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Title: DAMAGE DETECTION OF STRUCTURES USING INTERVAL FINITE ELEMENT METHOD
Creator: Venkitaraman, Shyamala
Date: 2012-04-16, 2012-05
Description: Health assessment and damage detection for existing structures is an essential procedure for their safe and reliable operation so that any...
Show moreHealth assessment and damage detection for existing structures is an essential procedure for their safe and reliable operation so that any catastrophic failure may be prevented in a timely manner. However, results obtained from a health assessment of a structure possess uncertainties in measurements, system properties and loads. Furthermore, the conventional deterministic structural analyses are incapable of considering these uncertainties, thereby resulting in error when estimating the state of health of a structure. Interval (unknown-but-bounded) representation is one method to quantify uncertainty in a physical system. Using an interval variable, the uncertain parameter is bounded between extreme values. In this work, a new method for damage assessment of structures is developed that utilizes the results from structural health assessment as uncertain input parameters in an interval finite element analysis scheme. This method, due to its capability of considering uncertainties, offers a more robust process for estimating the possible existence of damage and overall health of the structure. As an illustrative example, the method is applied for a failed sign support structure. First, the structure's response from previous health assessment procedure was used to construct uncertain interval responses. Then using these interval responses as input parameters, an interval finite element method was performed. The results of the analysis verify and correlate with the failure location of the actual structure. Moreover, the lifetime assessment of the structure obtained from this method is the lower bound of, and correlates with the actual failure time of the structure.
M.S. in Civil Engineering, May 2012
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Title: Laboratory Notebook 112
Creator: Zhang, Zhe, Varelis, Peter
Date: 2010-03-09T22:34:24Z
Description: This laboratory notebook relates to the "Heat Stability of Ricin in Phosphate Buffer System" project with Peter Varelis as the Principle...
Show moreThis laboratory notebook relates to the "Heat Stability of Ricin in Phosphate Buffer System" project with Peter Varelis as the Principle Investigator.
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Title: Alleviating Homelessness in Chicago: Alleviating Homelessness in Chicago - Poster
Creator: Degroff, Justin
Date: 2011, 2011-05
Description: Alleviating homelessness in Chicago through the creation of a network of self-sufficient, revenue generating support nodes.

Title: PARADIGM SHIFT IN REMOTE EDUCATION FOR THE LABORATORY: A SOCIAL APPROACH TO DISTANCE LEARNING
Creator: Hanley, Richard
Date: 2011-12, 2011-12
Description: With modern telecommunication tools the ability for two individuals to work together remotely has greatly improved. Moreover, there have been...
Show moreWith modern telecommunication tools the ability for two individuals to work together remotely has greatly improved. Moreover, there have been great strides made to improve handling medium to large groups of people in real time in remote settings, viz. the teleconference and webinar. However, the status of remote tools for laboratory environments where there is significant hardware and the individuals are more likely to talk amongst themselves in irregular patterns is not nearly as well studied. This thesis examines the way most laboratories in electrical engineering are setup, and creates a model for how to create a remote environment for distance learning. It then discusses the current state of the art, and how such an implementation of the model can be made with such tools. Finally a usability study of the implementation is examined. The primary result of the usability study is that when moving to a remote environment the social paradigm that students and instructors use is likely to change, and simply working on creating a virtual mirror to the laboratory may not work in the future.
M.S. in Electrical Engineering, December 2011
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Title: Development of High Bandwidth Powered Resonance Tube Actuators with Feedback Control
Creator: Raman, G., Khanafseh, S., Cain, A. B., Kerschen, E.
Date: 2004-01-22
Publisher: Academic Press Ltd Elsevier Science Ltd
Description: A high bandwidth powered resonance tube (PRT) actuator potentially useful for noise and flow control applications was developed. High...
