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Control System (control + system)
Kinds of Control System Terms modified by Control System Selected AbstractsNETWORK-INDUCED DELAY-DEPENDENT H, CONTROLLER DESIGN FOR A CLASS OF NETWORKED CONTROL SYSTEMSASIAN JOURNAL OF CONTROL, Issue 2 2006Xiefu Jiang ABSTRACT This paper is concerned with the problem of robust H, controller design for a class of uncertain networked control systems (NCSs). The network-induced delay is of an interval-like time-varying type integer, which means that both lower and upper bounds for such a kind of delay are available. The parameter uncertainties are assumed to be normbounded and possibly time-varying. Based on Lyapunov-Krasovskii functional approach, a robust H, controller for uncertain NCSs is designed by using a sum inequality which is first introduced and plays an important role in deriving the controller. A delay-dependent condition for the existence of a state feedback controller, which ensures internal asymptotic stability and a prescribed H, performance level of the closed-loop system for all admissible uncertainties, is proposed in terms of a nonlinear matrix inequality which can be solved by a linearization algorithm, and no parameters need to be adjusted. A numerical example about a balancing problem of an inverted pendulum on a cart is given to show the effectiveness of the proposed design method. [source] OPEN-LOOP AND CLOSED-LOOP OPTIMIZATION OF LINEAR CONTROL SYSTEMSASIAN JOURNAL OF CONTROL, Issue 3 2000R. Gabasov ABSTRACT A canonical optimal control problem for linear systems with time-varying coefficients is considered in the class of discrete controls. On the basis of linear programming methods, two primal and two dual methods of constructing optimal open-loop controls are proposed. A method of synthesis of optimal feedback control is described. Results are illustrated by a fourth-order problem; estimates of efficiency of proposed methods are given. [source] An Optimal Grey PID Control SystemIEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 4 2009Guo-Dong Li Non-member Abstract The PID control algorithm has been widely applied in many industry control system to solve efficiently the control problems of manufacturing processes. However, PID control algorithm belong to "delay control", because it functions on basis of the actions occurred in the system. Thus the control accuracy in real-time is limited. In this paper, in order to realize the accurate control in real-time, the grey model based on grey system theory is first proposed to combine with PID control to establish the control system. We define the proposed control system as grey PID control system. Then the cubic spline function is integrated into the grey model. to enhance the control accuracy of system. To further improve the performance, the particle swarm optimization (PSO) algorithm is employed to optimize the parameters of PID algorithm. Finally, we validated the effectiveness of the proposed control system by computer simulation. © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] Neurostimulation systems for deep brain stimulation: In vitro evaluation of magnetic resonance imaging,related heating at 1.5 teslaJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 3 2002Ali R. Rezai MD Abstract Purpose To assess magnetic resonance imaging (MRI)-related heating for a neurostimulation system (Activa® Tremor Control System, Medtronic, Minneapolis, MN) used for chronic deep brain stimulation (DBS). Materials and Methods Different configurations were evaluated for bilateral neurostimulators (Soletra® Model 7426), extensions, and leads to assess worst-case and clinically relevant positioning scenarios. In vitro testing was performed using a 1.5-T/64-MHz MR system and a gel-filled phantom designed to approximate the head and upper torso of a human subject. MRI was conducted using the transmit/receive body and transmit/receive head radio frequency (RF) coils. Various levels of RF energy were applied with the transmit/receive body (whole-body averaged specific absorption rate (SAR); range, 0.98,3.90 W/kg) and transmit/receive head (whole-body averaged SAR; range, 0.07,0.24 W/kg) coils. A fluoroptic thermometry system was used to record temperatures at multiple locations before (1 minute) and during (15 minutes) MRI. Results Using the body RF coil, the highest temperature changes ranged from 2.5°,25.3° C. Using the head RF coil, the highest temperature changes ranged from 2.3°,7.1° C.Thus, these findings indicated that substantial heating occurs under certain conditions, while others produce relatively minor, physiologically inconsequential temperature increases. Conclusion The temperature increases were dependent on the type of RF coil, level of SAR used, and how the lead wires were positioned. Notably, the use of clinically relevant positioning techniques for the neurostimulation system and low SARs commonly used for imaging the brain generated little heating. Based on this information, MR safety guidelines are provided. These observations are restricted to the tested neurostimulation system. J. Magn. Reson. Imaging 2002;15:241,250. © 2002 Wiley-Liss, Inc. [source] IR-SE and IR-MEMRI allow in vivo visualization of oscine neuroarchitecture including