How Fast Can You Escape a Compact Polytope?

The Continuous Polytope Escape Problem (CPEP) asks whether every trajectory of a linear differential equation initialised within a convex polytope eventually escapes the polytope. We provide a polynomial-time algorithm to decide CPEP for compact polytopes. We also establish a quantitative uniform upper bound on the time required for every trajectory to escape the given polytope. In addition, we establish iteration bounds for termination of discrete linear loops via reduction to the continuous case

The History of Nebraska Public School Reorganization Over the Past 30 Years and How This History Might be Used to Predict Nebraska School Reorganization in the Future: A Mixed Methods Study

The purpose of this study was to examine the history of reorganization in public schools in Nebraska over the past 30 years and how we can use this history to make predictions for the future of reorganization in public schools in Nebraska. The researcher used a mixed method approach. For the quantitative research 199 Nebraska superintendents were surveyed to determine the reasons for their school districts reorganization over the past 30 years. For the qualitative research, eight individuals were interviewed to gauge their perceptions of public school reorganization in Nebraska. These eight individuals were experts in public school education in Nebraska. The survey results showed that reorganization impacted school enrollment and school finances did not seem to be a major factor as to why districts reorganized. Additionally, results showed the legislature does not really have an impact on reorganization as well. There was a minimal effect from reorganization upon improving student opportunities, however, it did not take away opportunities from students. Reorganization has a positive effect on staffing as districts usually gain teachers and they do not normally lose their jobs. For the most part, reorganization was positive for the community. Based on the interview results Nebraska will continue to see a de-population of rural areas, which may negatively impact enrollment in schools. There will continue to be less need for more workers in agriculture, which will impact enrollment in rural areas. Rural communities and school districts prefer local control and that the legislature not be involved in reorganization in the future. However, there may be a need for a reorganization study to be conducted so the legislature better understands the needs of school districts rather than basing decisions on emotion. Advisor: Jody Isernhage

On the Complexity of the Escape Problem for Linear Dynamical Systems over Compact Semialgebraic Sets

We study the computational complexity of the Escape Problem for discrete-time linear dynamical systems over compact semialgebraic sets, or equivalently the Termination Problem for affine loops with compact semialgebraic guard sets. Consider the fragment of the theory of the reals consisting of negation-free ? ?-sentences without strict inequalities. We derive several equivalent characterisations of the associated complexity class which demonstrate its robustness and illustrate its expressive power. We show that the Compact Escape Problem is complete for this class

On rationality of nonnegative matrix factorization

Nonnegative matrix factorization (NMF) is the problem of decomposing a given nonnegative n × m matrix M into a product of a nonnegative n × d matrix W and a nonnegative d × m matrix H. NMF has a wide variety of applications, including bioinformatics, chemometrics, communication complexity, machine learning, polyhedral combinatorics, among many others. A longstanding open question, posed by Cohen and Rothblum in 1993, is whether every rational matrix M has an NMF with minimal d whose factors W and H are also rational. We answer this question negatively, by exhibiting a matrix M for which W and H require irrational entries. As an application of this result, we show that state minimization of labeled Markov chains can require the introduction of irrational transition probabilities. We complement these irrationality results with an NP- complete version of NMF for which rational numbers suffice

Hazardous Waste in The Netherlands: Dutch Policies from a Local Perspective

This paper is about risk management and environmental policy. Conventional approaches to risk management (Wynne et al., IIASA Working Papers on Hazardous Waste Management) tend to assume that risk is a technical phenomenon, and that successful risk management involves the elaboration and use of precise technical analytic models and regulatory instruments. The aim of this work is to show that this general approach is unrealistic. Firstly, it is shown that different perceptions and definitions of policy issues shape legislative and regulatory agendas in ways which mean that environmental management and specific definitions of risk problems are only a (varying) part of the broader agendas and concerns of interacting groups. Secondly, it is shown that even after apparently precise regulations have been established, the process of implementation effectively continues the negotiation of the basic agenda of issues as defined by different interests. This is shown to be the case at national and local levels. The family of Dutch case studies presented supports the argument of the IIASA hazardous waste papers, that effective regulatory instruments can only be identified in the context of interaction between the institutional realities of regulatory decision making and appropriate forms of technical knowledge. These vary from one regulatory system to another, making technical harmonization extremely problematic

The Pseudo-Skolem Problem is Decidable

We study fundamental decision problems on linear dynamical systems in discrete time. We focus on pseudo-orbits, the collection of trajectories of the dynamical system for which there is an arbitrarily small perturbation at each step. Pseudo-orbits are generalizations of orbits in the topological theory of dynamical systems. We study the pseudo-orbit problem, whether a state belongs to the pseudo-orbit of another state, and the pseudo-Skolem problem, whether a hyperplane is reachable by an ?-pseudo-orbit for every ?. These problems are analogous to the well-studied orbit problem and Skolem problem on unperturbed dynamical systems. Our main results show that the pseudo-orbit problem is decidable in polynomial time and the Skolem problem on pseudo-orbits is decidable. The former extends the seminal result of Kannan and Lipton from orbits to pseudo-orbits. The latter is in contrast to the Skolem problem for linear dynamical systems, which remains open for proper orbits

Risk perceptions about personal Internet-of-Things: Research directions from a multi-panel Delphi study

