自适应滤波在近红外无创生化分析中的应用

提出用血流容积差光谱相减法来消除近红外无创生化分析中组织背景的干扰.为提高光谱相减中所需获得的脉搏波近红外光谱信号的信噪比,研究了自适应滤波处理方法.介绍了最小均方算法(LMS)自适应滤波的基本原理,在此基础上提出了一种适用于处理本实验脉搏波光谱信号的自适应滤波方法;采用实验室自行研制的16元近红外脉搏波采集系统,获得人体脉搏波光谱信号;最后,利用提出的自适应滤波方法处理脉搏波光谱信号并分析其滤波效果.结果表明,利用该方法处理采集的脉搏波信号,可使血流容积光谱相减后血液光谱吸光度噪声由800 μAU降低至12 μAU,相邻波长的脉搏波相关系数由0.994 0提高至0.999 9.分析结果说明该自适应滤波方法可以有效地应用于近红外无创生化分析中.     

中红外衰减全反射法用于尿液成分检测

本文中采用中红外衰减全反射光谱法进行尿液中主要成分的快速、无试剂检测。对单质成分及尿液样品的光谱进行了相应分析,采用偏最小二乘法建立了中红外光谱信息与葡萄糖及白蛋白成分含量间的定量校正模型,并采用遗传算法进行了模型的优化。葡萄糖的预测精度(RMSEP)达到28.57mg/dL, 白蛋白的RMSEP达17.89mg/dL,表明该方法可逐步代替传统方法用于临床检测。     

光电容积脉搏波无创测量人体血液成分的评估

为了评估光电容积脉搏波法在人体血液主要成分检测方面的精度水平,基于朗伯比尔定律及简化的光电容积脉搏波法测量模型,给出了物质成分测量的极限分辨浓度公式。对公式中的三个要素,即人体测量时的光强信噪比、光程、被测物质的摩尔消光系数进行了评估,获得了理论上光电脉搏波法对血红蛋白、白蛋白、血糖的极限分辨浓度。评估结果表明,光电容积脉搏波法可以测量的血红蛋白、白蛋白和血糖的极限分辨浓度水平分别约为100mg/dL,5000mg/dL以及10 000mg/dL。将该评价结果与现阶段临床需要的检测精度进行对比,可知光电容积脉搏波法能够满足需求,有望实现对血红蛋白的无创检测。     

小型近红外玉米蛋白质成分分析 仪器设计的波段选择

采用傅里叶变换近红外漫反射光谱技术和偏最小二乘法(PLS)建立了玉米蛋白质含量的定标模型。按照预测效果优选光谱波段,为设计小型近红外玉米蛋白质成分分析仪器提供依据。采用多元散射校正方法对光谱进行预处理,然后利用Savitzky-Golay平滑法对原谱、一阶导数谱和二阶导数谱进行平滑处理。选取全谱、合频、一倍频、二倍频和蛋白质基团等5个波段,每个波段分别采用原光谱、一阶导数谱、二阶导数谱,共建立15个定标模型。同时调整Savitzky-Golay平滑点数和PLS因子数,通过多次PLS数值实验比较,按照预测效果确定每个模型的最优平滑点数、因子数,再从中选优。结果表明,采用一阶导数谱的一倍频波段(7 000~5 500 cm^－1)的定标效果最好,模型的预测相关系数、预测均方根偏差、相对预测均方根偏差分别为0.945,0.357,3.340%。一倍频波段可以代替全谱波段并得到更好的定标效果。     

尿中葡萄糖含量的近红外光谱快速测量

本文研究了采用近红外光谱技术检测尿液中葡萄糖含量的方法。讨论了采用偏最小二乘法(PLS)建立校正模型过程中数字滤波预处理方法以及利用遗传算法优选波段。尿液中的葡萄糖含量的最佳测量结果RMSEP为10．4mg／dL。结果表明，近红外光谱法可以满足尿液主要成分的实际测量要求。这些实验研究将为糖尿病等相关疾病的无损、快速检测提供一种新的方法。     

小波包正交校正法用于近红外光谱的干扰消除

提出了一种扣除背景和噪声干扰的新方法-小波包正交校正法.首先将原始光谱进行离散小波包变换,消除噪声及部分背景信息,然后采用正交信号校正法滤除与分析物浓度无关的全部信息.与单纯的离散小波包变换及正交信号校正方法相比,小波包正交校正法能有效地扣除背景和噪声干扰,使模型具有更强的抗干扰能力,提高了模型的预测精度.用该法对牛奶样品的近红外光谱进行处理,并将扣除干扰后的数据采用偏最小二乘法建立校正模型,其脂肪、蛋白质和乳糖的预测均方根误差分别为0.086 5%、0.093 6%和0.111 5%,实现了牛奶样品常规组分的定量分析,进一步证明这种算法是切实可行的.     