the main forebrain regions of the song control systemNMR IN BIOMEDICINE, Issue 1 2006Ilse Tindemans Abstract Songbirds share with humans the capacity to produce learned vocalizations (song). Recently, two major regions within the songbird's neural substrate for song learning and production; nucleus robustus arcopallii (RA) and area X (X) are visualized in vivo using Manganese Enhanced MRI (MEMRI). The aim of this study is to extend this to all main interconnected forebrain Song Control Nuclei. The ipsilateral feedback circuits allow Mn2+ to reach all main Song Control Nuclei after stereotaxic injection of very small doses of MnCl2 (10,nl of 10,mM) into HVC of one and MAN (nucleus magnocellularis nidopallii anterioris) of the other hemisphere. Application of a high resolution (80,µ) Spin Echo Inversion Recovery sequence instead of conventional T1-weighted Spin Echo images improves the image contrast dramatically such that some Song Control Nuclei, ventricles, several laminae, fibre tracts and other specific brain regions can be discerned. The combination of this contrast-rich IR-SE sequence with the transsynaptic transport property of Manganese (Inversion Recovery based MEMRI (IR-MEMRI)) enables the visualization of all main interconnected components of the Song Control System in telencephalon and thalamus. Copyright © 2006 John Wiley & Sons, Ltd. [source] Retrospective Review of Acute Acamprosate Exposures to a Poison Control SystemTHE AMERICAN JOURNAL ON ADDICTIONS, Issue 5 2010PharmD, Sean Patrick Nordt MD No abstract is available for this article. [source] Large-scale production of endotoxin-free plasmids for transient expression in mammalian cell cultureBIOTECHNOLOGY & BIOENGINEERING, Issue 3 2008Aleksei Rozkov Abstract Transient expression of recombinant proteins in mammalian cell culture in a 100-L scale requires a large quantity of plasmid that is very labour intensive to achieve with shake flask cultures and commercially available plasmid purification kits. In this paper we describe a process for plasmid production in 100-mg scale. The fermentation is carried out in a 4-L fed-batch culture with a minimal medium. The detection of the end of batch and triggering the exponential (0.1 h,1) feed profile was unattended and controlled by Multi-fermenter Control System. A restricted specific growth rate in fed-batch culture increased the specific plasmid yield compared to batch cultures with minimal and rich media. This together with high biomass concentration (68,107 g,L,1 wet weight) achieves high volumetric yields of plasmid (95,277 mg,L,1 depending on the construct). The purification process consisted of alkaline lysis, lysate clarification and ultrafiltration, two-phase extraction with Triton X-114 for endotoxin removal, anion-exchange chromatography as a polishing step, ultrafiltration and sterile filtration. Both fermentation and purification processes were used without optimisation for production of four plasmids yielding from 39 to 163 mg of plasmids with endotoxin content of 2.5 EU mg,1 or less. Biotechnol. Bioeng. 2008;99: 557,566. © 2007 Wiley Periodicals, Inc. [source] A Neuro-Fuzzy Logic for ATIS Stand-Alone Control Systems: Structure, Calibration, and AnalysesCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 3 2004Yaser E. Hawas The scheme logic attempts to optimize the network overall travel time by adjusting the path proportions while guessing the signal phase split decisions. An approximate simulation-based optimization algorithm is devised as an example of the logic operating this scheme. The logic is then replicated by a fuzzy-logic control system. Neural nets are utilized to develop the knowledge base of the fuzzy system and to calibrate the fuzzy set parameters. The neural nets utilize data replicates generated by the approximate simulation-based optimization algorithm. The calibration and effectiveness results of the fuzzy control system are presented. [source] Design of Robust Control Systems from Classical to Modern Practical Approaches, Krieger Publishing Co., Malabar, FL 32950, ISBN 1-57524-143-9, 2001.INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 10 2002Yossi Chait Dr. No abstract is available for this article. [source] The Underpinnings of ,Bureaucratic' Control Systems: HRM in European MultinationalsJOURNAL OF MANAGEMENT STUDIES, Issue 4 2000Anthony Ferner This paper explores the relationship between the operation of management control systems and the mobilization of power resources in multinational companies. It argues that formal ,bureaucratic' controls depend for their effective operation on informal systems and the power relations they embody. In particular, bureaucratic control systems rely inherently on the deployment of ,social' control mechanisms relating to the creation of common value systems, understandings, and expectations about the ,rules of the game' among corporate actors. The argument is illustrated by material from case studies of HRM in British and German multinationals. [source] P/Pd Types Of Override Control SystemsASIAN JOURNAL OF CONTROL, Issue 4 2002Yaw-Ying Tsai ABSTRACT The override control provides protective action against abnormal operation and/or incipient process failure. In terms of control theory, it is a logic-based switching system