关节臂式坐标测量机空间误差建模

关节臂式坐标测量机误差源多且复杂,其测量空间的误差存在不确定性,为了准确快速的得到关节臂式坐标测量机测量空间中的误差,利用标准锥窝对关节臂式坐标测量机进行了空间单点测量精度实验,获得了训练样本和测试样本。利用BP神经网络对空间误差进行了建模,为了提高其收敛速度和运算速度,引入粒子群优化算法(PSO)对BP神经网络模型进行了优化,并对模型进行了预测和验证。结果表明,BP神经网络和PSO-BP神经网络都可以对关节臂式坐标测量机进行空间点误差预测,PSO-BP神经网络模型的预测结果更加精确,相对误差更小。     

混合阳离子固相萃取净化结合UPLC-MS/MS测定蘑菇及生物样本中鹅膏肽类毒素

建立了一种混合阳离子固相萃取净化结合超高效液相色谱串联质谱法(UPLC-MS/MS)测定蘑菇、尿液及血浆中α-鹅膏毒肽、β-鹅膏毒肽、γ-鹅膏毒肽、二羟鬼笔毒肽和羧基二羟鬼笔毒肽的方法。对于蘑菇样本,烘干粉碎后纯水超声提取,经混合阳离子柱(MCX)净化;对于尿液和血浆样本,乙腈提取后,经PRi ME MCX柱净化。净化的样本以甲醇和5 mmol/L甲酸铵水溶液为流动相,在ACQUITY UPLC BEH C₁₈色谱柱上进行分离,电喷雾正离子多反应监测(MRM)模式检测,基质匹配外标法定量。结果表明,5种鹅膏肽类毒素在0.5～1000μg/L范围内均呈良好的线性关系,相关系数R²>0.999。方法检出限为0.1～0.5μg/kg(μg/L),定量限为0.5～1.0μg/kg(μg/L);3个加标浓度下的平均回收率为79.1%～103.5%,相对标准偏差(RSD)为0.2%～9.6%。该方法适用于含鹅膏毒肽蘑菇中毒的确证与临床诊断。     

UPLC-Q-Orbitrap HRMS法筛查动物肌肉组织中16种琥珀酸脱氢酶抑制剂类杀菌剂

应用超高效液相色谱-四极杆/静电场轨道阱高分辨质谱(UPLC-Q-Orbitrap HRMS)建立了筛查动物肌肉组织中16种新型琥珀酸脱氢酶抑制剂类杀菌剂农药残留的方法。样品使用乙腈提取,乙二胺-N-丙基硅烷(PSA)、十八烷基键合硅胶(C₁₈)净化处理,数据采集使用一级母离子全扫描及数据依赖的二级子离子扫描(Full MS/dd-MS²)模式。以Full MS一级质谱全扫描提取母离子精确质量数所得的色谱峰面积进行定量,以保留时间和dd-MS²数据依赖子离子扫描所得的二级子离子质谱图进行定性确证。结果表明,16种杀菌剂的精确质量偏差的绝对值低于4.85×10^-6;16种杀菌剂在一定质量浓度范围内线性关系良好(R²≥0.9983),方法检出限为0.12～0.60μg/kg,平均回收率为67.1%～111.9%,相对标准偏差(RSDs)为0.3%～12%。     

柱面扁壳的非线性数值分析

本文研究了柱面扁壳在均布荷载作用下的大变形弯曲问题。首先导出了位移型非线性控制微分方程,然后结合两种边界情况(简支与固定)给出了用正交配点法进行解算的详细公式。     

A density-wave-like transition in the polycrystalline V3Sb2 sample with bilayer kagome lattice

