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Aluminum–copper composite is an attractive candidate for electronic industry and power industry because of excellent electrical and thermal conductivity. In this work, the explosive welding techniq...

The joining of amorphous alloys and common metals has been hot subjects of abundant studies in recent years. Nevertheless, the crystallization and fracture of amorphous alloy are still big challeng...

Coalbed methane embedded in coal seams, is an unconventional energy resource as well as a hazardous gas existing in mining industries, which attracts lots of global attention. As the largest coal producer, the mining industry in China had to deal with many hazards induced by methane for decades. To solve this issue, underground methane extraction is commonly used in underground coal mines. However, underground methane extraction is hampered by low production rate and low efficiency because of slow gas emission from coal primarily controlled by gas desorption and permeability. It is well known that temperature has a great impact on gas sorption. The higher the temperature the larger the desorption rate. As the depth of coal mines increases beyond 1000m coal mines suffer elevated air temperatures caused by the natural geothermal gradient. The elevated temperature in such mines provides a potential economical way for geothermal energy extraction and utilization in deep coal mines which can largely cut the expenses of installation and operation maintenance. Therefore, a novel method is proposed to enhance underground methane extraction by deep heat stimulation. This paper mainly presents an assessment of previous and ongoing research in the related field and provides a first feasibility analysis of this method applied in the underground environment. The technique proposed in this early appraisal is deemed significant for coalbed methane drainage enhancing the productivity of deep coal mines by geothermal technology and can also be extended for many applications in relevant areas such as shale gas, and tight oil.

In order to study the impact of the geological structure on pulsating hydraulic fracturing (PHF), the industrial experiments of PHF were carried out in the tectonic zone and the non-tectonic zone, and then, the differences of PHF process and effect were analyzed. The results show that the fault structure brings out a weak surface in the area of PHF, easily inducing the seam crack extension to the fault, and pulsating water constantly moves to the direction of fault. Pulsating injection time and injection quantity of PHF in the tectonic zone are significantly larger than that in the non-tectonic zone, producing large water blocking effect to gas drainage and hindering gas migration dynamics. There is a natural relief area existing in the fault so that the pulsating pressure of PHF cannot be increased, reducing the effect of PHF. Geological structure reduces the increment of the stable gas concentration and improves the initial gas concentration before and after PHF.

Through analyzing the characteristics of the data processing in the environment of big data, the author puts forward the distributed optimization storage and statistical system model based on hash distribution. Based on massive amounts of data distribution, this model completed the data backup protocol based on master copy of distributed design and the Paxos distributed system protocol design on the basis of the principle of consistency distribution of hash algorithm and fully considering load balancing. The author makes simulation of the process of data storage through OPNET Modeler simulation software, and then complete performance evaluation of the designed storage model. The simulation results show that the big data distributed storage system model design based on hash distribution this paper proposed compared with sequential storage distribution policy increases by 12.2% in terms of throughput, and the response latency decreases by 9.8%. In addition, the random writing speed is about 8Mb/s. In general, the model of distributed storage this paper designed based on hash distribution has feasibility.

The geological condition of Chinese coal mines are complex and high gassy, which account for fifty percent to seventy percent. Because of the abundant pores and cracks around the drainage drilling hole, the gas concentration attenuates rapidly, and the effective gas drainage period is short. The traditional sealing materials of yellow mud and cement-sand grout will readily shrink after the drilling hole is sealed, the sealing length is short and the sealing quality is not satisfactory. Currently widely used polyurethane material will shrink when it comes into contact with water, and the price is also very high. In this study, taking cement as a base material, a novel composite sealing material mixed by expansion admixture, additive, and fibrin and coupling agent was developed and the sealing performance and expansion property of the material were also studied and analyzed. The FEI Quanta TM 250 environmental scanning electron microscope was used to investigate the microstructure of material. The results revealed that the new composite sealing material had a desirable expansion performance and a definite fluidity convenient for grouting. The solidified material, combining closely with the drilling wall, possessed an adequate strength and was not easy to shrink. Compared to the conventional polyurethane, the gas drainage concentration by drilling sealing exceeded 40 percent, and the sealing capacity improves 5 times, the sealing effect increases significantly. Keywords: Drilling sealing material, Microcosmic structure, Gas drainage, Sealing performance

In recent times, with the development of protection stratum, it is more and more important to investigate its effects. In this paper, in view of this situation, similar simulation experiment and site test are used to investigate the real-time effects at a certain mine of Pingdingshan Coal Group Company. The results of similar simulation experiment and site test show the stress and displacement variation of overlying rock and protected seam; define the max relative deformation and Roof Falling Interval; and determine the Protected Zone and Pressure Relief Angle. So, the result of research has great significance in directing the production of the mine and in developing the technology of protection stratum mining.

