Patents by Inventor Christopher J. Rukas

Christopher J. Rukas has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Publication number: 20240075815
    Abstract: A refuse vehicle includes a chassis, an energy storage device supported by the chassis and configured to provide electrical power to a prime mover, wherein activation of the prime mover selectively drives the refuse vehicle, a body for storing refuse therein supported by the chassis, a first hydraulic pump configured to convert electrical power into hydraulic power, a second first hydraulic pump configured to convert electrical power into hydraulic power, and a motor coupled to at least one of the body or the chassis and configured to drive the first hydraulic pump and drive the second hydraulic pump.
    Type: Application
    Filed: August 30, 2023
    Publication date: March 7, 2024
    Inventors: Jeffrey Koga, Emily Davis, Jerrod Kappers, Vince Schad, Robert S. Messina, Christopher K. Yakes, Vincent Hoover, Clinton T. Weckwerth, Zachary L. Klein, John Beck, Brendan Chan, Skylar A. Wachter, Nader Nasr, Chad K. Smith, Logan Gary, Derek A. Wente, Shawn Naglik, Mike J. Bolton, Jacob Wallin, Quincy Wittman, Christopher J. Rukas, Dylan Hess, Jason Rice, Zhenyi Wei, Bashar Amin, Catherine Linsmeier, Joshua D. Rocholl, Dale Matsumoto
  • Publication number: 20240052818
    Abstract: A pump system includes a housing defining a first internal volume and a second internal volume, a first piston positioned to separate the first internal volume into a first chamber and a second chamber, a second piston positioned to separate the second internal volume into a third chamber and a fourth chamber, a first inlet check valve configured to permit fluid flow into the first chamber, a second inlet check valve configured to permit fluid flow into the third chamber, a directional control valve (DCV) repositionable between (a) a first position where the DCV is configured to fluidly couple the second chamber to a high pressure fluid source and (b) a second position where the DCV is configured to fluidly couple the fourth chamber to the high pressure fluid source, and a relief valve configured to supply a fluid to the DCV through an orifice to move the DCV.
    Type: Application
    Filed: October 23, 2023
    Publication date: February 15, 2024
    Applicant: Oshkosh Corporation
    Inventors: Kai P. Schubart, Christopher J. Rukas, Patrick S. Dillman, Erik S. Ellifson, Aaron J. Rositch
  • Publication number: 20240001764
    Abstract: A refuse vehicle includes a battery configured to provide electrical energy to drive at least one of a plurality of wheels, a vehicle body supported by the chassis and defining a receptacle for storing refuse therein, and an electric power take-off system including a motor configured to power to a hydraulic system in response to receiving the electrical energy from the battery, an inverter configured to provide the electrical energy to the motor from the battery, a sensor configured to detect thermal energy within the inverter, and a controller configured to receive data from the sensor, wherein the controller is further configured to determine if the data from the sensor is greater than a critical operating condition and reduce a rate of electrical energy supplied to the motor in response to determining that the data from the sensor is greater than the critical operating condition.
    Type: Application
    Filed: September 13, 2023
    Publication date: January 4, 2024
    Applicant: Oshkosh Corporation
    Inventors: Jeffrey Koga, Emily Davis, Jerrod Kappers, Vince Schad, Robert S. Messina, Christopher K. Yakes, Vincent Hoover, Clinton T. Weckwerth, Zachary L. Klein, John Beck, Brendan Chan, Skylar A. Wachter, Nader Nasr, Chad K. Smith, Logan Gary, Derek A. Wente, Shawn Naglik, Mike J. Bolton, Jacob Wallin, Quincy Wittman, Christopher J. Rukas, Dylan Hess, Jason Rice, Zhenyi Wei, Bashar Amin, Catherine Linsmeier, Joshua D. Rocholl
  • Patent number: 11815078
    Abstract: A pump system includes a housing defining a first internal volume and a second internal volume, a first piston positioned to separate the first internal volume into a first chamber and a second chamber, a second piston positioned to separate the second internal volume into a third chamber and a fourth chamber, a directional control valve (DCV) fluidly coupled to the second chamber and the fourth chamber, a first relief valve fluidly coupled to the DCV via a first control line and the second chamber via a first sensing line, a first orifice positioned along the first sensing line, a second relief valve fluidly coupled to the DCV via a second control line and the fourth chamber via a second sensing line, and a second orifice positioned along the second sensing line.
