Improvement on the performance of perovskite solar cells by doctor-blade coating under ambient condition with hole-transporting material optimization

Numerous fabrication methods have been developed for high-efficiency perovskite solar cells(PSCs). However, these are limited to spin-coating processes in a glove box and are yet to be commercialized. Therefore, there is a need to develop a controllable and scalable deposition technique that can be carried out under ambient conditions. Even though the doctor-blade coating technique has been widely used to prepare PSCs, it is yet to be applied to high-efficiency PSCs under ambient conditions(RH ~45%, RT ~25 °C). In this study, we conducted blade-coating fabrication of modified high-efficiency PSCs under such conditions. We controlled the substrate temperature to ensure phase transition of perovskite and added dimethyl sulfoxide(DMSO) to the perovskite precursor solution to delay crystallization, which can facilitate the formation of uniform perovskite films by doctor-blade coating. The as-prepared perovskite films had large crystal domains measuring up to 100 μm. Solar cells prepared from these films exhibited a current density that was enhanced from 17.22 to 19.98 m A/cm^2 and an efficiency that was increased from 10.98% to 13.83%. However, the open-circuit voltage was only 0.908 V, probably due to issues with the hole-transporting layer. Subsequently, we replaced poly(3,4-ethylenedioxythiophene) polystyrene sulfonate(PEDOT:PSS) with Ni O x as the hole-transporting material and then prepared higher-quality perovskite films by blade-coating under ambient conditions. The as-prepared perovskite films were preferably orientated and had large crystal domains measuring up to 200 μm;The open-circuit voltage of the resulting PSCs was enhanced from 0.908 to 1.123 V, while the efficiency increased from 13.83% to 15.34%.

Revisiting Laws of Black Hole Mechanics and Violation of Null Energy Condition

Most of the important and powerful theorems in General Relativity such as singularity theorems and the theorems applied for null horizons depend strongly on the energy conditions. However, the energy conditions on which these theorems are based on, are beginning to look at less secure if one takes into accounts quantum effects which can violate these energy conditions. Even there are classical systems that can violate these energy conditions which would be problematic in validation of those theorems. In this article, we revisit to a class of such important theorems, the laws of black hole mechanics which are meant to be developed on null like killing horizons using null energy condition. Then we show some classical and quantum mechanical systems which violate null energy condition based on which the above theorem stands.

Effects of controlled pulse current waveform on key-holing condition in plasma arc welding

To overcome the shortcomings of conventional plasma arc welding （ PAW）, the ＇ controlled pulse key-holing＇ strategy is proposed and the keyhole PAW experiment system is developed. ＇The efflux plasma voltage signal is detected in realtime to characterize the keyhole size and dimension. The welding current waveform for controlled pulse key-holing strategy is implemented, and two slow-decreasing slopes are added at the dropping point from peak current to base current to further reduce both heat input and arc force so that the controllability of keyhole dynamics is improved. Two kinds of PAW tests are conducted, anti the different parameters of the controlled pulse current and the relevant efflux plasma voltage are measured in real-time to investigate ihe effects of welding current waveform parameters on the key-holing condition.

New black-to-white hole solutions with improved geometry and energy conditions

We construct new black-to-white hole solutions which connect the geometry of spacetime at some gluing surface inside the horizon.The continuity of the metric can be guaranteed up to the arbitrary order which is controlled by the power factor n.This sort of black-to-white holes is characterized by the sub-Planckian scalar curvature,independent of the mass of black-to-white holes.More importantly,we show that the energy condition is only violated within a small region near the gluing surface.The geodesics of particles within the region from black hole to white hole is also analyzed.It turns out that the matter falling into the black hole may pass through the center without singularity and come out from the white hole.This scenario provides novel ideas for understanding the information loss paradox in traditional black hole physics.

基于水平定向钻的城市燃气管道施工技术研究

由于城市燃气管道施工空间有限,因此施工难度较大,且施工过程会对城市道路基础产生很大的影响。基于此,文章提出基于水平定向钻的城市燃气管道施工技术。该技术通过水平定向钻施工准备、水平定向钻进、导向孔扩孔和管线回拖敷设,成功完成基于水平定向钻的城市燃气管道施工,在城市燃气管道工程领域具有良好的应用前景。

Exact Solutions for Piezoelectric Materials with an Elliptic Hole or a Crack under Uniform Internal Pressure

