Meshing temperature analyses of polymer gears reported in the literature mainly concern the effects of various material combinations and loading conditions,as their impacts could be seen in the first few meshing cycle...Meshing temperature analyses of polymer gears reported in the literature mainly concern the effects of various material combinations and loading conditions,as their impacts could be seen in the first few meshing cycles.However,the effects of tooth geometry parameters could manifest as the meshing cycles increase.This study investigated the effects of tooth geometry parameters on the multi-cycle meshing temperature of polyoxymethylene(POM)worm gears,aiming to control the meshing temperature elevation by tuning the tooth geometry.Firstly,a finite element(FE)model capable of separately calculating the heat generation and simulating the heat propagation was established.Moreover,an adaptive iteration algorithm was proposed within the FE framework to capture the influence of the heat generation variation from cycle to cycle.This algorithm proved to be feasible and highly efficient compared with experimental results from the literature and simulated results via the full-iteration algorithm.Multi-cycle meshing temperature analyses were conducted on a series of POM worm gears with different tooth geometry parameters.The results reveal that,within the range of 14.5°to 25°,a pressure angle of 25°is favorable for reducing the peak surface temperature and overall body temperature of POM worm gears,which influence flank wear and load-carrying capability,respectively.However,addendum modification should be weighed because it helps with load bearing but increases the risk of severe flank wear.This paper proposes an efficient iteration algorithm for multi-cycle meshing temperature analysis of polymer gears and proves the feasibility of controlling the meshing temperature elevation during multiple cycles by tuning tooth geometry.展开更多
The synthesis of Ta-substituted polyoxometalates has always been an attractive but challenging goal.Three novel tantalum-containing 12-tungsto-2-phosphates were successfully prepared using the water bath method.The mo...The synthesis of Ta-substituted polyoxometalates has always been an attractive but challenging goal.Three novel tantalum-containing 12-tungsto-2-phosphates were successfully prepared using the water bath method.The monomer,K_(11)Li[P_(2)W_(12)(TaO_(2))_(6)O_(56)]·19H_(2)O(1),is composed of{P_(2)W_(12)}and 6{Ta(O_(2))}building blocks,similar to[P_(2)W_(12)(NbO_(2))_(6)O_(56)]^(12-).Monomer 1 polymerized to form two cis-trans dimers,K1_(3)Li_(6)H-cis-[P_(2)W_(12)Ta_(4)(TaO_(2))_(2)O_(59)]_(2)·61H_(2)O(2)and KNa_(3)Li_(4)H_(12)-trans-[P_(2)W_(12)Ta_(4)(TaO_(2))_(2)O_(59)]_(2)·37H_(2)O(3).Compounds 1-3 can serve as a structural motif to manufacture additional fascinating molecular clusters,promoting the advancement of POM chemistry.In contrast to[P_(2)W_(12)(NbO_(2))_(6)O_(56)]^(12-),compound 1 exhibits exceptional stability,evidenced by ESI-MS,IR,and NMR spectroscopy.In addition,2 and 3 exhibit high proton conductivity and superior water adsorption properties.展开更多
Based on two long-term fertilization(1985-) and tillage(1990-) experiment, the effect of fertilization and tillage on soil particulate organic matter carbon(POM-C) and total organic carbon(TOC) were studied. The resul...Based on two long-term fertilization(1985-) and tillage(1990-) experiment, the effect of fertilization and tillage on soil particulate organic matter carbon(POM-C) and total organic carbon(TOC) were studied. The results indicated that under the conventional tillage condition, the largest POM-C and TOC content in 0～20cm soil layer was found in the treatment of N and P fertilizers + recycled nutrients among six fertilization simulated models. As blent residue into the whole 0～20cm topsoil, POM-C content of the deep ploughing treatment was higher than other treatments. The order was:association,prevalent and rotary tillage.展开更多
基金Supported by National Key R&D Program of China(Grant No.2019YFE0121300)。
文摘Meshing temperature analyses of polymer gears reported in the literature mainly concern the effects of various material combinations and loading conditions,as their impacts could be seen in the first few meshing cycles.However,the effects of tooth geometry parameters could manifest as the meshing cycles increase.This study investigated the effects of tooth geometry parameters on the multi-cycle meshing temperature of polyoxymethylene(POM)worm gears,aiming to control the meshing temperature elevation by tuning the tooth geometry.Firstly,a finite element(FE)model capable of separately calculating the heat generation and simulating the heat propagation was established.Moreover,an adaptive iteration algorithm was proposed within the FE framework to capture the influence of the heat generation variation from cycle to cycle.This algorithm proved to be feasible and highly efficient compared with experimental results from the literature and simulated results via the full-iteration algorithm.Multi-cycle meshing temperature analyses were conducted on a series of POM worm gears with different tooth geometry parameters.The results reveal that,within the range of 14.5°to 25°,a pressure angle of 25°is favorable for reducing the peak surface temperature and overall body temperature of POM worm gears,which influence flank wear and load-carrying capability,respectively.However,addendum modification should be weighed because it helps with load bearing but increases the risk of severe flank wear.This paper proposes an efficient iteration algorithm for multi-cycle meshing temperature analysis of polymer gears and proves the feasibility of controlling the meshing temperature elevation during multiple cycles by tuning tooth geometry.
基金supported by the National Natural Science Foundation of China(Nos.22071044,21771054 and 22171071)。
文摘The synthesis of Ta-substituted polyoxometalates has always been an attractive but challenging goal.Three novel tantalum-containing 12-tungsto-2-phosphates were successfully prepared using the water bath method.The monomer,K_(11)Li[P_(2)W_(12)(TaO_(2))_(6)O_(56)]·19H_(2)O(1),is composed of{P_(2)W_(12)}and 6{Ta(O_(2))}building blocks,similar to[P_(2)W_(12)(NbO_(2))_(6)O_(56)]^(12-).Monomer 1 polymerized to form two cis-trans dimers,K1_(3)Li_(6)H-cis-[P_(2)W_(12)Ta_(4)(TaO_(2))_(2)O_(59)]_(2)·61H_(2)O(2)and KNa_(3)Li_(4)H_(12)-trans-[P_(2)W_(12)Ta_(4)(TaO_(2))_(2)O_(59)]_(2)·37H_(2)O(3).Compounds 1-3 can serve as a structural motif to manufacture additional fascinating molecular clusters,promoting the advancement of POM chemistry.In contrast to[P_(2)W_(12)(NbO_(2))_(6)O_(56)]^(12-),compound 1 exhibits exceptional stability,evidenced by ESI-MS,IR,and NMR spectroscopy.In addition,2 and 3 exhibit high proton conductivity and superior water adsorption properties.
文摘Based on two long-term fertilization(1985-) and tillage(1990-) experiment, the effect of fertilization and tillage on soil particulate organic matter carbon(POM-C) and total organic carbon(TOC) were studied. The results indicated that under the conventional tillage condition, the largest POM-C and TOC content in 0～20cm soil layer was found in the treatment of N and P fertilizers + recycled nutrients among six fertilization simulated models. As blent residue into the whole 0～20cm topsoil, POM-C content of the deep ploughing treatment was higher than other treatments. The order was:association,prevalent and rotary tillage.
