A method, system, and computer program product, include identifying a plurality of pollution process sets and determining pollution sources based on pollution start times of target pollution processes with matched features in the plurality of pollution process sets within a time window.
Please help me write a proper abstract based on the patent claims. CLAIM: 1. A computer-implemented method comprising: identifying a plurality of pollution process sets; and determining pollution sources based on pollution start times of target pollution processes with matched features in the plurality of pollution process sets within a time window. 2. The computer-implemented method according to claim 1, wherein the identifying a plurality of pollution process sets comprises: obtaining a group of pollution concentration observations from each of a plurality of observation stations, wherein the pollution concentration observation comprises pollution concentration value and observation time; for the group of pollution concentration observations, establishing a pollution curve model which comprises at least one valley point and at least one peak point; and identifying at least one pollution process based on the pollution curve model, the pollution process starting from a valley point and ending at a peak point following the valley point. 3. The computer-implemented method according to claim 2, wherein the establishing a pollution curve model comprises: establishing a pollution curve model by performing curve fitting on the group of pollution concentration observations. 4. The computer-implemented method according to claim 2, wherein the establishing a pollution curve model comprises: establishing a candidate pollution curve model based on the group of pollution concentration observations; counting extreme points of the candidate pollution curve model; adapting a degree of the candidate pollution curve model; estimating parameter values of the adapted candidate pollution curve model; counting the extreme points of the adapted candidate pollution curve model; calculating a change in the number of the extreme points between the adapted candidate pollution curve model and its previous candidate pollution curve model; and in response to the change being greater than a threshold, repeatedly performing the degree adaption, the parameter estimation, the counting of the extreme points and the change calculation; or in response to the change being less than or equal to the threshold, determining either of the candidate pollution curve model and the adapted candidate pollution curve model as the pollution curve model. 5. The computer-implemented method according to claim 2, wherein the identifying at least one pollution process based on the pollution curve model further comprises: tuning the at least one peak point and the at least one valley point of the pollution curve model. 6. The computer-implemented method according to claim 5, wherein the tuning the at least one peak point and the at least one valley point of the pollution curve model comprises: for each of the at least one peak point, determining a maximum pollution concentration value in the group of pollution concentration observations within a time period from the previous valley point of the current peak point to the next valley point; and tuning a value of the current peak point to the maximum pollution concentration value and the time of the current peak point to the observation time of the maximum pollution concentration value; and for each of the at least one valley point, determining a minimum pollution concentration value in the group of pollution concentration observations within a time period from the previous peak point of the current valley point to the next peak point; and tuning a value of the current valley point to the minimum pollution concentration value and the time of the current valley point to the observation time of the minimum pollution concentration value. 7. The computer-implemented method according to claim 1, wherein the determining pollution sources based on pollution start times of target pollution processes with matched features in the plurality of pollution process sets within a time window comprises: determining the target pollution processes which occurred within the time window and have the matched features from the plurality of pollution process sets; and determining the pollution sources based on the pollution start times of the target pollution processes. 8. The computer-implemented method according to claim 7, wherein the determining the target pollution processes which occurred within the time window and have the matched features from the plurality of pollution process sets comprises: determining, for each of the plurality of pollution process sets, at least one pollution process which overlaps with the time window, as candidate pollution process; determining the target pollution processes having the matched features from the candidate pollution processes; and obtaining the pollution start times of the target pollution processes. 9. The computer-implemented method according to claim 1, wherein the target pollution processes with matched features are the pollution processes between which similarity is greater than a predetermined threshold. 10. The computer-implemented method according to claim 7, wherein the determining the pollution sources based on the pollution start times of the target pollution processes comprises: sorting a plurality of observation stations associated with the target pollution processes according to the pollution start times the target pollution processes; and arranging the pollution sources located within coverage areas of the plurality of observation stations in the order of the plurality of observation stations. 11. The computer-implemented method according to claim 7, wherein the determining the pollution sources based on the pollution start times of the target pollution processes comprises: grouping a plurality of observation stations associated with the target pollution processes into multiple groups of observation stations according to the pollution start times of the target pollution processes; generating a pollution source group for each of the multiple groups of observation stations, the pollution source group comprising the pollution sources located within coverage areas of the observation stations in the group of observation stations; and arranging the pollution source groups in the order of the pollution start times of the target pollution processes. 12. The computer-implemented method according to claim 7, wherein the determining the pollution sources based on the pollution start times of the target pollution processes comprises: sorting a plurality of observation stations associated with the target pollution processes according to the pollution start times of the target pollution processes; and determining the pollution sources located within coverage areas of a given number of the observation stations which are arranged at high position. 13. The computer-implemented method according to claim 1 further comprising: analyzing contributions of the determined pollution sources. 14. The computer-implemented method of claim 1, embodied in a cloud-computing environment. 15. A system comprising: one or more processors; a memory coupled to at least one of the processors; a set of computer program instructions stored in the memory and executed by at least one of the processors in order to perform actions of: identifying a plurality of pollution process sets; and determining pollution sources based on pollution start times of target pollution processes with matched features in the plurality of pollution process sets within a time window. 16. The system according to claim 15, wherein the set of computer program instructions is executed by at least one of the processors in order to identify a plurality of pollution process sets by: obtaining a plurality of groups of pollution concentration observations from a plurality of observation stations, wherein the pollution concentration observation comprises pollution concentration value and observation time; for each of the plurality of groups of pollution concentration observations, establishing a pollution curve model which comprises at least one valley point and at least one peak point; and identifying at least one pollution process based on the pollution curve model, the pollution process starting from a valley point and ending at a peak point following the valley point. 17. The system according to claim 15, wherein the set of computer program instructions is executed by at least one of the processors in order to determine pollution sources based on pollution start times of target pollution processes with matched features in the plurality of pollution process sets within a time window by: determining the target pollution processes which occurred within the time window and have the matched features from the plurality of pollution process sets; and determining the pollution sources based on the pollution start times of the target pollution processes. 18. The system according to claim 17, wherein the set of computer program instructions is executed by at least one of the processors in order to determine the pollution processes which occurred within the time window and have the matched features from the plurality of pollution process sets by: determining, for each of the plurality of pollution process sets, at least one pollution process which overlaps with the time window, as candidate pollution process; determining the target pollution processes having the matched features from the candidate pollution processes; and obtaining the pollution start times of the target pollution processes. 19. The system according to claim 15, embodied in a cloud-computing environment. 20. A computer program product, the computer program product comprising a computer-readable storage medium having program instructions embodied therewith, the program instructions being executable by a computer to cause the computer to: identifying a plurality of pollution process sets; and determining pollution sources based on pollution start times of target pollution processes with matched features in the plurality of pollution process sets within a time window.