Turbocharged engine operations using knock resistant fuel blends for engine efficiency improvements

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (p. 61).Engine downsizing with a turbocharger has become popular these days in automotive industries. Downsizing the engine lets the engine operate in a more efficient region, and the engine boosting compensates for the power loss accompanied by downsizing. However, the use of high boost in a downsized engine is limited by knock. Changing operating parameters such as spark timing has shown to be effective in avoiding knock. However, those strategies usually deteriorate efficiency of the engine. Another method to suppress knock without lowering efficiency is to use knock resistant fuels. Among them ethanol has gotten a large attention due to its renewable characteristics. About 13.3 billion gallons of ethanol were produced in 2012, and about 99 % of them are used as fuel added to gasoline. However, the optimal use of ethanol in a spark ignited engine as a knock suppressing additive is not well quantified. Also, operation limitations of a knock free engine are not well known. The objective of this project was to determine the knock onset engine operating conditions and to explore the potential of a direct injection of ethanol enhanced fuels. An engine with a turbocharger was used to measure efficiencies of the engine over the wide range of operating points. Speed range was chosen from 1500 rpm to 3000 rpm in which vehicle is usually driven in the driving cycle. Then, knock onset of different ethanol-gasoline blends, from 0 % ethanol to 85 % ethanol contents with 91 RON gasoline, were determined. Generated engine fuel consumption maps with knock onset limits were utilized in a vehicle driving simulation tool. In a simulation, the consumption of gasoline and knock suppressing fuels was determined in different driving cycles. Finally, effects of downsizig and spark retard on ethanol fraction in the fuel were determined.by Young Suk Jo.S.M

Dynamic Changes in Maritime Research Capability in Chinese Universities

This study determines the top fifty authors in China and their university affiliations in the maritime transportation field, compared to their world ranking. We refer to China in the broad sense of the Chinese economies, including not only mainland China and Hong Kong, but also Chinese Taipei (Taiwan) and Singapore. This study analyzes sixty-five SSCI and SCI journals in the field of maritime and transportation between the years 2000 and 2015. In terms of ranking, three indicators are employed: total number of articles, weighted score (indication of author contribution), and the impact score. With the exception of Shanghai Jiao Tong University, no other universities selected in the first phase of Project 985, which received billions of dollars in government support/aid, were listed in the world ranking. Star authors are deemed to have contributed greatly to the rankings of their affiliated universities. The future of China’s rankings is bright in view of the increasing number of papers being published by Chinese authors and universities and their strong grounding in quantitative methodologies. Document type: Articl

Comparative Analysis of Driver Mutations and Transcriptomes in Papillary Thyroid Cancer by Region of Residence in South Korea

Background Radiation exposure is a well-known risk factor for papillary thyroid cancer (PTC). South Korea has 24 nuclear reactors in operation; however, no molecular biological analysis has been performed on patients with PTC living near nuclear power plants. Methods We retrospectively included patients with PTC (n=512) divided into three groups according to their place of residence at the time of operation: inland areas (n=300), coastal areas far from nuclear power plants (n=134), and nuclear power plant areas (n=78). After propensity score matching (1:1:1) by age, sex, and surgical procedure, the frequency of representative driver mutations and gene expression profiles were compared (n=50 per group). Epithelial-mesenchymal transition (EMT), BRAF, thyroid differentiation, and radiation scores were calculated and compared. Results No significant difference was observed in clinicopathological characteristics, including radiation exposure history and the frequency of incidentally discovered thyroid cancer, among the three groups. BRAFV600E mutation was most frequently detected in the groups, with no difference among the three groups. Furthermore, gene expression profiles showed no statistically significant difference. EMT and BRAF scores were higher in our cohort than in cohorts from Chernobyl tissue bank and The Cancer Genome Atlas Thyroid Cancer; however, there was no difference according to the place of residence. Radiation scores were highest in the Chernobyl tissue bank but exhibited no difference according to the place of residence. Conclusion Differences in clinicopathological characteristics, frequency of representative driver mutations, and gene expression profiles were not observed according to patients’ region of residence in South Korea

Electric field control of nonvolatile four-state magnetization at room temperature

We find the realization of large converse magnetoelectric (ME) effects at room temperature in a multiferroic hexaferrite Ba$_{0.52}$Sr$_{2.48}$Co$_{2}$Fe$_{24}$O$_{41}$ single crystal, in which rapid change of electric polarization in low magnetic fields (about 5 mT) is coined to a large ME susceptibility of 3200 ps/m. The modulation of magnetization then reaches up to 0.62 $\mu$$_{B}$/f.u. in an electric field of 1.14 MV/m. We find further that four ME states induced by different ME poling exhibit unique, nonvolatile magnetization versus electric field curves, which can be approximately described by an effective free energy with a distinct set of ME coefficients

Genetic Analyses of the Chimeric CYP11B1/CYP11B2 Gene in a Korean Family with Glucocorticoid-Remediable Aldosteronism

Glucocorticoid-remediable aldosteronism (GRA) is an autosomal-dominant inheritable form of hyperaldosteronism with early onset hypertension. GRA is caused by unequal crossing-over of the steroid 11β-hydroxylase (CYP11B1) and aldosterone synthase (CYP11B2) genes. As a result of chimeric gene duplication, aldosterone is ectopically synthesized in the adrenal zona fasciculata under the control of adrenocorticotropin. Here, we describe three cases of GRA in a Korean family. The proband-a 21-yr-old female-was incidentally found to have high blood pressure (170/108 mmHg). Her 46-yr-old father had been treated twice for cerebral hemorrhage at the ages of 29 and 39 yr. Her 15-yr-old brother had a 2-yr history of hypertension; however, he was never treated. Their laboratory test results showed normokalemia, hyporeninemia, hyperaldosteronism, and a high plasma aldosterone concentration-to-plasma renin activity ratio. Normal saline loading failed to suppress aldosterone secretion. However, dexamethasone administration effectively suppressed their plasma aldosterone concentrations. Following genetic analyses with PCR and direct sequencing to document the chimeric gene and crossover site, respectively, we identified CYP11B1/CYP11B2 and determined the breakpoint of unequal crossover to be located between intron 2 of CYP11B1 and exon 3 of CYP11B2

