Motivated by recent realizations of spin-1 NaRb mixtures in the experiments[Phys.Rev.Lett.114,255301(2015);Phys.Rev.Lett.128,223201(2022)],we investigate heteronuclear magnetism in the Mott-insulating regime.Different...Motivated by recent realizations of spin-1 NaRb mixtures in the experiments[Phys.Rev.Lett.114,255301(2015);Phys.Rev.Lett.128,223201(2022)],we investigate heteronuclear magnetism in the Mott-insulating regime.Different from the identical mixtures where the boson statistics only admits even parity states from angular momentum composition,for heteronuclear atoms in principle all angular momentum states are allowed,which can give rise to new magnetic phases.While various magnetic phases can be developed over these degenerate spaces,the concrete symmetry breaking phases depend on not only the degree of degeneracy but also the competitions from many-body interactions.We unveil these rich phases using the bosonic dynamical mean-field theory approach.These phases are characterized by various orders,including spontaneous magnetization order,spin magnitude order,singlet pairing order,and nematic order,which may coexist specially in the regime with odd parity.Finally we address the possible parameter regimes for observing these spin-ordered Mott phases.展开更多
With the increase of underground engineering construction depth,the phenomenon of surrounding rock sudden failure caused by supporting structure failure occurs frequently.The conventional unloading con-fining pressure...With the increase of underground engineering construction depth,the phenomenon of surrounding rock sudden failure caused by supporting structure failure occurs frequently.The conventional unloading con-fining pressure(CUCP)test cannot simulate the plastic yielding and instantaneous unloading process of supporting structure to rock.Thus,a high stress loading-instantaneous unloading confining pressure(HSL-IUCP)test method was proposed and applied by considering bolt’s fracture under stress.The wall thickness of confining pressure plates and the material of bolts were changed to realize different confin-ing pressure loading stiffness(CPLS)and lateral maximum allowable deformation(LMAD).The superio-rity of HSL-ICPU method is verified compared with CUCP.The rock failure mechanism caused by sudden failure of supporting structure is obtained.The results show that when CPLS increases from 1.35 to 2.33 GN/m,rock’s peak strength and elastic modulus increase by 25.18%and 23.70%,respectively.The fracture characteristics change from tensile failure to tensile-shear mixed failure.When LMAD decreases from 0.40 to 0.16 mm,rock’s residual strength,peak strain,and residual strain decrease by 91.80%,16.94%,and 21.92%,respectively,and post-peak drop modulus increases by 140.47%.The test results obtained by this method are closer to rock’s real mechanical response characteristics compared with CUCP.展开更多
Current installation costs of offshore wind turbines(OWTs) are high and profit margins in the offshore wind energy sector are low, it is thus necessary to develop installation methods that are more efficient and pract...Current installation costs of offshore wind turbines(OWTs) are high and profit margins in the offshore wind energy sector are low, it is thus necessary to develop installation methods that are more efficient and practical. This paper presents a numerical study(based on a global response analysis of marine operations) of a novel procedure for installing the tower and Rotor Nacelle Assemblies(RNAs) on bottom-fixed foundations of OWTs. The installation procedure is based on the inverted pendulum principle. A cargo barge is used to transport the OWT assembly in a horizontal position to the site, and a medium-size Heavy Lift Vessel(HLV) is then employed to lift and up-end the OWT assembly using a special upending frame. The main advantage of this novel procedure is that the need for a huge HLV(in terms of lifting height and capacity) is eliminated. This novel method requires that the cargo barge is in the leeward side of the HLV(which can be positioned with the best heading) during the entire installation. This is to benefit from shielding effects of the HLV on the motions of the cargo barge, so the foundations need to be installed with a specific heading based on wave direction statistics of the site and a typical installation season. Following a systematic approach based on numerical simulations of actual operations, potential critical installation activities, corresponding critical events, and limiting(response) parameters are identified. In addition, operational limits for some of the limiting parameters are established in terms of allowable limits of sea states. Following a preliminary assessment of these operational limits, the duration of the entire operation, the equipment used, and weather-and water depth-sensitivity, this novel procedure is demonstrated to be viable.展开更多
