Qualitative simulation is a useful method for predicting the possible qualitatively distinct behaviors of an incompletely known mechanism described by a system of qualitative diierential equations (QDEs). Under some circumstances, sparse information about the derivatives of variables can lead to intractable branching (or \chatter") representing uninteresting or even spurious distinctions among ...

In this paper the nonlinear dynamics of a state-dependent delay model of the turning process is analyzed. The size of the regenerative delay is determined not only by the rotation of the workpiece, but also by the vibrations of the tool. A numerical continuation technique is developed that can be used to follow the periodic orbits of a system with implicitly defined state-dependent delays. The ...

Background As UCLA residents, we have the privilege of operating at 4 separate hospitals, each of them with a different phacoemulsification platform. Understanding the various phaco settings and occlusion surge minimizing features of each platform helps us maintain safety and efficiency as we rotate through our multiple hospitals. Currently, the Centurion system (Alcon, Fort Worth, Texas) is be...

Existing simulation models used in predicting the surface roughness of a workpiece in finish turning are based on an ideal circular cutting tool nose profile. This leads to a single predicted roughness value for a given set of input parameters. In this paper, a simulation approach that considers the random tool nose profile micro-deviations as well as the tool chatter vibration to predict a rou...

This paper presents a novel indirect adaptive Power System Stabilizer (PSS) via a developed synergetic control methodology and fuzzy systems. Fuzzy system is utilized in an adaptive scheme to estimate the system using a nonlinear model. The synergetic control guarantees robustness of the controller and makes the controller easy to implement because of using a chatter free continuous control law...

Chatter is a harmful self-excited vibration that commonly occurs during milling processes. Data-driven chatter detection and prediction critical to achieve high surface quality process efficiency. Most existing approaches are based on external sensors, such as accelerometers microphones, which require installation of extra devices. Some recent studies have proved the feasibility online using in...

Chatter detection from sensor signals has been an active field of research. While some success reported using several featurization tools and machine learning algorithms, existing methods have drawbacks including the need for data pre-processing by expert. In this paper, we present alternative approach chatter based on K-Nearest Neighbor (KNN) algorithm classification Dynamic Time Warping (DTW)...

Objective: The study purpose was to compare effects of two porcine lens storage methods on phacoemulsification efficiency and chatter. Methods: This in vitro laboratory study was conducted at the John A. Moran Eye Center Laboratories, University of Utah. Porcine nuclei were fixed in 10% formaldehyde and cut into 2.0 mm cubes. An equal number of lens cubes either were stored in a 100% humidity c...

This paper introduces practically important concept of local non-smoothness where any dynamical system can be considered as smooth in a finite size subspace of global hyperspaceΩ. Global solution is generated by matching local solutions obtained by standard methods. If the dynamical system is linear in all subspaces then an implicit global analytical solution can be given, as the times when non...

Productivity in modem machine tools is acheved by using high cutting velocities, spindle speeds and feed rates. A restriction for large material removal rates is the tendency of machines to chatter (structural vibration) for large depths of cut. This work is concerned with improving machine tool performance by understanding and ultimately controlling vibration in machine structures. If vibratio...