Chemical kinetics and CFD analysis of supercharged micro-pilot ignited dual-fuel engine combustion of syngas

A comprehensive chemical kinetics and computational fluid-dynamics (CFD) analysis were performed to evaluate the combustion of syngas derived from biomass and coke-oven solid feedstock in a micro-pilot ignited supercharged dual-fuel engine under lean conditions. The developed syngas chemical kinetics mechanism was validated by comparing ignition delay, in-cylinder pressure, temperature and laminar flame speed predictions against corresponding experimental and simulated data obtained by using the most commonly used chemical kinetics mechanisms developed by other authors. Sensitivity analysis showed that reactivity of syngas mixtures was found to be governed by H2 and CO chemistry for hydrogen concentrations lower than 50% and mostly by H2 chemistry for hydrogen concentrations higher than 50%. In the mechanism validation, particular emphasis is placed on predicting the combustion under high pressure conditions. For high hydrogen concentration in syngas under high pressure, the reactions HO2 + HO2 = H2O2 + O2 and H2O2 + H = H2 + HO2 were found to play important role in in-cylinder combustion and heat production. The rate constants for H2O2 + H = H2 + HO2 reaction showed strong sensitivity to high-pressure ignition times and has considerable uncertainty. Developed mechanism was used in CFD analysis to predict in-cylinder combustion of syngas and results were compared with experimental data. Crank angle-resolved spatial distribution of in-cylinder spray and combustion temperature was obtained. The constructed mechanism showed the closest prediction of combustion for both biomass and coke-oven syngas in a micro-pilot ignited supercharged dual-fuel engine

CO2 concentration measurements inside expansion-compression engine under high EGR conditions using an infrared absorption method

The purpose of this study is to measure the high concentrations of CO2 near a spark plug inside an internal combustion engine, and an infrared absorption method is used for the measurement. The spark plug sensor was adapted to a compression-expansion machine, and the CO2 concentration near the spark plug was measured by adding a gas mixture, including CO2 to imitate EGR. Next, the EGR ratio was changed from 10 to 40%, and the CO2 concentration was measured. The effect of the CO2 on the flame propagation was investigated by visualizing the bottom view of the compression-expansion machine. The measurements of CO2 mass concentration are in agreement with those predicted by direct-absorption spectroscopy fundamental theory from the crank angle −60 to −15 deg ATDC. The error was less than 20%, and under the conditions with an EGR ratio of 20–40%.The purpose of this study is to measure the high concentrations of CO2 near a spark plug inside an internal combustion engine, and an infrared absorption method is used for the measurement. The spark..

Quantum cascade laser assisted time-resolved measurements of carbon dioxide absorption during combustion in DME-HCCI engine

We conducted experiments to investigate in-cylinder light absorption by carbon dioxide (CO2) during homogeneous charge compression ignition (HCCI) engine combustion. The combustion was fuelled with dimethyl ether. An in situ laser infrared absorption method was developed. We used an optical fibre spark plug sensor and the light source was a 4.301 μm quantum cascade laser (QCL). We applied Lambert–Beer’s law in the case of a single absorption line of CO2. We were able to measure the transient CO2 formation during the HCCI combustion inside the engine cylinder. Our experiments showed that the laser light transmissivity level decreased with the intensity of the infrared (IR) signal. We compared the change in the transmissivity to the spatially integrated HCCI flame luminosity level and observed significant correlations between the flame luminosity level, heat release rate and transmissivity. Time-resolved experiments showed that the CO2 absorbance increases when the second peak of the rate of heat release (ROHR) is maximised. After combustion, the CO2 concentration was approximately 4 vol%, which agrees with the amount of CO2 formed during complete combustion

Endobronchial Electrocautery Using Snare

Between May 1987 and March 1994, upper airway and tracheobronchial electrosurgery with snare was performed in 13 patients (10 men and 3 women), ranging in age from 18 to 87 years. Four patients had benign lesions, and nine had malignant tumors. Total eradication has been achieved in the two patients with benign lesions. Electroexcision of the endobronchial portion of the tumor helped to clear the respiratory airways in all cases with malignant tumors. There has been no major side effects such as bleeding due to this method. Electrocautery is an available economical tool, which helps to diagnose and treat obstructing airway mass lesions

