n-nc-Si:H低温制备工艺及其在柔性钙钛矿太阳电池中的应用

【目的】为在低温工艺下制备出适用于柔性钙钛矿太阳电池的高性能电子传输层,需要对电子传输层材料及制备条件进行研究。【方法】将n型氢化纳米晶硅薄膜作为柔性钙钛矿太阳电池电子传输层,研究衬底温度对薄膜性能的影响,并优化电子传输层与钙钛矿层界面处理工艺和结构。【结果】得到暗电导率、光透过率、表面形貌适用于柔性钙钛矿太阳电池电子传输层的n型氢化纳米晶硅薄膜低温制备条件,经过界面优化处理的柔性钙钛矿太阳电池转换效率达到14.66%。【结论】在低温工艺下制备出了高性能的电子传输层及柔性钙钛矿太阳电池,对进一步开展叠层钙钛矿太阳电池的研究具有指导意义。

Global hybrid simulations of soft X-ray emissions in the Earth’s magnetosheath

Earth’s magnetopause is a thin boundary separating the shocked solar wind plasma from the magnetospheric plasmas,and it is also the boundary of the solar wind energy transport to the magnetosphere.Soft X-ray imaging allows investigation of the large-scale magnetopause by providing a two-dimensional(2-D)global view from a satellite.By performing 3-D global hybrid-particle-in-cell(hybrid-PIC)simulations,we obtain soft X-ray images of Earth’s magnetopause under different solar wind conditions,such as different plasma densities and directions of the southward interplanetary magnetic field.In all cases,magnetic reconnection occurs at low latitude magnetopause.The soft X-ray images observed by a hypothetical satellite are shown,with all of the following identified:the boundary of the magnetopause,the cusps,and the magnetosheath.Local X-ray emissivity in the magnetosheath is characterized by large amplitude fluctuations(up to 160%);however,the maximum line-of-sight-integrated X-ray intensity matches the tangent directions of the magnetopause well,indicating that these fluctuations have limited impact on identifying the magnetopause boundary in the X-ray images.Moreover,the magnetopause boundary can be identified using multiple viewing geometries.We also find that solar wind conditions have little effect on the magnetopause identification.The Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)mission will provide X-ray images of the magnetopause for the first time,and our global hybrid-PIC simulation results can help better understand the 2-D X-ray images of the magnetopause from a 3-D perspective,with particle kinetic effects considered.

航空航天铝合金腐蚀疲劳失效与寿命预测研究进展

铝合金具有低密度、高强度、良好的加工性能和焊接性能等众多优点,在航空航天领域得到了广泛的应用。在沿海或海洋环境中服役的航空航天装备,由于海水飞溅、雨水冲刷,一定程度上会受到腐蚀的影响,因此航空航天铝合金面临腐蚀疲劳的服役条件。本文综述了航空航天铝合金的应用现状,从腐蚀疲劳的失效机理角度,详细总结了腐蚀疲劳裂纹萌生机理、扩展机理以及裂纹的萌生位置和裂纹扩展行为,并对典型航空航天铝合金的腐蚀疲劳性能进行了概述,介绍了近年来在预腐蚀疲劳条件和腐蚀-疲劳交替条件下航空航天铝合金寿命预测的方法。从宏观与微观角度对航空航天铝合金腐蚀-疲劳交替过程进行研究,以及建立更加精准的腐蚀疲劳寿命预测模型是未来研究的重点。

Vulnerability assessment of UAV engine to laser based on improved shotline method

Laser anti-drone technology is entering the sequence of actual combat,and it is necessary to consider the vulnerability of typical functional parts of UAVs.Since the concept of"vulnerability"was proposed,a variety of analysis programs for battlefield targets to traditional weapons have been developed,but a comprehensive assessment methodology for targets'vulnerability to laser is still missing.Based on the shotline method,this paper proposes a method that equates laser beam to shotline array,an efficient vulnerability analysis program of target to laser is established by this method,and the program includes the circuit board and the wire into the vulnerability analysis category,which improves the precision of the vulnerability analysis.Taking the UAV engine part as the target of vulnerability analysis,combine with the"life-death unit method"to calculate the laser penetration rate of various materials of the UAV,and the influence of laser weapon system parameters and striking orientation on the killing probability is quantified after introducing the penetration rate into the vulnerability analysis program.The quantitative analysis method proposed in this paper has certain general expansibility,which can provide a fresh idea for the vulnerability analysis of other targets to laser.