    Type: Grant
    Filed: October 6, 2022
    Date of Patent: November 14, 2023
    Assignee: Oshkosh Corporation
    Inventors: Kai P. Schubart, Christopher J. Rukas, Patrick S. Dillman, Erik S. Ellifson, Aaron J. Rositch
  • Patent number: 11794584
    Abstract: A refuse vehicle includes a battery configured to provide electrical energy to drive at least one of a plurality of wheels, a vehicle body supported by the chassis and defining a receptacle for storing refuse therein, and an electric power take-off system including a motor configured to power to a hydraulic system in response to receiving the electrical energy from the battery, an inverter configured to provide the electrical energy to the motor from the battery, a sensor configured to detect thermal energy within the inverter, and a controller configured to receive data from the sensor, wherein the controller is further configured to determine if the data from the sensor is greater than a critical operating condition and reduce a rate of electrical energy supplied to the motor in response to determining that the data from the sensor is greater than the critical operating condition.
    Type: Grant
    Filed: October 25, 2021
    Date of Patent: October 24, 2023
    Assignee: Oshkosh Corporation
    Inventors: Jeffrey Koga, Emily Davis, Jerrod Kappers, Vince Schad, Robert S. Messina, Christopher K. Yakes, Vincent Hoover, Clinton T. Weckwerth, Zachary L. Klein, John Beck, Brendan Chan, Skylar A. Wachter, Nader Nasr, Chad K. Smith, Logan Gary, Derek A. Wente, Shawn Naglik, Mike J. Bolton, Jacob Wallin, Quincy Wittman, Christopher J. Rukas, Dylan Hess, Jason Rice, Zhenyi Wei, Bashar Amin, Catherine Linsmeier, Joshua D. Rocholl
  • Publication number: 20230303321
    Abstract: A refuse vehicle includes a chassis, a first energy storage device, a body, an electric power take-off system, and a subsystem coupled to the body and moveable using hydraulic power from the electric power take-off system. The first energy storage device (e.g., a battery) is supported by the chassis and is configured to provide electrical power to a prime mover. Activation of the prime mover selectively drives the refuse vehicle. The body is configured for storing refuse, and is supported by the chassis. The electric power take-off system is positioned on the body and includes an electric motor, a second energy storage device configured to provide electric power to the electric motor, and a hydraulic pump that is drive by the electric motor. The electric motor drives the hydraulic pump to convert the electrical power into hydraulic power.
    Type: Application
    Filed: May 31, 2023
    Publication date: September 28, 2023
    Applicant: Oshkosh Corporation
    Inventors: Jeffrey Koga, Emily Davis, Jerrod Kappers, Vince Schad, Robert S. Messina, Christopher K. Yakes, Vincent Hoover, Clinton T. Weckwerth, Zachary L. Klein, John Beck, Brendan Chan, Skylar A. Wachter, Nader Nasr, Chad K. Smith, Logan Gary, Derek A. Wente, Shawn Naglik, Mike J. Bolton, Jacob Wallin, Quincy Wittman, Christopher J. Rukas, Dylan Hess, Jason Rice, Zhenyi Wei, Bashar Amin, Catherine Linsmeier, Joshua D. Rocholl, Dale Matsumoto
  • Publication number: 20230294915
    Abstract: A refuse vehicle includes a chassis, an energy storage device, a vehicle body, an electric power take-off system, and a hydraulic component. The energy storage device is supported by the chassis and is configured to provide electrical power to a prime mover. Activation of the prime mover selectively drives the refuse vehicle. The vehicle body is supported by the chassis, and includes an on-board receptacle for storing refuse therein. The electric power take-off system is positioned on the vehicle body, and includes an electric motor configured to drive a hydraulic pump to convert electrical power received from the energy storage device into hydraulic power. An amount of electrical power at least one of received by and provided to the electric motor is limited by a controller to control an output characteristic of the hydraulic pump. The hydraulic component is in fluid communication with the hydraulic pump and configured to operate using hydraulic power from the electric power take-off system.
