动态测量数据的合理性检验方法研究

采样数据合理性检验,是数据处理中重要的一环,它的主要功能是鉴别采样数据中可能含有的异常值,并进行相应的机理分析与修复工作.本文从飞行器外测系统工程应用的角度出发,给出了两种简单易行的判断方法.     

考虑非周期检测的视情维修与备件订购联合策略优化

针对单部件系统/关键部件提出视情维修与备件订购联合策略,其中系统退化服从两阶段延迟时间过程且采用非周期检测策略,退化初期以检测间隔T₁检查系统状态,而在第一次识别缺陷状态时,缩短检测周期为T₂、订购备件且进行不完美维修;若系统在随后的退化中被识别处于缺陷状态,执行不完美维修直至超过阈值次数N_max并采取预防性更换,但若在检测周期内发生故障则进行更换。根据系统状态和备件状态分析各种可能更新事件及相应的联合决策,利用更新报酬理论构建最小化单位时间内期望成本的目标函数,优化T₁,T₂, N_max。与对比模型策略相比,算例结果表明所提出的联合策略能有效降低单位时间内的期望成本。     

隐性字迹的快速光谱显现与高光谱分类技术研究

擦除、密写、掩盖等隐性字迹的快速、无损显现与检验是法庭科学文件检验领域的研究难点。当前多采用切换多波段光源与滤光片的方法对隐性字迹进行显现,但对隐性字迹显现的光谱学机理分析较少,因此隐性字迹的显现效率与检验成功率均不高。为提高擦除、密写、掩盖三类隐性字迹的显现效率与检验精度,通过测量字迹的激发与荧光光谱、反射与透过光谱、微观形貌,对其显现机理与快速显现方法进行深入研究。并且基于液晶可调谐滤光器（LCTF）的高光谱成像技术与支持向量机（SVM）分类算法,提出一种对隐性字迹同时显现与分类的快速检验方法。晨光与百乐可擦笔字、荧光密写笔、柠檬汁均可在365 nm长波紫外光激发下发出较强荧光,其中可擦笔和柠檬汁的荧光波长为716 nm左右,荧光密写笔荧光波长为447 nm。此外,采用254或365 nm波长对柠檬汁隐性字迹进行紫外反射成像也可有效显现柠檬汁字迹。掩盖字迹的研究中发现,在700～2 500 nm红外波段,走珠笔、记号笔、可擦笔字迹透过率在60%以上,而中性笔字迹透过率在20%以下。因此,采用近红外波段850 nm成像有效显现了百乐走珠笔所覆盖的晨光中性笔字迹。同时,采用LCTF高光谱相机对三类隐性字迹在400～720 nm范围进行步长为5 nm的高光谱成像,并通过SVM分类算法对图像中不同笔迹成分进行同时显现和分类,分类总精度达99.284 4%,Kappa系数达0.959 1。以365 nm波长光源作为激发光进行光致发光成像可有效显现擦除与密写字迹。由于不同墨迹在近红外波段反射率差异较大,近红外成像可以有效显现掩盖字迹。基于LCTF高光谱成像的SVM分类技术可实现不同类别隐性字迹的同时显现与分类,并且有较高的显现效率与分类精度。     

多人有误检查的参数估计

文献[ 2 ] 在理论上不必要地复杂化了, 由此导出的算法也相当繁琐. 本文在独立性假设下, 推导了一 种估计参数的有效方法,能大大减少计算工作量. 实例还表明, 用新法估计的参数更接近于实际情况     

散射光子对60Co集装箱CT检测系统的影响

用蒙特卡罗（EGSnrc）方法模拟计算集装箱（大型客体）CT检测系统60Co光子能谱，讨论和分析了该检测系统的客体散射光子对影像分辨率的影响，为进一步提高集装箱（大型客体）CT检测系统数字成像分辨率提供了理论依据.     

