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(441 - 460 of 4,483)
Pages
- Title
- The synthetic manufacture of phenol
- Creator
- Parrot, Raymond D.
- Date
- 2009, 1919
- Publisher
- Armour Institute of Technology
- Description
-
http://www.archive.org/details/syntheticmanufac00parr
Thesis (B.S.)--Armour Institute of Technology
- Title
- THERMAL AND FLUID FLOW FEASIBILITY STUDY OF A CIRCULAR COUETTE FLOW REACTOR VIA PLANAR LASER-INDUCED FLUORESCENCE IMAGING
- Creator
- Bittner, Peter R.
- Date
- 2012-04-28, 2012-05
- Description
-
Liquid fueled microcombustors face many challenges in their development, the most prominent being high temperature gradients and radiative...
Show moreLiquid fueled microcombustors face many challenges in their development, the most prominent being high temperature gradients and radiative effects. Because the walls of microcombustors are thin, they offer very little resistance to conductive heat transfer, regardless of the materials used. This can cause very high heat losses that lead to large temperature gradients in the gas compared to nearly uniform temperatures inside conventional combustion chambers. In this investigation a circular Couette flow reactor (CCFR) and planar laser induced fluorescence (PLIF) are used to examine the feasibility of studying vapor distributions of a monodisperse acetone droplet stream, formed by a vibrating orifice aerosol generator (VOAG), exposed to combinations of varying velocity gradients, temperature gradients and radiant heating. The acetone droplets are injected through various ports on the CCFR to vary the time for vaporization of the droplets inside the reactor. Initial results of the operating CCFR uses acetone droplets seeded into the test section to demonstrate the fluorescence of the liquid and vapor acetone within the test section.
M.S. in Mechanical, Materials, and Aerospace Engineering, May 2012
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- Title
- Easy Access, Early Exit? The Internet and the FDLP (preprint)
- Creator
- Griffin, Luke A., Ahrens, Aric G.
- Date
- 2004-07
- Description
-
The article presents information on Federal Depository Library Program (FDLP). The majority of the twentieth century saw a marked growth in...
Show moreThe article presents information on Federal Depository Library Program (FDLP). The majority of the twentieth century saw a marked growth in the number of libraries participating in FDLP. The FDLP was established by Congressional resolution on December 27, 1813. On December 1, 1814, the American Antiquarian Society of Worcester, Massachusetts received the first documents distributed to a non-governmental body and became the first depository library. The primary purpose of the program was preservation of the historical record, not dissemination. Staff and funding issues and the availability of resources via the Internet points to the weight that libraries may be placing on the ability to provide information via the Internet on their decisions to remain in or to leave the FDLP. In today's work environment, in which increased productivity is expected and doing more with less is essential, the Internet can be an obvious alternative to physical collections, which require space and greater staff time and resources. In the last decade, the essential association between the ability to provide access to government information and participation in the FDLP has broken down.
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- Title
- EFFICIENT AND FAIR RESOURCE ALLOCATION FOR OFDMA NETWORKS
- Creator
- Alavi, Seyed Mohamad
- Date
- 2012-11-26, 2012-12
- Description
-
In Orthogonal Frequency Division Multiple Access (OFDMA) systems, resources, including subcarriers, bits and power, need to be adaptively...
