bluuebunny/crossref_metadata_2025 huggingface dataset:
Social Connection Through Joint Action and Interpersonal Coordination
Authors: Marsh Kerry L. , Richardson Michael J. , Schmidt R. C.
Published: April 2009

The pull to coordinate with other individuals is fundamental, serving as the basis for our social connectedness to others. Discussed is a dynamical and ecological perspective to joint action, an approach that embeds the individual’s mind in a body and the body in a niche, a physical and social environment. Research on uninstructed coordination of simple incidental rhythmic movement, along with research on goal‐directed, embodied cooperation, is reviewed. Finally, recent research is discussed that extends the coordination and cooperation studies, examining how synchronizing with another, and how emergent social units of perceiving and acting are reflected in people’s feelings of connection to others.
Contrasting the Social Cognition of Humans and Nonhuman Apes: The Shared Intentionality Hypothesis
Authors: Call Josep
Published: April 2009

Joint activities are ubiquitous in the animal kingdom, but they differ substantially in their underlying psychological states. Humans attribute and share mental states with others in the so‐called shared intentionality. Our hypothesis is that our closest nonhuman living relatives also attribute some psychological mechanisms such as perceptions and goals to others, but, unlike humans, they are not necessarily intrinsically motivated to share those psychological states. Furthermore, it is postulated that shared intentionality is responsible for the appearance of a suite of behaviors, including joint attention, declarative communication, imitative learning, and teaching, that are the basis of cultural learning and the social norms and traditions present in every human culture.
Experimental Semiotics: A New Approach for Studying Communication as a Form of Joint Action
Authors: Galantucci Bruno
Published: April 2009

In the last few years, researchers have begun to investigate the emergence of novel forms of human communication in the laboratory. I survey this growing line of research, which may be calledexperimental semiotics, from three distinct angles. First, I situate the new approach in its theoretical and historical context. Second, I review a sample of studies that exemplify experimental semiotics. Third, I present an empirical study that illustrates how the new approach can help us understand the socio‐cognitive underpinnings of human communication. The main conclusion of the paper will be that, by reproducing micro samples of historical processes in the laboratory, experimental semiotics offers new powerful tools for investigating human communication as a form of joint action.
Cytologic examination of fine‐needle aspirates from mammary gland tumors in the dog: diagnostic accuracy with comparison to histopathology and association with postoperative outcome
Authors: Simon Daniela , Schoenrock Dorina , Nolte Ingo , Baumgärtner Wolfgang , Barron Ronnie , Mischke Reinhard
Published: April 2009

Background: Mammary tumors are the most common neoplasms in female dogs. Malignant tumors may carry a poor prognosis and necessitate surgery. Few data are available on the value of cytologic examination as a diagnostic or prognostic tool for mammary tumors in dogs.

Objectives: The objectives of this study were to determine whether cytologic findings in fine‐needle aspirate specimens of canine mammary tumors correlate with histopathologic results and whether the cytologic diagnosis is associated with postoperative outcome.

Methods: In this prospective study, fine‐needle aspirate samples were obtained from 50 mammary tumors in 50 dogs. Results of cytologic and histopathologic examination were compared, using the histologic diagnosis as the reference method. Kaplan–Meier log rank analysis was used to evaluate univariate association of the cytologic diagnosis with duration of survival, local control, and metastasis‐free interval.

Results: Adequate cytologic samples were obtained in 43/50 (86%) cases. The cytologic diagnosis correlated with the histologic diagnosis for benign and malignant tumors in 40/43 (93%) and 35/43 (81%) cases, respectively. Cytologic examination had a sensitivity of 88% and a specificity of 96% for the diagnosis of malignancy. The cytologic diagnosis had significant univariate association with duration of survival (P=.016), recurrence‐free interval (P=.003), and metastasis‐free interval (P=.014).

Conclusions: Cytologic examination of mammary tumors in the dog has satisfactory accuracy, sensitivity, and specificity for the diagnosis of malignancy and is associated with postoperative outcome. Further studies on the diagnostic accuracy of cytology as well as multivariate analysis of its preoperative prognostic value in mammary tumors in the dog are warranted.
Influence of Age on Surfactant Isolated from Healthy Horses Maintained on Pasture
Authors: Christmann U. , Hite R.D. , Witonsky S.G. , Elvinger F. , Werre S.R. , Thatcher C.D. , Tan R.H.H. , Buechner‐Maxwell V.A.
Published: April 2009

Background:Surfactant alterations are described in horses after exercise, anesthesia, and prolonged transport, in horses with recurrent airway obstruction, and in neonatal foals. The effect of horse age or bronchoalveolar lavage fluid (BALF) sample characteristics on surfactant is unknown.

Objectives:To evaluate surfactant phospholipid composition and function in healthy horses, and to investigate the influence of age and BALF sample characteristics on surfactant.

Animals:Seventeen healthy horses 6–25 years of age maintained on pasture year‐round.

Methods:BALF was collected by standard procedures and was assessed for recovery volume, nucleated cell count (NCC), and cytology. Cell‐free BALF was separated into crude surfactant pellet (CSP) and surfactant supernatant (Supe) by ultracentrifugation. Phospholipid and protein content were determined from both fractions. CSP phospholipid composition was analyzed by high‐performance liquid chromatography with an evaporative light scatter detector. Surface tension of CSP was evaluated with a pulsating bubble surfactometer. Regression analysis was used to evaluate associations between age, BALF sample characteristics, and surfactant variables.

