68 results about "Spiral wave" patented technology

The invention discloses a three-level acceleration type spiral plasma propulsion device. The three-level acceleration type spiral wave plasma propulsion device is characterized in that an antenna is connected with an RF (Radio Frequency) power source, the antenna and a discharge chamber are fixedly arranged in a sleeve, and an electromagnetic coil is fixedly arranged on the outer circumferential surface of the sleeve in a surrounding way; the rear part of the discharge chamber is provided with a rotating electric field ion acceleration system, and the rotating electric field ion acceleration system comprises four graphite electrodes which are uniformly and symmetrically arranged on the outer circumferential surface of the sleeve; the tail end of the rotating electric field ion acceleration system is provided with an electromagnetic spray pipe ion acceleration system, and the electromagnetic spray pipe ion acceleration system comprises a conical expanding spray pipe of which one end is connected with the tail part of the discharge chamber, and the electromagnetic coil. According to the three-level acceleration type spiral plasma propulsion device disclosed by the invention, the rotating electric field acceleration system is adopted for carrying out secondary acceleration on a plasma, acceleration is further carried out through the electromagnetic spray pipe, and a three-level acceleration effect is formed, thus the thrust is generated by efficiently accelerating ions, the work of a propulsor under high power can be realized, the reliable performance of high ion ejecting speed and high propulsion capacity can be realized, wide application prospect is obtained, and a high-performance power platform can be provided for future space technology development.

The invention discloses a metal cutting wire with spiral wave-shaped rotary bending parts. The metal cutting wire is provided with a plurality of spiral wave-shaped rotary bending parts along a central axis. According to the metal cutting wire with the spiral wave-shaped rotary bending parts, better capability of carrying mortar grinding materials in the hard material cutting process can be provided through a three-dimensional structure, and the grinding materials are unlikely to strip from the cutting wire so that the production speed in the cutting and fragmenting process of silicon, jewel and the like is greatly increased, the production efficiency in the cutting and fragmenting process of silicon, jewel and the like is greatly improved, and the surface quality of the fragmented materials also can be effectively improved at the same time. The speed of the grinding materials in the abrasion cutting process of hard materials is reduced relative to that of the metal cutting wire, so that the abrasion degree of the metal cutting wire is reduced.

The invention discloses a bi-order grid spiral wave ion propulsion device which comprises a discharge chamber, a spiral wave excitation antenna, a metal sleeve, an electromagnetic coil and a bi-order grid system. The spiral wave excitation antenna is connected with a radio-frequency power source and is arranged outside the discharge chamber in a sleeving mode, the spiral wave excitation antenna and the discharge chamber are both arranged inside the metal sleeve, and the metal sleeve is sleeved with the electromagnetic coil. The bi-order grid system is arranged at the tail end of the discharge chamber. The bi-order grid system comprises a screen grid, an extraction grid, an accelerating grid and a decelerating grid which are sequentially arranged away from the discharge chamber from near to far, and the screen grid, the extraction grid, the accelerating grid and the decelerating grid are all provided with grid holes. According to the bi-order grid spiral wave ion propulsion device, the mode that a spiral wave plasma source and the bi-order grid system are combined is adopted, the propulsion device can work under high power, and thus the reliable performance of high specific impulse and high propulsion capability can be achieved.

The invention relates to a multi-mode spiral wave ion thruster and belongs to the field of aerospace electric propulsion. A quartz discharging chamber is placed in a Faraday barrel; an anode is fixedin an opening end of the quartz discharging chamber; an opening end of the quartz discharging chamber is in contact connection with a screen grid; the screen grid, an acceleration grid and a deceleration grid keep a distance; an antenna is mounted on an outer barrel wall of the quartz discharging chamber; a plurality of spiral coils are mounted on an outer wall of the Faraday barrel; a cathode neutralizer is placed at the opening end of the quartz discharging chamber and is used for neutralizing an electrostatic grid electrode to accelerate led-out ion beam flow; the cathode neutralizer and the anode generate an axial electric field, a route of electrons can be effectively increased and the ionization rate is improved. The thruster provided by the invention is provided with the neutralizerand the neutralizer can be used for neutralizing the ion beam flow led out from the electrostatic grid electrode; cathode and anode structures are arranged and the axial electric field can be provided, so that the ionization rate of plasmas is improved and the production cost of ions can be calculated; the designed spiral wave ion thruster has the advantages that an additional magnetic field hasan adjustable bit type and multi-mode working of the thruster can be realized.

