Estimation of the Flexural States of a Macro–Micro Manipulator Using Point-Acceleration Data

The work reported here was motivated by the development of manipulator systems comprising one long-reach, flexible-link subsystem, termed the macromanipulator, and a short-reach, rigid-link subsystem, called the micromanipulator. The flexural states of the macromanipulator, needed for controlling such systems effectively, are not usually measurable directly. For this reason, a state-estimation algorithm is proposed which uses the velocity and angular-velocity data of the micromanipulator base to estimate the flexural states of the macromanipulator. The velocity data are inferred from the acceleration signals delivered by a kinematically redundant set of triaxial accelerometers. The accelerometer signals are also utilized to calculate the translational and angular accelerations of the micromanipulator base, which are, in turn, used along with the dynamics equations of the micromanipulator to obtain the reaction force and moment acting between the two subsystems. Treating the force and the moment as inputs, the dynamics equations of the macromanipulator alone are used in the observer, thus reducing the order of the dynamics model. The state–output relations, on the other hand, are linearized in closed form to lower the computational cost. The relations thus obtained are then used in an extended Kalman filter to estimate the flexural states of the system.     

Application of an Equilibrium Model for an Electrified Fluid Interface—Electrospray Using a PDMS Microfluidic Device

An experimental investigation of an electrified fluid interface is presented. The experimental findings are related to a previously developed analytical model of Gubarenko , which is used to determine when a fluidic interface under electrical stress is in equilibrium, and to observations reported in the literature. The effect of key parameters on causing the interface to rupture, form, and maintain an electrospray is investigated. The experimental results reveal the dependence of interface shape on operational parameters, the impact of the interface apex angle on equilibrium, the conditions that cause either dripping mode or cone-jet mode, and the structure of operational domains. This paper confirms predictions made using the analytical model, including the range of parameters that cause the onset and steadiness of a quasi-equilibrium (electrospray) state of the interface. Testing is performed using an electrospray emitter chip fabricated from two layers of Polydimethylsiloxane and one layer of glass. The model and experimental results assist in design decisions for electrospray emitters. Applications of electrified interfaces (electrosprays) are found in mass spectrometry, microfluidics, material deposition, and colloidal thrusters for propulsion.$hfill$[2008-0074]      

Robustly Stable Adaptive Control of a Tandem of Master–Slave Robotic Manipulators With Force Reflection by Using a Multiestimation Scheme

The problem of controlling a tandem of robotic manipulators composing a teleoperation system with force reflection is addressed in this paper. The final objective of this paper is twofold: 1) to design a robust control law capable of ensuring closed-loop stability for robots with uncertainties and 2) to use the so-obtained control law to improve the tracking of each robot to its corresponding reference model in comparison with previously existing controllers when the slave is interacting with the obstacle. In this way, a multiestimation-based adaptive controller is proposed. Thus, the master robot is able to follow more accurately the constrained motion defined by the slave when interacting with an obstacle than when a single-estimation-based controller is used, improving the transparency property of the teleoperation scheme. The closed-loop stability is guaranteed if a minimum residence time, which might be updated online when unknown, between different controller parameterizations is respected. Furthermore, the analysis of the teleoperation and stability capabilities of the overall scheme is carried out. Finally, some simulation examples showing the working of the multiestimation scheme complete this paper.     

Oriented and Vectorial Patterning of Cardiac Myocytes Using a Microfluidic Dielectrophoresis Chip—Towards Engineered Cardiac Tissue With Controlled Macroscopic Anisotropy

Recently, the ability to create engineered heart tissues with a preferential cell orientation has gained much interest. Here, we present a novel method to construct a cardiac myocyte tissue-like structure using a combination of dielectrophoresis and electro-orientation via a microfluidic chip. The device includes a top home-made silicone chamber containing microfluidic channels and bottom integrated microelectrodes which are patterned on a glass slide to generate dielectrophoresis force and orientation torque. Using the interdigitated-castellated microelectrodes, the induction of a mutually attractive dielectrophoretic force between cardiac myocytes can lead to cells moving close to each other and forming a tissue-like structure with orientation along the alternating current (ac) electric field between the microelectrode gaps. Both experiments and analysis indicate that a large orientation torque and force can be achieved by choosing an optimal frequency around 2 MHz and decreasing the conductivity of medium to a relatively low level. Finally, electromechanical experiments and biopolar impedance measurements were performed to demonstrate the structural and functional anisotropy of electro-oriented structure     

A comparison of “fast” capacity planning methodologies in application to a health care facility

This paper compares the use of four “fast” capacity planning techniques to estimate requirements in a critical health care facility, a surgical intensive care unit (SICU). Each of the techniques is described, models applicable to the SICU facility are developed and indices which estimate performance are calculated. The crucial issue addressed is estimation of the relative level of service that a facility design will afford patients. Results indicate relative utility of the techniques in facility planning.     

Comment on “On Siphon Computation for Deadlock Control in a Class of Petri Nets”

It was claimed recently in the paper by Li and Zhou that ldquoa polynomial time algorithm for finding the set of elementary siphons in S³PRs is proposed, which avoids complete siphon enumerationrdquo. However, this is incorrect because Proposition 1 and Corollary 6 of the aforementioned paper, which lead to the claim, are both incorrect. In this correspondence paper, Proposition 1 and Corollary 6 are disproved. As a consequence, some claims of the aforesaid paper are denied. Two examples are presented to disprove some claims of the previously mentioned paper.     

