Lag-Stabilized Force Feedback Damping

A lag-stabilized, force feedback controller for damping initial and residual oscillations of a planar, cantilevered flexible arm has been analytically developed and experimentally implemented on a commercial robot. The controller feeds back force sensor measurements that are delayed in time and proportional to the displacement (angular orientation) of the arm in order to damp the oscillation. As a result of the lag (contrary to popular belief), the controlled robot system is stable and provides tunable performance on a Cincinnati Milacron T3-786 robot.     

Collective plume tracing: A minimal information approach to collective control

A team of simple robots are used to trace a chemical plume to its source in order to find buried landmines. The goal of this paper is to analyze and design ‘emergent’ behaviors to enable the team of simple robots to perform plume tracing with the assistance of information theory. The first step in the design process is to define a fundamental trade‐off for collective systems between processing, memory, and communications for each robot in order to execute the desired collective behaviors. The baseline problem is to determine the minimum values for processing, memory, and communications simultaneously. This will enable the designer to determine the required information flow and how effectively the information resources are being utilized in collective systems. The solution to this baseline problem is an 8‐bit processor, no memory, and three words to communicate. The details of this solution are described in this paper. The second step is to extend the previous kinematic solution to a more general Hamiltonian‐based solution to develop a Fisher Information Equivalency. The Fisher Information Equivalency leads directly to necessary and sufficient conditions for stability and control of nonlinear collective systems via physical and information exergy flows. In particular, the creation of a ‘virtual/information potential’ by the team of robots via the decentralized distributed networked sensors produces a direct relationship between proportional feedback control, stored exergy in the system, and Fisher Information. This nonlinear stability formulation through Fisher Information directly provides an optimization problem to ‘tune’ the performance of the team of robots as a function of required information resources. Copyright © 2009 John Wiley & Sons, Ltd.     

Cognitive-Behavioral Analysis System of Psychotherapy as a Maintenance Treatment for Chronic Depression.

Although the efficacy of maintenance pharmacotherapy for the prevention of recurrence in major depressive disorder (MDD) is well documented, few studies have tested the efficacy of psychotherapy as a maintenance treatment. The authors examined the efficacy of the cognitive-behavioral analysis system of psychotherapy (CBASP) as a maintenance treatment for chronic forms of MDD. Eighty-two patients who had responded to acute and continuation phase CBASP were randomized to monthly CBASP or assessment only for 1 year. Significantly fewer patients in the CBASP than assessment only condition experienced a recurrence. The 2 conditions also differed significantly on change in depressive symptoms over time. These findings support the use of CBASP as a maintenance treatment for chronic forms of MDD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Designing Stable Finite State Machine Behaviors Using Phase Plane Analysis and Variable Structure Control

This paper discusses how phase plane analysis can be used to describe the overall behavior of single and multiple autonomous robotic vehicles with finite state machine rules. The importance of this result is that we can begin to design provably stable group behaviors from a set of simple control laws and appropriate switching points with decentralized variable structure control. The ability to prove stable group behavior is especially important for applications such as locating military targets or land mines. In this paper, we demonstrate how phase plane analysis has been used to explain the behavior of a 16 cm³ autonomous line-tracking robot with four finite states. After which, the analysis is extended to include the design of a decentralized variable structure controller that guides multiple vehicles to a goal while avoiding each other.     

Effects of Induced Vibrations on Early Age Concrete

The purpose of this investigation was to conduct a laboratory test program on how much induced vibrations on concrete during the period between initial set and final set affect the attainable strength of concrete. To achieve this purpose, a laboratory test program was conducted. The laboratory program consisted of casting 144 76?mm by 152?mm (3×6?in.) concrete cylinders and subjecting them to one of two levels of vibration for either 1 or 2?min at five different ages ranging in time from before, during, and after the setting period for the concrete. The levels of vibration correspond to typical frequencies of vibratory soil compactors and the peak particle velocity produced by the compactors. Both compression and splitting tensile tests were performed. The results of the laboratory study indicate that vibratory soil compaction should not be considered a significant hazard to foundation strength as long as the vibrations are within the limits in this study.     

Pulmonary function in horses with recurrent airway obstruction after aerosol and parenteral administration of beclomethasone dipropionate and dexamethasone, respectively

OBJECTIVE: To determine changes in clinical signs of disease and response to pulmonary function testing in horses with recurrent airway obstruction (heaves) after aerosol and parenteral administration of beclomethasone dipropionate and dexamethasone, respectively. ANIMALS: 6 horses with inducible and reversible heaves. PROCEDURE: Episodes of heaves were induced by exposure (challenge) to moldy hay and straw for 7 days. Horses were assigned to treatment groups (aerosolized beclomethasone dipropionate, parenterally administered dexamethasone, aerosolized propellant [control]), and respiratory frequency and subjective assessment of respiratory effect were determined twice daily. Maximal change in pleural pressure (delta-Pplmax), pulmonary resistance (RL), and dynamic compliance (Cdyn) was determined on days 0, 7, 10, 14, and 21. RESULTS: The RL and delta Pplmax were increased, and Cdyn was decreased in all horses in response to natural challenge. Beclomethasone reduced RL on day 10, reduced delta Pplmax on days 14 and 21 and increased Cdyn on day 14. Dexamethasone reduced RL and delta Pplmax on days 10, 14, and 21 and increased Cdyn on days 10 and 14. Respiratory effort (subjective assessment) improved after 2 and 3 days of beclomethasone and dexamethasone administration but rebounded to pretreatment values 1 and 3 days after discontinuation of drugs. CONCLUSIONS: Pulmonary function testing responses and clinical signs of airway obstruction were improved by administration of beclomethasone. The magnitude of response to aerosolized beclomethasone generally was less marked than the response to parenterally administered dexamethasone. Higher or more frequent dosing of aerosolized beclomethasone may be necessary to achieve the anti-inflammatory response to parenterally administered dexamethasone.     

Preinjury Personality Traits and the Prediction of Early Neurobehavioral Symptoms Following Mild Traumatic Brain Injury.

Objective: To determine if preinjury personality predicts early outcome in mild traumatic brain injury (MTBI) compared with orthopedic injury (OI). Study Design: Participants and significant others (SO) completed preinjury personality and early postinjury symptom questionnaires. Setting: Inpatient hospital and outpatient follow-up. Subjects: Eighty-seven people with MTBI and 82 with OI. Outcome Measures: NEO Personality Inventory-Revised (NEO-PI-R); Neurobehavioral Functioning Inventory (NFI). Results: Personality ratings and symptom endorsement were within normal limits. Concordance between self- and SO ratings was moderate (r≥.50). In both groups, there were very modest associations between preinjury personality and early symptoms. Significant effects were primarily due to overlapping item content between the personality and symptom questionnaires. Conclusions: Preinjury personality holds limited predictive value for MTBI outcome. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Treatment of hydrodynamic effects for toroidal containment vessels

Hydrodynamic effects in liquid-shell systems may be characterized in terms of structural degrees of freedom alone if an ideal fluid is assumed. The hydrodynamic effects are modeled by means of a consistent (full) added mass matrix which is obtained via finite element methods. The procedure is demonstrated for the case of a nuclear reactor toroidal containment vessel partially filled with water. Results demonstrate the superiority of this method over diagonal added mass procedures, such as the tributary area method.