Waterborne polyurethane(WBPU)with controlled biodegradability and biocompatibility was synthesized by using poly(ε-caprolactone)(PCL)as the polyglycol,isophorone diisocyanate(IPDI)as the isocyanate,2,2-bishydroxymethylbutyric acid(DMPA)as the chain extender and 1,4-butanediol(BDO)as the hard-segment regulating agent.We found that BDO content significantlyinfluencedmechanicalproperties,degradable performances and cyto-biocompatibility of PCL-WBPUs.Increasing the BDO content in PCL-WBPU enhanced its tensile strength and decreases strain.Enzymolysis and hydrolysis properties were also regulated by BDO content,but with different mechanisms.Cytobiocompatibility was evaluated with ATDC5 cells.The results show that the biodegradability of PCL-WBPU is significantly determined by BDO content,which exerts a serious influence on its polymer structure,leading to resultant degradable properties.
For coupled system of multilayer dynamics of fluids in porous media, the characteristic alternating-direction finite element methods for nourectangular regions applicable to parallel arithmetic are put forward and two-dimensional and three-dimensional schemes are used to form a complete set. Some techniques, such as calculus of variations, isoparametric transformation, patch approximation, operator-splitting, characteristic method, negative norm estimate, energy method, the theory of prior estimates and techniques are used. For the nourectangular regions case, optimal order estimates in L^2 norm are derived for the error in the approximation solution. Thus the well-known theoretical problem has been thoroughly and completely solved. These methods have been successfully used in multilayer oil resources migration-accumulation numerical simulation.
Phase transition process and magnetic entropy change -ΔS of Ni55.2Mn18.6Ga26.2-xGdx(x=0, 0.05, 0.15) alloys were studied. Ni55.2Mn18.6Ga26.2-xGdx(x=0, 0.05, 0.15) alloys still underwent simultaneous structural and magnetic transitions and transform from ferro-magnetic martensitic phase to paramagnetic austenitic phase during heating. Under a field of 2 T, the maximum magnetic entropy change -ΔSM of Ni55.2Mn18.6Ga26.15Gd0.05 alloy was 7.7 J/kg·K at 317 K during heating and 8.6 J/kg·K at 314 K during cooling while it was 11.8 J/kg·K at 317 K in Ni55.2Mn18.6Ga26.05Gd0.15 alloy during heating.
This paper addresses the significance of preprocessing big data collected during a tunnel boring machine(TBM)excavation before it is used for machine learning on various TBM performance predictions.The research work is based on two water diversion tunneling projects that cover 29.52 km and 17051 boring cycles.It has been found that the penetration rate calculated from the raw measured penetration distances exhibits more random behavior owing to their percussive and vibratory behavior of the cutterhead.A moving average method to process the negative instantaneous velocities and a noise reduction filter to deal with signals with abnormal frequencies have been recommended.An index called the drilling efficiency index is introduced to assess the relationships between the mechanical parameters in a boring cycle,whose linear regression coefficient R^(2)is taken for a preliminary investigation of possible problems requiring preprocessing.The research work defines the irrelevant data whose errors are caused by human or mechanical mistakes,and therefore should be cleaned or amended.These irrelevant data can be divided into five categories:(1)premature cycles,(2)sensor defects,(3)mechanical defects,(4)human interruption,and(5)missing files.A program TBM-Processing has been coded for the recognition and classification of these categories.PDF books generated by the program have been uploaded at GitHub to encourage discussions,collaboration,and upgrading of the data processing work with our peers.
In Yingzuijie National Nature Reserve,Pinus massoniana forest,mixed broadleaf-coniferous forest and evergreen broad-leaf forest were investigated to study the changing characteristics of woody debris( WD) during various succession stages of evergreen broad-leaf forest. The results showed that during various succession stages of evergreen broad-leaf forest in Yingzuijie National Nature Reserve,WD storage of each forest ranged from 1. 26 to 8. 82 t /hm2,with the order of P. massoniana forest
