Abstract: An inverter apparatus includes heating components housed in an inverter main body and cooling fans for cooling the heating components. The inverter apparatus includes a fan unit case in which the cooling fans are housed as one integral unit, a housing space formed on an outer side of a ceiling surface of the inverter main body, and a fan cover that fixes the fan unit case. The fan unit case is slid to be housed in the housing space. The inverter apparatus makes it easier to replace cooling fans, reduce the number of components, enhance cooling efficiency, and secure high reliability.

Abstract: An entrainment heatsink system and method using distributed micro jets. Such a system and/or method utilize a pressurized primary flow through arrays of micro nozzles to entrain a much larger secondary flow to carry heat away from the heatsink. The bleed air from an aircraft engine represents an ideal pressurized air source for the primary flow with respect to such a heatsink. As such, the needed high-pressure primary flow is very small and can be delivered via thin air hoses, which has the flexibility to reach constraint spaces. In addition to the entrainment effect, the distributed micro jets also induce a high level of turbulence in the heatsink, significantly enhancing heat transfer and cooling performance.

Abstract: A combination heat sink form of a stack of radiation fins is disclosed. Each radiation fin has retaining flanges at two opposite lateral sides for securing another radiation fin. Each retaining flange has a bottom neck perpendicularly extending from the respective radiation fin, two pairs of vertically spaced retaining fingers respectively extending from two opposite lateral sides of the bottom neck in a parallel manner relative to the respective radiation fin for securing another radiation fin, a top retaining notch defined between the two pairs of vertically spaced retaining fingers above the bottom neck for accommodating the bottom neck of another radiation fin, and a retaining gap defined between each two vertically spaced retaining fingers for receiving another radiation fin.

Abstract: A card fixing structure includes a card holder for disposing at least one card. The card holder has an air deflector clamped on its one side. The air deflector catches the card to securely fix the card in the card holder, thereby reducing the number of fixing members and the manufacturing cost. Also, the card, the air deflector, and the card holder are easy to be assembled or disassembled.

Abstract: The invention relates to an arrangement for cooling equipment and network cabinets, particularly server cabinets, in which the fans are integrated into a door. The resulting fan door, in the closed position, covers an access area of the rear of the cabinet and longitudinally adjacent to the fan door is arranged in fixed manner an air-to-fluid heat exchanger, whilst covering a residual area of the rear of the cabinet and to which is articulated the fan door. The heat loss given off to a cooling liquid, particularly cold water, in the heat exchanger is removed via a pipe system outside the cabinet installation area and rigid connecting pipes of a gas-tight material can be used for the connection of the heat exchangers of the individual cabinets to the building-side pipe system.

Abstract: A system and method are provided for controlling a transfer of heat between circuit board components. Included is a circuit board with components mounted thereon. Also provided is a controllable heat transfer medium for controlling a transfer of heat between the components.

Abstract: A display unit and a vending machine having the same. The display unit includes a display panel to display an image, a circuit board to control the display panel, a board bracket installed at a rear of the display panel and formed with a receiving section to receive the circuit board, and a plurality of inlet holes and a plurality of outlet holes formed in opposite surfaces of the board bracket to allow external air to flow through the receiving section. The air travels through the inlet and outlet holes and passes through the receiving section in one direction to cool the display panel and the circuit board. Thus, the display unit is prevented from malfunctioning and the display panel is prevented from being degraded by heat even if tempered glass is installed at a front of the display panel.

Abstract: A heat dissipation device is used for removing heat from at least two adjacent first and second electronic devices in a computer enclosure. The heat dissipation device includes a first heat sink mounted on the first electronic device and a second heat sink mounted on the second electronic device. The first heat sink includes a base, a first fin unit mounted on the base and two heat pipes extending from the base outwardly. Second and third fin units engage with the two heat pipes, respectively. The first, second and third fin units are located adjacent to first, second and third openings of the computer enclosure, respectively. The second heat sink is located among the first, second and third fin units of the first heat sink.

Abstract: An improved cooling mechanism for a power electronics device is provided. More specifically, a cooling mechanism is provided wherein an air directing structure with a finite air-flow resistance is deployed in a cooling channel adjacent to a heatsink in a first cooling zone, such that some portion of the cooling air is forced through the heatsink while the rest of the cooling air bypasses the heatsink to provide additional cooling air to a second cooling zone. Additionally, the air-flow resistance of the air directing structure can be chosen so that the fan operates at its optimal point (maximum power input to the air).