Show moreA high bandwidth powered resonance tube (PRT) actuator potentially useful for noise and flow control applications was developed. High bandwidth allows use of the same actuator at various locations on an aircraft and over a range of flight speeds. The actuator selected for bandwidth enhancement was the PRT actuator, which is an adaptation of the Hartmann whistle. The device is capable of producing high-frequency and high-amplitude pressure and velocity perturbations for active flow control applications. Our detailed experiments aimed at understanding the PRT phenomenon are complemented by an improved analytical model and direct numerical simulations. We provide a detailed characterization of the unsteady pressures in the nearfield of the actuator using phase averaged pressure measurements. The measurements revealed that propagating fluctuations at 9 kHz were biased towards the upstream direction (relative to the supply jet). A complementary computational study validated by our experiments was useful in simulating the details in the region between the supply jet and the resonance tube where it was difficult to gather experimental data. High bandwidth was obtained by varying the depth of the resonance tube that determines the frequency produced by the device. Our actuator could produce frequencies ranging from 1600 to 15,000 Hz at amplitudes as high as 160 dB near the source. The frequency variation with depth is predicted well by the quarter wavelength formula for deep tubes but the formula becomes increasingly inaccurate as the tube depth is decreased. An improved analytical model was developed, in which the compliance and mass of the fluid in the integration slot is incorporated into the prediction of resonance frequencies of the system. Finally a feedback controller that varied both the resonance tube depth and spacing to converge on a desired frequency was developed and demonstrated. We are optimistic that numerous potential applications exist for such high bandwidth high dynamic range actuators. (C) 2003 Published by Elsevier Science Ltd.
http://dx.doi.org/10.1016/S0022-460X(03)00212-8
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Title: EUTECTIC γ(NI)/γ′(NI3AL)-δ(NI3NB) POLYCRYSTALLINE NICKEL-BASE SUPERALLOYS: CHEMISTRY, PROCESSING, MICROSTRUCTURE AND PROPERTIES
Creator: Xie, Mengtao
Date: 2012-12-03, 2012-12
Description: Directionally solidified γ(Ni)/γ′(Ni3Al)-δ(Ni3Nb) eutectic alloys possess attrac- tive high temperature mechanical properties and were...
Show moreDirectionally solidified γ(Ni)/γ′(Ni3Al)-δ(Ni3Nb) eutectic alloys possess attrac- tive high temperature mechanical properties and were considered as candidate tur- bine blade materials. Currently, the properties of polycrystalline γ/γ′-δ alloys are of interest as they inherit many advantageous attributes from the directionally solidi- fied γ/γ′-δ alloys, including high volume fraction of reinforcing phases, exceptional thermal stability and resistance to segregation-induced defect formation. If these at- tributes are properly harnessed, these γ/γ′-δ eutectic alloys might provide a unique solution to the problems experienced by traditional γ/γ′ polycrystalline Ni-base su- peralloys. This thesis is therefore dedicated towards the development of a funda- mental understanding of this novel class of eutectic alloys from several important perspectives. To enrich our understanding of this alloy system, this thesis will first be focused on quantifying the specific effect of individual alloying element on this γ/γ′-δ eutectic system. A set of quaternary Ni-Cr-Al-Nb alloy compositions with increasing levels of Chromium(Cr) was designed to investigate the detailed influence of this element on the primary phase formation, solidus and liquidus temperatures and γ-δ eutectic morphology. The alloying effect of Tantalum(Ta), which shares many similarities to Niobium(Nb), was studied by designing a matrix of multi-component γ/γ′-δ alloy compositions with nominally the same overall (Ta+Nb) content but varying Ta/Nb ratios. Here, different solidification segregation and solid state partitioning behaviors of Ta and Nb in this γ/γ′-δ eutectic system will be discussed, as well as the influ- ence of Ta/Nb ratio on solidification characteristics and equilibrium/non-equilibrium phase volume fractions. Thermodynamic calculations using the Computherm Pandat database (PanNi7) were compared to experimental results in these investigations. The second part of this thesis will aim to provide a more general understand- xvii ing of the effect of various alloying elements, including Cr, Co, Al, Ti, Mo, W, Ta and Nb, on this γ/γ′-δ system. A large number of experimental γ/γ′-δ alloys covering a broad range of compositions was selected for the analysis in this study. Important alloy attributes, such as primary phase formation, overall δ volume fraction, phase transformation temperatures and ternary eutectic initiation, were quantitatively char- acterized as a function of individual alloying element concentrations or combined con- tent of more elements. Linear regression analysis was performed to reveal the relative effectiveness of these elements on this eutectic system. Meanwhile, an extensive com- parison between the experimental observations and Pandat predictions was provided to critically evaluate the strength and weakness of existing thermodynamic database model in predicting trends in this eutectic alloy system with substantially higher Nb content compared to traditional γ/γ′ superalloys. The last part of this thesis emphasizes the development of cast and wrought manufacturing processes for cast γ/γ′-δ eutectic alloys as a cost effective alternative to the powder metallurgy route. Hot rolling of workpieces encapsulated within a steel can was performed on a simple model cast γ/γ′-δ alloy (897) to stimulate the ingot to billet. The influence of different deformation levels on breaking down the dendritic structure and promoting fine and homogenized microstructure was investi- gated. The mechanical soundness associated with different microstructures generated by different hot rolling processes was compared via compression and creep testing. Microstructural parameters that contribute to better mechanical properties will be discussed.
