摘要:
A method and system are disclosed for generating a decision-tree classifier in parallel in a multi-processor system, from a training set of records. The method comprises the steps of: partitioning the records among the processors, each processor generating an attribute list for each attribute, and the processors cooperatively generating a decision tree by repeatedly partitioning the records using the attribute lists. For each node, each processor determines its best split test and, along with other processors, selects the best overall split for the records at that node. Preferably, the gini-index and class histograms are used in determining the best splits. Also, each processor builds a hash table using the attribute list of the split attribute and shares it with other processors. The hash tables are used for splitting the remaining attribute lists. The created tree is then pruned based on the MDL principle, which encodes the tree and split tests in an MDL-based code, and determines whether to prune and how to prune each node based on the code length of the node.
摘要:
Process and system for liquefying a pressurized gas, especially natural gas. The process is carried out in two heat exchangers, and cooling for each heat exchanger is provided by a mixed refrigerant which is vaporized at a single essentially constant pressure. Feed precooling, low level refrigerant precooling, and high level liquid refrigerant subcooling are effected in one of the heat exchanger against low level refrigerant vaporizing at a single essentially constant pressure. The process and system of the invention are especially well-suited for installation on ships, barges, and offshore platforms.
摘要:
The present invention teaches an efficient and easier to operate distillation system to separate mixtures containing three or more components into streams enriched in one of the components. In this invention, a liquid stream enriched in the least volatile component is withdrawn from the bottom of one distillation column while a vapor stream enriched in the most volatile component is withdrawn from the top of another distillation column. Of these two distillation columns, the pressure of the distillation column with the bottom liquid enriched in the least volatile component is higher; and this higher pressure distillation column transfers at least two vapor streams from different locations to either one or more other distillation columns within the distillation system. For a ternary mixture, both the vapor streams are transferred to the distillation column with the top vapor enriched in the most volatile component. In the preferred mode, at least one of the vapor transfer is part of a two-way communication between the two columns, i.e., in addition to the transfer of the vapor stream, a return liquid stream is implemented between the same locations of the two columns. This invention allows the flow of all vapor streams from a higher pressure column to a lower pressure column and thereby does not suffer with the operating pressure constraints of the prior art efficient processes.
摘要:
The present invention relates to a process for the cryogenic separation of air to recover at least a nitrogen-depleted crude argon product, wherein the process is carried out in a primary distillation system comprising at least a first distillation column, which separates a feed mixture comprising nitrogen, oxygen and argon into a nitrogen-enriched overhead and an oxygen-rich bottoms, and a side-arm column which rectifies an argon-containing feed stream fed from the primary distillation column to produce an essentially-oxygen-depleted argon overhead. The improvement of the present invention is characterized in that: (a) a nitrogen-containing, argon-rich side stream is withdrawn from a location of the side-arm column which is above the location of entry of the argon-containing feed stream; (b) the withdrawn, nitrogen-containing, argon-rich side stream of step (a) is fed to a nitrogen rejection column to remove the contained nitrogen, wherein the nitrogen rejection column contains at least a stripping section which is located below the location of the feed of the nitrogen-lean, argon-rich side stream, and wherein the stripping section of the nitrogen rejection column is provided with vapor boilup; (c) the nitrogen-depleted, crude argon product is recovered and removed from the bottom of the nitrogen rejection column; and (d) at least a portion of upward flowing vapor in the nitrogen rejection column is removed and the removed portion is returned to a suitable location of the side-arm column.
摘要:
A system and method including a computer shape definition language are disclosed for defining shapes and mining time sequences that resemble the shapes. The system and method include provisions for establishing a user-defined alphabet that in turn establishes a set of elemental shapes. The system also includes simple yet powerful operators for combining the elemental shapes to define a desired time sequence shape. Moreover, intervals of actual time sequences are mapped into corresponding transition sequences using the alphabet, and the transition sequences are stored in a hierarchical index structure for easily accessing the transition sequences. The index structure is entered with the desired time sequence shape, and the index structure is traversed to identify maximal actual transition sequences which conform to the desired time sequence shape, within user-definable blurry criteria.
摘要:
A method and system are disclosed for generating a decision-tree classifier in parallel in a multi-processor system, from a training set of records. The method comprises the steps of: partitioning the records among the processors, each processor generating an attribute list for each attribute, and the processors cooperatively generating a decision tree by repeatedly partitioning the records using the attribute lists. For each node, each processor determines its best split test and, along with other processors, selects the best overall split for the records at that node. Preferably, the gini-index and class histograms are used in determining the best splits. Also, each processor builds a hash table using the attribute list of the split attribute and shares it with other processors. The hash tables are used for splitting the remaining attribute lists. The created tree is then pruned based on the MDL principle, which encodes the tree and split tests in an MDL-based code, and determines whether to prune and how to prune each node based on the code length of the node.
摘要:
A multiprocessor including a plurality of processing systems is disclosed for discovering consumer purchasing tendencies. Each processing system of the multiprocessor identifies consumer transaction itemsets that are stored in a database that is distributed among the processing systems and which appear in the database a user-defined minimum number of times, referred to as minimum support. Then, the system discovers association rules in the itemsets by comparing the ratio of the number of times each of the large itemsets appears in the database to the number of times particular subsets of the itemset appear in the database. When the ratio exceeds a predetermined minimum confidence value, the system outputs an association rule which is representative of purchasing tendencies of consumers.
摘要:
Disclosed is a system and method for performing database queries including GROUP-BY operations, in which aggregate values for attributes are desired for distinct, partitioned subsets of tuples satisfying a query. A special case of the aggregation problem is addressed, employing a structure, called the data cube operator, which provides information useful for expediting execution of GROUP-BY operations in queries. Algorithms are provided for constructing the data cube by efficiently computing a collection of GROUP-BYs on the attributes of the relation. Decision support systems often require computation of multiple GROUP-BY operations on a given set of attributes, the GROUP-BYs being related in the sense that their attributes are subsets or supersets of each other. The invention extends hash-based and sort-based grouping methods with optimizations, including combining common operations across multiple GROUP-BYs and using pre-computed GROUP-BYs for computing other GROUP-BYs. An extension of the cube algorithms handles any given collection of aggregates.
摘要:
A method and apparatus are disclosed for mining quantitative association rules from a relational table of records. The method comprises the steps of: partitioning the values of selected quantitative attributes into intervals, combining adjacent attribute values and intervals into ranges, generating candidate itemsets, determining frequent itemsets, and outputting an association rule when the support for a frequent itemset bears a predetermined relationship to the support for a subset of the frequent itemset. Preferably, the partitioning step includes determining whether to partition and the number of partitions based on a partial incompleteness measure. The candidate generation includes discarding those itemsets not meeting a user-specified interest level and those having a subset which is not a frequent itemset. The frequent itemsets are determined using super-candidates that include information of the candidate itemsets. Preferably, each super-candidate has a data structure, such as a multi-dimensional tree or array, representing quantitative attributes common to the replaced candidate itemsets.
摘要:
An integrated gasification combined cycle (IGCC) power generation system is operated with a cryogenic air separation system which produces oxygen used in a gasification system to produce fuel gas for the IGCC combustion turbine and pressurized nitrogen which is introduced into the combustor for control of nitrogen oxides and increased combustion turbine output. The air separation system produces argon as an additional product, and the air separation system preferably operates in the feed pressure range of about 100 to about 160 psia. The compressed air feed for the air separation system and the compressed combustion air for the IGCC system are provided independently in separate compression steps.