    Type: Application
    Filed: May 25, 2023
    Publication date: September 21, 2023
    Applicant: Oshkosh Corporation
    Inventors: Jeffrey Koga, Emily Davis, Jerrod Kappers, Vince Schad, Robert S. Messina, Christopher K. Yakes, Vincent Hoover, Clinton T. Weckwerth, Zachary L. Klein, John Beck, Brendan Chan, Skylar A. Wachter, Nader Nasr, Chad K. Smith, Logan Gary, Derek A. Wente, Shawn Naglik, Mike J. Bolton, Jacob Wallin, Quincy Wittman, Christopher J. Rukas, Dylan Hess, Jason Rice, Zhenyi Wei, Bashar Amin, Catherine Linsmeier, Joshua D. Rocholl
  • Patent number: 11702283
    Abstract: A refuse vehicle includes a chassis, an energy storage device, a body, and an electric power take-off system. The energy storage device (e.g., a battery) is supported by the chassis and is configured to provide electrical power to a prime mover. Activation of the prime mover selectively drives the refuse vehicle. The body is configured for storing refuse, and is supported by the chassis. The electric power take-off system is positioned on the body and includes an inverter, an electric motor, and a hydraulic pump that is drive by the electric motor. The inverter receives electrical power from the energy storage device and supplies electrical power to the electric motor. The electric motor drives the hydraulic pump to convert the electrical power into hydraulic power.
    Type: Grant
    Filed: November 30, 2021
    Date of Patent: July 18, 2023
    Assignee: Oshkosh Corporation
    Inventors: Jeffrey Koga, Emily Davis, Jerrod Kappers, Vince Schad, Robert S. Messina, Christopher K. Yakes, Vincent Hoover, Clinton T. Weckwerth, Zachary L. Klein, John Beck, Brendan Chan, Skylar A. Wachter, Nader Nasr, Chad K. Smith, Logan Gary, Derek A. Wente, Shawn Naglik, Mike J. Bolton, Jacob Wallin, Quincy Wittman, Christopher J. Rukas, Dylan Hess, Jason Rice, Zhenyi Wei, Bashar Amin, Catherine Linsmeier, Joshua D. Rocholl, Dale Matsumoto
  • Patent number: 11697552
    Abstract: A refuse vehicle includes a chassis, an energy storage device, a vehicle body, an electric power take-off system, and a hydraulic component. The energy storage device is supported by the chassis and is configured to provide electrical power to a prime mover. Activation of the prime mover selectively drives the refuse vehicle. The vehicle body is supported by the chassis, and includes an on-board receptacle for storing refuse therein. The electric power take-off system is positioned on the vehicle body, and includes an electric motor configured to drive a hydraulic pump to convert electrical power received from the energy storage device into hydraulic power. An amount of electrical power at least one of received by and provided to the electric motor is limited by a controller to control an output characteristic of the hydraulic pump. The hydraulic component is in fluid communication with the hydraulic pump and configured to operate using hydraulic power from the electric power take-off system.
    Type: Grant
    Filed: September 24, 2021
    Date of Patent: July 11, 2023
    Assignee: Oshkosh Corporation
    Inventors: Jeffrey Koga, Emily Davis, Jerrod Kappers, Vince Schad, Robert S. Messina, Christopher K. Yakes, Vincent Hoover, Clinton T. Weckwerth, Zachary L. Klein, John Beck, Brendan Chan, Skylar A. Wachter, Nader Nasr, Chad K. Smith, Logan Gary, Derek A. Wente, Shawn Naglik, Mike J. Bolton, Jacob Wallin, Quincy Wittman, Christopher J. Rukas, Dylan Hess, Jason Rice, Zhenyi Wei, Bashar Amin, Catherine Linsmeier, Joshua D. Rocholl
  • Publication number: 20230089417
    Abstract: A refuse vehicle includes a chassis, an energy storage device, a body, an electric power take-off system, and a disconnect. The energy storage device is supported by the chassis and is configured to provide electrical power to a prime mover. Activation of the prime mover selectively drives the refuse vehicle. The body is supported by the chassis and defines a receptacle for storing refuse. The electric power take-off system is positioned on the refuse vehicle, and includes a motor that is configured to drive a hydraulic pump to convert electrical power received from the energy storage device into hydraulic power. The disconnect is positioned between the energy storage device and the electric power take-off system and is configured to selectively decouple the electric power take-off system from the energy storage device.
