bluuebunny/crossref_metadata_2025 huggingface dataset:
Predictors of dental care utilization among working poor Canadians
Authors: Muirhead V. E. , Quiñonez C. , Figueiredo R. , Locker D.
Published: April 2009

Abstract –  Objective:  This study used the Gelberg–Andersen Behavioral Model for Vulnerable Populations to identify predictors of dental care utilization by working poor Canadians.

Methods:  A cross‐sectional stratified sampling study design and telephone survey methodology was used to collect data from a nationally representative sample of 1049 working poor individuals aged 18 to 64 years. Working poor persons worked ≥20 h a week, were not full‐time students and had annual family incomes <$34 300. A pretested questionnaire included sociodemographic items, self‐reported oral health measures and two dental care utilization outcomes: time since their last dental visit and the usual reason for dental visits.

Results:  Hierarchical stepwise logistic analyses identified independent predictors associated with visiting the dentist >1 year ago: male gender (OR = 1.63; P = 0.005), aged 25–34 years (OR = 2.05; P = 0.02), paying for dental care with cash or credit (OR = 2.31; P < 0.001), past welfare recipients (OR = 1.65; P = 0.03), <21 teeth (OR = 4.23; P < 0.001) and having a perceived need for dental treatment (OR=2.78; P < 0.001). Sacrificing goods or services to pay for dental treatment was associated with visiting the dentist within the past year. The predictors of visiting the dentist only when in pain/trouble were lone parent status (OR = 4.04; P < 0.001), immigrant status (OR = 1.72; P = 0.006), paying for dental care with cash or credit (OR = 2.71; P < 0.001), a history of an inability to afford dental care (OR = 1.62; P = 0.01), a satisfactory/poor/very poor self‐rated oral health (OR = 2.10; P < 0.001), number of teeth <21 (OR = 2.58; P < 0.001) and having a perceived need for dental treatment (OR = 2.99; P < 0.001).

Conclusions:  This study identified predisposing and enabling vulnerabilities that jeopardize the dental care‐seeking practices of working poor persons. Dental care utilization was associated with relinquishing spending on other goods and services, which suggests that dental care utilization is a competing financial demand for economically constrained adults.
Relationship of quantitative salivary levels of Streptococcus mutans and S. sobrinus in mothers to caries status and colonization of mutans streptococci in plaque in their 2.5‐year‐old children
Authors: Kishi M. , Abe A. , Kishi K. , Ohara‐Nemoto Y. , Kimura S. , Yonemitsu M.
Published: April 2009

Abstract –  Objectives:  The aim of this study was to assess the relationships of quantitative salivary levels of Streptococcus mutans and S. sobrinus in mothers with the colonization of mutans streptococci (MS) in plaque and caries status in their 2.5‐year‐old children. Furthermore, the dynamics of caries status in the children was evaluated in a 2‐year follow‐up survey.

Methods:  After oral examination of 54 mother‐and‐child pairs, the saliva samples from the mothers and the plaque samples from the children were collected. The levels (log DNA copies/ml saliva) of S. mutans and S. sobrinus were quantified using real‐time polymerase chain reaction (PCR) assays, while MS in the plaque samples were detected using a cultivation method. In addition, 50 of the 54 children participated in a 2‐year follow‐up survey of caries prevalence.

Results:  In the 2.5‐year‐old children, the percentage of dft‐positive subjects and mean number of dft were significantly higher in the MS(+) group when compared with the MS(−) group. Findings from the 2‐year follow‐up survey indicated that MS(+) subjects had a persistently higher mean number of dft at 4.5 years. The 2.5‐year‐old children were divided into three groups based on the quantitative levels of salivary S. mutans and S. sobrinus in their mothers: those whose mothers had low levels of S. mutans (<4 log DNA copies/ml) and S. sobrinus (<2) (group 1); those whose mothers had a high level of S. mutans (≥4) and low level of S. sobrinus (<2) (group 2); and those whose mothers had high levels of both (≥4 and ≥2, respectively) (group 3). Among the three groups, the percentages of MS(+) and dft‐positive children were highest in group 3 and lowest in group 1. Furthermore, multiple logistic regression analyses revealed that grouping the mothers based on salivary level of S. mutans and S. sobrinus was an efficient means to predict both MS colonization (OR = 2.96) and prevalence of dental caries (OR = 9.39) in children at 2.5 years of age.

Conlusions:  In the 54 mother‐and‐child pairs tested, the maternal salivary levels of S. mutans and S. sobrinus determined by real‐time PCR were significantly related to MS colonization in plaque as well as dental caries in their children at 2.5 years of age. Thus, determination of maternal levels of both organisms using the present cut‐off values is proposed as an efficient method to indicate the risks of maternal transmission of MS and childhood dental caries.
Income and oral health relationship in Brazil: is there a threshold?
Authors: Celeste Roger Keller , Nadanovsky Paulo
Published: April 2009

Abstract – Objectives: We explored the relationship between income and two oral health outcomes in Brazil, in order to assess the shape of this relationship.

