Two-dimensional random projection

As an alternative to adaptive nonlinear schemes for dimensionality reduction, linear random projection has recently proved to be a reliable means for high-dimensional data processing. Widespread application of conventional random projection in the context of image analysis is, however, mainly impeded by excessive computational and memory requirements. In this paper, a two-dimensional random projection scheme is considered as a remedy to this problem, and the associated key notion of concentration of measure is closely studied. It is then applied in the contexts of image classification and sparse image reconstruction. Finally, theoretical results are validated within a comprehensive set of experiments with synthetic and real images.     

Oxygen doped Ge crystals Czochralski-grown from the B2O3-fully-covered melt

Local vibrations of oxygen in Ge crystals grown from a melt fully covered by B₂O₃ were evaluated by Fourier-transform infrared spectroscopy. Ge single crystals containing oxygen were grown by the Czochralski method under various growth conditions. Oxygen concentrations in the crystals were determined to be in the range between 8.5 × 10¹⁵ and 5.5 × 10¹⁷ cm⁻³ from the infrared absorption at 855 cm⁻¹ originating in local vibration of Ge-O_i-Ge quasi-molecules. Absorption peaks relating to GeO_x, SiO_x and Si-O_i-Si were not detected in the as-grown crystals. The calibration coefficient for determining oxygen concentration in Ge crystals from the absorption peak intensity at 1264 cm⁻¹ was estimated to be 1.15 × 10¹⁹ cm⁻².     

光纤数字环路载波系统的发展

ＯＤＬＣ是当今用户接入网的新型设备，它一方面可取代端局，解决通信线路紧张和远距离大容量放号问题，另一方面也可满足日益增多的增值业务的需求。本文ＯＤＬＣ技术的基本原理，结合目前国内外常见ＯＤＬＣ系统，总结和对比了其基本特点，优势，并指明ＯＤＬＣ的技术发展方向和中国应用的前景。     

柴油机气缸内局部瞬态碳粒浓度、火焰温度改进双色法测量系统

介绍了一套新的改进双色法柴油机气缸内局部瞬态火焰温度和碳粒浓度测试系统,其测试原理利用了颗粒的衍射理论,细致地考虑了柴油机缸内碳粒云的光学参数。测试系统中采用了分叉光纤从而省去了一套复杂的光学分光系统。新型的探头设计较好地解决了蓝宝石窗面的积炭问题,对测试系统进行了标定。在缸盖火力面上布置两个具有代表性的测点来测量火焰温度和碳粒浓度,测试结果表明：活塞凹坑部位火焰温度和碳粒浓度均较高;在活塞挤流区,循环变动很大。在活塞凹坑部位和活塞挤流区所测火焰温度和碳粒浓度均有一定相位差。     

3.66μm激光外差光谱仪设计与水汽柱浓度反演

激光外差光谱测量技术具有光谱分辨率高、探测灵敏度高、成本低等特点,近年来在温室气体探测、激光大气传输等领域得到了广泛的应用。以3.66 μm 分布反馈式带间级联激光器作为本振光源搭建了一套高分辨率激光外差太阳光谱测量装置,实现了水汽吸收光谱的实时测量,并利用最优估算法对整层大气中的水汽柱浓度进行了反演,得到合肥地区2019年5月22日和23日的水汽柱浓度。反演结果与同步进行观测的傅里叶变换光谱仪EM27/SUN测量结果变化趋势一致,相关性优于0.8,偏差小于15%。研究结果表明,搭建的激光外差测量装置能够实现大气中水汽吸收光谱的实时测量以及水汽柱浓度的精确反演,同时为后续的水汽浓度廓线测量与研究奠定了基础。     

MBE生长的InSb和InASxSb1—x的载流子浓度剖面分布

在(111)InSb 和(100)GaAs 衬底上,用分子束外延技术生长了 InSb 和 InAs_xSb_(1-x)外延层。用自动电化学 C—V 法测量了外延层的载流子浓度剖面分布。结果表明:(1)外延层呈 P 型;(2)InSb/GaAs 异质外延层的载流子浓度为(1～2)×10~(16)cm~(-3),比相应的同质外延层 InSb/InSb 的(1～2)×10~(17)cm~(-3)小一个数量级;(3)生长层的载流子浓度剖面分布和质量取决于衬底表面的制备。讨论了有关问题。     

GA309型预湿浆纱机性能特点及其应用

分析GA309型预湿浆纱机上浆装置的性能特点,并对预湿上浆效果进行测试.通过合理设置预湿上浆工艺参数,顺利完成了对多个纯棉品种的预湿上浆实践,与采用传统上浆工艺浆纱效果的对比表明:在上浆压力和浆料配方相同的条件下,浆纱毛羽可降低20个百分点左右,上浆率可降低2个百分点以上,浆纱成本降低20%以上,织机效率和产品下机一等品率都优于传统上浆.     

进食状态下不同时间点血中标记氨基酸浓度和丰度差异性分析

目的通过示踪剂动态观察蛋白质和氨基酸的代谢变化过程中在同位素丰度达到稳定的平台期时,不同的时间点血液中标记氨基酸的丰度与浓度的变化,以此反映不同时点蛋白质和氨基酸的氧化分解状况。方法选取20名健康成年男性为研究对象,分为2组,以7 d为一个实验周期,给予受试者日常膳食5 d后,第6天经静脉滴注给予稳定同位素13C标记的亮氨酸,持续3 h。在输液结束前的30 min内每隔15 min取一次血液样品,测定血样中亮氨酸的浓度与13C的丰度值,并比较各时点丰度及浓度的差异性。结果二组受试者3个时间点亮氨酸的浓度与13C丰度值之间的差异无统计学意义。结论在进食状态下持续给予受试者稳定同位素的过程中,不同时间点机体蛋白质和氨基酸的氧化分解处于一个相对稳定的状态,可以在此时期内确定一个同一的时间点来研究机体处于不同的蛋白质和氨基酸营养状态下的各项代谢动力学参数。     

保香低温速溶红茶粉的研发

为了解决速溶茶粉的滋味淡、香气低、冷溶性差等问题,该试验以红茶为原料,采用高压脉冲电场（Pulsed Electric Field,PEF）技术辅助提取和杀菌,并结合冷冻浓缩和真空冷冻干燥联合真空吸附干燥法生产速溶红茶粉,使得整个加工工艺都在低温状态下完成。试验结果表明,高压脉冲电场技术有助于提高红茶的提取率,冷冻浓缩和高压脉冲电场杀菌能够有效保持茶汤的色、香、味;真空冷冻干燥联合真空吸附干燥后所得的速溶红茶粉的得率为22.7%,且其冷溶性高,滋味鲜浓而醇厚,香气高而纯正,汤色红艳明亮,无沉淀。     

Freeze‐drying concentration of Rangpur lime juice

The use of freeze‐drying for concentrating lime Rangpur juice was investigated. This procedure allowed obtaining concentrated Rangpur lime juices between 23 and 51.3 °Brix, without affecting their organoleptic and nutritional characteristics. The efficiency of the procedure was inversely related to the film thickness of the matrix to be lyophilised. The sublimation speed per unit area diminished with the reduction in the residual moisture content of the juice. The mathematical model that fitted to the concentration procedure allowed to predict the time required for concentrating Rangpur lime by freeze‐drying starting from samples of different thickness. When compared with other citric juices evaluated, the Rangpur lime juice was the most suitable for freeze‐drying concentration. The results could be used to devise optimal industrial freeze‐drying cycles for processing Rangpur lime juices at different concentrations.