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Title: A NOVEL HYDROPONICS SYSTEM FOR PRODUCING SAFE AND HEALTHY SPROUTS
Creator: Azizinia, Mehdi
Date: 2019
Description: Sprouts can be considered as one of the most nutritious and cheap nutritional sources. Due to these advantages, sprouts consumption has...
Show moreSprouts can be considered as one of the most nutritious and cheap nutritional sources. Due to these advantages, sprouts consumption has increased significantly in recent decades. However, because of their susceptible nature to microbial growth, numerous outbreaks associated with this fresh produce have occurred and thus the safety of the sprout is of major concern. A novel kinetic hydroponics system (KHS) was developed to optimize an improve safe sprout production. In KHS, sprouting seeds are able to grow under water while air is continuously introduced. In this study, effect of various airflow rates and light on yield, germination percentage, and physical properties of sprout were examined. In addition, microbial growth during the shelf life of sprout grown, using conventional and KHS methods were monitored. Moreover, the efficacy of chlorine-based sanitizers for reducing microbial loads during KHS sprout production was tested. Results showed that air flow rate had a positive impact on yield. However, higher airflow (8 and 10 feet3/minute) significantly lowered yield. Also, KHS has a significant higher yield compare with conventional method (110.30±4.88 versus 66.19±2.66 g). KHS did not have positive impact on germination percentage. Germination percentage was almost the same in KHS and conventional method (80.67±1.15% versus 81.33±1.53%). Moreover, when various light wavelengths were used, germination percentage increased significantly in KHS (from 91±2.65 to 96±1% in various wavelengths). In terms of color, there were no significant differences in color of sprouts in both systems. In KHS, when dark conditions applied, stem length was significantly higher (31.32±3.55 mm) than those sprouts treated with light. For example, stem length in white light was 8.54±1.32 mm. In contrast, leaves length was significantly higher when light used (highest was 6.67±0.49 mm for combination of blue and red lights compare to 3.19±0.22 mm for dark KHS). Analyzing microbial background showed that sprouts produced in KHS had lower total aerobic counts compared with conventional system (7.24±0.49 versus 8.22±0.18 log CFU/g respectively). However, after 21 days of shelf study at 4°C sprouts in both systems almost had the same counts (10.02±0.70 versus 9.55±0.49 log CFU/g in KHS and conventional systems respectively).
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Title: DOPING OF SODIUM CHROMIUM OXIDE CATHODE MATERIALS TO ENHANCE ELECTROCHEMICAL PERFORMANCE FOR SODIUM-ION BATTERIES
Creator: wang, ziyong
Date: 2019
Description: In this project, we investigated the effects of doping several types of metals to NaCrO2 on its electrochemical performance. The doping method...
Show moreIn this project, we investigated the effects of doping several types of metals to NaCrO2 on its electrochemical performance. The doping method is aiming to stabilize the O3-type structure by partial substituting some of Cr with other metals during intercalation/deintercalation by suppressing Cr6+ migration to alkaline slab, and thus facilitate long-term cycle performance and reversible capacity. All doped NaCrO2 powders were hereby denoted to NaMe0.1Cr0.9O2 (Me=Al, Co, Ni, Mn). To achieve metal-doped NaCrO2 powders, sodium, chromium and dopant sources were mixed with various metal oxides and then subjected to 6-hour high energy ball milling, followed by heating in flow-Ar tube at 900℃ for 1 hour. Pristine NaCrO2 powder synthesized in the same process was to make comparisons with doped ones. To understand the mechanism of doping, field emission scanning microscopy (FESM) and energy Disperse Spectroscopy (EDS), as well as X-ray diffractometer (XRD), were employed to analyze the morphology and composition of final products. Benefiting from Ni doping, NaNi0.1Cr0.9O2 cell exhibited a high reversible capacity of 132 mAh g-1 at the initial cycle in a potential region between 2.0 and 3.6 V vs. Na/Na+, and 78 % of capacity retention over 70 cycles. For NaMn0.1Cr0.9O2, reversible capacity at first discharge is about 30 mAh g-1, lower than that of Ni-doped and pristine NaCrO2, while the cycle retention stays at nearly 100% after 100 cycles. The opposite charge/discharge behaviors from Ni- and Mn-doped NaCrO2 provide us a potential method for the optimization of cathode materials with the best electrochemical performance in the future.