Recently,transition-metal-based kagome metals have aroused much research interest as a novel platform to explore exotic topological quantum phenomena.Here we report on the synthesis,structure,and physical properties of a bilayer kagome lattice compound V₃Sb₂.The polycrystalline V₃Sb₂ samples were synthesized by conventional solid-state-reaction method in a sealed quartz tube at temperatures below 850℃.Measurements of magnetic susceptibility and resistivity revealed consistently a density-wave-like transition at Tdw≈160 K with a large thermal hysteresis,even though some sample-dependent behaviors were observed presumably due to the different preparation conditions.Upon cooling through Tdw,no strong anomaly in lattice parameters and no indication of symmetry lowering were detected in powder x-ray diffraction measurements.This transition can be suppressed completely by applying hydrostatic pressures of about 1.8 GPa,around which no sign of superconductivity was observed down to 1.5 K.Specific-heat measurements revealed a relatively large Sommerfeld coefficientγ=18.5 mJ·mol^-1·K^-2,confirming the metallic ground state with moderate electronic correlations.Density functional theory calculations indicate that V₃Sb₂ shows a non-trivial topological crystalline property.Thus,our study makes V₃Sb₂ a new candidate of metallic kagome compound to study the interplay between density-wave-order,nontrivial band topology,and possible superconductivity.     

Improved thermal property of strained InGaAlAs/AlGaAs quantum wells for 808-nm vertical cavity surface emitting lasers

The 808-nm vertical cavity surface emitting laser (VCSEL) with strained In_0.13Ga_0.75Al_0.12As/Al_0.3Ga_0.7As quantum wells is designed and fabricated. Compared with the VCSELs with Al_0.05Ga_0.95As/Al_0.3Ga_0.7As quantum wells, the VCSEL with strained In_0.13Ga_0.75Al_0.12As/Al_0.3Ga_0.7As quantum wells is demonstrated to possess higher power conversion efficiency (PCE) and better temperature stability. The maximum PCE of 43.8% for 10-μm VCSEL is achieved at an ambient temperature of 30 ℃. The size-dependent thermal characteristics are also analyzed by characterizing the spectral power and output power. It demonstrates that small oxide-aperture VCSELs are advantageous for temperature-stable performance.     

Impact of back-gate bias on the hysteresis effect in partially depleted SOI MOSFETs

The hysteresis effect in the output characteristics, originating from the floating body effect, has been measured in partially depleted (PD) silicon-on-insulator (SOI) MOSFETs at different back-gate biases. I_D hysteresis has been developed to clarify the hysteresis characteristics. The fabricated devices show the positive and negative peaks in the I_D hysteresis. The experimental results show that the I_D hysteresis is sensitive to the back gate bias in 0.13-μm PD SOI MOSFETs and does not vary monotonously with the back-gate bias. Based on the steady-state Shockley--Read--Hall (SRH) recombination theory, we have successfully interpreted the impact of the back-gate bias on the hysteresis effect in PD SOI MOSFETs.     

X波段3GW高功率微波辐射喇叭的设计

依据数值模拟结果研制了一套X波段多模微波喇叭,采用3次变张角喇叭结构,设计要求辐射功率大于3 GW,E面和H面方向图在10 dB范围内等化度良好,10 dB波束宽度为40°。近场冷测结果表明,H面10 dB波束宽度为43°,E面10 dB波束宽度为40°。远场热测结果表明,H面10 dB波束宽度为40°,E面10 dB波束宽度为41°,在初步测试中,通过对比在线测量结果和辐射场测量结果,证明研制的喇叭输出功率达1.3 GW时不会出现击穿现象。     

二维几何的引力场及若干形式相似性问题

对于球对称的质量分布,牛顿证明了球壳定理.对二维几何的分布质量则不存在对应的规律.对圆环、圆盘的情形作了简练的解析计算,并精细作图将圆盘的径向场与圆球作比较.讨论了二维几何下引力场、静电场和磁场的形式相似性以及它们的物理或数学相似来源.     

从微观角度再看理想气体的绝热过程

在“ 从微观角度看理想气体的绝热过程”一文中提到了一种从微观角度来计算理想气体绝热公式的推 导, 这一推导中的物理本质为气体分子对活塞壁做功的集体效应, 即气体压强的微观解释. 基于这一思考, 从气体 分子对外做功的角度给出了相应的推导, 同时发现该文结论在其给定模型下的一个更为直观的解, 与热力学第一 定律中的做功项可以更直接地对应, 从而更直接地联系起微观过程和宏观的理想气体状态方程