and, in terms of operation, it is usually activated between the soft constraint and the hard constraint. It is used in all process industries, and most PID control loops are patched with some type of override system. Despite widespread application, little research has been done to analyze override control systems. In this work, the properties of the override control are explored. The stability of the override control is also studied. Counter to intuition, many well-known override systems may exhibit instability and lead to oscillatory responses as the process approaches constraints. Approaches are proposed for the design of override control systems to ensure inherent safe operation. [source] LMI Approach to Guaranteed Cost Control for Networked Control SystemsASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3-4 2005Shanbin Li This paper addresses the time-varying but bounded delay issue of networked control systems (NCS) within the framework of a discrete-time linear state-delayed system with norm-bounded uncertainty. A delay-dependent sufficient condition for the existence of a guaranteed cost controller for NCS is presented by a new Lyapunov-Krasovskii functional. The condition is formulated as a set linear matrix inequalities (LMIs). The resulting controller can not only asymptotically stabilize the system but also guarantee an adequate level of performance. Theoretical analysis and simulation results show that the control strategy presented in this paper is effective and feasible. [source] Generational Characteristics and Their Impact on Preference for Management Control SystemsAUSTRALIAN ACCOUNTING REVIEW, Issue 3 2010Emma Petroulas Research indicates that different macro-socialisation results in systematic differences in generational characteristics, which may in turn result in different generational workplace preferences for management control systems (MCS). An exploratory study was undertaken of three generations (Baby Boomers, Generation X and Generation Y) and their MCS preferences in a large Australian professional services firm. The results found that each generation exhibited different characteristics and these differences are linked to specific generational MCS preferences for goal setting, performance evaluation, administrative controls and incentives. These findings have implications for MCS design that attracts, motivates and retains employees, improves organisational performance, and manages intergenerational conflict. [source] Management Control Systems in a Non-Enterprise Network: The Greenhouse Gas Protocol InitiativeAUSTRALIAN ACCOUNTING REVIEW, Issue 2 2009Heidi Sundin This article is based on the action research project of a multi-stakeholder collaboration formed to produce the Greenhouse Gas Protocol. This non-enterprise cross-sector collaboration had two sets of problems: the first being the ideological differences of the stakeholders, who had differing interests and agendas regarding the production of standards. The second set relates to the practical problems of enabling 300 people from different organisations and time zones, with different levels of resource access and no clear financial goal or endpoint, to work together. To overcome these issues three types of management control systems were developed: strong planning processes, administrative and governance structures, and socio-ideological controls. The result of the collaboration is a set of greenhouse gas accounting standards that have widespread acceptance internationally. This study contributes to both practice and research on management control systems (MCS) by outlining how alternative forms of MCS can be designed for non-enterprise cross-sector collaboration. [source] Multiple input,multiple output adaptive feedback control strategies for the active headrest system: design and real-time implementationINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 10 2003Marek Pawelczyk Abstract In this article, multiple input,multiple output adaptive feedback control techniques for acoustic noise control in a headrest system are developed. The main goal underlying their design is to provide acoustic comfort to the user, i.e. high noise attenuation level over possibly large areas at the ears. Classical Internal Model Control system does not yield acceptable performance. An approach based on estimates of the residual noise at the ears is then proposed. It is shown that increase in the number of secondary sources to operate for one channel improves the performance. The experiments of tonal noise control are performed on an originally set-up prototype of the active headrest system. The results obtained are illustrated in the promoted form of distribution of zones of quiet. Copyright © 2003 John Wiley & Sons, Ltd. [source] Minimal data rate stabilization of nonlinear systems over networks with large delaysINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 10 2010C. De Persis Abstract Control systems over networks with a finite data rate can be conveniently modeled as hybrid (impulsive) systems. For the class of nonlinear systems in feedfoward form, we design a hybrid controller, which guarantees stability, in spite of the measurement noise due to the quantization, and of an arbitrarily large delay, which affects the