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Title: Rapidly Deployable PV-Based Smart Irrigation System
Creator: Usta, Salih
Date: 2019
Description: There are many agricultural fields in developing countries such as Turkey which do not have electricity on site. In order to water these...
Show moreThere are many agricultural fields in developing countries such as Turkey which do not have electricity on site. In order to water these fields, there is usually a need to store water in a water reservoir nearby. This purpose is achieved by manpower or by using diesel-operated water pumps which are often inefficient and require a high degree of maintenance over time. Furthermore, extending the power supply grid to the field is not considered an option by governors, due to the high cost for a relatively small-scale application. Along with this, watering the field is done by farmers, which frequently leads to waste of water, or leads to watering one particular area of the field less than the others, which causes a drop in crop efficiency. Preventing water waste is considered an important issue in the 21st century. Also, increasing crop efficiency in a developing country is an important consideration. To prevent water waste and to enhance crop efficiency, an automated irrigation system is needed. The objective of this study is to develop a photovoltaic-based irrigation system for an agricultural field that is not tied to an existing conventional electric grid. Firstly, a stand-alone PV system is designed according to the field requirements. Secondly, a soil moisture sensor-based smart irrigation system is developed for an automated irrigation process compatible with drip irrigation systems. This system also enables users to monitor and analyze soil moisture data. By developing this type of complete irrigation mechanism, a long-term lower cost, efficient, and environmental-friendly system is designed.
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Title: Mental Health Stigma and Care-Seeking in First Generation Indian Immigrants
Creator: Shah, Binoy
Date: 2019
Description: Objective: Immigrants from India face unique obstacles, including migration related factors and cultural pressures, that may contribute to...
Show moreObjective: Immigrants from India face unique obstacles, including migration related factors and cultural pressures, that may contribute to underutilization of mental health treatment services. The present thesis examined paths between mental health stigma and care-seeking in a sample of first-generation Indian immigrants, with a specific emphasis on the influences of acculturation and parental autonomy support. Method: A sample of 201 first-generation immigrants from India was ascertained using MTurk. Path analysis was conducted to examine the relationships between public stigma of mental illness, disclosure, mental health care-seeking, parental autonomy support, and bi-directional acculturation. Results: Final model was supported by good fit indicators. Greater public stigma was associated with reduced care-seeking, but greater disclosure was associated with increased care-seeking. Interestingly, parental autonomy support, mainstream acculturation, and heritage acculturation facilitated disclosure but had no discernible impact on public stigma. Conclusions: In contrast to traditional anti-stigma strategies that focus on reducing public stigma, present results suggest that it may be more beneficial to facilitate care-seeking by targeting disclosure of status. In turn, disclosure may be promoted by facilitating autonomy supportive social networks and bi-directional acculturation.
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Title: EVALUATION OF LISTERIA MONOCYTOGENES ENRICHMENT AND COMPOSITING PROTOCOLS FROM ENVIRONMENTAL SAMPLES
Creator: Eckert, Christine
Date: 2019
Description: Environmental sampling in a food production plant is routinely conducted using devices, such as sponges or swabs, to verify cleaning...
