Enhanced Efficiency of Metamorphic Triple Junction Solar Cells for Space Applications

Metamorphic In0.55Ga0.45P/In0.06Ga0.94As/Ge triple-junction （3J-MM） solar cells are grown on Ge （100） sub- strates via metal organic chemical vapor deposition. Epi-structural analyses such as high resolution x-ray diffrac- tion, photoluminence, cathodoluminescence and HRTEM are employed and the results show that the high crystal quality of 3J-MM solar cells is obtained with low threading dislocation density of graded buffer （an average value of 6.8× 10^4/cm2）. Benefitting from the optimized bandgap combination, under one sun, AM0 spectrum, 25℃ conditions, the conversion efficiency is achieved about 32%, 5% higher compared with the lattice-matched In0.49Ga0.51P/In0.01Ga0.99As/Ge triple junction （3J-LM） solar cell. Under 1-MeV electron irradiation test, the degradation of the EQE and I-V characteristics of 3J-MM solar cells is at the same level as the 33-LM solar cell. The end-of-life efficiency is -27.1%. Therefore, the metamorphic triple-junction solar cell may be a promising candidate for next-generation space multi-junction solar cells.

Modeling and Simulation of a Bonding Process for Space Solar Cells

A bonding process for space solar cells implemented by an automated coating and bonding system was theoretically investigated for future parametric studies to achieve better bonding quality. First, the mechanical properties of silicone adhesive and the vacuum suction cup were experimentally analyzed. Based on the constitutive relationship of four parts in the bonding process, the dynamic bonding process was modeled systematically, and numerically simulated by a commercial finite element analysis code, Adina. The final bonding edge-alignment error and the thickness and uniformity of the adhesive layer were obtained from simulation and validated by experiments. A simulation platform was created for predicting the final bonding quality via adjusting bonding parameters when dimensions of the solar cells and adhesive were changed.

Development of the Automated Bonding Robot for Space Solar Cells

The bonding process of space solar cells is a very complicated task undertaken by manual labor before.An automatic approach based on robot technology is presented to deal with the difficult problem.The architecture of the bonding robot for space solar cells is described.The two processes carried out by the robot,adhesive dispensing and cover-glass bonding,are studied.Based on the mechanical model,the flow velocity field of the adhesive in needles is obtained and the cover-glass bonding theory is interpreted.According to the studies,the thickness of the adhesive can be controlled accurately by robot and bubbles can be avoided coming about inside the adhesive.

Transplantation of autologous peripheral blood mononuclear cells in the subarachnoid space for amyotrophic lateral sclerosis:a safety analysis of 14 patients

There is a small amount of clinical data regarding the safety and feasibility of autologous peripheral blood mononuclear cell transplantation into the subarachnoid space for the treatment of amyotrophic lateral sclerosis.The objectives of this retrospective study were to assess the safety and efficacy of peripheral blood mononuclear cell transplantation in 14 amyotrophic lateral sclerosis patients to provide more objective data for future clinical trials.After stem cell mobilization and collection,autologous peripheral blood mononuclear cells（1 × 109） were isolated and directly transplanted into the subarachnoid space of amyotrophic lateral sclerosis patients.The primary outcome measure was incidence of adverse events.Secondary outcome measures were electromyography 1 week before operation and 4 weeks after operation,Functional Independence Measurement,Berg Balance Scale,and Dysarthria Assessment Scale 1 week preoperatively and 1,2,4 and 12 weeks postoperatively.There was no immediate or delayed transplant-related cytotoxicity.The number of leukocytes,serum alanine aminotransferase and creatinine levels,and body temperature were within the normal ranges.Radiographic evaluation showed no serious transplant-related adverse events.Muscle strength grade,results of Functional Independence Measurement,Berg Balance Scale,and Dysarthria Assessment Scale were not significantly different before and after treatment.These findings suggest that peripheral blood mononuclear cell transplantation into the subarachnoid space for the treatment of amyotrophic lateral sclerosis is safe,but its therapeutic effect is not remarkable.Thus,a large-sample investigation is needed to assess its efficacy further.

Silicon Solar Cell Space Charge Region and Capacitance Behavior under Electric Field

This paper investigates theoretically the behavior of the space charge region of a silicon solar cell and its associated capacitance under the effect of an external electric field. The purpose of this work is to show that under illumination the solar cell’s space charge region width varies with both operating point and the external induced electric field and how the solar cell capacitance varies with the space charge region width. Based on a 1D modelling of the quasi-neutral p-base, the space charge region width is determined and the associated capacitance is calculated taking into account the external electric field and the junction dynamic velocity. Based on the above calculations and simulations conducted with Mathcad, we confirmed the linear dependence of the inverse capacitance with space charge region width for thin space charge region and we exhibit an exponential dependence for large space charge region.

