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Title: THE EVALUATION OF THERMAL INACTIVATION OF COXIELLA BURNETII NINE MILE PHASE II IN BOVINE AND NON-BOVINE MILKS BY MOST PROBABLE NUMBER-POLYMERASE CHAIN REACTION (MPN-PCR) ASSAY
Creator: Zhang, Cheng
Date: 2016, 2016-05
Description: As non-bovine milks become popular for human consumption, ensuring that standard bovine milk pasteurization conditions provide enough...
Show moreAs non-bovine milks become popular for human consumption, ensuring that standard bovine milk pasteurization conditions provide enough treatment for non-bovine milks is significant for food safety. Coxiella burnetii, an obligate intracellular bacterium, has been used as the reference microorganism for defining milk pasteurization conditions. To evaluate C. burnetii thermal inactivation in bovine and non-bovine milks at commercial pasteurization temperature, an MPN-PCR assay was developed to quantitate viable C. burnetii in milk. Using this assay, the thermal inactivation of C. burnetii and a potential nonpathogenic surrogate, Micrococcus luteus, was tested in bovine, buffalo, camel and goat milks. Milk in sealed glass vials was pre-heated in a water bath at 72°C and inoculated via a syringe with C. burnetii and M. luteus at a final concentration of ~6.5 log10 ge/mL (CFU/mL) each. The inoculated milk was heat-treated at 72°C for up to 16 sec, cooled in a crushed ice bath and serially diluted. Viable M. luteus was quantitated by plating on BHIA plates. For C. burnetii detection, 1 mL of each dilution was inoculated into 9 mL Acidified Citrate Cysteine Medium-2 (ACCM-2) in triplicate T-25 flasks to produce a 3- flask Most Probable Number (MPN) assay. Viability of C. burnetii was considered positive if an increase of ≥0.5 log10 ge/mL was detected by qPCR after 14 d growth in ACCM-2 media. The numbers of positive flasks at each dilution were used to calculate the remaining viable C. burnetii by MPN method. The average D-values for 72°C inactivation were 1.99 ± 0.21 sec, 0.79 ± 0.28 sec, 1.43 ± 0.30 sec, and 2.06 ± 0.71 sec for C. burnetii, and 5.47 ± 0.94 sec, 3.65 ± 0.45 sec, 3.48 ± 0.83 sec and 5.34 ± 1.54 sec for M. luteus in bovine, buffalo, camel and goat milks, respectively. For C. burnetii, D-values in camel and goat milks were not significantly different (p>0.05) from bovine milk, but the D-value in buffalo milk was significantly lower (p<0.05). These results indicate that non-bovine milks may not be a safety concern under standard milk pasteurization conditions, and M. luteus could be a good surrogate for C. burnetii thermal inactivation in milk.
M.S. in Food Safety and Technology, May 2016
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Title: FLOW DISTRIBUTION AND TURBULENCE CHARACTERISTICS IN AN URBAN ENVIRONMENT
Creator: Goudarzi, Sepehr Aboutorabi
Date: 2014, 2014-12
Description: The amount of the urban flow studies has been excessively increased during past decade. Pollutant dispersion quality has been the main...