Show moreEnvironmental sampling in a food production plant is routinely conducted using devices, such as sponges or swabs, to verify cleaning procedures and determine if any foodborne pathogens, such as Listeria monocytogenes (L. monocytogenes), are present. The devices used for environmental monitoring are enriched to improve pathogen detection. This study aims to 1) compare the limit of detection (LOD) of L. monocytogenes of two U.S. Food and Drug Administration (FDA) enrichment procedures (i.e., Bacteriological Analytical Manual (BAM) and Compliance Document) with and without food matrix, and to 2) assess the number of samples which can be wet and dry composited without loss of sensitivity from stainless steel. To compare the LOD of L. monocytogenes using UVM and BLEB, three inoculation levels (0.27±0.07, 0.59±0.05, and 1.00±0.15 CFU per 225 mL enrichment) with 30 enrichments each were used. Results showed that there was no significant difference between the number of samples where L. monocytogenes was detected for UVM and BLEB at any of the three inoculation levels. However, the limit of detection (LOD95%) for UVM/Fraser was higher than that of BLEB (2.13 and 1.44 CFU/mL, respectively). For wet compositing, 1.24±0.34 CFU of L. monocytogenes was inoculated into 45 enrichments of UVM or BLEB without food matrix and 7.2±0.18 CFU of L. monocytogenes was inoculated into 30 enrichments of UVM or BLEB with 4.13±0.12 log CFU of native microflora from Romaine lettuce wash (RLW). Secondary composite enrichments in Fraser broth were conducted at each of four different ratios: 1:1 (1 positive:1 negative), 1:2 (1 positive: 2 negative), 1:4 (1 positive: 4 negative), and 1:7 (1 positive:7 negative). There was no significant difference between the number of samples where L. monocytogenes was detected between BLEB and UVM with or without food matrix at any of the composite ratios. When comparing wet and dry compositing enrichments from stainless steel, 10.16 × 10.16 cm areas on stainless steel plates were inoculated with 464±22 CFU (2.67±0.24 log CFU) L. monocytogenes, dried for 24 h, and sponges were used to swab the surface of the plates. The sponges were then composited (into primary enrichments for dry compositing) or the secondary enrichments were composited (for wet compositing). Compositing was conducted with RLW containing 4.13±0.02 log CFU of background microflora. There was no significant difference between the number of samples where L. monocytogenes was detected for BLEB and UVM when comparing dry or wet compositing at any of the composite ratios tested. Results of this thesis will aid in determining if compositing of environmental samples is an option when L. monocytogenes is the target pathogen.
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Title: Wireless Body Sensor Network for Tracking Human Mobility using Long Short-Term Memory Neural Network for Classification
Creator: Gupta, Saumya
Date: 2019
Description: A large number of sensors are used without justification of the number chosen or placement choice. Many papers about body sensor networks...
Show moreA large number of sensors are used without justification of the number chosen or placement choice. Many papers about body sensor networks explore how to capture a type or types of motion, but all their sensors are placed in different locations; making their algorithms very specific to that movement. In this research, we explore the enhancement of human activity classification algorithm using long short-term memory (LSTM) neural network and wearable sensor network. There are five identical nodes used in the body sensor network to collect data. Each node incorporates an ESP8266 Microcontroller with Wi-Fi which is connected to an inertial measurement unit consisting of triple axis accelerometer and gyroscope sensor board. An analysis on the accuracy that each sensor node provides separately and in different combinations has been conducted to allow future research to focus their positioning in optimal positions. A Robot Operating System (ROS) central node is used to illustrate the in-built multi-threading capability. For demonstration, the positions chosen are waist, ankles and wrists. The raw sensor data can be observed on screen while it is being labelled live to create fitting dataset for developing an artificial neural network. Expectation is that increasing the number of sensors should raise the overall accuracy of the output but that isn’t the case observed, positioning of the sensor is pertinent to improvement. These platforms can be further extended to understand different motions and different sensor positions, also expanded to include other sensors.
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Title: CULTURALLY SENSITIVE HELP-SEEKING AMONG ASIAN INTERNATIONAL AND ASIAN AMERICAN COLLEGE STUDENTS
Creator: Tsen, Jonathan Yee-jon
Date: 2020
Description: Asian populations are rapidly rising, representing the fastest growing racial group of immigrants in the U.S. with many seeking higher...
