Results 111 to 120 of about 157,311 (159)
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On the dynamic nature of positional information
BioEssays, 2006Morphogenetic fields are among the most fundamental concepts of embryology. However, they are also among the most ill-defined, since they consist of dynamic regulatory processes whose exact nature remains elusive. In order to achieve a more rigorous definition of a developmental field, Lewis Wolpert introduced the concept of positional information ...
Johannes, Jaeger, John, Reinitz
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Positive controllability of positive dynamical systems
Proceedings of the 2002 American Control Conference (IEEE Cat. No.CH37301), 2002The paper is devoted to a study of constrained controllability and controllability for linear dynamical systems if the controls are taken to be nonnegative. In analogy to the usual definition of controllability it is possible to introduce the concept of positive controllability. We concentrate on approximate positive controllability for linear infinite-
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A Note on Positive Dynamic Programming
Mathematics of Operations Research, 1986This note considers total reward Markov decision processes with countable state space. For these models it is well known that in the positive case, i.e. the immediate reward function is nonnegative, without further conditions (1) the value iteration holds and (2) there exist pointwise good stationary strategies.
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Exploring the dynamic measurement of position
Proceedings. Sixth International Symposium on Wearable Computers,, 2003This paper describes the development of several methods for the dynamic measurement of error distribution for positioning systems. When a user moves along a path at an unknown speed, it is no longer feasible to calculate the distance between the measured and real positions. We outline three applications using different positioning systems and apply our
Randell, CN, Muller, HL
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On the dynamics of piezoactuated positioning systems
Review of Scientific Instruments, 2008Piezoelectric actuators (PEAs) are commercially available for producing extremely small displacements. If a PEA is used to drive a positioning mechanism, the combined dynamics is approximated empirically by that of a second-order system. However, the rationale for such an approximation is lacking in the literature, thus leaving some issues unaddressed,
X B, Chen +3 more
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Dynamic Positional Deformity of the Hallux
The Journal of Foot and Ankle Surgery, 2014The present study reports a case with concomitant tethering of the flexor tendon and extensor tendon of the hallux after closed tibiofibular shaft fractures. We have obtained good clinical results using tenotomy of the flexor hallucis longus tendon and Z-plasty lengthening of the extensor hallucis longus tendon.
Byung-Ki, Cho +5 more
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A framework for dynamic position determination
Proceedings of the 6th International Conference on Mobile Technology, Application & Systems - Mobility '09, 2009This paper presents a brief survey of typical examples of systems in the field of position determination and identifies a need for a further research. This is followed by a description of a managed positioning environment for indoor and outdoor surroundings, in which accuracy and precision can be improved by using a mix of fixed sensors and the sensing
Saana Pauliina Liimatainen, David Grey
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Dynamic mooring-forces allocation in dynamic ship positioning
Journal of Optimization Theory and Applications, 1989The design of a dynamic positioning system for a multiply-moored vessel with active winches and thrusters is presented. The proposed positioning system is based on Kalman filter and linear optimal control. Its peculiarity is that it contains a scheme which allocates dynamically the control forces between moorings and thrusters.
AMBROSINO, GIUSEPPE +2 more
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Nonlinear positive observer design for positive dynamical systems
Proceedings of the 2010 American Control Conference, 2010In this paper, the observer design problem is considered for a class of positive dynamical systems. First, we establish a set of sufficient conditions for the design of a general class of positive nonlinear observers for nonlinear positive dynamical systems.
Brian, Ben, Wang, Jing, Qu, Zhihua
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Tuning a dynamic positioning system
Automatica, 1993Abstract The tuning of a complex control system used in ships and semisubmersible oil drilling rigs was studied. A method was sought which minimizes the time needed to tune a manned ship. Three different methods were compared to estimate the parameters of the nonlinear state filters used in the control system.
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