bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of Trace Elements in Calcite Using Solution and Laser Ablation ICP‐MS: Calibration to NIST SRM Glass and USGS MACS Carbonate, and Application to Real Landfill Calcite
Authors: Strnad Ladislav , Ettler Vojtech , Mihaljevic Martin , Hladil Jindrich , Chrastny Vladislav
Published: July 2009

We report new data on the trace element concentrations of Mg, Cr, Mn, Co, Ni, Cu, Zn, Sr, Cd, Ba, La, Ce, Nd, Pb and U in USGS carbonate reference materials (MACS‐1 and MACS‐2) and compare solution ICP‐MS and LA‐ICP‐MS trace element determinations on landfill calcites using calibration to different reference materials (MACS‐1 and MACS‐2 carbonate and NIST SRM 612 glass). Very good agreement (differences below 10% relative) was found between laser ablation and solution ICP‐MS data for MACS‐1 with higher concentrations of trace elements (values between 100 and 150 μg g−1), with the exception of Cu and Zn. Similarly good agreement was found for MACS‐2 with lower trace element concentrations (units to tens of μg g−1), with the exception of Cr, Co and Zn. The MACS‐1 reference material for calibration of LA‐ICP‐MS was found to be extremely useful for in situ determination of trace elements in real‐world carbonate samples (landfill calcites), especially those present in calcite in higher concentrations (Mn, Sr, Ba; < 5% RSD). Less accurate determinations were generally obtained for trace elements present at low concentrations (∼ units of μg g−1). In addition, good agreement was observed between the instrument calibration to MACS and NIST SRM 612 glass for in situ measurements of trace elements in landfill calcites K‐2, K‐3 and K‐4 (differences below 15% relative for most elements). Thus, the application of MACS carbonate reference materials is promising and points to the need for the development of new carbonate reference materials for laser ablation ICP‐MS.
HEALING LOSS, AMBIGUITY, AND TRAUMA: A COMMUNITY‐BASED INTERVENTION WITH FAMILIES OF UNION WORKERS MISSING AFTER THE 9/11 ATTACK IN NEW YORK CITY
Authors: Boss Pauline , Beaulieu Lorraine , Wieling Elizabeth , Turner William , LaCruz Shulaika
Published: July 2009

A team of therapists from Minnesota and New York workied with labor union families of workers gone missing on September 11, 2001, after the attack on the World Trade Center, where they were employed. The clinical team shares what they did, what was learned, the questions raised, and preliminary evaulations about the multiple family meeting that were the major intervention. Because of the vast diversity, training of therapists and interventions for families aimed for cultural competence. The community‐based approach, preferred by union families, plus family therapy using the lens of ambiguous loss are proposed as necessary additions to disaster work.
THE IMPACT ON THE FAMILY THERAPIST OF A FOCUS ON DEATH, DYING, AND BEREAVEMENT
Authors: Becvar Dorothy S.
Published: July 2009

Recognizing the growing numbers of family therapists who are choosing a focus on death, dying and bereavement, this article addresses the nature of the commitment required—as well as the gifts and challenges presented by work in this area. Particular attention is given to therapists' vulnerability to compassion fatigue and/or vicarious traumatization, both of which are described and discussed. A variety of strategies for individuals and institutions, aimed at supporting professionals and preventing problems, are considered. It is concluded that as family therapists focus on self‐care as well as client care, they have the potential to increase not only their effectiveness but also to enhance their own well‐being. Implications for training and for research on this topic also are considered.

“For their is nothing heavier than compassion. Not even one's own pain weighs so heavy as the pain one feels with someone, for someone, a pain intensified by the imagination and prolonged by a hundred echoes.” (Kundera, 1999, p. 31)
CONDUCT DISORDER AND DELINQUENCY
Authors: Henggeler Scott W. , Sheidow Ashli J.
Published: July 2009

Overviews evidence‐based family treatments for adolescent conduct problems. Three treatments succeed in meeting recommendations for treatment development set forth in recent evaluations by reviewers and federal entities. These treatments (Functional Family Therapy, Multisystemic Therapy, and Oregon Treatment Foster Care) have achieved their success by using the science base of known risk factors, providing an effective alternative to restrictive placements, and using scientific methods to evaluate effectiveness. Major features of these three treatments are presented including clinical and quality assurance procedures, controlled outcome research support, cost analyses, and process research. Bases of treatment success and parallels among the three approaches are summarized, as is their transport and dissemination to pracice settings. Finally, suggestions for future research and clinical implications are discussed.
Business Investment under Uncertainty and Irreversibility1
Authors: Lombardi Domenico
Published: July 2009

This article surveys developments in the literature on business investment that have shed light on important aspects of firms' investment behaviour. Recent contributions emphasize the relevance of idiosyncratic factors affecting investment decisions such as the degree of irreversibility and uncertainty, whose interaction may generate an opportunity cost equivalent to the exercise of an option. They add an important dimension to the neoclassical theory of investment in so far as they emphasize cross‐sectional differences in optimal investment behavior. The econometric evidence is consistent with the predictions of these models pointing to a slower response of investment to demand shocks at higher levels of uncertainty.
Glucose represses PPARαgene expression via AMP‐activated protein kinase but not via p38 mitogen‐activated protein kinase in the pancreatic β‐cell
Authors: JOLY Erik , RODUIT Raphaël , PEYOT Marie‐Line , HABINOWSKI Susan Amy , RUDERMAN Neil Bertrand , WITTERS Lee Alan , PRENTKI Marc
Published: July 2009

Background:  Peroxisome proliferator‐activated receptor α (PPARα) regulates the expression of fatty acid metabolism genes and is thought to play a role in the regulation of insulin secretion and lipid detoxification. We have examined the mechanism whereby glucose decreases PPARα gene expression in the pancreatic β‐cell.