Show moreThe amount of the urban flow studies has been excessively increased during past decade. Pollutant dispersion quality has been the main motivation in these investigations. Besides, a more recent goal is to provide a spatial map of the flow distribution which can be used for micro aerial vehicles (MAV) flight control. These all have developed advanced methodologies in both computational and experimental researches. In this study flow distribution and characteristics are investigated in a 7×5 urban array model (blocks are representing buildings) in a low-speed wind tunnel. Stereoscopic Particle Image Velocimetry (SPIV) is employed as the velocimetry method to acquire three-dimensional velocity filed in the three-dimensional region of street areas. A large amount of SPIV data was acquired in four consecutive streets for four wind incidence angle. The evolution of the three-dimensional coherent structures is investigated. Also, flow characteristics are studied using parameters such as mean velocity, turbulent kinetic energy (TKE), vorticity magnitude and Reynolds stress tensor components. All flow characteristics are studied in four consecutive streets of the array. Also, the effects of the wind direction on the flow characteristics and arch vortex location are studied. A valuable achievement of this study is to suggest a method to find the location of the arch vortex legs, and find the angle between the arch horizontal axis with the spanwise direction (𝜑). It is shown that this angle is increasing significantly in variation of angle of incidence (AOI) in the range of 𝐴𝑂𝐼=0° to 𝐴𝑂𝐼=15°. The rate of increment of 𝜑 is much slower between 𝐴𝑂𝐼=15° and 𝐴𝑂𝐼=30° but the 𝜑 range is still greater than AOI. Existence of geometrical symmetry in 𝐴𝑂𝐼=0° case, brings unique features for this condition such as zero spanwise flow velocity in streets.. Increasing AOI to higher magnitudes will cause severe change in flow distribution and turbulence level, in the sense that turbulence intensity starts to impoverish.
M.S. in Mechanical and Aerospace Engineering, December 2014
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Title: ANTENNA LOCATION DESIGN IN DOWNLINK DISTRIBUTED ANTENNA SYSTEM
Creator: Zhang, Peng
Date: 2015, 2015-07
Description: In recent years, Wireless cellular network design with distributed antenna system (DAS) has received much attention for its ability to extend...
Show moreIn recent years, Wireless cellular network design with distributed antenna system (DAS) has received much attention for its ability to extend the cell coverage, improve spectral efficiency and increase the system capacity. Instead of locating all antennas at the cell center in the centralized antenna systems (CAS), distributed antenna basements in the DAS are separated geographically, which has been wide implemented to cover the dead spots and improve the system efficiency in wireless communication systems The mainly purpose of this research is to find optimal antenna locations that maximize the cell average ergodic capacity for the distributed-antenna system in downlink applied condition. Squared distance criterion (SDC) will be considered to offer an object function to maximize the lower bound of the cell average ergodic capacity. Existed analyses for location design in distributed antenna system are based on the uniform distribution without considering other cell interference. Considering other cell interference, I derive the analytical antenna location position for the infinite uniform distribution linear cell. For multi-cell applied condition implementation, I get reasonable locations of the applied condition by applying K-means algorithm to generating the initial values and find the optimal location. In order to solve the multi-cell scenario considering other-cell interference, I change the existed algorithm and simulation results show the performance of the obtained antenna location with changed algorithm offer a higher performance than the original one. I propose a circle initial setup to generate the initial points for relative location and converge fitting. The simulation has showed the initial setup I proposed significant reduce the computation in the antenna location design in applied downlink scenario.
M.S. in Electrical Engineering, July 2015
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Title: A study of water distribution from automatic sprinklers
Creator: Schmidt, J. L., Alling, C. R
Date: 2009, 1907
Publisher: Armour Institute of Technology
Description: http://www.archive.org/details/studyofwaterdist00schm
Thesis (B.S.)--Armour Institute of Technology, 1907 B. S. in Fire Protection Engineering,...
Show morehttp://www.archive.org/details/studyofwaterdist00schm
Thesis (B.S.)--Armour Institute of Technology, 1907 B. S. in Fire Protection Engineering, 1907
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Title: A system of automatic train control
Creator: Morgan, Charles Woodward
Date: 2009, 1911
Publisher: Armour Institute of Technology
Description: http://www.archive.org/details/systemofautomati00morg
Thesis (B.S.)--Armour Institute of Technology, 1911 Includes bibliographical references...