In contrast to most existing works on robust unit commitment(UC),this study proposes a novel big-M-based mixed-integer linear programming(MILP)method to solve security-constrained UC problems considering the allowable...In contrast to most existing works on robust unit commitment(UC),this study proposes a novel big-M-based mixed-integer linear programming(MILP)method to solve security-constrained UC problems considering the allowable wind power output interval and its adjustable conservativeness.The wind power accommodation capability is usually limited by spinning reserve requirements and transmission line capacity in power systems with large-scale wind power integration.Therefore,by employing the big-M method and adding auxiliary 0-1 binary variables to describe the allowable wind power output interval,a bilinear programming problem meeting the security constraints of system operation is presented.Furthermore,an adjustable confidence level was introduced into the proposed robust optimization model to decrease the level of conservatism of the robust solutions.This can establish a trade-off between economy and security.To develop an MILP problem that can be solved by commercial solvers such as CPLEX,the big-M method is utilized again to represent the bilinear formulation as a series of linear inequality constraints and approximately address the nonlinear formulation caused by the adjustable conservativeness.Simulation studies on a modified IEEE 26-generator reliability test system connected to wind farms were performed to confirm the effectiveness and advantages of the proposed method.展开更多
For the tripod bucket jacket foundations used in offshore wind turbines, the probable critical tilt angles should be avoidedduring tilt adjustment operation. Thus, these critical values must be identified by engineers...For the tripod bucket jacket foundations used in offshore wind turbines, the probable critical tilt angles should be avoidedduring tilt adjustment operation. Thus, these critical values must be identified by engineers, and remedial techniques mustbe established prior to the occurrence of the problem. Model tests were carried out for typical tilting conditions of tripodbucket foundations, which were allowed to tilt freely at various penetration depths without interruption by manualoperation. After the foundation ceased its tilting, some measures, such as water pumping, water injection, air injection, or acombination of the above methods, were enabled for adjustment. The research results showed two critical values in thetilting state of the tripod bucket jacket foundation, namely the terminal and allowable angles. In the installation condition,the terminal angle was negatively correlated with the initial penetration depth, but the opposite was observed with theremoval condition. The allowable angle was less than or equal to the terminal angle. The allowable angle in the installationwas related to the terminal angle. The critical angles all varied linearly with the initial penetration depth. When tiltingduring installation, adjustment measures can be used in the order of high drum pumping, low drum water injection, highdrum pumping and low drum water injection, air injection, and exhaust. When tilting during removal, the sequential use oflow drum water injection, air, and exhaust was applied. For buckets that were sensitive to angle changes, adjustmentmeasures of the “point injection” mode can be selected.展开更多
A k⋅p effective Hamiltonian is important for theoretical analysis in condensed matter physics.Based on the kdotp-symmetry package,we develop an upgraded package named as kdotp-generator.This generator takes in arbitra...A k⋅p effective Hamiltonian is important for theoretical analysis in condensed matter physics.Based on the kdotp-symmetry package,we develop an upgraded package named as kdotp-generator.This generator takes in arbitrary magnetic symmetries with their representations and returns symmetry-allowed k⋅p Hamiltonians.Using this package,we calculate k⋅p Hamiltonians for irreducible co-representations in 1651 magnetic space groups up to the third order,and their linear coupling to external fields including the electromagnetic field and the strain tensor.We hope that the package will facilitate related research in the future.展开更多
The extending of a cantilever and transverse moving of a drilling floor enable the jack-up to operate in several well positions after the Jack-up has pitched. The cantilever allowable load nephogram is the critical re...The extending of a cantilever and transverse moving of a drilling floor enable the jack-up to operate in several well positions after the Jack-up has pitched. The cantilever allowable load nephogram is the critical reference which can evaluate the jack-up's drilling ability, design the cantilever structure and instruct a jack-up manager to make the operations safe. The intent of this paper is to explore the interrelationships between the cantilever position, drilling floor and the loads including wind force, the stand set-back weight etc., through analyzing the structure and load characteristics of the x-type cantilever and the simplified mechanics model with the restriction of the maximum moment capacity of the cantilever single side beam. Referring to several typical position designs load values, the cantilever allowable load nephogram is obtained by using the suitable interpolation method. The paper gives a method for cantilever allowable load design, which is proved reliable and effective by the calculation example.展开更多
