摘要:
Chemical agent warfare materials and their simulant liquids are identified on terrestrial surfaces at a distance by recognizing the contaminant's infrared fingerprint spectrum brought out in thermal luminescence (TL). Suspect surfaces are irradiated with microwave light that is absorbed into the surface and, subsequently, TL is released by the surface. An optics receiver collects the released TL radiant light, and a data acquisition system searches this TL radiant flux for the contaminant's fingerprint infrared spectrum. A decision on the presence or absence of any-of-N contaminants is done by a neural network system that acts as a filter through real-time pattern recognition of the contaminant's unique infrared absorption or emission spectra.
摘要:
An optomechanical switching device, a control system, and a graphical user interface for a photopolarimetric lidar standoff detection that employs differential-absorption Mueller matrix spectroscopy. An output train of alternate continuous-wave CO2 laser beams [ . . . L1:L2 . . . ] is directed onto a suspect chemical-biological (CB) aerosol plume or the land mass it contaminates (S) vis-à-vis the OSD, with L1 [L2] tuned on [detuned off] a resonant molecular absorption moiety of CB analyte. Both incident beams and their backscattered radiances from S are polarization-modulated synchronously so as to produce gated temporal voltage waveforms (scattergrams) recorded on a focus at the receiver end of a sensor (lidar) system. All 16 elements of the Mueller matrix (Mij) of S are measured via digital or analog filtration of constituent frequency components in these running scattergram data streams (phase-sensitive detection). A collective set of normalized elements {ΔMi,j} (ratio to M11) susceptible to analyte, probed on-then-off its molecular absorption band, form a unique detection domain that is scrutinized; i.e., any mapping onto this domain by incoming lidar data—by means of a trained neural network pattern recognition system for instance—cues a standoff detection event.
摘要:
A four-layer neural network is trained with data of midinfrared absorption by nerve and blister agent compounds (and simulants of this chemical group) in a standoff detection application. Known infrared absorption spectra by these analyte compounds and their computed first derivative are scaled and then transformed into binary or decimal arrays for network training by a backward-error-propagation (BEP) algorithm with gradient descent paradigm. The neural network transfer function gain and learning rate are adjusted on occasion per training session so that a global minimum in final epoch convergence is attained. Three successful neural network filters have been built around an architecture design containing: (1) an input layer of 350 neurons, one neuron per absorption intensity spanning 700.ltoreq..nu..ltoreq.1400 wavenumbers with resolution .DELTA..nu.=2; (2) two hidden layers in 256- and 128-neuron groups, respectively, providing good training convergence and adaptable for downloading to a configured group of neural IC chips; and (3) an output layer of one neuron per analyte--each analyte defined by a singular vector in the training data set. Such a neural network is preferably implemented with a network of known microprocessor chips.
摘要翻译:在间隔检测应用中,通过神经和起泡剂化合物(以及该化学基团的模拟物)的数据来训练四层神经网络。 通过这些分析化合物及其计算的一阶导数的已知红外吸收光谱进行缩放,然后通过具有梯度下降范例的反向误差传播(BEP)算法将其转换为二进制或十进制数组进行网络训练。 神经网络传递函数增益和学习率在每次训练中偶尔进行调整,从而达到最终时代收敛的全局最小值。 已经建立了三个成功的神经网络滤波器,包括:(1)350个神经元的输入层,每个吸收强度的一个神经元跨越700 = nu = 1400波数,分辨率为DELTA nu = 2; (2)分别在256和128神经元组中的两个隐藏层,提供良好的训练收敛,并适用于下载到配置的神经IC芯片组; 和(3)每个分析物的一个神经元的输出层 - 由训练数据集中的奇异向量定义的每个分析物。 这样的神经网络优选地使用已知的微处理器芯片的网络来实现。