Recently a Hybrid Carrier(HC) scheme based on Weighted-type Fractional Fourier Transform(WFRFT) was proposed and developed,which contains Single Carrier(SC) and Multi-Carrier(MC) synergetic transmission.The wide inter...Recently a Hybrid Carrier(HC) scheme based on Weighted-type Fractional Fourier Transform(WFRFT) was proposed and developed,which contains Single Carrier(SC) and Multi-Carrier(MC) synergetic transmission.The wide interest is primarily due to its appealing characteristics,such as the robust performances in different types of selective fading channels and a great deal of potential for secure communications.According to the literatures,the HC signal and SC or MC signal probability distributions are different.In particular,some benefits of this HC scheme are brought by the quasi-Gaussian distribution of WFRFT signals.However,until now researchers have only presented statistic properties through computer simulations,and the accurate expressions of signals are not derived yet.In this paper,we derive the accurate and rigorously established closed-form expressions of Probability Density Function(PDF) of WFRFT signal real and imaginary parts with a large number of QPSK subcarriers,and this PDF can describe the behavior of data modulated by WFRFT,avoiding the complex computation for extensive computer simulations.Furthermore,the components of PDF expression are described and analyzed,and it is revealed that the tendency of signal quasi-Gaussian changes with the increasingof the parameter α(α in(0,1]).To validate the analytical results,extensive simulations have been conducted,showing a very good match between the analytical results and the real situations.The contribution of this paper may be useful to deduce the closed form expressions of Bit Error Ratio(BER),the Complementary Cumulative Distribution Function(CCDF) of Peak to Average Power Ratio(PAPR),and other analytical studies which adopt the PDF.展开更多
Armchair graphene nanoribbons with different proportions of edge oxygen atoms are analyzed in this study using the crystal orbital method,which is based on density functional theory.Although buckled edges are present,...Armchair graphene nanoribbons with different proportions of edge oxygen atoms are analyzed in this study using the crystal orbital method,which is based on density functional theory.Although buckled edges are present,all the nanoribbons are energetically favorable.Unlike the adjacent edge oxygen atoms,the isolated edge oxygen atoms cause semiconductor-metal transitions by introducing edge states.For graphene nanoribbons with all oxygen atoms on the edges,band gap and carrier mobility vary with ribbon width.Furthermore,this behavior is different from that of hydrogen-passivated graphene nanoribbons because of different effective widths,which are pictorially presented with crystal orbitals.The carrier mobilities are as 18%~65% magnitude as those of hydrogen-passivated nanoribbons and are of the order of 10^3 cm^2·V^-1·s^-1.展开更多
In the present work, firstly, a first-principles study of the structural, electronic, and electron transport properties of the HgxMg1-xTe（HMT） ternary compound is performed using the ABINIT package and the results a...In the present work, firstly, a first-principles study of the structural, electronic, and electron transport properties of the HgxMg1-xTe（HMT） ternary compound is performed using the ABINIT package and the results are compared with Cd0.9Zn0.1 Te（CZT） as a current room-temperature photodetector. Next, the response functions of Hg0.6Mg0.4Te and Cd0.9Zn0.1Te under electromagnetic irradiation with 0.05 Me V, 0.2 MeV, 0.661 MeV and 1.33 MeV energies are simulated by using the MCNP code. According to these simulations, the Hg0.6Mg0.4Te ternary compound is suggested as a good semiconductor photodetector for use at room temperature.展开更多
Scar hyperplasia at the suture site is an important reason for hindering the repair effect of peripheral nerve injury anastomosis. To address this issue, two repair methods are often used. Biological agents are used t...Scar hyperplasia at the suture site is an important reason for hindering the repair effect of peripheral nerve injury anastomosis. To address this issue, two repair methods are often used. Biological agents are used to block nerve sutures and the surrounding tissue to achieve phys- ical anti-adhesion effects. Another agent is glucocorticosteroid, which can prevent scar growth by inhibiting inflammation. However, the overall effect of promoting regeneration of the injured nerve is not satisfactory. In this regard, we envision that these two methods can be combined and lead to shared understanding for achieving improved nerve repair. In this study, the right tibial nerve was transected 1 cm above the knee to establish a rat tibial nerve injury model. The incision was directly sutured after nerve transection. The anastomotic stoma was coated with 0.5 × 0.5 cm^2 chitosan sheets with betamethasone dipropionate. At 12 weeks after injury, compared with the con- trol and poly （D, L-lactic acid） groups, chitosan-betamethasone dipropionate film slowly degraded with the shape of the membrane still intact. Further, scar hyperplasia and the degree of adhesion at anastomotic stoma were obviously reduced, while the regenerated nerve fiber structure was complete and arranged in a good order in model rats. Electrophysiological study showed enhanced compound muscle action potential. Our results confirm that chitosan-betamethasone dipropionate film can effectively prevent local scar hyperplasia after tibial nerve repair and promote nerve regeneration.展开更多
