A plasmid vector characterized by comprising a promoter sequence that can be recognized by an RNA polymerase which is not inherent in a host and that controls the expression of desired genes and a replication origin that increases the number of copies under the induction by exogenous factors; methods for expression and isolation of target genes by using the vector; a polypeptide having the activity of an AccIII restriction endonuclease; and a DNA encoding the polypeptide. The invention provides for the first time a plasmid vector which can introduce an exogenous desired gene encoding proteins which are lethal or harmful to hosts into the hosts, a method for efficiently expressing the proteins by using the vector, and also a method for permitting a restriction endonuclease-gene constituting a restriction-modification system to be isolated even in the absence of a modification enzyme gene, which has been difficult in the prior arts.

The present invention relates to a plasmid vector usable in genetic recombinant technology and to a method for expressing a gene by using the plasmid vector. The present invention also relates to a method for isolating a desired gene by using such a plasmid vector. In addition, the present invention relates to a restriction enzyme and a gene thereof available as a genetic engineering reagent, in more detail to the AccIII restriction endonuclease and a DNA coding therefor.
In constructing an expression system for a desired gene by genetic recombinant technology, expression of the gene is controlled by bringing it under control of a promoter recognized by the RNA polymerase of the host used. In the case of a gene encoding a protein harmful to the host, however, plasmid construction itself is sometimes hampered by expression of the product of the gene due to the inability to stringently control the expression of the promoter used.
As an expression system resolving that problem, the pET system (produced by Novagen) has been developed, which uses the RNA polymerase of the bacteriophage T7, which infects Escherichia coli, with Escherichia coli as a host [journal of Molecular Biology, Vol. 189, pp. 113-130 (1986); Gene, Vol. 56, pp. 125-135 (1987)]. The pET system is a system that allows T7 RNA polymerase, which has high promoter recognition specificity and high transcription activity, to be expressed in Escherichia coli, which T7 RNA polymerase transcribes a desired gene placed downstream of the T7 promoter on an expression vector and causes high expression of the gene. Because transcription of the desired gene occurs in the presence of T7 RNA polymerase, plasmid construction in the host is possible without expressing the desired gene, provided that the host does not produce the polymerase; plasmid construction itself is never hampered, as in cases where the expression system is constructed, while the desired gene is kept under control of a promoter recognized by the RNA polymerase of the host.
However, because the T7 RNA polymerase gene has been cloned onto the xcex-phage vector and lysogenized into the expression host, there is no freedom of host choice; painstaking procedures are needed if the host is changed. In addition, because the expression of T7 RNA polymerase in the host is not stringently controlled, T7 RNA polymerase is expressed even when the host is in a non-inductive condition, resulting in expression of the desired gene placed downstream of the T7 promoter on the expression vector even in a non-inductive condition. To suppress such expression of the desired gene in a non-inductive condition, T7 RNA polymerase activity is inhibited using T7 lysozyme, a T7 RNA polymerase inhibitor [Journal of Molecular Biology, Vol. 219, pp. 37-44 (1991)], or T7 RNA polymerase is prevented from getting access to the T7 promoter by placing a lactose operator downstream of the T7 promoter [Journal of Molecular Biology, Vol. 219, pp. 45-59 (1991)].
However, even these countermeasures are unsatisfactory in terms of effect against T7 RNA polymerase of high transcription activity so that the activity of T7 RNA polymerase in a non-inductive condition cannot be completely inhibited. For this reason, if the desired gene product is lethal to the host, it is impossible in some cases to prepare a transformant for expression of the gene, even when plasmid construction is possible. In other words, the pET system involves two problems to be resolved: one of the inability to freely change the host, and the other of inaccurate control of T7 RNA polymerase expression.
On the other hand, there is a bacteriophage having characteristics similar to those of the bacteriophage T7, known as the bacteriophage SP6 [Science, Vol. 133, pp. 2069-2070 (1961)], which infects Salmonella typhimurium. The RNA polymerase produced by the bacteriophage SP6, a single peptide having-a molecular weight of about 100,000, is commonly used for in vitro RNA synthesis since it possesses high promoter recognition specificity and high transcription activity [Journal of Biological Chemistry, Vol. 257, pp. 5772-5778 (1982); Journal of Biological Chemistry, Vol. 257, pp. 5779-5788 (1982)]. In addition, the SP6 RNA polymerase gene has already been cloned and expressed in large amounts in Escherichia coli [Nucleic Acids Research, Vol. 15, pp. 2653-2664 (1987)].
Genes whose expression product acts lethally on hosts are exemplified by restriction endonuclease genes. Essentially, restriction endonucleases are utilized for self-defense by cleaving phages and other exogenous DNA entering the cells of microorganisms that produce the restriction endonucleases. On the other hand, microorganisms that produce restriction endonucleases mostly produce modification enzymes that recognize the same base sequences as those of the restriction endonucleases, to protect their own DNA against cleavage by the restriction endonucleases. Specifically, a modification enzyme modifies DNA by adding a methyl group to one or more bases in the base sequence recognized thereby, to make it impossible for the restriction endonuclease that recognizes the same sequence as that of the modification enzyme to bind thereto or to cleave the DNA. This mechanism is called restriction modification system, and the pair of genes of the restriction endonuclease and modification enzyme that constitute the restriction modification system called restriction modification system gene. Therefore, when the restriction endonuclease gene is expressed in a microorganism lacking a modification enzyme gene from the restriction modification system gene, the microorganism""s DNA is cleaved, resulting in cell death. In fact, there are two modification enzyme genes in the MboI restriction modification system gene; it has been reported that cloning of restriction endonuclease genes is impossible due to incomplete modification of the host DNA in the case of incomplete methylation in the co-presence of either modification enzyme gene alone [Nucleic Acids Research, Vol. 21, pp. 2309-2313 (1993)].
Also, it has been demonstrated that if a restriction modification system gene is lost from a cell retaining the restriction modification system gene, a lack of modification activity in the cell results in incomplete methylation of genomic DNA, which in turn causes lethal cleavage of its own genomic DNA by a very small amount of restriction endonuclease remaining therein [Science, Vol. 267, pp. 897-899 (1995)]. In summary, in the absence of modification enzymes that constitute a restriction modification system, restriction endonucleases behave as proteins very harmful to cells; separate cloning and expression of their genes have been impossible by prior art technologies.
Concerning restriction endonucleases, restriction endonucleases can be classified by their enzymatic properties into three types: I, II and III. Type II restriction endonucleases, in particular, each of which recognizes a particular DNA base sequence and cleaves it at a particular site in or near the sequence, are extensively used in the field of genetic engineering, and restriction endonucleases of this type with various specificities have been isolated from a variety of microorganisms [Nucleic Acids Research, Vol. 24, pp. 223-235 (1996)]. In the present specification, a type II restriction endonuclease is hereinafter referred to as xe2x80x9crestriction endonucleasexe2x80x9d. It should be noted, however, that some microorganisms produce only small amounts of restriction endonuclease, and others produce a plurality of restriction endonucleases. For example, the restriction endonuclease AccIII is produced by Acinetobacter calcoaceticus (hereinafter referred to as Acc bacterium), which has been deposited under accession number FERM BP-935 at the National Institute of Bioscience and Human-Technology, Agency of Industrial Science and Technology, Ministry of International Trade and Industry [address: 1-3, Higashi 1-chome, Yatabemachi, Tsukuba-gun, Ibaraki, 305, Japan] since Nov. 9, 1985 (date of original deposition), but the amount of the enzyme produced is small and this microorganism also produces the restriction endonucleases AccI and AccII simultaneously. Therefore, advanced production technology is needed to provide the restriction endonuclease AccIII as a reagent of high purity and low cost using this microorganism. In providing a restriction endonuclease as a reagent of high purity and low cost, it is effective to isolate the desired restriction endonuclease gene and selectively produce the desired restriction endonuclease in large amounts by genetic engineering technology. To accomplish this purpose, some methods of isolating restriction endonuclease genes have been reported.
First, there may be mentioned the xe2x80x9cshotgunxe2x80x9d method, wherein the genomic DNA of a microorganism that produces a restriction endonuclease is cleaved using the appropriate restriction endonuclease, the resulting fragment is inserted into an appropriate plasmid vector, and a clone expressing the restriction endonuclease gene is selected. Screening methods for desired clones are exemplified by a method wherein a restriction modification system gene is isolated with resistance to phage infection as an index, on the basis of the self-defence function acquired by the host upon introduction of the restriction modification system gene thereinto [PstI: Proceedings of the National Academy of Science of the USA, Vol. 78, pp. 1503-1507 (1981)]. This method, however, necessitates that the size of the restriction modification system gene falls within a range allowing its isolation, and that the expression of the restriction modification system gene isolated exhibits sufficient phage resistance to allow the selective survival of the host. On the other hand, as a general feature of restriction modification system genes, there may be mentioned the close location on the genome of restriction endonuclease genes and modification enzyme genes; in fact, this has been confirmed in many restriction modification system genes that have so far been obtained [Nucleic Acids Research, Vol. 19, pp. 2539-2566 (1991)]. Accordingly, there is a method wherein a restriction modification system gene is screened for with the expression of a modification enzyme gene as an index on the basis of the above-described feature [Japanese Patent Laid-Open No. 63-87982; Nucleic Acids Research, Vol. 19, pp. 1831-1835 (1991)]. When the restriction endonuclease gene is not close to the modification enzyme gene, however, this method fails to yield the restriction endonuclease gene.
Furthermore, the above-described xe2x80x9cshotgunxe2x80x9d method poses a fundamental problem associated with a difference in transcription-translation mechanism between the genomic DNA source organism and the host. For example, in the case of insufficient gene expression due to the failure of the promoter and ribosome binding site accompanying the restriction modification system gene to function well in the host, much labor is needed to select transformants containing the desired gene, even if obtained. To avoid this drawback, there is a method wherein the amino acid sequence of the restriction endonuclease protein is analyzed, the restriction endonuclease gene is obtained from the genomic DNA of a microorganism that produces the restriction endonuclease by PCR-based DNA amplification on the basis of the sequence data obtained, and wherein a known protein expression system is utilized [Japanese Patent Laid-Open No. 6-277070]. Because the presence of a restriction endonuclease is lethal to the host in conventional protein expression systems, there is a need to protect the host by, for example, allowing a modification enzyme that constitutes a restriction modification system together with the enzyme to be co-present.
