Abstract: A Ni--Zn type ferrite has the composition represented by the general formula: Ni.sub.X Zn.sub.1-X Fe.sub.2-Y-Z Mn.sub.Y Zr.sub.Z O.sub.4 (0.55.ltoreq.X.ltoreq.0.80, 0.001.ltoreq.Y.ltoreq.0.20, 0.001.ltoreq.Z.ltoreq.0.04). The Ni--Zn type ferrite is formed with the step described below. A raw powder is first mixed for 64 hours and then fired at 850.degree. C. in an oxygen atmosphere for two hours. Next, the fired powder is crushed and then the crushed powder is again mixed. Then, a binder is added to the resulting powder, which is then press-formed under a pressure of 2.5 ton/cm.sup.2, and the press-formed powder is sintered at 1350.degree. C. for 5 hours in an oxygen atmosphere.

Abstract: A Ni--Zn base ferrite is provided with a relatively small dielectric loss (tan.delta.(.epsilon.)) of the order of 10.sup.-3. Its saturation magnetization (4.pi.Ms) is relatively still high. A Ni--Zn base ferrite having a small dielectric loss (of the order of 10.sup.-3) can be obtained by proportioning raw materials to give a finished composition range of Ni.sub.X Zn.sub.1-X Fe.sub.2-Y-Z Mn.sub.Y M.sub.Z O.sub.4 where M: Ge and/or Sn, 0.55.ltoreq.X.ltoreq.1.00, 0.001.ltoreq.Y.ltoreq.0.36, and 0.002.ltoreq.Z.ltoreq.0.36, by calcination.

Abstract: An airship yaw line tractor comprising: a yaw line connector for holding and releasing the yaw line of the airship through remote control; a winch for winding and unwinding a cable connected to the yaw line connector; and a control unit for automatically controlling the tensile force of the cable extending from the winch to the yaw line connector and automatically releasing the yaw line held by the yaw line connector in an emergency.

Abstract: A novel low thermal expansion cast alloy is provided. The alloy consists of, by percents by weight, 0.02 to 0.25% of C, 30.5 to 33.3% of Ni, 4.0 to 6.0% of Co, 0.005 to 0.70% of Mn, 0.005-0.50% of Si and the balance substantially of Fe, with the proviso that % C.gtoreq.3.0285-0.0936 x % Ni (% C and % Ni are weight % of C and Ni). By such composition, micro-segregation of Ni can be reduced and the Ni content range showing the low thermal expansion coefficient can be broadened to an extent of substantially enabling mass production by a casting process in place of the conventional forging or rolling process. The average thermal expansion coefficient at the temperature range from - 50 to 120.degree. C. of the cast alloy is not more than 1.5.times.10.sup.-6 /.degree.C.