Show moreAsian populations are rapidly rising, representing the fastest growing racial group of immigrants in the U.S. with many seeking higher education. While many face risk for poor mental health outcomes and high suicidal ideation, Asian college students report lower rates seeking mental health services than White Americans. The purpose of this study was to test a culturally sensitive help-seeking model for Asian international and Asian American college students, and to capture relevant psychological and cultural factors that influence help-seeking. This study used an observational design to build on the current research and evaluated the effects of acculturation, enculturation, public stigma of help-seeking, self-stigma of help-seeking, and attitudes on willingness to seek psychological services. Four hundred and fifty-eight students (Age M = 23.93, SD = 4.36) represented by 265 Asian International Students and 193 Asian American Students. Using a path analysis, results demonstrated a poorly fitted model, suggesting that acculturation, enculturation, public stigma, self-stigma, attitudes, and willingness do not relate significantly to each other when viewed altogether in a model. This remained true even when modifications to the model were made, and when observing the model within only Asian American student sample or Asian international student sample. However, significant direct effects were observed between enculturation and public stigma in the total sample, as well as separately in Asian American or Asian international samples. These findings highlight the importance of exploring with different methodological approaches to gain insight on other important psychological and cultural factors that impact help-seeking among Asian international and Asian American college students.
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Title: MULTIYEAR AUTOMATED ANALYSIS OF AURORAL IMAGES TO CATEGORIZE IONOSPHERE IRREGULARITY LAYER
Creator: Stuart, David Jacques
Date: 2020
Description: This thesis presents a method of automated analysis of auroral all-sky images (ASIs) to determine the ionospheric layer of plasma...
Show moreThis thesis presents a method of automated analysis of auroral all-sky images (ASIs) to determine the ionospheric layer of plasma irregularities. These irregularities can perturb radio signals in an effect called scintillation, degrading and at worst preventing signal reception. One key question about scintillation-causing irregularities is whether they occur in the E or F layer of the ionosphere, whose dynamics differ.Previous studies have shown Global Positioning System (GPS) scintillation to be correlated with aurorae. The Scintillation Auroral GPS Array (SAGA) at Poker Flat Research Range, Alaska, was used to detect thousands of GPS L1 and L2C scintillation events over 2014-2015. Collocated auroral images of emissions are recorded nightly by both a keogram spectrograph (measuring intensity along a single longitude vs time) and an ASI filtered at 630.0 nm (red), 557.7 nm (green), and 427.8 nm (blue) wavelengths.In this work scattering layers are hypothesized based on optical measurements, through automated filtering of keograms followed by spectral analysis of aurorae, which tend to occur with these irregularities. A cloud detection method using the North-South keogram is implemented, where a time-averaged, intensity-corrected characteristic snapshot of cloudy times was built as a baseline response, and used as the gain in a flat field correction-like step to normalize the cloudy sky appearance. The coefficient of variation Cv is used as the test statistic to determine cloudy times. Cloud-free ASIs have the location of scintillating PRNs identified, and the ratio of red oxygen 630 nm to blue nitrogen 428 nm emissions in that direction. With an auroral model of characteristic energy, ratios above 0.5 are categorized E-Layer and ratios below F-Layer.Multiyear ASI irregularity layer determinations are used to categorize 364 of the initial 4174 SAGA scintillation events. A 77% majority of the events are hypothesized to be F-Layer based on ASI spectral classification. This disagrees with prior PFISR categorizations, which found scintillation events to be majority E-layer. This presents an outstanding question as to the possible reasons for the difference.
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Title: AN ACCELERATING COUETTE FLOW IN NEK5000: APPLICATIONS IN OCEANOGRAPHY AND MAGNETOHYDRODYNAMICS
Creator: Miksis, Zachary M.
Date: 2017, 2017-05
Description: Nek5000 is a highly scalable spectral element code used in a broad array of problems in computational fluid dynamics. In this thesis, we focus...
Show moreNek5000 is a highly scalable spectral element code used in a broad array of problems in computational fluid dynamics. In this thesis, we focus on applying the code to a model problem of an accelerating Couette flow, or a hydrodynamic flow between two plates, of which the top plate is accelerating and the bottom plate is stationary, and verifying the numerical methods as applied to this problem. We obtain an analytical solution to the hydrodynamic flow problem, and use this to analyze the effects of changing time step length, the size of the computational mesh, and the computational polynomial order on the accuracy and stability of Nek5000. Additionally, we discuss the addition of an applied magnetic field to the hydrodynamic Couette flow, and provide a formulation for an exact solution to this magnetohydrodynamic problem that can be used to further verify Nek5000 in a similar fashion to the hydrodynamic problem.