    Type: Application
    Filed: September 17, 2021
    Publication date: March 23, 2023
    Applicant: Oshkosh Corporation
    Inventors: Jeffrey Koga, Emily Davis, Jerrod Kappers, Vince Schad, Robert S. Messina, Christopher K. Yakes, Vincent Hoover, Clinton T. Weckwerth, Zachary L. Klein, John Beck, Brendan Chan, Skylar A. Wachter, Nader Nasr, Chad K. Smith, Logan Gary, Derek A. Wente, Shawn Naglik, Mike J. Bolton, Jacob Wallin, Quincy Wittman, Christopher J. Rukas, Dylan Hess, Jason Rice, Zhenyi Wei, Bashar Amin, Catherine Linsmeier, Joshua D. Rocholl, Dale Matsumoto
  • Patent number: 11584185
    Abstract: A vehicle includes a suspension system having a first damper, a second damper, valves and a controller. Each of the first damper and the second damper include a housing and a piston sealingly interfaced with an inner diameter of the housing, dividing the damper into a first and second chamber. Each valve controls flow rate of fluid entering or exiting at least one of the first and second chamber of at least one of the first damper and the second damper. The controller controls the valves to control extension or compression of at least one of the first damper and the second damper based on at least one of a degree of roll of the vehicle during a turn of the vehicle and a degree of pitch of the vehicle during acceleration of the vehicle or a degree of pitch of the vehicle during deceleration of the vehicle.
    Type: Grant
    Filed: December 20, 2019
    Date of Patent: February 21, 2023
    Assignee: Oshkosh Corporation
    Inventors: Kai P. Schubart, Christopher J. Rukas, Erik S. Ellifson, Aaron J. Rositch
  • Publication number: 20230046193
    Abstract: A pump system includes a housing defining a first internal volume and a second internal volume, a first piston positioned to separate the first internal volume into a first chamber and a second chamber, a second piston positioned to separate the second internal volume into a third chamber and a fourth chamber, a directional control valve (DCV) fluidly coupled to the second chamber and the fourth chamber, a first relief valve fluidly coupled to the DCV via a first control line and the second chamber via a first sensing line, a first orifice positioned along the first sensing line, a second relief valve fluidly coupled to the DCV via a second control line and the fourth chamber via a second sensing line, and a second orifice positioned along the second sensing line.
    Type: Application
    Filed: October 6, 2022
    Publication date: February 16, 2023
    Applicant: Oshkosh Corporation
    Inventors: Kai P. Schubart, Christopher J. Rukas, Patrick S. Dillman, Erik S. Ellifson, Aaron J. Rositch
  • Patent number: 11529836
    Abstract: A vehicle includes a suspension system having a first damper, a second damper, and a controller. The dampers include housings and pistons sealingly interfaced with an inner diameter of the housing, dividing the damper into a first and second chamber. The suspension system includes proportional variable relief valves which control pressure of fluid entering or exiting one of the first and second chamber of one of the first and second damper. The controller controls the valves to control extension or compression of the first damper and extension or compression of the second damper based on a degree of roll of the vehicle during a turn of the vehicle or a degree of pitch of the vehicle during acceleration or deceleration of the vehicle. The first and second damper control a roll and pitch of the vehicle. The valves control a damping rate of one of the first and second damper.
    Type: Grant
    Filed: December 20, 2019
    Date of Patent: December 20, 2022
    Assignee: Oshkosh Corporation
    Inventors: Kai P. Schubart, Christopher J. Rukas, Erik S. Ellifson, Aaron J. Rositch
  • Patent number: 11480165
    Abstract: A pump system includes a pump assembly and a pump controller. The pump assembly includes a housing defining a first volume and a second volume separated by a divider, a first piston dividing the first volume into a first chamber and a second chamber, a second piston dividing the second volume into a third chamber and a fourth chamber, and a piston rod coupling the first piston and the second piston such that a movement of the first piston causes an equal movement of the second piston. The pump controller is configured to alternately supply a first fluid to the second chamber and the fourth chamber to cause the first piston and the second piston to reciprocate within the housing.
