Halogen bonding between substituted chlorobenzene and trimethylamine: Decisive role of σ–hole and C?Cl bond breaking energy

Theoretical studies have been carried out on the halogen bonding interaction between para substituted chlorobenzene (Y C₆H₄Cl, Y = H, NH₂, CH₃, F, CN, NO₂) and N(CH₃)₃ using ab initio MP2/aug‐cc‐pVDZ and DFT based wB97XD/6‐311++G(d,p) methods. The positive electrostatic potential (V_S,max) on the Cl atom and the heterolytic bond breaking enthalpy of the C Cl bond have been calculated and their role on halogen bonding is discussed. The heterolytic bond breaking enthalpy of the C Cl bond is proposed as a measure of the strength of the σ‐hole on Cl atom. The binding strength of the complexes ranging between −6.13 kJ mol⁻¹ and −9.29 kJ mol⁻¹ are linearly related to the V_S,max of the Cl atom and the bond breaking enthalpy of the C Cl bond. In addition, energy decomposition analysis was performed on the halogen bonded complexes via symmetry adapted perturbation theory (SAPT) to predict the dominant energy component and the nature of the N···Cl interaction.     

增损比对激光陀螺影响的研究

光强调谐曲线是激光陀螺工作模式选取和稳频的依据,而陀螺的增损比将直接决定光强调谐曲线的形式.为了提高陀螺准确度,本文对双同位素综合展宽情况下二频激光陀螺出光带宽与增损比之间的关系进行了分析计算,结果表明,激光陀螺的出光带宽与增损比之间存在单调递增的变化关系.数值仿真了不同增损比情况下陀螺的光强调谐曲线,结果表明,根据激光陀螺出光带宽与相邻纵横间隔相对大小的不同,其光强调谐曲线的形状可分三种,仿真与试验结果非常吻合.分析并试验验证了增损比选取不当对激光陀螺工程化应用可能产生的影响,给出了不同腔长情况下激光陀螺增损比合理选取的参考值,即应保证陀螺的出光带宽约等于其相邻纵横间隔.     

Automatically improving the anytime behaviour of optimisation algorithms

Optimisation algorithms with good anytime behaviour try to return as high-quality solutions as possible independently of the computation time allowed. Designing algorithms with good anytime behaviour is a difficult task, because performance is often evaluated subjectively, by plotting the trade-off curve between computation time and solution quality. Yet, the trade-off curve may be modelled also as a set of mutually nondominated, bi-objective points. Using this model, we propose to combine an automatic configuration tool and the hypervolume measure, which assigns a single quality measure to a nondominated set. This allows us to improve the anytime behaviour of optimisation algorithms by means of automatically finding algorithmic configurations that produce the best nondominated sets. Moreover, the recently proposed weighted hypervolume measure is used here to incorporate the decision-maker’s preferences into the automatic tuning procedure. We report on the improvements reached when applying the proposed method to two relevant scenarios: (i) the design of parameter variation strategies for MAX-MIN Ant System and (ii) the tuning of the anytime behaviour of SCIP, an open-source mixed integer programming solver with more than 200 parameters.     

Flexible broadcasting and multicasting in 4λ × 10 Gb/s AOPR TWDM PON system

In this letter, we propose a new architecture of Time Wavelength Division Multiplexing Passive Optical Network (TWDM PON) system to support dynamic multi wavelength allocation (DMWA) in both upstream and downstream directions using an integrated semiconductor optical amplifier (SOA) and arrayed waveguide grating (AWG) with multi wavelength select continuous wave (CW) pump probe signal module. The significance of this architecture is the flexible routing function with the capability of multicasting and broadcasting between multiple optical line terminal (OLT) PON port with multiple optical distribution network (ODN) link using a new wavelength tuning free (WTF) OLT transmitter module to eliminate wavelength tuning delay in downstream signal utilizing multicasting Cross Gain Modulation (XGM) wavelength conversion. The experimental results show that 4λ × 10-Gb/s TWDM PON system can be used to connect 4096 users with the conventional fixed wavelength OLT transceivers with 36 dB link loss.     

调谐兰姆波在模态控制中的实验研究

兰姆波模态调谐是指在确定的压电传感器条件下,通过频率选择实现单一兰姆波模态检测的方法.本文在兰姆波模态调谐的理论指导下,实现了单一兰姆波模态激励和调控.同时,研究了实验条件,如粘接剂性能和传感器上粘结位置对兰姆波调谐模态控制的影响.结果表明,对于不同的粘接剂,固化后硬度越高,其实验结果与理论结果的一致性越好;对于同一种粘接剂,边缘位置的粘贴会使非对称模态应力幅值增大,从而对模态调控的实现造成一定的影响.     

推导纵向相对论多普勒效应的新方法

基于狭义相对论的洛伦兹变换和同时的相对性,本文给出了一个推导长度收缩和纵向相对论多普勒效应的新方法。该方法可更直观理解在两个惯性系中观测一个纵向光波的波长与观测沿纵向静止于某个系中杆的长度的本质区别。     

基于LabVIEW的He-Ne激光器综合实验系统

基于LabVIEW软件和数据采集卡设计了激光器综合实验系统,可实现对激光器谐振腔长调谐的自动、远程、精密的控制,并具有对输出光强信号进行实时显示、存储、读取和处理的功能,同时将频率分裂、模竞争和光强调谐实验相结合.     

自抗扰控制器在位置伺服系统中的参数整定及仿真应用

本文基于MATLAB/Simulink软件设计了自抗扰控制器,结合永磁同步电机控制系统各模块结构,实现了位置伺服系统的闭环仿真,利用仿真输出及时间、参数值绘制三维图象,通过对图象的分析验证了参数整定的新方法,实现了自抗扰控制器的参数整定。通过自抗扰和PI控制器的多组实验,对比了两种控制器在恒值、正弦、斜坡等给定输入下的跟踪效果,突出了自抗扰控制器的优势。最后,本文分析了自抗扰控制器的发展趋势,为自抗扰算法的进一步应用提供一定依据。