Methods:  INS832/13 β‐cell and isolated rat islets were incubated at 3 and 20 mM glucose for 18 h in the absence or presence of adenosine monophosphate (AMP)‐activated protein kinase (AMPK) activators and inhibitors, as well as p38 mitogen‐activated protein kinase (p38 MAPK) inhibitors. In another set of experiments, INS832/13 were infected with an adenovirus expressing a dominant‐negative form of AMPK. PPARα expression levels were measured by reverse transcription polymerase chain reaction and Western blot.

Results:  Elevated glucose reduced the abundance of the PPARα transcript and protein, and its target genes acyl‐coenzyme A (CoA) oxidase (ACO) and uncoupling protein 2 (UCP‐2) in INS832/13 β‐cell and isolated rat islets. Glucose reduced AMPK activity, while the AMPK activators 5‐amino‐4‐imidazolecarboxamide riboside and metformin increased PPARα expression and suppressed the action of glucose. By contrast, the AMPK inhibitor compound C mimicked the glucose effect. A dominant negative form of AMPKα reduced the PPARα, ACO and UCP‐2 transcripts to the same extent as elevated glucose. Pharmacological evidence indicated that glucose‐regulated PPARα expression does not involve p38 MAPK, a target of AMPK in several cell types.

Conclusions:  The results indicate that glucose represses PPARα gene expression via AMPK, but not via p38 MAPK in the β‐cell.
Genetics of human iris colour and patterns
Authors: Sturm Richard A. , Larsson Mats
Published: July 2009

The presence of melanin pigment within the iris is responsible for the visual impression of human eye colouration with complex patterns also evident in this tissue, including Fuchs’ crypts, nevi, Wolfflin nodules and contraction furrows. The genetic basis underlying the determination and inheritance of these traits has been the subject of debate and research from the very beginning of quantitative trait studies in humans. Although segregation of blue‐brown eye colour has been described using a simple Mendelian dominant‐recessive gene model this is too simplistic, and a new molecular genetic perspective is needed to fully understand the biological complexities of this process as a polygenic trait. Nevertheless, it has been estimated that 74% of the variance in human eye colour can be explained by one interval on chromosome 15 that contains the OCA2 gene. Fine mapping of this region has identified a single base change rs12913832 T/C within intron 86 of the upstream HERC2 locus that explains almost all of this association with blue‐brown eye colour. A model is presented whereby this SNP, serving as a target site for the SWI/SNF family member HLTF, acts as part of a highly evolutionary conserved regulatory element required for OCA2 gene activation through chromatin remodelling. Major candidate genes possibly effecting iris patterns are also discussed, including MITF and PAX6.
Temporal visual field defects are associated with monocular inattention in chiasmal pathology
Authors: Fledelius Hans C.
Published: July 2009

Purpose:  Chiasmal lesions have been shown to give rise occasionally to uni‐ocular temporal inattention, which cannot be compensated for by volitional eye movement. This article describes the assessments of 46 such patients with chiasmal pathology. It aims to determine the clinical spectrum of this disorder, including interference with reading.

Methods:  Retrospective consecutive observational clinical case study over a 7‐year period comprising 46 patients with chiasmal field loss of varying degrees. Observation of reading behaviour during monocular visual acuity testing ascertained from consecutive patients who appeared unable to read optotypes on the temporal side of the chart. Visual fields were evaluated by kinetic (Goldmann) and static (Octopus) techniques. Five patients who clearly manifested this condition are presented in more detail. The results of visual field testing were related to absence or presence of uni‐ocular visual inattentive behaviour for distance visual acuity testing and/or reading printed text.

Results:  Despite normal eye movements, the 46 patients making up the clinical series perceived only optotypes in the nasal part of the chart, in one eye or in both, when tested for each eye in turn. The temporal optotypes were ignored, and this behaviour persisted despite instruction to search for any additional letters temporal to those, which had been seen. This phenomenon of unilateral visual inattention held for both eyes in 18 and was unilateral in the remaining 28 patients. Partial or full reversibility after treatment was recorded in 21 of the 39 for whom reliable follow‐up data were available. Reading a text was affected in 24 individuals, and permanently so in six.

