Abstract: An electric power converter having an AC input and AC output, and comprising a power rectifier and a power inverter having a DC three-wire circuit, wherein means for detecting a current or a voltage is connected between the AC power source and ground. When a current or a voltage is detected, an alarm is produced or the apparatus is halted. This makes it possible to judge whether the power inverter is in a state capable of producing an excessively large potential.

Abstract: A sine wave input converter provided with a phase sequence computation unit which inputs two line voltages or two phase voltages of the three phase ac power supply, computes the phase of a sine wave voltage of one of these two inputs, and determines on the basis of computation using these two input voltages and the phase whether the phase sequence is positive or antiphase, which is determined depending on whether the result of computation assumes a constant value, or becomes a sine wave oscillating between positive and negative values. Power supply interruption can be determined from the same computation result.

Abstract: In a power converter apparatus having a three-phase AC power supply connecting unit, a positive side capacitor, a negative side capacitor, first-phase and third-phase converting circuits each including switching elements connected in series, and a common phase for connecting a neutral polarity to a second phase, there are provided a common phase converting circuit including two switching elements connected in series between positive and negative polarities, a change detector for detecting a temporal change of an electric current flowing through the common phase, and a duty controller for changing the on-off duty of the switching elements in the common phase converting circuit on the basis of the temporal change.

Abstract: A polyamide comprising a solution of (i) an aliphatic polyamide and/or an aliphatic aromatic poly amide dissolved in (ii) N-methyl-2-pyrrolidone and containing (iii) calcium chloride, the ratio between the polyamide (i) and the N-methyl-2-pyrrolidone (ii) in the solution composition being 3 to 25% by weight of the polyamide (i)to 97 to 75% by weight of the N-methyl-2-pyrrolidone, (ii) with the solution also containing calcium chloride (iii) in an amount of 5 to 60 parts by weight based on 100 parts by weight of the polyamide (i) which can be precipitated in a precipitant consisting essentially of water while stirring the precipitant to provide fibrids, which then can be mixed with fibers or natural pulp and formed into synthetic paper.

Abstract: In a uninterruptible power supply in which a plurality of inverters are operated in parallel, a current control loop is provided which responds to the magnitude of an output current of each inverter brought into parallel running to change a command value for a voltage waveform control circuit associated with each inverter, and the gain of the current control loop is made to be variable, whereby currents shared by the inverters can be set desirably to effectively suppress a cross current flowing between the inverters upon establishment of parallel running.

Abstract: A method for preparing a dialkylnaphthalene in one step by contacting an dialkylbenzene compound with a solid catalyst in a gas or liquid phase in the presence of hydrogen, using a catalyst having composition (I) or (II) below:(1)(M.sup.1).sub.a.(M.sup.2).sub.b.(SiO.sub.2.XAl.sub.2 O.sub.3).(Al.sub.2 O.sub.3).sub.c (I)(2) Mixture of II-(i) and II-(ii):(M.sup.3).sub.d.(Al.sub.2 O.sub.3) II-(i)(M.sup.4).sub.e.(SiO.sub.2.XAl.sub.2 O.sub.3) II-(ii)wherein M.sup.1 is a metal selected from the group consisting of metals belonging to group VIII of a periodic table and rhenium;M.sup.2 is a member selected from the group consisting of zinc, gallium, and oxides thereof;M.sup.3 is a metal belonging to group VIII of a periodic table;M.sup.4 is at least one alkali metal; anda, b, c, d, e, and X represent proportions, respectively.

Abstract: In a process for producing an alkenylbenzene by the reaction of an alkylbenzene having 8 or more carbon atoms and a conjugated diolefin, the improvement in which the reaction is performed in the presence of a catalyst obtained by dispersing (a) an alkali metal and (b) potassium carbonate and/or potassium hydroxide in the presence of (c) an aromatic hydrocarbon having at least a substituent with a double bond.

Abstract: A shaped silicon carbide-based ceramic article having an improved mechanical strength is produced at a high efficiency by a process comprising the step of: forming an organic silicone polymer, for example, polycarbosilastyrene copolymer, into a predetermined shape, for example, a filament or film; doping the shaped polymer with a doping material consisting of at least one type of halogen, for example, bromine or iodine, in an amount of 0.01% to 150% based on the weight of the shaped polymer, to render the shaped polymer infusible; and pyrolyzing the infusible shaped polymer into a shaped SiC-based ceramic article at a temperature of 800.degree. C. to 1400.degree. C. in an inert gas atmosphere, optionally the halogen-doped shaped polymer being treated with a basic material, for example, ammonia, before the pyrolyzing step, to make the filament uniformly infusible.

