119 research outputs found

    Human-System Integration

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    Experimental study on shear mechanical properties of improved loess based on rubber particle incorporation and EICP technology

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    Loess is often not suitable for direct use as a roadbed or building foundation due to its collapsibility, and it needs to be improved by adding curing agents. Taking the loess in Xi’an area as the research object, the reinforcement of loess was carried out using waste tire rubber particles and Enzyme Induced Carbonate Precipitation (EICP) technology. The change of shear strength and shear strength index of improved soil with rubber content and rubber particle size under different strengthening conditions was analyzed, and the strengthening mechanism was also expounded. The results show that rubber powder can improve the shear strength of loess to a certain extent, and the combination of EICP technology can increase the strength of improved loess by nearly 50%. In addition, rubber particles have a certain inhibitory effect on EICP, and the shear strength growth rate decreases with the increase of rubber content. When the rubber particle size is 1–2 mm, the shear strength growth rate is the highest. It is suggested that when adding rubber particles or adding rubber particles combined with EICP technology is used to improve loess, the rubber particle size should be selected as 1–2 mm, and the content is about 10%. The test results can provide a scientific basis for the reduction of geologic disasters in loess areas, and at the same time can provide a non-polluting way for the disposal of waste tires

    Global Solution to the Three-Dimensional Incompressible Flow of Liquid Crystals

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    The equations for the three-dimensional incompressible flow of liquid crystals are considered in a smooth bounded domain. The existence and uniqueness of the global strong solution with small initial data are established. It is also proved that when the strong solution exists, all the global weak solutions constructed in [16] must be equal to the unique strong solution

    Static pressure and dynamic impact characteristics of filled jointed rock after frozen-thaw cycle damage

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    In the construction project, rock mass is often destroyed from the joint plane, and the jointed rock mass is easy to be eroded by freeze-thaw environment. Therefore, the damage mechanical properties of filled jointed rock mass under freeze-thaw action are very important for construction disaster prevention, engineering safety evaluation and reinforcement. In order to research the effect of the freeze-thaw cycle on the mechanical deterioration properties and damage characteristics of filled jointed rocks, prefabricated filled jointed rock samples are tested with different numbers of freeze-thaw cycles under the temperature range of -20°C~20°C. Then the wave velocity test, static compression test and SHPB impact test are conducted on the rock samples after freeze-thaw. Based on the test results, the change regularity of wave velocity degradation, static compression mechanical properties and dynamic compression mechanical properties of filled jointed rocks under the effect of freeze-thaw cycles were analyzed. The results show that the wave velocity, static compressive strength and dynamic compressive strength of the filled jointed rocks all show a downtrend with the increase of the number of freeze-thaw cycles, and each parameter is positively correlated with the strength of the filling materials. Among them, the decrease in the wave velocity of the rock sample after 30 freeze-thaw cycles is greater than 30%, and the strength loss of the static peak compressive strength exceeds half of its initial strength. The static peak strain rises exponentially with the increase of the number of freeze-thaw cycles while the dynamic peak strain does not show a clear trend. The dynamic peak strain is about 1/10 to 1/5 of the static peak strain. Under the same freeze-thaw action, the lower the strength of filling material, the more serious the damage

    Unconventional inorganic characteristics of 4 types of Xinjiang coals and their influence on the generation of ultrafine particles

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    A deep understanding of the effects of the inorganic characteristics of Xinjiang coals on combustion particulate generation is of great significance for their clean and efficient utilization. This work investigated the inorganic characteristics of Wucaiwan coal (WCW), Wanxiang coal (WX), Tianchi coal (TC), and Xiheishan coal (XHS) and the their relationship with the production of ultrafine particulates during combustion. The results show that the four Xinjiang coals are mainly lignites with low ash and sulfur contents. Coal ashes are enriched in basic elements. Among them, the content of Na2O (3.58%−7.13%) is commonly higher than that of conventional utility coals. The ashes of WCW and WX coals have higher contents of CaO (> 33%), but low contents of SiO2 and Al2O3. WX coal is particularly characterized by high Na and Cl. The Na in coal is primarily water soluble(62.3%−90.6%). The K is mainly HCl insoluble. The Fe occurs primarily as HCl soluble and insoluble forms. And the distribution of Ca and Mg in different forms varies according to coal types. The composition of ultrafine particulate matter from Xinjiang coal combustion is dominated by Na, K, Cl, and S. The particle size range of the ultrafine particulate matter is accurately defined by using the condition that the mass fraction of Na2O+K2O+Cl+SO3 is higher than 50%. The ultrafine particulate matter of WCW, TC and XHS coals has similar particle size ranges (≤0.07 μm); while the ultrafine particulate matter of WX coal, which has the highest content of Na in the water-soluble form, has a wider particle size range (≤0.76 μm). The generation of ultrafine particulate matter (y) is found to be highly linearly and positively correlated with the total amount of water-soluble (Na+K) (x) in the coal, with the relationship equation y = 0.528x−0.239 and the correlation coefficient of 0.948

    A method for estimating yield of maize inbred lines by assimilating WOFOST model with Sentinel-2 satellite data

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    Maize is the most widely planted food crop in China, and maize inbred lines, as the basis of maize genetic breeding and seed breeding, have a significant impact on China’s seed security and food safety. Satellite remote sensing technology has been widely used for growth monitoring and yield estimation of various crops, but it is still doubtful whether the existing remote sensing monitoring means can distinguish the growth difference between maize inbred lines and hybrids and accurately estimate the yield of maize inbred lines. This paper explores a method for estimating the yield of maize inbred lines based on the assimilation of crop models and remote sensing data, initially solves the problem. At first, this paper analyzed the WOFOST(World Food Studies)model parameter sensitivity and used the MCMC(Markov Chain Monte Carlo) method to calibrate the sensitive parameters to obtain the parameter set of maize inbred lines differing from common hybrid maize; then the vegetation indices were selected to establish an empirical model with the measured LAI(Leaf Area Index) at three key development stages to obtain the remotely sensed estimated LAI; finally, the yield of maize inbred lines in the study area was estimated and mapped pixel by pixel using the EnKF(Ensemble Kalman Filter) data assimilation algorithm. Also, this paper compares a method of assimilation by setting a single parameter. Instead of the WOFOST parameter optimization process, a parameter representing the growth weakness of the inbred lines was set in WOFOST to distinguish the inbred lines from the hybrids. The results showed that the yield estimated by the two methods compared with the field measured yield data had R2: 0.56 and 0.18, and RMSE: 684.90 Kg/Ha and 949.95 Kg/Ha, respectively, which proved that the crop growth model of maize inbred lines established in this study combined with the data assimilation method could initially achieve the growth monitoring and yield estimation of maize inbred lines
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