bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Newton‐like approximation algorithm for the steady‐state solution of the riccati equation for time‐varying systems
Authors: Emre Erol , Knowles Gareth 
Published: July 2010

AbstractAn approximation technique is developed for the steady‐state solution of the time‐varying matrix Riccati equation. We show how the Newton‐type algorithm of Kleinman, developed for computing the steady solution to the algebraic Riccati equation for time‐invariant systems, can be extended for time‐varying linear systems. The time‐varying case is considerably more involved than the time‐invariant one. Consider a linear time‐varying system x(t) = F(t)x(t) + G(t)u(t). If (F, G) is uniformly completely controllable, we show how one can construct a recursive sequence of matrix functions (using linear techniques) which converge to the steady‐state solution of the associated time‐varying matrix Riccati equation (a non‐linear object). At each successive state, the next approximation is in terms of the steady‐state solution to a linear Lyapunov differential equation (which is the extension of the algebraic Lyapunov equations used by Kleinman) for which an explicit expression exists. This provides an approximation technique for obtaining infinite‐time, linear‐quadratic, optimal controllers and steady‐state Kalman—Bucy filters for time‐varying systems using purely linear techniques. Thus, we provide new types of suboptimal stabilizing feedback laws for linear time‐varying systems.
On the control of an uncertain water quality system
Authors: Chen Y. H. , Lee C. S. 
Published: July 2010

AbstractWe consider a one‐reach water quality system subject not only to bounded uncertain disturbances at the input and output levels but also to bounded uncertain variations of the rate coefficients. When the bounds of the time‐varying uncertainties are known, two classes of robust controllers, based on the measured state, are proposed to assure some desired performance, including uniform boundedness and uniform ultimate boundedness. If only output rather than full state is available for the control, a class of estimated state‐based control is proposed for the desired performance. When the bounds of the uncertainties are not known, we propose a class of controllers which, using the functional properties of the uncertainties, guarantees some desired system properties, one of which is the convergence to zero of all system responses.
Risk behaviour and optimum advertising with a stochastic dynamic sales response
Authors: Tapiero Charles S. , Eliashberg Jehoshua , Wind Yoram 
Published: July 2010

AbstractA stochastic (diffusion) sales response model to advertising is postulated. Optimum advertising policies are then found by solving a stochastic control problem with reflecting boundaries. Analytical results are obtained and interpreted to yield insights regarding a firm's risk behaviour and its optimal advertising policy.
Optimal control of current in a cathodic protection system: A numerical investigation
Authors: Zamani N. G. , Chuang J. M. 
Published: July 2010

AbstractIn this paper, the optimal control of current in an impressed cathodic protection system is considered. Such systems are routinely used for corrosion prevention. The analysis presented here enables the corrosion engineer to have a systematic way of determining the current output from a rectifier for complete protection. The boundary element method is employed for numerical calculations of the resulting coupled boundary value problems.
Generalized minimum variance control law revisited
Authors: Grimble M. J. 
Published: July 2010

AbstractThe generalized minimum variance control law is employed in many of the most successful self‐tuning control schemes. However, the control law was derived by using a single‐stage cost function where a conditional expectation operator was employed. This has limited our understanding of the operation of the control law and resulted in certain operational disadvantages. By rederiving the controller using a normal LQG approach but with a cost function of the same basic form, some of these deficiencies are mitigated. Moreover, the reason that the controller has poor stability characteristics on non‐minimum phase systems becomes apparent and it is shown that the magnitude of the error weighting term must be severely restricted in some problems if stability is to be maintained. Thus it may not be possible to limit error variance to the desired extent.
Design of decoupled optimal stochastic systems for low sensitivity to small time delays
Authors: Bamani Ali , Lee Gordon K. F. , Jin Lu 
Published: July 2010

AbstractIn this paper the problem of decoupling in the presence of time delays and external noise disturbances is addressed. By constructing a performance measure that incorporates trajectory sensitivity, a controller is formulated which decouples the overall system in spite of the time delay or noise sources. An example is provided to illustrate the approach and to demonstrate the effects of the choice of sensitivity weighting matrix on the state trajectory perturbation.
Linear quadratic self‐tuning control of a liquid‐liquid extraction column
Authors: Najim K. , Youlal H. , Irving E. , Najim M. 
Published: July 2010