快速制取人体组织病理切片的超声波法

本文介绍了用超声波方法快速制妈人体组织病理切片的基本原理，实验步骤和试验结果。结果表明，用超声波处理后快速制取的病理切片完全怀可常规石蜡切片相媲美，在临床外检快速病理诊断应用上，超声处理仪有可能取代价格昂贵的恒温式冷冻切片机。     

Optimal scheduling of non-perfect inspections

^** Corresponding author. Email: romulo.zequeira{at}utt.fr^*** Email: christophe.berenguer{at}utt.fr In this paper, we study the determination of optimal inspectionpolicies when three types of inspections are available: partial,perfect and imperfect. Perfect inspections diagnose withouterror the system state. The system can fail because of threecompeting failure types: I, II and III. Partial inspectionsdetect without error type I failures. Failures of type II canbe detected by imperfect inspections which have non-zero probabilityof false positives. Partial and imperfect inspections are madeat the same time. Type III failures are detectable only by perfectinspections. If the system is found failed in an inspection,a repair is made which renders the system in a good-as-new condition.The system is preventively maintained following an age-basedpolicy. Preventive maintenance actions return the system toa good-as-new condition. We consider cost contributions of inspections,repairs, preventive maintenance and periods of unavailability.The model presented permits to determine the optimal (constant)inter-inspection period for partial, imperfect and perfect inspectionsand the optimal times of preventive maintenance actions.     

Single-sided mobile NMR apparatus using the transverse flux of a single permanent magnet

This study presents a simple design for a mobile, single-sided nuclear magnetic resonance (NMR) apparatus which uses the magnetic flux parallel to the magnetization direction of a single, disc-shaped permanent magnet polarized in radial direction. The stray magnetic field above the magnet is approximately parallel to the magnetization direction of the magnet and is utilized as the B₀ magnetic field of the apparatus. The apparatus weighs 1.8 kg, has a compact structure and can be held in one's palm. The apparatus generates a B₀ field strength of about 0.279 T at the center of apparatus surface and can acquire a clear Hahn echo signal of a pencil eraser block lying on the RF coil in one shot. Moreover, a strong static magnetic field gradient exists in the direction perpendicular to the apparatus surface. The strength of the static magnetic field gradient near the center of the apparatus surface is about 10.2 T/m; one-dimensional imaging of thin objects and liquid self-diffusion coefficient measurements can be performed therein. The available spatial resolution of the one-dimensional imaging experiments using a 5×5 mm horizontal sample area is about 200 μm. Several nondestructive inspection applications of the apparatus, including distinguishing between polyethylene grains of different densities, characterizing epoxy putties of distinct set times and evaluating the fat content percentages of milk powders, are also demonstrated. Compared with many previously published designs, the proposed design bears a simple structure and generates a B₀ magnetic field parallel to the apparatus surface, simplifying apparatus construction and simultaneously rendering the selection of the radiofrequency coil relatively flexible.     

Optical design of high performance con-focal microscopy with digital micro-mirror and stray light filters

This research proposes a newly developed stray light filter in order to eliminate stray light, which otherwise might severely reduce the performance of the con-focal microscopy presented in this research. First, an optical design for con-focal microscopy with a digital micro-mirror device (DMD) is illustrated; second, a newly developed stray light filter is presented, which functions to eliminate possible stray light and ghost images without any sacrifice of luminance. It indicates that not only can the optical system be much simplified but also that its resolution could be one step higher, because the system employs neither a pinhole nor a CCD camera lens. Experimental results are shown in the paper, demonstrating an increase in contrast of up to 60%.     

ICF靶丸装配误差检测

针对激光惯性约束聚变装置中靶丸装配误差检测困难、要求精度高的特点,研制了一套用于微靶装配参数检测的测量系统。提出了一种基于激光与CCD的复合式测量方法,建立了二者数据融合的数学模型,通过标定空间位置关系有效地把二者的测量数据融合到同一个坐标系中,从而实现了高精度三维测量。分两种情况讨论了靶丸装配误差的检测方法。实验结果验证了这两种方法的可行性,并比较了两种方法的测量精度,其极限测量误差均不超过3 m。