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Title: COVERAGE AND CONNECTIVITY IN WIRELESS NETWORKS
Creator: Xu, Xiaohua
Date: 2012-04-25, 2012-05
Description: The limited energy resources, instability, and lacking central control in wireless networks motivates the study of connected dominating set ...
Show moreThe limited energy resources, instability, and lacking central control in wireless networks motivates the study of connected dominating set (CDS) which serves as rout- ing backbone to support service discovery, and area monitoring and also broadcasting. The construction of CDS involves both coverage and connectivity. We ¯rst study sev- eral problems related to coverage. Given are a set of nodes and targets in a plane, the problem Minimum Wireless Cover (MWC) seeks the fewest nodes to cover the targets. If all nodes are associated with some positive prices, the problem Cheapest Wireless Cover (CWC) seeks a cheapest set of nodes to cover the targets. If all nodes have bounded lives, the problem Max-Life Wireless Cover (MLWC) seeks wireless coverage schedule of maximum life subject to the life constraints of individ- ual nodes. We present a polynomial time approximation scheme (PTAS) for MWC, and two randomized approximation algorithms for CWC and MLWC respectively. Given a node-weighted graph, the problem Minimum-Weighted Dominating Set (MWDS) is to ¯nd a minimum-weighted vertex subset such that, for any vertex, it is contained in this subset or it has a neighbor contained in this set. We will propose a (4+²)-approximation algorithm for MWDS in unit disk graphs. Meanwhile, for the connecting part, given a node-weighted connected graph and a subset of terminals, the problem Node-Weighted Steiner Tree (NWST) seeks a lightest tree connecting a given set of terminals in a node-weighted graph. We present three approximation algorithms for NWST restricted to UDGs. This dissertation also explores the applications of CDS, and develops e±cient algorithms for the applications such as real-time aggregation scheduling in wireless networks. Given a set of periodic aggregation queries, each query has its own period , and the subset of source nodes Si containing the data, we ¯rst propose a family of e±cient and e®ective real-time scheduling protocols that can answer every job of each query task within a relative delay under resource constraints by addressing the following tightly coupled tasks: routing, transmission plan constructions, node activity scheduling, and packet scheduling. Based on our protocol design, we further propose schedulability test schemes to e±ciently and e®ectively test whether, for a set of queries, each query job can be ¯nished within a ¯nite delay. We also conduct extensive simulations to validate the proposed protocol and evaluate its practical performance. The simulations corroborate our theoretical analysis.
Ph.D. in Computer Science, May 2012
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Title: Orthotics and Prosthetics in Latin America (sequence unknown), IPRO 309 - Deliverables: IPRO 309 IPRO Day Presentation F09
Creator: Ashley, Trevor, Claxton, Matt, Conover, Stephen, Gotanco, Francis, Mathai, Alexander, Nizich, Adam, Park, Yong, Quikr, Kerry, Ray, Monmayuri, Vasquez, Raul
Date: 2009-12
Description: The overall goal of our IPRO team is to create a program for delivering orthotics and prosthetics that is sustainable. This will be...
Show moreThe overall goal of our IPRO team is to create a program for delivering orthotics and prosthetics that is sustainable. This will be accomplished by improving the quality of the product by increasing availability of funding, improving cost effectiveness of prosthetics, and promoting awareness of treatment available.
Deliverables for IPRO 309: Orthotics and Prosthetics in Latin America for the fall 2009 semester.
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Title: Design of a Large Scale Structure (sequence 315), IPRO 315 - Deliverables: IPRO 315 Final Report F09
Creator: Aguilar-wedge, Carmen, Animashaun, Oladipo, Baur, Alex, Cullen, Michael, Hadi, Shuaib, Hedge, Namrata, Kuo, Steve, Lee, Christopher, Lee, Yongdoo, Rybaltowski, Karol, Scully, Dawveed, Shen, Jie-hua, Yousef, Shadi
Date: 2009-12
Description: Located in Oakbrook, IL the architects and engineers of IPRO 315 will design a 22 story hotel. Together architects and engineers will modify...
