Heterogeneous Ir3Sn–CeO2/C as alternative Pt-free electrocatalysts for ethanol oxidation in acidic media

For reducing the Pt usage and driving down the cost of fuel cells, it is urgent to develop alternative Pt-free catalysts with high catalytic performance. In this study, an Ir₃Sn–CeO₂/C heterogeneous catalyst is designed as low-price, alternative Pt-free electrocatalyst towards ethanol oxidation reaction (EOR) in acidic conditions. Owing to the strong synergistic effect among Ir, Sn and CeO₂ components, Ir₃Sn–CeO₂/C heterogeneous catalyst exhibits higher catalytic activity and stability for EOR in comparison with commercial Pt/C, as-prepared Ir/C and Ir₃Sn/C. Additionally, kinetics and mechanisms of EOR are also investigated. It proves that ethanol electrooxidation on Ir₃Sn–CeO₂/C catalyst is a diffusion controlled irreversible process. Meanwhile, the H₂SO₄ and ethanol concentrations can affect the EOR activity. All results demonstrate Ir₃Sn–CeO₂/C heterogeneous catalyst is a promising Pt-free choice for EOR.     

基于WI-FI的井下定位算法研究

基于射频指纹的室内定位算法有很多,现提出基于射频指纹的应用在煤矿巷道这种特有的环境特征的一种新的定位算法。根据无线信号的衰减特性,将距离接入点3m处的接收信号强度值设为阈值,若设备接收的信号强度值大于阈值则直接定位到此接入点处。若信号强度低于阈值,则根据射频指纹数据库数据得到估计位置。在煤矿中移动目标的速度一般小于10m/s,根据这一特征,算法中设定前后两次的定位位置不能超过10 m;若超过10 m,则取前一秒的定位位置与该秒采用数据库匹配得出的位置的中点。将这些特征应用到射频指纹定位算法中可以非常有效的减少环境对信号强度的影响。通过实验表明,该定位算法具有较高的定位精度。     

Pathological lung segmentation based on random forest combined with deep model and multi-scale superpixels

Accurate segmentation of lungs in pathological thoracic computed tomography (CT) scans plays an important role in pulmonary disease diagnosis. However, it is still a challenging task due to the variability of pathological lung appearances and shapes. In this paper, we proposed a novel segmentation algorithm based on random forest (RF), deep convolutional network, and multi-scale superpixels for segmenting pathological lungs from thoracic CT images accurately. A pathological thoracic CT image is first segmented based on multi-scale superpixels, and deep features, texture, and intensity features extracted from superpixels are taken as inputs of a group of RF classifiers. With the fusion of classification results of RFs by a fractional-order gray correlation approach, we capture an initial segmentation of pathological lungs. We finally utilize a divide-and-conquer strategy to deal with segmentation refinement combining contour correction of left lungs and region repairing of right lungs. Our algorithm is tested on a group of thoracic CT images affected with interstitial lung diseases. Experiments show that our algorithm can achieve a high segmentation accuracy with an average DSC of 96.45% and PPV of 95.07%. Compared with several existing lung segmentation methods, our algorithm exhibits a robust performance on pathological lung segmentation. Our algorithm can be employed reliably for lung field segmentation of pathologic thoracic CT images with a high accuracy, which is helpful to assist radiologists to detect the presence of pulmonary diseases and quantify its shape and size in regular clinical practices.

     

一种基于码本轮转的有限反馈量化方法

大规模多输入多输出（Multiple-Input Multiple-Output,MIMO）系统中随着天线数目的增加,其反馈比特数将随之大幅度增加。为此,提出了一种基于码本轮转的有限反馈量化方法。该方法中,用户在前一时刻得到最佳码字之后,在码本中选取轮转区域构成虚拟码本,判断当前时刻的信道向量,满足轮转条件的用户将虚拟码本轮转到码本起始位置,在虚拟码本中进行量化;不满足轮转条件的用户在原始码本中进行量化,选出当前时刻的最优码字。反馈比特数分析与仿真结果表明,所提方法可轮转的虚拟码本减少了量化码字的数量,从而减少了反馈比特数,是系统性能与反馈比特数的一种折中。     

TC4钛合金上制备c轴取向AlN薄膜研究

采用中频磁控反应溅射,提出了在TC4钛合金基片上制备c轴取向AlN薄膜的两步法工艺。利用扫描电镜分析(SEM)、X线衍射(XRD)、原子力显微镜(AFM)对薄膜的表面及断面形貌、晶体结构、表面粗糙度进行了表征。研究结果表明,利用该文提出的两步法工艺可在TC4钛合金衬底上制备出表面粗糙度为2.3nm、c轴XRD摇摆曲线半高宽为4.1°的AlN薄膜,满足制作压电微机电系统(MEMS)器件或薄膜声表面波(SAW)和体声波器件的需求。     

直流分布式电源系统的建模研究

如今直流分布式电源系统(Distributed Power System，Dps)正以其冗余度高、控制灵活等优点而被广泛地应用于通信、航空航天、计算机等各个领域。但是由于系统内部各个单元模块自身、以及模块之间相互影响的复杂性，使得国内目前直流分布式电源系统的研究与国外相比存在较大的差距。本文就DC DPS内部各个模块自身、DC DPS的建模方法、稳定性分析作一总结。     

基于超声多普勒测速法对二维涡流场初步测量研究

为研究第四代先进反应堆燃料组件、散裂靶窗及换热器等复杂部件内的涡流场，利用超声多普勒测速（UDV）法在四直叶轮搅动装置上开展了涡流流场的测量实验。通过径向和轴向流场的矢量合成，获得了轴向截面上二维涡流流场分布。结果表明：轴向截面上流速随雷诺数的增大而增大；在叶轮上、下两侧区域分别存在较大的漩涡，上漩涡为逆时针方向，下漩涡为顺时针方向；截面上流速分布存在较大梯度，且湍流强度随雷诺数的增大逐渐增大，在与叶轮等高处流速很大，而在叶轮上、下两侧区域流速较小，这表征了涡流场的变化特性，说明UDV测量技术能用于复杂流场测量。     

罗家寨飞仙关高含硫气藏水平井完井技术

罗家寨气田是目前全国较大的高酸性气田,高含H2S且地形复杂,采用丛式井组水平井培育高产井,是提高气田开发效益的重要途径。对大产量、高含硫的水平井采用什么样的完井方式、完井工具、完井管柱、完井工艺才能使气井在生产过程中能够安全生产,采取何种安全措施,才能保证高含硫气井能安全顺利地完井。目前已安全地在罗家11H、16H-1两口井进行完井现场试验,其完井测试产量达到了200×104m3/d以上,这两口大产量井的现场试验成功,为规模开发川东北高含硫气田取得了宝贵的经验。