Application of k-person and k-task maximal efficiency assignment algorithm to water piping repair

Solving the absent assignment problem of the shortest time limit in a weighted bipartite graph with the minimal weighted k-matching algorithm is unsuitable for situations in which large numbers of problems need to be addressed by large numbers of parties. This paper simplifies the algorithm of searching for the even alternating path that contains a maximal element using the minimal weighted k-matching theorem and intercept graph. A program for solving the maximal efficiency assignment problem was compiled. As a case study, the program was used to solve the assignment problem of water piping repair in the case of a large number of companies and broken pipes, and the validity of the program was verified.

Research progresses on equipment technologies used in safety inspection,repair,and reinforcement for deepwater dams

China’s many dams are increasingly facing safety problems resulting from the natural aging of the dam hydraulic structure and geological disasters such as earthquakes under the operating condition of holding a vast amount of water.Problems such as dam leakage and concrete cracking and erosion seriously affect the normal operation and effectiveness of a reservior.It is impossible to empty a large reservoir with a high dam for many reasons,such as serious environmental consequences,and it is thus difficult to detect the working conditions of the underwater part of the facility.There is an increasingly urgent demand for detection and repair technologies that can be used in the deepwater environment.Indeed,there are cutting-edge deepwater detection and processing technologies for hidden dangers in dam engineering.The core technologies include underwater detection equipment,diving technologies,and underwater operation technologies.This paper analyzes safety-oriented detection equipment recently used in unmanned detection,manned detection,and deepwater diver detection from the viewpoint of practical application.The paper further reviews 100-m-depth-class technologies and applications of safety inspection,repair,and reinforcement equiment in the deepwater environment of reservoir dams.An outlook is provided on technology trends of deepwater detection,repair,and reinforcement and critical problems.

UV light tolerance and reactivation potential of tetracycline-resistant bacteria from secondary effluents of a wastewater treatment plant

Tetracycline-resistant bacteria（TRB） are of concern as emerging microbial contaminants in reclaimed water.To understand the effects of UV disinfection on TRB,both inactivation and reactivation profiles of TRB,as well as 16 tetracycline-resistant isolates from secondary effluent,were characterized in this study.The inactivation ratio of TRB was significantly lower（3.0-log） than that of heterotrophic bacteria（〉4.0-log） in the secondary effluent.Additionally,the proportion of TRB significantly increased from 1.65%to 15.51%under20 mJ/cm^2 ultraviolet（UV） exposure.The inactivation rates of tetracycline-resistant isolates ranged from 0.57/s to 1.04/s,of which tetracycline-resistant Enterobacter-1 was the most tolerant to UV light.The reactivation of TRB,tetracycline-resistant isolated strains,as well as heterotrophic bacteria commonly occurred in the secondary effluent even after20 mJ/cm^2 UV exposure.The colony forming ability of TRB and heterotrophic bacteria reached 3.2-log and 3.0-log under 20 mJ/cm^2 UV exposure after 22 hr incubation.The final inactivation ratio of tetracycline-resistant Enterobacter-1 was 1.18-log under 20 mJ/cm^2 UV exposure after 22 hr incubation,which is similar to those of TRB（1.18-log） and heterotrophic bacteria（1.19-log）.The increased proportion of TRB and the reactivation of tetracycline-resistant enterobacteria in reclaimed water could induce a microbial health risk during wastewater reuse.