Abstract: An orthogonal frequency-division multiple access (OFDMA)-based backscatter system is provided, including an analog portion and a digital logic portion. The analog portion includes an antenna, radio frequency switches, an envelope detection circuit, and a transmission line. The digital logic portion includes an inverse discrete Fourier transform (IDFT)-based digital frequency synthesis module. Two outputs of the digital logic portion control all of the radio frequency switches, and the envelope detection circuit provides an input of the digital logic portion. OFDMA backscatter tags designed can operate on any given subchannel without hardware being re-powered and modified, and can operate at a specified symbol rate. The system provides a networking physical layer foundation for a large amount of OFDMA backscatter tags, and satisfies the growing Internet of Things capacity requirements.

Abstract: An orthogonal frequency-division multiple access (OFDMA)-based backscatter system is provided, including an analog portion and a digital logic portion. The analog portion includes an antenna, radio frequency switches, an envelope detection circuit, and a transmission line. The digital logic portion includes an inverse discrete Fourier transform (IDFT)-based digital frequency synthesis module. Two outputs of the digital logic portion control all of the radio frequency switches, and the envelope detection circuit provides an input of the digital logic portion. OFDMA backscatter tags designed can operate on any given subchannel without hardware being re-powered and modified, and can operate at a specified symbol rate. The system provides a networking physical layer foundation for a large amount of OFDMA backscatter tags, and satisfies the growing Internet of Things capacity requirements.

Abstract: An object tracking method, device, backend, and medium. The object tracking method includes: obtaining raw sensor data sent by a sensor array, the sensor array including a plurality of magnetic field sensors, the raw sensor data including magnetic field strengths at locations of the magnetic field sensors; determining the presence of a target magnet based on the raw sensor data, where the target magnet is a permanent magnet provided on a target object; when the target magnet is present, tracking the target magnet based on the raw sensor data. The method enables permanent-magnet-based object tracking.

Abstract: A cooling control device comprises a compressor, a condenser, a material reservoir evaporator, a freezing cylinder refrigeration inlet conduit, and a freezing cylinder refrigeration outlet conduit. An outlet end of the condenser is connected to a condenser outlet pipe. The condenser outlet pipe is in communication with three branch pipes, which are a freezing cylinder refrigeration pipe, a material reservoir pre-cooling pipe and a material reservoir freshness-preserving pipe arranged in parallel. The freezing cylinder refrigeration pipe is in communication with the freezing cylinder refrigeration inlet conduit. The material reservoir pre-cooling pipe and the material reservoir freshness-preserving pipe are in communication with an inlet end of the material reservoir evaporator. An outlet end of the material reservoir evaporator and the freezing cylinder refrigeration outlet conduit are respectively in communication with the compressor.

Abstract: A mouthfeel maintaining method of an ice cream machine is provided. The ice cream machine is equipped with a freezing cylinder, a stirring device, a main refrigeration system, and a control system. When the ice cream material in the freezing cylinder is in a forming solid stage, the control system controls the ice cream machine to enter a mouthfeel maintaining state. The forming solid stage is: a stage from when all the ice cream material in the freezing cylinder is converted into all-solid ice cream until the preset hardness or the preset viscosity value is reached. The mouthfeel maintaining state is as follows that: the main refrigeration system refrigerates the ice cream material in the freezing cylinder according to the refrigeration capacity close to the lower limit refrigeration capacity. Moreover, the ice cream machine can discharge the all-solid ice cream in the freezing cylinder in the mouthfeel maintaining state.

Abstract: The invention belongs to the technical field of automatic equipment for pressure retention of earphone voice-operated motherboard adhesive and SR, and discloses a pressure-retaining automata for voice-operated motherboard adhesive and SR, which consists of a rack, an independent belt module arranged on the rack, opposite sensors fixed on each belt module, a guide module set on the belt module, and a stop module disposed on the guide module. The invention realizes high automation and high positioning accuracy.

Abstract: A cooling control device comprises a compressor, a condenser, a material reservoir evaporator, a freezing cylinder refrigeration inlet conduit, and a freezing cylinder refrigeration outlet conduit. An outlet end of the condenser is connected to a condenser outlet pipe. The condenser outlet pipe is in communication with three branch pipes, which are a freezing cylinder refrigeration pipe, a material reservoir pre-cooling pipe and a material reservoir freshness-preserving pipe arranged in parallel. The freezing cylinder refrigeration pipe is in communication with the freezing cylinder refrigeration inlet conduit. The material reservoir pre-cooling pipe and the material reservoir freshness-preserving pipe are in communication with an inlet end of the material reservoir evaporator. An outlet end of the material reservoir evaporator and the freezing cylinder refrigeration outlet conduit are respectively in communication with the compressor.

Abstract: An acquisition method for data in a wireless body area network and a central device, the acquisition method includes: a central device acquiring topology structure information of a network formed by node devices, and according to the topology structure information of the network determining time slot information about a super-frame; after time slot information is published, acquiring service data packets of an Exclusive Access Phase EAP, a Random Access Phase called RAP and a managed access MAP1 phase in sequence; acquiring packet loss information in the MAP1 phase, and allocating time slots of a managed access MAP2 phase according to the packet loss information; and after the allocated time slots are published, acquiring service data packets in the MAP2 phase according to the allocated time slots. The technical solution can realize the reliable transmission of data in a wireless body area network and reduce the power consumption and time delay.

Abstract: Provided are information interaction methods, devices and system for a Wireless Body Area Network (WBAN). The method includes that: a Hub sends beacon frames to nodes according to a preset superframe structure and receives, according to a preset superframe structure, information sent by the nodes. The preset superframe structure includes three phases. The first phase includes a first beacon period, a first timeslot period and a second timeslot period, the first timeslot period being used by nodes to send an emergency service and the second timeslot period being used by nodes to send an ordinary service. The second phase includes a second beacon period and a third timeslot period, the third timeslot period being used by nodes to complementarily send a service. The third phase includes a fourth timeslot period, the fourth timeslot period being used by nodes to send a sleep application and/or an access application.

Abstract: Provided are information interaction methods, devices and system for a Wireless Body Area Network (WBAN). The method includes that: a Hub sends beacon frames to nodes according to a preset superframe structure and receives, according to a preset superframe structure, information sent by the nodes. The preset superframe structure includes three phases. The first phase includes a first beacon period, a first timeslot period and a second timeslot period, the first timeslot period being used by nodes to send an emergency service and the second timeslot period being used by nodes to send an ordinary service. The second phase includes a second beacon period and a third timeslot period, the third timeslot period being used by nodes to complementarily send a service. The third phase includes a fourth timeslot period, the fourth timeslot period being used by nodes to send a sleep application and/or an access application.

Abstract: An acquisition method for data in a wireless body area network and a central device, the acquisition method includes: a central device acquiring topology structure information of a network formed by node devices, and according to the topology structure information of the network determining time slot information about a super-frame; after time slot information is published, acquiring service data packets of an Exclusive Access Phase EAP, a Random Access Phase called RAP and a managed access MAP1 phase in sequence; acquiring packet loss information in the MAP1 phase, and allocating time slots of a managed access MAP2 phase according to the packet loss information; and after the allocated time slots are published, acquiring service data packets in the MAP2 phase according to the allocated time slots. The technical solution can realize the reliable transmission of data in a wireless body area network and reduce the power consumption and time delay.