Acetic acid-and furfural-based adaptive evolution of Saccharomyces cerevisiae strains for improving stress tolerance and lignocellulosic ethanol production

Acetic acid and furfural are known as prevalent inhibitors deriving from pretreatment during lignocellulosic ethanol production.They negatively impact cell growth,glucose uptake and ethanol biosynthesis of Saccharomyces cerevisiae strains.Development of industrial S.cerevisiae strains with high tolerance towards these inhibitors is thus critical for efficient lignocellulosic ethanol production.In this study,the acetic acid or furfural tolerance of different S.cerevisiae strains could be significantly enhanced after adaptive evolution via serial cultivation for 40 generations under stress conditions.The acetic acid-based adaptive strain SPSC01-TA9 produced 30.5 g·L^(-1)ethanol with a yield of 0.46 g·g^(-1)in the presence of 9 g·L^(-1)acetic acid,while the acetic acid/furfural-based adaptive strain SPSC01-TAF94 produced more ethanol of 36.2 g·L^(-1)with increased yield up to 0.49 g·g^(-1)in the presence of both 9 g·L^(-1)acetic acid and 4 g·L^(-1)furfural.Significant improvements were also observed during non-detoxified corn stover hydrolysate culture by SPSC01-TAF94,which achieved ethanol production and yield of 29.1 g·L^(-1)and 0.49 g·g^(-1),respectively,the growth and fermentation efficiency of acetic acid/furfural-based adaptive strain in hydrolysate was 95%higher than those of wildtype strains,indicating the acetic acid-and furfural-based adaptive evolution strategy could be an effective approach for improving lignocellulosic ethanol production.The adapted strains developed in this study with enhanced tolerance against acetic acid and furfural could be potentially contribute to economically feasible and sustainable lignocellulosic biorefinery.

Suppression of low-frequency ultrasound broadband vibration using star-shaped single-phase metamaterials

In order to suppress the low-frequency ultrasound vibration in the broadband range of 20 k Hz—100 k Hz,this paper proposes and discusses an acoustic metamaterial with low-frequency ultrasound vibration attenuation properties,which is configured by hybrid arc and sharp-angle convergent star-shaped lattices.The effect of the dispersion relation and the bandgap characteristic for the scatterers in star-shaped are simulated and analyzed.The target bandgap width is extended by optimizing the geometry parameters of arc and sharp-angle convergent lattices.The proposed metamaterial configured by optimized hybrid lattices exhibits remarkable broad bandgap characteristics by bandgap complementarity,and the simulation results verify a 99%vibration attenuation amplitude can be obtained in the frequency of20 k Hz—100 k Hz.After the fabrication of the proposed hybrid configurational star-shaped metamaterial by 3D printing technique,the transmission loss experiments are performed,and the experimental results indicate that the fabricated metamaterial has the characteristics of broadband vibration attenuation and an amplitude greater than 85%attenuation for the target frequency.These results demonstrate that the hybrid configurational star-shaped metamaterials can effectively widen the bandgap and realize high efficiency attenuation,which has capability for the vibration attenuation in the application of highprecise equipment.

