太赫兹波计算鬼成像:原理和展望

本文立足于太赫兹波成像领域近年来备受关注的研究热点—太赫兹波计算鬼成像,首先回顾了鬼成像从量子到经典再到计算的历史过程,然后阐述了计算鬼成像的数学原理,随后综述了计算鬼成像在太赫兹波段的发展历程,及其在超衍射分辨成像、石墨烯光电导成像、太赫兹光谱成像等方面的应用,并在最后展望了太赫兹波计算鬼成像的发展前景:计算鬼成像作为一种成像手段,可以绕开在太赫兹频段缺乏经济高效的焦面阵列式探测器的难题,但目前的成像帧率还难以满足快速成像的应用需求,相信在未来随着器件性能的提升和成像算法的优化,其成像帧率可以得到大幅提升。     

应届化纤专业人才的工程实践能力培养与实践

随着时代的变化,聚酯化纤企业也在迅速地发生着变化,与此同时对化纤应届生人才需求也提出了新的变化。为了应对这种变化,大连工业大学对化纤人才培养主要体现在积极地针对化纤企业的工程特点去培养学生工程实践能力,以适应是时代的需求。在打造大连工业大学高分子材料与工程专业特色化纤品牌的同时,学生可以得到更好的就业机会与职业发展道路,企业可以得所需化纤人才。     

印度洋海盆沉积物中稀土的赋存状态及其浸出研究

印度洋海盆沉积物作为重要的稀土资源，已成为保障我国稀土供应的重要途径。为探究利用印度洋海盆沉积物提取稀土的可行性，通过激光粒度分析、化学物相分析、SEM分析等考察了某印度洋海盆沉积 物中稀土元素赋存状态，并采用硫酸为浸出剂，研究硫酸浓度、液固比、浸出温度及时间对稀土浸出率的影响，对最佳条件下获得的浸出液通过氨水中和沉淀净化。结果表明：①沉积物颗粒极细，体积平均粒径仅 4.47 μm，其主要矿物组成为黏土、锰氧化物、石英、长石、云母、绿泥石和石盐，其中稀土主要赋存于磷灰石中，占总稀土比例达73.10%；②在硫酸浓度2 mol/L，液固比7∶1，浸出温度55 ℃，浸出时间120 min的 最佳条件下，主要稀土元素La、Ce、Nd和Y的浸出率分别为80.57%，66.33%，88.42%和93.25%，高价值的重稀土Gd、Dy和Er浸出率分别为92.63%、55.30%和93.17%。③稀土浸出液成分复杂，且稀土含量偏低，仅有100 mg/L左右，采用氨水调节pH值至5.14，可有效去除Al和Fe，但稀土损失率也达到了30.85%。该研究结果对进一步开发利用深海稀土资源具有重要意义。     

Investigation on milling force of thin-walled workpiece considering dynamic characteristics of workpiece

Journal of Mechanical Science and Technology - The idea of integral calculus is used in traditional milling force prediction methods. In the traditional method, the milling cutter is divided into...     

A quarter century of wine pigment discovery

The red grape berry pigments, anthocyanins, were characterized in the early 20th century, but investigations of wine pigments were stymied during that era. The question of their identity was a major challenge for wine chemists. A number of techniques showed that the pigments were polymeric in nature. Some structures were postulated by mid-century based on reactions between anthocyanins and condensed tannin, and later postulated wine pigments were observed in model reactions. Some related compounds were then observed in wine. By the end of the 20th century, the ionization of non-volatiles for mass spectrometry opened the door to these compounds. In addition, a new class of compounds was observed, the pyranoanthocyanins, a product of fermentation and aging metabolites with anthocyanins. These compounds possess the pigment stability to SO₂ and pH change that is characteristic of aged red wine. Aging experiments show a dynamic situation with shifts in the population of pigment classes over time. The very large number of diverse pigments explains why it has been so difficult to answer the century-old question of the structure of wine pigments. Our current understanding is founded on the use of mass spectral analysis using electrospray and related ionization techniques over the last 25 years. Future progress will rely on more sophisticated analysis of this very complex mixture of substances. © 2019 Society of Chemical Industry     

Personalized broad learning system for facial expression

Multimedia Tools and Applications - Understanding human emotions through facial expressions is key enabling technology for interactive robots. Most approaches of facial expression recognition are...     

铸态Ti-20Zr-20Al钛合金动态压缩力学性能与断裂机制研究

采用X射线衍射仪、金相显微镜、分离式霍普金森杆和扫描电镜等手段研究了Ti-20Zr-20Al钛合金在动态压缩条件下的微观结构、力学性能和断裂机制。结果表明,Ti-20Zr-20Al铸态合金由Zr基体相和TiAl/Ti₃Al针状相组成; 随着应变率增加,合金的抗压强度增加,失效应变显著增加; Ti-20Zr-20Al合金的断裂机制为解理断裂; 随着应变率增加,试验压缩断裂后碎片总数增大,平均粒径减小。采用DID模型模拟的材料碎片尺度与实验结果比较吻合,Grady模型与实验结果的偏差较大。     

A distributed energy system integrating SOFC-MGT with mid-and-low temperature solar thermochemical hydrogen fuel production

Solar thermochemical hydrogen production with energy level upgraded from solar thermal to chemical energy shows great potential. By integrating mid-and-low temperature solar thermochemistry and solid oxide fuel cells, in this paper, a new distributed energy system combining power, cooling, and heating is proposed and analyzed from thermodynamic, energy and exergy viewpoints. Different from the high temperature solar thermochemistry (above 1073.15 K), the mid-and-low temperature solar thermochemistry utilizes concentrated solar thermal (473.15–573.15 K) to drive methanol decomposition reaction, reducing irreversible heat collection loss. The produced hydrogen-rich fuel is converted into power through solid oxide fuel cells and micro gas turbines successively, realizing the cascaded utilization of fuel and solar energy. Numerical simulation is conducted to investigate the system thermodynamic performances under design and off-design conditions. Promising results reveal that solar-to-hydrogen and net solar-to-electricity efficiencies reach 66.26% and 40.93%, respectively. With the solar thermochemical conversion and hydrogen-rich fuel cascade utilization, the system exergy and overall energy efficiencies reach 59.76% and 80.74%, respectively. This research may provide a pathway for efficient hydrogen-rich fuel production and power generation.