Criterion of differential settlement in subgrade is useful for keeping road in a good serving condition. The theory of traditional materials strength and their technologic economy are applied to analyze the additional...Criterion of differential settlement in subgrade is useful for keeping road in a good serving condition. The theory of traditional materials strength and their technologic economy are applied to analyze the additional bend stress of the pavement structure, the equivalent beam of elastic foundation and influence on the pavement structure of an uneven settlement. The allowable settling ratio of pavement index （ △i ） is got and is used to appraise the uneven settlement standard value in subgrade. The allowable settling ratio of pavement index is applied in an certain widening expressway project and △i ≤0.36 % is attained by the analyzing, calculating and adding a certain safe coefficient. This value was put into practice and is effective during the past two years.展开更多
问:(在1983年您关于设计的第一篇文章中)您写道:"对于某种技能高度熟练的掌握,如渲染或者模型制作,会让创作者被平庸的解决方案所蛊惑。"我感觉这是您在《设计改变一切》这本书中想要表达的关键问题,对吗?So,you wrote,"...问:(在1983年您关于设计的第一篇文章中)您写道:"对于某种技能高度熟练的掌握,如渲染或者模型制作,会让创作者被平庸的解决方案所蛊惑。"我感觉这是您在《设计改变一切》这本书中想要表达的关键问题,对吗?So,you wrote,"A great proficiency in a certain skill,such as rendering or model-making,has allowed a mediocre solution to seduce those for whom it was produced".Which I feel like is actually central to your book,"Change by Design",right?展开更多
The multi-configuration Dirac-Fock method is employed to calculate the energy levels and transition probabilities for the electric dipole allowed (El) and forbidden (M1,E2) lines for the 4s^(2) 4p,4s4p^(2) and 4s^(2) ...The multi-configuration Dirac-Fock method is employed to calculate the energy levels and transition probabilities for the electric dipole allowed (El) and forbidden (M1,E2) lines for the 4s^(2) 4p,4s4p^(2) and 4s^(2) 4d configurations of highly charged Ga-like ions from Z =68-95.The lifetimes of the 4s^(2) 4p^(2) P3/2 level of the ground configuration are also derived.Based on our calculations,it is found that the energy level of the 4s2 4p 2P3/2 is higher than that of the 4s4p24P1/2 for the high-Z Ga-like ions with Z ≥ 74,so as to generate an energy crossing at Z =74.The effect of the energy crossing is important to the calculation of the 4s^(2) 4p^(2) P3/2 level lifetime for Ga-like ions with Z≥ 74.展开更多
Symmetry has imposed very strong constraints on the internal structure of quantum mechanical system.In particular,whether a state can access a given outgoing channel is constrained by symmetry.For the dipositroniums,t...Symmetry has imposed very strong constraints on the internal structure of quantum mechanical system.In particular,whether a state can access a given outgoing channel is constrained by symmetry.For the dipositroniums,the most important channel is the Ps-Ps channel.However,based on symmetry consideration it was found that only a few excited states are allowed to access the Ps-Ps channel,thereby at least the existence of two higher L=0 bound states(higher than the Ps-Ps threshold)has been affirmed.展开更多
By applying systematically enlarged multi-configuration Dirac-Fock wavefunction, the transitions for electricdipole allowed （E1） and forbidden （E2, M1 and M2） lines are studied among 4f pair coupling and low-lying...By applying systematically enlarged multi-configuration Dirac-Fock wavefunction, the transitions for electricdipole allowed （E1） and forbidden （E2, M1 and M2） lines are studied among 4f pair coupling and low-lying configurations for singly ionized nitrogen. Most important effects of relativity, electron correlation, the rearrangement of electron density, Breit interaction, and quantum electrodynamic effects are included in the computation. Then, allowed （E1） and forbidden （E2, M1 and M2） transition probabilities of 4f for N＋ are obtained and compared with experimental results. Good agreement with available experimental results is found and most of the data of 4f are presented for the first time.展开更多
Within the context of the topcolor-assisted technicolor(TC2)model we investigate the associated production of the neutral top-higgs hto with a pair of top quarks,i.e.pp→t_(t)hto at the Large Hadron Collider(LHC),whic...Within the context of the topcolor-assisted technicolor(TC2)model we investigate the associated production of the neutral top-higgs hto with a pair of top quarks,i.e.pp→t_(t)hto at the Large Hadron Collider(LHC),which proceeds through the partonic processes q(q)→t_(t)hto and gg→t_(t)hto.We calculate the production rate and show the distributions of the transverse momenta of hto.It is found that the cross section of pp→t_(t)hot can reach a few hundred fb in the most part of the allowed parameter space and even a few tens of pb for the light top-higgs.Due to the large cross section of t_(t)hto production and the top-charm decay mode of h0t for mhto<2mt,the process pp→t_(t)hto can play an important role in the probe of neutral top-higgs and the test of the TC2 model.展开更多