The existing investigations on piezoelectric materials containing an elliptic hole or a crack mainly focus on remote uniform tensile loads.In order to have a better understanding for the fracture behavior of piezoelectric materials under different loading conditions,theoretical and numerical solutions are presented for an elliptic hole or a crack in transversely isotropic piezoelectric materials subjected to uniform internal pressure and remote electro-mechanical loads.On the basis of the complex variable approach,analytical solutions of the elastic and electric fields inside and outside the defect are derived by satisfying permeable electric boundary condition at the surface of the elliptical hole.As an example of PZT-4 ceramics,numerical results of electro-elastic fields inside and outside the crack under various electric boundary conditions and electro-mechanical loads are given,and graphs of the electro-elastic fields in the vicinity of the crack tip are presented.The non-singular term is compared to the asymptotic one in the figures.It is shown that the dielectric constant of the air in the crack has no effect on the electric displacement component perpendicular to the crack,and the stresses in the piezoelectric material depend on the material properties and the mechanical loads on the crack surface and at infinity,but not on the electric loads at infinity.The figures obtained are strikingly similar to the available results.Unlike the existing work,the existence of electric fields inside an elliptic hole or a crack is considered,and the piezoelectric solid is subjected to complicated electro-mechanical loads.

Electro-elastic Fields of Piezoelectric Materials with An Elliptic Hole under Uniform Internal Shearing Forces

The existing investigations on piezoelectric materials containing an elliptic hole mainly focus on remote uniform tensile loads. In order to have a better understanding of the fracture behavior of piezoelectric materials under different loading conditions, theoretical and numerical solutions are presented for an elliptic hole in transversely isotropic piezoelectric materials subjected to uniform internal shearing forces based on the complex potential approach. By solving ten variable linear equations, the analytical solutions inside and outside the hole satisfying the permeable electric boundary conditions are obtained. Taking PZT-4 ceramic into consideration, numerical results of electro-elastic fields along the edge of the hole and axes, and the electric displacements in the hole are presented. Comparison with stresses in transverse isotropic elastic materials shows that the hoop stress at the ends of major axis in two kinds of material equals zero for the various ratios of major to minor axis lengths; If the ratio is greater than 1, the hoop stress in piezoelectric materials is smaller than that in elastic materials, and if the ratio is smaller than 1, the hoop stress in piezoelectric materials is greater than that in elastic materials; When it is a circle hole, the shearing stress in two materials along axes is the same. The distribution of electric displacement components shows that the vertical electric displacement in the hole and along axes in the material is always zero though under the permeable electric boundary condition; The horizontal and vertical electric displacement components along the edge of the hole are symmetrical and antisymmetrical about horizontal axis, respectively. The stress and electric displacement distribution tends to zero at distances far from the elliptical hole, which conforms to the conclusion usually made on the basis of Saint-Venant’s principle. Unlike the existing work, uniform shearing forces acting on the edge of the hole, and the distribution of electro-elastic fields inside and outside the elliptic hole are considered.

SOLUTION OF DIFFERENT HOLES SHAPE BORDERS OF FIBRE REINFORCED COMPOSITE PLATES BY INTEGRAL EQUATIONS

Accurate boundary conditions of composite material plates with different holes are founded to settle boundary condition problems of complex holes by conformal mapping method upon the nonhomogeneous anisotropic elastic and complex function theory. And then the two stress functions required were founded on Cauchy integral by boundary conditions. The final stress distributions of opening structure and the analytical solution on composite material plate with rectangle hole and wing manholes were achieved. The influences on hole-edge stress concentration factors are discussed under different loads and fiber direction cases, and then contrast calculates are carried through FEM.

A review of down-hole tubular string buckling in well engineering

Down-hole tubular string buckling is the most classic and complex part of tubular string mechanics in well engineering. Studies of down-hole tubular string buckling not only have theoretical significance in revealing the buckling mechanism but also have prominent practical value in design and control of tubular strings. In this review, the basic principles and applicable scope of three classic research methods （the beam-column model, buck- ling differential equation, and energy method） are intro- duced. The critical buckling loads and the post-buckling behavior under different buckling modes in vertical, inclined, horizontal, and curved wellbores from different researchers are presented and compared. The current understanding of the effects of torque, boundary condi- tions, friction force, and connectors on down-hole tubular string buckling is illustrated. Meanwhile, some unsolved problems and controversial conclusions are discussed. Future research should be focused on sophisticated description of buckling behavior and the coupling effect of multiple factors. In addition, active control of down-hole tubular string buckling behavior needs some attention urgently.

