A spatial impedance controller for robotic manipulation

Mechanical impedance is the dynamic generalization of stiffness, and determines interactive behavior by definition. Although the argument for explicitly controlling impedance is strong, impedance control has had only a modest impact on robotic manipulator control practice. This is due in part to the fact that it is difficult to select suitable impedances given tasks. A spatial impedance controller is presented that simplifies impedance selection. Impedance is characterized using ¿spatially affine¿ families of compliance and damping, which are characterized by nonspatial and spatial parameters. Nonspatial parameters are selected independently of configuration of the object with which the robot must interact. Spatial parameters depend on object configurations, but transform in an intuitive, well-defined way. Control laws corresponding to these compliance and damping families are derived assuming a commonly used robot model. While the compliance control law was implemented in simulation and on a real robot, this paper emphasizes the underlying theor

Perovskite oxides: Oxygen electrocatalysis and bulk structure

Perovskite type oxides were considered for use as oxygen reduction and generation electrocatalysts in alkaline electrolytes. Perovskite stability and electrocatalytic activity are studied along with possible relationships of the latter with the bulk solid state properties. A series of compounds of the type LaFe(x)Ni1(-x)O3 was used as a model system to gain information on the possible relationships between surface catalytic activity and bulk structure. Hydrogen peroxide decomposition rate constants were measured for these compounds. Ex situ Mossbauer effect spectroscopy (MES), and magnetic susceptibility measurements were used to study the solid state properties. X ray photoelectron spectroscopy (XPS) was used to examine the surface. MES has indicated the presence of a paramagnetic to magnetically ordered phase transition for values of x between 0.4 and 0.5. A correlation was found between the values of the MES isomer shift and the catalytic activity for peroxide decomposition. Thus, the catalytic activity can be correlated to the d-electron density for the transition metal cations

1909 Ursinus College Founders\u27 Day Address

This booklet prints the Founders\u27 Day address delivered by Reverend D. Ernest Klopp at Ursinus College on February 11, 1909.https://digitalcommons.ursinus.edu/founders_programs/1004/thumbnail.jp

Forensic analysis of linux physical memory: Extraction and resumption of running processes.

Traditional digital forensics’ procedures to recover and analyze digital data were focused on media-type storage devices like hard drives, hoping to acquire evidence or traces of malicious behavior in stored files. Usually, investigators would image the data and explore it in a somewhat “safe” environment; this is meant to reduce as much as possible the amount of loss and corruption that might occur when analysis tools are used. Unfortunately, techniques developed by intruders to attack machines without leaving files on the disks and the ever dramatically increasing size of hard drives make the discovery of evidence difficult. These increased interest in research on live forensics (attempting to obtain evidence while the system is running) and on volatile memory forensic analysis. Because of the important role they play in computing systems, volatile memory is a source of information about running processes, network connections, opened files and/or loaded kernel modules that might be valuable to forensic investigations. In this thesis we show that when provided with an image of the physical memory of a Linux system, it is possible to extract data about a specific running process, enough to be able to resume its execution on a prepared environment. We also describe two proof-of-concept tools gettsk and memexec developed for this purpose. This would allow investigators to not only obtain information about a suspicious running task from a RAM dump, but also to perform further inquiry through techniques such as malware analysis