The use of atmospheric rotating gliding arc(RGA)plasma is proposed as a facile,scalable and catalyst-free approach to synthesizing hydrogen(H2)and graphene sheets from coalbed methane(CBM).CH4 is used as a CBM surroga...The use of atmospheric rotating gliding arc(RGA)plasma is proposed as a facile,scalable and catalyst-free approach to synthesizing hydrogen(H2)and graphene sheets from coalbed methane(CBM).CH4 is used as a CBM surrogate.Based on a previous investigation of discharge properties,product distribution and energy efficiency,the operating parameters such as CH4 concentration,applied voltage and gas flow rate can effectively affect the CH4 conversion rate,the selectivity of H2 and the properties of solid generated carbon.Nevertheless,the basic properties of RGA plasma and its role in CH4 conversion are scarcely mentioned.In the present work,a 3D RGA model,with a detailed nonequilibrium CH4/Ar plasma chemistry,is developed to validate the previous experiments on CBM conversion,aiming in particular at the distribution of H2 and other gas products.Our results demonstrate that the dynamics of RGA is derived from the joint effects of electron convection,electron migration and electron diffusion,and is prominently determined by the variation of the gas flow rate and applied voltage.Subsequently,a combined experimental and chemical kinetical simulation is performed to analyze the selectivity of gas products in an RGA reaction,taking into consideration the formation and loss pathways of crucial targeted substances(such as CH4,C2H2,H2 and H radicals)and corresponding contribution rates.Additionally,the effects of operating conditions on the properties of solid products are investigated by scanning electron microscopy(SEM)and Raman spectroscopy.The results show that increasing the applied voltage and decreasing CH4 concentration will change the solid carbon from its initial spherical structure into folded multilayer graphene sheets,while the size of the graphene sheets is slightly affected by the change in gas flow rate.展开更多
In the present paper, we introduce the coupled theory （CD）, Lord-Schulman （LS） theory, and Green-Lindsay （GL） theory to study the influences of a magnetic field and rotation on a two-dimensional problem of fibre...In the present paper, we introduce the coupled theory （CD）, Lord-Schulman （LS） theory, and Green-Lindsay （GL） theory to study the influences of a magnetic field and rotation on a two-dimensional problem of fibre-reinforced thermoelasticity. The material is a homogeneous isotropic elastic half-space. The method applied here is to use normal mode analysis to solve a thermal shock problem. Some particular cases are also discussed in the context of the problem. Deformation of a body depends on the nature of the force applied as well as the type of boundary conditions. Numerical results for the temperature, displacement, and thermal stress components are given and illustrated graphically in the absence and the presence of the magnetic field and rotation.展开更多
基于光磁耦合试验系统,利用新型复合磁性光催化剂,研究亚甲基蓝废水的降解性能,并讨论磁场强度、旋转速度、反应时间以及催化剂投加量对光磁耦合反应的影响.结果表明:旋转磁场能够显著加强光催化降解亚甲基蓝效果,当磁场强度为50 m T,...基于光磁耦合试验系统,利用新型复合磁性光催化剂,研究亚甲基蓝废水的降解性能,并讨论磁场强度、旋转速度、反应时间以及催化剂投加量对光磁耦合反应的影响.结果表明:旋转磁场能够显著加强光催化降解亚甲基蓝效果,当磁场强度为50 m T,转速为70 r·min-1,反应时间为120min,催化剂投加量为1.2 g·L-1条件下,光磁耦合处理系统对初始质量浓度为10 mg·L-1亚甲基蓝溶液的降解率为93.02%.通过对反应前后溶液的紫外-可见光扫描,发现经过光磁耦合处理系统作用反应后的溶液中,偶氮键与苯环特征峰均已消失,大部分亚甲基蓝得到有效降解.展开更多
同步发电机失磁故障对电网稳定性和发电机安全运行会产生很大影响。在中国,超高压发电机(extra high voltagegenerator,EHVG)是新型的同步发电机,其失磁后对电网的影响还处于研究阶段。为准确模拟EHVG失磁故障发生后磁场分布情况,建立了...同步发电机失磁故障对电网稳定性和发电机安全运行会产生很大影响。在中国,超高压发电机(extra high voltagegenerator,EHVG)是新型的同步发电机,其失磁后对电网的影响还处于研究阶段。为准确模拟EHVG失磁故障发生后磁场分布情况,建立了EHVG场、路、运动直接耦合的时步有限元分析模型,以EHVG模拟样机为算例,通过试验证明该模型正确,方法可行。利用该模型对EHVG同步运行和失磁异步运行的瞬态磁场进行对比分析,得出了同步运行和稳态异步运行时气隙磁密基波幅值基本一致,而失磁异步运行时气隙磁密谐波幅值较大;且随着EHVG失磁,稳态异步运行前所带负荷的减少进入稳态异步运行时,气隙磁密谐波分量也逐渐减小,气隙合成磁密接近正弦波,为其运行提供基础数据。展开更多