Show moreLocated in Oakbrook, IL the architects and engineers of IPRO 315 will design a 22 story hotel. Together architects and engineers will modify and re analyze a structure created by pervious designers, and select any new materials for construction. In creating the hotel students will be responsible for the structural analysis of columns, beams, foundation, steel, and concrete design required to insure all serviceability requirements. The students will be required to follow the 2006 International Building Code, and secure the safety of all possible occupants. Management, leadership, ethics, and teamwork will be an integral part of building a large scale structure as students learn to work together on a “real life” project.
Deliverables for IPRO 315: Design of a Large Scale Structure for the fall 2009 semester
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Title: The study of an air washer
Creator: Armspach, Otto W., Haines, E. Wilfred
Date: 2009, 1917
Publisher: Armour Institute of Technology
Description: http://www.archive.org/details/studyofairwasher00arms
Thesis (B.S.)--Armour Institute of Technology

Title: DOES NUTRITION KNOWLEDGE MODERATE THE ASSOCIATION BETWEEN PERFECTIONISM AND EATING DISORDER SYMPTOMATOLOGY?
Creator: Schwartz, Natalie
Date: 2017, 2017-05
Description: The trait of perfectionism is a psychological factor linked with the development of disordered eating, though the relation is unclear with...
Show moreThe trait of perfectionism is a psychological factor linked with the development of disordered eating, though the relation is unclear with some studies pointing to perfectionism as a predictor of eating disorder symptoms, while other studies have failed to find a statistically significant association. These discrepant findings suggest a need for understanding other factors that could be impacting the association. Research has suggested that individuals with eating disorders perform better than controls on knowledge of sources of nutrients and that while individuals with eating disorders spend more time reading about nutrition, this knowledge tends to be selective and skewed towards the aspects that maintain the eating disorder. The current study aimed to investigate the role of nutrition knowledge as a factor that may significantly influence the association between perfectionism and disordered eating attitudes. College women (N=122) completed several questionnaires related to disordered eating, nutrition knowledge, and perfectionism. The main research questions were: 1) whether perfectionism was related to disordered eating attitudes, 2) whether nutrition knowledge was related to disordered eating attitudes, and 3) whether nutrition knowledge moderated the relation between perfectionism and disordered eating attitudes. Results supported a positive association between perfectionism and disordered eating attitudes, in line with previous research. Despite a non-significant association between nutrition knowledge and disordered eating attitudes, there was found to be trend level significance (p<.07) for one moderation model. Specifically, the model assessing overall body dissatisfaction accounted for 33.34% of the variance, with a significant main effect for the level of perfectionism,suggesting the greater the degree of perfectionism traits, the greater the level of body dissatisfaction. While more research is needed to further develop an understanding of the link between perfectionism and disordered eating, nutrition knowledge is one possible avenue to explore in order to develop more effective prevention and intervention efforts.
M.S. in Psychology, May 2017
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Title: AN INTEGRATED DATA ACCESS SYSTEM FOR BIG COMPUTING
Creator: Yang, Xi
Date: 2016, 2016-07
Description: Big data has entered every corner of the fields of science and engineering and becomes a part of human society. Scientific research and...