PH.D in Materials Science and Engineering, December 2012
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Title: The Brownfield Renewal Recreation Center: Rosika-Babakhanian-finalbook
Creator: Babakhanian, Rosika
Date: 5/10/2011, 2011-05
Description: This Project is an urban renewal of an abandoned post-industrial land in the calumet region located on Chicago’s far southeast. The Calumet...
Show moreThis Project is an urban renewal of an abandoned post-industrial land in the calumet region located on Chicago’s far southeast. The Calumet region was once the largest and richest wetland in lower north America, but 120 years of intensive industrialization, pollution and waste disposal tailored the ecosystem of this region and resulted in thousands of acres of brownfields.
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Title: SURVIVAL AND GROWTH OF LISTERIA MONOCYTOGENES IN CHOPPED GREEN AND RED BELL PEPPERS USING PREDICTIVE MODELING
Creator: Zhang, L1jie
Date: 2015, 2015-07
Description: Listeria monocytogenes (L. monocytogenes) is a Gram-positive pathogenic organism and the causative agent of human and animal listeriosis....
Show moreListeria monocytogenes (L. monocytogenes) is a Gram-positive pathogenic organism and the causative agent of human and animal listeriosis. Listeriosis is a gastrointestinal or invasive systemic illness resulting from consumption of contaminated food products, mainly cheese, deli meats, and fresh produce, by L. monocytogenes. In recent years, several foodborne outbreaks have been reported that were associated with fresh produce, such as cantaloupe, celery and sprouts. Temperature is considered a major factor that affects L. monocytogenes growth during storage. The proliferation of L. monocytogenes varies on different produce items based on storage temperature. In this study, the persistence and population dynamics of three L. monocytogenes strains, LS806 (cheese isolate), LS810 (cantaloupe isolate) and LS808 (celery isolate) were evaluated by incubating inoculated fresh-cut green bell pepper and red bell pepper at various temperatures (5oC, 10oC, and 25oC) for 14 days. To assess the risk of L. monocytogenes in these fresh-cut vegetable items, a primary predictive model was fitted for L. monocytogenes growth data using DMFit. Green bell pepper had significantly (P<0.05) higher pH and aw, and higher amounts of yeast and mold and Enterobacteriaceae than did red bell pepper. In green bell pepper, all three strains showed no significant difference (P>0.05) in growth rate when incubated at the same temperature. In red bell peppers, LS808 had the highest (P<0.05) growth rate at both 5°C and 25°C out of the three strains. All of the three strains grew significantly faster (P<0.01) at 25°C than either 5°C or 10°C in both green and red bell peppers. All three strains obtained less than 1 log10 growth increase after incubating at 25°C for 6 hours on pre-chilled produce. Some strains (LS806 and LS810) significantly increased (P<0.01) during two 5-hour 25°C incubations, but did not reach 1 log10 growth increase. The results indicate that L. monocytogenes not only persists, but also grows in chopped green and red bell peppers at 5, 10, and 25°C, and strains grew faster at the higher temperature (25°C). Data obtained could be further evaluated for determining whether Time/temperature control for safety (TCS) designation should be applied to chopped green and red bell peppers.