AbstractAn application of a linear quadratic self‐tuning control approach to a pulsed liquid‐liquid extraction column is described. The control algorithm is derived from the minimization of a quadratic cost function. The resulting Riccati equation is iterated until the closed‐loop poles belong to a predefined stability domain included in the unit circle. Based upon the certainty equivalence principle, the adaptive control algorithm involves a parameter identification procedure and a feedback control law which uses the estimated parameters.Several experiments are carried out on a pulsed liquid‐liquid extraction column. Such extractors are being increasingly used in several industries because they are not energy‐consuming and they lead to high product purity. The column considered has the same dimensions as those currently used in fine chemical processes. The control objective is to optimize the column behaviour. The selected control variables are the pulse frequency and the conductivity measured at the bottom of the column. The experiments have been carried out with a mixture of water and toluene. The physical model developed for the column is too complex to use for control purposes. To represent the complex behaviour of the column, a single‐input/single‐output discrete‐time linear model was adopted. The parameters in the model are estimated on‐line with normalized data. The forgetting factor is also adjusted to maintain a constant trace of the estimator gain matix.The results obtained show the ability of this algorithm to improve the efficiency of the process considered. Finally, some details on practical implementation are provided.
On Verification of fuel‐optimal space trajectories
Authors: Vasudevan Gopal , Lutze F. H. 
Published: July 2010

AbstractCandidate fuel‐optimal trajectories for rendezvous in space are obtained with a parameter optimization method. These trajectories, which may include a minimum radius constraint, are verified against necessary conditions for optimality. Necessary conditions are presented in the form of requirements on a primer vector and in terms of requirements on the jumps in the costates when the constraint is encountered. In addition, criteria due to Lion and Handelsmann indicate how to improve candidate trajectories which prove non‐optimal so that they become locally optimal. Numerical results are presented which show that the candidate solutions must be obtained to a high level of accuracy before primer vector tests are valid.
Dynamic suboptimal control of a heat pump/heat storage system
Authors: Zaheeruddin M. , Gourishankar V. G. , Rink R. E. 
Published: July 2010

AbstractDynamic suboptimal control of a heat pump/heat storage system, recovering heat from a ground source and supplying it to a building via a storage tank, is investigated when the utilities offer time‐of‐day energy price incentives. On the basis of the analytical solution to the periodic optimization problem,1 suboptimal trajectories for the general time‐varying case are developed and a method for dealing with transition trajectories from one day to the next is given. The transition trajectories are very close to the numerically generated optimal trajectories and are simple enough to be implemented on microprocessors by use of standard PI controllers.
Optimal synchronization of n identical double‐integral plants with identical inputs but different initial conditions
Authors: Unbehauen H. , Vakilzadeh I. 
Published: July 2010

AbstractIn this paper automatic error elimination between outputs of n identical double‐integral plants (K/s2) with different output initial conditions will be studied with two distinct objectives: (1) making all the identical steady‐state outputs to be the double integral of any common input x(t); (2) having all the identical steady‐state outputs track perfectly a reference input r(t). Thus fulfilment of objective (1), which can be viewed as a synchronization problem, commands that the whole MIMO system work on a closed‐loop principle during the transient time in order to eliminate the errors between the n outputs; and on an open‐loop basis during the steady‐state phase in order to preserve the operation of the plant transfer functions (i.e. double integration) upon their inputs x(t). We shall see that objective (1) can always be attained if, once and for all, the plants are interconnected through identical PD‐controllers (1 + Ts), no matter what form the common inputs x(t) may have. This is a far cry from the orthodox feedback control systems in which the type of input always plays a decisive role in selecting the appropriate controller. Having arranged the system for achievement of objective (1), we will show, with a unique technique, that objective (2) can be achieved through use of only one replaceable controller H(s), which operates on the difference between the reference input r(t) and any one of the n outputs. That is, each time r(t) is changed with the possible necessary change of controller H(s), we can make any number of outputs follow the reference input. This second objective can be considered as both synchronization and tracking, which in the text we shall refer to as tracking. We shall also show, without any alteration in the arrangements of our MIMO system, that objective (1) can also be achieved for identical plants of transfer functions [K/s2(Tfs + 1)]. Through two examples, various observations discussed in the text will be demonstrated. Finally, armed with our previous results for simple‐integral plants (K/s) and the results obtained in this paper, we shall briefly discuss triple‐integral plants (K/s3) and q‐integral plants (K/s(q)).
Optimal control of temperature and fuel consumption for soaking pits in a steel plant—a distributed parameter approach
Authors: Yang D. R. , Wang F. Y. , Chang K. S. , Lee Won‐Kyoo 
Published: July 2010

