Abstract: A method for harmonic detection includes: acquiring a ripple component of a direct-current bus voltage; acquiring a harmonic component of the direct-current bus voltage based on the ripple component; acquiring a quadrature component of the harmonic component based on the harmonic component; acquiring a characteristic parameter of the harmonic component based on the quadrature component, in which the characteristic parameter includes a phase; and acquiring and outputting a voltage amplitude of the harmonic component based on the quadrature component and the phase of the harmonic component.

Abstract: A record-pattern expression of a record pattern of data records is translated to a character-pattern expression of a character pattern. A data-record series of data records is converted to a character string in which each character in the character string corresponds to a respective data record in the data-record series. Pattern instances of the character pattern in the character string are searched to identify ordinal character positions in the character string of characters in the character pattern instances. Data records at ordinal record positions in the record series of data records corresponding to the ordinal character positions are reported.

Abstract: A database management system (DBMS) client calls an interface of a DBMS server to execute a statement that has been prepared to be executed in batch form in relation to a database managed by the DBMS server. The DBMS client provides a different batch of data to the DBMS server each time the DBMS client calls the interface. The DBMS server processes the different batch of data in accordance with the statement that has been prepared, to effectuate execution of the statement at the DBMS server on a batch basis in relation to the different batch of data. The DBMS server returns results of processing the different batch of data to the DBMS client, such that the DBMS client receives intermediate feedback as to status of processing the statement prior to the statement being completely processed.

Abstract: A record-pattern expression of a record pattern of data records is translated to a character-pattern expression of a character pattern. A data-record series of data records is converted to a character string in which each character in the character string corresponds to a respective data record in the data-record series. Pattern instances of the character pattern in the character string are searched to identify ordinal character positions in the character string of characters in the character pattern instances. Data records at ordinal record positions in the record series of data records corresponding to the ordinal character positions are reported.

Abstract: A database management system (DBMS) client calls an interface of a DBMS server to execute a statement that has been prepared to be executed in batch form in relation to a database managed by the DBMS server. The DBMS client provides a different batch of data to the DBMS server each time the DBMS client calls the interface. The DBMS server processes the different batch of data in accordance with the statement that has been prepared, to effectuate execution of the statement at the DBMS server on a batch basis in relation to the different batch of data. The DBMS server returns results of processing the different batch of data to the DBMS client, such that the DBMS client receives intermediate feedback as to status of processing the statement prior to the statement being completely processed.

Abstract: A new approach for handling stream imperfections based on speculative execution involves the retraction of incorrect events facilitated using operators to remove speculatively produced incorrect output. Additionally, parameters are disclosed that define a spectrum of consistency levels. A first parameter, maximum blocking time, exposes a tradeoff between a degree of speculation and latency. A second parameter, the maximum time data is remembered before being purged from the system, exposes a tradeoff between state size and correctness. Varying these two parameters produces a spectrum of consistency levels (e.g., strong, middle, weak) which address the specific tradeoffs built into other systems. Retraction is accomplished using operators that include Select, AlterLifetime, Join, Sum, Align, and Finalize.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for a database designer and a database storage designer. In one aspect, a method includes creating a set of candidate projections and progressively narrowing the set of candidate projections and a set of queries by eliminating candidate projections that do not satisfy a performance improvement criterion for remaining queries based on the properties associated with the candidate projections.

Abstract: A streaming operator assignment system and method for determining a streaming operator assignment that minimizes overload in a data processing system. Embodiments of the streaming operator assignment system include an optimization goals definition module, which defines optimization goals in terms of fundamental quantities that system administrators and application writers want to control, such as minimizing the worst case latency over all periods of time, or minimizing how much the system is backlogged with work. Embodiments of the streaming operator assignment system also include an optimization goals solution module that optimizes and solves a selected optimization goal. A specialized optimization technique is used to find the best operator (or load) assignment using the optimization goals to measure of the value of the assignment.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for operating on time sequences of data. In one aspect, a method includes a database management system storing and updating information in records in a table of a database, the records being associated with respective times that are spaced apart by time intervals, the database management system responding to a query that is phrased to imply a putative record with respect to a time interval that is not among the time intervals with which the records of the table are associated, and the response of the database management system to the query including a computation of a value of an attribute of the putative record from at least one non-null value of the attribute for one of the records of the table, the computation being based on an interpolation policy.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for a database designer and a database storage designer. In one aspect, a method includes creating a set of candidate projections and progressively narrowing the set of candidate projections and a set of queries by eliminating candidate projections that do not satisfy a performance improvement criterion for remaining queries based on the properties associated with the candidate projections.

Abstract: A streaming operator assignment system and method for determining a streaming operator assignment that minimizes overload in a data processing system. Embodiments of the streaming operator assignment system include an optimization goals definition module, which defines optimization goals in terms of fundamental quantities that system administrators and application writers want to control, such as minimizing the worst case latency over all periods of time, or minimizing how much the system is backlogged with work. Embodiments of the streaming operator assignment system also include an optimization goals solution module that optimizes and solves a selected optimization goal. A specialized optimization technique is used to find the best operator (or load) assignment using the optimization goals to measure of the value of the assignment.

Abstract: A query translation system and method for processing a streaming language query on existing or stored data. The streaming language query is applied against a data stream log by first translating the streaming language query into a database management system query (such as a SQL query) and then applying the translated streaming language query against the data stream log. Embodiments of the query translation system and method include a bitemporal converter that converts a bitemporal data stream log into a canonical history table format. Once in this format, embodiments of the query translation system and method translate a streaming language query into a SQL query. A categorization of each of the streaming operators that make up the streaming language query is performed to determine which translation technique to use. In general, one of three general translation techniques is used based on these categorizations of the streaming operators.

Abstract: Disclosed is a temporal stream model that provides support both for query language semantics and consistency guarantees, simultaneously. A data stream is modeled as a time varying relation. The data stream model incorporates a temporal data perspective, and defines a clear separation in different notions of time in streaming applications. The temporal stream model further refines the conventional application time into two temporal dimensions of valid time and occurrence time, and utilizes system time (the clock of the stream processor) for modeling out-of-order event delivery but thereby providing three temporal dimensions. The methods for assigning timestamps and quantifying latency form the basis for defining a spectrum of consistency levels. Based on the selected consistency level, an output can be produced. The utilization of system time facilitates the retraction of incorrect output and the insertion of the correct revised output.

Abstract: A new approach for handling stream imperfections based on speculative execution involves the retraction of incorrect events facilitated using operators to remove speculatively produced incorrect output. Additionally, parameters are disclosed that define a spectrum of consistency levels. A first parameter, maximum blocking time, exposes a tradeoff between a degree of speculation and latency. A second parameter, the maximum time data is remembered before being purged from the system, exposes a tradeoff between state size and correctness. Varying these two parameters produces a spectrum of consistency levels (e.g., strong, middle, weak) which address the specific tradeoffs built into other systems. Retraction is accomplished using operators that include Select, AlterLifetime, Join, Sum, Align, and Finalize.