Show moreIn Orthogonal Frequency Division Multiple Access (OFDMA) systems, resources, including subcarriers, bits and power, need to be adaptively allocated to users in order to improve spectral efficiency, increase capacity, and reduce power consumption, while satisfying the Quality of Service (QoS) requirements for users. Most of the previous works concentrate on satisfying rate and power requirements, however providing delay requirement is also necessary, especially with increasing demand on delay-sensitive applications. We first model the resource allocation problem as a cross-layer optimization problem considering the constraints on bit error rate (BER), data rate, total power, as well as delay. We first develop a nonlinear optimization model, which generally requires high computation complexity. To consider a more realistic scenario, we take into account imperfect Channel State Information (CSI) due to estimation errors or channel feedback delay, and incorporate the imperfect CSI into the optimization problem formulation. We then derive the solution through a dual decomposition method. Due to the duality gap between the original and dual optimizations, we convert the non-linear optimization to an equivalent linear formulation so that an exact solution can be obtained. To further reduce the complexity, we develop a heuristic algorithm to provide a solution close to the optimum. Then, we study the notion of fairness in the context of resource allocation. In particular, cooperative game theory can be applied to OFDMA networks for fair resource allocation. We apply two cooperative games, Non-Transferable Utility (NTU) game and Transferable Utility (TU) game, to provide fairness in OFDMA networks. In NTU game, fairness is achieved by defining appropriate objective function, while in TU game, fairness is provided by forming the appropriate network structure. For NTU game, we analyze the Nash Bargaining Solution (NBS) as a solution of NTU game taking into account CSI and Queue State Information (QSI). In a TU game, we show that coalition among subcarriers to jointly provide rate requirements leads to better performance in terms of power consumpviii tion. We show that although NTU and TU games are modeled as rate adaptive and margin adaptive problems, respectively, but both solutions provide a fair distribution of resources with minimum fairness index of 0.8. Although NBS can provide fairness, the fairness is not from user perspective. In competitive fairness, which is based on auction theory, each user is responsible for his/her own action. A distributed allocation of resources in OFDMA networks is studied through auction theory. A combinatorial auction is formulated in which the users’ utility enforce the truthful resource demands. Since the original problem is NP hard, a method based on simulated annealing applied to find near-optimum results. Then, we turn our attention toward a more complicated scenario of multicell OFDMA networks. A combinatorial auction, which takes into account the interference from adjacent cells is presented. Auction objective is to minimize the interference, while power of users is limited. Due to the complexity of original problem, we apply a heuristic approach, in which the bids are ordered based on the linear programming approximation of combinatorial auction, and then local improvements are made in the order of bids. Our iterative approach along with the proposed load control scheme provides fair distribution of resources to the users, regardless of their position in the cell. Finally, we propose a comprehensive auction in OFDMA network. We present an auction framework for allocation of subcarriers, in which winner pays monitoring and entry fees, in addition to the price which he is paying for the allocated subcarrier. We prove that in our framework users will avoid bidding for the subcarriers where they have a relatively low chance of winning. We obtain optimal bidding strategy based on Bayesian Nash Equilibrium (BNE) in which users are maximizing their net profit. In a Fractional Frequency Reuse (FFR) implementation of frequency planning, we will find a focal distance which classifies the users into cell-center and cell-edge users. It is shown that the focal distance increases as the interference decreases.
PH.D in Electrical Engineering, December 2012
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- Title
- Finding Uses for Alternative Fuels in Intermodal Transportation Hubs (sequence unknown), IPRO 307 - Deliverables
- Creator
- Balakirev, Konstantin, Beau‐luby, Ryan, Bouikidis, John, Cargill, Matthew, Dziuba, David, Kehoe, Matthew, Slonski, Bryan, Tesfaye, Melat, Wiese, Matthew, Wiseman, Christopher, Zook, Joel
- Date
- 2009-12
- Description
-
Chicago, being the third largest freight hub in the world, needs an efficient movement of goods for the increasing freight shipments.
Sponsorsh...
Show moreChicago, being the third largest freight hub in the world, needs an efficient movement of goods for the increasing freight shipments.
Sponsorship: Mi-Jack
Deliverables for IPRO 307: Finding Uses for Alternative Fuels in Intermodal Transportation Hubs for the fall 2009 semester.
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- Title
- Static and dynamic behavior of autocatalytic replicators in reactor networks
- Creator
- Tatara, E., Birol, I., Teymour, F., Cinar, A.
- Date
- 2004-07-07
- Publisher
- AMER CHEMICAL SOC
- Description
-
The static and dynamic behavior of the autocatalytic reaction R + 2P --> 3P with decay P --> D is studied in networks of coupled continuous...
Show moreThe static and dynamic behavior of the autocatalytic reaction R + 2P --> 3P with decay P --> D is studied in networks of coupled continuous stirred tank reactors (CSTRs). Numerical bifurcation studies of the system are performed, resulting in rich steady-state bifurcation structures with multiple steady states and isolas. The heterogeneity of the networks is influenced by the number of reactors as well as the network topology. It is shown that the number of steady states of the network increases with heterogeneity, thereby allowing those autocatalytic species to exist in the network that would normally not exist in the homogeneous environment of a single CSTR. Spatial patterns of stable steady states are evident in reactor networks. Dynamic simulation studies are performed to illustrate the transition from one stable state configuration to another or from stable steady states to periodic regimes.
Endnote format citation for DOI:10.1021/ie030802d
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- Title
- EFFECTIVENESS OF CLEANING REGIMENS FOR REMOVING PEANUT, MILK AND EGG RESIDUE FROM PILOT-SCALE CEREAL BAR AND MUFFIN PROCESSING LINES
- Creator
- Zhang, Xi
- Date
- 2014, 2014-07
- Description
-
Allergen cross-contact can be caused by inadequate cleaning of shared processing equipment. The objectives of this project were to evaluate...