Methods: Individual‐level data from a national oral health survey were obtained for 22 634 15‐ to 19‐year‐old subjects from 330 municipalities. Relationships between income (equivalized household income) and oral health were smoothed using the locally weighted ordinary least squares regression (LOWESS) technique in order to assess the relationship between material circumstances and oral health. We also ranked individuals based on equivalized household income, supplemented by information from total household income, interviewees’ earnings, number of cars in the household and years of education, in order to assess the relationship between social position and oral health.

Results: The relationship between oral health and equivalized household income showed a threshold and, assuming causality, income levels higher than R$850 per month did not improve oral health further. The relationship between oral health and social position was linear. Correlations of oral health with the ranking variable (social position) were stronger than with equivalized household income, regardless of the income level, and did not decrease after controlling for income.

Conclusions: The relation of oral health in teenagers with equivalized household income (material circumstances) showed a threshold, but the relation with a ranking variable (social position) was linear. Maybe differences in oral health between individuals are influenced by both their material circumstances (up to a certain level of income) and their social position in relation to others, i.e. social status (at any income level).
Alcohol intake and oral cavity cancer risk among men in a prospective study in Kerala, India
Authors: Cancela Marianna de Camargo , Ramadas Kunnambath , Fayette Jean‐Marie , Thomas Gigi , Muwonge Richard , Chapuis François , Thara Somanathan , Sankaranarayanan Rengaswamy , Sauvaget Catherine
Published: April 2009

Abstract –  Objective:  The aim of the study was to evaluate the role of alcohol drinking and patterns of consumption in oral cancer incidence and mortality in a cohort study using data from the Trivandrum Oral Cancer Screening Study, India.

Methods:  At baseline, the study participants completed a lifestyle questionnaire including items on frequency and duration of alcohol consumption. They were followed up for oral cancer incidence and mortality. Data from 32 347 subjects, of whom 134 eventually developed oral cancer, were analysed to estimate risk of oral cancer incidence and mortality according to drinking patterns, using a Cox regression model adjusted for age, religion, education, occupation, body mass index (BMI), standard of living index, chewing habits, smoking habits, and vegetable and fruit intake.

Results:  Current and past drinkers were each associated with significantly increased risk of developing oral cancer. The hazard ratio increased significantly by 49% (95% CI = 1–121%) among current drinkers and 90% (95% CI = 13–218%) among past drinkers. A significant dose–response relationship between intake frequency, duration and oral cancer risk (incidence and mortality) was observed.

Conclusions:  As with other lifestyle factors, alcohol intake plays an important role in oral carcinogenesis in this population, and understanding this role is relevant to developing public health policies targeting at‐risk population.
Emergency department visits for dental care of nontraumatic origin
Authors: Quiñonez Carlos , Gibson Debbie , Jokovic Aleksandra , Locker David
Published: April 2009

Abstract –  Objectives:  To explore the nature of emergency department (ED) visits for dental problems of nontraumatic origin in Canada’s largest province, Ontario.

Methods:  The Canadian Institute for Health Information’s National Ambulatory Care Reporting System was used, which contains demographic, diagnostic, procedural and administrative information from hospital‐based ambulatory care settings across Ontario. Data of fiscal years 2003/04 to 2005/06 were included for emergency visits that had a main problem coded with an International Classification of Diseases – 10th edition code in the range K00–K14, representing diseases of the oral cavity, salivary glands and jaws. Volumes are presented by a number of different factors in order to describe patient and visit characteristics.

Results:  During this period, there were a total of 141 365 ED visits for dental problems of nontraumatic origin in Ontario, representing an estimated 116 357 persons. Approximately half of all visits (54%) were made by those 20 to 44 years old, and associated with periapical abscesses and toothaches (56%). The great majority (78%) were triaged as nonurgent, and most (93%) were discharged home.

Conclusion:  ED visits for dental problems of nontraumatic origin are not insignificant. Over the study period, these visits were greater than for diabetes and hypertensive diseases. Policy efforts are needed to provide alternative options for seeking emergency dental care in Ontario.
Clinical and haematological features in a compound heterozygote (HBB:c.92 + 5G > C/HBB:c.93‐2A > C) case of thalassaemia major
Authors: AGARWAL S. , TAMHANKAR P. M. , KUMAR R. , DALAL A.
Published: April 2009

An Indian Muslim boy was diagnosed with thalassaemia major at 3 months of age. His blood investigations revealed haemoglobin: 5.3 gm%, MCV: 68 fl, MCH 26.6 pg, MCHC: 39%, haemoglobin variant analysis: HbA2: 2.8%, HbF: 20.3% and HbA: 75.2% (post‐transfusion). His fathers’ haemoglobin was 10.2 gm%, MCV: 68 fl, MCH: 23.9 pg, MCHC: 35% HbA2: 4.7%, HbF: 0.7% and HbA: 85.2% and his mothers’ haemoglobin was 10.9 gm%, MCV: 67.4 fl, MCH 22.6 pg, MCHC: 33.5%, HbA2: 5.3%, HbF: 0% and HbA: 85.4%. The boy was found to be compound heterozygote for beta globin gene mutations (HBB:c.92 + 5G > C/HBB:c.93‐2A > C). The mutation HBB:c.93‐2A > C was inherited from his father. This report confirms the presence of HBB:c.93‐2A > C in the Indian subcontinent and has important implications for screening and prenatal diagnosis of beta thalassaemia. This report also supports inclusion of this mutation in the beta globin gene mutation database.
Isolation and characterization of microsatellite loci for mountain mullet (Agonostomus monticola)
Authors: FELDHEIM KEVIN A. , SANCHEZ PATRICK J. , MATAMOROS WILFREDO A. , SCHAEFER JACOB F. , KREISER BRIAN R.
Published: April 2009