极端海况下风力机冲刷效应动力学响应研究

基于有限元方法建立考虑土-构耦合效应的壳单元模型,对不同海况下发生冲刷时的海上风力机进行动力学响应分析。结果表明:在常规和极端海况下,发生较大冲刷时,塔顶和桩基顶部峰值位移均有所增加,且桩基顶部峰值位移增幅更大,随着冲刷深度的增加,塔架水平位移均呈先增大后减小的趋势,桩基水平位移随冲刷深度的增加持续增大,不同冲刷深度下桩基最大加速度位置均发生在桩基顶部,塔架最大应力均出现在塔架底部;与常规海况相比,极端海况下风力机在启动后一直处于不稳定状态,最大加速度位于桩基中上部位置,且随冲刷深度的增加持续增大,桩基应力峰值位置由桩基顶部转移至中部。

Performance of a centrifugal compressor with holed casing treatment in the large flowrate condition

As demonstrated by former work,the holed casing treatment can be used to expand the stall margin of a centrifugal compressor with unshrouded impeller.In addition,the choked margin can also be expanded as experimental results indicated.Moreover,the compressor performance,especially the efficiency,on the whole working range is improved.As shown by experiments,the stall margin and choked margin of the compressor are extended,and the maximum efficiency improvement is 14%at the large flowrate of 1.386.Numerical simulations were carried out to analyze the flow in the impeller and in the holes in the case of large flowrate.The results indicate that in large flowrate conditions,there is a low-pressure region on the throat part of the impeller passage,leading to the bypass flows appearing in the holes,which means the flow area at the inlet of the impeller is increased.The bypass flow can also contribute to the decrease of the Mach number at the throat part near the shroud end-wall which implies that the choked margin is expanded.Besides,as the bypass flow would inhibit the development of the vertexes in the tip clearance and suppress the flow recirculation in the shroud end-wall region,both the pressure ratio and efficiency of the compressor are improved,which agrees well with the experiments.

基于专家知识和参数阈值的钻探孔内事故判别准则研究

在找矿突破战略行动中,钻探深度不断加大,智能化工况识别已成为钻探安全、高效、低成本钻进的必要措施。其步骤包括信号采集、特征提取、状态识别及诊断决策等。其中建立准确可靠的孔内事故判别准则是状态识别和诊断决策的难点和核心。本文首先基于孔内事故相关理论知识和工程实践经验,对钻探孔内埋钻、卡钻、烧钻、断钻、孔漏、孔溢6种事故类型作了细致划分,归纳总结了它们的发生征兆;对实时钻探信号参数特征及变化趋势表达方式进行了详细分析;在此基础上提出通过泵压、钻速、扭矩、转速、悬重、出口流量6个特征参数的相对均值、标准差、均值斜率、标准差斜率及它们的阈值来表征各参数的变化情况;最后采用矩阵的形式建立了事故判别准则。该判别准则具有较强的理论和实践基础,在实际使用时能够划分详细的钻探事故类别,可以为后续软件开发提供理论依据。

空调孔防渗漏缩径预埋及开合榫卯式节点处理施工技术研究

渗漏通病是建筑工程中难以治愈的顽疾,在我国外墙空调孔节点处理对改造工程及新建工程一直以来难以解决的问题,且未有细部的节点防渗、防潮处理方法。在常规的节点处理方法中,既有房建改造工程需对管线拆卸后方可进行处理。新建工程采用预埋PVC套管,后期安装后填充或配备结构及装饰保温一体板,工程多采用后期开孔,然后进行填充。几种工艺在封堵过程中,多数不能完全达到防渗、防潮的功效,不仅外观质量粗糙,施工工序复杂且安全风险较大,整体性较差,严重的会导致保温层进水,内部遇水受到破坏后引起脱落,另由于水分水汽的渗入,极易导致室内发霉结露,影响人们的生活品质。针对此项问题研发一种既适用于新建工程,亦适用于改造工程的空调孔节点防渗漏施工工艺。此工艺操作简捷,从根本上解决了渗漏的源头,提高了施工时的安全性,延长外墙保温使用寿命,保证了人们的生活舒适度。

Regular black holes with improved energy conditions and their analogues in fluids

On the premise of the importance of energy conditions for regular black holes,we propose a method to remedy those models that break the dominant energy condition,e.g.,the Bardeen and Hayward black holes.We modify the metrics but ensure their regularity at the same time,so that the weak,null,and dominant energy conditions are satisfied,with the exception of the strong energy condition.Likewise,we prove a no-go theorem for conformally related regular black holes,which states that the four energy conditions can never be met in this class of black holes.In order to seek evidences for distinguishing regular black holes from singular black holes,we resort to analogue gravity and regard it as a tool to mimic realistic regular black holes in a fluid.The equations of state for the fluid are solved via an asymptotic analysis associated with a numerical method,which provides a modus operandi for experimental observations,in particular,the conditions under which one can simulate realistic regular black holes in the fluid.

