NO在稀有金属钇表面的吸附行为

以往的理论在预测六方结构(HCP)金属的表面能时,计算值与实验值存在较大误差.鉴于此,本文首先用一种较为合理的方法精准地预测了稀有金属钇(Y)(0001)面的表面能,计算值(1.141 J/M²)与实验值(1.125 J/M²)吻合的很好.随后,系统研究了NO小分子在Y(0001)面不同位置(空位、桥位和端位)的吸附行为.结果表明:空位(H1)表现出了良好的吸附能力,吸附能超过了5eV,同时N-O键长伸长量超过了24%,此时,NO分子几乎平行地吸附于Y(0001)表面.所有的吸附位置的N-O分子伸长量范围为0.2?-0.42?.这种伸长量明显超过了NO在其它金属表面时的计算结果.     

Memory Effects in High-Dimensional Systems Faithfully Identified by Hilbert–Schmidt Speed-Based Witness

A witness of non-Markovianity based on the Hilbert–Schmidt speed (HSS), a special type of quantum statistical speed, has been recently introduced for low-dimensional quantum systems. Such a non-Markovianity witness is particularly useful, being easily computable since no diagonalization of the system density matrix is required. We investigate the sensitivity of this HSS-based witness to detect non-Markovianity in various high-dimensional and multipartite open quantum systems with finite Hilbert spaces. We find that the time behaviors of the HSS-based witness are always in agreement with those of quantum negativity or quantum correlation measure. These results show that the HSS-based witness is a faithful identifier of the memory effects appearing in the quantum evolution of a high-dimensional system with a finite Hilbert space.     

Comparison Results Between Preconditioned Jacobi and the AOR Iterative Method

The large scale linear systems with M-matrices often appear in a wide variety of areas of physical,fluid dynamics and economic sciences.It is reported in[1]that the convergence rate of the IMGS method,with the preconditioner I S_α,is superior to that of the basic SOR iterative method for the M-matrix.This paper considers the preconditioned Jacobi(PJ)method with the preconditioner P=I S_α S_β,and proves theoretically that the convergence rate of the PJ method is better than that of the basic AOR method.Numerical examples are provided to illustrate the main results obtained.     

Stereoisomeric Tris-BINOL-Menthol Bulky Monophosphites: Synthesis,Characterisation and Application in Rhodium-Catalysed Hydroformylation

Four stereoisomeric monoether derivatives, based on axially chiral (R)- or (S)-BINOL bearing a chiral (+)- or (−)-neomenthyloxy group were synthesised and fully characterised by NMR spectroscopy and X-ray crystallography. The respective tris-monophosphites were thereof prepared and fully characterised. The coordination ability of the new bulky phosphites with Rh(CO)₂(acac), was attested by ³¹P NMR, which presented a doublet in the range of δ = 120 ppm, with a ¹J(¹⁰³Rh-³¹P) coupling constant of 290 Hz. The new tris-binaphthyl phosphite ligands were further characterised by DFT computational methods, which allowed us to calculate an electronic (CEP) parameter of 2083.2 cm⁻¹ and an extremely large cone angle of 345°, decreasing to 265° upon coordination with a metal atom. Furthermore, the monophosphites were applied as ligands in rhodium-catalysed hydroformylation of styrene, leading to complete conversions in 4 h, 100% chemoselectivity for aldehydes and up to 98% iso-regioselectivity. The Rh(I)/phosphite catalytic system was also highly active and selective in the hydroformylation of disubstituted olefins, including (E)-prop-1-en-1-ylbenzene and prop-1-en-2-ylbenzene.     

基于概率密度演化的输电塔-线体系抗风可靠性分析

以三线两塔直线段输电塔-线体系为工程对象,应用有限元数值模拟,建立了基于概率密度演化的输电塔-线体系抗风可靠性分析方法。首先,应用谱表示-降维方法模拟结构脉动风场,生成风荷载的代表性样本集合。然后,结合概率密度演化理论,分析了输电塔-线体系考虑气弹效应的随机动力反应。最后,应用等价极值思想构建了风荷载作用下输电塔-线体系失效准则,进而对输电塔-线体系的抗风可靠性进行精细化分析。本文结合谱表示-降维方法与概率密度演化理论,实现了仅用较少数量的代表性样本来精细地分析结构的抗风可靠性,为工程实践提供参考。     

反射式红外传感器在智能型节水系统中的应用

利用反射式红外传感器和少量的电子器件(单稳态触发器),研制了智能型节水控制系统。该系统能够识别是否有人入厕,酌情产生冲洗信号, 躯动进水电磁阀开启,向浮球式水箱内注水,待注满足以冲刷干净所需的两水箱水后,便自动地切断电磁阀中电源,达到了既卫生又节约的目的。在某一教学楼应用该系统一年多来,与无使用此系统的同规模另一教学楼相比,节水约70％。该系统元件少、成本低、结构合理、工作可靠、安装容易、维修方便,有广阔的应用前景。     

合肥光源慢加速过程中高频系统的调节

合肥光源是一台专用同步辐射光源,它在低能注入积累束流,然后同步地把束流加速到高能并在储存环中稳定运行。在加速过程中,粒子的同步辐射能量损失迅速增加,束流负载效应发生变化,需要相应地调节高频系统参数保持束流稳定。讨论了合肥光源加速过程中高频系统可能的两种高频系统调节方式以及高能情况下高频系统的最佳运行状态。     

A nearly zero temperature gradient furnace system for high pressure multi-anvil experiments

A new furnace system with an almost zero temperature gradient throughout the sample area was designed for multi-anvil high pressure experiments. Test experiments of the new design were performed using 18/11 and 25/15 cell assemblies at 4?GPa, 1400°C and 1500°C, respectively. The temperature field within the sample capsules appeared to be very homogenous as indicated by Mg₂Si₂O₆–MgCaSi₂O₆ two-pyroxene thermometry, by direct temperature measurements using two thermocouples within the same assembly, and by distribution of solid and liquid phases in the sample capsule. The temperature gradient is estimated to be <2.4°C/mm over an area of 4?×?5?mm² within the furnace. It is significantly lower than standard multi-anvil experiments with straight or stepped furnace systems, which are at the levels of 20–200°C/mm.     

The global existence and asymptotic stability of solutions for a reaction–diffusion system

This paper studies the solutions of a reaction–diffusion system with nonlinearities that generalize the Lengyel–Epstein and FitzHugh–Nagumo nonlinearities. Sufficient conditions are derived for the global asymptotic stability of the solutions. Furthermore, we present some numerical examples.     

宽视场长焦距离轴三反射镜光学系统的设计

分析了离轴三反射镜系统成像特性．根据共轴三反射镜光学系统像差理论，确定结构参数的基本计算公式．设计了长焦宽视场的离轴三反射镜光学系统，分析了系统结构参量对像差的影响．结果表明，该系统视角较大，地面复益范围较宽，成像质量接近衍射极限．