    Type: Grant
    Filed: September 19, 2019
    Date of Patent: October 25, 2022
    Assignee: Oshkosh Corporation
    Inventors: Kai P. Schubart, Christopher J. Rukas, Patrick S. Dillman, Erik S. Ellifson, Aaron J. Rositch
  • Publication number: 20220185582
    Abstract: A refuse vehicle includes a chassis, an energy storage device, a body, a first electric power take-off system, and a second electric power take-off system. The energy storage device is supported by the chassis and is configured to provide electrical power to a prime mover. Activation of the prime mover selectively drives the refuse vehicle. The body is supported by the chassis. The first electric power take-off system is coupled to at least one of the body and the chassis, and includes a first motor that is configured to drive a first hydraulic pump to convert electrical power received from the energy storage device into hydraulic power. The second electric power take-off system is coupled to at least one of the body and the chassis, and includes a second motor that is configured to drive a second hydraulic pump to convert electrical power received from the energy storage device into hydraulic power.
    Type: Application
    Filed: February 21, 2022
    Publication date: June 16, 2022
    Applicant: Oshkosh Corporation
    Inventors: Jeffrey Koga, Emily Davis, Jerrod Kappers, Vince Schad, Robert S. Messina, Christopher K. Yakes, Vincent Hoover, Clinton T. Weckwerth, Zachary L. Klein, John Beck, Brendan Chan, Skylar A. Wachter, Nader Nasr, Chad K. Smith, Logan Gary, Derek A. Wente, Shawn Naglik, Mike J. Bolton, Jacob Wallin, Quincy Wittman, Christopher J. Rukas, Dylan Hess, Jason Rice, Zhenyi Wei, Bashar Amin, Catherine Linsmeier, Joshua D. Rocholl, Dale Matsumoto
  • Publication number: 20220097961
    Abstract: A refuse vehicle includes a chassis, an energy storage device, a vehicle body, an electric power take-off system, and a hydraulic component. The energy storage device is supported by the chassis and is configured to provide electrical power to a prime mover. Activation of the prime mover selectively drives the refuse vehicle. The vehicle body is supported by the chassis, and includes an on-board receptacle for storing refuse therein. The electric power take-off system is positioned on the vehicle body, and includes an electric motor configured to drive a hydraulic pump to convert electrical power received from the energy storage device into hydraulic power. An amount of electrical power at least one of received by and provided to the electric motor is limited by a controller to control an output characteristic of the hydraulic pump. The hydraulic component is in fluid communication with the hydraulic pump and configured to operate using hydraulic power from the electric power take-off system.
    Type: Application
    Filed: September 24, 2021
    Publication date: March 31, 2022
    Applicant: Oshkosh Corporation
    Inventors: Jeffrey Koga, Emily Davis, Jerrod Kappers, Vince Schad, Robert S. Messina, Christopher K. Yakes, Vincent Hoover, Clinton T. Weckwerth, Zachary L. Klein, John Beck, Brendan Chan, Skylar A. Wachter, Nader Nasr, Chad K. Smith, Logan Gary, Derek A. Wente, Shawn Naglik, Mike J. Bolton, Jacob Wallin, Quincy Wittman, Christopher J. Rukas, Dylan Hess, Jason Rice, Zhenyi Wei, Bashar Amin, Catherine Linsmeier, Joshua D. Rocholl
  • Publication number: 20220097527
    Abstract: A refuse vehicle includes a battery configured to provide electrical energy to drive at least one of a plurality of wheels, a vehicle body supported by the chassis and defining a receptacle for storing refuse therein, and an electric power take-off system including a motor configured to power to a hydraulic system in response to receiving the electrical energy from the battery, an inverter configured to provide the electrical energy to the motor from the battery, a sensor configured to detect thermal energy within the inverter, and a controller configured to receive data from the sensor, wherein the controller is further configured to determine if the data from the sensor is greater than a critical operating condition and reduce a rate of electrical energy supplied to the motor in response to determining that the data from the sensor is greater than the critical operating condition.
