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# Search results

407 records were found.

## Customer retention in the financial industry: An application of survival analysis

Recently, in both marketing theory (academia) and practice (industry), the emphasis in relationship marketing has shifted to long term customer relationship management emphasizing customer retention or loyalty. This study has two main purposes: (1) to investigate the impacts of selected firm-customer interaction behavior and demographic characteristics on customer retention behavior in the financial industry, (2) to compare the results of a static method of analysis (logistic regression model) and a dynamic method (Cox’s hazard method) for customer retention. ^ The statistical analyses conducted employing two cohorts showed that the Cox model was stable across cohorts. Using Cox’s hazard method, all of the independent variables were found to be significantly related to customer retention, while some of demographic factors (for exampl...

## X-ray diffraction analysis of gene V protein encoded by filamentous bacteriophage Ff

The crystal structures of four mutant gene V proteins were solved and refined to $\sim$2 A resolutions. Three of these mutants were apolar substitutions in the hydrophobic core of the protein. One mutant, Arg 82 $\to$ Cys, is at the protein surface and is involved in breaking up of a surface salt bridge. The effects of these substitutions on the stability of the protein were discussed.

## A note on windowing for the waveform relaxation

The technique of windowing has been often used in the implementation of the waveform relaxations for solving ODE's or time dependent PDE's. Its efficiency depends upon problem stiffness and operator splitting. Using model problems, the estimates for window length and convergence rate are derived. The electiveness of windowing is then investigated for non-stiff and stiff cases respectively. lt concludes that for the former, windowing is highly recommended when a large discrepancy exists between the convergence rate on a time interval and the ones on its subintervals. For the latter, windowing does not provide any computational advantage if machine features are disregarded. The discussion is supported by experimental results.

## Design and Implementation of a Robot Force and Motion Server

A robot manipulator is a force and motion server for a robot. The robot, interpreting sensor information in terms of a world model and a task plan, issues instructions to the manipulator to carry out tasks. The control of a manipulator first involves motion trajectory generation needed when the manipulator is instructed to move to desired positions. The procedure of generating the trajectory must be flexible and efficient. When the manipulator comes into contact with the environment such as during assembly, it must be able to comply with the geometric constraints presented by the contact in order to perform tasks successfully. The control strategies for motion and compliance are executed in real time by the control computer, which must be powerful enough to carry out the necessary computations. This thesis first presents an efficient m...

## RFMS Software Reference Manual

This manual explains the software of the Robot Force and Motion Server (RFMS), a high performance robot control system designed and implemented in the GRASP laboratory. In this system, the robot manipulator is considered a force/motion server to the robot and a user application is treated as a request for the service of the manipulator. The user application is created on one of the Unix/VAX machines in 'C' programming language as a set of function calls. The application is carried out in a multi-processor controller, which consists of Intel single board computers and provides computing power necessary for computationally intensive tasks. The VAX machine and the Intel controller communicate through Ethernet, a local area network, which also allows interaction between the user and sensors. Design principles of the system can be found in ...

## RFMS Source Code

This is the source code of RFMS, a high performance robot control system designed and implemented in GRASP laboratory. It is intended to serve as a reference to "Software Reference Manual", prepared by Hong Zhang, the Department of Computer and Information Science, the University of Pennsylvania.

## Motion control for dynamic mobile robots

In this thesis, we present research results on sensor-based motion planning and nonlinear control for mobile robotic systems. In sensor-based motion planning, we use ideas from game theory to deal with the uncertainties accompanying real sensors and moving obstacles. We show that this idea can be successfully applied to both open loop and closed loop motion planning and control algorithms. With the emphasis on the use of a vision sensor, we extend the concept of sensor-based motion planning to motion planning in the image plane, which can help us to bypass the calibration errors associated with vision-based control, and achieve faster response speeds. Meanwhile, we address the effect of dynamics in vision-based motion control, or visual servoing, and expanded our ability to control a dynamic robotic system, such as the blimp robot. ^ ...

## Regulation of glial cell development and axonal outgrowth in the vertebrate central nervous system.

The complex and diverse functions of the mature vertebrate central nervous system (CNS) depend on the precise interactions formed by many types of neural cells, including neurons and glial cells. The major classes of macroglial cells in the CNS are astrocytes and oligodendrocytes. While astrocytes and their precursors have been proposed to participate in many CNS events including the guidance of migrating growth cones, oligodendrocytes form myelin, an axonal insulation sheath. The differentiation of oligodendrocytes occurs in a series of distinct stages in the spinal cord as well as other regions of the CNS and studies are required to determine the cellular mechanisms that regulate oligodendrocyte differentiation in the spinal cord. In the first part of this dissertation study, the results obtained indicate that oligodendrocyte differe...

## Personal information organization and re-access in computer folders: an empirical study of information workers

The current hierarchical folder system has long been found limited causing various difficulties in organizing and re-finding information on personal computers. Many alternative prototypes have been proposed to replace the current folder system. However, past empirical studies consistently observed that people prefer browsing folders in re-accessing information and only use searching as the last resort. Recognizing the complexity and our limited understanding of personal information organization and retrieval behavior in computer folders, my study was aimed to explore what people need from folders and the affordances and limitations of folders in the different stages of organization and retrieval, and furthermore provide implications for system design. Improved understanding on personal information organization and retrieval on computer...