基于微流控和酶比色的微创血糖连续检测仪

连续血糖检测对糖尿病的诊断与治疗具有十分重要的意义。本文设计了一种集成化、自动化的微创血糖连续检测仪器,该仪器通过微流控芯片透皮抽取组织液,利用单片机精确测量透皮抽取组织液的体积,并采用酶比色法检测组织液的葡萄糖浓度,利用组织液与血液的葡萄糖浓度相关性实现连续血糖检测。由于透皮抽取的组织液体积很小且分散在皮肤表面,为了便于收集,利用生理盐水对抽取出的组织液进行稀释,稀释后的组织液中葡萄糖浓度在3～50mg/dL。为了测量低浓度葡萄糖,实验选取了1～50mg/dL中的10个浓度的葡萄糖溶液进行吸光度测量,根据光谱数据与葡萄糖浓度建立吸光度模型,结果表明该酶比色检测方法在1～50mg/dL葡萄糖浓度内具有良好的线性度,测量相对标准偏差小于0.65%。该仪器能够实现自动化控制,为糖尿病的诊断提供依据,在微创血糖连续检测领域具有良好的应用前景。     

应用近红外透射光谱法测定稻米淀粉回复值

以235份精米为样品,利用近红外透射光谱分析仪扫描样品,采用改进的偏最小二乘法建立定标模型,得到了近红外分析模型的定标标准偏差（SEC）、交叉检验标准差（SECV）和定标决定系数（RSQ）,分别为14.28、14.92和0.87。内部交叉验证结果显示,经校正的工作标准差（SEP）、检验偏差（BIAS）和交叉检验相关系数（1-VR）分别为5.58、0.40和0.95,相关性达极显著水平。内部交叉验证和外部验证结果表明,近红外定量分析精米淀粉回复值有很高的准确度。     

便携式近红外光谱检测系统的开发

在MicroNIR-1700近红外光谱仪上开发了便携式近红外光谱检测系统,介绍了系统光谱仪控制和样品质量检测的功能。为了验证系统的可行性与实用性,以标准白板为检测对象进行了多次光谱检测的重复性试验,在波长1000¹600nm范围内,吸光度最大偏差的最大值为0.0062,标准偏差的最大值为0.0021,系统具有很高的重复性精度;对幸水桃的可溶性固形物进行了实测试验,使用该光谱检测系统采集光谱,同步利用阿贝折射仪在相应部位测量SSC,经卷积平滑法和标准正态变换预处理后,采用PLS方法建立定标模型,其校正集和预测集的相关系数r分别为0.902和0.867,均方根误差RMSECV和RMSEP分别为1.091,1.158。     

大视场多光谱空间相机在轨自动相对辐射校正研究

大视场多光谱空间遥感相机获取的图像直接合成彩色图像后存在严重的色带,且不同片探测器获取的图像存在较大的颜色偏差.随着分辨率、视场角和光谱谱段数量的增加,在地面进行相对辐射校正时数据处理量大且耗时长.提出了一种大视场多光谱遥感相机的在轨自动相对辐射校正方法,通过最小二乘法拟合得到绝对辐射定标系数,计算得到能够消除片间颜色偏差的相对辐射校正系数.在成像控制FPGA中原始图像和从BLOCK RAM中读取的校正系数,依次经过13 b有符号加法器、17 b无符号乘法器和四舍五入模块,自动完成每个像元图像数据的实时相对辐射校正.实验室均匀辐射背景成像实验和仿真结果表明,自动相对辐射校正的结果和在地面进行相对辐射校正的结果一致,校正误差在0.5个DN(digital number)值以内,校正后的图像滞后原始图像6个系统时钟,可以满足实时性要求.在轨成像实验结果表明,经过自动相对辐射校正后直接合成的彩色图像去除了色带和片间色差,使得对感兴趣目标分辨和识别更加快速及时.     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.     

Fractional order nonsingular terminal sliding mode control for flexible spacecraft attitude tracking

This paper investigates a fractional terminal sliding mode control for flexible spacecraft attitude tracking in the presence of inertia uncertainties and extern...     

奥氏体不锈钢表面双辉等离子渗锆的动力学

利用双辉等离子渗金属技术在0Cr18Ni9Ti奥氏体不锈钢表面制备了一层均匀、致密、呈良好冶金结合的渗锆合金层,并对1 060℃下的渗锆动力学进行了研究。结果表明:随着距锆合金层表面距离的增加,锆元素的含量呈梯度递减,扩散系数逐渐减小,而扩散激活能逐步增大;在1 060℃采用双辉等离子技术渗锆时,渗锆合金层表层的空位密度为2.945×(1012~1013)cm-2,与相同温度下采用常规渗金属工艺相比,提高了1~2个数量级。     

气化炉三维扫描测量与数据处理

以德士古气化炉耐火砖的内壁蚀损检测设备为基础,对采集到的点云数据做了进一步处理.通过对数据的筛选和剔除,实现了数据点的平滑降噪细化和精简.然后利用点云对整、网格划分和分色显示等方法,最终完成了内壁腐蚀情况的三维建模.重点讨论了点云数据的预处理及后处理的方法,并根据内壁耐火砖的腐蚀阈值,提出了一种气化炉内壁腐蚀区域的识别与分割方法.对耐火砖的腐蚀分析、气化炉的生产与维修提供了可靠依据,并在工程应用中获得了一致认可.