一种快速映射Isomap算法

传统的Isomap算法仅侧重于当前数据的分析,不能提供由高维空间到低维空间的快速直接映射,因此无法用于特征提取和高维数据检索.针对这一问题,文中提出一种基于Isornap的快速数据检索算法.该算法能够快速得到新样本的低维嵌入坐标,并基于此坐标检索与输入样本最相似的参考样本.在典型测试集上的实验结果表明,该算法在实现新样本到低维流形快速映射的同时,能较好保留样本的近邻关系.     

Ni-TiO2介孔材料的低热固相合成及其光降解甲基橙的动力学

以十六烷基三甲基溴化铵为模板, 通过钛酸丁酯与六水氯化镍的固相反应直接合成了镍掺杂的二氧化钛（Ni-TiO₂）介孔材料. 用X射线衍射、高分辨透射电镜、N₂脱附-吸附、红外、紫外以及拉曼光谱仪等分析技术对材料进行了物相与表面织构表征; 通过电感耦合等离子发射光谱仪对材料的元素组成进行分析; 同时研究了材料对甲基橙的光降解性能. 结果表明, 所得的介孔材料是锐钛矿型, 金属镍已进入了二氧化钛骨架, 镍的含量为3.62wt%; 孔壁是由无定形的晶界与微晶组成, 并伴有结构缺陷和痕量的金属镍氧化物; 其BET比表面积为102.4m²/g, 孔半径分布中心为2.4nm. 在298K下, Ni-TiO₂介孔材料对甲基橙溶液的紫外光降解行为遵循准一级动力学反应规律,其反应速率常数比纯TiO₂粉体大二倍, 且存在明显的浓度效应.     

A study on the transient effect due to hydrogen passivation in InGaP HBTs

The transient effect of InGaP heterojunction bipolar transistors is studied. The current gain increases with V/sub BE/ bias and becomes stable after several sweeps. The time to reach steady state depends on the collector current I/sub C/ and the ambient temperature. A new electrical method was introduced to calculate the passivation ratio, which is defined as the number of donor hydrogen (H/sup +/) atoms divided by the number of negatively charged carbon atoms (C/sup -/) in the heavily doped base layer. A passivation ratio of 69.98% obtained by this method agrees very well with that measured by secondary ion mass spectrometry of 69%.     

Ni-TiO2介孔材料的低热固相合成及其光降解甲基橙的动力学

以十六烷基三甲基溴化铵为模板, 通过钛酸丁酯与六水氯化镍的固相反应直接合成了镍掺杂的二氧化钛（Ni-TiO₂）介孔材料. 用X射线衍射、高分辨透射电镜、N₂脱附-吸附、红外、紫外以及拉曼光谱仪等分析技术对材料进行了物相与表面织构表征; 通过电感耦合等离子发射光谱仪对材料的元素组成进行分析; 同时研究了材料对甲基橙的光降解性能. 结果表明, 所得的介孔材料是锐钛矿型, 金属镍已进入了二氧化钛骨架, 镍的含量为3.62wt%; 孔壁是由无定形的晶界与微晶组成, 并伴有结构缺陷和痕量的金属镍氧化物; 其BET比表面积为102.4m²/g, 孔半径分布中心为2.4nm. 在298K下, Ni-TiO₂介孔材料对甲基橙溶液的紫外光降解行为遵循准一级动力学反应规律,其反应速率常数比纯TiO₂粉体大二倍, 且存在明显的浓度效应.     

Hydrogen-induced transient effect in carbon-doped InGaP hetero-junction bipolar transistors

The transient effect on the current gain of InGaP hetero-junction bipolar transistors was studied. It was found that this transient effect was caused by hydrogen and eliminated after three or more cycles of thermal annealing at 250 °C in nitrogen. A model based on the carbon-hydrogen complex dissociation by thermal anneal is proposed to explain this observation.     

基于深度卷积神经网络的红外过采样扫描图像点目标检测方法

针对红外过采样扫描成像特点,提出一种基于深度卷积神经网络的红外点目标检测方法.首先,设计回归型深度卷积神经网络以抑制扫描图像杂波背景,该网络不含池化层,输出的背景抑制图像尺寸与输入图像一致;其次,对抑制后的图像进行门限检测,提取候选目标小区域原始数据;最后,将候选目标区域数据依次输入分类型深度卷积神经网络以进一步判别目标、剔除虚警.生成大量过采样训练数据有效训练两个深度网络.结果表明,在不同杂波背景下,该方法在目标信杂比增益、检测概率、虚警概率和运算时间等方面,均优于典型红外小目标检测方法,适用于红外过采样扫描系统的点目标检测.     

