Combustion and atomization studies of coal-water fuel in a laminar flow reactor and in a pilot-scale furnace

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1988.Vita.Includes bibliographies.by Shin-Won Kang.Ph.D

RECONSTRUCTION OF SOCIAL SCIENCE AND HUMANITIES THROUGH NARRATIVE

Purpose: The purpose of this paper is to present new directions and research strategies through critical analysis of the academic tendencies of existing social science and humanities. The narrative theory of human experience is adopted as a theoretical rationale for critical analysing existing social sciences and humanities. Since the 1970s and 1980s, the academic tendencies of the humanities and social sciences have been transformed into the narrative turn. We focus on the new integrity of humanities and social sciences in light of the narrative theory that approaches the totality of human life. The narrative theory for academic inquiry makes use of the position of Bruner, Polkinghorne, Ricoeur Methodology: We reviewed the literature related to the research topic and took an integrated approach to the philosophical analysis of core claims. Main Findings: As a result, the narrative theory has a characteristic approach to human life and experience as a whole, and it is possible to integrate by narrative ways of knowing. Implications/Applications: Based on this narrative theory, existing humanities and social sciences need to be reconstructed into narrative science. And a narrative method or narrative inquiry is useful as its specific inquiry method. As a narrative science, humanities and social sciences can be implemented by the integration of human experience and narrative epistemology. It has the advantage of integrating the atomized sub-sciences into the narrative of human experience according to this new method. Also, in-depth research on concrete exploration strategies is expected in the future

Collisional Dynamics of Half-Quantum Vortices in a Spinor Bose-Einstein Condensate

We present an experimental study on the interaction and dynamics of half-quantum vortices (HQVs) in an antiferromagnetic spinor Bose-Einstein condensate. By exploiting the orbit motion of a vortex dipole in a trapped condensate, we perform a collision experiment of two HQV pairs, and observe that the scattering motions of the HQVs is consistent with the short-range vortex interaction that arises from nonsingular magnetized vortex cores. We also investigate the relaxation dynamics of turbulent condensates containing many HQVs, and demonstrate that spin wave excitations are generated by the collisional motions of the HQVs. The short-range vortex interaction and the HQV-magnon coupling represent two characteristics of the HQV dynamics in the spinor superfluid.Comment: 7 pages, 6 figure

Observation of wall-vortex composite defects in a spinor Bose-Einstein condensate

We report the observation of spin domain walls bounded by half-quantum vortices (HQVs) in a spin-1 Bose-Einstein condensate with antiferromagnetic interactions. A spinor condensate is initially prepared in the easy-plane polar phase, and then, suddenly quenched into the easy-axis polar phase. Domain walls are created via the spontaneous $\mathbb{Z}_2$ symmetry breaking in the phase transition and the walls dynamically split into composite defects due to snake instability. The end points of the defects are identified as HQVs for the polar order parameter and the mass supercurrent in their proximity is demonstrated using Bragg scattering. In a strong quench regime, we observe that singly charged quantum vortices are formed with the relaxation of free wall-vortex composite defects. Our results demonstrate a nucleation mechanism for composite defects via phase transition dynamics.Comment: 10 pages, 11 figures, reference update

Value Discount of Business Groups Surrounding the Asia Financial Crisis: Evidence from Korean Chaebols

Asian Financial Crisis, Business Group, Chaebol, Diversification, Firm Value

Different Modulation of the Cortical Silent Period by Two Phases of Short Interval Intracortical Inhibition

PURPOSE: To investigate the influence of 2 phases of short interval intracortical inhibition (SICI) on the cortical silent period (SP). MATERIALS AND METHODS: Single- and paired-pulse transcranial magnetic stimulations (TMSs) at 1 and 2.5ms interstimulus intervals (ISIs) were applied to the left motor cortex in 12 healthy subjects while their right hand muscles were moderately activated. Conditioning stimulation intensity was 90% of the active motor threshold (AMT). Test stimulation intensities were 120, 140, 160, 180, 200, 220, 240, 260% of the AMT and at 100% of the maximal stimulator output, the order of which was arranged randomly. The rectified electromyography area of motor evoked potential (MEP) and duration of the SP were measured off-line using a computerized program. RESULTS: At high-test stimulation intensities, MEP areas were saturated in both single- and paired-pulse stimulations, except that saturated MEPs were smaller for the paired-pulse TMS at 1ms ISI than for the other conditions. As the test stimulation intensity increased, SP was progressively prolonged in both single- and paired-pulse stimulations but was shorter in paired-pulse than single-pulse TMS. Overall, the ratio of SP duration/MEP area was comparable between single- and paired-pulse TMS except for the paired-pulse TMS at 1 ms ISI with a test stimulation intensity at 140-180% of the AMT, in which the ratio was significantly higher than in the single pulse TMS. CONCLUSION: These results suggest that 2 phases of SICI modulate MEP saturation and SP duration differently and provide additional evidence supporting the view that 2 phases of SICI are mediated by different inhibitory mechanisms.ope