The ground-state properties,especially the magnetic moments,of odd-A aluminum isotopes have been studied and well reproduced in covariant density functional theory after considering the rotational coupling.The present...The ground-state properties,especially the magnetic moments,of odd-A aluminum isotopes have been studied and well reproduced in covariant density functional theory after considering the rotational coupling.The present calculations support the rotational structure in the ground state of odd-A aluminum isotopes,i.e.the ground state 5/2^+is built on the intrinsic state 5/2[202].In addition,the contribution from the time-odd fields is also discussed.展开更多
基金supported by the Foundation for Innovative Research Groups of National Natural Science Foundation of China (No. 51621005)China Postdoctoral Science Foundation (No. 2018M630672)
文摘The use of atmospheric rotating gliding arc(RGA)plasma is proposed as a facile,scalable and catalyst-free approach to synthesizing hydrogen(H2)and graphene sheets from coalbed methane(CBM).CH4 is used as a CBM surrogate.Based on a previous investigation of discharge properties,product distribution and energy efficiency,the operating parameters such as CH4 concentration,applied voltage and gas flow rate can effectively affect the CH4 conversion rate,the selectivity of H2 and the properties of solid generated carbon.Nevertheless,the basic properties of RGA plasma and its role in CH4 conversion are scarcely mentioned.In the present work,a 3D RGA model,with a detailed nonequilibrium CH4/Ar plasma chemistry,is developed to validate the previous experiments on CBM conversion,aiming in particular at the distribution of H2 and other gas products.Our results demonstrate that the dynamics of RGA is derived from the joint effects of electron convection,electron migration and electron diffusion,and is prominently determined by the variation of the gas flow rate and applied voltage.Subsequently,a combined experimental and chemical kinetical simulation is performed to analyze the selectivity of gas products in an RGA reaction,taking into consideration the formation and loss pathways of crucial targeted substances(such as CH4,C2H2,H2 and H radicals)and corresponding contribution rates.Additionally,the effects of operating conditions on the properties of solid products are investigated by scanning electron microscopy(SEM)and Raman spectroscopy.The results show that increasing the applied voltage and decreasing CH4 concentration will change the solid carbon from its initial spherical structure into folded multilayer graphene sheets,while the size of the graphene sheets is slightly affected by the change in gas flow rate.
文摘In the present paper, we introduce the coupled theory （CD）, Lord-Schulman （LS） theory, and Green-Lindsay （GL） theory to study the influences of a magnetic field and rotation on a two-dimensional problem of fibre-reinforced thermoelasticity. The material is a homogeneous isotropic elastic half-space. The method applied here is to use normal mode analysis to solve a thermal shock problem. Some particular cases are also discussed in the context of the problem. Deformation of a body depends on the nature of the force applied as well as the type of boundary conditions. Numerical results for the temperature, displacement, and thermal stress components are given and illustrated graphically in the absence and the presence of the magnetic field and rotation.
文摘同步发电机失磁故障对电网稳定性和发电机安全运行会产生很大影响。在中国,超高压发电机(extra high voltagegenerator,EHVG)是新型的同步发电机,其失磁后对电网的影响还处于研究阶段。为准确模拟EHVG失磁故障发生后磁场分布情况,建立了EHVG场、路、运动直接耦合的时步有限元分析模型,以EHVG模拟样机为算例,通过试验证明该模型正确,方法可行。利用该模型对EHVG同步运行和失磁异步运行的瞬态磁场进行对比分析,得出了同步运行和稳态异步运行时气隙磁密基波幅值基本一致,而失磁异步运行时气隙磁密谐波幅值较大;且随着EHVG失磁,稳态异步运行前所带负荷的减少进入稳态异步运行时,气隙磁密谐波分量也逐渐减小,气隙合成磁密接近正弦波,为其运行提供基础数据。
基金supported by the National Natural Science Foundation of China under Grants No.11675063,No.11205068,No.11475072,and No.11847310。
文摘The ground-state properties,especially the magnetic moments,of odd-A aluminum isotopes have been studied and well reproduced in covariant density functional theory after considering the rotational coupling.The present calculations support the rotational structure in the ground state of odd-A aluminum isotopes,i.e.the ground state 5/2^+is built on the intrinsic state 5/2[202].In addition,the contribution from the time-odd fields is also discussed.
