The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform

Nick S. Jones - One of the best experts on this subject based on the ideXlab platform.

  • sparse bayesian step filtering for high throughput analysis of molecular Machine Dynamics
    arXiv: Quantitative Methods, 2010
    Co-Authors: Max A. Little, Nick S. Jones
    Abstract:

    Nature has evolved many molecular Machines such as kinesin, myosin, and the rotary flagellar motor powered by an ion current from the mitochondria. Direct observation of the step-like motion of these Machines with time series from novel experimental assays has recently become possible. These time series are corrupted by molecular and experimental noise that requires removal, but classical signal processing is of limited use for recovering such step-like Dynamics. This paper reports simple, novel Bayesian filters that are robust to step-like Dynamics in noise, and introduce an L1-regularized, global filter whose sparse solution can be rapidly obtained by standard convex optimization methods. We show these techniques outperforming classical filters on simulated time series in terms of their ability to accurately recover the underlying step Dynamics. To show the techniques in action, we extract step-like speed transitions from Rhodobacter sphaeroides flagellar motor time series. Code implementing these algorithms available from this http URL

  • Sparse Bayesian step-filtering for high-throughput analysis of molecular Machine Dynamics
    2010 IEEE International Conference on Acoustics Speech and Signal Processing, 2010
    Co-Authors: Max A. Little, Nick S. Jones
    Abstract:

    Nature has evolved many molecular Machines such as kinesin, myosin, and the rotary flagellar motor powered by an ion current from the mitochondria. Direct observation of the step-like motion of these Machines with time series from novel experimental assays has recently become possible. These time series are corrupted by molecular and experimental noise that requires removal, but classical signal processing is of limited use for recovering such step-like Dynamics. This paper reports simple, novel Bayesian filters that are robust to step-like Dynamics in noise, and introduce an L1-regularized, global filter whose sparse solution can be rapidly obtained by standard convex optimization methods. We show these techniques outperforming classical filters on simulated time series in terms of their ability to accurately recover the underlying step Dynamics. To show the techniques in action, we extract step-like speed transitions from Rhodobacter sphaeroides flagellar motor time series.

Max A. Little - One of the best experts on this subject based on the ideXlab platform.

  • sparse bayesian step filtering for high throughput analysis of molecular Machine Dynamics
    arXiv: Quantitative Methods, 2010
    Co-Authors: Max A. Little, Nick S. Jones
    Abstract:

    Nature has evolved many molecular Machines such as kinesin, myosin, and the rotary flagellar motor powered by an ion current from the mitochondria. Direct observation of the step-like motion of these Machines with time series from novel experimental assays has recently become possible. These time series are corrupted by molecular and experimental noise that requires removal, but classical signal processing is of limited use for recovering such step-like Dynamics. This paper reports simple, novel Bayesian filters that are robust to step-like Dynamics in noise, and introduce an L1-regularized, global filter whose sparse solution can be rapidly obtained by standard convex optimization methods. We show these techniques outperforming classical filters on simulated time series in terms of their ability to accurately recover the underlying step Dynamics. To show the techniques in action, we extract step-like speed transitions from Rhodobacter sphaeroides flagellar motor time series. Code implementing these algorithms available from this http URL

  • Sparse Bayesian step-filtering for high-throughput analysis of molecular Machine Dynamics
    2010 IEEE International Conference on Acoustics Speech and Signal Processing, 2010
    Co-Authors: Max A. Little, Nick S. Jones
    Abstract:

    Nature has evolved many molecular Machines such as kinesin, myosin, and the rotary flagellar motor powered by an ion current from the mitochondria. Direct observation of the step-like motion of these Machines with time series from novel experimental assays has recently become possible. These time series are corrupted by molecular and experimental noise that requires removal, but classical signal processing is of limited use for recovering such step-like Dynamics. This paper reports simple, novel Bayesian filters that are robust to step-like Dynamics in noise, and introduce an L1-regularized, global filter whose sparse solution can be rapidly obtained by standard convex optimization methods. We show these techniques outperforming classical filters on simulated time series in terms of their ability to accurately recover the underlying step Dynamics. To show the techniques in action, we extract step-like speed transitions from Rhodobacter sphaeroides flagellar motor time series.

Yusuf Altintas - One of the best experts on this subject based on the ideXlab platform.

  • automatic tuning of active vibration control systems using inertial actuators
    Cirp Annals-manufacturing Technology, 2017
    Co-Authors: Michael F Zaeh, Robin Kleinwort, P Fagerer, Yusuf Altintas
    Abstract:

    Abstract Material removal rates of Machine tools are mainly limited by chatter, which is caused by the Machine’s most flexible structural modes. Active damping of the structural modes requires the identification of a Machine Dynamics model used in tuning the active controller. This complex process has to consider uncertainties, actuator saturation, and the stability of the controller. This paper presents an automated identification of Machine Dynamics and auto-tuning of the controller using the same actuator and vibration sensor. The proposed method has been experimentally demonstrated with simple and advanced controllers which led to notable increases in chatter free material removal rates.

  • Integrated five-axis trajectory shaping and contour error compensation for high-speed CNC Machine tools
    IEEE ASME Transactions on Mechatronics, 2014
    Co-Authors: M. R. Khoshdarregi, Svenja Tappe, Yusuf Altintas
    Abstract:

    A feedforward trajectory command shaping algorithm is proposed to simultaneously reduce the contouring errors and avoid structural vibrations in five-axis CNC Machine tools. Trajectory shaping is used to avoid the excitation of the transient, inertial vibrations but at the expense of distorting the reference path due to added delay. The contouring error caused by both trajectory shaping and limited bandwidth of servo drives is predicted based on the trajectory parameters and Machine Dynamics. The shaped axis commands are then corrected to precompensate the predicted contour errors. The effectiveness of the proposed technique is verified experimentally on a five-axis CNC machining center.

