A machine tool having a motor-driven machine spindle which can be rotated about a spindle axis. The machine spindle has a tool holder arranged at the face. A tool is exchangeably arranged on the machine spindle. The tool has a coupling element which is compatible with the tool holder of the machine spindle. The coupling element has a rear surface pointing toward the machine spindle. The machine tool has at least one galvanic contact point for the electric current or data transmission, the point being arranged between the machine spindle and the tool and rotating together with the machine spindle. The galvanic contact point has a contact element which is arranged at the face of the tool holder on the spindle side, and a contact element which is arranged on the rear surface of the coupling element on the tool side.

A machining apparatus for grinding, milling, polishing or the like of a dental workpiece. The machining apparatus contains a machining tool, a housing to which the machining tool is mounted rotatably about an axis of rotation relative to the housing, and a holding device to which the housing is fixed. The housing is mounted yieldingly movably to the holding device in dependence on forces exerted on the machining tool.

In a machine tool having a rotary shaft for use in rotating a tool or a workpiece, a plurality of stable rotation speeds at which the chatter vibrations are expected to be suppressed, and at least one switching rotation speed across which a dynamic characteristic of a rotary shaft system changes are stored. The plurality of stable rotation speeds may be determined from chatter vibrations detected using a vibration detection unit. Optimum rotation speed that is a rotation speed to which a rotation speed of the rotary shaft is changeable without crossing the switching rotation speed is selected from the plurality of stable rotation speeds, and the rotation speed of the rotary shaft is changed to the optimum rotation speed. Thus, chatter vibrations generated during rotation of the rotary shaft can be suppressed effectively.

A machine permits an end of a thick-walled, high-pressure tubing to be chucked in a collet one time, coned, faced and threaded, using a coning head and threading head which are mounted on a carriage which can be translated laterally between three positions and the coning and threading heads parallel to the longitudinal axis of the workpiece to complete the coning and threading operations.

A translocation-simulating loading apparatus for the gear grinding machine with the shaped grinding wheel is provided. The apparatus includes a load-receiving test piece disposed on the gear grinding machine with the shaped grinding wheel and a load-exerting component for use in loading simulation. The gear grinding machine enables linear movements along the X, Y, and Z axes, a rotary movement around the Y axis, a rotary movement C around the Z axis, and a rotary movement A around the X axis. An angle α is formed between the axis L of a ball seat of the load-exerting component and the X axis direction of a Y axis component and an angle formed between the normal line of a load receiving face a and the X direction of the coordinate system of the machine tool is α. A detection method for static stiffness distribution is provided.

In a pilot hole of a workpiece made of a difficult-to-cut cast iron, a cutting tool having a leading end to which a cutting insert is attached is inserted to cut the surface of the wall of the pilot hole. At this time, the cutting tool rotates about an axis (α) and also revolves about another axis (β), so that contouring is performed on the workpiece by the tool. The cutting insert is formed of a sintered body having a CBN content of not less than 85% by volume, and the cutting insert has a thermal conductivity of not less than 100 W/(mK).

The present invention relates to a compensation system for compensating for the drop of the ram in a machine tool, comprising a vertical translation carriage (1) incorporating the application ram, at least one and preferably two perforated plates (2) being arranged on said carriage (1), on each of which there is incorporated a fixed sliding block (3) and movable sliding blocks (4), which blocks are linked with a guide for the transverse movement of the ram, such that the drop of the ram is compensated for by means of the controlled bending of the plates (2).

A master servo motor and a slave servo motor that synchronously drive for rotation a master main spindle provided with a center that supports one end of a work piece and a slave main spindle provided with a center that supports the other end of the work piece are included. Before grinding, a slip detection cycle that detects a limit current value for the servo motors, at which the work piece and the centers slip, is executed and, during grinding, a grinding condition is changed to prevent a slip between the work piece and the centers in advance at the time when any one of current values of the servo motors has reached a slip threshold value set on the basis of the limit current value.

A tool adapter includes an adaptor body having a connection portion structured to be attached to a machine tool and a holder portion disposed opposite the connection portion and a tool receiver structured to receive and couple a portion of a rotary cutting tool therein. The tool receiver is mounted in the holder portion so as to be rotatable to a limited extent. The tool receiver is mounted in the holder so as to be elastically resilient in both the axial and circumferential directions.