Show moreBig data has entered every corner of the fields of science and engineering and becomes a part of human society. Scientific research and commercial practice are increasingly depending on the combined power of high-performance computing (HPC) and high-performance data analytics. Due to its importance, several commercial computing environments have been developed in recent years to support big data applications. MapReduce is a popular mainstream paradigm for large-scale data analytics. MapReduce-based data analytic tools commonly rely on underlying MapReduce file systems (MRFS), such as Hadoop Distributed File System (HDFS), to manage massive amounts of data. In the same time, conventional scientific applications usually run on HPC environments, such as Message Passing Interface (MPI), and their data are kept in parallel file systems (PFS), such as Lustre and GPFS, for high-speed computing and data consistency. As scientific applications become data intensive and big data applications become computing hungry, there is a surging interest and need to integrate HPC power and data processing power to support HPC on big data, the so-called big computing. A fundamental issue of big computing is the integration of data management and interoperability between the conventional HPC ecosystem and the newly emerged data processing/analytic ecosystem. However, data sharing between PFS and MRFS is limited currently, due to semantics mismatches, lacking communication middleware, and the diverged design philosophies and goals, etc. Also, challenges also exist in cross-platform task scheduling and parallelism. At the application layer, the data model mismatch between the raw data kept on file systems and the data management software of an application impedes cross-platform data processing as well. To support cross-platform integration, we propose and develop the Integrated Data Access System (IDAS) for big computing. IDAS extends the accessibilities of programming models and integrates the HPC environment with the data processing MapReduce/Hadoop environment. Under IDAS, MPI applications and MapReduce applications can share and exchange data under PFS and MRFS transparently and efficiently. Through this sharing and exchange, MPI and MapReduce applications can collaboratively provide both high-performance computing and data processing power for a given application. IDAS achieves its goal with several steps. First, IDAS enhances MPI-IO so that MPI-based applications can access data stored in HDFS efficiently. Here the term efficient means that HDFS is enhanced to support MPI-based applications. For instance, we have enhanced HDFS to transparently support N-to-1 file write for better write concurrency. Second, IDAS enhances Hadoop framework to enable MapReduce-based applications process data that resides on PFS transparently. Please notice that we have carefully chosen the term “enhance” here. That is MPI-based applications not only can access data stored on HDFS but also can continue access data stored on PFS. The same is for MapReduce-based applications. Through these enhancements, we achieve seamless data sharing. In addition, we have integrated data accessing with several application tools. In particular, we have integrated image plotting, query, and data subsetting within one application, for Earth Science data analysis. Many data centers prefer erasure-coding rather than triplication to achieve data durability, which trades data availability for lower storage cost. To this end, we have also investigated performance optimization of the erasure coded Hadoop system, to enhance Hadoop system in IDAS.
Ph.D. in Computer Science, July 2016
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Title: DYNAMIC COHERENT ACCEPTABILITY INDICES AND THEIR APPLICATIONS IN FINANCE
Creator: Zhang, Zhao
Date: 2011-05-02, 2011-05
Description: This thesis presents a unified framework for studying coherent acceptability indices in a dynamic setup. We study dynamic coherent...
Show moreThis thesis presents a unified framework for studying coherent acceptability indices in a dynamic setup. We study dynamic coherent acceptability indices and dynamic coherent risk measures. In particular, we establish a duality between them. We derive representation theorems for both dynamic coherent acceptability indices and dynamic coherent risk measures in terms of so called dynamically consistent sequence of sets of probability measures. In addition, we present an alternative approach to study dynamic coherent acceptability indices and the representation theorem. Finally, we provide examples and counterexamples of dynamic coherent acceptability indices, and their applications in portfolio management.
Ph.D. in Applied Mathematics, May 2011
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Title: POWER ELECTRONIC INTERFACE FOR AN OFF-GRID SOLAR POWERED ENERGY STORAGE SYSTEM
Creator: Mao, Yanwen
Date: 2012-10-17, 2012-12
Description: There are about 1.5 billion people in the world with no access to electricity. Of these, a significant number of people live in rural parts of...
Show moreThere are about 1.5 billion people in the world with no access to electricity. Of these, a significant number of people live in rural parts of Africa and Asia. It is very inconvenient and unhealthy for them to work or study at night with the poor light from a candle or kerosene lamp. Additionally, since they do not have a continuous or predictable supply of power, it can be significantly difficult for them to use modern electronic devices such as cell phones, computers or sometimes even basic amenities such as lights and fans. For such situations, an energy storage system powered by solar energy can be a good solution, while being environmentally friendly and easy to use. In this thesis, the design and analysis of an off-grid solar powered energy storage system is presented. It consists of a solar panel, battery pack, control circuit, bidirectional DC/DC converter, and inverter. Operation of this system can be described in terms of two modes. In the daytime, the solar panel absorbs energy from sun light; the DC/DC converter boosts the voltage to a certain value and charges the battery pack. During the nighttime, the battery pack provides energy to the circuit; the DC/DC converter boosts voltage level and the inverter inverts DC voltage to single phase AC voltage; this output of 110V AC voltage can charge cell phones, run an energy save lamp, a fan, or even power a laptop. Details of the design process, system operation, components used in the system, simulation and experimental results are explained in the thesis. The main contribution of the thesis is the development of a new off-grid solar powered energy storage system control strategy that can store solar energy in the battery and provide regular 110V AC xii voltage output to the load when needed; additionally, the implementation of the concept along with testing on an experimental set-up is discussed.
