Synthesis and characterization of C3N4 hard films

C3N4 films have been synthesized on both Si and Pt substrates by microwave plasma chemical vapor deposition (MPCVD) method. X-ray spectra were calculated for single phase α-C3N4 and β-C3N4 respectively. The experimental X-ray spectra of films deposited on both Si and Pt substrates showed all the strong peaks of α-C3N4 and β-C3N4, so the films are mixtures of α-C3N4 and β-C3N4. The N/C atomic ratio is in the range of 1.0-2.0. X-ray photoelectron spectroscopy (XPS) analysis indicated that the binding energy of C 1s and N 1s are 286.2 eV and 399.5 eV respectively, corresponding to polarized C-N bond. Fourier transform infrared absorption (FT-IR) and Raman spectra support the existence of C-N covalent bond in the films. Nano-indentation hardness tests showed that the bulk modulus of a film deposited on Pt is up to 349 GPa.     

Teleportation of N-Particle Entangled GHZ State via Entanglement Swapping

In this scheme, N non-maximally entangled particle pairs are used as quantum channel to teleport an unknown N-particle entangled GHZ state via entanglement swapping. In order to realize this teleportation, the sender Alice operates Bell-state measurement on particles belonging to herself. Then she informs the results to the receiver Bob through classical communication. According to the results, Bob operates corresponding transformation to reconstruct the initial state. The advantage of this scheme is that it needs only one common unitary matrix for Alice＇s different results, which has a more general meaning. As a special case, teleporting an unknown three-particle entangled GHZ state is proposed.     

考虑员工疲劳度和休假的退化系统可靠性建模与检测策略研究

在退化系统检测维修策略的研究中,很少考虑人为因素对检测正确率的影响。事实上,考虑员工疲劳度水平和其工作状态可以更精确地评估和优化维修检测策略,帮助企业降低运维成本。本文考虑维修工的工作状态对检测结果的影响,通过建立疲劳度和检测正确率的函数关系,构建检测维修模型,以最小化维修成本为目标,优化员工工作时间安排、休假时间安排以及检测时间间隔;最后进行算例分析,针对各成本参数做敏感度分析,讨论参数变化时最优休假策略和维修策略的变化规律,从而寻找更广泛的优化适用性。结果表明检测出错成本大的系统,决策者应提高员工休假时间,降低检测频率;预防性维修成本高的系统,决策者应适当提高员工在岗时间并降低检测频率;停机机会成本更高的系统应提高员工在岗时间,同时提高检测频率。     

Stimulated emission and multi-peaked absorption in a four level N-type atom

Absorption and refraction of the inner transition F₂\leftrightarrow F₃ of the closed four level N-type atom have been investigated under a weak field. The outer transitions F₁\leftrightarrow F₃ and F₂\leftrightarrow F₄ are resonantly interacted with drive field with frequency \omega_c and Rabi frequency \Omega_c, and saturation field with \Omega_s and \Omega_s, respectively. For the suitable Rabi frequencies \Omega_c and \Omega_s, we obtain the Mollow absorption spectrum of probe field. The reason is that the drive field excites the atom to the upper level F_c and simultaneously the saturation field takes the atom out of the lower level F₂, leading to the stimulated emission. Meanwhile, due to the dynamic energy splitting induced by the drive and saturation fields, the two- and four-peaked absorption spectra are observed. At the zero off-resonance detuning of probe field, we also find the transfer of dispersion from negative to positive with an increment of \Omega_s. Finally, the refractive index enhancement is predicted for a wide spectral region.     

一类热传导问题源项识别的快速稳定算法

利用正算子的性质和Lax-Milgram定理,将一维热传导方程源项识别问题转化为适定的、第二类Volterra方程的求解,给出一个新的快速稳定算法,并进行理论分析.采用两种实现后验准则的新途径,在输入数据的误差水平已知和未知的情况下,快速地决定正则参数.数值实验证实了算法的有效性.     

组织策略在化学教学中的运用

由于缺乏应有的组织,学生头脑中的化学知识往往处于无序状态的堆积方式,这种无序状态堆积的知识不但不易贮存,在需要使用时也难以被充分激活。因此,在化学教学中教师要运用好组织策略,帮助学生把握知识的内在联系,归纳知识纲目要点,建构知识网络。     

试谈新课标下的初中化学命题策略

按照新课程的评价理念,通过命题实例,以命题涉及的范围为视角,探索了初中化学“紧扣基础,灵活多变;重视过程,考查方法;渗透人文,强化教育;源于生活,注重联系;模仿探究,体验活动;开放创新,张扬个性;运用史料,验证假设;提供事实,分析综合”的8项命题策略。     

化学复习课中问题优化策略的研究

化学复习课是以巩固所学知识并提高运用知识解决实际问题的能力为主要任务的一种课型。本文根据化学复习课的课型特征,提出问题优化策略是行之有效的化学复习策略,结合自己的教学实践,从问题选择、问题呈现、问题拓展这3个方面探索化学基础理论与化学计算复习课的教学策略,促进学生化学思维能力的提高。     

化学问题解决的心理机制及常用策略

本文从识别问题、表征问题、寻求解答、尝试解答、检验反思等方面分析了化学问题解决的心理机制,并针对问题表征、尝试解答、检验反思提出了常用的策略。     

氯化稀土催化ε-己内酯开环聚合

Ring-opening polymerization of ε-caprolactone catalyzed by rare earth chloride dissolved in N,N-dimethylformamide and adding a small amount of propylene oxide was studied.The optimum conditions for the ring-opening polymerization of CL are as follows.In the bulk polymerization: n(DMF)/n(LaCl₃)=10,n(PO)/n(LaCl₃)=20,aging temperature: 30 ℃,aging time: 1 h,c(CL)=7.91×10^-3 mol/L,c(LaCl₃)=1.58×10^-5 mol/L,the polymerization carried out at 30 ℃ for 1 h,yield=83.3%,M_ν=1.93×10⁴.In the solution polymerization: n(DMF)/n(LaCl₃)=10,n(PO)/n(LaCl₃)=20,aging temperature: 30 ℃,aging time: 1 h,toluene as the solvent,c(CL)=4.22×10^-3 mol/L,c(LaCl₃)=8.43×10^-6 mol/L,the polymerization was carried out at 30 ℃ for 2 h,yield=62.9%,M_ν=1.21×10⁴.