The present invention relates to a control system for a wind turbine, comprising an electrical device that is arranged for being used during normal operation of a wind turbine and a power source that is arranged to be used as an emergency power supply to a blade pitch motor, wherein the blade pitch motor is arranged to test at least one property of said power source. The invention also relates to a method for testing a power source.

A nacelle main frame structure and drive train assembly (1) for being mounted on a tower (2) of a wind turbine. The nacelle main frame structure and drive train assembly (1) comprises a nacelle main frame structure (4) with a central part (6) connecting a first part (7) to a second part (8). The first part (7), during wind turbine operation and/or servicing activities, takes up loads of a rotor (9). A drive train (5) is at least partially located between the first and second parts (7, 8). The central part (6) of the main frame structure (4) is located substantially above at least part of the drive train (5) and is such that at least part of the drive train (5) can only be removed from the main frame structure (4) by lowering at least part of the drive train (5) from the main frame structure (4).

The invention relates to a rotor for an axial flow pump for conveying a fluid having an axis of rotation and having an impeller blade which has at least one part surface which extends transversely to the axis of rotation and beyond it, wherein the impeller blade has throughgoing webs or a network of webs which connect a different marginal regions of the impeller blades to one another. A good compressibility is hereby achieved in the radial direction with high stability during operation.

Embodiments of the invention relate to a rotor system, particularly for use in a wind turbine generator system. A support (11) is provided having first and second rotating members (12, 13) coupled thereto, the rotating members being able to rotate about a common axis. One or more flexible blades (14, 15) having at least two ends are provided, one end being mounted on the first rotating member and another end being mounted on the second rotating member, so that they may rotate about the common axis. Actuating means are provided, being arranged to cause the ends of each blade to move closer together by movement of at least one of the rotating members along the common axis. The first and second rotating members are arranged to rotate relative to each other, said rotation allowing the flexible blades to coil around an axis.

A method for manufacturing a work piece is provided. The method includes preparing fiberglass in a mold, preparing a closed mold cavity around the fiberglass, flushing the closed mold cavity with an oxygen-free gas, injecting resin in the closed mold cavity, and curing the casted work piece. Furthermore, a work piece manufactured by the above method is provided.

The invention provides a method and system of monitoring bending strain on a wind turbine blade. The method in one aspect comprises: locating at least three strain sensors on the turbine blade, in use each strain sensor providing a strain measurement, the strain sensors located such that edgewise and flapwise bending can be determined from the strain measurements; calculating a plurality of resultant bending strains using the strain measurements; calculating an average resultant bending strain from the plurality of resultant bending strains; and calculating a confidence value for a first sensor based on a comparison of resultant bending strains derived from the strain measurement from the first sensor with the average resultant bending strain.

A method is provided for operating a wind turbine having an elongated stand apparatus, a generator rotatably mounted on the stand apparatus, and a rotor coupled to the generator via a rotor hub and the wind turbine also having an elongated rotor blade. A position of a radar system is determined with respect to the wind turbine and at least one area is determined for the rotational axis of the rotor as a function of the determined position which is not intended to be permanently assumed for alignment of the rotational axis of the rotor about the longitudinal axis of the stand apparatus. The wind turbine is operated with the at least one determined area not being permanently assumed for the alignment of the rotational axis of the rotor about the longitudinal axis of the stand apparatus.

A rotor blade assembly is disclosed. The rotor blade assembly includes a rotor blade having exterior surfaces defining a pressure side, a suction side, a leading edge, and a trailing edge extending between a tip and a root. The rotor blade further defines a span and a chord. The rotor blade includes a skin layer that includes the exterior surfaces. The rotor blade assembly further includes a passive spoiler assembly operable to alter a flow past an exterior surface of the rotor blade. The spoiler assembly includes a spoiler feature movable between a non-deployed position and a deployed position. Movement of the spoiler feature from the non-deployed position to the deployed position is caused by a change in an applied force to the spoiler feature by the skin layer.

A control apparatus C of a horizontal axis wind turbine apparatus WTG calculates the value en of a pitch angle command for each blade based on the rate of change ΨD of the azimuth angle Ψ of a Nacelle N and the rotor azimuth angle of the blades B1, B2 and B3, causes the rotor R to generated torque around the yaw axis by periodically controlling the angle change of the pitch angle of the blades B1, B2 and B3, and using that torque, controls the rate of change of the azimuth angle of the nacelle N. The value of that angle change is calculated as a value that increases as the inputted value of the rate of the change ΨD increases.