Tailoring Ni based catalysts by indium for the dehydrogenative coupling of ethanol into ethyl acetate

Exploring stable and robust catalysts to replace the current toxic CuCr based catalysts for dehydrogenative coupling of ethanol to ethyl acetate is a challenging but promising task.Herein,novel NiIn based catalysts were developed by tailoring Ni catalysts with Indium(In)for this reaction.Over the optimal Ni0.1Zn0.7Al0.3InOx catalyst,the ethyl acetate selectivity reached 90.1%at 46.2%ethanol conversion under the conditions of 548 K and a weight hourly space velocity of 1.9 h^(-1)in the 370 h time on stream.Moreover,the ethyl acetate productivity surpassed 1.1 g_(ethyl acetate)g_(catalyst)^(-1)h^(-1),,one of the best performance in current works.According to catalyst characterizations and conditional experiments,the active sites for dehydrogenative coupling of ethanol to ethyl acetate were proved to be Ni4In alloys.The presence of In tailored the chemical properties of Ni,and subsequently inhibited the C-C cracking and/or condensation reactions during ethanol conversions.Over Ni4In alloy sites,ethanol was dehydrogenated into acetaldehyde,and then transformed into acetyl species with the removal of H atoms.Finally,the coupling between acetyl species and surface-abundant ethoxyde species into ethyl acetate was achieved,affording a high ethyl acetate selectivity and catalyst stability.

基于多层极限学习机的电能质量扰动多标签分类算法

电力系统中电能质量扰动分类特征选择标准不统一、泛化能力差、分类效果与分类效率有待提高。为了解决这些问题,一方面,引入多层极限学习机自编码器,优化输入权重,完成电能质量扰动信号的特征提取。另一方面,引入多标签排位分类算法,充分考虑各标签之间的相关性,完成电能质量扰动的分类。基于两种算法,设计出基于多层极限学习机的多标签分类模型,并得到多层极限学习机的最优网络结构和多标签分类的最佳分类阈值。实验结果表明,所提方法适用于电能质量单一扰动和复合扰动的分类,改善了分类效果和分类效率,具有较高的分类精度、良好的抗噪能力和泛化能力。

太子参白绢病病原菌的分离鉴定及生防菌筛选

【目的】太子参白绢病是一种可造成严重产量损失的土传病害。为有效防控病害,对其病原菌种类进行分离鉴定,并筛选有效生防菌。【方法】从具有典型白绢病症状的太子参植株和块根病样中,分离纯化获得病原菌;利用形态学、分子生物学和致病性测定进行病原菌鉴定;取代表性菌株用平板对峙法进行生防菌的筛选。【结果】病原菌的菌落呈圆形,菌丝为白色绢状辐射生长、有明显隔膜和分枝,后期有不同颜色的菌核形成;病原菌经ITS、LSU、TEF-1α等基因序列分析,确定为罗耳阿太菌Athelia rolfsii;致病测定发病症状与田间一致,符合柯赫氏法则。筛选获得对该病原菌具有良好抑制效果的生防菌贝莱斯芽胞杆菌FJAT-17931和暹罗芽胞杆菌FJAT-52595,抑菌率分别为73.23%和71.16%。【结论】鉴定出太子参白绢病的病原菌为A. rolfsii,筛选获得两株对该病原菌具有良好防效的生防菌,为太子参白绢病的防治提供依据。

耐海洋环境腐蚀燃机热障涂层材料研究进展

随着船用燃机的高速发展,其热端部件的服役工况日渐严苛,而现有的热障涂层体系在耐多介质热腐蚀和高温热力耦合稳定性等方面均遇到性能提升瓶颈,无法完全满足新一代船用燃机热端部件更严苛的防护需求。对海洋大气环境下服役的热障涂层用陶瓷基材料的环境适配性改进研究现状进行了总结,分析了船用燃机热障涂层的服役工况特点,并对稀土离子掺杂改性与纤维增韧等手段强化的氧化钇部分稳定氧化锆陶瓷基材料,以及多种新型热障涂层用陶瓷基材料在提高热循环寿命及耐腐蚀性能方面的研究进行了归纳,最后预测了未来船用燃机热障涂层用陶瓷基材料的发展趋势。

