Geographically weighted visualization: interactive graphics for scale-varying exploratory analysis

We introduce a series of geographically weighted (GW) interactive graphics, or geowigs, and use them to explore spatial relationships at a range of scales. We visually encode information about geographic and statistical proximity and variation in novel ways through gw-choropleth maps, multivariate gw-boxplots, gw-shading and scalograms. The new graphic types reveal information about GW statistics at several scales concurrently. We impement these views in prototype software containing dynamic links and GW interactions that encourage exploration and refine them to consider directional geographies. An informal evaluation uses interactive GW techniques to consider Guerry's dataset of 'moral statistics', casting doubt on correlations originally proposed through visual analysis, revealing new local anomalies and suggesting multivariate geographic relationships. Few attempts at visually synthesising geography with multivariate statistical values at multiple scales have been reported. The geowigs proposed here provide informative representations of multivariate local variation, particularly when combined with interactions that coordinate views and result in gw-shading. We argue that they are widely applicable to area and point-based geographic data and provide a set of methods to support visual analysis using GW statistics through which the effects of geography can be explored at multiple scales.     

Printable phosphorescent organic light‐emitting devices

Abstract— A new approach to full‐color printable phosphorescent organic light‐emitting devices (P²OLEDs) is reported. Unlike conventional solution‐processed OLEDs that contain conjugated polymers in the emissive layer, the P²OLED's emissive layer consists of small‐molecule materials. A red P²OLED that exhibits a luminous efficiency of 11.6 cd/A and a projected lifetime of 100,000 hours from an initial luminance of 500 cd/m², a green P²OLED with a luminous efficiency of 34 cd/A and a projected lifetime of 63,000 hours from an initial luminance of 1000 cd/m², a light‐blue P²OLED with a luminous efficiency of 19 cd/A and a projected lifetime 6000 hours from an initial luminance of 500 cd/m², and a blue P²OLED with a luminous efficiency of 6.2 cd/A and a projected lifetime of 1000 hours from an initial luminance of 500 cd/m² is presented.     

Self-adaptive population sizing for a tune-free differential evolution

The study and research of evolutionary algorithms (EAs) is getting great attention in recent years. Although EAs have earned extensive acceptance through numerous successful applications in many fields, the problem of finding the best combination of evolutionary parameters especially for population size that need the manual settings by the user is still unresolved. In this paper, our system is focusing on differential evolution (DE) and its control parameters. To overcome the problem, two new systems were carried out for the self-adaptive population size to test two different methodologies (absolute encoding and relative encoding) in DE and compared their performances against the original DE. Fifty runs are conducted for every 20 well-known benchmark problems to test on every proposed algorithm in this paper to achieve the function optimization without explicit parameter tuning in DE. The empirical testing results showed that DE with self-adaptive population size using relative encoding performed well in terms of the average performance as well as stability compared to absolute encoding version as well as the original DE.     

Security through Diversity: Leveraging Virtual Machine Technology

Biologists have long recognized the dangers of the lack of diversity or monocultures in biological systems. Recently, it has been noted that much of the fragility of our networked computing systems can be attributed to the lack of diversity or monoculture of our software systems. The problem is severe. Because it is virtually inevitable that software will ship with flaws, our software monoculture leaves systems open to large-scale attacks by knowledgeable adversaries. Inspired by the resilience of diverse biological systems, the authors developed the Genesis Software Development Toolchain. An innovative aspect of Genesis is the use of an application-level virtual machine technology that enables the application of diversity transforms at any point in the software toolchain. Using Genesis, they authors demonstrated that diversity, when judiciously applied, is a practical and effective defense against two widely used types of attacks—return-to-libc and code injection.     

An Index Structure for Data Mining and Clustering

In this paper we present an index structure, called MetricMap, that takes a set of objects and a distance metric and then maps those objects to a k-dimensional space in such a way that the distances among objects are approximately preserved. The index structure is a useful tool for clustering and visualization in data-intensive applications, because it replaces expensive distance calculations by sum-of-square calculations. This can make clustering in large databases with expensive distance metrics practical. We compare the index structure with another data mining index structure, FastMap, recently proposed by Faloutsos and Lin, according to two criteria: relative error and clustering accuracy. For relative error, we show that (i) FastMap gives a lower relative error than MetricMap for Euclidean distances, (ii) MetricMap gives a lower relative error than FastMap for non-Euclidean distances (i.e., general distance metrics), and (iii) combining the two reduces the error yet further. A similar result is obtained when comparing the accuracy of clustering. These results hold for different data sizes. The main qualitative conclusion is that these two index structures capture complementary information about distance metrics and therefore can be used together to great benefit. The net effect is that multi-day computations can be done in minutes. Received February 1998 / Revised July 1999 / Accepted in revised form September 1999     