A wind turbine rotor includes a hub with a rotor blade mounted to a bearing of the hub wherein the rotor blade has a longitudinal axis extending in a radial direction relative to an axis of rotation of the hub, and the rotor blade is rotatable about its longitudinal axis whereby the pitch of the rotor blade is adjustable. The rotor blade has a tag such as an RFID tag fixed on the rotor blade at a predetermined angular position about the longitudinal axis of the rotor blade; and a sensor is fixed on the hub for contactless sensing of the tag when the tag is in a predetermined angular position about the longitudinal axis of the rotor blade. Repeated and accurate calibration of rotor blade pitch is hereby made possible.

A blade for use in water, the blade comprising an outer shell of fiber reinforced plastic defining a cavity. A substantial portion of the cavity is filled with a resin which adheres to the inner wall of the shell.

A mechanism compressing a sealing ring of a cooling circuit of blades of a turbine engine against a turbine wheel supporting the blades, the wheel supporting on a downstream surface thereof an annular flange positioned radially and defining with the surface a groove configured to house the sealing ring. The flange includes at least two cut-outs on the edge thereof located opposite the bottom of the groove, to form windows for axial insertion in the groove for claws supported by the circumference of the ring facing the groove of the wheel. The mechanism includes a bolt tab configured to be positioned in the groove between the surface of the wheel and the ring, and a clamping shaped to be supported by the surface of the wheel and to engage with the bolt to ensure that the ring is compressed against the flange.

An impeller of a centrifugal includes, a plurality of full blades provided from the fluid inlet part to the fluid outlet part of the impeller; a plurality of splitter blades provided on the hub surface, wherein the geometry of a flow entering part of the splitter blade is compatible with the complicated flow inside the compressor so that the evenly distributed flow rate distribution, the increased pressure ratio and the enhanced efficiency are achieved. The leading edge blade angle θ in the tip end part of the flow entering front-end-part of the splitter blade 7 in the area of the higher height level from the hub surface is further inclined smoothly toward the blade suction surface side Sb of the full blade 5 in comparison with the inclination standard curve, the increased inclination angle becoming smoothly greater in response to the increase of the height level.

A rotating airfoil component of a turbomachine, in which the component has an airfoil aligned in a spanwise direction of the component, a shank, and a platform therebetween oriented transverse to the spanwise direction. The platform has an outer radial surface adjacent the airfoil, and at least one recessed region defined in its outer radial surface. The recessed region extends opposite the spanwise direction from a platform plane that contains portions of the outer radial surface that are upstream and downstream from the recessed region. The recessed region is contiguous with an end wall of the platform and extends therefrom toward the airfoil. The recessed region defines a surface shape whose boundary is contained by the platform plane, and has a profile shape that extends from the end wall toward the airfoil. The recessed region is sized and shaped to increase the stiffness of the platform.

Embodiments of an axially-split radial turbine, as are embodiments of a method for manufacturing an axially-split radial turbine. In one embodiment, the method includes the steps of joining a forward bladed ring to a forward disk to produce a forward turbine rotor, fabricating an aft turbine rotor, and disposing the forward turbine rotor and the aft turbine rotor in an axially-abutting, rotationally-fixed relationship to produce the axially-split radial turbine.

Wind turbine rotor blades include a shell having a leading edge opposite a trailing edge, a structural support member that supports the shell and is disposed internal the wind turbine rotor blade between the leading edge and the trailing edge and extends for at least a portion of a rotor blade span length, and a resistive cellular support structure disposed at least partially about the wind turbine rotor blade that physically supports at least a portion of the wind turbine rotor blade and at least partially absorbs radar energy.

Wind turbine rotor blades with a reduced radar cross sections include a shell having a leading edge opposite a trailing edge, a structural support member that supports the shell and is disposed internal the wind turbine rotor blade between the leading edge and the trailing edge and extends for at least a portion of a rotor blade span length, wherein the structural support member comprises fiberglass, one or more cavities internal the wind turbine rotor blade, and a lightweight broadband radar absorbing filler material disposed in at least one of the one or more cavities to provide the reduced radar cross section.

