基于显著兴趣点颜色及空间分布的图像检索新方法

提出了一种基于显著兴趣点的图像检索新方法,此方法主要有显著兴趣点检测、基于显著兴趣点的特征描述和相似性度量三个步骤.先使用一个自适应滤波器对图像进行滤波,然后提取显著兴趣点;以显著兴趣点为线索,设计了一种基于显著兴趣点的环形颜色直方图,既利用了显著兴趣点的局部特征,又考虑了显著兴趣点的空间分布结构;用图像间的环形颜色直方图距离来度量图像间的相似性.该检索算法不但保证了对图像旋转、平移鲁棒性,而且克服了传统直方图没有空间位置的缺陷.实验结果表明,该方法对图像检索非常有效.     

自激振荡流热管脉冲加热强化传热实验研究

自激振荡流热管也称为脉动热管,是一种新型高效的传热元件。本文提出了采用脉冲加热代替常规连续热源加热强化自激振荡流热管传热的方法,并对其进行了实验研究。实验结果显示,脉冲加热时热管冷、热端壁面温度的振荡频率明显大于连续加热热管的壁面温度振荡频率。在相同的加热功率下,当脉冲宽度在200-1000 ms时,脉冲加热热管的传输热流量与当量导热系数均大于连续加热热管的传输功率和当量导热系数．这表明脉冲加热强化自激振荡流热管传热的方法是可行的．     

振幅指数衰减正弦干涉信号线性预测模型的求解

在光谱成像的光谱分辨率增强技术中,对振幅衰减干涉信号的线性预测是其中的关键之一.文中在已知振幅指数衰减正弦干涉信号的个数、波数和衰减率的前提下,给出了线性预测系数直接计算公式及其前向线性预测系数与后向线性预测系数之间的关系;定义了该类正弦迭加信号的前向和后向线性可预测性条件.研究结果表明,振幅指数衰减的正弦迭加信号的前向和后向线性预测系数不再是简单的共轭对称关系了,但是二者依然是有联系的.该研究为一般的衰减干涉信号的光谱分辨率增强算法提供了理论基础. 关键词： 光谱分辨率增强 线性预测 可预测条件 预测系数     

基于灰度冗余图像融合增强研究

为了改善原图像直方图像素灰度分布集中于低灰度级,与经过常规直方图均衡化处理的图像直方图像素灰度分布集中于高灰度级且均具有灰度冗余的图像增强效果,提出了一种新的图像增强算法.对原始图像进行常规直方图均衡处理,并对原始图像与进行了常规直方图均衡处理的图像分别在尽可能大的范围内进行映射,使两者变换后都尽可能去除灰度冗余而有较大的动态范围.取变换后的两图像各自的优点,融合成一幅效果最好的图像.实验结果验证了理论分析的正确性.     

飞秒激光共振增强腔的理论与实验研究

飞秒激光共振增强腔在非线性光学、 精密光谱学等研究领域有重要应用, 尤其是近年来已成为产生高重频紫外光梳的强大工具. 采用循环稳定电场方法分析了飞秒激光脉冲在共振 增强腔中的增强和色散特性,给出了增强倍数与 精细度的关系及共振带宽与精细度和腔内色散量的关系. 实验上实现了175 MHz, 15 fs的宽谱飞秒激光脉冲的共振 增强,增强倍数约为10倍左右.     

氨水降膜吸收传热传质强化的研究进展

综述了近年来应用于氨水降膜吸收性能强化的研究成果,总结了氨水降膜吸收的强化方法,分析了氨水降膜吸收过程中的影响因素,指出研究中的一些不足,并对该领域未来的研究方向进行了讨论,指出采用物理处理、化学处理和纳米技术三种强化手段相结合的方法是未来强化吸收可能的发展趋势。     

Internal quantum efficiency enhancement of silicon nanocrystals using double layer Au-rich cermet films

To improve the internal quantum efficiency of silicon nanocrystals, a double layer structure with Au-rich cermet is proposed. In the region far below surface plasmon resonance energy, effective enhancement can be still obtained, which indicates means to make surface plasmon mediated enhancement efficient in a wide wavelength region especially for long wavelength.     