We report on the isolation of 15 polymorphic microsatellite loci from mountain mullet (Agonostomus monticola). In the two populations sampled, loci exhibited two to 21 alleles and observed heterozygosity values ranged from 0.222 to 1.000. All loci conformed to Hardy–Weinberg equilibrium expectations, and none exhibited linkage disequilibrium. Although A. monticola is an important subsistence fishery in parts of its range, little is known about its ecology and many populations appear to be experiencing declines. These microsatellite loci should prove useful in the study of population structure of A. monticola and aid in other potential conservation efforts such as the management of hatchery broodstock.
Introduction: Philosophy in and Philosophy of Cognitive Science
Authors: Brook Andrew
Published: April 2009

Despite being there from the beginning, philosophical approaches have never had a settled place in cognitive research and few cognitive researchers not trained in philosophy have a clear sense of what its role has been or should be. We distinguish philosophyincognitive research and philosophyofcognitive research. Concerning philosophy in cognitive research, after exploring some standard reactions to this work by nonphilosophers, we will pay particular attention to the methods that philosophers use. Being neither experimental nor computational, they can leave others bewildered. Thought experiments are the most striking example but not the only one. Concerning philosophy of cognitive research, we will pay particular attention to its power to generate and test normative claims, claims about what should and should not be done.
The Part of Cognitive Science That Is Philosophy
Authors: Dennett Daniel C.
Published: April 2009

There is much good work for philosophers to do in cognitive science if they adopt the constructive attitude that prevails in science, work toward testable hypotheses, and take on the task of clarifying the relationship between the scientific concepts and the everyday concepts with which we conduct our moral lives.
Why Cognitive Science Needs Philosophy and Vice Versa
Authors: Thagard Paul
Published: April 2009

Contrary to common views that philosophy is extraneous to cognitive science, this paper argues that philosophy has a crucial role to play in cognitive science with respect to generality and normativity. General questions include the nature of theories and explanations, the role of computer simulation in cognitive theorizing, and the relations among the different fields of cognitive science. Normative questions include whether human thinking should be Bayesian, whether decision making should maximize expected utility, and how norms should be established. These kinds of general and normative questions make philosophical reflection an important part of progress in cognitive science. Philosophy operates best, however, not with a priori reasoning or conceptual analysis, but rather with empirically informed reflection on a wide range of findings in cognitive science.
Joint Action: Current Perspectives
Authors: Galantucci Bruno , Sebanz Natalie
Published: April 2009

In recent years researchers have begun to investigate how the perceptual, motor and cognitive activities of two or more individuals become organized into coordinated action. In the first part of this introduction we identify three common threads among the ten papers of this special issue that exemplify this new line of research. First, all of the papers are grounded in the experimental study of online interactions between two or more individuals. Second, albeit at different levels of analysis, the contributions focus on the mechanisms supporting joint action. Third, many of the papers investigate empirically the pre‐requisites for the highly sophisticated forms of joint action that are typical of humans. In the second part of the introduction, we summarize each of the papers, highlighting more specific connections among them.
Less Is More: A Minimalist Account of Joint Action in Communication
Authors: Shintel Hadas , Keysar Boaz
Published: April 2009

Language use can be viewed as a form of joint activity that requires the coordination of meaning between individuals. Because the linguistic signal is notoriously ambiguous, interlocutors need to draw upon additional sources of information to resolve ambiguity and achieve shared understanding. One way individuals can achieve coordination is by using inferences about the interlocutor’s intentions and mental states to adapt their behavior. However, such an inferential process can be demanding in terms of both time and cognitive resources. Here, we suggest that interaction provides interlocutors with many cues that can support coordination of meaning, even when they are neither produced intentionally for that purpose nor interpreted as signaling speakers’ intention. In many circumstances, interlocutors can take advantage of these cues to adapt their behavior in ways that promote coordination, bypassing the need to resort to deliberative inferential processes.
Joint Action: Neurocognitive Mechanisms Supporting Human Interaction
Authors: Bekkering Harold , De Bruijn Ellen R. A. , Cuijpers Raymond H. , Newman‐Norlund Roger , Van Schie Hein T. , Meulenbroek Ruud
Published: April 2009

Humans are experts in cooperating with each other when trying to accomplish tasks they cannot achieve alone. Recent studies of joint action have shown that when performing tasks together people strongly rely on the neurocognitive mechanisms that they also use when performing actions individually, that is, they predict the consequences of their co‐actor’s behavior through internal action simulation. Context‐sensitive action monitoring and action selection processes, however, are relatively underrated but crucial ingredients of joint action. In the present paper, we try to correct the somewhat simplified view on joint action by reviewing recent studies of joint action simulation, monitoring, and selection while emphasizing the intricate interrelationships between these processes. We complement our review by defining the contours of a neurologically plausible computational framework of joint action.
Prediction in Joint Action: What, When, and Where
Authors: Sebanz Natalie , Knoblich Guenther
Published: April 2009