面向空间细胞培养用多路切换陶瓷阀仿真优化研究

为了满足空间站环境细胞长期自动培养的需求,研制一款新型细胞自动培养装置,装置由微量泵、多路切换阀等组成。通过设计一款多路切换陶瓷阀,实现仅由一组泵阀自由切换多条液路。通过有限元仿真分析培养液、消化液和裂解液3种液体在多路切换阀内的压力、温度、流速等物理参数分布情况,确定最佳阀位布局,并优化阀体结构,以改善不同液体流入阀腔后分布均匀性。优化后多路切换阀内细胞培养液和消化液的压力和温度分布波动率均小于1%,流速稳定。裂解液温度分布变化在优化前为2℃,优化后小于0.01℃。液体流动更加顺畅,滞留现象减少。仿真结果表明:优化后的陶瓷阀有助于提升空间细胞培养的稳定性和经济性。

针对组网雷达的无人机集群转发式欺骗干扰时延误差研究

在现代战争中,利用无人机集群对敌方组网雷达进行欺骗干扰作为一种有效对抗手段受到了广泛应用。然而,面对复杂作战环境,无人机集群搭载的数字存储转发设备因其精度受限而存在转发时延误差,这将导致实际生成的虚假目标点和预设虚假目标点产生偏移,使欺骗效果大打折扣。针对此问题,本文在组网雷达站址及其射频辐射参数等信息先验已知的情况下,基于“同源检验”思想,在组网雷达空间分辨率一定时,分析了数字存储转发技术对组网雷达进行有效欺骗干扰的边界条件,并针对典型组网雷达系统,探明了转发延迟误差与欺骗干扰效果的影响规律。仿真结果表明,分析和推导的结果能够对实际干扰机性能可否对组网雷达实施有效欺骗干扰给出可行性判定。

模拟空间相关环境下神经胶质细胞外泌体的可视化快速检测

目的探讨模拟空间环境下神经胶质细胞外泌体的可视化快速检测方法。方法通过2 Gy、5 Gy辐照,12h、24 h微重力的处理方式,建立模拟空间环境下神经胶质细胞的损伤模型,将条件培养基和试剂盒提取的外泌体转移至神经元,明确神经胶质细胞对神经元产生的影响。通过膜嵌入型荧光染料分子对外泌体进行活细胞荧光标记,以荧光强度为指标对条件培养基中的外泌体释放规律进行可视化监测。探究不同保存条件、保存时间对外泌体的数量和粒径的影响。结果首先,本实验证实模拟空间环境下受损胶质细胞释放的胞外囊泡可在一定程度上保护神经元,而外泌体在这一过程中发挥决定性作用,并确定神经系统外泌体可视化检测方案与传统外泌体验证方案的结论一致;其次,本实验建立了可用于半定量分析的外泌体数量和粒径经验曲线,为细胞培养基中外泌体的快速检测提供了新思路。最后,本实验明确了培养基样本的最佳保存条件,为航天飞行后培养基样本的地基/天基在线分析奠定了基础。结论通过荧光标记可实现外泌体的快速检测和分析,并用于模拟空间环境下神经胶质细胞损伤的探究。

咽旁间隙基底细胞腺瘤的MRI表现

目的:探讨咽旁间隙基底细胞腺瘤的临床特征及MRI征象,增加对该病的认识。方法:回顾性分析6例经过手术或穿刺病理证实的咽旁间隙基底细胞腺瘤,对其临床及影像学资料进行总结。结果:6例患者中,男性1例,女性5例,年龄43~89岁,中位年龄64岁;最大径平均约3.2 cm。病灶边界清晰,形态规则,咽旁脂肪间隙向内受压移位,“C”形朝外。所有病例均伴有囊变,其中1例合并少许出血。增强扫描肿瘤实性成分表现为明显持续强化。结论:中老年女性患者发现茎突前间隙的形态规则、边界清晰伴有囊变的良性肿瘤,要考虑到BCA的可能。

