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Critical conditions are usually obtained for ignition in a self-heating solid system consisting of two components generating heat independently, one component being inexhaustible and the other exhaustible by either simple first order or autocatalytic reaction. Ignition depends upon whether the exhaustible component can cause a temperature rise in excess of the upper stationary, but unstable, value possible for the inexhaustible component reacting alone. The system provides a theoretical model for some commonly occurring examples of self-heating and ignition in porous solids containing oxidisable oils. It is shown that: (a) the ignition criterion of the model, which involves a nonarbitrary critical temperature increase, has a high degree of physical reality; (b) the model is, in principle, capable of predicting ignition from primary kinetic and thermal data; (c) it is likely to be possible often to make a reliable prediction of critical size for self-ignition in a two-component system at ordinary atmospheric temperatures by a simple extrapolation from small-scale ignition data, obtained at higher temperatures, in the same way as for ignition due to a single reaction. Examination of both adiabatic and non-adiabatic flame theories showed that a 'steady state' exists only under the special condition that a heat sink exists at the initial temperature. For the general case of freely propagating, non-adiabatic flames only a quasi-steady state can be achieved.
Combustion of fossil fuels provides around 88% of total energy supply for modern society, and meanwhile causes many environ mental problems and social problems such as air pollution and energy crisis. Therefore，both at home and abroad are focusing on the research and development of natural gas engine recently. However, the mass production and application of this kind of engine are restricted by some unsolved technical difficulties. This paper explored the injection, combustion and emission processes of diesel/ natural gas and dual fuel engine based on Chemkin II, Fire software and Schlieren method. The experimental study on the mixing process of dual fuel jet was carried out by using high-speed Schlieren method in a constant volume bomb. Based on the Fire software, and then applied to Chemkin II software to analyze the effect of the initial temperature and pressure on the net heat production and combustion emissions. The results show that Dual fuel mechanism is capable of producing different heat production behaviors when varying the initial pressure and temperature CO2 emissions are minimized by changing the initial pressure above or below the atmospheric value. However, CO emissions are peaked when diesel fuel is used. The dual fuel engine minimizes the CO emissions amount caused by diesel fuel. Increasing the initial pressure eliminates dual fuel CO2 combustion emissions. The research of this paper is important to optimize the in cylinder combustion processes of natural gas engine, and have a certain important meaning to guide the development of diesel ignition dual fuel engine.
Cerebral aspergillosis is a severe disease most commonly suspected in immunodeficient patients. The objective of this study is to determine the role of surgery in management of intracranial aspergillosis. We report three cases of immunocompetent patients presenting: posteriror fossa aspergillosis, sphenoidal extended to sellar region aspergillosis and post operative aspergillosis without extracerebral involvement. Microbiology and histological examination were carried out to provide the diagnosis. The patients underwent surgical procedure associated with medical treatment or not. In one case, surgical treatment was efficient. The outcome was good in two cases. Conclusion: Rapid diagnosis of invasive aspergillosis applying radiological and surgical procedures and immediate ignition of antifungal can be life saving.