BibSonomy publications for /tag/passiveThu Jun 19 17:35:00 CEST 2008Ann ArborGenetic Programming Theory and Practice {III}1812-14 May275--290Genetic ProgrammingDomain Specificity of Genetic Programming based Automated Synthesis: a Case Study with Synthesis of Mechanical Vibration Absorbers92005algorithms, domain synthesis, systems, absorber, knowledge passive vibration Automated genetic graphs, bond programming, mechatronic Genetic programming has proved its potential for automated synthesis of a variety of engineering systems such as electrical, control, and mechanical systems. Given any of these application domains, a set of generic GP functions can be developed for its synthesis. In this chapter, however, we illustrate that while a generic GP system can often be used to prove a concept, realistic or industrial automated synthesis often requires domain-specific GP configuration, especially of the GP function sets. As a case study, it is shown how the open-ended topology search capability of GP readily exploits _loopholes_ in a generic bond-graph-based GP function set and evolves high-performance but unrealistic mechanical vibration absorbers, even though the bond graphs would be readily implementable in, for example, the electrical domain. The preliminary attempt to constrain evolved topologies to only those that would be readily implementable in the mechanical domain was not sufficiently restrictive.Thu Jun 19 17:35:00 CEST 2008IEICE Transactions on Electronics61180--1185Practical Passive Filter Synthesis Using Genetic ProgrammingE88-C2005synthesis, programming, algorithms, filter passive frequency-dependent genetic component proposes a genetic programming method to synthesise passive filter circuits. This method allows both the circuit topology and the component values to be evolved simultaneously. Experiments show that this method is fast and capable of generating circuits which are more economical than those generated by traditional design approaches. In addition, we take into account practical design considerations at high-frequency applications, where the component values are frequency-dependent and restricted to some discrete values. Experimental results show that our method can effectively generate not only compliant but also economical circuits for practical design tasks.Thu Jun 19 17:35:00 CEST 2008Proceedings of the IEEE International Symposium on Circuits and Systems (ISCAS)Economical passive filter synthesis using genetic programming based on tree representation2005programming, Passive Filter genetic Synthesis, Circuit algorithms, Representation we propose a tree representation for RLC circuits. Genetic programming based on the tree representation is described and applied to passive filter synthesis problems. In addition, a way to minimize the size of synthesized circuits is presented. The results show that the proposed method can effectively generate not only compliant but also economical passive filters.Thu Jun 19 17:35:00 CEST 2008IEEE Transactions on Evolutionary ComputationFebruary193--100Automated passive filter synthesis using a novel tree representation and genetic programming102006analysis, topology, circuits, filter optimisation, programming, synthesis, filters, RLC tree passive genetic automated synthesis Circuit network circuit GP-evolved representation, algorithms, This paper proposes a novel tree representation which is suitable for the analysis of RLC (i.e., resistor, inductor, and capacitor) circuits. Genetic programming (GP) based on the tree representation is applied to passive filter synthesis problems. The GP is optimised and then incorporated into an algorithm which can automatically find parsimonious solutions without predetermining the number of the required circuit components. The experimental results show the proposed method is efficient in three aspects. First, the GP-evolved circuits are more parsimonious than those resulting from traditional design methods in many cases. Second, the proposed method is faster than previous work and can effectively generate parsimonious filters of very high order where conventional methods fail. Third, when the component values are restricted to a set of preferred values, the GP method can generate compliant solutions by means of novel circuit topology.Thu Jun 19 17:35:00 CEST 2008Microelectronics JournalAugust8792--799Automated synthesis of passive filter circuits including parasitic effects by genetic programming372006genetic Parasitic algorithms, effects, Passive filter synthesis programming, In this paper, we propose a genetic programming method to synthesise passive filter circuits including parasitic effects, which are very common in high-frequency application. This approach allows circuit topology and component values to be evolved simultaneously; therefore, novel circuits different from those generated by traditional methods can be explored. Experimental results show the proposed method can effectively generate not only compliant but also efficient solutions of such problems where the traditional approaches fail.Wed Apr 23 22:05:04 CEST 2008Signal ProcessingSep91695--1710Bearings-only target localization using total least squares852005target localization Passive Wed Apr 23 15:41:51 CEST 2008Environmental Science & Technology41317-1323Polyethylene Devices: Passive Samplers for Measuring Dissolved Hydrophobic Organic