Growth dynamics of C60 thin films: effect of molecular structure

The surface morphology and growth behavior of fullerene thin films have been studied by atomic force microscopy and height difference correlation function analysis. In contrast to the large growth exponents (beta) previously reported for other organic semiconductor thin-film materials, a relatively small beta value of 0.39±0.10 was determined. Simulations of (1+1)-dimensional surface lateral diffusion models indicate that the evolution of deep grain boundaries leads to a rapid increase in beta. We suggest that the commonly observed large beta values for organic thin films are due to their intrinsically anisotropic molecular structures and hence different stacking directions between crystallite domains

Experimental verification and practical application of torquewhirl theory of rotordynamic instability

A theory developed by Vance in 1978 to explain the destabilizing effect of torque on a whirling rotor was experimentally verified. The measurements made on a specially designed test apparatus are described. New computer models were also developed to investigate the effect of torque on rotordynamic stability of multidisk flexible rotor bearing systems. The effect of torque was found to be most pronounced when the system is already marginally stable from other influences. The modifications required to include torque in a typical shaft transfer matrix are described, and results are shown which identify the type of rotor design most sensitive to load torque

Decoupling and Disturbance Rejection Control for Target Circulation

In 1998, the Institute of Physics and Power Engineering (IPPE) and Experimental and Development Organization “Gidropress” in Russia, began the design and construction of a prototype lead-bismuth eutectic (LBE) accelerator target, the Target Complex 1 (TC-1), under the International Science and Technology Center (ISTC) project #559 (“Pilot Flow Lead-Bismuth Target of 1 MW Power for Accelerator Driven Systems”) in support of the international efforts to develop accelerator-driven spallation systems for nuclear transmutation and other applications. During the thermal and engineering test of the TC-1 in 2005 at UNLV, it was observed that the existing control algorithm led to a very slow convergence to the target temperature setting and also showed unstable oscillatory behavior. The original algorithm was not robust enough to handle the complicated heating system of the TC-1, where nine heating zones (elements) are compacted in one tight container. This interaction and coupling between each heating zone, as well as a heat disturbance from a low efficiency electromagnetic (EM) pump caused the overall temperature control system to be complex and nonlinear. The objective of the proposed research was to study the coupling effect between each heating zone, and to improve the overall temperature control system of the TC-1 loop. In addition to the temperature control algorithm modification, a 24-hour automatic monitoring system of the EM pump was developed for robust and safe operation of the loop

Modular Self-Reconfigurable Robot Systems

The field of modular self-reconfigurable robotic systems addresses the design, fabrication, motion planning, and control of autonomous kinematic machines with variable morphology. Modular self-reconfigurable systems have the promise of making significant technological advances to the field of robotics in general. Their promise of high versatility, high value, and high robustness may lead to a radical change in automation. Currently, a number of researchers have been addressing many of the challenges. While some progress has been made, it is clear that many challenges still exist. By illustrating several of the outstanding issues as grand challenges that have been collaboratively written by a large number of researchers in this field, this article has shown several of the key directions for the future of this growing fiel

Facebook’s “Free Basics”: For or against community development?

A recent discussion on a prominent community informatics (CI) listserv revealed arguments for and against the Facebook’s Free Basics platform among researchers in the field. To continue and enrich the conversation, this study first examines the contrasting stances revealed in the CI listserv discussion and derives the CI researchers’ major concerns about the platform. Under the light of these concerns, we then explore the nature of Facebook’s Free Basics in relation to community development through analysis of one of the forefront services that Free Basics offers, i.e., Facebook. Specifically, we examine relationships between uses of Facebook and information technology (IT) identity formation and social capital. We argue that although projects operated by private companies may possess potential for supporting community development, much consideration is needed in embracing the technology solutions due to the risks and restrictions they can impose on its users. We also suggest the CI researchers to open the next round of discussion regarding ways to thoroughly assess possible flaws of Free Basics and help users of the platform make more informed decisions. IT identity is a new theory that can help shed new light on the challenges of using platforms such as Free Basics and their contribution to community development

A New Approach for Practical Two Dimensional Data Fusion Utilizing a Single Eddy Current Probe

Interest in data fusion techniques have been growing in recent years due to the belief that a single NDE measurement may often be inadequate for providing sufficient information about the state of a test specimen. A variety of data fusion approaches have been proposed for combining results obtained by different methods, as well as different sensors, to provide comprehensive information about the material under test [1–4]. Techniques proposed to date range from blind superposition to approaches that involve the use of statistical and AI methods [5–7]