Abstract: A control device that is mounted in a second vehicle which a first vehicle having a following travel function is detachably connected to or loaded on is provided. The control device includes a control unit configured to perform: detecting another vehicle that is within a predetermined range from the second vehicle in a state in which the second vehicle has the first vehicle connected thereto or loaded thereon and of which some or all of a scheduled travel route is the same as some or all of a scheduled travel route of the first vehicle after the first vehicle has been disconnected from the second vehicle; and transmitting following instruction information to the first vehicle and disconnecting the first vehicle from the second vehicle such that the first vehicle travels with the detected other vehicle as a preceding vehicle by the following travel function.

Abstract: A modified polyvinyl alcohol is disclosed, which comprises the following structural units (I) and (II) and has a weight average molecular weight of from 3,000 to 400,000: ##STR1## wherein R.sup.1 represents H or CH.sub.3 ; and M.sup.1 represents H, an alkali metal, ammonium, alkylammonium, or alkanolammonium. The modified polyvinyl alcohol may be sulfonated. The modified polyvinyl alcohol is used as a dispersant such as a drilling fluid additive.

Abstract: A process for forming a gel by gelling an aqueous solution of a water-soluble polymer with a chromium compound as a gelling agent, in which a copolymer of acrylamide, 0.5 to 40% by mole of an unsaturated sulfonic acid or its salt, and optionally an unsaturated carboxylic acid or its salt having an intrinsic viscosity of at least 10 in 1N-NaNO.sub.3 at 30.degree. C., is used as the water-soluble polymer, and which is availably applied to improvement of water-oil ratio in oil production and to civil engineering for preventing leakage of underground water. The formed gel is very stable in a water system containing salts in high concentrations at high temperatures.