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As an important aspect of concrete durability damage, sulfate corrosion has attracted more and more people's general attention. Studying the durability of concrete against sulfate corrosion is conducive to ensuring the non-hazardous design of the concrete structure in the project, which is also very helpful to predict the service life of the project. This study simulates the corrosion characteristics of various sulfates on concrete under dry-wet cycle condi-tions through experimental methods, and studies the changes in the apparent characteristics, quality, deformation, and strength of concrete as the corrosion time increases. Based on the principle of fracture mechanics, three-point bending specimens are used to analyze the change mechanism of concrete fracture parameters under corrosion time, and to obtain the sulfate corrosion depth of concrete. According to the sulfate corrosion test, compared with the test samples without sulfuric acid corrosion solution, the test samples immersed in sulfuric acid concentration of 2.5% (A2.5 solution) and 10% (A10 solution) are all eroded by sulfur ions. After 30d-300d immersion in A2.5 and A10 solutions, the change trend of axial compressive strength and splitting tensile strength is basically the same. The corrosion time of 60d is the turning point of the change in the compressive strength of concrete. After a 300d test process, the compressive strength and tensile strength of the concrete in these two solutions are reduced to the lowest value. The compressive strength is 22.13 in the A2.5 solution and 21.13 in A10 solution, respectively, while the tensile strength is 1.83 in A2.5 solution and 1.81 inAlO solution, respectively. The changes of concrete axial compressive strength and splitting tensile strength with corrosion time are roughly the same, and both show a two-stage change pattern of first increasing and then decreasing. The difference is that the increase of the splitting tensile strength is at the initial stage of corrosion is smaller, but the deterioration is more serious in the later stage of the corrosion, indicating that sulfate corrosion has a greater impact on the splitting tensile strength of concrete. [ABSTRACT FROM AUTHOR]

In electronic ticketing system, the malicious behavior of scalpers damages the customer's interest and disturbs the normal order of market. In order to solve the problem of scalpers, we took two steps. Firstly, we established the electronic ticketing system based on the consortium blockchain (CB-ETS). By establishing CB-ETS, we can make the ticketing market develop better in a controlled environment and be managed by the members in the consortium blockchain. Secondly, we put forward a kind of taxation mechanism for suppressing scalpers based on CB-ETS. Together with the regulatory mechanism, our scheme can effectively reduce the scalpers' profits and further inhibit scalpers. Through the above two steps, the scheme can effectively resist the malicious behavior of scalpers. Among them, in the process of transferring tickets, we optimized the transfer mechanism to achieve a win-win situation. Finally, we analyzed the security and efficiency of our scheme. Our scheme realizes the anonymity through the mixed currency protocol based on ring signature and guarantees the unforgeability of tickets by multi-signature in the process of modifying the invalidity of tickets. It also could resist to Dos attacks and Double-Spending attacks. The efficiency analysis shows that our scheme is significantly superior to relevant works. [ABSTRACT FROM AUTHOR]

The tropical rainforest of Xishuangbanna (XSBN) in the southern Yunnan province is the most intact tropical rainforest of the high-latitude and high-altitude areas in China, and the only oasis at the latitude of 21 degrees north. However, large-scale rubber planting has seriously damaged the ecological environment in recent decades. The relationship between the carbon (C) and nitrogen (N) contents of soil and the stand age has been discussed based on the organic carbon (SOC) and nitrogen (STN) content of soil, the C/N variation in rainforests, and rubber plantation at different stand ages (10a, 22a, 30a). Furthermore, we analysed the factors influencing the variation of soil carbon and nitrogen. The results showed that the contents of SOC, STN, and C/N decreased with the depth of the soil profile in the study area at the same stand age. The order of the SOC content of different rubber stand ages at the same depth was generally as follows: 22a >30a >10a. The STN pattern from 30 cm depth to the top was 22a >10a >30a and the variation regularity was not significant below 30 cm. However, the value of C/N increased gradually with the age of the rubber trees. This indicates that the SOC and STN contents are significantly affected by the soil depth and stand age. Compared with the rainforest in the same region, the lower SOC and STN concentrations and the higher C/N of the rubber plantation demonstrated the effect of the rubber plantation on the carbon storage and nutrient utilization, which is much lower than that of virgin forest. Human activities (such as tapping) further intensified the loss of nitrogen in the soil. [ABSTRACT FROM AUTHOR]

Through investigating total phosphorus (TP) and ammonia nitrogen (NHj-N) concentrations of Baoxiang River, the spatial-temporal patterns and influencing factors of the TP and NH3-N pollution were studied. The results showed that the TP concentration increased gradually from the upper to lower reaches of the river, and TP concentrations at the town sites of Xiaobanqiao and Guandu were 0.5mg/L from July to September 2013, equalling or far exceeding the water quality V standard of surface water. Moreover, the correlation analysis indicated a strong relationship between TP concentrations and the precipitation of Kunming city, with R2 of 0.17-0.68. However, the NH3-N concentration showed no significant pattern, with the high NH3-N values found in the site of Baitu town, Dashiba and Ganhaizi. The relationship between the NH3-N concentration of the river and the precipitation was insignificant. In the inverse distance weighted (IDW) analysis, the variations of the TP and NH3-N in the Baoxiang River were calculated. The high concentration area of TP was mainly located in the downstream region of the Baoxiang River, and the NH3-N concentration exceeded the groundwater quality of Grade III throughout the year. All of these demonstrate that the TP concentrations of Baoxiang River was mainly influenced by the precipitation of Kunming city, and the frequent agriculture cultivation has further increased the loading of NH3-N concentration in the Baoxiang River. In addition, the amount of domestic sewage, which comes from the densely populated residential and popular tourist area of Kunming city, has exacerbated the eutrophication of Baoxiang River. [ABSTRACT FROM AUTHOR]