电刷镀镍–石墨烯复合镀层的制备及导热性能

采用电刷镀技术在45钢表面制备了镍-石墨烯(GE)复合镀层。镀液配方和工艺条件为:NiSO_4·6H_2O 220 g/L,CH_3COONH_4 40 g/L,(NH_4)_3C_6H_5O_7 45 g/L,GE 0.5 g/L,NH_3·H_2O 100~130 mL/L,十二烷基硫酸钠适量,pH 7.3~7.5,电压+12 V,镀笔速率10~12 m/min,时间5 min。采用扫描电镜(SEM)、能谱仪(EDS)、拉曼光谱仪、X射线衍射仪(XRD)和激光热导仪表征了Ni–GE复合镀层的微观结构、GE分布和导热性。与纯Ni镀层相比,Ni–GE复合镀层更致密,晶粒尺寸更小。复合电刷镀Ni–GE层的沉积速率(8.4μm/min)低于电刷镀Ni层的沉积速率(10.4μm/min)。Ni–GE复合镀层在25℃与100℃下的热导率较Ni镀层分别提高了11.5%和25.8%,导热性更优。

基于PCA和ML-ELM-AE的短期光伏功率预测

光伏发电系统输出功率受气象因素季节性和随机性的影响,表现出明显的间歇性和波动性。为了提高各种情况下的输出功率预测精度,提出了一种基于主成分分析和自编码结构多层极限学习机组合算法的预测模型。首先通过相关性分析明确影响输出功率的主要气象因素,然后根据相似日原则选取待测日的训练样本和测试样本,最后利用光伏电站历史气象数据和输出功率数据对预测模型进行训练和测试,验证预测方法的预测效果。实验结果表明,与反向传播神经网络算法和支持向量机算法相比,所提出的预测方法在不同季节和不同天气情况下均具有较高的预测精度,表现出良好的功率预测稳定性和泛化能力。

P型微晶硅在柔性太阳电池中的应用研究

以B(CH_3)_3为掺杂剂,采用正交实验法,以硅烷浓度、B(CH_3)_3掺杂比、反应压强及气体总流量等主要沉积参数为实验组变量,对P型微晶硅薄膜进行初步优化。在玻璃衬底上沉积厚度为80 nm左右的P型微晶硅(μc-Si:H)薄膜,通过测试材料暗态电导率、XRD、Raman等,研究了上述沉积参数对材料电学和微结构性能的影响,并在此基础上做进一步的参数优化,得到更高电导的微晶硅薄膜;将其应用于PEN衬底的非晶硅薄膜太阳电池中,得到6%的初始效率。

移动机器人的卡尔曼滤波定位算法改进与仿真

针对传统卡尔曼滤波算法和扩展卡尔曼滤波算法应用于移动机器人定位系统时出现的误差值较大和算法发散现象,在定位算法中引入修正因子对状态估计方程进行优化。分析传统卡尔曼滤波和扩展卡尔曼滤波的定位算法原理,研究运动过程中驱动力和摩擦力对移动机器人的影响,引入修正因子改进卡尔曼滤波算法,并对传统卡尔曼滤波算法、扩展卡尔曼滤波算法和改进算法做仿真对比和研究。仿真结果表明:修正因子对传统卡尔曼滤波算法和扩展卡尔曼滤波算法都具有改进效果,能提高定位精度。

资源获取与政治参与:张伯苓的角色困顿与抉择(1919-1946)

本文以张伯苓执掌私立南开大学时期(1919-1946)为例,考察并探讨他在办学历程中围绕办学资源获取而完成"教育人"到"政治人"的角色转变,以及由此引发的角色困顿与艰难抉择。张伯苓和南开的个案有助于理解近代中国私立大学在教育与政治的夹缝中生存的时代困境及其艰辛,张伯苓的角色困顿与抉择以及私立南开大学的发展境遇也是理解民国时期"教育独立"思潮的别样注脚。