Compounds in Aquatic Environments412007samplers organic Hydrophobic Passive Polyethylene PCBs compounds PAHs Abstract: We demonstrate the use of polyethylene devices (PEDs) for assessing hydrophobic organic compounds (HOCs) in aquatic environments. Like semipermeable membrane devices (SPMDs) and solid-phase microextraction (SPME), PEDs passively accumulate HOCs in proportion to their freely dissolved concentrations. Polyethylene-water partition constants (KPEWs) were measured in the laboratory for eight polycyclic aromatic hydrocarbons (PAHs), five polychlorinated biphenyls (PCBs), and one polychlorinated dibenzo-p-dioxin (PCDD), and these were found to correlate with octanol-water partition constants (KOWs; log KPEW = 1.13 log KOW - 0.86, R2 = 0.89). Temperature and salinity dependencies of KPEW values for the HOCs tested were well predicted with excess enthalpies of solution in water and Setschenow constants, respectively. We also showed that standards, impregnated in the PED before deployment, can be used to correct for incomplete equilibrations. Using PEDs, we measured phenanthrene and pyrene at ng/L concentrations and 2,2',5,5'-tetrachlorobiphenyl at pg/L concentrations in Boston Harbor seawater, consistent with our findings using traditional procedures. PEDs are cheap and robust samplers, competent to accomplish in situ, time-averaged passive sampling with fast equilibration times (~days) and simplified laboratory analyses.Tue Apr 22 14:25:45 CEST 2008Stochastic Processes and their ApplicationsAug81279--1301Einstein relation for random walks in random environments1152005tracer Passive Tue Apr 22 10:36:30 CEST 2008Physica A: Statistical Mechanics and its ApplicationsJul259--270Possible biomechanical origins of the long-range correlations in stride intervals of walking3802007walking Passive dynamic 01Sun Mar 02 02:12:02 CET 2008International Conference on Intelligent Robots and Systems (IROS)Passive Joint-Sensor Applications for Parallel Robots2004Micro Angular Parallel Inductive Passive Kinematics, Sensors, Measurement, Joint-Sensors, Coils Fri Oct 05 01:42:43 CEST 2007New Journal of Physics72Active and passive fields face to face62004passive cencini transport active intermittency turbulence The statistical properties of active and passive scalar fields transported by the same turbulent flow are investigated. Four examples of active scalar have been considered: temperature in thermal convection, magnetic potential in two-dimensional (2D) magnetohydrodynamics (MHD), vorticity in 2D Ekman turbulence and potential temperature in surface flows. In the cases of temperature and vorticity, it is found that the active scalar behaviour is akin to that of its co-evolving passive counterpart. The two other cases indicate that this similarity is in fact not generic and differences between passive and active fields can be striking: in 2D MHD, the magnetic potential performs an inverse cascade, whereas the passive scalar cascades towards the small scales; in surface flows, although both perform a direct cascade, the potential temperature and the passive scalar have different scaling laws already at the level of low-order statistical objects. These significant differences are rooted in the correlations between the active scalar input and the particle trajectories. The role of such correlations in the issue of universality in active scalar transport and the behaviour of dissipative anomalies is addressed.Fri Oct 05 00:38:29 CEST 2007Phys. Rev. Lett.Nov23234502Active versus Passive Scalar Turbulence892002turbulence passive scalar_turbulence cencini trasnport active Active and passive scalars transported by an incompressible two-dimensional conductive fluid are investigated. It is shown that a passive scalar displays a direct cascade towards the small scales while the active magnetic potential builds up large-scale structures in an inverse cascade process. Correlations between scalar input and particle trajectories are found to be responsible for those dramatic differences as well as for the behavior of dissipative anomalies.Sat Aug 18 13:22:24 CEST 2007JanMassive particles in acoustic space-times emergent inertia and passive gravity2006inertia emergent space-times passive gravity I show that massive-particle dynamics can be simulated by a weak, spherical, external perturbation on a potential flow in an ideal fluid. The effective Lagrangian is of the form mc^2L(U^2/c^2), where U is the velocity of the particle relative to the fluid and c the speed of sound. This can serve as a model for emergent relativistic inertia a la Mach's principle with m playing the role of inertial mass, and also of analog gravity where it is also the passive gravitational mass. m depends on the particle type and intrinsic structure, while L is universal: For D dimensional particles L is proportional to the hypergeometric function F(1,1/2;D/2;U^2/c^2). Particles fall in the same way in the analog gravitational field independent of their internal structure, thus satisfying the weak equivalence principle. For D less or equal 5 they all have a relativistic limit with the acquired energy and momentum diverging as U approaches c. For D less or equal 7 the null geodesics of the standard acoustic metric solve our equation of motion. Interestingly, for D=4 the dynamics is very nearly Lorentzian. The particles can be said to follow the geodesics of a