697 research outputs found
On orthogonal coding-based modulation
No full textIn this letter, we propose a new orthogonal coding-based modulation (OCBM) scheme, in which all available transmitting subcarriers and antennas are activated at a time instant to transmit the data constellation symbols, and the indices of the activated subcarriers and antennas are also harnessed to carry information bits. Our OCBM especially addresses a novel scheme in spatial modulation (SM) domain via employing virtual subarray, and improves the spectral efficiency compared with the existing orthogonal frequency division multiplexing (OFDM)-spread spectrum (SS), index modulation (IM)-OFDM-SS and IM-OFDM based SM (the number of transmit antennas is more than 2). In addition, our investigated detection scheme of the OCBM reduces the complexity of the receiver design by using the unique behavior of the orthogonal code, especially for the detection of the transmitted antenna index bits. Our simulated experiments have been carried out to test the performance of the proposed scheme, and demonstrate the benefits of our suggested approach
Altering tensile and crack initiation behavior in a metastable β titanium alloy via designing grain size and precipitates
No full textDoppler shift estimation for space-based AIS signals over satellite-to-ship links
No full textAs a communication system for maritime monitoring and navigation, automatic identification system (AIS) has been employed for many years, but its service range is limited in 40 nautical miles. Fortunately, an updated service navigation system named as space-based AIS has been presented in recent years, which can provide global coverage service. However, it encounters frequency offset issue caused by the relative satellites/ships motion. To cope with it, in this paper, a novel Doppler shift estimation algorithm is proposed for space-based AIS signals over satellite-to-ship wireless fading channels and non-Gaussian noise. In the estimation stage, the signals including the Doppler shift information are firstly separated from the received ones, but they are also disturbed by the noise. Then, Doppler shift is extracted from the above detached signals via the higher moments which cancel some excrescent parameters by using several flexible algebra operations, and its estimated expression is presented. Finally, numerical simulations are carried out to verify the performance of the proposed method, and simulation results demonstrate the benefits of the suggested scheme
High resolution millimeter wave imaging for self-driving cars
No full textRecent years have witnessed much interest in expanding the use of networking signals beyond communication to sensing, localization, robotics, and autonomous systems. This thesis explores how we can leverage recent advances in 5G millimeter wave (mmWave) technology for imaging in self-driving cars. Specifically, the use of mmWave in 5G has led to the creation of compact phased arrays with hundreds of antenna elements that can be electronically steered. Such phased arrays can expand the use of mmWave beyond vehicular communications and simple ranging sensors to a full-fledged imaging system that enables self-driving cars to see through fog, smog, snow, etc.
Unfortunately, using mmWave signals for imaging in self-driving cars is challenging due to the very low resolution, the presence of fake artifacts resulting from multipath reflections and the absence of portions of the car due to specularity. This thesis presents HawkEye, a system that can enable high resolution mmWave imaging in self-driving cars. HawkEye addresses the above challenges by leveraging recent advances in deep learning known as Generative Adversarial Networks (GANs). HawkEye introduces a GAN architecture that is customized to mmWave imaging and builds a system that can significantly enhance the quality of mmWave images for self-driving cars.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2021-12-01The student, Junfeng Guan, accepted the attached license on 2019-12-09 at 12:07.The student, Junfeng Guan, submitted this Thesis for approval on 2019-12-09 at 12:16.This Thesis was approved for publication on 2019-12-09 at 15:49.DSpace SAF Submission Ingestion Package generated from Vireo submission #14758 on 2020-02-28 at 17:23:56Made available in DSpace on 2020-03-02T22:15:15Z (GMT). No. of bitstreams: 2
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Previous issue date: 2019-12-09Embargo set by: Seth Robbins for item 113927
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The Health Impact of Indoor Air Filtration in Healthy Adults and Asthmatic Children