Although all the above-described methods of the isolation of restriction endonuclease genes necessitate the simultaneous isolation of the restriction endonuclease gene and a modification enzyme gene that constitutes a restriction modification system gene together with the gene, another method of isolating the restriction endonuclease gene alone has been reported [Nucleic Acids Research, Vol. 22, pp. 2399-2403 (1994)]. In that method, however, it is intended to isolate a gene encoding a restriction endonuclease for which optimal temperature for enzyme activity is around 70xc2x0 C.; the co-presence of a modification enzyme gene is necessary when the gene to be isolated encodes a restriction endonuclease showing high specific activity near host culturing temperature.
Exceptionally, there are restriction endonucleases that do not show cleavage activity unless a particular nucleic acid base in their DNA recognition sequence has not been modified by methylation, like the restriction endonuclease DpnI. Genes for restriction endonucleases possessing this property are thought to be exceptional in that they can be isolated even in the absence of another particular gene by selecting the appropriate host organism. In fact, the mrr gene has been isolated, which encodes the Mrr protein, which is not a type II restriction endonuclease but which recognizes a particular DNA base sequence containing a methylated nucleic acid base and exhibits DNA cleavage activity [Journal of Bacteriology, Vol. 173, pp. 5207-5219 (1991)].
As stated above, isolation of a restriction endohuclease gene by the prior art necessitates the simultaneous expression of the gene and a modification enzyme gene that constitutes a restriction modification system gene together with the gene, except for special cases.
Therefore, a first object of the present invention provides a plasmid vector capable of isolating such a gene that an isolation thereof or a construction of an expression system thereof has been difficult in the prior arts because the gene product is lethal or harmful to a host, and capable of introducing into a host to express the protein efficiently. A second object of the present invention provides a method for expressing a desired gene by using this plasmid vector. A third object of the present invention provides a method for isolating a desired gene by using this plasmid vector, especially for isolating a restriction endonuclease gene without co-existence of a modification enzyme gene constituting a restriction modification system. A fourth object of the present invention provides a polypeptide possessing an activity of an AccIII restriction endonuclease. In addition, a fifth object of the present invention provides a DNA which encodes a polypeptide possessing an activity of an AccIII restriction endonuclease.
First, to resolve the problems in the pET system, the present inventors have constructed an expression system using SP6 RNA polymerase as a new accurate expression control expression system, and assessed the system.
Because the expression system is constructed using a system plasmid inserted the SP6 RNA polymerase gene into the miniF plasmid, expression systems for the desired gene can be constructed in various strains of Escherichia coli by simultaneously introducing an expression vector harboring the desired gene cloned downstream of the SP6 promoter and this system plasmid into the host. In addition, using the lac promoter and antisense technology, the present inventors made it possible to exactly control the expression of the SP6 RNA polynerase gene on the system plasmid. Assessing this expression system using the xcex2-galactosidase gene as a reporter gene demonstrated that the expression of the SP6 RNA polymerase gene is accurately controlled in this system, that there is almost no expression of SP6 RNA polymerase in a non-inductive condition, and that induction is followed by the expression of a sufficient amount of SP6 RNA polymerase to efficiently express the desired gene and subsequent expression of the desired gene at a high level.
It was also shown, however, that when the host used is Escherichia coli, the desired gene downstream of the SP6 promoter is expressed in very small amounts even in a non-inductive condition because the SP6 promoter is very weakly but actually recognized by Escherichia coli RNA polymerase. It was thus proven that when the gene product acts very harmfully and lethally to Escherichia coli, expression system construction is impossible so that the object of the present invention cannot be accomplished well.
With these findings in mind, the present inventors have made further extensive investigation and unexpectedly found that (i) expression of the desired gene in a non-inductive condition can be suppressed to undetectable levels, and that (ii) expression induction increases the copy number of the plasmid containing the desired gene and causes RNA polymerase expression, resulting in the transcription and translation of the desired gene placed downstream of a promoter recognized by the RNA polymerase, by using a new system for controlling the expression of the desired gene by means of a combination of two control methods, i.e., control of the copy number of the gene, and transcription control via the promoter. In other words, the plasmid vector of the present invention is a plasmid vector having unique features to resolve the above problems in the field of genetic engineering. The present inventors made further investigation based on this finding, and developed a method for expressing the desired gene using the vector.
The present inventors also have developed a method for isolating a gene whose expression product acts lethally on the host, using the above-described plasmid vector, more specifically a method of isolating a restriction endonuclease gene without the drawbacks of the prior art.
The present inventors also found it possible to isolate DNA encoding the AccIII restriction endonuclease, which had not been obtained so far, without the co-presence of an AccIII modification enzyme, and express the AccIII restriction endonuclease in large amounts, using the above-described method.
(1) The gist of the present invention is concerned with:
A plasmid vector characterized by comprising a promoter sequence to control an expression of a desired gene, the promoter sequence being recognized by an RNA polymerase not inherent to a host, and a replication origin for increasing a copy number by induction with an exogenous factor;
(2) The plasmid vector described in item (1) above, wherein the promoter sequence is recognized by RNA polymerases derived from bacteriophages;
(3) The plasmid vector described in item (2) above, wherein the promoter sequence is recognized by an RNA polymerase derived from SP6 phage;
(4) The plasmid vector described in item (3) above, wherein the promoter sequence contains the base sequence of SEQ ID NO:30 in the Sequence Listing;
(5) The plasmid vector described in any one of items (1) to (4) above, wherein the replication origin is under control of a promoter;
(6) The plasmid vector described in any one of items (1) to (5) above, wherein the replication origin is under control of the lac promoter;
(7) The plasmid vector described in any one of items (1) to (6) above, comprising a drug resistance gene as a selection marker;
(8) The plasmid vector described in item (7) above, which is selected from pACE601, pACE611, pACE701 and pACE702;
(9) A plasmid vector in which a desired gene to be expressed is incorporated into the plasmid vector described in any one of items (1) to (8) above;
(10) A method for expressing a desired gene, characterized by introducing into a host a plasmid vector in which the desired gene is incorporated into the plasmid vector described in any one of items (1) to (8) above, and an RNA polymerase gene which recognizes a promoter sequence in the plasmid vector, and inducing an increase in a copy number of the plasmid vector and an expression of the RNA polymerase by using an exogenous factor to transcribe and translate the desired gene;
(11) The method for expressing a desired gene described in item (10) above, characterized in that the increase in the copy number of the plasmid vector and the expression of the RNA polymerase are induced by respective exogenous factors;
(12) The method for expressing a desired gene described in item (10) above, characterized in that the increase in the copy number of the plasmid vector and the expression of the RNA polymerase are induced by a same exogenous factor;
(13) The method for expressing a desired gene described in any one of items (10) to (12) above, wherein the exogenous factor which induces the increase in the copy number of the plasmid vector, is one or more selected from the group consisting of an addition of isopropyl-xcex2-D-thiogalactoside (IPTG), an addition of lactose, an addition of galactose, an addition of arabinose, a reduction of a tryptophane concentration and an adjustment of a transformant cultivation temperature;
(14) The method for expressing the desired gene described in any one of items (10) to (12) above, wherein the exogenous factor which induces the expression of the RNA polymerase, is one or more selected from the group consisting of an addition of isopropyl-xcex2-D-thiogalactoside (IPTG), an addition of lactose, an addition of galactose, an addition of arabinose, a reduction of a tryptophane concentration and an adjustment of a transformant cultivation temperature;
(15) The method for expressing a desired gene described in item (10) above, characterized in that the RNA polymerase gene is introduced into the host by the other plasmid vector or a phage vector;
(16) The method for expressing a desired gene described in item (10) above, characterized in that the RNA polymerase gene is incorporated into a chromosome of the host;
(17) The method for expressing a desired gene described in item (15) or item (16) above, characterized in that the RNA polymerase gene is derived from SP6 phage;
(18) The method for expressing a desired gene described in any one of items (10) to (17) above, wherein the desired gene encodes a protein lethal or harmful to the host;
(19) The method for expressing a desired gene described in any one of items (10) to (18) above, characterized in that Escherichia coli is used as the host;
(20) A method for isolating a desired gene, characterized in that the plasmid vector described in any one of items (1) to (8) above is employed in the method for isolating the desired gene;
(21) The method for isolating a desired gene described in item (20) above, wherein the desired gene encodes a protein lethal or harmful to a host;
(22) The method for isolating a desired gene described in item (21) above, wherein the gene encoding a protein lethal or harmful to the host is a restriction endonuclease gene;
(23) A polypeptide containing the entire or a portion of the amino acid sequence shown by SEQ ID NO:1 in the Sequence Listing, and possessing an activity of AccIII restriction endonuclease;
(24) A polypeptide having an amino acid sequence resulting from at least one of deletion, addition, insertion or substitution of one or more amino acid residues in the amino acid sequence of SEQ ID NO:1 in the Sequence Listing or a portion thereof, and possessing an activity of AccIII restriction endonuclease;
(25) A DNA encoding a polypeptide which contains the entire or a portion of the amino acid sequence shown by SEQ ID NO:1 in the Sequence Listing, and possesses an activity of AccIII restriction endonuclease;
(26) A DNA containing the entire or a portion of the DNA shown by SEQ ID NO:2 in the Sequence Listing wherein an expression product of the DNA possesses an activity of AccIII restriction endonuclease;
(27) A DNA encoding a polypeptide resulting from at least one of deletion, addition, insertion or substitution of one or more amino acid residues in the amino acid sequence of SEQ ID NO:1 in the Sequence Listing or a portion thereof, and possessing an activity of AccIII restriction endonuclease; and
(28) A DNA capable of hybridizing to the DNA described in any one of items (25) to (27) above, and encoding a polypeptide possessing an activity of AccIII restriction endonuclease.