High speed measurement of corn seed viability using hyperspectral imaging

Corn is one of the most cultivated crops all over world as food for humans as well as animals. Optimized agronomic practices and improved technological interventions during planting, harvesting and post-harvest handling are critical to improving the quantity and quality of corn production. Seed germination and vigor are the primary determinants of high yield notwithstanding any other factors that may play during the growth period. Seed viability may be lost during storage due to unfavorable conditions e.g. moisture content and temperatures, or physical damage during mechanical processing e.g. shelling, or over heating during drying. It is therefore vital for seed companies and farmers to test and ascertain seed viability to avoid losses of any kind. This study aimed at investigating the possibility of using hyperspectral imaging (HSI) technique to discriminate viable and nonviable corn seeds. A group of corn samples were heat treated by using microwave process while a group of seeds were kept as control group (untreated). The hyperspectral images of corn seeds of both groups were captured between 400 and 2500 nm wave range. Partial least squares discriminant analysis (PLS-DA) was built for the classification of aged (heat treated) and normal (untreated) corn seeds. The model showed highest classification accuracy of 97.6% (calibration) and 95.6% (prediction) in the SWIR region of the HSI. Furthermore, the PLS-DA and binary images were capable to provide the visual information of treated and untreated corn seeds. The overall results suggest that HSI technique is accurate for classification of viable and non-viable seeds with non-destructive manner.     

Numerical simulation of ultrasonic enhancement on mass transfer in liquid–solid reaction by a new computational model

Mass transfer coefficient is an important parameter in the process of mass transfer. It can reflect the degree of enhancement of mass transfer process in liquid–solid reaction and in non-reactive systems like dissolution and leaching, and further verify the issues by experiments in the reaction process. In the present paper, a new computational model quantitatively solving ultrasonic enhancement on mass transfer coefficient in liquid–solid reaction is established, and the mass transfer coefficient on silicon surface with a transducer at frequencies of 40 kHz, 60 kHz, 80 kHz and 100 kHz has been numerically simulated. The simulation results indicate that mass transfer coefficient increases with the increasing of ultrasound power, and the maximum value of mass transfer coefficient is 1.467 × 10⁻⁴ m/s at 60 kHz and the minimum is 1.310 × 10⁻⁴ m/s at 80 kHz in the condition when ultrasound power is 50 W (the mass transfer coefficient is 2.384 × 10⁻⁵ m/s without ultrasound). The extrinsic factors such as temperature and transducer diameter and distance between reactor and ultrasound source also influence the mass transfer coefficient on silicon surface. Mass transfer coefficient increases with the increasing temperature, with the decreasing distance between silicon and central position, with the decreasing of transducer diameter, and with the decreasing of distance between reactor and ultrasound source at the same ultrasonic power and frequency. The simulation results indicate that the computational model can quantitatively solve the ultrasonic enhancement on mass transfer coefficient.     

The oral administration of MnCl2: A potential alternative to IV injection for tissue contrast enhancement in magnetic resonance imaging

Mn⁺² (as MnCl₂) was administered to rabbits intravenously and orally (a route of administration which based upon our previous experiments in rats⁷ promises to give selective hepatobiliary enhancement with less systemic toxicity). Nuclear magnetic relaxation dispersion or T₁ (NMRD) was performed on selected tissues (heart, liver, kidney, serum, and bile) in both animal groups to examine possible qualitative and semiquantitative differences in T₁ relaxation at equivalent sacrifice times. One animal was given an oral dose of MnCl₂ (620 micromoles/kg) and imaged sequentially (T₁ weighted sequence, .12T) for 30 minutes. The NMRD curves for organ tissues show an increase in relaxation efficacy in the 10–20MHz range characteristic of Mn-macromolecular complexes and are similar irrespective of the route of administration. The lack of increased relaxation enhancement for bile in this frequency range reflects cleavage of this complex upon excretion. Decreased overall relaxation in the liver is observed when oral Mn⁺² is compared to IV Mn⁺² due to the small fraction of administered dose that is absorbed. However, the images document a significant increase in the intensity of liver signal after the oral dose. We suspect this dose may ultimately be adjusted downward to give selective hepatobiliary effects.