1. An exhaust gas system for an internal combustion engine, the exhaust gas system comprising:
a first exhaust gas treatment unit with a first back pressure; and
a second exhaust gas treatment unit with a second back pressure being higher than said first back pressure;
said first exhaust gas treatment unit being disposed at a first distance upstream of said second exhaust gas treatment unit, in exhaust gas flow direction, causing a gas flow entering said first exhaust gas treatment unit during operation to be homogenized.
2. The exhaust gas system according to claim 1, wherein said first distance is selected to cause an effect of said first back pressure and of said second back pressure to accumulate.
3. The exhaust gas system according to claim 1, wherein said first exhaust gas treatment unit has a gas inlet end side, and said second exhaust gas treatment unit has a gas inlet end side spaced from said gas inlet end side of said first exhaust gas treatment unit by a second distance of less than 60 mm.
4. The exhaust gas system according to claim 1, wherein said first exhaust gas treatment unit has a gas inlet end side, and said second exhaust gas treatment unit has a gas inlet end side spaced from said gas inlet end side of said first exhaust gas treatment unit by a second distance of less than 45 mm.
5. The exhaust gas system according to claim 1, wherein said first exhaust gas treatment unit has a gas inlet end side, and said second exhaust gas treatment unit has a gas inlet end side spaced from said gas inlet end side of said first exhaust gas treatment unit by a second distance of less than 30 mm.
6. The exhaust gas system according to claim 1, wherein said first exhaust gas treatment unit has an extent, in said exhaust gas flow direction, of less than 45 mm.
7. The exhaust gas system according to claim 1, wherein said first exhaust gas treatment unit has an extent, in said exhaust gas flow direction, of less than 35 mm.
8. The exhaust gas system according to claim 1, wherein said first exhaust gas treatment unit has an extent, in said exhaust gas flow direction, of 25 mm or less.
9. The exhaust gas system according to claim 1, wherein said first distance between said first exhaust gas treatment unit and said second exhaust gas treatment unit is less than 15 mm.
10. The exhaust gas system according to claim 1, wherein said first distance between said first exhaust gas treatment unit and said second exhaust gas treatment unit is less than 10 mm.
11. The exhaust gas system according to claim 1, wherein said first distance between said first exhaust gas treatment unit and said second exhaust gas treatment unit is less than 5 mm.
12. The exhaust gas system according to claim 1, wherein at least one of said exhaust gas treatment units includes at least one honeycomb body.
13. The exhaust gas system according to claim 1, wherein at least said first exhaust gas treatment unit includes a catalytically active coating.
14. The exhaust gas system according to claim 1, wherein said first back pressure and said second back pressure are in a ratio greater than 2.
15. The exhaust gas system according to claim 1, wherein said first back pressure and said second back pressure are in a ratio greater than 10.
16. The exhaust gas system according to claim 1, wherein said second exhaust gas treatment unit includes at least one component selected from the group consisting of:
(a) an open particle filter;
(b) a closed particle filter; and
(c) an SCR catalytic converter.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A search method comprising:
according to query data submitted by a client, obtaining a first search result set of first search results relevant to the query data;
according to a first relevance score and a preset diversity field of each first search result in the first search result set, calculating a second relevance score of each first search result, the preset diversity field representing an attribute category of a respective first search result;
according to the first relevance score and the second relevance score, generating a relevance parameter score for each first search result; and
according to a preset number of second search results and the relevance parameter score, extracting the present number of second search results from the first search result set to display to the client.
2. The method as recited in claim 1, wherein calculating the second relevance score of each first search result comprises:
according to the preset diversity field of each first search result in the first search result set, classifying the first search result set to obtain a respective subset corresponding to each respective attribute category of the first search result set;
according to the first relevance score in each subset, obtaining a corresponding ranking position of a respective first search result; and
according to a preset relationship between the ranking position of the respective first search result and the second relevance score, obtaining the second relevance score of each first search result.
3. The method as recited in claim 2, wherein extracting the preset number of second search results from the first search result set to display to the client comprises:
according to the relevance parameter score, ranking each subset after classification of the first search results; and
according to a ranking order, extracting the preset number of second search results respectively from the ranked subsets, the preset number of second search results being a product of a number of diversity values and a number of recurring extractions.
4. The method as recited in claim 1, further comprising:
storing the query data, the preset number of second search results, and a corresponding relationship between the query data and the preset number of second search results into a database.
5. The method as recited in claim 1, wherein obtaining the first search result set of first search results relevant to the query data comprises:
according to the first relevance score, conducting a search based on the query data submitted by the client; and
according to the preset diversity field, extracting the first search results from search results of the search.
6. The method as recited in claim 1, further comprising:
displaying the preset number of second search results to the client.
7. The method as recited in claim 1, wherein generating the relevance parameter score of each first search result comprises:
summing the first relevance score and the second relevance score to provide the relevance parameter score for each first search result.
8. A search system comprising:
a retrieval unit that, according to query data submitted by a client, obtains a first search result set of first search results relevant to the query data;
a calculation unit that, according to a first relevance score and a preset diversity field of each first search result in the first search result set, calculates a second relevance score of each first search result, the preset diversity field representing an attribute category of a respective first search result;
a configuration unit that, according to the first relevance score and the second relevance score, generates a relevance parameter score of each first search result; and
an extraction unit that, according to a preset number of second search results and the relevance parameter score, extracts the present number of second search results from the first search result set to display to the client.
9. The system as recited in claim 8, wherein the calculation unit comprises:
a first retrieval sub-unit that, according to the preset diversity field, classifies the first search result set to obtain a respective subset corresponding to each respective attribute category of the first search result set;
a second retrieval sub-unit that, according to the first relevance score in each subset, obtains a corresponding ranking position of a respective first search result; and
a matching unit that, according to a preset relationship between the ranking position of each first search result and the second relevance score, obtains the second relevance score of the respective first search result.
10. The system as recited in claim 9, wherein the extraction unit comprises:
a ranking sub-unit that, according to the relevance parameter score, ranks each first search result; and
a first extraction sub-unit that, according to a ranking order, extracts the preset number of second search results from the ranked subsets, the preset number of second search results being a product of a number of diversity values and a number of recurring extractions.
11. The system as recited in claim 8, further comprising:
a store unit that stores the query data, the preset number of second search results, and a corresponding relationship between the query data and the preset number of second search results into a database.
12. The system as recited in claim 8, wherein the retrieval unit comprises:
a searching sub-unit that, according to the first relevance score, conducts a search based on the query data submitted by the client; and
a second extraction sub-unit that, according to the preset diversity field, extracts first search results from search results of the search.
13. The system as recited in claim 8, further comprising:
a display unit that displays the preset number of second search results to the client.
14. The system as recited in claim 8, wherein the configuration unit sums the first relevance score and the second relevance score to provide the relevance parameter score of each first search result.