The invention relates to thermoplastic molding compositions comprising a polycarbonate resin which is rendered resistant to gamma radiation induced yellowing. It was surprisingly found that the incorporation in the resin of an effective amount of benzylic alcohol or its derivatized versions renders the composition resistant to yellowing. The composition of the invention is suitable for the preparation of molded articles having improved resistance to yellowing and to the formation of haze induced upon exposure to gamma radiation.

Because of their physical and mechanical properties polycarbonate resins were found to be eminently suitable for a variety of applications in the medical field. Applications which require sterilization by exposure to gamma radiation present a problem since polycarbonate tends to yellow and show increased haze. One solution to the problem was proposed in U.S. Pat. No. 4,624,972 which disclosed polycarbonate compositions containing an ester of an aromatic polycarboxylic acid. European Patent Application 152,012 disclosed a method for increasing the ionizing radiation resistance of polycarbonate by including in the composition a non-polymeric compound which is characterized by a strong oxidizing action and/or reaction at high reaction rate with active species such as E or OH radicals or hydrated electrons formed by ionizing radiation. U.S. Pat. No. 4,451,641 disclosed a container prepared from a copolyester which has been modified with either a dimer acid or a dimer glycol. The copolyester is said to have an improved resistance to gamma radiation. Radiation stable polyolefin compositions have been disclosed in U.S. Pat. No. 4,460,445. Copending U.S. patent application Ser. No. 07/305,301 filed Feb. 1, 1989 pending (a continuation of U.S. Ser. Nos. 67,670 filed June 26, 1987) and 07/297,264 filed Jan. 18, 1989 now U.S. Pat. No. 4,963,598 (a continuation-in-part of Ser. No. 183,023 filed Apr. 18, 1988) relate to relevant technology.

Gamma radiation resistant polycarbonate composition


A layout structure for memory devices includes a plurality of first gate patterns, a plurality of first landing pad patterns, a plurality of dummy patterns, a plurality of second landing pad patterns, and a plurality of second gate patterns. The first landing pad patterns are parallel with each other and electrically connected to the first gate patterns. The dummy patterns and the first landing pad patterns are alternately arranged, and the second landing pad patterns are respectively positioned in between one first landing pad pattern and one dummy pattern. The second gate patterns are electrically connected to the second landing pad patterns.

