Pneumatic resistance network analysis and dimension optimization of high pressure electronic pneumatic pressure reducing valve

The structure and working principle of a self-deigned high pressure electronic pneumatic pressure reducing valve (EPPRV) with slide pilot are introduced.The resistance value formulas and the relationship between the resistance and pressure of three typical pneumatic resistances are obtained.Then,the method of static characteristics analysis only considering pneumatic resistances is proposed,the resistance network from gas supply to load is built up,and the mathematical model is derived from the flow rate formulas and flow conservation equations,with the compressibility of high pressure gas and temperature drop during the expansion considered in the model.Finally,the pilot spool displacement of 1.5 mm at an output pressure of 15MPa and the enlarging operating stroke of the pilot spool are taken as optimization targets,and the optimization is carried out based on genetic algorithm and the model mentioned above.The results show that the static characteristics of the EPPRV are significantly improved.The idea of static characteristics analysis and optimization based on pneumatic resistance network is valuable for the design of pneumatic components or system.

STRATA AND SURFACE SUBSIDENCE CONTROL IN STRIP-PARTIAL MINING UNDER BUILDINGS

This paper systematiedy expounds the history and present situation of tbe research &application of strip-parttal mining at home and abroad. Tbe prospect of using strip-parttal miningmcthod to mine under balldings (structures) at the present situation of market economy is also expounded here Strata & surface subsidence mechanism of atrip-partni mining the optimization ofthe width of unit goaf & coal pillar as well as the calculation method of surface subsidence pridictionbased on Holding-Ptate Control Theory and Coal Pillar Long-term Stability, which are our researchachivements in recent years about strata & surface subsidence control in strip-partial mining, arethe main points introdued bere.

Structural dimension optimization and mechanical response analysis of fabricated honeycomb plastic pavement slab

Because of favorable mechanical properties,deformation resistance and being conducive to environmental protection,honeycomb fabricated plastic pavement slabs are highly recommended these years.At present,most studies focus on the performance of plastic materials,however,the dimension optimization of fabricated plastic pavement slab is rarely mentioned.In this paper,an optimized geometry of the honeycomb pavement slab was determined through finite element analysis.Mechanical response of honeycomb slabs with different internal dimensions and external dimensions were explored.Several dimension factors were taken into consideration including the side length,rib thickness,the thickness of both top and bottom slabs of honeycomb structure and the length,the width and the thickness of the fabricated plastic slab.The results showed that honeycomb pavement slab with 6 cm bottom slab,12 cm top slab,18 cm side length and 6 cm rib thickness is recommended,additionally,an external dimension of 4 m×4 m×0.45 m is suggested.Then,the mechanical responses of this optimized fabricated plastic slab were further investigated.Significance of different influencing factors,including wheel load,elastic modulus of plastic material,base layer thickness,soil foundation modulus and base layer modulus were ranked.

State Prediction of Chaotic System Based on ANN Model

The choice of time delay and embedding dimension is very important to the phase space reconstruction of any chaotic time series. In this paper, we determine optimal time delay by computing autocorrelation function of time series. Optimal embedding dimension is given by means of the relation between embedding dimension and correlation dimension of chaotic time series. Based on the methods above, we choose ANN model to appoximate the given true system. At the same time, a new algorithm is applied to determine the network weights. At the end of this paper, the theory above is demonstrated through the research of time series generated by Logistic map.