CN218751390U

CN218751390U - Cruising rescue throwing mechanism and cruising rescue aircraft using ground effect

Info

Publication number: CN218751390U
Application number: CN202223399732.1U
Authority: CN
Inventors: 温张喆; 周嘉伟
Original assignee: North China Electric Power University
Current assignee: North China Electric Power University
Priority date: 2022-12-19
Filing date: 2022-12-19
Publication date: 2023-03-28
Anticipated expiration: 2032-12-19

Abstract

The utility model relates to a but cruising rescue is put in mechanism, is utilized ground effect's rescue aircraft that can cruise, including the rudder frame, install power device, the input device on the rudder frame, power device provides power for putting in the device, put in the device include the gear train be connected with power device, with the rack that the gear train is connected, by lever and the firing pin that the rack drives, with trigger rope, the trigger that is equipped with the life buoy, the automatic hatch door device that are connected of lever are connected. The problem that traditional rescue is with high costs, dangerous high has been solved to this application.

Description

Cruising rescue throwing mechanism and cruising rescue aircraft using ground effect

Technical Field

The utility model belongs to the aircraft field, concretely relates to rescue aircraft that can cruise that utilizes ground effect.

Background

Modern drowning rescue can use many rotor unmanned aerial vehicle to reach drowning person and throw life saving equipment in the air, perhaps uses surface of water remote control rescue robot to expand the rescue in the surface of water.

Many rotor unmanned aerial vehicle with its easy operation, the reliability is high, requires advantages such as low to the place and has occupied the mass market in unmanned aerial vehicle field. But the characteristics of high energy consumption and poor cruising ability lead the rescue work of a long distance to be unable to be undertaken. And meanwhile, the multi-rotor unmanned aerial vehicle is limited by flight stability and influenced by natural factors such as wind direction, wind speed and spray, and the multi-rotor unmanned aerial vehicle is difficult to realize accurate delivery of rescue equipment. In the drowning accident, drowning person can't effectively remove in aqueous, consequently adopts the scheme of many rotor unmanned aerial vehicle aerial life saving equipment of puting in, and the drowning rescue that does not suit completely.

The water surface remote control rescue robot is mainly divided into a U-shaped (flying wing), a floating plate-shaped and a ship-shaped structure according to the shape. The U-shaped water area rescue robot is mainly propelled by a propeller (with a protective cover), a handle is arranged on the periphery of a shell, the general weight is light, the gripping performance of a trapped person is good, the steering is flexible under the normal posture, the U-shaped water area rescue robot has symmetry, the U-shaped water area rescue robot can be normally used after being overturned, the speed is low after the U-shaped water area rescue robot carries a load, and the posture control is greatly influenced by the person to be rescued. The floating plate type water area rescue robot mainly adopts propeller (with a protective cover) propulsion and duct type propeller propulsion, and the mixed type water area rescue robot is made of various materials and has more handles. Its advantages are high seaworthiness and bearing power, and high volume and mass. The ship-shaped water area rescue robot has a small-sized inflatable rubber boat type and a small-sized semi-submersible motorboat type according to the shape, and is propelled by a duct type propeller, so that the ship-shaped water area rescue robot is good in navigability, has good flexibility, is relatively complex in structure, large in size and mass and is not beneficial to storage and transportation.

SUMMERY OF THE UTILITY MODEL

The application aims to provide a cruising rescue throwing mechanism and a cruising rescue aircraft using a ground effect, which are formed by the cruising rescue throwing mechanism, so as to solve the problems that rescue personnel need to be launched, the rescue cost is high and the danger is high in the prior art.

In order to solve the above problem, the utility model adopts the following technical scheme:

a cruising rescue throwing mechanism comprises a power device and a throwing device, wherein the power device provides power for the throwing device, and the throwing device comprises a gear set connected with the power device, a rack connected with the gear set, a lever and a firing pin driven by the rack, a trigger rope connected with the lever, a trigger provided with a life buoy and connected with the trigger rope, and an automatic cabin door device.

The first straight gear and the second straight gear are respectively meshed with a first rack and a second rack, and the third straight gear is a quarter of the first straight gear in diameter and tooth number; the first rack and the second rack are fixedly connected with a first fixing piece, sharp teeth are arranged on the first fixing piece and used for locking the rack when pressure is applied, the pressure is provided by a screw fixed on the rudder base, a screw hole is formed in the first fixing piece, the first lever and the second lever are movably connected to the first fixing piece, and a firing pin is fixedly connected to the lower side of the rudder base.