1. Field of the Invention
The invention relates to a semiconductor structure and a layout structure for memory devices, and more particularly, to a semiconductor structure and a layout structure for flash memory devices.
2. Description of the Prior Art
Semiconductor memory has become increasingly popular for used in various electronic devices. For example, non-volatile semiconductor memory is used in cellular telephones, digital cameras, personal digital assistants, mobile computing devices. Electrically erasable programmable read only memory (EEPROM) and flash memory are among the most popular non-volatile semiconductor memories.
With rapid advancement of semiconductor fabricating technology and miniaturization of the devices, more and more challenges have been emerged. For example, a conventional flash memory cell includes a memory gate and a select gate adjacent to the memory gate. With the shrink of the device size and of the process window, device performance becomes more and more susceptible to the misalignment between the select gate and the contact plugs. The memory devices are even failed because of the misalignment issue. Furthermore, when a spacer-typed select gate approach is adopted, the select gate includes a sloped profile and thus the contact plug, which must be infallibly landed on the spacer-typed select gate, may not physically contacts the select gate and thus adversely impacts the reliability.

Semiconductor structure and layout structure for memory devices


A method including: Obtaining multiple conversation texts, one text per conversation, wherein each of the multiple conversation texts comprises: multiple messages authored by multiple parties, and a reference to an electronic document that provides resolution of a problem that is common to all the conversations. Calculating an importance score for each of the multiple messages of all the conversation texts. Clustering the multiple messages of all the conversation texts into multiple bins. Calculating an aggregated importance score for each of the multiple bins, based on the importance scores of the messages contained in the respective bin. Enriching (a) the electronic document, or (b) a record of the electronic document in an index of electronic documents, with at least some of the multiple bins and their aggregated importance scores, wherein the at least some of the multiple bins are added as fields to the electronic document or to the record.

The invention relates to the field of computerized information retrieval.
Information retrieval systems typically operate by receiving a query and searching for pertinent information in a corpus of digital data—be it text, images, audio, video, or any other type of data. For example, Web search engines receive user queries and search for respective information in the World Wide Web. Technically, the searches are conducted in a centralized index of the World Wide Web maintained by each search engine, to facilitate near real-time provision of search results.
Information retrieval systems use a variety of techniques to ensure that their searches return results that are highly-relevant to the queries. Some techniques focus on the contents of searched documents as a source for information relevant to the query, while others focus on contextual information that is associated with the searched documents, such as anchor texts in HTML (HyperText Markup Language) documents on the World Wide Web. A survey of such techniques can be found in the seminal work of S. Brin and L. Page, "The anatomy of a large-scale hypertextual Web search engine," Computer Networks and ISDN Systems 30 (1998) 107-117.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the figures.

Document enrichment with conversation texts, for enhanced information retrieval

International Business Machines Corporation


A method of adjusting operation of an internal combustion engine includes injecting fuel into cylinders of the internal combustion engine (first fuel operation); obtaining a first fuel exhaust temperature profile during the first fuel operation; injecting two fuels into the cylinders in a duel fuel operation; obtaining a duel fuel exhaust temperature profile; and adjusting the injection quantity and/or an injection timing of one fuel in a cylinder(s), based on a difference between the first fuel exhaust temperature profile and the duel fuel exhaust temperature profile. Other methods of operating with single fuel and using sensors other than exhaust temperature sensors are disclosed.

The present application relates generally to internal combustion engines and more particularly to improved methods of cylinder balancing in an internal combustion engine.
Variation of operation parameters of cylinders in multi-cylinder engines can lead to an imbalance of power in cylinders. Variation from cylinder-to-cylinder of fuel quantity delivery may cause one, or more, cylinders to approach the knock limits of the fuel-air mixture, which ultimately can lead to performance degradation of the engine. Further, unbalanced engines may apply greater forces to engine components compared to balanced engines. These greater forces may produce premature wear and decreased reliability.
Spark-ignited and dual fuel internal combustion engines commonly balance cylinders via a controller collecting the measuring of the exhaust temperature of each cylinder and then adjusting an engine parameter, typically fuel quantity, spark timing or injection timing, in order to rebalance the cylinders so that the resultant cylinder exhaust temperatures more closely match each other. While this is a plausible methodology, cylinder-to-cylinder exhaust temperatures are not necessarily indicative of cylinder condition and may provide an inaccurate indication of actual cylinder conditions due to variations in (but not limited to): sensor response, sensor mounting, cylinder breathing, and the like.
Accordingly, there is an ongoing need for improving internal combustion engine operation through improved cylinder balancing.

Differential cylinder balancing for internal combustion engine


An electronic device may be provided that includes a first processor and a second processor, the first processor to wirelessly receive a data packet from another device, and to determine a property (or type) of the received data packet. When the property or type of the received data packet is a first property or first type then the first processor to process the data packet. On the other hand, when the property or type of the received data packet is a second property or second type then the second processor to process the data packet.

1. Field
Embodiments may relate to circuitry or logic to process data packets at a specific processor.
2. Background
A wearable device (or wearable sensing device) for health and wellness purposes may have a limited battery life based on processing and data buffering performed on the wearable device and based on form factor constraints, such as limited space and weight for larger batteries. A wearable device may have a battery life of 1-4 days, for example. Accordingly, sensor data may be offloaded from the wearable device to another electronic device, such as a smartphone. This may be done by continuously transferring data from the wearable device to the electronic device. However, this may decrease the battery life of the electronic device, such as battery life of the smartphone.

Electronic device having two processors to process data


Integration of semiconductor tool maintenance operations on mobile devices to allow technicians to more accurately perform semiconductor tool maintenance and to allow more accurate analysis of data to improve maintenance procedures to be more repeatable, consistent, and efficient. Remote control of maintenance operations for the semiconductor tool via a portable electronic device decreases the time required to service semiconductor tools and thus increase throughput.

Currently, semiconductor tool maintenance operations are tracked through manual forms. Though data from the forms may be used to improve semiconductor tool maintenance, the forms may be lost and analyzing hand written feedback may be inaccurate, laborious, or impossible due to volume and timing constraints. There is also loss of productivity when paper forms are transcribed into electronic database systems. The format of data entry used may also vary operator to operator resulting in difficulty applying standardized method of analysis. Analyzing the forms filled out by technicians is time consuming and, when forms are lost, may not provide accurate data on how to improve semiconductor tool maintenance. Additionally, current semiconductor tools require users to control the tool, whether during processing or during maintenance, through an interface located on the semiconductor tool, increasing maintenance times and decreasing throughput.

This patent is subject to a terminal disclaimer.

Mobile connectivity and control of semiconductor manufacturing equipment


A disclosed droplet discharge apparatus includes a droplet discharge head; a head sealing member that is disposed so as to face the droplet discharge head and that is moved to a position where a surface of the droplet discharge head is sealed off from outside of the head sealing member; and a suction force generator that generates a suction force inside the head sealing member. Further, the head sealing member moves droplets remaining on a nozzle surface of the droplet discharge head along the nozzle surface and suctioning as well as suctioning ink from a nozzle surface of the droplet discharge head.