A turbomachine blade or vane is made of composite material including fiber reinforcement obtained by three-dimensional weaving of yarns and densified by a matrix. The blade or vane includes a first portion constituting at least an airfoil exhibiting two faces each connecting a leading edge to a trailing edge, the first portion forming a single part with at least one second portion present only on one of the faces of the airfoil, the second portion constituting a portion of at least one of the following elements: a flowpath delimiting outer portion of an inner platform, an inner portion of an inner platform, a flowpath delimiting inner portion of an outer platform, and an outer portion of an outer platform, the portions of the fiber reinforcement corresponding to the first and the second portions of the blade being at least partially mutually imbricated, with yarns of the first portion of the fiber reinforcement penetrating into the second portion of the fiber reinforcement.

A seal assembly between a disc cavity and a turbine section hot gas path includes a stationary vane assembly and a rotating blade assembly downstream from the vane assembly and including a plurality of blades that are supported on a platform and rotate with a turbine rotor and the platform during operation of the engine. The platform includes a radially outwardly facing first surface, a radially inwardly facing second surface, a third surface, and a plurality of grooves extending into the third surface. The grooves are arranged such that a space is defined between adjacent grooves. During operation of the engine, the grooves guide purge air out of the disc cavity toward the hot gas path such that the purge air flows in a desired direction with reference to a direction of hot gas flow through the hot gas path.

Provided is a small-sized propeller windmill which can efficiently generate power even when a wing speed is low, has no possibility that the windmill is broken even when a strong wind blows, can stably ensure a weathercock direction of a base blade, and can suppress an environmental burden, in such a propeller windmill, the blade having a corrugated wing shape is supported in a cantilever manner by way of an elastic body, and the blade and the elastic body are made of paper or plastic. Further, to stably ensure the weathercock. direction of the base blade, a weathercock stabilizing mechanism is arranged behind the base blade.

A turbine rotor of a turbine includes a hub that serves as an axis of rotation, and a plurality of turbine blades. The turbine blades each have a line extending along a shroud-side edge of the turbine blade from the inlet to the outlet as a shroud line. The shroud line includes an entrance-side shroud line La that makes a small change from the inlet toward the outlet in a blade angle with respect to the axis of rotation, a center shroud line Lb that extends from the outlet side of the entrance-side shroud line La and makes a greater change than that of the entrance-side shroud line La, and an exit-side shroud line Lc that extends from the outlet side of the center shroud line Lb to the outlet and makes a smaller change than that of the center shroud line Lb.

Turbine blade assemblies of a turbine include airfoils that are mounted on bases. The leading and/or trailing edges of the bases are provided with curved portions. Likewise, curved portions may be provided on leading and/or trailing edges of the angle wings of a turbine blade assembly. Also, curved portions may be provided on the leading and/or trailing edges of nozzle assemblies of a turbine.

A support ring for a rotary assembly such as a propeller assembly includes support cups for receiving blade roots of propeller blades. The support cups are interconnected by bridging structures. Each bridging structure includes bridging walls which extend radially from a bridging web. The bridging structures thus have a channel-shaped cross-section. The bridging walls have a scalloped configuration at their radially outer edges. As a result of this configuration, the neutral axes of the bridging structures are straight, so that the support ring behaves, in structural terms, as a polygon.

In general terms, embodiments of the present invention relate to fan assemblies and methods for installing the same. For example, some embodiments of the present invention include a fan assembly that includes: (a) a rotational member; (b) a connection member structured for connection to the rotational member and including a body portion and a head portion; and (c) a blade arm defining an opening therein, such that the opening includes an open end portion and a closed end portion. In some embodiments, the connection member and the blade arm are configured such that, (a) when the blade arm is positioned in a support state, the head portion of the connection member rests against the blade arm to support the blade arm relative to the rotational member, and (b) when the blade arm is positioned in a secure state, the head portion of the connection member at least partially bears against the blade arm adjacent to the opening defined in the blade arm. Also, some of these embodiments of the present invention may be characterized as “easy install” fan assemblies because they include an “easy install” blade arm to motor connection, as described above, and/or an “easy install” blade arm to fan blade connection.

A liner for a composite blade of a gas turbine engine includes a metallic shoe, operable substantially to encase a blade root of a composite blade and defining an inner surface and an outer surface. The liner also includes a retention lug formed on the shoe and has inner and outer keys that project from opposed portions of the inner and outer surfaces. The keys engage corresponding recesses on a dovetail slot and a blade root to resist axial displacement of the composite blade.

