210 research outputs found

    Bottom-Up Shape Analysis

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    In this paper we present a new shape analysis algorithm. The key distinguishing aspect of our algorithm is that it is completely compositional, bottom-up and non-iterative. We present our algorithm as an inference system for computing Hoare triples summarizing heap manipulating programs. Our inference rules are compositional: Hoare triples for a compound statement are computed from the Hoare triples of its component statements. These inference rules are used as the basis for a bottom-up shape analysis of programs. Specifically, we present a logic of iterated separation formula (LISF) which uses the iterated separating conjunct of Reynolds [17] to represent program states. A key ingredient of our inference rules is a strong biabduction operation between two logical formulas. We describe sound strong bi-abduction and satisfiability decision procedures for LISF. We have built a prototype tool that implements these inference rules and have evaluated it on standard shape analysis benchmark programs. Preliminary results show that our tool can generate expressive summaries, which are complete functional specifications in many cases

    Innovation in smallholder farming in Africa: recent advances and recommendations: Proceedings of the International Workshop on Agricultural Innovation Systems in Africa (AISA)

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    In the wake of a series of recent international events and initiatives focusing on understanding and fostering innovation1, there is growing awareness and interest in applying and making sense of the Agricultural Innovation Systems (AIS) concepts and perspectives and what they offer for understanding and supporting innovation systems, processes and networks. This has particular relevance for African agriculture as it faces several challenges, such as increasing and intensifying food production in a sustainable way and nourishing its fast-growing population, adapting to the consequences of climate change, and finding its rightful place in an increasingly global and complex international scene. Several initiatives and programmes seeking answers to these questions jointly organised a series of events during a Week on Agricultural Innovation in Africa (WAIA) held in Nairobi, Kenya, on 25–31 May 2013, of which the international workshop on Agricultural Innovation Systems in Africa (AISA) on 29–31 May was a major part. Another key event during this week, was the Eastern African Farmer Innovation Fair (EAFIF) held on 28–29 May, which was linked to AISA

    Natural Resource Management Plan for Brookhaven National Laboratory

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    Evaluation of Industry Standard Turbulence Models on an Axisymmetric Supersonic Compression Corner

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    Reynolds-averaged Navier-Stokes computations of a shock-wave/boundary-layer interaction (SWBLI) created by a Mach 2.85 flow over an axisymmetric 30-degree compression corner were carried out. The objectives were to evaluate four turbulence models commonly used in industry, for SWBLIs, and to evaluate the suitability of this test case for use in further turbulence model benchmarking. The Spalart-Allmaras model, Menter's Baseline and Shear Stress Transport models, and a low-Reynolds number k- model were evaluated. Results indicate that the models do not accurately predict the separation location; with the SST model predicting the separation onset too early and the other models predicting the onset too late. Overall the Spalart-Allmaras model did the best job in matching the experimental data. However there is significant room for improvement, most notably in the prediction of the turbulent shear stress. Density data showed that the simulations did not accurately predict the thermal boundary layer upstream of the SWBLI. The effect of turbulent Prandtl number and wall temperature were studied in an attempt to improve this prediction and understand their effects on the interaction. The data showed that both parameters can significantly affect the separation size and location, but did not improve the agreement with the experiment. This case proved challenging to compute and should provide a good test for future turbulence modeling work

    Special Libraries, October 1953

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    Volume 44, Issue 8https://scholarworks.sjsu.edu/sla_sl_1953/1007/thumbnail.jp