Based on the experiment, the important influence of the pipe with abnormal structure on gas explosion propagation characteristics is analyzed. The results show that gas explosion propagation at the turning point is a process of interaction of pressure wave, flame and complicated flow field. The overpressure of pressure wave and flame transmission velocity are rapidly accelerated and the pipe wall at the turning point is seriously destroyed. The angle of bend has a great influence on the gas explosion propagation characteristics, i.e. there is a different degree of change in both flame velocity and pressure wave overpressure value when gas explosion propagates through bend with different angles. The bend not only increases the turbulent flow of combustion area that accelerates the reaction and velocity, but also enlarges the resistance and heat transmission to the pipe wall. At the same time, the expansion wave at the turning point restrains the gas explosion propagation. The influence of bend on gas explosion propagation characteristics is determined by the combined impact of inhibitor factors and motivation factor. Experiment research and theory analysis indicate that gas explosion propagation characteristics in bend pipe are obviously different from that in straight pipe. So in the mine exploitation, the bend roadways should be decreased as few as possible, and preventive measures should be taken in order to diminish the loss caused by gas explosion. The research results will play an important role in the guidance of preventing gas explosion from occurring and alleviating the damage in coal mine.

In this study, the relationship between fluorine in drinking water and that in urine of urban residents in China is assessed. Fluorine concentrations in tap water and those in urine show a good correlation with a linear regression coefficient of 0.9798, indicating that the fluorine concentrations in big cities under investigation are extremely low, and the main source of fluorine is tap water. The weather effect on the intake amount of fluorine is also discussed. When air temperature is above 15℃, people would intake more fluorine through drinking water with the rise of air temperature. When temperature is below 15℃, no remarkable relationship is observed between air temperature and the intake amount of fluorine. This phenomenon indicates that the main source of fluorine in China is tap water instead of foodstuff.

Minimally invasive esophagectomy is now accepted as a regular treatment modality for esophageal cancer. Upper gastrointestinal (GI) bleeding is a common postoperative adverse event of esophagectomy. However, there are very few reports in the literature on endoscopic management of early upper GI bleeding after an esophagectomy. Here, we report the successful management of such an early case of GI bleeding after thoracolaparoscopic esophagectomy by the use of endoscopic intrathoracic anastomosis.

The administration of sodium 2,3-dimercapto-1-propane sulfonate (DMPS) to humans chronically exposed to inorganic arsenic in their drinking water resulted in the increased urinary excretion of arsenic, the appearance and identification of monomethylarsonous acid (MMA III ) in their urine, and a large decrease in the concentration and percentage of urinary dimethylarsinic acid (DMA). This is the first time that MMA III has been detected in the urine. In vitro biochemical experiments were then designed and performed to understand the urinary appearance of MMA III and decrease of DMA. The DMPS–MMA III complex was not active as a substrate for the MMA III methyltransferase. The experimental results support the hypothesis that DMPS competes with endogenous ligands for MMA III , forming a DMPS–MMA complex that is readily excreted in the urine and points out the need for studying the biochemical toxicology of MMA III . It should be emphasized that MMA III was excreted in the urine only after DMPS administration. The results of these studies raise many questions about the potential central role of MMA III in the toxicity of inorganic arsenic and to the potential involvement of MMA III in the little-understood etiology of hyperkeratosis, hyperpigmentation, and cancer that can result from chronic inorganic arsenic exposure.

This article sets out from the angle of systemic risk assessment, identification and control. Based on the deep research on coupling warning technology of multi-source information in weighty disasters, combined index system of weighty gas disasters in coal mines has been established, and the method of abnormal risk positioning of time and space combined with control chart and histogram has been put forward. Based on the coal mine safety risk, the article establishes risk management models of technology guarantee mechanism, organization guarantee mechanism, education training mechanism, safety culture mechanism. Comprehensive warning system of multi-source have been developed about great coal mine gas disasters, and the system integrates 6 kinds of security risk analysis and assessment methods as well as 5 kinds of prediction methods in regional or working face coal and gas outburst risk. Industrial application shows that the risk assessment system can improve the systematization and accuracy of weighty gas disasters in coal mine, and has an important significance in gas disasters prevention and control.

Through a roadway model whose cross-section area is 80×80 mm2 and length is 100m, the attenuation characteristics of explosive shock wave of methane-air mixtures with concentration of 9.5% and filling ratio of 10% were simulated by using AutoReaGas software at the initial pressure of 20 KPa, 60 KPa, 101.3 KPa, 150 KPa and 200 KPa. The results show that when shock wave propagates in roadway, the distances where peak overpressure and maximum gas velocity attenuate to zero are the same as those of maximum temperature and maximum density reduce nearly to their corresponding initial values. With the increase of initial pressure, the safety distance presents the change law of decrease, increase and decrease, the peak overpressure, the maximum density, the maximum combustion rate gradually increase, and their laws can be approximated by means of some linear functions, however, the changes of maximum temperature and maximum gas velocity are not obvious.

The existence of maximal and minimal fixed points for various set-valued operators is discussed. This paper presents some new fixed point theorems in ordered Banach spaces. A necessary and sufficient condition for the existence of the fixed point to a class of multivalued maps has been obtained. The uniqueness of the positive fixed point has been discussed. The results extend and improve the corresponding results. As an application, we utilize the results to study the existence and uniqueness of positive fixed points for a class of convex operators. In the end, we give a simple application to certain integral equations.