M.S. In Applied Mathematics, May 2017
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Title: INFORMATION QUALITY: RESTRUCTURING THE MODERN ACADEMIC LIBRARY FOR RESEARCH ACCURACY
Creator: JURKOWSKI, ODIN L.
Date: 1997-05
Description: Information overload causes problems in accessing information and is becoming more prevalent as technology allows us to store greater amounts...
Show moreInformation overload causes problems in accessing information and is becoming more prevalent as technology allows us to store greater amounts of information, and as researchers produce ever more specialized knowledge. This thesis will begin with a discussion of this overload followed by an examination of statistics gathered at Illinois Institute of Technology (which support the trend of increased interlibrary loan transactions and the rise in information availability). Following a review of the literature in library and information science, psychology, and linguistics, this thesis will discuss some of the solutions to this problem. First, access may be improved by transforming the storage of information from traditional print resources to electronic. Considering the restrictions of the present vendor supplied print resources, the limitations due to present copyright law, and cost comparisons between print and electronic subscriptions, we find a distinct advantage to future electronic access. This access can be improved through the use of electronic journals, full-text/image databases, and virtual libraries. Second, the searching capabilities of information systems can be improved in order to narrow information into more accurate search results. This can be done by advanced indexing, adding value, relevance and ranking, citation analysis to direct the patron towards improved search results, and by taking advantage of hypertext capabilities in order to ease navigation through information systems.
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Title: SELECTING AN EFFECTIVE DELIVERY METHOD FOR MULTIMEDIA-BASED DISTANCE EDUCATION
Creator: BURIAN, ARNOLD
Date: 1998-05

Title: THE EFFECT OF MOOD INDUCTION ON ADOLESCENT SPEECH BEHAVIOR
Creator: LAWRENCE, HALCYON
Date: 2010-12
Description: An experiment was conducted to determine if a sad mood induction procedure using music and self-imagery would produce sad speech in...
Show moreAn experiment was conducted to determine if a sad mood induction procedure using music and self-imagery would produce sad speech in adolescents. The participants were asked to rate their perceived positive and negative affect and they were recorded. reading speech materials. Results indicate that although participants perceived a change in mood from neutral to sad, none of the baseline acoustic correlates of sad speech were identified in their recordings. These results suggest that either participants were not induced into a sad mood by this procedure or that the method of self-reporting is an inadequate assessment for this age group, signaling that more effective ways to measure mood for adolescents should be investigated. Additionally, since most studies on sad speech use actors, the results may indicate that acted speech provides significantly different correlates from emotionally-induced speech. Finally, a similarly valenced mood may have been induced instead of sadness (e.g. "calmness") which possesses different acoustic correlates from sad speech. Whilst the findings suggest that there is need for further research on these issues, this experiment demonstrates that mood inducement procedures (MIPs), primarily used in the field of psychology, can be applied in other domains. For example, MIPs conducted in online environments could provide useful insights into how mood affects users' online behaviors.
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Title: RUNTIME FOR PERFORMING EXACT TESTS ON THE PI STATISTICAL MODEL FOR RANDOM GRAPHS
Creator: Dillon, Martin
Date: 2016, 2016-05
Description: In statistics, we ask whether some statistical model ts observed data. We use a Markov chain proposed by Gross, Petrovi c, and Stasi to...
Show moreIn statistics, we ask whether some statistical model ts observed data. We use a Markov chain proposed by Gross, Petrovi c, and Stasi to perform exact testing for the p1 random graph model. By comparing it to the simple switch Markov chain, we prove that it mixes rapidly on many classes of degree sequences, and we discuss why it is sometimes better suited than the simple switch chain, and try to easily introduce the concepts from the general theory along the way.
M.S. in Applied Mathematics, May 2016
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Title: Fate of Listeria Monocytogenes on Hard-cooked Eggs Treated With Citric Acid
Creator: Zeng, Hui
Date: 2021
Description: Commercially-prepared hard-cooked eggs are available for foodservice and to the public in retail grocers. Potential contamination with...