Conclusion:  A neglect‐like spatial unawareness and a lack of cognitive compensation for varying degrees of temporal visual field loss were present in all the patients observed. Not only is visual field loss a feature of chiasmal pathology, but the higher visual function of affording attention within the temporal visual field by means of using conscious thought to invoke appropriate compensatory eye movement was also absent. This suggests the possibility of ‘trans‐synaptic dysfunction’ caused by loss of visual input to higher visual centres. When inattention to the temporal side is manifest on monocular visual testing it should raise the suspicion of chiasmal pathology.
Ocular wavefront analysis and contrast sensitivity in eyes implanted with AcrySof IQ or AcrySof Natural intraocular lenses
Authors: Takmaz Tamer , Genç İpek , Yıldız Yelda , Can İzzet
Published: July 2009

Purpose:  This study aimed to compare ocular wavefront aberrations for pupil diameters of 4 mm and 6 mm, and contrast sensitivity, in eyes with AcrySof IQ and AcrySof Natural intraocular lenses (IOLs).

Methods:  Sixty eyes of 60 patients were enrolled in this prospective randomized study. After phacoemulsification the eyes received either AcrySof IQ SN60WF or AcrySof Natural SN60AT IOLs. One month after surgery, all patients underwent complete ophthalmological examination including corneal topography, wavefront analysis for pupil diameters of 4 mm and 6 mm, and contrast sensitivity measurements with the CSV 1000E instrument under photopic and mesopic conditions with and without glare.

Results:  There was no statistically significant difference between groups in age, sex or other preoperative ocular characteristics (p > 0.05). Patients with AcrySof IQ IOLs had higher contrast sensitivity at 6 c.p.d. under photopic conditions, at 6 c.p.d. and 18 c.p.d. under mesopic conditions, and at 6 c.p.d., 12 c.p.d. and 18 c.p.d. under mesopic conditions with glare (p < 0.05). Corneal spherical aberration was 0.273 ± 0.074 μm in the AcrySof Natural group and 0.294 ± 0.086 μm in the AcrySof IQ group (p = 0489). Ocular spherical aberration was 0.362 ± 0.141 μm and 0.069 ± 0.043 μm (p < 0.001) for 6‐mm diameter pupils and 0.143 ± 0.091 μm and 0.017 ± 0.016 μm (p < 0.001) for 4‐mm diameter pupils, with AcrySof Natural and AcrySof IQ IOLs, respectively. There were no significant differences in other higher‐order aberrations between the groups (p > 0.05).

Conclusions:  Aspherical AcrySof IQ IOLs significantly reduced spherical aberration for pupil diameters of both 4 mm and 6 mm and also improved contrast sensitivity more than spherical AcrySof Natural IOLs, especially in mesopic conditions.
Strabismus and employment: the opinion of headhunters
Authors: Mojon‐Azzi Stefania M. , Mojon Daniel S.
Published: July 2009

Purpose:  The aim of this study was to determine the influence of strabismus on an individual’s ability to find employment based on the opinion of Swiss headhunters.

Methods:  Forty Swiss headhunters retrieved from a Swiss online telephone directory were interviewed using a validated questionnaire in order to determine if strabismus would have an impact on a person's ability to find employment. Photographs of a strabismic man and woman as well as of other computer‐generated facial anomalies could be downloaded from the Internet during the interview.

Results:  72.5% of headhunters judged that strabismic individuals would have more difficulties in finding a job than orthotropic persons. These difficulties were judged to be stronger in women than in men (P = 0.006), and in exotropic compared to esotropic persons (P = 0.01). Asked about seven facial anomalies, exotropia was found to have the third and esotropia the fourth (women) or fifth (men) most strongly negative impact on finding employment, after having strong acne and a visible missing tooth. Headhunters judged that persons with strabismus are significantly perceived as less attractive and less intelligent by potential employers.

Conclusion:  Visible strabismus negatively influences individuals’ ability to find a job and therefore has an impact on their economic status. Successful strabismus surgery realigns the visual axes, producing a normal facial appearance and therefore eliminating the negative impact of strabismus on employability.
Ocular involvement in paediatric haemolytic uraemic syndrome
Authors: Sturm Veit , Menke Marcel N. , Landau Klara , Laube Guido F. , Neuhaus Thomas J.
Published: July 2009

Acta Ophthalmol. 2010: 88: 804–807

Purpose:  The aim of this study was to estimate the frequency and severity of ocular involvement in paediatric patients with haemolytic uraemic syndrome (HUS).

Methods:  The study was designed as an institutional, retrospective, observational case series. Charts for all 87 paediatric patients with HUS treated at the University Children’s Hospital Zurich between 1995 and 2007 were reviewed. Patients with ocular involvement were identified and clinical findings presented.

Results:  Three of 69 examined patients with HUS showed ocular involvement. Ophthalmic findings in two children were consistent with bilateral Purtscher retinopathy, showing multiple haemorrhages, exudations and superficial retinal whitening. The third child presented with bilateral isolated central intraretinal haemorrhages as a milder form of ocular involvement. In one of the children with Purtscher retinopathy, laser photocoagulation was required for bilateral rubeosis irides and development of disc neovascularization. Longterm outcomes in the two severely affected children showed decreased visual acuity caused by partial atrophy of the optic nerves. In the milder case visual acuity was not impaired at any time.