Show moreAllergen cross-contact can be caused by inadequate cleaning of shared processing equipment. The objectives of this project were to evaluate the effectiveness of cleaning regimens on removing allergenic food residue from a pilot-scale cereal bar and muffin processing lines and measure the levels of allergens (peanut, milk and egg) transferred into allergen-free (control) cereal bars and muffins processed on an inadequately cleaned processing line. Another object was to investigate the analytical methods used (conventional ATP, sensitive ATP, total protein and lateral flow) to evaluate the effectiveness of allergen cleaning procedures. Cereal bars and muffins containing peanut flour, nonfat dry milk and egg powder (1000 or 5000 g/g for cereal bar and 100 or 5000 g/g for muffin) were manufactured on a pilot-scale processing line followed by one of four cleaning regimens: 1) push-through with control cereal bar dough or muffin batter, 2) scraping the equipment surfaces with rubber scrapers, 3) a rinse with hot (54-60°C) water until “visibly clean” and 4) a full cleaning cycle with alkaline detergent followed by use of a sanitizer. The adequacy of the cleaning treatments was assessed by swabbing locations (3 swabs/location) on the processing lines (cereal bar: mixer, depositor, conveyor belt; muffin: mixer, depositor, nozzle) followed by analysis of swabs with peanut-, milk-, and egg-specific lateral flow devices (LFDs). The cereal bar crosscontact study involved obtaining samples of the sheeted control dough transferred over the conveyor belt at 2 min intervals over a 30 min time span, or after approximately 100 kg of cereal bar dough was processed over the line previously contaminated with 5000 g/g allergen-incurred cereal bars. Similarly, allergen cross-contact from the contaminated muffin processing line into control muffins was measured by collecting xi 750g of control muffin batter until a total of 36 kg of batter were deposited. This was followed by allergen analysis of cereal bar and muffin samples (before and after baking) using quantitative ELISA kits. Results of LFD tests indicated that hot water rinse was effective for cereal bar processing line but not for the muffin line. Only the full cleaning cycle was effective at removing allergenic food residues for both processing lines. During the cross-contact study, substantial levels of peanut, milk and egg were detected in samples obtained both before and after baking. Cereal bar dough produced on the contaminated lines contained up to 71.9 ± 48.9 μg/g egg, 23.3 ± 1.3 μg/g milk, and 5.0 ± 0.4 μg/g peanut and as high as 2929.7 ± 98.8 μg/g egg, 1894.9 ± 87.7 μg/g milk, and 193.2 ± 20.6 μg/g peanut in muffin batter. Overall, these results illustrate the importance of validated cleaning protocols for preventing allergen cross-contact on shared processing lines.
M.S. in Food Safety and Technology, July 2014
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- Title
- A study of a suction gas producer
- Creator
- Hoffman, Balthasar
- Date
- 2009, 1907
- Publisher
- Armour Institute of Technology
- Description
-
http://www.archive.org/details/studyofsuctionga00hoff
Thesis (B.S.)--Armour Institute of Technology
- Title
- AN ANALYTICAL MODEL FOR SWITCHED RELUCTANCE MACHINE WITH HIGHER NUMBER OF ROTOR POLES
- Creator
- Jia, Yijiang
- Date
- 2012-05-08, 2012-05
- Description
-
With growing interest in renewable energy technology and hybrid electric vehi- cle systems owing to environmental concerns and depleting...
Show moreWith growing interest in renewable energy technology and hybrid electric vehi- cle systems owing to environmental concerns and depleting fossil fuel reserves, electric machines have received widespread attention as a key component in the successful im- plementation of high efficiency drives. Towards this goal, the last two years have seen a significant increase in research in permanent magnet-alternative machine topologies. This has primarily been because of growing concerns over foreign dependence for rare- earth materials and a dramatic increase in the cost of permanent magnets. Switched Reluctance Machine (SRM) has been one of the leading contenders in this category. It does not require any permanent magnets, and is very suitable for operation in harsh operating environments. Furthermore, this machine has simple construction and is highly fault-tolerant with one of the widest operating speed ranges. Nowadays, it has found wide application in the automotive, aerospace as well as domestic area. How- ever conventional SRM suffers from modeling complexity and torque ripple during the phase commutation with the same origin. Using the novel PD formula proposed at the Illinois Institute of Technology, a new family of machines has been developed with a significant improvement in torque ripple. Owing to its novel configuration, analytical models for the design of advanced driver system design have also not been developed. In this study, an analytical model for the novel 6/10 SRM has been proposed. The machine model is characterized using an inductance model utilizing truncated Fourier series as well as multi-order polynomial curve-fitting algorithm. The induc- tance model is extended to back-EMF and electromagnetic torque models on purpose of obtaining the whole information for every single operating point of the machine during dynamic operation. The effectiveness of the proposed concept has analyzed for a prototype machine in the laboratory and verified using Finite Element Analysis. From this study, an algorithm has been proposed to develop the analytical model for the family of SRMs with higher number of rotor poles.