Optical studies of the CdTe/CdMnTe multiple quantum well structures with diluted manganese in barriers are presented.The combined measurements of photoluminescence and photoluminescence excitation allowed direct obser...Optical studies of the CdTe/CdMnTe multiple quantum well structures with diluted manganese in barriers are presented.The combined measurements of photoluminescence and photoluminescence excitation allowed direct observation of the binding energies of n=l heavy-and light-hole free excitons.The quantitative approach of variation of exciton binding energies with well width and barrier potential height is given.The calculated and measured exciton binding energies are in good agreement.Photoluminescence studies also show exciton-acoustic phonon scattering dominates the broadening of the exciton line width up to T=50 K,while T>50 K longitudinal-optical phonon scattering contributes to the line width broadening significantly.展开更多
We report a study of the resonant Raman scattering(RRS)by optical phonons that is induced by excitons bound to isoelectronic nitrogen impurities in GaAs_(1-x)P_(x):N alloys.Under resonant excitation into N_(x) band,st...We report a study of the resonant Raman scattering(RRS)by optical phonons that is induced by excitons bound to isoelectronic nitrogen impurities in GaAs_(1-x)P_(x):N alloys.Under resonant excitation into N_(x) band,strong Raman lines involving allowed LO and "forbidden" TO for badkscattering coniiguration from(100)surface are observed.This is interpreted as the breakdown of normal selection rule in the RRS process.By following the temperature dependence of the N_(x)luminescence and its phonon sidebands,we also separate RRS from sharp line due to luminescence.展开更多
A simple extension of the standard model(SM) with a μ-flavored vector-like lepton(VLL) doublet and a real singlet scalar can have an interesting implication to the h→μ^(+)μ^(-)decay while offering the simplest pos...A simple extension of the standard model(SM) with a μ-flavored vector-like lepton(VLL) doublet and a real singlet scalar can have an interesting implication to the h→μ^(+)μ^(-)decay while offering the simplest possible explanation for the dark matter(DM) phenomenology.Assuming the real singlet scalar to be a viable DM candidate,it has been shown that the muon Yukawa coupling can have a negative contribution at the oneloop order if the 2^(nd) generation SM leptons are allowed to couple with the VLL doublet.The stringent direct detection bounds corresponding to a real singlet scalar DM can easily be relaxed if the SM quark sector was augmented with a dimension-6 operator at some new physics(NP) scale Λ_(NP).Thus,this model presents a significant phenomenological study where the muon Yukawa coupling can be corrected within a real singlet scalar DM framework.The considered parameter space can be tested/constrained through the high luminosity run of the LHC(HL-LHC) and future direct detection experiments.展开更多
Based on an analysis of the inherent nodal structures of wave functions of 4-boson systems,we found that the internal energy of the 4_(1)^(+) state should be lower because its structure can be optimized without suffer...Based on an analysis of the inherent nodal structures of wave functions of 4-boson systems,we found that the internal energy of the 4_(1)^(+) state should be lower because its structure can be optimized without suffering a strong constraint arising from symmetry(while other 1≤L≤3 states suffer from this kind of constraints).Furthermore,two superior structures favorable in binding are found to be allowed to be possessed by 4^(+) states.These findings would lead to the appearance of two adjacent 4^(+) states,as a common feature,in the low-lying spectra of 4 boson systems.展开更多
A new quantum optical mechanism to realize simultaneously negative electric permittivity and magnetic permeability is suggested. In order to obtain a negative permeability, we choose a proper atomic configuration that...A new quantum optical mechanism to realize simultaneously negative electric permittivity and magnetic permeability is suggested. In order to obtain a negative permeability, we choose a proper atomic configuration that can dramatically enhance the contribution of the magnetic-dipole allowed transition via the atomic phase coherence. It is shown that the atomic system chosen with proper optical parameters can give rise to striking electromagnetic responses （leading to a negative refractive index） and that the atomic vapour becomes a left-handed medium in an optical frequency band. Differing from the previous schemes of artificial composite metamaterials （based on classical electromagnetic theory） to achieve the left-handed materials, which consist of anisotropic millimetre-scale composite structure units, the left-handed atomic vapour presented here is isotropic and homogeneous at the atomic-scale level. Such an advantage may be valuable in realizing the superlens （and hence perfect image） with left-handed atomic vapour.展开更多
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB0500000)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0301200)+1 种基金the National Natural Science Foundation of China(Grant Nos.12074431,12274384,and 12374252)the Excellent Youth Foundation of Hunan Scientific Committee(Grant No.2021JJ10044).