Conclusions:  A minority of paediatric patients with HUS developed ocular involvement. Acute ocular findings varied in severity from isolated intraretinal haemorrhages to Purtscher‐like retinopathy with retinal ischaemia. Longterm complications included the development of neovascularizations and consecutive optic nerve atrophy. Although ocular involvement in HUS seems to be rare, physicians should be aware of this complication because of its possible vision‐endangering consequences.
Phylogeny of Ptychostomum (Bryaceae, Musci) inferred from sequences of nuclear ribosomal DNA internal transcribed spacer (ITS) and chloroplast rps4
Authors: WANG Chen‐Ying , ZHAO Jian‐Cheng
Published: July 2009

Abstract  The phylogeny of Ptychostomum was first undertaken based on analysis of the internal transcribed spacer (ITS) region of the nuclear ribosomal (nr) DNA and by combining data from nrDNA ITS and chloroplast DNA rps4 sequences. Maximum parsimony, maximum likelihood, and Bayesian analyses all support the conclusion that the reinstated genus Ptychostomum is not monophyletic. Ptychostomum funkii (Schwägr.) J. R. Spence (≡Bryum funkii Schwägr.) is placed within a clade containing the type species of Bryum, B. argenteum Hedw. The remaining members of Ptychostomum investigated in the present study constitute another well‐supported clade. The results are congruent with previous molecular analyses. On the basis of phylogenetic evidence, we agree with transferring B. amblyodon Müll. Hal. (≡B. inclinatum (Brid.) Turton ≡Bryum archangelicum Bruch & Schimp.), Bryum lonchocaulon Müll. Hal., Bryum pallescens Schleich. ex Schwägr., and Bryum pallens Sw. to Ptychostomum.
Diversity of symbiotic algae of the genus Symbiodinium in scleractinian corals of the Xisha Islands in the South China Sea
Authors: DONG Zhi‐Jun , HUANG Hui , HUANG Liang‐Min , LI Yuan‐Chao
Published: July 2009

Abstract  Symbiotic algae (Symbiodinium sp.) in scleractinian corals are important in understanding how coral reefs will respond to global climate change. The present paper reports on the diversity of Symbiodinium sp. in 48 scleractinian coral species from 25 genera and 10 families sampled from the Xisha Islands in the South China Sea, which were identified with the use of restriction fragment length polymorphism (RFLP) of the nuclear ribosomal DNA large subunit gene (rDNA). The results showed that: (i) Symbiodinium Clade C was the dominant zooxanthellae in scleractinian corals in the Xisha Islands; (ii) Symbiodinium Clade D was found in the corals Montipora aequituberculata, Galaxea fascicularis, and Plerogyra sinuosa; and (iii) both Symbiodinium Clades C and D were found simultaneously in Montipora digitata, Psammocora contigua, and Galaxea fascicularis. A poor capacity for symbiosis polymorphism, as uncovered by RFLP, in the Xisha Islands indicates that the scleractinian corals have low adaptability to environmental changes. Further studies are needed to investigate zooxanthellae diversity using other molecular markers.
Energy Dissipation Through Modal Energy Redistribution
Authors: Issa Jimmy , Mukherjee Ranjan , Diaz Alejandro R.
Published: July 2009

A vibration suppression strategy based on passive damping is presented. Modal energy is shifted from low to high frequency modes where it will be rapidly dissipated. This is achieved through the repeated application and removal of constraints. Upon application of the constraint, part of the energy is transferred to the system modes in its new configuration while the remaining energy goes into the unmodeled, high frequency, flexible body modes where it is dissipated. When the constraint is removed, the remaining energy is transferred back to the modes of the unconstrained system. Removal of the constraint allows it to be applied again and the cycle to be repeated until the energy drains away completely. It is shown that the amount of energy lost during one cycle depends on the timing of the constraint application. Special cases where energy is conserved are considered. In one such case, energy is trapped in modes which are unaffected by the application of the constraint. These modes span an invariant subspace where energy remains trapped. Examples of linear systems are presented to illustrate this strategy.
Mobile Robots Characterized by Kinematic and Dynamic Equations: Motion Planning, Trajectory Tracking, and Group Control
Authors: Ailon Amit
Published: July 2009

The paper solves some control problems of mobile robots as both kinematics and dynamics are intertwined in the mathematical model. The problems of driving the vehicle to a desired configuration in a specified time and tracking a reference trajectory are considered. The control problems associated with motion in convoy and rigid formations of a group of vehicles are studied and some results are demonstrated by numerical examples.
A Two Zone Model of a Single Cylinder HCCI Engine for Control Applications
Authors: Tandra Varun , Srivastava Nilabh
Published: July 2009

This paper presents a first step towards developing a physics-based two-zone model of a single cylinder HCCI engine. Previously control laws were derived by using single zone mathematical models of HCCI combustion; although certain multi-zone models were reported, they were found too complex and unwieldy for the development of fast and efficient controllers for HCCI engines. The present work outlines the modeling approach of a single-cylinder two-zone HCCI engine by incorporating the first law of thermodynamics and temperature and concentration inhomogeneities within the cylinder in order to better predict peak pressures and combustion timings. The results showed good conformity when compared with the computationally intensive multi-zone models. A comparative analysis between the single zone and two-zone models, in the context of predicting cylinder pressures, temperatures, ignition timing is also discussed. Moreover, the effect of external parameters such as speed, and EGR were also evaluated.
Modeling Low Velocity Impacts in Mechanical Systems Involving Rigid and Flexible Bodies
Authors: Yigit Ahmet S. , Christoforou Andreas P.
Published: July 2009

