Knowledge of the airflow patterns and methane distributions at a continuous miner face under different ventilation conditions can minimize the risks of explosion and injury to miners by accurately forecasting potentia...Knowledge of the airflow patterns and methane distributions at a continuous miner face under different ventilation conditions can minimize the risks of explosion and injury to miners by accurately forecasting potentially hazardous face methane levels. This study focused on validating a series of computational fluid dynamics(CFD) models using full-scale ventilation gallery data that assessed how curtain setback distance impacted airflow patterns and methane distributions at an empty mining face(no continuous miner present). Three CFD models of face ventilation with 4.6, 7.6 and 10.7 m(15, 25, and 35 ft) blowing curtain setback distances were constructed and validated with experimental data collected in a full-scale ventilation test facility. Good agreement was obtained between the CFD simulation results and this data.Detailed airflow and methane distribution information are provided. Elevated methane zones at the working faces were identified with the three curtain setback distances. Visualization of the setback distance impact on the face methane distribution was performed by utilizing the post-processing capability of the CFD software.展开更多
Pulsed electrohydrodynamic printing (EHDP) is used to fabricate conductive silver patterns with micrometer resolution. The silver ink pendant experiences swelling, pulsation, and ejection under an applied pulse volt...Pulsed electrohydrodynamic printing (EHDP) is used to fabricate conductive silver patterns with micrometer resolution. The silver ink pendant experiences swelling, pulsation, and ejection under an applied pulse voltage of 20 Hz. The droplet deposi- tion frequency is equal to the applied voltage frequency so that the EHDP can deposit silver ink on demand. A low applied voltage favors uniform and non-scattering silver patterns while a high applied voltage results in ink scattering. Discrete drop- lets with 45-55 gm in diameter and continuous tracks with 60 gm in width are generated by using a ll0-i.tm-cailber nozzle. The feature size of deposited patterns is about half of the nozzle caliber, and a finer resolution can be achieved with the intro- duction of smaller nozzle calibers. Furthermore, the appropriate curing condition is investigated for sufficient combustion of ink solvent. The minimum resistivity of 3.3 gf~ cm is demonstrated for a continuous track cured at 200~C for 10 min. Eventu- ally, several passive electrical components, such as coated resistors, interdigitated capacitors (6 pF), and spiral inductors (0.6 gH), are successfully fabricated.展开更多
文摘Knowledge of the airflow patterns and methane distributions at a continuous miner face under different ventilation conditions can minimize the risks of explosion and injury to miners by accurately forecasting potentially hazardous face methane levels. This study focused on validating a series of computational fluid dynamics(CFD) models using full-scale ventilation gallery data that assessed how curtain setback distance impacted airflow patterns and methane distributions at an empty mining face(no continuous miner present). Three CFD models of face ventilation with 4.6, 7.6 and 10.7 m(15, 25, and 35 ft) blowing curtain setback distances were constructed and validated with experimental data collected in a full-scale ventilation test facility. Good agreement was obtained between the CFD simulation results and this data.Detailed airflow and methane distribution information are provided. Elevated methane zones at the working faces were identified with the three curtain setback distances. Visualization of the setback distance impact on the face methane distribution was performed by utilizing the post-processing capability of the CFD software.
基金supported by the National Natural Science Foundation of China (Grant No. 51035002)the Key Project of Chinese Ministry of Edu-cation (Grant No. 708055)the Fundamental Research Funds for the Central Universities (Grant No. 2010121039)
文摘Pulsed electrohydrodynamic printing (EHDP) is used to fabricate conductive silver patterns with micrometer resolution. The silver ink pendant experiences swelling, pulsation, and ejection under an applied pulse voltage of 20 Hz. The droplet deposi- tion frequency is equal to the applied voltage frequency so that the EHDP can deposit silver ink on demand. A low applied voltage favors uniform and non-scattering silver patterns while a high applied voltage results in ink scattering. Discrete drop- lets with 45-55 gm in diameter and continuous tracks with 60 gm in width are generated by using a ll0-i.tm-cailber nozzle. The feature size of deposited patterns is about half of the nozzle caliber, and a finer resolution can be achieved with the intro- duction of smaller nozzle calibers. Furthermore, the appropriate curing condition is investigated for sufficient combustion of ink solvent. The minimum resistivity of 3.3 gf~ cm is demonstrated for a continuous track cured at 200~C for 10 min. Eventu- ally, several passive electrical components, such as coated resistors, interdigitated capacitors (6 pF), and spiral inductors (0.6 gH), are successfully fabricated.