yamamoto [IEEE Trans. Autom. Control 61, 921 (2016), 10.1109/TAC.2015.2448491] for passive linear systems. In the regime of stationary quantum noise input, the output is completely determined by the power spectrum. We define the notion of global minimality for a given power spectrum, and characterize globally minimal systems as those with a fully mixed stationary state. We show that in the case of systems with a cascade realization, the power spectrum completely fixes the transfer function, so the system can be identified up to a symplectic transformation. We give a method for constructing a globally minimal subsystem direct from the power spectrum. Restricting to passive systems the analysis simplifies so that identifiability may be completely understood from the eigenvalues of a particular system matrix.
Solving complex-valued linear systems via equivalent real formulations
DAY,DAVID M.; HEROUX,MICHAEL A.
2000-05-22
Most algorithms used in preconditioned iterative methods are generally applicable to complex valued linear systems, with real valued linear systems simply being a special case. However, most iterative solver packages available today focus exclusively on real valued systems, or deal with complex valued systems as an afterthought. One obvious approach to addressing this problem is to recast the complex problem into one of a several equivalent real forms and then use a real valued solver to solve the related system. However, well-known theoretical results showing unfavorable spectral properties for the equivalent real forms have diminished enthusiasm for this approach. At the same time, experience has shown that there are situations where using an equivalent real form can be very effective. In this paper, the authors explore this approach, giving both theoretical and experimental evidence that an equivalent real form can be useful for a number of practical situations. Furthermore, they show that by making good use of some of the advance features of modem solver packages, they can easily generate equivalent real form preconditioners that are computationally efficient and mathematically identical to their complex counterparts. Using their techniques, they are able to solve very ill-conditioned complex valued linear systems for a variety of large scale applications. However, more importantly, they shed more light on the effectiveness of equivalent real forms and more clearly delineate how and when they should be used.
Optimum Damping in a Non-Linear Base Isolation System
NASA Astrophysics Data System (ADS)
Jangid, R. S.
1996-02-01
Optimum isolation damping for minimum acceleration of a base-isolated structure subjected to earthquake ground excitation is investigated. The stochastic model of the El-Centro1940 earthquake, which preserves the non-stationary evolution of amplitude and frequency content of ground motion, is used as an earthquake excitation. The base isolated structure consists of a linear flexible shear type multi-storey building supported on a base isolation system. The resilient-friction base isolator (R-FBI) is considered as an isolation system. The non-stationary stochastic response of the system is obtained by the time dependent equivalent linearization technique as the force-deformation of the R-FBI system is non-linear. The optimum damping of the R-FBI system is obtained under important parametric variations; i.e., the coefficient of friction of the R-FBI system, the period and damping of the superstructure; the effective period of base isolation. The criterion selected for optimality is the minimization of the top floor root mean square (r.m.s.) acceleration. It is shown that the above parameters have significant effects on optimum isolation damping.
String Stability of a Linear Formation Flight Control System
NASA Technical Reports Server (NTRS)
Allen, Michael J.; Ryan, Jack; Hanson, Curtis E.; Parle, James F.
2002-01-01
String stability analysis of an autonomous formation flight system was performed using linear and nonlinear simulations. String stability is a measure of how position errors propagate from one vehicle to another in a cascaded system. In the formation flight system considered here, each i(sup th) aircraft uses information from itself and the preceding ((i-1)(sup th)) aircraft to track a commanded relative position. A possible solution for meeting performance requirements with such a system is to allow string instability. This paper explores two results of string instability and outlines analysis techniques for string unstable systems. The three analysis techniques presented here are: linear, nonlinear formation performance, and ride quality. The linear technique was developed from a worst-case scenario and could be applied to the design of a string unstable controller. The nonlinear formation performance and ride quality analysis techniques both use nonlinear formation simulation. Three of the four formation-controller gain-sets analyzed in this paper were limited more by ride quality than by performance. Formations of up to seven aircraft in a cascaded formation could be used in the presence of light gusts with this string unstable system.
Identification and robust control of linear parameter-varying systems
NASA Astrophysics Data System (ADS)
Lee, Lawton Hubert
This dissertation deals with linear parameter-varying (LPV) systems: linear dynamic systems that depend on time-varying parameters. These systems appear in gain scheduling problems, and much recent research has been devoted to their prospective usefulness for systematic gain scheduling. We primarily focus on robust control of uncertain LPV systems and identification of LPV systems that are modelable as linear-fractional transformations (LFTs). Using parameter-dependent quadratic Lyapunov functions, linear matrix inequalities (LMIs), and scaled small-gain arguments, we define notions of stability and induced-{cal L}sb2 performance for uncertain LPV systems whose parameters and rates of parameter variation satisfy given bounds. The performance criterion involves integral quadratic constraints and implies naturally parameter-dependent induced-{cal L}sb2 norm bounds. We formulate and solve an {cal H}sb{infty}-like control problem for an LPV plant with measurable parameters and an "Output/State Feedback" structure: the feedback outputs include some noiselessly measured states. Necessary and sufficient solvability conditions reduce to LMIs that can be solved approximately using finite-dimensional convex programming. Reduced-order LPV controllers are constructed from the LMI solutions. A D-K iteration-like procedure provides robustness to structured, time-varying, parametric uncertainty. The design method is applied to a motivating example: flight control for the F-16 VISTA throughout its subsonic flight envelope. Parameter-dependent weights and {cal H}sb{infty} design principles describe the performance objectives. Closed-loop responses exhibited by nonlinear simulations indicate satisfactory flying qualities. Identification of linear-fractional LPV systems is treated using maximum-likelihood parameter estimation. Computing the gradient and Hessian of a maximum-likelihood cost function reduces to simulating one LPV filter per identified parameter. We use nonlinear
An approximation theory for the identification of linear thermoelastic systems
NASA Technical Reports Server (NTRS)
Rosen, I. G.; Su, Chien-Hua Frank
1990-01-01
An abstract approximation framework and convergence theory for the identification of thermoelastic systems is developed. Starting from an abstract operator formulation consisting of a coupled second order hyperbolic equation of elasticity and first order parabolic equation for heat conduction, well-posedness is established using linear semigroup theory in Hilbert space, and a class of parameter estimation problems is then defined involving mild solutions. The approximation framework is based upon generic Galerkin approximation of the mild solutions, and convergence of solutions of the resulting sequence of approximating finite dimensional parameter identification problems to a solution of the original infinite dimensional inverse problem is established using approximation results for operator semigroups. An example involving the basic equations of one dimensional linear thermoelasticity and a linear spline based scheme are discussed. Numerical results indicate how the approach might be used in a study of damping mechanisms in flexible structures.
Vacuum systems of linear accelerators of the NICA injection complex
NASA Astrophysics Data System (ADS)
Kosachev, V. V.; Bazanov, A. M.; Butenko, A. V.; Galimov, A. R.; Nesterov, A. V.; Pivin, R. V.; Smirnov, A. V.
2016-12-01
The NICA project, which includes several accelerators of charged particles, is under construction in the Laboratory of High Energy Physics, Joint Institute for Nuclear Research (JINR), Dubna. Obtaining the required vacuum conditions is one of the key points in implementing the project, because reaching the required ion lifetime at all stages of particle acceleration is what determines the effective luminosity of the experiments in the long run. Currently, modernization of the vacuum system of the injection complex of the LU-20 linear accelerator of light ions, one of oldest accelerators in the JINR, is being carried out and the new HILAC linear accelerator for the acceleration of gold ions in the collider mode of the NICA complex is being installed. At the end parts of the linear accelerators, the residual gas pressure must be approximately 10-5 Pa, which is determined by the maximum amplitude of the RF electric field used for the acceleration of ions.
Quintana, Daniel S; Dieset, Ingrid; Elvsåshagen, Torbjørn; Westlye, Lars T; Andreassen, Ole A
2017-01-01
There is growing interest in using intranasal oxytocin (OT) to treat social dysfunction in schizophrenia and bipolar disorders (i.e., psychotic disorders). While OT treatment results have been mixed, emerging evidence suggests that OT system dysfunction may also play a role in the etiology of metabolic syndrome (MetS), which appears in one-third of individuals with psychotic disorders and associated with increased mortality. Here we examine the evidence for a potential role of the OT system in the shared risk for MetS and psychotic disorders, and its prospects for ameliorating MetS. Using several studies to demonstrate the overlapping neurobiological profiles of metabolic risk factors and psychiatric symptoms, we show that OT system dysfunction may be one common mechanism underlying MetS and psychotic disorders. Given the critical need to better understand metabolic dysregulation in these disorders, future OT trials assessing behavioural and cognitive outcomes should additionally include metabolic risk factor parameters.
Ter Heijne, Annemiek; Hamelers, Hubertus V M; De Wilde, Vinnie; Rozendal, René A; Buisman, Cees J N
2006-09-01
There is a need for alternative catalysts for oxygen reduction in the cathodic compartment of a microbial fuel cell (MFC). In this study, we show that a bipolar membrane combined with ferric iron reduction on a graphite electrode is an efficient cathode system in MFCs. A flat plate MFC with graphite felt electrodes, a volume of 1.2 L and a projected surface area of 290 cm2 was operated in continuous mode. Ferric iron was reduced to ferrous iron in the cathodic compartment according to Fe(3+) + e(-) --> Fe2+ (E0 = +0.77 V vs NHE, normal hydrogen electrode). This reversible electron transfer reaction considerably reduced the cathode overpotential. The low catholyte pH required to keep ferric iron soluble was maintained by using a bipolar membrane instead of the commonly used cation exchange membrane. For the MFC with cathodic ferric iron reduction, the maximum power density was 0.86 W/m2 at a current density of 4.5 A/m2. The Coulombic efficiency and energy recovery were 80-95% and 18-29% respectively.
Designing a patient monitoring system for bipolar disorder using Semantic Web technologies.
Thermolia, Chryssa; Bei, Ekaterini S; Petrakis, Euripides G M; Kritsotakis, Vangelis; Tsiknakis, Manolis; Sakkalis, Vangelis
2015-01-01
The new movement to personalize treatment plans and improve prediction capabilities is greatly facilitated by intelligent remote patient monitoring and risk prevention. This paper focuses on patients suffering from bipolar disorder, a mental illness characterized by severe mood swings. We exploit the advantages of Semantic Web and Electronic Health Record Technologies to develop a patient monitoring platform to support clinicians. Relying on intelligently filtering of clinical evidence-based information and individual-specific knowledge, we aim to provide recommendations for treatment and monitoring at appropriate time or concluding into alerts for serious shifts in mood and patients' non response to treatment.
Preconditioning projection methods for solving algebraic linear systems
NASA Astrophysics Data System (ADS)
García-Palomares, Ubaldo
1999-09-01
Numerical experiments have shown that projection methods are robust for solving the problem of finding a point satisfying a linear system of n variables and m equations; however, their qualities of convergence depend on certain parameters: an n n symmetric positive definite matrix M, and a vector u with m components. We are concerned here with the choice of M. Through a link with Conjugate Gradient methods we determine an expedient M. Preliminary numerical results on a hard 3D partial differential equation are highly promising. We solve a discretized system that could not be solved by conventional methods. We also give hints on how to adapt our findings to the solution of a linear system of inequalities. This is the first stage of a forthcoming research.
Applications of equivalent linearization approaches to nonlinear piping systems
Park, Y.; Hofmayer, C.; Chokshi, N.
1997-04-01
The piping systems in nuclear power plants, even with conventional snubber supports, are highly complex nonlinear structures under severe earthquake loadings mainly due to various mechanical gaps in support structures. Some type of nonlinear analysis is necessary to accurately predict the piping responses under earthquake loadings. The application of equivalent linearization approaches (ELA) to seismic analyses of nonlinear piping systems is presented. Two types of ELA`s are studied; i.e., one based on the response spectrum method and the other based on the linear random vibration theory. The test results of main steam and feedwater piping systems supported by snubbers and energy absorbers are used to evaluate the numerical accuracy and limitations.
A parallel solver for huge dense linear systems
NASA Astrophysics Data System (ADS)
Badia, J. M.; Movilla, J. L.; Climente, J. I.; Castillo, M.; Marqués, M.; Mayo, R.; Quintana-Ortí, E. S.; Planelles, J.
2011-11-01
HDSS (Huge Dense Linear System Solver) is a Fortran Application Programming Interface (API) to facilitate the parallel solution of very large dense systems to scientists and engineers. The API makes use of parallelism to yield an efficient solution of the systems on a wide range of parallel platforms, from clusters of processors to massively parallel multiprocessors. It exploits out-of-core strategies to leverage the secondary memory in order to solve huge linear systems O(100.000). The API is based on the parallel linear algebra library PLAPACK, and on its Out-Of-Core (OOC) extension POOCLAPACK. Both PLAPACK and POOCLAPACK use the Message Passing Interface (MPI) as the communication layer and BLAS to perform the local matrix operations. The API provides a friendly interface to the users, hiding almost all the technical aspects related to the parallel execution of the code and the use of the secondary memory to solve the systems. In particular, the API can automatically select the best way to store and solve the systems, depending of the dimension of the system, the number of processes and the main memory of the platform. Experimental results on several parallel platforms report high performance, reaching more than 1 TFLOP with 64 cores to solve a system with more than 200 000 equations and more than 10 000 right-hand side vectors. New version program summaryProgram title: Huge Dense System Solver (HDSS) Catalogue identifier: AEHU_v1_1 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEHU_v1_1.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 87 062 No. of bytes in distributed program, including test data, etc.: 1 069 110 Distribution format: tar.gz Programming language: Fortran90, C Computer: Parallel architectures: multiprocessors, computer clusters Operating system
Galerkin projection methods for solving multiple related linear systems
Chan, T.F.; Ng, M.; Wan, W.L.
1996-12-31
We consider using Galerkin projection methods for solving multiple related linear systems A{sup (i)}x{sup (i)} = b{sup (i)} for 1 {le} i {le} s, where A{sup (i)} and b{sup (i)} are different in general. We start with the special case where A{sup (i)} = A and A is symmetric positive definite. The method generates a Krylov subspace from a set of direction vectors obtained by solving one of the systems, called the seed system, by the CG method and then projects the residuals of other systems orthogonally onto the generated Krylov subspace to get the approximate solutions. The whole process is repeated with another unsolved system as a seed until all the systems are solved. We observe in practice a super-convergence behaviour of the CG process of the seed system when compared with the usual CG process. We also observe that only a small number of restarts is required to solve all the systems if the right-hand sides are close to each other. These two features together make the method particularly effective. In this talk, we give theoretical proof to justify these observations. Furthermore, we combine the advantages of this method and the block CG method and propose a block extension of this single seed method. The above procedure can actually be modified for solving multiple linear systems A{sup (i)}x{sup (i)} = b{sup (i)}, where A{sup (i)} are now different. We can also extend the previous analytical results to this more general case. Applications of this method to multiple related linear systems arising from image restoration and recursive least squares computations are considered as examples.
Chaos pass filter: linear response of synchronized chaotic systems.
Zeeb, Steffen; Kestler, Johannes; Kanter, Ido; Kinzel, Wolfgang
2013-04-01
The linear response of synchronized time-delayed chaotic systems to small external perturbations, i.e., the phenomenon of chaos pass filter, is investigated for iterated maps. The distribution of distances, i.e., the deviations between two synchronized chaotic units due to external perturbations on the transferred signal, is used as a measure of the linear response. It is calculated numerically and, for some special cases, analytically. Depending on the model parameters this distribution has power law tails in the region of synchronization leading to diverging moments of distances. This is a consequence of multiplicative and additive noise in the corresponding linear equations due to chaos and external perturbations. The linear response can also be quantified by the bit error rate of a transmitted binary message which perturbs the synchronized system. The bit error rate is given by an integral over the distribution of distances and is calculated analytically and numerically. It displays a complex nonmonotonic behavior in the region of synchronization. For special cases the distribution of distances has a fractal structure leading to a devil's staircase for the bit error rate as a function of coupling strength. The response to small harmonic perturbations shows resonances related to coupling and feedback delay times. A bidirectionally coupled chain of three units can completely filter out the perturbation. Thus the second moment and the bit error rate become zero.
An extended GS method for dense linear systems
NASA Astrophysics Data System (ADS)
Niki, Hiroshi; Kohno, Toshiyuki; Abe, Kuniyoshi
2009-09-01
Davey and Rosindale [K. Davey, I. Rosindale, An iterative solution scheme for systems of boundary element equations, Internat. J. Numer. Methods Engrg. 37 (1994) 1399-1411] derived the GSOR method, which uses an upper triangular matrix [Omega] in order to solve dense linear systems. By applying functional analysis, the authors presented an expression for the optimum [Omega]. Moreover, Davey and Bounds [K. Davey, S. Bounds, A generalized SOR method for dense linear systems of boundary element equations, SIAM J. Comput. 19 (1998) 953-967] also introduced further interesting results. In this note, we employ a matrix analysis approach to investigate these schemes, and derive theorems that compare these schemes with existing preconditioners for dense linear systems. We show that the convergence rate of the Gauss-Seidel method with preconditioner PG is superior to that of the GSOR method. Moreover, we define some splittings associated with the iterative schemes. Some numerical examples are reported to confirm the theoretical analysis. We show that the EGS method with preconditioner produces an extremely small spectral radius in comparison with the other schemes considered.
Coherent versus Measurement Feedback: Linear Systems Theory for Quantum Information
NASA Astrophysics Data System (ADS)
Yamamoto, Naoki
2014-10-01
To control a quantum system via feedback, we generally have two options in choosing a control scheme. One is the coherent feedback, which feeds the output field of the system, through a fully quantum device, back to manipulate the system without involving any measurement process. The other one is measurement-based feedback, which measures the output field and performs a real-time manipulation on the system based on the measurement results. Both schemes have advantages and disadvantages, depending on the system and the control goal; hence, their comparison in several situations is important. This paper considers a general open linear quantum system with the following specific control goals: backaction evasion, generation of a quantum nondemolished variable, and generation of a decoherence-free subsystem, all of which have important roles in quantum information science. Some no-go theorems are proven, clarifying that those goals cannot be achieved by any measurement-based feedback control. On the other hand, it is shown that, for each control goal there exists a coherent feedback controller accomplishing the task. The key idea to obtain all the results is system theoretic characterizations of the above three notions in terms of controllability and observability properties or transfer functions of linear systems, which are consistent with their standard definitions.
The new control system of the Saclay Linear Accelerator
Gournay, J.F.; Garreau, F.; Giraud, A.; Gourcy, G.; Rouault, J.
1985-10-01
A new control system for the Saclay Linear Accelerator is now being designed. The computer control architecture is based on 3 dedicated VME crates with MC68000 micro-processors : one crate with a disk-based operating system will run the high level application programs and the data base management facilities, another one will manage the man-machine communications and the third one will interface the system to the linac equipments. Communications between the VME microcomputers will be done through 16 bit parallel links. The software is modular and organized in specific layers, the data base is fully distributed. About 90% of the code is written in Fortran.
Essential uncontrollability of discrete linear, time-invariant, dynamical systems
NASA Technical Reports Server (NTRS)
Cliff, E. M.
1975-01-01
The concept of a 'best approximating m-dimensional subspace' for a given set of vectors in n-dimensional whole space is introduced. Such a subspace is easily described in terms of the eigenvectors of an associated Gram matrix. This technique is used to approximate an achievable set for a discrete linear time-invariant dynamical system. This approximation characterizes the part of the state space that may be reached using modest levels of control. If the achievable set can be closely approximated by a proper subspace of the whole space then the system is 'essentially uncontrollable'. The notion finds application in studies of failure-tolerant systems, and in decoupling.
Steady-state decoupling and design of linear multivariable systems
NASA Technical Reports Server (NTRS)
Thaler, G. J.
1974-01-01
A constructive criterion for decoupling the steady states of a linear time-invariant multivariable system is presented. This criterion consists of a set of inequalities which, when satisfied, will cause the steady states of a system to be decoupled. Stability analysis and a new design technique for such systems are given. A new and simple connection between single-loop and multivariable cases is found. These results are then applied to the compensation design for NASA STOL C-8A aircraft. Both steady-state decoupling and stability are justified through computer simulations.
Chou, Yuan Hwa; Chu, Po-Chung; Wu, Szu-Wei; Lee, Jen-Chin; Lee, Yi-Hsuan; Sun, I-Wen; Chang, Chen-Lin; Huang, Chien-Liang; Liu, I-Chao; Tsai, Chia-Fen; Yen, Yung-Chieh
2015-01-01
Bipolar disorder (BD) is a major psychiatric disorder that is easily misdiagnosed. Patient adherence to a treatment regimen is of utmost importance for successful outcomes in BD. Several trials of antipsychotics suggested that depot antipsychotics, including long-acting first- and second-generation agents, are effective in preventing non-adherence, partial adherence, and in reducing relapse in BD. Various long-acting injectable (LAI) antipsychotics are available, including fluphenazine decanoate, haloperidol decanoate, olanzapine pamoate, risperidone microspheres, paliperidone palmitate, and aripiprazole monohydrate. Due to the increasing number of BD patients receiving LAI antipsychotics, treatment guidelines have been developed. However, the clinical applicability of LAI antipsychotics remains a global cause for concern, particularly in Asian countries. Expert physicians from Taiwan participated in a consensus meeting, which was held to review key areas based on both current literature and clinical practice. The purpose of this meeting was to generate a practical and implementable set of recommendations for LAI antipsychotic use to treat BD; target patient groups, dosage, administration, and adverse effects were considered. Experts recommended using LAI antipsychotics in patients with schizophrenia, rapid cycling BD, BD I, and bipolar-type schizoaffective disorder. LAI antipsychotic use was recommended in BD patients with the following characteristics: multiple episodes and low adherence; seldom yet serious episodes; low adherence potential per a physician’s clinical judgment; preference for injectable agents over oral agents; and multiple oral agent users still experiencing residual symptoms. PMID:26243837
Chou, Yuan Hwa; Chu, Po-Chung; Wu, Szu-Wei; Lee, Jen-Chin; Lee, Yi-Hsuan; Sun, I-Wen; Chang, Chen-Lin; Huang, Chien-Liang; Liu, I-Chao; Tsai, Chia-Fen; Yen, Yung-Chieh
2015-08-31
Bipolar disorder (BD) is a major psychiatric disorder that is easily misdiagnosed. Patient adherence to a treatment regimen is of utmost importance for successful outcomes in BD. Several trials of antipsychotics suggested that depot antipsychotics, including long-acting first- and second-generation agents, are effective in preventing non-adherence, partial adherence, and in reducing relapse in BD. Various long-acting injectable (LAI) antipsychotics are available, including fluphenazine decanoate, haloperidol decanoate, olanzapine pamoate, risperidone microspheres, paliperidone palmitate, and aripiprazole monohydrate. Due to the increasing number of BD patients receiving LAI antipsychotics, treatment guidelines have been developed. However, the clinical applicability of LAI antipsychotics remains a global cause for concern, particularly in Asian countries. Expert physicians from Taiwan participated in a consensus meeting, which was held to review key areas based on both current literature and clinical practice. The purpose of this meeting was to generate a practical and implementable set of recommendations for LAI antipsychotic use to treat BD; target patient groups, dosage, administration, and adverse effects were considered. Experts recommended using LAI antipsychotics in patients with schizophrenia, rapid cycling BD, BD I, and bipolar-type schizoaffective disorder. LAI antipsychotic use was recommended in BD patients with the following characteristics: multiple episodes and low adherence; seldom yet serious episodes; low adherence potential per a physician's clinical judgment; preference for injectable agents over oral agents; and multiple oral agent users still experiencing residual symptoms.
Solving Systems of Linear Equations with a Superconducting Quantum Processor
NASA Astrophysics Data System (ADS)
Zheng, Yarui; Song, Chao; Chen, Ming-Cheng; Xia, Benxiang; Liu, Wuxin; Guo, Qiujiang; Zhang, Libo; Xu, Da; Deng, Hui; Huang, Keqiang; Wu, Yulin; Yan, Zhiguang; Zheng, Dongning; Lu, Li; Pan, Jian-Wei; Wang, H.; Lu, Chao-Yang; Zhu, Xiaobo
2017-05-01
Superconducting quantum circuits are a promising candidate for building scalable quantum computers. Here, we use a four-qubit superconducting quantum processor to solve a two-dimensional system of linear equations based on a quantum algorithm proposed by Harrow, Hassidim, and Lloyd [Phys. Rev. Lett. 103, 150502 (2009), 10.1103/PhysRevLett.103.150502], which promises an exponential speedup over classical algorithms under certain circumstances. We benchmark the solver with quantum inputs and outputs, and characterize it by nontrace-preserving quantum process tomography, which yields a process fidelity of 0.837 ±0.006 . Our results highlight the potential of superconducting quantum circuits for applications in solving large-scale linear systems, a ubiquitous task in science and engineering.
SSNN toolbox for non-linear system identification
NASA Astrophysics Data System (ADS)
Luzar, Marcel; Czajkowski, Andrzej
2015-11-01
The aim of this paper is to develop and design a State Space Neural Network toolbox for a non-linear system identification with an artificial state-space neural networks, which can be used in a model-based robust fault diagnosis and control. Such toolbox is implemented in the MATLAB environment and it uses some of its predefined functions. It is designed in the way that any non-linear multi-input multi-output system is identified and represented in the classical state-space form. The novelty of the proposed approach is that the final result of the identification process is the state, input and output matrices, not only the neural network parameters. Moreover, the toolbox is equipped with the graphical user interface, which makes it useful for the users not familiar with the neural networks theory.
Solving Systems of Linear Equations with a Superconducting Quantum Processor.
Zheng, Yarui; Song, Chao; Chen, Ming-Cheng; Xia, Benxiang; Liu, Wuxin; Guo, Qiujiang; Zhang, Libo; Xu, Da; Deng, Hui; Huang, Keqiang; Wu, Yulin; Yan, Zhiguang; Zheng, Dongning; Lu, Li; Pan, Jian-Wei; Wang, H; Lu, Chao-Yang; Zhu, Xiaobo
2017-05-26
Superconducting quantum circuits are a promising candidate for building scalable quantum computers. Here, we use a four-qubit superconducting quantum processor to solve a two-dimensional system of linear equations based on a quantum algorithm proposed by Harrow, Hassidim, and Lloyd [Phys. Rev. Lett. 103, 150502 (2009)PRLTAO0031-900710.1103/PhysRevLett.103.150502], which promises an exponential speedup over classical algorithms under certain circumstances. We benchmark the solver with quantum inputs and outputs, and characterize it by nontrace-preserving quantum process tomography, which yields a process fidelity of 0.837±0.006. Our results highlight the potential of superconducting quantum circuits for applications in solving large-scale linear systems, a ubiquitous task in science and engineering.
Ultra-Precision Linear Actuator for optical systems
NASA Astrophysics Data System (ADS)
Nalbandian, Ruben
2000-10-01
The Ultra-Precision Linear Actuator presented in this paper was developed for the Next Generation Space Telescopes' (NGST) primary mirror surface figure control. The development was a joint effort between Alson E. Hatheway, Inc (AEH) and Moog, Schaeffer Magnetics Division (SMD). The goal of this project was to demonstrate an extremely light weight, relatively high stiffness actuator capable of operating uniformly well over the range of 2- degree(s)K to 300 degree(s)K and achieving diffraction-limited performance (+/- 10 nm) in the optical band for weeks at a time, while consuming no electrical power and dissipating no heat. The essence of the design challenge was to develop a lightweight, high stiffness, low power, thermally stable linear positioning mechanism. Actuation systems with resolutions comparable to that of this design normally are operated in a closed-loop control system to compensate for any non-linearities and hysteresis inherent in their enabling technologies, such as piezoelectric and magnetostrictive transducers. These technologies require continuous application of power and therefore are not low power consumption devices. The development challenge was met through the use of Alson E. Hatheway's (AEH) patented Rubicontm elastic transducer which consists of two elastic elements; a soft spring and a stiff flexural member. Deflection of the soft spring applies a force input to the stiff flexure, which responds with a proportionally reduced output deflection. To maintain linearity, the displacements, and hence the stresses, developed in both elastic members are kept well below the elastic yield strength of the material. The AEH transducer is inherently linear and hysteresis free.
A multi-level method for sparse linear systems
Shapira, Y.
1997-09-01
A multi-level method for the solution of sparse linear systems is introduced. The definition of the method is based on data from the coefficient matrix alone. An upper bound for the condition number is available for certain symmetric positive definite (SPD) problems. Numerical experiments confirm the analysis and illustrate the efficiency of the method for diffusion problems with discontinuous coefficients with discontinuities which are not aligned with the coarse meshes.
