One cannot manage information quality (IQ) without first being able to measure it meaningfully and establishing a causal connection between the source of IQ change, the IQ problem types, the types of activities affected, and their implications. In this article we propose a general IQ assessment framework. In contrast to context-specific IQ assessment models, which usually focus on a few variables determined by local needs, our framework consists of comprehensive typologies of IQ problems, related activities, and a taxonomy of IQ dimensions organized in a systematic way based on sound theories and practices. The framework can be used as a knowledge resource and as a guide for developing IQ measurement models for many different settings. The framework was validated and refined by developing specific IQ measurement models for two large-scale collections of two large classes of information objects: Simple Dublin Core records and online encyclopedia articles. © 2007 Wiley Periodicals, Inc.

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A framework for information quality assessment

The health risks of space radiation are arguably the most serious challenge to space exploration, possibly preventing these missions due to safety concerns or increasing their costs to amounts beyond what would be acceptable. Radiation in space is substantially different from Earth: high-energy ($E$) and charge ($Z$) particles (HZE) provide the main contribution to the equivalent dose in deep space, whereas $\ensuremath{\gamma}$ rays and low-energy $\ensuremath{\alpha}$ particles are major contributors on Earth. This difference causes a high uncertainty on the estimated radiation health risk (including cancer and noncancer effects), and makes protection extremely difficult. In fact, shielding is very difficult in space: the very high energy of the cosmic rays and the severe mass constraints in spaceflight represent a serious hindrance to effective shielding. Here the physical basis of space radiation protection is described, including the most recent achievements in space radiation transport codes and shielding approaches. Although deterministic and Monte Carlo transport codes can now describe well the interaction of cosmic rays with matter, more accurate double-differential nuclear cross sections are needed to improve the codes. Energy deposition in biological molecules and related effects should also be developed to achieve accurate risk models for long-term exploratory missions. Passive shielding can be effective for solar particle events; however, it is limited for galactic cosmic rays (GCR). Active shielding would have to overcome challenging technical hurdles to protect against GCR. Thus, improved risk assessment and genetic and biomedical approaches are a more likely solution to GCR radiation protection issues.

Physical basis of radiation protection in space travel

The progress on developing models of the radiation environment since the 1960s is reviewed with emphasis on models that can be applied to predicting the performance of microelectronics used in spacecraft and instruments. Space, atmospheric, and ground environments are included. It is shown that models must be adapted continually to account for increased understanding of the dynamics of the radiation environment and the changes in microelectronics technology. The IEEE Nuclear and Space Radiation Effects Conference is a vital forum to report model progress to the radiation effects research community.

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Space, atmospheric, and terrestrial radiation environments

In this paper, we describe a Monte Carlo approach for estimating the frequency and character of single event effects based on a combination of physical modeling of discrete radiation events, device simulations to estimate charge transport and collection, and circuit simulations to determine the effect of the collected charge. A mathematical analysis of the procedure reveals it to be closely related to the rectangular parallelepiped (RPP) rate prediction method. The results of these simulations show that event-to-event variation may have a significant impact when predicting the single-event rate in advanced spacecraft electronics. Specific criteria for supplementing established RPP-based single event analysis with Monte Carlo computations are discussed.

Monte Carlo Simulation of Single Event Effects

The physical processes affecting the dynamics of the Earth’s particle radiation environment are reviewed along with scientific and engineering models developed for its description. The emphasis is on models that are either operational engineering models or models presently under development for this purpose. Three components of the radiation environment, i.e., galactic cosmic rays (GCRs), solar energetic particles (SEPs) and trapped radiation, are considered separately. In the case of SEP models, we make a distinction between statistical flux/fluence models and those aimed at forecasting events. Models of the effects of particle radiation on the atmosphere are also reviewed. Further, we summarize the main features of the models and discuss the main outstanding issues concerning the models and their possible use in operational space weather forecasting. We emphasize the need for continuing the development of physics-based models of the Earth’s particle radiation environment, and their validation with observational data, until the models are ready to be used for nowcasting and/or forecasting the dynamics of the environment.

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Dynamics of the Earth’s Particle Radiation Environment

CREME96 is an update of the Cosmic Ray on Micro-Electronics code, a widely-used suite of programs for creating numerical models of the ionizing-radiation environment in near-Earth orbits and for evaluating radiation effects in spacecraft. CREME96, which is now available over the World-Wide Web (WWW) at http://crsp3.nrl.navy.mil/creme96/, has many significant features, including: (1) improved models of the galactic cosmic ray, anomalous cosmic ray, and solar energetic particle ("flare") components of the near-Earth environment; (2) improved geomagnetic transmission calculations; (3) improved nuclear transport routines; (4) improved single-event upset (SEU) calculation techniques, for both proton-induced and direct-ionization-induced SEUs; and (5) an easy-to-use graphical interface, with extensive on-line tutorial information. In this paper we document some of these improvements.

B. Brownstein

Papers

CREME96: A Revision of the Cosmic Ray Effects on Micro-Electronics Code