Hypoxia-inducible factor-1 alpha regulates microglial functions affecting neuronal survival in the acute phase of ischemic stroke in mice

Cells universally adapt to ischemic conditions by turning on a transcription factor hypoxia-inducible factor (HIF), in which its role is known to differ widely across many different types of cells. Given that microglia have been reported as an essential mediator of neuroinflammation in many brain diseases, we examined the role of HIF in microglia in the progression of an acute phase of ischemic stroke by challenging our novel strains of myeloid-specific Hif-1 alpha or Hif-2 alpha knockout (KO) mice created by Cre-loxP system via middle cerebral artery occlusion (MCAO). We observed that Hif-1 alpha but not Hif-2 alpha KO mice exhibited an improved recovery compared to wild-type (WT) mice determined by behavioral tests. Immunostaining analyses revealed that there were increased numbers of both mature and immature neurons while microglia and apoptotic cells were significantly decreased in the dentate gyrus of Hif-1 alpha KO mice following MCAO. By isolating microglia with fluorescence-activated cell sorter, we found that HIF-1 alpha-deficient microglia were impaired in phagocytosis, reactive oxygen species (ROS) production, and tumor necrosis factor-alpha (TNF-alpha) secretion. We further observed a significant decrease in the expression of Cd36 and milk fat globule-epidermal growth factor 8 (Mfg-e8) genes, both of which contain hypoxia-responsive element (HRE). Knocking down either of these genes in BV2 microglial cells was sufficient to abrogate HIF-mediated increase in phagocytosis, production of intracellular ROS, or TNF-alpha secretion. Our results therefore suggest that HIF-1 alpha in microglia is a novel therapeutic target to protect neuronal survival following an acute phase of ischemic stroke.113Ysciescopu

Probiotics (Lactobacillus rhamnosus R0011 and acidophilus R0052) Reduce the Expression of Toll-Like Receptor 4 in Mice with Alcoholic Liver Disease

Objective The role of lipopolysaccharide (LPS) and toll-like receptor 4 (TLR 4) in the pathogenesis of alcoholic liver disease (ALD) has been widely established. We evaluated the biological effects of probiotics (Lactobacillus rhamnosus R0011 and acidophilus R0052), KRG (Korea red ginseng), and urushiol (Rhus verniciflua Stokes) on ALD, including their effects on normal and high-fat diet in mice. Methods One hundred C57BL/6 mice were classified into normal (N) and high-fat diet (H) groups. Each group was divided into 5 sub-groups: control, alcohol, alcohol+probiotics, alcohol+KRG, and alcohol+urushiol. A liver function test, histology, electron-microscopy, interleukin (IL)-1β, tumor necrosis factor (TNF)-α, IL-6, and IL-10, and TLR 4 were evaluated and compared. Results In the N group, probiotics, KRG, and urushiol significantly reduced levels of TNF-α (12.3±5.1, 13.4±3.9, and 12.1±4.3 vs. 27.9±15.2 pg/mL) and IL-1β (108.4±39.4, 75.0±51.0, and 101.1±26.8 vs. 162.4±37.5 pg/mL), which were increased by alcohol. Alcohol-induced TLR 4 expression was reduced by probiotics and urushiol (0.7±0.2, and 0.8±0.1 vs. 1.0±0.3, p<0.001). In the H group, IL-10 was significantly increased by probiotics and KRG, compared with alcohol (25.3±15.6 and 20.4±6.2 vs. 7.6±5.6 pg/mL) and TLR 4 expression was reduced by probiotics (0.8±0.2 vs. 1.0±0.3, p = 0.007). Conclusions Alcohol-induced TLR 4 expression was down-regulated by probiotics in the normal and high-fat diet groups. Probiotics, KRG, and urushiol might be effective in the treatment of ALD by regulating the gut-liver axis

Longitudinal association between adiposity changes and lung function deterioration

Background The longitudinal relationship between adiposity and lung function is controversial. We aimed to investigate the long-term association between adiposity changes and lung function in a middle-aged general Asian population. Methods In total, 5011 participants (average age, 54years; 45% men) were enrolled from a community-based prospective cohort. During the follow-up period (median 8years), both spirometry and bio-electrical impedance analysis were performed biannually. Individual slopes of the fat mass index (FMI; fat mass divided by the square of height in meters) and waist-to-hip ratio (WHR) were calculated using linear regression analysis. Multivariate linear mixed regression analysis was used to determine the long-term association between adiposity changes and lung function. Results The FMI was inversely associated with forced vital capacity (FVC) (estimated: − 31.8mL in men, − 27.8mL in women) and forced expiratory volume in 1s (FEV1) (estimated: − 38.2mL in men, − 17.8mL in women) after adjusting for baseline age, height, residential area, smoking exposure (pack-years, men only), initial adiposity indices, and baseline lung function. The WHR was also inversely associated with FVC (estimated = − 1242.2mL) and FEV1 (estimated = − 849.8mL) in men. The WHR-increased group showed a more rapid decline in lung function than the WHR-decreased group in both the fat-gain and fat-loss groups. Conclusion Adiposity was associated with the long-term impairment of lung function. Central obesity was the main driver of lung function impairment in the middle-aged general Asian population, regardless of fat mass changes