Abstract: A fuel control system for a gas turbine engine reheat system has a plurality of fuel metering devices for controlling fuel flow to respective ones of the reheat burners, and a plurality of throttle valves in series with the respective metering devices. One of the throttle valves regulates a pressure difference across its associated metering device and the remaining throttle valves maintain the pressure difference across their respective metering devices equal to that controlled by the aforesaid one throttle valve. The system may include a fuel supply valve which is responsive to a pressure signal controlled by two of the metering devices so that fuel supply from a pump is provided only when both of the two metering devices are open. The pump may include a delivery pressure regulating arrangement responsive to pump delivery pressure and to the highest of the pressures downstream of the metering devices, for regulating pump delivery pressure so as to maintain the metering pressure differences constant.

Abstract: The present invention provides nucleic acid molecules containing nucleotide sequences encoding helminth aminopeptidase enzymes, and antigenic fragments and functionally-equivalent variants thereof, their use in the preparation of vaccines, for use against helminth parasites, and synthetic polypeptides encoded by them.

Abstract: A fuel control system as claimed in claim 1 wherein, the pressure raising valve includes: a pressure raising valve member exposed to fuel pressure within a reference chamber, an inlet to which fuel at supply pressure is supplied, wherein the pressure raising valve member is movable against a force due to pressure within the reference chamber by means of fuel at supply pressure, an outlet through which fuel at delivery pressure is supplied to the engine, and feedback means for permitting fuel at delivery pressure to flow to the reference chamber. There is also disclosed a pressure raising valve for use in such a system.

Abstract: A fuel system for a gas turbine engine having a main burner fuel supply line and a pilot burner fuel supply line, a high pressure pump supplying fuel to the main and pilot burner supply lines in use, a throttle valve controlling the flow of fuel in the main burner supply line, a metering valve controlling the flow of fuel in the pilot burner supply line, and a pressure raising valve between the pilot burners and the metering valve, the pressure raising valve serving to maintain the upstream fuel pressure to a pre-determined amount in excess of the pressure of fuel supplied from the throttle valve to the main burners.

Abstract: A fuel control system as claimed in claim 1 wherein, the pressure raising valve includes:

Abstract: A fuel system for a gas turbine engine having a main burner fuel supply line and a pilot burner fuel supply line, a high pressure pump supplying fuel to the main and pilot burner supply lines in use, a throttle valve controlling the flow of fuel in the main burner supply line, a metering valve controlling the flow of fuel in the pilot burner supply line, and a pressure raising valve between the pilot burners and the metering valve, the pressure raising valve serving to maintain the upstream fuel pressure to a pre-determined amount in excess of the pressure of fuel supplied from the throttle valve to the main burners.

Abstract: A control system is provided for use in controlling fuel supply to at least two sets of burners of an engine. The control system comprises two or more fuel pumps, each of the pumps being driven, in use, by a respective variable-speed motor. A control arrangement is provided for controlling the speed of the motors so as to regulate the rate of flow of fuel to each of the sets of burners.

Abstract: An apparatus for determining the statues of a shut-off valve arrangement forming part of a fuelling system of an engine comprises a metering valve arrangement comprising a metering valve member for regulating fuel flow from a pump to the engine and a position sensor for monitoring the position of the metering valve member. The shut-off valve arrangement is operable between open and closed positions and the metering valve arrangement is operable between a maximum flow position, in which the flow of fuel through the metering valve arrangement to the shut-off valve arrangement is a maximum, and a minimum flow position in which the flow of fuel through the metering valve arrangement to the shut-off valve arrangement is a minimum. The position of the metering valve member is controlled by controlling fuel pressure acting on the metering valve member.

Abstract: The present invention provides nucleic acid molecules containing nucleotide sequences encoding helminth aminopeptidase enzymes, and antigenic fragments and functionally-equivalent variants thereof, their use in the preparation of vaccines, for use against helminth parasites, and synthetic polypetides encoded by them.

Abstract: The present invention provides nucleic acid molecules containing nucleotide sequences encoding helminth aminopeptidase enzymes, and antigenic fragments and functionally-equivalent variants thereof, their use in the preparation of vaccines for use against helminth parasites, and synthetic polypeptides encoded by them.