1. Field of the Invention
The present invention generally relates to an image forming apparatus, and more particularly to a maintenance and recovery mechanism removing droplets and foreign matter remained and adhered to a droplet discharge section so that the discharge function of the droplet discharge apparatus is well maintained.
2. Description of the Related Art
As is well known, an image forming apparatuses such as a printer, a facsimile machine, a copier, and a multifunction peripheral having those functions includes a droplet discharge apparatus having a recording head including a droplet discharge head to discharge droplets such as ink.
In an apparatus discharging droplets such as ink, an image is formed by adhering or absorbing (impregnating) droplets discharged from a recording head onto or into a recording medium such a recording sheet while the recording medium is being fed.
In this case, the recording medium to be printed includes not only such a recording sheet but also any material to or into which a liquid can be adhered or absorbed, the material including fibers such as strings, leather, a metal, resin, glass, wood, ceramic and the like.
In such an image forming apparatus having the droplet discharge apparatus, ink retained on a nozzle surface of a droplet discharge head by surface tension of an ink meniscus is discharged (ejected) in a predetermined direction with a predetermined size by using a pressure caused by film boiling of ink or the like.
As a method of discharging droplets, there have been proposed a piezoelectric conversion method using a piezoelectric device, an electrostatic suction method using an electrostatic attractive force (see, for example, Japanese Patent Application Publication No. 2009-45870, "Patent Document 1"), a thermal conversion method such as bubble-jet (registered trademark) type (see, for example, Japanese Patent Application Publication No. 2007-290243, "Patent Document 2") and the like.
On the other hand, at the droplet discharge head, a maintaining and recovering operation is generally performed. By performing the maintaining and recovering operation, it becomes possible to prevent ink remained and adhered to a nozzle surface of the droplet discharge head from being thickened and avoid that ink is discharged in the direction other than a predetermined direction, that ink has a size other than a predetermined size, and that the meniscus of ink is destroyed (deformed) due to the ingress of foreign matter into the nozzle.
As an example of a structure performing the maintaining and recovering operation, a cap is used for sealing a nozzle surface of a liquid discharge head and a negative pressure is applied to the inside of the cap to suction ink from the nozzle (see for example, Japanese Patent No. 4149821, "Patent Document 3").
Further, as an example of a structure suctioning ink from the inside of the cap and cleaning the discharge head, a carriage is slightly moved during the suction operation so as to form a gap at a part of the cap to generate air flow within the cap to flow ink absorbed in an ink absorbing body from the nozzle surface to the absorbing section. Then, the nozzle surface is wiped by a wiper made of an elastomer material. By doing this, the nozzle surface is cleaned and the meniscus of ink in the nozzle is recovered (see, for example, Japanese Patent Application Publication No. 06-126947, "Patent Document 4").
However, in a case where ink accumulated in the nozzle or on the nozzle surface is suctioned in a manner as disclosed in Patent Document 3, when the cap is separated from the nozzle surface while the negative pressure is still large, a sudden pressure change may occur, and due to the sudden change of the pressure, the meniscus in the nozzle may be destroyed (deformed).
On the other hand, when the structure disclosed in Patent Document 4 is used, it may become easier to flow ink retained in the ink absorbing body. However, if the gap is not properly generated, a large amount of ink may be retained on the nozzle surface and the large amount of ink may be adhered to the wiper when the wiper wipes the ink. Because of this feature, when the ink adhered to the wiper is left for a long period, the ink may be thickened or may be fixed to the wiper. As result, the thickened or fixed ink may block the wiping capability of wiping the nozzle surface. In this case, the contacting area between the wiper surface and the nozzle surface may become smaller, thereby reducing the efficiency of removing ink from the nozzle surface. This phenomenon may affect the meniscus of ink and block normal discharging operation, which may degrade the quality of print data, increase maintenance cost of the wiper, and affect the maintenance and recovery mechanism of the apparatus.
Further, the gap to be formed at a part of the cap is formed while the cap is inclined against the nozzle surface due to the slight movement of the carriage. In this case, in order to ensure the sealing and adhesion performance between the cap and the nozzle surface, a flexible material such as elastomer is generally used. Because of this feature, for example, after the slight movement is repeated for a long period, the shape of the flexible material may not be easily recovered (i.e., the shape of the flexible material may be deformed), thereby making it difficult to maintain the sealing and adhesion performance.
On the other hand, ink retained on the surface of the nozzle surface is once absorbed (suctioned) into the ink absorbing body provided in the cap. After a certain time interval, the absorbed ink is further suctioned. Therefore, due to the time interval, ink may be thickened or fixed before being suctioned. In this case, the suctioning function may not be appropriately maintained.
Further, it may be required to fill the cap with ink in advance in order to remove ink retained on the nozzle surface. However, to fill the cap with ink, the suction operations is always required to be performed to withdraw ink from the inside of the nozzles. Because of this feature, ink filled in the cap may be unnecessarily wasted and ink consumption amount may be increased.
Next, with reference to FIGS. 1 through 4, a problem is described which may be occurred when such a method as disclosed in Patent Document 4 is used where a wiper wipes ink.
Conventionally, to perform the maintaining and recovering operation on the nozzles of the droplet discharge head, as schematically illustrated in FIG. 1, a cap B being in close contact with a nozzle surface A1 of a droplet discharge head A is used as a sealing member. Further, while the cap B is in close contact with the nozzle surface A1 of the droplet discharge head A, a negative pressure is applied to the inside of the cap B using a suction mechanism (not shown), so that droplets (i.e., ink L and foreign matter) are suctioned from nozzles A2.
After ink is suctioned from the nozzles A2, the cap B is separated from the nozzle surface A1 of the droplet discharge head A. As a result, as schematically illustrated in FIG. 2, a large amount of ink L′ withdrawn from the inside of the nozzles due to the negative pressure applied to the inside the cap A remains on the nozzle surface A1 of the droplet discharge head A in dorm shapes or in a combined shape.
Then, as schematically illustrated in FIG. 3, the remaining ink is wiped off by using a wiper C made of a material such as an elastomer. In this case, however, as schematically illustrated in FIG. 4, when the wiped ink is left on the wiper C for a period of time, the ink remaining on the wiper C may be thickened or fixed to the wiper C, which may block the further wiping operation. As a result, once the ink is thickened or fixed to the wiper C, ink on the nozzle surface A1 of the droplet discharge head A may not be sufficiently removed with the wiper C.
As described above, when a method as described in Patent Document 4 is used, when ink is suctioned to recover the meniscus of ink in the nozzle and ink remained on the nozzle surface is moved at the same time, there may arise a problem in further wiping operation and a problem in further suction operation.


A support for a mobile device which is provided on a mounted portion of a mobile device or a case of the mobile device to support the mobile device, includes: a fixing portion provided on the mounted portion; an extending portion extended while being drawn in or out in a longitudinal direction; a rotating portion provided between the fixing portion and the extending portion to relatively rotate the fixing portion; and an end support portion rotatably provided at an end of the extending portion.