Results:Results and conclusions were derived from 15 horses. Increasing age was associated with decreased phospholipid content in CSP but not Supe. Age did not affect protein content of CSP or Supe, or surfactant phospholipid composition or function. Age‐related surfactant changes were unaffected by BALF recovery percentage, NCC, and cytological profile.

Conclusions and Clinical Importance:Older horses have decreased surfactant phospholipid content, which might be because of age‐related pulmonary changes. Surfactant composition is unaffected by BALF sample characteristics at a BALF recovery percentage of at least 50%.
Possible Emergence of Drug‐Resistant Variants ofBabesia gibsoniin Clinical Cases Treated with Atovaquone and Azithromycin
Authors: Sakuma M. , Setoguchi A. , Endo Y.
Published: April 2009

Background:There is no well‐established treatment strategy forBabesia gibsoniinfection. A new therapeutic protocol using atovaquone (ATV) and azithromycin (AZM) has been proposed, but there is concern about the possible induction of relapse and the emergence of ATV‐resistant variants after treatment.

Objective:To evaluate the clinical use of combination therapy with ATV and AZM as a first‐line treatment of clinicalB. gibsoniinfection in dogs, and to investigate the emergence of ATV‐resistant variants.

Animals:EightB. gibsoninaturally infected dogs showing signs of acute onset of disease.

Methods:Retrospective case study. Eight clinical cases received combination therapy with ATV and AZM at Kagoshima University Veterinary Teaching Hospital during 2007–2008, and their clinical courses and clinicopathological parameters were evaluated. In addition, alterations in thecytochrome b(CYTb) gene ofB. gibsoniwere analyzed by polymerase chain reaction and DNA sequencing techniques.

Results:All of the dogs responded well to the treatment, with rapid improvement in their clinical condition and hematological parameters. However, 5 of the 8 dogs relapsed after treatment. Analysis of theCYTbgene strongly suggested the emergence of ATV‐resistant variants after treatment.

Conclusions and Clinical Importance:The combination of ATV and AZM can be used as a first‐line treatment for dogs with babesiosis, but relapses occur. Attention should be paid to the possible in vivo selection of drug‐resistant variants.
Hematology and Serum Biochemistry of Feline Immunodeficiency Virus‐Infected and Feline Leukemia Virus‐Infected Cats
Authors: Gleich S. , Hartmann K.
Published: April 2009

Background:Hematological and biochemical values in cats naturally infected by feline immunodeficiency virus (FIV) or feline leukemia virus (FeLV) are not completely documented.

Objective:Report differences in laboratory values between FIV‐ or FeLV‐infected and noninfected and between FIV‐ and FeLV‐infected cats.

Animals:Three thousand seven hundred and eighty client‐owned cats tested for FIV and FeLV.

Methods:Retrospective study. Evaluation of clinicopathologic changes in cats with defined FIV and FeLV status and for which laboratory data were available.

Results:FIV‐infected cats were more likely to be neutropenic (odds ratio [OR]=3.6, 95% confidence interval [95% CI] 2.1–6.2,P< .0001) and had lower serum activities of aspartate aminotransferase and glutamate dehydrogenase than control cats; serum total protein (8.1 ± 1.1 versus 7.6 ± 1.3 g/dL,P< .001) and γ‐globulin concentrations (2.2 ± 1.1 versus 1.7 ± 1.3 g/dL,P< .001) were higher than in uninfected cats. Compared with controls, FeLV‐infected cats had a higher risk of anemia (OR = 3.8, 95% CI 2.4–6.0,P< .0001), thrombocytopenia (OR = 5.0, 95% CI 3.0–8.4,P< .0001), neutropenia (OR = 3.6, 95% CI 2.1–6.1,P< .0001), lymphocytosis (OR = 2.8, 95% CI 1.6–4.8,P= .0002), and lower erythrocyte counts (6.13 ± 2.95 × 103versus 8.72 ± 2.18 × 103/μL,P< .001), thrombocyte counts (253.591 ± 171.841 × 103versus 333.506 ± 156.033 × 103/μL,P< .001), hematocrit (28.72 ± 12.86 versus 37.67 ± 8.90%,P< .001), hemoglobin and creatinine concentration.

Conclusions and Clinical Importance:Hematologic abnormalities are common in FeLV‐infected but not in FIV‐infected cats. Clinicopathologic abnormalities are less frequent in FIV‐infected cats and might reflect an unspecific immunologic response.
Magnetic Resonance Imaging Characteristics of Necrotizing Meningoencephalitis in Pug Dogs
Authors: Young B. D. , Levine J. M. , Fosgate G. T. , De Lahunta A. , Flegel T. , Matiasek K. , Miller A. , Silver G. , Sharp N. , Greer K. , Schatzberg S. J.
Published: April 2009

Background:The magnetic resonance imaging (MRI) characteristics of necrotizing meningoencephalitis (NME) are not well documented.

Objectives:To describe common MRI features of NME, to compare the MRI features to histopathologic findings, and to determine whether or not MRI lesions are predictive of survival time.