Linear Quantum Systems: Non-Classical States and Robust Stability
2016-06-29
basic importance to develop analysis and design methods that take uncertainty into account. Specifically, in the area of robust control for linear...show that the series product, which serves as an algebraic rule for connecting state-based input–output systems, is intimately related to the...Approved for public release: distribution unlimited. 7 commutation and anticommutation relations of the underlying algebra SU(n). Refereed Conference
Linear Quantum Systems: Non-Classical States and Robust Stability
2016-06-29
basic importance to develop analysis and design methods that take uncertainty into account. Specifically, in the area of robust control for linear...We show that the series product, which serves as an algebraic rule for connecting state-based input–output systems, is intimately related to the...Approved for public release: distribution unlimited. 7 commutation and anticommutation relations of the underlying algebra SU(n). Refereed
A Constraint Generation Approach to Learning Stable Linear Dynamical Systems
2008-01-01
and † denotes the Moore - Penrose inverse . Eq. (3) asks Â to minimize the error in predicting the state at time t + 1 from the state at time t. Given...A Constraint Generation Approach to Learning Stable Linear Dynamical Systems Sajid M. Siddiqi Byron Boots Geoffrey J. Gordon January 2008...REPORT DATE JAN 2008 2. REPORT TYPE 3. DATES COVERED 00-00-2008 to 00-00-2008 4. TITLE AND SUBTITLE A Constraint Generation Approach to Learning
AZTEC: A parallel iterative package for the solving linear systems
Hutchinson, S.A.; Shadid, J.N.; Tuminaro, R.S.
1996-12-31
We describe a parallel linear system package, AZTEC. The package incorporates a number of parallel iterative methods (e.g. GMRES, biCGSTAB, CGS, TFQMR) and preconditioners (e.g. Jacobi, Gauss-Seidel, polynomial, domain decomposition with LU or ILU within subdomains). Additionally, AZTEC allows for the reuse of previous preconditioning factorizations within Newton schemes for nonlinear methods. Currently, a number of different users are using this package to solve a variety of PDE applications.
Method of Conjugate Radii for Solving Linear and Nonlinear Systems
NASA Technical Reports Server (NTRS)
Nachtsheim, Philip R.
1999-01-01
This paper describes a method to solve a system of N linear equations in N steps. A quadratic form is developed involving the sum of the squares of the residuals of the equations. Equating the quadratic form to a constant yields a surface which is an ellipsoid. For different constants, a family of similar ellipsoids can be generated. Starting at an arbitrary point an orthogonal basis is constructed and the center of the family of similar ellipsoids is found in this basis by a sequence of projections. The coordinates of the center in this basis are the solution of linear system of equations. A quadratic form in N variables requires N projections. That is, the current method is an exact method. It is shown that the sequence of projections is equivalent to a special case of the Gram-Schmidt orthogonalization process. The current method enjoys an advantage not shared by the classic Method of Conjugate Gradients. The current method can be extended to nonlinear systems without modification. For nonlinear equations the Method of Conjugate Gradients has to be augmented with a line-search procedure. Results for linear and nonlinear problems are presented.
State feedback control of switched linear systems: An LMI approach
NASA Astrophysics Data System (ADS)
Montagner, V. F.; Leite, V. J. S.; Oliveira, R. C. L. F.; Peres, P. L. D.
2006-10-01
This paper addresses the problem of state feedback control of continuous-time switched linear systems with arbitrary switching rules. A quadratic Lyapunov function with a common matrix is used to derive a stabilizing switching control strategy that guarantees: (i) the assignment of all the eigenvalues of each linear subsystem inside a chosen circle in the left-hand half of the complex plane; (ii) a minimum disturbance attenuation level for the closed-loop switched system. The proposed design conditions are given in terms of linear matrix inequalities that encompass previous results based on quadratic stability conditions with fixed control gains. Although the quadratic stability based on a fixed Lyapunov matrix has been widely used in robust control design, the use of this condition to provide a convex design method for switching feedback gains has not been fully investigated. Numerical examples show that the switching control strategy can cope with more stringent design specifications than the fixed gain strategy, being useful to improve the performance of this class of systems.
A high linearity downconverter for digital broadcasting system
NASA Astrophysics Data System (ADS)
Songting, Li; Jiancheng, Li; Xiaochen, Gu; Hongyi, Wang; Zhaowen, Zhuang
2014-12-01
An integrated downconverter with high linearity for digital broadcasting system receivers is implemented in a 0.13 μm CMOS process with an active area of 0.1 mm2. The current-mode scheme is adopted to improve linearity performance by avoiding voltage fluctuation. A passive CMOS switching pair is utilized to improve the even-order linearity of the downconverter. A current amplifier is used to provide low input impedance which will easily lead to a wide operating bandwidth and high linearity. Moreover, a current-mode Sallen-Key low-pass filter is adopted for effective rejection of out-of-band interferers and also low input impedance. The digital-assisted DC offset calibration improves the second-order distortion of the downconverter. This design achieves a maximum gain of 40 dB and a dynamic range of 10 dB. Measured noise figure is 8.2 dB, an IIP2 of 63 dBm, an IIP3 of 17 dBm at the minimum gain of 30 dB. The downconverter consumes about 7.7 mA under a supply of 1.2 V.
Some generalisations of linear-graph modelling for dynamic systems
NASA Astrophysics Data System (ADS)
de Silva, Clarence W.; Pourazadi, Shahram
2013-11-01
Proper modelling of a dynamic system can benefit analysis, simulation, design, evaluation and control of the system. The linear-graph (LG) approach is suitable for modelling lumped-parameter dynamic systems. By using the concepts of graph trees, it provides a graphical representation of the system, with a direct correspondence to the physical component topology. This paper systematically extends the application of LGs to multi-domain (mixed-domain or multi-physics) dynamic systems by presenting a unified way to represent different domains - mechanical, electrical, thermal and fluid. Preservation of the structural correspondence across domains is a particular advantage of LGs when modelling mixed-domain systems. The generalisation of Thevenin and Norton equivalent circuits to mixed-domain systems, using LGs, is presented. The structure of an LG model may follow a specific pattern. Vector LGs are introduced to take advantage of such patterns, giving a general LG representation for them. Through these vector LGs, the model representation becomes simpler and rather compact, both topologically and parametrically. A new single LG element is defined to facilitate the modelling of distributed-parameter (DP) systems. Examples are presented using multi-domain systems (a motion-control system and a flow-controlled pump), a multi-body mechanical system (robot manipulator) and DP systems (structural rods) to illustrate the application and advantages of the methodologies developed in the paper.
Mathematical models of bipolar disorder
NASA Astrophysics Data System (ADS)
Daugherty, Darryl; Roque-Urrea, Tairi; Urrea-Roque, John; Troyer, Jessica; Wirkus, Stephen; Porter, Mason A.
2009-07-01
We use limit cycle oscillators to model bipolar II disorder, which is characterized by alternating hypomanic and depressive episodes and afflicts about 1% of the United States adult population. We consider two non-linear oscillator models of a single bipolar patient. In both frameworks, we begin with an untreated individual and examine the mathematical effects and resulting biological consequences of treatment. We also briefly consider the dynamics of interacting bipolar II individuals using weakly-coupled, weakly-damped harmonic oscillators. We discuss how the proposed models can be used as a framework for refined models that incorporate additional biological data. We conclude with a discussion of possible generalizations of our work, as there are several biologically-motivated extensions that can be readily incorporated into the series of models presented here.
A survey of packages for large linear systems
Wu, Kesheng; Milne, Brent
2000-02-11
This paper evaluates portable software packages for the iterative solution of very large sparse linear systems on parallel architectures. While we cannot hope to tell individual users which package will best suit their needs, we do hope that our systematic evaluation provides essential unbiased information about the packages and the evaluation process may serve as an example on how to evaluate these packages. The information contained here include feature comparisons, usability evaluations and performance characterizations. This review is primarily focused on self-contained packages that can be easily integrated into an existing program and are capable of computing solutions to very large sparse linear systems of equations. More specifically, it concentrates on portable parallel linear system solution packages that provide iterative solution schemes and related preconditioning schemes because iterative methods are more frequently used than competing schemes such as direct methods. The eight packages evaluated are: Aztec, BlockSolve,ISIS++, LINSOL, P-SPARSLIB, PARASOL, PETSc, and PINEAPL. Among the eight portable parallel iterative linear system solvers reviewed, we recommend PETSc and Aztec for most application programmers because they have well designed user interface, extensive documentation and very responsive user support. Both PETSc and Aztec are written in the C language and are callable from Fortran. For those users interested in using Fortran 90, PARASOL is a good alternative. ISIS++is a good alternative for those who prefer the C++ language. Both PARASOL and ISIS++ are relatively new and are continuously evolving. Thus their user interface may change. In general, those packages written in Fortran 77 are more cumbersome to use because the user may need to directly deal with a number of arrays of varying sizes. Languages like C++ and Fortran 90 offer more convenient data encapsulation mechanisms which make it easier to implement a clean and intuitive user
Long ion chamber systems for the SLC (Stanford Linear Collider)
Rolfe, J.; Gearhart, R.; Jacobsen, R.; Jenkins, T.; McComick, D.; Nelson, R.; Reagan, D.; Ross, M.
1989-03-01
A Panofsky Long Ion Chamber (PLIC) is essentially a gas-filled coaxial cable, and has been used to protect the Stanford Linear Accelerator from damage caused by its electron beam, and as a sensitive diagnostic tool. This old technology has been updated and has found renewed use in the SLC. PLIC systems have been installed as beam steering aids in most parts of the SLC and are a part of the system that protects the SLC from damage by errant beams in several places. 5 refs., 3 figs., 1 tab.
Beam-Based Feedback System for the International Linear Collider
NASA Astrophysics Data System (ADS)
Ivanov, Valentin
The algorithms and computer codes for linac Feedback system were developed at SLAC during 1991-2004. The efficiency of that system have been demonstrated for the SLC, CLIC, TESLA and NLC projects. International Linear Collider (ILC) has its own features. Ground motion (GM) oscillations play a dominant role here. It forced to implement a new version of the Linac Feedback Simulation Code based on the previous developments. A set of benchmark tests and realistic simulations for the whole ILC structure have been performed. The effects of different GM models, BPM resolution, time intervals, initial misalignments, a dispersion-free steering (DFS), and a quad jitter have been studied.
Critical electron binding to linear electric quadrupole systems.
Garrett, W R
2008-05-21
Results for critical quadrupolar moments for electron binding to fixed, point-charge systems are normalized, extended, and displayed in graphical forms. The influence of rotational degrees of freedom on critical binding to quadrupolar systems is examined through calculations of critical moments for electron binding to linear electric quadrupolar rotors. The results are presented for rotors covering useful ranges of size and inertial parameters. The effect of rotational degrees of freedom on critical binding is found to be less important for quadrupolar as compared to dipolar rotors.
Alloy, Lauren B.; Urošević, Snežana; Abramson, Lyn Y.; Jager-Hyman, Shari; Nusslock, Robin; Whitehouse, Wayne G.; Hogan, Michael
2011-01-01
Little longitudinal research has examined progression to more severe bipolar disorders in individuals with “soft” bipolar spectrum conditions. We examine rates and predictors of progression to bipolar I and II diagnoses in a non-patient sample of college-age participants (n = 201) with high General Behavior Inventory scores and childhood or adolescent onset of “soft” bipolar spectrum disorders followed longitudinally for 4.5 years from the Longitudinal Investigation of Bipolar Spectrum (LIBS) project. Of 57 individuals with initial cyclothymia or bipolar disorder not otherwise specified (BiNOS) diagnoses, 42.1% progressed to a bipolar II diagnosis and 10.5% progressed to a bipolar I diagnosis. Of 144 individuals with initial bipolar II diagnoses, 17.4% progressed to a bipolar I diagnosis. Consistent with hypotheses derived from the clinical literature and the Behavioral Approach System (BAS) model of bipolar disorder, and controlling for relevant variables (length of follow-up, initial depressive and hypomanic symptoms, treatment-seeking, and family history), high BAS sensitivity (especially BAS Fun Seeking) predicted a greater likelihood of progression to bipolar II disorder, whereas early age of onset and high impulsivity predicted a greater likelihood of progression to bipolar I (high BAS sensitivity and Fun-Seeking also predicted progression to bipolar I when family history was not controlled). The interaction of high BAS and high Behavioral Inhibition System (BIS) sensitivities also predicted greater likelihood of progression to bipolar I. We discuss implications of the findings for the bipolar spectrum concept, the BAS model of bipolar disorder, and early intervention efforts. PMID:21668080
Detecting and isolating abrupt changes in linear switching systems
NASA Astrophysics Data System (ADS)
Nazari, Sohail; Zhao, Qing; Huang, Biao
2015-04-01
In this paper, a novel fault detection and isolation (FDI) method for switching linear systems is developed. All input and output signals are assumed to be corrupted with measurement noises. In the proposed method, a 'lifted' linear model named as stochastic hybrid decoupling polynomial (SHDP) is introduced. The SHDP model governs the dynamics of the switching linear system with all different modes, and is independent of the switching sequence. The error-in-variable (EIV) representation of SHDP is derived, and is used for the fault residual generation and isolation following the well-adopted local approach. The proposed FDI method can detect and isolate the fault-induced abrupt changes in switching models' parameters without estimating the switching modes. Furthermore, in this paper, the analytical expressions of the gradient vector and Hessian matrix are obtained based on the EIV SHDP formulation, so that they can be used to implement the online fault detection scheme. The performance of the proposed method is then illustrated by simulation examples.
Distributed Control of Uncertain Systems using Superpositions of Linear operators
Sanger, Terence D.
2011-01-01
Control in the natural environment is difficult in part because of uncertainty in the effect of actions. Uncertainty can be due to added motor or sensory noise, unmodeled dynamics, or quantization of sensory feedback. Biological systems are faced with further difficulties, since control must be performed by networks of cooperating neurons and neural subsystems. Here, we propose a new mathematical framework for modeling and simulation of distributed control systems operating in an uncertain environment. Stochastic Differential Operators can be derived from the stochastic differential equation describing a system, and they map the current state density into the differential of the state density. Unlike discrete-time Markov update operators, stochastic differential operators combine linearly for a large class of linear and nonlinear systems, and therefore the combined effects of multiple controllable and uncontrollable subsystems can be predicted. Design using these operators yields systems whose statistical behavior can be specified throughout state space. The relationship to Bayesian estimation and discrete-time Markov processes is described. PMID:21521040
Distributed control of uncertain systems using superpositions of linear operators.
Sanger, Terence D
2011-08-01
Control in the natural environment is difficult in part because of uncertainty in the effect of actions. Uncertainty can be due to added motor or sensory noise, unmodeled dynamics, or quantization of sensory feedback. Biological systems are faced with further difficulties, since control must be performed by networks of cooperating neurons and neural subsystems. Here, we propose a new mathematical framework for modeling and simulation of distributed control systems operating in an uncertain environment. Stochastic differential operators can be derived from the stochastic differential equation describing a system, and they map the current state density into the differential of the state density. Unlike discrete-time Markov update operators, stochastic differential operators combine linearly for a large class of linear and nonlinear systems, and therefore the combined effects of multiple controllable and uncontrollable subsystems can be predicted. Design using these operators yields systems whose statistical behavior can be specified throughout state-space. The relationship to Bayesian estimation and discrete-time Markov processes is described.
Development of a linear induction motor based artificial muscle system.
Gruber, A; Arguello, E; Silva, R
2013-01-01
We present the design of a linear induction motor based on electromagnetic interactions. The engine is capable of producing a linear movement from electricity. The design consists of stators arranged in parallel, which produce a magnetic field sufficient to displace a plunger along its axial axis. Furthermore, the winding has a shell and cap of ferromagnetic material that amplifies the magnetic field. This produces a force along the length of the motor that is similar to that of skeletal muscle. In principle, the objective is to use the engine in the development of an artificial muscle system for prosthetic applications, but it could have multiple applications, not only in the medical field, but in other industries.
Thermoelectric effects in quantum Hall systems beyond linear response
NASA Astrophysics Data System (ADS)
López, Rosa; Hwang, Sun-Yong; Sánchez, David
2014-12-01
We consider a quantum Hall system with an antidot acting as a energy dependent scatterer. In the purely charge case, we find deviations from the Wiedemann-Franz law that take place in the nonlinear regime of transport. We also discuss Peltier effects beyond linear response and describe both effects using magnetic-field asymmetric transport coefficients. For the spin case such as that arising along the helical edge states of a two-dimensional topological insulator, we investigate the generation of spin currents as a result of applied voltage and temperature differences in samples attached to ferromagnetic leads. We find that in the parallel configuration the spin current can be tuned with the leads' polarization even in the linear regime of transport. In contrast, for antiparallel magnetizations the spin currents has a strict nonlinear dependence on the the applied fields.
Linear system identification via an asymptotically stable observer
NASA Technical Reports Server (NTRS)
Phan, Minh; Horta, Lucas G.; Juang, Jer-Nan; Longman, Richard W.
1991-01-01
This paper presents a formulation for identification of linear multivariable systems from single or multiple sets of input-output data. The system input-output relationship is expressed in terms of an observer, which is made asymptotically stable by an embedded eigenvalue assignment procedure. The prescribed eigenvalues for the observer may be real, complex, mixed real and complex, or zero. In this formulation, the Markov parameters of the observer are identified from input-output data. The Markov parameters of the actual system are then recovered from those of the observer, and used to obtain a state space model of the system by standard realization techniques. The basic mathematical formulation is derived, and numerical examples using simulated noise-free data are presented to illustrate the proposed method.
Indirect Identification of Linear Stochastic Systems with Known Feedback Dynamics
NASA Technical Reports Server (NTRS)
Huang, Jen-Kuang; Hsiao, Min-Hung; Cox, David E.
1996-01-01
An algorithm is presented for identifying a state-space model of linear stochastic systems operating under known feedback controller. In this algorithm, only the reference input and output of closed-loop data are required. No feedback signal needs to be recorded. The overall closed-loop system dynamics is first identified. Then a recursive formulation is derived to compute the open-loop plant dynamics from the identified closed-loop system dynamics and known feedback controller dynamics. The controller can be a dynamic or constant-gain full-state feedback controller. Numerical simulations and test data of a highly unstable large-gap magnetic suspension system are presented to demonstrate the feasibility of this indirect identification method.
Frequency weighted system identification and linear quadratic controller design
NASA Technical Reports Server (NTRS)
Horta, Lucas G.; Phan, Minh; Juang, Jer-Nan; Longman, Richard W.; Sulla, Jeffrey L.
1991-01-01
Application of filters for frequency weighting of Markov parameters (pulse response functions) is described in relation to system/observer identification. The time domain identification approach recovers a model which has a pulse response weighted according to frequency. The identified model is composed of the original system and filters. The augmented system is in a form which can be used directly for frequency weighted linear quadratic controller design. Data from either single or multiple experiments can be used to recover the Markov parameters. Measured acceleration signals from a truss structure are used for system identification and the model obtained is used for frequency weighted controller design. The procedure makes the identification and controler design complementary problems.
Identification of linear systems by an asymptotically stable observer
NASA Technical Reports Server (NTRS)
Phan, Minh Q.; Horta, Lucas G.; Juang, Jer-Nan; Longman, Richard W.
1992-01-01
A formulation is presented for the identification of a linear multivariable system from single or multiple sets of input-output data. The system input-output relationship is expressed in terms of an observer, which is made asymptotically stable by an embedded eigenvalue assignment procedure. The prescribed eigenvalues for the observer may be real, complex, mixed real and complex, or zero. In this formulation, the Markov parameters of the observer are identified from input-output data. The Markov parameters of the actual system are then recovered from those of the observer and used to obtain a state space model of the system by standard realization techniques. The basic mathematical formulation is derived, and extensive numerical examples using simulated noise-free data are presented to illustrate the proposed method.
Controlling coexisting attractors of an impacting system via linear augmentation
NASA Astrophysics Data System (ADS)
Liu, Yang; Páez Chávez, Joseph
2017-06-01
This paper studies the control of coexisting attractors in an impacting system via a recently developed control law based on linear augmentation. Special attention is given to two control issues in the framework of multistable engineering systems, namely, the switching between coexisting attractors without altering the system's main parameters and the avoidance of grazing-induced chaotic responses. The effectiveness of the proposed control scheme is confirmed numerically for the case of a periodically excited, soft impact oscillator. Our analysis shows how path-following techniques for non-smooth systems can be used in order to determine the optimal control parameters in terms of energy expenditure due to the control signal and transient behavior of the control error, which can be applied to a broad range of engineering problems.
A linear signal transmission system calibration method of wideband GPR
NASA Astrophysics Data System (ADS)
Wu, Bin; Zhao, Kai; Gu, Ling-jia; Cao, Qiong; Li, Xiao-feng; Zheng, Xing-ming
2016-09-01
In VHF pulse Ground Penetrating Radar(GPR) system, the echo pass through the antenna and transmission line circuit, then reach the GPR receiver. Thus the reflection coefficient at the receiver sampling gate interface, which is at the end of the transmission line, is different from the real reflection coefficient of the media at the antenna interface, which could cause the GPR receiving error. The pulse GPR receiver is a wideband system that can't be simply described as traditional narrowband transmission line model. Since the GPR transmission circuit is a linear system, the linear transformation method could be used to analyze the characteristic of the GPR receiving system. A GPR receiver calibration method based on transmission line theory is proposed in this paper, which analyzes the relationship between the reflection coefficients of theory calculation at antenna interface and the measuring data by network analyzer at the sampling gate interface. Then the least square method is introduced to calibrate the transfer function of the GPR receiver transmission circuit. This calibration method can be useful in media quantitative inversion by GPR. When the reflection coefficient at the sampling gate is obtained, the real reflection coefficient of the media at the antenna interface can be easily determined.
Linear systems formulation of non-paraxial scalar diffraction theory
NASA Astrophysics Data System (ADS)
Harvey, James E.
2011-10-01
Goodman's popular linear systems formulation of scalar diffraction theory includes a paraxial (small angle) approximation that severely limits the conditions under which this elegant Fourier treatment can be applied. In this paper a generalized linear systems formulation of non-paraxial scalar diffraction theory will be discussed. Diffracted radiance (not intensity or irradiance) is shown to be shift-invariant with respect to changes in incident angle only when modeled as a function of the direction cosines of the propagation vectors of the usual angular spectrum of plane waves. This revelation greatly extends the range of parameters over which simple Fourier techniques can be used to make accurate diffraction calculations. Non-paraxial diffraction grating behavior (including the Woods anomaly phenomenon) and wide-angle surface scattering effects for moderately rough surfaces at large incident and scattered angles are two diffraction phenomena that are not limited to the paraxial region and benefit greatly from this extension to Goodman's Fourier optics analysis. The resulting generalized surface scatter theory has been shown to be valid for rougher surfaces than the Rayleigh-Rice theory and for larger incident and scattered angles than the classical Beckman-Kirchhoff theory. This has enabled the development of a complete linear systems formulation of image quality, including not only diffraction effects and geometrical aberrations from residual optical design errors, but surface scatter effects from residual optical fabrication errors as well. Surface scatter effects can thus be balanced against optical design errors, allowing the derivation of optical fabrication tolerances during the design phase of a project.
Passive dynamic controllers for non-linear mechanical systems
NASA Technical Reports Server (NTRS)
Juang, Jer-Nan; Wu, Shih-Chin; Phan, Minh; Longman, Richard W.
1991-01-01
A methodology for model-independent controller design for controlling large angular motion of multi-body dynamic systems is outlined.The controlled system may consist of rigid and flexible components that undergo large rigid body motion and small elastic deformations. Control forces/torques are applied to drive the system, and at the same time suppress the vibrations due to flexibility of the components. The proposed controller consists of passive second-order systems which may be designed with little knowledge of the system parameters, even if the controlled system is non-linear. Under rather general assumptions, the passive design assures that the closed loop system has guaranteed stability properties. Unlike positive real controller design, stabilization can be accomplished without direct velocity feedback. In addition, the second-order passive design allows dynamic feedback controllers with considerable freedom to tune for desired system response, and to avoid actuator saturation. After developing the basic mathematical formulation of the design methodology, simulation results are presented to illustrate the proposed approach applied to a flexible six-degree-of-freedom manipulator.
Passive dynamic controllers for non-linear mechanical systems
NASA Technical Reports Server (NTRS)
Juang, Jer-Nan; Wu, Shih-Chin; Phan, Minh; Longman, Richard W.
1991-01-01
A methodology for model-independent controller design for controlling large angular motion of multi-body dynamic systems is outlined.The controlled system may consist of rigid and flexible components that undergo large rigid body motion and small elastic deformations. Control forces/torques are applied to drive the system, and at the same time suppress the vibrations due to flexibility of the components. The proposed controller consists of passive second-order systems which may be designed with little knowledge of the system parameters, even if the controlled system is non-linear. Under rather general assumptions, the passive design assures that the closed loop system has guaranteed stability properties. Unlike positive real controller design, stabilization can be accomplished without direct velocity feedback. In addition, the second-order passive design allows dynamic feedback controllers with considerable freedom to tune for desired system response, and to avoid actuator saturation. After developing the basic mathematical formulation of the design methodology, simulation results are presented to illustrate the proposed approach applied to a flexible six-degree-of-freedom manipulator.
Memristive non-linear system and hidden attractor
NASA Astrophysics Data System (ADS)
Saha, P.; Saha, D. C.; Ray, A.; Chowdhury, A. R.
2015-07-01
Effects of memristor on non-linear dynamical systems exhibiting chaos are analysed both form the view point of theory and experiment. It is observed that the memristive system has always fewer number of fixed points than the original one. Sometimes there is no fixed point in the memristive system. But its chaotic properties are retained. As such we have a situation known as hidden attractor because if it is a stable fixed point then the attractor does not evolve from its basin of attraction(obtained from its stable fixed point) or if there is no fixed point, the question of basin of attraction from fixed point does not arise at all [1, 2]. Our analysis gives a detailed accounts of properties related to its chaotic behavior. Important observations are also obtained with the help of electronic circuits to support the numerical simulations.
Damping Optimization for Linear Vibrating Systems Using Dimension Reduction
NASA Astrophysics Data System (ADS)
Benner, Peter; Tomljanović, Zoran; Truhar, Ninoslav
We consider a mathematical model of a linear vibrational system described by the second-order system of differential equations Mddot{x} + Ddot{x} + Kx = 0, where M, K and D are positive definite matrices, called mass, stiffness and damping, respectively. We are interested in finding an optimal damping matrix which will damp a certain part of the undamped eigenfrequencies. For this we use a minimization criterion which minimizes the average total energy of the system. This is equivalent to the minimization of the trace of the solution of a corresponding Lyapunov equation. In this paper we consider an algorithm for the efficient optimization of the damping positions based on dimension reduction techniques. Numerical results illustrate the efficiency of our approach.
Novel Approach to Linear Accelerator Superconducting Magnet System
Kashikhin, Vladimir; /Fermilab
2011-11-28
Superconducting Linear Accelerators include a superconducting magnet system for particle beam transportation that provides the beam focusing and steering. This system consists of a large number of quadrupole magnets and dipole correctors mounted inside or between cryomodules with SCRF cavities. Each magnet has current leads and powered from its own power supply. The paper proposes a novel approach to magnet powering based on using superconducting persistent current switches. A group of magnets is powered from the same power supply through the common, for the group of cryomodules, electrical bus and pair of current leads. Superconducting switches direct the current to the chosen magnet and close the circuit providing the magnet operation in a persistent current mode. Two persistent current switches were fabricated and tested. In the paper also presented the results of magnetic field simulations, decay time constants analysis, and a way of improving quadrupole magnetic center stability. Such approach substantially reduces the magnet system cost and increases the reliability.
High-yield positron systems for linear colliders
Clendenin, J.E.
1989-04-01
Linear colliders, such as the SLC, are among those accelerators for which a high-yield positron source operating at the repetition rate of the accelerator is desired. The SLC, having electron energies up to 50 GeV, presents the possibility of generating positron bunches with useful charge even exceeding that of the initial electron bunch. The exact positron yield to be obtained depends on the particular capture, transport and damping system employed. Using 31 GeV electrons impinging on a W-type converter phase-space at the target to the acceptance of the capture rf section, the SLC source is capable of producing, for every electron, up to two positrons within the acceptance of the positron damping ring. The design of this source and the performance of the positron system as built are described. Also, future prospects and limitations for high-yield positron systems are discussed. 11 refs., 5 figs., 3 tabs.
Acoustic FMRI noise: linear time-invariant system model.