No full textThe World Health Organization (WHO) estimated that 92% of the world’s population lived in areas with outdoor air pollution levels exceeding the WHO guidelines in 2014. Although the ultimate solution is to control emission sources, exposure reduction strategies at the individual level can address more immediate needs. As people typically spend approximately 80% of their time indoors, improvement of indoor air quality, such as using air filtration technologies, may lead to reduced total exposure. However, evidence is limited to support the effectiveness of air filtration in bringing beneficial health effects to the users. The goal of this dissertation research is to evaluate the health impact of indoor air filtration in healthy adults and asthmatic children using two randomized, double-blind, crossover trials (Aim 1 and Aim 2). Utilizing data from these two trials and other data, this dissertation also addresses two methodological questions. Aim 3 examines the relationship between free and total malondialdehyde, a biomarker of oxidative stress commonly used in air pollution research, in various types of human specimens. Aim 4 evaluates the relationship between the subjective evaluation of asthma control by childhood asthma control test (C-ACT) and objective indicators of lung pathophysiology using longitudinal measurements.In Aim 1 of this dissertation, a double-blinded, randomized, crossover study was conducted to examine the cardiorespiratory health effect of a sporadic, overnight use of indoor air filtration. Seventy healthy non-smoking adults were recruited from the medical and nursing students who were living in the same dormitory building in a suburb of Shanghai, China. The participants were aged 19 to 26 years old and included 41 (59%) females. Each participant received a true and a sham indoor air filtration session in a randomized sequence. Participants and research staff that performed health assessments were blinded to this sequence until the end of the study. Each filtration session was approximately 13 hours long. True and sham filtration sessions were separated by a two-week “washout” interval. During the study period, outdoor PM2.5 concentrations ranged from 18.6 to 106.9 µg/m3, which overlapped with levels measured in Western Europe and North America. Compared to sham filtration, true filtration on average decreased indoor PM2.5 concentration by 72.4% to 10.0 µg/m3 and particle number concentration by 59.2% to 2316/cm3. For lung function measured immediately after the end of filtration, true filtration significantly lowered airway impedance at 5 Hz (Z5) by 7.1% [95% CI: 2.4%, 11.9%], airway resistance at 5 Hz (R5) by 7.4% [95% CI: 2.4%, 12.5%], and small airway resistance (R5-R20) by 20.3% [95% CI: 0.1%, 40.5%], reflecting improved airway mechanics especially for the small airways. However, no significant improvements for spirometric indicators of lung function (FEV1, FVC) were observed. True filtration also significantly lowered von Willebrand factor (VWF) by 26.9% [95% CI: 7.3%, 46.4%] 24 hours after the end of filtration, indicating reduced risk for thrombosis. Stratified analysis in male and female participants showed that true filtration significantly decreased pulse pressure by 3.3% [95% CI: 0.8%, 7.4%] in females, and significantly reduced VWF by 42.4% [95% CI: 17.4%, 67.4%] and interleukin-6 by 22.6% [95% CI: 0.4%, 44.9%] in males. Effect modification analyses indicated that filtration effects in male and female participants were not significantly different. These findings suggest that a single overnight residential air filtration, capable of reducing indoor particle concentrations substantially, can lead to improved airway mechanics and reduced thrombosis risk.Air pollution exposure is a well-established risk factor for asthma exacerbation. In individuals with asthma, indoor air filtration has only been evaluated for allergen removal in areas with low outdoor levels of PM2.5. As asthmatic individuals may be responsive to short-term changes in air pollution levels, it is not clear whether the exposures occurring outside the home environment can override the potential health benefits of residential indoor air filtration. In Aim 2 of this dissertation, I investigated the respiratory impact of residential indoor air filtration in asthmatic children living with moderate levels of outdoor PM2.5. This double-blind, randomized crossover trial recruited 43 participants (40% females) aged 5 to 13 with mild or moderate asthma. From February to April 2017, each participant used a true filtration device and a sham filtration device, respectively in their bedrooms for two weeks. A two-week washout period separated the two sessions. During the study, the average PM2.5 concentrations for outdoor, indoor with sham filtration, and indoor with true filtration were 56.5 µg/m3, 34.1µg/m3, and 14.8 µg/m3, respectively. Compared to sham filtration, on average, true filtration reduced indoor PM2.5 concentrations by 53.3%. Concomitantly, true filtration significantly decreased fractional exhaled oxide (FeNO) by 5.1 [95% CI: 0.5, 9.6] ppb, airway impedance at 5Hz (Z5) by 14.7% [3.7%, 25.8%], respiratory resistance at 5Hz (R5) by 22.4% [9.6%, 35.2%], and small airway resistance (R5-R20) by 40.6% [10.2,% 70.9%]. Peak expiratory flow (PEF) measurements were made twice daily throughout each two-week intervention session. PEF values during true filtration were 1.5% [0.7%, 2.4%] higher than the measurements during sham filtration. True filtration also introduced a non-significant increase on FEF25-75 by 5.80% [-4.09%, 15.68%]. Stratified analyses show that the participants with blood eosinophil count ≤ 500/mm3, compared to those with blood eosinophil count > 500/mm3, had a 24.3% greater increase of FEF25-75 by true