“Epidemic in Switzerland”: Description of a Strategic Leadership Exercise by the Swiss Government

On January 20, 2005, a national strategic leadership exercise was held in Switzerland. The theme being the first day response to an epidemic outbreak. Special attention was paid to cooperation and coordination among the various federal departments, the definition of responsibilities within the leadership organisation, and the level of information and communication that served the leadership process, and how these elements played out under time pressure, during a crisis situation and within a federal and international setting. The evaluation of this exercise concludes that short term crisis management could be considered as adequate but strategic decision making was mostly absent. The value of this large scale exercise is considered positive for the preparation on crisis management because of heightened political attention which for example is visible in the swift implementation of the recommendations of the evaluation.     

Retraction of “Using ergonomic digital human modeling in evaluation of workplace design and prevention of workrelated musculoskeletal disorders onboard small fishing vessel”

The following article from Human Factors and Ergonomics in Manufacturing & Service Industries, “Using ergonomic digital human modeling in evaluation of workplace design and prevention of workrelated musculoskeletal disorders onboard small fishing vessel,” by Enrique Álvarez‐Casado, Bing Zhang, Sonia Tello Sandoval and Mondelo Pedro, published online on October 11, 2011 in Wiley Online Library ( www.onlinelibrary.wiley.com ), has been retracted by agreement between the authors, the journal Editors‐in‐Chief, Waldemar Karwowski and Gavriel Salvendy, and Publisher Wiley Periodicals, Inc. The retraction has been agreed as these articles were mistakenly published after being rejected.     

Numerical studies of “side-by-side” and other modes for the Taylor problem in a finite annulus

A numerical scheme for solving the Navier-Stokes equations for axisymmetric flow in a Couette apparatus is presented. It is time-dependent, and uses primitive variables with finite-differencing on a stretched, staggered grid. The model gives good agreement with the experiments. Anomalous modes have been found and are initially established by a technique in which Schaeffer's [1] end-wall boundary conditions are used to set up a steady state, and then the boundary conditions are gradually changed to those of the finite-length, Taylor apparatus. When both the inner and outer walls of the annulus rotate, a new class of “side-by-side” modes is predicted.     

The positive and negative implications of anonymity in Internet social interactions: “On the Internet, Nobody Knows You’re a Dog”

The growth of the Internet at a means of communication has sparked the interest of researchers in several fields (e.g. communication, social psychology, industrial-organizational psychology) to investigate the issues surrounding the expression of different social behaviors in this unique social context. Of special interest to researchers is the increased importance that anonymity seems to play in computer-mediated communication (CMC). This paper reviews the literature related to the issues of anonymity within the social context, particularly in CMC, demonstrating the usefulness of established social psychological theory to explain behavior in CMC and discussing the evolution of the current theoretical explanations in explaining the effects of anonymity in social behavior in CMC environments. Several suggestions for future research are proposed in an attempt to provide researchers with new avenues to investigate how anonymity can play both positive and negative roles in CMC.     

Comments on the erratum to “The spatial and temporal consolidation of returned products in a closed-loop supply chain network” [Comput. Ind. Eng. 51 (2006) 309–320]

A genetic algorithm based mixed-integer; non-linear programming model proposed by Min et al. [Min, H., Ko, C. S., & Ko, H. J. (2006). The spatial and temporal consolidation of returned products in a closed-loop supply chain network. Computers & Industrial Engineering, 51, 309–320] was recently published in Computers & Industrial Engineering journal to solve the reverse logistics problem involving both spatial and temporal consolidation of returned products. In this work, comments and suggestions are given to the recently published model of Min et al. (2006). The comments like centralized return center location, maximum allowable distance between customers and the initial collection point, calculation of transportation cost and finally, the modification of the objective function are suggested in this work.     

‘There was a lot of learning going on’ Using a digital medium to support learning in a professional course for new HE lecturers

This small scale action research study investigated the experiences of learners over two iterations as they completed a patchwork text assignment within the digital medium of a personal learning system (PLS). The aim was to investigate the extent to which using a PLS can facilitate formative and collaborative feedback to assist student learning. A secondary question, linked to the course being a post graduate Certificate for new HE teachers within a geographically dispersed university, was to examine if using a PLS in the programme would influence their interest in using it with their own students in the future. This question is of particular importance for the tutors of this programme, as the university attracts mainly part-time students who are studying at a distance from the university campus. The study was carried out as part of the JISC funded Flourish Project, whose overall aim was to examine the use of a PLS to support the development of academic staff.     

Comments on “Viscoelastic studies of human subscapularis tendon: Relaxation test and a Wiechert model” by C. Machiraju, A.V. Phan, A.W. Pearsall, S. Madanagopal, Computer Methods and Programs in Biomedicine (2006)

Referring to the approach for determining the material parameters for a Wiechert model of the human subscapularis tendon proposed by Machiraju et al. [C. Machiraju, A.V. Phan, A.W. Pearsall, S. Madanagopal, Viscoelastic studies of a human subscapularis tendon: relaxation test and a Wiechert model, Computer Methods and Programs in Biomedicine (2006), doi:10.1016/j.cmpb.2006.05.004], some comments are made on the basis of the result of an alternative method that is capable of giving more reasonable values for the Wiechart model with the fitting discrepancies minimized by a multi-variable optimization strategy.