Show morehttp://www.archive.org/details/systemofautomati00morg
Thesis (B.S.)--Armour Institute of Technology, 1911 Includes bibliographical references and index B.S. in Mechanical Engineering, 1911
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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: 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: 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: Elementary Charter School: Renovation and Addition
Creator: Hutchison, William
Date: 2010-07-29

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: 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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Title: ANALYSIS AND PROTOTYPING OF ENERGY HARVESTING SYSTEM BASED ON DIELECTRIC ELECTRO ACTIVE POLYMER
Creator: He, Peiwen
Date: 2012-04-26, 2012-05
Description: Energy harvesting is a new emerging technology which is used to gather am- bient energy from all surroundings. Dielectric Electro Active...
Show moreEnergy harvesting is a new emerging technology which is used to gather am- bient energy from all surroundings. Dielectric Electro Active Polymer (DEAP) is a new material for energy harvesting based on mechanical-to-electric energy conversion. By using MATLAB simulation, a new system design based on DEAP is proposed to harvest energy. In the proposed system, the energy harvesting and the feedback cir- cuit loops can keep the system working without an external source. The simulation results show that the proposed system can harvest energy, and the bias voltage can be supplied by the system itself. Hence, no external source is needed. For circuit level design, based on two different vibration input patterns in terms of mechanical vibration frequency and displacement, two topologies of system forward paths which include DEAP generator, voltage regulation circuit and DC-DC buck converter are designed. For the low frequency high displacement vibration input pattern, a low frequency forward path is developed by using Zener diode regulator. For the high frequency low displacement input pattern, a high frequency forward path is designed by using Butterworth low pass filter. PSPICE simulation results prove that both of the proposed circuits work properly to generate steady DC voltage for energy harvesting. Finally, a prototyping circuit including a low pass filter and a battery charging module is implemented in experiment to verify the feasibility of partial system func- tion. The results show that the prototyping circuit for the proposed energy harvesting system by using DEAP can work well.
M.S. in Electrical Engineering, May 2012
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Title: A 2-GHZ FREQUENCY MULTIPLIER BASED ON DIGITAL DELAY LOCK LOOP IN 65 NM CMOS
Creator: Zhang, Kaiqiang
Date: 2017, 2017-05
Description: Generally phase lock loops (PLLs) are utilized in the implementation of the conventional clock generators and frequency multipliers. However...
Show moreGenerally phase lock loops (PLLs) are utilized in the implementation of the conventional clock generators and frequency multipliers. However there are some issues happened during designing PLLs. First of all, PLLs has a stability issue due to its higherorder systems. And this issue will cause the change of the loop bandwidth when PVT is different. Secondly, in PLLs, the output of the VCO will be fed back to the loop, which causes a peak phase error unexpectedly larger than the desired phase variation since jitter is accumulating over the oscillation cycles. These issues will make the design of a PLLbased frequency multiplier more complicated and challenging. In order to solve these issues, this thesis presents a 2-GHz frequency multiplier based on digital delay lock loop. In this design when the DLL is locked the digital DLL operated in the open-loop mode will reduce the jitter and power consumption due to dithering in the lock condition. In this design a compensation structure is proposed to keep track of any potential phase error caused by environmental variations. The reference input frequency is 500M Hz. This frequency multiplier is designed and fabricated in a 65nm CMOS. The thesis also provides theory and simulation results on frequency multiplier for readers.
M.S. in Electrical Engineering, May 2017
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Title: A DEVICE-TO-DEVICE COMMUNICATION AND KEY EXCHANGE APPLICATION OVER WI-FI DIRECT
Creator: Hong, Weisheng
Date: 2014, 2014-12
Description: With the rapid growth of smartphone and tablet users, Device-to-Device (D2D) communications have become an attractive solution for enhancing...
