Abstract: An obtaining method and apparatus for a block group header, a storage medium, and an electronic device are disclosed. The method may include, performing a determination as to whether a target node in a blockchain system meets a preset condition, where the preset condition is indicative of at least one of, the target node receiving a block group header but failing to receive a preset number of legal blocks, or the target node failing to receive the block group header; identifying a cause of an event that the target node fails to receive the block group header, in response to the determination that the target node fails to receive the block group header, where the cause of the event comprises at least one of, the target node failing to receive the block group header, or the blockchain system failing to generate the block group header; and determining a method for acquiring by the target node, the block group header that fails to be received, according to the cause of the event.

Abstract: Disclosed are a recommendation method, an apparatus, an electronic device, and a storage medium. The recommendation method includes: generating an item recommendation rank for a user based on a policy network in response to a user request at moment t; obtaining an experience at the moment t based on a feedback result from the user on the item recommendation rank; aggregating the experience of each user at the moment t to a global experience pool; and obtaining an updated policy network based on experiences in the global experience pool.

Abstract: Provided are a data access method and device, a storage medium and an electronic device. The method includes: a first access request used for requesting access to data in a database is received; the first access request is parsed to obtain the following data corresponding to the first access request: a first access parameter, a first request type, and a first controlled field list; a first data protection operation is performed on the first controlled field list based on the first access parameter and the first request type to obtain a target result; and a second access request is synthesized based on the target result, and the data in the database is accessed based on the second access request, so as to obtain an access result.

Abstract: Provided are a data association query method and apparatus, a device, and a storage medium. The data association query method includes the following: parsing a data query statement to obtain association query information, where the association query information includes query key information of a first association table; determining a query policy according to the query key information, where the query policy includes a partition filtering policy, a scan-while-filter policy and a scan-before-filter policy; and querying data in a second association table based on the query policy.

Abstract: A proxy method, a device, and a computer-readable storage medium are disclosed. The proxy method may include: obtaining transaction data of a user, the transaction data including a transaction request and private data; sending the transaction request to a blockchain platform, completing, by the blockchain platform, a transaction according to the transaction request, and storing the private data locally; and after the transaction is completed, sending the private data to a peer proxy for transaction verification.

Abstract: Disclosed are a data protection method and device and a storage medium. The method includes that a database execution engine receives data request information sent by a client; a preset policy corresponding to an identity of the client carried in the data request information is acquired and the database execution engine performs a data protection operation for requested data according to the preset policy to obtain target data; and the database execution engine sends the target data to the client.

Abstract: Disclosed are a data protection method and device and a storage medium. The method includes that a database execution engine receives data request information sent by a client; a preset policy corresponding to an identity of the client carried in the data request information is acquired and the database execution engine performs a data protection operation for requested data according to the preset policy to obtain target data; and the database execution engine sends the target data to the client.

Abstract: An apparatus and method for measuring molecular diffusivity in porous powders or minerals, e.g., the microporous synthetic minerals used for gas separation and chemical catalysis, were invented that allows a varying pressure in the gas around the powder during the measurement. This obviates the need for the pressure to be constant and the attendant complicated component parts. A mass balance model equation of the sample cell with the diffusivity as an adjustable parameter is used to deduce the sample cell pressure change versus time (uptake curve) until the equilibration of gas diffusion into the powder. A numerical analysis method is used to solve the mathematical model to compute a simulated uptake curve. Curve fitting of the simulated and measured uptake curves is used to optimize the diffusivity parameter, which gives the measured diffusivity. The apparatus and method are simple, easy to use, and automation is also simple.

Abstract: An apparatus and method for measuring molecular diffusivity in porous powders or minerals, e.g., the microporous synthetic minerals used for gas separation and chemical catalysis, were invented that allows a varying pressure in the gas around the powder during the measurement. This obviates the need for the pressure to be constant and the attendant complicated component parts. A mass balance model equation of the sample cell with the diffusivity as an adjustable parameter is used to deduce the sample cell pressure change versus time (uptake curve) until the equilibration of gas diffusion into the powder. A numerical analysis method is used to solve the mathematical model to compute a simulated uptake curve. Curve fitting of the simulated and measured uptake curves is used to optimize the diffusivity parameter, which gives the measured diffusivity. The apparatus and method are simple, easy to use, and automation is also simple.

