1,722,202 research outputs found
A universally applicable 0D turbulence model based on the physical analysis of fundamental tumble behaviors in spark-ignition engines
No full textPredicting turbulence in a zero-dimensional (0D) simulation is an undeniably challenging task due to the complexity of in-cylinder charge motion. In that respect, a physics-based understanding of in-cylinder flow phenomena is of vital importance for establishing high-fidelity 0D turbulence models under diverse engine conditions. The proposed 0D model is hence built upon the kinetic energy analyses of tumble, evidenced by three-dimensional computational fluid dynamics. Specifically, the overall 0D turbulence model consists of an intake model, a spinning up model, and a turbulence production model. The major difference between this model and the existing 0D turbulence models is that this model is grounded on a kinetic energy perspective of tumble, as opposed to an angular momentum perspective of tumble. That is, the behaviors of tumble, such as spinning up and vortex breakdown, are interpreted and modeled based on the changes in the kinetic energy of tumble. This enables the proposed model to secure wider applicability at various engine conditions, which were otherwise difficult to achieve. Therefore, the 0D simulation in this study was able to predict turbulent intensities at the conditions, differing in valve strategy, engine geometry, and engine operation, without changing any validation constants. Furthermore, along with the validation points used in this study, better predictions of turbulent intensity were achieved using the proposed model compared to the existing state-of-the-art model.N
Solid oxide fuel cell-internal combustion engine hybrid system utilizing an internal combustion engine for anode off-gas recirculation, external reforming, and additional power generation
No full textA solid oxide fuel cell (SOFC)-internal combustion engine (ICE) hybrid system is proposed and analyzed. Although the existing SOFC-ICE hybrid system improves the efficiency of the SOFC stand-alone system by deriving additional power from the anode off-gas in the ICE, the proposed hybrid system further increases the system efficiency by utilizing the ICE for anode off-gas recirculation, external reforming, and additional power generation. Accordingly, we developed models for the SOFC and ICE and performed simulations to understand the operational characteristics of the hybrid system. Through simulation, the influence of each control parameter was analyzed, and the system operable ranges were determined according to the rate of system heat loss. When the heat loss considered is the least, a gross system efficiency of 66.9% is achieved at the optimum point. Thus, this study developed a high-efficiency SOFC-ICE hybrid system by combining methods that utilize the ICE as a recirculation blower, reformer, and power generator.N
A study on the alloy design and degradation mechanism of type high capacity metal-hydride electrode for Ni/MH rechargeable battery
No full text학위논문(박사) - 한국과학기술원 : 재료공학과, 1996.8, [ v, 144 p. ]한국과학기술원 : 재료공학과
Design and performance analysis of variable configuration tracked vehicle
No full text학위논문(석사) - 한국과학기술원 : 기계공학전공, 2000.2, [ vii, 60 p. ]한국과학기술원 : 기계공학전공
Tackling Surgical Morbidity and Mortality through Modifiable Risk Factors in Cancer Patients
No full textDespite advances in surgical techniques, surgical morbidity and mortality remain important public health problems. Postoperative complications often lead to greater morbidity and mortality, as well as increased length of hospital stay and medical costs. Therefore, a reduction in postoperative complications is particularly important with regard to positive long-term outcomes in patients with cancer. To improve patients’ postoperative prognosis, it is necessary to screen for and focus on modifiable risk factors and their subsequent resolution. Recently, it was reported that nutritional status, inflammation and surgical approaches are related to postoperative morbidity and mortality. Therefore, in this review article, we describe the current evidence regarding modifiable risk factors influencing surgical morbidity and mortality as well as future directions for improved postoperative management in cancer patients
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
A new species of Myoleja Rondani (Diptera: Tephritidae) from Turkey with a key to the known species of the genus
No full textHan, Ho-Yeon, Kütük, Murat (2006): A new species of Myoleja Rondani (Diptera: Tephritidae) from Turkey with a key to the known species of the genus. Zootaxa 1155: 25-33, DOI: 10.5281/zenodo.17224
A second species of Manicomyia Hancock (Diptera: Tephritidae: Tephrellini)
No full textFreidberg, Amnon, Han, Ho-Yeon (2012): A second species of Manicomyia Hancock (Diptera: Tephritidae: Tephrellini). African Invertebrates 53 (1): 143, DOI: 10.5733/afin.053.0108, URL: http://www.bioone.org/doi/abs/10.5733/afin.053.010
- …