单孔抽水试验在岩溶场地中的运用

为了了解场地水文地质条件,确定含水层参数,为施工降水提供合理的水文地质资料。本文以遵义市新蒲新区某项目为例,对其项目基本概况和地质条件进行了分析和介绍,着重介绍了采用单孔抽水试验确定地下水参数。通过试验表明,单孔抽水试验能较准确地了解场地的水文地质条件,具有方法简便、成本低廉的优点。对于类似的勘察项目可参考应用。

基于循环神经网络的深孔钻削镗床刀具振动监测

为克服刀具状态监测缺陷,采集得到加工期间产生的振动以及声音等多种音频信号,通过平衡样本训练深循环神经网络(RNN)。利用深孔镗床开展模型验证,分析刀具状态的变化情况。研究结果表明:为实现模型监测效果的验证分析,利用深孔镗床完成模型的测试。测试结果达到了98.4%的准确率,获得了理想监测效果。相比较模糊PID与BP神经网络,采用循环神经网络进行处理时除了可以实现降噪功能以外还能够有效保留信号本身的有用信息。

钻孔胶囊封孔器封孔性能检测及其在水力压裂中的应用

目前,由于水力压裂封孔工艺复杂、封孔存在不严密以及封孔失效等问题,对钻孔胶囊封孔器耐压能力开展理论研究并进行现场实践。经过理论分析可知,钻孔直径减小,使封孔器能够承受更高的注水压力,其最大承受压力主要取决于它内部的水压。根据该结论开展胶囊封孔器封孔性能检测的缩胀实验,研究结果表明,聚氨酯橡胶胶囊封孔器膨胀性良好,75 mm以下的孔径均能紧密坐封,同时抗收缩性较好,在最大承载压力下长度变化率仅为25.3%,在收缩状态下能够满足有效封孔长度的要求。根据理论研究和实验结果,确定了胶囊封孔器参数并在某矿进行了顺层钻孔和定向长钻孔的水力压裂,取得了较好的封孔效果。

超高厚径比电镀加工技术研究

随着电子产品不断向着高集成度方向发展,印制电路板(PCB)设计呈现线路精细化,密集化,同时布线层数随之不断增加,板厚也越来越厚,孔径越来越小。厚径比从原来的20:1提升至50:1甚至更高,这对PCB制造工艺提出了更高的技术挑战。本文针对超高厚径比50:1(板厚6.5 mm,孔径0.13 mm)通孔电镀展开了研究。首先通过理论分析确定了浓差极化过电位和板面与孔内的电位差是影响深镀能力的主要因素,然后根据这些影响因素制定了最佳施镀条件(如:药水、设备、电镀参数等),以实现超高厚径比50:1的通孔电镀能力。

特殊条件下复合钢围堰施工技术研究

在已有研究基础上,针对钢板桩应用广泛但刚度较低、锁扣钢管桩刚度高但经济性差及止水难度大的特点,结合工程实例,针对围堰结构距水管过近、承台基坑较深且面积较大、河床地质结构复杂等特殊条件,对施工方案进行优化研究,创新性提出了钢管桩、钢板桩组合“8”字形围堰施工的技术。采用围堰钢管桩精确定位方法,开创性解决了围堰锁扣钢管桩间距控制难度大的问题;锁口内采用50%石粉+25%腻子粉+20%锯末+5%水泥的集配材料进行拌和填充,成功解决了钢管桩渗水问题;采用钢管桩、钢板桩接合“8”字型围堰的设计,大幅节省了钢管桩用量且克服了小间距承台围堰结构打架的难题,极大地提升了经济性与施工便捷性。该技术在东晓南路-广州南站连接线南段某工程中得到成功应用,各项指标合格率均为100%,取得了良好的经济效益,具有较好的推广与应用价值。

欠平衡钻井方式地层适应性研究

地层评价的不得当常常致使欠平衡钻井方式的选择不当,进而引起复杂情况及储集层的严重破坏;同时欠平衡钻井设备庞大、动迁费用高,也会造成经济上的重大损失。在大量的欠平衡钻井现场实钻资料统计基础上,提出了欠平衡钻井方式对地层适应性评价的内容和步骤,这对现场合理选择欠平衡钻井方式具有一定的参考意义。