Rizzo Sierra, Carlos V; Versluis, Maarten J; Hoogduin, Johannes M; Duifhuis, Hendrikus Diek
2008-09-01
Functional magnetic resonance imaging (fMRI) enables sites of brain activation to be localized in human subjects. For auditory system studies, however, the acoustic noise generated by the scanner tends to interfere with the assessments of this activation. Understanding and modeling fMRI acoustic noise is a useful step to its reduction. To study acoustic noise, the MR scanner is modeled as a linear electroacoustical system generating sound pressure signals proportional to the time derivative of the input gradient currents. The transfer function of one MR scanner is determined for two different input specifications: 1) by using the gradient waveform calculated by the scanner software and 2) by using a recording of the gradient current. Up to 4 kHz, the first method is shown as reliable as the second one, and its use is encouraged when direct measurements of gradient currents are not possible. Additionally, the linear order and average damping properties of the gradient coil system are determined by impulse response analysis. Since fMRI is often based on echo planar imaging (EPI) sequences, a useful validation of the transfer function prediction ability can be obtained by calculating the acoustic output for the EPI sequence. We found a predicted sound pressure level (SPL) for the EPI sequence of 104 dB SPL compared to a measured value of 102 dB SPL. As yet, the predicted EPI pressure waveform shows similarity as well as some differences with the directly measured EPI pressure waveform.
Evaluating linear response in active systems with no perturbing field
NASA Astrophysics Data System (ADS)
Szamel, Grzegorz
2017-03-01
We present a method for the evaluation of time-dependent linear response functions for systems of active particles propelled by a persistent (colored) noise from unperturbed simulations. The method is inspired by the Malliavin weights sampling method proposed by Warren and Allen (Phys. Rev. Lett., 109 (2012) 250601) for out-of-equilibrium systems of passive Brownian particles. We illustrate our method by evaluating two linear response functions for a single active particle in an external harmonic potential. As an application, we calculate the time-dependent mobility function and an effective temperature, defined through the Einstein relation between the self-diffusion and mobility coefficients, for a system of many active particles interacting via a screened Coulomb potential. We find that this effective temperature decreases with increasing persistence time of the self-propulsion. Initially, for not too large persistence times, it changes rather slowly, but then it decreases markedly when the persistence length of the self-propelled motion becomes comparable with the particle size.
Modelling human balance using switched systems with linear feedback control
Kowalczyk, Piotr; Glendinning, Paul; Brown, Martin; Medrano-Cerda, Gustavo; Dallali, Houman; Shapiro, Jonathan
2012-01-01
We are interested in understanding the mechanisms behind and the character of the sway motion of healthy human subjects during quiet standing. We assume that a human body can be modelled as a single-link inverted pendulum, and the balance is achieved using linear feedback control. Using these assumptions, we derive a switched model which we then investigate. Stable periodic motions (limit cycles) about an upright position are found. The existence of these limit cycles is studied as a function of system parameters. The exploration of the parameter space leads to the detection of multi-stability and homoclinic bifurcations. PMID:21697168
Neighboring extremal guidance for systems with a piecewise linear control
NASA Technical Reports Server (NTRS)
Hull, David G.; Helfrich, Clifford E.
1991-01-01
The neighboring extremal feedback control law is developed for systems with a piecewise linear control for the case where the optimal control is obtained by nonlinear programming techniques. To develop the control perturbation for a given deviation from the nominal path, the second variation is minimized subject to the constraint that the final conditions be satisfied. This process leads to a feedback relationship between the control perturbation and the measured deviation from the nominal state. A simple example, the lunar launch problem, is used to demonstrate the validity of the guidance law. For model errors on the order of 5 percent, the results indicate that 5 percent errors occur in the final conditions.
Steady state decoupling and design of linear multivariable systems
NASA Technical Reports Server (NTRS)
Huang, J. Y.; Thaler, G. J.
1974-01-01
A constructive criterion for decoupling the steady states of linear multivariable systems is developed. The criterion consists of n(n-1) inequalities with the type numbers of the compensator transfer functions as the unknowns. These unknowns can be chosen to satisfy the inequalities and hence achieve a steady state decoupling scheme. It turns out that pure integrators in the loops play an important role. An extended root locus design method is then developed to take care of the stability and transient response. The overall procedure is applied to the compensation design for STOL C-8A aircraft in the approach mode.
The effect of non-linear human visual system components on linear model observers
NASA Astrophysics Data System (ADS)
Zhang, Yani; Pham, Binh T.; Eckstein, Miguel P.
2004-05-01
Linear model observers have been used successfully to predict human performance in clinically relevant visual tasks for a variety of backgrounds. On the other hand, there has been another family of models used to predict human visual detection of signals superimposed on one of two identical backgrounds (masks). These masking models usually include a number of non-linear components in the channels that reflect properties of the firing of cells in the primary visual cortex (V1). The relationship between these two traditions of models has not been extensively investigated in the context of detection in noise. In this paper, we evaluated the effect of including some of these non-linear components into a linear channelized Hotelling observer (CHO), and the associated practical implications for medical image quality evaluation. In particular, we evaluate whether the rank order evaluation of two compression algorithms (JPEG vs. JPEG 2000) is changed by inclusion of the non-linear components. The results show: a) First that the simpler linear CHO model observer outperforms CHO model with the nonlinear components investigated. b) The rank order of model observer performance for the compression algorithms did not vary when the non-linear components were included. For the present task, the results suggest that the addition of the physiologically based channel non-linearities to a channelized Hotelling might add complexity to the model observers without great impact on medical image quality evaluation.
Prendergast, Claire Nicole
2016-06-01
This paper demonstrates that Kohut's definitional system of the "bipolar self" within psychoanalytic self psychology can be modeled as a biological autopoietic system, both in terms of its structure and dynamics, in a way that accounts for the phenomenological aspects of experiential living. Based on this finding, the author argues that a nonreductionist definitional system of this type is an integral component of any pragmatic methodology, such as Kohut's "empathic-introspective" method of treatment, which aims to enable the analyst, as observer, to gain access to the phenomenological world of the analysand within the analytic setting. The dialectic approach undertaken in this preliminary exploration of the "bipolar self" as an autopoietic system has proven fruitful in excavating some of the theoretical features of psychoanalytic self psychology, the weighted importance of which can now be reevaluated in contemporary practice.
The efficient parallel iterative solution of large sparse linear systems
Jones, M.T.; Plassmann, P.E.
1992-06-01
The development of efficient, general-purpose software for the iterative solution of sparse linear systems on a parallel MIMD computer requires an interesting combination of expertise. Parallel graph heuristics, convergence analysis, and basic linear algebra implementation issues must all be considered. In this paper, we discuss how we have incorporated recent results in these areas into a general-purpose iterative solver. First, we consider two recently developed parallel graph coloring heuristics. We show how the method proposed by Luby, based on determining maximal independent sets, can be modified to run in an asynchronous manner and give aa expected running time bound for this modified heuristic. In addition, a number of graph reduction heuristics are described that are used in our implementation to improve the individual processor performance. The effect of these various graph reductions on the solution of sparse triangular systems is categorized. Finally, we discuss the performance of this solver from the perspective of two large-scale applications: a piezoelectric crystal finite-element modeling problem, and a nonlinear optimization problem to determine the minimum energy configuration of a three-dimensional, layered superconductor model.
Solving tridiagonal linear systems on the Butterfly parallel computer
Kumar, S.P.
1989-01-01
A parallel block partitioning method to solve a tri-diagonal system of linear equations is adapted to the BBN Butterfly multiprocessor. A performance analysis of the programming experiments on the 32-node Butterfly is presented. An upper bound on the number of processors to achieve the best performance with this method is derived. The computational results verify the theoretical speedup and efficiency results of the parallel algorithm over its serial counterpart. Also included is a study comparing performance runs of the same code on the Butterfly processor with a hardware floating point unit and on one with a software floating point facility. The total parallel time of the given code is considerably reduced by making use of the hardware floating point facility whereas the speedup and efficiency of the parallel program considerably improve on the system with software floating point capability. The achieved results are shown to be within 82% to 90% of the predicted performance.
Elevated levels of urinary markers of oxidatively generated DNA and RNA damage in bipolar disorder.
Munkholm, Klaus; Poulsen, Henrik Enghusen; Kessing, Lars Vedel; Vinberg, Maj
2015-05-01
The pathophysiological mechanisms underlying bipolar disorder and its multi-system nature are unclear. Oxidatively generated damage to nucleosides has been demonstrated in metabolic disorders; however, the extent to which this occurs in bipolar disorder in vivo is unknown. We investigated oxidatively generated damage to DNA and RNA in patients with bipolar disorder and its relationship with the affective phase compared with healthy control subjects. Urinary excretion of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and 8-oxo-7,8-dihydroguanosine (8-oxoGuo), markers of oxidatively generated DNA and RNA damage, respectively, was measured in 37 rapid cycling patients with bipolar disorder and in 40 age- and gender-matched healthy control subjects. Employing a longitudinal design, repeated measurements of both markers were evaluated in various affective phases in patients with bipolar disorder during a six- to 12-month period and compared with repeated measurements in healthy control subjects. In linear mixed models, adjusting for demographical, metabolic, and lifestyle factors, the excretion of 8-oxodG and 8-oxoGuo was significantly elevated in euthymic patients with bipolar disorder compared with healthy control subjects, with increases of 40% (p < 0.0005) and 43% (p < 0.0005), respectively. The increased oxidatively generated nucleoside damage was present through all affective phases of the illness, with no significant difference between affective states. Our results indicate that bipolar disorder is associated with increased oxidatively generated damage to nucleosides. The findings could suggest a role for oxidatively generated damage to DNA and RNA as a molecular mechanism contributing to the increased risk of medical disorders, shortened life expectancy, and the progressive course of illness observed in bipolar disorder. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Linear theory for filtering nonlinear multiscale systems with model error
Berry, Tyrus; Harlim, John
2014-01-01
In this paper, we study filtering of multiscale dynamical systems with model error arising from limitations in resolving the smaller scale processes. In particular, the analysis assumes the availability of continuous-time noisy observations of all components of the slow variables. Mathematically, this paper presents new results on higher order asymptotic expansion of the first two moments of a conditional measure. In particular, we are interested in the application of filtering multiscale problems in which the conditional distribution is defined over the slow variables, given noisy observation of the slow variables alone. From the mathematical analysis, we learn that for a continuous time linear model with Gaussian noise, there exists a unique choice of parameters in a linear reduced model for the slow variables which gives the optimal filtering when only the slow variables are observed. Moreover, these parameters simultaneously give the optimal equilibrium statistical estimates of the underlying system, and as a consequence they can be estimated offline from the equilibrium statistics of the true signal. By examining a nonlinear test model, we show that the linear theory extends in this non-Gaussian, nonlinear configuration as long as we know the optimal stochastic parametrization and the correct observation model. However, when the stochastic parametrization model is inappropriate, parameters chosen for good filter performance may give poor equilibrium statistical estimates and vice versa; this finding is based on analytical and numerical results on our nonlinear test model and the two-layer Lorenz-96 model. Finally, even when the correct stochastic ansatz is given, it is imperative to estimate the parameters simultaneously and to account for the nonlinear feedback of the stochastic parameters into the reduced filter estimates. In numerical experiments on the two-layer Lorenz-96 model, we find that the parameters estimated online, as part of a filtering procedure
Early-Onset Bipolar Disorder: Characteristics and Outcomes in the Clinic.
Connor, Daniel F; Ford, Julian D; Pearson, Geraldine S; Scranton, Victoria L; Dusad, Asha
2017-08-22
To assess patient characteristics and clinician-rated outcomes for children diagnosed with early-onset bipolar disorder in comparison to a depressive disorders cohort from a single clinic site. To assess predictors of bipolar treatment response. Medical records from 714 consecutive pediatric patients evaluated and treated at an academic tertiary child and adolescent psychiatry clinic between 2006 and 2012 were reviewed. Charts of bipolar children (n = 49) and children with depressive disorders (n = 58) meeting study inclusion/exclusion criteria were compared on variables assessing clinical characteristics, treatments, and outcomes. Outcomes were assessed by using pre- and post-Clinical Global Impressions (CGI)-Severity and Children's Global Assessment Scale (CGAS) scores, and a CGI-Improvement score ≤2 at final visit determined responder status. Bipolar outcome predictors were assessed by using multiple linear regression. Clinic prevalence rates were 6.9% for early-onset bipolar disorder and 1.5% for very early-onset bipolar disorder. High rates of comorbid diagnoses, symptom severity, parental stress, and child high-risk behaviors were found in both groups. The bipolar cohort had higher rates of aggression and higher lifetime systems of care utilization. The final CGI and CGAS outcomes for unipolar depression patients differed statistically significantly from those for the bipolar cohort, reflecting better clinical status and more improvement at outcome for the depression patients. Both parent-reported Child Behavior Checklist total T-score at clinic admission and the number of lifetime systems-of-care for the child were significantly and inversely associated with improvement for the bipolar cohort. Early-onset bipolar disorder is a complex and heterogeneous psychiatric disorder. Evidence-based treatment should emphasize psychopharmacology with adjunctive family and individual psychotherapy. Strategies to improve engagement in treatment may be especially
Linear operating region in the ozone dial photon counting system
NASA Technical Reports Server (NTRS)
Andrawis, Madeleine
1995-01-01
Ozone is a relatively unstable molecule found in Earth's atmosphere. An ozone molecule is made up of three atoms of oxygen. Depending on where ozone resides, it can protect or harm life on Earth. High in the atmosphere, about 15 miles up, ozone acts as a shield to protect Earth's surface from the sun's harmful ultraviolet radiation. Without this shield, we would be more susceptible to skin cancer, cataracts, and impaired immune systems. Closer to Earth, in the air we breathe, ozone is a harmful pollutant that causes damage to lung tissue and plants. Since the early 1980's, airborne lidar systems have been used for making measurements of ozone. The differential absorption lidar (DIAL) technique is used in the remote measurement of O3. This system allows the O3 to be measured as function of the range in the atmosphere. Two frequency-doubled Nd:YAG lasers are used to pump tunable dye lasers. The lasers are operating at 289 nm for the DIAL on-line wavelength of O3, and the other one is operated at 300 nm for the off-line wavelength. The DIAL wavelengths are produced in sequential laser pulses with a time separation of 300 micro s. The backscattered laser energy is collected by telescopes and measured using photon counting systems. The photon counting system measures the light signal by making use of the photon nature of light. The output pulse from the Photo-Multiplier Tube (PE), caused by a photon striking the PMT photo-cathode, is amplified and passed to a pulse height discriminator. The peak value of the pulse is compared to a reference voltage (discrimination level). If the pulse amplitude exceeds the discrimination level, the discriminator generates a standard pulse which is counted by the digital counter. Non-linearity in the system is caused by the overlapping of pulses and the finite response time of the electronics. At low count rates one expects the system to register one event for each output pulse from the PMT corresponding to a photon incident upon the
Linear operating region in the ozone dial photon counting system
NASA Technical Reports Server (NTRS)
Andrawis, Madeleine
1995-01-01
Ozone is a relatively unstable molecule found in Earth's atmosphere. An ozone molecule is made up of three atoms of oxygen. Depending on where ozone resides, it can protect or harm life on Earth. High in the atmosphere, about 15 miles up, ozone acts as a shield to protect Earth's surface from the sun's harmful ultraviolet radiation. Without this shield, we would be more susceptible to skin cancer, cataracts, and impaired immune systems. Closer to Earth, in the air we breathe, ozone is a harmful pollutant that causes damage to lung tissue and plants. Since the early 1980's, airborne lidar systems have been used for making measurements of ozone. The differential absorption lidar (DIAL) technique is used in the remote measurement of O3. This system allows the O3 to be measured as function of the range in the atmosphere. Two frequency-doubled Nd:YAG lasers are used to pump tunable dye lasers. The lasers are operating at 289 nm for the DIAL on-line wavelength of O3, and the other one is operated at 300 nm for the off-line wavelength. The DIAL wavelengths are produced in sequential laser pulses with a time separation of 300 micro s. The backscattered laser energy is collected by telescopes and measured using photon counting systems. The photon counting system measures the light signal by making use of the photon nature of light. The output pulse from the Photo-Multiplier Tube (PE), caused by a photon striking the PMT photo-cathode, is amplified and passed to a pulse height discriminator. The peak value of the pulse is compared to a reference voltage (discrimination level). If the pulse amplitude exceeds the discrimination level, the discriminator generates a standard pulse which is counted by the digital counter. Non-linearity in the system is caused by the overlapping of pulses and the finite response time of the electronics. At low count rates one expects the system to register one event for each output pulse from the PMT corresponding to a photon incident upon the
Energy and environmental analysis of a linear concentrating photovoltaic system
NASA Astrophysics Data System (ADS)
Kerzmann, Tony
The world is facing an imminent energy supply crisis. In order to sustain and increase our energy supply in an environmentally-conscious manner, it is necessary to advance renewable technologies. Despite this urgency, however, it is paramount to consider the larger environmental effects associated with using renewable energy resources. This research is meant to better understand linear concentrating photovoltaics (LCPVs) from an engineering and environmental standpoint. In order to analyze the LCPV system, a simulation and life cycle assessment (LCA) were developed. The LCPV system serves two major purposes: it produces electricity, and waste heat is collected for heating use. There are three parts to the LCPV simulation. The first part simulates the multijunction cell output so as to calculate the temperature-dependent electricity generation. The second part simulates the cell cooling and waste heat recovery system using a model consisting of heat transfer and fluid flow equations. The waste heat recovery in the LCPV system was linked to a hot water storage system, which was also modeled. Coupling the waste heat recovery simulation and the hot water storage system gives an overall integrated system that is useful for system design, optimization, and acts as a stepping stone for future multijunction cell Photovoltaic/Thermal (PV/T) systems. Finally, all of the LCPV system components were coded in Engineering Equation Solver (EES) and were used in an energy analysis under actual weather and solar conditions for the Phoenix, AZ, region. The life cycle assessment for the LCPV system allowed for an environmental analysis of the system where areas of the highest environmental impact were pinpointed. While conducting the LCA research, each component of the system was analyzed from a resource extraction, production, and use standpoint. The collective production processes of each LCPV system component were gathered into a single inventory of materials and energy flows
Linear homotopy solution of nonlinear systems of equations in geodesy
NASA Astrophysics Data System (ADS)
Paláncz, Béla; Awange, Joseph L.; Zaletnyik, Piroska; Lewis, Robert H.
2010-01-01
A fundamental task in geodesy is solving systems of equations. Many geodetic problems are represented as systems of multivariate polynomials. A common problem in solving such systems is improper initial starting values for iterative methods, leading to convergence to solutions with no physical meaning, or to convergence that requires global methods. Though symbolic methods such as Groebner bases or resultants have been shown to be very efficient, i.e., providing solutions for determined systems such as 3-point problem of 3D affine transformation, the symbolic algebra can be very time consuming, even with special Computer Algebra Systems (CAS). This study proposes the Linear Homotopy method that can be implemented easily in high-level computer languages like C++ and Fortran that are faster than CAS by at least two orders of magnitude. Using Mathematica, the power of Homotopy is demonstrated in solving three nonlinear geodetic problems: resection, GPS positioning, and affine transformation. The method enlarging the domain of convergence is found to be efficient, less sensitive to rounding of numbers, and has lower complexity compared to other local methods like Newton-Raphson.
Predictability of extremes in non-linear hierarchically organized systems
NASA Astrophysics Data System (ADS)
Kossobokov, V. G.; Soloviev, A.
2011-12-01
Understanding the complexity of non-linear dynamics of hierarchically organized systems progresses to new approaches in assessing hazard and risk of the extreme catastrophic events. In particular, a series of interrelated step-by-step studies of seismic process along with its non-stationary though self-organized behaviors, has led already to reproducible intermediate-term middle-range earthquake forecast/prediction technique that has passed control in forward real-time applications during the last two decades. The observed seismic dynamics prior to and after many mega, great, major, and strong earthquakes demonstrate common features of predictability and diverse behavior in course durable phase transitions in complex hierarchical non-linear system of blocks-and-faults of the Earth lithosphere. The confirmed fractal nature of earthquakes and their distribution in space and time implies that many traditional estimations of seismic hazard (from term-less to short-term ones) are usually based on erroneous assumptions of easy tractable analytical models, which leads to widespread practice of their deceptive application. The consequences of underestimation of seismic hazard propagate non-linearly into inflicted underestimation of risk and, eventually, into unexpected societal losses due to earthquakes and associated phenomena (i.e., collapse of buildings, landslides, tsunamis, liquefaction, etc.). The studies aimed at forecast/prediction of extreme events (interpreted as critical transitions) in geophysical and socio-economical systems include: (i) large earthquakes in geophysical systems of the lithosphere blocks-and-faults, (ii) starts and ends of economic recessions, (iii) episodes of a sharp increase in the unemployment rate, (iv) surge of the homicides in socio-economic systems. These studies are based on a heuristic search of phenomena preceding critical transitions and application of methodologies of pattern recognition of infrequent events. Any study of rare
Filtering nonlinear dynamical systems with linear stochastic models
NASA Astrophysics Data System (ADS)
Harlim, J.; Majda, A. J.
2008-06-01
An important emerging scientific issue is the real time filtering through observations of noisy signals for nonlinear dynamical systems as well as the statistical accuracy of spatio-temporal discretizations for filtering such systems. From the practical standpoint, the demand for operationally practical filtering methods escalates as the model resolution is significantly increased. For example, in numerical weather forecasting the current generation of global circulation models with resolution of 35 km has a total of billions of state variables. Numerous ensemble based Kalman filters (Evensen 2003 Ocean Dyn. 53 343-67 Bishop et al 2001 Mon. Weather Rev. 129 420-36 Anderson 2001 Mon. Weather Rev. 129 2884-903 Szunyogh et al 2005 Tellus A 57 528-45 Hunt et al 2007 Physica D 230 112-26) show promising results in addressing this issue; however, all these methods are very sensitive to model resolution, observation frequency, and the nature of the turbulent signals when a practical limited ensemble size (typically less than 100) is used. In this paper, we implement a radical filtering approach to a relatively low (40) dimensional toy model, the L-96 model (Lorenz 1996 Proc. on Predictability (ECMWF, 4-8 September 1995) pp 1-18) in various chaotic regimes in order to address the 'curse of ensemble size' for complex nonlinear systems. Practically, our approach has several desirable features such as extremely high computational efficiency, filter robustness towards variations of ensemble size (we found that the filter is reasonably stable even with a single realization) which makes it feasible for high dimensional problems, and it is independent of any tunable parameters such as the variance inflation coefficient in an ensemble Kalman filter. This radical filtering strategy decouples the problem of filtering a spatially extended nonlinear deterministic system to filtering a Fourier diagonal system of parametrized linear stochastic differential equations (Majda and Grote
Control methods to improve non-linear HVAC system operations
NASA Astrophysics Data System (ADS)
Phalak, Kaustubh Pradeep
The change of weather conditions and occupancy schedules makes heating ventilating and air-conditioning (HVAC) systems heavily dynamic. The mass and thermal inertia, nonlinear characteristics and interactions in HVAC systems make the control more complicated. As a result, some conventional control methods often cannot provide desired control performance under variable operating conditions. The purpose of this study is to develop control methods to improve the control performance of HVAC systems. This study focuses on optimizing the airflow-pressure control method of air side economizers, identifying robust building pressurization controls, developing a control method to control outdoor air and building pressure in absence of flow and pressure sensors, stabilizing the cooling coil valve operation and, return fan speed control. The improvements can be achieved by identifying and selecting a method with relatively linear performance characteristics out of the available options, applying fans rather than dampers to control building pressure, and improving the controller's stability range using cascade control method. A steady state nonlinear network model, for an air handling unit (AHU), air distribution system and conditioned space, is applied to analyze the system control performance of air-side economizers and building pressurization. The study shows that traditional controls with completely interlinked outdoor air, recirculated air, relief air dampers have the best control performance. The decoupled relief damper control may result in negative building static pressure at lower outdoor airflow ratio and excessively positive building static pressure at higher outdoor airflow ratio. On the other hand, return fan speed control has a better controllability on building pressurization. In absence of flow and pressure sensors fixed interlinked damper and linear return fan speed tracking control can maintain constant outside air ratio and positive building pressure. The
Domain walls and vortices in linearly coupled systems.
Dror, Nir; Malomed, Boris A; Zeng, Jianhua
2011-10-01
We investigate one- and two-dimensional radial domain-wall (DW) states in the system of two nonlinear-Schrödinger (NLS) or Gross-Pitaevskii (GP) equations, which are couple by linear mixing and by nonlinear XPM (cross-phase-modulation). The system has straightforward applications to two-component Bose-Einstein condensates, and to bimodal light propagation in nonlinear optics. In the former case the two components represent different hyperfine atomic states, while in the latter setting they correspond to orthogonal polarizations of light. Conditions guaranteeing the stability of flat continuous wave (CW) asymmetric bimodal states are established, followed by the study of families of the corresponding DW patterns. Approximate analytical solutions for the DWs are found near the point of the symmetry-breaking bifurcation of the CW states. An exact DW solution is produced for ratio 3:1 of the XPM and SPM (self-phase modulation) coefficients. The DWs between flat asymmetric states, which are mirror images of each other, are completely stable, and all other species of the DWs, with zero crossings in one or two components, are fully unstable. Interactions between two DWs are considered too, and an effective potential accounting for the attraction between them is derived analytically. Direct simulations demonstrate merger and annihilation of the interacting DWs. The analysis is extended for the system including single- and double-peak external potentials. Generic solutions for trapped DWs are obtained in a numerical form, and their stability is investigated. An exact stable solution is found for the DW trapped by a single-peak potential. In the 2D geometry, stable two-component vortices are found, with topological charges s=1,2,3. Radial oscillations of annular DW-shaped pulsons, with s=0,1,2, are studied too. A linear relation between the period of the oscillations and the mean radius of the DW ring is derived analytically.
Three-dimensional linear system analysis for breast tomosynthesis.
Zhao, Bo; Zhao, Wei
2008-12-01
The optimization of digital breast tomosynthesis (DBT) geometry and reconstruction is crucial for the clinical translation of this exciting new imaging technique. In the present work, the authors developed a three-dimensional (3D) cascaded linear system model for DBT to investigate the effects of detector performance, imaging geometry, and image reconstruction algorithm on the reconstructed image quality. The characteristics of a prototype DBT system equipped with an amorphous selenium flat-panel detector and filtered backprojection reconstruction were used as an example in the implementation of the linear system model. The propagation of signal and noise in the frequency domain was divided into six cascaded stages incorporating the detector performance, imaging geometry, and reconstruction filters. The reconstructed tomosynthesis imaging quality was characterized by spatial frequency dependent presampling modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE) in 3D. The results showed that both MTF and NPS were affected by the angular range of the tomosynthesis scan and the reconstruction filters. For image planes parallel to the detector (in-plane), MTF at low frequencies was improved with increase in angular range. The shape of the NPS was affected by the reconstruction filters. Noise aliasing in 3D could be introduced by insufficient voxel sampling, especially in the z (slice-thickness) direction where the sampling distance (slice thickness) could be more than ten times that for in-plane images. Aliasing increases the noise at high frequencies, which causes degradation in DQE. Application of a reconstruction filter that limits the frequency components beyond the Nyquist frequency in the z direction, referred to as the slice thickness filter, eliminates noise aliasing and improves 3D DQE. The focal spot blur, which arises from continuous tube travel during tomosynthesis acquisition, could degrade DQE significantly
Domain walls and vortices in linearly coupled systems
Dror, Nir; Malomed, Boris A.; Zeng Jianhua
2011-10-15
We investigate one- and two-dimensional radial domain-wall (DW) states in the system of two nonlinear-Schroedinger (NLS) or Gross-Pitaevskii (GP) equations, which are couple by linear mixing and by nonlinear XPM (cross-phase-modulation). The system has straightforward applications to two-component Bose-Einstein condensates, and to bimodal light propagation in nonlinear optics. In the former case the two components represent different hyperfine atomic states, while in the latter setting they correspond to orthogonal polarizations of light. Conditions guaranteeing the stability of flat continuous wave (CW) asymmetric bimodal states are established, followed by the study of families of the corresponding DW patterns. Approximate analytical solutions for the DWs are found near the point of the symmetry-breaking bifurcation of the CW states. An exact DW solution is produced for ratio 3:1 of the XPM and SPM (self-phase modulation) coefficients. The DWs between flat asymmetric states, which are mirror images of each other, are completely stable, and all other species of the DWs, with zero crossings in one or two components, are fully unstable. Interactions between two DWs are considered too, and an effective potential accounting for the attraction between them is derived analytically. Direct simulations demonstrate merger and annihilation of the interacting DWs. The analysis is extended for the system including single- and double-peak external potentials. Generic solutions for trapped DWs are obtained in a numerical form, and their stability is investigated. An exact stable solution is found for the DW trapped by a single-peak potential. In the 2D geometry, stable two-component vortices are found, with topological charges s=1,2,3. Radial oscillations of annular DW-shaped pulsons, with s=0,1,2, are studied too. A linear relation between the period of the oscillations and the mean radius of the DW ring is derived analytically.