准晶相含量对AlCuFe基涂层耐蚀性能影响机制

随着我国“海洋强国”战略目标日益推进,舰船表面使用的铝合金部件面临着海洋腐蚀的风险。为进一步提升铝合金的耐腐蚀性能,增长其使用寿命,通过爆炸喷涂技术于铝合金基体上制备AlCuFe和AlCuFeSc准晶涂层,借助扫描电子显微镜(SEM)、X射线衍射仪(XRD)表征准晶粉末及涂层的微观及物相组织结构,进一步利用拉伸试验机、电化学工作站等分析涂层的结合力及耐蚀性能,研究准晶相含量与涂层耐蚀性能间的影响规律。结果表明,爆炸喷涂制备的AlCuFe和AlCuFeSc涂层致密度高且与基体结合良好,结合强度分别为51.9MPa、51.2MPa。经700℃退火处理后的涂层准晶相含量分别由49%、38%提升至93.2%、92.5%。退火前的准晶涂层耐腐蚀性能与基体相近,退火后的准晶涂层自腐蚀电流密度仅为铝合金基体的1/5,证明准晶相含量提升增强了涂层的耐蚀性能。同时盐水静态挂片测试336 h后,退火处理的涂层表面未生成明显的腐蚀区域,准晶相含量提升促使表面生成的氧化铝钝化层为基体提供了良好的保护,研究可以为未来舰船使用铝合金表面的腐蚀防护提供新思路,同时也可为铝基准晶涂层的制备应用提供研究基础。

基于MI-PCA和ML-AE-ELM的脱硝系统入口NOx质量浓度预测

为提高脱硝系统入口氮氧化物(nitrogen oxide,NOx)质量浓度的预测精度,提出一种基于互信息的主成分分析(principal component analysis,PCA)和多层自编码结构的极限学习机(extreme learning machine,ELM)组合算法的预测模型。对输入变量的选取方式进行完善,并加入历史NOx质量浓度,对预测算法的网络结构进行优化。实验结果表明:与其他预测算法模型相比,该模型具有较高的预测效率,在不同工况下均具有较高的预测精度,表现出良好的抗噪能力和泛化能力。

中间层厚度对具有隧穿结构的叠层电池的影响

为了提高非晶硅/微晶硅叠层电池的转换效率和稳定性,在隧穿结构中引入ZnO∶B中间层,研究了中间层厚度对叠层电池短路电流密度、开路电压、转换效率等性能的影响。实验结果表明,较薄的中间层厚度,可以优化顶电池和底电池的短路电流密度,使微晶硅底电池生长致密,提高叠层电池的开路电压。采用厚度为60 nm的中间层,并优化顶电池和底电池的厚度后,制备出了初始转换效率为11.5%、衰退率在9%以内的叠层电池。

p型GaSb窗口层在热光伏电池中的应用研究

为了提高GaSb热光伏电池的转换效率,在电池结构中引入p^+-GaSb窗口层,研究了生长基底、衬底温度和反应物源温度对p^+-GaSb薄膜性能的影响,并优化了电池结构中p^+-GaSb窗口层的厚度和掺杂浓度。实验结果表明,生长基底和温度等制备参数影响着p^+-GaSb薄膜的结构特性和电学特性,而且,较薄的高掺杂p^+-GaSb层有利于提高电池性能。通过测试和仿真,热光伏电池的转换效率达到9.49%(AM1.5测试)和20.34%(AFORS-HET仿真)。

隧穿结对具有中间层的非晶硅/微晶硅叠层电池的影响

为了改善非晶硅/微晶硅叠层电池的载流子输运效果,将隧穿结引入到具有中间层结构的叠层电池中,研究了隧穿结的结构、掺杂浓度、厚度等条件对叠层电池性能的影响。实验结果表明,叠层电池中引入隧穿结构成"隧穿结-中间层"结构,可以进一步改善电池性能,经过结构和参数优化的隧穿结可以提高子电池的电流密度匹配度,提升叠层电池转换效率。加入"隧穿结-中间层"结构的叠层电池具有较高的转换效率和光照稳定性,并且得到了初始转换效率12.2%,光照衰退率9%的叠层电池。