Furthermore, the automatic cabin door device comprises a left cabin door and a right cabin door, a first push rod connected with the power device is installed between the left cabin door and the right cabin door, and a second push rod sliding along the first push rod is further installed on the left cabin door and the right cabin door respectively.

Further, the power device is a steering engine.

Furthermore, the first rack, the second rack, the first lever and the second lever are fixed on a base of the releasing device through a first fixing piece; the trigger is fixed on the base through a second fixing piece; the gear set is fixed on the base through a third fixing piece.

A cruising rescue aircraft using ground effect, which also comprises a fuselage, wings, a power supply device, an energy system, an output control system and a cabin,

the wings are designed in a duck wing structure;

the power supply device comprises motors, a triangular motor set is formed by a front motor and a rear motor, the front motor and the rear motor are fixed on two sides of the machine head by a fixing frame, and the rear motor is fixed in front of the machine body close to the rear tail wing;

the energy system is set to be double power;

the output control system is set to adjust the flying attitude of the airplane in a mode of flying control and a gyroscope, the rotating speed of the motor is adjusted by using an electric regulator to control the flying speed of the airplane, a PPM receiver is used to receive signals transmitted by a remote controller, and the signals are output after demodulation to realize the control of each steering engine and the motor;

the nacelle is designed as a ship-type nacelle. The aircraft can float on the water surface, thereby realizing water surface take-off and landing. Meanwhile, the resistance of the aircraft moving on the water surface in a low-speed state is reduced, and the energy utilization rate of the aircraft is improved.

The front motor and the rear motor are controlled separately. The front motor and the rear motor are separately controlled, so that the rear motor can be closed when being close to a drowning person, the drowning person is close to the drowning person by means of low-speed sailing of the front double motors, and the accuracy of drowning rescue is realized.

The dual power comprises that the wings are covered with solar panels and used as main energy sources of the aircraft, and a lithium battery is arranged in the aircraft body and used as a backup energy source. Theoretically, 100% of clean energy can be utilized, and the use cost in the daily patrol process is greatly reduced. In order to deal with the influence of long-time rainy weather, a lithium battery is also equipped for the emergency rescue device to serve as a backup energy source, so that the emergency rescue device can deal with emergency rescue under various special weather conditions.

The utility model discloses there is following beneficial effect:

1. rescue workers do not need to be launched, and the problems of high cost and high danger of the traditional rescue are solved;

2. the ground effect aircraft is innovatively used for drowning rescue, and the problem that the rescue speed of the traditional water surface remote control rescue robot is low is solved;

3. the problem of poor throwing precision of the multi-rotor unmanned aerial vehicle is solved by adopting an independently designed throwing scheme;

4. carry on solar panel on the wing, promoted aircraft duration and search and rescue scope, simultaneously more energy-conserving.

In consideration of the defects of high energy consumption, low speed, poor rescue accuracy, low energy utilization rate and the like of rescue equipment on the market at present, the three-motor triangular power unit improves the lift-drag ratio of the airplane, the airplane efficiency, the airplane flying speed and the energy utilization rate based on the ground effect, improves the airflow blocking effect, enables the actual maximum flying speed of the airplane to reach 110km/h, and solves the problems of insufficient take-off and landing capacity and longitudinal maneuvering capacity, low speed and the like of a common ground effect aircraft under complex conditions. The novel rescue mode is matched with the inflatable life buoy and the independently designed throwing device, so that the flying vehicle has smaller resistance after taking off, and can be close to drowning persons quickly. The accuracy of rescue can also be guaranteed to the throwing device of cooperation autonomous design.

Drawings

Fig. 1 is a schematic structural view of a first view angle of the feeding device of the present invention;

fig. 2 is a schematic structural view of a second viewing angle of the medium dispensing device of the present invention;

fig. 3 is a schematic structural view of a third viewing angle of the medium dispensing device of the present invention;

fig. 4 is a schematic structural view of a first view angle of the automatic door device of the present invention;

fig. 5 is a schematic structural view of a second view angle of the automatic door apparatus of the present invention;

fig. 6 is a schematic structural view of the lever portion viewing angle of the middle dispensing device of the present invention.