Abstract: A method for controlling a system to work at an appropriate temperature provides a control manner allowing not only a temperature factor but also a time factor to be considered when a system is heated. When a heated value of the system reaches a certain preset value, a controller will then executes corresponding control modes to emit control signals to allow each of components of the system to obtain a better protection while being heated.

Abstract: One embodiment of the present invention sets forth an electronic assembly, which comprises a printed circuit board having at least one opening, an electronic component mounted on a first side of the printed circuit board, and a thermal dissipation structure including at least one heat sink having a first surface and a second surface. The first surface includes a first region coupled with a surface of the electronic component, and one or more second region provided with at least a heat dissipating member that is exposed through the opening on a second side of the printed circuit board.

Abstract: In one embodiment, an air guiding plate is attached to an enclosure with a plurality of vents defined therein. The air guiding plate includes a plurality of guiding holes defined therein. Each of the guiding holes is surrounded by a plurality of walls and includes an inlet with a large size, and an outlet with a small size. The outlets are in alignment with the vents of the enclosure. A size in cross section of each of the walls gradually decreases along a direction from the inlet to the outlet.

Abstract: A cooking appliance for cooking a foodstuff over a period of time including a shell having a heating cavity and a heating element to heat the heating cavity. A container is removably positionable within the heating cavity and includes a food cavity for receiving the foodstuff. A temperature probe is removably insertable into the foodstuff and a controller is mounted to the shell. The controller controls operation of the cooking appliance in a probe mode wherein the temperature probe is inserted into the foodstuff and transmits foodstuff temperatures to the controller for controlling the heating of the foodstuff, a program mode wherein the controller actuates the heating element to heat the container at a temperature for a selected amount of time and subsequently at a lower temperature and a manual mode wherein the controller actuates the heating element to heat the container at a selected temperature.

Abstract: An assembly for extracting heat from a housing for electronic equipment, the housing having a front, a back, two sides and a top. The assembly is defined by a back for the housing that defines an open area proximate the top, and an air passageway in fluid communication with the open area in the back, to conduct heated air exiting the housing through the open area away from the housing.

Abstract: A method and incorporated assembly is provided to enhance structural integrity and prevent interface deflection in a computer rack having a midplane and capable of housing a plurality of nodes. The assembly comprises at least one structural filler book capable of being disposed above or below said midplane where any node may be disposed having geometry and material properties to resist and counteract the plugging force of said node an causing a cancellation effect. The filler book have at least two horizontal supports being connected to one another via a vertical support and a plenum an air for directing air flow. The filler book is being secured to said rack or midplane via an engagement component disposed on one of its horizontal supports.

Abstract: A cooling structure for an electricity storage device includes: a secondary battery (10) generating heat; a DC-DC converter (20) generating heat in a quantity different from that of secondary battery (10); an exhaust path (30n) for passing air after cooling secondary battery (10) generating heat in a relatively small quantity, and led to the outside of a vehicle; an exhaust path (35n) for passing air after cooling DC-DC converter (20) generating heat in a relatively large quantity, and joining exhaust path (30n); and a circulation path (40) connected to exhaust path (30n) upstream of an air flow beyond a position (38) at which exhaust path (35n) joins, and led to the inside of a vehicle compartment. With this configuration, there is provided a cooling structure for an electricity storage device in which the suppression of both increase in temperature and decrease in inner pressure inside the vehicle compartment can be effectively achieved at the same time.

Abstract: An apparatus with some embodiments is described having a protrusion to provide air flow distribution to a computing device. In some embodiments, the apparatus may include a housing with one or more openings on each of the external surfaces of the housing, an air mover, and a protrusion to channel airflow to an inlet while restricting airflow from an outlet from being circulated back into the inlet. Furthermore, in some embodiments, the apparatus may be implemented on a computer system that includes one or more electronic components can generate thermal energy. Other embodiments are described.

Abstract: According to one embodiment, an electronic apparatus includes: a main body including a housing; a wiring connection port which is provided in the housing of the main body and which has an insertion passage into which a wiring connection plug is to be inserted; one lock section whose portion protrudes into the insertion passage for the wiring connection port and which becomes displaced toward a housing upon contact with the wiring connection plug; and an opening section which is formed at a position on the housing which opposes the one lock section, wherein the one lock section having become displaced upon contact with the wiring connection plug enters the inside of the opening section.