filtration; and that the participants allergic to dust mite had smaller improvements in small airway resistance (R5 and R5-R20). These findings suggest that a two-week long intervention of indoor air filtration, capable of significantly reducing indoor PM2.5 concentrations, can lead to reduced respiratory inflammation, improved lung function (PEF) and airway mechanics in asthmatic children.Oxidative stress is a core mechanism involved in the cardiorespiratory effects of air pollution. Malondialdehyde (MDA) is a well-established marker of oxidative stress. However, most of its use in existing studies were conducted by researchers in clinical medicine and epidemiology, who were unaware that MDA is present in both unconjugated and conjugated forms. Aim 3 of this dissertation examined the relationship between free MDA (unconjugated MDA) and total MDA (the sum of both unconjugated and conjugated MDA) in various types of human biospecimens. Using bio-banked samples from multiple studies, free MDA and total MDA were measured simultaneously in nasal fluid (N=158), saliva (N=158), exhaled breath condensate (N=40), serum (N=232), and urine samples (N=429). MDA quantification was performed using an HPLC-fluorescence method with high sensitivity and specificity. Due to the right-skewed distribution of free MDA and total MDA, natural-log transformation was performed before subsequent statistical analyses. The relationship between the natural log of free and total MDA was evaluated by R2 of simple linear regression. T-test was used for comparisons of means between two groups. One-way analysis of variance was used in combination with Tukey’s test to compare the natural log of the ratio of free MDA to total MDA across various types of biospecimens. For exhaled breath condensate, serum, urine, nasal fluid and saliva samples, the R2 between free and total MDA were 0.61, 0.22, 0.59, 0.47 and 0.06, respectively; the medians of the free MDA to total MDA ratio were 48.1%, 17.4%, 9.8%, 5.1% and 3.0%, respectively. The free MDA to total MDA ratio in EBC > serum > urine > nasal fluid > saliva (PThe Childhood Asthma Control Test (C-ACT) is a validated questionnaire that provides a subjective evaluation of asthma control using collective inputs from children and their caregivers. Cross-sectional studies have identified cut-points for discerning different degrees of asthma control. However, few studies have examined whether changes in the C-ACT score are reflective of changes in airway pathophysiology in longitudinal measurements from the same individuals. In Aim 4 of this dissertation, I utilized data from four clinical visits originally conducted for Aim 2. The clinical visits were scheduled bi-weekly over a period of six weeks. Thirty-seven children aged 5 to 10 with mild or moderate asthma (43% female) took the C-ACT. The scores were 24.4 ± 2.4 (mean ± standard deviation) and ranged from 16 to 27. Linear mixed-effects models were used to examine the association between C-ACT and clinical measurements from the same participants. As a change of two points in the C-ACT score is considered as the minimal clinically important difference, I reported the change in biomarkers associated with a two-point decrease in C-ACT score. Results showed that a two-point decrease was significantly associated with a 1.7% [95% CI: 0.1%, 3.3%] decrease in FEV1, a 1.6% [0.5%, 2.8%] decrease in FVC, and a 3.8% [0.0%, 7.6%] increase in airway resistance at 5 Hz (R5). For PEF measurements conducted within two weeks before the C-ACT, a two-point decrease in C-ACT score was significantly associated with a 17.3% [95%CI: 6.8%, 27.8%] increase in the coefficient of variation, while no significant association was observed with the average PEF value (P=0.12). In contrast, within-participant measurements showed no significant associations of C-ACT with respiratory inflammation (FeNO) or any of the small airway function and mechanics parameters (FEF25-75, FEF25-75, R5-R20, X5, and Fres). When examining individual questions of the C-ACT, none of the questions answered by the caregiver were significantly associated with indicators of lung function and respiratory inflammation. In contrast, three out of the four questions answered by the child demonstrated significant or marginally significant associations with FEV1, FVC, FEF25-75, R5, and R20. This suggests that in spite of the relatively young age of the participants, their perception of disease control provides important information for asthma control assessment. Overall, the findings in Aim 4 indicate that subjective evaluation of asthma control using the C-ACT was associated with objective measurements of airway obstruction, airway restriction, respiratory resistance and the variation of airflow limitations in longitudinal measurements. However, the C-ACT is not reflective of changes in respiratory inflammation and small airway mechanics, indicating that its use should be complementary to but not a substitute for these measurements.</p
A novel approach of mechanical chemical grinding