Generally, a support for a mobile device is a device for supporting a mobile device such as a smart phone or a tablet PC to allow a user to use more conveniently the mobile device.
The support for the mobile device may be classified into a fixture-supported support which is placed on a fixture such as a table to support the mobile device, a hand-supported support which is inserted to a hand such as a finger to support the mobile device, and a bellows-connected support which uses a long bending allowable member (so called "bellows") to support the mobile device.
Specifically, the fixture-supported support is configured by one body and includes a support surface on which the mobile device is placed, an inclined surface which supports the bottom of the mobile device to provide an inclination angle to the mobile device placed on the support surface, and a bottom surface which is in surface contact with the fixture. The hand-supported support includes a case for holding the mobile device, a fixing plate attached to the bottom of the case through an adhesive tape or the like, and a metallic finger ring provided on the fixing plate to insert a user's finger. The bellows-connected support includes a fixing portion fixed to the fixture such as a table or the like, a holding portion for holding the mobile device, and a bending allowable member which connects the fixing portion and the holding portion and has an elongated shape, in which a bendable structure is elongated therein and an exterior is enclosed by an outer cover made of rubber or the like.
However, in existing supports for the mobile device, in the case of the existing fixture-supported support, there is a problem in that it is inconvenient in use because a thick book or the like needs to be filed below the mobile device in order to adjust a height of the mobile device such as adjusting the mobile device to the eye level, and in the case of the existing hand-supported support, there is a problem in that the adjusting to the eye level is easy, but it is difficult to use the mobile device for a long time due to the limitation of the power of the hand or arm that can be supported by the user. In addition, in the case of the existing bellows-connected support, there is a problem in that the portability is poor, and the support falls below an expected position due to the weight of the mobile device and rotates based on a fixed end while falling due to a cantilever structure, and thus, it is difficult to adjust the position such that the support needs to be lifted above the expected position in order to adjust an accurate eye level, and the support is further twisted in an opposite direction to the rotation direction than the expected position by considering the rotation.


Various embodiments provide a graphical element displayed through a mapping application that visually represents at least one point of interest (POI) data point on a map for a location. In one example, a single multi-dimensional graphical element can identify a location and identity of multiple POIs associated with the same geocode or physical location on a map, such as a multi-tenant building. In this example, each surface of the graphical element may represent a different POI. In another example, a multi-dimensional graphical element can identify a location and information for a single POI. In this example, each surface can represent different information, such as a surface for customer reviews, a surface for store hours, address, or contact information, a surface for a restaurant's menu, a surface for promotions, and the like.

Many people utilize computer-based mapping applications to obtain the locations of, and directions to, various locations, as well as to locate places near a current or specific location. A person wanting to perform such a task typically opens an application, inputs the necessary information (such as a location or point of interest) and receives location information, driving directions, nearby points of interest (POI) as determined by the mapping application provider, and other such information. The user might be interested in specific types of locations or points of interest that the user would like to include with the mapping information, but the point of interest information provided with the mapping application typically is selected by a provider of the mapping application and often relates specifically to businesses, public spaces, government buildings, and other such locations. The POI is not customized for the user, other than the user potentially being able to select subsets of the already-determined POI to obtain on a map. Further, conventional POI databases have been incomplete except for a few high volume/revenue categories (e.g., travel, restaurants, medical). Thus, in the past, the number of complete publishable POI records has been a subset of the total number of points of interest that actually exist. However, this trend is changing through a combination of databases expanding coverage and the creation of new POI models, which has created POI congestion in locations, such as multi-tenant facilities (e.g., office buildings, shopping malls, and the like). Therefore, as technology advances and as more and more POI become available, it can be advantageous to adapt the ways in which POI is presented to users and the ways in which users access the same.

User interface points of interest approaches for mapping applications


An actuator module for inducing the relative motion of robot members joined in a robot joint includes a Ferguson epicyclic gear train, integral motor and integrated control means. The gear train comprises a plurality of base gears connected to the robot members and a plurality of planet gear carriers, each planet gear carrier having a plurality of planet gears rotatably mounted therein. A motor integrated with certain gear train components induces the rotation of the planet gear carriers about or within the base gears. Because of the Ferguson paradox, this induces the motion of base gears connected to one robot member relative to those connected to the other robot member, which in turn causes the relative motion of the robot members. The actuator module can be configured as dual substantially symmetric systems and may comprise multiple stages of epicyclic gearing.

The present invention relates to an actuator module for inducing the relative motion of robot members joined in a robot joint, and a robot using the actuator module. In particular, the invention relates to an actuator module comprising a Ferguson epicyclic gear train, integral motor and integrated control means (brakes, encoders, sensors, etc.).
Today's robots are designed with virtually no standardization. This results in a costly technology which cannot rapidly adapt to emerging technologies and may be obsolete before it goes to production. Modularity would do much to reduce the level of cost and would reduce the threat of obsolescence, allowing rapid changeover in favor of improved module technology. The model of the personal computer can provide a benchmark for the benefits of modularity in another system architecture. While the original computers were dedicated mainframes, each designed separately with little compatibility from one generation to the next, the personal computer is now highly modular, layered, interfaced at each level, etc. in a nearly standardized format.
The pressing need is to develop a robot architecture which can rapidly evolve in the same fashion as is now feasible for personal computers. Existing drive systems usually include encoders, brakes, motors, drive trains and joint bearings, each provided with its own housing, mounting plates, wiring interfaces, etc. Before the present invention, no thought had been given to aggressively integrating these multi-component systems into a combined whole to reduce weight, size and complexity and to increase scalability and adaptability. The architecture which results from modularity maximizes the number of physical parameters still available so that a designer has a full selection with which to design.
Of course, there are literally billions of systems which can be derived from the hundreds of design parameters available. Hence, a strategy for design must be developed which allows optimum results to occur in smaller, more addressable packages. This is the primary design argument in favor of modularity in robotics. Evolutionary changes in previous designs are presently made without having the capability to make dramatic changes which could provide substantial benefits.
Although the need for modularity and compactness has been recognized in the prior art, see, e.g., U.S. Pat. Nos. 4,738,576 and 4,062,601, these proposed solutions retain such deficiencies as separately housed motors and unnecessary complexity.
The use of epicyclic gear trains is also known in the art. See, e.g., U.S. Pat. Nos. 4,686,402; 4,492,510; and Nasa Publication JSC-09709 (June 1975). These devices are particularly suited for robotics because of their compactness (for the reduction ratios possible), efficiency (and thus back-driveability), durability and smooth operation. As with most gear trains, however, the use of an epicyclic gear train typically adds a relatively heavy structure to the robot joint assembly. The prior art, characterized by separately-housed, discrete components and long force paths, has not provided an adequate solution to this and other stumbling blocks facing the development of robot-drive technology. Finally, none of the proposed solutions combine modularity and compactness with superior redundancy and stiffness characteristics.

Robot and robot actuator module therefor


An air-blower tidal power generation device includes a rack, an air-blower mechanism, and a power generation mechanism. The air-blower mechanism includes a pumping device, a buoy, and an air conduit. The pumping device includes a cylinder and a stationary barrel movably coupled together. The power generation mechanism includes a constant-pressure and pressure-regulation device and a power generator having an air-driven turbine. Thus, tides move the buoy up and down to drive the pumping device for cyclically drawing and pumping air, and the air is preserved in the constant-pressure and pressure-regulation device to provide a constant pressure for subsequent and stable supply of airflow to the turbine for driving the power generator to generate power.