M.S. in Electrical Engineering, May 2012
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- Title
- Washington Park Center for Improvisational Music
- Creator
- White, Kellen
- Date
- 2010-07-30
- Title
- Power Measurement for Road Bicycles: Towards a Universal Solution (sequence unknown), IPRO 324 - Deliverables: IPRO 324 Midterm Presentation F09
- Creator
- Adrianzen, Luis, Allen, Ross, Antonio, Chris, Callan, Mark, Claxton, Sara, Diesse, Patrick, Gaylord, Matthew, Herbert, Greg, Shaffer, Dan, Wegrzyn, Celeste
- Date
- 2009-12
- Description
-
The goal of the IPRO is to try to find an inexpensive, but accurate way of measuring the power output of a rider on a bicycle. Problems with...
Show moreThe goal of the IPRO is to try to find an inexpensive, but accurate way of measuring the power output of a rider on a bicycle. Problems with systems currently available are: some products are not compatible with all bike systems causing the need to purchase new parts, the cost of the available products is expensive, and some of the available measuring systems are not very accurate.
Deliverables for IPRO 324: Power Measurement for Road Bicycles: Towards a Universal Solution for the fall 2009 semester
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- Title
- GROWTH, INACTIVATION, AND SURVIVAL OF SALMONELLA ON SESAME SEEDS DURING TAHINI PROCESSING AND REFRIGERATED STORAGE OF TAHINI
- Creator
- Zhang, Yangjunna
- Date
- 2016, 2016-05
- Description
-
Salmonella can survive for long period of time in low-moisture foods and cause human illness after consumption of contaminated foods. Recently...
Show moreSalmonella can survive for long period of time in low-moisture foods and cause human illness after consumption of contaminated foods. Recently, sesame seeds and tahini (sesame seeds pasta), have been identified as unusual sources of salmonellosis. Controlling specific steps during tahini processing and storage of tahini may minimize the risk of Salmonella contamination. This study examined the fate of Salmonella in different steps of tahini processing and refrigerated storage of tahini. A four serovar cocktail of Salmonella was used for inoculation of sesame seeds and tahini. Bacterial populations were determined by aerobic plate counts on both selective and non-selective media. Water activity of samples was determined during processing and storage. For the soaking step during tahini processing, unhulled dry sesame seeds with aw of 0.1 were inoculated with Salmonella, held 24 h, and then soaked in water at ambient temperature. Populations were monitored at 0, 18, 22 and 24 h. Salmonella decreased by 2 - 3-log CFU/g during drying and then increased by 5 log CFU/g after rehydration. Separately, inoculated de-hulled seeds with two different initial aw were roasted at three different temperatures (95, 110, and 130 ºC) for 90 min. Both the Salmonella populations and aw were determined at 10 min intervals during roasting. Finally, inoculated sesame seeds were processed into tahini. As a comparison, the same quantity of uninoculated roasted sesame seeds were processed into tahini, and then inoculated post-processing. Tahini was stored at 4 ºC for 17 weeks. Approximately 8 log CFU/g of Salmonella was detected initially in the sesame seeds prior to roasting with a 1-log CFU/g reduction after 20 min at 95 ºC when the aw of seeds decreased quickly. For different roasting temperatures, the aw declined much faster and stopped decreasing during roasting, while populations continue decreasing throughout the whole roasting. To investigate survival of Salmonella during refrigerated storage of tahini, approximately 9 log CFU/g of Salmonella was inoculated onto sesame seeds or into processed tahini without significant reduction throughout 17 weeks (p > 0.05). These results suggest that Salmonella contamination can be an issue at any step of tahini manufacture.