The invention discloses a spiral wave electromagnetic acceleration plasma source which is cylindrical as a whole. The plasma source sequentially comprises an outer magnetic screen, an outer magnetic coil set, an inner magnetic screen, an antenna, an annular ceramic discharge chamber and an inner magnetic coil set from outside to inside in the radial direction. On one hand, a spiral wave source serves as a plasma generation device, has the advantages of being high in ionization rate, free of electrode design, high in controllability and the like, and is a novel plasma source with excellent performance; and on the other hand, a hall electromagnetic acceleration mechanism is used, on the basis of high-density plasma generated by the spiral wave source, the plasma is subjected to second-orderacceleration, the ion jet speed is increased, and the specific impulse of a thruster is improved.

The invention relates to an antiphase coupling elliptic function spiral wave filter which comprises a spiral wave filter cavity, a spiral wave filter cover plate, an SMA joint, a frequency debugging screw, a coupling debugging screw, a block plate, n resonators and m antiphase coupling mechanisms, wherein n is an integer more than or equal to 3, and m is an integer more than or equal to 1; each resonator comprises a polytetrafluoroethylene medium framework and a positive phase spiral coil, wherein the positive phase spiral coil is wound on the polytetrafluoroethylene medium framework; each antiphase coupling mechanism includes two antiphase spiral coils and an antiphase feed cable, wherein the antiphase spiral coils are wound on the polytetrafluoroethylene medium framework along the reverse direction from the earthing position of the positive phase spiral coil, and the winding direction is opposite to the direction of the positive phase spiral coil, so that antiphase current is generated; on the premise of not increasing the volume, the weight and the loss, a pair of or a plurality of attenuation pole points are formed outside a band of the wave filter, so that inhibition outside the band can be greatly improved. The spiral wave filter has the advantages of novel and compact structure, small volume, light weight and large power capacity.

The invention discloses an amplitude type fractal spiral wave zone plate. According to the amplitude type fractal spiral wave zone plate, a series of light permeable spiral annular zones are obtained by applying cantor set fractal to amplitude angles of the spiral wave zone plate, and the coordinates of the light permeable spiral annular zones meet the formulas shown in the description. On the basis of the spiral wave zone plates, the self-similarity of the fractal is combined, and the annular zones are obtained by applying the cantor set fractal to the amplitude angles. Equivalently, a series of transparent half-wave zones and non-transparent half-wave zones with self-similarity are picked out from the directions of the amplitude angles. Compared with common spiral wave zone plate of the same numerical aperture, a series of zonal turbulent structures can be obtained. By adjusting N and S, the fractal period can be controlled, and different fractal spiral wave zone plates can be obtained. In the research fields of extreme ultraviolet lithography, tiny electric power systems and the like, the amplitude type fractal spiral wave zone plate has the wide application prospect, and the application range of visual light, extreme ultraviolet, X ray and other multiple wave band three-dimensional trapped particles is enlarged.

The invention relates to a vortex light shaping and multi-singular-point control method based on a high-order cross phase. Vortex light is a special light field with a spiral wave front, a cross phaseis a special light field phase structure, and the third order or more is called as a high-order cross phase. The method comprises the following steps: firstly, preparing a holographic sample carryingvortex light information and a high-order cross phase by utilizing a multi-parameter combined regulation and control technology, and loading same to a spatial light modulator; emitting a linear polarization Gaussian beam to the spatial light modulator for complex amplitude modulation, wherein the emergent light is vortex light carrying a high-order cross phase, and vortex light with a required shape and odd point distribution can be obtained after the emergent light is propagated for a certain distance. The method is simple in light path and high in flexibility, belongs to the field of vortexlight control, and can be applied to shaping and multi-singular-point control of complex vortex light.

Although, conventionally, there were two methods, (1) a wave was transmitted through a spiral phase plate and (2) a diffraction grating containing an edge dislocation was used, they incurred complication of a configuration and securement of a larger amount of space and were not efficient because each of the spiral wave generation methods needed an incident wave to be a plane wave and at least one time of imaging is necessary at the time of wave irradiation on an observation object. In order to efficiently generate the spiral wave having a sufficient intensity, a structure of edge dislocation is taken in into a pattern of the zone plate and a spiral pattern containing a discontinuous zone is formed. Moreover, a thickness and a quality of material that change the phase of the wave by an odd multiple of π are selected for a material of the wave-blocking section in the pattern.