This paper presents the preliminary results of an ongoing computational and experimental study of common impact situations in mechanical systems involving both rigid and flexible bodies. It is demonstrated that a characterization diagram that shows the relationship of three non-dimensional parameters with the normalized maximum impact force, can be used to fully describe the impact response. The governing non-dimensional parameters can be obtained a priori by analytical, experimental, or computational means. Impact situations having the same non-dimensional parameters, have dynamic similarity and have the same non-dimensional response. Furthermore, they can be placed in appropriate dynamic regions in which simplified dynamic models can be used to predict the response. Therefore, the characterization methodology has the potential to identify the most suitable model for a given impact situation.
Analysis the Effect of Undesirable Factors on Stability of Model Predictive Controller
Authors: Ansarpanahi Shadi , Mohd Noor Samsul Bahari
Published: July 2009

MPC also known as moving or receding horizon control, is a feedback control scheme that has originated in industry as a real-time computer control algorithm to solve linear and nonlinear multi-variable problems that have constraints and time delays. Since disturbances can drive model predictive control into non-convexity and instability this problem has attracted many researchers. The stability studies in this paper are illustrated in presence of colored noise, error in delay estimation, unstable and non-minimum phase system by means of numerical example. The simulation is carried out using an example, which is the main contribution of the paper.
Full State Feedback Control Design for “Delay Scheduling”
Authors: Cavdaroglu Mursel Emre , Olgac Nejat
Published: July 2009

A fixed full state feedback controller design approach is proposed for linear time invariant (LTI) systems with time delays. This approach enables the designer to use recently introduced “delay scheduling” procedure, which opens a new direction in control synthesis. “Delay scheduling” strategy suggests prolonging the existing (and unavoidable) delays in order to recover stability or to improve the control performance features. To be able to do this, however, system should have multiple stable operating zones in the domain of the delays. The main contribution of this paper is to develop a procedure for designing such a control law. It starts with a simple usage of LQR for non-delayed systems. This approach, nevertheless, imparts some complexities when delays are introduced. We handle them using a recent paradigm, called the Cluster Treatment of Characteristic Roots (CTCR). For an example to the ensuing design strategy, we use a fully actuated cart-pendulum system. Relevant simulations are carried out to show the viability of the proposed idea.
Modeling and Experimental Vibration Analysis of Nanomechanical Cantilever Active Probes With Application to Ultra Small Mass Detection
Authors: Salehi-Khojin Amin , Bashash Saeid , Jalili Nader
Published: July 2009

This paper presents a precise modeling framework for modal characterization and dynamic response analysis of nanomechanical cantilever Active Probes with geometrical discontinuities. An experimental setup consisting of a commercial NMC Active Probe from Veeco and a state-of-the-art microsystem analyzer, the MSA-400 from Polytec, for non-contact vibration measurement is developed to verify the theoretical derivations. Mode shapes and modal frequency response of system for the first three modes obtained from the proposed model are compared with those obtained from the experiment and commonly used theory for uniform beams. Results indicate that the uniform beam model fails to accurately predict the actual system response in multiple-mode operation, while the proposed discontinuous beam model demonstrates good agreement with the experimental data. The Active Probe is then utilized in an ultra small mass detection application. For this, a sensitivity analysis is carried out to measure the added mass at the most sensitive mode of operation. Results indicate detection of tip masses as small as a few hundreds of picograms.
Analysis and Optimization of a Series-Elastic Actuator for Jumping in Robots With Articulated Legs
Authors: Curran Simon , Orin David E. , Knox Brian T. , Schmiedeler James P.
Published: July 2009

This paper presents the analysis and optimization of a series-elastic actuator (SEA) for jumping with an articulated leg. Analytical and simulation results are validated with experimental results from a prototype leg. Similar to the series-elastic elements in muscles, an SEA decouples the dynamic limitations of a DC actuator from the joint, allowing larger liftoff velocities than with a directly driven joint. Detailed analysis of the complex dynamic SEA response during the thrust phase yields insights into its performance. The maximum impulse occurs when the motor speed is approximately half the no-load speed at the moment of peak motor torque. This proposed criterion is used to develop a simple analytical design equation for an optimal SEA.
Wave-Variable Based Force Feedback for a Space-Qualified Telerobot
Authors: Hart J. Scot , Shull Pete , Gentry Diana , Niemeyer Gu¨nter , Roderick Stephen , Akin David
Published: July 2009

Bilateral teleoperation across significant time delays has been extensively studied and is posed to provide remote control of orbiting robots. Unfortunately, most standard approaches assume an impedance controlled, backdrivable robot. In this work, we apply wave variable control to Ranger, a large, space-qualified, geared robot. We incorporate local feedback of contact forces into the control framework to achieve backdrivable operation. In particular, this control framework imitates an idealized point mass to respect Ranger’s dynamic capabilities. Beyond perceiving steady state contact forces, the user’s perception can be enhanced with high-frequency acceleration feedback of contact transients. Experimental results from controlling Ranger using network communications show stable operation in free space and contact.
Algebraic Criteria for Qualitative Analysis of Nonlinear Dynamics in Biochemistry
Authors: Kiriakidis Kiriakos , Nakos George
Published: July 2009

