Influence of gas ambient on the synthesis of co-doped ZnO:(Al,N) films for photoelectrochemical water splitting

Al and N co-doped ZnO thin films, ZnO:(Al,N), are synthesized by radio-frequency magnetron sputtering in mixed Ar and N₂ and mixed O₂ and N₂ gas ambient at 100 °C. The ZnO:(Al,N) films deposited in mixed Ar and N₂ gas ambient did not incorporate N, whereas ZnO:(Al,N) films grown in mixed O₂ and N₂ gas ambient showed enhanced N incorporation and crystallinity as compared to ZnO:N thin films grown in the same gas ambient. As a result, ZnO:(Al,N) films grown in mixed O₂ and N₂ gas ambient showed higher photocurrents than the ZnO:(Al,N) thin films deposited in mixed Ar and N₂ gas ambient. Our results indicate that the gas ambient plays an important role in N incorporation and crystallinity control in Al and N co-doped ZnO thin films.     

玉米秆纤维形态和制浆漂白特性研究

本文研究了玉米秆化学成分及纤维形态、KP法蒸煮及其纸浆的CEH、DQP和D1(EOP)D2漂白、漂后浆料的打浆性能及所得纸页的物理强度.结果表明,玉米秆的纤维形态较好,适合作为制浆造纸的纤维原料.KP法蒸煮较优的用碱量为16%(NaOH计),超过此用量,卡伯值降低不明显,而得率直线下降.DQP漂序在较低的有效氯用量下,纸浆白度达到84.0%ISO,后续打浆性能和纸页物理强度较好.     

一种大型高空板材安装机器人分析与研究

针对目前高空狭小工作空间、大型重板材安装实际环境的需要,尤其是板材安装仍依赖人工的问题进行了高空板材安装智能化的相关技术研究。对该高空板材安装机器人进行了运动学分析,求出了其运动学正解和逆解。并对其中关键机构四连杆通过建立普通数学模型和模糊数学模型进行了优化,得到机构的最优解,为该机器人的轨迹规划提供了依据。     

原位生成CeB_6颗粒增韧B_4C/Al复合材料的研究

采用无压浸渗法制备了B_4C-CeB_6/Al复合材料, 并对其进行了力学性能测试. B_4C-CeB_6/Al复合材料的密度、抗弯强度、断裂韧性相比单一B4C材料都有很大的提高, 而硬度有所降低. 其抗弯强度值为409.47 Mpa, 比单一碳化硼提高了39.32%; 断裂韧性值6.58 Mpa·m~(1/2), 比单一碳化硼提高了78.80%. B_4C-CeB_6/Al复合材料的抗弯强度和断裂韧性的提高主要有两方面的作用: 一是由于原位生成的CeB_6和B_4C颗粒之间热膨胀系数的不匹配产生残余应力, 从而引起裂纹偏转起到增韧的效果; 二是渗入金属铝的延展性在复合材料中得以体现, 使复合材料韧性增加.     

合肥地区气溶胶光学特性的地基观测研究

利用自主研制的DTF-5型太阳辐射计观测合肥地区2008年10月—2010年5月的太阳直接辐射消光,反演合肥地区气溶胶光学厚度、Angstrom参数和沙尘天气过程中的粒子谱分布,并对结果进行分析。结果表明:合肥地区气溶胶光学厚度季节变化除气候因素外,受人为因素影响明显,季节变化规律复杂。总体上秋季较小,冬春季节持续增大,夏季较平稳。而Angstrom参数与气溶胶光学厚度大致呈反相关,秋冬上升,春季骤降,夏季平稳值较大。气溶胶光学厚度日变化大致可分为4种类型:日变化相对稳定;整体呈上升趋势;整体呈下降趋势;一日内出现一到多个峰值。其中第四种类型出现几率最大。沙尘天气过程中,气溶胶光学厚度和Angstrom参数分别呈现出"谷-峰-谷"、"峰-谷-峰"的变化规律,其中Angstrom参数在沙尘影响严重时甚至出现负值。半径为0.2~1.0μm的大粒子和大于1.0μm的巨粒子浓度在沙尘天气过程中大幅增加。     

Mycoplasma bovis infection in dairy herds—Risk factors and effect of control measures