M.S. in Food Safety and Technology, July 2015
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Title: Influence of the target on multiparticle production in the forward domain in p+Pb collisions at 158 GeV, Proceedings of the XLIII International Symposium on Multiparticle Dynamics
Creator: Rybczyński, Maciej
Date: 2013-09-15, 2013-09-15
Publisher: IIT Press
Description: In this talk we show the influence of the target on multiparticle production in the forward hemisphere in p+Pb collisions at top SPS energy....
Show moreIn this talk we show the influence of the target on multiparticle production in the forward hemisphere in p+Pb collisions at top SPS energy. The multiplicity distributions appear to be almost target independent in the projectile fragmentation domain and the effect of fluctuations of the number of target participants is not seen in the projectile fragmentation region. We compare the obtained results with those for p+p interactions and predictions of models.
Sponsorship: IIT College of Science, High Energy Physics Division of Argonne National Laboratory
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Title: STRUCTURAL CHARACTERIZATION OF THE FLIGHT MUSCLE OF MANDUCA SEXTA
Creator: Cheng, Yu-shu
Date: 2013-04-22, 2013-05
Description: There are several properties of the flight muscle Manduca sexta that are interesting. In its physiological characteristics, like mammalian...
Show moreThere are several properties of the flight muscle Manduca sexta that are interesting. In its physiological characteristics, like mammalian skeletal and cardiac striated muscle, it is a synchronous muscle. However, it is much more similar structurally to the more widely known asynchronous insect flight muscles of Drosophila and Lethocerus. The goal of the thesis is to study the structural characteristics and perform mechanical studies of dorsal and ventral muscle of Manduca flight muscle. In pursuit of this goal, a secondary purpose was to develop better storage conditions for skinned insect muscle which can maintain muscle structure and function. Maximum active force as a function of time in storage was compared for storing at 4℃ without glycerol and storing at -80℃ with 75% glycerol. The maximum force values were almost the same during days 0-4. However, the muscle stored at -80℃ with 75% glycerol gave higher active force in high calcium (pCa 4.5) solution over a longer time in storage than muscle stored at 4℃. Both ventral and dorsal muscles can deliver 40-50% of original active force for up to 21 days in storage. X-ray diffraction experiments were done to compare the response of chemically skinned Manduca flight muscle to temperature and to the induction of rigor. The lattice spacing (d10) decreased and intensity ratio I20/I10 increased when the temperature of the relaxing solution bathing the solution increased from 10℃ to 40℃. Lattice spacing (d10) decreased, but the I20/I10 intensity ratio increased slightly while concentration of dextran increased from 1% to 6%. Six percent dextran was insufficient to restore the in vivo lattice spacing.
M.S. in Molecular Biochemistry and Biophysics, May 2013
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Title: Widget Applications to Enhance the Tru2Way Consumer Experience (sequence unknown), IPRO 312 - Deliverables
Creator: Alsharief, Yagoob, Aulfata, Muluken, Curtis, Christopher, Dhewaju, Anusuya, Mooney, Kevin, Mutyaba, Kevin, Ndoping, Marco, Onaissi, Samah, Peterson, Naomi, Siwek, Steven, Wallace, Sean, Yi, Won-jae
Date: 2009-12
Description: The IPRO teams objectives are to provide Comcast with feedback from an outside perspective, allowing them to see where their Tru2Way system...
Show moreThe IPRO teams objectives are to provide Comcast with feedback from an outside perspective, allowing them to see where their Tru2Way system needs additional attention or support.
Sponsorship: Comcast
Deliverables for IPRO 312: Widget Applications to Enhance the Tru2Way Consumer Experience for the fall 2009 semester
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Title: MONITORING, MODELING, AND TREATMENT OF ODORS/ODORANTS AT WATER RECLAMATION PLANTS
Creator: Zhang, Yanming
Date: 2012-04-23, 2012-05
Description: A thorough study including odor monitoring, modeling and treatment as three important aspects of odor control in WRPs has been performed in...
