Conventional and Alternative Jet Fuels for Diesel Combustion: Surrogate Development and Insights into the Effect of Fuel Properties on Ignition.

The use of kerosene-based jet fuels for all military applications has been mandated by U.S. military’s single fuel forward concept. Recently, interest in non-petroleum-derived alternative jet fuels has also been increasing as a way to diversify the source of jet fuels. Computational Fluid Dynamics (CFD) simulations with detailed kinetic modeling can be used to model the combustion behavior of real fuel and predict their performance. This thesis revolves around the development of a surrogate mixture for real jet fuels, kinetic models for the surrogate components, and CFD simulations of diesel engines to assess the effects of surrogate’s chemical and physical properties on fundamental combustion processes. Fuel surrogates are mixtures of one or more simple fuels that are designed to emulate key properties of a more complex fuel. For the first time we report on a comprehensive jet fuel surrogates that successfully emulate physical and chemical properties of conventional and alternative jet fuels. To identify the target properties that need to be used to reproduce the diesel combustion, in the first part of this dissertation, a sensitivity analysis was conducted with CFD simulations of pure n-dodecane spray in a constant volume chamber to identify temperature dependent liquid physical properties that are of significance to the diesel ignition process. Out of six physical properties that were tested, density, viscosity, volatility, and specific heat showed major impact on liquid penetration length and ignition delay time. Using a six-component surrogate palette (n-dodecane, n-decane, iso-cetane, iso-octane, decalin, and toluene), the surrogate optimizer generated surrogate mixtures for Jet-A POSF-4658, a petroleum-derived conventional jet fuel, IPK POSF-5642, a coal-derived synthetic jet fuel, and S-8 POSF-4734, a natural-gas-derived synthetic jet fuel. Kinetic modeling of the surrogate fuels were enabled by a detailed chemical mechanism. Numerical experiments were conducted using CFD simulations to evaluate the importance of physical and chemical properties of surrogates on the ignition process of the fuel spray for two fuels. This study indicates that the chemical properties of fuel are much more important to the duration of the ignition delay period than the physical properties, which emphasizes the chemical aspect of the diesel ignition phenomena.PHDMechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/120818/1/gogum_1.pd

Real-Time Control of Sawteeth and NTMs in TCV and ITER

The main goal of this thesis is to demonstrate the capability of magneto-hydrodynamic (MHD) instability control, particularly sawteeth and neoclassical tearing modes (NTMs), in order to achieve high performance operation. Experiments and simulations have been carried out to pursue this purpose on different tokamaks: TCV (in Switzerland), KSTAR (in Korea), AUG (in Germany) and ITER (in construction in France). Each tokamak has different features such as machine size, heating systems, operation scenarios and energy confinement time scale, all the tokamaks are equipped or will be equipped with an electron cyclotron heating/current drive (ECH/ECCD) system for plasma heating/current drive and control of MHD instabilities. Therefore, this work focusses on the feasibility of using the localised ECH/ECCD beams to control the instabilities; sawteeth and NTMs. For the experimental part, sawtooth and NTM control experiments have been carried out. In TCV, novel ways of sawtooth period control - sawtooth pacing and locking - have experimentally been demonstrated using the TCV real-time control system. Based on the successful application of these methods to sawtooth control in TCV, we have next focussed on the extension of these new sawtooth period control methods to other tokamaks: KSTAR and AUG. In the 2013 KSTAR experimental campaign, the applicability of sawtooth locking using EC power modulation has been tested for sawtooth period control in the presence of fast particles generated by neutral beam injection (NBI). The KSTAR real-time control system was not ready for sawtooth pacing thus only locking has been examined. These preliminary KSTAR experimental results have shown the possibility of sawtooth period control using sawtooth locking, although proper locking was not obtained yet. The locking parameters would still need to be adjusted for single period locking to occur. In order for the investigation of the capability of sawtooth locking on KSTAR tokamak to be complete, more experiments with different locking parameters should be carried out. The sawtooth locking technique has also been applied to AUG plasmas. As in the KSTAR tokamak, the real-time control for sawtooth pacing was not available, thus sawtooth locking has been tested. The AUG plasmas were more complicated compared to TCV and KSTAR cases due to the fast particles effect on the evolution of sawtooth from both NBI and ion cyclotron heating (ICH). Sawteeth did not lock to the EC modulation in AUG experiments, though in some discharges they became somewhat more regular. However, the application of sawtooth locking to the AUG tokamak has been well initiated and more experiments will follow to understand better the behaviour of sawteeth and to determine the sawtooth locking range. In addition, sawtooth control was demonstrated and used in other experiments studying the role of sawteeth on impurity transport. Concerning the NTM control experiments, we have focussed on the enhancement of the NTM control strategy, which has been achieved in two ways. In previous TCV experiments, NTM stabilisation was obtained as ECH/ECCD deposition was swept in one direction until the mode disappeared. In order to ameliorate the control of NTMs, as a first improvement, a real-time version of the equilibrium reconstruction code LIUQE (RT-LIUQE) has been implemented in the TCV real-time control system. [...