基金supported by the National Natural Science Foundation General Program of China(No.61201146)the National Basic Research Program of China(2013CB329003)the Fundamental Research Funds for the Central Universities(HIT.NSRIF.2015022)
文摘Recently a Hybrid Carrier(HC) scheme based on Weighted-type Fractional Fourier Transform(WFRFT) was proposed and developed,which contains Single Carrier(SC) and Multi-Carrier(MC) synergetic transmission.The wide interest is primarily due to its appealing characteristics,such as the robust performances in different types of selective fading channels and a great deal of potential for secure communications.According to the literatures,the HC signal and SC or MC signal probability distributions are different.In particular,some benefits of this HC scheme are brought by the quasi-Gaussian distribution of WFRFT signals.However,until now researchers have only presented statistic properties through computer simulations,and the accurate expressions of signals are not derived yet.In this paper,we derive the accurate and rigorously established closed-form expressions of Probability Density Function(PDF) of WFRFT signal real and imaginary parts with a large number of QPSK subcarriers,and this PDF can describe the behavior of data modulated by WFRFT,avoiding the complex computation for extensive computer simulations.Furthermore,the components of PDF expression are described and analyzed,and it is revealed that the tendency of signal quasi-Gaussian changes with the increasingof the parameter α(α in(0,1]).To validate the analytical results,extensive simulations have been conducted,showing a very good match between the analytical results and the real situations.The contribution of this paper may be useful to deduce the closed form expressions of Bit Error Ratio(BER),the Complementary Cumulative Distribution Function(CCDF) of Peak to Average Power Ratio(PAPR),and other analytical studies which adopt the PDF.
基金supported by the National Natural Science Foundation of China(No.21203127)the Beijing Higher Education Young Elite Teacher Project(YETP1629)the Scientific Research Base Development Program of the Beijing Municipal Commission of Education
文摘Armchair graphene nanoribbons with different proportions of edge oxygen atoms are analyzed in this study using the crystal orbital method,which is based on density functional theory.Although buckled edges are present,all the nanoribbons are energetically favorable.Unlike the adjacent edge oxygen atoms,the isolated edge oxygen atoms cause semiconductor-metal transitions by introducing edge states.For graphene nanoribbons with all oxygen atoms on the edges,band gap and carrier mobility vary with ribbon width.Furthermore,this behavior is different from that of hydrogen-passivated graphene nanoribbons because of different effective widths,which are pictorially presented with crystal orbitals.The carrier mobilities are as 18%~65% magnitude as those of hydrogen-passivated nanoribbons and are of the order of 10^3 cm^2·V^-1·s^-1.
基金the support of Shahrekord University under project number 230689
文摘In the present work, firstly, a first-principles study of the structural, electronic, and electron transport properties of the HgxMg1-xTe（HMT） ternary compound is performed using the ABINIT package and the results are compared with Cd0.9Zn0.1 Te（CZT） as a current room-temperature photodetector. Next, the response functions of Hg0.6Mg0.4Te and Cd0.9Zn0.1Te under electromagnetic irradiation with 0.05 Me V, 0.2 MeV, 0.661 MeV and 1.33 MeV energies are simulated by using the MCNP code. According to these simulations, the Hg0.6Mg0.4Te ternary compound is suggested as a good semiconductor photodetector for use at room temperature.
文摘Scar hyperplasia at the suture site is an important reason for hindering the repair effect of peripheral nerve injury anastomosis. To address this issue, two repair methods are often used. Biological agents are used to block nerve sutures and the surrounding tissue to achieve phys- ical anti-adhesion effects. Another agent is glucocorticosteroid, which can prevent scar growth by inhibiting inflammation. However, the overall effect of promoting regeneration of the injured nerve is not satisfactory. In this regard, we envision that these two methods can be combined and lead to shared understanding for achieving improved nerve repair. In this study, the right tibial nerve was transected 1 cm above the knee to establish a rat tibial nerve injury model. The incision was directly sutured after nerve transection. The anastomotic stoma was coated with 0.5 × 0.5 cm^2 chitosan sheets with betamethasone dipropionate. At 12 weeks after injury, compared with the con- trol and poly （D, L-lactic acid） groups, chitosan-betamethasone dipropionate film slowly degraded with the shape of the membrane still intact. Further, scar hyperplasia and the degree of adhesion at anastomotic stoma were obviously reduced, while the regenerated nerve fiber structure was complete and arranged in a good order in model rats. Electrophysiological study showed enhanced compound muscle action potential. Our results confirm that chitosan-betamethasone dipropionate film can effectively prevent local scar hyperplasia after tibial nerve repair and promote nerve regeneration.