Drawing on recent findings in the cognitive and neurosciences, this article discusses how people manage to predict each other’s actions, which is fundamental for joint action. We explore how a common coding of perceived and performed actions may allow actors to predict the what, when, and where of others’ actions. The “what” aspect refers to predictions about the kind of action the other will perform and to the intention that drives the action. The “when” aspect is critical for all joint actions requiring close temporal coordination. The “where” aspect is important for the online coordination of actions because actors need to effectively distribute a common space. We argue that although common coding of perceived and performed actions alone is not sufficient to enable one to engage in joint action, it provides a representational platform for integrating the actions of self and other. The final part of the paper considers links between lower‐level processes like action simulation and higher‐level processes like verbal communication and mental state attribution that have previously been at the focus of joint action research.
Just How Joint Is Joint Action in Infancy?
Authors: Carpenter Malinda
Published: April 2009

Joint action is central to countless aspects of human life. Here I examine the roots of joint action in infancy. First, I provide evidence that—contrary to popular belief—1‐year‐old infants do have the social‐cognitive prerequisites needed to participate in joint action, even in a relatively strict sense: they can read others’ goals and intentions, they have some basic understanding of common knowledge, and they have the ability and motivation to help others achieve their goals. Then I review some evidence of infants’ and young children’s active participation in different types of joint action, from prelinguistic communication to more instrumental collaborations with others, with a particular focus on whether young children show evidence of an understanding of the commitments and obligations entailed in joint action. I conclude that the uniquely human ability and motivation to participate in joint action is already seen in infants by 1 year of age.
Combination Therapy with Digoxin and Diltiazem Controls Ventricular Rate in Chronic Atrial Fibrillation in Dogs Better than Digoxin or Diltiazem Monotherapy: A Randomized Crossover Study in 18 Dogs
Authors: Gelzer A.R.M. , Kraus M.S. , Rishniw M. , Moïse N.S. , Pariaut R. , Jesty S.A. , Hemsley S.A.
Published: April 2009

Background: Atrial fibrillation (AF) with excessively high ventricular rates (VR) occurs in dogs with advanced heart disease. Rate control improves clinical signs in these patients. Optimal drug therapy and target VR remain poorly defined.

Hypothesis: Digoxin‐diltiazem combination therapy reduces VR more than either drug alone in dogs with high VR AF.

Animals: Eighteen client‐owned dogs (>15 kg) with advanced heart disease, AF, and average VR on 24‐hour Holter > 140 beats per minute (bpm).

Methods: After baseline Holter recording, dogs were randomized to digoxin or diltiazem monotherapy, or combination therapy. Repeat Holter evaluation was obtained after 2 weeks; dogs were then crossed over to the other arm (monotherapy or combination therapy) for 2 weeks and a third Holter was acquired. Twenty‐four hour average VR, absolute and relative VR changes from baseline, and percent time spent within prespecified VR ranges (>140, 100–140, and <100 bpm) were compared. Correlations between serum drug concentrations and VR were examined.

Results: Digoxin (median, 164 bpm) and diltiazem (median, 158 bpm) decreased VR from baseline (median, 194 bpm) less than the digoxin‐diltiazem combination (median, 126 bpm) (P < .008 for each comparison). With digoxin‐diltiazem, VR remained <140 bpm for 85% of the recording period, but remained >140 bpm for 88% of the recording period with either monotherapy. Serum drug concentrations did not correlate with VR.

Conclusions and Clinical Importance: At the dosages used in this study, digoxin‐diltiazem combination therapy provided a greater rate control than either drug alone in dogs with AF.
Evaluation of a Portable Meter to Measure Ketonemia and Comparison with Ketonuria for the Diagnosis of Canine Diabetic Ketoacidosis
Authors: Tommaso M. Di , Aste G. , Rocconi F. , Guglielmini C. , Boari A.
Published: April 2009

Background:The diagnosis of canine diabetic ketoacidosis (DKA) usually is based on measurement of urinary acetoacetate (ketonuria). In humans, this test is less sensitive and specific than blood 3‐β‐hydroxybutyrate (ketonemia) evaluation.

Hypothesis:Ketonemia measurement using a portable meter is more accurate than ketonuria determination with a dipstick to diagnose canine DKA.

Animals:Seventy‐two client‐owned diabetic dogs with ketonemia, ketonuria, or both.

Methods:Prospective observational study. Based on blood bicarbonate concentration and anion gap, dogs were divided into 2 groups: patients with DKA (n= 25); patients with diabetic ketosis (n= 47). Sensitivity, specificity, and positive and negative likelihood ratio (LR) at different cut‐off points were determined for both ketonemia and ketonuria. Receiver operating characteristic (ROC) analysis was used to assess the accuracy of each diagnostic test to diagnose DKA.

