Patents by Inventor Michael Ghebrebrhan

Michael Ghebrebrhan 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).

  • Patent number: 11822105
    Abstract: The disclosed subject matter relates to relate to fibers, textiles, fabrics, clothing and methods that are retroreflective including fibers having a hollow sheath that is filled with retroreflective particles.
    Type: Grant
    Filed: December 7, 2021
    Date of Patent: November 21, 2023
    Assignee: The Government of the United States, as represented by the Secretary of the Army
    Inventors: Michael Ghebrebrhan, Eric Wetzel
  • Patent number: 11123937
    Abstract: Disclosed is a retro-reflective thread 100 including an internal section 10; a plurality of fibers 12, each fiber comprising a respective longitudinal axis and a respective surface and each fiber comprising a first material that is at least partially optically transmissive, and wherein said plurality of fibers are configured with their respective longitudinal axes substantially co-linearly aligned with one another and said plurality of fibers are interconnected in series around said internal section and wherein a first part 12b of said respective surface of each of said plurality of fibers faces into said internal section; and a reflective material 14 provided on said first part of said respective surface of each of said plurality of fibers.
    Type: Grant
    Filed: August 20, 2019
    Date of Patent: September 21, 2021
    Assignee: U.S. Government as Represented by the Secretary of the Army
    Inventors: Michael Ghebrebrhan, Landa Hoke
  • Patent number: 10427367
    Abstract: Disclosed is a retro-reflective thread 100 including an internal section 10; a plurality of fibers 12, each fiber comprising a respective longitudinal axis and a respective surface and each fiber comprising a first material that is at least partially optically transmissive, and wherein said plurality of fibers are configured with their respective longitudinal axes substantially co-linearly aligned with one another and said plurality of fibers are interconnected in series around said internal section and wherein a first part 12b of said respective surface of each of said plurality of fibers faces into said internal section; and a reflective material 14 provided on said first part of said respective surface of each of said plurality of fibers.
    Type: Grant
    Filed: February 24, 2016
    Date of Patent: October 1, 2019
    Assignee: U.S. Government as Represented by the Secretary of the Army
    Inventors: Michael Ghebrebrhan, Landa Hoke
  • Patent number: 9116537
    Abstract: Inventive systems and methods for the generation of energy using thermophotovoltaic cells are described. Also described are systems and methods for selectively emitting electromagnetic radiation from an emitter for use in thermophotovoltaic energy generation systems. In at least some of the inventive energy generation systems and methods, a voltage applied to the thermophotovoltaic cell (e.g., to enhance the power produced by the cell) can be adjusted to enhance system performance. Certain embodiments of the systems and methods described herein can be used to generate energy relatively efficiently.
    Type: Grant
    Filed: May 20, 2011
    Date of Patent: August 25, 2015
    Assignee: Massachusetts Institute of Technology
    Inventors: Ivan Celanovic, Walker Chan, Peter Bermel, Adrian Y. X. Yeng, Christopher Marton, Michael Ghebrebrhan, Mohammad Araghchini, Klavs F. Jensen, Marin Soljacic, John D. Joannopoulos, Steven G. Johnson, Robert Pilawa-Podgurski, Peter Fisher
  • Patent number: 9057830
    Abstract: The present invention provides systems, articles, and methods for discriminating electromagnetic radiation based upon the angle of incidence of the electromagnetic radiation. In some cases, the materials and systems described herein can be capable of inhibiting reflection of electromagnetic radiation (e.g., the materials and systems can be capable of transmitting and/or absorbing electromagnetic radiation) within a given range of angles of incidence at a first incident surface, while substantially reflecting electromagnetic radiation outside the range of angles of incidence at a second incident surface (which can be the same as or different from the first incident surface). A photonic material comprising a plurality of periodically occurring separate domains can be used, in some cases, to selectively transmit and/or selectively absorb one portion of incoming electromagnetic radiation while reflecting another portion of incoming electromagnetic radiation, based upon the angle of incidence.
