Stability of mine ventilation system based on multiple regression analysis

In order to overcome the disadvantages of diagonal connection structures that are complex and for which it is difficult to derive the discriminant of the airflow directions of airways, we have applied a multiple regression method to analyze the effect, of changing the rules of mine airflows, on the stability of a mine ventilation system. The amount of air （ Qj ） is determined for the major airway and an optimum regression equation was derived for Qi as a function of the independent variable （ Ri ）, i.e., the venti- lation resistance between different airways. Therefore, corresponding countermeasures are proposed according to the changes in airflows. The calculated results agree very well with our practical situation, indicating that multiple regression analysis is simple, quick and practical and is therefore an effective method to analyze the stability of mine ventilation systems.

Key Technologies for Design of Changqing Yellow River Super-long Bridge of Zhengzhou Ji'nan HSR

Changqing Yellow River Super-long Bridge of Zhengzhou-Ji'nan HSR is a partial cable-stayed bridge with concrete main girder and a unit length of 1,080 m.Studies are carried out on the key technologies of bridge design,and the main conclusions are as follows:The whole unit adopts the supporting system of tower pier consolidation and tower-beam separation,and each pier is provided with seismic mitigation and isolation bearing;shaped-steel reinforced concrete bridge tower is adopted to bring into full play the tensile performance of steel and the compressive performance of concrete,and avoid the construction challenges of setting up multi-layer and multi-stirrup reinforcement while improving the bearing capacity of section;a new type of double-side and bi-directional anti-skid anchorage device is adopted for the cable saddle of wire divider pipe in order to withstand the unbalanced cable force,and verify the reliability of the anti-skid anchorage device by solid model test;and large-segment cantilever pouring design is adopted for the main girder with a maximum segment length of 8 m to effectively shorten the construction period of the bridge.

An Optimization of HTTP/2 for Mobile Applications

In recent years, Hyper Text Transfer Protocol （HTTP） spreads quickly and steadily in the usage of mobile applications as a common web protocol, so that the mobile applications can also benefit from HTTP/2, which is the new version of HTTP based on SPDY developed by Google to speed up the Internet transmission speed. HTTP/2 enables a more efficient use of network resources and a reduced perception of latency by in- troducing header field compression and allowing multiple concurrent exchanges on the same connection. However, what H3TP/2 focuses on is visiting websites through a browser, and mobile applications are not considered much. In this paper, firstly, mobile applications are classified based on the da- ta flow characteristics. Based on the classification, we propose an optimization of HTTP/2 for mobile applications, called HTTP/2-Advance, which uses multiple Transmission Control Protocol （TCP） connections to multiplex HTYP requests and responses. Then we build a tiny system which simulates actu- al requests and responses between mobile applications and servers. We figure out the best choice of the number of multiple TCP connections for mobile applications, and compare the performance of HTTP, HTTP/2 and HTrP/2-Advance in both simulated and in-situ experiments in our system.

Tailoring sintering-resistant thermal barrier coatings by considering critical healing width of two-dimensional interlamellar pores

Large degradation in thermal insulation and strain tolerance is a main headache and a primary cause of the failure for plasma-sprayed thermal barrier coatings(TBCs)during service.One mechanism behind such degradation is the healing of interlamellar pores formed by multiple connections between edges of a pore,which significantly speeds up healing during thermal exposure.The objective of this study is to obtain sintering-resistant TBCs by tailoring the width of interlamellar pores to avoid multiple connections.Firstly,the mechanism responsible for the multiple connections was revealed.The splat surfaces before and after thermal treatments were characterized via an atomic force microscope(AFM).The roughening of the pore surface occurs during thermal exposure,along with the grain growth inside the splats.Consequently,the local surface height increases,which causes multiple connections and healing of the interlamellar pores.Secondly,critical widths of the interlamellar pores for avoiding the multiple connections during thermal exposure are established by correlating the extent of surface roughening with the growth of individual grains.The height increase of the splat surface and the growth of the grain size(D)were found to increase with the exposure temperature and duration.A relationship linking the height increase and the growth of the grain size induced by thermal exposure in plasma-sprayed ceramic splats was obtained.Finally,composite TBCs were prepared to form wide interlamellar pores in the coatings.Using this design,the increases in the thermal conductivity(λ)and the elastic modulus(E)can be prevented to a large extent.Thus,sintering-resistant TBCs that maintain high thermal insulation and strain tolerance,even afer long thermal exposure,can be created.