On Verifying Complex Properties using Symbolic Shape Analysis

One of the main challenges in the verification of software systems is the analysis of unbounded data structures with dynamic memory allocation, such as linked data structures and arrays. We describe Bohne, a new analysis for verifying data structures. Bohne verifies data structure operations and shows that 1) the operations preserve data structure invariants and 2) the operations satisfy their specifications expressed in terms of changes to the set of objects stored in the data structure. During the analysis, Bohne infers loop invariants in the form of disjunctions of universally quantified Boolean combinations of formulas. To synthesize loop invariants of this form, Bohne uses a combination of decision procedures for Monadic Second-Order Logic over trees, SMT-LIB decision procedures (currently CVC Lite), and an automated reasoner within the Isabelle interactive theorem prover. This architecture shows that synthesized loop invariants can serve as a useful communication mechanism between different decision procedures. Using Bohne, we have verified operations on data structures such as linked lists with iterators and back pointers, trees with and without parent pointers, two-level skip lists, array data structures, and sorted lists. We have deployed Bohne in the Hob and Jahob data structure analysis systems, enabling us to combine Bohne with analyses of data structure clients and apply it in the context of larger programs. This report describes the Bohne algorithm as well as techniques that Bohne uses to reduce the ammount of annotations and the running time of the analysis

A grammatical specification of human-computer dialogue

The Seeheim Model of human-computer interaction partitions an interactive application into a user-interface, a dialogue controller and the application itself. One of the formal techniques of implementing the dialogue controller is based on context-free grammars and automata. In this work, we modify an off-the-shelf compiler generator (YACC) to generate the dialogue controller. The dialogue controller is then integrated into the popular X-window system, to create an interactive-application generator. The actions of the user drive the automaton, which in turn controls the application

Molecular propensity as a driver for explorative reactivity studies

Quantum chemical studies of reactivity involve calculations on a large number of molecular structures and comparison of their energies. Already the set-up of these calculations limits the scope of the results that one will obtain, because several system-specific variables such as the charge and spin need to be set prior to the calculation. For a reliable exploration of reaction mechanisms, a considerable number of calculations with varying global parameters must be taken into account, or important facts about the reactivity of the system under consideration can go undetected. For example, one could miss crossings of potential energy surfaces for different spin states or might not note that a molecule is prone to oxidation. Here, we introduce the concept of molecular propensity to account for the predisposition of a molecular system to react across different electronic states in certain nuclear configurations. Within our real-time quantum chemistry framework, we developed an algorithm that allows us to be alerted to such a propensity of a system under consideration.Comment: 10 pages, 7 figure

Policies for capacity development

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What Works at Scale? Distilling the Critical Success Factors for Scaling Up Rural Sanitation

This paper is based on the Knowledge Sharing Forum of the same name. It examines the conditions for success in sanitation programs and strategies that lead to robust implementation in various countries

Effects of environmentally imposed roughness on airfoil performance

The experimental evidence for the effects of rain, insects, and ice on airfoil performance are examined. The extent to which the available information can be incorporated in a calculation method in terms of change of shape and surface roughness is discussed. The methods described are based on the interactive boundary procedure of Cebeci or on the thin layer Navier Stokes procedure developed at NASA. Cases presented show that extensive flow separation occurs on the rough surfaces

EPA's Office of Wetlands, Oceans and Watersheds

This agency portal provides background information on habitats from streams and rivers, lakes, wetlands and estuaries to rocky coasts, sandy beaches, coral reefs and ocean environments, their importance, monitoring and assessment programs, regulations and protection. Also features databases and mapping links, publications, kids activities and teacher resources on water and aquatic environments, project grants and training opportunities. Posts government announcements and policy reports and links to watershed-related projects by partnership agencies and organizations. Educational levels: Middle school, High school

Political Economy of Renewable Energy Deployment in India: Case Study of Karnataka

Over the past few years, India has paid considerable attention to the development of its Renewable Energy (RE) capacity. This can be attributed to the country's energy security concerns, necessity to provide reliable electricity to its citizens and the global need to mitigate climate change. India's ambitious targets project that by 2020, 10 per cent of its power shall come from renewable sources and by 2022 there will be 165 GW of RE capacity installed. Of this target capacity, there will be a 100 GW of installed solar capacity, 60 MW from wind and 5 MW from other sources such as small hydro and bioenergy (Vashishtha 2014). This implies that within the next five years, India has to undertake the mammoth task of almost doubling its RE contribution to the energy mix from the current 6 per cent. The solar sector faces the largest challenge of scaling up its capacity by almost 20 times in six years, from the current 4.7 GW (MNRE 2016).Such tremendous growth can only be accomplished through an effective policy and regulatory framework, which is essential to incentivise the deployment of RE. Pegels and Lu?tkenhorst (2014) state that government intervention is particularly necessary for energy policy because market mechanisms such as falling prices alone are not sufficient to ensure the development of long-term sustainable infrastructure. They further say that as a nation's energy policy determines the future of the basic public services, it is important to have a holistic view from the political, socio-economic and technological aspects. In India however, RE policy interventions have not taken such a holistic approach. Current national policies such as preferential-grid access, Feed in Tariffs (FiT), Renewable Purchase Obligations (RPO) on utilities, tax holidays, RE Certificate (REC) trading and Accelerated Depreciation (AD) only address techno-economic barriers. While these are surely important incentives, in the past they haven't been sufficient for Indian states to meet their RE targets. Further, it appears unlikely that India will manage to meet its FY 16 targets in the next few months looking at the large gap between target and achievement (Figure 1). does India need to do to ensure that it's RE aspirations do not remain a pipedream? As Sreekumar and Chitnis (2014) point out, in order to have a complete idea of the electricity sector, in addition to techno-economic considerations, a political perspective is also imperative. Hence, this article attempts to answer the question posed above by providing insights into the political economy of the RE sector in India. Key observations from an extensive stakeholder consultation (n=20) conducted in the Indian state of Karnataka have been used in this study (CSTEP 2014).This case study revealed that despite high targets and two comprehensive RE policies (GoK 2014; GoK 2010) the deployment of RE technologies has faced significant barriers in Karnataka during the past five years. The state was unable to meet its targets for RE capacity installation in all renewable sources (biomass, wind, solar, small-hydro) that were laid down in the Karnataka 2009-2014 RE policy. Although the state did have an impressive 10 per cent of its electricity from RE sources in Financial Year (FY) '13, there was an unmet peak demand of 1.4 GW and electricity deficit of 14 per cent (CSTEP 2013)