Abstract: The present invention is related to novel 20-sulfonylamidine derivatives of camptothecin (1), method of synthesizing the same, and use thereof as an antitumor agent, for examples an antitumor agent for treating nasopharyngeal, lung, breast or prostate cancer.

Abstract: The present invention is related to novel 20-sulfonylamidine derivatives of camptothecin (1), method of synthesizing the same, and use thereof as an antitumor agent, for examples an antitumor agent for treating nasopharyngeal, lung, breast or prostate cancer.

Abstract: A control system for controlling the load of an AC motor/generator of secondary AC excitation type connected to a power system in parallel to at least a synchronous machine. The AC motor/generator has the secondary excitation winding thereof controlled in the amount of excitation so as to generate an output in accordance with an external output command. In the case of variation of power flow between the power system and the synchronous machine, the output command is corrected in accordance with the variation, and the amount of the secondary excitation is controlled by the corrected output command, whereby the variation of power flow between the power system and the synchronous machine is absorbed by the AC motor/generator thereby to prevent the synchronous machine from stepping out.

Abstract: A compound of the formula ##STR1## wherein Y represents a halogen atom, a lower alkyl group, a lower alkoxy group or a trifluoromethyl group and R represents a lower alkyl group. This compound can be produced by reacting a compound of the formula ##STR2## or a reactive derivative thereof with an aniline derivative of the formula ##STR3## and is useful as a herbicide.

Abstract: A composition of flake graphite, binder clay and a refractory material is extruded from an auger machine into a mold to form a cylindrical graphitic casting nozzle brick. The mold includes a coaxial core terminating short of an extrusion die of the auger machine, so that the graphitic casting nozzle brick as extruded has a longitudinal bore with one end closed, with transverse holes being subsequently defined through the nozzle brick across the bore adjacent to the closed end. As an alternative, a coaxial core may be connected to an extrusion screw of the auger machine to define an axial through bore in the casting nozzle brick as the latter is extruded.

Abstract: A field control apparatus for a generator having a field winding comprises a terminal voltage control unit for controlling a field current of the generator in accordance with a difference between a terminal voltage signal of the generator and a reference voltage signal, which control unit has at least one of a line drop compensation function, an under-excitation limitation function, an over-excitation limitation function, a power factor regulation function, an armature winding over-current compensation function and a cross-current compensation function. The field control apparatus includes a detector as a common signal source for detecting active power and reactive power components at an output terminal of the generator and means responsive to the output of the detector for performing scalar operation in accordance with a function of the added compensation/control function described above.

Abstract: Disclosed is an apparatus for carrying out normal stop of a synchronous generator in an advantageous manner without use of a field breaker. The apparatus comprises a six-phase thyristor converter for controlling field excitation of the synchronous generator in dependence upon terminal voltage thereof, which converter exhibits not only a forward conversion function (power rectifier) but also backward conversion function (power inverter). When a generator operation stop command is produced, the operation of the converter in power rectifier mode is changed over to power inverter mode.

Abstract: An apparatus for protecting a synchronous machine from a field overvoltage is disclosed. The apparatus comprises a field excitation control circuit which is impressed with the armature voltage of the synchronous machine so as to provide a DC power supply for producing a DC output to excite the field winding of the synchronous machine, a first discharge circuit which is adapted to discharge the stored energy of the field winding when the synchronous machine is to be tripped under predetermined conditions, and a second discharge circuit for reducing the field voltage by allowing a field current to flow therethrough in response to generation of an overvoltage whose absolute value is higher than a predetermined level, across the field winding.

Abstract: In a control system for a hydroelectric power station system including upper and lower water reservoirs connected through a water channel, an intermediate water reservoir having a smaller storage capacity than those of the upper and lower reservoirs and provided on the water channel in cascade with the upper and lower reservoirs, and two power stations disposed between the upper and intermediate reservoirs and between the intermediate and lower reservoirs, respectively, the control system is arranged such that the water level of the intermediate reservoir is detected continuously and the detected value of the water level is used to correct the load instructions which are applied to the power stations for controlling outputs of the power stations whereby the water level of the intermediate reservoir is maintained substantially constant, while the power generation of the power stations is controlled so as to satisfactorily meet with the load instruction applied to the power system.

Abstract: The field excitation flux of the synchronous generator is controlled in response to the summing rotor angle signal of a predetermined set signal and of a rotor angle signal representing a phase difference between the voltage equivalent to an infinite bus voltage and the output voltage from the pilot generator provided on the same rotating shaft as the synchronous generator.