communication channel. The rate at which feedback packets are transmitted from the sensors to the actuators is shown to be arbitrarily close to the infimal one. Copyright © 2009 John Wiley & Sons, Ltd. [source] Hypervideo application on an experimental control system as an approach to educationCOMPUTER APPLICATIONS IN ENGINEERING EDUCATION, Issue 1 2008Debevc, Matja Abstract Hypervideo, as an interactive tool with links within video frames, is becoming widely used in multimedia presentations for e-learning applications. Its concept of rich multimedia presentation together with temporal based link objects, gives a chance for use in engineering education courses, where many practical work and experiments are needed. In the article we present a strategy for the development and navigation of hypervideo application, to be used in engineering education. Example of magnetic suspension system experiment was built as hypervideo application. The system usability was tested with two methods, software usability measurement inventory (SUMI) evaluation and general approach to usability engineering. Test results have shown that hypervideo increases the users' motivation to work and helps students recognize, organize and present specific information. By applying some of the proposed improvements in future development, hypervideo could be a significant tool in the future of engineering education. © 2008 Wiley Periodicals, Inc. Comput Appl Eng Educ 16: 31,44, 2008; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20116 [source] Mobile Construction Supply Chain Management Using PDA and Bar CodesCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 4 2005H. Ping Tserng However, extending the construction project control system to job sites is not considered efficient because using notebooks in a harsh environment like a construction site is not particularly a conventional practice. Meanwhile, paper-based documents of the site processes are ineffective and cannot get the quick response from the office and project control center. Integrating promising information technologies such as personal digital assistants (PDA), bar code scanning, and data entry mechanisms, can be extremely useful in improving the effectiveness and convenience of information flow in construction supply chain control systems. Bar code scanning is appropriate for several construction applications, providing cost savings through increased speed and accuracy of data entry. This article demonstrates the effectiveness of a bar-code-enabled PDA application, called the mobile construction supply chain management (M-ConSCM) System, that responds efficiently and enhances the information flow between offices and sites in a construction supply chain environment. The advantage of the M-ConSCM system lies not only in improving the efficiency of work for on-site engineers, but also providing the Kanban-like visual control system for project participants to control the whole project. Moreover, this article presents a generic system architecture and its implementation. [source] Hybrid Control of Smart Structures Using a Novel Wavelet-Based AlgorithmCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 1 2005Hongjin Kim A new hybrid control system is presented through judicious combination of a passive supplementary damping system with a semi-active TLCD system. The new model utilizes the advantages of both passive and semi-active control systems, thereby improving the overall performance, reliability, and operability of the control system during normal operations as well as a power or computer failure. The robust wavelet-hybrid feedback least mean square (LMS) control algorithm developed recently by the authors is used to find optimal values of the control parameters. The effectiveness and robustness of the proposed hybrid damper-TLCD system in reducing the vibrations under various seismic excitations are evaluated through numerical simulations performed for an eight-story frame using three different simulated earthquake ground accelerations. It is found that the new model is effective in significantly reducing the response of the structure under various seismic excitations. [source] A Neuro-Fuzzy Logic for ATIS Stand-Alone Control Systems: Structure, Calibration, and AnalysesCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 3 2004Yaser E. Hawas The scheme logic attempts to optimize the network overall travel time by adjusting the path proportions while guessing the signal phase split decisions. An approximate simulation-based optimization algorithm is devised as an example of the logic operating this scheme. The logic is then replicated by a fuzzy-logic control system. Neural nets are utilized to develop the knowledge base of the fuzzy system and to calibrate the fuzzy set parameters. The neural nets utilize data replicates generated by the approximate simulation-based optimization algorithm. The calibration and effectiveness results of the fuzzy control system are presented. [source] Orexins (hypocretins) actions on the GHRH/somatostatin-GH axisACTA PHYSIOLOGICA, Issue 3 2010M. López Abstract The secretion of growth hormone (GH) is regulated through a complex neuroendocrine control system that includes two major hypothalamic regulators, namely GH-releasing hormone (GHRH) and