Results:With regard to ketonemia, cut‐off values of 2.3 and 4.3 mmol/L revealed 100% sensitivity and 100% specificity, respectively, whereas cut‐off values of 2.8 and 3.5 mmol/L showed a −LR of 0.05 and a + LR of 13.16, respectively. With regard to ketonuria, a cut‐off value of 1+ revealed 92% sensitivity, 40% specificity, and −LR of 0.20, whereas a cut‐off value of 3+ revealed 44% sensitivity, 94% specificity, and +LR of 6.89. The areas under the ROC curves for the ketonemia and ketonuria tests were significantly different (0.97 and 0.81, respectively,P= .003).

Conclusions and Clinical Importance:Measurement of ketonemia is accurate and more effective than measurement of ketonuria to diagnose canine DKA.
Parametric Design of a Spherical Eight-Bar Linkage Based on a Spherical Parallel Manipulator
Authors: Soh Gim Song , McCarthy J. Michael
Published: April 2009

This paper presents a procedure that determines the dimensions of two constraining links to be added to a three degree-of-freedom spherical parallel manipulator so that it becomes a one degree-of-freedom spherical (8, 10) eight-bar linkage that guides its end-effector through five task poses. The dimensions of the spherical parallel manipulator are unconstrained, which provides the freedom to specify arbitrary base attachment points as well as the opportunity to shape the overall movement of the linkage. Inverse kinematics analysis of the spherical parallel manipulator provides a set of relative poses between all of the links, which are used to formulate the synthesis equations for spherical RR chains connecting any two of these links. The analysis of the resulting spherical eight-bar linkage verifies the movement of the system.
Analyzing Bounding and Galloping Using Simple Models
Authors: Waldron Kenneth J. , Estremera J. , Csonka Paul J. , Singh S. P. N.
Published: April 2009

This paper focuses on modeling the gait characteristics of a quadrupedal gallop. There have been a number of studies of the mechanics of the stance phase in which a foot is in contact with the ground. We seek to put these studies in the context of the stride, or overall motion cycle. The model used is theoretical, and is kept simple in the interest of transparency. It is compared to empirical data from observations of animals, and to data from experiments with robots such as our KOLT machine, and results from sophisticated simulation studies. Modeling of the energy loss inherent in the interaction between the system and the environment plays a key role in the study. Results include the discovery of a hidden symmetry in the gait pattern, usually regarded as being completely asymmetrical. Another result demonstrates that the velocities with which the two front feet impact and leave the ground are different, and similarly for the rear feet. The velocities of the foot pairs mirror each other. This is consistent with empirical observation, but is at variance with the assumption used almost universally when modeling stance. A further result elicits the importance of the pitch moment of inertia and other effects that make the mammalian architecture, in which the center of mass is closer to the shoulders than to the hips, beneficial..
The Design of an Expressive Humanlike Socially Assistive Robot
Authors: Allison Brian , Nejat Goldie , Kao Emmeline
Published: April 2009

It is anticipated that the use of assistive robots will be one of the most important service applications of robotic systems of the future. In this paper, the development of a unique noncontact socially assistive robot consisting of a humanlike demeanor is presented for utilization in hospital wards and nursing∕veteran homes to study its role and impact on the well-being of patients, addressing patient’s needs and its overall effect on the quality of patient care. The robot will be an embodied entity that will participate in hands-off noncontact social interaction with a patient during the convalescence, rehabilitation, or end-of-life care stage. The robot has been designed as a platform to incorporate the three design parameters of embodiment, emotion, and nonverbal communication to encourage natural human-robot interactions. Herein, we present the overall mechanical design of the socially assistive robot focusing mainly on the development of the actuation system of the face, head, and upper body. In particular, we propose the development of a unique muscle actuation mechanism for the robotic face to allow for the display of rich facial expressions during social assistive interaction scenarios. The novelty of the actuation system is in its use of the dependency of facial muscle activity to minimize the number of individual actuators required to control the robotic face.
Parametric Design and Power-Flow Analysis of Parallel Force∕Velocity Actuators
Authors: Rabindran Dinesh , Tesar Delbert
Published: April 2009

In this paper we introduce a dual-input actuator, based on an epicyclic gear train, called parallel force∕velocity actuator (PFVA) designed for variable response manipulation. The focus of this work is to formulate a parametric representation for internal and external power flows, and effective inertia in this actuator. Dimensionless criteria have been developed to judge the design of a PFVA, based on the above phenomena. These criteria are then related to two fundamental dimensionless parameters of a PFVA: (i) a design parameter called the relative scale factor that describes the relative kinematic scaling between the two inputs of the PFVA and (b) an operational parameter called the velocity mixing ratio that represents the velocities of the inputs relative to each other. Some numerical examples have been considered using PFVA designs based on positive-ratio drives to convey the practical implication of our parametric models. Based on this study a set of design and operational guidelines has been suggested, which we believe will be useful to the designer in evaluating PFVA designs and operational scenarios on the basis of power-flow and effective inertias. As a representative result, it was observed that the efficiency of a PFVA decreases approximately 19% from the basic efficiency when the relative scale factor was increased approximately 6.5 times (from 4.7 to 25.27) and the velocity mixing ratio was increased 10 times (from 4.16 to 41.6).
Singularity Analysis of an Extensible Kinematic Architecture: Assur Class N, Order N−1
Authors: Myszka David H. , Murray Andrew P. , Schmiedeler James P.
Published: April 2009

