A device for reducing sound from an air treatment unit includes, in one embodiment, a wall curb. The air treatment system includes a supply opening and a return opening. The wall curb includes a frame portion defining an interior chamber. A partition divides the interior chamber into a supply plenum in a first portion of the interior chamber and a return plenum in a second portion of the interior chamber. A curb supply opening is formed through the perimeter frame in communication with the supply plenum. A curb return opening is formed through the perimeter frame in communication with the return plenum. The curb return opening is positioned such that airflow through the return plenum is non-linear and a sound absorbing material may be positioned on at least some inside surfaces of the return plenum.

A cabinet structure for a switchgear assembly. The cabinet structure includes a cabinet having upper and lower vents and a breaker cradle for holding a circuit breaker having primary disconnects for connecting the circuit breaker to bus bars. The cabinet further includes an air passageway located between the upper and lower vents, wherein the air passageway extends vertically through the primary disconnects and the cabinet. Further, the cabinet includes a fan module having at least one fan for drawing outside air through the lower vent, the air passageway and the primary disconnects for cooling the primary disconnects.

A tractor cab HVAC system has a blower (22) which draws air into the system via air intake means (13) in the roof (14) of the cab (10). Ducting (15) in the roof of the cab directs air drawn in via the intake means down the center of one or more hollow adjacent pillars (16) of the cab to an air filter (18) contained in a housing (20) located between the adjacent pillars. Further ducting (19) extends from the air filter housing to an HVAC unit (11), the HVAC unit processing the air drawn into the system prior to discharging the processed air into the cab. The filter housing (20) is of generally rectangular form and is connected at opposite ends to the two hollow adjacent pillars (16) of the cab via inlet openings (20a) in the housing to allow the passage of intake air from the pillars to the filter (18).

The present invention is directed to apparatus and methods for cooling computer servers and/or electrical equipment in a rack device for data centers or telecommunication centers.

The invention relates to an optical device for imparting an asymmetrical light beam. The optical device comprises a lens (10) having an exit diopter (12) having an exit surface consisting of a convex surface (16) defining a curved rear portion (18) having a first curvature and a curved front portion (19) having a second curvature different from the first curvature. Furthermore the lens (10) comprises an entry diopter (11) including at least one concave lodging (13) for lodging at least one light source, the surface of the concave lodging (13) facing at least partly the curved rear portion (18).

A saddle type vehicle provided with a headlight stay for permitting a harness laying operation to be easily carried out. A motorcycle is provided with the headlight stay which is supported on a head pipe and extends toward the vehicle front side from the head pipe. A headlight unit is attached to the headlight stay. The headlight stay includes a first stay extending forward from the head pipe, in a side view of the vehicle and a second stay which is supported in a cantilever manner by a front portion of the first stay and extends rearwardly and upwardly. The headlight unit is partly disposed on the front side of the second stay and is disposed so as to overlap with the first stay.

The present invention relates to an aluminum extrusion heat sink structure and a corresponding backlight module. The aluminum extrusion heat sink structure comprises a light source connecting portion, a back plate connecting portion and a light guide plate support portion. The manufacture cost of the aluminum extrusion heat sink structure is lower, and the heat dissipation effect is better, so as to solve the technology problem that the volume of a traditional aluminum extrusion heat sink structure is larger caused the cost of the aluminum extrusion heat sink structure and the corresponding backlight module is higher.

A lead-free conductive paste composition contains a source of an electrically conductive metal, a fusible material, an optional additive, and an organic vehicle. An article such as a high-efficiency photovoltaic cell is formed by a process of deposition of the lead-free paste composition on a semiconductor substrate (e.g., by screen printing) and firing the paste to remove the organic vehicle and sinter the metal and fusible material.

A lamp includes an outer shell having heat conductivity, a base provided in the outer shell, and a cover provided in the outer shell. The outer shell has a light source support, and a heat radiating surface exposed to the outside of the outer shell. The light source support is formed integral with the heat radiating surface. A light source is supported on the light source support. The light source is heated during lighting, and thermally connected to the light source support. The light source is covered with the cover.