AbstractAn optimal control theory for a class of non‐linear distributed parameter control systems in the general setting involving more than one spatial co‐ordinate is developed for use on control of a typical soaking pit in a steel industry. The system is described by a set of non‐linear partial differential equations in multidimensional spatial co‐ordinates and non‐linear boundary conditions with time‐dependent boundary controls as well as a spatially independent parameter vector which is governed by its own set of dynamic equations. The set of necessary conditions for optimality obtained from the theoretical development is directly applied to the optimal heating control of the soaking pit with rectangular ingots. The numerical solution by iterations demonstrates the success of the technique and the algorithm leading to the optimal policy for heating control of a typical soaking pit with minimum fuel consumption.
On Existence of a nash equilibrium point in N‐person non‐zero sum stochastic jump differential games
Authors: Wernerfelt Birger 
Published: July 2010

AbstractUsing the technique of Wan and Davis, we give an existence theorem for a Nash equilibrium point in N‐person non‐zero sum stochastic jump differential games. It is shown that if the Nash condition (generalized Isaacs condition) holds there is a Nash equilibrium point in feedback strategies. We extend the results to other solution concepts and discuss applications and extensions.
Levels of empathy in undergraduate occupational therapy students
Authors: Brown Ted , Williams Brett , Boyle Malcolm , Molloy Andrew , McKenna Lisa , Molloy Liz , Lewis Belinda 
Published: July 2010

AbstractEmpathy is an important attribute for occupational therapists in establishing rapport and in better understanding their clients. However, empathy can be compromised by high workloads, personal stressors and pressures to demonstrate efficacy. Occupational therapists also work with patients from a variety of diagnostic groups. The objective of this study was to determine the extent of empathy and attitudes towards clients amongst undergraduate occupational therapy students at one Australian University. A cross‐sectional study was undertaken using a written survey of the Jefferson Scale of Physician Empathy (JSPE) and the Medical Condition Regard Scale. Overall, a strong level of empathy was reported amongst students. Four medical conditions that occupational therapists work with (stroke, cerebral palsy, traumatic brain injury and depression) were held in high regard. Substance abuse, however, was held in comparatively low regard. Overall, the year of study appeared to have no significant impact on the students' empathy. Despite having a lower reported empathy level than found in health professions from other studies using the JSPE, occupational therapy students were found to have a good level of empathy. Of concern, however, was the bias reported against the medical condition of substance abuse, highlighting that the there may be a need to reinforce that patients from this diagnostic group are equally deserving of quality care irrespective of their clinical condition. Recommendations for future research include completing a longitudinal study of occupational therapy students' empathy levels and investigating the empathy levels of occupational therapists working with different client groups. Limitations of the study include the convenience sampling of occupational therapy students enrolled at one university which limits the generalizability of the results to groups of participants with similar characteristics. Copyright © 2010 John Wiley & Sons, Ltd.
Ausflug in die Vergangenheit: Chinin und andere Chinaalkaloide 3. Teil : Vom Weg zur Totalsynthese der Chinolin‐Chinaalkaloide über die Herstellung besser wirksamer Malariamittel bis zur Erforschung der Indol‐Chinaalkaloide
Authors: Eiden Fritz 
Published: July 2010