Numerical optimization of ramp-down phases for TCV and AUG plasmas

Optimization of the plasma discharge can be defined as determination of an optimal time evolution of the plasma parameters to lead a plasma to a desired state keeping it within the specific limits: physical ones (like the Greenwald density limit, low normalized beta and internal inductance values) and technical ones (like the vertical stability limit). The parameters, time-trajectories of which have to be optimized, are the ones significantly changing the plasma state, and, depending on the optimization goal, can be chosen from a wide range of plasma parameters: plasma current, plasma elongation, EC, NBI heating or current drive power, electron density, etc. Developing non-disruptive termination scenarios is important for safe operation of future tokamaks and especially for ITER since significant heat fluxes to the wall are expected during disruptions because of large amount of energy stored in burning plasmas. Therefore, the main goal of ramp-down optimization is to ramp down a plasma current as fast as possible while avoiding any disruptions. The results of the optimization problem study with the physical and technical limits is presented for TCV and AUG plasmas. The present work was done mainly with the RAPTOR code. The transport model has been extended to include a time-varying plasma equilibrium geometry, increasing the accuracy of full discharge simulations. Due to the design, the RAPTOR code is also an efficient tool for an optimization problem solving. A new ad-hoc transport model has been implemented to the RAPTOR code and tested during this work. Verification of the thermal transport model with simulation of the AUG and TCV full plasma discharges using RAPTOR will be presented

On the non-stiffness of edge transport in L-modes

It is shown that contrary to the plasma core, the edge region between rho_V=0.8 and 1 is not stiff. This non-stiffness is crucial for global confinement understanding. It is also shown that it can explain the strong confinement improvement with negative triangularity observed in TCV

The Expression of Adipophilin Is Frequently Found in Solid Subtype Adenocarcinoma and Is Associated with Adverse Outcomes in Lung Adenocarcinoma

Background The up-regulation of the lipogenic pathway has been reported in many types of malignant tumors. However, its pathogenic role or clinical significance is not fully understood. The objective of this study was to examine the expression levels of adipophilin and related hypoxic signaling proteins and to determine their prognostic impacts and associations with the pathologic characteristics of lung adenocarcinoma. Methods Expression levels of adipophilin, heat shock protein 27 (HSP27), carbonic anhydrase IX, and hypoxia-inducible factor 1α were examined by immunohistochemical staining using tissue microarray blocks. Correlations between protein expression levels and various clinicopathologic features were analyzed. Results A total of 230 cases of primary adenocarcinoma of the lung were enrolled in this study. Adipophilin expression was more frequent in males and with the solid histologic type. It was correlated with HSP27 expression. Patients with adipophilin-positive adenocarcinoma showed a shorter progression-free survival (PFS) (median PFS, 17.2 months vs 18.4 months) in a univariable survival analysis, whereas HSP27 positivity correlated with favorable overall survival (OS) and PFS. In a multivariable analysis, adipophilin and HSP27 were independent prognostic markers of both OS and PFS. Conclusions Activated lipid metabolism and the hypoxic signaling pathway might play a major role in the progression of lung adenocarcinoma, especially in the solid histologic type

Round-robin test on thermal conductivity measurement of ZnO nanofluids and comparison of experimental results with theoretical bounds

Ethylene glycol (EG)-based zinc oxide (ZnO) nanofluids containing no surfactant have been manufactured by one-step pulsed wire evaporation (PWE) method. Round-robin tests on thermal conductivity measurements of three samples of EG-based ZnO nanofluids have been conducted by five participating labs, four using accurate measurement apparatuses developed in house and one using a commercial device. The results have been compared with several theoretical bounds on the effective thermal conductivity of heterogeneous systems. This study convincingly demonstrates that the large enhancements in the thermal conductivities of EG-based ZnO nanofluids tested are beyond the lower and upper bounds calculated using the models of the Maxwell and Nan et al. with and without the interfacial thermal resistance

Inhibitory Effect of KP-A038 on Osteoclastogenesis and Inflammatory Bone Loss Is Associated With Downregulation of Blimp1

Excessive osteoclastic activity results in pathological bone resorptive diseases, such as osteoporosis, periodontitis, and rheumatoid arthritis. As imidazole-containing compounds possess extensive therapeutic potential for the management of diverse diseases, we synthesized a series of imidazole derivatives and investigated their effects on osteoclast differentiation and function. In the present study, we found that a novel imidazole derivative, KP-A038, suppressed receptor activator of nuclear factor-κB ligand (RANKL)-mediated osteoclastogenesis and bone-resorbing activity in vitro and attenuated lipopolysaccharide (LPS)-induced bone destruction in vivo. KP-A038 significantly inhibited the induction of nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1) and the expression of its target genes, including tartrate-resistant acid phosphatase (Acp5), cathepsin K (Ctsk), dendritic cell-specific transmembrane protein (Dcstamp), and matrix metallopeptidase 9 (Mmp9). KP-A038 upregulated the expression of negative regulators of osteoclast differentiation, such as interferon regulatory factor-8 (Irf8) and B-cell lymphoma 6 (Bcl6). Consistently, KP-A038 downregulated the expression of B lymphocyte-induced maturation protein-1 (Blimp1 encoded by Prdm1), a repressor for Irf8 and Bcl6. Moreover, administration of KP-A038 reduced LPS-induced bone erosion by suppressing osteoclast formation in vivo. Thus, our findings suggest that KP-A038 may serve as an effective therapeutic agent for the treatment and/or prevention of bone loss in pathological bone diseases, including osteoporosis and periodontitis