Macroscopic and microscopic mechanical behavior and seepage characteristics of coal under hydro-mechanical coupling

Understanding the physical,mechanical behavior,and seepage characteristics of coal under hydro-mechanical coupling holds significant importance for ensuring the stability of surrounding rock formations and preventing gas outbursts.Scanning electron microscopy,uniaxial tests,and triaxial tests were conducted to comprehensively analyze the macroscopic and microscopic physical and mechanical characteristics of coal under different soaking times.Moreover,by restoring the stress path and water injection conditions of the protective layer indoors,we explored the coal mining dynamic behavior and the evolution of permeability.The results show that water causes the micro-surface of coal to peel off and cracks to expand and develop.With the increase of soaking time,the uniaxial and triaxial strengths were gradually decreased with nonlinear trend,and decreased by 63.31%and 30.95%after soaking for 240 h,respectively.Under different water injection pressure conditions,coal permeability undergoes three stages during the mining loading process and ultimately increases to higher values.The peak stress of coal,the deviatoric stress and strain at the permeability surge point all decrease with increasing water injection pressure.The results of this research can help improve the understanding of the coal mechanical properties and seepage evolution law under hydro-mechanical coupling.

机械化保护性耕作技术

针对传统耕作的缺点,阐述了机械化保护性耕作的优点及工艺体系,说明了机械化保护性耕作是耕作方式的一场革命。

电动机的维护方法

一、电动机简易防潮法 作业之后存放的电动机,往往会因存放不当,而使电动机受潮.当重新使用时,出现绝缘性能下降、发热、漏电的故障现象,有的电动机甚至出现短路不能使用的问题.

Rice Yield and Water Use as Affected by Soil Management Practices

A field experiment was conducted at the Shenyang Experimental Station ofEcology, Chinese Academy of Sciences, to study the effects of soil management practices on water useand rice (Oryza sativa L.) yield in an aquic brown soil during 2001 and 2002. A completely randomexperimental design with three replications was employed, having four soil management practices astreatments, namely: an undisturbed plow layer (CK), a thin plastic film (TN), a thick plastic film(TI) and subsoil compacting (CP). Results indicated no significant differences among all treatmentsfor rice biomass and grain yields. Also, water consumption was about the same for treatments TN andCK, however the treatments TI and CP were much lower with more than 45% and 40% of the irrigationwater in the treatments TI and CP, respectively, saved each year compared to CK. Therefore, wateruse efficiency was higher in the treatments TI and CP. These results will provide a scientific basisfor the water-saving rice cultivation.

Condensation of Water Vapor on Waterproof Breathable Fabrics

Condensation occurs when the local vapor pressure rises above the saturation vapor pressure at the local temperature in theory. A new measuring apparatus were made to obtain temperature and relative humidity simultaneously for the purpose of investigating the mechanism of condensation occurred on the fabrics. The experiment conducted at the standard condition of temperature of 20℃ and relative humidity of 65%. The result obtained from experiment showed that condensation could occur under the situation closed to saturation line as the temperature on fabric may be lower than dew point of water vapor in the measuring box depending on the experiment conducted at an ambient environment temperature of 20℃ The range of fabrics studied showed that PTFE laminated fabrics except nylon gingham PTFE laminated fabric facilitates the loss of water vapor and therefore prevent condensation. It is necessary to develop studies from a wide range of fabrics, especially breathable fabrics and under bad experiment condition in order to develop fabrics, which could eliminate condensation, or transport water vapor through the fabric while remaining waterproof.

Studies on Effect of Syrup Concentration and Drying Modes on Quality of Kesar Mango Slices

An attempt was made to preserve mango slices by treating with 2% calcium chloride solution followed by dipping into sugar syrup of different concentrations i.e. 50°, 60° and 70 °Brix respectively. The treated slices were subjected for drying in different modes of drying （oven, microwave oven and cabinet tray drying） and analyzed for various physico-chemical and organoleptic quality characteristics. The study revealed that the osmo-air dried slices of mango produced with partial dehydration facilitated by osmotic agent （sugar syrup of 60 °Brix. A fruit： sugar syrup ratio of 1：4 （w/v） for 18 h at 40 ℃ temperature） followed by mechanical drying showed superiority in sensorial quality attributes over other concentrations of ingredients and the rest of the modes of drying. The good quality osmotically dehydrated mango slices could be preserved with maximum retentions of vitamins with better dehydration, rehydration and sensorial quality characteristics.

Effect of seawater immersion on plasma osmotic pressure and electrolyte balance following open chest trauma

Objective: To explore the effect of seawater immersion on serum osmotic pressure and electrolytes balance following chest trauma in dogs. Methods: Twenty five healthy adult dogs were used in the experiment. A canine model of right open pneumothorax was established by chest puncturing on all animals. Animals were divided into three groups: a control group (n=10) with chest trauma without any immersion; a seawater group (n=10) immersed in seawater after chest trauma and a normal saline group (n=5) immersed in normal saline solution following chest trauma. Blood samples were taken at different time intervals to determine plasma osmotic pressure and electrolytes. The hemodynamic changes were also recorded. Results: Mortality in the seawater group was much higher than that of the control group and the normal saline group. The mean survival time in the seawater group lasted only 45 minutes, while in the control group and the normal saline group the average survival time was more than 4 hours (P< 0.01 ). One of the most important causes of death was hypernatremia and high osmolality. Severe electrolytes imbalance was observed in seawater group. Hypernatremia and high osmolality were the most significant factors of high mortality in the seawater group. Conclusions: Seawater immersion after chest trauma appears to be associated with severe electrolyte imbalance as well as high osmotic pressure. These may be the risk factors leading to fatal outcome.