Using the ab initio plane-wave ultrasoft pseudopotential method based on generalized gradient approximation（GGA）,we investigated the band-gap tuning in monolayer phosphorene（MLP） and bilayer phosphorene（BLP） by ...Using the ab initio plane-wave ultrasoft pseudopotential method based on generalized gradient approximation（GGA）,we investigated the band-gap tuning in monolayer phosphorene（MLP） and bilayer phosphorene（BLP） by external electric fields applied perpendicular to the layers.The band continuously decreases with increasing applied electric fields,eventually rendering them metallic.For MLP,the phenomenon is explained in the light of the giant Stark effect,which is essentially characterized by the interlayer spacing,for the rate of change of bandgap with applied external field.The atomic distance and charges also contribute to the semiconductor-metal transition.The BLP is more sensitive to electric fields than MLP,since their charges are rearranged among bilayers and the bandgap can dramatically drop in terms of electronic field.The results show the bandgap will change for the fabrication of novel electronic and photonic devices.展开更多
Vibration energy harvesting is widely recognized as the useful technology for saving energy. The piezoelectric energy harvesting device is one of energy harvester and is used to operate certain types of MEMS devices. ...Vibration energy harvesting is widely recognized as the useful technology for saving energy. The piezoelectric energy harvesting device is one of energy harvester and is used to operate certain types of MEMS devices. Various factors influence the energy regeneration efficiency of the lead zirconate titanate piezoelectric (PZT) devices in converting the mechanical vibration energy to the electrical energy. This paper presents the analytical and experimental evaluation of energy regeneration efficiency of PZT devices through impedance matching method and drop-weight experiments to different shape of PZT devices. The results show that the impedance matching method has increased the energy regeneration efficiency while triangular shape of PZT device produce a stable efficiency in the energy regeneration. Besides that, it becomes clear that the power, energy and subsequently efficiency of the triangular plate are higher than those of the rectangular plate under the condition of the matching impedance and the same PZT area.展开更多
The concept of linear tangle was introduced as an obstruction to mixed searching number. The concept of (maximal) single ideal has been introduced as an obstruction to linear-width. Moreover, it was already known that...The concept of linear tangle was introduced as an obstruction to mixed searching number. The concept of (maximal) single ideal has been introduced as an obstruction to linear-width. Moreover, it was already known that mixed search number is equivalent to linear-width. Hence, by combining those results, we obtain a proof of the equivalence between linear tangle and maximal single ideal. This short report gives an alternative proof of the equivalence.展开更多
基金Funded by National Natural Science Foundation of China(No.61176101)the PhD Programs Foundation of Ministry of Education of China(No.20120101120156)Key Laboratory of Nanodevices and Applications,Suzhou Institute of Nano-Tech and Nano-Bionics,Chinese Academy of Sciences(No.14JG01)
文摘Using the ab initio plane-wave ultrasoft pseudopotential method based on generalized gradient approximation（GGA）,we investigated the band-gap tuning in monolayer phosphorene（MLP） and bilayer phosphorene（BLP） by external electric fields applied perpendicular to the layers.The band continuously decreases with increasing applied electric fields,eventually rendering them metallic.For MLP,the phenomenon is explained in the light of the giant Stark effect,which is essentially characterized by the interlayer spacing,for the rate of change of bandgap with applied external field.The atomic distance and charges also contribute to the semiconductor-metal transition.The BLP is more sensitive to electric fields than MLP,since their charges are rearranged among bilayers and the bandgap can dramatically drop in terms of electronic field.The results show the bandgap will change for the fabrication of novel electronic and photonic devices.
文摘Vibration energy harvesting is widely recognized as the useful technology for saving energy. The piezoelectric energy harvesting device is one of energy harvester and is used to operate certain types of MEMS devices. Various factors influence the energy regeneration efficiency of the lead zirconate titanate piezoelectric (PZT) devices in converting the mechanical vibration energy to the electrical energy. This paper presents the analytical and experimental evaluation of energy regeneration efficiency of PZT devices through impedance matching method and drop-weight experiments to different shape of PZT devices. The results show that the impedance matching method has increased the energy regeneration efficiency while triangular shape of PZT device produce a stable efficiency in the energy regeneration. Besides that, it becomes clear that the power, energy and subsequently efficiency of the triangular plate are higher than those of the rectangular plate under the condition of the matching impedance and the same PZT area.
文摘The concept of linear tangle was introduced as an obstruction to mixed searching number. The concept of (maximal) single ideal has been introduced as an obstruction to linear-width. Moreover, it was already known that mixed search number is equivalent to linear-width. Hence, by combining those results, we obtain a proof of the equivalence between linear tangle and maximal single ideal. This short report gives an alternative proof of the equivalence.