A method and apparatus for treating ocular disorders such as blepharitis, meibomitis, and dry eye syndrome. The method includes using an electromechanical device to move a swab relative to the eye to create cyclical movement that impacts debris present at the eyelid margin and effectively removes the debris from the eye to encourage healing and prevent further digression of the health of the eye. The apparatus is an electromechanical device that includes a mechanical drive unit operatively connected to a swab to create a precise relative movement of the swab to the eye to remove debris present therein.

The invention comprises a method for treating a prostate to alleviate prostate cancer, benign prostatic hyperplasia (BPH), and other conditions. The method involves inserting a tool to create a small self-sealing puncture site through tissue to gain access to a portion of a prostate, inserting a probe though the puncture site into the prostate, activating the probe to treat the prostate, withdrawing the probe and inspecting a surgical site for a flow of urine or semen to determine whether a sufficient amount of prostate tissue has been treated, and inspecting for hemostasis. The method may also include delivering a luminally protective sheath before inserting any instruments, using a template to guide insertion of the probe, and delivery of tamponading balloons to assist with attainment of hemostasis after the coring procedure.

A dermatological skin treatment device is provided. The device comprises a handpiece and a cutting tool, wherein the tool is inserted through the conduit and percutaneously inserted into a tissue disposed within a recessed area of the handpiece. The device and method cut the fibrous structures under the skin that cause cellulite at an angle substantially parallel to the surface of the skin and replace these structures with a non-cellulite forming structure by deploying a highly fibrous mesh through a single needle hole to create a highly fibrous layer directly or through wound healing processes. A tool is provided to aspirate excess fluid and tissue from the treatment area.

A system for treating heart disease, such as pulmonary hypertension or right heart failure, including an implantable component and external components for monitoring the implantable component is provided. The implantable component may include a compliant member, e.g., balloon, coupled to a reservoir via a conduit. Preferably, the compliant member is adapted to be implanted in a pulmonary artery and the reservoir is adapted to be implanted subcutaneously. The external components may include a clinical controller component, monitoring software configured to run a clinician's computer, a patient monitoring device, and a mobile application configured to run on a patient's mobile device.

Braid-balls suitable for aneurysm occlusion and/or parent vessel occlusion/sacrifice (e.g., in treating neurovascular defects) are disclosed. Especially for aneurysm treatment, but also for either one of the aforementioned treatments, the form of the ball is very important. In particular, the density of the device is paramount in applications where braid itself is intended to moderate or stop blood flow—allowing thrombosis within a volume formed by the ball.

Apparatus for sealing a puncture communicating with a blood vessel includes a porous carrier formed from lyophilized hydrogel or other material. The plug may include at least first and second hydrogel precursors and a pH adjusting agent carried by the porous carrier in an unreactive state prior to exposure to an aqueous physiological environment. Once exposed to bodily fluids, the carrier expands as the lyophilized material hydrates to enhance and facilitate rapid hemostasis of the puncture. When the plug is placed into the puncture, the natural wetting of the plug by bodily fluids (e.g., blood) causes the first and second precursors to react and cross-link into an adhesive or “sticky” hydrogel that aids in retaining the plug in place within the puncture.

An internal tissue puncture closure method and apparatus. The method and apparatus provide a folded sealing plug that provides more surface area than conventional plugs to more fully cover and seal an external situs of an internal tissue puncture. The folded sealing plug may have a weave pattern that tends to cause the sealing plug to corkscrew into the internal tissue puncture as it is compressed toward an anchor placed inside of the tissue puncture.

The present invention is specifically directed to a heart occlusion device with a self-centering mechanism. The heart occlusion device includes two separate uniquely shaped wires 12, 14, each forming shapes that mirror the respective wire's shapes. Each wire forms half-discs or quarter-discs that together form a distal disc and a proximal disc. In other versions, the device includes four separate wires, each mirroring its neighboring wire and forming a proximal and a distal quarter-disc. In the versions with four wires, the quarter-discs of each wire together form proximal and distal discs. The distal disc and proximal disc are separated by a self-centering waist. The proximal disc is attached to a hub comprising a screw mechanism. A similar hub is optional on the distal disc. The discs further include coverings which form a sealant to occlude an aperture in a tissue. The wires forming the discs have a shape-memory capability such that they can be collapsed and distorted in a catheter during delivery but resume and maintain their intended shape after delivery.