空间等离子体环境对高压太阳电池静电放电特性研究

随着3D打印等新技术的空间应用,新一代航天装备对能源系统的功率需求将日益增加。运行于低地球轨道航天器将面临低能高密度等离子体环境,导致高压太阳电池阵产生静电放电效应。通过模拟低轨道等离子体环境特点,测试了不同等离子体能量、密度以及电池偏置电压下高压太阳电池静电放电试验,揭示了等离子体参数对放电特性的影响规律。研究结果显示,当高压太阳电池的偏置电压达到-70 V时,静电放电现象开始显现,并且随着偏置电压幅值的增加,静电放电频次也相应增多。此外,空间等离子体的密度越大,越容易诱发静电放电,而轨道等离子体的能量对静电放电次数的影响则相对较小。

Mechanical properties of multi-scale germanium specimens from space solar cells under electron irradiation

During long-term service in space,Gallium Arsenide(GaAs)solar cells are directly exposed to electron irradiation which usually causes a dramatic decrease in their performance.In the multilayer structure of solar cells,the germanium(Ge)layer occupies the majority of the thickness as the substrate.Due to the intrinsic brittleness of semiconductor material,there exist various defects during the preparation and assembly of solar cells,the influences of which tend to be intensified by the irradiation effect.In this work,first,Ge specimens for mechanical tests were prepared at scales from microscopic to macroscopic.Then,after different doses of electron irradiation,the mechanical properties of the Ge specimens were investigated.The experimental results demonstrate that electron irradiation has an obvious effect on the mechanical property variation of Ge in diverse scales.The four-point bending test indicates that the elastic modulus,fracture strength,and maximum displacement of the Ge specimens all increase,and reach the maximum value at the irradiation dose of 1×10^(15)e/cm^(2).The micrometer scale cantilever and nanoindentation tests present similar trends for Ge specimens after irradiation.Atomic Force Microscope(AFM)also observed the change in surface roughness.Finally,a fitting model was established to characterize the relation between modulus change and electron irradiation dose.

MC-NAS:一种可视化模块贡献神经架构搜索方法

现有的神经架构搜索方法无法直观地将网络模型与候选模块以及模型识别准确率之间的关系展示出来;同时很多NAS方法可扩展性差,无法将其搜索策略扩展至任意搜索空间。针对上述挑战,提出了一种可视化模块贡献神经架构搜索方法。提出了模块贡献这个概念,并通过分析贡献计算过程的窘境给出了任意搜索空间下的统一采样原则,利用统一的贡献度指导原则给出了不同搜索空间的贡献度计算策略。针对特定的约束条件通过动态网络规划算法生成神经网络体系结构。大量的实验结果表明该算法在任意搜索空间中的有效性。使用CIFAR-10、CIFAR-100和ImageNet16-120数据集在NAS-Bench-201基准测试上平均准确率达到了93.33%、71.07%、42.69%。

卫星辅助的去蜂窝大规模MIMO通感一体化系统

为了应对未来通信系统中物联网业务和数据业务需求的激增,以及通信与雷达频谱重叠导致的资源紧缺问题,同时提高系统容量和降低感知网络部署成本,卫星技术被认为是通信与感知一体化系统的有效辅助手段。对卫星辅助的去蜂窝大规模MIMO通感一体化系统架构进行深入研究,通过阐述信号处理流程,重点分析其通信性能,并利用仿真实验比较不同密集化部署和网络负载条件下的用户下行平均速率,验证了该系统有着比单纯地面去蜂窝大规模MIMO系统更优越的性能,为后续的星地融合通感一体化系统设计提供了指导和参考。

质子交换膜燃料电池气体扩散层研究进展

质子交换膜燃料电池(PEMFC)可以提供较高的功率/能量密度,是未来空间探索最有前途的动力设备之一,其性能主要取决于内部反应物的传输和水管理。气体扩散层(GDL)作为燃料电池中的重要组成部件,与燃料电池的质量、水、热和电的多相传输紧密相关,是反应物和液态水的主要传输场所。因此,要提高燃料电池性能,合理的气体扩散层的设计至关重要。从提升空间燃料电池的使用寿命、稳定性及电化学性能的角度出发,综述了气体扩散层的物理化学特性,并介绍了多种改性方法,包括疏水性、结构和新型一体式GDL以及其对燃料电池性能的影响,为未来空间燃料电池高性能GDL设计提供了参考。

空间受限对航空发动机室内试车台的气动影响

室内试车是航空发动机研制的关键试验手段之一。试车台空间受限等诸多实际因素使得被试发动机周围气动环境偏离理想条件,导致直接测量推力中包含有附加气动力等误差。针对墙壁及排气管形成的空间约束建立室内试车台简化几何模型,运用数值模拟方法分析空间约束对发动机近周流场的影响,并结合理论分析方法研究关联流动特征变化形成的附加气动力。