A winglet for a rotor blade is disclosed. The winglet may generally include a winglet body extending between a first end and a second end. The winglet body may define a sweep and may have a curvature defined by a curve fit including a first radius of curvature and a second radius of curvature. The sweep between the first end and the second end may range from about 580 millimeters to about 970 millimeters. Additionally, the first radius of curvature may range from about 1500 millimeters to about 2500 millimeters and the second radius of curvature may range from about 1200 millimeters to about 2000 millimeters.

A wind turbine for generating electrical energy may include a wind turbine blade including a plurality of vortex generators integrally formed in the outer surface of the blade. The vortex generator includes a first component that defines a portion of the outer surface of the blade and a second component defining the shape of the vortex generator and at least partially surrounded by the first component. A method of manufacturing the wind turbine blade includes disposing a first plurality of layers of structural material over a mold main body and a removable insert member with a shaped cavity. A shaped plug is then pressed into the shaped cavity, and a second plurality of layers of structural material is disposed over the plug and the mold main body to complete manufacture of a wind turbine blade with a vortex generator.

A cooled turbine blade comprises a root for fixing the blade to rotor, an airfoil extending along a radial axis from the root, and a tip shroud disposed at a radially outward end of the airfoil. The tip shroud extends in a circumferential direction from the airfoil and defines, within itself, a core plenum and a peripheral plenum. The airfoil defines an aft airfoil cooling passage that extends radially through the airfoil proximate a trailing edge portion of the airfoil. The airfoil also defines an aft cooling inlet for providing an aft stream of cooling fluid to the aft airfoil cooling passage. The airfoil also defines at least one aft cooling exit for discharging the aft stream of cooling fluid from the aft airflow cooling passage to the peripheral plenum. The tip shroud defines at least one peripheral plenum vent for discharging the aft stream of cooling fluid.

Chemical liquid injector 100 includes two piston driving mechanisms 130 each moving a piston of a syringe forward, main injection condition determining section 171 determining injection conditions for a chemical liquid in main injection, test injection condition determining section 172 determining injection conditions for the chemical liquid in test injection performed prior to the main injection to inject a smaller injection amount of the chemical liquid than that in the main injection, and control section 161 creating an injection protocol in accordance with the injection conditions determined by test injection condition determining section 171 and main injection condition determining section 172 such that the chemical liquid is injected in a series of operations in which the test injection is performed, then a preset injection suspension time is present, and subsequently the main injection is performed, and further controlling operation of piston driving mechanisms 130 in accordance with the injection protocol.

A system and method for nodule boundary visualization superimposed on a scan image, including generating phantom image measurements of at least one synthetic calibration object in relation to a body to calibrate a scanner; acquiring a first image of a nodule on the calibrated scanner; computing and marking a boundary on the image; displaying the first image with the boundary superimposed over the first image; presenting the initial boundary to a user for modification where the user can add one or more modification points to the image to create a modified boundary that is encompassed by the one or more modification points; once the user has marked the one or more modification points on the image, computing an updated boundary that adapts to include the new points.

A machine-implemented display method that, with respect to a volume dataset being rendered, enables a user to navigate to any position in space and look in any direction. Preferably, the volume dataset is derived from a computer tomography (CT) or magnetic resonance imaging (MRI) scan. With the described approach, the user can see details within the dataset that are not available using conventional visualization approaches. The freedom-of-motion capability allows the user to go to places (positions) within the volume rendering that are not otherwise possible using conventional “orbit” and “zoom” display techniques. Thus, for example, using the described approach, the display image enables a user to travel inside physical structures (e.g., a patient's heart, brain, arteries, and the like).

A method is provided for constructing a tomographic reconstruction through the application of statistical inversion. Unknowns associated with points of a reconstruction grid are represented with components of a vector-valued variable. A next version of the vector-valued variable is repeatedly created by drawing for each component a value from a conditional distribution. The components of a so generated version of the vector-valued variable are used as the tomographic reconstruction. The components are divided into sets, so that components in a set represent unknowns associated with mutually independent points of the reconstruction grid, or into independent collections. For at least two components of a set or at least two collections, the drawing of values from a conditional distribution is performed in parallel in a computer-implemented process.