An injection-molding method for selectively manufacturing molded parts with and without a breakthrough is disclosed. A molded part with a breakthrough is manufactured by positioning a mold core in a mold cavity, whereas a molded part without breakthrough is manufactured by removing the mold core at least partly from the mold cavity. The mold cavity delimited by a nozzle-side mold platen and an ejector-side mold platen. The mold core is movable relative to at least one of the mold platens, in particularly the nozzle-side mold platen, in an advance direction, where the mold core is closer to the nozzle-side mold platen and an opposite withdrawal direction. At least one protective measure is provided for protecting the inner surface facing the mold cavity of the respective mold platen, in particularly the nozzle-side mold platen, from adverse mechanical effects during movement of the mold core in the advance direction.

In accordance with this invention a binder composition for treating particulate material to form a solid aggregate matrix is prepared by providing a urea formaldehyde precondensate; a polar solvent; additional urea; an acid or salt thereof, the acid or salt thereof being selected such as to render the pH of the binder composition to a value from 2.0 to 5.3; providing a sugar; providing a binding promoter for enhancing the binding between the binder composition and the particulate material; and mixing the above so as to form a binder composition. The binder composition is mixed with particulate material and allowed to set into a solid aggregate matrix over a period of longer than 30 minutes from being mixed with the said particulate material.

A system for a thermal manufacturing system including a heliostat and a mold. The heliostat includes at least one reflecting surface, a steering mechanism and a controller. The steering mechanism is coupled to the at least one reflecting surface and capable of directing at least a first portion of the at least one reflecting surface toward a first one of multiple, selectable focal points. The mold is located in a second one of the selectable focal points. A manufacturing method is also disclosed.

The invention relates to a method and a device for producing and treating plastic pellets. According to said method, a melt of the plastic material is granulated to give pellets, the pellets are cooled in a cooling fluid, the pellets are separated from the cooling fluid and the pellets are crystallized. The device according to the invention is characterized by comprising a control unit which monitors the crystallization step and controls the method in such a manner that, in case of a disturbance of crystallization, the pellets are supplied to an intermediate storage alter separation of the pellets from the cooling fluid and, as soon as the disturbance is removed, the pellets temporarily stored in the intermediate storage are supplied to crystallization and are crystallized.

A data creation device performing compression encoding on first frame images showing a view from a first viewpoint and second frame images showing a view from a second viewpoint generates a stream in an MPEG-2 format, and base-view/dependent-view video streams in a format conforming to an MPEG-4 MVC format. The stream in the MPEG-2 format is generated by performing compression encoding on the first frame images. The base-view video stream is a stream of dummy data having the same number of frames as and a smaller data amount than the stream in the MPEG-2 format. The dependent-view video stream is obtained by performing compression encoding on each frame of the second frame images, with reference to a frame of the stream in the MPEG-2 format to be presented at the same time as a frame of the base-view video stream corresponding to the frame of the second frame images.

Systems and methods are provided for generating a composite video based on a plurality of asynchronously recorded input video streams. A plurality of segments of the input video streams are identified. A number of the input video streams that were recording during the particular segment are determined. A video display configuration for the particular segment is determined based on the number of video streams that were recording, where the video display configuration includes a display sub-region for each of the number of video streams that was recording. A composite video is generated, where the composite video includes a portion of video associated with each of the segments, where the composite video portion associated with the particular segment is formatted according to the video display configuration and displays the video streams that were recording during the particular segment in the display sub-regions of the video display configuration.

Methods and apparatus for switching between a live video decoding and a recorded playback in a digital video and recording system. A received video data stream is transmitted to a first-in first-out video decoder buffer without first looping the video data stream through a playback buffer. The video data stream is transmitted from the video decoder buffer to a video decoder. If a “pause” command is received, the video data stream is transmitted to a first-in first-out playback buffer, while continuing to transmit the video data stream to the video decoder buffer. Transmission of the video data stream to the video decoder buffer is halted when the video decoder buffer fills up. The last byte of the video data stream that was transmitted to the video decoder buffer is marked. If a “play” command is received, the video data stored in the video decoder buffer is transmitted to the video decoder. The video data stored in the playback buffer is transmitted to the video decoder buffer starting at a point immediately after the data element that was marked previously.

A measuring apparatus for measuring a stereo video format includes an active space measuring circuit and a decision circuit. The active space measuring circuit is utilized for determining a position of an active space of a frame packing to generate an active space measuring result according to pixels values of a plurality of scan lines of the frame packing. The decision circuit is coupled to the active space measuring circuit, and is utilized for determining the stereo video format according to at least the active space measuring result.