Marked in the figure, 1, a rack I; 2. a first fixing part; 3. a first straight gear; 4. a first bevel gear; 5. a third fixing part; 6. a second bevel gear; 7. a second straight gear; 8. a second rack; 9. a lever; 10. a second fixing part; 11. a first push rod; 12. a second push rod; 13. a left hatch door; 14. a right hatch door; 15. and a third straight gear.

Detailed Description

As shown in fig. 1-3, a cruising rescue throwing mechanism comprises a power device and a throwing device, wherein the power device provides power for the throwing device, and the throwing device comprises a gear set connected with the power device, a rack connected with the gear set, a lever 9 and a firing pin driven by the rack, a trigger rope connected with the lever 9, a trigger provided with a life buoy and connected with the trigger rope, and an automatic cabin door device.

The gear set comprises a first bevel gear 4 fixed on the rudder engine base, a second bevel gear 6 meshed with the first bevel gear 4 and a third straight gear 15 meshed with the second bevel gear 6, a first straight gear 3 and a second straight gear 7 are symmetrically arranged on an output shaft of the third straight gear 15, the first straight gear 3 and the second straight gear 7 are respectively meshed with a first rack 1 and a second rack 8, and the third straight gear 15 is a first straight gear 3 with a quarter diameter and a tooth number; the first rack 1 and the second rack 8 are fixedly connected with a first fixing part 2, sharp teeth are arranged on the first fixing part 2 and used for locking the racks when pressure is applied, the pressure is provided by screws fixed on a rudder base, screw holes are arranged on the first fixing part 2, the first lever 9 and the second lever 9 are movably connected to the first fixing part 2, and a firing pin is fixedly connected to the lower side of the rudder base.

As shown in fig. 4-6, the automatic door assembly includes a left door 13 and a right door 14, a first push rod 11 connected to a power device is installed between the left door 13 and the right door 14, and a second push rod 12 sliding along the first push rod 11 is further installed on each of the left door 13 and the right door 14.

The power device is a steering engine.

The first rack 1, the second rack 8, the first lever 9 and the second lever 9 are fixed on a base of the releasing device through a first fixing piece 2; the trigger is fixed on the base through a second fixing piece 10; the gear set is fixed on the base through a fixing piece III 5.

the wings are designed in a duck wing structure;

the energy system is set to be double power;

the nacelle is designed as a ship-type nacelle. The aircraft can float on the water surface, and therefore water surface take-off and landing are achieved. Meanwhile, the resistance of the aircraft in the low-speed state during movement on the water surface is reduced, and the energy utilization rate of the aircraft is improved.

The design principle of the utility model

(1) Ground effect

The product is mainly applied to the ground effect, which is a fluid mechanical effect that the induced resistance of an aircraft is reduced, and the lift-drag ratio is higher than that of air flight: when the flying height of the moving aircraft is very close to the ground or the water surface, the up-down pressure difference of the whole aircraft body is increased, the lift force is increased suddenly, a high-pressure air cushion layer is generated below the aircraft body during flying, the lift-drag ratio of the aircraft body is increased, the flying efficiency is improved, the energy consumption is reduced, and the energy utilization rate is higher. Therefore, in the design and manufacture process, the wings and the triangular power set in the brand-new canard layout are adopted, the airflow blocking effect is improved, and the ground effect of the aircraft is increased. Therefore, compared with the common aircraft, the aircraft utilizing the ground effect has higher speed and higher energy utilization rate, and is expected to become a revolutionary product of water surface quick rescue equipment.

2. Mechanical design

(1) Wing model

For the optimization of the ground effect wing type, the team designs the duck wing structure after carrying out a large amount of experiments and comparison, and carries out simulation on the brand-new duck wing layout.