Henk Nijmeijer - One of the best experts on this subject based on the ideXlab platform.

  • Online chatter detection in high-speed milling
    2020
    Co-Authors: R. P H. Faassen, J.a.j. Oosterling, Van De N Nathan Wouw, E.j.j. Doppenberg, Henk Nijmeijer
    Abstract:

    The high-speed milling process is most efficient when the material removal rate or surface generation rate are maximised. However, these two rates are often limited by the occurrence of Machine tool chatter. Chatter is an instability phenomenon, which results in heavy vibrations of the tool. This causes an inferior workpiece quality, rapid tool wear and noise. Therefore, chatter should be prevented from occurring at all times. Nowadays, utilities exist to predict the stability boundaries off-line [1]. These methods produce a stability lobe diagram as is shown in figure 1. However, these stability lobes are very sensitive to variations in the cutting process or Machine Dynamics, e.g. the stiffness of the spindle. For example, due to spindle heating during milling, Machine Dynamics can change to such an extent that a set of machining parameters ensuring a stable cut at first, will induce chatter later on. Therefore, it is necessary not only to predict the occurrence of chatter off-line, but also to monitor the process on-line while cutting.

  • Prediction of regenerative chatter by modelling and analysis of high-speed milling
    International Journal of Machine Tools & Manufacture, 2003
    Co-Authors: R. P H. Faassen, J.a.j. Oosterling, Van De N Nathan Wouw, Henk Nijmeijer
    Abstract:

    High-speed milling is widely used in the manufacturing industry. For the efficiency of the milling process, high demands on the material removal rate and the surface generation rate are posed. The process parameters, determining these two rates, are restricted by the occurrence of regenerative chatter. Chatter is an undesired instability phenomenon, which causes both a reduced product quality and rapid tool wear. In this paper, the milling process is modelled, based on dedicated experiments on both the material behaviour of the workpiece material and the Machine Dynamics. These experiments show that both the material properties and the Machine Dynamics are dependent on the spindle speed. Furthermore, a method for the prediction of the chatter boundaries is proposed and applied in order to predict the chatter boundaries as a function of process parameters, such as spindle speed and depth-of-cut, for spindle speed varying material and Machine parameters. Finally, experiments are performed to estimate these chatter boundaries in practice. The modelled chatter boundaries are compared to the experimental results in order to validate the model and the stability analysis.

  • Prediction of regenerative chatter by modelling and analysis of high-speed milling
    International Journal of Machine Tools and Manufacture, 2003
    Co-Authors: R. P H. Faassen, J.a.j. Oosterling, Nathan Van De Wouw, Henk Nijmeijer
    Abstract:

    High-speed milling is widely used in the manufacturing industry. For the efficiency of the milling process, high demands on the material removal rate and the surface generation rate are posed. The process parameters, determining these two rates, are restricted by the occurrence of regenerative chatter. Chatter is an undesired instability phenomenon, which causes both a reduced product quality and rapid tool wear. In this paper, the milling process is modelled, based on dedicated experiments on both the material behaviour of the workpiece material and the Machine Dynamics. These experiments show that both the material properties and the Machine Dynamics are dependent on the spindle speed. Furthermore, a method for the prediction of the chatter boundaries is proposed and applied in order to predict the chatter boundaries as a function of process parameters, such as spindle speed and depth-of-cut, for spindle speed varying material and Machine parameters. Finally, experiments are performed to estimate these chatter boundaries in practice. The modelled chatter boundaries are compared to the experimental results in order to validate the model and the stability analysis. © 2003 Elsevier Ltd. All rights reserved.

DD Walker - One of the best experts on this subject based on the ideXlab platform.

  • Subsurface damage in precision ground ULE (R) and Zerodur (R) surfaces
    OPT EXPRESS, 2007
    Co-Authors: DD Walker
    Abstract:

    The total process cycle time for large ULE (R) and Zerodur((R)) optics can be improved using a precise and rapid grinding process, with low levels of surface waviness and subsurface damage. In this paper, the amounts of defects beneath ULE (R) and Zerodur((R)) surfaces ground using a selected grinding mode were compared. The grinding response was characterised by measuring: surface roughness, surface profile and subsurface damage. The observed subsurface damage can be separated into two distinct depth zones, which are: 'process' and 'Machine Dynamics' related. (c) 2007 Optical Society of America.

  • Comparison of the subsurface damage induced when precision grinding ULE® and Zerodur® surfaces
    Laser Metrology and Machine Performance VIII - 8th International Conference and Exhibition on Laser Metrology, Machine Tool, CMM and Robotic Performan, 2007
    Co-Authors: DD Walker
    Abstract:

    A precise and rapid grinding process, with low levels of surface waviness and subsurface damage, can improve the total cycle time for producing large ULE® and Zerodur® optics. In this paper, the subsurface damage level of ULE® and Zerodur® were investigated and compared. Resin bonded diamond cup wheels were employed. The grinding response was characterized by measuring: surface roughness, surface profile and subsurface damage. The amount of defects beneath ULE® and Zerodur® surfaces ground using the selected grinding mode were compared. The observed subsurface damage can be separated in two distinct depth zones, the first 'process' related and the second being 'Machine Dynamics' related.