AbstractAnfang des 20. Jahrhunderts war die Konstitution der Chinolin‐Chinaalkaloide endgültig aufgeklärt worden (siehe 1. Teil). Im Laufe von Jahrzehnten hatten dann Vorstellungen von der räumlichen Struktur dieser Alkaloide Gestalt angenommen (siehe 2. Teil). Mit dem Entwicklungstempo der organischen Chemie wuchsen auch Wunsch und Möglichkeiten, Chinin durch Synthese zu gewinnen. Wieder war es vor allem Paul Rabe, der Pläne schmiedete und mit seinen Mitarbeitern erfolgversprechende Wege erkundete. 1931 hatte die Hamburger Arbeitsgruppe die schwierigste Etappe bewältigt: die erste Totalsynthese eines natürlichen Chinaalkaloids – des Dihydrochinins – war gelungen. Mit den dabei gewonnenen Erkenntnissen im Rucksack konnten dann gegen Ende des zweiten Weltkriegs Robert Burns Woodward und William v. E. Doering einen weiteren Gipfel besteigen.Nicht vergessen werden sollten auch die zahlreichen Versuche, mit Chinin als Molekülmodell besser wirkende und einfacher strukturierte Malariamittel zu entwickeln; die Erfolge waren aufsehenerregend – wenn auch oft wegen der Resistenzentwicklung von Krankheitserregern nicht von Dauer.Und schließlich gab es da noch die schon im 19. Jahrhundert aus Chinarinden isolierten Indol‐Chinaalkaloide, deren Konstitution, räumlicher Aufbau und synthetischer Zugang zu erforschen waren.
Adverse drug events in the outpatient setting: an 11‐year national analysis
Authors: Bourgeois Florence T. , Shannon Michael W. , Valim Clarissa , Mandl Kenneth D. 
Published: July 2010

AbstractPurposeAdverse drug events (ADEs) are a common complication of medical care resulting in high morbidity and medical expenditure. Population level estimates of outpatient ADEs are limited. Our objective was to provide national estimates and characterizations of outpatient ADEs and determine risk factors associated with these events.MethodsData are from the National Center for Health Statistics which collects information on patient visits to outpatient clinics and emergency departments throughout the United States. We examined visits between 1995 and 2005 and measured the national annual estimates of and risk factors for outpatient ADEs requiring medical treatment.ResultsThe national annual number of ADE‐related visits was 4 335 990 (95%CI: 4 326 872–4 345 108). Visits for ADEs to outpatient clinics increased over the study period from 9.0 to 17.0 per 1000 persons (p‐value for trend < 0.001). In multivariate analyses, factors associated with ADE visits included patient age (OR: 2.13; 95%CI: 1.63–2.79 for 65 years and older), number of medications taken by patient (OR: 1.88; 95%CI: 1.58–2.25 for five medications or more), and female gender (OR: 1.51; 95%CI: 1.34–1.71). Overall, outpatient ADEs resulted in 107 468 (95%CI: 89 011–125 925) hospital admissions annually, with older patients at highest risk for hospitalization (p‐value for trend < 0.001).ConclusionsBoth patient age and polypharmacy use are risk factors for ADE‐related healthcare visits, which have substantially increased in outpatient clinics between 1995 and 2005. The incidence of ADEs has particularly increased among patients 65 years and older with as many as 1 in 20 persons seeking medical care for an ADE. Copyright © 2010 John Wiley & Sons, Ltd.
Cardiovascular safety of ADHD medications: rationale for and design of an investigator‐initiated observational study
Authors: Hennessy Sean , Schelleman Hedi , Daniel Gregory W. , Bilker Warren B. , Kimmel Stephen E. , Guevara James , Cziraky Mark J. , Strom Brian L. 
Published: July 2010

AbstractPurposeTo describe the design and rationale of an investigator‐initiated observational study to examine the cardiovascular safety of the following commonly‐used medications to treat attention deficit hyperactivity disorder (ADHD): amphetamines, methylphenidate, and atomoxetine.MethodsWe are conducting an observational cohort study using data from five large Medicaid programs and the HealthCore Integrated Research Database (HIRDSM), which is derived from administrative data from commercial health plans. Our primary outcomes of interest are (1) sudden death/ventricular arrhythmia, (2) stroke, (3) myocardial infarction, and (4) stroke or myocardial infarction as a composite outcome. These claims diagnoses have been previously validated in adults, and the positive predictive value in children will be examined as part of this study. Secondary outcomes are (1) all‐cause death, (2) non‐suicide death, and (3) non‐accident death. All design decisions have been made to minimize bias toward the null. Based on our pilot data, we expect to have at least 90% power to detect a minimum detectable hazard ratio (HR) of 3.0 in children and adolescents who initiate an ADHD medication for each outcome of interest (except for MI, for which the expected minimum detectable HR is 7.9). The expected minimum detectable HR is 1.7 for each outcome for adult incident ADHD medication users.ResultsForthcoming.ConclusionsPotential limitations to this study include a low expected event rate in children and adolescents, potentially incomplete ascertainment of outcomes, and potential confounding by unmeasured variables. Nevertheless, this study will provide important information about the cardiovascular safety of ADHD medications. Copyright © 2010 John Wiley & Sons, Ltd.
Is suboptimal prescribing a risk factor for poor health outcomes in community‐dwelling elders? The ICARe Dicomano study
Authors: Pozzi C. , Lapi F. , Mazzaglia G. , Inzitari M. , Boncinelli M. , Geppetti P. , Mugelli A. , Marchionni N. , Di Bari M. 
Published: July 2010

