514 research outputs found
Towards Distributed Memory Parallel Program Analysis
Our work presents a parallel attribute evaluation for distributed memory parallel
computer architectures where previously only shared memory parallel support for
this technique has been developed. Attribute evaluation is a part of how attribute
grammars are used for program analysis within modern compilers. Within this
work, we have extended ROSE, a open compiler infrastructure, with a distributed
memory parallel attribute evaluation mechanism to support user defined global
program analysis required for some forms of security analysis which can not be
addresses by a file by file view of large scale applications. As a result, user
defined security analyzes may now run in parallel without the user having to
specify the way data is communicated between processors. The automation of
communication enables an extensible open-source parallel program analysis
infrastructure
Cross-project simulation of construction productivity for caisson fabrication
The aims are to (a) predict crew productivity improvement due to the repetitive nature
of caisson fabrication as the result of on the job learning and (b) validate the previously specially built
simulation platform CaissonSim' in different projects. More specifically, two such marine projects one in
Greece and one in Cyprus have been studied
Additively manufacturable micro-mechanical logic gates.
Early examples of computers were almost exclusively based on mechanical devices. Although electronic computers became dominant in the past 60 years, recent advancements in three-dimensional micro-additive manufacturing technology provide new fabrication techniques for complex microstructures which have rekindled research interest in mechanical computations. Here we propose a new digital mechanical computation approach based on additively-manufacturable micro-mechanical logic gates. The proposed mechanical logic gates (i.e., NOT, AND, OR, NAND, and NOR gates) utilize multi-stable micro-flexures that buckle to perform Boolean computations based purely on mechanical forces and displacements with no electronic components. A key benefit of the proposed approach is that such systems can be additively fabricated as embedded parts of microarchitected metamaterials that are capable of interacting mechanically with their surrounding environment while processing and storing digital data internally without requiring electric power
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A Family of Flexures That Eliminate Underconstraint in Nested Large-Stroke Flexure Systems
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Design of Flexure-based Precision Transmission Mechanisms using Screw Theory
This paper enables the synthesis of flexure-based transmission mechanisms that possess multiple decoupled inputs and outputs of any type (e.g. rotations, translations, and/or screw motions), which are linked by designer-specified transmission ratios. A comprehensive library of geometric shapes is utilized from which every feasible concept that possesses the desired transmission characteristics may be rapidly conceptualized and compared before an optimal concept is selected. These geometric shapes represent the rigorous mathematics of screw theory and uniquely link a body's desired motions to the flexible constraints that enable those motions. This paper's impact is most significant to the design of nano-positioners, microscopy stages, optical mounts, and sensors. A flexure-based microscopy stage was designed, fabricated, and tested to demonstrate the utility of the theory
Safety and patient outcomes with lubiprostone for up to 52 weeks in patients with irritable bowel syndrome with constipation
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90244/1/apt4983.pd
Pt accelerated coarsening of A15 precipitates in Cr-Si alloys
The effect of alloying Cr-rich Cr-Si alloys with Pt was investigated by a combination of complementary experimental methods and atomic scale modelling. The investigated Cr-Si and Cr-Si-Pt (Cr ⩾86 at.%) alloys developed a two-phase microstructure consisting of Cr solid solution (Crss) matrix and strengthened by A15 precipitates during annealing at 1200\ub0C. It was found that additions of 2 at.% Pt increase the coarsening rate by almost five times considering annealing times up to 522 h. Pt was found to change the precipitate matrix orientation relationship, despite its low influence on the Crss matrix/A15 precipitate misfit. Through this experimental and modelling approach new insight has been gained into mechanisms of enhanced coarsening by Pt addition. The increased coarsening is principally attributed to a change in interface composition and structure resulting in different thermodynamic stabilities: Pt-containing A15 phase was found to have a broader compositional range if both elements, Pt and Si, are present compared to only Si. Additionally, the Crss phase was found to have a higher solubility of Pt and Si over just Si. Both factors additionally facilitated Ostwald ripening
Nonprofit governance: Improving performance in troubled economic times
Nonprofit management is currently pressured to perform effectively in a weak economy. Yet, nonprofit governance continues to suffer from unclear conceptions of the division of labor between board of directors and executive directors. This online survey of 114 executive directors aims to provide clarification and recommendations for social administration
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Support for Whole-Program Analysis and the Verification of the One-Definition Rule in C++
We present a compact and accurate representation of a whole-program abstract syntax tree, and use it to detect a specific security vulnerability in C++ programs known as a One-Definition Rule (ODR) violation. The ODR states that types and functions appearing in multiple compilation units must be defined identically. However, no current compiler can enforce ODR because doing so requires the ability to see the full application source at once; where ODR is violated, the program is incorrect. Moreover, a lack of ODR enforcement makes a program vulnerable to the so-called VPTR exploit, in which an object's virtual function table is replaced by malicious code. Our representation of the whole program preserves all features of the source for analysis and transformation, and permits a million-line application to fit entirely in the memory of a workstation with 1 GB of RAM
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