Excellent Intrinsic Long-Term Thermal Stability of Co-Evaporated MAPbI3 Solar Cells at 85 °C

Thermal stability is a critical criterion for assessing the long-term stability of perovskite solar cells (PSCs). Here, it is shown that un-encapsulated co-evaporated MAPbI₃ (TE_MAPbI₃) PSCs demonstrate remarkable thermal stability even in an n-i-p structure that employs Spiro-OMeTAD as hole transport material (HTM). TE_MAPbI₃ PSCs maintain over ≈95% and ≈80% of their initial power conversion efficiency (PCE) after 1000 and 3600 h respectively under continuous thermal aging at 85 °C. TE_MAPbI₃ PSCs demonstrate remarkable structural robustness, absence of pinholes, or significant variation in grain sizes, and intact interfaces with the HTM, upon prolonged thermal aging. Here, the main factors driving TE_MAPbI₃ stability are assessed. It is demonstrated that the excellent TE_MAPbI₃ thermal stability is related to the perovskite growth process leading to a compact and almost strain-stress-free film. On the other hand, un-encapsulated PSCs with the same architecture, but incorporating solution-processed MAPbI₃ or Cs_0.05(MA_0.17FA_0.83)_0.95Pb(I_0.83Br_0.17)₃ as active layers, show a complete PCE degradation after 500 h under the same thermal aging condition. These results highlight that the control of the perovskite growth process can substantially enhance the PSCs thermal stability, besides the chemical composition. The TE_MAPbI₃ impressive long-term thermal stability features the potential for field-operating conditions.     

橡胶支座中橡胶板基于抗压弹性模量的寿命预测

橡胶板是橡胶支座的重要组成部分,对橡胶支座以及建筑物整体结构的稳定起着重要的作用。对橡胶板的使用寿命做出预测,提出更换周期,有助于工程做好更换计划。以抗压弹性模量对橡胶支座中占绝大部分的橡胶板分别作80℃,90℃以及100℃的加快老化试验。结果表明,在不考虑其它因素下通过阿伦尼乌斯方程拟合推导出橡胶板在年平均温度为23℃下的使用寿命在37．60 a之间。     

用改进Najar能量法分析混凝土单轴受压损伤特性

Najar能量法定义了损伤耗散能和无损应变能,并通过两者的比值确定了混凝土单轴受压情况下的损伤变量。该方法原理清晰,但不能在宏观上很好地描述混凝土单轴受压破坏的实际过程。针对此问题改进了Najar能量法,将混凝土受压过程中的弹性变形和塑性变形剥离开来,定义了一个新的损伤变量。为了对比分析改进前后的方法,进行了不同加载速率下的混凝土单轴压缩试验,并对试验数据加以拟合。以拟合后的试验数据为基础,分别利用改进前后的两种方法计算了混凝土受压过程中损伤变量,得到了改进前后损伤变量随应变变化的关系曲线。对比分析发现,改进后的Najar能量法在计算上更为简便,而且在宏观上更符合混凝土单轴受压的一般破坏规律。同时,这一关系曲线也反映了混凝土材料的应变率效应。     

护坡植物根系分布及抗拉力学特性

为了探讨草本植物根系固土的主要机制。以适宜的护坡植物白三叶、小冠花、黑麦草、早熟禾为研究对象,对它们的根系分布特征和抗拉特性进行研究。结果表明:随着土层深度的增加,禾本科植物的根长密度以指数函数形式逐渐减少,豆科植物的根长密度以多项式形式先增后减;随着距主茎距离的增加,禾本科植物根长密度逐渐减少,豆科植物根长密度先增后减;在根径0.1~3mm范围内,豆科植物平均抗拉力大于禾本科植物,豆科植物的抗拉力与根径呈幂函数关系,早熟禾和黑麦草的抗拉力与根径分别呈指数函数和对数函数关系;四种植物根系抗拉强度均表现为随根径的增加而减小;四种植物根系应力与应变关系表现为对数函数关系,表现为非线性弹性特征;根径相同时,不同植物的应力表现为:白三叶小冠花黑麦草早熟禾。运用主成分分析法综合分析其护坡特性,表现为豆科植物优于禾本科植物,其中白三叶的护坡效益最好。     

