梁柱简化模型在自立塔塔线体系动态响应中的适用性研究

对输电塔进行合理简化可以提高塔线体系动力学仿真的效率。本文给出自立塔梁柱简化模型的计算方法，并提出利用梁柱简化模型计算方法建立自立塔塔线体系整体模型，同时采用桁梁混合模型建立精细化塔线体系整体模型，对两种模型塔线体系静力特性及振型和固有频率等动力特性进行对比分析。以脱冰工况为例，采用生死单元技术将施加在输电线节点上的集中质量单元杀死来模拟脱冰，实现对塔线体系动力学响应的有限元模拟，研究塔线体系简化模型在动态响应中的适用性。结果表明，两种模型弯曲变形误差小，低阶的振型相同，固有频率值误差小，动力特性基本相同；脱冰工况下，自立塔节点位移和塔材内力时程曲线一致，在提高计算效率的情况下，能有效保证计算精度。     

频闪及Matlab技术验证机械能守恒实验装置

利用摄像头频闪技术及Matlab软件组装了一个利用单摆验证机械能守恒的实验装置,主要解决学生在缺乏打点计时器的情况下,利用简便设备进行探究的难题,并将验证推广到二维.利用数据采集量大的优点,解决了传统实验只能验证机械能相等而不能验证机械能守恒的问题.     

浅谈在线课程中的“作弊”及应对策略

2020年春季学期各高等院校均采用在线教学保证停学不停课,在线课程的教学和考试暴露了一些新的问题,教师面临着全新的挑战.文章通过问卷调查,统计考察了学生对在线考试的看法,以及考试中作弊的预期和常见作弊方式,结合开展在线教育较早的欧美研究结果探讨了预防和减少作弊的方法和思路.提出应在激发学生学习兴趣的基础上,建立学术诚信意识,降低作弊冲动.在疫情后的教学活动中,结合线上线下教学各自的优势,改变考核与评分方式,对学生整个学习过程进行考核,全面反应学生学习成果.     

Simulation and analysis of 13N+p elastic resonance scattering

The ^13 N＋p elastic resonance scattering has been studied at the secondary radioactive beam facility of CIAE in inverse kinematics via a thick-target method. The excitation function for the ^13N（p,p） scattering was obtained in the energy interval of Ecru ≈0.5-3.2 MeV with a ^13 N secondary beam of （47.8±1.5） MeV. Careful analysis of the secondary beam components and extensive Monte-Carlo simulations enable the resolution of the experimental proton spectra. The resonance parameters for five low-lying levels in ^14 O were deduced by Rmatrix fitting calculations with MULTI7 and SAMMY-M6-BETA. The present results show general agreement with those from a recent similar work, and thus confirm the observation of a new 0^- level at 5.7 MeV in 140 with an improved width of 400（45） keV.     

Measurements of stellar and explosive nuclear astrophysics reactions

This paper described the nuclear astrophysical studies using the unstable ion beam facility GIRAFFE in CIAE, by indirect measurements. We measured the angular distributions for some single proton or neutron transfer reactions, such as ⁷Be(d,n)⁸B, ¹¹C(d,n)¹²N, ⁸Li(d,p)⁹Li and ¹³N(d,n)¹⁴O in inverse kinematics, and derived the astrophysical S-factors or reaction rates of ⁷Be(p,γ)⁸B, ¹¹C(p,γ)¹²N, ⁸Li(n,γ)⁹Li, ¹³N(p,γ)¹⁴O by asymptotic normalization coefficient, spectroscopic factor, and R-matrix approach at astrophysically relevant energies. Some most recent progress of nuclear astrophyiscal work in CIAE are also summarized.     

Breakdown characteristics of AIGaN/GaN Schottky barrier diodes fabricated on a silicon substrate

In this work, the breakdown characteristics of AlGaN/GaN planar Schottky barrier diodes （SBDs） fabricated on the silicon substrate are investigated. The breakdown voltage （BV） of the SBDs first increases as a function of the anodeto-cathode distance and then tends to saturate at larger inter-electrode spacing. The saturation behavior of the BV is likely caused by the vertical breakdown through the intrinsic GaN buffer layer on silicon, which is supported by the post-breakdown primary leakage path analysis with the emission microscopy. Surface passivation and field plate termination are found effective to suppress the leakage current and enhance the BV of the SBDs. A high BV of 601 V is obtained with a low on-resistance of 3.15 mΩ·cm^2.     

含钆对比剂的环境污染现状、毒性及分析方法

随着医疗技术的发展,药品和个人护理产品(PPCPs)因其在全世界范围内的大量使用,受到了越来越多的关注,含钆对比剂(GBCAs)可归属于这类化学品。许多造影剂在医疗诊断中被广泛使用以提高医学成像质量,大量的造影剂经生产、使用等过程释放至环境,成为新型环境污染物,对环境及生态造成影响,其中含钆对比剂便是其中一大类。GBCAs在体内几乎无代谢,而废水处理厂的传统工艺无法将其有效去除,造成该类物质进入水环境中,存在潜在环境风险。该文综述了目前含钆对比剂的分类、环境污染、生物毒性研究现状及分析检测方法,可为含钆对比剂的风险评价研究提供参考。     

Valen席夫碱单核铜配合物的合成、热化学性质及其对粟酒裂殖酵母细胞作用的热动力学研究

以甲醇为溶剂,邻香草醛缩乙二胺席夫碱(H2vanen)与一水合醋酸铜[Cu(OAc)2·H2O]反应,合成了一种Valen席夫碱单核铜配合物[Cu(vanen)(H2O)].以盖斯定律为理论基础,设计了一个合理可行的热化学循环.根据该热化学循环,依次测定了各样品的标准摩尔溶解焓,进而求得配位反应的标准摩尔反应焓(θr m?H)为?(16.61±0.54)kJ/mol.再结合其他相关的文献值,求得配合物的标准摩尔生成焓(θf m?H)为?(756.5±2.4)kJ/mol.在32℃条件下,用热导式等温微量热仪测定了不同浓度配合物作用下粟酒裂殖酵母细胞的产热曲线,探讨了不同浓度的配合物对酵母菌生长的影响,分析了配合物的浓度与酵母菌代谢的生长速率常数k、抑制率I、最大发热功率Pmax、半抑制浓度IC50以及达到最大发热功率所需时间tmax等动力学参数之间的关系.分析结果表明,配合物对粟酒裂殖酵母细胞的生长具有低浓度促进、高浓度抑制的Hormesis效应.     

Enhancement of β^＋-Decay Rate of ^22Na in Metal Pd at Low Temperature

Temperature dependence of nuclear decays in metallic environments is a controversial issue. We measured the temperature dependence of the β^＋-decay half-life of ^22Na implanted into the metal host of palladium. It is found that the β^＋-decay half-life of ^22Na in the metal Pd cooled to T = 15 K is shorter by 0.46（14）% than that at room temperature. The result is consistent in sign with, but dearly smaller than, the estimated one by the Debye model.     

有趣的正弦平方差公式

苏教版必修4第99页上有这样一道习题:"求证:sin(α+β)sin(α-β)=sin2α-sin2β".这个公式形式优美,与平方差公式(a+b)(a-b)=a2-b2的结构十分相似,体现了数学的形