Three-dimensional linear system analysis for breast tomosynthesis
Zhao, Bo; Zhao, Wei
2008-01-01
The optimization of digital breast tomosynthesis (DBT) geometry and reconstruction is crucial for the clinical translation of this exciting new imaging technique. In the present work, the authors developed a three-dimensional (3D) cascaded linear system model for DBT to investigate the effects of detector performance, imaging geometry, and image reconstruction algorithm on the reconstructed image quality. The characteristics of a prototype DBT system equipped with an amorphous selenium flat-panel detector and filtered backprojection reconstruction were used as an example in the implementation of the linear system model. The propagation of signal and noise in the frequency domain was divided into six cascaded stages incorporating the detector performance, imaging geometry, and reconstruction filters. The reconstructed tomosynthesis imaging quality was characterized by spatial frequency dependent presampling modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE) in 3D. The results showed that both MTF and NPS were affected by the angular range of the tomosynthesis scan and the reconstruction filters. For image planes parallel to the detector (in-plane), MTF at low frequencies was improved with increase in angular range. The shape of the NPS was affected by the reconstruction filters. Noise aliasing in 3D could be introduced by insufficient voxel sampling, especially in the z (slice-thickness) direction where the sampling distance (slice thickness) could be more than ten times that for in-plane images. Aliasing increases the noise at high frequencies, which causes degradation in DQE. Application of a reconstruction filter that limits the frequency components beyond the Nyquist frequency in the z direction, referred to as the slice thickness filter, eliminates noise aliasing and improves 3D DQE. The focal spot blur, which arises from continuous tube travel during tomosynthesis acquisition, could degrade DQE significantly
Jiang, J; Ma, G M; Luo, D P; Li, C R; Li, Q M; Wang, W
2014-02-01
Damped AC voltages detection system (DAC) is a productive way to detect the faults in power cables. To solve the problems of large volume, complicated structure and electromagnetic interference in existing switches, this paper developed a compact solid state switch based on electromagnetic trigger, which is suitable for DAC test system. Synchronous electromagnetic trigger of 32 Insulated Gate Bipolar Transistors (IGBTs) in series was realized by the topological structure of single line based on pulse width modulation control technology. In this way, external extension was easily achieved. Electromagnetic trigger and resistor-capacitor-diode snubber circuit were optimized to reduce the switch turn-on time and circular layout. Epoxy encapsulating was chosen to enhance the level of partial discharge initial voltage (PDIV). The combination of synchronous trigger and power supply is proposed to reduce the switch volume. Moreover, we have overcome the drawback of the electromagnetic interference and improved the detection sensitivity of DAC by using capacitor storage energy to maintain IGBT gate driving voltage. The experimental results demonstrated that the solid-state switch, with compact size, whose turn-on time was less than 400 ns and PDIV was more than 65 kV, was able to meet the actual demands of 35 kV DAC test system.
NASA Astrophysics Data System (ADS)
Jiang, J.; Ma, G. M.; Luo, D. P.; Li, C. R.; Li, Q. M.; Wang, W.
2014-02-01
Damped AC voltages detection system (DAC) is a productive way to detect the faults in power cables. To solve the problems of large volume, complicated structure and electromagnetic interference in existing switches, this paper developed a compact solid state switch based on electromagnetic trigger, which is suitable for DAC test system. Synchronous electromagnetic trigger of 32 Insulated Gate Bipolar Transistors (IGBTs) in series was realized by the topological structure of single line based on pulse width modulation control technology. In this way, external extension was easily achieved. Electromagnetic trigger and resistor-capacitor-diode snubber circuit were optimized to reduce the switch turn-on time and circular layout. Epoxy encapsulating was chosen to enhance the level of partial discharge initial voltage (PDIV). The combination of synchronous trigger and power supply is proposed to reduce the switch volume. Moreover, we have overcome the drawback of the electromagnetic interference and improved the detection sensitivity of DAC by using capacitor storage energy to maintain IGBT gate driving voltage. The experimental results demonstrated that the solid-state switch, with compact size, whose turn-on time was less than 400 ns and PDIV was more than 65 kV, was able to meet the actual demands of 35 kV DAC test system.
Locally weighted linear combination in a vector geographic information system
NASA Astrophysics Data System (ADS)
Carter, Brad; Rinner, Claus
2014-07-01
Weighted linear combination is a multi-criteria decision analysis technique that can be used by decision-makers to select an optimal location from a collection of alternative locations. Its local form takes into account the range of attribute values within a user-defined neighbourhood in accordance with the range-sensitivity principle. This research explores locally weighted linear combination in a vector-based geographic information system. A custom application in ArcGIS 10 allows the user to select a neighbourhood definition from a standard set including contiguity, distance, and k-nearest neighbours, for which local weights are generated. A case study on vulnerability to heat-related illness in Toronto is used to illustrate the technique. The impact of local weighting on the heat vulnerability index is examined using visual analysis of the spatial patterns of heat vulnerability under the global and local approaches, as well as the sensitivity of the local approach to the selected neighbourhood definition. A trade-off analysis of the local weights is also presented. The combination of socio-demographic and environmental determinants in a locally weighted index results in patterns of heat vulnerability that could support targeted hot weather response at a micro-geographic level within urban neighbourhoods.
Altered visual information processing systems in bipolar disorder: evidence from visual MMN and P3
Maekawa, Toshihiko; Katsuki, Satomi; Kishimoto, Junji; Onitsuka, Toshiaki; Ogata, Katsuya; Yamasaki, Takao; Ueno, Takefumi; Tobimatsu, Shozo; Kanba, Shigenobu
2013-01-01
Objective: Mismatch negativity (MMN) and P3 are unique ERP components that provide objective indices of human cognitive functions such as short-term memory and prediction. Bipolar disorder (BD) is an endogenous psychiatric disorder characterized by extreme shifts in mood, energy, and ability to function socially. BD patients usually show cognitive dysfunction, and the goal of this study was to access their altered visual information processing via visual MMN (vMMN) and P3 using windmill pattern stimuli. Methods: Twenty patients with BD and 20 healthy controls matched for age, gender, and handedness participated in this study. Subjects were seated in front of a monitor and listened to a story via earphones. Two types of windmill patterns (standard and deviant) and white circle (target) stimuli were randomly presented on the monitor. All stimuli were presented in random order at 200-ms durations with an 800-ms inter-stimulus interval. Stimuli were presented at 80% (standard), 10% (deviant), and 10% (target) probabilities. The participants were instructed to attend to the story and press a button as soon as possible when the target stimuli were presented. Event-related potentials (ERPs) were recorded throughout the experiment using 128-channel EEG equipment. vMMN was obtained by subtracting standard from deviant stimuli responses, and P3 was evoked from the target stimulus. Results: Mean reaction times for target stimuli in the BD group were significantly higher than those in the control group. Additionally, mean vMMN-amplitudes and peak P3-amplitudes were significantly lower in the BD group than in controls. Conclusions: Abnormal vMMN and P3 in patients indicate a deficit of visual information processing in BD, which is consistent with their increased reaction time to visual target stimuli. Significance: Both bottom-up and top-down visual information processing are likely altered in BD. PMID:23898256
Altered visual information processing systems in bipolar disorder: evidence from visual MMN and P3.
Maekawa, Toshihiko; Katsuki, Satomi; Kishimoto, Junji; Onitsuka, Toshiaki; Ogata, Katsuya; Yamasaki, Takao; Ueno, Takefumi; Tobimatsu, Shozo; Kanba, Shigenobu
2013-01-01
Mismatch negativity (MMN) and P3 are unique ERP components that provide objective indices of human cognitive functions such as short-term memory and prediction. Bipolar disorder (BD) is an endogenous psychiatric disorder characterized by extreme shifts in mood, energy, and ability to function socially. BD patients usually show cognitive dysfunction, and the goal of this study was to access their altered visual information processing via visual MMN (vMMN) and P3 using windmill pattern stimuli. Twenty patients with BD and 20 healthy controls matched for age, gender, and handedness participated in this study. Subjects were seated in front of a monitor and listened to a story via earphones. Two types of windmill patterns (standard and deviant) and white circle (target) stimuli were randomly presented on the monitor. All stimuli were presented in random order at 200-ms durations with an 800-ms inter-stimulus interval. Stimuli were presented at 80% (standard), 10% (deviant), and 10% (target) probabilities. The participants were instructed to attend to the story and press a button as soon as possible when the target stimuli were presented. Event-related potentials (ERPs) were recorded throughout the experiment using 128-channel EEG equipment. vMMN was obtained by subtracting standard from deviant stimuli responses, and P3 was evoked from the target stimulus. Mean reaction times for target stimuli in the BD group were significantly higher than those in the control group. Additionally, mean vMMN-amplitudes and peak P3-amplitudes were significantly lower in the BD group than in controls. Abnormal vMMN and P3 in patients indicate a deficit of visual information processing in BD, which is consistent with their increased reaction time to visual target stimuli. Both bottom-up and top-down visual information processing are likely altered in BD.
Rhodes, Mark A.
2008-10-21
A bipolar pulse forming transmission line module for linear induction accelerators having first, second, third, fourth, and fifth planar conductors which form an interleaved stack with dielectric layers between the conductors. Each conductor has a first end, and a second end adjacent an acceleration axis. The first and second planar conductors are connected to each other at the second ends, the fourth and fifth planar conductors are connected to each other at the second ends, and the first and fifth planar conductors are connected to each other at the first ends via a shorting plate adjacent the first ends. The third planar conductor is electrically connectable to a high voltage source, and an internal switch functions to short a high voltage from the first end of the third planar conductor to the first end of the fourth planar conductor to produce a bipolar pulse at the acceleration axis with a zero net time integral. Improved access to the switch is enabled by an aperture through the shorting plate and the proximity of the aperture to the switch.
Rhodes, Mark A [Pleasanton, CA
2008-10-21
A bipolar pulse forming transmission line module for linear induction accelerators having first, second, third, fourth, and fifth planar conductors which form an interleaved stack with dielectric layers between the conductors. Each conductor has a first end, and a second end adjacent an acceleration axis. The first and second planar conductors are connected to each other at the second ends, the fourth and fifth planar conductors are connected to each other at the second ends, and the first and fifth planar conductors are connected to each other at the first ends via a shorting plate adjacent the first ends. The third planar conductor is electrically connectable to a high voltage source, and an internal switch functions to short a high voltage from the first end of the third planar conductor to the first end of the fourth planar conductor to produce a bipolar pulse at the acceleration axis with a zero net time integral. Improved access to the switch is enabled by an aperture through the shorting plate and the proximity of the aperture to the switch.
Versatile Low Level RF System For Linear Accelerators
Potter, James M.
2011-06-01
The Low Level RF (LLRF) system is the source of all of the rf signals required for an rf linear accelerator. These signals are amplified to drive accelerator and buncher cavities. It can even provide the synchronizing signal for the rf power for a synchrotron. The use of Direct Digital Synthesis (DDS) techniques results in a versatile system that can provide multiple coherent signals at the same or different frequencies with adjustable amplitudes and phase relations. Pulsing the DDS allows rf switching with an essentially infinite on/off ratio. The LLRF system includes a versatile phase detector that allows phase-locking the rf frequency to a cavity at any phase angle over the full 360 deg. range. With the use of stepper motor driven slug tuners multiple cavity resonant frequencies can be phase locked to the rf source frequency. No external phase shifters are required and there is no feedback loop phase setup required. All that is needed is to turn the frequency feedback on. The use of Digital Signal Processing (DSP) allows amplitude and phase control over the entire rf pulse. This paper describes the basic principles of a LLRF system that has been used for both proton accelerators and electron accelerators, including multiple tank accelerators, sub-harmonic and fundamental bunchers, and synchrotrons.
Computational Aspects of Realization & Design Algorithms in Linear Systems Theory.
NASA Astrophysics Data System (ADS)
Tsui, Chia-Chi
Realization and design problems are two major problems in linear time-invariant systems control theory and have been solved theoretically. However, little is understood about their numerical properties. Due to the large scale of the problem and the finite precision of computer computation, it is very important and is the purpose of this study to investigate the computational reliability and efficiency of the algorithms for these two problems. In this dissertation, a reliable algorithm to achieve canonical form realization via Hankel matrix is developed. A comparative study of three general realization algorithms, for both numerical reliability and efficiency, shows that the proposed algorithm (via Hankel matrix) is the most preferable one among the three. The design problems, such as the state feedback design for pole placement, the state observer design, and the low order single and multi-functional observer design, have been solved by using canonical form systems matrices. In this dissertation, a set of algorithms for solving these three design problems is developed and analysed. These algorithms are based on Hessenberg form systems matrices which are numerically more reliable to compute than the canonical form systems matrices.
Linear System Models for Ultrasonic Imaging: Application to Signal Statistics
Zemp, Roger J.; Abbey, Craig K.; Insana, Michael F.
2009-01-01
Linear equations for modeling echo signals from shift-variant systems forming ultrasonic B-mode, Doppler, and strain images are analyzed and extended. The approach is based on a solution to the homogeneous wave equation for random inhomogeneous media. When the system is shift-variant, the spatial sensitivity function—defined as a spatial weighting function that determines the scattering volume for a fixed point of time—has advantages over the point-spread function traditionally used to analyze ultrasound systems. Spatial sensitivity functions are necessary for determining statistical moments in the context of rigorous image quality assessment, and they are time-reversed copies of point-spread functions for shift variant systems. A criterion is proposed to assess the validity of a local shift-invariance assumption. The analysis reveals realistic situations in which in-phase signals are correlated to the corresponding quadrature signals, which has strong implications for assessing lesion detectability. Also revealed is an opportunity to enhance near- and far-field spatial resolution by matched filtering unfocused beams. The analysis connects several well-known approaches to modeling ultrasonic echo signals. PMID:12839176
Integrability of Quadratic Non-autonomous Quantum Linear Systems
NASA Astrophysics Data System (ADS)
Lopez, Raquel
The Quantum Harmonic Oscillator is one of the most important models in Quantum Mechanics. Analogous to the classical mass vibrating back and forth on a spring, the quantum oscillator system has attracted substantial attention over the years because of its importance in many advanced and difficult quantum problems. This dissertation deals with solving generalized models of the time-dependent Schrodinger equation which are called generalized quantum harmonic oscillators, and these are characterized by an arbitrary quadratic Hamiltonian of linear momentum and position operators. The primary challenge in this work is that most quantum models with timedependence are not solvable explicitly, yet this challenge became the driving motivation for this work. In this dissertation, the methods used to solve the time-dependent Schrodinger equation are the fundamental singularity (or Green's function) and the Fourier (eigenfunction expansion) methods. Certain Riccati- and Ermakov-type systems arise, and these systems are highlighted and investigated. The overall aims of this dissertation are to show that quadratic Hamiltonian systems are completely integrable systems, and to provide explicit approaches to solving the time-dependent Schr¨odinger equation governed by an arbitrary quadratic Hamiltonian operator. The methods and results established in the dissertation are not yet well recognized in the literature, yet hold for high promise for further future research. Finally, the most recent results in the dissertation correspond to the harmonic oscillator group and its symmetries. A simple derivation of the maximum kinematical invariance groups of the free particle and quantum harmonic oscillator is constructed from the view point of the Riccati- and Ermakov-type systems, which shows an alternative to the traditional Lie Algebra approach. To conclude, a missing class of solutions of the time-dependent Schrodinger equation for the simple harmonic oscillator in one dimension is
Linear Temporal Logic (LTL) Based Monitoring of Smart Manufacturing Systems.
Heddy, Gerald; Huzaifa, Umer; Beling, Peter; Haimes, Yacov; Marvel, Jeremy; Weiss, Brian; LaViers, Amy
2015-01-01
The vision of Smart Manufacturing Systems (SMS) includes collaborative robots that can adapt to a range of scenarios. This vision requires a classification of multiple system behaviors, or sequences of movement, that can achieve the same high-level tasks. Likewise, this vision presents unique challenges regarding the management of environmental variables in concert with discrete, logic-based programming. Overcoming these challenges requires targeted performance and health monitoring of both the logical controller and the physical components of the robotic system. Prognostics and health management (PHM) defines a field of techniques and methods that enable condition-monitoring, diagnostics, and prognostics of physical elements, functional processes, overall systems, etc. PHM is warranted in this effort given that the controller is vulnerable to program changes, which propagate in unexpected ways, logical runtime exceptions, sensor failure, and even bit rot. The physical component's health is affected by the wear and tear experienced by machines constantly in motion. The controller's source of faults is inherently discrete, while the latter occurs in a manner that builds up continuously over time. Such a disconnect poses unique challenges for PHM. This paper presents a robotic monitoring system that captures and resolves this disconnect. This effort leverages supervisory robotic control and model checking with linear temporal logic (LTL), presenting them as a novel monitoring system for PHM. This methodology has been demonstrated in a MATLAB-based simulator for an industry inspired use-case in the context of PHM. Future work will use the methodology to develop adaptive, intelligent control strategies to evenly distribute wear on the joints of the robotic arms, maximizing the life of the system.
Linear Temporal Logic (LTL) Based Monitoring of Smart Manufacturing Systems
Heddy, Gerald; Huzaifa, Umer; Beling, Peter; Haimes, Yacov; Marvel, Jeremy; Weiss, Brian; LaViers, Amy
2017-01-01
The vision of Smart Manufacturing Systems (SMS) includes collaborative robots that can adapt to a range of scenarios. This vision requires a classification of multiple system behaviors, or sequences of movement, that can achieve the same high-level tasks. Likewise, this vision presents unique challenges regarding the management of environmental variables in concert with discrete, logic-based programming. Overcoming these challenges requires targeted performance and health monitoring of both the logical controller and the physical components of the robotic system. Prognostics and health management (PHM) defines a field of techniques and methods that enable condition-monitoring, diagnostics, and prognostics of physical elements, functional processes, overall systems, etc. PHM is warranted in this effort given that the controller is vulnerable to program changes, which propagate in unexpected ways, logical runtime exceptions, sensor failure, and even bit rot. The physical component’s health is affected by the wear and tear experienced by machines constantly in motion. The controller’s source of faults is inherently discrete, while the latter occurs in a manner that builds up continuously over time. Such a disconnect poses unique challenges for PHM. This paper presents a robotic monitoring system that captures and resolves this disconnect. This effort leverages supervisory robotic control and model checking with linear temporal logic (LTL), presenting them as a novel monitoring system for PHM. This methodology has been demonstrated in a MATLAB-based simulator for an industry inspired use-case in the context of PHM. Future work will use the methodology to develop adaptive, intelligent control strategies to evenly distribute wear on the joints of the robotic arms, maximizing the life of the system. PMID:28730154
NASA Technical Reports Server (NTRS)
Gunderson, R. W.; George, J. H.
1974-01-01
Two approaches are investigated for obtaining estimates on the error between approximate and exact solutions of dynamic systems. The first method is primarily useful if the system is nonlinear and of low dimension. The second requires construction of a system of v-functions but is useful for higher dimensional systems, either linear or nonlinear.
NASA Technical Reports Server (NTRS)
Gunderson, R. W.; George, J. H.
1974-01-01
Two approaches are investigated for obtaining estimates on the error between approximate and exact solutions of dynamic systems. The first method is primarily useful if the system is nonlinear and of low dimension. The second requires construction of a system of v-functions but is useful for higher dimensional systems, either linear or nonlinear.
Aerodynamic preliminary analysis system. Part 1: Theory. [linearized potential theory
NASA Technical Reports Server (NTRS)
Bonner, E.; Clever, W.; Dunn, K.
1978-01-01
A comprehensive aerodynamic analysis program based on linearized potential theory is described. The solution treats thickness and attitude problems at subsonic and supersonic speeds. Three dimensional configurations with or without jet flaps having multiple non-planar surfaces of arbitrary planform and open or closed slender bodies of non-circular contour may be analyzed. Longitudinal and lateral-directional static and rotary derivative solutions may be generated. The analysis was implemented on a time sharing system in conjunction with an input tablet digitizer and an interactive graphics input/output display and editing terminal to maximize its responsiveness to the preliminary analysis problem. Nominal case computation time of 45 CPU seconds on the CDC 175 for a 200 panel simulation indicates the program provides an efficient analysis for systematically performing various aerodynamic configuration tradeoff and evaluation studies.
Stability and complexity of small random linear systems
NASA Astrophysics Data System (ADS)
Hastings, Harold
2010-03-01
We explore the stability of the small random linear systems, typically involving 10-20 variables, motivated by dynamics of the world trade network and the US and Canadian power grid. This report was prepared as an account of work sponsored by an agency of the US Government. Neither the US Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the US Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the US Government or any agency thereof.
Convergence Results on Iteration Algorithms to Linear Systems
Wang, Zhuande; Yang, Chuansheng; Yuan, Yubo
2014-01-01
In order to solve the large scale linear systems, backward and Jacobi iteration algorithms are employed. The convergence is the most important issue. In this paper, a unified backward iterative matrix is proposed. It shows that some well-known iterative algorithms can be deduced with it. The most important result is that the convergence results have been proved. Firstly, the spectral radius of the Jacobi iterative matrix is positive and the one of backward iterative matrix is strongly positive (lager than a positive constant). Secondly, the mentioned two iterations have the same convergence results (convergence or divergence simultaneously). Finally, some numerical experiments show that the proposed algorithms are correct and have the merit of backward methods. PMID:24991640
Method and system for non-linear motion estimation
NASA Technical Reports Server (NTRS)
Lu, Ligang (Inventor)
2011-01-01
A method and system for extrapolating and interpolating a visual signal including determining a first motion vector between a first pixel position in a first image to a second pixel position in a second image, determining a second motion vector between the second pixel position in the second image and a third pixel position in a third image, determining a third motion vector between one of the first pixel position in the first image and the second pixel position in the second image, and the second pixel position in the second image and the third pixel position in the third image using a non-linear model, determining a position of the fourth pixel in a fourth image based upon the third motion vector.
Using parallel banded linear system solvers in generalized eigenvalue problems
NASA Technical Reports Server (NTRS)
Zhang, Hong; Moss, William F.
1993-01-01
Subspace iteration is a reliable and cost effective method for solving positive definite banded symmetric generalized eigenproblems, especially in the case of large scale problems. This paper discusses an algorithm that makes use of two parallel banded solvers in subspace iteration. A shift is introduced to decompose the banded linear systems into relatively independent subsystems and to accelerate the iterations. With this shift, an eigenproblem is mapped efficiently into the memories of a multiprocessor and a high speed-up is obtained for parallel implementations. An optimal shift is a shift that balances total computation and communication costs. Under certain conditions, we show how to estimate an optimal shift analytically using the decay rate for the inverse of a banded matrix, and how to improve this estimate. Computational results on iPSC/2 and iPSC/860 multiprocessors are presented.
Model of intermodulation distortion in non-linear multicarrier systems
NASA Astrophysics Data System (ADS)
Frigo, Nicholas J.
1994-02-01
A heuristic model is proposed which allows calculation of the individual spectral components of the intermodulation distortion present in a non-linear system with a multicarrier input. Noting that any given intermodulation product (IMP) can only be created by a subset of the input carriers, we partition them into 'signal' carriers (which create the IMP) and 'noise' carriers, modeled as a Gaussian process. The relationship between an input signal and the statistical average of its output (averaged over the Gaussian noise) is considered to be an effective transfer function. By summing all possible combinations of signal carriers which create power at the IMP frequencies, the distortion power can be calculated exactly as a function of frequency. An analysis of clipping in lightwave CATV links for AM-VSB signals is used to introduce the model, and is compared to a series of experiments.
Robust mean field games for coupled Markov jump linear systems
NASA Astrophysics Data System (ADS)
Moon, Jun; Başar, Tamer
2016-07-01
We consider robust stochastic large population games for coupled Markov jump linear systems (MJLSs). The N agents' individual MJLSs are governed by different infinitesimal generators, and are affected not only by the control input but also by an individual disturbance (or adversarial) input. The mean field term, representing the average behaviour of N agents, is included in the individual worst-case cost function to capture coupling effects among agents. To circumvent the computational complexity and analyse the worst-case effect of the disturbance, we use robust mean field game theory to design low-complexity robust decentralised controllers and to characterise the associated worst-case disturbance. We show that with the individual robust decentralised controller and the corresponding worst-case disturbance, which constitute a saddle-point solution to a generic stochastic differential game for MJLSs, the actual mean field behaviour can be approximated by a deterministic function which is a fixed-point solution to the constructed mean field system. We further show that the closed-loop system is uniformly stable independent of N, and an approximate optimality can be obtained in the sense of ε-Nash equilibrium, where ε can be taken to be arbitrarily close to zero as N becomes sufficiently large. A numerical example is included to illustrate the results.
A Structured Model Reduction Method for Linear Interconnected Systems
NASA Astrophysics Data System (ADS)
Sato, Ryo; Inoue, Masaki; Adachi, Shuichi
2016-09-01
This paper develops a model reduction method for a large-scale interconnected system that consists oflinear dynamic components. In the model reduction, we aim to preserve physical characteristics of each component. To this end, we formulate a structured model reduction problem that reduces the model order of components while preserving the feedback structure. Although there are a few conventional methods for such structured model reduction to preserve stability, they do not explicitly consider performance of the reduced-order feedback system. One of the difficulties in the problem with performance guarantee comes from nonlinearity of a feedback system to each component. The problem is essentially in a class of nonlinear optimization problems, and therefore it cannot be efficiently solved even in numerical computation. In this paper, application of an equivalent transformation and a proper approximation reduces this nonlinear problem to a problem of the weighted linear model reduction. Then, by using the weighted balanced truncation technique, we construct a reduced-order model with preserving the feedback structure to ensure small modeling error. Finally, we verify the effectiveness of the proposed method through numerical experiments.
A linear geospatial streamflow modeling system for data sparse environments
Asante, Kwabena O.; Arlan, Guleid A.; Pervez, Md Shahriar; Rowland, James
2008-01-01
In many river basins around the world, inaccessibility of flow data is a major obstacle to water resource studies and operational monitoring. This paper describes a geospatial streamflow modeling system which is parameterized with global terrain, soils and land cover data and run operationally with satellite‐derived precipitation and evapotranspiration datasets. Simple linear methods transfer water through the subsurface, overland and river flow phases, and the resulting flows are expressed in terms of standard deviations from mean annual flow. In sample applications, the modeling system was used to simulate flow variations in the Congo, Niger, Nile, Zambezi, Orange and Lake Chad basins between 1998 and 2005, and the resulting flows were compared with mean monthly values from the open‐access Global River Discharge Database. While the uncalibrated model cannot predict the absolute magnitude of flow, it can quantify flow anomalies in terms of relative departures from mean flow. Most of the severe flood events identified in the flow anomalies were independently verified by the Dartmouth Flood Observatory (DFO) and the Emergency Disaster Database (EM‐DAT). Despite its limitations, the modeling system is valuable for rapid characterization of the relative magnitude of flood hazards and seasonal flow changes in data sparse settings.
A method to stabilize linear systems using eigenvalue gradient information
NASA Technical Reports Server (NTRS)
Wieseman, C. D.
1985-01-01
Formal optimization methods and eigenvalue gradient information are used to develop a stabilizing control law for a closed loop linear system that is initially unstable. The method was originally formulated by using direct, constrained optimization methods with the constraints being the real parts of the eigenvalues. However, because of problems in trying to achieve stabilizing control laws, the problem was reformulated to be solved differently. The method described uses the Davidon-Fletcher-Powell minimization technique to solve an indirect, constrained minimization problem in which the performance index is the Kreisselmeier-Steinhauser function of the real parts of all the eigenvalues. The method is applied successfully to solve two different problems: the determination of a fourth-order control law stabilizes a single-input single-output active flutter suppression system and the determination of a second-order control law for a multi-input multi-output lateral-directional flight control system. Various sets of design variables and initial starting points were chosen to show the robustness of the method.
Laursen, Thomas Munk; Wahlbeck, Kristian; Hällgren, Jonas; Westman, Jeanette; Ösby, Urban; Alinaghizadeh, Hassan; Gissler, Mika; Nordentoft, Merete
2013-01-01
Excess mortality from diseases and medical conditions (natural death) in persons with psychiatric disorders has been extensively reported. Even in the Nordic countries with well-developed welfare systems, register based studies find evidence of an excess mortality. In recent years, cardiac mortality and death by diseases of the circulatory system has seen a decline in all the Nordic countries, but a recent paper indicates that women and men in Denmark, Finland, and Sweden, who had been hospitalised for a psychotic disorder, had a two to three-fold increased risk of dying from a cardiovascular disease. The aim of this study was to compare the mortality by diseases of the circulatory system among patients with bipolar disorder or schizophrenia in the three Nordic countries Denmark, Sweden, and Finland. Furthermore, the aim was to examine and compare life expectancy among these patients. Cause specific Standardized Mortality Rates (SMRs) were calculated for each specific subgroup of mortality. Life expectancy was calculated using Wiesler's method. The SMR for bipolar disorder for diseases of the circulatory system was approximately 2 in all countries and both sexes. SMR was slightly higher for people with schizophrenia for both genders and in all countries, except for men in Denmark. Overall life expectancy was much lower among persons with bipolar disorder or schizophrenia, with life expectancy being from 11 to 20 years shorter. Our data show that persons in the Nordic countries with schizophrenia or bipolar disorder have a substantially reduced life expectancy. An evaluation of the reasons for these increased mortality rates should be prioritized when planning healthcare in the coming years.
