Influence of Drilling Fluid Components on Shear Strength at Cement-aquifuge Interface in Coalbed Methane Wells

The hydraulic fracturing is still an effective technology for the exploitation of coalbed methane （CBM）. However, after the hydraulic fracturing operation, the high water cut or sudden water flooding of CBM well usually occurs due to upward migration of bottom water, which is called water channeling （water inrush）. This problem has been severely limiting the hydraulic fracturing effect of CBM wells. Some studies show that the aquifuge and cement paste themselves will not crush under hydraulic fracturing pressure. Water channeling often occurs at cement- aquifuge interface （CAI）.

An Application of the Modified Shear Lag Model to Study the Influence of Thermal Residual Stresses on the Stiffness and Yield Strength of Short Fiber Reinforced Metal Matrix Composites

The modified shear lag model proposed recently was applied to calculate thermal residual stresses and subsequent stress distributions under tensile and compressive loadings. The expressions for the elastic moduli and the yield strengths under tensile and compressive loadings were derived which take account of thermal residual stresses. The asymmetries in the elastic modulus and the yield strength were interpreted using the derived expressions and the obtained results of the stress calculations. The model predictions have exhibited good agreements with the experimental results and also with the other theoretical predictions

Influencing factor of sinter body strength and its effects on iron ore sintering indexes

Sinter body strength, which reflects the strength of sinter, plays an important role in the improvement of sinter. In this study, the sinter body strengths of iron ores were measured using a microsintering method. The relationship between the chemical composition and sinter body strength was discussed. Moreover, sinter-pot tests were performed. The effects of sinter body strength on the sintering indexes were then elucidated, and the bottom limit of sinter body strength of blending ores was confirmed. In the results, the compressive strengths（CSs） of iron ores are observed to decrease with the increasing of the contents of loss on ignition（LOI）, SiO 2, and Al2O3; however, LOI of less than 3wt% does not substantially influence the CSs of fine ores. In the case of similar mineral composition, the porosity, in particular, the ratio between the number of large pores and the total number of pores, strongly influences the sinter body strength. With an increase of the blending-ore CSs used in sinter-pot tests, the yield, productivity, and tumbler strength increase, and the solid fuel consumption decreases. The CSs of the blending ores only slightly affect the sintering time. The CS bottom limit of the blending ores is 310 N. When the CSs of the blending ores increase by 10%, the yield, productivity, and tumbler index increase by 1.9%, 2.8%, and 2.0%, respectively, and the solid fuel consumption decreases by 1.9%.

The effects of water depth on the growth and reproduction of Potamogeton crispus in an in situ experiment

Aims Water level is one of the most important determinants of the distri-bution and composition of submersed aquatic vegetation in shal-low lakes.Without changes in nutrient loading,large-scale declines in submerged macrophytes in shallow lakes are largely attributed to strong external or internal forces,including changes in water level.As a winter-active submerged macrophyte,Potamogeton crispus has important functions in aquatic ecosystem.The objec-tives of our study were to reveal the effects of water depths on the germination,growth,reproduction and morphological changes of P.crispus under natural environmental conditions;identify the optimum water depth range for colonization of P.crispus;and pre-dict the succession course for P.crispus in Lake Taihu.Methods A long-term in situ experiment was performed to study the effects of water depth on the growth and morphology of P.crispus across the entire life cycle.Plants were grown in the improved cross type of rhizotrons for 30 weeks at three different water depths(60,120 and 200 cm)in Dongtaihu Bay of Lake Taihu.We measured the plant height,root length,the length and width of leaves and counted the numbers of leaves,ramets,turion spikes and roots of each plant on each observation day during the experiment.Important Findings Water depths ranging from 60 to 120 cm were favourable for above-ground vegetation growth,root tissue growth and the reproductive ability of P.crispus.At water depth of 200 cm or beyond,the distri-bution of P.crispus will be limited in the following year because of the lack of turion formation and the severe inhibition of ramet pro-duction.The relationship between above-ground biomass and growth time at three different water depths fits a logistic growth curve well(P<0.001).The rapid growth and distribution with high density of P.crispus at water depth near 60 cm during the reproductive stage is not favourable for growth of other submerged species.So a continuous water depth of~60-120 cm is the optimum growth depth range for the conservation and restoration of P.crispus in Lake Taihu.In addi-tion,the morphological parameters values acquired can replace or provide the ranges for the value of GmaxSB(the maximum growth rate of submerged plants,in the unit of d^(−1))obtained via calibration in the control equations of submerged plant growth in the Eco-Taihu model,which is a three-dimensional ecological model of Lake Taihu.

Analysis of the influencing factors of PAEs volatilization from typical plastic products

The primary emphasis of this research was to investigate the foundations of phthalate（PAEs） pollutant source researches and then firstly confirmed the concept of the coefficient of volatile strength, namely phthalate total content in per unit mass and unit surface area of pollutant sources. Through surveying and evaluating the coefficient of volatile strength of PAEs from typical plastic products, this research carried out reasonable classification of PAEs pollutant sources into three categories and then investigated the relationship amongst the coefficient of volatile strength as well as other environmental factors and the concentration level of total PAEs in indoor air measured in environment chambers.Research obtained phthalate concentration results under different temperature, humidity,the coefficient of volatile strength and the closed time through the chamber experiment. In addition, this study further explored the correlation and ratio of influencing factors that affect the concentration level of total PAEs in environment chambers, including environmental factors, the coefficient of volatile strengths of PAEs and contents of total PAEs in plastic products. The research created an improved database system of phthalate the coefficient of volatile strengths of each type of plastic goods, and tentatively revealed that the volatile patterns of PAEs from different typical plastic goods, finally confirmed that the coefficient of volatile strengths of PAEs is a major factor that affects the indoor air total PAEs concentration, which laid a solid foundation for further establishing the volatile equation of PAEs from plastic products.