Internet-of-Things (IoT) research has primarily focused on identifying IoT devices\u27 organizational risks with little attention to consumer perceptions about IoT device risks. The purpose of this study is to understand consumer risk perceptions for personal IoT devices and translate these perceptions into guidance for future research directions. We conduct a sequential, mixed-methods study using multi-panel Delphi and thematic analysis techniques to understand consumer risk perceptions. The results identify four themes focused on data exposure and user experiences within IoT devices. Our thematic analysis also identified several emerging risks associated with the evolution of IoT device functionality and its potential positioning as a resource for malicious actors to conduct security attacks

Energy End-Use : Industry

The industrial sector accounts for about 30% of the global final energy use and accounts for about 115 EJ of final energy use in 2005. 1Cement, iron and steel, chemicals, pulp and paper and aluminum are key energy intensive materials that account for more than half the global industrial use. There is a shift in the primary materials production with developing countries accounting for the majority of the production capacity. China and India have high growth rates in the production of energy intensive materials like cement, fertilizers and steel (12–20%/yr). In different economies materials demand is seen to grow initially with income and then stabilize. For instance in industrialized countries consumption of steel seems to saturate at about 500 kg/capita and 400–500 kg/capita for cement. The aggregate energy intensities in the industrial sectors in different countries have shown steady declines – due to an improvement in energy efficiency and a change in the structure of the industrial output. As an example for the EU-27 the final energy use by industry has remained almost constant (13.4 EJ) at 1990 levels. Structural changes in the economies explain 30% of the reduction in energy intensity with the remaining due to energy efficiency improvements. In different industrial sectors adopting the best achievable technology can result in a saving of 10–30% below the current average. An analysis of cost cutting measures for motors and steam systems in 2005 indicates energy savings potentials of 2.2 EJ for motors and 3.3 EJ for steam. The payback period for these measures range from less than 9 months to 4 years. A systematic analysis of materials and energy flows indicates significant potential for process integration, heat pumps and cogeneration for example savings of 30% are seen in kraft, sulfite, dairy, chocolate, ammonia, and vinyl chloride. An exergy analysis (second law of thermodynamics) reveals that the overall global industry efficiency is only 30%. It is clear that there are major energy efficiency improvements possible through research and development (R&D) in next generation processes. A comparison of energy management policies in different countries and a summary of country experiences, program impacts for Brazil, China, India, South Africa shows the features of successful policies. Energy management International Organization for Standardization (ISO) standards are likely to be effective in facilitating industrial end use efficiency. The effective use of demand side management can be facilitated by combination of mandated measures and market strategies. A frozen efficiency scenario is constructed for industry in 2030. This implies a demand of final energy of 225 EJ in 2030. This involves an increase of the industrial energy output (in terms of Manufacturing Value Added (MVA)) by 95% over its 2005 value. Due to normal efficiency improvements the Business as Usual scenario results in a final energy demand of 175 EJ. The savings possibilities in motors and steam systems, process improvements, pinch, heat pumping and cogeneration have been computed for the existing industrial stock and for the new industries. An energy efficient scenario for 2030 has been constructed with a 95% increase in the industrial output with only a 17% increase in the final energy demand (total final energy demand for industry (135 EJ)). The total direct and indirect carbon dioxide emissions from the industry sector in 2005 is about 9.9 GtCO 2 . Assuming a constant carbon intensity of energy use, the business as usual scenario results in carbon dioxide (CO 2 ) emissions increasing to 17.8 GtCO 2 annually in 2030. In the energy efficient scenario this reduces to 11.6 GtCO 2 . Renewables account for 9% of the final energy of industry (10 EJ in 2005). If an aggressive renewables strategy resulting in an increase in renewable energy supply to 23% in 2030 is targeted (23 EJ), it is possible to have a scenario of constant greenhouse gas (GHG) emissions by the industrial sector (at 2005 levels) with a 95% increase in the industrial output. Several interventions will be required to achieve the energy efficient or constant GHG emission scenario. For the existing industry measures include developing capacity for systems assessment for motors, steam systems and pinch analysis, sharing and documentation of best practices, benchmarks and roadmaps for different industry segments, access to low interest finance etc. A new energy management standard has been developed by ISO for energy management in companies. Its adoption will enable industries to systematically monitor and track energy efficiency improvements. In order to level the playing field for energy efficiency a paradigm shift is required with the focus on energy services not on energy supply per se. This requires a re-orientation of energy supply, distribution companies and energy equipment manufacturing companies. Planning for next generation processes and systems needs the development of long term research agenda and strategic collaborations between industry, academic and research institutions and governments

Engaging homeless service providers in educational efforts during a tuberculosis outbreak in Atlanta

Background: During an outbreak of tuberculosis (TB) in the homeless population of metropolitan Atlanta, education of homeless service providers (HSPs) about the implementation of local infection control measures was imperative to limiting the spread of TB and to preventing future outbreaks. Methods: By use of educational sessions and teaching posters, two interventions were designed to focus educational efforts from November 2014 to August 2015: 1) a spatially-targeted approach that identified HSPs within an area of Fulton County, GA (which includes downtown Atlanta) with high TB case density (cases per square mile) from 2009 – 2014, and 2) an organizational meeting approach that included scheduled meetings of professionals who had regular contact with homeless individuals at risk of TB infection. Results: Of the 18 HSPs targeted in the identified high-TB density area, 9 engaged in educational activities, and 9 were closed at time of contact or unreachable by email or phone. Through organizational meetings, 36 additional facilities were reached. Conclusions: The HSPs with successful contact were amenable to educational efforts, and a combination of spatially targeted and organizational meeting approaches with teaching aids was feasible in developing sustainable TB educational programs in the homeless communit