Necessity of Teaching Culture in Foreign Language Classroom

This paper expounds on the importance of teaching cultural things in foreign language classroom. Some commonly seen ＂cultural mistakes＂ are probed in detail to reveal that cultural awareness plays a crucial role in cross-cultural communication and teaching culture can greatly boost students＇ interest in learning a foreign language.

Preparation and Electrochemical Performance of Si@void@NC Composite with a Tunable Nitrogen Doping Content in the Carbon Layer

A strategy for the preparation nitrogen-doped carbon encapsulated Si nanocomposite with a void layer(Si@void@NC)is proposed,in which the nitrogen doping content in the carbon layer is tunable.Aniline and ortho-phenylenediamine are both selected as the nitrogen,carbon sources and co-polymerized on Si@SiO_(2),in which SiO_(2)is functionalized as a void template.SEM and TEM observation show that Si nanoparticles are encapsulated in a hollow and interconnected carbon cages with a thickness of less than 10 nm,which is inclined to agglomerate together to form larger particles in micrometer scale.The variation of mole ratio of aniline and ortho-phenylenediamine will enable the change of nitrogen doping level in the carbon layer and ranges from 3.2%to 8.4%.The nitrogen is doped into the carbon framework in the form of pyridinic,pyrrolic and graphitic nitrogen.Electrochemical tests indicate that the nitrogen content influences the SEI formation and the lithiation of Si nanoparticles.The potential for the decomposition of electrolyte to form SEI film and the alloying of Si-Li negatively shift when the nitrogen doping content is increased.Furthermore,the cycling performance of Si@void@NC is improved when raising the nitrogen content in the carbon.And the optimal nitrogen content is 7.5%,which is corresponding to the mole ratio of aniline to ortho-phenylenediamine is 5:5.

Piezoelectric sensing method for segmental joint contact stress during shield tunnel construction

The emergence of curved shield tunnels poses a significant construction challenge.If the quality of the segment assembly is not guaranteed,many segment cracks and damage will result from the stress concentration.Sensing the contact stresses between segmental joints is necessary to improve the quality of segments assembled for shield tunnel construction.Polyvinylidene difluoride(PVDF)piezoelectric material was chosen for the sensor because it can convert contact stresses into electrical signals,allowing the state of the segmental joints to be effectively sensed.It matches the working environment between the segmental joints of the shield tunnel,where flexible structures such as rubber gaskets and force transfer pads are present.This study proposes a piezoelectric sensing method for segmental joints in shield tunnels and conducts laboratory tests,numerical analyses,and field tests to validate the feasibility of the method.The results indicate that the PVDF film sensor can effectively sense the entire compression process of the gasket with different amounts of compression.The piezoelectric cable sensor can effectively sense the joint offset direction of the gasket.For differently shaped sections,the variation in the force sensed by the piezoelectric cable sensors was different,as verified by numerical simulation.Through the field test,it was found that the average contact stress between the segmental joints was in the range of 1.2–1.8 MPa during construction of the curved shield tunnels.The location of the segmental joints and the type of segment affect the contact stress value.The field monitoring results show that piezoelectric sensing technology can be successfully applied during assembly of the segments for effective sensing of the contact stress.

Multi-fluid Eulerian simulation of mixing of binary particles in a gas-solid fluidized bed with a cohesive particle-particle drag model

A particle-particle(p-p)drag model is extended to cohesive particle flow by introducing solid surface energy to characterize cohesive collision energy loss.The effects of the proportion of cohesive particles on the mixing of binary particles were numerically investigated with the use of a Eulerian multiphase flow model incorporating the p-p drag model.The bed expansion,mixing,and segregation of Geldart-A and C particles were simulated with varying superficial velocities and Geldart-C particle proportions,from which we found that the p-p drag model can reasonably predict bed expansion of binary particles.Two segregation types of jetsam-mixture-flotsam and mixture-flotsam processes were observed during the fluidization processes for the Geldart-A and C binary particle system.The mixing processes of the binary particle system can be divided into three scales:macro-scale mixing,meso-scale mixing,and micro-scale mixing.At a constant superficial velocity the optimal mixing was observed for a certain cohesive particle proportion.