二级倒立摆的建模与MATLAB仿真

通过对二级倒立摆结构构成及平衡控制问题的分析,给出基于牛顿力学定律的数学建模方法,并应用二次型最优控制理论实现二级倒立摆控制。根据MATLAB仿真结果表明,建模方法可行,采用二次型最优控制对系统进行控制,能满足控制系统稳定性、鲁棒性要求。     

Origin of Hole-Trapping States in Solution-Processed Copper(I) Thiocyanate and Defect-Healing by I2 Doping

Solution-processed copper(I) thiocyanate (CuSCN) typically exhibits low crystallinity with short-range order; the defects result in a high density of trap states that limit the device's performance. Despite the extensive electronic applications of CuSCN, its defect properties are not understood in detail. Through X-ray absorption spectroscopy, pristine CuSCN prepared from the standard diethyl sulfide-based recipe is found to contain under-coordinated Cu atoms, pointing to the presence of SCN⁻ vacancies. A defect passivation strategy is introduced by adding solid I₂ to the processing solution. At small concentrations, the iodine is found to exist as I⁻ which can substitute for the missing SCN⁻ ligand, effectively healing the defective sites and restoring the coordination around Cu. Computational study results also verify this point. Applying I₂-doped CuSCN as a p-channel in thin-film transistors shows that the hole mobility increases by more than five times at the optimal doping concentration of 0.5 mol.%. Importantly, the on/off current ratio and the subthreshold characteristics also improve as the I₂ doping method leads to the defect-healing effect while avoiding the creation of detrimental impurity states. An analysis of the capacitance-voltage characteristics corroborates that the trap state density is reduced upon I₂ addition.     

Mitigating Detrimental Effect of Self-Doping Near the Anode in Highly Efficient Organic Solar Cells

Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) has been one of the most established hole transport layers (HTL) in organic solar cells (OSCs) for several decades. However, the presence of PSS⁻ ions is known to deteriorate device performance via a number of mechanisms including diffusion to the HTL-active layer interface and unwanted local chemical reactions. In this study, it is shown that PSS⁻ ions can also result in local p-doping in the high efficiency donor:non-fullerene acceptor blends – resulting in photocurrent loss. To address these issues, a facile and effective approach is reported to improve the OSC performance through a two-component hole transport layer (HTL) consisting of a self-assembled monolayer of 2PACz ([2-(9H-Carbazol-9-yl)ethyl]phosphonic acid) and PEDOT:PSS. The power conversion efficiency (PCE) of 17.1% using devices with PEDOT:PSS HTL improved to 17.7% when the PEDOT:PSS/2PACz two-component HTL is used. The improved performance is attributed to the overlaid 2PACz layer preventing the formation of an intermixed p-doped PSS⁻ ion rich region (≈5–10 nm) at the bulk heterojunction-HTL contact interface, resulting in decreased recombination losses and improved stability. Moreover, the 2PACz monolayer is also found to reduce electrical shunts that ultimately yield improved performance in large area devices with PCE enhanced from 12.3% to 13.3% in 1 cm² cells.     

Ball-burnishing effect on deep residual stress on AISI 1038 and AA2017-T4

Ball-burnishing induces compressive residual stresses on treated materials by the effect of plastic deformation. The result is an increase in the fatigue life of the treated part, retarding the initiation of cracks on the surface. Compressive residual stresses have been previously measured by X-ray diffraction near the surface, revealing considerably high values at the maximum analyzed depth, in relation to other finishing processes such as shot peening. However, the maximum analyzed depth is very limited by using this technique. In this paper, the incremental hole drilling (IHD) technique is tested to measure residual stresses, being able to reach a 2-mm measuring depth. To that objective, a commercial strain gage is used and calibrated using finite element model simulations. A second Finite Element Model based on material removal rate is developed to obtain the equations to calculate the strain release through IHD. Finally, residual stresses are measured experimentally with that technique on two different materials, confirming that ball-burnishing increases the compressive residual stresses in layers up to 0.5?mm deep for the testing conditions, which is a good response to industrial needs. The method proves to be suitable, simple and inexpensive way to measure the value of these tensions.     