Abstract: A fuel control system for an engine, laving a pup operable to supply an output flow of fuel, engine fuel flow regulation means operable to regulate the pump output flow, and pump control means operable to vary an output rate of the pump according to an operational condition of the engine fuel flow regulation means.

Abstract: A fuel system comprising a low pressure fuel pump having an outlet which is connected to an inlet of a high pressure pump arranged, in use, to supply fuel to an engine. The fuel system her comprises at least one actuator controlled by a servo-valve, wherein the servo-valve has a high pressure connection connected to the high pressure side of the high pressure pump and a low pressure connection connected upstream of the outlet of the low pressure pump.

Abstract: A fuel control system for an engine, having a pump operable to supply an output flow of fuel, engine fuel flow regulation means operable to regulate the pump output flow, and pump control means operable to vary an output rate of the pump according to an operational condition of the engine fuel flow regulation means.

Abstract: A fuel control system for an engine, having a pump operable to supply an output flow of fuel, engine fuel flow regulation means operable to regulate the pump output flow, and pump control means operable to vary an output rate of the pump according to an operational condition of the engine fuel flow regulation means.

Abstract: A control system is provided for use in controlling fuel supply to at least two sets of burners of an engine. The control system comprises two or more fuel pumps, each of the pumps being driven, in use, by a respective variable-speed motor. A control arrangement is provided for controlling the speed of the motors so as to regulate the rate of flow of fuel to each of the sets of burners.

Abstract: An apparatus for determining the statues of a shut-off valve arrangement forming part of a fuelling system of an engine comprises a metering valve arrangement comprising a metering valve member for regulating fuel flow from a pump to the engine and a position sensor for monitoring the position of the metering valve member. The shut-off valve arrangement is operable between open and closed positions and the metering valve arrangement is operable between a maximum flow position, in which the flow of fuel through the metering valve arrangement to the shut-off valve arrangement is a maximum, and a minimum flow position in which the flow of fuel through the metering valve arrangement to the shut-off valve arrangement is a minimum. The position of the metering valve member is controlled by controlling fuel pressure acting on the metering valve member.

Abstract: A fluid flow system for supplying fuel to an engine, the system including a fluid flow valve having a valve element movable alternatively to a first operative position in which a relatively low fluid flow rate is permitted through the valve, for achieving a normal gradual shut-off of fuel supply, and a second operative position in which a relatively high fluid flow rate is permitted through the valve, for achieving a rapid emergency shut-off of fuel supply. Also disclosed is a fluid flow valve for use in the system. The invention has application in aircraft gas turbine engines.

Abstract: The present invention provides nucleic acid molecules containing nucleotide sequences encoding helminth aminopeptidase enzymes, and antigenic fragments and functionally-equivalent variants thereof, their use in the preparation of vaccines for use against helminth parasites, and synthetic polypeptides encoded by them.

Abstract: Disclosed is a flow sensor comprising a cylinder and a piston movable within the cylinder and dividing the cylinder into first and second chambers. The first chamber communicates with an inlet and the cylinder has an orifice which cooperates with the piston to define an outlet from the first chamber. The area of the orifice varies with the position of the piston within the cylinder. The apparatus operates to vary the pressure in the second chamber so as to move the piston in response to fluid flow to maintain a substantially constant pressure drop between the inlet and outlet, each unique axial position of the piston within the cylinder indicating a particular flow rate. A transducer senses the position of the piston and thus the direction and rate of flow.

Abstract: A protein complex H45 is described whose components are glycoproteins isolable from the intestinal microvillus plasma membrane of a parasitic nematode, such as Haemonchus contortus. This complex includes protein H4.5, which has an apparent molecular weight on sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) of about 45 Kd under reducing conditions and about 90 Kd under non-reducing conditions, as well as proteins H4.9 and H5.3 which have apparent molecular weights on SDS-PAGE of about 49 Kd and about 53 Kd respectively both under reducing and under non reducing conditions. Protein complex H45 and its components can be used, optionally together with the already known protein doublet H110D, to form a vaccine which can reduce the weight of worms in sheep infected with Haemonchus contortus by an average of 91% and the parasite egg production by an average of 94.5%.