Abstract: A gas leakage detection system includes a flow path, a dual mode valve disposed in the flow path, an ultrasonic measuring section including a pair of ultrasonic transducers, disposed in the flow path upstream from the dual mode valve, a flow rate calculation section for computing a flow rate based on a signal from the ultrasonic measuring section, and a control section for controlling the dual mode valve. The control section closes or opens the dual mode valve instantaneously, and the flow rate calculation section computes a flow rate when the dual mode valve is closed. Thus, gas leakage can be decided substantially without stopping a gas flow when a user is using the gas.

Abstract: A gas type identification system includes: a flow path; an ultrasonic measurement section disposed in the flow path, the ultrasonic measurement section including a pair of ultrasonic transducers; a sound velocity calculation section for calculating a sound velocity of a gas flowing through the flow path based on a signal from the ultrasonic measurement section; a sound velocity memory section for previously storing a predetermined sound velocity; and a comparison section for comparing the sound velocity calculated by the sound velocity calculation section with the predetermined sound velocity previously stored in the sound velocity memory section.

Abstract: An equipment specifying system of the present invention includes: a flow path for supplying gas to a plurality of pieces of equipment; an ultrasonic propagation signal measuring section for measuring a propagation signal based on a time during which an ultrasonic wave propagates across the flow path; a signal pattern generation section for generating a signal pattern based on a change in a propagation signal; a signal pattern storage section for previously storing a plurality of signal patterns respectively corresponding to a plurality of pieces of equipment; a signal pattern comparison section for comparing a signal pattern generated by the signal pattern generation section with a plurality of signal patterns previously stored in the signal pattern storage section; and an equipment specifying section for specifying currently used equipment among a plurality of pieces of equipment, in accordance with the comparison results obtained by the signal pattern comparison section.

Abstract: A vertical bipolar transistor arrangement in which the distance between the emitter and the isolation region is kept within a range determined by the sum of emitter depth and base width (i.e., the thickness of the base in the depth direction). This keeps the carriers given by the emitter from getting trapped inside, thereby preventing the cut-off frequency from dropping.

Abstract: A boron doped amorphous silicon film is formed by CVD under the conditions of a pressure lower than 1 atm and a temperature higher than 200.degree. C. and lower than 400.degree. C. by using at least one of disilane and trisilane, and diborane as source gases. Since the resultant amorphous silicon film can diffuse impurities at a lower temperature than in the case of the polycrystalline silicon film formed by the conventional method, a pn junction much shallower than in the prior art can be formed.

Abstract: A semiconductor device including a polycrystalline silicone resistor which has a resistance of 40 k.OMEGA.-800 k.OMEGA. and which is formed by a polycrystalline silicon film having a specific resistivity of 0.01 .OMEGA..cm-0.1 .OMEGA..cm. The resistor having the above resistance, which has previously been difficult to fabricate, can be fabricated with a high accuracy, so it is very useful for several kinds of semiconductor integrated circuits such as bipolar memory.

Abstract: A vertical bipolar transistor arrangement in which the distance between the emitter and the isolation region is kept within a range determined by the sum of emitter depth and base width (i.e., the thickness of the base in the depth direction). This keeps the carriers given by the emitter from getting trapped inside, thereby preventing the cut-off frequency from dropping.

Abstract: Plastic scraps are subjected to thermal decomposition in the presence of zeolite type catalyst and converted into a liquid hydrocarbon oil.

Abstract: Alumina or aluminum is arranged on, or in the vicinity of, a wafer surface into which an impurity, particularly antimony, is to be diffused, and the impurity is vapor-diffused.The impurity can be diffused in much larger quantities than in a prior art vapor diffusion, and a very low sheet resistance for the diffused layer of antimony can be attained.