Aggregate modeling can approximate the convex hull of local matrices to nonlinear dynamics for any given accuracy. The authors use aggregate models to extend sufficient conditions for asymptotic stability of linear differential inclusions to nonlinear dynamics. An example illustrates the applicability of the proposed criteria to the analysis of nonlinear biochemical reaction chains.
Model-Based Control of Electroslag Remelting Process Using Unscented Kalman Filter
Authors: Ahn Seokyoung , Beaman Joseph J. , Williamson Rodney L. , Melgaard David K.
Published: July 2009

Electroslag Remelting (ESR) is used widely throughout the specialty metals industry. The process generally consists of a regularly shaped electrode that is immersed a small amount in liquid slag at a temperature higher than the melting temperature of the electrode. Melting droplets from the electrode fall through the lower density slag into a liquid pool constrained by a crucible and solidify into an ingot. High quality ingots require that electrode melt rate and immersion depth be controlled. This can be difficult when process conditions are such that the temperature distribution in the electrode is not at steady state. A new method of ESR control has been developed that incorporates an accurate, reduced-order melting model to continually estimate the temperature distribution in the electrode. The ESR process is highly nonlinear, noisy, and has coupled dynamics. An extended Kalman filter and an unscented Kalman filter were chosen as possible estimators and compared in the controller design. During the highly transient periods in melting, the unscented Kalman filter showed superior performance for estimating and controlling the system.
Blind Identification of 2-Channel IIR Wave Propagation Systems for Central Cardiovascular Monitoring
Authors: Hahn Jin-Oh , Reisner Andrew T. , Asada H. Harry
Published: July 2009

This paper presents a new approach to blind identification of a class of 2-channel infinite impulse response (IIR) systems describing the wave propagation dynamics. For these systems, this paper derives a blind identifiability condition and develops a blind identification algorithm, which is capable of uniquely determining both the numerator and denominator polynomials of the channel dynamics. The efficacy of the method is illustrated by a 2-sensor central cardiovascular monitoring application as an example, where the cardiovascular blood pressure wave propagation dynamics is identified and the aortic signals are reconstructed from blood pressure measurements at two distinct extremity locations. Experimental results using a swine subject illustrate how the new blind identification approach effectively identifies cardiovascular dynamics and reconstructs the aortic blood pressure and flow signals very accurately from two distinct peripheral blood pressure measurements under diverse physiologic conditions.
Portable Automated Driver for Road Vehicle Dynamics Testing
Authors: Mikesell David R. , Sidhu Anmol S. , Heydinger Gary J. , Bixel Ronald A. , Guenther Dennis A.
Published: July 2009

An automated test driver (ATD) has been developed which is capable of executing dynamic test maneuvers with accuracy and repeatability beyond the ability of a human driver. This system enables any production car or light truck to follow a user-defined path or to perform specific steering sequences with excellent repeatability. Combined with an automated brake and throttle controller, capable of matching a desired velocity profile as well as providing specific test inputs with acceleration or other feedback, this system provides a powerful tool to improve vehicle dynamics testing.
Design of an Overground Interactive Therapeutic Robot for Rodents Recovering After Spinal Cord Injury
Authors: Song Yun Seong , Hogan Neville
Published: July 2009

Growing interest in robotic treatment of patients with neurological injury motivates the development of therapeutic robots for basic research into recovery. Though humans are the ultimate beneficiaries, basic research frequently involves rodent models of neurological injury, which motivates robotic devices that can interact with rats or mice. This paper proposes an overground therapeutic robot suitable for rodent studies of recovery after for spinal cord injury. Advantages and challenges of an overground machine are compared with treadmill-type machines. Design and implementation issues, including its kinematic configuration, control scheme, biomechanical coupling and partial body weight support system, are presented and discussed. Current development progress is reported along with possible future applications of the device.
Real-Time Nonlinear Programming by Amplitude Modulation
Authors: Kong Kyoungchul , Inaba Kiyonori , Tomizuka Masayoshi
Published: July 2009

Nonlinear Programming (NLP) is for optimization of nonlinear cost functions. In applications of NLP for real-time optimization, however, the estimation of the gradient of the cost function remains as a challenge. On the other hand, the Extremum-Seeking Control (ESC) optimizes the cost function in real-time, but it involves a complicated design of filters in multi-dimensional cases. In this paper, a new method that optimizes an arbitrary multi-variable cost function in real-time is proposed. In the proposed method, the variables are updated as in NLP while the gradient of the cost function is continuously estimated by the amplitude modulation as in ESC. The proposed method does not require design of any complicated filters. The performance is verified by simulations on time-varying and noisy cost functions as well as automatic controller tuning applications.
A Motion Platform Integrated UAV Pilot Training and Evaluation System for Future Civilian Applications
Authors: Hing James T. , Oh Paul Y.
Published: July 2009