Animals:Eighteen Pugs with NME.

Methods:Retrospective MRI case study of Pugs identified by a search of medical records at 6 veterinary institutions. Eighteen dogs met inclusion criteria of histopathologically confirmed NME and antemortem MRI exam. MRI lesions were characterized and compared with histopathology with the kappa statistic. Survival times were compared with MRI findings by use of Mann‐WhitneyU‐tests and Spearman's ρ.

Results:Twelve of 18 lesions were indistinctly marginated with mild parenchymal contrast enhancement. Prosencephalic (17/18) lesion distribution included the parietal (16/18), temporal (16/18), and occipital (16/18) lobes. There were cerebellar (4/18) and brainstem (3/18) lesions. Asymmetric lesions were present in both gray and white matter in all dogs. Falx cerebri shift was common (11/18), and 6 dogs had brain herniation. Leptomeningeal enhancement was present in 9/18 dogs. A moderate positive association was found between parenchymal contrast enhancement and both necrosis (κ= 0.45;P= .045) and monocytic inflammation (κ= 0.48;P= .025). Higher MRI lesion burden was correlated with longer time from disease onset to MRI (P= .045). MRI lesion burden did not correlate to survival time.

Conclusions and Clinical Importance:Asymmetric prosencephalic grey and white matter lesions with variable contrast enhancement were consistent MRI changes in Pugs with confirmed NME. While not pathognomonic for NME, these MRI characteristics should increase confidence in a presumptive diagnosis of NME in young Pugs with acute signs of neurologic disease.
Reproducibility of Airway Responsiveness in Horses Using Flowmetric Plethysmography and Histamine Bronchoprovocation
Authors: Nolen‐Walston R. D. , Kuehn H. , Boston R. C. , Mazan M. R. , Wilkins P. A. , Bruns S. , Hoffman A. M.
Published: April 2009

Background:Inflammatory airway disease has a high prevalence in horses, but is often a diagnostic challenge. Flowmetric plethysmography and histamine bronchoprovocation (FP/HBP) is a simple and effective tool for diagnosis, but reproducibility of these measurements made over time has not been established.

Hypothesis:We hypothesize that the measurement of airway responsiveness in horses using FP/HBP is consistent over both short and long periods of time.

Animals:Twenty‐nine healthy adult horses from 2 university herds.

Methods:In this prospective experimental study, airway responsiveness was determined in each horse at day 0 (baseline [BL]) with FP/ HBP, using PC35 (provocative concentration of histamine needed to increase Δflowby 35%) as a measure of airway responsiveness. Each horse was re‐tested 1–4 weeks after BL (short‐term [ST]) and again at 3–12 months after BL (long‐term [LT]).

Results:In the ST period, 23/27 (85%) of the horses had a PC35 that was within 1 doubling concentration of histamine of their BL value, with a mean change of 0.52 doubling concentrations (95% CI 0.26–0.79, range 0–2.06). For the LT data, 19/26 (73%) of horses were within 1 doubling concentration of their BL value, with a mean change of 0.81 doubling concentrations (95% CI 0.45–1.17, range 0.14–3.10). There was no significant difference in reproducibility between the 2 groups of subjects.

Conclusions and Clinical Importance:Repeated measurements of airway responsiveness obtained with FP/HBP show acceptable reproducibility over time periods up to a year. However, caution must be used when testing horses when ambient air temperature is low.
Rattling the Hesam: International Distractions from Internal Problems in Iran
Authors: Tures John A.
Published: April 2009

President Mahmoud Ahmadinejad began waging a war of words against the state of Israel several months after he won Iran's 2005 election. This article explores the motives for his fiery rhetoric. A series of explanations including ideological zeal, inexperience, international pressure, unifying regional regimes, and inciting a war with Israel are evaluated and critiqued. This article offers a new rationale that examines internal politics as a motive for the Iranian leader's speeches. The diversionary theory of conflict, which claims that leaders try to overcome domestic shortcomings with foreign distractions, is examined in this context. But while this theory has typically been associated with war and unifying the country's political structure, this article contends that President Ahmadinejad's plan may not be full‐scale war, but a verbal confrontation and subtle support for terror groups, which can be just as effective in achieving internal aims. Such a policy would also win converts among the rank‐and‐file Arabs. The resulting regional prestige is also designed to mask his domestic shortcomings in the political and economic arena. Blasting Israel and boosting groups such as Hizballah and Hamas, while receiving cheers from many Arab people for standing up to Israel, in other words, is designed to distract the Iranian people from the sinking economy and President Ahmadinejad's loss of power, blocked appointments, and criticism from even conservatives. In addition, rather than seeking support from the entire country, the president may be trying to outflank his conservative opponents, including many from the clergy, legislature, and ruling elite, who have become disenchanted with his anti‐corruption crusades, appointments, and policies. If successful, this plan would pit his country's conservative majority (including young people and the Revolutionary Guard) against the minority moderates and some disaffected conservatives. Finally, this article critiques other theories and suggested strategies responding to the crisis and offers its own diversionary theory, as well as ideas about how to handle President Ahmadinejad's oratories.
A Comparative Study of the Formulations and Benchmark Problems for the Topology Optimization of Compliant Mechanisms
Authors: Deepak Sangamesh R. , Dinesh M. , Sahu Deepak K. , Ananthasuresh G. K.
Published: April 2009