This paper presents an analysis to create a general singularity condition for a mechanism that contains a deformable closed contour. This kinematic architecture is particularly relevant to rigid-link, shape-changing mechanisms. Closed contour shape-changing mechanisms will be shown to belong to the Assur classification because of the pattern of interconnections among the links. The general singularity equations are reduced to a condensed form, which allows geometric relationships to be readily detected. The analysis is repeated for alternative input links. A method for formulating the singularity condition for an Assur Class N, knowing the condition for a Class N−1 mechanism, is given. This approach is illustrated with several examples.
The Kinetostatic Conditioning of Two-Limb Schönflies Motion Generators
Authors: Gauthier Jean-François , Angeles Jorge , Nokleby Scott B. , Morozov Alexei
Published: April 2009

This paper introduces a study on the kinetostatic conditioning of two-limb Schönflies motion generators. These are robots capable of producing the motions undergone by the end-effector of what is known as selective-compliance assembly robot arm (SCARA) systems, which can best be described as the motions of the tray of a waiter: three independent translations plus one rotation about an axis of fixed orientation. SCARA systems are usually understood as four-axis serial robots, Schönflies motion generators being a generalization thereof, that encompass first and foremost parallel architectures. Kinetostatic conditioning is understood here in connection with the condition number of each of the two Jacobian matrices of the parallel robot under study. After a brief introduction on the geometry and the kinematics of two-limb parallel systems, the kinetostatics of this class of robots is discussed; whence, the calculation of the kinetostatic conditioning of these robots is undertaken. The motivation behind this work is the need to understand an unstable behavior of the prototype in a substantial part of its workspace, which is attributed to poor conditioning. A main result of this paper is the correlation between the shortest dimension of the robot kinematic chain and the characteristic length, which hints to the need of specifying the range of the characteristic length when optimizing the dimensions of robots of the class studied here, a result that may equally hold for parallel robots in general.
A Biarticulated Robotic Leg for Jumping Movements: Theory and Experiments
Authors: Babič J. , Lim Bokman , Omrčen D. , Lenarčič J. , Park F. C.
Published: April 2009

This paper investigates the extent to which biarticular actuation mechanisms—spring-driven redundant actuation schemes that extend over two joints, similar in function to biarticular muscles found in legged animals—improve the performance of jumping and other fast explosive robot movements. Robust numerical optimization algorithms that take into account the complex dynamics of both the redundantly actuated system and frictional contact forces are developed. We then quantitatively evaluate the gains in vertical jumping vis-à-vis monoarticular and biarticular joint actuation schemes and examine the effects of spring stiffness and activation angle on overall jump performance. Both numerical simulations and experiments with a hardware prototype of a biarticular legged robot are reported.
A Fast and Robust Hybrid Method for the Solution of the 6-3 Stewart–Gough Platform Direct Position Analysis
Authors: Vertechy R. , Parenti-Castelli V.
Published: April 2009

A robust and accurate hybrid method for the real-time estimation of the actual configuration of 6-3 Stewart–Gough platforms is presented. The method is hybrid since on one hand it requires the use of three extra sensors in addition to the six ones, which measure the lengths of the manipulator legs, and on the other hand it reduces the influence of sensor noise on the pose estimate by means of either an iterative procedure, which is based on the Newton–Raphson scheme, at regular configurations, or by means of a noniterative procedure, which is based on the study of the null-space of the manipulator Jacobian, in the vicinity of singular configurations. The method is robust since it does not fail near singular configurations and it detects the actual assembly mode of the manipulator. It is also accurate since it always provides a solution, which satisfies the kinematic constraint equations of the manipulator and is rather insensitive to sensor noise. The method is fast since the estimation of the actual configuration of the mechanism requires a limited number of operations, which can be executed in real-time. Analytical and numerical results are reported to show the robustness, accuracy, and computational efficiency of the proposed method.
Kinematic Representations of Pop-Up Paper Mechanisms
Authors: Winder Brian G. , Magleby Spencer P. , Howell Larry L.
Published: April 2009

Pop-up paper mechanisms use techniques similar to the well-studied paper folding techniques of origami. However, pop-ups differ in both the manner of construction and the target uses, warranting further study. This paper outlines the use of planar and spherical kinematics to model commonly used pop-up paper mechanisms. A survey of common joint types is given, including folds, interlocking slots, bends, pivots, sliders, and rotating sliders. Also included is an overview of common one-piece and layered mechanisms, including single-slit, double-slit, V-fold, tent, tube strap, and arch mechanisms. Each mechanism or joint is shown using both a paper representation and either a rigid-body or pseudo-rigid-body representation. In addition, this paper shows that more complex mechanisms may be created by combining simple mechanisms in various ways. The principles presented are applied to the creation of new pop-up joints and mechanisms. The new mechanisms employ both spherical and spatial kinematic chains. Understanding pop-up mechanism kinematics could lead to new applications in deployable structures, packaging, and instruments for minimally invasive surgery.
Polynomial Solution to the Position Analysis of Two Assur Kinematic Chains With Four Loops and the Same Topology
Authors: Borràs Júlia , Di Gregorio Raffaele
Published: April 2009