中心组合设计优化铁垫片的化学镀镍磷工艺

采用中心组合设计法研究了化学镀镍过程中的三个作用因子:表面活性剂十二烷基二甲基甜菜碱(BS-12)用量、施镀温度、光亮剂辛基酚聚氧乙烯基醚(OP-10)对镍磷沉积速率的影响,得到了三因子与沉积速率的回归方程以及三因素之间相互作用的响应面图。用电子扫描电镜与X-射线衍射仪分析了表征了镀层形貌与晶型结构。优化结果表明,表面活性剂的用量为4.8 mL,施镀温度为52.8 oC,光亮剂的用量为6.6 mL时,镀速为13.56μm/h,比基础镀液的镀速高13%,且镀层光亮致密。所用的光亮剂与表面活性剂不仅影响镀层的沉积速率,而且改变镀层的相结构与性能。     

基于灰度线性建模的亚像素图像抖动量计算

为了解决凝视遥感云场景序列图像的亚像素抖动量求解问题,提出了基于灰度线性建模的亚像素序列图像抖动量计算方法。首先,利用三参数线性模型描述像素及邻域灰度,提出了一种图像灰度的线性建模方法。其次,以序列帧图像相对参考帧图像的抖动量作为线性模型中的优化变量,以参考帧图像与序列帧图像之间的相似性为优化目标,建立了亚像素抖动量解算的最小二乘优化方法,并推导得到了解析计算公式。最后,利用云场景序列图像进行了算法仿真验证。结果表明,该方法抖动量的计算误差小于0.1pixel。将该方法与传统基于特征点的配准算法进行了比较,结果显示该方法具有较高的抖动量计算精度,可应用于遥感图像几何定标、目标定位以及时序图像中目标多帧关联检测等。     

同位素稀释-气相色谱/高分辨质谱法测定食品中的指示性毒杀芬指示性毒杀芬

目的 建立食品样品中P26, P50, P62等三大指示性毒杀芬的检测分析方法,为进一步开展常规监测提供技术平台和基础数据。方法 食品样品使用索式提取系统(Soxtec)提取, 提取液依次由30%酸性硅胶柱和氧化铝柱净化, 利用同位素稀释-高分辨气相色谱/高分辨双聚焦磁式质谱联用(ID-HRGC/HRMS)技术对三种指示性毒杀芬单体P26, P50, P62进行定量定性分析。结果 本研究所建成的检测方法相对标准偏差(RSD)小于25%, 回收率可以达到40%~120%; P26, P50, P62的方法检测限分别为0.08、0.02、0.06 pg/g; 方法性能达到开展食品样品中毒杀芬检测技术的要求。结论 该方法可以对食品样品中毒杀芬进行检测, 检测效率高, 结果准确可靠。     

Solid-Phase Synthesis of Non-metal (S,N)-Doped Tin Oxide Nanopowders at Room Temperature and its Photodegradation Properties for Wastewater of Biomass Treatment

Tin oxide and sulfur, nitrogen-doped tin oxide nano-powder catalysts were prepared by a solid phase reaction at room temperature, using the sodium p-toluene sulfonate (STS) surfactant as template. Theoretical calculation of the dehydration reaction energy of tin hydroxide was performed with the framework of DFT and their structures were characterized. And the UV-light degradation performance and mechanism used for the biomass wastewater were discussed, as well as, its COD and NH₃-N value. The results show that the large gap of the reaction energy between intramolecular dehydration (Er?=?2.81 eV) and intermolecular dehydration (Er?=?5.77 eV) for tin hydroxide causes the presence of amorphous SnO₂ and metastable tin hydroxide at 450 °C. The entry of S and N into the (110) crystal plane of SnO₂ reduces its energy band gap width, exhibiting the photocatalytic degradation rate (98.9%) of S?+?N-SnO₂-_STS sample for the rice straw powder treatment wastewater (RSPTW) irradiated by UV-light for 8 h. The excellent degradation capacity of RSPTW mainly comes from the hydroxyl radicals (·OH) and superoxygen radicals (·O₂^?) produced by the rich hydroxyl on the surface of S?+?N-SnO₂-_STS due to the regulatory effect of STS and lower calcined temperature. The sewage discharge of photodegraded RSPTW complies with Chinese National Level II Standards.