Abstract: Two catalytic converters are disposed in series midway in an engine exhaust passage, and a by-pass valve selectively introduces exhaust into the upstream converter and a by-pass passage which by-passes the converter. When the catalyst temperature of the upstream catalytic converter exceeds a threshold value A, exhaust is routed to the by-pass passage. The catalyst temperature in the state when exhaust is routed to the upstream catalytic converter under steady state engine running conditions is stored as a convergence temperature depending on the engine running conditions.When exhaust is routed to the by-pass passage, exhaust is re-introduced into the upstream converter only when both the catalyst temperature and the convergence temperature corresponding to the running conditions at that time are less than a threshold value B which is less than the threshold value A.In this way, hunting of the by-pass valve operation is prevented.

Abstract: The delay of fuel flow in an intake passage of an engine is divided into two categories, namely a short-term delay having a relatively fast time constant and a long-term delay having a relatively slow time constant. The corrections for each delay are stored separately depending on the engine running conditions. A mechanism is provided for estimating the particle diameter of the fuel spray, and either the long-term delay correction is modified so that it increases or the short-term delay correction is modified so that it decreases as the particles of fuel spray become smaller. The basic fuel injection amount during transient engine running conditions is corrected by applying the delay flow correction thereby modified, and error in the air-fuel ratio during transient conditions due to atomization of fuel particles is prevented.

Abstract: A leak detecting method for vessels in which a gas of a given pressure is mixed with sulfur hexafluoride of a given partial pressure and the mixture is introduced into a vessel, and a gas in the vicinity of an outer peripheral surface of the vessel is sucked by a gas sucking mechanism.According to one form of the invention, the sucked air is introduced into an absorption cell and a P(16)-line laser light of a carbon dioxide gas laser is introduced into the absorption cell. Then, the presence or absence of absorption of the P(16)-line laser light within the absorption cell is detected in accordance with a change in the transmitted light intensity of the P(16)-line laser light and the presence or absence of a leak in the pressure vessel is discriminated in accordance with a result of the detection.

Abstract: A method for producing snow comprises producing a group of waterdrops by jetting water or water together with compressed air from a nozzle into the atmosphere of 0.degree. C. or less, and freezing the group of waterdrops jetted by applying ultrasonic waves to the group of waterdrops. An apparatus for producing snow comprises a jetting apparatus for producing a group of waterdrops by jetting water or water together with compressed air into the atmosphere of 0.degree. C. or less, and an ultrasonic wave generator for applying ultrasonic waves to the group of waterdrops jetted by the jetting apparatus.

Abstract: A method and apparatus for detecting a defective portion on the outer surface not exposed of a pipe, which comprises: heating or cooling a pipe, the outer surface of which is not exposed, from the side of the inner surface thereof so that a difference in temperature is produced between a portion of the inner surface of the pipe corresponding to an accumulation of foreign matters or a thinner portion as a defective portion on the outer surface not exposed of the pipe and a portion of the inner surface of the pipe corresponding to a normal portion of the outer surface of the pipe; then shooting the inner surface of the pipe by means of a thermal imaging system while the difference in temperature still remains on the inner surface of the pipe to obtain a thermal image of the difference in temperature; and detecting the accumulation of foreign matters or the thinner portion as the defective portion on the outer surface of the pipe by means of the thus obtained thermal image.

Abstract: A burner skeleton made of a composition including calcium aluminate and a silica compound. The calcium aluminate contains 15 to 40 wt % of lime, 35 to 80 wt % of alumina and 0.3 to 20 wt % of iron oxide. The composition may include titanium oxide.

Abstract: There is disclosed a fuel supply system having a fuel delivery pipe for distributing fuels to injectors of cylinders. This system further includes an inner pipe fixedly inserted into the delivery pipe to constitute part of a fuel passageway, the inner pipe having a length approximate to the delivery pipe. Fuel feed and feedback pipes close to each other are connected to a proximal portion of the fuel passageway consisting of the delivery pipe and the inner pipe.

Abstract: A method and an apparatus for detecting a defective portion on the inner surface of a pipe, the outer surface of which is exposed, includes: heating or cooling a pipe, the outer surface of which is exposed, from the side of the outer surface thereof so that a difference in temperature is produced between a portion of the outer surface of the pipe corresponding to an accumulation of foreign matters or a thinner portion as a defective portion on the inner surface thereof, and a portion of the outer surface of the pipe corresponding to a normal portion of the inner surface thereof; then shooting the outer surface of the pipe by means of a thermal imaging system while the above-mentioned difference in temperature still remains on the outer surface of the pipe to obtain a thermal image of the difference in temperature; and detecting the accumulation of foreign matters or the thinner portion as the defective portion of the inner surface of the pipe by means of the thus obtained thermal image.

Abstract: A burner skeleton made of a composition including calcium aluminate and a silica compound. The calcium aluminate contains 15 to 40 wt % of lime, 35 to 80 wt % of alumina and 0.3 to 20 wt % of iron oxide. The composition may include titanium oxide.

Abstract: A gouging wire electrode comprising a metal shell, and a powdery or particulate filler section packed into the metal shell, the composition of the filler section comprising 80-95% by weight of carbon and 5-20% by weight of thermosetting resin binder, the bulk density of the filler section being 1.2-1.7 g/cm.sup.3 and the cross-sectional area of the filler section being 60-90% of the total cross-sectional area. It produces stabilized arcs during electric discharge and is consumed slowly and can replace the conventional carbon electrode.

Abstract: A successively joinable carbon electrode for use in gouging or blasting metallic articles comprises a copper coated electrode body having one end formed into a coaxial connecting projection and the other end formed with a coaxial tapered socket for receiving the connecting projection of another carbon electrode of identical construction. The connecting projection consists of a tapered stem portion adjacent the electrode body and a cylindrical portion on one side of the stem portion opposite to the electrode body such that the projection of one carbon electrode can tightly be fitted into the socket of another carbon electrode with the copper layer on such one carbon electrode electrically connected to the copper layer on such another carbon electrode.