Synthesizing framework uses from program behavior data

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 42-43).This thesis presents MATCHMAKER, a new synthesis tool that aims to help programmers use software frameworks by synthesizing source code needed to interact with the framework. Software engineers of today are constantly faced with the task of using or extending large software code bases. This proves to be a challenging endeavor, as object-oriented frameworks tend to grow exceedingly intricate. Functionality is spread out among numerous classes and tailoring it for a specific need requires knowledge of exact components to extend and combine. MATCHMAKER is presented to help programmers understand such complex behavior, especially, to help deal with one common task in using frameworks: connecting two classes so that they can interact with each other. Taking as input two classes that the programmer want to connect, MATCHMAKER observes many real runs of the framework, aggregates relevant execution traces in which similar connections are built by client-framework interactions, and synthesizes the necessary source code the user needs to write to make the connection possible. MATCHMAKER relies on the hypothesis that the logical connection between two objects is fulfilled by a chain of pointer references linking them together, and the earliest possible pointer reference chain (called Critical Chain) is critical to the logical connection. MATCHMAKER employs a new program behavior data engine (called DELIGHT) to find the critical chain, uses a special slicing algorithm to dig out the relevant instructions which form the client-framework protocol from the critical chain, and synthesize the client code from the slices. In this thesis we also demonstrate MATCHMAKER's capability on a range of programming tasks using complex software frameworks such as Eclipse, and evaluate MATCHMAKER's usability and its improvement to programming efficiency by comprehensive user study.by Zhilei Xu.S.M

Cosmology Large Angular Scale Surveyor (CLASS): Integration and Testing of CLASS at 40 GHz

The Cosmology Large Angular Scale Surveyor (CLASS) is an array of telescopes to observe Cosmic Microwave Background (CMB) polarization in Chile. CLASS will make large angular scale CMB polarization measurements in frequency bands at 40 GHz, 90 GHz, 150 GHz, and 220 GHz. The CLASS survey (started from 2016) will constrain the tensor-to-scalar ratio from the first moments of the universe and also provide critical data on cosmic reionization, the sum of neutrino masses, and the Galactic interstellar medium. In this thesis, the CLASS strategy and design are introduced. The optical filter system is described in details along with two testing devices, including a Fourier Transform Spectrometer (FTS) and an optics test cryostat. For the telescope mount system, a bottom-up introduction is provided focusing on individual components. Preliminary data analysis from the first observing season with the 40~GHz telescope is also described

Data-driven synthesis for object-oriented frameworks

Software construction today often involves the use of large frameworks. The challenge in this type of programming is that object-oriented frameworks tend to grow exceedingly intricate; they spread functionality among numerous classes, and any use of the framework requires knowledge of many interacting components. We present a system named MATCHMAKER that from a simple query synthesizes code that interacts with the framework. The query consists of names of two framework classes, and our system produces code enabling interaction between them. MATCHMAKER relies on a database of dynamic program traces called DELIGHT that uses novel abstraction-based indexing techniques to answer queries about the evolution of heap connectivity in a matter of seconds. The paper evaluates the performance and effectiveness of MATCHMAKER on a number of benchmarks from the Eclipse framework. The paper also presents the results of a user study that showed a 49% average productivity improvement from the use of our tool.National Science Foundation (U.S.). (Grant number CCF-1049406)Massachusetts Institute of Technology. Computer Science and Artificial Intelligence Laborator

Direct optimal mapping for 21 cm cosmology: A demonstration with the hydrogen epoch of reionization array

Motivated by the desire for wide-field images with well-defined statistical properties for 21 cm cosmology, we implement an optimal mapping pipeline that computes a maximum likelihood estimator for the sky using the interferometric measurement equation. We demonstrate this “direct optimal mapping” with data from the Hydrogen Epoch of Reionization (HERA) Phase I observations. After validating the pipeline with simulated data, we develop a maximum likelihood figure-of-merit for comparing four sky models at 166 MHz with a bandwidth of 100 kHz. The HERA data agree with the GLEAM catalogs (Wayth et al. 2015) to < 10%. After subtracting the GLEAM point sources, the HERA data discriminate between the different continuum sky models, providing most support for the model of Byrne et al. (2021). We report the computation cost for mapping the HERA Phase I data and project the computation for the HERA 320-antenna data; both are feasible with a modern server. The algorithm is broadly applicable to other interferometers and is valid for wide-field and non-coplanar arrays

The effects of inclination on a two stage pulse tube cryocooler for use with a ground based observatory

Abstract Ground-based observatories across a wide range of wavelengths implement cryogenic cooling techniques to increase the sensitivity of instruments and enable low temperature detector technologies. Commercial pulse tube cryocoolers (PTCs) are frequently used to provide 40 K and 4 K stages as thermal shells in scientific instruments. However, PTC operation is dependent on gravity, giving rise to changes in cooling capacity over the operational tilt range of pointed telescopes. We present a study of the performance of a two stage PTC with a cooling capacity of 1.8 W at 4.2 K and 50 W at 45 K (Cryomech PT420-RM) from 0 - 55 ° away from vertical to probe capacity as a function of angle over a set of realistic thermal loading conditions. Our study provides a method to extract temperature estimates given predicted thermal loading conditions across the angular range sampled. We then discuss the design implications for current and future tilted cryogenic systems

ProtoEM: A Prototype-Enhanced Matching Framework for Event Relation Extraction

Event Relation Extraction (ERE) aims to extract multiple kinds of relations among events in texts. However, existing methods singly categorize event relations as different classes, which are inadequately capturing the intrinsic semantics of these relations. To comprehensively understand their intrinsic semantics, in this paper, we obtain prototype representations for each type of event relation and propose a Prototype-Enhanced Matching (ProtoEM) framework for the joint extraction of multiple kinds of event relations. Specifically, ProtoEM extracts event relations in a two-step manner, i.e., prototype representing and prototype matching. In the first step, to capture the connotations of different event relations, ProtoEM utilizes examples to represent the prototypes corresponding to these relations. Subsequently, to capture the interdependence among event relations, it constructs a dependency graph for the prototypes corresponding to these relations and utilized a Graph Neural Network (GNN)-based module for modeling. In the second step, it obtains the representations of new event pairs and calculates their similarity with those prototypes obtained in the first step to evaluate which types of event relations they belong to. Experimental results on the MAVEN-ERE dataset demonstrate that the proposed ProtoEM framework can effectively represent the prototypes of event relations and further obtain a significant improvement over baseline models.Comment: Work in progres