文摘Motivated by recent realizations of spin-1 NaRb mixtures in the experiments[Phys.Rev.Lett.114,255301(2015);Phys.Rev.Lett.128,223201(2022)],we investigate heteronuclear magnetism in the Mott-insulating regime.Different from the identical mixtures where the boson statistics only admits even parity states from angular momentum composition,for heteronuclear atoms in principle all angular momentum states are allowed,which can give rise to new magnetic phases.While various magnetic phases can be developed over these degenerate spaces,the concrete symmetry breaking phases depend on not only the degree of degeneracy but also the competitions from many-body interactions.We unveil these rich phases using the bosonic dynamical mean-field theory approach.These phases are characterized by various orders,including spontaneous magnetization order,spin magnitude order,singlet pairing order,and nematic order,which may coexist specially in the regime with odd parity.Finally we address the possible parameter regimes for observing these spin-ordered Mott phases.
基金the National Natural Science Foundation of China(Nos.52374218,52174122 and 52374094)Outstanding Youth Fund of Shandong Natural Science Foundation(No.ZR2022YQ49)Taishan Scholar Project in Shandong Province(Nos.tspd20210313 and tsqn202211150).
文摘With the increase of underground engineering construction depth,the phenomenon of surrounding rock sudden failure caused by supporting structure failure occurs frequently.The conventional unloading con-fining pressure(CUCP)test cannot simulate the plastic yielding and instantaneous unloading process of supporting structure to rock.Thus,a high stress loading-instantaneous unloading confining pressure(HSL-IUCP)test method was proposed and applied by considering bolt’s fracture under stress.The wall thickness of confining pressure plates and the material of bolts were changed to realize different confin-ing pressure loading stiffness(CPLS)and lateral maximum allowable deformation(LMAD).The superio-rity of HSL-ICPU method is verified compared with CUCP.The rock failure mechanism caused by sudden failure of supporting structure is obtained.The results show that when CPLS increases from 1.35 to 2.33 GN/m,rock’s peak strength and elastic modulus increase by 25.18%and 23.70%,respectively.The fracture characteristics change from tensile failure to tensile-shear mixed failure.When LMAD decreases from 0.40 to 0.16 mm,rock’s residual strength,peak strain,and residual strain decrease by 91.80%,16.94%,and 21.92%,respectively,and post-peak drop modulus increases by 140.47%.The test results obtained by this method are closer to rock’s real mechanical response characteristics compared with CUCP.
基金financially supported by the Research Council of Norway granted through the Department of Marine Technologythe Centre for Ships and Ocean Structures(CeSOS) and the the Centre for Autonomous Marine Operations and Systems(AMOS) from the Norwegian University of Science and Technology(NTNU)the financial support from Escuela Politécnica Nacional(EPN)through the project PIMI-15-03"Investigación y evaluación de sistemas innovadores de propulsión distribuida con ingestión de capa límite para mejorar la eficiencia propulsiva y térmica de vehículos aéreos no tripulados aplicados en los sectores:agrícola,medicina y vigilancia"
文摘Current installation costs of offshore wind turbines(OWTs) are high and profit margins in the offshore wind energy sector are low, it is thus necessary to develop installation methods that are more efficient and practical. This paper presents a numerical study(based on a global response analysis of marine operations) of a novel procedure for installing the tower and Rotor Nacelle Assemblies(RNAs) on bottom-fixed foundations of OWTs. The installation procedure is based on the inverted pendulum principle. A cargo barge is used to transport the OWT assembly in a horizontal position to the site, and a medium-size Heavy Lift Vessel(HLV) is then employed to lift and up-end the OWT assembly using a special upending frame. The main advantage of this novel procedure is that the need for a huge HLV(in terms of lifting height and capacity) is eliminated. This novel method requires that the cargo barge is in the leeward side of the HLV(which can be positioned with the best heading) during the entire installation. This is to benefit from shielding effects of the HLV on the motions of the cargo barge, so the foundations need to be installed with a specific heading based on wave direction statistics of the site and a typical installation season. Following a systematic approach based on numerical simulations of actual operations, potential critical installation activities, corresponding critical events, and limiting(response) parameters are identified. In addition, operational limits for some of the limiting parameters are established in terms of allowable limits of sea states. Following a preliminary assessment of these operational limits, the duration of the entire operation, the equipment used, and weather-and water depth-sensitivity, this novel procedure is demonstrated to be viable.