基于物理的植物形变和运动建模

研究植物体的材料力学特性,用材质参数可调的剪向弹性杆体、柔性线体及其组合对植物体建模。给出各模型在外力作用下的力平衡方程推导方法,模拟了典型植物体模型在风吹动下的状态,结合模型提出实现真实感植物体动画的方法。建模方法的有效性由模拟结果得到验证,具有简洁、计算量小、对不同植物体普适性强的特点。     

亚麻/聚丙烯机织复合材料薄板的制备与研究

本文以聚丙烯长丝作为基体,亚麻纱线为增强体,二者按一定体积含量进行捻合,形成合股纱,采用机织的方法织造亚麻/聚丙烯共织平纹布.选取五层平纹布进行层合热压,制备出亚麻增强聚丙烯(PP)热塑性复合材料薄板.对其拉伸性能进行测试,并分析破坏机理.     

The tensile properties of strain‐crystallizing vulcanizates. III. The superiority of conventional over peroxide vulcanizates in terms of network microstructure

It is proposed that, when vulcanization is performed using peroxides, crosslinking leads to a simple network, whereas in conventional vulcanization crosslinking a partially interpenetrating polymer network (PIPN) is formed. Two unfilled polyisoprene networks of similar crosslink density, produced with dicumyl peroxide and 2‐bisbenzothiazole‐2,2′‐disulfide/sulfur formulations, were compared with respect to the effect of strain rate on their stress–strain and hysteresis curves at room and elevated temperatures. At high elongations, the stress–strain curves for peroxide vulcanizates show a steeper upturn than for conventional vulcanizates, but have lower tensile strength and elongation at break. On increasing the extension rate, stress–strain curves for peroxide vulcanizates rise less steeply, while conventional vulcanizates rise more steeply. For both vulcanizates the hysteresis ratio decreases on increasing the rate at which samples are extended and retracted. The effect on conventional vulcanizates is less than on peroxide vulcanizates. It is suggested that chains in peroxide networks disengage increasingly rapidly at higher strains, allowing increased strain‐induced crystallization. Rapid strain‐induced crystallization leads to low ultimate tensile strength (UTS). In more complex PIPNs, the disengagement and alignment of chains are retarded. The increased nonuniform extension of chains promotes early strain‐induced crystallization at low extensions, but overall it reduces the rate of crystallization, which occurs over a wider range of strains. This improves UTS and elongation. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 876–884, 2006     

Effects of heat treatment on tensile properties of diacetate fibers

Diacetate filaments were heat‐treated (without tension or with tension) under dry‐heat or wet‐heat environment, respectively. The effects of temperature, time, and tension on tensile properties of diacetate fibers after heat treatments were discussed. The results show that diacetate fibers present no obvious improvement on its tensile properties after dry‐heat treatments without tension. It was also found that during dry heat treatments with tension, the increase in tensile properties of fibers mainly depends on temperature and tension. Moreover, being dry‐heat treated with tension instant after wet‐heat treatment without tension, diacetate fibers exhibit a higher improvement on its tensile properties comparing with dry heat method with tension. The shrinking measurement for the fibers indicates different supermolecular structures were developed in the fiber before treatment and after treatment, which leads to the different extent in the improvement of tensile properties for the fibers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101:787–791, 2006     

不同饱水强度灰岩应变特性及劣化损伤本构模型研究

为研究饱水强度作用下灰岩的物理力学特性,对不同饱水强度的灰岩试样进行单轴压缩试验,分析其典型的应力-应变特征,并基于损伤力学理论建立损伤本构模型。结果表明,饱水强度加剧了灰岩的软化效应,高强度饱水灰岩的压密阶段相对延长,而弹性变形阶段相对缩短;随着饱水强度的增加,灰岩峰值强度呈线性降低,但饱水作用未对灰岩的破坏类型造成较大影响,仍以剪切破坏为主;损伤本构模型曲线和试验曲线高度吻合,说明建立的损伤本构模型是可靠的;随着饱水强度的增加,灰岩脆性和强度弱化,参数m和F₀分别呈二次函数和三次函数降低。     

Co_(40)Fe_(40)B_(20)-SiO_2纳米颗粒膜中强单轴磁各向异性的起源探讨

采用磁控溅射工艺制备Co40Fe40B20-S iO2纳米颗粒膜;研究影响颗粒膜磁各向异性的主要因素;基于实验结果及其分析讨论,提出各向异性耦合模型,解释了CoFe基纳米颗粒膜中强单轴磁各向异性的起源问题,从而为更好地调控纳米颗粒膜的微波电磁性能提供了理论参考。