Abstract: A shaped silicon carbide-based ceramic article having an improved mechanical strength is produced at a high efficiency by a process comprising the step of: forming an organic silicon polymer, for example, polycarbosilastyrene copolymer, into a predetermined shape, for example, a filament or film; doping the shaped polymer with a doping material consisting of at least one type of halogen, for example, bromine or iodine, in an amount of 0.01% to 150% based on the weight of the shaped polymer, to render the shaped polymer infusible; and pyrolyzing the infusible shaped polymer into a shaped SiC-based ceramic article at a temperature of 800.degree. C. to 1400.degree. C. in an inert gas atmosphere, optionally the halogen-doped shaped polymer being treated with a basic material, for example, ammonia, before the pyrolyzing step, to make the filament uniformly infusible.

Abstract: A new polycarbosilastyrene copolymer which comprises recurring carbosilane units of the formula I: ##STR1## and recurring silastyrene units of the formula II: ##STR2## and having easy shaping and sintering properties, is produced by ultra-violet ray treatment and/or heat treatment of a polysilastyrene material and is useful for producing a shaped sintered silicon carbide article by shaping the polycarbosilastyrene copolymer to a desired form, by applying an ultra-violet ray treatment or heat treatment to the shaped article, and by sintering the resultant corss-linked, non-fusible shaped article at an elevated temperature.

Abstract: A polycarbosilastyrene copolymer which comprises recurring carbosilane units of the formula I: ##STR1## and recurring silastyrene units of the formula II: ##STR2## is useful for producing a shaped sintered silicon carbide article by shaping the polycarbosilastyrene copolymer to a desired form, by applying an ultra-violet ray treatment or heat treatment to the shaped article, and by sintering the resultant cross-linked, non-fusible shaped article at an elevated temperature.

Abstract: A fiber-reinforced composite material comprising a resin and 20 to 90% by weight, based on the composite material, of reinforcing fibers, said reinforcing fibers comprising fibers of a wholly aromatic polyamide consisting essentially of(1) structural units of the formula ##STR1## and (2) structural units of the formula ##STR2## and/or structural units of the formula ##STR3## wherein X represents a halogen atom and n is an integer of from 1 to 3.

Abstract: There is provided an aromatic polyamide composition, which comprises (a) a polyamide, the recurring structural units of which are substantially totally aromatic, (b) an organic amide solvent, and (c) one or more salts selected from chlorides and bromides of an alkali metal, an alkaline earth metal or ammonium. The amounts of the polyamide and the organic amide solvent are in the ranges of 30 to 50% and 70 to 50% by weight, respectively, based on the total weight of the polyamide and the organic amide solvent. The amount of the salt is defined by the formulae:in the case where 30.ltoreq.x.ltoreq.33.6, y.gtoreq.10, andin the case where 33.6<x.ltoreq.50, y>2.8x-84wherein "x" is the amount in % by weight of the polyamide based on the total weight of the polyamide and the organic amide solvent, and "y" is the amount in % by mole of the salt based on the polyamide. The polyamide composition is useful for melt-shaping films, fibers and other shaped articles.

Abstract: High modulus shaped articles such as fibers and films, composed of a wholly aromatic copolyamide, are provided. The wholly aromatic copolyamide is comprised of recurring units of the formulae:--NH--AR.sub.1 --NH--CO--Ar.sub.2 --CO-- (A)and--NH--Ar.sub.3 --CO-- (B)wherein Ar.sub.1, Ar.sub.2 and Ar.sub.3 independently stand for divalent groups selected from ##STR1## in which X's independently stand for a group selected from halogeno, alkyl, aralkyl, aromatic, alkoxy, acetyl and cyano, n is 1 to 3 and Y is selected from ##STR2## in which R' stands for an 1-5C alkyl group, and the copolymerization ratio expressed by the molar ratio of the total of Ar.sub.1, Ar.sub.2 and Ar.sub.3 fails within the square hatched region in a triangular coordinate of FIG. 1, and said copolyamide has an intrinsic viscosity of at least 1.5.

Abstract: An aromatic polyamide paper-like sheet having excellent heat- and chemical- resistances and electric insulating properties, comprises an artificial pulp ingredient comprising a number of amorphous pulp particles consisting of an aromatic polyamide material, and a fiber ingredient consisting of a number of short fibers bonded to each other with the amorphous pulp particles, the ratio in weight of the artificial pulp ingredient to the fiber ingredient being in a range of from 1:9 to 9:1 and the aromatic polyamide molecules contained at least in the amorphous pulp particles being cross-linked with a cross-linking agent.