somatostatin (SST) that stimulate and inhibit, respectively, GH release. Classical experiments involving damage and electrical stimulation suggested that the lateral hypothalamic area (LHA) modulated the somatotropic axis, but the responsible molecular mechanisms were unclear. Evidence obtained during the last decade has demonstrated that orexins/hypocretins, a family of peptides expressed in the LHA controlling feeding and sleep, play an important regulatory role on GH, by inhibiting its secretion modulating GHRH and SST neurones. Considering that GH release is closely linked to the sleep,wake cycle and feeding state, understanding orexin/hypocretin physiology could open new therapeutic possibilities in the treatment of sleep, energy homeostasis and GH-related pathologies, such as GH deficiency. [source] Sarbanes Oxley Section 404 Costs of Compliance: a case studyCORPORATE GOVERNANCE, Issue 2 2007Lineke Sneller In 2002 US Congress approved the Sarbanes Oxley Act (SOX). Section 404 requires companies to assess their internal controls and acquire an attestation of this assessment from their external auditor. In this paper, we investigate the costs of compliance of this assessment and attestation. The European division of a US listed company is used as a case study. The divisional project approach is described, and costs of compliance for this division are presented in two categories: assessment costs, mainly hours spent by internal staff; and attestation costs, mainly audit fees. The case study shows that the internal hours spent on assessment are approximately 12 times higher than the initial estimate made by the SEC in 2002, and that the realised other expenses are approximately 1.4 times higher than this estimate. Furthermore, a year on year increase of 50 per cent of the company's audit fee in the first year of Section 404 compliance is found. Companies can reduce the costs of compliance by implementing programmed controls, using auditors from countries with lower rates, remediating material weaknesses only, focusing on the internal control system rather than on individual controls, and by encouraging the auditor to rely on the company's assessment. [source] Inhibition deficits of serious delinquent boys of low intelligenceCRIMINAL BEHAVIOUR AND MENTAL HEALTH, Issue 5 2007Roos Koolhof Introduction,Studies have shown that low intelligence (IQ) and delinquency are strongly associated. This study focuses on inhibitory deficits as the source for the association between low IQ and delinquency. Further, the authors explore whether serious delinquent boys with a low IQ are exposed to more risk factors than serious delinquent boys with an average to high IQ. They also examine the extent to which low IQ and higher IQ serious delinquents incurred contact with the juvenile court because of their delinquent behaviour. Methods,Cross-sectional and longitudinal data from the Pittsburgh Youth Study were used to constitute four groups of boys: low IQ serious delinquents (n = 39), higher IQ serious delinquents (n = 149), low IQ non-to-moderate delinquents (n = 21) and higher IQ non-to-moderate delinquents (n = 219). Results,Low IQ serious delinquents committed more delinquent acts than higher IQ serious offenders. Low IQ serious delinquent boys also exhibited the highest levels of cognitive and behavioural impulsivity. There were no differences between low IQ and higher IQ serious delinquents on measures of empathy and guilt feelings. Instead, elevations on these characteristics were associated with serious offenders as a whole. Compared with higher IQ serious delinquents, low IQ serious delinquents were exposed to more risk factors, such as low academic achievement, being old for grade, depressed mood and poor housing. Conclusions,Inhibition deficits appear important in the aetiology of delinquency, especially among low IQ boys. Serious delinquent boys are all impulsive, but the higher IQ serious delinquents seem to have a better cognitive control system. Interventions aimed at low IQ boys should focus on the remediation of behavioural impulsivity as well as cognitive impulsivity. Copyright © 2007 John Wiley & Sons, Ltd. [source] Blood volume, blood pressure and total body sodium: internal signalling and output controlACTA PHYSIOLOGICA, Issue 1 2009P. Bie Abstract Total body sodium and arterial blood pressure (ABP) are mutually dependent variables regulated by complex control systems. This review addresses the role of ABP in the normal control of sodium excretion (NaEx), and the physiological control of renin secretion. NaEx is a pivotal determinant of ABP, and under experimental conditions, ABP is a powerful, independent controller of NaEx. Blood volume is a function of dietary salt intake; however, ABP is not, at least not in steady states. A transient increase in ABP after a step-up in sodium intake could provide a causal relationship between ABP and the regulation of NaEx via a hypothetical integrative control system. However, recent data show that subtle sodium loading (simulating salty meals) causes robust natriuresis without changes in ABP. Changes in ABP are not necessary for natriuresis. Normal sodium excretion is not regulated by pressure. Plasma renin is log-linearly related to salt intake, and normally, decreases