Crawshaw, Benjamin P; Russ, Andrew J; Ermlich, Bridget O; Delaney, Conor P; Champagne, Bradley J
2016-12-01
Background Existing nonsurgical procedures for the treatment of grade I and II internal hemorrhoids are often painful, technically demanding, and often necessitate multiple applications. This study prospectively assessed the safety and efficacy of the HET Bipolar System, a novel minimally invasive device, in the treatment of symptomatic grade I and II internal hemorrhoids. Methods Patients with symptomatic grade I or II internal hemorrhoids despite medical management underwent hemorrhoidal ligation with the HET Bipolar System. Endpoints included resolution or improvement of hemorrhoidal bleeding and/or prolapse from baseline, recurrent or refractory symptoms, and pain. Results Twenty patients were treated with the HET Bipolar System. Two were lost to follow-up. Refractory or recurrent bleeding was present in 8 of 18 (44.4%), 4 of 11 (36.4%), and 4 of 8 (50.0%) patients, and prolapse was reported by 1 of 18 (5.6%), 4 of 11 (36.4%), and 1/7 (14.3%) of patients at 1, 3, and 6 months, respectively. Bleeding improved from baseline in 88.2%, 81.8%, and 87.5% of patients, and resolution of baseline prolapse was seen in 11 of 11 (100%), 4 of 7 (57.1%), and 5 of 5 (100%) patients at the same intervals. Thirteen of 18 (72.2%) patients did not require additional treatment for their symptoms. Conclusions The HET Bipolar System is safe and easy to use with short-term effectiveness comparable to that of currently used techniques for the treatment of symptomatic grade I and II internal hemorrhoids. It may be an effective alternative to rubber band ligation in patients with larger internal hemorrhoids and those with hemorrhoids close to the dentate line in which banding may produce debilitating pain. © The Author(s) 2016.
Laursen, Thomas Munk; Wahlbeck, Kristian; Hällgren, Jonas; Westman, Jeanette; Ösby, Urban; Alinaghizadeh, Hassan; Gissler, Mika; Nordentoft, Merete
2013-01-01
Objective Excess mortality from diseases and medical conditions (natural death) in persons with psychiatric disorders has been extensively reported. Even in the Nordic countries with well-developed welfare systems, register based studies find evidence of an excess mortality. In recent years, cardiac mortality and death by diseases of the circulatory system has seen a decline in all the Nordic countries, but a recent paper indicates that women and men in Denmark, Finland, and Sweden, who had been hospitalised for a psychotic disorder, had a two to three-fold increased risk of dying from a cardiovascular disease. The aim of this study was to compare the mortality by diseases of the circulatory system among patients with bipolar disorder or schizophrenia in the three Nordic countries Denmark, Sweden, and Finland. Furthermore, the aim was to examine and compare life expectancy among these patients. Cause specific Standardized Mortality Rates (SMRs) were calculated for each specific subgroup of mortality. Life expectancy was calculated using Wiesler’s method. Results The SMR for bipolar disorder for diseases of the circulatory system was approximately 2 in all countries and both sexes. SMR was slightly higher for people with schizophrenia for both genders and in all countries, except for men in Denmark. Overall life expectancy was much lower among persons with bipolar disorder or schizophrenia, with life expectancy being from 11 to 20 years shorter. Conclusion Our data show that persons in the Nordic countries with schizophrenia or bipolar disorder have a substantially reduced life expectancy. An evaluation of the reasons for these increased mortality rates should be prioritized when planning healthcare in the coming years. PMID:23826212
Targeting astrocytes in bipolar disorder.
Peng, Liang; Li, Baoman; Verkhratsky, Alexei
2016-06-01
Astrocytes are homeostatic cells of the central nervous system, which are critical for development and maintenance of synaptic transmission and hence of synaptically connected neuronal ensembles. Astrocytic densities are reduced in bipolar disorder, and therefore deficient astroglial function may contribute to overall disbalance in neurotransmission and to pathological evolution. Classical anti-bipolar drugs (lithium salts, valproic acid and carbamazepine) affect expression of astroglial genes and modify astroglial signalling and homeostatic cascades. Many effects of both antidepressant and anti-bipolar drugs are exerted through regulation of glutamate homeostasis and glutamatergic transmission, through K(+) buffering, through regulation of calcium-dependent phospholipase A2 (that controls metabolism of arachidonic acid) or through Ca(2+) homeostatic and signalling pathways. Sometimes anti-depressant and anti-bipolar drugs exert opposite effects, and some effects on gene expression in drug treated animals are opposite in neurones vs. astrocytes. Changes in the intracellular pH induced by anti-bipolar drugs affect uptake of myo-inositol and thereby signalling via inositoltrisphosphate (InsP3), this being in accord with one of the main theories of mechanism of action for these drugs.
NASA Astrophysics Data System (ADS)
Zehe, Erwin; Loritz, Ralf; Ehret, Uwe; Westhoff, Martijn; Kleidon, Axel; Savenije, Hubert
2017-04-01
It is flabbergasting to note that catchment systems often behave almost linearly, despite of the strong non-linearity of point scale soil water characteristics. In the present study we provide evidence that a thermodynamic treatment of environmental system dynamics is the key to understand how particularly a stronger spatial organization of catchments leads to a more linear rainfall runoff behavior. Our starting point is that water fluxes in a catchment are associated with fluxes of kinetic and potential energy while changes in subsurface water stocks go along with changes in potential energy and chemical energy of subsurface water. Steady state/local equilibrium of the entire system can be defined as a state of minimum free energy, reflecting an equilibrium subsurface water storage, which is determined catchment topography, soil water characteristics and water levels in the stream. Dynamics of the entire system, i.e. deviations from equilibrium storage, are 'pseudo' oscillations in a thermodynamic state space. Either to an excess potential energy in case of wetting while subsequent relaxation back to equilibrium requires drainage/water export. Or to an excess in capillary binding energy in case of driving, while relaxation back to equilibrium requires recharge of the subsurface water stock. While system dynamics is highly non-linear on the 'too dry branch' it is essentially linear on the 'too wet branch' in case of potential energy excess. A steepened topography, which reflects a stronger spatial organization, reduces the equilibrium storage of the catchment system to smaller values, thereby it increases the range of states where the systems behaves linearly due to an excess in potential energy. Contrarily to this a shift to finer textured soils increases the equilibrium storage, which implies that the range of states where the systems behaves linearly is reduced. In this context it is important to note that an increased internal organization of the system due to
Identify bipolar spectrum disorders.
Mynatt, Sarah; Cunningham, Patricia; Manning, J Sloan
2002-06-01
Patients with bipolar spectrum disorders commonly present with depressive symptoms to primary care clinicians. This article details bipolar spectrum disorder assessment, treatment, and treatment response. By intervening early in the course of depressive and hypomanic episodes, you can help decrease the morbidity and suffering associated with bipolar spectrum disorders.
2-D linear motion system. Innovative technology summary report
1998-11-01
The US Department of Energy's (DOE's) nuclear facility decontamination and decommissioning (D and D) program requires buildings to be decontaminated, decommissioned, and surveyed for radiological contamination in an expeditious and cost-effective manner. Simultaneously, the health and safety of personnel involved in the D and D activities is of primary concern. D and D workers must perform duties high off the ground, requiring the use of manlifts or scaffolding, often, in radiologically or chemically contaminated areas or in areas with limited access. Survey and decontamination instruments that are used are sometimes heavy or awkward to use, particularly when the worker is operating from a manlift or scaffolding. Finding alternative methods of performing such work on manlifts or scaffolding is important. The 2-D Linear Motion System (2-D LMS), also known as the Wall Walker{trademark}, is designed to remotely position tools and instruments on walls for use in such activities as radiation surveys, decontamination, and painting. Traditional (baseline) methods for operating equipment for these tasks require workers to perform duties on elevated platforms, sometimes several meters above the ground surface and near potential sources of contamination. The Wall Walker 2-D LMS significantly improves health and safety conditions by facilitating remote operation of equipment. The Wall Walker 2-D LMS performed well in a demonstration of its precision, accuracy, maneuverability, payload capacity, and ease of use. Thus, this innovative technology is demonstrated to be a viable alternative to standard methods of performing work on large, high walls, especially those that have potential contamination concerns. The Wall Walker was used to perform a final release radiological survey on over 167 m{sup 2} of walls. In this application, surveying using a traditional (baseline) method that employs an aerial lift for manual access was 64% of the total cost of the improved technology
Psychotic and Bipolar Disorders: Bipolar Disorder.
Holder, Sarah D
2017-04-01
Bipolar disorder is a severe chronic mental illness that affects a large number of individuals. This disorder is separated into two major types, bipolar I disorder, with mania and typically recurrent depression, and bipolar II disorder, with recurrent major depression and hypomania. Patients with bipolar disorder spend the majority of time experiencing depression, and this typically is the presenting symptom. Because outcomes are improved with earlier diagnosis and treatment, physicians should maintain a high index of suspicion for bipolar disorder. The most effective long-term treatments are lithium and valproic acid, although other drugs also are used. In addition to referral to a mental health subspecialist for initiation and management of drug treatment, patients with bipolar disorder should be provided with resources for psychotherapy. Several comorbidities commonly associated with bipolar disorder include other mental disorders, substance use disorders, migraine headaches, chronic pain, stroke, metabolic syndrome, and cardiovascular disease. Family physicians who care for patients with bipolar disorder should focus their efforts on prevention and management of comorbidities. These patients should be assessed continually for risk of suicide because they are at high risk and their suicide attempts tend to be successful. Written permission from the American Academy of Family Physicians is required for reproduction of this material in whole or in part in any form or medium.
Factorial switching linear dynamical systems applied to physiological condition monitoring.
Quinn, John A; Williams, Christopher K I; McIntosh, Neil
2009-09-01
Condition monitoring often involves the analysis of systems with hidden factors that switch between different modes of operation in some way. Given a sequence of observations, the task is to infer the filtering distribution of the switch setting at each time step. In this paper, we present factorial switching linear dynamical systems as a general framework for handling such problems. We show how domain knowledge and learning can be successfully combined in this framework, and introduce a new factor (the "X-factor") for dealing with unmodeled variation. We demonstrate the flexibility of this type of model by applying it to the problem of monitoring the condition of a premature baby receiving intensive care. The state of health of a baby cannot be observed directly, but different underlying factors are associated with particular patterns of physiological measurements and artifacts. We have explicit knowledge of common factors and use the X-factor to model novel patterns which are clinically significant but have unknown cause. Experimental results are given which show the developed methods to be effective on typical intensive care unit monitoring data.
Linear dynamic system approach to groundwater solute transport equation
Cho, W.C.
1984-01-01
Groundwater pollution in the United States has been recognized in the 1980's to be extensive both in degree and geographic distribution. It has been recognized that in many cases groundwater pollution is essentially irreversible from the engineering or economic viewpoint. Under the best circumstance the problem is complicated by insufficient amounts of field data which is costly to obtain. In general, the governing partial differential equation of solute transport is spatially discretized either using finite difference or finite element scheme. The time derivative is also approximated by finite difference. In this study, only the spatial discretization is performed using finite element method and the time derivative is retained in continuous form. The advantage is that special features of finite element are maintained but most important of all is that the equation can be rearranged to be in a standard form of linear dynamic system. Two problems were studied in detail: one is the determination of the locatio of groundwater pollution source(s). The problem is equivalent to identifying an input to the dynamic system and is solved by using the sensitivity theorem. The other one is the prediction of pollutant concentration at a given time at a given location. The eigenvalue technique was employed to solve this problem and the detailed procedures of the computation were delineated.
Low-Rank Linear Dynamical Systems for Motor Imagery EEG
Tan, Chuanqi; Liu, Shaobo
2016-01-01
The common spatial pattern (CSP) and other spatiospectral feature extraction methods have become the most effective and successful approaches to solve the problem of motor imagery electroencephalography (MI-EEG) pattern recognition from multichannel neural activity in recent years. However, these methods need a lot of preprocessing and postprocessing such as filtering, demean, and spatiospectral feature fusion, which influence the classification accuracy easily. In this paper, we utilize linear dynamical systems (LDSs) for EEG signals feature extraction and classification. LDSs model has lots of advantages such as simultaneous spatial and temporal feature matrix generation, free of preprocessing or postprocessing, and low cost. Furthermore, a low-rank matrix decomposition approach is introduced to get rid of noise and resting state component in order to improve the robustness of the system. Then, we propose a low-rank LDSs algorithm to decompose feature subspace of LDSs on finite Grassmannian and obtain a better performance. Extensive experiments are carried out on public dataset from “BCI Competition III Dataset IVa” and “BCI Competition IV Database 2a.” The results show that our proposed three methods yield higher accuracies compared with prevailing approaches such as CSP and CSSP. PMID:28096809
Low-Rank Linear Dynamical Systems for Motor Imagery EEG.
Zhang, Wenchang; Sun, Fuchun; Tan, Chuanqi; Liu, Shaobo
2016-01-01
The common spatial pattern (CSP) and other spatiospectral feature extraction methods have become the most effective and successful approaches to solve the problem of motor imagery electroencephalography (MI-EEG) pattern recognition from multichannel neural activity in recent years. However, these methods need a lot of preprocessing and postprocessing such as filtering, demean, and spatiospectral feature fusion, which influence the classification accuracy easily. In this paper, we utilize linear dynamical systems (LDSs) for EEG signals feature extraction and classification. LDSs model has lots of advantages such as simultaneous spatial and temporal feature matrix generation, free of preprocessing or postprocessing, and low cost. Furthermore, a low-rank matrix decomposition approach is introduced to get rid of noise and resting state component in order to improve the robustness of the system. Then, we propose a low-rank LDSs algorithm to decompose feature subspace of LDSs on finite Grassmannian and obtain a better performance. Extensive experiments are carried out on public dataset from "BCI Competition III Dataset IVa" and "BCI Competition IV Database 2a." The results show that our proposed three methods yield higher accuracies compared with prevailing approaches such as CSP and CSSP.
NASA Astrophysics Data System (ADS)
Zawadzki, Andrzej; Różowicz, Sebastian
2016-05-01
The paper presents a transformation of nonlinear electric circuit into linear one through changing coordinates (local diffeomorphism) with the use of closed feedback loop. The necessary conditions that must be fulfilled by nonlinear system to enable carrying out linearizing procedures are presented. Numerical solutions of state equations for the nonlinear system and equivalent linearized system are included.
Xiang, Yinbo; Liu, Guangli; Zhang, Renduo; Lu, Yaobin; Luo, Haiping
2017-06-01
The aim of this study was to develop an efficient bioanode microbial electrosynthesis system (MES) to convert carbon dioxide into acetate using bioenergy from the wastewater. The bioanode MESs were constructed using proton exchange membrane (PEM) and bipolar membrane (BPM) as separator, respectively, and operated under different voltages (i.e., 0.8, 1.0, 1.2, and 1.4V). Since BPM could dissociate H2O into H(+) and OH(-) in situ to buffer the pH change in the chambers, the BPM-MES achieved 238% improvement in cathodic acetate production rate, 45% increase in anodic substrate removal efficiency, and more than five times enhancement in current output, as compared to the PEM-MES. The biomass on the surface of anode and cathode, and the relative abundance of Acetobacterium in the cathode of BPM-MES was higher than that in PEM-MES. Bioanode MES with BPM should be a useful microbial electrosynthesis strategy for acetate production using bioenergy from wastewater treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.
Kim, Eosu; Jung, Young-Chul; Ku, Jeonghun; Kim, Jae-Jin; Lee, Hyeongrae; Kim, So Young; Kim, Sun I; Cho, Hyun-Sang
2009-11-13
Social cognition entails both cognitive and affective processing, and impairments in both have accounted for residual symptoms of bipolar disorder (BD). However, there has been a lack of studies identifying neural substrates responsible for social cognitive difficulties in BD patients. Fourteen euthymic BD patients and 14 healthy normal controls underwent functional MRI while performing a virtual reality social cognition task, which incorporated both cognitive and emotional dimensions, simulating real-world social situations. During the scanning, subjects tried to guess (attribute) possible reasons for expressed emotion of virtual humans (avatars) while viewing their facial expressions, just after observing their verbal and nonverbal (facial) expressions which were emotionally valenced (happy, angry and neutral). BD patients compared to normal controls showed delayed reaction times in emotional conditions, with comparable response accuracy. Healthy normal controls activated the right anterior cingulate cortex, inferior frontal, and insular cortex in emotional conditions contrasted with neutral control conditions, that is, the regions that have been related to empathic processes during viewing others' emotional expression. Relative to normal controls, BD patients showed reduced activations in the 'mirror neuron system', including the right inferior frontal cortex, premotor cortex, and insula, mainly in angry or happy condition. These results may suggest that, even during euthymic state, BD patients have difficulties in recruiting brain regions for the utilization of emotional cues as a means for understanding others. Clinical attention should be paid to emotion-related residual symptoms to help improve social outcomes in these patients.
Cohen-Mazor, Meital; Mathur, Prabodh; Stanley, James R.L.; Mendelsohn, Farrell O.; Lee, Henry; Baird, Rose; Zani, Brett G.; Markham, Peter M.; Rocha-Singh, Krishna
2014-01-01
Objective: To evaluate the safety and effectiveness of different bipolar radiofrequency system algorithms in interrupting the renal sympathetic nerves and reducing renal norepinephrine in a healthy porcine model. Methods: A porcine model (N = 46) was used to investigate renal norepinephrine levels and changes to renal artery tissues and nerves following percutaneous renal denervation with radiofrequency bipolar electrodes mounted on a balloon catheter. Parameters of the radiofrequency system (i.e. electrode length and energy delivery algorithm), and the effects of single and longitudinal treatments along the artery were studied with a 7-day model in which swine received unilateral radiofrequency treatments. Additional sets of animals were used to examine norepinephrine and histological changes 28 days following bilateral percutaneous radiofrequency treatment or surgical denervation; untreated swine were used for comparison of renal norepinephrine levels. Results: Seven days postprocedure, norepinephrine concentrations decreased proportionally to electrode length, with 81, 60 and 38% reductions (vs. contralateral control) using 16, 4 and 2-mm electrodes, respectively. Applying a temperature-control algorithm with the 4-mm electrodes increased efficacy, with a mean 89.5% norepinephrine reduction following a 30-s treatment at 68°C. Applying this treatment along the entire artery length affected more nerves vs. a single treatment, resulting in superior norepinephrine reduction 28 days following bilateral treatment. Conclusion: Percutaneous renal artery application of bipolar radiofrequency energy demonstrated safety and resulted in a significant renal norepinephrine content reduction and renal nerve injury compared with untreated controls in porcine models. PMID:24875181
Nutrition and Bipolar Depression.
Beyer, John L; Payne, Martha E
2016-03-01
As with physical conditions, bipolar disorder is likely to be impacted by diet and nutrition. Patients with bipolar disorder have been noted to have relatively unhealthy diets, which may in part be the reason they also have an elevated risk of metabolic syndrome and obesity. An improvement in the quality of the diet should improve a bipolar patient's overall health risk profile, but it may also improve their psychiatric outcomes. New insights into biological dysfunctions that may be present in bipolar disorder have presented new theoretic frameworks for understanding the relationship between diet and bipolar disorder.
Dosimetric comparison of linear accelerator-based stereotactic radiosurgery systems
Sharma, S. D.; Kumar, Sudhir; Dagaonkar, S. S.; Bisht, Geetika; Dayanand, S.; Devi, Reena; Deshpande, S. S.; Chaudhary, S.; Bhatt, B. C.; Kannan, S.
2007-01-01
Stereotactic radiosurgery (SRS) is a special radiotherapy technique used to irradiate intracranial lesions by 3-D arrangements of narrow photon beams eliminating the needs of invasive surgery. Three different tertiary collimators, namely BrainLab and Radionics circular cones and BrainLab micro multileaf collimator (mMLC), are used for linear accelerator-based SRS systems (X-Knife). Output factor (St), tissue maximum ratio (TMR) and off axis ratio (OAR) of these three SRS systems were measured using CC01 (Scanditronix/ Welhofer) and Pinpoint (PTW) cylindrical and Markus plane parallel ionization chambers as well as TLD and radiochromic film. Measurement results of CC01 and Pinpoint chambers were very close to each other which indicate that further reduction in volume and physical dimensions of cylindrical ionization chamber is not necessary for SRS/SRT dosimetry. Output factors of BrainLab and Radionics SRS cones were very close to each other while output factors of equivalent diameter mMLC field were different from SRS circular cones. TMR of the three SRS systems compared were very close to one another. OAR of Radionics cone and BrainLab mMLC were very close to each other, within 2%. However, OARs of BrainLab cone were found comparable to OARs of Radionics cone and BrainLab mMLC within maximum variation of 4%. In addition, user-measured similar data of other three mMLC X-Knives were compared with the mMLC X-Knife data measured in this work and found comparable. The concept of switching over to mMLC-based SRS/SRT is thus validated from dosimetric characteristics as well. PMID:21217914
Dosimetric comparison of linear accelerator-based stereotactic radiosurgery systems.
Sharma, S D; Kumar, Sudhir; Dagaonkar, S S; Bisht, Geetika; Dayanand, S; Devi, Reena; Deshpande, S S; Chaudhary, S; Bhatt, B C; Kannan, S
2007-01-01
Stereotactic radiosurgery (SRS) is a special radiotherapy technique used to irradiate intracranial lesions by 3-D arrangements of narrow photon beams eliminating the needs of invasive surgery. Three different tertiary collimators, namely BrainLab and Radionics circular cones and BrainLab micro multileaf collimator (mMLC), are used for linear accelerator-based SRS systems (X-Knife). Output factor (S(t)), tissue maximum ratio (TMR) and off axis ratio (OAR) of these three SRS systems were measured using CC01 (Scanditronix/ Welhofer) and Pinpoint (PTW) cylindrical and Markus plane parallel ionization chambers as well as TLD and radiochromic film. Measurement results of CC01 and Pinpoint chambers were very close to each other which indicate that further reduction in volume and physical dimensions of cylindrical ionization chamber is not necessary for SRS/SRT dosimetry. Output factors of BrainLab and Radionics SRS cones were very close to each other while output factors of equivalent diameter mMLC field were different from SRS circular cones. TMR of the three SRS systems compared were very close to one another. OAR of Radionics cone and BrainLab mMLC were very close to each other, within 2%. However, OARs of BrainLab cone were found comparable to OARs of Radionics cone and BrainLab mMLC within maximum variation of 4%. In addition, user-measured similar data of other three mMLC X-Knives were compared with the mMLC X-Knife data measured in this work and found comparable. The concept of switching over to mMLC-based SRS/SRT is thus validated from dosimetric characteristics as well.
A Linear Systems Approach to Segmented Watershed Contaminant Transport
NASA Astrophysics Data System (ADS)
Carleton, J. N.
2013-12-01
The U.S. Environmental Protection Agency (USEPA) employs simulation models to estimate concentrations of pesticide residues in surface waters for risk assessment. These models have historically been used to simulate runoff loadings from homogeneous landscapes to isolated, well-mixed lentic systems that generically represent vulnerable waters. Recent efforts to refine this approach in terms of realism and geographic specificity have focused on enhancing the level of detail of the landscape representation, rather than that of receiving water hydrology. Linear systems theory and transfer function based approaches have been applied by various investigators to the representation of contaminant leaching through soils, and to surface water hydrology (e.g., unit hydrographs), but rarely to contaminant transport either within surface waters, or through multi-compartment systems such as stream networks. This poster describes a straightforward approach to simulating watersheds as segmented into collections of linked water bodies. The approach employs convolution integrals, impulse response functions, and the Discrete Fourier Transform to propagate concentration time series from upstream to downstream locations. Given knowledge only of estimated mean stream residence times, with appropriately-scaled segmentations of catchments, realistic representations of concentration dynamics are shown to be achievable. These representations are based upon high-frequency atrazine monitoring data sets collected over common time periods from upstream and downstream locations within the same small watersheds. Simulated concentrations are shown to match measured concentrations well in both the temporal and spectral domains without the need for calibration, and despite inherent simplifying assumptions such as steady flow. The approach may have utility for enhancing surface water hydrologic representation in contaminant modeling used for regulatory purposes.
On differential operators generating iterative systems of linear ODEs of maximal symmetry algebra
NASA Astrophysics Data System (ADS)
Ndogmo, J. C.
2017-06-01
Although every iterative scalar linear ordinary differential equation is of maximal symmetry algebra, the situation is different and far more complex for systems of linear ordinary differential equations, and an iterative system of linear equations need not be of maximal symmetry algebra. We illustrate these facts by examples and derive families of vector differential operators whose iterations are all linear systems of equations of maximal symmetry algebra. Some consequences of these results are also discussed.
Cognitive style in bipolar disorder sub-types.
Fletcher, Kathryn; Parker, Gordon; Manicavasagar, Vijaya
2013-04-30
Clearer understanding of psychological processes and mechanisms such as cognitive style inform more targeted psychological treatments for mood disorders. Studies to date have focused on bipolar I disorder or combined bipolar sub-types, precluding identification of any distinctive cognitive style profiles. We examined cognitive style separately in the bipolar sub-types, contrasted with unipolar and non-clinical controls. A total of 417 participants (94 bipolar I, 114 bipolar II, 109 unipolar, 100 healthy controls) completed cognitive style measures including the Rosenberg Self-Esteem Scale, Dysfunctional Attitudes Scale, Inferential Styles Questionnaire, Stress Appraisal Measure and the Behavioural Inhibition System/Behavioural Activation System Scale. Overall, cognitive styles were similar in unipolar and bipolar participants, but with styles relevant to the Behavioral Activation System differentiating bipolar I disorder in particular. State anxiety influenced negative inferential style in unipolar participants and appraisal of stress in bipolar II participants. Analyses restricted to bipolar I vs. II comparisons revealed subtle differences in terms of dispositional stress appraisal, with higher scores on two stress appraisal sub-scales in the bipolar I group. Further exploration of cognitive style in bipolar sub-types is indicated in order to determine whether there are specific psychological vulnerabilities that would benefit from more targeted psychological interventions. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.
Symmetry breaking in linearly coupled Korteweg-de Vries systems.
Espinosa-Cerón, A; Malomed, B A; Fujioka, J; Rodríguez, R F
2012-09-01
We consider solitons in a system of linearly coupled Korteweg-de Vries (KdV) equations, which model two-layer settings in various physical media. We demonstrate that traveling symmetric solitons with identical components are stable at velocities lower than a certain threshold value. Above the threshold, which is found exactly, the symmetric modes are unstable against spontaneous symmetry breaking, which gives rise to stable asymmetric solitons. The shape of the asymmetric solitons is found by means of a variational approximation and in the numerical form. Simulations of the evolution of an unstable symmetric soliton sometimes produce its breakup into two different asymmetric modes. Collisions between moving stable solitons, symmetric and asymmetric ones, are studied numerically, featuring noteworthy features. In particular, collisions between asymmetric solitons with identical polarities are always elastic, while in the case of opposite polarities the collision leads to a switch of the polarities of both solitons. Three-soliton collisions are studied too, featuring quite complex interaction scenarios.
Characterising the stabilisability for second-order linear switched systems
NASA Astrophysics Data System (ADS)
Cong, Shen
2013-03-01
The stabilisability of second-order linear switched systems is the topic focused on in a number of papers, however, some of its fundamental characteristics are still unrevealed. In this article, regarding a pair of subsystems, we are interested in characterising this problem from both the state-triggering and time-domain viewpoints and in revealing the inherent connection between them. To this end, we first use polar coordinates to represent the geometric property of switching and the dynamical behaviours caused by it, and then put the geometrised switching control into correspondence with the implicit stabilisation mechanism behind it. Doing this in a strong way relies on classifying switching control into two types intuitively, namely, chattering switching and spinning switching, and then clarifying their distinction and properties rigorously. Furthermore, the uniform convergence of the forced trajectory is shown by presenting estimation on its decay rate; and the limit cycles and sliding motions generated by switching are also accounted for. The results are illustrated by elaborate examples.