Abstract: A wholly aromatic polyamide fiber non-woven sheet having satisfactory density, impregnating property, heat resistance, and surface evenness, comprises mutually, randomly entangled fibers consisting essentially of a wholly aromatic polyamide having 85 molar % or more of at least one type of recurring units selected from those of the formulae (I) and (II): ##STR1## The non-woven sheet is characterized in that the wholly aromatic polyamide fibers have portions thereof having a flattened cross-sectional profile; the aromatic polyamide fibers are fuse-bonded to each other at least at portions thereof intersecting each other; and the sheet includes pores connected to each other, and having a size at the peak of pore size distribution, of 13 microns or less determined by means of a mercury porosimeter, and no voids isolated from each other, and has a porosity of from 5% to 40% and an air permeability rate of from 0.1 to 10,000 sec/100 ml.

Abstract: An aromatic copolyamide comprising recurring units (A) of the formula (I), (B) of the formula (II) and (C) of the formula (III): ##STR1## wherein in (I), (II) and (III), Ar.sub.1 is phenylene, naphthylene or biphenylene radicals, each having two valence bonds oriented meta; Ar.sub.2 is phenylene, naphthylene or biphenylene radicals, each having two valence bonds oriented coaxially or in parallel to each other and radicals of the formula (IV): ##STR2## wherein Y.sub.1 and Y.sub.2 are independently ##STR3## and; X.sub.1, X.sub.2, X.sub.3, X.sub.4, X.sub.5 and X.sub.6 respectively are independently --NH-- and --CO-- radicals, connected to each other to form an amide bond (--NHCO-- or --CHNH--), and the molar proportions of said recurring units (A), (B), and (C) fall within a quadrilateral defined by the co-ordinates P, Q, R and S or on a twice-turned line defined by the co-ordinates Q, R, S and P:P (A 50, B 5, C 45)Q (A 5, B 5, C 90)R (A 5, B 40, C 55) andS (A 50, B 15, C 35)on a triangular composition diagram.

Abstract: A papery product consisting essentially of a fibrous web, at least part of said web being made of a wholly aromatic polyamide fiber having a readily soluble skin layer and a sparingly soluble or insoluble core layer, and pressure and heat being applied to said web. Said product is excellent in its mechanical and heat-resisting properties.

Abstract: An aromatic and/or heterocyclic polyamide-amide type polar solvent composition is prepared by prepolymerizing an aromatic or heterocyclic diamine with an aromatic or heterocyclic or heterocyclic dicarboxylic acid chloride in a smaller molar equivalent than that of the diamine to prepare a prepolymer solution having a solution viscosity of 20 poise or less; by removing a by-product, hydrochloric acid, from the resultant prepolymer solution by neutralizing it with ammonia to such an extent that the pH of a mixture of 10 g of the neutralized mixture with 200 ml of water becomes 3.7 to 8.0; by high polymerizing the prepolymer with an additional amount of aromatic or heterocyclic dicarboxylic acid chloride, and; finally, by converting the entire amount of hydrochloric acid and 10 to 70% NH.sub.

Abstract: An aromatic copolyamide comprising recurring units (A) of the formula (I), (B) of the formula (II) and (C) of the formula (III): ##STR1## wherein in (I), (II) and (III) Ar.sub.1 is phenylene, naphthylene or biphenylene radicals, each having two valence bonds oriented meta; Ar.sub.2 is phenylene, naphthylene or biphenylene radicals, each having two valence bonds oriented coaxially or in parallel to each other and radicals of the formula (IV): ##STR2## wherein Y.sub.1 and Y.sub.2 are independently; ##STR3## and; X.sub.1, X.sub.2, X.sub.3, X.sub.4, X.sub.5 and X.sub.6 respectively are independently --NH-- and --CO-- radicals, connected to each other to form an amide bond (--NHCO-- or --CHNH--), and the molar proportions of said recurring units (A), (B) and (C) fall within a quadrilateral defined by the co-ordinates P, Q, R and S or on a twice-turned line defined by the co-ordinates Q,R,S, and P:P (A 50, B 5, C 45)Q (A 5, B 5, C 90)R (A 5, B 40, C 55) andS (A 50, B 15, C 35)on a triangular composition diagram.