generalized acoustic metric of a Finslerian type that shares the null geodesics with the standard acoustic metric. In vortex geometries, the ergosphere is automatically the static limit. As in the real world, in ``black hole'' geometries circular orbits do not exist below a certain radius that occurs outside the horizon. There is a natural definition of antiparticles; and I describe a mock particle vacuum in whose context one can discuss, e.g., particle Hawking radiation near event horizons.Wed Jun 20 10:16:09 CEST 2007Genova, ItalyAbstract Book of the XXIII IUPAP International Conference on Statistical Physics9-13 JulyOn the fractal structure of the passive scalar fields in a fully developed turbulence.2007topography passive statistical statphys23 topic-5 scalar turbulent diffusion The features of turbulent diffusion has been a great challenge for the statistical physics during decades. This is explained by high geometrical complexity of the emerging patterns, and by a large number of qualitatively different mixing regimes. Our aim is to study the statistical topography of a passive scalar (tracer) field in a fully developed two-dimensional turbulence, assuming the lower cut-off scale of the turbulent energy spectrum to be vanishingly small. In this case, the tracer density field is known to be characterized by a cascade of fractal discontinuity fronts [A. Celani et al, Phys. Fluids 13, 1768 (2001)]. Let us suppose that initially, the tracer density has a constant gradient, i.e. the iso-density lines are straight. If the molecular diffusion could be ignored, the value of the tracer density would be ``glued'' to the fluid particles. So, the fractal geometry of separate iso-density lines would correspond to the fractal geometry of a simple fluid line (virtual chain of fluid particles) evolving in the turbulent velocity field. However, the situation is somewhat more complicated. Large gradients of the tracer density field emerge due to the stretching and folding by the velocity field. If the molecular diffusion could be ignored, these large gradients would evolve into discontinuity fronts within a finite time. Then, any non-zero diffusivity can no longer be ignored. This gives rise to a drift and reconnection of the iso-density lines. Still, one can argue that the most significant drift and reconnection will take place only on a sparse, fractal set of the highest local stretching rate. Therefore, the iso-density lines (and the discontinuity fronts) might belong to the same universality class as the fluid lines. In order to test this hypothesis, we have calculated the fractal dimension of the liquid line numerically, and compared the results with earlier experimental data [J. Kondev and G. Huber, Phys. Rev. Lett. 86, 5890 (2001)]. The fluid line is defined as a set of points that co-move with the local velocity field; new points are added, when two neighbouring points depart farther than the lattice resolution $\delta$, and the line is reconnected, when two loops of the line approach closer than $\delta$. We generate a random velocity field, which is delta-correlated in time (Kraichnan regime), and follows a normal scaling power law. The simulations are performed on polygons of variable size (up to the radius $r=4096\delta$, as limited by the capabilities of the computing cluster); the exponents are obtained by extrapolating the finite-size scaling. The result $d\in [1.3,1.33]$ is in agreement with the fractal dimension of the iso-density lines ($d\approx 1.3$) obtained by Kondev and Huber. We calculate also the size-distribution exponent of the loops breaking apart from the main fluid line as a result of reconnections. The result $\alpha \approx 1.95$ is in agreement with our theoretical expectation $\alpha=2$.Wed Jun 20 10:16:09 CEST 2007Genova, ItalyAbstract Book of the XXIII IUPAP International Conference on Statistical Physics9-13 JulyClustering of sliding passive scalars driven by fluctuating surfaces2007scalars systems diffusive passive driven clustering statphys23 topic-3 A collection of passive particles driven by a fluctuating potential develops interesting correlations in space and time. We consider a system of damped particles sliding down a fluctuating surface evolving through Edwards-Wilkinson or Kardar-Parisi-Zhang dynamics. The particles are found to reach an interesting steady state with long range order, but with fluctuations which remain large in the thermodynamic limit. The density-density correlation function is a scaling function of separation and system size. Interestingly, the scaling function is singular at small argument, signalling large-scale clustering without well-defined interfaces --- a breakdown of the Porod law. The nature of the singularity depends on whether or not the particles interact with each other --- it is a divergence for noninteracting particles, and a cusp singularity for particles with hard core exclusion. Dynamical correlation functions also show size-dependent scaling with singular scaling functions. These results have a bearing on the passive scalar problem in fluid dynamics, as our problem maps onto particles advected by a noisy Burgers fluid. The properties of our strongly nonequilibrium system turn out to be surprisingly similar to those of a system of particles at equilibrium in a quenched disordered Sinai potential.passiveCommunity for tag(s) passive