Weight function,stress intensity factor and crack opening displacement solutions to periodic collinear edge hole cracks

Periodic collinear edge hole cracks and arbitrary small cracks emanating from collinear holes, which are two typical multiple site damages occurred in the aircraft structures, are studied by using the weigh function method. An explicit closed form weight function for periodic edge hole cracks in an infinite sheet is obtained and further used to calculate the stress intensity factor and crack opening displacement for various loading cases. Compared to finite element method, the present weight function is accurate and highly efficient. The interactions of the holes and cracks on the stress intensity factor and crack opening displacement are quantitatively determined by using the present weight function. An approximate weight function method is also proposed for arbitrary small cracks emanating from multiple collinear holes. This method is very useful for calculating the stress intensity factor for arbitrary small cracks.     

煤矿硬岩巷道掘进大直径炮孔爆破试验研究

增大药卷直径可提高炸药爆速,配以较大直径炮孔爆破能够增强岩石的破裂和破碎。为了提高煤矿硬岩巷道掘进爆破效率,在液压凿岩台车施工巷道首次进行大直径炮孔和大直径药卷中深孔爆破试验研究,同时对各段雷管起爆延期时间进行优化,其中第2段雷管的延期时间由原先的25 ms增加至50 ms,目的是使掏槽爆破后岩石有足够的时间破碎、运动和抛掷出槽腔,形成新的自由面。并配用底部集能装药掏槽爆破技术和水垫层周边光爆装药结构,爆破试验取得了良好的效果。     

580 m长钢筋混凝土箱型拱桥爆破拆除

580 m长钢筋混凝拱桥需爆破拆除。大桥是钢筋混凝土建造,拱肋采用箱型截面的砼箱形拱桥,经多次加固,桥墩最大体积1200 m~3,桥面到墩角最高33 m,拱箱壁为薄壁结构。因传统钻爆方式无法有效破坏大桥结构,采用水压、深孔和浅孔爆破相结合的方式,将药包置于注满水的箱型拱肋内的设计位置上,以水作为传爆介质传播爆炸压力使拱肋破坏,从而达到破坏拱轴解除支撑的目的;对桥墩采用大孔径深孔,由桥面垂直钻孔一次性爆破解除;桥面、拱上结构等用浅孔爆破。大桥解体充分,空气冲击波、飞石及噪声等得到有效控制,也减少了后续出渣工作量。     

不同炮孔堵塞材料对矿山露天爆破效果的影响

通过矿山目前采用的单一材料堵塞的冲孔分析,利用控制变量法和对比分析法,定性地研究炮孔中应力和时间的变化规律,结合现场爆破试验,将炮孔堵塞分6种情况进行试验研究,最终得出:混合材料的炮孔堵塞相比单一材料的炮孔堵塞,具有抗剪强度高、炸药能量在炮孔中作用时间长和炸药做功能力增大等特点。现场混合材料堵塞能有效地降低冲孔现象的发生,提高炸药利用率和减少炮孔上部大块的产生。     

Ag纳米颗粒等离激元光散射增强对Si刻蚀形貌的影响机制

通过实验与有限元(FDTD)模拟系统研究了不同粒径尺寸的Ag纳米颗粒在P(100)Si表面刻蚀过程中等离激元光散射增强对刻蚀孔形貌的影响。SEM结果表明,刻蚀孔由与粒径尺寸接近的垂直孔演化为一种上大下小的火炬状形貌特征孔,该孔的直径与纳米颗粒尺寸散射半径相仿。模拟不同粒径的Ag纳米颗粒进入刻蚀孔后的光散射特征,证实了Ag纳米颗粒等离激元散射对刻蚀孔初期形成的重要作用。分析表明,基于光照条件下电子-空穴的激发特征,刻蚀孔的形貌主要依赖Ag纳米颗粒等离激元散射的光增强,即通过改变入射光频率以及Ag纳米颗粒粒径可以有效地调控Si表面形貌特征。Ag纳米颗粒等离激元光散射增强技术在Si基太阳能电池、发光二极管(LED)器件等领域有潜在应用前景。     

钙钛矿太阳能电池空穴传输材料的研究进展

钙钛矿太阳能电池具有工艺简单、可弯曲、应用前景广阔等优点。从2009年出现起,至今其效率从3.8%提高到了22%以上,引起了研究者的广泛关注。介绍了钙钛矿太阳能电池的基本结构和工作原理,概述了钙钛矿太阳能电池空穴传输材料的研究进展,着重介绍了无机空穴传输材料的研究进展。最后展望了钙钛矿太阳能电池未来的发展与商业化应用。