Abstract: A polycrystalline bulk body of this invention has uniformity in superconducting properties, in comparison to a polycrystalline bulk body including crystal grains each constituted by (Ba1-xKx)Fe2As2. A polycrystalline bulk body (1) of this invention includes crystal grains each constituted by an iron-based compound (10) expressed by chemical formula AA?Fe4As4, where A is Ca and A? is K, the iron-based compound (10) having a crystal structure in which AFe2As2 layers (16) and A?Fe2As2 layers (17) are alternately stacked.

Abstract: A heat exchanger having excellent heat exchanging performance is obtainable by a simple production technique and at a low cost. This is achieved by providing a fin member and by increasing heat conductivity between the fin member and a meandering pipe body. Further, the heat exchanger is made compact for high degrees of layout freedom, enabling the heat exchanger to be installed in a tight space. Engagement grooves (8) are provided in both end surfaces (6, 7), which are opposite to each other, of a fin member (5) in which fins (4) are parallel arranged. Straight pipe sections (2) are parallelly arranged, with gaps (16)in between, in the engagement grooves (8) of the fin member (5). The straight pipe sections (2)a are connected at bent sections (3). A pair of meandering sections (11, 12) is arranged opposite to each other with an insertion gap (17) of the fin member (5) in between.

Abstract: A heat exchanger having excellent heat exchanging performance is obtainable by a simple production technique and at a low cost. This is achieved by providing a fin member and by increasing heat conductivity between the fin member and a meandering pipe body. Further, the heat exchanger is made compact for high degrees of layout freedom, enabling the heat exchanger to be installed in a tight space. Engagement grooves are provided in both end surfaces, which are opposite to each other, of a fin member in which fins are parallel arranged. Straight pipe sections are parallelly arranged, with gaps in between, in the engagement grooves of the fin member. The straight pipe sections a are connected at bent sections. A pair of meandering sections is arranged opposite to each other with an insertion gap of the fin member in between. On of the meandering sections and the other meandering section are connected by a connection pipe to form a meandering pipe main body.

Abstract: A high-pressure fuel injection pipe having connecting head portion is provided which is capable of eliminating a fear of the occurrence of cavitation erosion of the inner surface of the connecting head portion and a fatigue failure of the same head portion by having a contour of a cross section of an annular pocket occurring in an inner part of the connecting head portion during a head portion processing operation extend shallowly and gently. This fuel injection pipe has at a connecting end portion of a thick-walled steel pipe having a relatively small diameter, including a seat surface, an annular flange formed so that the flange is axially spaced from the seat surface, and a conical surface connected to the seat surface, extending therefrom to the annular flange and tapering off to a free end of the connecting head portion, wherein the conical surface is provided at a part thereof with an annular, shallow, cross-sectionally curved recess.

Abstract: A high-pressure fuel injection pipe having connecting head portion is provided which is capable of eliminating a fear of the occurrence of cavitation erosion of the inner surface of the connecting head portion and a fatigue failure of the same head portion by having a contour of a cross section of an annular pocket occurring in an inner part of the connecting head portion during a head portion processing operation extend shallowly and gently. This fuel injection pipe has at a connecting end portion of a thick-walled steel pipe having a relatively small diameter, including a seat surface, an annular flange formed so that the flange is axially spaced from the seat surface, and a conical surface connected to the seat surface, extending therefrom to the annular flange and tapering off to a free end of the connecting head portion, wherein the conical surface is provided at a part thereof with an annular, shallow, cross-sectionally curved recess.