Design for emergence: experiments with a mixed reality urban playground game

In this paper we present our work in the design of ubiquitous social experiences, aiming to foster group participation and spontaneous playful behaviours in a city environment. We outline our approach of design for emergence: to provide just enough of a game context and challenge for people to be creative, to extend and enrich the experience of play through their interaction in the real world. CitiTag is our mixed reality testbed, a wireless location-based multiplayer game based on the concept of playground ‘tag’. We describe the design and implementation of CitiTag and discuss results from two user studies.     

Generalization of dissonance reduction: Decreasing prejudice through induced compliance.

Three studies involving a total of 318 White college students demonstrated that induced compliance can change socially significant attitudes and that the change generalizes to broader beliefs. Ss wrote an essay endorsing a pro-Black policy that was costly to Whites. In Exps 1 and 2, attitudes and general beliefs about Blacks became more favorable in both high- and low-choice conditions, provided publicity of the essay was high. Overall, choice and publicity had additive effects on attitude change. Some high-choice Ss wrote only semipositive (semicompliant) essays and did not change their essay attitudes. Yet their beliefs about Blacks still became more favorable. In Exp 3, racial ambivalence, but not prior attitude, predicted essay compliance. Ambivalent Ss were more likely to comply than were less ambivalent Ss. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evaluating a virtual summer school

The Open University's Virtual Summer School took place in 1994 and was an experimental project which aimed to use technology to support students who were unable to attend a conventional campus‐based summer school. Students on many courses at the Open University are expected to attend summer school, but for some students this is impossible. In the Virtual Summer School, 12 students used a wide range of software to communicate with tutors and each other, attend lectures and tutorials, access resources and complete projects in groups. The students were studying Cognitive Psychology and the work involved a range of activities including programming, carrying out experiments and statistical analysis. The evaluation used a series of questionnaires to the students, which were compared with those of students at conventional summer school. This paper provides an overview of the Virtual Summer School, presents a selection of the results of the evaluation and discusses the issues which arose out of the evaluation.     

A new on-chip interconnect crosstalk model and experimentalverification for CMOS VLSI circuit design

A new, simple closed-form crosstalk model is proposed. The model is based on a lumped configuration but effectively includes the distributed properties of interconnect capacitance and resistance. CMOS device nonlinearity is simply approximated as a linear device. That is, the CMOS gate is modeled as a resistance at the driving port and a capacitance at a driven port. Interconnects are modeled as effective resistances and capacitances to match the distributed transmission behavior. The new model shows excellent agreement with SPICE simulations. Further, while existing models do not support the multiple line crosstalk behaviors, our model can be generalized to multiple lines. That is, unlike previously published work, even if the geometrical structures are not identical, it can accurately predict crosstalk. The model is experimentally verified with 0.35-μm CMOS process-based interconnect test structures. The new model can be readily implemented in CAD analysis tools. This model can be used to predict the signal integrity for high-speed and high-density VLSI circuit design     

Dynamic Current Requirements in Single-Ended Log-Domain Filters

Single-ended log-domain filters must operate Class A: the amplitude of any symmetric signal must be less than the bias current. Even so, peak internal dynamic current requirements can be much greater than the bias currents. Worst-case peak current demands in a second-order log-domain filter are related to modulation index by simple expressions that allow transistor geometries to be optimized for specified signal levels. Several circuit topologies are considered, and some circuit topologies are shown to be better able to supply larger internal currents than others.     

Direct measurement of crosstalk between integrated differentialcircuits

Silicon integrated-circuit test structures have been fabricated that allow direct measurement of crosstalk between differential transmission lines and between single-ended transmission lines in the presence of metal ground plane. The differential test structures are characterized with mixed-mode scattering parameters (common mode, differential mode, and mode conversion), as measured with the pure-mode vector network analyzer. Comparisons with simulation show good agreement for differential-mode crosstalk, and the dependence of crosstalk on transmission-line separation is presented. Difficulties in simulating crosstalk fur even simple structures illustrate the utility of direct measurement of crosstalk     

Circuit for monitoring BJT RF performance using DC measurements

A test circuit is described for on-wafer monitoring of high-frequency performance of bipolar junction transistors using only dc measurements. The test circuit includes an oscillation-amplitude detector and a high-frequency (/spl sim/3 GHz) oscillator whose minimum bias current for oscillation I/sub osc/ correlates strongly with the transistors' maximum oscillation frequency f/sub max/. Variations in the circuit's I/sub osc/ can be routinely monitored to track changes in f/sub max/ caused by process variations. Monte Carlo simulations showed a correlation coefficient of -0.79 between I/sub osc/ and f/sub max/. Variations in measured f/sub max/ intentionally introduced through layout variations were verified to be strongly correlated with I/sub osc/.     

Calibration and verification of the pure-mode vector networkanalyzer

In this paper, the calibration of a pure-mode vector network analyzer (PMVNA) is presented in detail. The analyzer is intended for the measurement of mixed-mode scattering parameters (s-parameters) of differential circuits, but is also suitable for measurement of general microwave networks with up to four ports. The theory of calibration of the analyzer is developed in terms of a general n-port analyzer, including the correction of port-to-port crosstalk. The type of the standards used in calibration is examined, and the minimum number of standards are summarized for various levels of crosstalk correction. A new standard for all multiport network analyzer calibrations is introduced. A calibration is performed from 0.25 to 25.25 GHz based on standards with coaxial connectors, and verification standards are measured. The measured data is compared with National Institute of Standards and Technology (NIST) traceable measurements, and errors are found to be generally less than ±1 dB in transmission. In many cases, the error is less than the uncertainty of the NIST traceable measurements     

Pareto layer: Its formulation and search by way of evolutionary multi-objective optimization

This article examines multi-objective problems where a solution (product) is related to a cluster of performance vectors within a multi-objective space. Here the origin of such a cluster is not uncertainty, as is typical, but rather the range of performances attainable by the product. It is shown that, in such cases, comparison of a solution to other solutions should be based on its best performance vectors, which are extracted from the cluster. The result of solving the introduced problem is a set of Pareto optimal solutions and their representation in the objective space, which is referred to here as the Pareto layer. The authors claim that the introduced Pareto layer is a previously unattended novel representation. In order to search for these optimal solutions, an evolutionary multi-objective algorithm is suggested. The article also treats the selection of a solution from the obtained optimal set.