The potential for UAVs to benefit the civilian consumer is driving the demand for the integration of these vehicles into the national airspace. With UAV accidents occurring at a significantly higher rate than commercial airlines, the urgent issue becomes designing systems and protocols that can prevent UAV accidents, better train UAV operators and augment pilot performance. This paper presents three directions of research stemming from the goal of a UAV piloting and training system. Research direction one is the development of a research platform to assess UAV pilot skills and recreate the sensation of shared fate for UAV pilots. The second research direction looks at utilizing flight simulation packages to create virtual tools for training UAV pilots. The third direction covers the investigation of UAV’s in near earth environments as future applications will place UAVs in these areas.
Uniform Global Asymptotic Stability of Adaptively Controlled Nonlinear Systems via Strict Lyapunov Functions
Authors: Mazenc Fre´de´ric , de Queiroz Marcio , Malisoff Michael
Published: July 2009

We prove global uniform asymptotic stability of adaptively controlled dynamics by constructing explicit global strict Lyapunov functions. We assume a persistency of excitation condition that implies both asymptotic tracking and parameter identification. We also construct input-to-state stable Lyapunov functions under an added growth assumption on the regressor, assuming that the unknown parameter vector is subject to suitably bounded time-varying uncertainties. This quantifies the effects of uncertainties on the tracking and parameter estimation. We demonstrate our results using the Ro¨ssler system.
Direct Measurement of the Piston-Assembly Friction Force in a Single Cylinder Engine Under Motoring Conditions
Authors: Fadel C. , Chalhoub N. G. , Kfoury G. A. , Henein N. A.
Published: July 2009

Characterization of the lubrication regimes and quantification of the frictional losses are very important factors for the design of durable IC engines with improved fuel economy. Therefore, the current work has focused on the development of a tribology test rig that allows for the direct measurement of the instantaneous piston-assembly friction force under motoring conditions. The test rig was used to examine the effects of oil viscosity and engine speed on both the lubrication regimes and the friction force of the piston-assembly. Furthermore, the experimental data served to generate Stribeck curves for the coefficient of friction at different points in the cycle. Tear-down experiments were conducted to assess the friction contribution of each component in the piston-assembly. The results demonstrated that the magnitude of the friction force decreases with increasing oil grade under both boundary and mixed lubrication regimes. However, it tends to increase with increasing oil viscosity under a hydrodynamic lubrication regime. Moreover, the engine speed above which the hydrodynamic lubrication regime becomes prevalent at the midpoint of the stroke tends to decrease with increasing oil viscosity.
Adaptive Robust Control of a Linear Motor Driven Precision Industrial Gantry With Improved Cogging Force Compensation
Authors: Lu Lu , Yao Bin , Chen Zheng , Wang Qingfeng
Published: July 2009

This paper proposes a new model for cogging forces of linear motor systems. Sinusoidal functions of positions are used to capture the largely periodic nature of cogging forces with respect to position effectively while B-spline functions are employed to account for the additional aperiodic part of cogging forces. This model is experimentally demonstrated to be able to capture both the periodic and non-periodic characteristics of cogging force while having a linear parametrization form which makes effective on-line adaptive compensation of cogging forces possible. A discontinuous projection based desired compensation adaptive robust controller (DCARC) is then constructed for linear motors, which makes full use of the proposed cogging force model for an improved cogging force compensation. Comparative experimental results are obtained on both axes of a linear motor driven Anorad industrial gantry having a linear encoder resolution of 0.5 μm. Experiments are done with each axis running separately to compare the three algorithms: DCARC without cogging force compensation, DCARC with sinusoidal cogging force model compensation, and DCARC with the proposed cogging force model compensation. The results show that DCARC with proposed model compensation achieves the best tracking performance among the three algorithms tested, validating the proposed cogging force model. The excellent tracking performances obtained in experiments also verify the effectiveness of the proposed ARC control algorithms in practical applications.
Combining Inverse Dynamics With Traditional Mechanism Synthesis to Improve the Performance of High Speed Machinery
Authors: Rayner Robert , Sahinkaya M. Necip , Hicks Ben
Published: July 2009

This paper describes a unique, computer-based, mechanism design strategy that takes into account both kinematic and dynamic performance criteria at the synthesis stage of the design process. The strategy can be used to investigate improvements in the design of any existing mechanism with geometric redundancy in its output path. By iteratively varying the form of this redundant portion of the output path, alternative potentially better mechanism designs can be generated using a traditional mechanism synthesis and kinematic analysis method. The generated designs with the most desirable kinematic characteristics can be selected and analyzed using a multi-body, dynamic modeling and analysis tool. Using forward and inverse dynamic analysis the quality of the designs can be quantified. This paper describes work done to apply the strategy to an existing mechanism. An alternative mechanism design was identified with superior dynamic qualities. Kinematic performance was not sacrificed.
Force and Position Scaling Limits for Stability in Force Reflecting Teleoperation
Authors: Shull Pete , Niemeyer Gu¨nter
Published: July 2009

Many telerobotic systems require the use of a slave robot with large inertial and frictional properties. Using a force sensor on the end effector can hide the slave’s inertia and friction from the user providing a more accurate sense of the environment, but introduces dangers of system instability. Both the position and force scale directly affect the system loop gain and hence stability. This opens up the possibility of trading off between them based on the environment and task. In this paper we derive explicit limits for their product. In particular we consider varying environment stiffnesses, as well as distinguishing impact and contact phases. The theoretical limits closely align with experimental results using a large slave telerobotic system interacting with very soft to nearly rigid environments.
Motion Tracking Control Design for Wheeled Mobile Systems
Authors: Jarze˛bowska Elz˙bieta
Published: July 2009

