Abstract: A feedstream comprising nitrous oxide is purified by a pressure swing adsorption process employing a copurge with an oxygen-lean stream to produce a high purity nitrous oxide stream. The high purity nitrous oxide stream can be incorporated in a complex for the production of adipic acid to recover nitrous oxide from a dilute waste stream and pass the recovered nitrous oxide to a process for the production of phenol from an aromatic hydrocarbon. Unreacted nitrous oxide from the phenol production step acid can be recovered in a second, or vent PSA step, and combined with the recovery of byproduct nitrous oxide waste streams from the production of adipic for the overall recovery of nitrous oxide, thereby significantly reducing nitrous oxide emissions from the production of adipic acid.

Abstract: The present invention is directed to characterizing the sense of an occurrence of a polysemous word in a representation of a dictionary. In a preferred embodiment, the representation of the dictionary is made up of a plurality of text segments containing word occurrences having a word sense characterization and word occurrences not having a word sense characterization. The embodiment first selects a plurality of the dictionary text segments that each contain a first word. The embodiment then identifies from among the selected text segments a first and a second occurrence of a second word. The identified second occurrence of the second word has a word sense characterization. The embodiment then attributes to the first occurrence of the second word sense characterization of the second occurrence of the second word.

Abstract: The present invention is directed to performing information retrieval utilizing semantic representation of text. In a preferred embodiment, a tokenizer generates from an input string information retrieval tokens that characterize the semantic relationship expressed in the input string. The tokenizer first creates from the input string a primary logical form characterizing a semantic relationship between selected words in the input string. The tokenizer then identifies hypernyms that each have an "is a" relationship with one of the selected words in the input string. The tokenizer then constructs from the primary logical form one or more alternative logical forms. The tokenizer constructs each alternative logical form by, for each of one or more of the selected words in the input string, replacing the selected word in the primary logical form with an identified hypernym of the selected word. Finally, the tokenizer generates tokens representing both the primary logical form and the alternative logical forms.

Abstract: The present invention identifies salient semantic relation paths between two words using a knowledge base. For a group of semantic relations occurring in the knowledge base, the facility models with a mathematical function the relation between a frequency of occurrence of unique semantic relations and the number of unique semantic relations that occur at that frequency. This mathematical function has a vertex frequency identifying a transition point in the mathematical function. The facility then determines the level of salience of unique semantic relations of the group such that the level of salience of unique semantic relations increases with the frequency of occurrence of the unique semantic relations approaches the vertex frequency of the mathematical function with which the relation between the frequency of occurrence of the unique semantic relations and the number of unique semantic relations occurring at that frequency is modeled.

Abstract: Apparatus and accompanying methods for an information retrieval system that utilizes natural language processing to process results retrieved by, for example, an information retrieval engine such as a conventional statistical-based search engine, in order to improve overall precision. Specifically, such a search ultimately yields a set of retrieved documents. Each such document is then subjected to natural language processing to produce a set of logical forms. Each such logical form encodes, in a word-relation-word manner, semantic relationships, particularly argument and adjunct structure, between words in a phrase. A user-supplied query is analyzed in the same manner to yield a set of corresponding logical forms therefor. Documents are ranked as a predefined function of the logical forms from the documents and the query.

Abstract: An author-oriented document summarizer for a word processor is described. The document summarizer performs a statistical analysis to generate a list of ranked sentences for consideration in the summary. The summarizer counts how frequently content words appear in a document and produces a table correlating the content words with their corresponding frequency counts. Phrase compression techniques are used to produce more accurate counts of repeatedly used phrases. A sentence score for each sentence is derived by summing the frequency counts of the content words in a sentence and dividing that tally by the number of the content words in the sentence. The sentences are then ranked in order of their sentence scores. Concurrent with the statistical analysis, during the same pass through the document the summarizer performs a cue-phrase analysis to weed out sentences with words or phrases that have been pre-identified as potential problem phrases.

Abstract: A process is disclosed for the shut-down of a membrane separation zone comprising a non-permeate side and a permeate side and processing a feed stream comprising a non-permeable component, a less-readily permeable, condensible component, and a readily permeable component. When the feed stream is not passed to the membrane separation zone, a purge stream is passed to the non-permeate side of the membrane separation zone to remove a residual gas stream and thereby prevent condensation of the less-readily permeable, condensible component upon depressurization and/or cooling of the membrane separation zone. The invention reduces the need for oversizing membrane system which reduces treating costs and prevents permeate damage to membrane surfaces caused by condensation of less-readily permeable, condensible components such as C.sub.6.sup.+ hydrocarbons.

Abstract: A pressure swing adsorption (PSA) process is provided for the size-selective separation of a feedstream into an adsorbate fraction employing a rapid blowdown step to induce a state of disequilibrium within an adsorbent bed and thereby increase the weight hourly space velocity of the process. The selective separation mechanism explored in the PSA process may also include equilibrium separation. The benefits include a reduced adsorbent bed size for new installations or increased feed rates for existing facilities. In one aspect of the invention the feedstream to be separated comprises iso and normal pentane.

Abstract: A process for the rejection of carbon dioxide from a natural gas feedstream comprising a gas permeable membrane and a multiple bed pressure swing adsorption system to produce a fixed gas product having a desired concentration of carbon dioxide. The permeate stream from the gas permeable membrane system is fed to the PSA unit and a stream essentially free of carbon dioxide gas from the PSA unit is compressed and blended with the non-permeate stream to form the mixed gas product.