Interoperability and Electronic Commerce: A New Policy Framework for Evaluating Strategic Options

Enthusiasm for the anticipated social dividends of the Internet appears boundless. Indeed, the Internet is expected to do no less than virtually transform society. Yet even as the Internet races ambitiously toward critical mass, some social scientists are beginning to examine carefully the policy implications of current demographic patterns of Internet access and usage. Key demographic variables like income and education drive the policy questions surrounding the Internet because they are the most likely have a differential impact on the consequences of interactive electronic media for different segments in our society. Given these concerns, we set out to conduct a systematic investigation of the differences between whites and African Americans in the United States with respect to computer access, the primary current prerequisite for Internet access, and Web use. We wished to examine whether observed race differences in access and use can be accounted for by differences in income and education, how access influences use, and when race matters in the calculus of equal access. The particular emphasis of this research is on how such differences may be changing over time. We believe our results may be used as a window through which policymakers might view the job of ensuring access to the Internet for the next generation.     

Pointing in the third-person: an exploration of human motion and visual pointing aids for 3D virtual mirrors

Virtual Reality - A “virtual mirror” is a promising interface for virtual or augmented reality applications in which users benefit from seeing themselves within the environment, such as...     

Improving brain B0 shimming using an easy and accessible multi-coil shim array at ultra-high field

Object

Improve shimming capabilities of ultra-high field systems, with addition of an accessible low-complexity B₀ shim array for head MRI at 7 T.

Materials and methods

An eight channel B₀ shim coil array was designed as a tradeoff between shimming improvement and construction complexity, to provide an easy to use shim array that can be employed with the standard 7 T head coil. The array was interfaced using an open-source eight-channel shim amplifier rack. Improvements in field homogeneity for whole-brain and slice-based shimming were compared to standard second-order shimming, and to more complex higher order dynamic shimming and shim arrays with 32 and 48 channels.

Results

The eight-channel shim array provided 12% improvement in whole brain static shimming and provided 33% improvement when using slice-based shimming. With this, the eight-channel array performed similar to third-order dynamic shimming (without the need for higher order eddy current compensation). More complex shim arrays with 32 and 48 channels performed better, but require a dedicated RF coil.

Discussion

The designed eight-channel shim array provides a low-complexity and low-cost approach for improving B₀ field shimming on an ultra-high field system. In both static and dynamic shimming, it provides improved B₀ homogeneity over standard shimming.

     

Buoyant Jets of Elliptic Shape: Approximation for Duckbill Valves

The intrusion of seawater into a pipeline servicing an ocean outfall can significantly reduce its operational efficiency. Duckbill valves are sometimes installed on sewage outlet ports to help prevent such intrusions. While there is growing literature associated with the hydraulics of duckbill valves, there appears to be little published information on the trajectory and dilution achieved by the buoyant jets when the outlet ports are fitted with duckbill valves. Further, no models presently exist that incorporate the effects on the rise and dilution of buoyant jets discharged through orifices fitted with duckbill valves for which the size and shape of the opening varies with the effluent flow. Solutions to the asymptotic equations for jets and plumes are generated for ports fitted with duckbill valves by assuming that the shape of the duckbill is elliptical. This allows asymptotic expressions to be generated for the trajectory and dilution of the jet/plume. In the limiting case when the ellipse becomes circular, these expressions reduce to those for discharges from round outlets and are consistent with expressions for round ports found in literature.     

Generic programming techniques for parallelizing and extending procedural finite element programs

We outline an approach for extending procedural finite-element software components using generic programming. A layer of generic software components consisting of C++ containers and algorithms is used for parallelization of the finite-element solver and for solver coupling in multi-physics applications. The advantages of generic programming in connection with finite-element codes are discussed and compared with those of object-oriented programming. The use of the proposed generic programming techniques is demonstrated in a tutorial fashion through basic illustrative examples as well as code excerpts from a large-scale finite-element program for serial and parallel computing platforms.