The topology optimization problem for the synthesis of compliant mechanisms has been formulated in many different ways in the past 15years, but there is not yet a definitive formulation that is universally accepted. Furthermore, there are two unresolved issues in this problem. In this paper, we present a comparative study of five distinctly different formulations that are reported in the literature. Three benchmark examples are solved with these formulations using the same input and output specifications and the same numerical optimization algorithm. A total of 35 different synthesis examples are implemented. The examples are limited to desired instantaneous output direction for prescribed input force direction. Hence, this study is limited to linear elastic modeling with small deformations. Two design parametrizations, namely, the frame element-based ground structure and the density approach using continuum elements, are used. The obtained designs are evaluated with all other objective functions and are compared with each other. The checkerboard patterns, point flexures, and the ability to converge from an unbiased uniform initial guess are analyzed. Some observations and recommendations are noted based on the extensive implementation done in this study. Complete details of the benchmark problems and the results are included. The computer codes related to this study are made available on the internet for ready access.
Design of Series-Elastic Actuators for Dynamic Robots With Articulated Legs
Authors: Curran Simon , Knox Brian T. , Schmiedeler James P. , Orin David E.
Published: April 2009

A series-elastic actuator (SEA) can provide remarkable performance benefits in a robotic system, allowing the execution of highly dynamic manuevers, such as a jump. While SEAs have been used in numerous robotic systems, no comprehensive understanding of an optimal design exists. This paper presents a new analytical basis for maximizing an SEA thrust performance for jumping from rest with an articulated leg. The analytical SEA model is validated with simulation and experimental results from a prototype leg. An SEA decouples the dynamic limitations of a dc motor actuator from the joint, allowing larger lift-off velocities than with a directly driven joint. A detailed analysis of the complex dynamic response of an SEA during the thrust phase leads to a new maximum impulse criterion, where motor speed is approximately half the no-load speed at the moment of peak motor torque. The analytical model and this proposed criterion are used to develop a simple equation for selecting SEA design parameters. Lastly, a novel unidirectional SEA design is presented that allows for accurate positioning of the leg during flight.
Cooperative Towing With Multiple Robots
Authors: Cheng Peng , Fink Jonathan , Kumar Vijay , Pang Jong-Shi
Published: April 2009

In this paper, we address the cooperative towing of payloads by multiple mobile robots that move in the plane. Robots are attached via cables to an object or a pallet carrying a payload, and they coordinate their motion to manipulate the payload through a planar warehouselike environment. We formulate a quasistatic model for manipulation and derive equations of motion that yield the motion of the payload for a prescribed motion of the robots in the presence of dry friction and tension constraints. We present the experimental results that demonstrate the basic concepts.
Discretely Deformable Surface Based on Mechanical Interpolation: Application to the Design of a Dynamically Reconfigurable Theater Stage
Authors: Jobin Jean-Philippe , Gosselin Clément
Published: April 2009

This paper presents the development of an active discretely deformable surface that makes use of mechanical interpolation in order to limit the number of required actuators. First, a planar interpolation mechanism is proposed and optimized in order to minimize the interpolation errors. Then a four-DOF spatial interpolation mechanism with the actuators in the corners is designed based on the planar mechanism. The kinematics of this mechanism are also derived. Finally, a prototype—built in order to illustrate the concept—is presented. The prototype consists of a small-scale dynamically reconfigurable stage for puppet theater performance, referred to as a Castelet. The prototype was used for the creation of two shows that clearly demonstrate the potential of the Castelet in theater performance as well as in other applications.
Static of Parallel Manipulators and Closeness to Singularity
Authors: Hubert J. , Merlet J.-P.
Published: April 2009

Singularity is a major problem for parallel robots as in these configurations the robot cannot be controlled, and there may be infinite forces/torques in its joints, possibly leading to a robot breakdown. In the recent years classification and detection of singularities have made large progress. However, the issue of closeness to a singularity is still open and we propose in this paper an approach that is based on a static analysis. Our measure of closeness to a singularity is based on the very practical issue of having the joint forces/torques lower than a given threshold. We consider a planar parallel robot whose end-effector has a constant orientation and is submitted to a known wrench and we show that it is possible to compute the border of the region that describes all possible end-effector location for which the joint forces are lower than the fixed threshold.
Reconfiguration of Spatial Metamorphic Mechanisms
Authors: Zhang Liping , Dai Jian S.
Published: April 2009

This paper investigates reconfiguration of metamorphic mechanisms as a typical character of topological change of the mechanisms. Metamorphic mechanisms with reconfigurable topology provide changed topological states and subsequently change the mobility to give various subphase mechanisms. This paper investigates the built-in spatial modules extended with metamorphic characteristics to develop a metamorphosis operation based on building blocks in the form of spatial kinematic pairs and associated links. The composition principle of a metamorphic mechanism gives the mechanism characteristics and generates subphase working mechanisms. These working mechanisms change and develop into different forms in an evolutionary process of topological change and the proposed module composition principle in metamorphic mechanisms leads to the development of module topology variation and reconfiguration operations based on algebraic properties of Lie displacement-subgroup. The topology transformation is further used for configuration aggregation and degeneration and all the linkage operations are based on set theoretic, leading to topological reconfiguration of metamorphic mechanisms that maps a source metamorphic mechanism into various subphase configurations. This paper demonstrates the principle with case studies from a metamorphic mechanism generator to subphase mechanisms and vice versa.
Whole Skin Locomotion Inspired by Amoeboid Motility Mechanisms
Authors: Hong Dennis W. , Ingram Mark , Lahr Derek
Published: April 2009