Abstract: An illustrative power-efficient data center is described for operating in an uncontrolled environment in one scenario. The data center includes an air moving system that applies unconditioned air to its resource items. The resource items are stripped down to provide a substantially minimum set of components for performing the data center's core functions. Various illustrative techniques for managing a power-efficient data center are also described.

Abstract: An exemplary heat dissipation device is provided for removing heat from a first electronic element and a second electronic element attached to a circuit board. The first electronic element is arranged at a side of the second electronic element. The heat dissipation device includes a heat sink attached to the CPU, a fan attached to the heat sink, and an air guide member attached to the second electronic element. The air guide member includes a guiding portion to guide air from the fan to the second electronic element.

Abstract: A data center cooling system includes a floor structure defining a below-floor warm-air plenum and an above-floor cool air plenum, a plurality of above-floor computer assemblies arranged to exhaust warmed air into the warm-air plenum, and one or more fan-coil arrangements to draw air from the warm-air plenum, cool the air, and provide the air to the cool air plenum. The volume of the above-floor cool air plenum and the below-floor warm air plenum may both be substantial so as to minimize changes in temperature from the failure of components in the system.

Abstract: An electronic unit housing includes (i) a receiving space for receiving a printed circuit board, (ii) at least one foot, which is designed to fasten the electronic unit housing onto a base, and is disposed to the side of the receiving space relative to a projection of the receiving space onto the base, and (iii) a venting device, which opens on the underside of the electronic unit housing facing the base.

Abstract: The storage subsystem is connected to an external device and comprises a storage device arrangement portion, on which a plurality of storage devices is arranged, and a control device that controls communications between the plurality of storage devices arranged on the storage device arrangement portion and the external device. The storage device arrangement portion is constituted such that the plurality of storage devices is arranged upright in the directions of two dimensions.

Abstract: In the disk array system, in the basic chassis, HDD modules are installed from a front surface in a front part of a backboard, and duplex CTL modules are installed up and down from a rear surface in a rear part, and duplex power source modules containing fans are installed in the left and right sides thereof. By the operation of the fans, in the rear part, the cooling air flows separately into each CTL module and into each power source module, and the cooling air having passed through the area of the duct by a block in the CTL module is drawn by the fans in the power source module through a ventilation hole and is then exhausted outside. The cooling air flow path to the plurality of ICs is divided by the block. The rotation speed of the fans is controlled by using a temperature sensor.

Abstract: A heat exchange structure includes elongated air ducts. Each air duct has a first opening and a second opening at two ends of the air duct to allow air to enter and exit the air duct, respectively. The heat exchange structure includes an exterior heat exchange surface and interior heat exchange surfaces, in which the exterior heat exchange surface is configured to receive thermal energy from heat generators that are mounted on the exterior heat exchange surface, and the exterior heat exchange surface dissipates a portion of the thermal energy received from the heat generators and transfers another portion of the thermal energy to the interior heat exchange surfaces. The interior heat exchange surfaces are in the elongated air ducts and configured to exchange thermal energy with air flowing in the air ducts, enhancing air flow in the air ducts by buoyancy of heated air.

Abstract: A cooling fan mounting structure for a flat display displaying an image on a screen based on a video signal is disclosed. The structure includes a chassis bracket attached to a rear of the display, and a type of fan holder to which the cooling is attached. The fan holder has an end with an insertion hole located in alignment with a screw hole and through which a screw is inserted to be fixed when the chassis bracket is attached, a positioning convex portion fitted into a positioning hole positioning the chassis bracket, and a locking claw bent into such a crank shape that the locking claw has a step located lower by a thickness of the chassis bracket and extends from the step, the positioning convex portion being inserted into the rectangle hole to be locked.

Abstract: A device generally intended to be used for providing an enclosure for a wall-mounted flat panel monitor. The device comprises an enclosure with a front face angled to match the mounting angle of the flat panel monitor. The device can further comprise a ventilation port to provide circulation around the flat panel monitor. The device can further comprise a cooling fan to improve airflow around the flat panel monitor. The device can be constructed from wood, plastic, metal, other suitable materials, or a combination of suitable materials. The device can provide a surface for attaching a flat panel monitor mounting bracket or can enable the mounting bracket to be attached to the adjoining wall.