The invention discloses a high-frequency characteristic measuring device of a spiral wave travelling tube, which is composed of a moving unit, a data acquisition unit and a centralized control unit; a control part is arranged in the centralized control unit and realizes the communication among the centralized control unit, the moving unit and the data acquisition unit. The moving unit realizes position calibration and movement during the measurement under the control of the centralized control unit, thus avoiding the error of manual calibration and improving the measuring precision; the data acquisition unit completes parameter setting and data transmission under the control of the centralized control unit, and avoids manual operation of a vector network analyzer, thus greatly improving the measuring efficiency; the centralized control unit can implement direct processing of the collected data and does not need to import the data into other software for processing. The measuring device improves the precision and efficiency of the high-frequency characteristic measurement of the spiral wave travelling tube, and solves the lower precision and efficiency problems of other traditional measuring devices.

The invention discloses a multistage ionization rotating magnetic field acceleration spiral wave plasma source, and the plasma source uses spiral wave discharge plasma as a plasma first-order ionization source, uses a multistage stepped contraction ionization structure, and uses a magnetic confinement structure and a rotating magnetic field acceleration structure to accelerate the plasma. According to the invention, the ionization rate and the plasma density of a plasma source propellant are improved through the multi-step ionization technology; the magnetic confinement and rotating magnetic field acceleration structure is used for accelerating the plasma, and the ejection speed of the plasma is increased; in addition, the overall structural design does not need discharge electrodes, neutralizers and other parts which are prone to corrosion and seriously restrict the service life of the plasma source, and then the performance and the service life of the plasma source are improved.

The invention discloses an aortic dissection vascular stent and a manufacturing method thereof. The aortic dissection vascular stent comprises a stent body and a membrane attached to the outer side of the stent body, the stent body is formed by multiple coils in a spiraling mode, and each coil is formed by multiple waves. The manufacturing method includes the steps that a spatial continuous spiral wave curve is constructed through a spatial cylindrical coordinate system; a three-dimensional model of the stent body is obtained in a scanning mode; an entity model of the stent body is made according to the three-dimensional model; a metal wire is wound around the entity model to obtain the stent body; heat shaping and electropolishing are carried out on the stent body; the membrane is arranged on the outer side of the stent body in an electrospinning or hot-pressing mode. Bending of the vascular stent in the bent lumen is uniformly distributed in the whole vascular stent, so that the fitness of the vascular stent is improved, and the situation that the vascular wall is bent or damaged is avoided. Besides, the vascular stent is specially designed for the aortic dissection and is simple in structure, convenient to operate, appropriate in supporting force and suitable for the pathological characteristics of the aortic dissection.

The invention provides an injection molding machine and an injection screw thereof. The screw thread part of the injection screw comprises a feeding section, a compressing section and a homogenizing section; the homogenizing section is formed by large-pitch spiral grooves and spiral wave crests; and a gap between the spiral wave crests and the inner wall of a charging barrel is small, and when a motor drives the screw to rotate to plastify raw materials, all sol needs to cross the gap to obtain suitable cutting. The plastified sol enters the large-pitch spiral grooves and is conveyed into the material storage space of the charging barrel at relatively small damping and high efficiency. When the sol enters the deeper spiral grooves after crossing the spiral wave crests, eddy currents are formed to generate scroll currents along the depth of the spiral grooves; uniform chaotic mixing is conducted on the plastified sol, and heat exchange between the sol and the charging barrel is conducted more fully; and a uniform-temperature sol body with high quality is generated. According to the injection molding machine and the injection screw thereof, the material is fully plastified at smaller cutting displacement and higher plastifying efficiency. The defects of uncontrolled temperature rising, slipping of the screw, slow feeding and the like which are prone to occur in the sol melting process are overcome.

