79 research outputs found

    Fuzzy logic controller and game theory based distributed energy resources allocation

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    Get Me Here: Using Verification Tools to Answer Developer Questions

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    ABSTRACT While working developers often struggle to answer reachability questions (e.g. How can execution reach this line of code? How can execution get into this state?), the research community has created analysis and verification technologies whose purpose is systematic exploration of program execution. In this paper, we show the feasibility of using verification tools to create a query engine that automatically answers certain kinds of reachability questions. For a simple query, a developer invokes the "Get Me Here" command on a line of code. Our tool uses an SMT-based static analysis to search for an execution that reaches that line of code. If the line is reachable, the tool visualizes the trace using a Code Bubbles representation to show the methods invoked, the lines executed within the methods and the values of variables. The Get Me Here tool also supports more complex queries where the user specifies a start point, intermediate points, and an end point, each of which can specify a predicate over the program's state at that point. We evaluate the tool on a set of three benchmark programs. We compare the performance of the tool with professional developers answering the same reachability questions. We conclude that the tool has sufficient accuracy, robustness and performance for future testing with professional users

    Superior mesenteric artery syndrome in an 18-year old female: case report

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    We report an unusual case of an 18-year old woman, who presented to Civil Hospital Karachi in May 2016 with complaints of vomiting, abdominal pain, dysphagia, altered bowel habits, loss of appetite and chronic weight loss. On examination, abdomen was found to be soft and non-tender with discomfort on breathing. CT angiogram revealed reduction of aortomesenteric angle and aortomesenteric distance which were both consistent with superior mesenteric artery syndrome. Reduction in angle was thought to be because of weight loss and adipose tissue depletion so patient was started on enteral and parenteral nutritional supplements. Upon seeing little to no improvement, duodenojejunostomy was performed and patient was kept under observation. Nutritional supplements were continued. The after procedure course was uneventful

    Reliable State Machines: A Framework for Programming Reliable Cloud Services

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    Building reliable applications for the cloud is challenging because of unpredictable failures during a program\u27s execution. This paper presents a programming framework, called Reliable State Machines (RSMs), that offers fault-tolerance by construction. In our framework, an application comprises several (possibly distributed) RSMs that communicate with each other via messages, much in the style of actor-based programming. Each RSM is fault-tolerant by design, thereby offering the illusion of being "always-alive". An RSM is guaranteed to process each input request exactly once, as one would expect in a failure-free environment. The RSM runtime automatically takes care of persisting state and rehydrating it on a failover. We present the core syntax and semantics of RSMs, along with a formal proof of failure-transparency. We provide a .NET implementation of the RSM framework for deploying services to Microsoft Azure. We carry out an extensive performance evaluation on micro-benchmarks to show that one can build high-throughput applications with RSMs. We also present a case study where we rewrite a significant part of a production cloud service using RSMs. The resulting service has simpler code and exhibits production-grade performance
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