M.S. in Electrical Engineering, December 2012
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Title: A NUMERICAL-METHOD FOR DETERMINING OPTIMAL PARAMETER VALUES IN FORCED PERIODIC OPERATION
Creator: Ozgulsen, F., Adomaitis, R. A., Cinar, A.
Date: 1992-02
Publisher: PERGAMON-ELSEVIER SCIENCE LTD
Description: A numerical approach for determining values of forcing parameters which maximize performance of a periodically forced system is described....
Show moreA numerical approach for determining values of forcing parameters which maximize performance of a periodically forced system is described. Periodic solutions of the system equations plus a differential form of the time-average performance measure are computed with a shooting algorithm. A nonlinear programming package is used to solve the optimization problem. The algorithm is applied to ethylene oxidation process, using the model of a continuous stirred-tank reactor (CSTR).
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Title: Developing a Collaborative On-line Student Research Forum (sequence unknown), IPRO 321 - Deliverables: IPRO 321 Midterm Presentation F09
Creator: Abhay, Anandha, Cornelius, Zachary, Corsus, Tom, De Courten-myers, Maximilian, Eberlin, Adam, Kapaldo, James, Nicholson, Bethany, Sizyuk, Yuriy, Sundberg, Stephen
Date: 2009-12
Description: ResearchWeb is meant to broaden IIT undergraduate participation beyond the existing mechanisms such as fellowships, research and reading...
Show moreResearchWeb is meant to broaden IIT undergraduate participation beyond the existing mechanisms such as fellowships, research and reading courses, and departmental projects. There is also the possibility of broadening this program to other scholarly individuals outside of the IIT undergraduate community. These individuals include IIT graduate students, students from other universities, and promising high school students. ResearchWeb is also meant to improve the transition, and perhaps promote if need be, the transition from undergraduate education to graduate education. This would be fulfilled through practical research experience.
Deliverables for IPRO 321:Developing a Collaborative On-line Student Research Forum for Fall 2009
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Title: B-SPLINE BASED ROBUST FORMULATION IN TOPOLOGY OPTIMIZATION
Creator: Gu, Yu
Date: 2014, 2014-12
Description: In this thesis, we extend the B-spline based density representation to robust topology optimization. The B-spline based representation has...
Show moreIn this thesis, we extend the B-spline based density representation to robust topology optimization. The B-spline based representation has been shown to have the ability of preventing checker-boards. With separate analysis and design mesh, the B-spline based filter is also competitive on computation storage compared with usual density filter. However, the current B-spline based representation is not robust where gray transitions exist. The recent proposed robust formulation highlights the manufacturability that simulates under- or over- etching designs compared with intermediate design. The robustness is demonstrated through three test cases. The minimum length control for quadratic B-splines is analytically derived with respect to knot span size and threshold. Our study about the characteristics of rectangular domain of B-spline based representation, shows that the optimized designs are comparable to those by density filter.
M.S. in Mechanical and Aerospace Engineering, December 2014
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Title: Transmission efficiencies of belting
Creator: Marks, Robert Edward
Date: 2009, 1919
Publisher: Armour Institute of Technology
Description: http://www.archive.org/details/transmissioneffi00mark
Thesis (B.S.)--Armour Institute of Technology; Bibliography: leaf 29

Title: ENVIRONMENTAL PERFORMANCE VS. FINANCIAL PERFORMANCE, MARKET INEFFICIENCY AND INVESTMENTS
Creator: He, Chaohua
Date: 2014, 2014-07
Description: It is challenging to de ne corporate environmental performance or corporate nancial performance. In this study, a company is considered to...
