What is claimed is:
1. An air intake system of an internal combustion engine having an intake passage divided into a first passage and a second passage downstream of a throttle valve and a control valve provided in said first passage for controlling a flow of air, comprising:
an electronic control unit provided to open and hold said control valve at a specified opening angle while said engine is inoperative after said engine is stopped.
2. The air intake system according to claim 1, wherein
said electronic control unit is adopted to fully close said control valve before opening said control valve at said specified opening angle.
3. The air intake system according to claim 1, wherein
said specified opening angle is preferably less than 15 degrees.
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 quantization apparatus that performs multiple-stage quantization by using tree search, comprising:
a search section that matches each of one or more of encoding targets with a code vector stored in a codebook to select a certain number of candidates including one in order of smaller quantization distortion, the number of candidates being determined in a preceding stage or determined beforehand;
a calculation section that calculates a quantization error vector by subtracting the code vector from the target for each of the candidates; and
a candidate number determination section that determines a certain number of candidates to be used in a subsequent stage, on the basis of the number of candidates determined in the preceding stage.
2. The quantization apparatus according to claim 1, wherein the candidate number determination section determines the number of candidates to be used in the subsequent stage by reducing by one from the number of candidates determined in the preceding stage.
3. The quantization apparatus according to claim 1, wherein, in the case where the number of candidates determined in the preceding stage is not greater than a value P specified beforehand, the candidate number determination section determines that, when a value of the quantization distortion is larger than a predetermined threshold value, the value P is used as the number of candidates in the subsequent stage, and determines that, when the value of the quantization distortion is not greater than the predetermined threshold value, a value Q smaller than the value P specified beforehand is used as the number of candidates in the subsequent stage.
4. The quantization apparatus according to claim 1, wherein, in a first stage of the multiple-stage quantization, the search section selects a pre-specified number of candidates in order of candidates having smaller quantization distortion.
5. The quantization apparatus according to claim 1, wherein, in the case where a present number of stages is at least a predetermined number of stages, or the number of candidates is not greater than a predetermined number of candidates P,
the candidate number determination section determines that a predetermined number of candidates R is used in the subsequent stage, when a value of the quantization distortion is larger than a predetermined threshold value and also the number of candidates is smaller than the predetermined number of candidates R, and
the candidate number determination section determines that a predetermined number of candidates Q is used in the subsequent stage when the value of the quantization distortion is the predetermined threshold value or less and also the number of candidates is smaller than the predetermined number of candidates Q smaller than the number of candidates R.
6. A quantization method configured to perform multiple-stage quantization by using tree search, comprising:
matching each of one or more encoding targets with a code vector stored in a codebook to select, in a first stage, a certain number of candidates including one in order of smaller quantization distortion, the number of candidates being determined beforehand, and to select, in a second stage and in a stages subsequent to the second stage, a certain number of candidates in order of smaller quantization distortion, the number of candidates being determined in a preceding stage;
calculating a quantization error vector by subtracting the code vector from the target for each of the candidates; and
determining the number of candidates to be used in the subsequent stage, on the basis of the number of candidates determined in the preceding stage.