Due to increasing demand of fossil energy, the price of oil is constantly increased. Thus, the advanced countries, such as Japan and European countries, devote a great amount of effort to develop power generation with waves and tides, which is often realized by providing a tidal power generator that is operated by the up and down movement tides to generate electrical power thereby converting the tidal energy into electrical energy. It is estimated that the world's power consumption can be satisfied by five times if 0.1% tidal energy of the world is converted into electrical energy. The storage of tidal energy is amazingly large.
Tidal power generation has been developed for hundreds of years, but no technical breakthrough has been done. A known tidal power generation device is disclosed in U.S. Pat. No. 6,717,284 B2, in the name of the present inventor, comprising a rack, an air-blower mechanism disposed at a predetermined position of the rack, the air-blower mechanism comprising an extendible cylinder, a buoy mounted to an end of the extendible cylinder and a tube mounted to another end of the extendible cylinder, the bottom of the buoy being positioned on the sea surface; a power generation mechanism comprising an air canister and a power generator having a pneumatically operated motor, the air canister being coupled to the tube, whereby the tides drive the air-blower mechanism to directly extract energy from the up and down movement of the tides for providing compressed air into the air canister from which airflow is released to drive the pneumatically operated motor of the power generator to thereby realize an air-blower tidal power generation device. The device utilizes the up and down movement of the tides, which causes a substantial difference in the height of the sea surface, to continuously drive the air-blower mechanism whereby compressed air can be obtained in all situations of large/small tides and high/low tides and stored in the air canister for subsequent supply to the pneumatically operated motor for driving the power generator. In this way, large construction and complicated mechanism can be omitted and power generation can be realized with a simple structure of the air-blower type tidal power generation device. Costs of installation and operation and time and effort required for installing the device are both reduced, which also result in easy maintenance.
The conventional air-blower type tidal power generation device, although effective in simplifying the structure and reducing costs for convenient generation of electrical power, suffers a disadvantage of instable supply of airflow of substantially fixed pressure. This is due to the fact that the air compressed and filled into the canister by the air-blower mechanism is continuously accumulated inside the canister and the internal pressure of the canister is increased with air filled into the canister. Thus, it is in general impossible to maintain constant pressure. Also, when air starts to discharge from the canister, the internal pressure of the canister is lowered. Thus, stable supply of constant pressure airflow is in general impossible.
Thus, the present invention is aimed to provide an air-blower tidal power generation device to overcome the drawbacks of the conventional devices.

Air-blower tidal power generation device


The present disclosure describes a three-dimensional object segmentation method and device, and medium, and relates to the field of computer vision (CV) technologies of an artificial intelligence (AI) technology. The method includes obtaining, by a device, a point cloud of a three-dimensional object. The device includes a memory storing instructions and a processor in communication with the memory. The method includes determining, by the device, three scaling directions of the point cloud; scaling, by the device, positions of points in the point cloud along the three scaling directions to obtain a scaled point cloud, so that the scaled point cloud has the same scale in the three scaling directions; and segmenting, by the device, the three-dimensional object based on the scaled point cloud to obtain a segmentation result.

Simulation-based physical simulation technology is an important branch of computer vision (CV) technologies, and is widely applied to films and televisions, animations, games, robot control, and the like. To efficiently and accurately simulate a collision in a real physical environment, or to enable a user to interact in real time, in game and film and television production, developers often use convex shapes, such as cylinders, ellipsoids, or convex polyhedrons, to approximate objects in a virtual world. However, in practice, there are a large quantity of concave objects. If a simple convex set is used for approximation, not only a large approximation error is caused, but also a false collision occurs.
To resolve this problem, convex segmentation needs to be performed on a three-dimensional object in the real physical environment. That is, the three-dimensional object is segmented into several sub-objects, and each sub-object is ensured to be a convex set.
Currently, a precise convex set segmentation algorithm exists. However, a computation amount of the algorithm increases exponentially. The algorithm not only is infeasible in calculation, but also segments excessive sub-objects, and is unfavorable for use in a simulation environment. To overcome these disadvantages, in the related art, an approximate convex set segmentation algorithm is further provided, and implements the equalization of a segmentation speed, a quantity and a simulation collision effect while allowing a local tiny depression.
An indoor environment is a classic physical simulation object. A shape of a three-dimensional object in the indoor environment is more complex, and collisions occur more frequently. This has a higher requirement on three-dimensional object segmentation. A large quantity of thin-walled objects such as wall surfaces, table tops, and various plates exist in the indoor environment, and many of the thin-walled objects further have hollowed-out structures, such as wall surfaces of doors and windows, drawers and cabinets. The existence of such objects further increases the difficulty of three-dimensional object segmentation.
The approximate convex set segmentation algorithm described above often has a poor segmentation effect on the thin-walled objects with the hollowed-out structures. Intuitively, this is because it is difficult for the traditional approximate convex set segmentation algorithm to effectively distinguish between the hollowed-out structures and small structural depressions of the thin-walled objects. Specifically, when segmenting the three-dimensional object, related approximate convex set algorithms are consistent in processing in all directions without considering special structures of the thin-walled objects, but the concavity of many thin-walled objects is extremely sensitive to the directions.
The present disclosure describes various embodiments for segmenting a three-dimension object, addressing at least some the problems/issues discussed above.

Method, device, and storage medium for segmenting three-dimensional object

TENCENT TECHNOLOGY (SHENZHEN) COMPANY LIMITED


A marine propulsion device includes an engine, a driveshaft powered by the engine, a propulsor shaft coupled in torque-transmitting relationship with the driveshaft, and a propulsor coupled to the propulsor shaft and rotatable to produce a thrust. A housing supports the propulsor shaft therein. The housing has fore and aft skegs projecting from a bottom surface thereof.

The following U.S. Patents and Patent Applications are incorporated herein by reference, in their entireties:
U.S. Pat. No. 5,085,603 discloses a marine drive having a trim tab with a flair on one side thereof at an upper portion. When the drive is trimmed in, the flair is unshrouded by the anti-ventilation plate and diverts mainstream water flow therearound, which produces a force on the other side of the trim tab opposite the flair which counteracts steering torque. In another embodiment, a variable compensation flair is provided.
U.S. Pat. No. 8,545,280 discloses a marine drive having a lower drive unit including a gearcase with a vertical strut having a lower horizontal torpedo with an aft propeller. An anti-ventilation plate on the strut is spaced above the torpedo. A spray shield plate on the strut is spaced above the torpedo and below the anti-ventilation plate.
U.S. Pat. No. 9,359,059 discloses an outboard marine engine comprising an anti-ventilation plate; a torpedo housing that is disposed below the anti-ventilation plate; and a gearcase strut that extends from the anti-ventilation plate to the torpedo housing. The gearcase strut has a leading end, a trailing end, and opposing outer surfaces that extend from the leading end to the trailing end. A flow separator is on each outer surface. The flow separator is located closer to the trailing end than the leading end and causes flow of water across the gearcase strut to separate from the outer surface.
U.S. application Ser. No. 16/171,490, filed Oct. 26, 2018, discloses an outboard motor having a powerhead that causes rotation of a driveshaft, a steering housing located below the powerhead, wherein the driveshaft extends from the powerhead into the steering housing; and a lower gearcase located below the steering housing and supporting a propeller shaft that is coupled to the driveshaft so that rotation of the driveshaft causes rotation of the propeller shaft. The lower gearcase is steerable about a steering axis with respect to the steering housing and powerhead.

Marine propulsion device and lower unit therefor


System and method in a network processor for performing cut-through forwarding of LANE packets without incurring the overhead associated with LANE protocol stack assisted routing. A content addressable memory (CAM) stores LEC uplink information including mapping between MAC destination addresses and VCC information. The network processor also stores LEC information table for corresponding VLAN identifiers and LECs. The LEC information table includes LEC ID information for the VLAN ID. For a LANE packet received from Ethernet and outbound to ATM destination, the network processor determines the LEC ID for the packet and then performs a CAM lookup to determine VCC information for the packet. The packet is then forwarded using the LEC ID and VCC information. For a LANE packet received from an ATM source and outbound to the Ethernet, the network processor determines the interface address of the packet. Based on the interface address, the network processor determines if the packet is a echoed or loopback packet or if its destination is the network processor itself. The packet is then routed to via the Ethernet if it is not a loopback or echo packet and the destination is not the network processor.