In this paper, a locomotion mechanism for mobile robots inspired by how single celled organisms use cytoplasmic streaming to generate pseudopods for locomotion is presented. Called the whole skin locomotion, it works by way of an elongated toroid, which turns itself inside out in a single continuous motion, effectively generating the overall motion of the cytoplasmic streaming ectoplasmic tube in amoebae. With an elastic membrane or a mesh of links acting as its outer skin, the robot can easily squeeze between obstacles or under a collapsed ceiling and move forward using all of its contact surfaces for traction, even squeezing itself through holes of a diameter smaller than its nominal width. Therefore this motion is well suited for search and rescue robots that need to traverse over or under rubble, or for applications where a robot needs to enter into and maneuver around tight spaces such as for robotic endoscopes. This paper summarizes the many existing theories of amoeboid motility mechanisms and examines how these can be applied on a macroscale as a mobile robot locomotion concept, illustrating how biological principles can be used for developing novel robotic mechanisms. Five specific mechanisms are introduced, which could be implemented to such a robotic system. Descriptions of an early prototype and the preliminary experimental and finite element analysis results demonstrating the feasibility of the whole skin locomotion strategy are also presented, followed by a discussion of future work.
Benefits of Active Compressor Stability Management on Turbofan Engine Operability
Authors: Liu Yuan , Dhingra Manuj , Prasad J. V. R.
Published: April 2009

Active compressor stability management can play a significant role in the intelligent control of gas turbine engines. The present work utilizes a computer simulation to illustrate the potential operability benefits of compressor stability management when actively controlling a turbofan engine. The simulation, called the modular aeropropulsion system simulation (MAPSS) and developed at NASA Glenn, models the actuation, sensor, controller, and engine dynamics of a twin-spool, low-bypass turbofan engine. The stability management system is built around a previously developed stability measure called the correlation measure. The correlation measure quantifies the repeatability of the pressure signature of a compressor rotor. Earlier work has used laboratory compressor and engine rig data to develop a relationship between a compressor’s stability boundary and its correlation measure. Specifically, correlation measure threshold crossing events increase in magnitude and number as the compressor approaches the limit of stable operation. To simulate the experimentally observed behavior of these events, a stochastic model based on level-crossings of an exponentially distributed pseudorandom process has been implemented in the MAPSS environment. Three different methods of integrating active stability management within the existing engine control architecture have been explored. The results show that significant improvements in the engine emergency response can be obtained while maintaining instability-free compressor operation via any of the methods studied. Two of the active control schemes investigated utilize existing scheduler and controller parameters and require minimal additional control logic for implementation. The third method, while introducing additional logic, emphasizes the need for as well as the benefits of a more integrated stability management system.
Combustion Characteristics of a Can Combustor With a Rotating Casing for an Innovative Micro Gas Turbine
Authors: Shih Hsin-Yi , Liu Chi-Rong
Published: April 2009

A can type combustor with a rotating casing for an innovative micro gas turbine has been modeled, and the combustion characteristics were investigated. The simulations were performed using commercial code STAR-CD, in which a three-dimensional compressible k-ε turbulent flow model and a one-step overall chemical reaction between methane/air were used. The results include the detailed flame structure at different rotation speeds of outside casing, ranging from stationary to the maximum speed of 58,000 rpm of the design point. The airflows are baffled when entering the combustor through the linear holes due to the centrifugal force caused by the rotating casing, and the inlet flow angle is inclined. When the rotation is in the opposite direction of the swirling flows driven by the designed swirler, a shorter but broader recirculation zone and a concave shape flame are found at a higher rotating speed. At maximum rotating speed, the swirling flows are dominated by the rotating flows caused by the casing, especially downstream of the combustor. The combustor performance was also analyzed, indicating a higher combustion efficiency and higher exit temperature when the casing rotates, which benefits the performance of the gas turbine, but the cooling and possible hot spots for turbines are the primary concerns.
Pantopteron: A New Fully Decoupled 3DOF Translational Parallel Robot for Pick-and-Place Applications
Authors: Briot S. , Bonev I. A.
Published: April 2009

In this paper, a novel 3DOF fully decoupled translational parallel robot, called the Pantopteron, is presented. This manipulator is similar to the Tripteron Cartesian parallel manipulator, but due to the use of three pantograph linkages, an amplification of the actuator displacements is achieved. Therefore, equipped with the same actuators, the mobile platform of the Pantopteron moves many times faster than that of the Tripteron. This amplification is defined by the magnification factor of the pantograph linkages. The kinematics, workspace, and constraint singularities of the proposed parallel robot are studied in detail. Design considerations are also discussed, and a possible prototype is illustrated.
Stiffness Modeling of the Tricept Robot Using the Overall Jacobian Matrix
Authors: Wang Youyu , Liu Haitao , Huang Tian , Chetwynd Derek G.
Published: April 2009