基金State Grid Jiangsu Electric Power Co.,Ltd(JF2020001)National Key Technology R&D Program of China(2017YFB0903300)State Grid Corporation of China(521OEF17001C).
文摘In contrast to most existing works on robust unit commitment(UC),this study proposes a novel big-M-based mixed-integer linear programming(MILP)method to solve security-constrained UC problems considering the allowable wind power output interval and its adjustable conservativeness.The wind power accommodation capability is usually limited by spinning reserve requirements and transmission line capacity in power systems with large-scale wind power integration.Therefore,by employing the big-M method and adding auxiliary 0-1 binary variables to describe the allowable wind power output interval,a bilinear programming problem meeting the security constraints of system operation is presented.Furthermore,an adjustable confidence level was introduced into the proposed robust optimization model to decrease the level of conservatism of the robust solutions.This can establish a trade-off between economy and security.To develop an MILP problem that can be solved by commercial solvers such as CPLEX,the big-M method is utilized again to represent the bilinear formulation as a series of linear inequality constraints and approximately address the nonlinear formulation caused by the adjustable conservativeness.Simulation studies on a modified IEEE 26-generator reliability test system connected to wind farms were performed to confirm the effectiveness and advantages of the proposed method.
文摘For the tripod bucket jacket foundations used in offshore wind turbines, the probable critical tilt angles should be avoidedduring tilt adjustment operation. Thus, these critical values must be identified by engineers, and remedial techniques mustbe established prior to the occurrence of the problem. Model tests were carried out for typical tilting conditions of tripodbucket foundations, which were allowed to tilt freely at various penetration depths without interruption by manualoperation. After the foundation ceased its tilting, some measures, such as water pumping, water injection, air injection, or acombination of the above methods, were enabled for adjustment. The research results showed two critical values in thetilting state of the tripod bucket jacket foundation, namely the terminal and allowable angles. In the installation condition,the terminal angle was negatively correlated with the initial penetration depth, but the opposite was observed with theremoval condition. The allowable angle was less than or equal to the terminal angle. The allowable angle in the installationwas related to the terminal angle. The critical angles all varied linearly with the initial penetration depth. When tiltingduring installation, adjustment measures can be used in the order of high drum pumping, low drum water injection, highdrum pumping and low drum water injection, air injection, and exhaust. When tilting during removal, the sequential use oflow drum water injection, air, and exhaust was applied. For buckets that were sensitive to angle changes, adjustmentmeasures of the “point injection” mode can be selected.
基金Supported by National Key R&D Program of China(Grant No.2016YFA0302400)Chinese Academy of Sciences(Grant No.XDB33000000).
文摘A k⋅p effective Hamiltonian is important for theoretical analysis in condensed matter physics.Based on the kdotp-symmetry package,we develop an upgraded package named as kdotp-generator.This generator takes in arbitrary magnetic symmetries with their representations and returns symmetry-allowed k⋅p Hamiltonians.Using this package,we calculate k⋅p Hamiltonians for irreducible co-representations in 1651 magnetic space groups up to the third order,and their linear coupling to external fields including the electromagnetic field and the strain tensor.We hope that the package will facilitate related research in the future.