The flow line diagram of the nearby flow field of the ground effect optimized airfoil under the free incoming flow and the ground effect can be seen, and the flow line around the airfoil tends to be parallel to the ground due to the limitation of the ground boundary under the ground effect. Less air flow over the upper surface of the airfoil than in free-flowing conditions is responsible for the reduced velocity and increased surface pressure of the upper surface air flow. The stagnation streamline under the conditions of free incoming flow of the wing profile and the ground effect can be seen, the wing profile stagnation point moves towards the lower surface under the condition of the ground effect, and the pressure difference resistance of the wing profile is reduced due to the fact that the stagnation point moves downwards. Compared with a common airplane, the ground effect aircraft has the advantages of larger lift force, higher flying efficiency, higher speed and higher energy utilization rate. The method is obtained by relevant theoretical calculation and physical test: the theoretical energy consumption per kilometer of the aircraft is 1.02 multiplied by 10^3KJ, the energy utilization rate can reach 83%, the energy consumption per kilometer of the rescue four-rotor unmanned aerial vehicle is reduced by 61.5%, the range is improved by 50%, and the energy-saving effect is obvious.

(2) Power supply device

In order to solve the problem that the ground effect is not obvious during low-speed sailing, a triangular motor set is used for providing power. Consists of two front motors and a rear motor. The front two motors are fixed on two sides of the machine head by a fixing frame, and the rear motor is fixed in front of the machine body close to the rear tail wing. The two front double motors are used for providing relative convection, providing relatively large resistance for the wings, and generally improving lift force and load capacity, and the rear motor is used for meeting the requirement of providing fluid for the rear delta wing in the low-speed sailing state, so that the wing effect can play an obvious control role in the low-speed sailing state, the stability of the low-speed sailing is improved, and the flying efficiency in the low-speed flying state is improved. The front motor and the rear motor can be separately controlled, so that the rear motor can be closed when being close to a drowning person, the drowning person is close to the drowning person by low-speed sailing by means of the front double motors, and the accuracy of drowning rescue is realized.

The power combination method of the aircraft comprises the following stages: taking off, cruising at low speed and cruising at high speed. During takeoff, the triangular motor set is completely opened, extremely strong power and certain lift force are generated instantaneously, the lift force is generated by matching with the wings, and the aircraft takes off quickly in a short distance; in actual use, only 1.48 seconds is needed for measuring the distance of 50m before the vehicle starts.

When the vehicle is in a low-speed cruising state, the rear motor is closed, and the two front motors provide the thrust in the cruising state.

When the aircraft is in a high-speed cruising state, the rear motor is completely started, and the front double motors are controlled by flight control to ensure that the aircraft flies stably.

(3) Energy system design

In the aspect of energy power of the airplane, a double-power design is innovatively used. The design of using a solar panel to match a lithium battery is adopted. The solar cell panel is covered on the wings of the airplane and used as a main energy source of the airplane, so that 100% of clean energy utilization can be realized theoretically, and the use cost in the daily patrol process is greatly reduced. In order to deal with the influence of long-time rainy weather, a lithium battery is also equipped for the emergency rescue device to serve as a backup energy source, so that the emergency rescue device can deal with emergency rescue under various special weather conditions.

(4) Output control system

The flight attitude of the airplane is adjusted by using a mode of flight control and a gyroscope, the flight speed of the airplane is controlled by using an electric speed regulator to regulate the rotating speed of a motor, a PPM receiver is used for receiving signals transmitted by a remote controller, and the signals are output after demodulation to realize the control of each steering engine and the motor.

(4) Throwing device

The throwing device which is independently designed is used and comprises a steering engine, a gear, a rack, a lever, a firing pin and the like. The first fixing piece is fixedly connected with the rack, the first lever and the second lever. The second fixing piece fixes the small black box on the inflatable life ring, and the triggering rope is hung on the second lever. The third fixing piece fixes the gear set on the base. When the trigger rope is used, the steering engine drives the bevel gear I to rotate 90 degrees, linear motion along the direction of the rack is formed and amplified through a gear set consisting of the bevel gear II, the straight gear I, the straight gear II and the like, the rack drives the fixing piece I, the lever I and the lever II to collide with the firing pin when moving, and the trigger rope is pulled. And triggering the lifebuoy trigger, popping the switch on the small black box, dropping the switch from the second fixing part, and opening the lifebuoy. Meanwhile, the first port of the first lever collides with the striker to drive the second port to rotate downwards. And releasing the second lever to enable the second lever to rotate, so that the trigger rope hung on the second lever falls off, and the trigger device falls off completely. The doors are opened simultaneously and the lifebuoy is launched out of the cabin but is still connected to the aircraft by a rope.