Show moreA thorough study including odor monitoring, modeling and treatment as three important aspects of odor control in WRPs has been performed in this research. Measurement of H2S emissions from odor sources was proven to be an essential step in odor monitoring program. The H2S emission rates were measured from various sources throughout a WRP for 9 sampling events during winter and summer. During summer, both the average and the maximum emission rates of H2S from liquid treatment processes increased significantly compared to those measured during winter. However, for solids-handling processes, the emission rates remained constant because sludge characteristics did not vary throughout the year. The total sulfide concentrations present in liquid treatment processes were higher than those in preliminary and primary treatment units but at much lower levels in secondary treatment. Rates of H2S emission from the headworks were correlated to daily average wastewater temperature, TKN concentration, and flow rate. AERMOD was used as the modeling tool to evaluate the odor impact of Egan WRP on the surrounding communities. The emission rates could significantly affect the modeling results. Long-term H2S monitoring increases the possibility of developing the proper emission rate for the worst-case scenario. Excluding the modeling during the night would avoid overestimation of odor impact and excessive odor control. In the laboratory-scale study of O3 oxidation of H2S, O3 oxidation was proven to be a fast and effective method to remove H2S from the odorous air emitted from wastewater treatment processes. The increased initial ratio of O3/H2S enhances the removal rate of H2S. The consumption ratio of O3/H2S is a function of input reactant ratios. A multiple linear regression model (R2=0.84) has been developed to predict the H2S residual for given initial H2S and O3 concentrations and reaction time. The increased moisture content of the odorous air enhanced the H2S removal while DMS and DMDS inhibit H2S removal by competing for the limited O3 supply.
Ph.D. in Environmental Engineering, May 2012
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Title: the evolution of the south fork turning basin: Grilli_Board_Map
Creator: Grilli, Graham
Date: 5/4/2011, 2011-05
Description: a historical analysis of the South Fork Turning basin from 1833-2040 including proposals for future timeline. wetland remediation coupled with...
Show morea historical analysis of the South Fork Turning basin from 1833-2040 including proposals for future timeline. wetland remediation coupled with modular housing and adaptive reuse solutions. prototype for other potential developments along river's edge leading to healthier Great Lakes basin.
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Title: DETERMINATION OF REDUNDANCY IN STRUCTURES USING INTERVAL UNCERTAINTY ANALYSIS
Creator: Amirshaghaghi, Sayeh
Date: 2014, 2014-05
Description: Existence of redundancy in structures plays an important role in increasing their safety and reliability. However, using state-of-the-art...
Show moreExistence of redundancy in structures plays an important role in increasing their safety and reliability. However, using state-of-the-art deterministic and probabilistic approaches, all possibilities for estimation of redundancy (e.g. due to occurrence of different damage scenarios) have not been considered. One of the methods to quantify the presence of uncertainties in a system is to use interval variables. In this work, a new method for estimating the redundancy using interval structural analysis is developed. This method, hereafter referred to as Interval Redundancy Analysis (IRA), is robust and considers possibilities of strength reduction for each element leading to failure. Independent intervals for reduction of the strength for five damage scenarios of intact, slightly damage, moderately damaged, severely damaged, and completely damaged as well as strength of each element are considered. A numerical example to show the behavior of the developed method with comparison to Monte-Carlo simulation results is presented.
M.S. in Civil Engineering, May 2014
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Title: AN ADAPTIVE RESCALING SCHEME FOR COMPUTING HELE-SHAW PROBLEMS
Creator: Zhao, Meng
Date: 2017, 2017-07
Description: In this thesis, we develop efficient adaptive rescaling schemes to investigate interface instabilities associated with moving interface...
Show moreIn this thesis, we develop efficient adaptive rescaling schemes to investigate interface instabilities associated with moving interface problems. The idea of rescaling is to map the current time-space onto a new time-space frame such that the interfaces evolve at a chosen speed in the new frame. We couple the rescaling idea with boundary integral method to demonstrate the efficiency of the rescaling idea, though it can be applied to Cartesian-grid based method in general. As an example, we use the Hele-Shaw problem to examine the efficiency of the rescaling scheme. First, we apply the rescaling scheme to a slowly expanding interface. In the new frame, the evolution is dramatically accelerated, while the underlying physics remains unchanged. In particular, at long times numerical results reveal that there exist nonlinear, stable, self-similarly evolving morphologies. The rescaling idea can also be used to simulate the fast shrinking interface, e.g. the Hele-Shaw problem with a time dependent gap. In this case, the rescaling scheme slows down the interface evolution in the new frame to remove the severe time step constraint that makes the long-time simulations prohibitive. Finally, we study an analytical solution to the stability of the interface of the Hele-Shaw problem, assuming a small surface tension under a time dependent flux Q(t). Following [116, 109], we find the motions of daughter singularity ζd and simple singularity ζ0 do not depend on the flux Q(t). We also find a criterion to identify the relation between ζ0 and ζd.