M.S. in Food Safety and Technology, May 2016
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- Title
- STRUCTURE AND FUNCTION OF NATIVE AND EDITED DYSTROPHIN RODS
- Creator
- Sahni, Neha
- Date
- 2011-05-10, 2011-05
- Description
-
The purpose of this study is to examine the biophysical properties of the rod region of the dystrophin protein. This is important due to the...
Show moreThe purpose of this study is to examine the biophysical properties of the rod region of the dystrophin protein. This is important due to the severity of the disease Duchenne Muscular Dystrophy, (DMD), which is associated with the malfunction of this protein. DMD is one of the most serious single gene genetic defects of man. This rod region consists of a number of repeat motifs called spectrin type repeats or STRs. The thermodynamical and biochemical stability analysis shows, which single motifs are unstable on their own and which ones become more stable when linked to their appropriate tandem neighbors. This knowledge will impact strategies to produce modified mini dystrophins for gene therapy. Exon skipping therapy is an emerging approach to treat such genetic diseases. This is done by the administration of modified antisense oligonucleotides, AONs, which can interfere with exon splicing process and eliminate certain exons from the mature transcript. Furthermore, the rod region has a number of ancillary functions, such as providing secondary binding sites for actin, neuronal NO synthetase and phospholipids, which may be adversely perturbed by the edits.
Ph.D. in Biological, Chemical, and Physical Sciences, May 2011
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- Title
- Elementary Charter School: Renovation and Addition
- Creator
- Hutchison, William
- Date
- 2010-07-29
- Title
- Flow characteristics of a rectangular multielement supersonic mixer-ejector
- Creator
- Taghavi, R, Raman, G
- Date
- 1996-10
- Publisher
- AMER INST AERONAUT ASTRONAUT
- Title
- PERINATAL PHOTOPERIOD AND LATITUDE AS PREDICTORS OF REACTION TO CHRONOBIOLOGICAL STRESS
- Creator
- Antler, Caroline A.
- Date
- 2013-04-24, 2013-05
- Description
-
The present study explored the possible roles of perinatal photoperiod and latitude as predictors of later reaction to chronobiological stress...
Show moreThe present study explored the possible roles of perinatal photoperiod and latitude as predictors of later reaction to chronobiological stress, specifically the experience of winter in Chicago (41.89°N). Participants consisted of new undergraduate and graduate students at a technological university in Chicago, Illinois (N = 64 - 76). The sample was 62% male, ranged in age from 18 to 38 years (M = 22.5, SD = 4.3), and was born mainly in North America and East/South Asia. The vegetative and cognitive/affective subscales of the Seasonal Assessment Form (SAF; Young et al., 2012) were completed by participants between February 7 and March 7, 2011. Results indicated that both perinatal photoperiod and latitude have a significant effect on vegetative but not cognitive symptom severity. A curvilinear relationship between perinatal photoperiod and winter vegetative symptom severity was displayed with optimal adjustment (minimum vegetative symptoms) occurring near LD 12:12. Attention should be paid to the stronger effect of latitude at birth over perinatal photoperiod on symptom severity. Implications, limitations, and future directions for research are discussed.
M.S. in Psychology, May 2013
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- Title
- Jet Thrust Vectoring Using a Miniature Fluidic Oscillator
- Creator
- Raman, G., Packiarajan, S., Papadopoulos, G.
- Date
- 2005-03
- Publisher
- Royal Aeronautical Soc
- Description
-
This paper presents a new approach to vectoring jet thrust using a miniature fluidic actuator that provided spatially distributed mass...
Show moreThis paper presents a new approach to vectoring jet thrust using a miniature fluidic actuator that provided spatially distributed mass addition. The fluidic actuators used had no moving parts and produced oscillatory flow with a square wave form at frequencies up to 1(.)6kHz. A subsonic jet with an exit diameter of 3(.)81cm was controlled using single and dual fluidic actuators, each with an equivalent circular diameter of 1(.)06mm. The fluidic nozzle was operated at pressures between 20(.)68 and 165(.)47kPa. The objectives of the present work included documentation of the actuation characteristics of fluidic devices, assessment of the effectiveness of fluidic devices for jet thrust vectoring, and evaluation of mass flow requirements for vectoring under various conditions. Measurements were made in the flow field using a pitot probe for the vectored and unvectored cases. Some acoustic measurements were made using microphones in the near-field and for selected cases particle image velocimetry (PIV) measurements were made. Thrust vectoring was obtained in low speed jets by momentum effects with fluidic device mass flow rates of only 2 x 10(-4) kg/sec (0-6% of main jet mass flow per fluidic oscillator). Although a single fluidic device produced vectoring of the primary jet, the dual fluidic device configuration (with two fluidic devices on either side of the jet exit) produced mass flux enhancement of 28% with no vectoring. Our results indicate that fluidic actuators have the potential for use in thrust vectoring, flow mixing and industrial flow deflection applications.