A core drilling machine having an axial extending hollow drill shaft supported rotatably in a housing and rotated by means of a drive unit; a coaxial tool holder receiving an axially displaceable drill bit, the tool holder having a locking mechanism securing the drill bit in a rotationally fixed manner to the hollow drill shaft; wherein the hollow drill shaft is suitable for receiving a shaft of an interchangeable centre drill, the center drill axially supported against a first spring element; and an axial stop element preventing in a first position a complete displacement of the center drill into the interior of the hollow drill shaft and allows in a second position a complete displacement of the center drill into the interior of the hollow drill shaft; and an activation device for activating the first or second positions of the stop element.

A cutting head has a resilient male coupling member. The cutting head has a central resilience slit that extends between two major surfaces and opens out to the male coupling member and at least one lateral resilience slit that extends between the two major surfaces and opens out to a base surface. The central resilience slit and the at least one lateral resilience slit each have forwardmost points, located forward of the base surface. Also, a cutting tool that has a tool holder with the cutting head secured thereto. The tool holder has an insert pocket that includes a forward facing holder base abutment surface that has a female coupling member. In a locked position, the male coupling member is resiliently retained in the female coupling member. All points on the male coupling member are under deflection.

A cutting tool has a tool shank and a replaceable cutting head resiliently secured to the tool shank by an interference fit between a male fixation member of the cutting head and a female fixation member of the tool shank. The male fixation member has a resilience slit. In each cross section of the cutting tool taken perpendicular to an axis of rotation of the cutting tool through mutual abutment regions, the cross sectional profiles of the mutual abutment regions are arcuate sectors.

Low profile reamers and methods of use are provided which can, in general, allow a hole to be drilled in bone. In one embodiment, a low profile retractable bone reamer is provided having an elongate shaft with a cutting element disposed on a distal end of the elongate shaft that can be configured to drill a hole in bone. The elongate shaft and cutting element can have first and second longitudinally separated portions that are movably coupled to each other. The reamer can be configured to move between a retracted configuration, in which a the reamer has a reduced, low profile configuration, and a non-retracted configuration, in which both longitudinally separated portions of the cutting element can be positioned adjacent to one another to form a single cutting element.

A cutting head having a cutting end and an opposite coupling end along a longitudinal cutting head axis; having a cutting head length; and including two major surfaces and a peripheral surface. A male coupling portion extends rearwards from the coupling end, between a base portion and a rear surface, with a circumferential peripheral surface, having a coupling length. A flexibility slot extends from the rear surface opening to the major surfaces, along the cutting head axis, having a slot length and a head slot length. The coupling length is equal to or less than half the head slot length, and the slot length is equal to or greater than half the cutting head length. The cutting head is self-clamped into a tool shank with female coupling portion, by a friction fit between the male and female portion peripheral surfaces, causing the cutting head to elastically deform.

Provided is a technique to secure compositional or microstructural uniformity of a ceramic sintered body while increasing the area of the ceramic sintered boy, thus improving basic performance including non-linearity, maximum withstand energy and aging characteristics. A plurality of small varistor pieces 11 and insulating resin are kneaded and extruded for shaping, whereby a sheet-form varistor layer 13 can be formed where a plurality of small varistor pieces 11 are spaced from one another and are aligned on the same plane, and the adjacent small varistor pieces 11 are bonded via insulating resin.

Provided is a non-linear resistive element which enables to narrow an interval between a plurality of electrodes. A ceramic sheet (2) which constitutes the non-linear resistive element is configured by being supported in a sheet like form by a support member (22) composed of an insulating material. A plurality of ceramic pieces (21) are sectioned and arranged in each of a plurality of unit areas (23) which are apart from each other.

An electromagnetic field measuring apparatus capable of measuring an electromagnetic field for a minuscule area in which electronic devices are densely packed with a high sensitivity is provided. In an electromagnetic field measuring apparatus according to the present invention, the amplitude level of signal light (pf) is adjusted by the analyzer (34) by adjusting its angle with respect to the plane of polarization of the signal light (pf) based on an amplitude level control signal (eb) supplied from the calculation control unit (40). An amplitude level control signal (eb) is supplied from the calculation control unit (40) to the analyzer (34) based on the spectrum (ea) of an electric signal (ed) measured by an RF spectrum analyzer (39). The amplitude level ration between the carrier and the sideband contained in the signal light (ph) incident on the optical receiver (38) is controlled to a fixed value.