in renin secretion are a precondition of natriuresis after increases in total body sodium. Renin secretion is controlled by renal ABP, renal nerve activity and the tubular chloride concentrations at the macula densa (MD). Renal nerve activity is related to blood volume, also at constant ABP, and elevates renin secretion by means of ,1 -adrenoceptors. Recent results indicate that renal denervation reduces ABP and renin activity, and that sodium loading may decrease renin without changes in ABP, glomerular filtration rate or ,1 -mediated nerve activity. The latter indicates an essential role of the MD mechanism and/or a fourth mediator of the physiological control of renin secretion. [source] Conservation and expression of IQ-domain-containing calpacitin gene products (neuromodulin/GAP-43, neurogranin/RC3) in the adult and developing oscine song control systemDEVELOPMENTAL NEUROBIOLOGY, Issue 2-3 2009David F. Clayton Abstract Songbirds are appreciated for the insights they provide into regulated neural plasticity. Here, we describe the comparative analysis and brain expression of two gene sequences encoding probable regulators of synaptic plasticity in songbirds: neuromodulin (GAP-43) and neurogranin (RC3). Both are members of the calpacitin family and share a distinctive conserved core domain that mediates interactions between calcium, calmodulin, and protein kinase C signaling pathways. Comparative sequence analysis is consistent with known phylogenetic relationships, with songbirds most closely related to chicken and progressively more distant from mammals and fish. The C-terminus of neurogranin is different in birds and mammals, and antibodies to the protein reveal high expression in adult zebra finches in cerebellar Purkinje cells, which has not been observed in other species. RNAs for both proteins are generally abundant in the telencephalon yet markedly reduced in certain nuclei of the song control system in adult canaries and zebra finches: neuromodulin RNA is very low in RA and HVC (relative to the surrounding pallial areas), whereas neurogranin RNA is conspicuously low in Area X (relative to surrounding striatum). In both cases, this selective downregulation develops in the zebra finch during the juvenile song learning period, 25,45 days after hatching. These results suggest molecular parallels to the robust stability of the adult avian song control circuit. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2009 [source] Seasonal changes in frequency tuning and temporal processing in single neurons in the frog auditory midbrainDEVELOPMENTAL NEUROBIOLOGY, Issue 1 2005Jozien BM Goense Abstract Frogs rely on acoustic signaling to detect, discriminate, and localize mates. In the temperate zone, reproduction occurs in the spring, when frogs emerge from hibernation and engage in acoustically guided behaviors. In response to the species mating call, males typically show evoked vocal responses or other territorial behaviors, and females show phonotactic responses. Because of their strong seasonal behavior, it is possible that the frog auditory system also displays seasonal variation, as evidenced in their vocal control system. This hypothesis was tested in male Northern leopard frogs by evaluating the response characteristics of single neurons in the torus semicircularis (TS; a homolog of the inferior colliculus) to a synthetic mating call at different times of the year. We found that TS neurons displayed a seasonal change in frequency tuning and temporal properties. Frequency tuning shifted from a predominance of TS units sensitive to intermediate frequencies (700,1200 Hz) in the winter, to low frequencies (100,600 Hz) in the summer. In winter and early spring, most TS neurons showed poor, or weak, time locking to the envelope of the amplitude-modulated synthetic call, whereas in late spring and early summer the majority of TS neurons showed robust time-locked responses. These seasonal differences indicate that neural coding by auditory midbrain neurons in the Northern leopard frog is subject to seasonal fluctuation. © 2005 Wiley Periodicals, Inc. J. Neurobiol, 2005 [source] Immediate early gene (ZENK, Arc) expression in the auditory forebrain of female canaries varies in response to male song qualityDEVELOPMENTAL NEUROBIOLOGY, Issue 3 2005Stefan Leitner Abstract In male songbirds, the song control pathway in the forebrain is responsible for song production and learning, and in females it is associated with the perception and discrimination of male song. However, experiments using the expression of immediate early genes (IEGs) reveal the activation of brain regions outside the song control system, in particular the caudomedial nidopallium (NCM) and the caudomedial mesopallium (CMM). In this study on female canaries, we investigate the role of these two regions in relation to playback of male songs of different quality. Male canaries produce elaborate songs and some contain syllables with a more complex structure (sexy syllables) that induce females to perform copulation solicitation displays (CSD) as an invitation to mate. Females were first exposed to playback of a range of songs of different quality, before they were finally tested with playback of songs containing either sexy or nonsexy syllables. We