The invention relates to a vortex light wavefront distortion correction method based on a deep multi-branch compensation network. Vortex light is a special light field with a spiral wavefront, and superposition-state vortex light can be generated through self-interference of single-state vortex light in multiple modes. The method is characterized in that a deep multi-branch compensation network is designed, first ten Zernike polynomials are selected to carry out numerical simulation on an atmospheric turbulence phase, and branch learning is carried out on a mapping relation between a vortex light distortion intensity diagram and an atmospheric turbulence phase screen according to a principle that different Zernike polynomials represent different aberration characteristics. In a concept experiment, under various turbulence intensities, once a distorted vortex light intensity distribution diagram is input into a trained network, the network can accurately predict a corresponding atmospheric turbulence compensation screen in an extremely short time; the method can be used for correcting distorted vortex light subjected to phase interference, and the correction effect is good; the method has the advantages of good flexibility, rapidity and robustness, simple operation, and strong generalization ability.

The invention discloses a method for three-dimensionally capturing and rotating a micromechanical member by using an ultrasonic radiation force. In the method, four ultrasonic transducers are used to generate a wave beam having a spiral wave front, the wave beam interferes and is superposed with a radiation wave beam generated by an ultrasonic transducer which is coaxial with and opposite to the four ultrasonic transducers, an interferential sound field has the capacity for three-dimensionally capturing the micromechanical member, and the direction angle of an ultrasonic radiation force potential trough along the circumferential direction of an ultrasonic transducer phase is adjusted and changed to drive the micromechanical member to rotate around an axis. Compared with the conventional operation policy, the method has an important function of angle control and can control the rotation direction and angle of the micromechanical member. The method plays a significant role on occasions when non-contact operation of the micromechanical member is required and can be used in high-tech fields of micro electro mechanical system manufacture and assembly, biomedical engineering and the like.

The invention relates to the technical field of cutting steel wires, in particular to a spiral-structure cutting steel wire. The spiral-structure cutting steel wire comprises a steel wire body. Bent deformed parts are arranged on the steel wire body and spirally distributed in the axial direction of the steel wire body. The wave heights of the deformed parts in the radial direction of the steel wire body are the same. In addition, the invention further provides a production device of the spiral-structure cutting steel wire. The production device comprises a rotatable columnar hollow shell. Two pairs of torsion limiting wheels are arranged in the shell in the axial direction and are fixed in the shell through bearing pedestals. A deformation device is arranged between the two pairs of torsion limiting wheels. The steel wire sequentially penetrates the first torsion limiting wheel pair, the deformation device and the second torsion limiting wheel pair. After the above structure is adopted, the produced steel wire achieves a uniform and stable spiral wave shape, the defects of saw marks, steps and the like, caused by cutting steel wire fluctuation and the like, of a cut piece are thoroughly overcome, the quality of the cut piece is improved, the percent of pass of the cut piece is increased, and cost is reduced.

The invention discloses a spiral wave opening system electrostatic ion thruster, and belongs to the technical field of aerospace propulsion of long-life deep space detectors and satellite power systems. The spiral wave opening system electrostatic ion thruster comprises a gas storage tank, a gas supply pipe, a discharge cavity, a spiral wave antenna, an AC electrode and a ring electrode plate. Theworking medium gas in the gas storage tank enters the discharge cavity through the gas supply pipeline, and at the same time, an external radio frequency source supplies power to the antenna, and thehelium gas is ionized inside the discharge to produce spiral wave plasma. Due to the unique double-layer potential difference of spiral wave plasma, the working fluid gas can be accelerated, and other working fluids leave the discharge cavity and enter the ring electrode plate area to accelerate again in the electric field area generated by the ring electrode plate. The spiral wave opening systemelectrostatic ion thruster has the advantages of reduced energy consumption, long service life, low production difficulty and the like.

The outer shape and size of a diffraction grating including an edge dislocation is made smaller than the irradiation areas of light waves and electromagnetic waves, by using an opener different from in the diffraction grating, the shape and size of the opening is superposed on the shape of a spiral wave that is generated by an edge dislocation diffraction grating, and the shape and size of the opening are reflected in the shape and size of the spiral wave on the diffractive surface. In addition, not only a diffraction grating system including a pair of a single opener and a single diffraction grating, but also a diffraction grating system in which plural openers and plural edge dislocation diffraction gratings are combined are used, and plural spiral waves can be generated on the diffractive surface with a higher degree of freedom.