(5) Nacelle design

By using the design of the ship-shaped cabin, the aircraft can float on the water surface, thereby realizing the water surface take-off and landing. Meanwhile, the resistance of the aircraft moving on the water surface in a low-speed state is reduced, and the energy utilization rate of the aircraft is improved.

A full-automatic cabin door device is designed for the life buoy, when the life buoy is thrown, the throwing device pushes a rod 1 to slide along a rod 2, the cabin door is pushed away from the right, the life buoy slides out of a cabin, and a rope is still connected with an aircraft.

3. Rescue mode

The common rescue mode of special equipment in the existing market is that a multi-rotor unmanned aerial vehicle approaches a drowning person and puts a lifesaving device in the air, or a water surface remote control rescue robot is used for carrying out rescue on the water surface. The invention designs a brand-new rescue mode by combining the advantages of the invention.

In the standby state, the unopened inflatable lifebuoy is stored in the cabin of the aircraft. After the drowning accident happens, the aircraft takes off quickly from the water surface and quickly flies to the drowning person at a high speed of more than 80 km/h. When the drowning person approaches 10 to 15 meters, the throwing device is started, the inflatable life buoy is opened and thrown to the water surface, and is still connected with the aircraft in a rope form. Meanwhile, the aircraft decelerates, the front motor is closed, the aircraft returns to the water surface again, the aircraft drives to a drowner at low speed by the aid of the rear double motors, and the drowner catches the lifesaving device and then brings the lifesaving device to the water surface. The rescue personnel can finish the rescue without launching water. The invention has the advantages of rescue accuracy and high efficiency which cannot be achieved by the existing equipment at the same time. Meanwhile, the invention also has stronger safety and portability.

Compared with the prior art, the invention can realize the following beneficial effects:

1. high speed: at present, overwater rescue equipment mainly comprises rescue boats, submachine boats, multi-rotor rescue unmanned aerial vehicles and the like, the defect of too low rescue speed generally exists, and the optimal rescue time of a drowner is only a few minutes. Our ground effect aircraft uses advanced wing design, high speed, low torque motors. The ground effect vehicle can fly at low altitude near the water surface at the speed of at least 70km/h in the cruising state, and has a more obvious rescue speed advantage compared with the traditional water surface rescue equipment.

The front-mounted double motors are matched with a motor rotating device for providing relative convection. The auxiliary motor can rotate to supply air to the bottom of the wing, so that the wing can have a certain ground effect under the condition of low speed, and short-distance or even direct vertical takeoff can be realized.

2. Economy, low cost: compared with existing rescue equipment such as rescue boats, the cost of the traditional rubber dinghy is different from one to five ten thousand yuan, the traditional rubber dinghy is made of various environment-friendly recyclable materials, the cost is controlled to be about 2000 yuan, the traditional rubber dinghy has the advantages of being green and environment-friendly, simple in structure and durable, and the traditional rubber dinghy also provides advantages for maintenance, volume production and the like.

3. The loading capacity is big, and the operating efficiency is high: this team adopts three motor groups for start-up pulling force reaches higher level. The power system with independent innovative design is distributed with the wing profile, the power system with smaller thrust-weight ratio and higher efficiency can better utilize the ground effect to improve the running speed of the aircraft, and simultaneously, the extra airflow brought by the blades is utilized to improve the running efficiency.

4. Stable, application scope is wide: the gyroscope and the speedometer are used for optimizing the stability of the airplane, the flying control of the autonomous parameter adjustment is used for controlling the near-water windward attitude of the airplane, the gyroscope and the speedometer are used for optimizing the stability of the airplane, and the large-area aileron and delta wing control logic is used for achieving a stable flying condition. The wind power generation device is suitable for a certain wind speed in a certain severe environment and can reach the safe use standard. Compare in current many rotor unmanned aerial vehicle's the problem that is difficult to the surface of water, but ground effect near surface of water work can adapt to required application place.

5. The rescue efficiency is high, and the rescue can be accurately implemented: at present, rescue materials such as life buoys and the like are thrown by using throwing and other methods, and the problems that the throwing distance is short, the materials are difficult to accurately throw to the side of a drowner and the like exist. The novel ground effect aircraft can be used as a carrier, can carry devices such as a GPS (global positioning system) positioning device and a graph transmission system, can better perform water surface supervision and water surface rescue tasks, and the ground effect aircraft designed by us can adopt special wing profiles

The problem of load and the problem of fixed point putting are solved.

