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Computational Engineering Commons

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University of Massachusetts Amherst

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Articles 1 - 12 of 12

Full-Text Articles in Computational Engineering

A Combined Quadtree/Delaunay Method For 2d Mesh Generation, Simon Tang Jan 2012

A Combined Quadtree/Delaunay Method For 2d Mesh Generation, Simon Tang

Masters Theses 1911 - February 2014

Unstructured simplicial mesh is an integral and critical part of many computational electromagnetics methods (CEM) such as the finite element method (FEM) and the boundary element method (BEM). Mesh quality and robustness have direct impact on the success of these CEM methods.

A combined quadtree/Delunay 2D mesh generator, based on the early work of Schroeder (1991, PhD), is presented. The method produces a triangulation that approximates the original geometric model but is also topologically consistent. The key advantages of the method are: (a) its robustness, (b) ability to create a-priori graded meshes, and (c) its guaranteed mesh quality.

The ...


A Numerical Study On Hydraulic Characteristics In The Ice Harbor-Type Fishway, Seojun Kim, Kwonkyu Yu, Byungman Yoon, Yoonsung Lim Jan 2012

A Numerical Study On Hydraulic Characteristics In The Ice Harbor-Type Fishway, Seojun Kim, Kwonkyu Yu, Byungman Yoon, Yoonsung Lim

Journal Articles

Recently various types of fishways have been developed and constructed in order to preserve diversity of fish species and restore the riverine ecological system. Some of the fishways in Korea, however, seem to be designed and installed without careful study on their functions and swimming characteristics of target fishes. The present study aims to elucidate proper hydraulic characteristics of the Ice Harbor-type fishway. In the present study, we analyzed the hydraulic characteristics depending on changes in the spans of walls in the Ice Harbor-type fishways, by using Flow-3D, a three dimensional numerical simulation program. Two physical experiments were performed to ...


High Speed Flow Simulation In Fuel Injector Nozzles, Sukanta Rakshit Jan 2012

High Speed Flow Simulation In Fuel Injector Nozzles, Sukanta Rakshit

Masters Theses 1911 - February 2014

Atomization of fuel is essential in controlling combustion inside a direct injection engine. Controlling combustion helps in reducing emissions and boosting efficiency. Cavitation is one of the factors that significantly affect the nature of spray in a combustion chamber. Typical fuel injector nozzles are small and operate at a very high pressure, which limit the study of internal nozzle behavior. The time and length scales further limit the experimental study of a fuel injector nozzle. Simulating cavitation in a fuel injector will help in understanding the phenomenon and will assist in further development.

The construction of any simulation of cavitating ...


News Media Environment, Selective Perception, And The Survival Of Preference Diversity Within Communication Networks, Frank C.S. Liu, Paul E. Johnson May 2011

News Media Environment, Selective Perception, And The Survival Of Preference Diversity Within Communication Networks, Frank C.S. Liu, Paul E. Johnson

JITP 2011: The Future of Computational Social Science

There is a natural tension between the effects on public opinion of social networks and the news media. It is widely believed that social networks tend to harmonize opinions within them, but the presence of media may accentuate diversity by inserting discordant messages. On the other hand, in a totalitarian state where the government controls the media, social networks may mitigate the homogenizing pressure of a regime’s propaganda. The tendency of opinion to follow the “official line” may be mitigated because opponents of the government interact on a personal level and bolster one another’s views. This paper employs ...


Infoextractor – A Tool For Social Media Data Mining, Chirag Shah, Charles File Jan 2011

Infoextractor – A Tool For Social Media Data Mining, Chirag Shah, Charles File

JITP 2011: The Future of Computational Social Science

We present InfoExtractor, a web-based tool for collecting data and metadata from focused social media content. InfoExtractor then provides this data in various structured and unstructured formats for easy manipulation and analysis. The tool allows social science researchers to easily collect data for quantitative analysis, and is designed to deliver data from popular and influential social media sites in a useful and easy to access way. InfoExtractor was designed to replace traditional means of content aggregation, such as page scraping and brute- force copying.


Tradeoffs In Accuracy And Efficiency In Supervised Learning Methods, Loren Collingwood, John Wilkerson Jan 2011

Tradeoffs In Accuracy And Efficiency In Supervised Learning Methods, Loren Collingwood, John Wilkerson

JITP 2011: The Future of Computational Social Science

Text is becoming a central source of data for social science research. With advances in digitization and open records practices, the central challenge has in large part shifted away from availability to usability. Automated text classification methodologies are becoming increasingly important within political science because they hold the promise of substantially reducing the costs of converting text to data for a variety of tasks. In this paper, we consider a number of questions of interest to prospective users of supervised learning methods, which are appropriate to classification tasks where known categories are applied. For the right task, supervised learning methods ...