The invention discloses a radio frequency transmission device for a spiral wave plasma electric thruster. The radio frequency transmission device comprises a rigid metal tubular outer conductor, cylindrical insulating blocks, a metal rod-shaped central conductor and a metal gasket, the inner walls of the two ends of the rigid metal tubular outer conductor are sequentially provided with a first step and a second step from the middle to the two ends. The cylindrical insulating blocks are embedded in the portions, located on the inner wall of the first step, of the two ends of the rigid metal tubular outer conductor, stepped grooves are formed in the outer ends of the cylindrical insulating blocks, and the portions, located between the second step and the stepped grooves, of the outer ends ofthe cylindrical insulating blocks are sleeved with the metal gasket. According to the invention, a combined bracket type transmission structure is adopted, the power output by the radio frequency power supply can be transmitted to the discharge antenna in a lossless manner, and meanwhile, the phenomena of overflow of electromagnetic interference and parasitic plasmas in the transmission process are avoided, so that the high efficiency and stability of radio frequency transmission are improved.

A low-frequency loudspeaker is provided comprising an enclosure having a front, a back and a sidewall. An audio speaker is mounted in an opening in the front of the enclosure. The audio speaker has a diaphragm for producing front sound waves that are transmitted outwardly from the diaphragm and back sound waves that are transmitted into the enclosure from the diaphragm. A spiral waveguide is positioned within the enclosure. The spiral waveguide has a first end proximal to the speaker diaphragm for receiving the back sound waves and extends outwardly therefrom in a spiral pattern to a second end that forms a low-frequency terminus exit port opening in the sidewall.

The invention provides a single-stage focusing spiral wave zone plate. The wave zone plate comprises a transparent substrate and a plurality of lightproof elements formed on the transparent substrate;the number density of the lightproof elements is in cosine or sine distribution along the radial direction, i.e., the lightproof elements are distributed annularly and are randomly distributed alongrings; the transmittance function of the zone plate is described in the descriptions of the invention; in the transmittance function, l is a topological charge number, phi is an argument, n is the number of rings, ri is the radius of the nth ring, r1<2> is equal to lambda f, wherein lambda is the wavelength, and f is the focal length. The single-stage focusing spiral wave zone plate is only provided with a pair of conjugated first-stage focuses, so that interference and errors caused by high-stage diffraction can be eliminated, and vortex light beams can be generated; meanwhile, the structureof the single-stage focusing spiral wave zone plate only has a light-transmitting area and a light-proof area, since the single-stage focusing spiral wave zone plate is of a binary structure, and thesingle-stage focusing spiral wave zone plate is easy to manufacture. The characteristics of the single-stage focusing spiral wave zone plate show that the single-stage focusing spiral wave zone platecan be used as an optical conversion element for generating optical vortexes, edge enhanced imaging elements or X-ray bands.

The invention relates to a vortex light mode detection method based on a three-step phase shift method. Vortex light is a special light field with a spiral wave front, and the three-step phase shift method is a phase measurement method. The method comprises the steps of firstly, preparing a hologram of target vortex light; superposing three beams of one-dimensional gratings with phase shifts of 0,0.5 pi and pi on the basis to obtain three new holograms; sequentially recording the intensity distribution of the initial vortex light and the interference distribution of the three beams of phase shift vortex light on the same plane through a spatial light modulator method, and obtaining the complex amplitude distribution of the vortex light in combination with a phase formula; and secondly, carrying out convolution operation on the complex amplitude distribution and standard vortex light bases with different topological charges through a computer to acquire the mode degree and the mode purity of the target vortex light and achieve mode analysis of the target vortex light. The method provided by the invention is simple in optical path and high in flexibility, belongs to the field of vortex light detection, and can be applied to mode detection of complex vortex light.

The invention discloses an aortic dissection vascular stent and a manufacturing method thereof. The aortic dissection vascular stent comprises a stent body and a membrane attached to the outer side of the stent body, the stent body is formed by multiple coils in a spiraling mode, and each coil is formed by multiple waves. The manufacturing method includes the steps that a spatial continuous spiral wave curve is constructed through a spatial cylindrical coordinate system; a three-dimensional model of the stent body is obtained in a scanning mode; an entity model of the stent body is made according to the three-dimensional model; a metal wire is wound around the entity model to obtain the stent body; heat shaping and electropolishing are carried out on the stent body; the membrane is arranged on the outer side of the stent body in an electrospinning or hot-pressing mode. Bending of the vascular stent in the bent lumen is uniformly distributed in the whole vascular stent, so that the fitness of the vascular stent is improved, and the situation that the vascular wall is bent or damaged is avoided. Besides, the vascular stent is specially designed for the aortic dissection and is simple in structure, convenient to operate, appropriate in supporting force and suitable for the pathological characteristics of the aortic dissection.

