Analysis and verification of an automatic document feeder

Modern copying machines are versatile and complex systems in which embedded software plays an essential role. The progress towards faster and more stable machines that can satisfy ever growing customers' needs, places strict requirements on the efficiency and quality of such software. In order to meet these requirements, the software should be well-designed and free of errors. Using modern formal verification techniques, software designs can be checked for errors and deadlocks so that their quality can be assessed and improved at an early stage of the development process. In this paper, we analyze the embedded software of an Automatic Document Feeder (ADF). ADFs are important components of copier machines. The ADF studied here is a prototype developed by Océ-Technologies B.V., a company that develops professional printing systems. We construct a model of the ADF in µcrl, a process algebra-based specification language, and express the system's requirements in the modal µ-calculus. Next, we use the µcrl and Cadp tool sets to check whether the system meets its requirements. This analysis reveals important errors in the ADF and we propose solutions to these problems. Also, we show that some requirements that engineers assumed to be valid, are too strict. We present slightly weaker versions of these requirements and show that these do hold. In this sense, in addition to finding errors in the ADF, our analysis also led to a better understanding of the behaviour the system

Expanding School Enrollment by Subsidizing Private Schools: Lessons from Bogotá

Many countries use tax revenues to subsidize private schools. Whether these policies meet social objectives depends, in part, on the relative quality of education provided by the two types of schools. We use data on elementary school students and their teachers in Bogotá, Colombia to examine difference in resource mixes and differences in the relative effectiveness of public and private schools. We find that, on average, the schools in the two sectors are equally effective. However, they produce education using very different resource combinations. Moreover, there are large differences in the effectiveness of schools in both sectors, especially in the private sector. The results of our analysis shed light on the quantity-quality tradeoff that governments in many developing countries face in deciding how to use scarce educational resources.

Rabbits (<i>Oryctolagus cuniculus</i> L.) in coastal dune grasslands

We describe a field experiment for examining the impact of wild rabbits (Oryctolagus cuniculus L.) on the vegetation in two Flemish coastal dune grasslands. When numerous, rabbits had a major impact on the vegetation. This impact can be considered positive in the case of the studied grasslands, as evidenced by a decreasing abundance by dominant grass species and a declining species richness. The decrease of the number of rabbits, due to VHS, may hence negatively affect dune grassland species richness. Introducing large herbivores can be part of the solution for preserving the dune grasslands, and this introduction may even have positive effects on rabbit populations through feeding facilitation

Apollo to Artemis: Mining 50-Year Old Records to Inform Future Human Lunar Landing Systems

Under the Artemis lunar exploration program, NASA is committed to landing American astronauts on the moon by 2024. While NASAs new Space Launch System rocket and Orion capsule will carry astronauts from Earth to the Gateway, the human lunar landing system has not yet been fully defined. As in the Apollo program, there are concerns for vehicle weight and internal volume such that seats may not be desirable, and standing during lunar descent and ascent may be a preferred engineering solution. With such a design, astronauts will experience +GZ (head-to-foot) accelerations during capsule accelerations, and it is unclear whether spaceflight deconditioned astronauts can tolerate these. Apollo astronauts stood during lunar descent and ascent, and the data contained in the early program records for those missions represent a unique resource that may provide insights to the cardiovascular stress associated with this human landing system design

Manifesto on Art, Design and Social Science - Method as Speculative Event.

Proposes that techniques from art and design can be used within social science research as part of a speculative methodology. Provides a set of heuristic principles for speculative method, characterizing it as processual, performative, playful, promising and propositional. Keywords: speculative, method, art, design, social science, researchn/