Muon tomography is a capable imaging technique to measure the geometry of high-Z objects. However,most existed algorithms used in muon tomography have obscured the effects of angular distribution and momentum spectra ...Muon tomography is a capable imaging technique to measure the geometry of high-Z objects. However,most existed algorithms used in muon tomography have obscured the effects of angular distribution and momentum spectra of cosmic ray muons and reduced the spatial resolution. We present a modified multi-group model that takes into account these effects and calibrates the model by the material of lead. Performance tests establish that the model is capable of measuring the thickness of a Pb slab and identifying the material of an unknown slab on a reasonable exposure timescale, in both cases of complete and incomplete angular data. Results show that the modified multi-group model is helpful for improvements in image resolution in real applications.展开更多
A new method based on angular momentum theory was proposed to construct the basis functions of the irreducible representations(IRs) of point groups. The transformation coefficients, i. e., coefficients S, are the com...A new method based on angular momentum theory was proposed to construct the basis functions of the irreducible representations(IRs) of point groups. The transformation coefficients, i. e., coefficients S, are the components of the eigenvectors of some Hermitian matrices, and can be made as real numbers for all pure rotation point groups. The general formula for coefficient S was deduced, and applied to constructing the basis functions of single-valued irreducible representations of icosahedral group from the spherical harmonics with angular momentum j≤7.展开更多
"We are pleased to announce another quarter of profitable growth,"said Dr.Roland Fischer,CEO of Oerlikon Group."Our positive performance confirms that our strategy addresses attractive markets,our initi..."We are pleased to announce another quarter of profitable growth,"said Dr.Roland Fischer,CEO of Oerlikon Group."Our positive performance confirms that our strategy addresses attractive markets,our initiatives and activities are delivering positive results,and we are able to take advantage of the growth momentum and opportunities in our end markets.Consequently,we are in a position to increase our full-year expectations for the second time this year."展开更多
This paper investigates the momentum-dependent symmetries for nonholonomic nonconservative Hamilton canonical systems. The definition and determining equations of the momentum-dependent symmetries are presented, based...This paper investigates the momentum-dependent symmetries for nonholonomic nonconservative Hamilton canonical systems. The definition and determining equations of the momentum-dependent symmetries are presented, based on the invariance of differential equations under infinitesimal transformations with respect to the generalized coordinates and generalized momentums. The structure equation and the non-Noether conserved quantities of the systems are obtained. The inverse issues associated with the momentum-dependent symmetries are discussed. Finally, an example is discussed to further illustrate the applications.展开更多
An Electromagnetic (EM) radiation in dispersion less free space vacuum is represented by a photon, with corpuscular and wave nature. The discussions, for the past century aimed at the nature of photon inside a media h...An Electromagnetic (EM) radiation in dispersion less free space vacuum is represented by a photon, with corpuscular and wave nature. The discussions, for the past century aimed at the nature of photon inside a media having dispersion in the refraction property, other than free space. What about its nature if the space be of refractive index which is negative, is discussed in this paper. We call mechanical momentum, wave-momentum, and try to match our present theories with intriguing property of this ‘photon’ or pulse carrying EM energy packet, and more so we try to find its property energy, momentum inside a media a positive refractive media, and if the media show a negative refractive index behavior, then these queries are profound, and suitable explanations to these classical concepts of corpuscular-wave nature of photon inside these media are quest for the scientists dealing with these materials having negative index of refraction. Here some of this counterintuitive nature of corpuscular-wave nature of photon inside negative indexed material is brought out, with possible ‘new definition’ of its ‘wave-momentum’, the concept of ‘reactive energy’ inside negative indexed material, along with possible ‘new wave equation’. These definitions and expressions of ‘wave-momentum’ and ‘reactive energy’ pertaining to negative indexed material are new and discussed and derived by classical means.展开更多
新工科的建设目标要求为新经济培养新型复合人才,基于问题/项目的学习(Problem/Project Based Learning,即PBL)被认为是一种能够调动学习积极性,同时能够激发及培养学生创新能力、多学科融合的教学方式。在大班授课模式下引入"互联...新工科的建设目标要求为新经济培养新型复合人才,基于问题/项目的学习(Problem/Project Based Learning,即PBL)被认为是一种能够调动学习积极性,同时能够激发及培养学生创新能力、多学科融合的教学方式。在大班授课模式下引入"互联网+"实施PBL,使受空间和时间限制的PBL活动通过网络实施成为可能。本文以大学物理中刚体的动量矩守恒定律为例详细讨论了如何在实际授课中通过"互联网+"和课堂教学活动实施PBL。研究结果表明,"互联网+"为教学实施PBL提供了课堂的拓展途径,成为课堂的有效延伸,进而为培养新工科人才奠定基础。展开更多
基金supported by the Science and Technology Development Foundation of CAEP(No.2015B0103014)the National Natural Science Foundation of China(No.11605163)
文摘Muon tomography is a capable imaging technique to measure the geometry of high-Z objects. However,most existed algorithms used in muon tomography have obscured the effects of angular distribution and momentum spectra of cosmic ray muons and reduced the spatial resolution. We present a modified multi-group model that takes into account these effects and calibrates the model by the material of lead. Performance tests establish that the model is capable of measuring the thickness of a Pb slab and identifying the material of an unknown slab on a reasonable exposure timescale, in both cases of complete and incomplete angular data. Results show that the modified multi-group model is helpful for improvements in image resolution in real applications.