Taking the 3DOF parallel mechanism within the Tricept robot as an example, this paper presents an analytical approach for the stiffness modeling of parallel kinematic machines having a properly constrained passive limb. The stiffness model is formulated using the 6×6overall Jacobian. It takes particular interest in the precise formulation of the bending stiffness matrix of the properly constrained passive limb by considering the compatibility conditions of the system. Stiffness evaluation of a sample Tricept robot is carried out using two global indices obtained from singular value decomposition of the compliance matrix.
Type Synthesis of
Linkage-Driven Self-Adaptive Fingers
Authors: Birglen Lionel
Published: April 2009

This paper aims at providing a method to synthesize mechanical architectures of self-adaptive robotic fingers driven by linkages. Self-adaptive mechanisms are used in robotic fingers to provide the latter with the ability to adjust themselves to the shape of the object seized without any dedicated electronics, sensor, or control. This type of mechanisms has been known for centuries but the increased capabilities of digital systems have kept them in the shadows. Recently, because of the lack of commercial and industrial success of complex robotic hands, self-adaptive mechanisms have attracted much more interest from the research community and several prototypes have been built. Nevertheless, only a handful of prototypes are currently known. It is the aim of this paper to present a methodology that is able to generate thousands of self-adaptive robotic fingers driven by linkages with two and three phalanges. First, potential kinematic architectures are synthesized using a well-known technique. Second, the issue of proper actuation and passive element(s) selection and location is addressed.
Triangle Pseudocongruence in Constraint Singularity of Constant-Velocity Couplings
Authors: Milenkovic Paul
Published: April 2009

Congruent triangles establish that a class of intersecting-shaft couplings is constant velocity. These mechanisms employ a pair of linkages in parallel: a spherical joint at the intersection of the shafts and the intersection of straight-line tracks away from the shaft center to transmit rotation. A proof of constant velocity follows from the congruence of an initial pair of triangles with two matching sides and one excluded angle. This side-side-angle (SSA) condition is a pseudocongruence because it allows two different values for the included angle, indicating that such shaft couplings have symmetric and skewed assembly configurations. If the other excluded angle happens to be 90 deg, the SSA condition guarantees congruence because there is a single solution for the included angle. The 90 deg condition, however, occurs at a posture with a constraint singularity, where the shaft coupling is unable to transmit torque. Motion screw analysis establishes the same geometric condition for a coupling based on a revolute-spherical-revolute Clemens linkage. An upper bound on shaft deflection imposed by hyperextension of that linkage, along with a bound on deflection where constraint singularity occurs, identifies couplings where the constraint singularity can occur within the physical limits.
Influence of Film-Hole Shape and Angle on Showerhead Film Cooling Using PSP Technique
Authors: Gao Zhihong , Han Je-Chin
Published: April 2009

The effect of film-hole geometry and angle on turbine blade leading edge film cooling has been experimentally studied using the pressure sensitive paint technique. The leading edge is modeled by a blunt body with a semicylinder and an after-body. Two film cooling designs are considered: a heavily film cooled leading edge featured with seven rows of film cooling holes and a moderately film cooled leading edge with three rows. For the seven-row design, the film holes are located at 0 deg (stagnation line), ±15 deg, ±30 deg, and ±45 deg on the model surface. For the three-row design, the film holes are located at 0 deg and ±30 deg. Four different film cooling hole configurations are applied to each design: radial angle cylindrical holes, compound angle cylindrical holes, radial angle shaped holes, and compound angle shaped holes. Testing was done in a low speed wind tunnel. The Reynolds number, based on mainstream velocity and diameter of the cylinder, is 100,900. The mainstream turbulence intensity is about 7% near of leading edge model and the turbulence integral length scale is about 1.5 cm. Five averaged blowing ratios are tested ranging from M=0.5 to M=2.0. The results show that the shaped holes provide higher film cooling effectiveness than the cylindrical holes, particularly at higher average blowing ratios. The radial angle holes give better effectiveness than the compound angle holes at M=1.0–2.0. The seven-row film cooling design results in much higher effectiveness on the leading edge region than the three-row design at the same average blowing ratio or same amount coolant flow.
Comparative Radial Heat Flow Method for Thermal Conductivity Measurement of Liquids
Authors: Iyengar Ananth S. , Abramson Alexis R.
Published: April 2009

A steady state thermal conductivity measuring setup based on the comparative radial heat flow method is presented. The setup consists of a pair of coaxial cylinders as its main components, with test fluid placed in the annular space between these cylinders with water tight cover plates at the top and bottom of the cylinders. Experiment involves heating the coil at the concentric-center of the inner cylinder; steady state data are acquired for the calculation of the thermal conductivity. Thermal conductivity is calculated by comparing the radial heat flow between the cylinders and the test fluid (comparative method). Thermal conductivity of water, glycerol, and ethylene glycol was measured for varying temperatures and is in good agreement with the published thermal conductivity values in literature.
The Impact of Normal Magnetic Fields on Instability of Thermocapillary Convection in a Two-Layer Fluid System
Authors: Huang Hulin , Zhou Xiaoming
Published: April 2009