An axial resistance sheathed heater is presented. The axial resistance sheathed heater includes a retaining sheath having a first end and a second end and a resistance wire completely disposed within the retaining sheath. The heater further includes a first conductor rod partially disposed within the retaining sheath and extending beyond the first end of the retaining sheath, the first conductor rod in direct electrical communication and direct mechanical communication with the resistance wire; and a second conductor rod partially disposed within said retaining sheath and extending beyond the second end of the retaining sheath, the second conductor rod in direct electrical communication and direct mechanical communication with the resistance wire. The resistance wire, the first conductor rod and the second conductor rod comprise a circuit achieving a power to voltage rating of about 5000:24.

A piezoresistive sensor device and a method for making a piezoresistive device are disclosed. The sensor device comprises a silicon wafer having piezoresistive elements and contacts in electrical communication with the elements. The sensor device further comprises a contact glass coupled to the silicon wafer and having apertures aligned with the contacts. The sensor device also comprises a non-conductive frit for mounting the contact glass to a header glass, and a conductive non-lead glass frit disposed in the apertures and in electrical communication with the contacts. The method for making a piezoresistive sensor device, comprises bonding a contact glass to a silicon wafer such that apertures in the glass line up with contacts on the wafer, and filling the apertures with a non-lead glass frit such that the frit is in electrical communication with the contacts. The use of a lead free glass frit prevents catastrophic failure of the piezoresistive sensor and associated transducer in ultra high temperature applications.

A heater assembly includes one or more first heating elements, the one or more first heating elements being characterized by a positive temperature coefficient; and one or more second heating elements, the one or more second heating elements comprising resistance wire elements. The one or more second heating elements are positioned in proximity to the one or more first heating elements such that at least one of the one or more second heating elements is configured to, upon being powered on, pre-heat at least one of the one or more first heating elements before the at least one first heating element is powered on.

A surface mount chip resistor for increasing power handling capabilities of radio frequency (RF) circuits and for minimizing parasitic capacitance and inductance effects, the chip resistor includes a ceramic substrate having a main portion and an outrigger. A resistor element is between an input contact and an output contact on a top surface of the main portion. A ground plane attachment area is on a top surface of the outrigger. The ground plane attachment area is mounted to a ground plane of a circuit board to provide a heat pathway for dissipating heat generated by the resistor element.

Provided is a non-linear resistive element which improves the degree of freedom of design of its mounting space. A ceramic sheet 10 which constitutes the non-linear resistive element is configured by a plurality of ceramic pieces 11 being consolidated in a plate like form by an insulating resin 12. One or a plurality of ceramic pieces 11 configure each of a plurality of conductive paths which penetrate the ceramic sheet 10 in a thickness direction thereof, and the ceramic pieces 11 which configure both ends of the conductive paths partially projects from the insulating resin 12.

A system and method of painting parts of large dimensions that present a certain amount of flexibility that makes their shape geometrically unstable in the event of being moved. The surface of a part is moved in front of a paint spray device by an arm of a robot, while the spray device remains stationary relative to the robot and while the part is being deformed. Other elements include a gripper for gripping parts of large dimensions, the gripper being adapted to implement the method; an installation; and a booth for performing surface treatment of parts.

A device for cleaning trays comprises a tub that has a bottom and a wall. The tub is dimensioned such that a baking tray can be placed therein. The device further comprises a dish drain that can be placed in the tub. Said device for cleaning a baking tray uses only a small amount of space in a kitchen and is easy to handle. In fact, in a typical kitchen that already has a dish drain, the device requires no additional space.

A fluidic structure has a first chamber having a connection to a fluid reservoir and a connection to an array of apertures, the chamber forming a flow path between the fluid reservoir and the array of apertures, a second chamber having a connection to at least one vent connected to an atmosphere external to the fluidic structure, and at least one path between the first chamber and the second chamber.

