Mechanism Modeling and Simulation Based on Dimensional Deviation

To analyze the effects on motion characteristics of mechanisms of dimensional variations, a study on random dimensional deviation generation techniques for 3D models on the basis of the present mechanical modeling software was carried out, which utilized the redeveloped interfaces provided by the modeling software to develop a random dimensional deviation generation system with certain probability distribution characteristics. This system has been used to perform modeling and simulation of the specific mechanical time delayed mechanism under multiple deviation varieties, simulation results indicate the dynamic characteristics of the mechanism are influenced significantly by the dimensional deviation in the tolerance distribution range, which should be emphasized in the design.

Influences of different diluents on ignition delay of syngas at gas turbine conditions：A numerical study

Ignition delay of syngas is an important factor that affects stable operation of combustor and adding diluents to syngas can reduce NO_x emission.This paper used H_2O,CO_2 and N_2 as diluents and calculated ignition delay of syngas in temperature range of 900-1400 K and at pressures of 10 and 30 atm respectively.In high temperature range,comparing with N_2 dilution,adding H_2O and CO_2 can significantly inhibit autoignition of syngas because they have higher collision efficiencies in reaction H + O_2(+ M) = HO_2(+ M).As for low temperature conditions,adding H_2O can increase reactivity of syngas,especially under high pressure,because of its high collision efficiency in reaction H_2O_2(+ M) = 2OH(+ M).Comparing with different dilution rates shows that for syngas and operating conditions in this paper,adding N_2 mainly influences temperature rising process of syngas combustion,thus inhibiting reactivity of syngas.In addition,this paper calculated ignition delay of syngas at different equivalence ratios(φ= 0.5,1.0).Higher equivalence ratio(φ≤1) means that less air(especially N_2) needs to be heated,thus promoting ignition of syngas,

A novel needle probe for deeper photoacoustic viscoelasticity measurement

We present for the first time,to the best of our knowledge,a needle probe for photoacoustic viscoelasticity(PAVE)measurements at a depth of 1 cm below the sample surface.The probe uses a gradient index rod lens,encased within a side-facing needle(0.7 mm outer diameter),to direct excitation light(532 nm)and detection light(1325 nm)focused on the sample,collecting and directing the returned detection light in a spectral domain low coherence interferometry system,which allows for obtaining optical phase differences due to photoacoustic oscillations.The feasibility of needle probe for PAVE depth characterization was investigated on gelatin phantoms and in vitro biological tissues.The experimental results in an in vivo animal model predict the great potential of this technique for in vivo tumor boundary detection.