Rockets: Physical science teacher's guide with activities

This guide begins with background information sections on the history of rocketry, scientific principles, and practical rocketry. The sections on scientific principles and practical rocketry are based on Isaac Newton's three laws of motion. These laws explain why rockets work and how to make them more efficient. The background sections are followed with a series of physical science activities that demonstrate the basic science of rocketry. Each activity is designed to be simple and take advantage of inexpensive materials. Construction diagrams, materials and tools lists, and instructions are included. A brief discussion elaborates on the concepts covered in the activities and is followed with teaching notes and discussion questions. The guide concludes with a glossary of terms, suggested reading list, NASA educational resources, and an evaluation questionnaire with a mailer

Proceedings of the 2nd Annual Conference on NASA/University Advanced Space Design Program

Topics discussed include: lunar transportation system, Mars rover, lunar fiberglass production, geosynchronous space stations, regenerative system for growing plants, lunar mining devices, lunar oxygen transporation system, mobile remote manipulator system, Mars exploration, launch/landing facility for a lunar base, and multi-megawatt nuclear power system

Improving the uptake of flood resilience at the individual property level

© 2016 WIT Press. One of the drivers for improving resilience to flooding at property level (also known as adoption of a 'water entry strategy') was demonstrated by the overtopping of hard engineered flood defences across Cumbria, UK during 'Storm Desmond' in December 2015. Although the uptake of water exclusion strategies (also termed 'flood resistance) is gradually improving in the UK, the longer term resilience options that permit water entry are less popular. Findings from an evidence assessment of the barriers and drivers to uptake of low-cost water entry strategy options are presented. Evidence was collected using a Rapid Evidence Assessment of published materials, semi-structured interviews and workshops with professionals, and a series of case studies of properties that had been adapted to flood risk. Factors leading to successful implementation are identified and illustrated by case study material from homes and small businesses. Water entry and water exclusion approaches were found to be seen as two methods used as part of an integrated approach that can bring about important co-benefits such as improved thermal efficiency and lower energy bills

Effects of Mixing Sequence of Polypropylene Fibers on Spalling Resistance of Normal Strength Concrete

This paper presents an experimental study on the spalling resistance of normal strength concrete with different mixing sequences of polypropylene (PP) fibers subjected to fire. The mixing sequences of PP fibers in concrete mixture investigated are: (1) mixing PP fibers with fresh concrete; (2) mixing PP fibers with coarse aggregates; and (3) mixing PP fibers with fine aggregates. According to the test results, the degree of concrete spalling is reduced for specimens containing PP fibers at 0.2% by volume in the concrete mixture. The beneficial effect on spalling resistance is maximized when the PP fibers are mixed with fresh concrete and when the PP fibers are mixed with fine aggregates. The results are confirmed using scanning electron microscope (SEM) to investigate the dispersion of PP fibers in hardened concrete. In the case of mixing PP fibers with fine aggregates, smaller amount of superplasticizer is needed to obtain the target slump, and it is therefore recommended for practical use

RacerD: compositional static race detection

Automatic static detection of data races is one of the most basic problems in reasoning about concurrency. We present RacerD—a static program analysis for detecting data races in Java programs which is fast, can scale to large code, and has proven effective in an industrial software engineering scenario. To our knowledge, RacerD is the first inter-procedural, compositional data race detector which has been empirically shown to have non-trivial precision and impact. Due to its compositionality, it can analyze code changes quickly, and this allows it to perform continuous reasoning about a large, rapidly changing codebase as part of deployment within a continuous integration ecosystem. In contrast to previous static race detectors, its design favors reporting high-confidence bugs over ensuring their absence. RacerD has been in deployment for over a year at Facebook, where it has flagged over 2500 issues that have been fixed by developers before reaching production. It has been important in enabling the development of new code as well as fixing old code: it helped support the conversion of part of the main Facebook Android app from a single-threaded to a multi-threaded architecture. In this paper we describe RacerD’s design, implementation, deployment and impact

RacerD: compositional static race detection

Automatic static detection of data races is one of the most basic problems in reasoning about concurrency. We present RacerD—a static program analysis for detecting data races in Java programs which is fast, can scale to large code, and has proven effective in an industrial software engineering scenario. To our knowledge, RacerD is the first inter-procedural, compositional data race detector which has been empirically shown to have non-trivial precision and impact. Due to its compositionality, it can analyze code changes quickly, and this allows it to perform continuous reasoning about a large, rapidly changing codebase as part of deployment within a continuous integration ecosystem. In contrast to previous static race detectors, its design favors reporting high-confidence bugs over ensuring their absence. RacerD has been in deployment for over a year at Facebook, where it has flagged over 2500 issues that have been fixed by developers before reaching production. It has been important in enabling the development of new code as well as fixing old code: it helped support the conversion of part of the main Facebook Android app from a single-threaded to a multi-threaded architecture. In this paper we describe RacerD’s design, implementation, deployment and impact

Discussion meeting on Gossamer spacecraft (ultralightweight spacecraft)

Concepts, technology, and application of ultralightweight structures in space are examined. Gossamer spacecraft represented a generic class of space vehicles or structures characterized by a low mass per unit area (approximately 50g/m2). Gossamer concepts include the solar sail, the space tether, and various two and three dimensional large lightweight structures that were deployed or assembled in space. The Gossamer Spacecraft had a high potential for use as a transportation device (solar sail), as a science instrument (reflecting or occulting antenna), or as a large structural component for an enclosure, manned platform, or other human habitats. Inflatable structures were one possible building element for large ultralightweight structures in space

Verification of temporal properties involving multiple interacting objects

Defects that arise due to violating a prescribed order for executing statements or executing a disallowed sequence of statements can be hard to detect since the sequence is often spread over multiple functions and source code files. In this dissertation, we develop a verification tool which uses a sound and precise static analysis to verify temporal specifications that can involve multiple objects. Statically analyzing properties that involve multiple objects requires two separate abstractions; one that abstracts the objects in the program and the second which abstracts the state of a group of objects. We present two such abstractions. Objects are abstracted using a storeless heap abstraction. This provides flow-sensitive tracking of individual objects along control flow paths and precise may-alias information. The state abstraction leverages the object abstraction to abstract the state of a group of related objects. We use the IFDS algorithm to implement an analysis that computes the object and state abstractions. Since the original IFDS algorithm is not directly suitable for domains involving objects and pointers, we present four extensions to the original IFDS algorithm. We also present results of an empirical study to measure the precision of the analysis. The performance of the analysis is improved through the use of two types of method summaries. Callee summaries guarantee that using the summary instead of flow-sensitive analysis of the callee does not degrade the precision of the abstraction at the callsite for the callee. For further performance gains, caller summaries that make conservative assumptions for aliasing between parameters of a function call are used. We present results from empirically evaluating the use of these summaries for the object analysis. Finally, to make the analysis practical for use in the development life cycle, we present a verification tool to configure the analysis and visualize the results. The tool provides a number of configuration options to run the analysis. The analysis results are presented in a list displaying statements flagged as possible violations of a property and, for each violation, the sequence of events (statements) that lead to this violation