Ph.D. in Applied Mathematics, July 2017
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Title: Aeroacoustic Features of Coupled Twin Jets with Spanwise Oblique Shock-Cells
Creator: Panickar, P., Srinivasan, K., Raman, G.
Date: 2004-11-22
Publisher: Academic Press Ltd Elsevier Science Ltd
Description: This paper experimentally investigates the aeroacoustics of coupled twin jets of complex geometry. The study was motivated by the fact that...
Show moreThis paper experimentally investigates the aeroacoustics of coupled twin jets of complex geometry. The study was motivated by the fact that twin jet configurations that are commonly used in aircraft propulsion systems can undergo unpredictable resonant coupling resulting in structural damage. Further, nozzles with spanwise oblique exits are increasingly being considered for their aerodynamic and acoustic advantages, as well as stealth benefits. Although several studies have examined aspects of twin jet coupling, very little data is available on the coupling of jets from nozzles of complex geometry. Our study focuses on twin convergent nozzles with an aspect ratio of 7 with spanwise oblique exits operated over the fully expanded Mach number range from 1.3 to 1.6. The inter-nozzle spacing (s/h) was varied from 7.4 to 13.5. However, the focus remained on the lower spacing that is more representative of aircraft applications. Several interesting results have emerged from this study: (1) Coupling of twin nozzles with a beveled exit was observed only when the beveled edges faced each other and the nozzles formed a 'V' shape in the inter-nozzle region. Specifically, if the two beveled edges were oriented away from each other to form an arrowhead (W) shape no coupling was observed. (2) Despite the presence of spanwise antisymmetric, spanwise symmetric and spanwise oblique modes for the single nozzles, only the first two modes were evident in the coupling. (3) The symmetric coupling produced unsteady pressures in the inter-nozzle region that were up to 7.5 dB higher than the antisymmetrically coupled case. (4) Dynamic tests conducted by moving the nozzles apart while they were operating or by continuously changing the stagnation pressure at fixed inter-nozzle spacing revealed that coupling modes could co-exist at non-harmonically related frequencies. These dynamic tests reproduced the static test data. (5) The frequency of both coupling modes agrees with the higher order waveguide modes based on Tam's theory. (6) Differences in broadband shock noise between the 'V' and 'A' configurations were also documented. Our results provide an understanding of complex twin jet coupling and will serve as benchmark data for validating computational models. (C) 2003 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.jsv.2003.10.011
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Title: The potential importance of low luminosity and high energy at the LHC, Proceedings of the XLIII International Symposium on Multiparticle Dynamics
Creator: White, Alan R.
Date: 2013-09-15, 2013-09-15
Publisher: IIT Press
Description: Low luminosity runs at higher LHC energy could provide definitive evidence for an electroweak scale sextet quark sector of QCD that produces...
Show moreLow luminosity runs at higher LHC energy could provide definitive evidence for an electroweak scale sextet quark sector of QCD that produces electroweak symmetry breaking and dark matter within the bound-state S-Matrix of QUD - a massless, weak coupling, infra-red fixed-point, SU(5) field theory that might underly and unify the full Standard Model.
Sponsorship: IIT College of Science, High Energy Physics Division of Argonne National Laboratory
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Title: Tests on a four-cycle automobile engine
Creator: Barrett, D. O., Morgan, C. W.
Date: 2009, 1908
Publisher: Armour Institute of Technology
Description: http://www.archive.org/details/testsonfourcycle00barr
Thesis (B.S.)--Armour Institute of Technology; Bibliography: leaves 1-3

Title: WIRELESS SCHEDULING IN MULTI-CHANNEL MULTI-RADIO MULTIHOP WIRELESS NETWORKS
Creator: Wang, Zhu
Date: 2014, 2014-07
Description: Maximum multi ow (MMF) and maximum concurrent multi ow (MCMF) in multi-channel multi-radio (MC-MR) wireless networks have been well-studied in...
