Abstract: Embodiments of the present disclosure include improvements to millimeter wave backscatter RFID technology for rotational sensing. Embodiments of the present disclosure leverage the polarization mismatch of linearly polarized antennas to capture rotational motion with high accuracy. One embodiment described herein includes utilization of a four-antenna system, each featuring a different modulation frequency. This configuration allows for independent extraction of rotational information by observing the changes in signal amplitudes as the angle of rotation varies. With a polarization offset of 15° between successive antennas, the backscatter channels trace distinct curves, enabling the resolution of angular ambiguities.

Abstract: The disclosed technology includes device, systems, techniques, and methods for mm-wave backscattering and energy harvesting systems utilizing a Rotman-Lens-based rectenna system. An mm-wave backscattering and energy harvesting system can include one or more antenna, a Rotman Lens having a beam port side and an antenna side in electrical communication with the one or more antenna, and a switching network in electrical communication with the beam port side of the Rotman Lens. The switching network can be configured to cause the system to operate in either a backscattering mode or an energy harvesting mode.

Abstract: Device, systems, techniques, and methods for mm-wave energy harvesting utilizing a Rotman-Lens-based rectenna system. An energy harvester system can include one or more antenna, a Rotman Lens having a beam port side and an antenna side in electrical communication with the one or more antenna, and a rectifier network in electrical communication with the beam port side of the Rotman Lens. The energy harvester system can also include a power combining network in electrical communication with the rectifier network and having an output. The rectifier network can include a plurality of rectifiers connected to the beam port side of the Rotman Lens. Further, each of the plurality of rectifiers can include a rectifying diode. The power combining network can include a plurality of bypass diodes.

Abstract: The disclosed technology includes device, systems, techniques, and methods for mm-wave energy harvesting utilizing a Rotman-Lens-based rectenna system. An energy harvester system can include one or more antenna, a Rotman Lens having a beam port side and an antenna side in electrical communication with the one or more antenna, and a rectifier network in electrical communication with the beam port side of the Rotman Lens. The energy harvester system can also include a power combining network in electrical communication with the rectifier network and having an output. The rectifier network can include a plurality of rectifiers connected to the beam port side of the Rotman Lens. Further, each of the plurality of rectifiers can include a rectifying diode. The power combining network can include a plurality of bypass diodes.

Abstract: Techniques and apparatuses are described that implement localization and health monitoring. With the use of multiple backscatter tags, a reader can be implemented with a single antenna and have a relatively small footprint compared to other systems that utilize antenna arrays or multiple readers. Also, the backscatter tags can be implemented as passive devices and located at fixed positions. In this way, a single power source can be provided at the reader, and target angular resolutions can be realized without the additional mechanical complexities associated with other moving systems. Additionally, the backscatter tags can be implemented using relatively low-cost commercial off-the-shelf hardware. As such, performance of the reader can be readily customized with the purchase of additional backscatter tags.

Abstract: The disclosed technology includes device, systems, techniques, and methods for mm-wave backscattering and energy harvesting systems utilizing a Rotman-Lens-based rectenna system. An mm-wave backscattering and energy harvesting system can include one or more antenna, a Rotman Lens having a beam port side and an antenna side in electrical communication with the one or more antenna, and a switching network in electrical communication with the beam port side of the Rotman Lens. The switching network can be configured to cause the system to operate in either a backscattering mode or an energy harvesting mode.

Abstract: An exemplary embodiment of the present disclosure provides a backscattering RFID system comprising: a combined oscillator and reflection amplifier circuit comprising a first tunnel diode having an anode and a cathode; and a biasing circuit in communication with the anode and configured to bias the first tunnel diode in a negative differential resistance region; wherein the combined oscillator and reflection amplifier circuit is configured to modulate a RF interrogation signal to produce a backscatter signal.

Abstract: A system for using thin and energy-autonomous backscatter tags and corresponding sensing nodes may operate with 24 GHz backscatter reflectarray tags having low power consumption. A digital beam steering, frequency-modulated continuous wave (FMCW) radar may be used for detection, localization, identification and communications. The tags may include environmental sensors that are used to modulate backscatter waves for data communications directed to a reader or may digitally modulate the backscatter transmissions without sensor data for independent localization of each tag in a network.

Abstract: A system for using thin and energy-autonomous backscatter tags and corresponding sensing nodes may operate with 24 GHz backscatter reflectarray tags having low power consumption. A digital beam steering, frequency-modulated continuous wave (FMCW) radar may be used for detection, localization, identification and communications. The tags may include environmental sensors that are used to modulate backscatter waves for data communications directed to a reader or may digitally modulate the backscatter transmissions without sensor data for independent localization of each tag in a network.

Abstract: The disclosed technology includes device, systems, techniques, and methods for mm-wave energy harvesting utilizing a Rotman-Lens-based rectenna system. An energy harvester system can include one or more antenna, a Rotman Lens having a beam port side and an antenna side in electrical communication with the one or more antenna, and a rectifier network in electrical communication with the beam port side of the Rotman Lens. The energy harvester system can also include a power combining network in electrical communication with the rectifier network and having an output. The rectifier network can include a plurality of rectifiers connected to the beam port side of the Rotman Lens. Further, each of the plurality of rectifiers can include a rectifying diode. The power combining network can include a plurality of bypass diodes.

Abstract: This disclosure describes techniques for distributed storage of files that represent video content across different storage tiers to reduce the amount of computing resources used to store the files, while maintaining a low latency when responding to user requests to stream the video content. Video streaming services support the streaming of video content at different resolutions to support various user devices and/or user preferences. To provide streaming of a particular video content item at different resolutions, the video streaming services may store multiple files that represent the video content item for the different resolutions and stream at different bitrates to user devices. The techniques described herein include storing files configured to stream a video content item at different bitrates (and for different display resolutions) in a tiered storage structure to reduce the amount of computing resources taken to store the files.

Abstract: A system for using thin and energy-autonomous backscatter tags and corresponding sensing nodes may operate with 24 GHz backscatter reflectarray tags having low power consumption. A digital beam steering, frequency-modulated continuous wave (FMCW) radar may be used for detection, localization, identification and communications. The tags may include environmental sensors that are used to modulate backscatter waves for data communications directed to a reader or may digitally modulate the backscatter transmissions without sensor data for independent localization of each tag in a network.

Abstract: A method of refreshing a materialized view includes creating a materialized view based on a first result of a database query executed against a set of tables stored in a database and discovering a set of child storage objects associated with a parent storage object. The method also includes inserting, based on discovering the set of child storage objects, an entry into one or more tables of the set of tables, the entry including a child storage object of the set of child storage objects. The method further includes delaying a refresh of the materialized view until after the entry is inserted into the set of tables and then refreshing the materialized view, which is based on a second result of the database query executed against the set of tables.

Abstract: A method of refreshing a materialized view includes creating a materialized view based on a first result of a database query executed against a set of tables stored in a database and discovering a set of child storage objects associated with a parent storage object. The method also includes inserting, based on discovering the set of child storage objects, an entry into one or more tables of the set of tables, the entry including a child storage object of the set of child storage objects. The method further includes delaying a refresh of the materialized view until after the entry is inserted into the set of tables and then refreshing the materialized view, which is based on a second result of the database query executed against the set of tables.