Soft X-ray Transmission Spectroscopy of Warm/Hot Intergalactic Medium with XEUS

We discuss the detectability of Warm/Hot Intergalactic medium (WHIM) via the absorption lines toward bright point sources with a future X-ray satellite mission, XEUS. While we consider bright QSOs as specific examples, the methodology can be applied to bright GRB afterglows. We create mock absorption spectra for bright QSOs (more than 20 QSOs over the all sky) using a light-cone output of a cosmological hydrodynamic simulation. We assume that WHIM is under collisional and photo-ionization equilibrium. If WHIM has a constant metallicity of $Z=0.1Z_\odot$, approximately 2 O{\sc vii} absorption line system with $>3\sigma$ will be detected on average along a random line-of-sight toward bright QSOs up to $z=0.3$ for 30 ksec exposure.Comment: 34 pages, 17 figures. Substantial revision. PASJ, in press (2006, vol.58, August 25 issue

Novel scotoma detection method using time required for fixation to the random targets

We developed a novel scotoma detection system using time required for fixation to the random targets, or the” eye-guided scotoma detection method “. In order to verify the” eye-guided scotoma detection method “, we measured 78 eyes of 40 subjects, and examined the measurement results in comparison with the results of measurement by Humphrey perimetry. The results were as follows: (1) Mariotte scotomas were detected in 100% of the eyes tested; (2) The false-negative rate (the percentage of cases where a scotoma was evaluated as a non-scotoma) was less than 10%; (3) The positive point distribution in the low-sensitivity eyes was well matched. These findings suggested that the novel scotoma detection method in the current study will pave the way for the realization of mass screening to detect pathological scotoma earlier.[Author summary] Conventional perimeters, such as the Goldmann perimeter and Humphrey perimeter, require experienced examiners and space occupying. With either perimeter, subjects’ eye movements need to be strictly fixed to the fixation target of the device. Other perimeters can monitor fixation and automatically measure the visual field. With the eye-guided scotoma detection method proposed in the current study, subjects feel less burdened since they do not have to fixate on the fixation target of the device and can move their eyes freely. Subjects simply respond to visual targets on the display; then, scotomas can be automatically detected. The novel method yields highly accurate scotoma detection through an algorithm that separates scotomas from non-scotomas

Clinical Study in 11 Cases of Endobronchial Foreign Body

We report 11 cases of endobronchial foreign body. From January 1982 through December 1994, a total of 11 cases were diagnosed roentogenographically and bronchoscopically at our hospital. These patients consisted of 10 men and 1 woman with a mean age of 58.5 years (range 33 to 77 years). Symptoms on presenting were usually cough, sputum, or chest pain. The foreign bodies were inorganic in 10 cases and of organic origin in 1 case. Three patients were not aware that they had aspirated a foreign body. In 9 patients, the endobronchial foreign bodies were successfully removed endoscopically. One patient spontaneously expectorated the foreign body before bronchoscopy. One patient underwent thoracotomy because the foreign body could not be removed bronchoscopically. There were no severe complications during or after the endoscopic removal of the foreign bodies, but in one patient extraction of the foreign body caused pneumonia after bronchoscopy. In conclusion, flexible bronchoscopy is useful for the diagnosis and treatment of endobronchial foreign bodies

The ASTRO-H X-ray Observatory

The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions initiated by the Institute of Space and Astronautical Science (ISAS). ASTRO-H will investigate the physics of the high-energy universe via a suite of four instruments, covering a very wide energy range, from 0.3 keV to 600 keV. These instruments include a high-resolution, high-throughput spectrometer sensitive over 0.3-2 keV with high spectral resolution of Delta E < 7 eV, enabled by a micro-calorimeter array located in the focal plane of thin-foil X-ray optics; hard X-ray imaging spectrometers covering 5-80 keV, located in the focal plane of multilayer-coated, focusing hard X-ray mirrors; a wide-field imaging spectrometer sensitive over 0.4-12 keV, with an X-ray CCD camera in the focal plane of a soft X-ray telescope; and a non-focusing Compton-camera type soft gamma-ray detector, sensitive in the 40-600 keV band. The simultaneous broad bandpass, coupled with high spectral resolution, will enable the pursuit of a wide variety of important science themes.Comment: 22 pages, 17 figures, Proceedings of the SPIE Astronomical Instrumentation "Space Telescopes and Instrumentation 2012: Ultraviolet to Gamma Ray