Abstract: A waterproof ventilated enclosure for housing equipment is disclosed having the ability to channel water thru the enclosure without touching the equipment and further with the ability to provide active or passive ventilation to the equipment. In the preferred case, the equipment is a video monitor which may be mounted in an outdoor environment. The enclosure includes structures which separate liquid from air through the same or related ports, but prevents commingling.

Abstract: A fan module, including a housing for receiving a fan, a connector configured to mate with a connector housing, and a vibration pad configured to isolate vibrations of the fan from transferring through the fan module, wherein the fan module is configured to receive an alignment attachment standoff.

Abstract: A device adapted to optimize air duct flow in an electronic system including a printed circuit board configured to support one or more electronic components having various heights. The device includes an air duct including a rigid cross-sectional member, the air duct being adapted to facilitate air flow from an inlet port to an outlet port. Further, the rigid cross-sectional member includes an opening having an interior perimeter, the interior perimeter of the opening being attached to a flexible sheet by a pressure sensitive adhesive. The rigid cross-sectional member attached to the flexible sheet is adapted to compress one or more electronic components to the printed circuit board when the rigid cross-sectional member is mounted on the printed circuit board, and is configured to form an airtight enclosure to optimize air duct flow.

Abstract: A first sheet metal is configured into an enclosure and first and second pluralities of fingers are bent inwardly from the sheet metal to serve retention fingers, the first plurality frictionally engaging the outside of a honeycomb material to retain it in the enclosure while the second plurality serve as a limit stop to keep the honeycomb above the electrical device being protected. The honeycomb may have two sets of oppositely angled honeycomb cells, one capturing airflow from a fan and drawing it into the enclosure which the second set permits convective air currents to rise upwardly out of the enclosure. Alternatively, the cells of the honeycomb may be vertical convective air currents will flow under the wall of the enclosure, with or without the aid of a fan, the vertically directed cells of the honeycomb creating a chimney effect to dissipate the heat.

Abstract: An electronics housing system (S) adapted for electronic devices (D) includes a main chassis unit (M) and at least one removable module (10) mountable with the base unit (M) for supporting electronic circuitry components electro-optically coupled with the base unit (M). The removable module assembly (10) has a main body (12) that includes two opposing mounting edges (14, 16) and a connection edge (18). At least one of the mounting edges (14, 16) of the removable mounting assembly (10) has an opening (20) to receive a cooling air flow (F) into an interior cavity (22) of the main body (12) of the removable module (10). The main chassis (M) has a pair of opposing module mounting assemblies (24, 26) to receive a removable module (10) between the opposing module mounting assemblies (24, 26). The electronics rack wall (24, 26) includes a removable seal plate (32) to provide an air seal.

Abstract: A chassis assembly for an electronic device such as a storage device. The assembly includes a chassis for housing various functional components included in the electronic device. A sub-housing for containing a waste heat generating device, a device which requires temperature moderation, is included. The sub-housing defines a first airflow exhaust path for exhausting air in a first direction and a second airflow exhaust path for exhausting air in a second direction. The directing of airflow from the sub-housing is based on a chassis enclosure configuration such as to allow for the implementation of a common component including a component enclosure in a variety of chassis form factors.

Abstract: A chimney assembly is provided for an electrical switching apparatus, such as a circuit breaker including a housing and a number of poles. The chimney assembly includes a frame, an intake, a duct and an exhaust. A first side of the frame is coupled to the circuit breaker housing proximate the poles of the circuit breaker, and the intake and exhaust are respectively disposed at first and second ends of the frame. A first portion of the duct is coupled to the circuit breaker housing above the poles, and a second portion is coupled to the first side of the frame. The chimney assembly draws a volume of air through the intake into the circuit breaker housing, circulates the volume of air through the poles of the circuit breaker, and discharges the volume of air out of the circuit breaker housing through the duct and the exhaust.