    Type: Application
    Filed: October 25, 2021
    Publication date: March 31, 2022
    Applicant: Oshkosh Corporation
    Inventors: Jeffrey Koga, Emily Davis, Jerrod Kappers, Vince Schad, Robert S. Messina, Christopher K. Yakes, Vincent Hoover, Clinton T. Weckwerth, Zachary L. Klein, John Beck, Brendan Chan, Skylar A. Wachter, Nader Nasr, Chad K. Smith, Logan Gary, Derek A. Wente, Shawn Naglik, Mike J. Bolton, Jacob Wallin, Quincy Wittman, Christopher J. Rukas, Dylan Hess, Jason Rice, Zhenyi Wei, Bashar Amin, Catherine Linsmeier, Joshua D. Rocholl
  • Publication number: 20220097964
    Abstract: A refuse vehicle includes a chassis, an energy storage device, a body, and an electric power take-off system. The energy storage device (e.g., a battery) is supported by the chassis and is configured to provide electrical power to a prime mover. Activation of the prime mover selectively drives the refuse vehicle. The body is configured for storing refuse, and is supported by the chassis. The electric power take-off system is positioned on the body and includes an inverter, an electric motor, and a hydraulic pump that is drive by the electric motor. The inverter receives electrical power from the energy storage device and supplies electrical power to the electric motor. The electric motor drives the hydraulic pump to convert the electrical power into hydraulic power.
    Type: Application
    Filed: November 30, 2021
    Publication date: March 31, 2022
    Applicant: Oshkosh Corporation
    Inventors: Jeffrey Koga, Emily Davis, Jerrod Kappers, Vince Schad, Robert S. Messina, Christopher K. Yakes, Vincent Hoover, Clinton T. Weckwerth, Zachary L. Klein, John Beck, Brendan Chan, Skylar A. Wachter, Nader Nasr, Chad K. Smith, Logan Gary, Derek A. Wente, Shawn Naglik, Mike J. Bolton, Jacob Wallin, Quincy Wittman, Christopher J. Rukas, Dylan Hess, Jason Rice, Zhenyi Wei, Bashar Amin, Catherine Linsmeier, Joshua D. Rocholl, Dale Matsumoto
  • Patent number: 11254498
    Abstract: A refuse vehicle includes a chassis, a battery, a vehicle body, an electric power take-off system, and a lifting system. The chassis supports a plurality of wheels. The battery is supported by the chassis and is configured to provide electrical power to a first motor. Rotation of the first motor selectively drives at least one of the plurality of wheels. The vehicle body is supported by the chassis and defines a receptacle for storing refuse. The electric power take-off system is coupled to the vehicle body and includes a second motor configured to convert electrical power received from the battery into hydraulic power. The electric power take-off system is positioned within the receptacle. The lifting system is coupled to the vehicle body and is movable relative to the receptacle using hydraulic power from the electric power take-off system.
    Type: Grant
    Filed: May 21, 2021
    Date of Patent: February 22, 2022
    Assignee: Oshkosh Corporation
    Inventors: Jeffrey Koga, Emily Davis, Jerrod Kappers, Vince Schad, Robert S. Messina, Christopher K. Yakes, Vincent Hoover, Clinton T. Weckwerth, Zachary L. Klein, John Beck, Brendan Chan, Skylar A. Wachter, Nader Nasr, Chad K. Smith, Logan Gary, Derek A. Wente, Shawn Naglik, Mike J. Bolton, Jacob Wallin, Quincy Wittman, Christopher J. Rukas, Dylan Hess, Jason Rice, Zhenyi Wei, Bashar Amin, Catherine Linsmeier, Joshua D. Rocholl, Dale Matsumoto
  • Publication number: 20210380179
    Abstract: A vehicle includes a chassis, a front axle coupled to the chassis, a rear axle coupled to the chassis, a powertrain coupled to the chassis, a cab coupled to the chassis, a rear module coupled to the chassis behind the cab. The powertrain is configured to drive at least one of the front axle or the rear axle. The rear module is selectively reconfigurable between a plurality of configurations.
    Type: Application
    Filed: August 20, 2021
    Publication date: December 9, 2021
    Applicant: Oshkosh Corporation
    Inventors: Chad K. Smith, Robert S. Messina, Chris K. Yakes, Mark J. Charniak, Neil E. DeKarske, Mike A. Koenigs, Michael S. Poetter, Devon C. Palmer, Jesse D. Gander, Jason J. Zuleger, Megan N. Schultz, Troy D. Lind, Michael R. Yanacek, Kevin L. Pennau, Andrew L. Drach, Steve Volkman, Nathaniel J. Harter, Justin N. Rittenhouse, Peter K. Kramer, Annelise L. Kotenberg, Christopher J. Rukas