then sectioned the brains and used in situ hybridization to reveal brain regions that express the IEGs ZENK or Arc. In CMM, expression of ZENK mRNA was significantly higher in females that last heard sexy syllables compared to those that last heard nonsexy syllables, but this was not the case for NCM. Expression of Arc mRNA revealed no differences in either CMM or NCM in both experimental groups. These results provide evidence that in female canaries CMM is involved in female perception and discrimination of male song quality through a mechanism of memory reconsolidation. The results also have further implications for the evolution of complex songs by sexual selection and female choice. © 2005 Wiley Periodicals, Inc. J Neurobiol, 2005 [source] Syllable repertoire and the size of the song control system in captive canaries (Serinus canaria)DEVELOPMENTAL NEUROBIOLOGY, Issue 1 2004Stefan Leitner Abstract In songbirds, there is considerable interest in relationships between song structure and the size of the song control system in the forebrain. In male canaries, earlier studies have reported that repertoire size increased with age, and positive correlations were obtained between repertoire size and the volume of song control nuclei such as high vocal center (HVC). Here we investigate whether age has an effect upon both the song structure and the morphology of two song control nuclei [HVC and robustus archistriatalis (RA)] that are important in song production. We recorded songs from an aviary population of 1- and 2-year-old male domesticated canaries. We found that repertoire size, number of sexually attractive (sexy) syllables, and size of song nuclei did not differ between 1- and 2-year-old males. Neither did we find significant correlations between syllable repertoire size and the size of the song control nuclei. However, HVC size was positively correlated with the proportion of sexy syllables in the repertoires of 2-year-old males. Some older males may enhance vocal performance by modifying the control of syllables rather than by increasing repertoire size or neural space. © 2004 Wiley Periodicals, Inc. J Neurobiol 60: 21,27, 2004 [source] Experimental and analytical study on pounding reduction of base-isolated highway bridges using MR dampersEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 11 2009Anxin Guo Abstract Pounding between adjacent superstructures has been a major cause of highway bridge damage in the past several earthquakes. This paper presents an experimental and analytical study on pounding reduction of highway bridges subjected to earthquake ground motions by using magnetorheological (MR) dampers. An analytical model, which incorporates structural pounding and MR dampers, is developed. A series of shaking table tests on a 1:20 scaled base-isolated bridge model are performed to investigate the effects of pounding between adjacent superstructures on the dynamics of the structures. Based on the test results, the parameters of the linear and the nonlinear viscoelastic impact models are identified. Performance of the semiactive system for reducing structural pounding is also investigated experimentally, in which the MR dampers are used in conjunction with the proposed control strategy, to verify the effectiveness of the MR dampers. Structural responses are also simulated by using the established analytical model and compared with the shaking table test results. The results show that pounding between adjacent superstructures of the highway bridge significantly increases the structural acceleration responses. For the base-isolated bridge model considered here, the semiactive control system with MR dampers effectively precludes pounding. Copyright © 2009 John Wiley & Sons, Ltd. [source] Experimental verification of a wireless sensing and control system for structural control using MR dampersEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 10 2007Chin-Hsiung Loh Abstract The performance aspects of a wireless ,active' sensor, including the reliability of the wireless communication channel for real-time data delivery and its application to feedback structural control, are explored in this study. First, the control of magnetorheological (MR) dampers using wireless sensors is examined. Second, the application of the MR-damper to actively control a half-scale three-storey steel building excited at its base by shaking table is studied using a wireless control system assembled from wireless active sensors. With an MR damper installed on each floor (three dampers total), structural responses during seismic excitation are measured by the system's wireless active sensors and wirelessly communicated to each other; upon receipt of response data, the wireless sensor interfaced to each MR damper calculates a desired control action using an LQG controller implemented in the wireless sensor's computational core. In this system, the wireless active sensor is responsible for the reception of response data, determination of optimal control forces, and the issuing of command signals to the MR damper. Various control solutions are formulated in this study and embedded in the wireless control system including centralized and decentralized control algorithms. 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