Show moreIt is challenging to de ne corporate environmental performance or corporate nancial performance. In this study, a company is considered to have good environmental performance (namely, be green, environment-friendly or environmentally responsible) if it is among the Top 100 of the 500 US greenest companies ranked by Newsweek, or has environmental strength(s) and no environmental concern in terms of the KLD ratings. A company is regarded to have good nancial performance if it has a high raw return, Sharpe ratio, and excess (or abnormal) return over various benchmarks. Preference will be given to excess return estimated using the Carhart four-factor model [14]. A previous published longitudinal study, co-authored with my advisor [13], unveils that: 1) environmentally responsible companies tend to experience signi cantly positive abnormal performance in the long horizon (e.g. from the fourth to seventh year after being selected); 2) the value-adding e ect and the market's upward price adjustments on undervalued intangible environmental strength(s) might have resulted in the long-term outperformance. Would environmentally responsible companies still outperform during shorter horizons, such as the event period of an environmental disclosure? Using event study methodologies, this paper investigates market responses to independent Newsweek environmental disclosures by analyzing cross-sectional and time-series abnormal security returns. Results suggest that the Top 100 greenest companies tend to display signi cant abnormal returns within 4 days after a disclosure, and the signi cant abnormal returns generally persist for no more than 3 trade days. e.g., the Carhart four-factor abnormal return, with statistical signi cance, is averaged at 0.50% per day over the four disclosure events. The ndings are robust to di erentmodels of normal return, removal of outliers, elimination of confounding e ects, controlling for characteristic factors, and adjusting for cross-sectional correlation and volatility shift on test statistics using BMP-adjusted technology[56]. Signi cant abnormal returns over the event period may indicate ine ciency of the nancial market. Fama-Macbeth regressions further reveal that short-horizon abnormal returns could be explained by a spectrum of characteristic variables, green investing, arbitrage trading, and/or various psychological biases. Complementing the cited longitudinal study, a portfolio-level comparison reveals that an actively managed green portfolio outperforms an actively managed nongreen portfolio in terms of raw return and risk-adjusted measures such as Sharpe ratio, Jensen's alpha and Fama-French alpha in the long horizon. The results are robust to di erent portfolio weighting technologies and the consideration of turnover costs. In addition, the green portfolio's outperformance is driven by a bunch of small, aggressive and relatively inactive stocks that have better performance than the market predicts. No evidence shows that the ever-increasing demand on green securities leads to the green portfolio's outperformance, because green stocks are actually less actively traded. Panel regressions further indicate that long-horizon corporate economic performance positively correlates to historical corporate environmental performance.
Ph.D. in Management Science, July 2014
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Title: SUSTAINABLE, CONTROLLED, REACTION SYNTHESIS OF METALLIC WIRES AND STRIPS
Creator: Chen, Xin
Date: 2014, 2014-05
Description: The main purpose of this work is to investigate bi and tri-metallic metal com- binations as initiators which require an ability to have a self...
Show moreThe main purpose of this work is to investigate bi and tri-metallic metal com- binations as initiators which require an ability to have a self-sustaining exothermic reaction. Through the reaction, the initiator should achieve a temperature in excess of 500 C when in contact with a thermally conducting surface. Also the initiator must be in the form of a exible wire or strip of the order of one millimeter radius. There are four phases in my MS research project. First was identifying the potential candidate compounds for exothermic reaction. During this phase, I wrote a program using Mathematicar (Appendix A) to calculate the adiabatic temperature resulting from the reaction of di erent binary or ternary elemental combinations. The calculation took into account the speci c heats and any enthalpies of transformation occurring between room temperature and the adiabatic temperature. Based on the results of this program several suitable compositions were selected from three hun- dred candidates. The second phase was determining a methodology to manufacture selfCpropagating thin strips or wires. We attempted several methods including plate rolling, wire twisting, mechanical coating, chemical coating, and powder metallurgy. We successfully obtained self-propagating thin metal strips and wires using powder metallurgy methods. In the third phase, a transparent reaction box was constructed in order to provide a protective atmosphere (Ar gas) and connect to a data acqui- sition system to obtain the reaction temperature, initiation temperature and video materials of reactions. In the last phase, the reacted samples were characterized using Scanning Electron Microscope (SEM), Backscattered Electron detector (BSE), X-ray Di raction (XRD), Di erential scanning calorimeter (DSC), etc.