Show moreCommercially-prepared hard-cooked eggs are available for foodservice and to the public in retail grocers. Potential contamination with Listeria monocytogenes during or after the cooking and peeling steps is of concern since this pathogen can proliferate at refrigeration temperatures. Citric acid is a common preservative used in the food industry to treat hard-boiled eggs (HBEs). The purpose of this project was to evaluate the efficacy of citric acid treatment of HBEs to reduce the population levels of L. monocytogenes during 24 h (treatment trials) and 28 d storage (storage trials) at 5 or 25°C. Fresh eggs were boiled for 12 min, cooled to 4°C, peeled, and stored at 5°C for 24 h prior to experiments. In treatment trials, HBEs were dip inoculated with a 4-strain cocktail of rifampicin-resistant L. monocytogenes resulting in either 4 (low) or 7 (high) log CFU/egg. Eggs were air-dried 10 min, followed by treatment with pH 2.5 citric acid (PHCA) or 0.2 M citric acid (calculated as the molarity resulting in pH 2.5: MCA) at 5 or 25°C for 24 h. In treatment-storage trials, citric acid treatment of HBEs occurred before or after inoculation, followed by 28-d storage at 5 or 25°C. L. monocytogenes populations were enumerated by homogenization of eggs with BLEB and cultivation on BHI/rifampicin agar. Enrichment in BLEB was conducted if the pathogen was below the level of enumeration. Significant differences in the populations of L. monocytogenes due to temperature of the acid treatment (5 or 25°C) or the two citric acids (MCA and PHCA) were determined using Student’s T-test and ANOVA with Tukey’s post-test, p ≤ 0.05. Overall, the largest L. monocytogenes reduction occurred after 6 h treatment of HBEs with PHCA at 25°C (1.59 ± 0.00 log CFU/egg) and after 24 h with MCA at 5°C (1.23 ± 0.54 log CFU/egg) when the pathogen was inoculated at the low and high levels, respectively. In treatment-storage trials, citric acid treatment after HBE contamination resulted in a fewer number of samples where the pathogen was detected compared to when treatment occurred before contamination. Citric acid treatment for 24 h also resulted in a greater number of samples where L. monocytogenes was not detected than the 1 h treatment. The results of this study determined that L. monocytogenes could survive on HBEs treated with citric acid, regardless of treatment or storage temperature and acid concentration (PHCA or MCA).
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Title: Using population-level data to examine between-group health differences among transgender and cisgender United States military veterans
Creator: Woodward, Honor
Date: 2021
Description: Some subgroups of military veterans, including those with marginalized identities, may be especially vulnerable to poor health. This...
Show moreSome subgroups of military veterans, including those with marginalized identities, may be especially vulnerable to poor health. This hypothesis is supported by the Minority Stress Theory framework, which posits that disparities in health can be attributed to the stress that minority individuals experience as a result of discrimination, prejudice, and oppression (Meyer, 1995; Meyer, 2003). A specific, potentially marginalized group of veterans that is under-explored regarding health is transgender veterans. Using data from the 2019 U.S. Behavioral Risk Factor Surveillance System (BRFSS), the current study hypothesized that transgender U.S. military veterans will report worse health than cisgender U.S. military veterans. Using case control matching, groups of transgender veterans (n = 124) and cisgender veterans (n = 104) were compared on several population-relevant health outcome measures. Chi-square tests of independence were conducted to test for significant differences between transgender and cisgender military veterans on the likelihood of experiencing certain health conditions, engaging in certain health behaviors, and utilizing health care services. Independent samples t-tests were used to test continuous health outcomes, such as self-reported mental health, physical health, and access to health care services. Gender identity was significantly associated with only one health outcome variable, with transgender veterans being more likely than cisgender veterans to have received a formal depression diagnosis (p = .01, phi = .17). No significant differences emerged between transgender and cisgender veterans on continuous health outcome variables. This suggests that previous literature on health disparities between transgender and cisgender individuals may not be generalizable to transgender veterans.
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Title: Frictional behavior of bronze-graphite composite as sliding element in the base isolation system
Creator: You, Da
Date: 2021
Description: There are many calamities around the world, one of the most dangerous disasters is earthquake which threatens the safety of people and the...