As Mycoplasma bovis spreads to new countries and becomes increasingly recognized as a disease with major welfare and economic effects, control measures on dairy farms are needed. To minimize the risk of infection spread to naive herds, all possible risk factors for M. bovis infection should be identified and controlled. Mycoplasma bovis was first diagnosed in dairy cattle in Finland in 2012, and by January 2020, 86 Finnish dairy farms (<1.5%) supporting M. bovis infections were identified. We evaluated risk factors for M. bovis infection using a questionnaire provided to 40 infected and 30 control dairy farms. Control measures were advised for 19 of the infected dairy farms during visits by a veterinarian. The course of the infection on those farms was followed by analyzing calf nasal swabs with PCR for presence of M. bovis 4 times at 6-mo intervals. Control measures included culling of M. bovis mastitic cows, isolation of new calves from older animals after initial M. bovis mastitic cows had been culled, prevention of nose-to-nose contact with infected animals, early detection of mastitis cases using M. bovis PCR, and hygiene measures mainly related to milking, calf pens, feeding buckets, and teats. Farms implemented the control measures related to the isolation of calves or avoidance of nose-to-nose contact in various ways, according to farm structures and financial circumstances. In our study, the control measures recommended to the dairy farms appeared effective, such that 13 of 19 farms reached a low risk level during at least 3 consecutive negative samplings from calves, with no M. bovis mastitis detected subsequently. Among risk factors, insemination with an M. bovis-positive bull indicated a trend of increasing the odds of M. bovis infection on the farm in a multivariable logistic model. In contrast, higher herd average milk yield had an association with lower odds for M. bovis infection. Occurrence of other infectious diseases affecting several animals on the dairy farm in the previous 6 mo before M. bovis infection were more frequent on M. bovis-infected farms.     

20kJ/15kW可控超导储能实验装置

介绍了一套可控超导储能(SMES)实验装置.该装置可作为可控超导储能在电力系统中应用的实验研究平台.它包括一个储能量为20 kJ的低温超导磁体和一个15 kW的基于绝缘栅双极晶体管(IGBT)的电流型变流装置.为了减少冷却系统的漏热,超导磁体通过Bi-2223带材制成的高温超导电流引线同变流装置连接.变流装置采用双桥型拓扑和PWM开关策略以减少其输出电流中的谐波成分.为了可以执行高速和高精度的控制算法,变流装置的控制系统采用双DSP的控制器.文中还介绍了该实验装置各部分的结构和工作原理,并给出了初步的实验结果.     

LPX: Overlapping community detection based on X‐means and label propagation algorithm in attributed networks

Traditional community detection methods in attributed networks (eg, social network) usually disregard abundant node attribute information and only focus on structural information of a graph. Existing community detection methods in attributed networks are mostly applied in the detection of nonoverlapping communities and cannot be directly used to detect the overlapping structures. This article proposes an overlapping community detection algorithm in attributed networks. First, we employ the modified X‐means algorithm to cluster attributes to form different themes. Second, we employ the label propagation algorithm (LPA), which is based on neighborhood network conductance for priority and the rule of theme weight, to detect communities in each theme. Finally, we perform redundant processing to form the final community division. The proposed algorithm improves the X‐means algorithm to avoid the effects of outliers. Problems of LPA such as instability of division and adjacent communities being easily merged can be corrected by prioritizing the node neighborhood network conductance. As the community is detected in the attribute subspace, the algorithm can find overlapping communities. Experimental results on real‐attributed and synthetic‐attributed networks show that the performance of the proposed algorithm is excellent with multiple evaluation metrics.     

UFMC系统载波干扰抑制改进算法

针对ICI自消除算法导致UFMC系统频带利用率过低的问题,提出一种联合部分自消除和加升余弦窗的改进方案。该方案具体通过在UFMC系统发射端子带边界插入自消除子载波,并在UFMC系统接收端进行时域加窗来达到抑制UFMC系统干扰、提升系统的频带利用率的目的。对算法进行MATLAB仿真实验,当子带两侧设置4个自消除子载波时,相较自消除算法,系统载波干扰比增大,同时系统的频谱利用率也提升了10%。仿真结果表明,所提算法能够有效抑制ICI,提高系统抗干扰性能,同时提升系统频带利用率。     

通过设计之研究的风景园林学位论文写作框架探讨

长期以来,在设计类专业的研究生培养中,教师和学生对于学位论文的选题和撰写形式一直感到困惑。基于设计研究的理论,探讨在风景园林学位论文撰写过程中,研究生应当如何"通过设计之研究"以及如何呈现研究成果。通过分析清华大学和代尔夫特理工大学的相关学位论文,讨论适合风景园林设计方向的学位论文的研究程序和论文结构:1)研究的过程包括界定设计问题、提出理论假设、设计项目、定量和定性验证假设、总结与反思;2)论文的内容应体现"通过设计之研究"的各个环节,即绪论、设计问题、理论研究和案例研究、研究假设、设计方案、总结与反思。该研究为风景园林设计学位论文的写作提供了一个参考的框架。