Melcher, Tobias; Wolter, Sarah; Falck, Stefanie; Wild, Eva; Wild, Florian; Gruber, Eva; Falkai, Peter; Gruber, Oliver
2014-09-01
Schizophrenia and bipolar disorder broadly overlap in multiple areas involving clinical phenomenology, genetics, and neurobiology. Still, the investigation into specific elementary (sub-)processes of executive functioning may help to define clear points of distinction between these categorical diagnoses to validate the nosological dichotomy and, indirectly, to further elucidate their pathophysiological underpinnings. In the present behavioral study, we sought to separate common from diagnosis-specific deficits in a series of specific elementary sub-functions of executive processing in patients with schizophrenia and bipolar disorder. For our purpose, we administered a modern and multi-purpose neuropsychological task paradigm to equal-sized and matched groups of schizophrenia patients, patients with bipolar disorder, and healthy control subjects. First, schizophrenia patients compared to the bipolar group exhibited a more pronounced deficit in general measures of task performance comprising both response speed and accuracy. Additionally, bipolar patients showed increased advance task preparation, i.e., were better able to compensate for response speed deficits when longer preparation intervals were provided. Set-shifting, on the other hand, was impaired to a similar degree in both patient groups. Finally, schizophrenia patients exhibited a specific deficit in conflict processing (inhibitory control) and the shielding of task-relevant processing from distraction (i.e., attentional maintenance). The present investigation suggests that specific neuropsychological measures of elementary executive functions may represent important points of dissociation between schizophrenia and bipolar disorder, which may help to differentiate the pathophysiological underpinnings of these major psychiatric disorders. In this context, the present findings highlight the measures of inhibitory control and attentional maintenance as promising candidates.
Electron linear accelerator system for natural rubber vulcanization
NASA Astrophysics Data System (ADS)
Rimjaem, S.; Kongmon, E.; Rhodes, M. W.; Saisut, J.; Thongbai, C.
2017-09-01
Development of an electron accelerator system, beam diagnostic instruments, an irradiation apparatus and electron beam processing methodology for natural rubber vulcanization is underway at the Plasma and Beam Physics Research Facility, Chiang Mai University, Thailand. The project is carried out with the aims to improve the qualities of natural rubber products. The system consists of a DC thermionic electron gun, 5-cell standing-wave radio-frequency (RF) linear accelerator (linac) with side-coupling cavities and an electron beam irradiation apparatus. This system is used to produce electron beams with an adjustable energy between 0.5 and 4 MeV and a pulse current of 10-100 mA at a pulse repetition rate of 20-400 Hz. An average absorbed dose between 160 and 640 Gy is expected to be archived for 4 MeV electron beam when the accelerator is operated at 400 Hz. The research activities focus firstly on assembling of the accelerator system, study on accelerator properties and electron beam dynamic simulations. The resonant frequency of the RF linac in π/2 operating mode is 2996.82 MHz for the operating temperature of 35 °C. The beam dynamic simulations were conducted by using the code ASTRA. Simulation results suggest that electron beams with an average energy of 4.002 MeV can be obtained when the linac accelerating gradient is 41.7 MV/m. The rms transverse beam size and normalized rms transverse emittance at the linac exit are 0.91 mm and 10.48 π mm·mrad, respectively. This information can then be used as the input data for Monte Carlo simulations to estimate the electron beam penetration depth and dose distribution in the natural rubber latex. The study results from this research will be used to define optimal conditions for natural rubber vulcanization with different electron beam energies and doses. This is very useful for development of future practical industrial accelerator units.
NASA Astrophysics Data System (ADS)
Dobrokhotov, S. Yu.; Shafarevich, A. I.; Tirozzi, B.
2008-06-01
The result of this paper is that any fast-decaying function can be represented as an integral over the canonical Maslov operator, on a special Lagrangian manifold, acting on a specific function. This representation enables one to construct effective explicit formulas for asymptotic solutions of a vast class of linear hyperbolic systems with variable coefficients.
Linear matrix inequalities for analysis and control of linear vector second-order systems
Adegas, Fabiano D.; Stoustrup, Jakob
2014-10-06
Many dynamical systems are modeled as vector second-order differential equations. This paper presents analysis and synthesis conditions in terms of LMI with explicit dependence in the coefficient matrices of vector second-order systems. These conditions benefit from the separation between the Lyapunov matrix and the system matrices by introducing matrix multipliers, which potentially reduce conservativeness in hard control problems. Multipliers facilitate the usage of parameter-dependent Lyapunov functions as certificates of stability of uncertain and time-varying vector second-order systems. The conditions introduced in this work have the potential to increase the practice of analyzing and controlling systems directly in vector second-order form.
Composite-step product methods for solving nonsymmetric linear systems
Chan, T.F.; Szeto, T.
1994-12-31
The Biconjugate Gradient (BCG) algorithm is the {open_quotes}natural{close_quotes} generalization of the classical Conjugate Gradient method to nonsymmetric linear systems. It is an attractive method because of its simplicity and its good convergence properties. Unfortunately, BCG suffers from two kinds of breakdowns (divisions by 0): one due to the non-existence of the residual polynomial, and the other due to a breakdown in the recurrence relationship used. There are many look-ahead techniques in existence which are designed to handle these breakdowns. Although the step size needed to overcome an exact breakdown can be computed in principle, these methods can unfortunately be quite complicated for handling near breakdowns since the sizes of the look-ahead steps are variable (indeed, the breakdowns can be incurable). Recently, Bank and Chan introduced the Composite Step Biconjugate Gradient (CSBCG) algorithm, an alternative which cures only the first of the two breakdowns mentioned by skipping over steps for which the BCG iterate is not defined. This is done with a simple modification of BCG which needs only a maximum look-ahead step size of 2 to eliminate the (near) breakdown and to smooth the sometimes erratic convergence of BCG. Thus, instead of a more complicated (but less prone to breakdown) version, CSBCG cures only one kind of breakdown, but does so with a minimal modification to the usual implementation of BCG in the hope that its empirically observed stability will be inherited. The authors note, then, that the Composite Step idea can be incorporated anywhere the BCG polynomial is used; in particular, in product methods such as CGS, Bi-CGSTAB, and TFQMR. Doing this not only cures the breakdown mentioned above, but also takes on the advantages of these product methods, namely, no multiplications by the transpose matrix and a faster convergence rate than BCG.
BenAbdallah, Abdallah; Hammami, Mohamed Ali; Kallel, Jalel
2009-03-05
In this paper we present some sufficient conditions for the robust stability and stabilization of time invariant uncertain piecewise linear system using homogenous piecewise polynomial Lyapunov function. The proposed conditions are given in terms of linear matrix inequalities which can be numerically solved. An application of the obtained result is given. It consists in resolving the stabilization of piecewise uncertain linear control systems by using a state piecewise linear feedback.
Dynamic MLC leaf sequencing for integrated linear accelerator control systems
Popple, Richard A.; Brezovich, Ivan A.
2011-11-15
Purpose: Leaf positions for dynamic multileaf collimator (DMLC) intensity modulated radiation therapy must be closely synchronized with MU delivery. For the Varian C3 series MLC controller, if the planned trajectory (leaf position vs. MU) requires velocities exceeding the capability of the MLC, the leaves fall behind the planned positions, causing the controller to momentarily hold the beam and thereby introduce dosimetric errors. We investigated the merits of a new commercial linear accelerator, TrueBeam, that integrates MLC control with prospective dose rate modulation. If treatment is delivered at dose rates so high that leaves would fall behind, the controller reduces the dose rate such that harmony between MU and leaf position is preserved. Methods: For three sets of DMLC leaf trajectories, point doses and two-dimensional dose distributions were measured in phantom using an ionization chamber and film, respectively. The first set, delivered using both a TrueBeam and a conventional C3 controller, comprised a single leaf bank closing at planned velocities of 2.4, 7.1, and 14 cm/s. The maximum achievable leaf velocity for both systems was 3 cm/s. The remaining two sets were derived from clinical fluence maps using a commercial treatment planning system for a range of planned dose rates and were delivered using TrueBeam set to the maximum dose rate, 600 MU/min. Generating trajectories using a planned dose rate that is lower than the delivery dose rate effectively increased the leaf velocity constraint used by the planning system for trajectory calculation. The second set of leaf trajectories was derived from two fluence maps containing regions of zero fluence obtained from representative beams of two different patient treatment plans. The third set was obtained from all nine fields of a head and neck treatment plan. For the head and neck plan, dose-volume histograms of the spinal cord and target for each planned dose rate were obtained. Results: For the single
Linear, Parameter-Varying Control of Aeroservoelastic Systems
NASA Astrophysics Data System (ADS)
Moreno Chicunque, Claudia Patricia
Modern aircraft designers are adopting light-weight, high-aspect ratio flexible wings to improve performance and reduce operation costs. A technical challenge associated with these designs is that the large deformations in flight of the wings lead to adverse interactions between the aircraft aerodynamic forces and structural forces. These adverse interactions produce excessive vibrations that can degrade flying qualities and may result in severe structural damages or catastrophic failure. This dissertation is focused on the application of multivariable robust control techniques for suppression of these adverse interactions in flexible aircraft. Here, the aircraft coupled nonlinear equations of motion are represented in the linear, parameter-varying framework. These equations account for the coupled aerodynamics, rigid body dynamics, and deformable body dynamics of the aircraft. Unfortunately, the inclusion of this coupled dynamics results in high-order models that increase the computational complexity of linear, parameter-varying control techniques. This dissertation addresses three key technologies for linear, parameter-varying control of flexible aircraft: (i) linear, parameter-varying model reduction; (ii) selection of actuators and sensors for vibration suppression; and (iii) design of linear, parameter-varying controllers for vibration suppression. All of these three technologies are applied to an experimental research platform located at the University of Minnesota. The objective of this dissertation is to provide to the flight control community with a set of design methodologies to safely exploit the benefits of light-weight flexible aircraft.
Gao, Fan; Latash, Mark L; Zatsiorsky, Vladimir M
2006-03-01
We address issues of simultaneous control of the grasping force and the total moment of forces applied to a handheld object during its manipulation. Six young healthy male subjects grasped an instrumented handle and performed its cyclic motion in the vertical direction. The handle allowed for setting different clockwise (negative) or counterclockwise torques. Three movement frequencies: 1, 1.5 and 2 Hz, and five different torques: -1/3, -1/6, 0, 1/6 and 1/3 Nm, were used. The rotational equilibrium was maintained by two means: (1) Concerted changes of the moments produced by the normal and tangential forces, specifically anti-phase changes of the moments during the tasks with zero external torque and in-phase changes during the non-zero-torque tasks, and (2) Redistribution of the normal forces among individual fingers such that the agonist fingers--the fingers that resist external torque--increased the force in phase with the acceleration, while the forces of the antagonist fingers--those that assist the external torque--especially, the fingers with the large moment arms, the index and little fingers, stayed unchanged. The observed effects agree with the principle of superposition--according to which some complex actions, for example, prehension, can be decomposed into elemental actions controlled independently--and the mechanical advantage hypothesis according to which in moment production the fingers are activated in proportion to their moment arms with respect to the axis of rotation. We would like to emphasize the linearity of the observed relations, which was not prescribed by the task mechanics and seems to be produced by specific neural control mechanisms.
Biological dysrhythm in remitted bipolar I disorder.
Iyer, Aishwarya; Palaniappan, Pradeep
2017-05-17
Recent treatment guidelines support treatment of biological rhythm abnormalities as a part of treatment of bipolar disorder, but still, literature examining various domains (Sleep, Activity, Social, and Eating) of biological rhythm and its clinical predictors are less. The main aim of our study is to compare various domains of biological rhythm among remitted bipolar I subjects and healthy controls. We also explored for any association between clinical variables and biological rhythm among bipolar subjects. 40 subjects with Bipolar I disorder and 40 healthy controls who met inclusion and exclusion criteria were recruited for the study. Diagnoses were ascertained by a qualified psychiatrist using MINI 5.0. Sociodemographic details, biological rhythm (BRIAN-Biological Rhythm Interview of assessment in Neuropsychiatry) and Sleep functioning (PSQI- Pittsburgh Sleep Quality Index) were assessed in all subjects. Mean age of the Bipolar subjects and controls were 41.25±11.84years and 38.25±11.25 years respectively. Bipolar subjects experienced more biological rhythm disturbance when compared to healthy controls (total BRIAN score being 34.25±9.36 vs 28.2±6.53) (p=0.002). Subsyndromal depressive symptoms (HDRS) had significant positive correlation with BRIAN global scores(r=0.368, p=0.02). Linear regression analysis showed that number of episodes which required hospitalization (β=0.601, t=3.106, P=0.004), PSQI (β=0.394, t=2.609, p=0.014), HDRS (β=0.376, t=2.34, t=0.036) explained 31% of variance in BRIAN scores in remitted bipolar subjects. Biological rhythm disturbances seem to persist even after clinical remission of bipolar illness. More studies to look into the impact of subsyndromal depressive symptoms on biological rhythm are needed. Copyright © 2017 Elsevier B.V. All rights reserved.
NASA Technical Reports Server (NTRS)
Jamison, J. W.
1994-01-01
CFORM was developed by the Kennedy Space Center Robotics Lab to assist in linear control system design and analysis using closed form and transient response mechanisms. The program computes the closed form solution and transient response of a linear (constant coefficient) differential equation. CFORM allows a choice of three input functions: the Unit Step (a unit change in displacement); the Ramp function (step velocity); and the Parabolic function (step acceleration). It is only accurate in cases where the differential equation has distinct roots, and does not handle the case for roots at the origin (s=0). Initial conditions must be zero. Differential equations may be input to CFORM in two forms - polynomial and product of factors. In some linear control analyses, it may be more appropriate to use a related program, Linear Control System Design and Analysis (KSC-11376), which uses root locus and frequency response methods. CFORM was written in VAX FORTRAN for a VAX 11/780 under VAX VMS 4.7. It has a central memory requirement of 30K. CFORM was developed in 1987.
NASA Technical Reports Server (NTRS)
Jamison, J. W.
1994-01-01
CFORM was developed by the Kennedy Space Center Robotics Lab to assist in linear control system design and analysis using closed form and transient response mechanisms. The program computes the closed form solution and transient response of a linear (constant coefficient) differential equation. CFORM allows a choice of three input functions: the Unit Step (a unit change in displacement); the Ramp function (step velocity); and the Parabolic function (step acceleration). It is only accurate in cases where the differential equation has distinct roots, and does not handle the case for roots at the origin (s=0). Initial conditions must be zero. Differential equations may be input to CFORM in two forms - polynomial and product of factors. In some linear control analyses, it may be more appropriate to use a related program, Linear Control System Design and Analysis (KSC-11376), which uses root locus and frequency response methods. CFORM was written in VAX FORTRAN for a VAX 11/780 under VAX VMS 4.7. It has a central memory requirement of 30K. CFORM was developed in 1987.
Some estimation formulae for continuous time-invariant linear systems
NASA Technical Reports Server (NTRS)
Bierman, G. J.; Sidhu, G. S.
1975-01-01
In this brief paper we examine a Riccati equation decomposition due to Reid and Lainiotis and apply the result to the continuous time-invariant linear filtering problem. Exploitation of the time-invariant structure leads to integration-free covariance recursions which are of use in covariance analyses and in filter implementations. A super-linearly convergent iterative solution to the algebraic Riccati equation (ARE) is developed. The resulting algorithm, arranged in a square-root form, is thought to be numerically stable and competitive with other ARE solution methods. Certain covariance relations that are relevant to the fixed-point and fixed-lag smoothing problems are also discussed.
NASA Astrophysics Data System (ADS)
Clifford, J. E.
1984-06-01
The status of development of bipolar batteries with an aqueous electrolyte was determined. Included in the study were lead-acid, nickel-cadmium, nickel-zinc, nickel-iron, and nickel-hydrogen batteries. The technical and patent literature is reviewed and a bibliography covering the past 15 years is presented. Literature data are supplemented by a survey of organizations. The principal interest was in bipolar lead-acid batteries and more recently in bipolar nickel-hydrogen batteries for space applications.
Performance Models for the Spike Banded Linear System Solver
Manguoglu, Murat; Saied, Faisal; Sameh, Ahmed; ...
2011-01-01
With availability of large-scale parallel platforms comprised of tens-of-thousands of processors and beyond, there is significant impetus for the development of scalable parallel sparse linear system solvers and preconditioners. An integral part of this design process is the development of performance models capable of predicting performance and providing accurate cost models for the solvers and preconditioners. There has been some work in the past on characterizing performance of the iterative solvers themselves. In this paper, we investigate the problem of characterizing performance and scalability of banded preconditioners. Recent work has demonstrated the superior convergence properties and robustness of banded preconditioners,more » compared to state-of-the-art ILU family of preconditioners as well as algebraic multigrid preconditioners. Furthermore, when used in conjunction with efficient banded solvers, banded preconditioners are capable of significantly faster time-to-solution. Our banded solver, the Truncated Spike algorithm is specifically designed for parallel performance and tolerance to deep memory hierarchies. Its regular structure is also highly amenable to accurate performance characterization. Using these characteristics, we derive the following results in this paper: (i) we develop parallel formulations of the Truncated Spike solver, (ii) we develop a highly accurate pseudo-analytical parallel performance model for our solver, (iii) we show excellent predication capabilities of our model – based on which we argue the high scalability of our solver. Our pseudo-analytical performance model is based on analytical performance characterization of each phase of our solver. These analytical models are then parameterized using actual runtime information on target platforms. An important consequence of our performance models is that they reveal underlying performance bottlenecks in both serial and parallel formulations. All of our results are validated
Towards Stability Analysis of Jump Linear Systems with State-Dependent and Stochastic Switching
NASA Technical Reports Server (NTRS)
Tejada, Arturo; Gonzalez, Oscar R.; Gray, W. Steven
2004-01-01
This paper analyzes the stability of hierarchical jump linear systems where the supervisor is driven by a Markovian stochastic process and by the values of the supervised jump linear system s states. The stability framework for this class of systems is developed over infinite and finite time horizons. The framework is then used to derive sufficient stability conditions for a specific class of hybrid jump linear systems with performance supervision. New sufficient stochastic stability conditions for discrete-time jump linear systems are also presented.
Prisciandaro, James J.; Tolliver, Bryan K.
2016-01-01
Background Evidence supporting the continuous latent structure of mood phenomena has not been incorporated into psychiatric diagnostic systems, in part because the evidence has been incomplete. For example, no studies have investigated the boundary between "sick" and "well" periods in individuals with bipolar disorder, despite agreement that characterization of mood disorders as having a discrete episodic course is inaccurate. The present study examined the validity of mood episode symptom thresholds in outpatients with bipolar disorder using multiple methodologies: taxometrics and information-theoretic latent distribution modeling (ITLDM), to evaluate the continuity/discontinuity of mood symptoms, and structural equation mixture modeling (SEMM), to evaluate the continuity/discontinuity of associations between mood symptoms and general functioning. Methods 3,721 outpatients with bipolar disorder from the Systematic Treatment Enhancement Program for Bipolar Disorder (STEP-BD) were available for analysis. Data were collected at participants' baseline STEP-BD visit. Taxometric (MAXCOV/MAMBAC with simulated comparison data), ITLDM, and SEMM methods were applied twice, once to the Montgomery-Asberg Depression Rating Scale and again to the Young Mania Rating Scale. Results Taxometric results unequivocally supported a continuous interpretation of the data. ITLDM results favored many-valued "discrete metrical" models suggesting that mood symptoms have continuous, but potentially non-normally distributed, latent structures in outpatients with bipolar disorder. Finally, SEMM results demonstrated that latent associations between mood symptoms and general functioning were linear. Conclusions Results from the present study argue against the validity of DSM mood episode thresholds and argue for a graded continuum of care of bipolar symptom management. PMID:25881582
Variational Iterative Methods for Nonsymmetric Systems of Linear Equations.
1981-08-01
approximations to the convection diffusion equation. In Society of Petroleum Engineers of AIME, Proceedinus of the Fifth Svmnosium on Reservoir Simulation , 1979...simultaneous linear equations. In Society of Petroleum Engineers of ADIE, Proceedings 2f the Fourth SyvMosium on Reservoir Simulation , 1976, pp. 149
Sabelli, H C; Carlson-Sabelli, L; Javaid, J I
1990-11-01
Two models dominate current formulations of bipolar illness: the homeostatic model implicit in Freud's psychodynamics and most neuroamine deficit/excess theories; and the oscillatory model of exaggerated biological rhythms. The homeostatic model is based on the closed systems approach of classic thermodynamics, while the oscillatory model requires the open systems approach of modern thermodynamics. Here we present a thermodynamic model of bipolarity that includes both homeostatic and oscillatory features and adds the most important feature of open systems thermodynamics: the creation of novel structures in bifurcation processes. According to the proposed model, bipolarity is the result of exaggerated biological energy that augments homeostatic, oscillatory and creative psychological processes. Only low-energy closed systems tend to rest ("point attractor") and entropic disorder. Open processes containing and exchanging energy fluctuate between opposite states ("periodic attractors"); they are characteristic of most physiological rhythms and are exaggerated in bipolar subjects. At higher energies, their strong fluctuations destroy pre-existing patterns and structures, produce turbulence ("chaotic attractors"), which sudden switches between opposite states, and create new and more complex structures. Likewise, high-energy bipolars develop high spontaneity, great fluctuations between opposite moods, internal and interpersonal chaos, and enhanced creativity (personal, artistic, professional) as well as psychopathology (personality deviations, psychotic delusions). Offered here is a theoretical explanation of the dual--creative and destructive--nature of bipolarity in terms of the new enantiodromic concept of entropy generalized by process theory. Clinically, this article offers an integrative model of bipolarity that accounts for many clinical features and contributes to a definition of the bipolar personality.
Conjugate gradient type methods for linear systems with complex symmetric coefficient matrices
NASA Technical Reports Server (NTRS)
Freund, Roland
1989-01-01
We consider conjugate gradient type methods for the solution of large sparse linear system Ax equals b with complex symmetric coefficient matrices A equals A(T). Such linear systems arise in important applications, such as the numerical solution of the complex Helmholtz equation. Furthermore, most complex non-Hermitian linear systems which occur in practice are actually complex symmetric. We investigate conjugate gradient type iterations which are based on a variant of the nonsymmetric Lanczos algorithm for complex symmetric matrices. We propose a new approach with iterates defined by a quasi-minimal residual property. The resulting algorithm presents several advantages over the standard biconjugate gradient method. We also include some remarks on the obvious approach to general complex linear systems by solving equivalent real linear systems for the real and imaginary parts of x. Finally, numerical experiments for linear systems arising from the complex Helmholtz equation are reported.
The convergence of the modified Gauss-Seidel methods for consistent linear systems
NASA Astrophysics Data System (ADS)
Li, Wen
2003-05-01
In this paper we present a convergence analysis for the modified Gauss-Seidel methods given in Gunawardena et al. (Linear Algebra Appl. 154-156 (1991) 125) and Kohno et al. (Linear Algebra Appl. 267 (1997) 113) for consistent linear systems. We prove that the modified Gauss-Seidel method converges for some values of the parameters in the preconditioned matrix.
Amplitude Linearizers for PEP-II 1.2 MW Klystrons and LLRF Systems
Van Winkle, D.; Browne, J.; Fox, J.D.; Mastorides, T.; Rivetta, C.; Teytelman, D.; /SLAC
2006-07-18
The PEP-II B-factory has aggressive current increases planned for luminosity through 2008. At 2.2A (HER) on 4A (LER) currents, we estimate that longitudinal growth rates will be comparable to the damping rates currently achieved in the existing low level RF and longitudinal feedback systems. Prior to having a good non-linear time domain model [1] it was postulated that klystron small signal gain non-linearity may be contributing to measured longitudinal growth rates being higher than linearly predicted growth rates. Five prototype klystron amplitude modulation linearizers have been developed to explore improved linearity in the LLRF system. The linearizers operate at 476 MHz with 15 dB dynamic range and 1 MHz linear control bandwidth. Results from lab measurements and high current beam tests are presented. Future development plans, conclusions from beam testing and ideas for future use of this linearization technique are presented.
ATOPS B-737 inner-loop control system linear model construction and verification
NASA Technical Reports Server (NTRS)
Broussard, J. R.
1983-01-01
Nonlinear models and block diagrams of an inner-loop control system for the ATOPS B-737 Research Aircraft are presented. Continuous time linear model representations of the nonlinear inner-loop control systems are derived. Closed-loop aircraft simulations comparing nonlinear and linear dynamic responses to step inputs are used to verify the inner-loop control system models.
Solution of homogeneous systems of linear equations arising from compartmental models
Funderlic, R.E.; Mankin, J.B.
1981-12-01
Systems of linear differential equations with constant coefficients, Ax = x, with the matrix A having nonnegative off-diagnonal elements and zero column sums, occur in compartmental analysis. The steady-state solution leads to the homogeneous system of linear equations Ax(infinity)=x(infinity)=0. LU-factorization, the Crout algorithm, error analysis and solution of a modified system are treated.
Model reference adaptive control for linear time varying and nonlinear systems
NASA Technical Reports Server (NTRS)
Abida, L.; Kaufman, H.
1982-01-01
Model reference adaptive control is applied to linear time varying systems and to nonlinear systems amenable to virtual linearization. Asymptotic stability is guaranteed even if the perfect model following conditions do not hold, provided that some sufficient conditions are satisfied. Simulations show the scheme to be capable of effectively controlling certain nonlinear systems.
Tansey, Katherine E; Guipponi, Michel; Domenici, Enrico; Lewis, Glyn; Malafosse, Alain; O'Donovan, Michael; Wendland, Jens R; Lewis, Cathryn M; McGuffin, Peter; Uher, Rudolf
2014-01-01
The high heterogeneity of response to antidepressant treatment in major depressive disorder (MDD) makes individual treatment outcomes currently unpredictable. It has been suggested that resistance to antidepressant treatment might be due to undiagnosed bipolar disorder or bipolar spectrum features. Here, we investigate the relationship between genetic susceptibility for bipolar disorder and response to treatment with antidepressants in MDD. Polygenic scores indexing risk for bipolar disorder were derived from the Psychiatric Genomics Consortium Bipolar Disorder whole genome association study. Linear regressions tested the effect of polygenic risk scores for bipolar disorder on proportional reduction in depression severity in two large samples of individuals with MDD, treated with antidepressants, NEWMEDS (n=1,791) and STAR*D (n=1,107). There was no significant association between polygenic scores for bipolar disorder and response to treatment with antidepressants. Our data indicate that molecular measure of genetic susceptibility to bipolar disorder does not aid in understanding non-response to antidepressants.
AN INTRODUCTION TO THE APPLICATION OF DYNAMIC PROGRAMMING TO LINEAR CONTROL SYSTEMS
DYNAMIC PROGRAMMING APPLIED TO OPTIMIZE LINEAR CONTROL SYSTEMS WITH QUADRATIC PERFORMANCE MEASURES. MATHEMATICAL METHODS WHICH MAY BE APPLIED TO SPACE VEHICLE AND RELATED GUIDANCE AND CONTROL PROBLEMS.
Linear stochastic system with delay: Energy balance and entropy production
NASA Astrophysics Data System (ADS)
Munakata, Toyonori; Iwama, Shinpei; Kimizuka, Makoto
2009-03-01
We study the energy balance in a linear stochastic dynamics with delay under the impact of an external periodic force. The linearity of the model, in combination with a response function method, enables us to perform detailed analytic calculations of each term in the energy balance equation. From this, we discuss thermodynamics and entropy production rate σ . With use of the delay time τ and strength of the external force A0 , σ is simply expressed as σ=σD,1(τ)+A02η(τ) , with both σD,1(τ) and η(τ) positive definite. We thus conclude that even when there is no external force (A0=0) , the entropy production rate σ=σD,1(τ) is positive, meaning that the delay force produces work, which is dissipated into a reservoir. Numerical experiments are performed to confirm theoretical results.
Arjmand, Shokouh; Behzadi, Mina; Stephens, Gary J; Ezzatabadipour, Sara; Seifaddini, Rostam; Arjmand, Shahrad; Shabani, Mohammad
2017-06-01
One of the most interesting but tenebrous parts of the bipolar disorder (BD) story is the switch between (hypo)mania and depression, which can give bipolar patients a thrilling, but somewhat perilous, 'ride'. Numerous studies have pointed out that there are some recognizable differences (either state-dependent or state-independent) in several brain regions of people with BD, including components of the brain's reward system. Understanding the underpinning mechanisms of high and low mood statuses in BD has potential, not only for the development of highly specific and selective pharmaceutical agents, but also for better treatment approaches and psychological interventions to manage BD and, thus, give patients a safer ride. Herein, we review evidence that supports involvement of the reward system in the pathophysiology of mood swings, with the main focus on the mesocorticolimbic dopaminergic neural circuitry. Principally using findings from neuroimaging studies, we aim to signpost readers as to how mood alterations may affect different areas of the reward system and how antipsychotic drugs can influence the activity of these brain areas. Finally, we critically evaluate the hypothesis that the mesocorticolimbic dopamine reward system may act as a functional rheostat for different mood states.
Modelling and Resource Allocation of Linearly Restricted Operating Systems.
