Abstract: A method for preparing nano iron phosphate with low sulfur content. The method may include: S1: mixing a phosphorus source and an iron source to obtain a raw material solution, then adding alkali and a surfactant, adjusting a pH, and stirring and reacting to obtain an iron phosphate dihydrate slurry, S2: adding phosphoric acid solution into the iron phosphate dihydrate slurry, adjusting the pH, heating and stirring for aging, and filtering to obtain iron phosphate dihydrate, S3: adding water into the iron phosphate dihydrate for slurrying, and grinding to obtain a ground slurry; and S4: adding the ground slurry into a washing solution to wash, carrying out solid-liquid separation, and calcining a solid phase to obtain the nano iron phosphate with low sulfur content.

Abstract: A method for preparing nano iron phosphate with low sulfur content. The method may include: S1: mixing a phosphorus source and an iron source to obtain a raw material solution, then adding alkali and a surfactant, adjusting a pH, and stirring and reacting to obtain an iron phosphate dihydrate slurry, S2: adding phosphoric acid solution into the iron phosphate dihydrate slurry, adjusting the pH, heating and stirring for aging, and filtering to obtain iron phosphate dihydrate, S3: adding water into the iron phosphate dihydrate for slurrying, and grinding to obtain a ground slurry; and S4: adding the ground slurry into a washing solution to wash, carrying out solid-liquid separation, and calcining a solid phase to obtain the nano iron phosphate with low sulfur content.

Abstract: The present invention discloses a preparation method for the plant-based nano corrosion inhibition bactericide for oilfield, comprising the following steps: Step 1. Prepare the aloin liquid; Step 2. Stir the carbon nanotube, hydroxyethyl methacrylate and acrylic acid to react for 4 h at a constant temperature of 80° C. to get the carbon nanotube after fiber treatment, namely the modified carbon nanotube; Step 3. Mix the aloin liquid with imidazoline-ammonium-salt, add acetonitrile, and then add modified carbon nanotube, increase the temperature to 95° C. stir and react for 12 hours, and filter after naturally cooling down to room temperature and get the carbon nanotube loaded with bactericide; Step 4. Stir the carbon nanotube loaded with bactericide, diphenylmethane diisocyanate and polycaprolactone to react for 6 hours at a constant temperature of 95° C. and in the reaction process, continuously inject helium to get the target bactericide.

Abstract: The present disclosure relates to a contactor and an operation method thereof. The contactor includes a contact, a control device, a wear indication and reset device, and a memory. The control device generates and stores wear diagnosis alarm information when the contactor is disconnected; generates a switch control signal based on the wear diagnosis alarm information when the contactor is powered on. A switch unit in the wear indication and reset device enters a wear indication state based on the switch control signal, and receives a user's operation to enter a reset state. The control device receives switch state information of the switch unit, and stores it when the contactor is disconnected. When the contactor is powered on, the control device clears the wear diagnosis alarm information based on the received switch state information being the reset state and the switch state information stored being the wear indication state.

Abstract: The present invention discloses a preparation method for the plant-based nano corrosion inhibition bactericide for oilfield, comprising the following steps: Step 1. Prepare the aloin liquid; Step 2. Stir the carbon nanotube, hydroxyethyl methacrylate and acrylic acid to react for 4 h at a constant temperature of 80° C. to get the carbon nanotube after fiber treatment, namely the modified carbon nanotube; Step 3. Mix the aloin liquid with imidazoline-ammonium-salt, add acetonitrile, and then add modified carbon nanotube, increase the temperature to 95° C. stir and react for 12 hours, and filter after naturally cooling down to room temperature and get the carbon nanotube loaded with bactericide; Step 4. Stir the carbon nanotube loaded with bactericide, diphenylmethane diisocyanate and polycaprolactone to react for 6 hours at a constant temperature of 95° C. and in the reaction process, continuously inject helium to get the target bactericide.

Abstract: Embodiments of the present invention provide an event reporting method and an apparatus. The method includes: receiving, by a policy and charging rules function PCRF entity, a first message sent by a traffic detection function TDF entity, where the first message includes a start event, and the start event is used to notify the PCRF entity that a data stream starts to be transmitted; sending, by the PCRF entity, a second message to a PCEF entity or the TDF entity, where the second message is used by the PCEF entity or the TDF entity to send a stop event to the PCRF entity, and the stop event is used to notify the PCRF entity that the transmission of the data stream stops; and receiving, by the PCRF entity, the stop event sent by the PCEF entity or the TDF entity.

Abstract: A two-level database structure for use by unlicensed TVBD devices operating in TV white space comprises a central database and local databases. The central database comprises two sub-database: the central licensed database which maintains information about all licensed TV devices and the central unlicensed database which maintains information about unlicensed wireless devices operating in TV spectrum. The local database is created by each TVBD device or TVBD network when it initiates and it stores information related to all transmitters in the local area. The local databases communicate with central database to query it about licensed usage of TV spectrum and register with central database. The local databases communicate with each other to exchange information about channel usage, sensing results, transmission patterns and other information that will allow the local databases to negotiate coexistence without central coordinator.

Abstract: A two-level database structure for use by unlicensed TVBD devices operating in TV white space comprises a central database and local databases. The central database comprises two sub-database: the central licensed database which maintains information about all licensed TV devices and the central unlicensed database which maintains information about unlicensed wireless devices operating in TV spectrum. The local database is created by each TVBD device or TVBD network when it initiates and it stores information related to all transmitters in the local area. The local databases communicate with central database to query it about licensed usage of TV spectrum and register with central database. The local databases communicate with each other to exchange information about channel usage, sensing results, transmission patterns and other information that will allow the local databases to negotiate coexistence without central coordinator.