文摘The extending of a cantilever and transverse moving of a drilling floor enable the jack-up to operate in several well positions after the Jack-up has pitched. The cantilever allowable load nephogram is the critical reference which can evaluate the jack-up's drilling ability, design the cantilever structure and instruct a jack-up manager to make the operations safe. The intent of this paper is to explore the interrelationships between the cantilever position, drilling floor and the loads including wind force, the stand set-back weight etc., through analyzing the structure and load characteristics of the x-type cantilever and the simplified mechanics model with the restriction of the maximum moment capacity of the cantilever single side beam. Referring to several typical position designs load values, the cantilever allowable load nephogram is obtained by using the suitable interpolation method. The paper gives a method for cantilever allowable load design, which is proved reliable and effective by the calculation example.
基金Sponsored by Project of Ning Xia Hui Autonormous Region Communications Department2005
文摘Criterion of differential settlement in subgrade is useful for keeping road in a good serving condition. The theory of traditional materials strength and their technologic economy are applied to analyze the additional bend stress of the pavement structure, the equivalent beam of elastic foundation and influence on the pavement structure of an uneven settlement. The allowable settling ratio of pavement index （ △i ） is got and is used to appraise the uneven settlement standard value in subgrade. The allowable settling ratio of pavement index is applied in an certain widening expressway project and △i ≤0.36 % is attained by the analyzing, calculating and adding a certain safe coefficient. This value was put into practice and is effective during the past two years.
文摘问:(在1983年您关于设计的第一篇文章中)您写道:"对于某种技能高度熟练的掌握,如渲染或者模型制作,会让创作者被平庸的解决方案所蛊惑。"我感觉这是您在《设计改变一切》这本书中想要表达的关键问题,对吗?So,you wrote,"A great proficiency in a certain skill,such as rendering or model-making,has allowed a mediocre solution to seduce those for whom it was produced".Which I feel like is actually central to your book,"Change by Design",right?
基金Supported by the National Natural Science Foundation of China under Grant Nos 10876028,10847007 and 10964010the Scientific Research Foundation of the Higher Education Institutions of Gansu Province.
文摘The multi-configuration Dirac-Fock method is employed to calculate the energy levels and transition probabilities for the electric dipole allowed (El) and forbidden (M1,E2) lines for the 4s^(2) 4p,4s4p^(2) and 4s^(2) 4d configurations of highly charged Ga-like ions from Z =68-95.The lifetimes of the 4s^(2) 4p^(2) P3/2 level of the ground configuration are also derived.Based on our calculations,it is found that the energy level of the 4s2 4p 2P3/2 is higher than that of the 4s4p24P1/2 for the high-Z Ga-like ions with Z ≥ 74,so as to generate an energy crossing at Z =74.The effect of the energy crossing is important to the calculation of the 4s^(2) 4p^(2) P3/2 level lifetime for Ga-like ions with Z≥ 74.
基金Supported by the National Natural Science Foundation of China under Grant No.19875084the fund of National Educational Committee of China。
文摘Symmetry has imposed very strong constraints on the internal structure of quantum mechanical system.In particular,whether a state can access a given outgoing channel is constrained by symmetry.For the dipositroniums,the most important channel is the Ps-Ps channel.However,based on symmetry consideration it was found that only a few excited states are allowed to access the Ps-Ps channel,thereby at least the existence of two higher L=0 bound states(higher than the Ps-Ps threshold)has been affirmed.
基金Project supported by the Foundation of Handan College,China (Grant No. 09005)the National Natural Science Foundation of China (Grant No. 40475007)
文摘By applying systematically enlarged multi-configuration Dirac-Fock wavefunction, the transitions for electricdipole allowed （E1） and forbidden （E2, M1 and M2） lines are studied among 4f pair coupling and low-lying configurations for singly ionized nitrogen. Most important effects of relativity, electron correlation, the rearrangement of electron density, Breit interaction, and quantum electrodynamic effects are included in the computation. Then, allowed （E1） and forbidden （E2, M1 and M2） transition probabilities of 4f for N＋ are obtained and compared with experimental results. Good agreement with available experimental results is found and most of the data of 4f are presented for the first time.