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- Title
- NEW TOOLS FOR JET ANALYSIS IN HIGH ENERGY COLLISIONS
- Creator
- Duffty, Daniel
- Date
- 2015, 2015-05
- Description
-
Our understanding of the fundamental interactions of particles has come far in the last century, and is still pushing forward. As we build...
Show moreOur understanding of the fundamental interactions of particles has come far in the last century, and is still pushing forward. As we build ever more powerful machines to probe higher and higher energies, we will need to develop new tools to not only understand the new physics objects we are trying to detect, but even to understand the environment that we are searching in. We examine methods of identifying both boosted objects and low energy jets which will be shrouded in a sea of noise from other pasts of the detector. We display the power of boosted-b tagging in a simulated W' search. We also examine the effetc of pile up on low energy jet reconstructions. For this purpose we develop a new priority-based jet algorithm, "p-jets", to cluster the energy that belongs together, but ignore the rest.
Ph.D in Physics, May 2015
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- Title
- INFLUENCE OF FOUR BACILLUS SP. STRAINS ON GROWTH AND DESULFURIZATION ABILITY OF MYCOBACTERIUM STRAIN U
- Creator
- Tian, Fangzhou
- Date
- 2016, 2016-05
- Description
-
Desulfurization is an important step in crude oil processing and is commonly achieved through a chemical process known as hydrodesulfurization...
Show moreDesulfurization is an important step in crude oil processing and is commonly achieved through a chemical process known as hydrodesulfurization (HDS). Because this process is expensive and produces H2S as a by-product, the alternative of biodesulfurization (BDS) has been investigated for many years. The most potentially useful biodesulfurization process is the 4S pathway, which is found in a number of bacterial species, including Mycobacterium Strain U, which was isolated in our lab. To reach the requirement of BDS for use in an actual industrial-scale process, U has to survive at temperatures approaching 60 OC. In work in our lab, natural selection methods have been introduced for improving the U strain. During this natural selection, four contaminant strains, identified by 16S rDNA sequencing as Bacillus sp., were isolated from extraordinary U cultures which have BDS activity at 54 OC. Meanwhile the BDS activity of U on its own was found to have an upper temperature limitation of 53 OC. Additional experiments proved that all four Bacillus strains interact with U and improve its BDS ability.
M.S. in Biology, May 2016
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- Title
- SIMULATIONS OF CENTERLINE DEFECT CLOSURE IN OPEN DIE FORGING
- Creator
- Gangatirkar, Suhasini
- Date
- 2014, 2014-12
- Description
-
Open die forging is a technique widely used to achieve desired shape and sound mechanical properties. Due to large sizes, the ingots often...
Show moreOpen die forging is a technique widely used to achieve desired shape and sound mechanical properties. Due to large sizes, the ingots often have internal defects such as porosity, shrinkage cavities which damage the overall quality of the final product and affect the mechanical properties of the material. The voids developed during cooling of the ingot have to be treated in the initial forming operation known as cogging which depends on parameters such as die width ratio, die overlap, feed ratio, die shape etc. In this work, finite element method has been used to identify different aspects affecting centerline defect closure, material properties, effect of friction coefficient, relationship between effective strain and the grain size. FORGE 2011 and FORGE NxT 1.0 by Transvalor Corp were used to create numerical models. The material used in this case is H13. Material data and compression test samples were obtained from experiments in a Gleeble 3500. Physical experiments carried out on the Gleeble 3500 were used to determine the coefficient of friction for samples treated at different temperature, strain and strain rates. The effect of these parameters on coefficient of friction was studied in later part of the study. The formulae from the literature used to calculate the coefficient of friction was validated by using simulation models of the compression test samples. These samples were also used to study fraction recrystallized for a particular sample to study the relationship between effective strain and microstructure. Comparisons between validation experiments and simulations showed that there was good agreement between the two and established the effective strain criterion for void closure. From the conclusions obtained from validation experiments, optimal pass schedule was developed to ensure closure of internal voids and uniform distribution of effective strain along centerline for sound quality of the workpiece by changing die overlap percentage every two passes.
M.S. in Material Science Engineering, December 2014
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