径向三重流MOCVD反应器壁面温度的数值模拟

将研究辐射换热问题的区域法引入壁面间的辐射换热计算,建立了MOCVD壁面温度的计算模型,应用该模型计算了径向三重流MOCVD反应器的壁面温度分布.结果表明,在反应器的不同部位,壁面温度分布的规律有所不同.当径向三重流MOCVD反应器处于自然对流的环境时,壁面的最大温差可达123K,如此大的温差将会对反应器内的气体流动和沉积过程产生影响;为了使反应器的温度保持在较为恒定的低温,外壁面的强制对流换热系数应大于84W/(m 2·K).     

Enhancing Representation of Deep Features for Sensor-Based Activity Recognition

Sensor-based activity recognition (AR) depends on effective feature representation and classification. However, many recent studies focus on recognition methods, but largely ignore feature representation. Benefitting from the success of Convolutional Neural Networks (CNN) in feature extraction, we propose to improve the feature representation of activities. Specifically, we use a reversed CNN to generate the significant data based on the original features and combine the raw training data with significant data to obtain to enhanced training data. The proposed method can not only train better feature extractors but also help better understand the abstract features of sensor-based activity data. To demonstrate the effectiveness of our proposed method, we conduct comparative experiments with CNN Classifier and CNN-LSTM Classifier on five public datasets, namely the UCIHAR, UniMiB SHAR, OPPORTUNITY, WISDM, and PAMAP2. In addition, we evaluate our proposed method in comparison with traditional methods such as Decision Tree, Multi-layer Perceptron, Extremely randomized trees, Random Forest, and k-Nearest Neighbour on a specific dataset, WISDM. The results show our proposed method consistently outperforms the state-of-the-art methods.

     

等离子体激励对飞行器流场影响的数值研究

针对传统飞行器控制方式的缺点,采用小尺度等离子体流动控制技术对飞行器流场影响进行研究。在前人的实验模型及飞行参数进行研究的基础上建立三维模型,采用数值仿真方法,研究了等离子体激励器位置和注入能量大小对飞行器流场及表面压力分布的影响。仿真结果表明：等离子体与边界层的相互作用可改变飞行器外部激波的初始结构,并在激励位置附近形成局部高压区;随着注入能量的增加,高压区峰值及作用范围分别扩大;等离子体激励产生的扰动具有三维传播特性,对飞行器侧壁面甚至对整个壁面周向压力分布产生影响。     

非标准情况下衰荡光谱的理论分析

本文研究了当激光脉冲线宽远大于被测吸收物质的吸收线宽时,衰荡光谱满足的规律,以及在这种情况下,测量灵敏度的大小。     

液体火箭发动机喷雾液滴内部流动及传热数值模拟

液体火箭发动机喷雾液滴在表面剪切力的作用下形成内部环流,影响液滴内部传热特性,进而影响喷雾蒸发燃烧过程.将一种基于光滑压力修正的非交错网格sIMPLE算法推广到一般曲线坐标系,并对液滴表面特殊边界条件进行数值处理,然后采用代数法生成正交贴体结构网格,求解气相及液相轴对称不可压流动控制方程,得到运动液滴内部稳态流场及其温...     

LightSheer半导体激光脱毛的疗效评价

目的:评价LightSheer半导体激光脱毛的治疗效果。方法:运用LightSheer半导体激光脱毛系统,对97名患者共113个部位进行脱毛治疗,波长800nm,能量密度24-40J/cm2,脉冲宽度30ms,分别对治疗一次、二次及三次后的有效性进行分级评价。结果:97名患者共113个部位一次治疗后均出现毛发再生减少、再生延迟,再生毛发细小、浅淡。随着治疗次数的增加有效性分级提高。二次治疗后,60%以上可达到3级(毛发减少40-59%);三次治疗后,80%以上可达到3级。腋窝和唇毛部位约50%可达到4级(毛发减少60-79%)。结论:LightSheer半导体激光脱毛系统对亚洲人是安全和有效的,80%的患者经三次治疗后毛发可减少近60%,但要达到更好的疗效需更多次治疗。     

小功率单片CMOS不间断电源

介绍了一种无工频变压器的小功率单片ＣＭＯＳ不间断电源（ＵＰＳ）。它由一片ＭＡＸ６１０构成,电路结构简单,外围元件少,体积小,稳压性能良好,而且具有欠压,过压保护和电流过流保护,适用于小型智能仪器和便携式数字仪表。     

TiO2/MXene-Assisted LDI-MS for Urine Metabolic Profiling in Urinary Disease

Cancer remains an intractable medical problem. Rapid diagnosis and identification of cancer are critical to differentiate it from nonmalignant diseases. High-throughput biofluid metabolic analysis has potential for cancer diagnosis. Nevertheless, the present metabolite analysis method does not meet the demand for high-throughput screening of diseases. Herein, a high-throughput, cost-effective, and noninvasive urine metabolic profiling method based on TiO₂/MXene-assisted laser desorption/ionization mass spectrometry (LDI-MS) is presented for the efficient screening of bladder cancer (BC) and nonmalignant urinary disease. Combined with machine learning, TiO₂/MXene-assisted LDI-MS enables high diagnostic accuracy (96.8%) for the classification of patient groups (including 47 BC and 46 ureteral calculus (UC) patients) from healthy controls (113 cases). In addition, BC patients can also be identified from noncancerous UC individuals with an accuracy of 88.3% in the independent test cohort. Furthermore, metabolite variations between BC and UC individuals are investigated based on relative quantification, and related pathways are also discussed. These results suggest that this method, based on urine metabolic patterns, provides a potential tool for rapidly distinguishing urinary diseases and it may pave the way for precision medicine.     

Metal Micropatterning by Triboelectric Spark Discharge

Metal micropatterns play critical roles in flexible electronics. However, the lack of versatile strategies for micropatterning of diverse metal materials on various thin, flexible or stretchable substrates has limited the rapid development of flexible electronics. Here, a metal micropatterning method by triboelectric spark discharge under atmospheric environment is developed, where a triboelectric nanogenerator (TENG) is employed to precisely and safely control the voltage, current, and frequency of the spark discharges. Micropatterns of metal films like gold, silver, copper, aluminum and platinum are successfully fabricated on substrates of polyimide, polyethylene terephthalate, polyvinyl chloride, polydimethylsiloxane, paper or latex, even on ultrathin substrates (5 μm thick) without damage, where the feature sizes of metal patterns are controllable from 20 μm to 1 mm. Experimental insights into the triboelectric spark discharge behaviors and the pattern feature sizes control are discussed. A straightforward fabrication of metal patterns on the balloon surface or human skin through “handwriting” by a pencil as discharge electrode is realized. Besides metals, extended processibility of conductive materials like carbon nanotubes, graphene, MXene, graphite, carbon fibers, and conductive polymers are also demonstrated. This work proves the possibility of microfabrication by TENG, which is of simplicity and attractiveness for flexible electronics.     

碲镉汞外延晶膜的不稳定性

利用变温和变磁场霍尔测试对在空气室温环境长期存放的碲镉汞液相处延晶膜作了定期的检测，结果表明，晶膜的电学性质随时间有明显的改变，本文采用非均匀晶膜的层状模型对晶膜的不稳定性作了详细的分析。