Show moreMaximum multi ow (MMF) and maximum concurrent multi ow (MCMF) in multi-channel multi-radio (MC-MR) wireless networks have been well-studied in the literature. They are NP-hard even in single-channel single-radio (SC-SR) wireless networks when all nodes have uniform (and xed) interference radii and the positions of all nodes are available. This disertation studies maximum multi ow (MMF) and maximum concur- rent multi ow (MCMF) in muliti-channel multi-radio multihop wireless networks under the protocol interference model in the bidirectional mode or the unidirectional mode. We introduce a ne-grained network representation of multi-channel multi- radio multihop wireless networks and present some essential topological properties of its associated con ict graph. It was proved that if the number of channels is bounded by a constant (which is typical in practical networks), both MMF and MCMF admit a polynomial-time ap- proximation scheme under the protocol interference model in the bidirectional mode or the unidirectional mode with some additional mild conditions. However, the run- ning time of these algorithms grows quickly with the number of radios per node (at least in the sixth order) and the number of channels (at least in the cubic order). Such poor scalability stems intrinsically from the exploding size of the ne-grained network representation upon which those algorithms are built. In Chapter 2 of this dissertation, we introduce a new structure, termed as concise con ict graph, on the node-level links directly. Such structure succinctly captures the essential advantage of multiple radios and multiple channels. By exploring and exploiting the rich structural properties of the concise con ict graphs, we are able to develop fast and scalable link scheduling algorithms for either minimizing the communication latency or maximizing the (concurrent) multi ow. These algorithms have running time growing linearly in both the number of radios per node and the number of channels, while not sacri cing the approximation bounds. While the algorithms we develop in Chapter 2 admit a polynomial-time ap- proximation scheme (PTAS) when the number of channels is bounded by a constant, such PTAS is quite infeasible practically. Other than the PTAS, all other known approximation algorithms, in both SC-SR wireless networks and MC-MR wireless networks, resorted to solve a polynomial-sized linear program (LP) exactly. The s- calability of their running time is fundamentally limited by the general-purposed LP solvers. In Chapter 3 of this dissertation, we rst introduce the concept of interference costs and prices of a path and explore their relations with the maximum (concurrent) multi ow. Then we develop purely combinatorial approximation algorithms which compute a sequence of least interference-cost routing paths along which the ows are routed. These algorithms are faster and simpler, and achieve nearly the same approximation bounds known in the literature. This dissertation also explores the stability analysis of two link scheduling in MC-MR wireless networks under the protocol interference model in the bidirectional mode or the unidirectional mode. Longest-queue- rst (LQF) link scheduling is a greedy link scheduling in multihop wireless networks. Its stability performance in single-channel single-radio (SC-SR) wireless networks has been well studied recently. However, its stability performance in multi-channel multi-radio (MC-MR) wireless networks is largely under-explored. We present a stability subregion with closed form of the LQF scheduling in MC-MR wireless networks, which is within a constant factor of the network stability region. We also obtain constant lower bounds on the efficiency ratio of the LQF scheduling in MC-MR wireless networks under the protocol interference model in the bidirectional mode or unidirectional mode. Static greedy link schedulings have much simpler implementation than dy- namic greedy link schedulings such as Longest-queue-frst (LQF) link scheduling. However, its stability performance in multi-channel multi-radio (MC-MR) wireless networks is largely under-explored. In this dissertation, we present a stability subre- gion with closed form of a static greedy link scheduling in MC-MR wireless networks under the protocol interference model in the bidirectional mode. By adopting some special static link orderings, the stability subregion is within a constant factor of the stable capacity region of the network. We also obtain constant lower bounds on the throughput efficiency ratios of the static greedy link schedulings in some special static link orderings.
Ph.D. in Computer Science, July 2014
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Title: Presentation to CARLI collections group
Creator: Uth, Charles
Date: 2010-04-13T13:25:24Z

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