No full textIn this study, two diamond wheels are newly developed. A novel approach of mechanical chemical grinding (MCG) is proposed using the diamond wheel (C2) with ceria (CeO2) developed. A uniform wear layer of 48 nm in thickness is obtained on a silicon (Si) wafer ground by the C2 at a feed rate of 12 mu m/min, which is less than one third that formed by a conventional diamond wheel with mesh size of 5000. The uniform wear layer consists of a 40 nm amorphous layer at the top and an 8 nm damage crystalline layer beneath. Si, silica (SiO2) and SiOx are identified on all the ground Si wafers by energy dispersive spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy and Raman spectra. Only CeO2 and diamond are confirmed by XRD on the C2, indicating the perfect vitrified effect. CeO2, diamond and amorphous carbon are discerned by Raman spectra on the C2 at 466,1332 and 1430 cm(-1), respectively. (C) 2017 Elsevier B.V. All rights reserved
Single-chain nanoparticle based catalysts
No full textEnzymes achieve their excellent catalytic properties by surrounding the catalytic sites with a polypeptide scaffold. The three-dimensional structure of the peptide chains creates a local environment that supramolecularly binds substrates to facilitate the catalysis. In this dissertation, synthetic polymers are used to serve a similar role, binding substrates and creating an optimal environment for performing efficient catalysis. Several single-chain nanoparticle (SCNP) catalysts have been developed to perform copper(I)-mediated alkyne–azide cycloaddition (CuAAC), “click” reactions, or the photoreduction of azido groups to amines. The nanoparticles are shown to have significantly higher activity when compared to analogous small molecule catalysts. Structure-activity relationships and reaction mechanisms are studied with SCNPs of different structures. The polymeric scaffolds are found to bind substrates in an enzyme-like manner. The catalysts operate in two modes: an “uptake mode” where small molecule substrates bind inside the polymer pockets and an “attach mode” that involves surface binding of protein substrates. The versatility and high efficiency of the nanoparticles lead to applications in protein and cell surface modification. In addition, another SCNP was shown to co-deliver an exogenous enzyme inside cells. The enzyme and SCNP reside and stay active in the endosomes, in essence engineering the endosome into an artificial organelle. The SCNP-enzyme complex can perform both concurrent and tandem reactions performing organic synthesis intracellularly. The combination of SCNP and enzymatic catalysts provides a versatile tool for intracellular organic synthesis with applications in chemical biology.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2022-05-01The student, Junfeng Chen, accepted the attached license on 2020-04-21 at 15:27.The student, Junfeng Chen, submitted this Dissertation for approval on 2020-04-21 at 15:53.This Dissertation was approved for publication on 2020-04-23 at 10:51.DSpace SAF Submission Ingestion Package generated from Vireo submission #15024 on 2020-08-25 at 17:27:49Made available in DSpace on 2020-08-26T23:54:35Z (GMT). No. of bitstreams: 2
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Previous issue date: 2020-04-23Embargo set by: Seth Robbins for item 115727
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Phase Equilibrium Study of the AlCl3-CaCl2-H2O System for the Production of Aluminum Chloride Hexahydrate from Ca-Rich Flue Ash
No full textThe study of the solidliquid phase equilibrium for the AlCl3-CaCl2-H2O system is of significance to separate aluminum chloride hexahydrate from the leachate obtained by the reaction of Ca-rich fly ash and a waste hydrochloride from chemical plant. The phase equilibrium data for the binary AlCl3-H2O system and the ternary AlCl3-CaCl2-H(2)Osystem over the temperature range from 278.15 K to 363.15 K were measured. A rigorous and thermodynamically consistent model representing the AlCl3-CaCl2-H(2)Osystem developed on the basis of the Pitzers activity coefficient model embedded in the Aspen Plus. On the basis of this, the phase behavior of the ternary AlCl3-CaCl2-H2O system at different temperatures was visualized with lucidity on an equilateral triangle. The phase-equilibrium diagram generated by modeling was illustrated to identify the course of crystallization to recover AlCl3.6H(2)O from the solutions containing calcium chloride. All of these will provide a thermodynamic basis for the separation of aluminum chloride from calcium chloride solutions
China's Wind-Power Generation Policy and Market Development
No full textThe Chinese government set its wind power generation capacity target at 5 million kW for 2010 and 30 million kW for 2020 in its Medium to Long-term Renewable Energy Development Plan released in September 2007. The 11th Five-Year Renewable Energy Development Plan, announced in March 2008, doubled the 2010 target to 10 million kW, attracting much attention from relevant parties. This report considers the challenges and future course of the Chinese wind power development policies and other background factoes behind the government's upward revision to the wind power genration capacity in the 11th Five-Year Renewable Energy Development Plan.China, wind-power, Energy, market developments
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