Abstract: A frequency resource allocation system and method for a wireless network that comprises one or more unlicensed cognitive devices that operate using white spaces in a TV frequency spectrum and one or more licensed incumbent devices that are associated with an incumbent service that uses the TV frequency spectrum stores one or more frequency resource databases that store one or more frequency band lists. A frequency band list comprises one or more frequency bands within the TV frequency spectrum. Merit-related information specific to a location associated with the wireless network are collected to choose a specified frequency based on the merit-related information. The specified frequency band can be chosen based on a merit class derived from transforming the merit-related information into different merit classes, with each merit class being associated with one or more frequency bands. A resource user device is then notified to operate in the specified frequency band.

Abstract: A cognitive radio band device uses information gleaned from a database inquiry based on geo-location information in combination with spectrum sensing to determine if cognitive radio channels are available for unlicensed use.

Abstract: An interleaver of an OFDM/OFDMA transceiver reshapes a binary vector to be transmitted into a matrix, rotates bits in respective columns of the matrix, divides respective rows of the matrix into an integer number of interleaving blocks, and interleaves the bits in the respective interleaving blocks.

Abstract: A two-level database structure for use by unlicensed TVBD devices operating in TV white space comprises a central database and local databases. The central database comprises two sub-database: the central licensed database which maintains information about all licensed TV devices and the central unlicensed database which maintains information about unlicensed wireless devices operating in TV spectrum. The local database is created by each TVBD device or TVBD network when it initiates and it stores information related to all transmitters in the local area including location, power transmission levels, operating schedule, sensing results, backup channel information. The local databases communicate with central database to query it about licensed usage of TV spectrum and register with central database.

Abstract: A TV band device for indoor applications uses information gleaned from a database inquiry based on geo-location information in combination with spectrum sensing to determine if TV channels are available for unlicensed use.

Abstract: Methods and systems for operating a base station communicating with one or more user terminals in an orthogonal frequency division multiple access (OFDMA) system where the one or more user terminals are configured to insert pilots in up stream bursts every nth symbol on each subcarrier, where n is an integer, are provided. The method includes identifying a needed amount of up stream bandwidth to be allocated to a user terminal; determining the subcarriers and the number of symbols per subcarrier to be allocated to meet the identified need in a burst; allocating, for the user terminal, a set of subcarriers and a number of symbols for each member of the set of subcarriers, wherein sufficient symbols per subcarrier per burst are allocated to allow user terminal to send two or more pilots per subcarrier per burst; and transmitting a message to the user terminal, the message identifying the allocated subcarriers and the number of symbols allocated for each subcarrier.

Abstract: A frequency resource allocation system and method for a wireless network that comprises one or more unlicensed cognitive devices that operate using white spaces in a TV frequency spectrum and one or more licensed incumbent devices that are associated with an incumbent service that uses the TV frequency spectrum stores one or more frequency resource databases that store one or more frequency band lists. A frequency band list comprises one or more frequency bands within the TV frequency spectrum. Merit-related information specific to a location associated with the wireless network are collected to choose a specified frequency based on the merit-related information. The specified frequency band can be chosen based on a merit class derived from transforming the merit-related information into different merit classes, with each merit class being associated with one or more frequency bands. A resource user device is then notified to operate in the specified frequency band.

Abstract: A carrier frequency offset can be present in a signal received by a communications receiver, when the receiver has a local frequency oscillator that generates a carrier frequency different from a carrier frequency generated by a local frequency oscillator at a transmitter that transmitted the signal. A residual carrier frequency offset can remain after most of the carrier frequency offset has been removed from the received signal using conventional techniques. The residual carrier frequency offset is estimated using first and second channel impulse responses derived from first and second portions of the received signal. An estimated phase difference between the first and second channel impulse responses is computed. An estimate of the residual carrier frequency offset is computed using the estimated phase difference.

Abstract: A received signal comprises a continuous sequence of symbols ?1, ?2, . . . ?n, each represented by a sequence of samples X0, X2, . . . Xn?1, and wherein the symbols have a guard period GP of duration Tgp at the beginning thereof. Each guard period contains a cyclic prefix with the same subsequence of samples as a tail end portion of the associated symbol. The symbols are identified by delaying the received signal by a fixed number of samples, computing the correlation of the received signal with the delayed signal, computing the summation of said correlation over a window of duration Ti, wherein Ti>Tgp, and sliding the window over the correlation to find a characteristic point or region. The start of each symbol for further processing is selected from the characteristic point or region. By increasing the duration of the window, more robust performance can be achieved, especially in multipath conditions.

Abstract: A cognitive radio band device uses information gleaned from a database inquiry based on geo-location information in combination with spectrum sensing to determine if cognitive radio channels are available for unlicensed use.

Abstract: A two-level database structure for use by unlicensed TVBD devices operating in TV white space comprises a central database and local databases. The central database comprises two sub-database: the central licensed database which maintains information about all licensed TV devices and the central unlicensed database which maintains information about unlicensed wireless devices operating in TV spectrum. The local database is created by each TVBD device or TVBD network when it initiates and it stores information related to all transmitters in the local area including location, power transmission levels, operating schedule, sensing results, backup channel information. The local databases communicate with central database to query it about licensed usage of TV spectrum and register with central database.

Abstract: A carrier frequency offset can be present in a signal received by a communications receiver, when the receiver has a local frequency oscillator that generates a carrier frequency different from a carrier frequency generated by a local frequency oscillator at a transmitter that transmitted the signal. A residual carrier frequency offset can remain after most of the carrier frequency offset has been removed from the received signal using conventional techniques. The residual carrier frequency offset is estimated using first and second channel impulse responses derived from first and second portions of the received signal. An estimated phase difference between the first and second channel impulse responses is computed. An estimate of the residual carrier frequency offset is computed using the estimated phase difference.