When a temperature gradient is imposed along a liquid-liquid interface, thermocapillary convection is driven by the surface tension gradient. Such flow occurs in many application processes, such as thin-film coating, metal casting, and crystal growth. In this paper, the effect of a normal magnetic field, which is perpendicular to the interface, on the instability of thermocapillary convection in a rectangular cavity with differentially heated sidewalls, filled with two viscous, immiscible, incompressible fluids, is studied under the absence of gravity. In the two-layer fluid system, the upper layer fluid is electrically nonconducting encapsulant B2O3, while the underlayer fluid is electrically conducting molten InP. The interface between the two fluids is assumed to be flat and nondeformable. The results show that the two-layer fluid system still experiences a wavelike state when the magnetic field strength Bz is less than 0.04 T. The wave period increases and the amplitude decreases with the increasing of magnetic field strength. However, the convective flow pattern becomes complicated with a variable period, while the perturbation begins to fall into oblivion as the magnetic field intensity is larger than 0.05 T. When Bz=0.1 T, the wavelike state does not occur, the thermocapillary convection instability is fully suppressed, and the unsteady convection is changed to a steady thermocapillary flow.
Experimental Investigation of Radiation Effects on Natural Convection in Horizontal Channels Heated From Above
Authors: Manca Oronzio , Nardini Sergio
Published: April 2009

Radiation heat transfer affects natural convection of air inside an open-ended cavity with a heated horizontal upper plate and an unheated lower parallel plate. Its effect is the heating of the lower plate, which heats the adjacent fluid layer and could determine secondary motions. In this paper, an experimental study is carried out to describe the effect of high value of surface emissivity on air flow in an open-ended cavity. The investigation is performed by means of wall temperature profiles, smoke visualization, and air temperature measurements. Results are obtained for an emissivity of the horizontal plates equal to 0.8, for aspect ratios between 10.0 and 20.0. By means of flow visualization and local air temperature measurements in the cavity as a function of time, remarkable secondary motions in the cavity are observed for the highest considered surface heat flux (Ra=8.91×103, 6.45×104, and 1.92×105). Measurement of the air temperature in the cavity also shows that radiation causes and damps secondary motions at the same time. Mean air temperature profiles as a function of the vertical coordinate, at different locations along the longitudinal axis, confirm both the main flow path inside the cavity and radiation effect on convective heat transfer. Finally, correlations for average Nusselt numbers and dimensionless maximum wall temperatures, in terms of Rayleigh number and channel aspect ratio, are proposed for natural convection with or without radiative heat transfer contribution for 2.26×103≤Ra≤1.92×105 and 10≤2L/b≤20.
Analysis of Instantaneous Turbulent Velocity Vector and Temperature Profiles in Transitional Rough Channel Flow
Authors: Afzal Noor
Published: April 2009

The instantaneous velocity vector and instantaneous temperature in a turbulent flow in a transitionally rough channel have been analyzed from unsteady Navier–Stokes equations and unsteady thermal energy equation for large Reynolds numbers. The inner and outer layers asymptotic expansions for the instantaneous velocity vector and instantaneous temperature have been matched in the overlap region by the Izakson–Millikan–Kolmogorov hypothesis. The higher order effects and implications of the intermediate (or meso) layer are analyzed for the instantaneous velocity vector and instantaneous temperature. Uniformly valid solutions for instantaneous velocity vector have been decomposed into the mean velocity vector, and fluctuations in velocity vector, as well as the instantaneous temperature, have been decomposed into mean temperature and fluctuations in temperature. It is shown in the present work that if the mean velocity vector in the work of Afzal (1976, “Millikan Argument at Moderately Large Reynolds Numbers,” Phys. Fluids, 16, pp. 600–602) is replaced by instantaneous velocity vector, we get the results of Lundgren (2007, “Asymptotic Analysis of the Constant Pressure Turbulent Boundary Layer,” Phys. Fluids, 19, pp. 055105) for instantaneous velocity vector. The comparison of the predictions for momentum and thermal mesolayers is supported by direct numerical simulation (DNS) and experimental data.
Large-Eddy Simulation of Turbulence-Radiation Interactions in a Turbulent Planar Channel Flow
Authors: Gupta Ankur , Modest Michael F. , Haworth Daniel C.
Published: April 2009

Large-eddy simulation (LES) has been performed for planar turbulent channel flow between two infinite, parallel, stationary plates. The capabilities and limitations of the LES code in predicting correct turbulent velocity and passive temperature field statistics have been established through comparison to direct numerical simulation data from the literature for nonreacting cases. Mixing and chemical reaction (infinitely fast) between a fuel stream and an oxidizer stream have been simulated to generate large composition and temperature fluctuations in the flow; here the composition and temperature do not affect the hydrodynamics (one-way coupling). The radiative transfer equation is solved using a spherical harmonics (P1) method, and radiation properties correspond to a fictitious gray gas with a composition- and temperature-dependent Planck-mean absorption coefficient that mimics that of typical hydrocarbon-air combustion products. Simulations have been performed for different optical thicknesses. In the absence of chemical reactions, radiation significantly modifies the mean temperature profiles, but temperature fluctuations and turbulence-radiation interactions (TRI) are small, consistent with earlier findings. Chemical reaction enhances the composition and temperature fluctuations and, hence, the importance of TRI. Contributions to emission and absorption TRI have been isolated and quantified as a function of optical thickness.
The Air-Side Thermal-Hydraulic Performance of Flat-Tube Heat Exchangers With Louvered, Wavy, and Plain Fins Under Dry and Wet Conditions
Authors: Park Young-Gil , Jacobi Anthony M.
Published: April 2009

