HIRFL与CSR的匹配研究

国家重大科学工程HIRFLCSR冷却储存环计划主环CSRm利用已有的HIRFL作为注入器,为了更好地利用HIRFL加速器的能力,对这两台加速器的匹配在原来的初步考虑的基础上进行了较为详细的研究,提出了分别利用HIRFL自己的注入器SFC单独注入到CSR以及SFC加上主加速器SSC注入到CSR的两套方案,既可以提高HIRFL与CSR的总传输效率,又可以在SFC与CSR联合运行的同时使SSC与另建的小回旋加速器组合加速质子,从而充分提高HIRFL的运行效率.     

241Am-Be中子参考辐射的蒙特卡罗模拟研究

研究用于校准场所中子剂量监测仪表的241Am-Be中子参考辐射场计量特性。采用蒙特卡罗方法模拟了空气自由中子参考辐射(FRNR),GB/T 14055规定的最小尺寸中子参考辐射(SRNR)和实际中子参考辐射(ARNR)中不同检验点处中子周围剂量当量率、散射中子占比和能谱分布特征。研究结果表明,空气对FRNR中的剂量率和能谱分布影响小,近似为理想中子参考辐射;采用5%含硼聚乙烯作屏蔽的最小尺寸SRNR可减少热中子,降低散射中子占比,影锥法不适用于小尺寸中子参考辐射中对散射中子的修正;ARNR中的散射中子更少、占比更低,影锥法所得散射中子占比与理论值基本一致。     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

基于改进的压缩式随机游走算法对静态电源/地网的模拟

将随机游走法和等效电路压缩相结合,对静态P/G网(Power and Ground Networks)进行分析.针对一个大规模的电路,在经过多层的参数提取和建模后,得到静态P/G网模型.首先根据网络的规律性,运用等效电路压缩法将原始的P/G网进行压缩处理,然后运用随机游走法求解,最后利用计算得到的化简网络电压值,通过相关的插值公式得到原网络的电压值.实验数据表明,改进的压缩式随机游走法可有效简化网络的复杂性,节省计算时间,计算速度提高到普通随机游走法的两个数量级以上.     

Contact between two plastically deformable crystals: a discrete dislocation dynamics study

It is customary to simplify the analysis of contact between two elastically deformable bodies by treating an equivalent problem where only one body is deformable and the other is rigid. This is possible provided that the gap geometry and the effective elastic modulus of the bodies in the simplified problem are the same as in the original problem. However, the question arises on whether – and to which extent – the simplification is still valid even when (size-dependent) plasticity occurs. Studies using discrete dislocation plasticity have also, so far, addressed simple contact problems where only one body can deform plastically. Here, we extend the analysis to two bodies in contact that can both deform by dislocation plasticity and investigate under which conditions the response agrees with that of an equivalent simplified problem. The bodies in contact are metal single crystals with sinusoidal and flat surface. It is found that the response of two plastically deformable bodies in contact can be simplified to an equivalent problem where one body is rigid and the other can deform plastically. Also, a plasticity size effect is observed, but the effect fades when the platen becomes more plastically deformable.     

Band bending at the conducting polymer/indium tin oxide interfaces with and without ultraviolet treatment

In this study, the effect of ultraviolet treatment on the band bending at the poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate)/indium tin oxide (PEDOT:PSS/ITO) interfaces were researched. The authors suggested that ultraviolet treatment could lead to a reduction in the band bending at the PEDOT:PSS/ITO interface, owing to the removal of carbon contamination at the ITO surfaces and a decrease in the number of the trap-states at the PEDOT:PSS/ITO interface.     

Load’s temporal characteristics for annulling forced vibrations of linear elastic plates

We consider trapezoidal load-time pulses with linearly increasing and affinely decreasing durations equal to integer multiples of the time period of the first bending mode of vibration of a linearly elastic structure. For arbitrary spatial distributions of loads applied to monolithic and laminated orthotropic plates, it is shown through numerical solutions that plates’ vibrations become miniscule after the load is removed. This phenomenon is independent of the dwell time (i.e., the time duration between the rising and the falling portions) during which the load is kept constant. The primary reason for this response is that for such time-dependent loads, nearly all of plate’s strain energy is concentrated in deformations corresponding to the fundamental bending mode of vibration. Thus plate’s deformations can be studied by taking the mode shape of the 1st bending mode as the basis function and reducing the problem to that of solving a single second-order ordinary differential equation. We have verified this postulate by comparing strain energies computed from the 3-dimensional deformations of different plate geometries and boundary conditions with those determined by using the single degree of freedom (DoF) model. Thus for trapezoidal time-dependent loads applied on plates, the 1 DoF model provides reasonably accurate results and saves considerable computational effort.     

LOCAL BENDING OF THIN FILM ON VISCOUS LAYER

Effects of deposition layer position film are systematically investigated. Because the and number/density on local bending of a thin deposition layer interacts with the thin film at the interface and there is an offset between the thin film neutral surface and the interface, the deposition layer generates not only axial stress but also bending moment. The bending moment induces an instant out-of-plane deflection of the thin film, which may or may not cause the socalled local bending. The deposition layer is modeled as a local stressor, whose location and density are demonstrated to be vital to the occurrence of local bending. The thin film rests on a viscous layer, which is governed by the Navier-Stokes equation and behaves like an elastic foundation to exert transverse forces on the thin film. The unknown feature of the axial constraint force makes the governing equation highly nonlinear even for the small deflection chse. The constraint force and film transverse deflection are solved iteratively through the governing equation and the displacement constraint equation of immovable edges. This research shows that in some special cases, the deposition density increase does not necessarily reduce the local bending. By comparing the thin film deflections of different deposition numbers and positions, we also present the guideline of strengthening or suppressing the local bending.     

Chain Conformation and Local Rigidity of Soluble Polyimides(Ⅱ): Isomerized Polyimides in THF

Two soluble isomerized polyimides(PIs)synthesized from 2,2′-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride(6FDA)with either 2,2′-dimethylbenzidine(2,2′-DMB)or 3,3′-DMB were investigated by means...     

光纤弯曲损耗特性的理论与实验研究

为了减小在长距离光纤通信中存在的弯曲损耗和利用光纤激光器中的弯曲损耗获得单模输出，利用速度法解释了光纤弯曲损耗机制，采用Marcuse理论研究了弯曲损耗随弯曲半径、波长和纤芯半径变化的关系。通过计算机仿真和实验得出弯曲损耗随弯曲半径的减小而增大，随波长的增大而增大，随纤芯半径的增大而增大，高阶模式的损耗大于低阶模式。利用这一结论就可以通过控制弯曲半径在临界半径以内来减小通信中的弯曲损耗，通过增大模场半径来实现光纤激光器中的单模输出。