Abstract: A heat dissipating device used for dissipating heat from a heat generating device (100) in a computer. The heat dissipating device includes a fan bracket (20), a fan (27) received in the fan bracket, and an air duct (50). The fan bracket defines a fan opening (25), and has a supporting member (233). The supporting member has a flat board (2333). A pair of retaining portions (2335) is formed on opposite edges of the flat board respectively. The flat board defines a retaining hole (2337) therein. The air duct defines an airflow passageway and has a top wall (51) and two opposite sidewalls extending from the top wall. A securing member (553) extends from one of the sidewalls is retained between the two retaining portions. A post (5535) protruding from the securing member is engaged in the retaining hole for cooperatively retaining the air duct to the fan bracket.

Abstract: A vacuum plasma generator (VPG) includes an output connector for electrical connection of the VPG to at least one electrode of a plasma chamber. The VPG includes a mains connector for connection of the VPG to a mains power supply, a mains input filter coupled to the mains connector, a voltage converter coupled to the mains input filter for generating an output signal, a voltage converter control input for connection to a voltage converter control, a shield that surrounds at least the voltage converter, the mains power supply, and the mains input filter, and a connection device that provides an electrical connection between the shield and the plasma chamber.

Abstract: In accordance with various embodiments, a printed structure of a flex circuit assembly includes a plurality of adjacent land portions formed on a heat conductive stiffener member and which support electrically conductive paths for connection to an integrated circuit. A corresponding plurality of separation channels are formed between the adjacent electrically conductive paths, and thermal energy generated by operation of the integrated circuit is transferred through the separation channels to the stiffener member. In some embodiments, the separation channels retain a fluid, such as air or a low density inert gas, which flows through the separation channels in response to rotation of a rotatable member adjacent the flex circuit assembly. In other embodiments, a dielectric, thermally conductive material fills the separation channels.

Abstract: A heat dissipation device, electrically connected to an intermittent power source, is used for dissipating heat generated by a heat-generating element on a circuit board. The heat dissipation device has at least one coil and at least one vibrating sheet. The coil is used to receive the intermittent power source to produce a magnetic field. One end of the vibrating sheet is fixed, and the other end is suspended over the coil. The suspended end flutters periodically under the magnetic force of the intermittent magnetic field, so as to produce an airflow.

Abstract: A display apparatus includes a casing, a display module, a cooling device, and a dust-proof device. The casing has first and second openings. The display module disposed in the casing has a display area exposed by the first opening and a non-display area corresponding to the second opening. The cooling device disposed at the non-display area in the casing has an air inlet corresponding to the second opening. The dust-proof device includes a body disposed at the non-display area in the casing, a cover disposed at the body, and a dust-proof element disposed therebetween. The body has first holes corresponding to the air inlet. The second opening exposes second holes of the cover. Each second hole overlaps at least one of the first holes. An airflow produced by the cooling device flows through the second opening, the second holes, the dust-proof element, the first holes, and the air inlet.

Abstract: A temperature isolation duct in a computer system comprising a chassis securing a circuit board and a fan system, wherein the fan system draws air through the chassis in an airflow direction, and a heat-generating component is mounted on the circuit board and exposed to the air flow. The hot air duct passively directs air heated by the heat-generating component from a single hot air duct inlet in direct downstream alignment with the heat-generating component to a single hot air duct outlet, wherein the hot air duct has a length to width aspect ratio of greater than four. A first thermal sensor is secured within, or direct alignment with, the hot air duct near the duct outlet for sensing the temperature of air flowing through the hot air duct and generating a first temperature signal. A controller is in electronic communication with the first thermal sensor for receiving the temperature signal and in electronic communication with the fan system for sending a fan speed control signal.

Abstract: A system and method are provided for cooling exhaust from a power center, such as in the event of an arc fault. In one embodiment, a system is provided that includes a power center having an enclosure, an exhaust duct coupled to the enclosure, and a phase change material disposed in the enclosure, the exhaust duct, or both, wherein the phase change material is configured to rapidly cool exhaust in response to a high temperature in the enclosure. A method is provided that includes cooling an exhaust at a high temperature from a power center by changing phase of a phase change material from a solid to a vapor. Another method is provided that includes providing a phase change material configured to cool an exhaust at a high temperature from a power center by changing phase from a solid to a vapor.

Abstract: A chassis of a portable electronic apparatus includes a heat sink assembly disposed therein and carries a keyboard on the top. The chassis has an air inlet and an air outlet on a first surface on the side opposite to the keyboard, which are respectively corresponding to an intake end and an exhaust end of the heat sink assembly. The air outlet extends from the first surface to a second surface connected to the first surface, and the second surface has an opening for disposing communication connectors, so as to adequately the heat sink assembly and the communication connectors.