Observation of a Geometric Hall Effect in a Spinor Bose-Einstein Condensate with a Skyrmion Spin Texture

For a spin-carrying particle moving in a spatially varying magnetic field, effective electromagnetic forces can arise due to the geometric phase associated with adiabatic spin rotation of the particle. We report the observation of a geometric Hall effect in a spinor Bose-Einstein condensate with a skyrmion spin texture. Under translational oscillations of the spin texture, the condensate resonantly develops a circular motion in a harmonic trap, demonstrating the existence of an effective Lorentz force. When the condensate circulates, quantized vortices are nucleated in the boundary region of the condensate and the vortex number increases over 100 without significant heating. We attribute the vortex nucleation to the shearing effect of the effective Lorentz force from the inhomogeneous effective magnetic field.Comment: 9 pages, 11 figure

Toxic effects of ammonia exposure on growth performance, hematological parameters, and plasma components in rockfish, Sebastes schlegelii, during thermal stress

Abstract Rockfish, Sebastes schlegelii (mean length 14.53 ± 1.14 cm and mean weight 38.36 ± 3.45 g), were exposed for 4 weeks with the different levels of ammonia in the concentrations of 0, 0.1, 0.5, and 1.0 mg/L at 19 and 24 °C. The indicators of growth performance such as daily length gain, daily weight gain, condition factor, and hematosomatic index were significantly reduced by the ammonia exposure and high temperature. The ammonia exposure induced a significant decrease in hematological parameters, such as red blood cell (RBC) count, white blood cell (WBC) count, hemoglobin (Hb), and hematocrit (Ht), whose trend was more remarkable at 24 °C. Mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC) were also notably decreased by the ammonia exposure. Blood ammonia concentration was considerably increased by the ammonia concentration exposure. In the serum components, the glucose, glutamic oxalate transaminase (GOT), and glutamic pyruvate transaminase (GPT) were substantially increased by the ammonia exposure, whereas total protein was significantly decreased. But, the calcium and magnesium were not considerably changed

Optimal Frequency Intensity of Physical Activity to Reduce the Risk of Hypertension in the Korean Population

PURPOSE: Regular physical activity (PA) is an effective lifestyle modification for preventing hypertension. This study aimed to analyze the optimal frequency of PA required to reduce the incidence of hypertension in the Korean population. Most Korean studies have included only small samples and limited age ranges. METHODS: The present study analyzed 16,299,865 participants aged ≥20 years (44.25±12.74 years) from the 2009 to 2012 Korean National Health Insurance Corporation Survey database. The International Physical Activity Questionnaire was used to assess the frequency and intensity of physical activity. Hazard ratios for incident hypertension were analyzed by physical activity participation, age, and sex using multivariable Cox proportional hazard models, with a non-regular physical activity group as reference. RESULTS: A total of 1,322,674 cases of incident hypertension were identified during the mean follow-up period of over 3 years. Hazard ratios for incident hypertension increased with age, with values of 50.4 and 56.1 for men and women in the older age group, respectively. Hazard ratios for incident hypertension were significantly lower in the regular PA group of middle-aged (4%) and older (7%) adults than in the non-regular PA group. The study revealed that moderate-to-vigorous-intensity PA 3-5 times/week was most effective in reducing the risk of incident hypertension in middle-aged and older adults but not in young adults. We observed no additional lowering of incident hypertension risk in the group undergoing moderate-to-vigorous PA at a frequency of 6-7 days/week compared to the 35 days/week group. CONCLUSIONS: We suggest PA at a frequency of 3-5 times/week for the prevention of incident hypertension in Korean adults