基金Supported by the National Natural Science Foundation of China under Grant No 10775039the Specialized Research Fund for the Doctoral Program of Higher Education under Grant No 20094104110001and the Program for Youths’Talents of Xinyang Normal University under Grant No 200950。
文摘Within the context of the topcolor-assisted technicolor(TC2)model we investigate the associated production of the neutral top-higgs hto with a pair of top quarks,i.e.pp→t_(t)hto at the Large Hadron Collider(LHC),which proceeds through the partonic processes q(q)→t_(t)hto and gg→t_(t)hto.We calculate the production rate and show the distributions of the transverse momenta of hto.It is found that the cross section of pp→t_(t)hot can reach a few hundred fb in the most part of the allowed parameter space and even a few tens of pb for the light top-higgs.Due to the large cross section of t_(t)hto production and the top-charm decay mode of h0t for mhto<2mt,the process pp→t_(t)hto can play an important role in the probe of neutral top-higgs and the test of the TC2 model.
基金Supported in part by the National Natural Science Foundation of China under Grant No.69606006the Office of State Education Commission.
文摘Optical studies of the CdTe/CdMnTe multiple quantum well structures with diluted manganese in barriers are presented.The combined measurements of photoluminescence and photoluminescence excitation allowed direct observation of the binding energies of n=l heavy-and light-hole free excitons.The quantitative approach of variation of exciton binding energies with well width and barrier potential height is given.The calculated and measured exciton binding energies are in good agreement.Photoluminescence studies also show exciton-acoustic phonon scattering dominates the broadening of the exciton line width up to T=50 K,while T>50 K longitudinal-optical phonon scattering contributes to the line width broadening significantly.
基金Supported by the National Natural Science Foundation of China.
文摘We report a study of the resonant Raman scattering(RRS)by optical phonons that is induced by excitons bound to isoelectronic nitrogen impurities in GaAs_(1-x)P_(x):N alloys.Under resonant excitation into N_(x) band,strong Raman lines involving allowed LO and "forbidden" TO for badkscattering coniiguration from(100)surface are observed.This is interpreted as the breakdown of normal selection rule in the RRS process.By following the temperature dependence of the N_(x)luminescence and its phonon sidebands,we also separate RRS from sharp line due to luminescence.
文摘A simple extension of the standard model(SM) with a μ-flavored vector-like lepton(VLL) doublet and a real singlet scalar can have an interesting implication to the h→μ^(+)μ^(-)decay while offering the simplest possible explanation for the dark matter(DM) phenomenology.Assuming the real singlet scalar to be a viable DM candidate,it has been shown that the muon Yukawa coupling can have a negative contribution at the oneloop order if the 2^(nd) generation SM leptons are allowed to couple with the VLL doublet.The stringent direct detection bounds corresponding to a real singlet scalar DM can easily be relaxed if the SM quark sector was augmented with a dimension-6 operator at some new physics(NP) scale Λ_(NP).Thus,this model presents a significant phenomenological study where the muon Yukawa coupling can be corrected within a real singlet scalar DM framework.The considered parameter space can be tested/constrained through the high luminosity run of the LHC(HL-LHC) and future direct detection experiments.
基金Supported by the National Natural Science Foundation of China under Grant No.19875084.
文摘Based on an analysis of the inherent nodal structures of wave functions of 4-boson systems,we found that the internal energy of the 4_(1)^(+) state should be lower because its structure can be optimized without suffering a strong constraint arising from symmetry(while other 1≤L≤3 states suffer from this kind of constraints).Furthermore,two superior structures favorable in binding are found to be allowed to be possessed by 4^(+) states.These findings would lead to the appearance of two adjacent 4^(+) states,as a common feature,in the low-lying spectra of 4 boson systems.
基金Project supported by the State Key Development Program for Basic Research of China （Grant No 2004CB719800）, partially by the National Natural Science Foundation of China （Grant No 10604046） and the Chinese Doctoral Science Foundation.
文摘A new quantum optical mechanism to realize simultaneously negative electric permittivity and magnetic permeability is suggested. In order to obtain a negative permeability, we choose a proper atomic configuration that can dramatically enhance the contribution of the magnetic-dipole allowed transition via the atomic phase coherence. It is shown that the atomic system chosen with proper optical parameters can give rise to striking electromagnetic responses （leading to a negative refractive index） and that the atomic vapour becomes a left-handed medium in an optical frequency band. Differing from the previous schemes of artificial composite metamaterials （based on classical electromagnetic theory） to achieve the left-handed materials, which consist of anisotropic millimetre-scale composite structure units, the left-handed atomic vapour presented here is isotropic and homogeneous at the atomic-scale level. Such an advantage may be valuable in realizing the superlens （and hence perfect image） with left-handed atomic vapour.