AbstractPurposeMostly because of comorbidity and drugs consumption, older persons are often exposed to an increased risk of sub‐optimal prescribing (SP). At present, few studies investigated the association between SP and long‐term health outcomes. We examined the relation between SP and the risk of mortality and hospitalization in Italian older community‐dwellers.MethodsOlder (65+ years) community‐dwelling residents of a small town in Tuscany were enrolled in a longitudinal study. SP was defined as polypharmacy (use of 5+ drugs), prescription of inappropriate drugs (ID) according to Beers' criteria, and of potentially interacting drugs (PID), evaluated in 1995 and 1999. These three forms of SP were entered as time‐dependent exposures into multivariable Cox regression analysis models, whose outcomes were mortality and hospitalizations through 2003.ResultsOf 1022 participants (mean age 73.0 ± 6.8, 57% women), 220 were evaluated in 1995, 234 in 1999 and 568 in both waves. In univariate analysis, mortality was two‐fold higher in participants with polypharmacy (73.4/1000 person/years, 95% CI 58.2–92.4 vs. 34.1, 95% CI 29.7–39.2; p < 0.001) or PID (72.7/1000 person/years, 95% CI 46.3–113.9 vs. 38.0, 95% CI 33.5–43.1; p < 0.001), whereas it was unrelated to the presence of ID. Hospitalization rates were independent of any form of SP. In multivariable models, polypharmacy, ID, and PID were no longer associated with an increased risk of death, and ID predicted a slightly increased risk of hospitalizations (HR 1.03, 95% CI 1.0–1.06, p = 0.048).ConclusionsIn this cohort, SP was not associated with an excess risk of poor health outcomes. Copyright © 2010 John Wiley & Sons, Ltd.
p53 downregulates the gene expression of mitochondrial aconitase in human prostate carcinoma cells
Authors: Tsui Ke‐Hung , Feng Tsui‐Hsia , Lin Yu‐Fen , Chang Phei‐Lang , Juang Horng‐Heng 
Published: July 2010

AbstractBACKGROUNDMitochondrial aconitase (mACON) is regarded as the key enzyme in citrate oxidation in human prostate epithelial cells, and its abnormal expression has been implicated in tumorigenesis of the prostate. Evidence also supports a broad role for the p53 gene in suppressing prostatic tumorigenesis. We investigated whether p53 regulates mACON expression and explore the potential mechanisms responsible for its effect on prostate cancer cells.METHODSCamptothecin (CPT) treatments and transient overexpression of p53 were used to investigate p53 regulation of mACON and may effects were assessed using immunoblotting and transient gene expression assays.RESULTSIn vitro enzymatic activity assays and immunoblot assays showed that CPT treatment induced p53 expression while reducing mACON protein biosynthesis in wild‐type p53 expressing LNCaP cells. Immunoblot assays and reporter assays revealed that transient transfection of a p53 expression vector into p53‐null PC‐3 cells decreased mACON expression. Cyclic pifithrin‐α, an inhibitor of p53 transcriptional activity, blocked the decrease in mACON gene expression resulting from CPT treatment in LNCaP cells. Two putative p53 response elements were identified within the mACON promoter; however, mutation of these putative p53 response elements did not abolish the effect of CPT whereby it decreased mACON expression. A similar result was obtained for the effect of these mutants on the promoter activity of the mACON gene after transient overexpression of p53.CONCLUSIONSTogether these results suggest that p53 downregulation of mACON gene expression in human prostate carcinoma cells may not occur through the putative consensus p53 response elements found within the mACON promoter. Prostate 71: 62–70, 2011. © 2010 Wiley‐Liss, Inc.