国外空间太阳电池阵先进制造技术综述

为达到经济、科学、军事等领域的深层次发展,近年来,世界先进航天强国在卫星系统建设方面纷纷展开竞争。空间太阳电池阵作为卫星唯一在轨能量来源,以SpaceX为代表的众多公司均对其需求量呈现井喷式增长,在运用机器人、先进检测技术之外,国外空间太阳电池阵研制厂商也在通过大数据采集应用、数字孪生等先进辅助制造技术进行太阳电池阵智能化研制模式升级,以满足卫星整体批量化发射要求。

单晶钙钛矿太阳能电池研究进展

单晶半导体(如硅、锗和砷化镓)在太阳能电池领域展现的光电转换效率要普遍优于多晶薄膜。然而,基于ABX3新型有机-无机杂化金属卤化物钙钛矿材料构建的第三代太阳能电池中,其>26%的最高认证效率是基于多晶薄膜实现的。目前,单晶钙钛矿太阳能电池最高效率约为24%,且相关研究较少。多晶钙钛矿薄膜存在着高密度的固有结构缺陷(如晶界、空位缺陷、杂质缺陷、反位缺陷等),会导致太阳能电池器件稳定性弱和严重迟滞效应等问题。相比之下,钙钛矿单晶具有无晶界、低缺陷密度、长载流子寿命和扩散距离等优势,这些特性使得钙钛矿单晶成为高性能光电子器件的理想优选材料。本综述简述钙钛矿单晶太阳能电池的基本器件结构,系统综述不同组分构成的钙钛矿单晶材料的优势/劣势,同时探讨不同单晶钙钛矿材料的制备/生长方法,细致分析其最新的研究进展和关键攻关方向,重点强调单晶钙钛矿材料组分、器件结构、生长工艺与器件性能之间的关系。希望本综述能为促进研究人员开发高效与高稳定钙钛矿单晶太阳能电池提供借鉴。

空间氢氧燃料电池技术发展现状与趋势分析

针对空间应用场景下的能源需求,对空间氢氧燃料电池技术现状和发展趋势进行分析,总结国内外在空间氢氧燃料电池发电技术的发展趋势,面向利用液氢液氧推进剂的一次燃料电池以及月面可再生电池应用场景,对多种空间电源技术方案进行对比,发现空间氢氧燃料电池在运载火箭上面级推进剂利用、月面探测能源系统、月球原位资源利用、长时间月面驻留等应用场景具有较高潜力。通过分析空间应用场景下氢氧燃料电池电源系统特点,对未来空间氢氧燃料电池技术发展趋势,空间氢氧燃料电池技术发展方向提出展望。

城市绿色空间对青少年心理健康的影响:性别和手机娱乐时间的调节作用

本研究探讨了城市绿色公共空间,尤其是公园广场对青少年心理健康的影响,并着重分析了性别差异以及手机娱乐时间的调节作用。研究基于对广州市472名中学生问卷收集的数据,包括居住地、学校周边、工作日和休息日活动路径空间4种不同地理背景,建立回归模型。研究结果显示,绿色空间对青少年心理健康具有显著正向影响,居住地周围影响最大,其次是工作日活动路径、再次是休息日活动路径,学校周围影响最小。绿色空间对男生和女生的心理健康效应在不同的地理背景下表现出明显的差异,对男生在居住地周围和工作日活动路径的心理健康效应高于女生,而对女生在休息日活动空间路径的效应高于男生。手机娱乐时间的增加会抑制绿色空间的心理健康效应,对女生在居住地周围的抑制效应高于男生,对男生在休息日活动路径的抑制效应高于女生。建议可以从增加绿色空间、限制手机娱乐时间以及考虑性别敏感的干预措施3个维度促进青少年心理健康。

一种非对称特性约束的碰撞振动系统的动力学分析

该文研究了一种具有非对称约束的单自由度非对称碰撞振动系统。在对系统进行无量纲化建模处理后分析了系统的n-1-1周期运动的存在条件。在此基础之上推导了系统在n-1-1周期运动的情况下的Jacobi矩阵,利用参数状态空间联合仿真的方法分析了系统在参数平面(ω,δ)下系统的转迁规律以及变化参数ω时的动力学行为。提出了一种参数空间变化下探索吸引子共存现象的新方法,并分析了系统在状态空间下吸引子的演化趋势。