The air-side thermal-hydraulic performance of flat-tube aluminum heat exchangers is studied experimentally for conditions typical to air-conditioning applications, for heat exchangers constructed with serpentine louvered, wavy, and plain fins. Using a closed-loop calorimetric wind tunnel, heat transfer and pressure drop are measured at air face velocities from 0.5 m/s to 2.8 m/s for dry- and wet-surface conditions. Parametric effects related to geometry and operating conditions on heat transfer and friction performance of the heat exchangers are explored. Significant differences in the effect of geometrical parameters are found for dry and wet conditions. For the louver-fin geometry, using a combined database from the present and the previous studies, empirical curve-fits for the Colburn j- and f-factors are developed in terms of a wet-surface multiplier. The wet-surface multiplier correlations fit the present database with rms relative residuals of 21.1% and 24.4% for j and f multipliers, respectively. Alternatively, stand-alone Colburn j and f correlations give rms relative residuals of 22.7% and 29.1%, respectively.
Solid-State Thermal Rectification With Existing Bulk Materials
Authors: Dames C.
Published: April 2009

A two-terminal thermal device exhibits thermal rectification if it transports heat more easily in one direction than in the reverse direction. Within the framework of classical heat conduction by Fourier’s law, thermal rectification occurs in a two-segment bar if the thermal conductivities of the segments have different dependencies on temperature. The general solution to this problem is a pair of coupled integral equations, which in previous work had to be solved numerically. In this work the temperature dependencies of the thermal conductivities are approximated using power laws, and perturbation analysis at low thermal bias leads to a simple algebraic expression, which shows that the rectification is proportional to the difference in the power-law exponents of the two materials, multiplied by a geometric correction function. The resulting predictions have no free parameters and are in good agreement with the experimental results from the literature. For maximum rectification, the thermal resistances of the two segments should be matched to each other at low thermal bias. For end point temperatures of 300 K and 100 K, using common bulk materials it is practical to design a rectifier with rectification of well over one hundred percent. A new quantity, the normalized thermal rectification, is proposed to better facilitate comparisons of various rectification mechanisms across different temperature ranges.
Microscale Temperature Measurements Near the Triple Line of an Evaporating Thin Liquid Film
Authors: Dhavaleswarapu Hemanth K. , Garimella Suresh V. , Murthy Jayathi Y.
Published: April 2009

Thin-film evaporation from a meniscus in a confined space, which is the basis for many two-phase cooling devices, is experimentally investigated. The meniscus formed by heptane, a highly wetting liquid, on a heated fused quartz wafer is studied. Microscale infrared temperature measurements performed near the thin-film region of the evaporating meniscus reveal the temperature suppression caused by the intensive evaporation in this region. The high spatial resolution (∼6.3 μm) and high temperature sensitivity (∼20 mK) of the infrared camera allow for improved accuracy in the measurements. The effects of evaporation rate, applied heat flux, and channel width on the thin-film heat transfer distribution are also explored.
Experimental Study and Genetic-Algorithm-Based Correlation on Pressure Drop and Heat Transfer Performances of a Cross-Corrugated Primary Surface Heat Exchanger
Authors: Wang Qiu-Wang , Zhang Dong-Jie , Xie Gong-Nan
Published: April 2009

Heat transfer and pressure drop characteristics of a cross-corrugated (CC) primary surface heat exchanger with different CC passages (P/H=2, θ=60 and 120 deg, called CC2-60 and CC2-120, respectively) in two air sides have been experimentally investigated in this study. It is shown that the corrugation angle (θ) and the ratio of the wavelength P to height H(P/H) are the two key parameters of CC passages to influence the heat transfer and flow friction performances. The heat transfer and friction factor correlations for these two configurations are also obtained with Reynolds numbers ranging from Re=450–5500(CC2-60) and Re=570–6700(CC2-120). At a certain P/H, the Nusselt number, Nu, and the friction factor, f, are affected by the corrugation angle, θ. The heat transfer performance of CC2-120 are much better than that of CC2-60 while the pressure drop of the former is higher than that of the latter, especially at high Reynolds numbers region. The critical Reynolds numbers at which the flow mode transits from laminar to turbulent in the two different passages are also estimated. Furthermore, in this study a genetic algorithm (GA) has been used to determine the coefficients of heat transfer correlations by separation of total heat transfer coefficient without any information of measured wall temperatures. It is concluded that the GA-based separated heat transfer Nusselt number provides a good agreement with the experimental data; the averaged relative deviation by GA (1.95%) is lower than that by regression analysis (2.84%). The inversely yielding wall temperatures agree well with the measured data in turn supporting the reliability of experimental system and measurements. It is recommended that GA techniques can be used to handle more complicated problems and to obtain both-side heat transfer correlations simultaneously, where the conventional Wilson-plot method cannot be applied.