文摘A new method based on angular momentum theory was proposed to construct the basis functions of the irreducible representations(IRs) of point groups. The transformation coefficients, i. e., coefficients S, are the components of the eigenvectors of some Hermitian matrices, and can be made as real numbers for all pure rotation point groups. The general formula for coefficient S was deduced, and applied to constructing the basis functions of single-valued irreducible representations of icosahedral group from the spherical harmonics with angular momentum j≤7.
文摘"We are pleased to announce another quarter of profitable growth,"said Dr.Roland Fischer,CEO of Oerlikon Group."Our positive performance confirms that our strategy addresses attractive markets,our initiatives and activities are delivering positive results,and we are able to take advantage of the growth momentum and opportunities in our end markets.Consequently,we are in a position to increase our full-year expectations for the second time this year."
基金Project supported by the National Natural Science Foundation of China （Grant No 10372053） and the Natural Science Foundation of Henan Province, China （Grant Nos 0311011400 and 0511022200） and the State Key Laboratory of Scientific and Engineering Computing, Chinese Academy of Sciences.
文摘This paper investigates the momentum-dependent symmetries for nonholonomic nonconservative Hamilton canonical systems. The definition and determining equations of the momentum-dependent symmetries are presented, based on the invariance of differential equations under infinitesimal transformations with respect to the generalized coordinates and generalized momentums. The structure equation and the non-Noether conserved quantities of the systems are obtained. The inverse issues associated with the momentum-dependent symmetries are discussed. Finally, an example is discussed to further illustrate the applications.
文摘An Electromagnetic (EM) radiation in dispersion less free space vacuum is represented by a photon, with corpuscular and wave nature. The discussions, for the past century aimed at the nature of photon inside a media having dispersion in the refraction property, other than free space. What about its nature if the space be of refractive index which is negative, is discussed in this paper. We call mechanical momentum, wave-momentum, and try to match our present theories with intriguing property of this ‘photon’ or pulse carrying EM energy packet, and more so we try to find its property energy, momentum inside a media a positive refractive media, and if the media show a negative refractive index behavior, then these queries are profound, and suitable explanations to these classical concepts of corpuscular-wave nature of photon inside these media are quest for the scientists dealing with these materials having negative index of refraction. Here some of this counterintuitive nature of corpuscular-wave nature of photon inside negative indexed material is brought out, with possible ‘new definition’ of its ‘wave-momentum’, the concept of ‘reactive energy’ inside negative indexed material, along with possible ‘new wave equation’. These definitions and expressions of ‘wave-momentum’ and ‘reactive energy’ pertaining to negative indexed material are new and discussed and derived by classical means.
文摘新工科的建设目标要求为新经济培养新型复合人才,基于问题/项目的学习(Problem/Project Based Learning,即PBL)被认为是一种能够调动学习积极性,同时能够激发及培养学生创新能力、多学科融合的教学方式。在大班授课模式下引入"互联网+"实施PBL,使受空间和时间限制的PBL活动通过网络实施成为可能。本文以大学物理中刚体的动量矩守恒定律为例详细讨论了如何在实际授课中通过"互联网+"和课堂教学活动实施PBL。研究结果表明,"互联网+"为教学实施PBL提供了课堂的拓展途径,成为课堂的有效延伸,进而为培养新工科人才奠定基础。