The direct position analysis (DPA) of a manipulator is the computation of the end-effector poses (positions and orientations) compatible with assigned values of the actuated-joint variables. Assigning the actuated-joint variables corresponds to considering the actuated joints locked, which makes the manipulator a structure. The solutions of the DPA of a manipulator one to one correspond to the assembly modes of the structure that is generated by locking the actuated-joint variables of that manipulator. Determining the assembly modes of a structure means solving the DPA of a large family of manipulators since the same structure can be generated from different manipulators. This paper provides an algorithm that determines all the assembly modes of two structures with the same topology that are generated from two families of mechanisms: one planar and the other spherical. The topology of these structures is constituted of nine links (one quaternary link, four ternary links, and four binary links) connected through 12 revolute pairs to form four closed loops.
Evaluation and Representation of the Theoretical Orientation Workspace of the Gough–Stewart Platform
Authors: Jiang Qimi , Gosselin Clément M.
Published: April 2009

The evaluation and representation of the orientation workspace of robotic manipulators is a challenging task. This work focuses on the determination of the theoretical orientation workspace of the Gough–Stewart platform with given leg length ranges [ρimin,ρimax]. By use of the roll-pitch-yaw angles (ϕ,θ,ψ), the theoretical orientation workspace at a prescribed position P0 can be defined by up to 12 workspace surfaces. The defined orientation workspace is a closed region in the 3D orientation Cartesian space Oϕθψ. As all rotations R(x,ϕ), R(y,θ), and R(z,ψ) take place with respect to the fixed frame, any point of the defined orientation workspace provides a clear measure for the platform to, respectively, rotate in order around the (x,y,z) axes of the fixed frame. An algorithm is presented to compute the size (volume) of the theoretical orientation workspace and intersectional curves of the workspace surfaces. The defined theoretical orientation workspace can be applied to determine a singularity-free orientation workspace.
A Novel Family of Leaf-Type Compliant Joints: Combination of Two Isosceles-Trapezoidal Flexural Pivots
Authors: Pei Xu , Yu Jingjun , Zong Guanghua , Bi Shusheng , Hu Yida
Published: April 2009

The leaf-type isosceles-trapezoidal flexural (LITF) pivot consists of two compliant beams and two rigid bodies. For a single LITF pivot, the range of motion is small while the center-shift is relatively large. The capability of performance can be improved greatly by the combination of two LITF pivots. Base on the pseudorigid-body (PRB) model of a LITF pivot, a method to construct the double-LITF pivots is presented by regarding a single LITF pivot as a the configurable flexure module. The trends of the center-shift are mainly considered by using this method with the combination of two LIFT pivots. Eight types of double-LITF pivots are synthesized. Compared with the single LIFT pivot, the stroke becomes larger, and stiffness becomes smaller. Four of them have the increased center-shift. The other four have the decreased center-shift. Two of the double-LITF pivots are selected as the examples to explain the proposed method. The comparison between PRB model and finite element analysis result shows the validity and effectiveness of the method.
A Quasi-Static Model for Planar Compliant Parallel Mechanisms
Authors: Quennouelle Cyril , Gosselin Clément
Published: April 2009

In this paper, the mobility, the kinematic constraints, the pose of the end-effector, and the static constraints that lead to the kinematostatic model of a compliant parallel mechanism are introduced. A formulation is then provided for its instantaneous variation—the quasi-static model. This new model allows the calculation of the variation in the pose as a linear function of the motion of the actuators and the variation in the external loads through two new matrices: the compliant Jacobian matrix and the Cartesian compliance matrix that give a simple and meaningful formulation of the model of the mechanism. Finally, a simple application to a planar four-bar mechanism is presented to illustrate the use of this model and the new possibilities that it opens, notably the study of the kinematics for any range of applied load.
A Pseudorigid-Body 3R Model for Determining Large Deflection of Cantilever Beams Subject to Tip Loads
Authors: Su Hai-Jun
Published: April 2009

In this paper, a pseudorigid-body (PRB) 3R model, which consists of four rigid links joined by three revolute joints and three torsion springs, is proposed for approximating the deflection of a cantilever beam subject to a general tip load. The large deflection beam equations are solved through numerical integration. A comprehensive atlas of the tip deflection for various load modes is obtained. A three-dimensional search routine has been developed to find the optimal set of characteristic radius factors and spring stiffness of the PRB 3R model. Detailed error analysis has been done by comparing with the precomputed tip deflection atlas. Our results show that the approximation error is much less than that of the conventional PBR 1R model. To demonstrate the use of the PRB 3R model, a compliant four-bar linkage is studied and verified by a numerical example. The result shows a maximum tip deflection error of 1.2% compared with the finite element analysis model. The benefits of the PRB 3R model include that (a) the model parameters are independent of external loads, (b) the approximation error is relatively small for even large deflection beams, and (c) the derived kinematic and static constraint equations are simpler to solve compared with the finite element model.
Forward Displacement Analysis of a Quadratic Planar Parallel Manipulator: 3-RP̱R Parallel Manipulator With Similar Triangular Platforms 1
Authors: Kong Xianwen , Gosselin Clément M.
Published: April 2009