    Type: Grant
    Filed: July 19, 2011
    Date of Patent: June 16, 2015
    Assignee: Massachusetts Institute of Technology
    Inventors: Rafif E. Hamam, Peter Bermel, Ivan Celanovic, Marin Soljacic, Adrian Y. X. Yeng, Michael Ghebrebrhan, John D. Joannopoulos
  • Publication number: 20120037217
    Abstract: The present invention provides systems, articles, and methods for discriminating electromagnetic radiation based upon the angle of incidence of the electromagnetic radiation. In some cases, the materials and systems described herein can be capable of inhibiting reflection of electromagnetic radiation (e.g., the materials and systems can be capable of transmitting and/or absorbing electromagnetic radiation) within a given range of angles of incidence at a first incident surface, while substantially reflecting electromagnetic radiation outside the range of angles of incidence at a second incident surface (which can be the same as or different from the first incident surface). A photonic material comprising a plurality of periodically occurring separate domains can be used, in some cases, to selectively transmit and/or selectively absorb one portion of incoming electromagnetic radiation while reflecting another portion of incoming electromagnetic radiation, based upon the angle of incidence.
    Type: Application
    Filed: July 19, 2011
    Publication date: February 16, 2012
    Applicant: Massachusetts Institute of Technology
    Inventors: Rafif E. Hamam, Peter Bermel, Ivan Celanovic, Marin Soljacic, Adrian Y.X. Yeng, Michael Ghebrebrhan, John D. Joannopoulos
  • Publication number: 20110284059
    Abstract: Inventive systems and methods for the generation of energy using thermophotovoltaic cells are described. Also described are systems and methods for selectively emitting electromagnetic radiation from an emitter for use in thermophotovoltaic energy generation systems. In at least some of the inventive energy generation systems and methods, a voltage applied to the thermophotovoltaic cell (e.g., to enhance the power produced by the cell) can be adjusted to enhance system performance. Certain embodiments of the systems and methods described herein can be used to generate energy relatively efficiently.
    Type: Application
    Filed: May 20, 2011
    Publication date: November 24, 2011
    Applicant: Massachusetts Institute of Technology
    Inventors: Ivan Celanovic, Walker Chan, Peter Bermel, Adrian Y.X. Yeng, Christopher Marton, Michael Ghebrebrhan, Mohammad Araghchini, Klavs F. Jensen, Marin Soljacic, John D. Joannopoulos, Steven G. Johnson, Robert Pilawa-Podgurski, Peter Fisher
  • Publication number: 20100258174
    Abstract: A solar cell includes a thin film photovoltaic material structure used in absorbing light of a selective bandwidth. A multitude of dielectric front coatings are positioned on the thin film photovoltaic material structure so as to maximize admittance over the selected bandwidth. The thicknesses and indices of each of the front coatings are chosen by a global-optimization procedure to maximize the short-circuit current of the solar cell.
    Type: Application
    Filed: April 14, 2009
    Publication date: October 14, 2010
    Inventors: Michael Ghebrebrhan, Peter Bermel, Yehuda Avniel, John D. Joannopoulos, Steven G. Johnson
  • Patent number: RE47157
    Abstract: The present invention provides systems, articles, and methods for discriminating electromagnetic radiation based upon the angle of incidence of the electromagnetic radiation. In some cases, the materials and systems described herein can be capable of inhibiting reflection of electromagnetic radiation (e.g., the materials and systems can be capable of transmitting and/or absorbing electromagnetic radiation) within a given range of angles of incidence at a first incident surface, while substantially reflecting electromagnetic radiation outside the range of angles of incidence at a second incident surface (which can be the same as or different from the first incident surface). A photonic material comprising a plurality of periodically occurring separate domains can be used, in some cases, to selectively transmit and/or selectively absorb one portion of incoming electromagnetic radiation while reflecting another portion of incoming electromagnetic radiation, based upon the angle of incidence.
    Type: Grant
    Filed: June 12, 2017
    Date of Patent: December 11, 2018
    Assignee: Massachusetts Institute of Technology
    Inventors: Rafif E. Hamam, Peter Bermel, Ivan Celanovic, Marin Soljacic, Adrian Y. X. Yeng, Michael Ghebrebrhan, John D. Joannopoulos