Show moreThere are many calamities around the world, one of the most dangerous disasters is earthquake which threatens the safety of people and the structures. Almost every year, there are a lot of property losses and casualties caused by earthquakes. To mitigate the bad effect of the earthquake, the base isolation system was proposed by previous researchers. With the contribution of many researchers, several seismic isolations have been developed. Until now, many structures have installed seismic isolations to resist seismic energy and vibration. The seismic isolation system works well during the earthquake period, and it does help reduce the casualty and property loss induced by earthquakes. There are two main types of bearings used in the seismic isolation system. One is the elastomeric bearings and the other is the sliding bearings. The mechanics of the seismic isolation system preventing the influence of the earthquake and reducing the horizontal acceleration of the structure is to elongate the natural frequency of structure. As for the sliding bearings, the simplest way to increase the period is to reduce the friction coefficient of the two sliding elements. In conventional, two stainless steel plates are commonly used in the pure flat sliding bearing. This study tries to use bronze-graphite composite in the sliding bearing to decrease the friction coefficient.Consequently, the testing results suggest that the bronze-graphite composite has a lower friction coefficient, especially the graphite acting as a lubricant. The friction coefficient of the bronze-graphite plate is in the range of 0.12 to 0.23 under the load of 160 kg - 800kg. With a higher ratio of graphite to bronze at the sliding surface, the effect of reducing the friction coefficient more obviously. And the friction coefficient changes during the increasing loads period. It decreases at the beginning, and starts to increase at a certain load applied on it. Finally, it is reasonable to bronze-graphite composite in a low rise structure which has a relatively low weight. Because the load applied in the test is not high enough, the consequence may not work for high or heavy structure. Taken together, the use of new material with similar properties in the seismic isolation system can help improve the performance of resisting the earthquake. It should be accounted for further research in this field.
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Title: HIGH-THROUGHPUT FIRST-PRINCIPLES STUDY ON HIGH-ENTROPY ALLOYS
Creator: Zhang, Jie
Date: 2021
Description: This research thesis discusses the current ecosystem surrounding a new type of alloy: high entropy alloys (HEA) or multi-element crystalline...
Show moreThis research thesis discusses the current ecosystem surrounding a new type of alloy: high entropy alloys (HEA) or multi-element crystalline materials and lays out the high-throughput first-principles calculation as a valuable approach to study these materials. The density function theory (DFT) from computational material science prospect was implemented to investigate the HEAs. Using EMTO-CPA algorithm, high-throughput DFT calculations were conducted. A total of 1958 HEA systems including equimolar and non-equimolar systems were studied with respect to the varies properties, including lattice parameters, bulk moduli, elastic constants, and elastic anisotropy. The first-principles HEA dataset was employed as the training set for the DeepSets a machine learning model. DeepSets, in combination with EMTO-CPA high-throughput calculation, successfully predicted the mechanical properties of specific HEA composition. This paves a promising new path of designing, investigating, and validating the HEA system compared to the time-consuming conventional HEA design method. The doping effect of Vanadium (V) and Titanium (Ti) to NbMoTaW HEA, as well as V or Ti as the fifth element with different molar fraction to the NbMoTaW HEA system, were studied. The phase stability of the new systems was discussed and concluded that all proposed systems tend to form single-phase solid solution. Though the addiction of V only slightly enhances the system’s ductility, the addition of Ti not only enhances the quinary system NbMoTaWTiX (X =0.25, 0.5,0.75, 1.0) ductility, but enables the system to be closer to fully isotropic.
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Title: Sex Differences in a Network Model of Depressive Symptoms
Creator: Ginger, Emily J
Date: 2021
Description: Major Depressive Disorder (MDD) is one of the most prevalent mental health disorders, with a lifetime prevalence rate of 13-16% and 12-month...