Abstract: A cooling system for a computer is provided. In one implementation, the cooling system includes a heat spreader that is in thermal contact with a heat generating component in the computer, a frame casting, and a heat pipe to passively dissipate heat generated from the heat generating component in the computer to the frame casting. The heat pipe includes a first portion that is co-planar with and in direct contact with the heat generating component, and a second portion that is in thermal contact with the frame casting.

Abstract: A portable computer having a decorative cover is disclosed. The portable computer includes a main housing and a display side housing. The display side housing is openably and closably attached to the main housing. Several apertures for forced air cooling are formed in a bottom and a side of the main housing. The decorative cover is configured to cover surfaces of the display side housing and the main housing. A tray having a flat plate member and a spacer are attached to the bottom of the main housing. The spacer is configured to secure a predetermined space between the flat plate member and the bottom of the main housing to form an air flow passage for allowing outside air to pass through the apertures. The spacer is arranged between the decorative cover and the bottom of the main housing.

Abstract: An electronic device with an airflow guiding duct includes a chassis, an airflow guiding duct, and a top cover. The chassis includes a bottom wall and a sidewall perpendicular to the bottom wall. A circuit board is mounted on the bottom wall. A pair of securing members protrudes from a top of the sidewall. The airflow guiding duct includes a top wall and a plurality of securing slots defined in the top wall corresponding to the securing members, for the securing members being lockingly engaging in the securing slots, thereby limiting movement of the airflow guiding duct in directions parallel to the circuit board. The cover is mounted on the chassis and abuts against the top wall of the airflow guiding duct, for limiting movement of the airflow guiding duct in a direction perpendicular to the circuit board.

Abstract: A heat dissipation system for digital electronic signboard includes a first heat dissipation subsystem disposed in a main circuit board area of a digital electronic signboard, and a second heat dissipation subsystem disposed in a computer mainboard area of the digital electronic signboard. The main circuit board area has a plurality of heat dissipation fans disposed therein, wherein one heat dissipation fan is disposed at a side of the main circuit board area, while another heat dissipation fan is disposed at a side of a power supply and can be externally connected to an air guide pipe. The computer mainboard area can also have a plurality of heat dissipation fans disposed therein, wherein one heat dissipation fan is disposed at a side of the computer mainboard, while another heat dissipation fan is disposed on the top of a microprocessor of the computer mainboard.

Abstract: An electronic equipment enclosure includes a frame structure at least partially enclosed by a plurality of panels defining a compartment in which one or more electronic components are mounted and an exhaust air duct that is adapted to segregate hot air being exhausted from the compartment from cool air entering the compartment, thereby improving thermal management of the enclosure. The exhaust duct includes a lower duct section extending upward from the top panel of the compartment and an upper duct section telescoping upward from an upper end of the lower duct section. Each duct section includes four panels connected together by hinged corner fittings such that the section is collapsible. The upper duct section includes an outwardly flared portion.

Abstract: Some embodiments of a method, apparatus and computer system are described for vortex generator enhanced cooling. The computer system may include a housing and an apparatus. The apparatus may include one or more vortex generators coupled to a heat spreader and positioned in close proximity to an electronic component, and a flow of air to provide for an exchange of thermal energy, where the flow of air is provided by a configuration of the housing, and where the one or more vortex generators may promote turbulence to enhance the exchange of thermal energy of the electronic component. In some embodiments, an air mover may be used to increase the flow of air in the housing. Other embodiments are described.

Abstract: Cooling device for electronic components, in particular for power electronics in an aircraft, comprising an energy storage device which is in heat-conducting communication with at least one electronic component which is to be cooled, and which storage device is in the form of a material which performs a change in phase on absorbing the waste heat from the at least one electronic component.

Abstract: The extruded section forms a tunnel that is substantially rectangular and is provided with fins on at least one side of the rectangle. The fins allow air to flow outside the housing by natural convection in the extrusion directions. A side without fins serves as a base for fastening the housing and as a support for power electronic components of the power electronic device. The fins are machined transversely to the extrusion direction to form notches in the fins. The notches being aligned in succession to allow air to flow outside the housing by natural convection in the optimum direction.