Researching Real-World Web Use With Roxy, A Research Proxy, Ericka Menchen-Trevino, Chris Karr Jan 2011

Researching Real-World Web Use With Roxy, A Research Proxy, Ericka Menchen-Trevino, Chris Karr

JITP 2011: The Future of Computational Social Science

Outside of a lab environment, it has been difficult for researchers to collect both behavioral and self-reported Web-use data from the same participants. To address this challenge we created Roxy, open source software that collects real-world Web-use data with participants’ informed consent. Roxy gathers Web log data as well as the text and HTML code of each page visited by participants. We describe Roxy’s data gathering capabilities and search functions and then illustrate how we used the software in a multi-method study. The use case examines selective exposure to political communication during the November 2010 U.S. general election ...


An Automated Snowball Census Of The Political Web, Abe Gong Jan 2011

An Automated Snowball Census Of The Political Web, Abe Gong

JITP 2011: The Future of Computational Social Science

This paper solves a persistent methodological problem for social scientists studying the political web: representative sampling. Virtu- ally all existing studies of the political web are based on incomplete samples, and therefore lack generalizability. In this paper, I combine methods from computer science and sampling theory to conduct an automated snowball census of the political web and constructs an all- but-complete index of English political websites. I check the robust- ness of this index, use it to generate descriptive statistics for the entire political web, and demonstrate that studies based on ad hoc sampling strategies are likely to be biased ...


Facilitating Encounters With Political Difference: Engaging Voters With The Living Voters Guide, Deen G. Freelon, Travis Kriplean, John Morgan, W. Lance Bennett, Alan Borning Jan 2011

Facilitating Encounters With Political Difference: Engaging Voters With The Living Voters Guide, Deen G. Freelon, Travis Kriplean, John Morgan, W. Lance Bennett, Alan Borning

JITP 2011: The Future of Computational Social Science

Unlike 20th-century mass media, the Internet requires self-selection of content by its very nature. This has raised the normative concern that users may opt to encounter only political information and perspectives that accord with their preexisting views. This study examines the different ways that voters appropriated a new, purpose-built online engagement platform to engage with a wide variety of political opinions and arguments. In a deployment aimed at helping Washington state citizens make their 2010 election decisions, we find that users take significant advantage of three key opportunities to engage with political diversity: reading, acknowledging, and writing arguments on both ...


Politics 2.0 With Facebook – Collecting And Analyzing Public Comments On Facebook For Studying Political Discourses, Chirag Shah, Tayebeh Yazdani Nia Jan 2011

Politics 2.0 With Facebook – Collecting And Analyzing Public Comments On Facebook For Studying Political Discourses, Chirag Shah, Tayebeh Yazdani Nia

JITP 2011: The Future of Computational Social Science

Analyzing publicly available content on various social media sites such as YouTube and Twitter, as well as social network sites such as Facebook, has become an increasingly popular method for studying socio-political issues. Such public-contributed content, primarily available as comments, let people express their opinions and sentiments on a given topic, news-story, or post, while allowing social and political scientists to extend their analysis of a political discourse to social sphere. We recognize the importance of Facebook in such analysis and present several approaches and observations of collecting and analyzing public comments from it. In particular, we demonstrate what it ...


Gpu Based Lithography Simulation And Opc, Lokesh Subramany Jan 2011

Gpu Based Lithography Simulation And Opc, Lokesh Subramany

Masters Theses 1911 - February 2014

Optical Proximity Correction (OPC) is a part of a family of techniques called Resolution Enhancement Techniques (RET). These techniques are employed to increase the resolution of a lithography system and improve the quality of the printed pattern. The fidelity of the pattern is degraded due to the disparity between the wavelength of light used in optical lithography, and the required size of printed features. In order to improve the aerial image, the mask is modified. This process is called OPC, OPC is an iterative process where a mask shape is modified to decrease the disparity between the required and printed ...


Analytical Modeling Of Tree Vibration Generated During Cutting Process, Payman Karvanirabori Jan 2009

Analytical Modeling Of Tree Vibration Generated During Cutting Process, Payman Karvanirabori

Masters Theses 1911 - February 2014

There are several ways to cut down a tree. The piece by piece cutting method is studied in this research. By modeling the cutting process into simple dynamic models and obtaining governing equations of motion of tree and cut piece in each model, the forces during cutting process were calculated. The method was then applied to a set of real data and tree vibrations were compared with field measurements. The study is very rare in the case of the variety of the topics it covers from dynamics and mechanics to finite element modeling of a biological system.