M.S. in Mechanical, Materials, and Aerospace Engineering, May 2014
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Title: A MODEL OBJECT BASED SUPERVISORY EXPERT SYSTEM FOR FAULT TOLERANT CHEMICAL REACTOR CONTROL
Creator: Basila, M. R., Stefanek, G., Cinar, A.
Date: 1990-05
Publisher: PERGAMON-ELSEVIER SCIENCE LTD
Description: An expert system for real-time control of chemical processes provides an environment for coordination of process fault diagnosis, assessment...
Show moreAn expert system for real-time control of chemical processes provides an environment for coordination of process fault diagnosis, assessment of process behavior, automated controller retuning and/or reconfiguration and consequently enables fault-tolerant process control. A supervisory expert system with object-based knowledge representation and heuristic (shallow) and model-based (deep) knowledge is presented. The expert system resides on a PC/386 and communicates with the control system developed in the form of control blocks residing on a PC/286. The prototype of the expert system is developed for retuning model-based controllers to improve the behavior of a packed-bed tubular CO oxidation reactor under autothermal operation. MOBECS is a supervisory expert system designed to tailor the process control system for a tubular autothermal reactor in response to process or control system faults, and changes in the process behavior. Specific functions include process fault diagnosis, control system performance monitoring and trouble-shooting, controller tuning and control system restructuring. As this work progresses, we will also address the problems of sensor placement, state estimation and process identification. Because of the high degree of coupling and interaction between process and control system entities, objects are the best knowledge representation for a process control expert system. The class—object structures of MOBECS is divided into three orthogonal trees representing the process and control system hierarchies and the topology of the system. Using this structure, knowledge is divided into general knowledge applicable to any process or control system and knowledge that is domain specific. The general knowledge is stored in the class structures and, together with generalized rules, forms a knowledge base kernel. This permits rapid prototyping of other applications of MOBECS. Properties are defined as high as possible in the class tree structure and inherited downwards. Knowledge specific to the process is stored in the objects at the leaves of the trees. Rules form the reasoning portion of the knowledge base and contain the causal relationships, meta-knowledge and performance monitoring functions. Rules that perform general monitoring and troubleshooting are applied at the class level through pattern matching. Rule sets are linked through context relationships to identify indirect relationships to the inference engine. These relationships are used with the process topology tree to reduce the search space when a fault is detected. The process monitoring and instability detection rules have been tested by simulating the inputs to the expert system. At the present time, experimental validation of the MOBECS prototype is being undertaken. Once the MOBECS prototype has been fully tested, the knowledge base will be extended to incorporate more complex fault diagnosis, state estimation, sensor placement and controller restructuring.
Endnote format citation
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Title: Agricultural Rehabilitation Tower
Creator: Garcia, Rodrigo, Lee, Jennifer
Date: 5/4/2011, 2011-05
Description: to create a vertical community bound together by two key issues/requirements in Korean society: urban agriculture and mental health care to...