The paper presents a model-based tracking control strategy design for wheeled mobile systems (WMS). The strategy enables tracking a variety of WMS motions that come from task specifications and control or design requirements put on them. From the point of view of mechanics and derivation of equations of motion, the WMS belongs to one class of first order nonholonomic systems. From the perspective of nonlinear control theory, the WMS differ and may not be approached by the same control strategies and algorithms, e.g. some of them may be controlled at the kinematic level and the other at the dynamic level only. The strategy we propose is based on a modeling control oriented framework. It serves a unification of the WMS modeling and a subsequent controller design with no regard whether a specific WMS is fully actuated, underactuated, or constrained by the task constraints.
Mobile Robot Path Planning Using Support Vector Machines
Authors: Sarkar Saurabh , Hall Ernest L. , Kumar Manish
Published: July 2009

This paper describes an approach that uses support vector machines (SVM) for path planning of mobile robots. The algorithm generates a collision free path for mobile robots running between two tracks or moving towards a known way point. This approach can negotiate tracks and avoid obstacles which may be initially unknown but are later perceived by the robot, and hence is suitable for use with onboard sensors which provides local information. The approach involves dividing the whole terrain into two different classes, classifying any new point obtained from sensors into either of the classes, and generating a track between both the classes as a path of the robot. SVM generates a non-linear class boundary on the principle of maximizing the margin. The boundary generated by this method is smooth, free of obstacles, and safe for a robot to navigate. The paper presents various case studies and simulation results. Future possibility to integrate this technique with other path planning techniques is also discussed.
Adaptive Stabilization of MEMS Relays
Authors: Bastani Y. , de Queiroz M. S.
Published: July 2009

An adaptive nonlinear stabilizer is introduced for uncertain, voltage-controlled, microelectromechanical system (MEMS) relays. The control construction follows a Lyapunov approach, and is based on a nonlinear dynamic model applicable to the two types of MEMS relays—electrostatic and electromagnetic. The adaptive stabilizer compensates for parametric uncertainty in all mechanical parameters and selected electrical parameters while ensuring asymptotic regulation of the electrode opening and closing. Simulations demonstrate the performance of the adaptive control scheme in comparison to the typical open-loop operation of the MEMS relay.
Design of Cellular Piezoelectric Actuators With High Blocking Force and High Strain
Authors: Neal Devin , Asada H. Harry
Published: July 2009

Preliminary design and analysis of a new concept for efficiently amplifying piezoelectric actuators are presented in this paper. Piezoelectric actuators, such as Lead Zirconate Titanate (PZT), have produced substantial stress at high bandwidth, but at very small strains on the order of 0.1%. This paper presents a new strain amplification design to be utilized as the first layer in the previously designed “nested rhombus” multi-layer mechanism. This mechanism produces substantial strain through exponentially increasing strain with each subsequent layer. However, the blocking force produced in previous designs is insufficient for many practical applications. Through static and kinematic analysis, this paper addresses how this new concept sufficiently amplifies strain, and presents numerous issues to consider in designing for greater blocking force. A prototype of this new concept provides 126 N of blocking force and displacement of 0.3 mm.
Parameter Estimation for Systems With Randomly Missing Output Under Network Environment
Authors: Shi Yang , Fang Huazhen
Published: July 2009

In this paper, we study how to identify the model parameters of a plant with randomly missing output in a network environment. As a result of networked-induced time delays and packet loss, the identification is inevitable to be affected by data missing. We propose to online estimate the missing output measurements, and employ the Kalman filter to estimate system parameters recursively. Convergence analysis on parameter estimation and output estimation is carried out. Simulation results verify the effectiveness of the proposed algorithm.
Parametric Design of Parallel Force/Velocity Actuators: Force Balance Analysis
Authors: Rabindran Dinesh , Tesar Delbert
Published: July 2009

This paper adds to the analytical work done in a companion paper [3]. In that work, the power analysis for a Parallel Force/Velocity Actuator was carried out. In this work, we present a force balance analysis of the same actuator. In so doing, we consider a link driven by a Parallel Force/Velocity Actuator and study the balance of static and inertial forces in this system. The results from this study include design maps for the PFVA including the effects listed above. We also present five specific design examples of the PFVA using commercial off-the-shelf components to illustrate our force balance analysis.
LMST-Based Safety-Preserved Consensus Control of Multi-Robot Systems With Kinodynamic Constraints
Authors: Yi Jingang , Wang Hongpeng , Liu Jingtai , Song Dezhen
Published: July 2009

We report a local minimum spanning tree (LMST)-based consensus control of multi-robot systems. Instead of using a potential function-based approach, we propose a safety region concept for distributed collision-free control system design. The safety region design also takes a consideration of the kinematics and dynamics constraints, namely, kinodynamic constraints of each robot. The network topology control among multiple robots is constructed by an LMST algorithm. The LMST-based topology control not only preserves the connectivity of multi-robot systems but also improves the energy consumption and network communication quality. Simulation results are presented to validate the proposed control system design.