基于太赫兹时域光谱技术与PCA-BPN网络的转基因大豆鉴别

基于太赫兹波段内的光谱分析技术以及主成分特性分析与反向前馈神经网络建模,提出了一种转基因大豆鉴别方法.从光谱数据中提取累计方差贡献率达到97.582％的前8种主成分因子,并将其作为输入源导入神经网络模型,通过剔除冗余数据、降低数据维数,所建立的神经网络模型能准确识别校验集.该方法可以实现转基因大豆的快速、无损检测,在农业安全领域有广泛的应用前景.     

基于VPX架构的测控通信综合测试系统设计

针对传统测控通信系统测试设备种类多、数量大、设备间连接关系复杂,难以满足当前型号任务快速、通用、集成的测试需求,提出了一种基于VPX总线架构的测控通信综合测试系统。系统将以往型号测试采用的前端设备、变频设备、基带设备综合集成,以VPX板卡形式集成到一台机箱,利用背板高速串行总线替代传统设备间电缆,显著简化了系统组成,提高测试设备通用性。     

基于C++Builder的换热器性能试验平台测控软件的开发

换热器性能测试是换热器设计过程中的重要环节,对其结构优化及性能评估具有重要作用。针对传统的换热器性能测试系统存在试验周期长、组合方案少,自动化水平不高、可重用应用性较差等不足,文章基于工业控制计算机和C++ Builder软件平台开发了换热器性能试验测控与仿真系统。该系统实现了试验工况参数的控制与过程仿真、试验数据的采集记录与分析处理等各项操作的自动化。文章在简要介绍换热器性能测试系统硬件设计的基础上,具体结合系统硬件介绍了利用C++ Builder制作的换热器仿真实验测控系统的方法及过程,最后给出换热器性能测试仿真实验用户界面及仿真实验运行结果。试验结果表明,测控系统具有交互界面良好、使用方便,可靠性高等特点,能够较好地满足换热器性能测试的要求。     

精密离心机动态半径的定位测量技术研究

精密离心机动态半径是影响精密离心机输出加速度精度的主要参数。对于高精度精密离心机的研制,必须对动态半径进行精密测量,并将测量结果作为补偿分量加入到精密离心机输出加速度修正数学模型中,以获得精确的加速度信号,同时为精密离心机输出加速度的精确评定奠定基础。本文介绍了精密离心机动态半径的外基准定位测试技术,包括多个定位平台的定位测试技术论证、测试系统配置等。该方法已应用于某高精度精密离心机动态半径测量中,实测结果表明,采用这种测量方法,动态半径的测量标准差为σ=0.21μm,其测量精度满足高精度精密离心机研制的技术指标要求。     

测定固体催化剂表面酸碱分布新方法的研究

酸碱催化是一类很重要的催化反应,酸碱强度分布和酸碱反应类型之间有着对应关系,因此,对表面酸碱的测定具有重要的意义。 固体表面酸碱的测定方法很多,常用的是Hammett指示剂酸碱滴定法,但这种方法不能用于测定有色催化剂,神保等研究的Al_2O_3和硅铝上苯酚的升温脱附曲线表明,Al_2O_3上有较强的碱性吸附点。Webb用HF-Al_2O_3吸附NH_3后再脱附并计算表面吸附的NH_3量,认为表面吸附的NH_3多,则表面酸也强,Shirasaki在SiO_2-Al_2O_3上吸附吡啶等气体后,以吸附量x对da/dx(s为吸附热)作图,得到酸碱分布图,Zetllemoyey用吸附热对吸附量的倒数作     

Decoherence–fluctuation relation and measurement noise

We discuss fluctuations in the measurement process and how these fluctuations are related to the dissipational parameter characterizing quantum damping or decoherence. On the example of the measuring current of the variable-barrier or QPC problem we discuss the extra noise or fluctuation connected with the different possible outcomes of a measurement. This noise has an enhanced short time component which could be interpreted as due to “telegraph noise” or “wavefunction collapses”. Furthermore, the parameter giving the strength of this component is related to the parameter giving the rate of damping or decoherence.     

漫透射近红外光谱的便携式面粉品质安全检测仪的设计

基于近红外漫透射光谱分析技术,设计了便携式面粉品质安全检测仪,该检测仪主要包括光谱采集模块、光源控制模块、处理与显示模块以及电源模块.其中漫透射检测附件不仅可以实现光谱补偿功能,还可以有效避免外界杂散光的干扰,设计了控制光源开关的电路,通过实验确定样品的最佳厚度.选用树莓派4B作为核心处理器,选用可充电锂电池供电,仪器...     

高光谱成像的煤与矸石分类

煤与矸石分选是煤矿生产的必要工序,现有的人工分选与机械分选,存在效率低,易造成资源浪费以及环境污染等问题.鉴于可见/近红外高光谱成像具有分析速度快、样品无需预处理、无污染等诸多优势,旨在探讨基于可见/近红外高光谱成像对黑色背景下块状煤与矸石准确分类的可行性,并基于特征波长筛选算法简化模型,为构建多光谱煤与矸石分选系统提...     

Effect of ignition energy on the uncertainty in the determination of laminar flame speed using outwardly propagating spherical flames

The initial propagation processes of expanding spherical flames of CH₄/N₂/O₂/He mixtures at different ignition energies were investigated experimentally and numerically to reduce the effect of ignition energy on the accurate determination of laminar flame speeds. The experiments were conducted in a constant-volume combustion bomb at initial pressures of 0.07???0.7?MPa, initial temperatures of 298???398?K, and equivalence ratios of 0.9???1.3 with various Lewis numbers. The A-SURF program was employed to simulate the corresponding flame propagation processes. The results show that elevating the ignition energy increases the initial flame propagation speed and expands the range of flame trajectory which is affected by ignition energy, but the increase rates of the speed and range decrease with the ignition energy. Based on the trend of the minimum flame propagation speed during the initial period with the ignition energy, the minimum reliable ignition energy (MRIE) is derived by considering the initial flame propagation speed and energy conservation. It is observed that MRIE first decreases and then increases with the increasing equivalence ratio and monotonously decreases with increasing initial pressure and temperature. As the Lewis number rises, MRIE increases. The results also suggest that during the data processing of the spherical flame experiment, the accuracy of determination of laminar flame speeds can be enhanced when taking the flame radius influenced by MRIE as the lower limit of the flame radius range. Then the flame radius influenced by MRIE was defined as RFR. It can also be found that there exist nonlinear relationships between RFR and the equivalence ratio and Lewis number, and the RFR decreases with increasing initial pressure and temperature.     

A method to recover water-wave profiles from pressure measurements

An operational formulation is proposed for reconstructing a time series of water surface displacement from waves using measurements of pressure. The approach is based on the fully nonlinear formulation for pressure below traveling-wave solutions of Euler’s equations developed by Oliveras, Vasan, Deconinck and Henderson. Its validity is tested using experiments in which both the pressure and the surface displacement are measured. The experiments include a wave system that is Galilean invariant – cnoidal waves, and wave systems that are not – reflected cnoidal waves and wave groups. We find that since the proposed formulation is nonlinear, it reproduces the amplitude spectrum of the measured surface displacements better than the hydrostatic model and better than the linear model that takes into account the pressure response factor due to small amplitude waves (the transfer function). Both the proposed formula and the transfer function reconstruct the surface reasonably well, with the proposed formula’s being about 5% more accurate.