    The Conductance of Some Polyvalent Electrolytes

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    A new compound, 1,3,5-triphenylbenzene-4\u27 ,4 ,4 \u27-trisulfonic acid, was synthesized by treating triphenylbenzene in 1,2-dichloroethane with chlorosulfonic acid. The reaction appears to be quantitative. Conductance measurements were then made on the sodium, potassium, and lanthanum salts of this new acid and of 1,3,5-benzenetrisulfonic acid. The choice of these acids was based on two factors: 1) the desire to prepare a 3-3 symmetrical unassociated electrolyte which would allow the determination of a more reliable equivalent ionic conductance value for La3+ and 2) an interest in using the Murphy-Cohen equation to determine solute parameters such as association constants if association is present. Conductance measurements were done in water at 25°C using the weight dilution technique and phoreograms of each salt were drawn. From the phoreograms of the sodium, potassium, and lanthanum salts of 1,3,5-triphenylbenzene-4\u27 ,4 ,4 \u27-trisulfonic acid values of ⋀∘ found are 99.35 (ohm-1-cm2-equiv-1), 122.65 (ohm-1-cm2-equiv-1), and 119.25 (ohm-1-cm2-equiv-1), respectively. The value of the limiting equivalent ionic conductance, λ∘-, of 1,3,5-triphenylbenzene-4\u27 ,4 ,4 \u27-trisulfonate ion found is 49.25 ± 0.1 (ohm-1-cm2-equiv-1). A value of λ∘+ for La3+ as determined from λ∘- is 70.0 (ohm-1-cm2-equiv-1). Similarly, ⋀∘\u27s for the sodium and potassium salts of 1,3,5-benzenetrisulfonic acid were found to be 80.69 (ohm-1-cm2-equiv) and 80.88 (ohm-1-cm2-equiv-1) respectively. The value of λ∘- for 1,3,5-benzenetrisulfonate ion was found to be 80.78 ± .1 (ohm-1-cm2-equiv-1). The Murphy-Cohen equation qualitatively shows these salts to be associated; however, there is a real possibility of very slight association

    Single Camera Photogrammetry MATLAB Solver Developed for Automation of the Oil Interferometry Process

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    Over the last 20 years, Gregory G. Zilliac of the NASA AMES Research Center has been in continuous development of a fringe-imaging skin friction PC application used in oil interferometry analysis. This application, CXWIN5G, allows users to analyze propagation of oil smears across an aerodynamic surface using photogrammetry. The purpose of this thesis is to investigate the feasibility of increasing the level of automation currently found in CXWIN5G by developing a MATLAB solver capable of determining oil smear geometry with minimal user input. There are two main automation goals of this thesis that are reflected in the core of the MATLAB solver: the determination of oil smear centerline propagation without user input and the calculation of fringe spacing without the use of fiduciary markings on the test surface. In CXWIN5G, oil smear propagation centerlines must be drawn by a user with their computer mouse. The MATLAB solver removes the necessity for this by utilizing the centroid location of each fringe as a reference for centerline propagation. The solver’s ability to calculate fringe spacing without the use of fiduciary markings is a result of its ability to accurately determine the physical dimensions captured in an image. This is done by separating the camera’s field of view into its pixel components and calculating the horizontal and vertical object length captured in each pixel. Validation of the MATLAB solver’s ability to define fringe propagation and fringe spacing is performed at multiple different camera positions. When the camera location is not directly overhead an oil smear the camera is in a state of skew. Camera skew is measured in degrees, and can occur in the horizontal or vertical direction. Images analyzed in this thesis feature representative hand-drawn oil smears, as well as oil smears created in the Cal Poly 3’ x 4’ low speed wind tunnel. The MATLAB solver’s ability to create accurate centerlines is accessed by comparing pixel coordinates of the MATLAB centerlines with pixel coordinates of centerlines created on an identical image in Microsoft Paint. During experimentation, 18 images were analyzed under both horizontal (X) and vertical (Y) skew camera conditions, with skew angles ranging from zero to 13.2 degrees. Under X-skew camera conditions the average position error between MATLAB and hand drawn centerlines is 0.6 %, while average position error under Y-skew camera conditions is 1.0 %. Fringe spacing accuracy is defined by how closely fringe spacing determined by the MATLAB solver is to fringe spacing measured by hand with a 1/16th inch ruler. Spacing analysis is performed on the same photos used in centerline determination. For X-skew camera positions, the average fringe spacing error is 6.1 %, while the average spacing error in Y-skew conditions is 4.3 %. As is discussed in later sections of this text, the X-skew fringe spacing error is artificially inflated due to human error during data collection

    Research in interactive scene analysis

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    An interactive scene interpretation system (ISIS) was developed as a tool for constructing and experimenting with man-machine and automatic scene analysis methods tailored for particular image domains. A recently developed region analysis subsystem based on the paradigm of Brice and Fennema is described. Using this subsystem a series of experiments was conducted to determine good criteria for initially partitioning a scene into atomic regions and for merging these regions into a final partition of the scene along object boundaries. Semantic (problem-dependent) knowledge is essential for complete, correct partitions of complex real-world scenes. An interactive approach to semantic scene segmentation was developed and demonstrated on both landscape and indoor scenes. This approach provides a reasonable methodology for segmenting scenes that cannot be processed completely automatically, and is a promising basis for a future automatic system. A program is described that can automatically generate strategies for finding specific objects in a scene based on manually designated pictorial examples
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