An ink jet recording head includes a substrate having a plurality of discharge energy generation elements and having an ink supply port, a protective film provided on the substrate and configured to protect wiring connected to the discharge energy generation elements, and an ink discharge port forming member, wherein the protective film has a protruding portion, wherein the ink discharge port forming member has a beam-like protrusion, wherein the beam-like protrusion has a reinforcing rib, and wherein a separation film containing gold is formed at a portion where the protruding portion and the reinforcing rib are held in close contact with each other.

A full-line printhead includes a base in which a plurality of substrates each including arrayed print elements are arranged in the arrayed direction has the following arrangement. The base includes a terminal for inputting a first differential signal, a first pair of lines for transferring the first differential signal from the terminal to the substrates, a terminal for inputting a second differential signal, and a second pair of lines for transferring the second differential signal from the terminal to the substrates. Each substrate includes a first amplifier for amplifying the first differential signal transferred via the first pair of lines, and a second amplifier for amplifying the second differential signal transferred via the second pair of lines. Control is performed to change the gain of the first amplifier based on a control signal from outside.

An optical print head, including: a light emitting substrate which includes a light emitting element on a base; a rod lens array which focuses light emitted from the light emitting element onto an image carrier, the rod lens array having a larger linear expansion coefficient than the base of the light emitting substrate; and expansion suppressing members which are attached to both lateral surfaces of the rod lens array in a direction that is perpendicular to an optical axis direction and is a shorter direction, each of the expansion suppressing members having a smaller linear expansion coefficient than the rod lens array.

For each totally black pixel of image data to be printed using a fluid-ejection printing device, it is determined whether the pixel is part of a line feature or an area fill feature of the image data. Where the pixel is part of a line feature, a first printing mask selected that is optimized for printing line features. Where the pixel is part of an area fill feature, a second printing mask is selected that is optimized for printing area fill features. Each mask specifies a number of fluid droplets to be printed and positions where the fluid droplets are to be printed. The selected mask is applied to the pixel. The pixel is printed using the mask that has been applied. The fluid-ejection printing device prints the pixel by ejecting the number of fluid droplets specified by the mask at the positions specified by the mask.

A liquid ejecting head comprises a pressure generation chamber communicating with a nozzle opening, a vibrating wall provided as one surface of the pressure generation chamber and vibrates so that ejects the liquid from the nozzle opening, and a resin portion having a recessed arc-shape and formed in a corner of the pressure generation chamber and formed of a resin material having a Young's modulus of less than or equal to 10 GPa. A ratio r/w of a radius r of the surface of the resin portion to a width w of the pressure generation chamber defined by the vibrating wall is greater than or equal to 0.017 and less than or equal to 0.087.

There are provided a substrate for an inkjet head and an inkjet head wherein in a case where a protection layer of heating resistors is energized, an electrical connection with portions around the protection layer is more reliably cut. A first protection layer provided for the substrate for an inkjet head includes individual sections provided at positions corresponding to the plurality of heating resistors and a common section which commonly connects the plurality of individual sections. The individual sections and the common section are connected via connect sections which are eluted and connect in a case where an electrochemical reaction occurs between the connect sections and ink when electricity flow therethrough, so that an electrical connection between the individual sections and the common section is cut.

A piezoelectric element comprises a piezoelectric layer made of a perovskite compound containing sodium, potassium, lithium, niobium and tantalum and bismuth manganate and electrodes for applying a voltage to the piezoelectric layer.

Provided is a technique capable of suppressing the deterioration in azimuth resolution and distance resolution in even a modulated and transmitted or received signal or a signal reflected by an object and varied in intensity when acquiring waveform information. A measurement device comprise: a plurality of sensors which receive waves propagating through a space; and a sampling timing calculation means which obtains, on the basis of the relative positions of the sensors and the velocities of the waves, the difference between the arrival times of the waves received by the respective sensors and calculates, for each sensor, sampling timing for acquiring the waveform information relating to the waves, on the basis of the difference between the arrival times.

A method of determining a filling level of a product contained in a tank using a level gauge system, comprising the steps of: transmitting a first signal towards a surface of the product; receiving a first echo signal; determining a present echo characteristic value based on the first echo signal; and comparing the present echo characteristic value and a stored echo characteristic value. If a difference between the present echo characteristic value and the stored echo characteristic value is greater than a predefined value, the method further comprises transmitting at least a second transmit signal towards the surface; receiving at least a second echo signal; and determining the filling level based on the at least second electromagnetic echo signal.