Energy control of the IMPELA series of industrial accelerators

Electron accelerator sources of radiation for industrial processes must maintain constant and reproducible irradiation parameters in order to provide satisfactory dose quality assurance. The advanced control system used in AECL's IMPELA^TM series of accelerators ensures this by making it possible to decouple the primary accelerator variables, beam energy and beam current. Beam energy is made independent of current by controlling the field amplitude in the standing-wave structure during a relatively long pulse (50–500 μs) and an energy stability similar to that of dc machines is achieved. Experiments with the calibration linac facility at Chalk River show that the beam energy can be held constant to within ± 2% on an absolute basis. This eliminates the requirement for the complex beam analysis after acceleration used on short-pulse linacs. Methods for the measurement of energy at the users site and at the calibration facility are described.     

Porous organosilicates low-dielectric films for high-frequency devices

The dielectric properties are reported for nanoporous thin films of poly(methyl silsesquioxane) (MSSQ) for use as an ultralow, dielectric intermetal insulator. Direct experimental conformation is provided that the films have low dielectric constants with low loss up to 10 GHz. Low-frequency measurements are also reported.     

Development of substrate-pumped nMOS protection for a 0.13 μm technology

A methodology is presented for improved process and circuit development of substrate-pumped nMOS protection. ESD process development is accelerated by applying factor analysis to completed non-ESD experiments. Factor analysis is complemented by a straightforward diagnosis of nMOS snapback. This approach enabled verification of two process solutions, including a novel method, in one fab cycle-time. HBM data that shows the substrate-pumped nMOS can provide dramatically higher protection than estimated from conventional I_t2 measurements. This motivates improved ESD circuit development. The nMOS clamp transistor is characterized as an actively biased LNPN, which is how it is used in a substrate-pumped protection circuit. A systematic approach to circuit development is described that is based upon empirical characterization of well-defined circuit components under conditions approximating ESD.     

CAT4 (Cable Actuated Truss—4 Degrees of Freedom): A Novel 4 DOF Cable Actuated Parallel Manipulator

The CAT4 (Cable Actuated Truss—4 degrees of freedom) robot is a novel, passively jointed, parallel robot utilizing six control cables for actuation. The architecture has been under development at the Queen's University Robotics Laboratory. The robot utilizes a passive jointed linkage with 18 revolute joints to constrain the end effector motion and provide the desired structural stability, restricting the end effector to 3 translational degrees of freedom (DOF) and 1 DOF for end effector pitch. This central mechanism together with winched cable actuation gives a number of important benefits for applications where the advantages of a parallel robot are required in conjunction with light weight. Six electric motor driven winches control the length of the cable actuators that extend from the top frame to points on the end effector raft and jointed linkage to create a stiff, but lightweight, actuated robot. Simulation work on the robot is presented giving the kinematics, including a computational estimate of the workspace for a specific configuration. Results of computational simulation of the motion of the manipulator and a discussion of the advantages and potential difficulties are also presented. © 2002 Wiley Periodicals, Inc.     

Behavioral adaptation within cross-cultural virtual teams

With today's business environments no longer confined to national borders, much work is undertaken in global virtual teams. Such teams consist of members located in different countries that communicate via technology media to complete a project task. Much of the research in this area has been focused on the technological aspects of such environments; there is, however, a lack of research into the behavioral aspects and the issue of cultural differences in particular. It has been acknowledged that when cultural diversity is neither recognized nor acted upon, significant challenges can arise for the team. Current advice in the literature suggests that team members should adapt their normal working behavior in consideration of cultural differences. However, there is little indication of how team members should do so. This study investigated if and/or how team members adapt their behavior in cross-cultural virtual teams. The results of this study indicate that team members can adapt their behavior in both spoken and written communication as well as allowing for religious beliefs and time zone differences. This paper discusses specifically how behavior can be adapted, including a discussion of behaviors that caused concern. Finally, a framework of behavioral adaptations is presented for ways to improve cross-cultural virtual team interactions.     

Vibrotactile pattern isolation/integration

Temporal integration has been cited as a major factor in temporal masking. Two experiments were designed to examine the conditions under which temporal integration may aid or hinder the perception of vibrotactile spatial patterns. In Experiment 1, the subject's task was to discriminate between pairs of patterns. Each pattern was composed of two temporally separated pattern elements. When the task required the subjects to perceive the individual pattern elements, performance improved with temporal isolation--that is, performance improved as the temporal separation between the elements increased. In a second task, when the discrimination could be based on either the overall pattern shape or the pattern elements, temporal integration appeared to improve performance--that is, performance improved as the temporal separation decreased. In Experiment 2, an identification task was used. Several factors appeared to determine whether temporal integration aided or hindered pattern identification. When pattern elements similar to those in Experiment 1 were tested, performance improved with increasing temporal separation (isolation). A single function was fit to the discrimination (isolation) and identification (isolation) results. Whether temporal integration aids or hinders pattern perception appears to depend on pattern shape, the pattern elements, and the nature of the task.     

Making law modern: Toward a contextual model of justice.

Contemporary psychological and legal models of behavior are still fundamentally at odds, and the impending paradigm clash may have profound, long-term consequences for our 21st-century legal doctrines and institutions. The 19th-century "formative era" of American law coincided with the dominance of psychological individualism in the nation's collective view of human nature and resulted in the institutionalization of a now antiquated model of human behavior. As we enter the new millennium, a "New Legal Realism" based on a view of human nature more consistent with contemporary psychological thinking is urged, along with a series of interlocking legal changes intended to both incorporate a more contextual view of human nature into law and improve the quality of justice our system currently dispenses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Output-SensitiveVisibility Algorithms for Dynamic Scenes with Applications to Virtual Reality

An output-sensitive visibility algorithm is one whose runtime is proportional to the number of visible graphic primitives in a scene model—not to the total number of primitives, which can be much greater. The known practical output-sensitive visibility algorithms are suitable only for static scenes, because they include a heavy preprocessing stage that constructs a spatial data structure which relies on the model objects’ positions. Any changes to the scene geometry might cause significant modifications to this data structure. We show how these algorithms may be adapted to dynamic scenes. Two main ideas are used: first, update the spatial data structure to reflect the dynamic objects’ current positions; make this update efficient by restricting it to a small part of the data structure. Second, use temporal bounding volumes (TBVs) to avoid having to consider every dynamic object in each frame. The combination of these techniques yields efficient, output-sensitive visibility algorithms for scenes with multiple dynamic objects. The performance of our methods is shown to be significantly better than previous output-sensitive algorithms, intended for static scenes. TBVs can be adapted to applications where no prior knowledge of the objects’ trajectories is available, such as virtual reality (VR), simulations etc. Furthermore, they save updates of the scene model itself; notjust of the auxiliary data structure used by the visibility algorithm. They can therefore be used to greatly reduce the communications overhead in client-server VR systems, as well as in general distributed virtual environments.