1979-12-01
services thus rendered are the products . Clearly, in a limited resource situation, how best to dispense the available resources to achieve some...Preliminary Although a linear programming model for an economic problem had been developed as early as 1939 by the Russian mathematician L. Kantorovich...individual user programs) to achieve productions (computations). The purpose is then to devise a way (A plan) to allocate those available memory spaces
Analysis and Regulation of Nonlinear and Generalized Linear Systems.
1985-09-06
But this intuition is based on a linearized analysis, and may well be too conservative -or even totally inappropiate - for a particular (global...in the field of stochastic estimation. Given a time series, it is often possible to compute sufficient statistics of the associated process...and dynamically updating sufficient statistics with finite resources had received almost no attention in the literature, and turns out to be
A final focus system for the Next Linear Collider
Zimmermann, F.; Brown, K.; Emma, P.; Helm, R.; Irwin, J.; Tenenbaum, P.; Wilson, P.
1995-06-01
The final focus of the Next Linear Collider (NLC) demagnifies electron and positron beams of 250--750 GeV energy down to a transverse size of about 2.5 {times} 350 nm{sup 2} at the interaction point (IP). The basic layout, momentum bandwidth, vibration tolerances, wakefield effects, and the tunability of the proposed final focus design are discussed. Also a perspective is given on the crab cavity and on effects of the solenoid field in the interaction region.
On stochastic control system design methods for weakly coupled large scale linear systems.
NASA Technical Reports Server (NTRS)
Kwong, R.; Chong, C.-Y.; Athans, M.
1972-01-01
This paper considers the problem of decentralized control of two weakly coupled linear stochastic systems, using quadratic performance indices. The basic idea is to have each controller control independently his own system, based upon noisy measurements of his own output. To compensate for the effects of weak coupling upon the resultant performance, fake white plant noise is introduced to each system. The appropriate intensity of the fake plant noise is obtained through the solution of an off-line deterministic matrix optimal control problem. The effects of this design method upon the overall coupled system performance are analyzed as a function of the degree of intersystem coupling.
Algebraic coarsening methods for linear and nonlinear PDE and systems
McWilliams, J C
2000-11-06
In [l] Brandt describes a general approach for algebraic coarsening. Given fine-grid equations and a prescribed relaxation method, an approach is presented for defining both the coarse-grid variables and the coarse-grid equations corresponding to these variables. Although, these two tasks are not necessarily related (and, indeed, are often performed independently and with distinct techniques) in the approaches of [1] both revolve around the same underlying observation. To determine whether a given set of coarse-grid variables is appropriate it is suggested that one should employ compatible relaxation. This is a generalization of so-called F-relaxation (e.g., [2]). Suppose that the coarse-grid variables are defined as a subset of the fine-grid variables. Then, F-relaxation simply means relaxing only the F-variables (i.e., fine-grid variables that do not correspond to coarse-grid variables), while leaving the remaining fine-grid variables (C-variables) unchanged. The generalization of compatible relaxation is in allowing the coarse-grid variables to be defined differently, say as linear combinations of fine-grid variables, or even nondeterministically (see examples in [1]). For the present summary it suffices to consider the simple case. The central observation regarding the set of coarse-grid variables is the following [1]: Observation 1--A general measure for the quality of the set of coarse-grid variables is the convergence rate of compatible relaxation. The conclusion is that a necessary condition for efficient multigrid solution (e.g., with convergence rates independent of problem size) is that the compatible-relaxation convergence be bounded away from 1, independently of the number of variables. This is often a sufficient condition, provided that the coarse-grid equations are sufficiently accurate. Therefore, it is suggested in [1] that the convergence rate of compatible relaxation should be used as a criterion for choosing and evaluating the set of coarse
Dissipative open systems theory as a foundation for the thermodynamics of linear systems.
Delvenne, Jean-Charles; Sandberg, Henrik
2017-03-06
In this paper, we advocate the use of open dynamical systems, i.e. systems sharing input and output variables with their environment, and the dissipativity theory initiated by Jan Willems as models of thermodynamical systems, at the microscopic and macroscopic level alike. We take linear systems as a study case, where we show how to derive a global Lyapunov function to analyse networks of interconnected systems. We define a suitable notion of dynamic non-equilibrium temperature that allows us to derive a discrete Fourier law ruling the exchange of heat between lumped, discrete-space systems, enriched with the Maxwell-Cattaneo correction. We complete these results by a brief recall of the steps that allow complete derivation of the dissipation and fluctuation in macroscopic systems (i.e. at the level of probability distributions) from lossless and deterministic systems.This article is part of the themed issue 'Horizons of cybernetical physics'. © 2017 The Author(s).
Dissipative open systems theory as a foundation for the thermodynamics of linear systems
NASA Astrophysics Data System (ADS)
Delvenne, Jean-Charles; Sandberg, Henrik
2017-03-01
In this paper, we advocate the use of open dynamical systems, i.e. systems sharing input and output variables with their environment, and the dissipativity theory initiated by Jan Willems as models of thermodynamical systems, at the microscopic and macroscopic level alike. We take linear systems as a study case, where we show how to derive a global Lyapunov function to analyse networks of interconnected systems. We define a suitable notion of dynamic non-equilibrium temperature that allows us to derive a discrete Fourier law ruling the exchange of heat between lumped, discrete-space systems, enriched with the Maxwell-Cattaneo correction. We complete these results by a brief recall of the steps that allow complete derivation of the dissipation and fluctuation in macroscopic systems (i.e. at the level of probability distributions) from lossless and deterministic systems. This article is part of the themed issue 'Horizons of cybernetical physics'.
Bipolar Treatment: Are Bipolar I and Bipolar II Treated Differently?
... and the antipsychotic olanzapine. It works as a depression treatment and a mood stabilizer. Symbyax is approved by ... Current landscape, unmet needs and future directions for treatment of bipolar depression. Journal of Affective Disorders. 2014;169S1:S17. Frye ...
Yu, Xue; Liang, Jiying; Yang, Tiangang; Gong, Mengjie; Xi, Dongman; Liu, Hongyun
2018-01-15
Herein, a resettable and reprogrammable biomolecular keypad lock on the basis of a closed bipolar electrode (BPE) system was established. In this system, one ITO electrode with immobilized chitosan (CS) and glucose oxidase (GOD), designated as CS-GOD, acted as one pole of BPE in the sensing cell; another ITO with electrodeposited Prussian blue (PB) films as the other pole in the reporting cell. The addition of ascorbic acid (AA) in the sensing cell with driving voltage (Vtot) at +2.5V would make the PB films become Prussian white (PW) in the reporting cell, accompanied by the color change from blue to nearly transparent. On the other hand, with the help of oxygen, the addition of glucose in the sensing cell with Vtot at -1.5V would induce PW back to PB. The change of color and the corresponding UV-vis absorbance at 700nm for the PB/PW films in the reporting cell could be reversibly switched by changing the solute in the sensing cell between AA and glucose and then switching Vtot between +2.5 and -1.5V. Based on these, a keypad lock was developed with AA, glucose and Vtot as 3 inputs, and the color change of the PB/PW films as the output. This keypad lock system combined enzymatic catalysis with bipolar electrochemistry, demonstrating some unique advantages such as good reprogrammability, easy resettability and visual readout by naked eye. Copyright © 2017 Elsevier B.V. All rights reserved.
Analysis and application of minimum variance discrete linear system identification
NASA Technical Reports Server (NTRS)
Kotob, S.; Kaufman, H.
1977-01-01
An on-line minimum variance (MV) parameter identifier is developed which embodies both accuracy and computational efficiency. The formulation results in a linear estimation problem with both additive and multiplicative noise (AMN). The resulting filter which utilizes both the covariance of the parameter vector itself and the covariance of the error in identification is proven to be mean-square convergent and mean-square consistent. The MV parameter identification scheme is then used to construct a stable state and parameter estimation algorithm.
On Decay Estimates of Solutions to One-dimensional Linear Parabolic Feedback Control Systems
NASA Astrophysics Data System (ADS)
Nambu, Takao
In feedback stabilization for linear parabolic systems,a control scheme is designed so that the “state” of the system decays with a designated decay rate as t → ∞. An arbitrary linear functional of the state, which is subordinate to the state, also decays at least with the same decay rate. We study in the paper a class of linear parabolic systems of one dimension, and construct a specific control scheme such that a nontrivial linear functional decays exactly faster than the state.
Forsthoff, A; Born, C; Grunze, H
2005-05-17
Despite many advances in making the diagnosis of bipolar disorder, five to twelve years lie between the first affective episode and the introduction of an effective treatment. However, it is estimated that approximately only one-fourth of the patients with bipolar disorder are recognized as such at all. Clinical experience plays an important role in the diagnosis. Manias are often the cause for the first treatment with drugs, but the daily lives of patients with bipolar depression are often clearly more negatively affected. The acute therapy of bipolar depression is more complicated than that of mania and the difficult long-term treatment is always associated with a high suicide risk. A long-term therapy of bipolar disorders is not only meaningful for the prevention of new disease episodes, but also because it has a positive effect on comorbidities.
Thermal chondroplasty: effect of bipolar and monopolar radio frequency energy
NASA Astrophysics Data System (ADS)
Edwards, Ryland B.; Lu, Yan; Cole, Brian J.; Markel, Mark D.
2001-06-01
Cartilage fibrillation is commonly associated with injury and long-term degeneration. Contouring the articular surface with radiofrequency energy (RFE) may stabilize the surface, and improve clinical function, but subchondral bone injury has been reported in some patients. The purpose of this research was to document the effects of bipolar and monopolar RFE on articular cartilage. Bipolar RFE and monopolar RFE treatment of abraded bovine cartilage was investigated in an in vitro model. Bipolar RFE caused greater chondrocyte death than monopolar RFE, (bipolar RFE: 1700-mm; monopolar RFE: 800-mm) (p<0.05). Both bipolar RFE and monopolar RFE contoured the articular surface but the depth of chondrocyte death raised concerns regarding the clinical application of RFE. Further work investigated the arthroscopic application of bipolar RFE and monopolar RFE on human chondromalacic cartilage in vitro. Both devices smoothed the fibrillated surface, but bipolar RFE caused increased depth of chondrocyte death compared to monopolar RFE (bipolar RFE 2100-mm; monopolar RFE 620-mm (p<0.05). Fluoroptic thermometry has demonstrated cartilage matrix temperatures exceeding 70° C 2-mm below the articular surface during the application of bipolar RFE. The clinical use of the bipolar RFE systems available to date will likely result in unacceptable chondrocyte death and subchondral injury. While RFE demonstrates some promise for the management of cartilage injury, further work must be completed to define the parameters for its application.
Using crosscorrelation techniques to determine the impulse response of linear systems
NASA Technical Reports Server (NTRS)
Dallabetta, Michael J.; Li, Harry W.; Demuth, Howard B.
1993-01-01
A crosscorrelation method of measuring the impulse response of linear systems is presented. The technique, implementation, and limitations of this method are discussed. A simple system is designed and built using discrete components and the impulse response of a linear circuit is measured. Theoretical and software simulation results are presented.
Guidi, Andrea; Salvi, Sergio; Ottaviano, Manuel; Gentili, Claudio; Bertschy, Gilles; de Rossi, Danilo; Scilingo, Enzo Pasquale; Vanello, Nicola
2015-11-06
Bipolar disorder is one of the most common mood disorders characterized by large and invalidating mood swings. Several projects focus on the development of decision support systems that monitor and advise patients, as well as clinicians. Voice monitoring and speech signal analysis can be exploited to reach this goal. In this study, an Android application was designed for analyzing running speech using a smartphone device. The application can record audio samples and estimate speech fundamental frequency, F0, and its changes. F0-related features are estimated locally on the smartphone, with some advantages with respect to remote processing approaches in terms of privacy protection and reduced upload costs. The raw features can be sent to a central server and further processed. The quality of the audio recordings, algorithm reliability and performance of the overall system were evaluated in terms of voiced segment detection and features estimation. The results demonstrate that mean F0 from each voiced segment can be reliably estimated, thus describing prosodic features across the speech sample. Instead, features related to F0 variability within each voiced segment performed poorly. A case study performed on a bipolar patient is presented.
Guidi, Andrea; Salvi, Sergio; Ottaviano, Manuel; Gentili, Claudio; Bertschy, Gilles; de Rossi, Danilo; Scilingo, Enzo Pasquale; Vanello, Nicola
2015-01-01
Bipolar disorder is one of the most common mood disorders characterized by large and invalidating mood swings. Several projects focus on the development of decision support systems that monitor and advise patients, as well as clinicians. Voice monitoring and speech signal analysis can be exploited to reach this goal. In this study, an Android application was designed for analyzing running speech using a smartphone device. The application can record audio samples and estimate speech fundamental frequency, F0, and its changes. F0-related features are estimated locally on the smartphone, with some advantages with respect to remote processing approaches in terms of privacy protection and reduced upload costs. The raw features can be sent to a central server and further processed. The quality of the audio recordings, algorithm reliability and performance of the overall system were evaluated in terms of voiced segment detection and features estimation. The results demonstrate that mean F0 from each voiced segment can be reliably estimated, thus describing prosodic features across the speech sample. Instead, features related to F0 variability within each voiced segment performed poorly. A case study performed on a bipolar patient is presented. PMID:26561811
Characterization of the system functions of ultrasonic linear phased array inspection systems.
Huang, Ruiju; Schmerr, Lester W
2009-02-01
This work characterizes the electrical and electromechanical aspects of an ultrasonic linear phased array inspection system, using a matrix of system functions that are obtained from the measured response of individual array elements in a simple reference experiment. It is shown that for the arrays tested all these system functions are essentially identical, allowing one to use a single system function to characterize the entire array, as done for an ordinary single element transducer. The variation of this single system function with the number of elements firing in the array or with changes of the delay law used is examined. It is also demonstrated that once such a single system function is obtained for an array, it can be used in a complete ultrasonic measurement model to accurately predict the array response measured from a reference reflector in an immersion setup.
A Design Method for Pole Placement and Observer of Linear Time-Varying Discrete MIMO Systems
NASA Astrophysics Data System (ADS)
Mutoh, Yasuhiko; Hara, Tomohiro
It is well known that, the pole placement controller can be designing for linear time-varying systems using the Frobenius canonical form, as for the time invariant case. This paper presents the new approach to the design of the pole placement controller for linear time-varying discrete multivariable systems. The concept of the relative degrees of multivariable system plays an important role, and the time-varying feedback gain can be simply calculated without transforming the system into any canonical form, which is regarded as a discrete Ackerman's method. This method is applied in order to calculate the observer gain for linear time-varying systems.
Wang, Jinglu; Qu, Susu; Wang, Weixiao; Guo, Liyuan; Zhang, Kunlin; Chang, Suhua; Wang, Jing
2016-11-01
Numbers of gene expression profiling studies of bipolar disorder have been published. Besides different array chips and tissues, variety of the data processes in different cohorts aggravated the inconsistency of results of these genome-wide gene expression profiling studies. By searching the gene expression databases, we obtained six data sets for prefrontal cortex (PFC) of bipolar disorder with raw data and combinable platforms. We used standardized pre-processing and quality control procedures to analyze each data set separately and then combined them into a large gene expression matrix with 101 bipolar disorder subjects and 106 controls. A standard linear mixed-effects model was used to calculate the differentially expressed genes (DEGs). Multiple levels of sensitivity analyses and cross validation with genetic data were conducted. Functional and network analyses were carried out on basis of the DEGs. In the result, we identified 198 unique differentially expressed genes in the PFC of bipolar disorder and control. Among them, 115 DEGs were robust to at least three leave-one-out tests or different pre-processing methods; 51 DEGs were validated with genetic association signals. Pathway enrichment analysis showed these DEGs were related with regulation of neurological system, cell death and apoptosis, and several basic binding processes. Protein-protein interaction network further identified one key hub gene. We have contributed the most comprehensive integrated analysis of bipolar disorder expression profiling studies in PFC to date. The DEGs, especially those with multiple validations, may denote a common signature of bipolar disorder and contribute to the pathogenesis of disease. Copyright © 2016 Elsevier Ltd. All rights reserved.
Dynamics and thermodynamics of linear quantum open systems.
Martinez, Esteban A; Paz, Juan Pablo
2013-03-29
We analyze the evolution of the quantum state of networks of quantum oscillators coupled with arbitrary external environments. We show that the reduced density matrix of the network always obeys a local master equation with a simple analytical solution. We use this to study the emergence of thermodynamical laws in the long time regime demonstrating two main results: First, we show that it is impossible to build a quantum absorption refrigerator using linear networks (thus, nonlinearity is an essential resource for such refrigerators recently studied by Levy and Kosloff [Phys. Rev. Lett. 108, 070604 (2012)] and Levy et al. [Phys. Rev. B 85, 061126 (2012)]). Then, we show that the third law imposes constraints on the low frequency behavior of the environmental spectral densities.
Attractor reconstruction for non-linear systems: a methodological note
Nichols, J.M.; Nichols, J.D.
2001-01-01
Attractor reconstruction is an important step in the process of making predictions for non-linear time-series and in the computation of certain invariant quantities used to characterize the dynamics of such series. The utility of computed predictions and invariant quantities is dependent on the accuracy of attractor reconstruction, which in turn is determined by the methods used in the reconstruction process. This paper suggests methods by which the delay and embedding dimension may be selected for a typical delay coordinate reconstruction. A comparison is drawn between the use of the autocorrelation function and mutual information in quantifying the delay. In addition, a false nearest neighbor (FNN) approach is used in minimizing the number of delay vectors needed. Results highlight the need for an accurate reconstruction in the computation of the Lyapunov spectrum and in prediction algorithms.
Dynamics and Thermodynamics of Linear Quantum Open Systems
NASA Astrophysics Data System (ADS)
Martinez, Esteban A.; Paz, Juan Pablo
2013-03-01
We analyze the evolution of the quantum state of networks of quantum oscillators coupled with arbitrary external environments. We show that the reduced density matrix of the network always obeys a local master equation with a simple analytical solution. We use this to study the emergence of thermodynamical laws in the long time regime demonstrating two main results: First, we show that it is impossible to build a quantum absorption refrigerator using linear networks (thus, nonlinearity is an essential resource for such refrigerators recently studied by Levy and Kosloff [Phys. Rev. Lett. 108, 070604 (2012)] and Levy et al. [Phys. Rev. B 85, 061126 (2012)]). Then, we show that the third law imposes constraints on the low frequency behavior of the environmental spectral densities.
Linear and/or curvilinear rail mount system
NASA Technical Reports Server (NTRS)
Thomas, Jackie D. (Inventor); Harris, Lawanna L. (Inventor)
2012-01-01
One or more linear and/or curvilinear mounting rails are coupled to a structure. Each mounting rail defines a channel and at least one cartridge assembly is engaged in the channel. Each cartridge assembly includes a housing that slides within the channel. The housing defines a curvilinearly-shaped recess longitudinally aligned with the channel when the housing is in engagement therewith. The cartridge assembly also includes a cleat fitted in the recess for sliding engagement therealong. The cleat can be coupled to a fastener that passes through the mounting rail and the housing when the housing is so-engaged in the channel. The cleat is positioned in the recess by a position of the fastener.
Dynamic Performance of Subway Vehicle with Linear Induction Motor System
NASA Astrophysics Data System (ADS)
Wu, Pingbo; Luo, Ren; Hu, Yan; Zeng, Jing
The light rail vehicle with Linear Induction Motor (LIM) bogie, which is a new type of urban rail traffic tool, has the advantages of low costs, wide applicability, low noise, simple maintenance and better dynamic behavior. This kind of vehicle, supported and guided by the wheel and rail, is not driven by the wheel/rail adhesion force, but driven by the electromagnetic force between LIM and reaction plate. In this paper, three different types of suspensions and their characteristic are discussed with considering the interactions both between wheel and rail and between LIM and reaction plate. A nonlinear mathematical model of the vehicle with LIM bogie is set up by using the software SIMPACK, and the electromechanical model is also set up on Simulink roof. Then the running behavior of the LIM vehicle is simulated, and the influence of suspension on the vehicle dynamic performance is investigated.
Linear polarization of a group of symbiotic systems
NASA Astrophysics Data System (ADS)
Brandi, E.; García, L. G.; Piirola, V.; Scaltriti, F.; Quiroga, C.
2000-08-01
We report linear polarization measurements of a set of symbiotic stars, made at several epochs during the period 1994-1998. Evidence of intrinsic polarization is looked for from the wavelength dependence of the polarization degree and position angle in UBVRI bands. The results have also been analysed to search for temporal variability of polarization. Several objects have shown a polarization spectrum different from that produced by interstellar dust grains and/or polarimetric variations on time scales as short as several days or months, indicating the presence of polarization component of circumstellar origin. Based on observations taken at Complejo Astronómico El Leoncito (CASLEO), operated under an agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina, the Secretaría de Ciencia y Tecnología de la Nación and the National Universities of La Plata, Córdoba and San Juan.
Robust stabilization, robust performance, and disturbance attenuation for uncertain linear systems
NASA Technical Reports Server (NTRS)
Wang, Yeih J.; Shieh, Leang S.; Sunkel, John W.
1992-01-01
This paper presents a linear quadratic regulator approach to the robust stabilization, robust performance, and disturbance attenuation of uncertain linear systems. The state-feedback designed systems provide both the robust stability with optimal performance and the disturbance attenuation with H-infinity-norm bounds. The proposed approach can be applied to matched and/or mismatched uncertain linear systems. For a matched uncertain linear system, it is shown that the disturbance attenuation robust-stabilizing controllers with or without optimal performance always exist and can be easily determined without searching; whereas, for a mismatched uncertain linear system, the introduced tuning parameters greatly enhance the flexibility of finding the disturbance-attenuation robust-stabilizing controllers.
Noise robust linear dynamic system for phase unwrapping and smoothing.
Estrada, Julio C; Servin, Manuel; Quiroga, Juan A
2011-03-14
Phase unwrapping techniques remove the modulus ambiguities of wrapped phase maps. The present work shows a first-order feedback system for phase unwrapping and smoothing. This system is a fast sequential unwrapping system which also allows filtering some noise because in deed it is an Infinite Impulse Response (IIR) low-pass filter. In other words, our system is capable of low-pass filtering the wrapped phase as the unwrapping process proceeds. We demonstrate the temporal stability of this unwrapping feedback system, as well as its low-pass filtering capabilities. Our system even outperforms the most common and used unwrapping methods that we tested, such as the Flynn's method, the Goldstain's method, and the Ghiglia least-squares method (weighted or unweighted). The comparisons with these methods shows that our system filters-out some noise while preserving the dynamic range of the phase-data. Its application areas may cover: optical metrology, synthetic aperture radar systems, magnetic resonance, and those imaging systems where information is obtained as a demodulated wrapped phase map.
Experiment-based identification of time delays in linear systems
NASA Astrophysics Data System (ADS)
Jin, Meng-Shi; Sun, Yi-Qiang; Song, Han-Wen; Xu, Jian
2017-03-01
This paper presents an identification approach to time delays in single-degree-of-freedom (SDOF) and multiple-degree-of-freedom (MDOF) systems. In an SDOF system, the impedance function of the delayed system is expressed by the system parameters, the feedback gain, and the time delay. The time delay can be treated as the "frequency" of the difference between the impedance function of the delayed system and that of the corresponding uncontrolled system. Thus, it can be identified from the Fourier transform of the difference between the two impedance functions. In an MDOF system, the pseudo-impedance functions are defined. The relationships between the time delay and the pseudo-impedance functions of the delayed system and uncontrolled system are deduced. Similarly, the time delay can be identified from the Fourier transform of the difference between the two pseudo-impedance functions. The results of numerical examples and experimental tests show that the identification approach to keeps a relatively high accuracy.
Spline collocation method for linear singular hyperbolic systems
NASA Astrophysics Data System (ADS)
Gaidomak, S. V.
2008-07-01
Some classes of singular systems of partial differential equations with variable matrix coefficients and internal hyperbolic structure are considered. The spline collocation method is used to numerically solve such systems. Sufficient conditions for the convergence of the numerical procedure are obtained. Numerical results are presented.
Response of linear dynamic systems with random coefficients
NASA Technical Reports Server (NTRS)
Dickerson, J.
1976-01-01
Numerous models of physical systems contain parameters whose values are not known exactly. The physical and mathematical complexities arising in the prediction of the statistical behavior of such systems are discussed. Although the discussions are far from providing a satisfactory solution to such problems, they perhaps, by utilization of simple examples, will create a greater awareness of the statistical effect of random parameters.
A Granular System of Ellipses under Linear Shear
NASA Astrophysics Data System (ADS)
Wang, Dong; Zheng, Hu; Behringer, Robert P.
2017-06-01
Shear of granular systems of disks (in 2D) and spheres (3D) has been studied extensively. However, less is known about systems of non-spherical particles, i.e., ellipses and polygons, etc. Here we studied a quasi 2D granular system composed of ellipses in a novel apparatus, which provided homogeneous simple shear by utilizing the weak friction between ellipses and the deformable base of the apparatus. Shear jamming, which was first reported for a disk system [1], was also observed for our ellipse system. We contrast shear jamming for systems of disks and systems of ellipses. By tracking the positions and orientations of the ellipses, we observed that the ellipses gradually rotated to align along a preferred direction as the shear strain increased. We also applied Voronoï tessellation to the packing of ellipses, showing that the distribution of the local density changed during shear. By contrast, such a change in the distribution was not observed in a disk system [2].
2014-01-01
Although bipolar disorder historically was thought to only occur rarely in children and adolescents, there has been a significant increase in children and adolescents who are receiving this diagnosis more recently (Carlson, 2005). Nonetheless, the applicability of the current bipolar disorder diagnostic criteria for children, particularly preschool children, remains unclear, even though much work has been focused on this area. As a result, more work needs to be done to further the understanding of bipolar symptoms in children. It is hoped that this paper can assist psychologists and other health service providers in gleaning a snapshot of the literature in this area so that they can gain an understanding of the diagnostic criteria and other behaviors that may be relevant and be informed about potential approaches for assessment and treatment with children who meet bipolar disorder criteria. First, the history of bipolar symptoms and current diagnostic criteria will be discussed. Next, assessment strategies that may prove helpful for identifying bipolar disorder will be discussed. Then, treatments that may have relevance to children and their families will be discussed. Finally, conclusions regarding work with children who may have a bipolar disorder diagnosis will be offered. PMID:24800202
[Prevention of bipolar disorders].
Leopold, K; Pfennig, A; Severus, E; Bauer, M
2013-11-01
In the past, preventive measures for psychoses have focused mainly on schizophrenic disorders. Bipolar disorders are often diagnosed and treated with a significant delay. The expansion of preventive measures for bipolar disorders aims at minimizing the substantial negative consequences associated with the disease. Some of the shared aspects of prevention in psychoses and bipolar disorders are that the first symptoms commonly appear during adolescence and early adulthood and that there is a symptomatic overlap between the disorders. To improve efforts to seek early help, public information about mental illness, low threshold services as well as cooperation between adult, child and adolescent psychiatry are needed for this target group. One differences is that psychotic symptoms play a minor role in bipolar disorders. Specific biological markers, such as disturbances of sleep and circadian rhythm and clinical characteristics, such as substance use and behavioral problems in childhood and youth supplement (subsyndromal) clinical symptoms in a multifactorial risk model. Besides severity and frequency of symptoms, specific periodic course patterns are crucial. Strategies of early intervention require a careful consideration of risks and benefits. Two aims should be distinguished: the improvement of current symptomatology and the prevention of conversion to bipolar disorder. Currently, studies evaluating risks and benefits of such interventions are first conducted. Expertise and resources for early recognition of psychoses and bipolar disorders should be pooled. Common standards are the basis for advancement and implementation of preventive strategies for bipolar disorders.
Vibration analysis of harmonically excited non-linear system using the method of multiple scales
NASA Astrophysics Data System (ADS)
Moon, Byung-Young; Kang, Beom-Soo
2003-05-01
An analytical method is presented for evaluation of the steady state periodic behavior of non-linear systems. This method is based on the substructure synthesis formulation and a multiple scales procedure, which is applied to the analysis of non-linear responses. A complex non-linear system is divided into substructures, of which equations are approximately transformed to modal co-ordinates including non-linear term under the reasonable procedure. Then, the equations are synthesized into the overall system and the solution of the non-linear system can be obtained. Based on the method of multiple scales, the proposed procedure reduces the size of large-degree-of-freedom problem in solving the non-linear equations. Feasibility and advantages of the proposed method are illustrated by the application of the analytic procedure to the non-linear rotating machine system as a large mechanical structure system. Results obtained are reported to be an efficient approach with respect to non-linear response prediction when compared with other conventional methods.
NASA Astrophysics Data System (ADS)
Royston, T. J.; Singh, R.