Show moreWith the rapid growth of smartphone and tablet users, Device-to-Device (D2D) communications have become an attractive solution for enhancing the performance of traditional cellular networks. However, relevant security issues involved in D2D communications have not been addressed yet. In this thesis, I investigate the security requirements and challenges for D2D communications, and present a secure and efficient key agreement protocol, which enables two mobile devices to establish a share secret key for D2D without prior knowledge. The mobile devices are playing an important role in our social life. People trend to share their files and chat with each other without Wi-Fi. Wi-Fi Direct technology provides a very good way to satisfy people’s need. After established a security D2D communication, I used the socket communication method to implement the chat function between devices and some protocols to enable the files transmitted. In the file transfer function, my demo support any types of the files. In the chat function, my demo also uses the shared secret to encrypt the message and then the receiver can decrypt it with the shared secret.
M.S. in Electrical Engineering, December 2014
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Title: FACTORS AFFECTING THE SANITIZER EFFICACY IN PREVENTING SALMONELLA TRANSFER DURING POSTHARVESTWASHING OF CUT LETTUCE
Creator: Zang, Mingxia
Date: 2014, 2014-07
Description: This study investigated the spread of Salmonella during postharvest washing of contaminated lettuce and determined the factors that affect the...
Show moreThis study investigated the spread of Salmonella during postharvest washing of contaminated lettuce and determined the factors that affect the efficacy of chlorine in preventing Salmonella cross-contamination. A bench-scale washing system was assembled. It consisted of a 15 gal tank equipped with a submersible pump and various probes to measure wash water properties including pl-l, temperature, chlorine level. oxidation reduction potential (ORP), turbidity, and total organic carbon (TOC) level. Eight grams of cut romaine lettuce inoculated with approximately 7 log CFU/g of Salmonella typhimurium expressing green fluorescent protein were added to 40 L of sterile tap water or spent wash water collected from a commercial produce processing facility together with 800 g of uninoculated lettuce and washed for 2 min. Washing trials were performed at 3°C under different levels of chlorine treatment (0. 5, 10, 20 and 30 ppm of sodium hypochlorite). Small-scale (100 mL) experiments were performed to determine the effects of organic matter (lettuce homogenate) and solids (play sand) on the efficacy of chlorine in wash water. Without chlorine treatment, the spread of Salmonella occurred during lettuce washing in both sterile tap water and in spent industry water. With 5 ppm ofchlorine. although no Salmonella was detected in the wash water, the pathogen was found in the uninoculated lettuce after culture enrichments. When the chlorine level increased to either 10 or 20 ppm of chlorine, no Salmonella was detected in the wash water or the uninoculated lettuce. Similar experiments were performed using the spent industry water. Salmonella transfer occurred at chlorine of 10 or 20 ppm. Transfer was prevented when the chlorine level was raised to 30 ppm. IX Data from the small-scale experiments indicated that the increase in organic contents resulted in a lower level of free chlorine and a greater survival of Salmonella. At 5 ppm of chlorine, the level of Salmonella increased from not detectable « 1 log CFU/ml) to completely unaffected (4.3 ± 0.4 log CFU/ml) when the TOC level increased from 10.6 ± 10.4 to 164.0 ± 21.2 mg/L. Also, the increase in solid contents led to a greater survival of Salmonella even though the free chlorine level remained unchanged. At 0.5 ppm of chlorine, the level ofSalmonella increased from not detectable « 1 log CFU/ml) to completely unaffected (4.2 ± 0.1 log CFU/ml) when the turbidity level increased from 0.7 ± 0.5 to 378.2 ± 53.5 NTU. In summary, the use of sufficient chlorine could prevent Salmonella cross-contamination but the effective chlorine level was affected by the organic load and solid content present in the wash water. Since the chlorine efficacy was the key to preventing cross-contamination and organic load was an important factor affecting the chlorine efficacy, measurements of the organic load was needed to determine the level ofchlorination needed in the wash water. However, current methods for measuring TOC took a few hours to perform. Turbidity measurements which could be done in a minute had been frequently used in the produce industry to determ ine wash water quality. In this study. it was found that a linear correlation could be established between turbidity and TOC suggesting that turbidity could be a good predictor of the organic load in produce wash water.
M.S. in Food Safety and Technology, July 2014
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