Precision Higgs physics at the CEPC

The discovery of the Higgs boson with its mass around 125 GeV by the ATLAS and CMS Collaborations marked the beginning of a new era in high energy physics.The Higgs boson will be the subject of extensive studies of the ongoing LHC program.At the same time,lepton collider based Higgs factories have been proposed as a possible next step beyond the LHC,with its main goal to precisely measure the properties of the Higgs boson and probe potential new physics associated with the Higgs boson.The Circular Electron Positron Collider(CEPC)is one of such proposed Higgs factories.The CEPC is an e~+e~- circular collider proposed by and to be hosted in China.Located in a tunnel of approximately 100 km in circumference,it will operate at a center-of-mass energy of 240 GeV as the Higgs factory.In this paper,we present the first estimates on the precision of the Higgs boson property measurements achievable at the CEPC and discuss implications of these measurements.     

Compression behavior and phase transition of β-Si_3N_4 under high pressure

The compressibility and pressure-induced phase transition of β-Si_3N_4 were investigated by using an angle dispersive x-ray diffraction technique in a diamond anvil cell at room temperature. Rietveld refinements of the x-ray powder diffraction data verified that the hexagonal structure(with space group P63/m, Z = 2 formulas per unit cell) β-Si_3N_4 remained stable under high pressure up to 37 GPa. Upon increasing pressure, β-Si3 N4 transformed to δ-Si_3N_4 at about 41 GPa. The initial β-Si_3N_4 was recovered as the pressure was released to ambient pressure, implying that the observed pressureinduced phase transformation was reversible. The pressure–volume data of β-Si_3N_4 was fitted by the third-order Birch–Murnaghan equation of state, which yielded a bulk modulus K_0= 273(2) GPa with its pressure derivative K_0= 4(fixed)and K0= 278(2) GPa with K 0= 5. Furthermore, the compressibility of the unit cell axes(a and c-axes) for the β-Si_3N_4 demonstrated an anisotropic property with increasing pressure.     

楞次定律实验验证--电磁炮

本文给出了一种验证楞次定律实验现象的良好方法,可以明显观察到线圈中突然通以电流时产生的电磁冲击力.     

恒温恒湿箱定频制冷压缩机吸气喷液实验研究

极端工况下制冷压缩机排气温度过高是压缩机故障率多的主要原因,为此对采用定频制冷、电加热补偿和电热蒸汽加湿的恒温恒湿箱的12个设定温湿度工况进行试验。结果表明:采用压缩机吸气少量喷液可有效降低压缩机排气温度,从而降低压缩机故障率;而内置式电热蒸汽加湿器在加湿时,由于带入过多热量,且加湿量难以精确调节,易导致加湿滞后性过大。     

基于贝叶斯神经网络的近红外光谱实木地板表面缺陷检测

实木地板的表面缺陷直接影响其力学性能和产品等级,表面缺陷的快速检测对实木地板的在线分选具有重要的现实意义。针对视觉方法检测实木地板表面缺陷识别率低的问题,提出了一种基于近红外光谱分析技术的检测方法。首先,分别采集规格为200 mm×100 mm×20 mm的表面带有活节、死节以及无缺陷的实木地板的光谱数据各60份,其中30份作为训练样本,30份作为测试样本;其次,使用高斯滤波(GSF)、分段多元散射校正(PMSC)和去趋势法(DT)等方法对采集到的光谱数据进行预处理,降低光谱噪声、消除光谱的散射影响;然后,利用改进遗传算法从处理后的光谱中提取特征波长用于构建缺陷识别与分类模型;最后,使用基于贝叶斯理论改进的神经网络构建实木地板缺陷识别和分类模型。实验使用含有活节、死节以及无缺陷的实木地板样本对模型进行训练和测试,结果表明：通过贝叶斯神经网络构建的缺陷识别与分类模型能够准确识别活节、死节和无缺陷三类实木地板,识别率分别为92.20%, 94.47%和95.57%。证明了实木地板表面缺陷类型与其近红外吸收光谱密切相关,并为下一步实现实木地板表面缺陷的准确定位提供快速检测方法。     

一锅法绿色合成烯酰胺和1,3-二炔(英文)

结合绿色化学概念,将酮肟还原酰化和末端炔氧化偶联在一锅进行反应,发展了一种Pd/Cu协同催化一锅绿色合成烯酰胺和1,3-二炔的新方法.该方法无需外加任何氧化剂和还原剂,可同时得到烯酰胺和1,3-二炔,产率高,反应条件温和.     

基于稀疏高斯积分的舰机传递对准滤波方法

针对舰机传递对准中的大姿态失准角问题,研究了稀疏高斯厄米特积分滤波在舰机传递对准中的应用。为了解决稀疏高斯滤波中积分点利用效率不高的问题,提出了一种改进的自适应各向异性稀疏高斯积分滤波算法,改进算法根据状态参数可观测度大小将积分变量分类并根据分类结果构造各向异性权重向量来控制各维通道积分的精度等级,进而对各变量通道的积分点数目进行合理分配。模拟轨迹下仿真结果表明,采用稀疏高斯滤波与采用改进算法的舰机传递对准精度相当,较无味卡尔曼滤波有所提高,对准精度由3?提高到2?;改进算法的积分点数目减少了30%⁶0%,提高了计算效率。     

Rhodamine 6G-doped polymer optical fiber amplifiers

Rhodamine 6G-doped step-index polymer optical fiber is fabricated. The characteristics of the amplification of rhodamine 6G-doped step-index polymer optical fiber amplifier have been studied. The high-gain optical amplification with a tunable wavelength range from 585 to 613 nm is obtained in a step-index polymer optical fiber doped with rhodamine 6G at 10-ppm level, which can be used for broadband amplifiers and tunable lasers.     

基于双光栅成像的RGB模型色彩还原效果的研究

基于双光栅衍射成像的实验方案,利用双光栅的色散和汇合光谱效应特性,用电脑摄像头拍摄作为物体的RGB模型,得到了RGB颜色模型的像。利用Photo shop软件将RGB颜色模型和得到的像进行颜色通道分离,再进行数据化分析处理,探究双光栅的RGB色彩模型色彩还原情况以及不同光栅组合对RGB颜色模型的色彩还原效果的影响。     

pH对两步法非离子模板合成MSU-X类硅基介孔结构的影响

采用两步法以非离子型表面活性剂Tween 20为模板剂合成硅基介孔材料, 研究了pH对介孔材料结构的影响. 结果表明, 没有氟离子存在且模板剂浓度较低(约为2%(w))的条件下, 在弱酸性环境中(pH=3.32-4.26)可以制备有序的MSU-X类硅基介孔材料, 本研究中的简单合成体系有助于查明MSU-X合成机理. 对所得介孔材料测试表明, 在同样的合成体系中, 随着体系pH的变化, 所得硅基介孔材料的形貌和孔壁结构都发生了变化.