The invention relates to a floor heating pipeline cleaning machine. The floor heating pipeline cleaning machine comprises an air compressor and further comprises a self-priming water pump; the air compressor is connected with an air inlet pipeline; the self-priming water pump is connected with a water inlet pipeline; the air inlet pipeline is in parallel connection with the water inlet pipeline; the air inlet pipeline and the water inlet pipeline are connected with an output pipeline through a three-way valve; and a rotating device is arranged on the output pipeline and comprises a round pipeand a spiral blade which is located in the round pipe. The floor heating pipeline cleaning machine adopts a spiral wave cleaning principle, and the rotating device is disposed in the floor heating pipeline cleaning machine, so that the cleaning efficiency of the cleaning machine is higher; and a manual operation mode and a remote operation mode are arranged, equipment braking is achieved in an emergency, remote control over equipment can be achieved, and the floor heating pipeline cleaning machine is convenient to use, easy to manufacture and capable of being widely popularized in the field ofcleaning devices.

The invention relates to a method for detecting prestart load of an intelligent soft starter of a three-phase asynchronous motor, comprising a three-phase power input end, a three-phase controllable silicon module, a current voltage detection module and a motor. The three-phase controllable silicon module sends a cycle of the voltage which is the gradually descending second half part of a positive spiral wave of a three-phase alternating current into the motor before the intelligent soft starter electrifies the motor, the current voltage detection module tests the current changes of three-phases input ends of the motor and the voltage changes among the zero lines, if the changes are continuous, the motor and the devices relevant with the motor are failure-free, if the sudden changes are involved in the changes, the motor and the devices relevant with the motor are out of action.

This optical receiver (20) receives, with a light-receiving element (21), a light beam having a spiral wave surface propagated through a multimode fiber (30). The optical receiver (20) is provided with a receiving side vortex optical element (24) disposed between the multimode fiber (30) and the light-receiving element (21).

The invention provides a pair of single-fiber vortex optical tweezers, and a manufacturing method and a modulation method thereof. A section of gradient refractive index multimode optical fiber is welded at the end part of a single-mode optical fiber; a spiral wave zone plate formed by a shading film layer is prepared on the optical fiber end face of the multimode optical fiber with the gradient refractive index, and a light-transmitting bright wave zone and a light-proof dark wave zone are formed on the shading film layer by the spiral wave zone plate. The gradient refractive index multimode optical fiber can realize a larger beam expanding effect; the spiral wave zone plate enables light emitted from the end face of the optical fiber to pass through the spiral wave zone plate and realize vortex focusing behind the end face of the optical fiber; the dark wave zone is light-proof, only the bright wave zone is light-transmitting, and the spiral wave zone plate has only one primary diffraction focus all the time even in an environment with a changing refractive index. The single-fiber vortex optical tweezers not only can detect an emergent light field in an air environment and capture particles in a liquid environment, but also can change the axial position of the light trap by adjusting the wavelength of incident light, so that the particles are driven to axially move and rotate in fluid.

The invention discloses a design method for a heart failure model of a human ventricular muscle tissue, and belongs to the technical field of virtual human hearts. Heart failure is taken as a research object, and myocardial electrophysiological and mechanics characteristics and a spiral wave dynamics mechanism under heart excitation-contraction coupling are discussed to discover a relationship of interaction between the heart failure and arrhythmia. A TP06 model simulates a single ventricular muscle cell of a human body, then the TP06 model is coupled to an NHS08 model, and an ECC model is built; based on an improved TP06 model and existing data, a human ventricular heart failure muscle cell model is built, and the electrophysiological and mechanics characteristics of human ventricular muscle cells, an action potential duration restitution curve and an early afterdepolarization restitution curve under normal and heart failure conditions are compared; finally by adding coupling among the cells, a two-dimensional single-layer myocardial tissue action potential conduction model is successfully built, and spiral waves are induced by adopting a ''wave shearing method''; and then, dynamics characteristics of the spiral waves under the normal and heart failure conditions are compared.