Simulation and Measurements of Small Arms Blast Wave Overpressure in the Process of Designing a Silencer
Abstract Simulation and measurements of muzzle blast overpressure and its physical manifestations are studied in this paper. The use of a silencer can have a great influence on the overpressure intensity. A silencer is regarded as an acoustic transducer and a waveguide. Wave equations for an acoustic dotted source of directed effect are used for physical interpretation of overpressure as an acoustic phenomenon. Decomposition approach has proven to be suitable to describe the formation of the output wave of the wave transducer. Electroacoustic analogies are used for simulations. A measurement chain was used to compare the simulation results with the experimental ones.
A Method for Monitoring the Underground Mining Position Based on the Blasting Source Location
Abstract Some small and medium-sized coal mines are mining beyond their mining boundary driven by profit. The illegal activities cause many mine disasters but effective supervision is very hard to achieve, especially for underground coal mining. Nowadays, artificial blasting operation is widely used in tunneling or mining in small and medium-sized coal mines. A method for monitoring the underground mining position by monitoring the blasting source position is firstly introduced in this paper. The blasting vibration waves are picked up by the detectors and dealt by the signal acquisition sub-station, and then sent to the principal computer. The blasting source is located by the principal computer and displayed in the mine’s electronic map. The blasting source position is located in 10 seconds after the first P wave reaching the detector, whose error is registered within 20 meters by field-proven method. Auto-monitoring of the underground mining position in real-time is solved better and management level is improved using this method.
Euthanasia — again: “Letting die” is not in the patient's best interests: a case for active euthanasia
Recent discussions in the Journal on the subject of euthanasia have relied on intuitive appeals to distinctions traditionally considered to be morally relevant, such as the distinction between acts and omissions (or killing and letting die), or ordinary and extraordinary means of treatment. These discussions remained inconclusive. However, the question of euthanasia no longer remains inconclusive if one adopts the perspective suggested by the United States President's Commission for the Study of Ethical Problems in Medicine and Biomedical and Behavioral Research and by the World Medical Assembly – that a doctor should act in his or her patient's best interests. From this vantage point, it is argued, there will be instances when active euthanasia is the proper cause of action.