1996-07-01
While significant non-linear behavior has been observed in many vibration mounting applications, most design studies are typically based on the concept of linear system theory in terms of force or motion transmissibility. In this paper, an improved analytical strategy is presented for the design optimization of complex, active of passive, non-linear mounting systems. This strategy is built upon the computational Galerkin method of weighted residuals, and incorporates order reduction and numerical continuation in an iterative optimization scheme. The overall dynamic characteristics of the mounting system are considered and vibratory power transmission is minimized via adjustment of mount parameters by using both passive and active means. The method is first applied through a computational example case to the optimization of basic passive and active, non-linear isolation configurations. It is found that either active control or intentionally introduced non-linearity can improve the mount's performance; but a combination of both produces the greatest benefit. Next, a novel experimental, active, non-linear isolation system is studied. The effect of non-linearity on vibratory power transmission and active control are assessed via experimental measurements and the enhanced Galerkin method. Results show how harmonic excitation can result in multiharmonic vibratory power transmission. The proposed optimization strategy offers designers some flexibility in utilizing both passive and active means in combination with linear and non-linear components for improved vibration mounts.
Bipolar disorder and aggression.
Látalová, K
2009-06-01
In clinical practice, overt aggressive behaviour is frequently observed in patients diagnosed with bipolar disorder. It can be dangerous and complicates patient care. Nevertheless, it has not been adequately studied as a phenomenon that is separate from other symptoms such as agitation. The aim of this review is to provide information on the prevalence, clinical context, and clinical management of aggression in patients with bipolar disorder. MEDLINE and PsycInfo data bases were searched for articles published between 1966 and November 2008 using the combination of key words 'aggression' or 'violence' with 'bipolar disorder'. For the treatment searches, generic names of mood stabilisers and antipsychotics were used in combination with key words 'bipolar disorder' and 'aggression'. No language constraint was applied. Articles dealing with children and adolescents were not included. Acutely ill hospitalised bipolar patients have a higher risk for aggression than other inpatients. In a population survey, the prevalence of aggressive behaviour after age 15 years was 0.66% in persons without lifetime psychiatric disorder, but 25.34% in bipolar I disorder. Comorbidity with personality disorders and substance use disorders is frequent, and it elevates the risk of aggression in bipolar patients. Impulsive aggression appears to be the most frequent subtype observed in bipolar patients. Clinical management of aggression combines pharmacological and non-pharmacological approaches. A major problem with the evidence is that aggression is frequently reported only as one of the items contributing to the total score on a scale or a subscale. This makes it impossible to ascertain specifically aggressive behaviour. Large controlled head-to-head randomised controlled studies comparing treatments for aggressive behaviour in bipolar disorder are not yet available. There is some evidence favouring divalproex, but it is not particularly strong .We do not know if there are any efficacy
Model Checking Linear-Time Properties of Probabilistic Systems
NASA Astrophysics Data System (ADS)
Baier, Christel; Größer, Marcus; Ciesinski, Frank
This chapter is about the verification of Markov decision processes (MDPs) which incorporate one of the fundamental models for reasoning about probabilistic and nondeterministic phenomena in reactive systems. MDPs have their roots in the field of operations research and are nowadays used in a wide variety of areas including verification, robotics, planning, controlling, reinforcement learning, economics and semantics of randomized systems. Furthermore, MDPs served as the basis for the introduction of probabilistic automata which are related to weighted automata. We describe the use of MDPs as an operational model for randomized systems, e.g., systems that employ randomized algorithms, multi-agent systems or systems with unreliable components or surroundings. In this context we outline the theory of verifying ω-regular properties of such operational models. As an integral part of this theory we use ω-automata, i.e., finite-state automata over finite alphabets that accept languages of infinite words. Additionally, basic concepts of important reduction techniques are sketched, namely partial order reduction of MDPs and quotient system reduction of the numerical problem that arises in the verification of MDPs. Furthermore we present several undecidability and decidability results for the controller synthesis problem for partially observable MDPs.
Bipolar Disorder, Bipolar Depression and Comorbid Illness.
Manning, J Sloan
2015-06-01
There is a substantial need for the early recognition and treatment of the psychiatric and medical comorbidities of bipolar disorder in primary care. If comorbid conditions are recognized and treated, serious adverse health outcomes may be averted, including substantial morbidity and mortality.
Channel Capacity of Non-Linear Transmission Systems
NASA Astrophysics Data System (ADS)
Ellis, Andrew D.; Zhao, Jian
Since their introduction in the late 1970s, the capacity of optical communication links has grown exponentially, fuelled by a series of key innovations including movement between the three telecommunication windows of 850 nm, 1,310 nm and 1,550 nm, distributed feedback laser, erbium-doped fibre amplifiers (EDFAs), dispersion-shifted and dispersion-managed fibre links, external modulation, wavelength division multiplexing, optical switching, forward error correction (FEC), Raman amplification, and most recently, coherent detection, electronic signal processing and optical orthogonal frequency division multiplexing (OFDM). Throughout this evolution, one constant factor has been the use of single-mode optical fibre, whose fundamental principles dated back to the 1800s, when Irish scientist, John Tyndall demonstrated in a lecture to the Royal Society in London that light could be guided through a curved stream of water [1]. Following many developments, including the proposal for waveguides by J.J. Thompson [2], the presentation of detailed calculations for dielectric waveguides by Snitzer [3], the proposal [4] and fabrication [5] of ultra low loss fibres, single-mode fibres were first adopted for non-experimental use in Dorset, UK in 1975, and are still in use today, despite the evolving designs to control chromatic dispersion and non-linearity.
H ∞ output feedback stabilisation of linear discrete-time systems with impulses
NASA Astrophysics Data System (ADS)
Zhao, Shouwei; Sun, Jitao; Pan, Shengtao
2010-10-01
This article addresses the issue of designing an H ∞ output feedback controller for linear discrete-time systems with impulses. First, a new concept of H ∞ output feedback stabilisation for general linear discrete-time systems with impulses is introduced. Then sufficient linear matrix inequality conditions for the stabilisation and H ∞ performance of general discrete systems with impulses are proposed. In addition, the result is applied to resolve typical output feedback control problems for systems with impulses, such as the decentralised H ∞ output feedback control and the simultaneous H ∞ output feedback control. Finally, a numerical simulation is also presented to illustrate the effectiveness of the proposed results.
Fault Detection and Model Identification in Linear Dynamical Systems
2001-02-01
fault detection and isolation (FDI). One avenue of FDI is via the multi-model approach, in which the parameters of the nominal, unfailed model of the system are known, as well as the parameters of one or more fault models. The design goal is to obtain an indicator for when a fault has occurred, and, when more than one type is possible, which type of fault it is. A choice that must be made in tile system design is how to model noise. One way is as a bounded energy signal. This approach places very few restrictions on the types of noisy systems which
Gain scheduled control of linear systems with unsymmetrical saturation actuators
NASA Astrophysics Data System (ADS)
Wu, Wen-Juan; Duan, Guang-Ren
2016-11-01
The problem of stabilisation of a class of nonlinear continuous-time systems with asymmetric saturations on the control is studied in this paper. By combining the parametric Lyapunov equation approach and gain scheduling technique, a state feedback gain scheduling controller is proposed to solve the stabilisation problem of systems with unsymmetrical saturated control. The proposed gain scheduled approach is to increase the value of the design parameter so that the convergence rate of the closed-loop system can be increased. Numerical simulations show the effectiveness of the proposed approach.
Phase and amplitude control system for Stanford Linear Accelerator
Yoo, S.J.
1983-09-26
The computer controlled phase and amplitude detection system measures the instantaneous phase and amplitude of a 1 micro-second 2856 MHz rf pulse at a 180 Hz rate. This will be used for phase feedback control, and also for phase and amplitude jitter measurement. The program, which was originally written by John Fox and Keith Jobe, has been modified to improve the function of the system. The software algorithms used in the measurement are described, as is the performance of the prototype phase and amplitude detector system.
Tirelli, Giancarlo; Camilot, Debora; Bonini, Pierluigi; Del Piero, Giulia Carolina; Biasotto, Matteo; Quatela, Eliana
2015-11-01
Define and compare the thermal nerve injury caused by 3 different vessel sealing and dissection devices: the harmonic scalpel (HS), the electrothermal bipolar vessel sealing system (EBVS), and the bipolar electrosurgery unit (BE). First we recorded the heating variations in pig tissue caused by a BE unit, HS, and EBVS after an activation for 5, 10, and 15 seconds at minimum and at maximum power. In the second part, we evaluated the histological damage caused by HS and EBVS on 20 in vivo human nerves, 10 per device. The 2 scalpels were placed and activated at 3 different distances from the nerve (1, 3, and 5 mm). The extension and the degree of the nerve lesion was then calculated. The instrument determining the highest rise in temperature was the BE unit, followed by HS and then EBVS. Comparison between the extension and degree of nerve injury caused by the 2 scalpels showed no statistically significant differences. Based on these evaluations, we established a relative safety limit at 3 mm and an absolute safety limit at 5 mm for both scalpels. Our data suggest EBVS and HS can be considered valid and safe devices for ENT surgery. © The Author(s) 2015.
Discontinuous Galerkin Methods for NonLinear Differential Systems
NASA Technical Reports Server (NTRS)
Barth, Timothy; Mansour, Nagi (Technical Monitor)
2001-01-01
This talk considers simplified finite element discretization techniques for first-order systems of conservation laws equipped with a convex (entropy) extension. Using newly developed techniques in entropy symmetrization theory, simplified forms of the discontinuous Galerkin (DG) finite element method have been developed and analyzed. The use of symmetrization variables yields numerical schemes which inherit global entropy stability properties of the PDE (partial differential equation) system. Central to the development of the simplified DG methods is the Eigenvalue Scaling Theorem which characterizes right symmetrizers of an arbitrary first-order hyperbolic system in terms of scaled eigenvectors of the corresponding flux Jacobian matrices. A constructive proof is provided for the Eigenvalue Scaling Theorem with detailed consideration given to the Euler equations of gas dynamics and extended conservation law systems derivable as moments of the Boltzmann equation. Using results from kinetic Boltzmann moment closure theory, we then derive and prove energy stability for several approximate DG fluxes which have practical and theoretical merit.
Conditions of asymptotic stability for linear homogeneous switched systems
NASA Astrophysics Data System (ADS)
Ivanov, Gennady; Alferov, Gennady; Sharlay, Artem; Efimova, Polina
2017-07-01
In this article the authors prove the theorems giving the necessary and sufficient conditions for stability of robotic and mechatronic systems motion in terms of Lyapunov functions theory with the use of set-theoretic approach.
Using Parallel Banded Linear System Solvers in Generalized Eigenvalue Problems
1993-09-01
systems. The PPT algorithm is similar to an algorithm introduced by Lawrie and Sameh in [18]. The PDD algorithm is a variant of PPT which uses the fa-t...AND L. JOHNSSON, Solving banded systems on a parallel processor, Parallel Comput., 5 (1987), pp. 219-246. [10] J. J. DONGARRA AND A. SAMEH , On some...symmetric generalized matrix eigenvalur problem, SIAM J. Matrix Anal. Appl., 14 (1993). [18] D. H. LAWRIE AND A. H. SAMEH , The computation and
Improving the energy efficiency of sparse linear system solvers on multicore and manycore systems.
Anzt, H; Quintana-Ortí, E S
2014-06-28
While most recent breakthroughs in scientific research rely on complex simulations carried out in large-scale supercomputers, the power draft and energy spent for this purpose is increasingly becoming a limiting factor to this trend. In this paper, we provide an overview of the current status in energy-efficient scientific computing by reviewing different technologies used to monitor power draft as well as power- and energy-saving mechanisms available in commodity hardware. For the particular domain of sparse linear algebra, we analyse the energy efficiency of a broad collection of hardware architectures and investigate how algorithmic and implementation modifications can improve the energy performance of sparse linear system solvers, without negatively impacting their performance.
Non-Linear System Identification for Aeroelastic Systems with Application to Experimental Data
NASA Technical Reports Server (NTRS)
Kukreja, Sunil L.
2008-01-01
Representation and identification of a non-linear aeroelastic pitch-plunge system as a model of the NARMAX class is considered. A non-linear difference equation describing this aircraft model is derived theoretically and shown to be of the NARMAX form. Identification methods for NARMAX models are applied to aeroelastic dynamics and its properties demonstrated via continuous-time simulations of experimental conditions. Simulation results show that (i) the outputs of the NARMAX model match closely those generated using continuous-time methods and (ii) NARMAX identification methods applied to aeroelastic dynamics provide accurate discrete-time parameter estimates. Application of NARMAX identification to experimental pitch-plunge dynamics data gives a high percent fit for cross-validated data.
Benzi, Michele; Evans, Thomas M.; Hamilton, Steven P.; ...
2017-03-05
Here, we consider hybrid deterministic-stochastic iterative algorithms for the solution of large, sparse linear systems. Starting from a convergent splitting of the coefficient matrix, we analyze various types of Monte Carlo acceleration schemes applied to the original preconditioned Richardson (stationary) iteration. We expect that these methods will have considerable potential for resiliency to faults when implemented on massively parallel machines. We also establish sufficient conditions for the convergence of the hybrid schemes, and we investigate different types of preconditioners including sparse approximate inverses. Numerical experiments on linear systems arising from the discretization of partial differential equations are presented.
Space and frequency-multiplexed optical linear algebra processor - Fabrication and initial tests
NASA Technical Reports Server (NTRS)
Casasent, D.; Jackson, J.
1986-01-01
A new optical linear algebra processor architecture is described. Space and frequency-multiplexing are used to accommodate bipolar and complex-valued data. A fabricated laboratory version of this processor is described, the electronic support system used is discussed, and initial test data obtained on it are presented.
Optimized stiffness for linear time-invariant dynamic system according to a new system design
NASA Astrophysics Data System (ADS)
Veeraklaew, Tawiwat
2012-11-01
This paper deals with a linear time-invariant dynamic system such as spring-mass-damper system. General dynamic systems are quite commonly to be redesigned for another purpose of using. For example, if one automobile must be redesigned to have more weights, the existing suspension must be replaced due to that gained weight. Therefore the stiffness and damping coefficient must be recomputed in order to make the automobile become suitable for using as previous. Here the spring-mass-damper system is used as an example to demonstrate the technique through dynamic optimization where the problem is solved in two categories as minimum energy and maximum jerk. Once the state and control variables are provided from the problem of minimum energy and maximum jerk, respectively, these parameter will be substituted in dynamic equations and leave the stiffness and damping coefficient as the unknown parameters to be solved.
Linear system identification via backward-time observer models
NASA Technical Reports Server (NTRS)
Juang, Jer-Nan; Phan, Minh Q.
1992-01-01
Presented here is an algorithm to compute the Markov parameters of a backward-time observer for a backward-time model from experimental input and output data. The backward-time observer Markov parameters are decomposed to obtain the backward-time system Markov parameters (backward-time pulse response samples) for the backward-time system identification. The identified backward-time system Markov parameters are used in the Eigensystem Realization Algorithm to identify a backward-time state-space model, which can be easily converted to the usual forward-time representation. If one reverses time in the model to be identified, what were damped true system modes become modes with negative damping, growing as the reversed time increases. On the other hand, the noise modes in the identification still maintain the property that they are stable. The shift from positive damping to negative damping of the true system modes allows one to distinguish these modes from noise modes. Experimental results are given to illustrate when and to what extent this concept works.
Stochastic Stability of Sampled Data Systems with a Jump Linear Controller
NASA Technical Reports Server (NTRS)
Gonzalez, Oscar R.; Herencia-Zapana, Heber; Gray, W. Steven
2004-01-01
In this paper an equivalence between the stochastic stability of a sampled-data system and its associated discrete-time representation is established. The sampled-data system consists of a deterministic, linear, time-invariant, continuous-time plant and a stochastic, linear, time-invariant, discrete-time, jump linear controller. The jump linear controller models computer systems and communication networks that are subject to stochastic upsets or disruptions. This sampled-data model has been used in the analysis and design of fault-tolerant systems and computer-control systems with random communication delays without taking into account the inter-sample response. This paper shows that the known equivalence between the stability of a deterministic sampled-data system and the associated discrete-time representation holds even in a stochastic framework.
Krylov Subspace Methods for Complex Non-Hermitian Linear Systems. Thesis
NASA Technical Reports Server (NTRS)
Freund, Roland W.
1991-01-01
We consider Krylov subspace methods for the solution of large sparse linear systems Ax = b with complex non-Hermitian coefficient matrices. Such linear systems arise in important applications, such as inverse scattering, numerical solution of time-dependent Schrodinger equations, underwater acoustics, eddy current computations, numerical computations in quantum chromodynamics, and numerical conformal mapping. Typically, the resulting coefficient matrices A exhibit special structures, such as complex symmetry, or they are shifted Hermitian matrices. In this paper, we first describe a Krylov subspace approach with iterates defined by a quasi-minimal residual property, the QMR method, for solving general complex non-Hermitian linear systems. Then, we study special Krylov subspace methods designed for the two families of complex symmetric respectively shifted Hermitian linear systems. We also include some results concerning the obvious approach to general complex linear systems by solving equivalent real linear systems for the real and imaginary parts of x. Finally, numerical experiments for linear systems arising from the complex Helmholtz equation are reported.
System Combination with Log Linear Models (Author’s Manuscript)
2016-05-19
HMM) topology, and the frame level acoustic log-likelihoods from different systems are combined. As- sume there are K different systems to be...problem is to segment the continuous speech into segments, and then classify each (independent) segment in an acoustic code breaking fashion [9...ρi) ...∑|ρ| i=1 φK(O(i), ρi) φlm(W,ρ) ; η = η1 ... ηK ηlm (4) where φk(·) denotes the acoustic features for one segment from the kth
Cost decomposition of linear systems with application to model reduction
NASA Technical Reports Server (NTRS)
Skelton, R. E.
1980-01-01
A means is provided to assess the value or 'cst' of each component of a large scale system, when the total cost is a quadratic function. Such a 'cost decomposition' of the system has several important uses. When the components represent physical subsystems which can fail, the 'component cost' is useful in failure mode analysis. When the components represent mathematical equations which may be truncated, the 'component cost' becomes a criterion for model truncation. In this latter event component costs provide a mechanism by which the specific control objectives dictate which components should be retained in the model reduction process. This information can be valuable in model reduction and decentralized control problems.
Linear CCD attitude measurement system based on the identification of the auxiliary array CCD
NASA Astrophysics Data System (ADS)
Hu, Yinghui; Yuan, Feng; Li, Kai; Wang, Yan
2015-10-01
Object to the high precision flying target attitude measurement issues of a large space and large field of view, comparing existing measurement methods, the idea is proposed of using two array CCD to assist in identifying the three linear CCD with multi-cooperative target attitude measurement system, and to address the existing nonlinear system errors and calibration parameters and more problems with nine linear CCD spectroscopic test system of too complicated constraints among camera position caused by excessive. The mathematical model of binocular vision and three linear CCD test system are established, co-spot composition triangle utilize three red LED position light, three points' coordinates are given in advance by Cooperate Measuring Machine, the red LED in the composition of the three sides of a triangle adds three blue LED light points as an auxiliary, so that array CCD is easier to identify three red LED light points, and linear CCD camera is installed of a red filter to filter out the blue LED light points while reducing stray light. Using array CCD to measure the spot, identifying and calculating the spatial coordinates solutions of red LED light points, while utilizing linear CCD to measure three red LED spot for solving linear CCD test system, which can be drawn from 27 solution. Measured with array CCD coordinates auxiliary linear CCD has achieved spot identification, and has solved the difficult problems of multi-objective linear CCD identification. Unique combination of linear CCD imaging features, linear CCD special cylindrical lens system is developed using telecentric optical design, the energy center of the spot position in the depth range of convergence in the direction is perpendicular to the optical axis of the small changes ensuring highprecision image quality, and the entire test system improves spatial object attitude measurement speed and precision.
Solution of homogeneous systems of linear equations arising from compartmental models
Funderlic, R.E.; Mankin, J.B.
1980-12-01
Systems of linear differential equations with constant coefficients, Ax = x-dot, with the matrix A having nonnegative off-diagonal elements and zero column sums occur in compartmental analysis. The steady-state solution leads to the homogeneous system of linear equations Ax(infinity) = x-dot(infinity) = 0. LU factorization, the Crout algorithm, error analysis, and solution of a modified system are treated. 3 figures.
Consensus of Heterogeneous Linear Multiagent Systems With Communication Time-Delays.
Xu, Xiang; Liu, Lu; Feng, Gang
2017-05-23
This paper studies the consensus problem of heterogeneous linear multiagent systems with arbitrarily large constant, time-varying, or distributed communication delays. Novel distributed dynamic controllers are proposed for such multiagent systems with fixed and switching directed communication topologies, respectively. It is shown that the controlled heterogeneous linear multiagent system can reach consensus for arbitrarily large constant, time-varying, and distributed communication delays under some sufficient conditions. Simulation examples are provided to demonstrate the effectiveness of the proposed controllers.
Generation of multi-scroll attractors without equilibria via piecewise linear systems.
Escalante-González, R J; Campos-Cantón, E; Nicol, Matthew
2017-05-01
In this paper, we present a new class of dynamical system without equilibria which possesses a multiscroll attractor. It is a piecewise-linear system which is simple, stable, displays chaotic behavior and serves as a model for analogous non-linear systems. We test for chaos using the 0-1 Test for Chaos from Gottwald and Melbourne [SIAM J. Appl. Dyn. Syst. 8(1), 129-145 (2009)].
Parallel Direct Methods for Solving Banded Linear Systems.
1985-08-01
Dongarra and A. Sameh , On some parallel banded system solvers, Technical Report MCSD, No. 27, Argonne National Lab., 1984. [2] D. Gannon, J. van...Report , Computer Science Dept., Yale University, 1985. In preparation. [10] A.H. Sameh , Numerical Parallel Algorithms - A Survey., D. Lawrie, A. Sameh
Passive dynamic controllers for non-linear mechanical systems
NASA Technical Reports Server (NTRS)
Juang, Jer-Nan; Wu, Shih-Chin; Phan, Minh; Longman, Richard W.
1992-01-01
The objective is to develop active model-independent controllers for slewing and vibration control of nonlinear multibody flexible systems, including flexible robots. The topics are presented in viewgraph form and include: passive stabilization; work-energy rate principle; Liapunov theory; displacement feedback; dynamic controller; displacement and acceleration feedback; velocity feedback; displacement feedback; physical interaction; a 6-DOF robot; and simulation results.
Brunton, Steven L; Brunton, Bingni W; Proctor, Joshua L; Kutz, J Nathan
2016-01-01
In this wIn this work, we explore finite-dimensional linear representations of nonlinear dynamical systems by restricting the Koopman operator to an invariant subspace spanned by specially chosen observable functions. The Koopman operator is an infinite-dimensional linear operator that evolves functions of the state of a dynamical system. Dominant terms in the Koopman expansion are typically computed using dynamic mode decomposition (DMD). DMD uses linear measurements of the state variables, and it has recently been shown that this may be too restrictive for nonlinear systems. Choosing the right nonlinear observable functions to form an invariant subspace where it is possible to obtain linear reduced-order models, especially those that are useful for control, is an open challenge. Here, we investigate the choice of observable functions for Koopman analysis that enable the use of optimal linear control techniques on nonlinear problems. First, to include a cost on the state of the system, as in linear quadratic regulator (LQR) control, it is helpful to include these states in the observable subspace, as in DMD. However, we find that this is only possible when there is a single isolated fixed point, as systems with multiple fixed points or more complicated attractors are not globally topologically conjugate to a finite-dimensional linear system, and cannot be represented by a finite-dimensional linear Koopman subspace that includes the state. We then present a data-driven strategy to identify relevant observable functions for Koopman analysis by leveraging a new algorithm to determine relevant terms in a dynamical system by ℓ1-regularized regression of the data in a nonlinear function space; we also show how this algorithm is related to DMD. Finally, we demonstrate the usefulness of nonlinear observable subspaces in the design of Koopman operator optimal control laws for fully nonlinear systems using techniques from linear optimal control.ork, we explore finite
HOLMES, WILLIAM R.
2014-01-01
Reaction diffusion systems are often used to study pattern formation in biological systems. However, most methods for understanding their behavior are challenging and can rarely be applied to complex systems common in biological applications. I present a relatively simple and efficient, non-linear stability technique that greatly aids such analysis when rates of diffusion are substantially different. This technique reduces a system of reaction diffusion equations to a system of ordinary differential equations tracking the evolution of a large amplitude, spatially localized perturbation of a homogeneous steady state. Stability properties of this system, determined using standard bifurcation techniques and software, describe both linear and non-linear patterning regimes of the reaction diffusion system. I describe the class of systems this method can be applied to and demonstrate its application. Analysis of Schnakenberg and substrate inhibition models is performed to demonstrate the methods capabilities in simplified settings and show that even these simple models have non-linear patterning regimes not previously detected. The real power of this technique however is its simplicity and applicability to larger complex systems where other non-linear methods become intractable. This is demonstrated through analysis of a chemotaxis regulatory network comprised of interacting proteins and phospholipids. In each case, predictions of this method are verified against results of numerical simulation, linear stability, asymptotic, and / or full PDE bifurcation analyses. PMID:24158538
... sex. These problems can damage lives and hurt relationships. Some people with bipolar disorder have trouble keeping ... too much. Sometimes the stress can strain your relationships with other people. Caregivers can miss work or ...
Bipolar disorder is a mood disorder characterized by episodes of mania and major depression. Treatment with lithium or mood stabilizers may be effective, but medication regimens are sometimes difficult to tolerate ...
Escamilla, Michael A; Zavala, Juan M
2008-01-01
Bipolar disorder especially the most severe type (type I), has a strong genetic component. Family studies suggest that a small number of genes of modest effect are involved in this disorder. Family-based studies have identified a number of chromosomal regions linked to bipolar disorder, and progress is currently being made in identifying positional candidate genes within those regions. A number of candidate genes have also shown evidence of association with bipolar disorder, and genome-wide association studies are now under way, using dense genetic maps. Replication studies in larger or combined datasets are needed to definitively assign a role for specific genes in this disorder. This review covers our current knowledge of the genetics of bipolar disorder, and provides a commentary on current approaches used to identify the genes involved in this complex behavioral disorder.
Bipolar Disorder - Multiple Languages
... Supplements Videos & Tools You Are Here: Home → Multiple Languages → All Health Topics → Bipolar Disorder URL of this page: https://medlineplus.gov/languages/bipolardisorder.html Other topics A-Z Expand Section ...
Closed-loop structural stability for linear-quadratic optimal system
NASA Technical Reports Server (NTRS)
Wong, P. K.; Athans, M.
1976-01-01
This paper contains an explicit parameterization of a subclass of linear constant gain feedback maps that will not destabilize an originally open-loop stable system. These results can then be used to obtain several new structural stability results for multi-input linear-quadratic feedback optimal designs.
System and method for linearly amplifying optical analog signals by backward Raman scattering
Lin, Cheng-Heui
1988-07-05
A system for linearly amplifying an optical analog signal by backward stimulated Raman scattering comprises a laser source for generating a pump pulse; and an optic fiber having two opposed apertures, a first aperture for receiving the pump pulse and a second aperture for receiving the optical analog signal, wherein the optical analog signal is linearly amplified to an amplified optical analog signal.
Compensating inherent linear move water application errors using a variable rate irrigation system
USDA-ARS?s Scientific Manuscript database
Continuous move irrigation systems such as linear move and center pivot irrigate unevenly when applying conventional uniform water rates due to the towers/motors stop/advance pattern. The effect of the cart movement pattern on linear move water application is larger on the first two spans which intr...
System and method for linearly amplifying optical analog signals by backward Raman scattering
Lin, Cheng-Heui
1988-01-01
A system for linearly amplifying an optical analog signal by backward stimulated Raman scattering comprises a laser source for generating a pump pulse; and an optic fiber having two opposed apertures, a first aperture for receiving the pump pulse and a second aperture for receiving the optical analog signal, wherein the optical analog signal is linearly amplified to an amplified optical analog signal.
ERIC Educational Resources Information Center
Ramirez, Rene; Flores, Homero
This paper takes G.K. Chesterton's short story, "The Three Horsemen of Apocalypse," as a motivating introduction to the study of linear equations systems, as well as a review of the concept of linear function. The guide has three objectives: (1) to illustrate how to use non-mathematical sources to create math problems; (2) to use the graphing…
On the Resonance Concept in Systems of Linear and Nonlinear Ordinary Differential Equations
1965-11-01
Determinanten und Matrizen mit Anwen- dungen in Physik und Technik). Berlin: Akademie-Verlag 1949. The author wishes to express his thanks to Prof.Dr.R.Iglisch...Case in the System of Ordinary Linear Differential Equations, Part III ( Studium des Resonanzfalles bei Systemen linearer gew6hnlicher