Abstract: An apparatus and method for measuring molecular diffusivity in porous powders or minerals, e.g., the microporous synthetic minerals used for gas separation and chemical catalysis, were invented that allows a varying pressure in the gas around the powder during the measurement. This obviates the need for the pressure to be constant and the attendant complicated component parts. A mass balance model equation of the sample cell with the diffusivity as an adjustable parameter is used to deduce the sample cell pressure change versus time (uptake curve) until the equilibration of gas diffusion into the powder. A numerical analysis method is used to solve the mathematical model to compute a simulated uptake curve. Curve fitting of the simulated and measured uptake curves is used to optimize the diffusivity parameter, which gives the measured diffusivity. The apparatus and method are simple, easy to use, and automation is also simple.

Abstract: An apparatus and method for measuring molecular diffusivity in porous powders or minerals, e.g., the microporous synthetic minerals used for gas separation and chemical catalysis, were invented that allows a varying pressure in the gas around the powder during the measurement. This obviates the need for the pressure to be constant and the attendant complicated component parts. A mass balance model equation of the sample cell with the diffusivity as an adjustable parameter is used to deduce the sample cell pressure change versus time (uptake curve) until the equilibration of gas diffusion into the powder. A numerical analysis method is used to solve the mathematical model to compute a simulated uptake curve. Curve fitting of the simulated and measured uptake curves is used to optimize the diffusivity parameter, which gives the measured diffusivity. The apparatus and method are simple, easy to use, and automation is also simple.

Abstract: An apparatus and method are disclosed for measuring the kinetic parameters of a catalyst powder, which include the reaction rate constants, active site concentration and intraparticle diffusivity. The measurement of the active site concentration selectively measures just the active sites and not the entire exposed atom concentration. The apparatus and method use surface concentrations less than 50% and larger than 1% the total active site concentration and a dynamic pulsed flow to avoid including weak adsorption sites not involved in the catalysis. The measurement is more accurate because (1) it uses a reactant gas and non-steady state adsorption at temperatures near to reaction temperatures, and (2) it uses the chemical kinetics expressions to extract the measured active site concentration to perform the measurement so as to count just those sites actually active for that reactant.

Abstract: An apparatus and method are disclosed for measuring the kinetic parameters of a catalyst powder, which include the reaction rate constants, active site concentration and intraparticle diffusivity. The measurement of the active site concentration selectively measures just the active sites and not the entire exposed atom concentration. The apparatus and method use surface concentrations less than 50% and larger than 1% the total active site concentration and a dynamic pulsed flow to avoid including weak adsorption sites not involved in the catalysis. The measurement is more accurate because (1) it uses a reactant gas and non-steady state adsorption at temperatures near to reaction temperatures, and (2) it uses the chemical kinetics expressions to extract the measured active site concentration to perform the measurement so as to count just those sites actually active for that reactant.

Abstract: A method and apparatus for measuring the gas amounts adsorbed on a powder which directly measures pressure changes in a gas supply chamber with the use of differential pressure sensors between the gas supply chamber and a reference chamber which gas amount is maintained constant. Calculations of the gas amounts adsorbed are based on the pressure changes in a sample cell and the pressure changes in the gas supply chamber or a gas reference chamber. The method and apparatus of this invention measures the adsorption or desorption isotherm or gas uptake at constant pressure curve of a powder with, as compared with presently available measurement techniques, increased accuracy and resolution. The experimental data can be analyzed to obtain information on the surface area, pore size distribution, pore volume, pore structure and diffusion coefficient of the powder.

Abstract: A method and apparatus for measuring the gas amounts adsorbed on a powder which directly measures pressure changes in a gas supply chamber with the use of differential pressure sensors between the gas supply chamber and a reference chamber which gas amount is maintained constant. Calculations of the gas amounts adsorbed are based on the pressure changes in a sample cell and the pressure changes in the gas supply chamber or a gas reference chamber. The method and apparatus of this invention measures the adsorption or desorption isotherm or gas uptake at constant pressure curve of a powder with, as compared with presently available measurement techniques, increased accuracy and resolution. The experimental data can be analyzed to obtain information on the surface area, pore size distribution, pore volume, pore structure and diffusion coefficient of the powder.