A quadratic parallel manipulator refers to a parallel manipulator with a quadratic characteristic polynomial. This paper revisits the forward displacement analysis (FDA) of a quadratic parallel manipulator: 3-RP̱R planar parallel manipulator with similar triangular platforms. Although it has been revealed numerically elsewhere that for this parallel manipulator, the four solutions to the FDA fall, respectively, into its four singularity-free regions (in its workspace), it is unclear if there exists a one-to-one correspondence between the four formulas, each producing one solution to the FDA, and the four singularity-free regions. Using an algebraic approach, this paper will prove that such a one-to-one correspondence exists. Therefore, a unique solution to the FDA can be obtained in a straightforward way for such a parallel manipulator if the singularity-free region in which it works is specified.
A Kinetoelastic Formulation of Compliant Mechanism Optimization
Authors: Wang Michael Yu
Published: April 2009

The current design algorithms for compliant mechanisms often generate solutions that imitate rigid-body linkages by means of point flexures or flexure pivots, by using the popular spring model formulation. This paper presents a kinetoelastic formulation for compliant mechanism optimization. With a state equation of the mechanism defined by the elasticity theory, the model incorporates not only the kinematic function requirements of the mechanism but, more importantly, the necessary conditions on the compliance characteristics of the mechanism’s structure. The kinematics of the compliant mechanism is defined on rigid bodies of input/output ports and is related to a set of kinetoelastic factors of the mechanism’s compliance matrix. The kinetoelastic formulation is applied to the problem of optimizing a compliant translational joint, producing compliant designs with compliance properties such as the leaf spring type sliding joint as opposed to the notch-type joint. This paper represents an initial development toward a more general methodology for compliant mechanism optimization.
Film-Cooling Enhancement of the Mist Vertical Wall Jet on the Cylindrical Channel Surface With Heat Transfer
Authors: Terekhov V. I. , Pakhomov M. A.
Published: April 2009

Results of a numerical study of heat and mass transfer in a gas-droplet wall jet developing over a surface with supplied heat flux are reported. The calculation model is based on an Eulerian/Eulerian approach using a turbulence model that allows for the dynamic and thermal interactions between the phases. This approach is based on using the kinetic equation of probability density function for the coordinates, velocities, and temperatures of droplets in the turbulent flow (Derevich, I. V., “The Hydrodynamics and Heat Transfer and Mass Transfer of Particles Under Conditions of Turbulent Flow of Gas Suspension in a Pipe and in an Axisymmetric Jet,” 2002, High Temp., 40, pp. 78–91). The effects due to many factors are traced, including the dispersed-phase concentration in the wall jet, the droplet diameter, the blowing ratio m=ρSUS/ρ1U1, the main-flow temperature, and the wall heat flux. A considerable enhancement of heat transfer at relatively low mass concentrations of droplets MLS in the jet (more than twofold at MLS≤0.05) has been revealed.
Modeling Frost Growth for Subcooled Tube-Array Configurations
Authors: Yadav V. , Moon C. G. , Kant K.
Published: April 2009

Methodology for predicting frost growth trends on a subcooled cylindrical surface is developed and implemented for multitube array configuration. Extension of conventional analysis and a novel technique for understanding frost formation phenomenon on the cylindrical surfaces is proposed; later one takes into account the nonsteady temperature field, which affects the density and thermal conductivity at a local level in the growing frost mass, for more accurate prediction of thermal resistance. The influence of migration of liquid water due to tortuosity effect is also considered. The results due to new model are found to be in good agreement with the data in the open literature. Data for frost thickness ratio (FTR) versus time for a section of array with four (tube) rows in the airstream are presented and thoroughly analyzed. The trends of FTR noted are complex and considerably dependent on the tube location, temperature of subcooled surface (Ts), airflow velocity (Ua), and the relative humidity (RHa) values. Approximate ranges for important parameters are −30≤Ts≤−5.0°C, 1.0≤Ua≤5.0 m/s, and 0.20≤RHa≤0.80. Presented analysis and the results are valuable in order to predict probable locations and precursors to partial or complete choking of airflow passages due to frost deposition in the evaporator coils.
Vertical Movement of Isothermal Lines in Water
Authors: Gorman William R. , Parks Gregory J. , Brownridge James D.
Published: April 2009

We experimentally investigated the development and vertical movement of isothermal lines in cooling columns of confined water. The isothermal line develops spontaneously whenever the bottom of the column cools to ∼4°C before the top. The width of these lines was typically less than 1 cm, with up to a 3°C thermal gradient across these lines. The velocity was inversely proportional to the diameter of the column. The velocity was 1.4±0.1 cm/min when the column diameter was 2.2 cm, and decreases to 0.4±0.1 cm/min when the diameter was increased to 12.5 cm. Data presented here also raise serious questions about the claim of new phase transitions in water made by Esposito et al. (2008, “Mpemba Effect and Phase Transitions in the Adiabatic Cooling of Water Before Freezing,” Physica A, 387, pp. 757–763).