6. Small, the quality is light, easily carries: traditional rescue equipment is relatively heavy and not convenient enough. The product uses environment-friendly materials in a large number, so that the aircraft has considerable strength, is lighter in weight, small in size and equivalent to a large life buoy, and is convenient for rescue workers to carry.

7. The safety is high: the multi-rotor unmanned aerial vehicle is easy to cause secondary damage to drowners in rescue, so that the position of the propeller is designed to be higher in water leaving and higher in safety factor when the aircraft is designed; in order to reduce injury caused by people collision, the wing is divided into two parts, and the outer part of the wing is easy to break off under the influence of impulsive force, so that most of impulsive force can be relieved, and the injury of people can be greatly relieved under the condition of people collision. Meanwhile, the aircraft is made of relatively soft materials, and the safety of the product is guaranteed.

8. Energy conservation and strong cruising ability: compare with general unmanned aerial vehicle energy consumption greatly, the duck wing structure of ground effect, ship type cabin for ground effect aircraft flight efficiency is higher, and is fast, and energy utilization is rateed highly. The resistance borne by the airplane during ordinary navigation is about 70% of that during high-speed navigation, and the resistance is obtained through relevant theoretical calculation and physical tests: the theoretical energy consumption per kilometer of the aircraft is 1.02 multiplied by 10^3KJ, the energy utilization rate can reach 83%, the energy consumption per kilometer of the rescue four-rotor unmanned aerial vehicle is reduced by 61.5%, the range is improved by 50%, and the energy-saving effect is obvious. And this aircraft has carried solar panel, under non-long-time overcast and rainy weather, can realize 100% use solar energy completely, realizes 0 carbon discharge capacity, 0 pollutes.

Claims

1. The cruising rescue throwing mechanism is characterized by comprising a rudder base, a power device and a throwing device, wherein the power device and the throwing device are installed on the rudder base, the power device provides power for the throwing device, and the throwing device comprises a gear set connected with the power device, a rack connected with the gear set, a lever and a firing pin driven by the rack, a trigger rope connected with the lever, a trigger connected with the trigger rope and provided with a life buoy, and an automatic cabin door device.

2. The cruising rescue throwing mechanism according to claim 1, wherein the gear set comprises a first bevel gear fixed to the rudder base, a second bevel gear meshed with the first bevel gear, and a third spur gear meshed with the second bevel gear, wherein a first spur gear and a second spur gear are symmetrically arranged on an output shaft of the third spur gear, the first spur gear and the second spur gear are respectively meshed with a first rack and a second rack, and the third spur gear is a first spur gear with a quarter diameter and a tooth number; the first rack and the second rack are fixedly connected with a first fixing piece, sharp teeth are arranged on the first fixing piece and used for locking the rack when pressure is applied, the pressure is provided by screws fixed on the rudder base, a screw hole is formed in the first fixing piece, the first fixing piece is movably connected with a first lever and a second lever, and the lower side of the rudder base is fixedly connected with a firing pin.

3. The cruise rescue release mechanism according to claim 2, wherein the automatic cabin door device comprises a left cabin door and a right cabin door, a first push rod connected with the power device is installed between the left cabin door and the right cabin door, and a second push rod sliding along the first push rod is further installed on each of the left cabin door and the right cabin door.

4. The cruise rescue release mechanism according to claim 3, wherein the power device is a steering engine.

5. The cruise rescue release mechanism according to claim 4, wherein the rack I, the rack II, the lever I and the lever II are fixed on a base of the release device through a fixing piece I; the trigger is fixed on the base through a second fixing piece; the gear set is fixed on the base through a third fixing piece.

6. A cruising rescue aircraft using ground effect, comprising the cruising rescue throwing mechanism of any one of claims 1 to 5, further comprising a fuselage, wings, a power supply device, an energy system, an output control system, and a cabin,

the wings are designed in a duck wing structure;

the energy system is set to be double power;

the nacelle is designed as a ship-type nacelle.

7. A cruise rescue aircraft using ground effect according to claim 6, characterized in that the two front motors are controlled separately from the two rear motors.

8. A cruise rescue aircraft as claimed in claim 7, characterized in that the dual power consists of solar panels covering the wings as the primary energy source of the aircraft and a lithium battery inside the fuselage as the backup energy source.