The present invention relates generally to computer networks and more particularly to techniques for performing high speed forwarding of traffic in an ATM network providing local area network emulation (LANE) services.
The Local Area Network Emulation (LANE) standard/protocol emulates a local area network (LAN) over an Asynchronous Transfer Mode (ATM) network. LANE thus allows existing LAN software applications to take advantage of the high bandwidth and quality of service offered by ATM networks without having to make significant changes to the LAN software applications. LANE allows ATM equipment and networks to be interconnected to existing LANs, and further allows logically separate LANs to be connected via an ATM backbone network. An emulated LAN (ELAN) provides for the communication of data frames among all users of the ELAN similar to a physical LAN.
Presently, LANE emulates either a Ethernet/IEEE 802.3 LAN or a IEEE 802.5 (Token Ring) type LAN. An emulated LAN typically comprises at least one LAN emulation client (LEC), a LAN emulation server (LES), a LAN emulation configuration server (LECS), and a broadcast and unknown server (BUS). The aforementioned components are logical entities and may be implemented in a single physical unit or in separate physical units.
A LEC represents one or more users requiring LAN emulation services. A LEC may be an end workstation, a switch, a network interface card, or even an ATM bridge connecting an ATM network to a legacy LAN. A LEC provides data forwarding, address resolution, and other networking functions for its associated end users. A LEC is generally identified by a LEC identifier (LEC ID) which is unique to the LEC within the network. A LEC is generally assigned to a LES. Communications between LECs are usually performed over ATM virtual channel connections (VCCs).
A LES implements the control coordination function for an emulated LAN. An LES provides address registration services allowing participants of an emulated LAN to register their media access control (MAC) and ATM addresses. An LES also provides address resolution services by implementing the address resolution protocol (ARP) which facilitates conversion between MAC and ATM addresses. A LEC typically queries the LES to which it is assigned to resolve MAC addresses. Communication between a LEC and a LES is usually performed over control VCCs established between the LEC and the LES. Each emulated LAN typically has one LES.
A LECS provides configuration services for the emulated LAN including assignment of individual LECs to various emulated LANs by giving the LECs the ATM address of an LES associated with the particular emulated LAN along with necessary operating parameters such as the type of the emulated LAN and the maximum frame size. A network typically has one LECS.
A BUS handles broadcasts and multicasts in the network. Data frames are generally sent to the BUS when either the information is to be transferred to workstations in the emulated LAN or when a source LEC has sent an ARP request to the LES, but does not wish to wait for a response before starting the data transfer to the destination LEC.
In order to route data frames from a source to a destination in an emulated LAN, each participant of the emulated LAN, for example, workstations, switches, network interface cards, and bridges, implements a LAN emulation protocol stack which performs the functions necessary to communicate the data frames from the source to the destination. A LAN emulation protocol stack is made of one or more protocol layers which provide services for communicating information to the appropriate destination. The functions corresponding to the protocol stack are generally executed by a microprocessor associated with the emulated LAN participant equipment.
With the ever increasing amount of pipe bandwidth available for data communication, it is desired that the protocol stack processing be performed at broadband speeds. For example, LAN traffic generated by 100 Bbps and Gigabit Ethernet migration are now required to fill multiple OC-3 or OC-12 SONET backbones in corporate enterprises. High-end routers are required to be able to feed OC-12 (622 Mbps) SONET pipes and OC-48 (2.4 Gbps) SONET pipes with millions of small packets per second.
Unfortunately, conventional protocol stack processing has been unable to proportionately scale with increasing bandwidth requirements. As a result, the slower processing speeds associated with protocol stack processing reduce the efficiency of bandwidth usage. Thus, there is a need for a technique which reduces the time associated with protocol stack routing and improves bandwidth usage in an emulated LAN network environment.
The present invention provides techniques to reduce the time associated with protocol stack routing in an emulated LAN network environment. According to the teachings of the present invention, a technique is described for performing cut-through forwarding of LAN emulation (LANE) packets without incurring the overhead associated with LANE protocol stack assisted routing. The teachings of the present invention may be used for performing cut-through forwarding of packets received from an Ethernet (including a Gigabit Ethernet) and outbound to the ATM network, or of packets received from the ATM network and outbound to the Ethernet (including a Gigabit Ethernet). The routing of LANE packets can accordingly be achieved in an expedited manner approaching broadband speeds.
According to an aspect of the present invention, a network processor coupled to an Ethernet and an ATM network supporting LANE services is responsible for performing cut-through forwarding of packets received from the Ethernet and outbound to the ATM network. In one embodiment, the network processor uses information contained in the header of the packet to determine if the packet is of type LANE or virtual LAN (VLAN). If the packet is of type LANE or VLAN, the network processor uses the VLAN ID in the packet header to determine the LANE emulation client (LEC) identifier (LEC ID) for the packet. The network processor also determines the virtual channel connection (VCC) information for the packet based on the medium access address (MAC) address contained in the packet header. The network processor may then use the LEC ID and the VCC information to forward the packet to its destination without having to go through protocol stack assisted routing.
According to another aspect of the present invention, the network processor stores LEC information for the LECs coupled to the ATM network. The LEC information contains LEC IDs for the LECs along with the VLAN IDs. Accordingly, in one embodiment, the present invention determines the LEC ID for the packet by using the VLAN ID of the packet as an index to the LEC information. The LEC ID may then be used for packet forwarding according to the teachings of the present invention.
According to yet another aspect of the present invention, the network processor stores LEC up-link information which facilitates mapping of MAC addresses to VCC information. In one embodiment, this information is stored in a content addressable memory (CAM) coupled to a packet forwarding subsystem within the network processor. In order to determine VCC information for the packet, the packet forwarding subsystem uses the MAC address of the packet as an input for CAM lookup. If the output of the CAM lookup indicates a hit, the CAM lookup output is used to determine the VCC information. In one embodiment, the CAM lookup output acts as an index to the VCC information for the input MAC address. The VCC information may then be used by the network processor for packet forwarding according to the present invention.
According to yet another aspect of the present invention, a network processor coupled to an Ethernet and an ATM network supporting LANE services is responsible for performing cut-through forwarding of packets received from an ATM network and outbound to the Ethernet. In one embodiment, the network processor uses information contained in the header of the packet to determine the interface address for the packet. Based on the interface address, the network processor determines if the destination of the packet is the network processor. If so, the packet is queued to the processor of the network processor for further processing. If the network processor is not the destination, the network processor forwards the packet to its destination via the Ethernet.
According to another aspect of the present invention, the network processor performs echo suppression to determine if the packet is a echo or loopback packet. The packet may be discarded if it is an echo or loopback packet. If the packet is not a loopback or echo packet, the packet is forwarded via the Ethernet. In one embodiment, echo suppression is achieved by comparing the LEC ID of the packet with the LEC ID stored in the LEC information corresponding to the packet. If the two LEC IDs are the same, this indicates a loopback or echo packet, and the packet is accordingly discarded.
According to yet another aspect of the present invention, the network processor may perform 801.1q tag discovery to determine the tag associated with the packet. Based on the tag, the network processor then determines if the packet violates any ingress policy. The packet may be discarded if an ingress policy is violated.
According to still another aspect of the present invention, the network processor adds a 802.1q tag to non-tagged packets. The network processor may then perform spanning tree detection based on the packet. The packet may then be forwarded based on the results of the spanning tree detection.
Other aspects and advantages of the invention will be better understood by reference to the following detailed description and the accompanying figures.

System and method for performing cut-through forwarding in an ATM network supporting LAN emulation