Show moreto create a vertical community bound together by two key issues/requirements in Korean society: urban agriculture and mental health care to create a ‘vertical façade farm’ capable of producing 156 tons of vegetables (predominantly lettuce, tomatoes, peppers, and strawberries) and 200 tons of fish per year to create a mental health sanctuary (or sanatorium) that provides short term (days), midterm (months) and long term (years) residence and care for people with mental health issues that may require physical operations and/or psychological care. to actively engage the mental health residents in aspects of the agricultural production to draw on research showing that engagement with plants/nature assists in mental healing. to create a large multi-purpose space at the ground floor of the building which will largely serve as a farmer’s market for sale of the agricultural produce and engagement between the community residents and the public to create a series of gardens/green spaces at height within the complex, as well as vertical green walls, for healing (residents and urban issues) to use the double-skin ‘façade farm’ for assisting in passive natural ventilation of internal spaces
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Title: A Video Annotation and Indexing System (sequence unknown), IPRO 327 - Deliverables
Creator: Dhagam, Karthik, Donchev, Alexander, Homawoo, Sergio, Litas, Alexander, Orlichenko, Anton, Osswald, Christian, Petsod, Jason, Rawlings, Ori, Shaffer, Joshua, Smith, Antoinette, Yates, Andrew, Yu, Hee Jeoung
Date: 2009-12
Description: Much information available on the Web is in video format. The problem with this medium is users cannot comment on particular scenes within the...
Show moreMuch information available on the Web is in video format. The problem with this medium is users cannot comment on particular scenes within the videos and there is no method of searching for specific content within the videos. The team proposes to develop a system that will allow users to make fine-grained comments on scenes within the video and then to use these comments to aid in search within videos.
Deliverables for IPRO 327: A video annotation and indexing system for the fall 2009 semester
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Title: WIDESPAN: 2030-board 2
Creator: Ninan, Janice
Date: 2011-05, 2010-12
Description: Widespan design.Investigating the integration of windmills into longspan structure and investigating the axial forces of tension to span...
Show moreWidespan design.Investigating the integration of windmills into longspan structure and investigating the axial forces of tension to span grater spans using virtual depth concepts with slender lightweight design.
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Title: Greenweb
Creator: Thomas, Boerman
Date: 2010-07-29

Title: CONSTITUTIVE BEHAVIOR AND MODELING OF AL-CU ALLOY SYSTEMS
Creator: Turkkan, Omer Anil
Date: 2013-05-07, 2013-05
Description: High speed deformation events such as caused by projectile penetration, fragment impact and shock/blast loading are of great importance in...
Show moreHigh speed deformation events such as caused by projectile penetration, fragment impact and shock/blast loading are of great importance in designing materials and structures for army applications. In these events, materials are subjected to large strains, high strain rates and rapid increase in temperature due to thermoplastic heating. In such severe conditions, overall performance is determined by the evolution of flow stress, failure initiation and propagation, and commonly in the form of adiabatic shear banding. Some of 2XXX series aluminum-copper (Al-Cu) alloys are recognized for their decent ballistic properties, and therefore they have been used as an armor material for lightweight U.S. Army vehicles. Most recently, an Al-Cu-Mg-Mn-Ag alloy labeled as Al 2139-T8 has been developed and is evaluated by the U.S. Army Research Labs. because of its better ballistic properties and higher strength than its predecessors. The underlying microstructure is believed to be the key element for this superior performance. The goal of this study is to explore the effect of composition and microstructural features on overall dynamic material behavior by examining mechanical and deformation behavior of different Al-Cu material systems. Starting from the pure single crystal and polycrystalline Al structures, and adding a different element to chemical composition in each step (i.e., Cu, Mg, Mn, Ag), mechanical response of these different systems has been investigated. For all alloy systems with the exception of single crystal Al, mechanical tests have been performed at room and elevated temperatures covering quasi-static ( to ) and dynamic ( to strain rate regimes. xiv Shear-compression specimens promoting localized shear deformation have been used to explore tendency of each one of these materials to failure by adiabatic shear banding. In addition to phenomenological Johnson-Cook Model (JCM), physics based Zerrilli-Armstrong and Mechanical Threshold Models have been studied to model the constitutive response of Al-Cu alloys over a wide range of strain rates and temperatures.. An improved ZA model has been developed to better capture the trends in experimental data.
M.S. in MECHANICAL, MATERIALS, AND AEROSPACE ENGINEERING, May 2013
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