The present invention pertains to a system and method for X-ray imaging wherein a targeted fluence at the detector for projection images can be achieved at a plurality of projection angles around the imaging subject by control of exposure times implemented during image acquisition. Exposure time for a second projection image may be determined by the fluence in a first projection image, and in a third projection image by the fluence in a second projection image, where projection images are acquired within two degrees of one another. An acquisition parameter calculation can be configured to calculate acquisition parameters, such as said exposure times, to achieve the targeted fluence in projection images and can be coupled to a rotation controller that implements the acquisition parameters by controlling a relative angle between the imaging subject and X-ray image acquisition device.

A system and method is provided for estimating the local noise of CT images and denoising the images using a modified non-local means (NLM) algorithm that is adaptive to local variations of noise levels. A strategy for efficiently estimating the local noise of CT images is also described.

A mirror for the EUV wavelength range (1) having a layer arrangement (P) applied on a substrate (S), the layer arrangement having a periodic sequence of individual layers, where the periodic sequence has at least two individual layers—forming a period—composed respectively of silicon (Si) and ruthenium (Ru). Also disclosed are a projection objective for microlithography (2) including such a mirror, and a projection exposure apparatus for microlithography having such a projection objective (2).

An X-ray arrangement is suitable to record absorption, phase contrast, and dark field images of an object. The visibility of low absorbing specimens is improved and required radiation dose is reduced. The assembly includes an X-ray source; two or more gratings; a position-sensitive detector with spatially modulated detection sensitivity; a recorder for recording the images; an evaluator for evaluating the intensities for each pixel to identify the characteristic of the object for each individual pixel as an absorption and/or a differential phase contrast and/or an x-ray scattering dominated pixel. Images are collected by rotating from 0 to n or 2n either the sample or the assembly. The gratings are produced with planar geometry. The X-rays pass through the gratings parallel to the substrate. The grating structures extend along the X-ray path which determines the phase shift. The attenuation of the X-rays caused by the grating structures is no longer given by the thickness, but by the length of the grating structures.

A Compton radiation detection device for determining of Compton radiation of iron, includes a sensor and a filter arrangement. The filter arrangement is adapted such that the radiation emitted by a test object due to Compton scattering passes a nickel layer and an iron layer before being detected by the sensor. A dispersive ionization chamber includes an ionization chamber having a plurality off ionization volumes and a window. Each ionization volume includes an electrode. Radiation can enter through the window. The ionization volumes are arranged in a beam propagation direction behind each other. Radiation having lower energy is statistically absorbed in ionization volumes located more proximal to the window. Radiation having higher energy is statistically absorbed in the ionization volumes located more distal from the window.

A method for recording a four-dimensional angiography data record using an x-ray facility with a C-arm is proposed. Projection images are recorded from different projection directions at different time points of the cardiac cycle. A number of three-dimensional reconstruction image data records assigned respectively to a time segment of the cardiac cycle are reconstructed from the projection images and combined to form the four-dimensional angiography data record by temporal assignment in respect of the cardiac cycle. At least one recording parameter describing the temporal sequence is selected when recording the projection images as a function of cardiac stimulation performed to ensure a stable heart rate during recording so that the recording of the projection images takes place in such a manner that it is synchronized with the cardiac cycle.

A computer-implemented method for gain calibration is provided. The method includes sorting the calibration data of each pixel location from the offset-corrected X-ray image data into a sequence. The method also includes removing part of the calibration data from one end or both ends of the respective sequence for each pixel location. The method further includes averaging the calibration data remaining within each respective sequence to obtain an average pixel value for each pixel location. The method yet further includes generating a gain map based on the average pixel value for each pixel location.

A noninvasive, quantitative imaging technique is presented for detecting and diagnosing liver disease, such as cirrhosis. The technique includes: capturing scan data from a subject using computed tomography or another type of imaging method and extracting image data representing the liver from the scan data. Various measures of the liver may be obtained from image data and then used to compute random variables of a statistical model, where the model is predictive of a medical condition of the liver and comprised of random variables that are indicative of at least one of a shape or texture of the liver. Output from the statistical model provides an indication of an undesirable condition of the liver.

A method is provided. The method includes acquiring a first dataset at a first energy spectrum and a second dataset at a second energy spectrum. The method also includes extracting a metal artifact correction signal using the first dataset and the second dataset or using a first reconstructed image and a second reconstructed image generated respectively from the first and the second datasets. The method further includes performing metal artifact correction on the first reconstructed image using the metal artifact correction signal to generate a first corrected image.