Show moreMajor Depressive Disorder (MDD) is one of the most prevalent mental health disorders, with a lifetime prevalence rate of 13-16% and 12-month prevalence rates of 5-7%. It has long been established that the rates of MDD in females is two to three times that of males. Previous research has examined sex differences in the occurrence and severity of MDD symptoms, primarily indicating greater severity of appetite increase and weight gain in females compared to males. The majority of previous research has been conducted assuming the latent factor model that MDD accounts for the symptoms of depression, and sex operates as a mediator or moderator between the latent variable and MDD, or between MDD and its symptoms. The present study used network analysis to examine whether there are sex differences in the relations between symptoms of depression, which might be an important factor for understanding sex differences in prevalence rates of MDD. The present study compared networks of DSM MDD symptoms between currently depressed females and males, and separate networks that also included other symptoms commonly associated with depression (e.g., anxiety, anger). Sex differences were examined using jointly estimated networks, and a Network Comparison Test (NCT) for the independently estimated networks. Results indicated no sex differences in depression symptom networks. These results indicate that depressive symptom networks, or the relations between symptoms are not an important factor for understanding the disparity in sex differences in MDD prevalence rates. Interestingly, non-DSM symptoms were among the strongest and most important symptoms within the network, suggesting future research and diagnostic criteria should consider inclusion of non-DSM symptoms associated with MDD.
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Title: Child Temperament, Attachment, and Loneliness: The Mediating Effects of Social Competence
Creator: Evans, Lindsey M
Date: 2021
Description: Chronic loneliness is a risk factor associated with adverse psychological, physical, and academic outcomes. Converging evidence suggests that...
Show moreChronic loneliness is a risk factor associated with adverse psychological, physical, and academic outcomes. Converging evidence suggests that young children experience and can reliably report on their own loneliness. Due to the significant negative sequalae associated with childhood loneliness, it is critically important to examine risk factors for child loneliness. The aims of this study were two-fold: (a) to examine if temperament (i.e., negative affect, effortful control, and inhibitory control) and attachment security assessed at 4 years of age predict loneliness at age 6; and (b) to determine if social competence at age 5 mediates the relation between temperament and attachment security at age 4 and loneliness at age 6. Participants included a diverse sample of 796 4-year old children, about half of whom were male. At age 4, temperament was assessed with the Rothbart Child Behavior Questionnaire and three inhibitory control tasks, and attachment security was assessed with the Attachment Q-Sort. At age 5, the Social Skills Rating Scale was used to assess social competence, and, at age 6, loneliness was assessed with the Loneliness and Social Dissatisfaction Questionnaire. Results of hierarchical regression analyses indicated that lower levels of effortful control and inhibitory control at age 4 significantly predicted higher levels of loneliness at age 6. Also, lower levels of negative affect and higher levels of effortful control and attachment security at age 4 significantly predicted higher levels of social competence at age 5. However, social competence at age 5 did not predict loneliness at age 6. There was no evidence that social competence at age 5 mediated the relation between age 4 temperament, attachment security and age 6 loneliness. These findings reveal that early self-regulation is associated with later child-reported loneliness and that intervention for children who struggle with cognitive regulation may be effective in decreasing risk for later loneliness.
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Title: Inviscid Shock Propagation within a Variable-Geometry Scramjet Inlet
Creator: Grybko, Maciej
Date: 2021
Description: The study concerns the propagation of shockwaves within an inlet of a scramjet engine and effect of inlet geometry variation on performance. A...
Show moreThe study concerns the propagation of shockwaves within an inlet of a scramjet engine and effect of inlet geometry variation on performance. A Python code was developed to simulate and visualize a flowfield within a scramjet inlet, based on inviscid oblique shock theory. The program was validated against NASA Shock software, and the results differed only by round-off error (0.05%). Subsequently a geometric sensitivity study was conducted, showing that throughout acceleration from Mach 5 to Mach 20 parameters like inlet height could be varied to ensure constant number of shocks within an inlet (preventing discontinuous changes of flowfield), whereas lower wedge angle could control compression required for optimal combustion. Correspondingly, a trajectory was determined with a constraint on static pressure entering combustion chamber (100 kPa). For an arbitrary baseline inlet geometry, it was established that beyond Mach 10 the scramjet would exceed structural load limit, despite delivering sufficient conditions for rapid combustion. Nevertheless, below Mach 10 it would operate efficiently, proving that hydrocarbon-fueled scramjets can have a fixed geometry. For higher speeds, a variable geometry is a necessity.
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