71 results about "Saturation flow rate" patented technology

An arbiter for a switch maintains a pair of counters for each flow of traffic at each input port: one counter (also called “first counter”) to indicate an ideal transfer of traffic, and another counter (also called “second counter”) to indicate the actual transfer of traffic. Both counters are incremented when traffic is received by the input port, and the second counter is decremented when a unit of traffic (such as a cell or packet) is about to be transmitted whereas the first counter is decremented in a fractional manner (relative to the unit of traffic) in each period of arbitration, based on available bandwidth. The arbiter selects one of the output ports (also called “winning output port”) of the switch, based at least partially on values of the two counters for each flow from the input port to one of the output ports, and generates a signal to approve transfer of traffic from the input port to the winning output port. In several embodiments, the above-described flow can be for either high priority traffic or for low priority traffic, and any bandwidth leftover from transferring high priority traffic is used in transferring low priority traffic. Specifically, the arbiter maintains additional counters for each port indicative of total bandwidth being used, and the additional counters are used to allocate leftover bandwidth in an iterative manner, until a flow from an input port to an output port is saturated, at which time the saturated flow is removed from iteration.

The invention discloses a crossroad traffic signal lamp real time dynamic timing method, relating to the road traffic control field. The crossroad traffic signal lamp real time dynamic timing method comprises steps of defining phases of various traffic flow directions of a crossroad, determining a saturation flow of each phase, measuring multiple current flows of each phase, obtaining a biggest current flow of each phase, calculating a relative biggest flow ratio of each phase and crossroad flow intensity, designing a target function and solving the target function to obtain a theoretical effective green light time of each phase, determining a signal lamp cycle time according to the theoretical effective green light time of each phase and crossroad signal lamp total loss time, and determining the practical effective green light time of each phase according to a ratio of the relative biggest flow ratio of each phase to crossroad flow intensity in the signal lamp cycle. The crossroad traffic signal lamp real time dynamic timing method avoids the fact that the vehicle starts and stops frequently in a congestion road due to the short cycle, improves a traffic capacity of the congestion road, reduces the parking rate of the congestion rate and has good robustness.

An evaluation method for motor vehicle exhaust gas diffusion at a structured intersection comprises the following steps of: 1, calculating the intensity of an emission source of a road segment line source according to parameters such as traffic flow of vehicles passing through a road segment, the proportions of various vehicle models and an emission factor; 2, converting idling emission of a queuing road segment into the intensity of a virtual line source according to parameters such as traffic flow arrival rate of the traffic flow queuing road segment, traffic signal green ratio, lane saturation flow rate, the proportions of various vehicle models and the emission factor and with reference to a CAL3QHC mode of an intersection exhaust gas diffusion mode; 3, building a coordinate system by taking an intersection center as an original point, and calculating corresponding concentration component values CA, CB, CC and CD of an arbitrary receiving point in an intersection region on a plane with a height value z in intersections A, B, C and D respectively, wherein CA is in the intersection A and is the pollutant concentration far away from the virtual line source 1 by L1; 4, calculating the pollutant concentration C of the receiving point according to the concentration of two segments of street canyons and a wind angle Theta in an upwind direction of the receiving point in the intersections; and 5, acquiring the pollutant concentration value C of the receiving point of which the concentration is within the period.

The invention provides a Gaussian process regression saturation flow rate detection method. The method comprises the steps that 1) original passing time data of a certain lane of an intersection at astop line during a period of interest are acquired; 2) the original passing time data are pre-processed to acquire passing time data; 3) instantaneous flow data and the passing time data in a cycle are calculated by using a timing scheme and the passing time data; 4) a Gaussian process regression method is used to fit an instantaneous flow rate curve based on the instantaneous flow rate data and the passing time data in the cycle; and 5) the maximum value of the instantaneous flow rate curve is solved and is used as the detection value of the saturation flow rate. Compared with the prior art,the method provided by the invention fully exploits intermittent traffic flow information contained in passing time big data at the stop line at the intersection, and acquires the saturation flow ratedetection value which is more accurate.

The invention provides a system, a method and a device for determining traffic saturation, and relates to the field of traffic signal lamp control. The method includes acquiring vehicle occupation data in red lamp phase durations; determining demand traffic volumes of corresponding lanes of to-be-detected phase according to comparison results of occupation time of the vehicle occupation data and preset occupation time; determining the traffic saturation according to the demand traffic volumes of the corresponding lanes of the to-be-detected phase, saturation flow rates and timing information of signal periods to which the red lamp phase durations belong. The vehicle occupation data are transmitted by upstream detectors in the corresponding lanes of the to-be-detected phase. The traffic saturation corresponds to the to-be-detected phase. The system, the method and the device have the advantages that separate point detectors of the corresponding lanes of the to-be-detected phases and thetiming information of the signal periods corresponding to the to-be-detected phase are combined with one another, accordingly, the traffic demand volumes of the corresponding lanes of the to-be-detected phase can be accurately measured, and the computational accuracy of the traffic saturation can be improved.

The invention provides an adaptive signal control optimization method for an urban main and branch intersection. The method comprises the following steps: establishing a combined algorithm based on fuzzy control and machine learning, determining a signal period according to a real-time saturation flow rate (RS) and a flow change ratio (RR) of the intersection, and calculating according to a Q-learning algorithm to obtain the green light duration of each phase. The method can adaptively optimize the time length of the signal lamp at the main and branch intersection of the city according to the change of the traffic operation environment, improves the traffic efficiency, safety and stability of the traffic flow at the intersection, saves the manual intervention cost, and is wide in application range and easy to popularize.